Creping. Tissue machine creping

transcript

•Introduction

•Definition of Creping

•Types of Creping

•Types of Crepe

Creping

•Hardware Geometry

•Theoretical Model

•Process Variables

•Sheet Properties

•Coatings

Yankee Dryer

Wet Press Reel Doctor Blade

Crepe Structure Formed

Creping

Yankee Dryer

UncrepedSheet

CrepedSheet

Blade Holder

Creping Changes the Sheet

Yankee Dryer

Former

Creping Blade

Typical Dry-Crepe Machine

•Introduction

•Theoretical Model - Macroscopic Model

- Microscopic Model

•Sheet Properties

•Coatings

Creping

Yankee Dryer

CoatingAdhesive Uncreped

CrepedSheet

GrindAngle

Blade Holder

BladeWearAngle

PocketAngle

BladeExtension

YANKEEDRYER

Mechanism of Creping

YANKEE DRYER

Microfold (Primary Crepe)

Macrofolds (Secondary Crepe)

Microfold (Primary Crepe)

Macrofold (Secondary Crepe)

Yankee Dryer

Doctor Blade

Creping Analogy

6 m 90 E

Pocket Angle

MG SHEET CREPING BLADE

95 km/hr

Failure Mechanisms in Compression

Shear Zone

Lateral Supports

P (a) Shear-slip-plane

mode (brittle) (b) Bending mode (c) Bulging mode

(internal rupture)

Lateral Supports

We want this kind of failure

Crepe Wavelength

Crepe Amplitude

Folding Radius

Crepe Structure Measurement

Creped Sheet

100X Actual Size

•Introduction

•Angle Definition

•Inter-Relationships

•Measuring Blade Angles

•Sheet Properties

•Coatings

Creping

Creping Geometry Yankee Tangent Line

Yankee Tangent

Creping Blade

Yankee Dryer

Creping Geometry Blade Wear Angle

Yankee Tangent

Creping Blade

Yankee Dryer

Blade Wear

Creping Geometry Blade Grind Angle

Yankee Dryer

Blade Grind Angle

Yankee Tangent

Creping Blade

Creping Geometry Creping Pocket Angle

Yankee Dryer

Creping Pocket

Yankee Tangent

Creping

POCKET = 90 - WEAR+ GRIND

Creping Geometry Creping Angle Summary

Yankee Dryer

Blade Grind Angle

Yankee Tangent

Creping Blade

Creping Geometry Sheet Take-Off Angle

Creped Sheet

Creping Blade

Yankee Dryer

Yankee Tangent

Sheet Take-Off Angle

SHEET-TO-BLADE + TAKE-OFF = POCKET

Creping Geometry Sheet to Blade Angle

Sheet-to- Blade Angle

Creping Blade

Yankee Dryer

Yankee Tangent

Creped Sheet

SHEET-TO-BLADE + TAKE-OFF = POCKET

Effect of Creping Pocket Angle Crepe Amplitude vs Creping Pocket Angle

PRIMARY

SECONDARY

Creping Pocket Angle, degrees

75 80 85 90 65

Yankee Dryer CREPING

POCKET

Yankee Tangent

Creping Blade

Reflective Wear Angle Gauge

Flashlight Angle Finder

Sighting Tube

Micarta Block

Doctor Blade

Magnet

Typical Dry Creping Geometry 12 - 24

2.6 kN/m (15 pli)

Blade Wear Angle

Loading Pressure

0 - 15

82 - 88

52 - 68

12 - 30

12 - 19 mm

0.65- 1.25 mm

Blade Grind Angle

Creping Pocket Angle

Sheet Take-Off Angle

Sheet-To-Blade Angle

Blade Extension

Blade Thickness

Creping Mechanism Effect of Pocket Angle

Pocket Angle < 80

Pocket Angle > 80

Primary Crepe Only

Primary & Secondary Crepe

Creping Mechanism TISSUE CROSS SECTIONS

Creping Pocket Angle = 65

Creping Pocket Angle = 80

•Introduction

•Process Variables •Pocket Angle

•Adhesion

•Basis Weight

•Uncreped Sheet Properties

•Sheet Properties

•Coatings

Creping

Creping Mechanism Effect of Adhesion Level

LOW ADHESION

HIGH ADHESION

Fine, Uniform Crepe

Coarse, Skippy Crepe

Creping Mechanism TISSUE CROSS SECTIONS

Dryer Adhesion = 2.3 gram per inch

Dryer Adhesion = 12.2 gram per inch

Effect of Adhesion on Crepe Amplitude

2 4 14 6 8 10 12 16

Sheet-To-Dryer Adhesion (g/in)

Creping Mechanism

UNCREPED

SECTIONS

High Adhesion, Pocket < 80

High Adhesion, Pocket > 80

PRIMARY

PRIMARY &

SECONDARY

CREPING

Low Adhesion, Pocket < 80

Effect of Basis Wt on Crepe Amplitude

8 10 20

Basis Weight (gsm)

0.03 12 14 16 18

•Introduction

•Sheet Properties

•Creping Moisture

•Strength

•Debonding

•Crepe ratio

•Coatings

Creping

Sheet Debonding

0 4 8 12 16 20 0

Debonding In Creping Process

Effect of Adhesion and Blade Geometry

Adhesion To Dryer (g/in)

80 Pocket

70 Pocket

60 Pocket

50 60 70 80 90 100

Dryer Adhesion vs Sheet Dryness

Sheet Dryness, %

Strength - Softness Curve Facial Tissue

Invariant Tensile Strength (g/ 3” sheet)

0 200 400 600 800 1,000 1,200 1,400

Strength - Softness Curve Facial Panel Softness

Invariant Tensile Strength (g/3”)

0 400 800 1,200 1,600 2,000 0

Historical Line

Closed Pocket Angle

Open Pocket Angle

Very Open Pocket

0 1,000 1,400 1,800 2,200

Overall Strength (g)

Facial Tissue Brand / Structural Comparison

Sheet Debonding vs. Stiffness

% Debonding/ Length

Sensory Panel Stiffness

15.0 Marcal 7.4

30.0 6.0

Secondary Fiber Kleenex

Virgin Fiber Kleenex

Regular Puffs

Kleenex Softique

New Puffs

Panel Stiffness

Reel Doctor Blade

Crepe Ratio

Crepe Ratio = V 2 / V1

where:

V 2 is Reel surface speed V 1 is Yankee Dryer surface speed

Bulk Development in Creped Wadding

1 2 3 4 5

Crepe Ratio

90 Pocket

80 Pocket

Debonding In Creping

Weak Points KOTEX ® TYPE WADDING

Closed Pocket, High Adhesion

Uniformly Debonded, No Weak Points KLEENEX ® FACIAL WADDING

Open Pocket, High Adhesion

•Introduction

•Sheet Properties

•Coatings

•Definition

•Inorganic Coatings

•Organic Coatings

•Application Systems

Creping

Title of Chart

"Advanced" Coatings "Natural" Coatings

Organic From

Fibers

Organic From

Fibers

Inorganic

Embedded

Fibers Embedded

Fibers

Synthetic

Additives

Title of Chart

Inorganic Salts

•100 ppm Calcium needed to form good coatings

•Some must harden water to achieve

•More than 600 ppm will cause excessive scaling elsewhere

Organic From

Fibers

Embedded

Fibers

Inorganic

Creping Adhesive References

Poly-(aminoamides) Winslow.Spicer 1972:Giles.Espy 1975:Oliver 1980:Schoreer et al.1982: Soerens 1985.1987 : Obokata.Takizawa 1990

Polyamides Lazorisak et al. 1977: Pomplu.Grube 1984 : Marzullo 1987: Chen et al. 1989: Soerens 1991

Polyamines Lazorisak et al. 1977: Latimer.Stevens 1983: Soerens 1991

Polyvinyl Alcohol Bates 1975: Grube.Ries 1981: Pomplun.Grube 1984: Soerens 1985 : Pippen 1987; Soerens 1987: Chen et al. 1989:Soerens 1991

Polyvinyl acetate & copolymers

Grossman1977: Lazorisak et al.1977: Grube.Ries 1981: Pomplun.Grube1984 : Pippen1987: Chen et al 1989

Polyethers & copolymers polycrylic acid

Pomplu.Grube 1984: Soerens 1991 : Lazorisak et al. 1977:

Animal glue Fuxelius 1967: Sanford.Sisson 1967: Lazorisak et al. 1977: Oliver 1980

Starch Fuxelis 1967: Salvucci. Yannos 1974: Oliver 1980

Cellulose derivatives Grossman 1977: Marzullo 1987

Title of Chart

Absorption Diffusion

Mechanical Interlocking

Weak Boundary

Layers

Chemical Bonding

Acid-Based Interactions

Electrostatic Attractions

Components of Adhesion

Strong adhesion between materials

is governed by two interactions:

• Intimate molecular contact closer than 9

angstroms (0.0000000009 meters). This is a

necessary condition.

•Maximum attractive force with minimum

potential energy. This is a sufficient condition.

(Chung 1991)

Cast Iron

Adhesive

Cotton Cloth

Peel Speed = 30 cm/min

Peel Adhesion Test

Adhesion Values

0.0 0.5 2.0 1.0 1.5 2.5 3.0 3.5 4.0

Concentration (% actives)

Sample 1 Sample 2 Sample 3 Sample 4 Sample 5

Typical Tensile Stress

Strain

Low Modulus

Strain

High Modulus

Strong

Brittle

Coating Requirements

• Must form uniform films

• Provide stable adhesion

• Be stable

• Have some re-wettability

• Have controllable hardness

Synthetic Additives

Organics from

Fibers

Inorganic

Embedded

Fibers

Thermoplastic

(rewettable)

Thermoset

(cross-linking)

Release

Kymene

• Good attraction to fibers (cationic)

•Strength increases with heating

•Crosslinking polymer

•Limited wettability

•Provides good dryer protection

•Minimum addition rate for dryer

protection is 0.35 kg/ton

• Nonionic (compatible with kymene)

• Good film former

• High cohesive strength

• Rewettable

• Different grades available

•% Hydrolysis

•Molecular Weight

• Typical application amounts: 0.3-2.5 kg/ton

based on tissue grade

Peel Adhesion

PVA / KYMENE MIXTURES

10 0 20 60 30 40 50 100 70 80 90 600

% Polyvinyl Alcohol (balance kymene)

Releases

• Modify coating

•Provide lubrication for doctor blade

•Examples

Quaternary Amines - Quaker 2008

Emulsified Oils - Cynol, Mulrex, Houghton

Polyglycol Esters - Hercules M-1336

•Quat. Amines and Esters provide less release

action

•Oils are powerful releases and difficult to

control to correct amount

What we spray on the dryer -

Water Polymer A Polymer B Release

Inorganic Salts

What is actually in the coating -

Cellulose fiber Ash?

Polymer A Polymer B

Inorganic Salts Release Water

Dryer Coating Composition (In order of % of mixture)

Coating Application System

Recirculation Line

Chemicals

Coating Application System

Hard Water

Chemicals

Mixer Spray Boom & Nozzles Filters (2)

Yankee Surface Pressure

Gauges

Booster Pump

Variable Speed Chemical Metering Pumps (Gear)

Mass Flowmeters

In-line

VS VS VS

FIC FIC FIC

Valves

Metering Pumps

Advantages

Disadvantages

• Inexpensive

•Uneven flow, possible hammering in lines

•Pulsation dampers needed

•More Accurate

•Infinite speed adjustment

• Expensive

•Reduces nozzle plugging from:

•Water source •Undissolved PVA •Bacteria "slugs"

•Should be placed close to application

•Progressively finer screens as

you move down steam

Filters

•Must be safe and convenient for operator

•Should have:

•Gauge cocks to isolate tips •Separate cross bars w/individual bodies for each tip •Removable booms

•Typical set-up: 15 cm apart, 12-20 cm away from yankee, 700 900 kPa supply pressure

•K-C uses Spraying Systems Unijet® nozzles

•Spray angles range from 65 - 110

•Flowrates range from .025 - .100 gpm

•Nozzle part number tells flowrate and spray angle at 275 kPa

Example:

80 Spray Angle .100 gpm Flowrate

65 0050

65 Spray angle .050 gpm Flowrate

Spray Nozzles

Spray Nozzle Geometry

O/2 O/2

20 40 60 100 80 120 140 160 200 180

Spraying Systems Uni Jet Nozzles

650025

Nozzle Pressure (PSI)

650025

Spraying Systems Vee Jet Nozzles

0 20 40 60 100 80 120 140 160 200 180

650025 650033

650050

650067

Pressure (PSI)

Volumetric Distribution of Spray Nozzle For A New Nozzle

0 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 1

Spray Pattern

31 3 5 7 9 11 13 15 17 19 21 23 25 27 29 1 0

Volumetric Distribution of a Spray Nozzle For a worn nozzle

Volumetric Distribution of Spray Nozzle Double Coverage - New Nozzles

0 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 1

Spray Pattern

Volumetric Distribution of Spray Nozzle Double Coverage - Worn Nozzles

3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 1

Spray Pattern

Volumetric Distribution Spray Coverage Triple Coverage - New Nozzles

Spray Pattern

9 5 13 17 21 25 29

Volumetric Distribution Spray Coverage Triple Coverage - Worn Nozzles

1 5 9 13 17 21 25 29 Spray Pattern

Drying Load (for coating application)

Nozzle

Pressure

Spacing

Nozzle

Coverage

Nozzle

Number of

Nozzles

Consumption

% of Total

Steam Flow

(kg/cm 2 ) (cm) (LPM) (LPM) (KG/HR)

650050

650067

Spray System

Recommendations

Spray Tips - 650050

Coverage - Double Overlap / 5 Offset

Boom - Easily Changeable Tips/Booms

Filters - 70 to 100 Microns

Pumps - Gear Pumps

Mixing - Direct Injection

Water - 100+ ppm Calcium and Alkalinity

Temperature - As is (non heated)

Flow Meters - Micromotion (Mass Flowmeters)

Chemicals - PVA/Kymene/Release

Adhesive Type Comments

poly (aminoamides) Commercial materials crosslinked with epichlorohydrin 48-70

polyamides polyacrylamide 165 ployvinyl pyrrolidone 126-174

polyamines commercial ethylene dichloride alkylamine type -18-20

polyvinyl alcohols commercial 68-75

polyvinyl acetate 28

polyethers polyethylene oxide (PEO) -67 polypropylene oxide (PPO) -75

poly (acrylic acid) 106

cellulose derivatives methyl cellulose 150 ethyl cellulose 43

hemicellulose various types 150-220

Glass Transition Temperatures of Common

Dryer Coating Chemicals

T (C) g

Creping. Tissue machine creping

Engineering