ENERGY CURABLE TECHNOLOGIES

CHRIS ORILALL, PHDSARTOMER AMERICAS

ARKEMA INC.

OUTLINE

Advantages of UV/EB Curing

Energy Sources (UV vs EB, Lamps, LED)

Photo-initiators

Monomers and Oligomers

Structure Property Relationships

WHAT IS ENERGY CURING?

Use of UV energy, visible light or high energy electrons to initiate polymerization to form a continuous coating, ink or adhesive film.

Alternative to thermal evaporation of solvents or water, oxidative (air) curing or two-part film forming methods.

“Energy Curing” or “UV/EB Curing” often used interchangeably with Radiation Curing

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PROCESS OVERVIEW OF UV/EB CURING

100% Solids System● No Solvent (less regulatory restrictions) or Water● Applied as a viscous liquid system● Eliminates the need for solvent extraction systems (no oven required)● Instant Cure● Tunable Properties by formulating approach

Equipment Advantages● Very high lines speed possible● Small equipment footprint● Reduced energy usage● Increased throughput/ lowered manufacturing cost● Retrofitting of existing lines possible

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UV/EB formulation

UV/EB Unit

COATING UNIT/INKJET

ENERGY CURING INDUSTRIAL APPLICATIONS

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Coatings

• Wood• Metal• Industrial• Optical fiber• Cosmetic• Flooring/roofing/road Marking

Developments

• Coil

Adhesives

• UV/EB• Optically clear adhesives• Anaerobic• Construction• PVC plastisol

GraphicArts

• OPV• Inkjet• Inks

Developments• Heat transfer

labels• Low-

extractable food applications

Adhesives

• UV/EB• Anaerobic• Construction• Laminating• PSA

Coatings

• Wood• Metal• Industrial• Optical fiber• Cosmetic• Flooring/

roofing/ road marking

Developments• Coil

Electronics

• Dry film• Display• Solar• Liquid resists• Photopolymer

plates

Advanced Materials

• Artificial marble

• Lenses• 3D printing

(stereo lithography)

• Dental• Composites• Electrical

insulation• Vacuum

impregnation

Chemical Intermediates

• SAP • Oil field• Leather/

textile• Dispersing

agents

Others

• Rubber• Epoxy

modification

UV (AND VISIBLE LIGHT) CURING

UV Lamp as source of energy

Requires Photoinitiator to absorb energy and initiate polymerization

Must match PI absorbance to lamp output

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hv (light) +

free radicalU

V La

mp

ELECTRON BEAM CURING

Electrons emitted from a filament and accelerated to high energies● Can cure thick sections or through opaque substratesRadicals formed by direct reaction of coating components with electrons ● No Photo-initiator required Cure method of choice for food packaging ● very high conversion/very low migratables

7

Elec

tron

Bea

m

UV CURING - ELECTROMAGNETIC SPECTRUM

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Range for UV/Visible Curing

UV CURING LAMPS

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• Clears• Thin films• Surface cure

• Pigmented systems• Deep cure• Thick film

• White pigmented• Visible light cure• Gloss control

Visible light cure

NB: Some processes use more than one type to achieve desired results, e.g., V bulb + D bulb in series

UV-LED SPECTRAL DISTRIBUTION

UV-LED units provide a “single” wavelength (narrow distribution)High energy output in UVA range vs broad spectrumOutput is concentrated at long UV wavelengths

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phoseon.com

WHAT’S IN A TYPICAL FORMULATION?

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Energy Cured FormulationConventional Liquid Coating

Binder

Diluent

Additives

Initiator Photoinitiator (for UV)

Pigments, Fillers Leveling, Flow, Wetting AidsDefoamer, Biocide, etc

Monomer reactive diluents

Reactive Oligomers

Pigments, Fillers Leveling, Flow, Wetting AidsDefoamer, Biocide, etc

N/A

Water or Solvents

Thermoplastic Polymers

O

O

O

O

O

OSR351 - TMPTA

O OOO

OHOH

O O

RADICAL PHOTOINITIATORS – TWO TYPES

Norrish Type I – Unimolecular Cleavage

Norrish Type II – Bimolecular H* Abstraction● Requires a Curing Synergist – Amine or Ether containing monomer

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Irgacure® 184 or PL-CPK (α-hydroxy ketone)

Benzophenone

OOH

hυ

O

+

OH

initiation

O

hυ

R2N R"

H H

OH

+R2N R"

Hinactive

initiating

PI SELECTION FOR THROUGH AND SURFACE CURE

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SUBSTRATE

Monomer Oligomer

FillersAdditives

PigmentsStabilizers

Shorter UV wavelength

SUBSTRATE

Monomer Oligomer

FillersAdditives

PigmentsStabilizers

Longer UV wavelength

200-350 nm PI Absorption 350-440 nm

Applications Pigmented coatings/inksThick coatings (>4 mil)Through cure

ClearcoatsThin coatingsSurface cure

Use PI Cocktail for best results

MATCHING EMISSION SPECTRUM OF LAMPS TO PHOTOINITIATOR

14

0

20

40

60

80

100

0

50

100

150

200

280 310 330 350 370 390 410 430 450

V-Bulb

TPO

Emis

sion

V-bu

lb (3

00w

/in)

% Absorption

C

O

P

O

Irgacure® TPO, PL-TPO

Good match with V-bulb –through cure

Absorbance in LED range 385-405 nm

V-Bulb

RAW MATERIALS FOR FREE RADICAL UV/EB CURING

Acrylates: Fast cure, good properties balance, huge range of options

Methacrylates: Slower cure, can improve heat resistance and strength

Other classes such as vinyl ether, unsaturated polyester, allylics much less used

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RO

O

RO

O

(METH)ACRYLATE MONOMER ROLE IN FORMULATION

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Reactive Diluent – Replaces Volatile Solvents Used in Conventional Formulations –Becomes Part of Final Product

Property Effect Result

Viscosity Diluency Formulation Viscosity

Surface Tension Wetting Flowout, Adhesion

Refractive Index Light Bending Gloss, Brightness

Solubility Parameter Compatibility Filler/Pigment Dispersion, Adhesion

Equivalent Weight Crosslink Density Hardness, Shrinkage

(METH)ACRYLATE FUNCTIONALITY & PROPERTIES

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Property Mono Di Tri Tetra Penta

Cure Speed Slow Fast

Flexibility Flexible Brittle

Hardness Soft Hard

Solvent Resistance Less Best

Shrinkage Low High

OLIGOMER ROLE AND TYPES

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Binder – Replaces Resin/Polymer from Conventional Formulation. Provides Most of the Properties of the Cured Film

• BPA Types most common. Hard, brittle, fast cure, yellowing • Aliphatics and modified types more flexibleEpoxy Acrylates• Very flexible to very hard (functionality), tough and strong• Excellent weathering for aliphaticsUrethane Acrylates• Relatively low viscosity, good adhesion and pigment wetting• Cost/Performance balance vs epoxies and urethanesPolyester Acrylates• Curing synergists – increase surface cure• Polyether/ester amines – adhesion, fast cureAmino Acrylates• Adhesion promoters – acidic, polyester or acrylic for plastics,

metal, glassSpecialty

URETHANE ACRYLATE STRUCTURE & PROPERTIES

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EFFECT OF BACKBONE STRUCTURE ON MVTR

20

0

20

40

60

80

100

120

HHP HHPUA

MVT

R (g

*mil/

m2*

day)

Neat Oligomer20% HDDA20% TCDMDA50% TCDMDA

CONTROLLING DIELECTRIC CONSTANT OF FORMULATIONS

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Oligomer Description

Average Dielectric Constant

(D150)

PRO 13832Polybutadiene Backbone

Aliphatic Urethane Acrylate1.93

PRO 13833Polyester Backbone

Aliphatic Urethane Acrylate2.19

PRO 13834

Polyether BackboneAliphatic Urethane Acrylate

2.21

PRO 13835 2.48

PRO 13836 2.54

PRO 13837 2.23

PRO 13838 2.06

PRO 13839Polycarbonate

Aliphatic Urethane Acrylate2.27

Monomer effect

APPLICATIONS FOR PRINTED/ FLEXIBLE ELECTRONICS

Moisture and Oxygen Barrier Layer Coatings

Resins for Liquid Optically Clear Adhesives (LOCA)

(Pressure Sensitive / Laminating/ Assembly) Adhesives

3D Printing Resins

Dispersion medium for Quantum Dots

Optically Clear Hard Coats

Scratch Resistant Coatings

Hepatic Coatings (e.g., Soft Touch)

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CORE COMPETENCE: (METH)ACRYLATE CHEMISTRY

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Monomers: Low molecular weightLow viscosity/ reactive diluentsUnique building blocks

Oligomers: High molecular weight; Backbone of the formulations; Provides the key properties

nO

O

H or CH3

R

Backbone

Functionality(Allylic,

Carboxylic & Hydroxyl)

Acrylate or Methacrylate