UV CURING BASICS - Heraeus Group

UV CURING BASICSBroadband & LED Technology and Applications by Heraeus Noblelight

HOUSEKEEPING

Webinar duration: presentation: 30-40 min with additional 20 min for Q&A

This webinar will be recorded and every registrant will receive a link to therecording and handouts

All attendees are muted by default

Questions can be submitted ONLY via Go To Webinar Question’s box at anytime, we will address them at the end of the presentation

If you are joining via “Computer audio”, we recommend using a headset

If there is an issue with your internet connection, you can always dial in viaphone

Online Session: UV Curing Basics / Broadband & LED Technology and Applications

AGENDA

Introduction to Heraeus and Heraeus NoblelightPrinciples of UV curing: chemistry, process, UV lamp systemsBenefits of UV LEDs: explore customer cases Q&A session


AGENDA



HERAEUS – A GLOBALLY SUCCESSFUL PORTFOLIO COMPANY


EMPLOYEES2

14,900

R&D EXPENDITURES17%

Listed in FORTUNE GLOBAL 500

TOTAL REVENUE

20.3 bn €

1 based on revenues excl. Precious Metals 2 incl. contract employees

25%

17%America

REVENUE EXCL. PRECIOUS METALS2018 BY REGION

EMPLOYEES2018 BY REGION

19%

15%

Rest ofEurope

11%

39%Germany

2%

1%

Africa /Australia

43%

28%Asia

More thanSITESin COUNTRIES40

100

GLOBAL BUSINESS UNITS

Market-oriented distributionin 11

TOP 10 FAMILY-OWNED COMPANIES

in Germany

6/22/20206

› 10+ years of experience in UV LED mechanical & electrical engineering, optical & thermal simulations, photon management and production.

› Manufactured in Germany in fully automated state-of-the-art production lines. In-house qualification of chips delivers better and more consistent quality. Tests include electrical and thermal connections on the chips.

› Value Chain control with own production of patented primary optics, of silver paste and gold wire. Full traceability of assembled material, inline process parameters, final inspection measurement data

› Independent measurement laboratory accredited as a test laboratory and local Application Competence Centers (ACCs) for in-house trials with the support of experienced chemists.

HERAEUS UV LED

Online Session: UV Curing Basics / Broadband & LED Technology and Applications6/22/20207

AGENDA



› UV curing is based on a photochemical reaction› Fast, immediate process due to UV irradiation› No outgassing and no loss of coating thickness› Solvent-free› Free radical polymerization process is typical (shown)


SUBSTRATE

POLYMERCOATINGLAYER

SOLID

OLIGOMER, MONOMER, PHOTOINITIATOR

SUBSTRATE

UV LIGHT

COATINGLAYER

LIQUID

Polymer chains are built up and crosslinked into a 3-dimensional network using a photoinitiated polymerization process.Within a split second, the cross-linked system is dry and abrasion-proof and can immediately be processed in the next production step.

6/22/20209

UV CURING PROCESS

APPLICATION AND INDUSTRIES FOR UV CURING


AUTOMOTIVE INDUSTRY

COATING OF SURFACES

PRINTING INDUSTRY (DIGITAL, FLEXO,

SCREEN PRINTING)

METAL DECORATING& BOTTOM RIM

COATING

ELECTRONICS COATINGS & ASSEMBLY

GLASS DECORATING FIBER OPTICS

ADHESIVE AND PAINT CURING

6/22/202010

FACTORS THAT INFLUENCE THE UV PROCESS


› Spectral distribution› Irradiance and energy› Energy distribution› IR-radiation

UV lamp system

› Chemical components› Spectral absorption› Spectral reaction› Optical thickness

Formulation

› Dispensing method› Layer thickness› Process speed› Substrate

Product

6/22/202011

COMPONENTS OF A UV CURABLE FORMULATION


Photoinitiator

Additives

Monomers

Oligomers

Molecules that absorb UV light and initiate polymerisation process

Pigments, flow control agents, matting agents, fillers etc

Molecules crosslink with each other &with oligomers.Viscosity reduction. Contribute to coating performance characteristics

High molecular weight molecules with reactive sites. Key coating performance characteristics.

6/22/202012

PHOTOINITIATORS


Initiation reaction

Polymerization process

M M●●

OO

MM

MO

● ●

Initiation

Propagation

Photoinitiator

ORー

O●

R●

Initiation species generation

photons

Hg lamp UV LED lampPhotochemical process

PHOTOINITIATORS


Surface cure Through cure and adhesion

Absorbance of 4 different photo initiators

KEY FEATURES OF A UV LAMP SYSTEM


Irradiance, W/cm2

Profile of radiant power arriving at a surface, in a specific waveband Usually peak irradiance is reported

Energy, J/cm2

Spectral output

6/22/202015

Distance or time

Area under curve is proportional to total energy

Irradiance Profile(Not a function of speed)

Peak

1 2 3 4 5 6 7 8 9 10 11


PEAK IRRADIANCE & TOTAL ENERGY

6/22/202016

0,0

0,5

1,0

1,5

2,0

2,5

3,0

50 75 100 125 150 175

Irrad

ianc

e [W

/cm

²]

Distance from lamp [mm]


IRRADIANCE & DISTANCE TO THE SURFACE

6/22/202017

Semray® UV4000 UV LED lampMicrowave powered UV lamp, 240W/cm H bulb



Irradiance, W/cm2


Energy, J/cm2

Total energy arriving at a surface in a given timeTime integral of the irradiance profileInverse of speed

Spectral output

6/22/202018

Distance or time

Area under curve is proportional to total energy

Irradiance Profile(Not a function of speed)

Peak

1 2 3 4 5 6 7 8 9 10 11


PEAK IRRADIANCE & TOTAL ENERGY

6/22/202019



Irradiance, W/cm2


Energy, J/cm2

Total energy arriving at a surface in a given timeTime integral of the irradiance profileInverse of speed

Spectral outputRelative radiant output versus wavelength (nm)

6/22/202020


Spectra of different microwave-powered bulbs

6/22/202021

UV SPECTRAL OUTPUT

SPECTRAL OUTPUT


Semray® UV4000 series output wavelength

PENETRATION OF MATERIAL BY UV RADIATION


UV Coating

Substrate

1- 60µm

200 – 280 nmHigh energy UV lightfor top surface curing

315 – 380 nmUV closest to the visible spectrum

to cure deep layers, e.g. highly pigmented lacquers and thick varnish layers

280 – 315 nmLonger wavelength for

deeper penetration

UVC UVB UVA Optical thickness of a curable film determines to what extent irradiance will affect depth of cure and adhesion.

Spectral absorbance of coatings will affect which wavelengths will more effectively penetrate and how the irradiance level will achieve depth of cure.

Absorption spectrum of the photoinitiator will determine the wavelength responsivity.

6/22/202023

› Oxygen is present on the surface & dissolved in the bulk of the formulation

› Reduces the efficiency of photoinitiators› Formation of peroxy radicals reduces

polymerization process› Variation in double bond conversion through

the depth of coating

OXYGEN INHIBITION - CHALLENGE FOR SURFACE CURE WITH UV LED


Challenge – lack of short wavelength output › Absorbed in top layers of coatings› Overcome problems caused by oxygen inhibition

› Tacky surface

Challenge – lack of short wavelength output › Optimise formulation› Cure in inert atmosphere › Combine with other UV lamps, e.g. med. pressure Hg › Ensure high UV irradiance reaches the coating

surface› Higher power UV LED lamp

› Increase concentration of initiating & propagating radicals

UV LED CHALLENGES – WORKING DISTANCE


Working distance› As distance increases, intensity of UV decreases› Reduces cure speed of the coating› Some applications may not be possible:

› Intensity/energy reaching coating is too low› Physically need lamps to be further away

› Optimise micro-optics within the UV LED lamp› Ensure minimum stray light

› Micro-optics reduce exit angle from 120° to 60°› 30% higher UV energy reaches the substrate › Possibility to cure coatings at larger or variable

working distances

PHOTOPOLYMERISATION WITH UV BROAD BAND LAMP & UV LED LAMP


Similarities› Principle of UV curing› Photopolymerization process› Used for both free radical & cationic curing› Components UV formulation› UV curing system design considerations› Process & application development process

Differences› Reduced heat delivered to coating during curing› No ozone generation› Lack of short wavelength UV impacts surface cure› Restricted photoinitiator choice matching narrow

band LED emission

AGENDA



DIFFERENT SOLUTIONS FOR DIFFERENT APPLICATIONS


› Irradiance values & Power class› Optical concepts› Different cooling concepts› Complete UV LED systems

Medium Power Class

High End Class

High Power Class

UV5000 Series

UV7000 Series

UV4000 Series

60+

40-60

20-40Pinning Class

UV2000 Series<20

CASE STUDY – NANO IMPRINT


Request› UV irradiance adjustment for

different line speeds / coating compositions

› Homogeneity and flexibility for different substrate widths

› High power at 365 nm› Oxygen inhibition

Development› Joint trials at Heraeus ACC

(lab and demo center)› Process validation tests› Machine integration meetings

Solution› UV4000 BP-16 with Semray

UV4003 365 nm [primary optics]› Interface control integration for

automatic or manual control of irradiation width and UV irradiance

› High power for 365 nm with 13 W/cm2 at the emission window

› Press the coating on the roll to exclude oxygen

6/22/202029

CASE STUDY – BOTTLE PRINTING


Request › Replace outdated mercury system› Print speed:

83 ft/min / 25 m/min› Curing distance:

3 inches / 76 mm› Maintain production speed of

30 to 60 bottles per min.

Development› Trials at Heraeus lab and OEM

demo center› Customer validation tests› Machine integration meetings

Solution› Flexible LED installation at

demo center› Exchange of wavelength in

seconds› Flexibility of integration› 75% Energy savings

6/22/202030

ENERGY SAVINGS ESTIMATIONS


$-

$10.000

$20.000

$30.000

$40.000

$50.000

$60.000

$70.000

$80.000

0 0,2 0,4 0,6 0,8 1 1,2

USD

Time (years)

Electrical Cost Comparison (kWh)

Hg lamp LED

CASE STUDY – CABLE MARKING


Request › Develop a powerful air-cooled small

format LED system for curing at marking speeds

› Print speed: 650 ft/min - 200 m/min › Curing distance: 1 inch – 25 mm› Support both side curing

Development› Trials at OEM due to project

confidentiality› First initial tests done with Heraeus

LED Altair› Semray 4003 introduced six months

later› Customer validation tests

Solution› Compact LED design › Power modulation adjustable to

line speeds› Cost effective reflective solution› Semray micro optics allow focus

on small footprint

6/22/202032

AGENDA

Introduction to Heraeus and Heraeus NoblelightPrinciples of UV curing: chemistry, process, UV lamp systemsBenefits of UV LEDs: explore customer casesQ&A


Many thanks for your participation.

heraeus-noblelight.com/[email protected]

Date post:	04-Feb-2022
Category:	Documents
Upload:	others
View:	9 times
Download:	1 times

UV CURING BASICS - Heraeus Group

Documents