Focus: Direct offset printing on corrugated board · Focus: Direct offset printing on corrugated...

Focus: Direct offset printingon corrugated boardDirect printing on corrugated board isstill a quite new process, but neverthelessone which already brings significanteconomic benefits, e.g. for packagingproduction. Thanks to the joint develop-ment activities undertaken by KBA, aspress manufacturer, together withnumerous industry suppliers, the resultsand processing quality of direct printingon the most varied corrugated materialshave reached such a high level, thatthere are now practically no differences

in quality to be seen in comparison withstandard print on paper or board. Inthis special issue of our user magazine"KBA-Process" we would like to presentyou some of the design details thanks towhich the Rapida sheetfed offset pressesare able to achieve such exceptionalresults in the direct printing of corrugatedboards. Equally important aspects are thediverse auxiliary systems and materials,which contribute essentially to the processcapabilities, reliability and quality.

Issue 1/2002

1No.

Foreword 1

Rapida technologyFrom feeder to infeed 2The design principle of the printing units 4Washing systems 6Stability for the print process 8

Coating technologyCoating tower 10

Dryer and delivery conceptAir Clean System 13Eltosch: Inert UV 14Grafix: UV drying with hybrid inks 16

LogisticsLogistics in the press room 18

Workflow and control technologies Logotronic professional 20Densitronic S 22

Media and materialsEichhorn: Potential for corrugated materials 24ContiTech: Conti-Air Prestige 26Flint-Schmidt:Printing inks for corrugated board 28Huber group: Low-odour inks 30Huber group: Pearlescent effects 32Vegra: Barrier coatings for food packaging 34SunChemical Hartmann:Packaging printing + varnish 36

Hybrid inksEpple:Hybrid inks 38Böttcher:Hybrid resistance tests 40KBA: Hybrid double-coating process 42KBA: Hybrid double-coating profitability 45

Contents

Foreword

1

Dear customers and business friends,

Packaging printing has always been a central focus of the sheetfed offset activities and innovationsat the Radebeul works of Koenig & Bauer AG. The enormous faith placed in our Rapida sheetfedoffset presses and in our further developments for the print process by countless packaging printersaround the world documents KBA's unique standing in this extremely important market segment.

We know that, despite the permanently growing demand for modern packaging, the competitionfacing our partners in the industry is today fiercer than ever and that they are thus particularly interested in future-oriented and economical print and refinement solutions. Together with renownedindustry suppliers and a circle of innovation-oriented users, we have taken up this challenge withenthusiasm and determination.

For print industry insiders, it is almost certainly no great surprise that KBA is cooperating with numerous partners to develop a solution answering the specific needs of printers in this branch ofour industry. With a practically universal packaging printing press, in combination with flexibleauxiliary equipment and materials, we would like to fulfil longstanding wishes from this sector ofthe market.

Packaging, irrespective of the material used, is becoming an ever more important advertising vehicle for brand-name products. The demands placed on print quality and inline refinement options, such as high-gloss and decorative matt finishes (with both UV and water-based varnishes),are increasing constantly. At the same time, nevertheless, the general call from print customerseverywhere is for significant cost savings.

In a consumer society characterised by an absolute flood of visual stimuli, packaging must not only provide attractive and safe protection for its contents, it must also communicate essential information about the enclosed product to potential buyers, often within just a fraction of a second.The appearance of the packaging is a decisive factor influencing the customers' buying decisions.

With this new technical journal "KBA Process", we are initiating a worldwide dialogue amongprocess technology specialists from the print and printing supplies branch. Our aim is to presentusers and their customers information on what is possible today in the print business, and above all how to implement this potential. The restrictions of space, unfortunately, mean that we can only include contributions from a limited number of suppliers in our "KBA Process". The absence of an individual supplier, therefore, is in no way intended to signal lesser competence.

We would like to thank all our development partners and hope that this "KBA Process" will also inspire new ideas and packaging solutions. As always, we look forward to your feedback. Afterall, partnership and cooperation between press manufacturers, printing suppliers and users bringbenefits for all concerned.

Yours,

Andreas Mößner Jürgen VeilDirector for Sheetfed Offset Sales Head of Sheetfed Offset Marketing

E-mail: [email protected]

Andreas Mößner

Jürgen Veil

Issue 1/2002 KBA Process

2

From feeder to infeed

All features of the feeders and infeeds for the Rapida sheetfedoffset presses are designed to permit substrate changes – evenchanges from very thin to extremely thick materials – to beperformed without the need for manual adjustments in all buta few exceptional cases. Most setting changes are carried outautomatically and remotely via the Ergotronic control console.

Ultimate substrate flexibility from the very beginning

Feeder and infeed

One new development is theso-called four-axis sheet feederof the Rapida presses. Dedicat-ed electronic drives take careof all necessary motions:

• Drive for the feed table with belt deceleration

• Drive for the feeder head• Drive for the main pile

with intelligent continuouspile lift

• Drive for the auxiliary pile(for non-stop operation) with intelligent continuouspile lift

All these drives operate withoutthe previously indispensablemechanical link to the drive ofthe press itself. The electroni-cally controlled pile motorsensure a constant pile heightrelative to the feeder head withno differences due to steppingintervals. The pile lift, at thesame time, is much smoother –also at the point of pile reunionin both standard and fully auto-matic non-stop operation. Withthe electronically controlleddedicated drives, furthermore,components susceptible to wear,such as timing gears, cardanshafts, belt drives, etc., arerendered superfluous.

High piles for thickersubstrates

The standard feeder pile heightis already 1.3 m for the RAPIDA105 and 1.5 m for the large-format Rapidas. For printers ofheavy board or corrugatedmaterials the presses can beraised by a further 37 or 60 cm,which provides for pile heightsof up to 1.8 m for the RAPIDA105 and over 2 m for the large-format models. The 37 cmhigher version of the RAPIDA105 is even able to forgo acapital-intensive special foun-dation. Standard and fully auto-

matic non-stop facilities providefor uninterrupted production.The fully automatic non-stopfeeder is able to unfold its fullpotential in conjunction withautomatic pile logistics.

Double-sheetdetection

The Rapida sheetfed offsetpresses are equipped with threedifferent double-sheet sensors.The ultrasonic double-sheetdetector is an ideal choice forpractically the whole range ofsubstrates from paper to board,metallised stocks and evenplastic materials. A capacitivesensor is preferred for thickersubstrates such as multi-plyboard. The third alternative, anoptical double-sheet system,handles a wide spectrum ofsubstrates from paper to corru-gated board. Simple switchingvia the console menu screenfor format settings activatesthe most favourable double-sheet detection system for thepresent substrate.

One infeed system for all eventualities

No manual adjustments arerequired at either the side orfront lays for even the mostextreme substrate changes. Thevacuum-operated side layeliminates mechanical stresson the sheets and with it therisk of damage. Unlike othersystems, there are no parts tobe exchanged. Nevertheless, aspecial side-lay with an en-larged suction area is availablefor extremely heavy materials.Options for central setting ofthe front lay cover height,skew correction of the infeedline and parallel variation ofthe print-free gripper marginfurther enhance the operatingcomfort at the infeed. Rollersheet guides are used to improvethe transport of rigid substrates

Four electronically controlled motors drive all functions of the feeder and belttable. This eliminates the cardan shaft between the press and feeder, alongsidevarious other wear-prone components.


3

From feeder to infeed

Suction-belt feed table with individually controlled vacuum chambers. The optional automatic non-stop rake is housed under the feed table.

Sheet infeed via swing arm and feed drum (RAPIDA 105) or Vari-Speed drum (large formats)

The vacuum side lay aligns each sheet precisely before it is fed into the press,whether paper or corrugated board.

The console menu screen "Sheet travel configuration" is used not only to set the format lengthand width, but also to preselect the double-sheet system appropriate to the substrate type.

such as heavy board, corrugatedsheets or plastic materials. Aguide shaft assists precisetransfers of the sheets into thepress. This guide shaft lifts anddips in line with the press speedso as not to hinder the actualpassage of the sheets and canalso be deactivated altogetherfor the processing of highlysensitive substrates.

Another safety device at thepress infeed is the crash barwith a tilting plate to hold backsticking sheets or like beforethey even reach the infeed.Magnets retain any metallicforeign bodies.

Smooth acceleration

The infeed maintains the widelyproven principle of a swing armoperating from below, combinedwith timed pneumatic andmechanical sheet guiding ele-ments for reliable and scratch-free feeding of the sheets intothe press. The sheets are trans-ferred from the swing grippersto the first impression cylindervia a feed drum. On the large-format Rapidas this drum isdesigned as a so-called Vari-Speed drum. The resultant two-stage acceleration of the sheetto full press speed is especiallygentle on the sheets. The wholeinfeed system is extremelyrobust and can be characterisedby its pronounced ease of ad-justment.

A dust extraction system enablesunwanted paper dust or powderto be removed from the sheetsurface, whereby the conven-tional extraction equipment iscombined with dedicated sheetguide elements to guarantee thefull efficiency of the systemacross the widest possible sub-strate range.

Further information can be requestedby phone on +49-(0)351/833-2580 or by e-mail from [email protected]


4

Substructure

The monolithic substructure boxframe is the central guaranteefor the outstanding rigidity ofthe printing units.

Unlike press frames which areformed by bolting togetherseveral individual elements, thistechnology is able to withstandeven the enormous forces arising

in the heavy board branch withno distortion whatsoever.

After assembly, the direct, tightjoints between the Rapida sub-structures mean that the wholepress is effectively a singletorsionally rigid block, whichstands on the foundation andcarries the printing towers. Withthe presses of the KBA Rapidaseries we can thus differentiatebetween a superstructure with theinking and dampening units anda substructure for sheet travel.

The impression cylinders andtransfer systems are carried inplay-free bearings in the wallsof the substructure box frames.This design principle enablesthe press to run vibration-freeand secures maximum registeraccuracy even at the highestproduction speeds.

The modular structure of theunits, furthermore, permits

The design principle of the printing units

The frames of the Rapida presses, which all follow the unit-designprinciple, comprise a one-piece cast substructure with inking unittowers mounted directly over the joints.

Robust and vibration-free

One-piece cast box frame

identical substructures to beused not only for all printingunits, but also for coating andintermediate dryer towers.

A further argument in favour ofdividing the printing units intoupper and lower sections is theresultant possibility to deliverand install the two halves sepa-rately in print factories whereaccess and space are restricted.The reduced transport weight ofthe split printing unit comparedto a one-piece design at the sametime serves to exclude excessivemechanical loads on the individualsubassemblies during transport.

Drive

All presses of the Rapida seriesare driven by a single motor,irrespective of the number ofprinting units. The drive poweris introduced almost exclusivelyvia the first impression cylindergear, from where it is distributedthrough a single continuous geartrain with helical teeth. Thanksto this design solution, there isno distortion of the drive systemeven in the case of very longpress configurations.

Fast-rotating drive componentsare often the source of unwant-ed vibration. One objective ofthe Rapida drive technology,therefore, was to eliminate alltypical origins of vibration, suchas longitudinal drive shafts,transmission gear boxes andbevel gears. Practical imple-mentation was made possibleby the high manufacturingquality of the helical gears.

Bearings

In view of the higher bearingforces which necessarily arise

Substructuresand gear train

Impression cylinder and gripper system

with bearer-to-bearer opera-tion, the use of plain slide bear-ings involves a much greaterrisk of bearing damage com-pared to antifriction roller bear-ings This can only be coun-tered by incorporating a de-fined bearing play into the sys-tem, though this can in turnbring negative effects for theprint result. Thanks to the play-free roller bearings used in alltoday's Rapida presses, thisproblem has become irrelevantfor Rapida users.

Grippers

Especially in the case of directoffset printing on corrugatedboard, constant gripper forcesappropriate to the substrate areessential. Differences in theclosing forces of the grippersystems on impression cylindersand transfer drums can leadto register fluctuations in thestretching direction of the sheets.

The impression cylinder andtransfer system grippers in pressesof the Rapida series operatewith a universal gripper setting.

This design solution means thatthere are no adjustments to bemade to the grippers to accom-modate changes in substratethickness.

Further support for sheet trans-port is provided by the rough-ened, ceramic-coated gripper

Three-ring eccentric bearing

Grippers

tips and the serrated gripper padswith flexible plastic inlays. Thegripper tips are characterised bytheir high friction values andresultant wear-resistance. Thisnot only permits reduction ofthe gripper pressure, but alsoachieves a constant self-cleaningeffect to significantly enhancethe service life of the grippers.

Together these componentsstand for utmost precision atsheet transfer.

View AView A

5

The design principle of the printing units

Double-size impression cylinders and transfer systems havealready been standard features of KBA presses for decades.

Experience makes slim and flexible

Console screen for air control settings

Sheet guide elements

Comb plate

Sheet guide system with function diagram

Impression cylinder and transfer system

Console screen for remote format setting

Impression cylinderand transfer system

The double-size impressioncylinders and transfer systems,each with two sets of grippersfor sheet transfer, guaranteelow-curvature sheet travelplacing a minimum of stresson the sheet.

The so-called "7 o'clock" cylin-der arrangement ensures thatsheets are always fully printedbefore transfer. This excludesthe deformation of the screendots which arises from thetransfer pull when a sheet isstill in the impression zone.

Sheet travel

Two particularly advantageousaspects of the Rapida technologyare the wide substrate flexibilityand the fast makeready times.A day's printing schedule canvary from lightweight papersright up to N, G, F or even E-flute board. There is often littletime to spare for experimentsto find the optimum settingsfor the fans and other elementsinfluencing sheet travel.

We have taken up the wishesreceived from customers, and

especially from their pressoperators, and have developeda system which permits centraloperation from the Ergotroniccontrol console and whichpresents all the available settingsin graphical form. The inputboxes have been positionedexactly where the printer expectsto find them for the individualadjustment to be made.

Sheet travel through the pressis based on the aerodynamicparadox, whereby fans and guideplates beneath the grippertransfer points create a vacuumair cushion. This provides forboth smear-free and stable sheettransfer from one printing unitto the next.

The settings for the air systemsare transmitted synchronouslyto all the printing units fromthe control console. Separatecontrol of the air volume ateach individual unit is unnec-essary since the transfer condi-tions for the sheet are identicalthroughout the press.

Corrugated board can be countedamong the most rigid printingsubstrates. Drum shells andcover plates, however, limit theflexibility of a press in this

Further information can be requested by phone on +49-(0)351/833-2674 or by e-mail from [email protected]

field and also restrict access tothe individual printing unitsubstructures. For this reason,the Rapida presses are designedfor smooth and unhindered sheettravel without drum shells orcover plates.

For materials up to 200 g/m2,so-called comb suckers smooththe sheets as they enter thenew impression gap and indoing so prevent slapping anddoubling. Further system com-ponents are available to handleheavy and corrugated boards.All electronically controlledsetting components can be ad-justed from the Ergotroniccontrol console, and the settingdata are naturally also savedfor later repeat jobs.

For the handling of thickersubstrates, a blower bar systemassists the passage of thesheets at the impression gapand at the gripper transfer points(no high-pressure air blastingnecessary).

The mechanical sheet guidingequipment for heavy stockscomprises a special guide barabove the impression cylindersand, for extremely rigid mate-rials, additional sheet-edgerollers.

It is only necessary to leave a3 mm guide margin down thetwo outer edges of the sheet tobe able to use these specialrollers. This system completelyeliminates the risk of the rearedge of the sheet hitting cross-beams or the like in the printingunit. The sheet-edge rollers arepositioned automatically in linewith the sheet format entered atthe Ergotronic control console.


6

Impression cylinder washing system RAPIDA 105 Blanket washing system RAPIDA 105 Blanket washing system RAPIDA 74

A distinction is made betweenthe washing systems for the smalland medium-format presses andthe technical solution for largeformats, all of which are to bedescribed here in somewhatmore detail.

Washing systemRAPIDA 74/105

The KBA presses for small andmedium formats are equippedwith the B 500 washing systemfrom Baldwin. In these formatclasses, two separate washingbeams can be installed in eachunit for blanket and impressioncylinder washing.

Common features

The previous inflatable rubbermembrane has been replacedby a fixed rubber lip, and a spraysystem has been integrated onthis lip directly at the point ofcontact between the cylinderand washing beam for preciselytargeted application of thewashing solvent to the cloth.

Washing systems

The wash-up times for a printing press are factors which regularlydiminish the degree of utilisation of the means of production. Forthis reason, KBA has developed a concept for its Rapida sheetfed

Concepts for cleaning

On the previous washing systems,it was not possible to advancethe cloth until the membranehad been vented. With the B500washing system, however, noventing is necessary and so thecloth advance can be performedparallel to the retraction of thewashing beam. The resultantshortening of the washing timesis an undeniable advantage forthe operator.

The weight of the individualwashing beams, moreover, hasbeen drastically reduced. Thecloth advance mechanism whichwas previously integrated intothe beam itself has now beenremoved to the side frame on thedrive side. The B 500 washingbeam thus now comprises onlythe two spindles, end platesand the rubber lip element. Afurther weight reduction isachieved by using aluminiumcasting (instead of steel) for theside cheeks and the pressureelement. Handling when remov-ing the washing beam has inthis way been made consider-ably easier for the operator andcan now be accomplished by asingle person with no problemswhatsoever.

Thanks to these design modifi-cations it is furthermore nowimmediately possible to exchangethe washing beams betweenprinting units.

The capacity of the cloth spindleshas also been increased by 25%.

Blanket washing system RAPIDA 74

The previously necessary removalof the floor plates between theprinting units has been over-come. It is now only necessaryto lift up these floor plates tobe able to replace the washingbeams.

The slimmer design of thebeams, furthermore, means thatthe drip tray beneath the systemcan now remain in the press.

Blanket washing system RAPIDA 105

A solution has been developedhere whereby the operator isable to replace the cloth both inthe press and outside.

Impression cylinderwashing system RAPIDA 105

One decisive improvement overthe previous models of the im-pression cylinder washing systemmust not be left unmentioned.A mechanical control cam nowlifts the washing beam over thecylinder grippers during thewashing process. The previouslyfrequent contamination of thegrippers has thus been eliminatedcompletely.

All advantages at a glance

• Fixed rubber lip with integrated nozzles for precisesolvent spraying

• Shorter washing timesthrough process optimisation

• Lighter washing beam facilitates handling for theoperator

• Washing beams can be exchanged between printingunits

• Spindle capacity increasedby 25%

• Cloth replacement possibleboth in the press and outsideon RAPIDA 105

offset presses which relieves the operator of much of the work whichotherwise occupies his time alongside the actual printing process,and here above all the washing of the cylinders and rollers.


7

Washing systems

• Mechanical control cam prevents contamination ofthe grippers

• Previous removal of floorplates and drip trays on RAPIDA 74 no longer necessary

Washing system RAPIDA large formats

For the large-format sheetfedoffset presses KBA developeda completely new washingprinciple. The washing systemsfor these presses enable theoperator to wash the impres-sion cylinder, blanket andplate cylinder with one and thesame washing unit.

On the latest version, the pathalong which the washing beamtravels to the individual cylin-der to be washed provides fora linear motion. The washingbeam is pivoted and can thusbe swung simply to the cylin-der to be washed.

One significant benefit with re-gard to ease of operation is thefact that the washing beam cannow remain in the press whenthe cloth is replaced and doesnot need to be removed manu-ally by the printer.

The washing system comprisesa motor spindle and a replace-ment spindle. When the clothreaches its end, the washingbeam is simply brought intothe change position, where thereplacement spindle with theused cloth can be removed andexchanged for a previously

prepared new spindle withfresh cloth.

Press studs on the motor spin-dle are used to fix the newwashing cloth. When the coveris closed, the new cloth is auto-matically wound fully onto themotor spindle, whereby dou-ble-sided adhesive tape fixesthe back edge on the replace-ment spindle to prevent the endof the cloth being torn off.

During each washing process, acertain length of used cloth, asdefined by the chosen washingprogram, is wound back ontothe replacement spindle.

With the aid of this new designsolution it has been possible toachieve a significant reductionin washing cloth consumption,as the only slightly soiled sec-tion of the cloth from the endof one washing process can beused again to remove the heavi-

est ink and/or dirt at the be-ginning of the subsequent wash.The resultant cost savings forcloth and solvent are not to beunderestimated.

Thanks to the motor-controlledspindle, it is possible to monitorthe length of the remainingclean cloth continuously and todisplay this information on thecontrol console.

All advantages at aglance

• Greater ease of operation for the printer

• Time savings when replacingwashing cloths

• Simple handling for cloth replacement

• Only necessary to replace one spindle (previously 2 spindles)

• Constant indication of the remaining clean cloth at thecontrol console

Effective utilisation of the washing cloth

• More effective utilisation of the washing cloth

• Reduced washing cloth consumption

Concluding remarks

The cloth-based Impact washingsystems available on all pressesof the Rapida series reduce theconsumption of washing solventsfor an individual washing cycleto an absolute minimum. It goeswithout saying for KBA thatvegetable-oil-based solvents canbe used. This means that usedwashing cloths can be disposedof together with normal domesticwaste. In this connection, brushsystems, which produce wasterequiring separate special dis-posal, are at a clear disadvantage.

A further major advantage ofthe washing systems on theRapida presses is the fact thatall washing programs can beconfigured simply from the con-trol console. By matching thewashing functions to the exactproduction conditions, solventuse especially can be limitedautomatically to the amountwhich is actually necessary.

Washing beam RAPIDA 74

Impression cylinder washing Blanket washing Plate cylinder washing


Washing beam positions on the large-format RAPIDAs


Inking and dampening units

8

The Colortronic ink ducts arefitted with ink keys which eachcover a 30 mm zone. The tips ofthese ink keys are carbideblades, while the duct roller isceramic-coated. This materialcombination enables the systemto operate free of all wear. Thefunction principle of the inkkeys guarantees exact, bleed-free separation of the individualzones and renders equalisationsoftware superfluous. The factthat the duct roller is drivensynchronously with the pressprovides for a fast ink transferfrom the metering point to thevibrator roller.

Requested ink metering correc-tions are realised quickly andwithout fluctuation. The speciallocking mechanism at the inkduct ensures that it is alwaysclosed to the duct roller withuniform pressure and contributessimilarly to the high degree ofreproducibility.

High process stabilityand quality

The single-train ink feed pro-vides for optimum heat dissipa-tion and avoids unwanted heat

The Rapida presses are equipped with inking and dampening units to satisfy even the most exactingquality demands. The single-train ink feed to the front forme rollers provides for fast reaction, lowwastage and short washing times.

Fast reactions and process stability

build-up in the inking unit. Thisdesign detail improves the inkflow characteristics by maintain-ing a highly constant viscosity.A further positive effect is fasterattainment of a correct ink-waterbalance. The outstanding processstability this brings ensures thatthe printed products satisfy thehighest quality demands. Therollers guarantee exceptional flex-ural rigidity, while the significantdiameter differences reduce thetendency to ghosting. An absoluteminimum of maintenance andadjustment, together with simpleinsertion and removal of therollers, are similarly clear illus-trations of the user-friendlyinking unit design. The capitaloutlay for roller replacement isalso relatively minor.

Inking unit temperaturecontrol

Temperature fluctuations influ-ence process stability. Varioustemperature control concepts,however, enable the user to re-main independent of the whimsof Nature! The medium and large-format Rapidas are already pre-pared for the installation of ink-ing unit temperature control in

the standard version. The ductroller and the three distributorrollers already possess the nec-essary bores for coolant circula-tion, which minimises the finan-cial outlay and installation timeif it is decided to retrofit the fullsystem at a later date.

One interesting variation forinking unit temperature controlis a combi-cooling unit, whichprovides cooling not only forthe inking unit, but also for thedampening solution.

A glycol cooler maintains thedesired temperature of the ink-ing rollers, the dampening so-lution and the compressors. Thecorresponding heat exchangershould, where possible, be in-stalled outside the building toavoid unnecessary warming ofthe air in the press room.

Where appropriate, it is alsopossible to implement solutionswhereby the warm air can bereturned to the production build-ing during the colder months ofthe year to reduce heating costs.If correctly dimensioned, asingle system is able to serveseveral presses.

Schematic diagram of the Colortronic ink duct with geared motor and meteringlever

Single-train ink feed for fast reactionsand process stability

Heat exchanger of a glycol cooler system

Installation diagram for temperature controlwith combi-cooling unit and glycol cooler

Filter and pump unit

Combi-cooling unitGlycol cooler

8 Issue 1/2002 KBA Process

9

Inking and dampening units

Not so with the Rapida presses.A simple console program per-mits the unused inking unitsto be mechanically disengagedfrom the press drive. Thisfeature immediately pays off inthe form of shorter washingtimes, a longer service life forthe rollers and more efficientmakeready.

Solids or chamois tones fromEuroscale colours are demand-ing challenges for both operatorand press. With such images,ink fading over the print lengthis especially critical. On theRapida presses, corrections canbe entered conveniently throughthe control console.

The reversal point of the oscil-lation is defined numericallyand at the same time displayedgraphically on the monitor screen.The same applies to the activa-tion and deactivation of oscilla-tion for the forme rollers.

If regularly changing colour combinations are the order of theday, it is often necessary to leave one or more printing unitsrunning "empty". On almost all other presses it is then impor-tant to apply roller oil to prevent excessive wear arising fromfriction heat.

Flexibility is standard

Dampening unit withwiping effect

The standard film-type dampen-ing units have already been inuse for low-alcohol and alcohol-free printing for some time.The differential drive for theink/dampening forme rollerrelative to the plate produces awiping effect and thus serves toprevent hickeys. This feature canbe activated and deactivatedthrough the Ergotronic console.A speed compensation functionis not exclusive to the inkingunits – the dampening unitsalso benefit from this technology.

Practice-orientedautomation

On-the-run adjustment of cir-cumferential, diagonal andlateral register can be effectedfrom the control console, eitherfor a single unit or for all printingunits simultaneously. Diagonalregister correction is achievedthrough tilting of the transfersystems.

Another useful system compo-nent is the optional video reg-ister device ACR Control whichserves to automate circumfer-ential, lateral and diagonalregistration.

Video register systemACR Control

Ergotroniccontrol console function forroller disen-gagement

Ergotroniccontrol console screen for oscillationtiming

Ergotroniccontrol console screen for diagonal regis-ter adjustment

Ergotroniccontrol consolescreen for lateral and circumferentialregisteradjustment


10

The separate coating tower istoday the most frequently chosenvariation for inline refinement.Conventional towers can be usedas a two-roller unit operating inthe standard direction of rotationor else with three rollers forcounter-rotation (reverse mode).This design solution is especiallysuitable for job structures wherethe volume of varnish to beapplied is regularly changing,but does bring difficulties inmany cases when working withconstant and even varnish coat-ings. The setting of an exactroller gap over the whole widthof the roller is rather time-con-suming and places high demandson the skills of the press operator.

For this reason, a coating towerwith chambered doctor blade andanilox roller has established

Coating tower

KBA offers its customers a number of different varnishing conceptsfor the inline refinement of the printed products. All the unit-basedpresses of the Rapida series can be equipped with the ideal combi-nation of modules to suit individual needs.

Inline refinement: High efficiency in co

itself successfully for over 90%of inline varnishing applications.

Since recently, KBA is able tooffer sheetfed offset customersan even more sophisticateddesign solution for such ananilox coating system.

The chambered doctor blade,in conjunction with a laser-engraved ceramic anilox roller,represents a precise method forthe processing of

• water-based varnishes• UV varnishes• blister varnishes • decorative metallic inks• primers• gloss and matt varnishes• tintings• special varnishes

the whole sheet width even withdifficult formes.

Anilox rollers with engravedscreens between 55 and 160lines/cm are available for themost varied applications. Eachcoating tower is fitted with ablock-and-tackle hoist to facil-itate exchanging of the aniloxrollers.

For the system blade cham-ber/anilox roller, KBA now in-stalls the LithoCoat systemmanufactured by Harris & BrunoMachine Company, the world-wide largest supplier of cham-bered doctor blade systems.

A number of decisive designchanges compared to previoustechnical solutions have pro-duced significant benefits withregard to ease of operation.

With the LithoCoat system,the blade chamber is appliedto the anilox roller by way ofa hydro-pneumatic blade pres-sure control. Thanks to theHydroCompsystem™ any wear

Blanket cylinder

Formeroller

Transfer roller

Pan roller

Varnish pan

Impressioncylinder

Conventional offset coating towerOffset coating towers with pan rollersdemand continuous adjustment of the rollers and are not always able totransfer a constant film of varnish.

New: LithoCoatTM systemA chamber blade system, in conjunc-tion with a laser-engraved aniloxroller, is an extremely precise meansfor constant applications of printinginks and varnishes.

Impressioncylinder

Blanket or plate cylinder

Aniloxroller

Harris & Brunoblade chamber

In the new system, the alteredposition of the anilox roller re-sults in significantly improvedhandling for the operator. Forexample, it is no longer neces-sary to adjust the anilox rollerto compensate substrate thick-ness changes up to 0.8 mm.

The varnish plate, further-more, is now inserted in thedirection of printing. With semi-automatic plate clamping, thiseliminates the previously nec-essary manual tightening ofthe tensioning screws. Themakeready time for the semi-automatic system has thus beenreduced noticeably comparedto the original technical solu-tion and now amounts to justtwo minutes.

Further design modificationshave simplified access to thevarnish forme. This is especiallyimportant when using blankets.

By increasing the diameter ofthe anilox roller, it has also beenpossible to achieve a stable andeven varnish application across


11

Coating tower

on the blade is automaticallycompensated, eliminating theneed for manual adjustmentand correction of the wearingblade as is required when oper-ating with constant pressure. Theextremely low contact pressure,furthermore, ensures a consid-erably longer service life of theblade – and in the long runalso of the anilox roller.

The positioning of the bladechamber against the anilox rolleris a linear action. This meansthat the angle of the blade andconsequently also the exactvolume of varnish applied isalways constant.

This is naturally an ideal situa-tion when it comes to repeatjobs, as it is a simple matter toreproduce the production con-ditions for coating at any time.With three to five actuatingcylinders distributed evenlyacross the whole width of thechamber (the actual number isdependent on the press format),possible flexing of the chambercan be prevented effectively.

For maintenance and cleaningpurposes the blade chambercan be swung out by 90° forremoval, without the need fortools. The surfaces of thechamber itself have been givena special coating known as"Ceramic Coat", which providesfor simple cleaning and at thesame time provides effectiveprotection against mechanicaldamage.

The technical design of thisanilox coating system bringsthe following advantages:

• Minimum blade wear• Optimum sealing of the

system• Minimum stressing of the

anilox roller• Constant varnish application• Comfortable handling• Fully automatic varnish

changes (optional)

The cleaning of an anilox coat-ing tower after use was to datealways a rather time-consumingaffair for the operator. To over-come this time factor in daily

production, the LithoCoat bladechamber can be combined witha dedicated varnish supply andcleaning system, a so-calledLithoCoat circulator.

The LithoCoat circulator canbe used for both water-basedand UV varnishes. It comprisesall the elements which are nec-essary for an efficient varnishsupply and for thorough clean-ing of the system, including awarm water tank and a recircu-lation tank for the cleaning sol-vent. The printer operates thesystem simply and convenientlyby way of a detachable touch-screen controller.

The printer is also able to selectdifferent programs for differenttypes of varnish, which guaran-tees an optimum cleaning effectand eliminates all need for ad-ditional manual cleaning of thesystem. This naturally shortensthe overall cleaning process andmeans that it is also possible toswitch varnish types during anormal production schedulewithout losing unnecessary time.

The new varnishing system onthe Rapida presses represents afurther leap forward in termsof quality, as becomes visibleboth in the ease of handling forthe operator and in the resultsof the product refinement.

nstantly reproducible quality

Varnish

Desired filmthickness

Sheet

A constant film thickness reduces varnish con-sumption while at the same time improving quality.

Optimised varnish application



Anilox roller with chambered doctor blade

Function principle• The LithoCoatTM unit pumps the varnish into the chamber• The chamber fills the cells in the anilox roller• The anilox roller transfers the varnish to the blanket or plate cylinder

12

Anilox roller Detachable touchscreen controller for simple and reproducible handling

Varnish tank(water-based or UV)

LithoCoatTM

circulator

Heated water tankCleaning solventcirculation tank

Level sensor for overflowtray

Blanket or platecylinder

Coating tower

Typical coating tower with Harris & Bruno LithoCoatTM

The LithoCoat™ circulator is a standard component of all installations.It incorporates all the necessary pumps,valves and (quick-snap) fittings, as wellas a controller for efficient managementof the varnish supply and cleaning of the system. No additional manual clean-ing is required.

First the anilox roller

The anilox roller is a meteringroller designed to supply aconstant, uniform and definablevolume of a liquid. A computer-controlled laser is used to etchmillions of microscopically smallpits (cells) in the ceramic-coatedsurface of the roller. These cellstake up the ink or varnish andtransfer it to the blanket or platecylinder.

Now the LithoCoatTM

varnishing process

The LithoCoat™ unit pumpsvarnish into the chamber space,from where it is able to fill thecells in the anilox roller. Aspecial blade inside the cham-ber then scrapes the surface ofthe roller clean, leaving behindonly the liquid in the cells. Thecontents of the cells are thentransferred onto the blanket orplate cylinder and subsequentlydirectly to the sheet or substrate.

This printing process has al-ready been used successfullyfor many years in other branchesof the printing industry. It isprecise, tested in practice – and

it works. Offset printers allover the world have recognisedthe clear benefits of this tech-nology and have turned theirbacks on the problems associ-ated with roller-based systems!

Further information can be requested by phone on +49-(0)7171/947040or by e-mail [email protected]

What catches the eye• Higher gloss values• Improved varnish or ink

acceptance• Constant film thickness• Fast cleaning• Reduced varnish or

ink consumption• Less blocking• Flatter piles• Reduced powder

consumption• Precise, sharp edges

What has disappeared• Orange peel effects• Blank spots• Marking• Unwelcome edge build-up


Further information can be requestedby phone on +49-(0)351/833-2580or by e-mail from [email protected]

13

Air Clean System

Eliminating odoursin the press room


The eco-accreditation process for our Rapida sheetfed offset presses entailed measuring all possibleemissions at and around the press. These included alcohol vapours, ink mist, vapours from cleaningagents, powder dust, warm air and, where UV applications come into play, ozone. We are happy toreport that all the values recorded were well below the maximum permitted levels for workplace emis-sions, and as a result our Rapidas were the first sheetfed offset presses worldwide to be awarded”emission tested” environmental accreditation. However, in order to ensure compliance – even underextreme shopfloor conditions – with the rigorous threshold values prescribed by emissions directives,we decided to refine some basic features even further and to develop new ones.

One example is ACS, our new air-cleaning system for installationat the sheet delivery.

Health risks to press personnelfrom emissions are particularlyhigh at the delivery. This istherefore the zone that demandsthe closest scrutiny and effectiveaction to safeguard a healthyenvironment.

During a production run the grip-per carriage generates turbulenceand an intensive movement ofair in the direction of inspectionsheet delivery, drawing odours,heat and powder dust along inits wake.

This is exacerbated if the sheetsare coated before being dried,because chemical reactions duringreticulation cause odorous sub-stances to be released which,though not hazardous to health,are nonetheless far from pleasantfor the press operator.

ACS was developed specificallyto eliminate such emissions at

the delivery of Rapida presses. Itfeatures a special exhaust systemthat kills two birds with onestone by eliminating both odoursand powder dust. On top of this,we introduced a new generationof powder sprayers and extractorsystems to reduce the absolutevolume of dust generated.

The new air-cleaning system isan optional extra offered for allRapida press types from thesmall-format 74 and medium-format 105 to the largest formatwe offer, the 120 x162cm (63.75")162a. Although ACS is an inte-gral component of the Rapidaeco-package, it is also availableseparately.

Effective extraction ofairborne emissions

The ACS delivery features anextractor nozzle with an acrylicair barrier, located at 90° to theviewing window in front of thedelivery pile, and additionalnozzles at the edges of the pile.The emission-laden air is drawn

by a special suction system intothe main exhaust stream. Theventilation channels needed areintegrated in the design of thedelivery. The two photos aboveshow how the air-extractionsystem functions, from inspec-tion sheet removal to the mainexhaust path in the upper sec-tion of the delivery.

Compatible with inline coating

Alongside the eco-accreditedRapidas, in which an ACS delivery is a standard component,we also recommend installingACS in other presses featuring

inline UV coating, because thesystem can substantially reduceodour emissions that arise whenUV inks and coatings, and alsocertain dispersion varnishes, arebeing processed.

A healthy working environmentfor the press crew is essential inany printshop wishing to enhanceproductivity, quality and costefficiency. With the new ACSdelivery we offer a feature thatcan dramatically improve thepressroom environment.

How an ACS fitted at the delivery of a Rapida 142 functions

On our medium- andlarge-format Rapidasthe extractor nozzles arelocated directly beneaththe viewing window atinspection sheet delivery

14

Plastics

Every printer today needs toachieve the highest possibledegree of press utilisation,while atthe same time minimising outlayfor maintenance and makeready.After all, these factors are at leastas decisive for business calcula-tions as the production speed ofthe printing press. The demandsplaced on equipment suppliers,consequently, have been fixedat an equally high level.

Whether with or without UVtechnologies, there are manyfactors which not only hinderthe printer's work, but also in-fluence the quality of the result,depending on the materials andpresses used. Particularly withUV printing, this is then added toby the problem of ink adhesionto the most varied substrates.

The curing (drying) of UV inkis an extremely fast chemical

process, in which UV radiationtriggers a photochemical reaction(polymerisation) and causesphoto-initiators contained inthe ink to break down. Withinjust a fraction of a second, thisleads to cross-linking of theUV ink and adhesion to thesubstrate. It is this propertywhich makes it possible at allto print on a variety of plasticmaterials, such as PE, PP or PVC.

The UV print market continues to expand in two-figure leaps.Why is that? On the one hand no doubt because the UV printprocess has in the meantime left its teething troubles and develop-ment phase behind and has gained wide acceptance. On the

Inert UV in sheetfed offset – the new solution for plastic materials

A great deal of electrical energyis needed for this process. Thisenergy, however, is not con-verted exclusively into the UVradiation required for poly-merisation, but also generatesa substantial amount of heat.

The UV dryer systems in usetoday generally operate with aspecific UV radiation output of160 W/cm per UV lamp. Certainapplications (high ink coveragewith opaque white) may evencall for higher outputs of up to240 W/cm. The amount of heatintroduced into the press, whichis equivalent to about 60% ofthe lamp output, is correspond-ingly high.

This additional heat generationconstitutes a significant thermalload on both the press and theprint substrate, and can easilyculminate in material deforma-tion, registration problems andexcessive pile temperatures.These factors influence theprinter's work and demand his orher full attention if a high-qualityprint result is to be achieved.

The build up of heat in thepress and in the printshop ingeneral leads over time tounstable ambient conditions,which in turn upsets the ink-water balance and can thussimilarly impair print quality.

Reduction of the heat generationin the press, therefore, is animportant priority. To this end,dichroic reflectors are used toabsorb heat from the reflectedUV radiation, alongside chilledair systems for the cooling ofthe impression cylinders andthe substrate.

A better solution, however,would be to reduce the lampoutput and at the same time toimprove the curing and adhe-sion properties. This is madepossible by "inert UV".

What is inert UV andwhat influence doesthis have on printingwith UV inks?

Inert UV means that the UVinks are cured under a nitrogenatmosphere and that oxygen fromthe ambient air is practicallyexcluded from the process.

The oxygen in the air hindersUV curing considerably, as thefree radicals produced by thebreaking down of the photo-initiators (the particles actuallyresponsible for the curing ofthe UV ink) tend to form bondswith the oxygen instead of pro-moting the curing process inthe ink. The result is that veryhigh UV lamp outputs (up to240 W/cm) are required to beable to break down all thephoto-initiators.

The inert technology itself isnot new. Eltosch has beensupplying inert UV systems tothe coating industry for some10 years now, e.g. for the pro-

duction of carrier materialsfor adhesive labels. For suchapplications, in particular, ex-tremely high demands areplaced on the quality of theinert atmosphere.

Before this technology could beimplemented in a sheetfed off-set printing press, it was firstnecessary to develop a specialchamber compact enough to beintegrated into the press betweenthe impression cylinders and theUV radiation sources. Throughcooperation with SID, theSaxon Institute for the PrintIndustry, it was possible tosolve all the arising problems(limited installation space,rotating cylinders, gripper car-riages, etc.).

This chamber is flushed withnitrogen during the printingprocess, which keeps the oxy-gen in the ambient air awayfrom the substrate surface. Allthe free radicals produced arethus available for the curing ofthe ink.

As a further consequence, theycan also be activated with asignificantly lower lamp output(60-80 W/cm!). There are more-over practically no restrictionswith regard to substrate thick-ness due to the additional inertchamber.

other hand, however, it must also be seen as a reflection of theever new challenges faced by print enterprises (faster availability,shorter delivery schedules, higher levels of refinement) and theincreasingly frequent demand for the printing of plastic materials.

Cross-linking of the ink under UV radiation

UV cross-linking under inert conditions


15

Plastics

The advantages of inert UV

The UV interdeck dryers canbe operated with outputs of 80W/cm. Print jobs without var-nish can be handled withoutUV end drying and with onlyone interdeck dryer. The useof substrate primers can bereduced.

To take a practical example,this means that a print job on300 µm PVC with 2x opaquewhite (printing units 1 and 2)and four scale colours inline plusUV varnish can be produced

Summary

Approx. 80% less heat generated in the material thanks to anoptimised UV dryer system (for printing on plastics):

• Drastically reduced UV lamp outputs• Newly developed inert UV modules• Fewer registration problems arising from heat build-up

in the material• Excellent curing of the ink• New process options enable new products to be developed• Reduction and partial elimination of unpleasant odours• Potential for savings in power consumption• Printing press protected from excessive thermal loads• Safe technology: Nitrogen already makes up 78%

of our atmosphere

Application examples

Material: Soft PVC, white, 300 µm

Colour sequence: 4 colours (K, C, M, Y)

Varnish: yes

Printing speed: 7,200 sheets/h

Dryer configuration: 1x interdeck inert UV, 80 W/cmUV end drying, 2 x120 W/cm

Material: Vinyl, transparent, with adhesive, 100 µm

Colour sequence: 4 colours (K, C, M, Y)

Varnish: yes

Printing speed: 7,500 sheets/h

Dryer configuration: 1x inert UV interdeck, 80 W/cmUV end drying, 2 x120 W/cm

Calculation example

• 3B format, 6 colours, 3 inert UV modules• Run length = 12,000 sheets• Printing speed = 8,000 sheets/h• Costs for nitrogen (N2) = approx. 47,20 Euros• Extra costs for nitrogen in 3B format:• For 12,000 sheets approx. 0,4 Euro cents per sheet

Further information can be requested by phone from Dipl.-Ing. Jens Gottschalk,Eltosch Torsten Schmidt GmbH, on +49-(0)40/84 00 07-0

Inert UV interdeck dryer in a KBA RAPIDA 105

Inert UV interdeck dryer connections on the drive side

using 3 UV interdeck dryers(positioned after units 1 and 2and ahead of the coating tower)with outputs of 80 W/cm eachand a final drying installationof 2 x 120 W/cm. The printingspeed could be raised from7,500 to 9,000 sheets/hour witha parallel reduction in the piletemperature by approx. 15°C.

As plastic materials becomeever more widespread also inpackaging printing, the inertUV technology represents afuture-oriented solution foroffset printers.


16

The result, a first generation ofso-called hybrid inks, was pre-sented some two years laterand the first printing press wasequipped specifically for thisapplication in 1998. In the yearssince, the total of such configu-rations has risen to between 70and 80 installations.

Who uses hybrid solutions in practice?

The "classic" hybrid installa-tion with hybrid drying is to befound in over 90% of the caseson presses with a coating towerand extended delivery. This in-dicates that the users see thehybrid technology as an exten-sion of their product range.These presses are equippedwith infrared/hot-air dryers inthe extended delivery for thehandling of conventional jobs(water-based varnishes). Topermit the use of hybrid inks,an additional UV interdeckdryer is installed between thefinal printing unit and thecoating tower to dry the inksbefore application of the UVvarnish. The extended delivery

UV dryers

Sometimes it is a coincidence which brings a breakthrough! Dur-ing a visit to an American customer, the UV final drying happenedto be switched on during a conventional print job, whereby theapplications engineer from GRAFIX USA LLC noticed that the sur-

Noble and economical: Hybrid applications in sheetfed offset

is then fitted correspondinglywith UV final drying to curethis UV varnish.

Precisely this technology enablesprinters to offer new productswhich in the past would onlyhave been feasible with severalpress passes and with dedicated

accessories. They are no longerhampered by the high invest-ment outlay for a "special press".Furthermore, the users are ableto take advantage of a relativelysimple process to achieve highgloss values, and no longer needto experiment with the vagariesof a double-coating press andthe uncertain compatibility ofdifferent conventional inks,primers and UV varnishes.

The first hybrid installations usedthis technology for approximate-ly 20 to 30% of the work, whilethe majority of the jobs was stillprocessed in the conventionalmanner. Over the course oftime, however, the percentageswere shifted more and more infavour of hybrid drying.

One of the main reasons forthe success of the hybrid tech-nology in an inline process isno doubt to be found in theattainable gloss values. Underideal circumstances, the glossis today already able to ex-ceed that obtained with offlinecoating.

This is naturally still dependenton the willingness of the userto learn and gradually build upexperience. With hybrid inks,too, success in attaining highgloss values is governed by thedetails. The configuration of theUV equipment, for example, hasundergone various changes inthe course of development. Atthe beginning, as describedabove, the presses ran with in-termediate drying before thecoating tower. Today, however,a typical hybrid dryer system isplanned with two interdeckdryers. The second interdeckdryer is inserted individually atthe point along the press mostappropriate for the job or coloursequence in use. This flexibilityin the location of the UV inter-deck dryers needs to be taken

into account as part of the orig-inal investment decision to avoidunnecessarily expensive retro-fitting. An opaque white, forexample, is usually cured im-mediately by an interdeck dryerto obtain better results at highproduction speeds. This meas-ure, in combination with further

job-specific settings, enablesthe user to achieve a stableand reproducible print quality.Another possible applicationfor hybrid inks is to producespot coatings through the com-bination of hybrid and conven-tional inks with UV varnish.

How dangerous is UV drying?

The interesting fields of appli-cation for the new hybrid tech-nology have led to more andmore "conventional" printerscoming to work on such presses.A few years ago this would havebeen a domain for specialisedUV printers. The advantage fora specialist lies above all inthe fact that the operating staffalready possess extensive back-

Possible installation positions for the UV modulesin a sheetfed offset press for hybrid applications

UV module with open shutters, air and water cooling, top heat shield anddichroic coated reflectors

face of the ink had been hardened to a certain extent by the UVradiation. To optimise this process, a recipe for printing inks with acertain UV content was developed together with an ink supplierand improved through numerous test series.

Quartz filter (optional)

Reflector

UV lamp Shutter Heat shield


17

UV dryers

ground knowledge about the UVprocess and equipment. For the"newcomers" to the UV scene,there is quite naturally a greatdeal to catch up on in termsof staff familiarisation andinstruction. This applies espe-cially to the handling of UVinks and UV varnishes.

Through the cooperation be-tween KBA and GRAFIX, ithas been possible to preparethe presses optimally for theincorporation of a UV system.Special attention is paid toshielding of the UV radiation.It can thus be excluded that auser needs to look directly intothe UV light. All press coversare either bolted tight to thepress itself or else protected byway of safety switches.

It is strongly recommended, inthis connection, to consult therelevant brochures publishedby the health and safety associ-ations responsible for the printand paper industries. They in-variably contain a wealth of in-formation regarding UV drying.

Power consumption of UV dryers

The energy demand of UV dry-ers is significantly greater thanthat of conventional IR/hot-airdrying systems. This is dueabove all to the performancecharacteristics of the gas dis-

charge lamps used. This isillustrated in the diagram below.In the case of the UV systeminstalled by GRAFIX on theRAPIDA 105 in the KBA cus-tomer centre in Radebeul, forexample, the UV dryer aloneaccounts for a connected loadof 100 kW.

Do UV dryers mean intensive maintenance?

This is not necessarily true,though much does depend onthe general care and mainte-nance of the UV system. It isclear that the UV elements inthe press are to be cleanedfrom time to time, wherebyalcohol or white spirit and alint-free cloth can be used towipe the UV lamp and reflector.

If the press is to operate for alonger period without the UVsystem, then it is recommendedto remove the UV modules. Tothis end, all connections aredesigned as quick-release cou-plings, enabling the whole UVsystem to be removed from thepress in less than five minutes.If the UV system is to remainin the press, on the other hand,it is important to clean offpowder and other accumulateddirt each time before using theUV drying. This maintenanceis decisive for the service lifeof the lamps and reflectors.

GRAFIX UV modules are de-signed as slide-in cassettes, i.e.guide rails permit the elementsto be inserted and removedquickly and simply through thecorresponding openings in thepress side.

UV lamps

The GRAFIX UV modules in-corporate almost exclusivelymercury lamps, which arecharacterised by their high UVyield, low-ozone operation andthe facility for adaptation todifferent spectra. This providesfor lower energy costs and

higher productivity. The lampsthemselves are simple to re-place thanks to the user-friendlydesign of the UV modules.

Performance characteristics of a gas discharge lamp in the system of UV drying for hybrid applications

UV module as a slide-in cassette Quick-release couplings for simple in-sertion and removal of the UV modules

Fast UV lamp replacement

Heat radiation at electrodes 10 %

Total radiation of plasma 80%

10% heat conduction

30%UV

40%IR

10%

vis

ible

ligh

t

Further information can be requested from theGRAFIX team by phone on+49-(0)711/7869-00or by visiting www.grafix-online.de


18

Logistics

Non-stop systems for the feeder and delivery of the Rapidapresses offer an ideal starting point for enhanced productivitythrough automation of the whole process of materials logisticsin the printshop. This is especially significant for the directprinting of corrugated boards, as a substrate thickness of 1 mm

Pile logistics for greater productivity

initiates an automatic pilechange. During this process,the full pile is removed to thedrive side and the empty pallettakes its place on the pile car-rier plate. The press operatorneed only pay attention to the

depositing of the auxiliary pileonto the empty pallet. Theprinted pile can be passedeither to an intermediate stor-age area or else directly to thedie-cutting machine, as re-quired by the local technology.

Logistics integration solutionscannot be treated in the sameway as standard products. Suchan installation is always theresult of specific, individualplanning.

or more means that piles already need to be changed at bothfeeder and delivery approximately every eight minutes. Pressoperators are naturally unable to keep pace with suchdemands over longer periods in addition to their quality con-trol duties.

Fully integrated logistics

The most efficient variation isachieved by integrating thelogistics elements of the feederand delivery. The press roomdepicted here is just one exam-ple to illustrate the many pos-sibilities for logistics integra-tion. The pallets are taken fromthe high-rack stores, unpacked,set down on the transport sys-tem and subsequently trans-ferred to the pile turners. Thepile turners enable the piles tobe aligned and also exchangethe transport pallets for specialsystem pallets.

Alignment and straightening ofthe pile is necessary to ensuretrouble-free handling at thefully automatic feeder of thepress. The prepared pallets cannow be directed to the appro-priate press via a system oftransport tracks and turntables.

The empty pallet is ejected to apark position on the operatingside of the press to allow thepre-stacked new pallet to beinserted into the fully automaticfeeder from the drive side.Once the main and auxiliarypiles are reunited, the emptypallet can be passed back underthe new pile and transported tothe delivery for further use. Thefunction principle at the deliv-ery is effectively identical. Theempty pallet is passed underthe pile in the delivery andparked on the operating side.When the printed pile reachesthe predefined height, the printer

Example of a production set-up withautomatic pile handling and palletdistribution


19

Logistics

Automated transport to the feeder

Pile transport to the feeder canbe automated with a roller con-veyor to deliver the pre-stackedpiles. In this case, the logistics

Pile logistics is an immensely importantconsideration when handling thicker sub-strates such as heavy board or corrugatedmaterials.

Phases of a non-stop pile change with logistics at the feeder

1 The press prints from the auxiliary pilewhile the empty pallet is removed

2 The new pile is inserted automatically3 The main and auxiliary piles are united

Automated removal at the delivery

The procedure at the deliveryis virtually the same. Once themaximum or preselected pileheight has been reached, thenon-stop rollers are activated.While the rollers support theauxiliary pile, the main pile isautomatically lowered and re-moved from the delivery. Theempty pallet is positioned onthe pile carrier plate and liftedup beneath the non-stop rollers,which then retract automatically.Unlike the feeder system, thelogistics equipment for the de-livery is also able to handlestandard wooden pallets.

system then accepts the pile andaligns it with the feeder. Oncethe empty pallet has been low-ered and automatically ejectedfor manual removal, the newpile is inserted into the feeder,where it is picked up by a car-

rier frame and raised to pro-duction height.

Automated pile logistics at the delivery of a Rapida large-format press

Further information can be requestedfrom Jürgen Veil by phone on+49-(0)351/833-2674 or by e-mail under [email protected].

Information can also be obtained from Martin Dänhardt by phone on +49-(0)351/833-2580 or by e-mail under [email protected]


20

Production management

Because it supports a company-wide, cross-platform exchange of digital data among management,production and logistics divisions, Logotronic professional furnishes enormous potential for enhancingprintshop productivity.

Digital workflow with Logotronic professional

Featuring open interfaces, thesystem is built around theLogotronic server – a high-powered PC with database andbasic software, plus an inte-grated web server – which hasthe task of exchanging data be-tween the individual systemcomponents within the printingplant, processing and storingthese data and supporting com-munication via the printshopnetwork. Here KBA is breakingnew ground with browser tech-nology that is far superior toother stand-alone systems cur-rently available on the market.

Logotronic professional fur-nishes a link to commercialIT and management informa-tion systems (MIS) as well asto different types of printingpress and peripheral equipmentat production level. Both weband sheetfed presses can benetworked within a singleLogotronic system.

Expansion with branch software

The Logotronic system is fur-thermore able to incorporateseparate branch software froma variety of suppliers. This soft-ware is used for job scheduling,calculating and planning. Job

data are transferred via an in-terface to the Logotronic serverwith the printing out of the jobdocket. If the plate is exposedcomputer-to-plate, a file is cre-ated simultaneously in CIP3format and transferred to theLogotronic system. Ink preset-ting data for the relevant pressare also created. A job queue isdisplayed at the console for theoperator. Once the new job hasbeen selected from the queue,Logotronic furnishes the presswith all the relevant presettingand repeat data, and the pressis then preset automatically inaccordance with these data. Theresult is a major reduction inmakeready times and waste.

When printing repeat jobs, awhole array of additional settingvalues such as blower parame-ters, powder data, printing pres-sure etc. are available for presspresetting.

Overview for management

The Logotronic system en-ables management to monitorthe current job status. ThePressWatch component fur-nishes an overview of all theprinting presses on the net-work. The jobs currently beingrun, counter states and theprinting speed of the individualpresses are displayed on the

Example for the networking of presses and peripherals with KBA Logotronic professional

KBA Logotronic

Rapida 74 Rapida 105 Rapida 162

PerfectaKBAservicedepart-ment

Console Console Console

Router ScantronicCreo

TrendsetterCreo

Lotem QuantumBranch software

Print PlusLogotronic

professional server

EthernetArcnet


21

Production management

screen. Press data and moredetailed data on the job runningon a specific press, can be calledup using the mouse. This in-cludes data on split jobs andindividual printing passes,scheduled deadlines and runlengths, as well as gross andnet counters. The text and timestamp of the most recent pressstatus message are also dis-played. SpeedWatch, on theother hand, creates a time/speeddiagram with which all theresults and messages for theselected presses can be checkedand stored. The press for whichthe time/speed diagram is to becreated is selected from adropdown list. All the parame-ters generated automatically bythe press are entered in the dia-gram. The yellow line standsfor makeready, the green linefor production. The cursor marksthe press status at a specifictime. The arrow buttons areused to jump between events.A zoom function enables theintervals displayed in the dia-gram to be changed. This meansthat press events from the past72 hours can be monitored. In

Customers are showing a lotof interest in this option forcreating a printshop workflowsystem using Logotronic pro-fessional. As more and moreprint enterprises adopt com-puter-to-plate technologies, sothe conditions become morefavourable for accessing andutilising all available digitaldata companywide.

Logotronic basic for simple transfers of presetting data

Alongside the full-scaleLogotronic professional work-flow system, we also offer amore compact version calledLogotronic basic. This versionwas developed to support thetransfer of preset data to thepress as simply as possible, e.g.to older presses. Logotronicbasic embraces CIPLink (CIP3data transfer for press preset-ting), a job log and an onlineconnection for the plate scanner.

PressWatch furnishes a production update on all presses With SpeedWatch all the events and messages relating to individual presses are collated in a time/speed diagram

The presses linked via Logotronic professional at the KBA site in

Radebeul are installed in three pressrooms like the one to be seen here

The printing plant's own hard-ware (server) is used to imple-ment the networking system.Only the presetting data for theink keys and duct rollers aretransferred. When the job isfinished, job log data are madeavailable for actual costing. Bycontrast, Logotronic professionalfurnishes the printshop with acomplete production manage-ment system, which includesmore detailed information tosupport operational and strate-gic decisions at executive level.

the mornings, for example, it isthus possible to obtain data onproduction during the previousnight shift.

Intranet and Internet as total informationmedium

This information can be down-loaded by authorised personnelvia an Intranet or the Internet.Needless to say, security fea-tures play a key role. A printingplant manager for example, canupdate his customers on thecurrent status of their print job,or download current productiondata, both in his office or fromhome.

Logotronic professional in use: Final check of the imposed sheet before printing

Further information can be requested by phone on +49-(0)351/833-2183or by e-mail from [email protected]


22

Densitronic S

Advances in press engineeringhave still failed to solve oneproblem: the final print, whethermeasured by colour density orcolour coordinates, cannot bereproduced with 100% accuracy.It is neither possible to print ajob where the images are iden-tical from the first sheet to thelast, nor to run off a repeat jobthat is identical in every detailwith the original job a year be-fore, even with identical ink keysettings. The reasons are phys-ical and depend on the con-sumables and equipment used.

1. Behaviour of the inking unit over time

An inking unit cannot startinking the sheet until it con-tains a basic volume of ink.This basic volume dependsprimarily on the average con-sumption per key. But it can

The first press featuring KBA Densitronic S was shipped in December 1996, to Staudigl Druck inDonauwörth. Since then, around 100 sheetfed offset presses with this system have come on streamworldwide. Thanks to its open architecture it can be configured freely with more than one press, andin some printing plants three Densitronic units are connected to six presses The number of shipmentshas more than doubled year by year. What's the big attraction?

Spectral quality measurement and control

neither be applied via the inkkeys all at once nor fed into theinking unit in precisely the rightvolume. In addition, althoughthe volume of ink must be me-tered precisely, it is distributedbetween the rollers in differentproportions. The thickness ofthe ink film applied to the firstroller after the vibrator roller,for example, is always severaltimes as thick as the film onthe forme rollers.

Luckily, operators of printingpresses do not have to worryabout the exact relative thick-nesses of the ink films. Thenumber of sheets wasted in therun-up to colour, however, isvery much their concern: afterall, a dynamically unfavourableink run-up program – whethercontrolled manually or auto-matically – can generate anawful lot of waste.

Achieving the correct balancebetween ink feed and ink ap-plication always takes time andtherefore consumes sheets, eventhough the number has beenreduced to a relative minimumwith KBA's short-train inkingsystems. Admittedly, KBADensitronic S cannot shortenthe physical transition timesbetween two inking states:however, thanks to its controlalgorithms, far fewer controlsteps are needed to obtain thedesired result – a decided ad-vantage in view of the fact thatone job change can involve ad-justing as many as 324 ink keyson a single press.

2. Mechanical settingsin the inking unit

Although presses are engineered,manufactured and set to thehighest standards of precision,the general influence of exist-ing tolerances will still preventuniform inking across the cylin-der. Even if the key meteringelements on a solids form haveidentical settings, the densitycharacteristic will still not be

absolutely straight, nor willother factors such as pressure,blanket parameters etc. remainconstant for the whole durationof the print run. Storing pro-files from the previous job orretrieving presetting values froma plate scanner can deliver only70% - 90% of the desired settingperfection. The remaining 10%- 30% must be achieved manu-ally or with a control system.KBA Densitronic S, with itsself-learning control system,delivers optimum results fast.

New technology combines densitometryand colorimetry

For a long time ink key controlwas based solely on densitomet-ric values. Measurements weretaken in control strips or onindividual fields distributedaround the sheet. The referencevalues for checking density werebased, in commercial printing,on standard values spearheadedby FOGRA and the BVD usinginking samples and dot gain ta-bles, in packaging printing andspecial colour printing on in-house standards. Problems arose,and still arise, whenever theagreed combination of printcharacteristics and full-soliddensity in the press could not beutilised because of productionfactors such as blanket condition,pressure setting, trapping, wateretc. The only corrective actionthe press operator can take is tochange the target density of in-dividual inks in the zones.

Quality measurement and control with Densitronic S on several Rapida large-format presses

The dual-purpose Densitronic S measuringhead can be positioned at any point on the sheet


step by step with all the mani-fold merits of spectral col-orimetry and control.

Greater interest for spectral colorimetry throughcolour management

The high-precision positioningunit can position the spectralmeasuring points anywhere onthe sheet that is sufficientlysmooth. Controlling the greybalance is just one – relativelysimple – special case, becauseany percentages of area cover-age for the individual colourscan be combined. In the sim-plest scenario, spectral refer-ence values are obtained fromthe reference sheet. However, ifthe system is used during make-ready as well, the referencevalues can also be retrievedfrom the comprehensive andself-expanding reference-colourdatabase, or from customersamples.

2. The spectral and other meas-uring deviations between thereference sheet and the actu-al sheet had to be translatedinto control recommenda-tions for the individual ink-ing units.

The second obstacle was over-come before the first: As partof a research project in 1992,a process was developed forbreaking up the spectral dif-ferences into any number ofindividual colours. The processwas patented in 1995 and hasbeen available for use by KBAsince 1998. At the same time,a suggestion was made to com-bine a high-sensitivity spectralphotometer with a densitome-ter. The dual-purpose measur-ing head (illustration above)was born.

More for your money

Anyone opting for a KBAsheetfed offset press today, andspecifying Densitronic S as acontrol accessory, reaps thebenefits of 10 years' experiencein densitometric and spectralcontrol. The deciding factorfor many is the built-in optionof first learning how to meas-ure only density and how toutilise this knowledge to maxi-mum effect. With the support ofinstructors and press engineersfrom KBA and Lithec, userscan then familiarise themselves

23

Densitronic S

Standardisation, despite all thepractical problems involved, isan invaluable common denom-inator between prepress andpress and promotes more uni-form prints than would bepossible without any commu-nication. For this reason, KBADensitronic S features numer-ous functions to support stan-dardisation, e.g. the ability tostore density standards forEuroscale and special colours,and to monitor full solids andscreens of such colours. Refer-ence density values can also betransferred directly from theoriginal and modified in thezones wherever the press oper-ator thinks necessary. Dot gainon standard or non-standardmeasuring strips can be dis-played at any time and trans-ferred to pre-press in eitherprinted or digital form. HereDensitronic S reveals a flexi-bility unparalleled by anyother measuring device. Forthis reason it is often used forscientific research and pressacceptance.

Nevertheless: control strips andtheir measuring values primarilystand for one thing - namelyfor themselves! Investigations atthe FOGRA Institute in 1989/1990 [1] showed that measuringstrips are not particularly rep-resentative of the entire printedsheet. Stochastic fluctuationscaused by ink transfer, andsystematic deviations causedby ink fade and plate changesetc., can accumulate into com-paratively substantial deviationsof up to 0.4 density for anaverage value of 1.6. Even backthen there was talk of measuringand controlling print qualityduring production, and whereit is measured by customers,namely directly in the printedimage.

Two obstacles, however, had tobe overcome before this goalcould be achieved:

1. A sensor – if possible aspectral photometer – had to be developed that was capable of functioning underpress-room conditions;

How the dual-purpose measuring head works

Communication in a standardised workflow

Pre-press communication with colour values

Press room Pre-press

Density/press characteristics

Curve-compensated films and plates

Press room Pre-press

L*a*b* values from printed test charts

L*a*b*-compensated films andplates, L*a*b* reference values

Further information can be requested by phone on +49-(0)8025/99720 or by e-mailfrom [email protected]

The spectral control processsubsequently calculates the keyadjustments necessary at eachindividual inking unit from thedifference spectra. Thus, insteadof abstract suggestions for ad-justment in the L*a*b* colourspace, the press operator re-ceives practical recommenda-tions for each Euroscale colourand special colour, and can im-plement these recommendationsautomatically, at the touch of abutton.

In future, reference values willalso be retrieved from prepressand transferred to the DensitronicS system via CIP3 files, for ex-ample (illustration below). Cur-rent and future KBA customerswill be able to take advantage ofthese features as soon as pre-press bridges the technology gap.


24

The product

Corrugated board is produced through thermo-mechanical remodellingof a flat web into the typical flute form, which is then fixed betweentwo further flat webs at the flute peaks by means of a starch glue.

This structure achieves an efficient padding and damping effect,offering a high degree of product protection with reduced materialconsumption and low weight. Through the combination of differentpaper types and grammages, it is possible to vary the specificqualities and strength properties of the resulting corrugated board.In fact, this variability is one of the essential advantages of corru-gated board over alternative packaging materials.

The raw materials can generally be divided into two categories:primary-fibre and secondary-fibre (recycling) papers. The high-quality primary-fibre papers are produced from chemical pulp,whereas secondary-fibre papers are obtained by recycling wastepaper. Both paper types are available in a variety of grammages.

The product and flute type are further factors in the equation foran ideal packaging and can similarly be matched to the demandsof the individual case. Qualified customer/packaging advisorsassist users in the selection of the most suitable combinations.

Further distinguishing properties are the flute grade (coarse,medium, fine) and the number of flute layers making up the finalboard. The flute grades are defined more specifically by the fluteheight and the peak-to-peak repeat intervals, and are typicallyclassified as C, B, E, F or G-flute.

Flute types

Corrugated

The family-run enterprise Carl Eichhorn GmbH Wellpappen-werke has been developing special packaging concepts for itscustomers for almost 150 years now, elaborating solutions foreven the most complex tasks and applications. The 260 em-

Corrugated board – a substrate with potential

1

2

31 Outer liner 2 Flute 3 Inner liner

H▼

▲

▼▲ R

Type Height Repeat Flutes (mm) (mm) per m

C-flute 3.66 7.95 126

B-flute 2.50 6.50 153

E-flute 1.16 3.50 285

F-flute 0.75 2.40 415

G-flute 0.55 1.80 555

Depending on the strength requirements it is possible to combineseveral corrugated layers into a single final product. The most com-monly used type of corrugated board is the single-wall type.

Types of corrugated board

Corrugated board is furthermore an ideal advertising medium, ashigh-quality flexo or offset printing transforms it into an attractivesales packaging or display. The corrugated board is thus able to"call out" to consumers from the shop shelf, to draw attention andat the same time to provide information on the product to be sold.

In flexo printing on corrugated board, a distinction is made betweenpre-printing and post-printing. Pre-printing means that a paperweb is printed in advance on a flexo press and subsequently usedas the outer liner when the final corrugated board is produced.Pre-printing is especially suitable for high-volume production.

With post-printing, on the other hand, the flexo printing is doneon the finished corrugated sheet, whereby we distinguish betweeninline and offline print. Inline print means that the printing isdone on a single line together with the conversion processes toproduce the final packaging. With offline print, printing and con-version are done on separate machines.

If especially high-quality print is required for a corrugated pack-aging, then it is possible to turn to an offset process. In the past,however, offset-printed corrugated packaging could only be pro-duced in two separate stages. The first step is to print a sheet onan offset printing press. This sheet must then be laminated with asingle-face corrugated board. Following lamination, a certain waitingtime may be necessary before the corrugated board can be passedon for conversion and finishing. Such a production method is bothtime-consuming and cost-intensive.

The development of G-flute has today introduced a favourable al-ternative to lamination. G-flute is a single-wall corrugated boardwhich can be printed directly in an offset printing press.

Single-face

Single-wall

Double-wall

Triple-wall

ployees at the locations Jülich-Kirchberg and Brechen (Limburg/Lahn) today produce approx. 150 million m2 of corrugatedboard every year, generating an annual turnover of around€ 60 million.


25

Corrugated

G-flute

Corrugated board specialists Eichhorn launched G-flute in 1999 asthe thinnest corrugated board in the world and as the first corrugatedboard on the market which can be printed directly in an offsetprocess. In the meantime, G-flute enjoys a high level of accept-ance and has been able to expand its market share continuously.The G-flute board is produced on a high-performance corrugatingplant. The grammages range from 320 to 550 g/m2, correspondingto total heights between 0.82 and 0.98 mm. G-flute is also offeredin a number of different paper combinations. For direct offsetprinting, at least one side comprises a double-coated kraftliner orduplex paper. For products requiring perfecting, the inner liner isalso a coated paper.

In comparisons with folding carton board (GD II) of a comparableweight, G-flute offers significantly greater strength (flexural rigidity,bursting strength, resistance to crushing). Test results for flexuralrigidity are shown here as an example:

G-flute 410g/m2

G-flute 450g/m2

GD II 400g/m2

GD II 450g/m2

Nmm200

150

100

50

0

length

crosswise

Flexural rigidity (to DIN 53121)

Compared to laminated offset-printed corrugated materials,direct printing on finished G-flute sheets brings consider-able cost savings by eliminat-ing the whole additional lami-nation process.

G-flute can be printed on anysheetfed offset press with a low-curvature sheet path, though thepresses of the KBA Rapida se-ries are especially suited. Unlikethose from other manufacturers,the KBA presses do not demandany additional or special acces-sory kits to be able to handlethe corrugated board. Very goodprint results have been obtainedwith the compressible printingblanket ContiAir Prestige, whichwas developed in the course ofintensive cooperation between thecompanies KBA and ContiTech.(For more details, see also pages26 and 27).

Thanks to the excellent resultsachieved with direct, two-sidedfull-colour offset printing, G-flute product packaging has beenable to establish itself ever more

Product examples

firmly on retail shelves. In par-ticular the demands of the brand-name manufacturers – eye-catching and economical directprinting of corrugated board,without an intermediate lami-nation process, also for low-volume orders – are being metadmirably. Summing up, G-fluteis better able than any of itsalternatives to satisfy the threeessential demands placed onpackaging:

• low weight• high stability• attractive appearance

A further advantage of direct off-set printing over flexo printingon corrugated board, alongsidethe quality, is the reduced outlayfor printing plates. This is anespecially interesting factorwhen printing short runs.

Further information can be requested by phone on +49-(0)2461/6990 or by e-mailfrom [email protected]


26

A subsidiary of Continental, thewell-known manufacturer oftyres and automotive parts,ContiTech has been a leadinginternational supplier of rubberblankets for sheetfed, commer-cial web and newspaper offsetpresses for many years, andboasts the pole position inEurope. Among members ofthe printing trade the companyhas established a reputation forongoing innovation, not leastthrough long-standing ties withKBA and other top press man-ufacturers directed at develop-ing and optimising new typesof blanket to address ever moresophisticated demands in theoffset market. Which is whyContiTech has been workingclosely with engineers at allour main facilities in Germany:on sheetfed offset presses inRadebeul, newspaper presses inWürzburg and Compacta com-mercial web offset presses, whichfeature minigaps on the plate andblanket cylinders, in Frankenthal.

Members of the graphic artsindustry are already familiarwith Conti-Air blankets: the FSR,Crystal, Dot Star and Ebony forsheetfed presses, Blue Steel andBlack Steel for minigap presses,Evolution and Synchro forshaftless newspaper presses,and Prisma for packagingpresses. Within a few monthsof hitting the market the newConti-Air Prestige, an “all-roundwonder blanket” as ContiTechhas modestly dubbed it, hasalready made a name for itselfamong packaging printers and

Blankets

In the print media arena there is an emerging emphasis on closecollaboration between press and consumables manufacturers toexpand the applications of modern sheetfed offset presses. TheConti-Air Prestige, a new rubber blanket developed jointly byContiTech Elastomer-Beschichtungen in Northeim, Germany, and

Conti-Air Prestige performs equally well with paper and E-flute

is now used in a large numberof printing plants.

Official premiere at Ipex

The Conti-Air Prestige’s un-paralleled ability to handle awide range of stock thicknesseswas demonstrated to the tradein a similarly versatile Rapidasheetfed offset press at Ipex2002. The ten-colour Rapidamedium-format perfector press

for five-back-five – a pure paper-printing version with no specialboard facilities – printed 0.94mm(38pt) G-flute at a speed of13,000 sheets per hour. Thesheets were later converted intocarrier cartons on the Bobststand. After this demonstrationthe press was converted to 5/5perfecting in less than 10 min-utes and printed a 16-pagebrochure in just as good a qual-ity on 150gsm (96.5 lb) stock.

Thanks to the Rapida’s univer-sal gripper pretensioning system,no substrate-specific adjustmentswere needed when switchingfrom board to paper, or vice versa.

Challenging wish-list

One hundred years ago ContiTechunveiled the first of many rev-olutionary advances for thebenefit of the automotive in-dustry. 40 years ago it regis-

CO

NTINENTAL

.C

O

NTINENTAL

.

our specialist sheetfed offset plant in Radebeul, is a prime exampleof the benefits such user-driven collaboration can bring. The newblanket promotes a high-quality print on a broad spectrum ofstock ranging from 180gsm (115.75 lb) paper to rigid 1.5mm(60pt) E-flute.

Cross section: Printed G-flute

Cross section: Printed F-flute

Cross section: Printed E-flute

Feature Conventional Conti-Air Prestigecompressible blanket compressible offset blanket

Gauge loss 0.02 - 0.03 mm 0.02 - 0.03 mm

Load (kPa) 1500 at 0.20 mm indentation 1350 at 0.50 mm indentation

Indentation required 0.13 - 0.16 mm 0.25 - 0.30 mm

Thickness 1.70 or 1.95 mm 2.3 mm

Ink compatibility UV/hybrid or oxidative UV/hybrid and oxidative

Stock compression ~ 14 % 0 %

Reduction in stock strength 34 % 0 %

Register accuracy poor on large formats very good on all formats

Dot distortion severe on tail end undetectable

The new Conti-Air Prestige blanket versus a conventional blanket


27

Blankets

tered the first patent for theproduction of compressiblerubber blankets incorporating amicroporous layer in the middle.This laid the foundations forContiTech’s awesome expert-ise in the development of newand unusual types of blanket.

Among packaging printersthere has long been a call for a‘universal’ blanket. This callhas become louder since KBAdemonstrated direct sheetfedoffset on corrugated in early1999, opening up new applica-tions for high-quality packaging.More specifically, there was aneed to eliminate the dreadedwashboard effect on corrugatedand to print a good offset qual-ity – even in large solids – onheavier types of corrugated thanG-flute, such as F- (1.2mm/48pt)and E-flute (1.5mm/60pt). Ontop of this, packaging printerswanted to exploit new optionssupporting high-quality inlinecoating with hybrid inks andend-of-press UV coating, andwere keen to print corrugated,board and heavyweight paperone after the other, withouthaving to change the blanketsin between.

So the wish-list that KBApassed on to ContiTech, its de-velopment partner, was prettychallenging. Nonetheless Conti-Tech came up with a solutionin a relatively short space oftime: the Conti-Air Prestige,based on a compressible layerpatented in 1964.

Unparalleled compres-sion characteristics

The secret of the Conti-AirPrestige is that it can adapt tothe surface structure of virtuallyall the types of substrate cur-rently used in offset packagingprinting. The cross-section andclose-up at the top and centreof this page show what makesthis possible. First, the surfacecompound of the printing sur-face is relatively soft (shore Ahardness 55°). Second, the com-pressible layer beneath, whichhas a compressibility of around20% and at 1.55mm (0.06") is

CO

NTINENTAL

.C

O

NTINENTAL

.

Cross-section of a Conti-Air Prestige blanket showing the compressible layerof pre-pressurised sealed cells

How the 1.55mm compressible layer functions:above: no pressure exertedbelow: pressure exerted

Quality check on a Conti-Air Prestigeblanket in a Rapida 142 size 6 (56")press – there is no perceptible slurring or doubling

Compressibility of Conti-Air Crystal, FSR and Prestige blankets. The new blanket has a much wider compression range

CONTI-AIR PRESTIGE Benefits in brief

• extremely high compressibility (20% vs 6% for normal blankets)

• pre-pressurised sealed cells

• unparalleled deformation capacity with no memory effect

• compressible layer 1.55mm thick (normal blanket: 0.50mm)

• compressible layer adapts to substrate surface

• micro-ground surface for high print quality

• printing surface hardness 55°shore A

• two-layer low-stretch carcass

• no additional compressible underpacking necessary

• uniformly smooth impression across entire surface

• minimum substrate compression during impression

• excellent registration even on thick board

• no printing length corrections required

• no pre-impression compression required

• minimum pressure on stock,flat sheet delivery

• suitable for all sheetfed presses

• suitable for paper and corrugated board

Further information can be requestedfrom Albrecht Szeitszam by phone on +49-(0)5551/702-289 or by e-mail under [email protected]

Indentation in mm CONTI AIR CRYSTALCONTI AIR FSRCONTI AIR PRESTIGE

1400

1200

1000

800

600

400

200

0

kPa

0,00 0,05 0,10 0,15 0,20 0,25 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 0,70 0,75

Face compoundAdhesive rubber layer

Compressible layer

Adhesive rubber layer2nd layer: cotton fabricAdhesive rubber layer3rd layer: cotton fabric


more than three times as thickas in a conventional blanket,withstands pressure well andreacts much more slowly to anincrease in pressure.

Another new feature of theConti-Air Prestige is that it canbe used with mineral-basedinks, UV inks and hybrid inksalike. Furthermore, tests haveshown that it is unaffected bydouble sheets and sheet jams,even of thick board.

Quality measurements on aRapida 142 size 6 press have re-vealed that the Conti-Air Pres-tige promotes a high registerprecision even on large-formatcorrugated, which tends to‘work’ as it is printed. This isbecause the blanket supports thesheet in such a way that there isno need to adjust the print lengthduring a print run. The surfaceof the rubber blanket is finelyground to ensure that the sheetsare released cleanly. Ink transferis also clean, there is less build-up of ink, dots are sharp andlarge solids are printed in aneven better quality because thesheets lie more smoothly. Thelow level of compression duringprint impression also means thatthe printed sheets are deliveredneatly and the delivery stackstays flat.

New options for printing packaging

In a modern-day package print-ing plant all the production se-quences must be absolutely sta-ble, affordable and reproducible,and perform to high quality stan-dards. The Conti-Air Prestige,which in KBA sheetfed pressesis already used to great effect onF- and E-flute, offers offset pack-aging printers the chance to ex-plore new markets without hav-ing to install new kit. KBA andContiTech will continue to testand optimise the blankets in theinterest of users worldwide.

28

One of the reasons for the lackof colourful advertising ontransport packaging is to befound in the relatively compli-cated and costly process of pre-printing and subsequent lamina-tion onto a corrugated carrier.On top of this, the shorter runswhich are so common partic-ularly for transport packagingserve to give costs anotherpowerful boost.

An attractive and favourablypriced alternative is offset printdirectly onto the corrugatedboard. The advantages over di-rect flexo printing on corrugatedmaterials are to be seen on theone hand in the higher qualityattainable, but above all in thesignificantly lower costs for theprinting formes. Several impor-tant factors influence high-qualitydirect offset printing on corru-gated boards (F and G-flute):

Inks for corrugated board

The vast majority of the transport boxes in which even expensivelymanufactured products make their way to retail outlets are stilltoday rather sad-looking affairs. Brown kraftliner, with at most a

Inks for direct offset printing on corrugated boards

• Printing press with corresponding technicalcapabilities,

• Printing blanket with an especially pro-nounced elasticity,

• Substrate(preferably a light-colouredliner with suitable coating)and

• Printing inkswith special properties.

The focus of attention for oursheetfed offset department ispackaging printing, wherebywe are known especially as asupplier of low-odour andodourless printing inks, labelinks and concentrates for themixing of special colours.

The task of developing a print-ing ink suitable for direct print-ing on corrugated board was forus an interesting challenge.

The central demand placed onsuch a printing ink is the abilityto eliminate so-called "wash-board" effects (fig. 4) as far aspossible. This phenomenon isthe result of the differences inprinting pressure between thepeaks and valleys in the bodyof the corrugated board.

All the development partnersinvolved – whether press, blan-ket, corrugated board or inkmanufacturer – have concen-trated their efforts on suppress-ing these effects to the maxi-mum possible extent.

Before we consider how theink can make a positive contri-bution to successful print re-sults, we should first recallbriefly the composition of an

offset printing ink. Printing inkscomprise pigments, which de-termine the colour tone, along-side resins to enable the pig-ments to adhere to the paper,and drying oils and alkyd resins,which are necessary to dis-solve the resins and permit for-mation of an ink film. Mineraloils are also used to dissolvethe resins and for thinning. Avariety of additives, furthermore,serve to accelerate drying, toenhance rub resistance and toachieve other specific properties(see table on the right-handpage).

Resins, drying oils, alkyd resinsand mineral oil, in turn, are gen-erally already mixed togetherat an initial stage to predeter-mine the most important prop-

single-colour bar code and product designation, is generally theorder of the day. Vast potential advertising surfaces are simplywasted (figs. 1-3).

Fig. 1

Fig. 2

Fig. 3 Fig. 4


29

Inks for corrugated board

erties of the final product. Thisintermediate mixture is thus, soto speak, the heart of the print-ing ink. Through selections ofdifferent resin combinations andby varying production condi-tions, the ink manufacturers areable to exploit a practically un-limited range of options for thedevelopment of these ink bases.

Two demands must be placedon the printing ink to eliminatethe washboard effects:

Despite the varying pressures,the ink must be transferredevenly, both in the screens andin solids. Figure 5 illustratesthe problem and indicates theproperties the ink should have.In this admittedly exaggeratedrepresentation, it can be seenhow the dots on the blanketcome into contact with the cor-rugated board. Whereas the inkdot above the flute peak istransferred fully, a dot meetinga flute valley will achieve onlypartial contact with the sub-strate surface. If light and darkspots are to be avoided, there-fore, it is necessary to ensurefull transfer of the ink alsowhere there is no full contact.This demand can be met betterby an ink which displays amore elastic behaviour.

If we compare in our minds adot-sized amount of chewinggum and an equivalent amountof hand lotion, then this leadsto an immediate understandingof the point. Whereas the chew-ing gum would require onlyvery minimal contact to theboard to progress from no trans-fer to full transfer, the lotionwill only ever be transferredin those areas where there isdirect contact.

Similar principles for ink transferapply also when printing a solid(fig. 6). In this case, however,the ink must also spread aftertransfer, a process which is notexactly encouraged, of course,by an excessive elasticity.

The task, therefore, is to findthe ideal compromise betweenthe elastic and flow character-istics to enable both demandson the ink to be met optimally.Determination of the optimumrecipe was only possible on thebasis of practical print tests, asthe complex behaviour of print-ing inks during the printingprocess could not be predictedfrom calculated values alone.

The conclusion:Direct offset printing on corru-gated board is able to achieve ahigh quality, whereby the inkused contributes significantlyto successful results.

Raw materials

• Pigment• Resin• Drying oils/alkyd resin• Mineral oil• Additives

Tasks

• Colouring• Adhesion to the paper• Dissolving of resins, formation

of an ink film• Dissolving of resins, thinning• Acceleration of drying,

rub resistance, etc.

Composition of printing ink

Figs. 5 and 6

Ink

Ink

Further information can be requested from Dr. Hans-Peter Seyer by phoneon +49-(0)69/7802-282 or by e-mail under [email protected]

Blanket cylinder

Impression cylinder

Board surfaceBlanket


30

More than 90% of foodstuffssold on the Western Europeanmarket are packaged. The sheet-fed offset package printingprocess is primarily used forprinting folding boxes and wrap-pers. The share of primary pack-aging has risen sharply over thepast years. Under normal cir-cumstances – and to be on thesafe side – the foodstuffs comeinto contact with only the un-printed inner side of the packag-ing. But this is obviously notenough to protect organolepti-cally sensitive package contentsagainst becoming contaminatedby constituents of the substratesand printing inks. Investigationshave revealed that it is highlyfeasible for foodstuffs to be-come polluted through packag-ing material.

Low-odour inks

The necessity to protect the con-sumer demands that packagesdo not lead to contamination ofpackaged foodstuffs. Conse-quently, printing inks and var-nishes are not allowed to con-tain any substances that canbe transferred to the packagecontents in quantities that ex-ceed the stipulated limits. Therelevant legislation lays downthat it is the manufacturers andmarketers of foodstuff packages– and not the printing ink man-ufacturer, for example – whobear responsibility for ensuringtheir packages conform. As aresponsible partner of the man-ufacturing industry, the huber-group can now put the printingindustry and its customers on asure footing thanks to its newlow-migration and low-odour,sheet-fed offset inks.

CORONA®-MGA:A new dimension for foodstuff packaging

Invisible setoff and migration identified asthe main sources of risk

Interaction between packagingand package contents can comeabout in three different ways.The first of these is related tothe production process: whenin the stack or on the reel, theunprinted side of the boardcomes into contact with theprinted side under it, thus mak-ing it feasible for colourless,and therefore invisible, ink

constituents (such as solvents)to be transferred by means ofwhat is termed "invisible setoff".These substances can then betransferred (migrate) from theunprinted inner side to thefoodstuff. Secondly, low-mo-lecular constituents can alsomigrate through the substrate.The third mode of interactioninvolves the transfer of volatilesubstances in the enclosed airspace of the packaging to thefoodstuff, thereby contaminat-ing the foodstuff.

Whereas the ink industry hadfor a long time concentrated itefforts primarily on avoidingchanges to the smell and tasteof foodstuffs caused by thepackaging, the measurementand minimisation of substancetransfer through invisible setoffand migration is relatively new.A resolution of the EuropeanCouncil in this regard is cur-rently in preparation, whichwill regulate the printing inksput to use.


31

Low-odour inks

Food regulations placefull responsibility at thedoor of the printer

Provisions for the protection ofthe consumer against healthhazards arising from contami-nated foodstuffs have been laiddown for the German market inthe German Food and ConsumerGoods Act (LMBG). Amongother things, this Act providesthe fundamental guidelines forthe design of food packaging,guidelines that likewise applyto tobacco products and cos-metics. Of paramount importanceto this particular area are twoparagraphs of the LMBG. § 30,Section 1 demands a "Physio-logically non-objectionablecharacter" and consequentlyforbids the manufacture of con-sumer goods – such as packag-ing – that, due to their materialcomposition, in particular due totoxicologically active substancesor contamination, are likely tobe detrimental to human health.

§ 31, Section 1 for its part dealswith the "Transfer of substances(migration) to foodstuffs" andstates that "It is forbidden touse articles as consumer goodswithin the meaning of §5, Sec.1"(in our case, packaging) "forcommercial purposes or tomarket them for such purposesin a manner by which sub-stances are transferred fromsaid articles to foodstuffs ortheir surface; excluded fromthis are components that areharmless with respect to health,odour and taste and that aretechnically unavoidable".

The requirements laid down inthese two paragraphs relate tothe final product "packaging"and not to its constituent com-ponents such as substrates,printing inks and varnish films.For this reason, under Germanlaw relating to foodstuffs, it isthe manufacturers of packagingand the marketers who bear fullresponsibility for their prod-ucts: when it comes down to it,then, the printhouses, too.

Preventing a level of substancemigration that exceeds specified

limits – as have been found inthe latest investigations intofolding boxes for foodstuffs –would have required a func-tional barrier; for example, aninner bag or laminated board.

On the safe side with low-migration and low-odour inks

With the migration problemspecifically in mind, the peoplein the research and applicationdepartments of the hubergroupcompanies have channelledtheir efforts into finding a solu-tion and have come up with one.Recently, the companies launcheda special and already patentedproduct series for the packageprinting sector:

• CORONA®-MGAoffset inks

• ACRYLAC®-MGAdispersion varnishes

The last three letters indicatethat these products are theworld's first and so far onlylow-migration and organolepti-cally neutral, sheet-fed offsetinks and varnishes.

CORONA®-MGA inks are thebest technology available forprinting folding boxes forfoodstuff packages. They con-tain only constituents with aminimum of migration potentialand display neutrality towardspackaged foodstuffs with respectto odour and taste. The solventemployed is a special fatty acidester that is classified as non-toxic and that is scarcely capa-ble of migrating even throughfolding boxboard due to itshigh molecular weight. As theresults from tests carried out byan independent institute haveshown, the limit of 10 mg/kg infat or fat simulant laid downfor global migration is under-shot by a long chalk. SinceCORONA®-MGA inks set quick-ly, absorbent substrates are re-quired. With their sheet-fed offsetink system CORONA®-MGA,varnished inline with the dis-persion varnish system ACRY-LAC®-MGA, the packaging inkspecialists of the hubergroup

have succeeded in solving themigration problems involvedwith folding-box printing with-out the need for an additionalfunctional barrier. And there areno shortfalls in relation to thehigh demands of the industrywith respect to gloss, mechani-cal loadability and sliding fric-tion. What's more, the ink sys-tem also offers an extra benefit:conventional sheet-fed offsetinks frequently cause swellingwhen they come into contactwith OPP films, which areused, for instance, to packagecigarettes. This process makesthe packaging look unsightly. Itis brought about by mineraloils that penetrate the polymermatrix. This cannot happenwith MGA inks. However, theirchief advantage is without doubtthe fact that they can be usedto print primary packag-ing that fulfils all statu-tory requirements, whilefully utilising the eco-nomic and qualitativeadvantages of the sheet-fed offset process.

What the Food and Con-sumer Goods Act describesas being "technically un-avoidable" with respect to the

contamination of foodstuffsmust surely require reassess-ment now that CORONA®-MGAinks have been launched on themarket. The benchmark bar hasnow been raised considerablyhigher. It's a good thing, then,that the latest state of the art isstill affordable.

If you would like further informationon this subject, please send a fax to+49 (0)89 9003-535 or an e-mail [email protected] quoting the keyword"CORONA®-MGA".


32

Innovative refinement

Pearlescent inks offer special opportunities for the creative de-sign of print jobs. To date, such pigments have been employedpredominantly in gravure, flexo and screen printing, and inconjunction with integrated varnishing units, in offset printing.Thanks to new ink production processes, they can now also beused in the inking units of offset presses. Pearlescent pigments,that enable glacé and iridescent colour effects in the print, en-hance every print result. The kaleidoscope of colours and ele-gant colour shades that develop from different viewing anglesare just two of the many effects that appeal to the consumer –"if it doesn't catch the eye, the feet will walk on by".

Pearlescent effects in offset printing:Finishing in the inking unit

Pearlescent pigments(iriodine):

Pearlescent pigments are oxide-coated platelets, whose typicalpearlescent effects developthrough interference (wavetransmission). These effectshave been exploited now formore than 30 years. Whereasearlier finely ground fish scaleswere used to produce these ef-fects, we now use platelet-typepigments which not only pro-duce better effects, but alsomake them far easier to obtain.The new ink production process-es already mentioned aboveand the sharp increase in de-mand for inexpensive finishingtechniques have helped pushthis technology to new heights.

Pearlescent pigments in offset printing:

Pearlescent effect pigments upto 25 µm in size can be used inconventional offset printing.

Larger pigments cannot be op-timally transferred in the ink-ing unit and they are used inspecial varnishing systems(chambered doctor blade) inoffset printing or in the print-ing processes mentioned above.

A special rubber blanket is rec-ommended for printing withpearlescent ink, in order toprevent rapid build-up of thepigments on the blanket. Sucha rubber blanket is requiredonly for the particular inkingunit in which the pearlescentink is being printed.

Depending on the type ofpress, it has proven advanta-geous to operate outside theusual standard with regard toinking and inking-unit setting.

In contrast with gravure print-ing, it is not possible to repro-duce genuine halftones in theoffset process. In offset, halftonegraduations from light to darkare reproduced in the form ofscreening. When printing withhalftone image areas, the screencount should be no finer than34 lines per centimetre. Other-wise there may be problemswith transfer of the pigments.

Pearlescent inks in offset printing:

The consistency of the pearles-cent inks used for offset printingcorresponds to that of today'stypical standard inks. Withregard to their composition,pearlescent inks, like all print-ing inks, are made up of pig-ments, vehicles and additives.The colour pigments can betransported and printed on theimage carrier to produce a last-ing application only by meansof the colour carrier (vehicleand additives). The effects ob-tained with pearlescent inksare multifarious and depend onthe pigment. Extraordinarykaleidoscopes of colours andeffects can be achieved by com-bining various colour shadesand/or by priming or overprint-

G-Welle G-Flute Microondulado-GG-Cannelure Cartone microonda onda G

Perlglanzfarbe Lithoyellow und ACRYLAC Perlmutt von Huber Farben München!Nacreous ink Lithoyellow and ACRYLAC nacre from Huber Farben München!Inchiostro semilucido Lithoyellow e ACRYLAC madreperla da Huber Farben München!Encres brillantes de Lithoyellow et ACRYLAC nacre de Huber Farben München!Color nacarado Lithoyellow y ACRYLAC nacar de la firma Huber Farben München!


33

Innovative refinement

✹ ✹✹ ✹

✹ ✹✹ ✹Application example:

ing. There are ten selected sep-arations specifically for offsetprinting using the inking unit.The effect also depends on thesize of the pigment particles. Ifpossible, the separations andpigment sizes required for aparticular application should beselected in co-operation withthe ink manufacturer. The inksare then delivered to the print-house ready for printing.

Substrates:

All materials used in offsetprinting can be printed withpearlescent inks. The matterand smoother a surface, thebetter the effect pigments areable to reveal their typicalcharacteristics. It is advanta-geous if the substrate has ahigh level of opacity and lowtransparency.

Finishing:

As with all common printingprocesses, the use of pearlescentinks and varnishes has absolute-ly no negative consequenceswith respect to finishing. Var-nishing, follow-up printing andoverprinting (also using differ-ent printing processes), heat andcold sealing and laminationcan be carried out in the usualway. There is no need to fearany negative effects from thepearlescent pigments used.

Environmental protection regulations:

One highly significant plus pointof pearlescent inks and var-nishes is their high degree ofenvironmental compatibility, afactor which is exceedinglyhelpful to the printing industry

when it comes to fulfilling thepertinent environmental pro-tection regulations.

Pearlescent pigments complywith the purity requirements ofthe Federal German HealthBoard (Bundesgesundheitsamt– BGA) and the FDA (AmericanFood and Drug Administration)with respect to the limits forheavy metals content and theconcentration of aromaticamines. They are approved foruse on foodstuff packaging andare classified as non-toxic andchemically inactive.

All of these characteristics arevital in view of the high re-quirements set with respect tothe harmlessness of productsfrom the printing-ink industry.To be specific, this relates to,among other things:

Further information can be requested by fax on +49-(0)89/9003-1328 or by e-mailfrom [email protected].

• the disposal of left-over inks• the cleaning of formes and

inking units• the recycling of print products

and, in general, the disposalof other printing wastes thatarise.


34

Barrier coatings in packaging printing

When used for the coating offast-food packaging, dispersionvarnishes are expected to beresistant to water, grease, edibleoils, acetic acid and to soda.Corresponding testing is donein accordance with the standardDIN EN 646 (test institute cer-tificates can be provided).

The barrier coatings are appliedin offset, preferably via aniloxsystems, with a viscosity of 50seconds, in flexo with a viscos-ity of 25 to 20 seconds and ingravure presses with a viscosityof 18 to 16 seconds (4 mm DINcup at 20°C). VEGRA suppliesthe varnish either at the specifi-cally required viscosity or al-ternatively at an increased vis-cosity of 80 seconds for indi-vidual dilution with water (fig. 1).

In packaging printing, the demands placed on dispersion varnishesoften go beyond typical properties such as gloss, rub resistance,

VEGRA® barrier varnish 1315: Water and grease repellency in offset,

The characteristic parametersfor the water and grease-repel-lent properties of the barriercoatings can be seen from theabove tables and graphs for anaverage application of 4 g wetfilm/m2 at the correspondingviscosity.

If the substrate is extremely ab-sorbent, it may be necessary toconsider double-coating.

The Cobb test is performed todetermine the so-called Cobb120value, which indicates the waterabsorption of the substrate ingrams per square metre over anexposure time of 120 seconds.For the three different fields ofapplication for the VEGRAbarrier varnish, the water up-take of the tested kraftliner isless than 10 g/m2 (fig. 2).

The Kit test determines the bar-rier effect against grease and oils.The scale runs from 1 to 12,whereby 12 represents a verygood barrier effect and 1 a verypoor barrier effect. Measuredvalues in the range 11 to 12 forall three fields of application ofour barrier coatings indicate avery effective grease barrierwhich is perfectly adequate formost uses (fig. 3).

The European standard DINEN 646 describes methods forthe testing of coloured paperand board which necessarilycomes into contact with food-stuffs. A renowned foods insti-tute has tested our barrier var-nish 1315 on the basis of thisstandard and has confirmed itssuitability for applications in-volving direct contact withfoodstuffs.

The barrier varnish 1315, aswell as the thereby protectedoffset ink, can be consideredresistant on GD 2 board for thecriteria listed in the table.

ecological compatibility, etc., requiring also that coatings be safefor use in direct contact with foodstuffs.

Fig. 1: Dilution curve VEGRA® dispersion coating 1315

80

70

60

50

40

30

20

100 5 10 15 20

Amount of water (% by weight)

Fig. 2: Cobb120 value as dependent on viscosity, application 4 g/m2

12

10

8

6

4

2

0

Cob

b120

val

ue (g

/m2 )

50 25 – 20 18 –16Viscosity in seconds (DIN 4 mm, 20°C)

Water to be added to varnish 1315 / 80 seconds (%):

approx. 3% approx.12% approx. 20%


35

Barrier coatings in packaging printing

Viscosity setting

The viscosity of the barrier var-nish 1315 is modified by stirringin water, either manually or au-tomatically. The appropriateamount of water can be readfrom the dilution curve (fig. 1).

When processing larger amountsof varnish, and to maintain aconstant varnish application, itis recommended to integrate anautomatic viscosity control sys-tem, for example the Viskomat2000 from the company EASY-LAC® (photo right).

The system measures the var-nish viscosity in the applicationsystem continuously and regu-lates dilution either with freshwater or preferably with thevarnish-water mixture which isaccumulated automatically dur-ing the coating process. Thisserves to minimise waste andthus makes an active contribu-tion to environmental protection.

The VEGRA® group of com-panies was founded in 1979and develops various environ-ment-friendly products whichare bio-degradable and in mostcases suitable for recycling.

The product range covers dis-persion and UV varnishes,dampening additives, cleaningagents and general printing aids.

Our subsidiary companiesmanufacture filtration systemsand special rollers for low-al-cohol and alcohol-free printing.Contact: [email protected]

Further information can be ob-tained via the Internet at thefollowing addresses:www.vegra.dewww.easylac.de

Author:Albert Uhlemayr, President

flexo and gravure printing

Fig. 3: Kit value as dependent on viscosity, application 4 g/m2

9.0

9.5

10.0

10.5

11.0

11.5

12.0

0 10 20 30 40 50 60

Viscosity in seconds (DIN 4 mm, 20°C)

Kit v

alue

Product resistance of VEGRA® barrier coating 1315 andthe thereby protected offset printing ink on GD 2 board in accordance with DIN EN 646, method A (long-term contact)

ResistantWater

Soda DilutedOlive oilagainst solution acetic acid

Printed 5 5 5 5front side

Reverse 5 5 5 5

Ratings between 1 and 5 points were given, whereby 1 standsfor no resistance and 5 for maximum resistance.


The properties of the packag-ing are also influenced stronglyby the coatings used. It is nocoincidence that some 90% ofall packaging is varnished. Anunblemished, scratch-free sur-face is a prerequisite for thedesign of the packaging to beable to unfold its full potential.Matt and gloss effects, pearles-cent finishes and metallic var-nishes are effective means tounderline the packaging design.In fact, this is often the onlypossibility to achieve a certaindemarcation from competitorproducts at the point of sale.

The most commonly used coat-ing system in packaging print-ing is water-based dispersionvarnish. The reasons for thisare to be seen in the simpleprocessing in conjunction withconventional offset inks, thefast drying and above all the di-versity of properties and spe-cial properties which can beachieved with this system.

Drying of dispersionvarnishes

The most frequently exploitedadvantage of dispersion var-nishes is the fast drying, whichmeans that the prints can usuallyalready be passed on for furtherprocessing on the same day.One essential aspect here isthat the dispersion varnish is atthis time not merely dry to thetouch, but has in fact alreadyattained its final rub resistance.This is a result of the composi-tion and the drying mechanismof a dispersion varnish. Unlikeoffset inks (and oil-based var-nishes), the dispersion varnishrequires no subsequent oxida-tive drying. The process of filmformation is purely physical.

In the liquid state, the polymersof the binder are suspended inthe "solvent" water. As soon asthe water is absorbed into thesubstrate, the polymers beginto fuse. There is no chemicalreaction, however. Alongside

the speed of the process, thisbrings another decisive advan-tage. Dispersion varnishes con-tain no reactive constituentssuch as monomers or initiators,which necessitate special la-belling in the case of UV var-nishes, for example. At thesame time, there are none ofthe residual monomers or reac-tion by-products which are ableto influence the odour or taste ofthe packaging contents in thecase of coatings which dry byoxidation. For this reason, dis-persion varnishes are especiallysuitable for use with low-odourinks, whose binders require thatthe surface be varnished toachieve acceptable rub resist-ance.

With this combination, it isthus possible to produce pack-aging for sensitive goods sus-ceptible to odour or taste trans-fer without needing to compro-mise on gloss or rub resistance.

36

Packaging refinement

Packaging is nowadays expected to fulfil numerous tasks alongsideits original purpose of product protection. These tasks can varyenormously depending on the type of packaging. Some packagingalready provides information on the product it contains. This infor-mation helps the consumer to select the most suitable product, and

What counts with varnish

Properties of dispersionvarnishes

Alongside the universally ap-plicable advantages for dis-persion varnishes gained fromthe drying mechanism, it is alsopossible to set further proper-ties for specific applications.

Gloss

Dispersion varnishes are ableto achieve a very high level ofgloss. It must be said, however,that high-gloss types do drymore slowly than standard var-nishes. Another influential fac-tor is the amount of varnish ap-plied, which is in turn dependenton the coating equipment used.A high and at the same timesmooth and even varnish appli-cation displays the best glossresults. The substrate, too, is animportant consideration whenseeking to maximise gloss.Only unstructured surfaces per-mit a truly smooth varnish filmwith a correspondingly highreflection (= gloss).

Matt effects

The surface acquires a mattappearance through a micro-structured surface which re-flects the light diffusely ratherthan directly. Dispersion var-nishes are able to achieve verygood matt effects, though withthe reservation of possibleglossy spots arising where thesurface is subjected to exces-sive mechanical "polishing".

may even be required by law, as in the case of warning notes orinstructions for use. Besides offering information, the packaging isfrequently also intended to stimulate an actual purchasing decisionin favour of the product. Packaging has thus become a decisiveselling factor.

Film formation (schematic)Gloss values up to 85% are possible


37

Packaging refinement

Pearl gloss

Dispersion varnishes permit theprocessing of pearlescent pig-ments with a greater particlesize than is the case with offsetinks. This has the advantagethat a wider range of effectscan be achieved. Alongside thetypical pearl finishes, it is alsopossible to produce silk-gloss orglitter effects. The processing ofpearl gloss varnishes requiresthe use of a coating unit withan anilox system.

Metallic varnish

Metallic varnishes are alsodependent on an anilox coatingunit. Fine and negative types,in particular, are otherwise dif-ficult to produce in acceptablequality. The advantage of thesesystems over metallic offset inkis again the greater particlesize, which achieves a morebrilliant metallic effect. Where-as pearlescent pigments are ableto use conventional dispersionvarnishes as a binder, thebinders for metallic pigmentsare formulated specifically forthis application.

Visual effects

Gloss and matt varnishes, aswell as pearlescent and metallicfinishes, provide packaging de-signers with a sheer boundlessrange of options. Combinationsof several effects, in particular,may enable a product to standout clearly from its competitors.

Slip and friction effects

When working with dispersionvarnishes, it is possible to in-fluence not only the visual ap-pearance, but also the handlingproperties of the packaging.Anti-slip varnishes are used toensure reliable product trans-port over conveyor belts, whereaslow-friction settings are impor-tant for further processing onhigh-speed packaging lines.

Heat-sealing resistance

Many food products, etc. arewrapped in airtight films tomaintain their aroma. In suchcases, the film forms a seal withitself, but must not be allowedto adhere to the packaging. Thevarnish, therefore, serves as aprotective or separating layerbetween the film and the pack-aging. Although the heat-sealingresistance of dispersion var-nishes is generally good, it isstill imperative to perform teststo check each individual appli-cation. Variation of the sealingparameters pressure, tempera-ture and time, and above all theexact type of film used, canlead to very different results.

Hot foil embossing

With only a few special excep-tions, dispersion varnishes arewell suited for hot foil emboss-ing. In this process, a foil withhotmelt adhesive on the reverseis applied to the packagingunder the influence of pressureand temperature. Possible dis-turbing factors to be taken intoaccount here are the siliconecompounds used in some spe-cially formulated varnish sys-tems, e.g. to enhance the re-lease properties (for the re-moval of adhesive labels andthe like without destroying theprinted image).

Heat-sealing capability

Special raw materials also per-mit the formulation of blistervarnishes. These varnish systemsare generally able to replacehotmelt adhesives. Nevertheless,practical testing is indispensa-ble to verify the suitability of aparticular blister varnish foruse in conjunction with thechosen substrates and blistermaterials.

Barrier varnishes

Barrier varnishes are able totake the place of plastic coatings.Barriers against grease, airhumidity or direct moisture areavailable. High-volume varnishapplication and a suitable sub-strate are here essential pre-requisites. Application-specif-ic testing is thus imperative.

Primers

Dispersion varnishes can beused as intermediate layers toimprove adhesion and wettingbetween conventional offsetinks and UV varnishes. Furtheradvantages are reduced powderconsumption and less significantdifferences in gloss betweenthe printed and unprinted areas.

Friction tester

Further information can be requestedfrom Sun Aqua Systems EuropeHARTMANN Druckfarben GmbH by phone on +49-(0)6109/605077 or by e-mail from [email protected]


Conclusion

Dispersion varnishes are able toexert a decisive influence on thevisual appearance of a packag-ing product. However, it is moreimportantly the access to the nu-merous technical advantages andthe extensive variability whichmake this varnish system so in-teresting for packaging printers.Dispersion varnishes are nolonger merely rub protection topermit fast further processing,but have become independentmeans to enhance the design andfunction of modern packaging.

Even UV varnish is only able to achieve this high level of gloss ifvarious parameters are observed. To prevent the varnish penetratinginto the ink film, it is important that the print to be varnished isproperly dry. A certain distance of travel between application andthe final UV drying also assists the spreading of the UV varnish. Ifthe varnish is able to spread, this produces a smoother coating sur-face, and the consequently superior reflection enables gloss valuesin excess of 85 points to be achieved. Quality demands of this orderhave to date been a domain of dedicated coating presses.

Offline UV coating, requiring as it does a second press pass, is atime-consuming process and also restricts the user's flexibility.

One alternative to offline UV varnishing is double inline coating.After the inks have been printed wet-in-wet, a water-based primeris applied inline through a first coating unit. The primer serves toform a dry layer between the wet inks and the subsequent UV var-nish. This is achieved by installing two intermediate towers withIR/hot-air drying systems. This configuration initially produces arelatively high-gloss finish, though gloss values do often drop dra-matically after a certain period of time (draw-back effect). Thecause is to be seen in the fact that the conventional ink film, whichis not yet fully dry, permits penetration of the primer and the UVvarnish into the ink layers and into the paper.

Tests have shown that high-quality dispersion varnishes are oftenable to achieve gloss results as good as those obtained with thedouble coating technology.

The third and newest method for inline refinement is the hybridtechnology. In the hybrid ink system the properties of mineral-oil-based and UV-reactive inks are combined in a single product.

The primary advantages of the hybrid inks are the fast drying andthe reliable compatibility of the binder systems with the UV var-nish, features similar to pure UV ink systems. The hybrid inks per-mit only minimal penetration of the UV varnish into the ink film.This results in very high and reproducible gloss values.

The success of the hybrid technology demands that users observecertain important parameters. The following sections of this articlesummarise the essential information for a technical understandingof this ink system.

Stability in storageThe stability of the ink in storage is influenced by the storagetemperature. Higher storage temperatures generally reduce thestability, though other factors such as the chemical constitutionof the pigments also play an important role. Through a broad se-ries of tests, it has been possible to identify pigments, also forspecial colours, with a shelf life of at least six months at 25°C.

PrintabilityInk-water balanceThe classification of hybrid inks with regard to ink-water balancecan be equated to conventional inks rather than to pure UV inks.This is reflected in a stable emulsion and significantly reducedrisks of scumming.

Any standard commercial additive can be used for the dampeningsolution. Dampening additives with active drying properties maylead to disturbances and are thus not to be recommended. Printtests have shown that active-drying dampening additives cantrigger drying of the hybrid inks on the rollers.

It is furthermore recommended to perform a water analysis, asthe quality of the process water also influences the printability ofthe hybrid inks. The suppliers will normally test the quality ofthe water free of charge and will then recommend the necessarymeasures.

RheologyThe rheology of the printing ink covers properties such as viscosity,tack and flow characteristics. These three parameters are veryclosely interrelated. It is extremely difficult to modify one of theseparameters without also influencing the other two.

The most important property of the ink in respect of ink transportis the tack. The tack is a measure for the forces required to splitthe ink as it is passed through the inking unit to the blanket andfinally to the substrate. The dry tack (ink without water) is a littlehigher in hybrid systems than with conventional inks, the wet tackon the other hand a little lower. It is thus important to adjust andmatch the dry and wet tacks carefully to obtain results of thedesired quality.

38

Hybrid inks

Today's market is constantly raising the yardstick for the high-glossrefinement of printed products. 85 gloss points or more havebecome a standard demand. Such values are only attained bycellophaning or with UV varnishing.

Starbrite

Flow curve1.200

Pa

1.000

900

800

700

600

500

400

300

200

100

0

1.000Pa·s900

800

700

600

500

400

300

200

100

00 1 2 3 4 5 6 7 8 9 1/s 10

Shearing rate γ

ητ

The viscosity of a system is derived from the internal frictionwhich opposes a compressive or thrust force therein. Under theinfluence of such a thrust force (n), a material is subjected to ashearing effect with a constant shearing rate.

The quotients from thrust force and shearing rate describe thedynamic viscosity with the unit Pa·s. Viscosity measurementsare immensely important in ink development in order to beable to elaborate and specifically optimise ink properties suchas flow behaviour, flow point, relaxation time, etc.



39

Hybrid inks

Print qualityThe print quality achieved by hybrid systems is by all meanscomparable to that of conventional inks. The graphs below placethe individual characteristics alongside those of a standard con-ventional ink series.

100

90

80

70

60

50

40

30

20

10

0

Characteristic (magenta)

100

90

80

70

60

50

40

30

20

10

0

100

90

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0

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0

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100

Characteristic (cyan)

Characteristic (black)

Characteristic (yellow)

StarbriteConvent.

StarbriteConvent.

StarbriteConvent.

StarbriteConvent.

Gas chromatographic analysisHigh-volatile aldehydes are responsible for unpleasant odours andaromas. Gas chromatographic analyses were carried out to deter-mine the relevant aldehydes in the Starbrite inks.

The Starbrite ink system was evaluated in two separate tests. In the first test, the hybrid ink wasplaced against a conventional, oxidatively drying ink. In the second test, the hybrid ink was placedagainst a low-odour conventional offset ink.

The concentrations of the following high-volatile aldehydes were determined: 1. Butanal C-4 aldehyde 2. Pentanal C-5 aldehyde3. Hexanal C-6 aldehyde 4. Heptanal C-7 aldehyde

The aldehyde hexanal is primarily responsible for the development of odours. The hexanalpeak for the conventional ink is clearly visible (green line), whereas the peak for the Starbriteink is significantly smaller.

In the comparison between the Starbrite and low-odour inks, the emission curves practicallycoincide.

In conclusion, it can be said that the Starbrite inks bring aldehyde reductions comparable tothose achieved with low-odour inks. As with food packaging printed using conventionalinks, however, it remains important to ensure that the packaged product cannot come intocontact with the ink.

The final packaging product can be assessed by way of a Robinson test. The paper, varnish,dampening solution and even the storage conditions all play an important role for this sensi-tive test method. It is thus recommended to make arrangements for an individual Robinsontest to be performed at a competent institute for packaging printed with hybrid inks.

1. MEK testApplicationsThis test serves to evaluate the full curing of all UV varnishes. Varying degrees ofcuring of the UV-varnished surfaces are expressed in varying resistance to methylethyl ketone (MEK).

Test principlesThe test must always be performed on the original substrate. Part of the UV-varnishedsubstrate is covered with paper or aluminium foil and passed through the UV dryingsystem a second time, whereby it can be guaranteed that the uncovered part is ab-solutely fully cured. This double-cured part of the substrate serves as a reference forthe MEK test.

Testing agentsMethyl ethyl ketone or acetone and cotton wadding.

MethodA wad of cotton soaked in MEK is rubbed back and forth with gentle pressure overthe whole substrate to be tested, i.e. over both the originally cured and the double-cured sections. This is done until the UV varnish and the ink begin to soften. The var-nish is not properly cured if the UV varnish and ink on the originally cured sectionare softened quicker than on the double-cured section.

Test methodsTwo methods can be used to test the full curing of UV varnishes.

2. Talcum testApplicationsThis test serves to evaluate the surface curing of all UV varnishes. The measure to assessthe surface curing is the adhesion of talcum powder on the varnish surface.

Test principlesThe test must always be performed on the original substrate. Part of the UV-varnishedsubstrate is covered with paper or aluminium foil and passed through the UV dryingsystem a second time, whereby it can be guaranteed that the uncovered part is ab-solutely fully cured. This double-cured part of the substrate serves as a reference forthe talcum test.

Testing agentsTalcum powder and cotton wadding

MethodA wad of cotton with talcum power is rubbed with gentle pressure over the wholesubstrate to be tested, i.e. over both the originally cured and the double-cured sec-tions. If the varnish is not properly cured, talcum powder will adhere to the varnishsurface after wiping with the wadding. The amount of talcum powder left behind isthe indicator for the degree of surface curing.

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wider. If the press operator failsto compensate this change, thiscan lead to problems such asscumming. The higher dynamicstressing of the roller coating,furthermore, may also subse-quently result in damaging ofthe roller surface. The changein diameter is normally greaterin the centre than at the edgesof the roller, i.e. the roller be-comes "cigar-shaped". In the datacharts, swelling is indicated asa positive volume change.

Roller shrinkage brings otherconsequences. The roller diam-eter decreases and roller con-tact can be lost if no adjust-ments are made to compensate.The decrease in diameter isoften less at the edge than inthe centre of the roller. This"bugle" effect normally has nodetrimental influence on printresults, as the flared ends areoutside the image area. In thedata charts, shrinkage is indicat-ed as a negative volume change.

Since the introduction of hybridinks on the European market,Böttcher has tested ink seriesfrom various manufacturers todetermine their compatibility

with Böttcher materials. Hybridinks are basically mixtures ofconventional and UV inks. Itwould thus be reasonable toexpect the "dual-purpose" rub-bers which are suitable for al-ternating UV and conventionalproduction to be similarly com-patible with the hybrid inks.For many users, it would alsobe interesting to ascertainwhether or not the materialsalready present in inking anddampening units for conven-tional inks, e.g. the Böttchermaterials 179 25 and 220 22,are equally suitable for hybridapplications.

The charts are examples of theresults for various hybrid inkseries which, on the basis ofexperience to date, are suitablefor use with all the specifiedroller coating materials.

40

Hybrid resistance tests

Hybrid inks are interesting additions to the range of available printing inks. One important question which many users are asking is:Do I need special rubber coatings on the rollers to print with hybrid inks?

Hybrid inks and their effects on roller materials

53521, though with the deviationthat the test discs used possessa thickness of 6 mm.

The swell data obtained fromthese static tests cannot be ap-plied unconditionally to practicaluse. This is above all because therollers are subject to dynamic,constantly changing influencesand because contact with theinks is only possible on thecoating surface, whereas thetest discs in the laboratorytests are exposed to the inkfrom all sides. It requires long-standing experience on the partof the roller manufacturer todraw conclusions as to the sig-nificance of certain measure-ments and to determine whichmaterials can thus be usedwithout problems under nor-mal practical circumstances.

If swelling occurs, the contactstripes on the rollers become

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Volume change after 7 days in the medium

31035 37435 31035 37435Ink A Ink B

Influence of temperature on swelling test results

Testing of chemical resistance

Typical contact stripe after swelling

Contact after roller shrinkage

There are basically two process-es which can be observed whenthe rubber matrix comes intocontact with printing inks. Firstly,substances can penetrate intothe rubber matrix, a situationwhich is generally described asswelling. The roller diameterincreases. At the same time,other substances, in particularsofteners, can be dissolved outof the rubber. This shrinkageleads to a decrease in the rollerdiameter. Both processes aredependent on the temperature,the exposure time, the contactmedia and the roller coatingmaterials used. The influenceof temperature is illustrated inthe chart below. The higher thetemperature, the greater thechanges in the tested rollerunder otherwise identical con-ditions.

The roller manufacturer simu-lates these processes in the lab-oratory. The material samples,round discs with a diameter of36 mm, are placed in the printingink to be tested and kept therefor seven days at 50°C. The vol-ume change is then calculatedby determining the mass of thetest disc in air and in water.

Swelling tests at Böttcher arebased on the standard DIN

20° C

50° C

80° C Further information can be requested by phone on +49-(0)221/4907-467or by e-mail [email protected]

Inking roller

Dampening roller

Inking roller


41

Hybrid resistance tests

The tested roller coating materials:179 25 Standard material for conventional inks and

individual hybrid series375 38 Standard material for alternating UV/conv. production171 25 Standard material for alternating UV/conv. production471 38 Standard material for alternating UV/conv. production220 25 Standard material for dampening rollers2840 25 Special material for dampening rollers

for low-alcohol printing

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Chemical resistance testing of Böttcher materials with hybrid inks, version A

SummaryTest results to date indicate that the materials for alternatingUV/conventional production can be used together with the hybridinks available on the market. The hybrid inks recommended byKBA Radebeul, furthermore, are also compatible with the standardmaterials for conventional printing inks.

Chemical resistance testing of Böttcher materials with hybrid inks, version B

Chemical resistance testing of Böttcher materials with hybrid inks, version D

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Chemical resistance testing of Böttcher materials with a hybrid washing solvent, version A

Chemical resistance testing of Böttcher materials with hybrid inks, version C

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Chemical resistance testing of Böttcher materials with a hybrid washing solvent, version B

Test conditions: 1 day at 23°C






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42

Hybrid versus double coating

Despite the relative simplicity of the hybrid technology and thefavourable costs, many users remain sceptical. The interest shownby the packaging industry, however, is very extensive. The ink andvarnish manufacturers have thus taken up the challenge of devel-oping low-odour and odourless products. There are numerous reasons for the great commitment shown byKBA to this new technology. The pressures of time and costs areincreasing constantly in daily printing practice, parallel to a trendtowards ever shorter runs. Against this background, the hybridtechnology opens up new possibilities for cost-efficient refinement.

Hybrid technology versus double-coatinfrom the viewpoint of the experienced u

The philosophy of a hybrid press is clearly defined:

1 Inking units for conventional and hybrid inks with standard roller coatings 2 UV interdeck dryer; 1 lamp, 160 W/cm3 Coating tower with two separate varnish circuits (dispersion and UV)

Alternatively: Lithocoat Circulator™ (see pages 10–12)4 Extended delivery; IR lamps and hot air 5 UV final drying; 3 lamps, 160 W/cm each6 ACS extraction (recommended, see page 13)

This press configuration, however, is only possible in connection with the recommended and approved hybrid inks and washing solvents.

Standard equipment of a hybrid press configuration

An optimisation of the process still holds considerable potential forfurther enhancements in quality, economy and environmentalawareness. Technical progress should here be understood as achance and not as a threat to established market positions.Recent opinion in the branch has often been characterised by hesi-tation and uncertainty. Reservations concerning press configura-tions and the corresponding attainable qualities in inline UV var-nishing have been the subject of stormy debates. This article is in-tended to offer users an objective appraisal of the current "status"of the hybrid technology.

Washing systems andwashing solvents

The principal objective was todevelop a hybrid washing sol-vent on a high-boiling basis foruse in the washing systems. Thesupplier industry has fulfilledthis task. Washing solvents onthe basis of high boilers areoilier than products with lowerflash points and call for metic-ulous adjustment of the wash-ing programs. Test series have

shown that the amounts of sol-vent used can be reduced in thiscase. The water metering on theother hand must be increasedon account of the vegetable oilscontained in the washing solventfilm. The metering for rollerwashing is basically identical.Nevertheless, it is recommendedto follow automatic roller wash-ing with an acidic roller sham-poo in the case of hybrid inks.In this way, greasy residues andinvisible contamination can be

loosened and removed from thecapillaries of the roller coatings.

Optional equipment for hybrid press configurations

The configuration of the print-ing press is always governedby individual applications. Inthis connection, as describedbelow, the standard press equip-ment can be expanded with avariety of additional options.

For the packaging printer, theprocessing of aluminium-coat-ed materials is nothing out ofthe ordinary. Even so, theseproducts bring numerous diffi-culties for a conventional pro-duction setup.

A first press pass is usuallytaken to print an opaque whitesolid as a background primer.The subsequent intermediatedrying time for these sheets isfar from insignificant. The ac-

15 4 3 26


43


g alternatives for inline UV varnishingser

tual image is then printed in asecond press pass, whereby thepowder used during the firstproduction pass leads to shorterintervals between the interrup-tions for washing.

Using the hybrid technology,on the other hand, the opaquewhite can be printed in thesame pass as the image itself.The condition, however, is thatan optional interdeck dryer hasbeen added in the first printingunit.

This additional interdeck dryermay also become necessary for

• presses with more than fiveprinting units

• images with a high ink coverage

• the use of certain specialcolours

• high production speeds.

In view of the diversity inpotential product ranges, it isrecommended to seek indi-vidual specialist advice fromour process engineers whenconfiguring your press.

The drying process

The hybrid technology demandsthat the operator sets the dryingsystems on the press with par-ticular care. An approach basedon the motto "The more, thebetter" will not bring processreliability. If dryer tempera-tures are set too high, this maylead to demission changes inthe substrate. In extreme cases,the user must even reckon withpile blocking, especially ifhybrid and mineral-oil-basedinks are used in refinement.Excessive pile temperature canalso cause yellowing of a min-eral-oil-based varnish.

Pile temperatures around 50°Care not unusual and do notnecessarily lead to blocking. It

is recommended here to providea certain spacing in the form ofpowder.

Gloss determination

Basically, no standardised testforme existed in the past todetermine exact gloss valuesin accordance with the aboveparameters. For this reason,process engineers at KBA havedeveloped a test forme them-selves.

Each individual field representsa different tone value combina-tion, graded right up to 4 x100% area coverage. This testforme can now be used tomeasure the gloss values forany chosen substrate, at anyproduction speed, for any areacoverage and also with anychosen varnish type. The useris thus able to determine notonly the gloss points, but alsothe reproducibility of the mostvaried print jobs without com-plications.

Refinement possibilities

Alongside simple high-glossvarnishing, there are a numberof other refinement possibilitieswhich can be achieved withoutparticular technological diffi-culties using the hybrid method.If, for example, a printedproduct requires both matt satinand gloss-varnished elements,then there are generally threeproduction options:

1. Inline double coating2. Production in two press

passes, or3. Offline varnishing.

In all three cases, it is neces-sary, assuming the elementsare not simple geometricalshapes, to plot or manuallystrip separate varnish formesfor each varnish application.The only feasible alternativewould be to use special spotvarnishing formes exposed ona circular setter. This, however,is complex, expensive and must

Gloss measurements are natu-rally an important basis forevaluation. Nevertheless, thegeneral visual impression shouldnot be disregarded.

The two photo images in theforme are especially suited inthis connection as they con-tain both light tones and areaswith a very high coverage. Thehard transition to the higharea coverages will be reflect-ed in "draw-back effects" (cf.pages 38/39).

Last but not least, patches arealso provided to measure thedot gain.

The following results were ob-tained repeatedly in the courseof intensive test series, where-by proof of the reproducibilityhas been furnished.


The general process parametersfor this test series were identical to those for the double-coating configuration.The results show a significantlyhigher degree of gloss. Even themeasurements after 72 hours

revealed only a minimal "draw-back effect". On the basis of thesemeasurements it can be deducedthat the hybrid technology permitsvery high and reproducible qualityfor UV coatings.

44


generally be entrusted to anexternal supplier.

Varnish registration and thesubsequently inevitable make-ready at the coating towersvery quickly dispel any hopesof economically viable pro-duction.

With the hybrid technology, onthe other hand, such demandscan be met with a five-colourpress with a single coatingtower and extended delivery.The procedure is as follows:Printing units 1 to 4 are as-signed the hybrid Euroscalecolours. All matt satin ele-ments are produced in the fifthunit with a mineral-oil-basedsystem in a normal offsetprocess. The high-gloss ele-ments must be left blank onthis unit.

The subsequent all-over UVcoating triggers a defined inter-action. The UV varnish pene-trates the mineral-oil-based inksystem and produces the desiredmatt/gloss effects. Since thevarnish registration is achievedin a normal offset unit, thereare practically no limitationsto be observed with regard todesign complexity and applica-tion. This is backed up, fur-thermore, by an excellent eco-nomic efficiency.

Further developments

It would be presumptuous toclaim that the hybrid technol-ogy has already attained thezenith of its development. Thesuppliers are looking into thefuture objectively and want touse the close cooperation withKoenig & Bauer AG to imple-ment further demands andwishes from the users.

Central topics to be addressedare currently odour reduction,hybrid inks for plastic sub-strates and improved suitabilityfor folding and embossing.The influence of the chemicalcomposition of the dampeningsolution is another subject forinvestigation. Positive resultsare expected in the mediumterm.

Hybrid press: Rapida 105-5+L ALV2

Settings and materials

Double coating press: Rapida 105-5+T+T+L ALV2

Plates: Positive-working and bakedInk rollers: Conventional rollers (see pages 40+41)Blankets: Standard product, not UV blanketsDampening additive: Standard product, no active drying (see pages 38+39) Dampening solution temperature: 10°CVarnish formes: Relief varnish platesSubstrate: Double-coated art paper, glossy, 150 g/m2

The vertical axis of the graph repre-sents the measured gloss values from55 to 95 gloss points. The pointsacross the horizontal axis representdifferent combinations of area cover-age for the individual colours, togetherwith the unprinted, but varnishedpaper white as a reference value.

The sheets measured immediatelyafter printing display very good glossresults.

The sheets were measured a secondtime after 72 hours. The results illustrate clearly the ensuing "draw-back effect".

Further information can berequested by phone on +49-(0)351/833-2674 or by e-mailfrom [email protected]

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55MK 70% CM 70% CMY 70% MK 100% CM 100% CMYK 70% CMY 100% CMYK 100% unprinted

140% 140% 210% 200% 200% 280% 300% 400%

Mineral-oil-based inks + primer and UV final coatingGloss measured immediately and after 72 hours

Measured immediately, 10,000 sphMeasured immediately, 12,000 sph

Measured after 72 h, 10,000 sphMeasured after 72 h, 12,000 sph

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Measured immediately, 10,000 sphMeasured immediately, 12,000 sph

Measured after 72 h, 10,000 sphMeasured after 72 h, 12,000 sph

Test results for the hybrid technologyGloss measured immediately and after 72 hours


Important information

Hybrid inks and their applica-tions must be considered a sep-arate dedicated system. Noneof the printing aids for miner-al-oil-based and pure UV inkscan be used.

The products are not chemicallycompatible. Even hybrid inksand hybrid printing aids fromdifferent manufacturers are notcompatible with each other.

45

Profitability of the hybrid technology

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This study is the result of wide-ranging computations and arith-metical models. The press typewe used for the study was a B1Rapida 105, configured as threedifferent versions: a pure UVpress, a conventional two-coaterpress and a hybrid press.

In this context the term “hybridpress” indicates a sheetfed offsetpress capable of applying hybridinks plus a UV end-of-presscoating as well as normal inksplus a water-based coating.

The press configuration on whichwe based our cost calculationsfeatured five printing unitsplus coater, a double deliveryextension and automatic washingsystems for the blankets androllers.

This basic version (designated (0)in figures 1 to 3) was fitted withadditional equipment dependingon the processes involved, whichincreased the capital outlay to agreater or lesser extent.

The interplay between printing presses and new consumables still offers enormous potential forenhancing plant profitability and production flexibility to support non-standard products. A currentexample is the use of hybrid inks in conjunction with inline coating. The comparative economics ofconventional and hybrid processes are detailed in the following feasibility study.

Reduced costs, enhanced flexibility = greater impact

Version 1: Pure UV press

At one time UV processes werethe only alternative to pure-playcoating presses for producing ahigh-grade inline coating, wet-on-wet. The equipment neededfor UV production comprises:

1 UV options for printingunits and coater,

2 UV rollers and ink agitators,

3 a UV coating circulator(with heating/flushing functions),

4 two interdeck UV dryers (one possible positionshown here),

5 three more positions forinterdeck dryers betweenthe printing units,

6 a final dryer for UVinks and coatings.

Version 2: Two-coater press

The basic two-coater press (0) infigure 2 requires the followingfeatures:

7 two interdeck dryers withIR and hot-air systems,

8 a second coater withchamber blade and UV options,

9 a coating circulator forwater-based and UV coatings, with heating/agitating/flushing functions(two circuits)

10 a number of final dryersthat can be used for conventional inks plus protective coatings, conventional inks plusgloss coatings, or UV inks plus UV coatings.

Figure 1: 5-colour Rapida 105UV press (0) with coater, doubledelivery extension, blanket/rollerwashing

Figure 3: 5-colour Rapida 105hybrid press (0) with coater,double delivery extension, blanket/roller washing

Figure 2: 5-colour Rapida 105two-coater press (0) with coater,two dryers, coater, double deliveryextension, blanket/roller washing

Even though this configurationis much more complex – andtherefore also much more ex-pensive – than that of a pureUV press, it does enable thepress to be run, for example,with standard offset inks fol-lowed by a primer, interdeckdrying and UV coating, as wellas with standard offset inks plusa double application of a water-based coating. For the latterprocess, however, it may be nec-essary to install an additionalIR dryer before the first coater.

Version 3: Hybrid press

The hybrid press, like the UVpress, only needs one coater,but is very much more flexiblein the use of inks and coatings.In addition to the basic features(0) the hybrid press requires:

1 UV options for printingunits and coater,4 two interdeck UV dryers, 9 a coating circulator for

water-based and UV coatings,

10 a final dryer for conventional inks and protective coatings, conventional inks andgloss coatings in the delivery extension, UVinks and UV coatings in the swan neck,

11 dual-purpose rollers for alternate hybrid andstandard inks.

With the new-generation hybridinks we can now combine thebenefits offered by the UVprocess, namely

• a less complex and thereforeless expensive press configu-ration and

• a higher gloss level forcoatings, with the benefits

offered by conventional inksand coatings (for specific applications) to enhance versatility while nailing downcosts.

For example, depending on thejob to be printed the use ofhybrid inks with UV coatingsor the use of conventional offsetinks with water-based coatingsis possible without changing thepress configuration and withouttime-consuming makeready tasks.A number of KBA customers

are already taking advantage ofthis option. The hybrid press isthus capable of far more than theUV press, without driving upinitial investment costs.

The feasibility study for the threedifferent versions encompassedspace requirements, the initialinvestment cost, energy con-sumption and the cost of con-

sumables such as inks, coatings,coating formes, and profitabilitybased on annual output and runcosts.

Hybrid footprint 20% smaller than two-coater footprint

A Rapida 105 press with twocoaters is around 3.2m (10' 6")longer than a five-colour UV orhybrid press. Whereas a two-coater press takes up roughly160m2 (1,722ft2), a hybrid pressrequires just 135m2 (1,453ft2).So a hybrid press has a 20 percent smaller footprint than atwo-coater press.

Key data for feasibility study

As a platform for comparisonwe took two-shift operation,3,000 production hours peryear and a plant utilisationlevel of 85 per cent. This isslightly lower than the techni-cally possible utilisation levelof 92 to 95 per cent becauseplant- and production-specificfactors also had to be takeninto account.

Material costs were calculatedfor a 700 x 1,000mm (27.5" x39.5") image, an ink thicknessof 1µm (0.04 mils), a 30% me-dian tonal value, five printingunits and a coating applicationof 4gsm (0.8lbs/1,000ft2, wet)at 80% ink coverage. For sim-plicity’s sake we assumed thesame volumes for primer, aque-ous coatings and UV coatings.

Production output was basedon an average job length of10,000 sheets which, within theavailable 3,000 hours of pro-duction time, would give a totalof 1,600 jobs per year, allowingan average of 45 to 55 minutesfor makeready.

Makeready times on hybrid orUV presses can, in fact, bemuch shorter – around 25 min-utes or so. But for maximumaccuracy we also included inkchanges, cylinder changes andother tasks in the makereadytimes.

On average we can say that,with the same number of oper-ators, makeready tasks on atwo-coater press take around

10 to 20 minutes longer thanon a hybrid or UV press. Thisis largely because positioningthe two coating formes in pre-cise registration takes up a lotof time, especially if spot coat-ing is specified.

Two-coater press 20% dearer than hybrid press

Taking the initial outlay for ahybrid press as a value of 100,then a UV press works out ataround 3 per cent cheaper. Thedifference in price is mainlydue to the additional dryers andmore complex coating circuiton the hybrid press, whichenable it to handle water-basedcoatings in conjunction withstandard inks, as well as UVcoatings.

The two-coater press works outeven more expensive – around20 per cent or €300,000($295,000) dearer than a hybridpress. This is because a secondcoater and two interdeck dryersare required.

Energy costs much higher with two-coater press

Energy consumption, repre-senting a sizeable percentageof annual production costs, isup to 80 per cent higher withthe two-coater press than withthe hybrid or UV press. This isprimarily caused by the rela-tively high energy consumptionof the two IR/hot-air dryers andthe end-of-press IR dryer, notto mention the additional powerneeded to drive the much longerpress line.

At an assumed price of €0.11per kWh we calculated that theannual energy consumption ofthe two-coater press would cost€39,000. This is a big expensewhich must be passed on to thecustomer or assimilated in theform of reduced profits.

46



Figure 4:Initial outlay

Ink agitators, UV rollers, UV coating circulation, final UV dryer

Two interdeck UV dryers, UV option in printing unit

Coating circulation and final dryer for UV and water-based coatings

Two interdeck dryers and second coater

Basic 5-colour Rapida 105 withcoater, double delivery extension and washingUV ink,

UV coatingHybridink, UVcoating

Conv. ink,primer, UVcoating

Figure 5:Energy consumption

Final UV dryer

Final IR dryer

Interdeck IR/hot-air dryer

Interdeck IR dryer

Interdeck UV dryer

Motor, actuators, dampening preparation

Two-coater Hybrid UVpress press press

> € 39,000 p.a.(€ 0.11/kWh)

> €300,000

Material costs also favour hybrid press

Turning to the cost of consum-ables for the three versions(fig. 6), we found that those forthe two-coater press are around58 per cent higher than for thehybrid press and some 60 percent higher than for the UVpress. Here much of the blamelies with the high price of coat-ing formes. In extreme casesthe price difference for con-sumables alone can approachhalf a million euros a year, afigure not to be taken lightly.

This is assuming that the two-coater press requires two platesper coater. If, however, primerfor full-solids coating, say, canbe applied via a blanket, thenthe cost of coating plates willbe much lower.

In fact, if we ignored the costof coating plates then the two-coater press would have thelowest material consumption.This is because, at present, off-set inks are very much cheaperthan either hybrid or UV inks –around half the price. Here it isup to the manufacturers of hy-brid inks to promote their useby bringing down the price,which in turn would increasesales. There are already movesin this direction.

If the job so specifies, hybridpresses can, of course, also berun with standard offset inksand water-based coatings, sothe cost advantage of two-coater presses only exists if oneis comparing apples with pears,as it were. Moreover, a hybridpress is very much more cost-effective for occasional, ink-only jobs than a two-coaterpress, whose coating assem-blies are then superfluous forthis type of job but have to runnonetheless.

Hybrid process more profitable

Lastly, we compared theprofitability of the two-coater,hybrid and UV processes.

• The columns indicating initialcost in figure 7 are to thesame scale as the columns infigure 4.

• Absolute output is a fictitiousmean output embracing allprinting times, makereadyand assumed down times.

• The makeready columns onlyinclude average make-readytimes. Work sequences not required for every job changeare therefore averaged outacross several jobs.

In fig. 7 we assumed an averagemakeready time of just tenminutes for the two-coaterpress, compared to the hybridor UV press. However, thisassumes that both coaters aremade ready simultaneously,which requires additional per-sonnel.

• The possible annual outputhas been based on joblength, makeready time,press speed (which has beentaken as 11,500s/h for allthree presses) and the avail-able production capacity of3,000 hours per year.

The columns on the right of thechart indicate production costsper 1,000 sheets as a percentage,including makeready, with val-ues for the hybrid press takenas 100. From figure 7 it can beseen that the production costsfor 1,000 sheets with the UVpress are even lower than withthe hybrid press because of thelimited coating options it offers.The cost per 1,000 sheets withthe two-coater press is between38 and 20 per cent higher,depending on run length.

The hybrid press’s clear advan-tage with regard to productioncosts diminishes as run lengthsincrease, since both the longermakeready time and the highcost of coating formes for thetwo-coater press then decreaserelative to total costs.

On the whole, however, for therun lengths most widely usedin sheetfed offset, productioncosts with hybrid inks and anend-of-press UV coating arevery much lower than with atwo-coater press, and comparefavourably to those with a UVpress because of the increasedoptions possible.

The curve at top right in figure7 shows that the actual produc-tion costs (excluding paper)for 1,000 sheets printed on thehybrid press depend on runlength, and drop sharply beforelevelling out at around €50 for20,000 sheets or more.

Prior to investing in a newpress it is always wise todefine the types of productthat it will print, and not justlook at individual cost factorssuch as inks.

Further information can be requested by phone on +49-(0)931/909-4336 or by e-mailfrom [email protected]

47


174

92,5

66 57 52 47,5

2 5 10 15 20 30


Figure 6:Cost of consumables (ink, coatings, coating plates) and additional waste

Coating formes [130% 65% 65%]

Add. makeready waste [2,9% 0% 0%]

UV coating[6,5% 6,5% 6,5%]

Water-based coating[3,2% 0% 0%]

Ink[13% 28% 25%]

Conv. ink, primer,UV coating

> € 480,000 p.a.

Figure 7:ProfitabilityDouble coating (CDDC) /Hybrid / UV

Initialcost

Abs.outp.

Make-ready

Outputp.a. Run length (1,000 sheets)

Two-coater

Hybrid

UV

–– Hybrid(€ )

Production costs for 1,000 sheets Hybrid press

Hybrid ink, UV coating

UV ink, UV coating

We would like to thank all those who have contributed in the form of articles or otherwise to the success of this first issue of "KBA Process". Further information on the individual topics can be obtained from the following contact partners at the companies concerned.

If you are not already a subscriber to our customer magazine "KBA Report" andwould like to receive copies in the future, simply get in touch. Anja Enders would be pleased to receive your call: E-mail: [email protected],Tel.: +49-(0)931/909-4518, Fax: +49-(0)931/909-6015

Company Contact partner

Baldwin Alexander FischerTel. +49-(0)821/7942360

Böttcher Gerhard SchmiedelTel. +49-(0)221/4907-467

ContiTech Albrecht SzeitzsamTel. +49-(0)5551/702-105Mobile +49-(0)170/5763127

Eichhorn Wellpappenwerke Hellmut EichhornTel. +49-(0)2461/699200

Eltosch Jens GottschalkTel. +49-(0)40/84000756

Epple Druckfarben Norbert LenzgeigerTel. +49-(0)821/4603-224

Flint-Schmidt Dr. Hans-Peter SeyerTel +49-(0)69/7802-282

Grafix Andreas DöderleinTel. +49-(0)711/78 69-200

Harris & Bruno Gerhard PalinkasTel. +49-(0)7171/947040

Huber group Roland SchröderTel. +49-(0)89/9003-328Mobile +49-(0)170/7808241

Lithec Thomas FuchsTel. +49-(0)8025/99720

Sun Chemical Dr. Bernhard FritzTel. +49-(0)69/4000-215

Vegra Albert UhlemayrTel. +49-(0)8638/96780

Impressum

Koenig & Bauer AG, RadebeulPostfach 02 0164D-01439 D-Radebeul, GermanyTel. +49-(0)351/833-0Fax +49-(0)351/833-2550Web: www.kba-print.deE-Mail: [email protected]

Contact partner: Jürgen VeilTel.:+49-(0)351/833-2674E-mail: [email protected]

48 Issue 1/2002 KBA Process

Packaging: print serving communication

Packaging designers, suppliers, advertisers, buyers and printers

all apply our technology to create eye-catching products from

blank cardboard. We take pride in the fact that print promotes

communication and the spread of knowledge, information and

entertainment. Communication is an essential part of our daily

lives – and print plays a major role. Promoting print is our

mission. Now and in the future.

What’s Life without Print?

People & PrintKBA

.I.319 e

Koenig & Bauer AG, RadebeulPostfach 02 0164, 01439 Radebeul, Germany, Tel. +49-(0)351/833-0, Fax: +49-(0)351/833-2550Web: www.kba-print.de, E-mail: [email protected]

People & PrintPeople & Print

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