ENERGY CURABLE TECHNLGIES CHRIS RILALL, PHD SARTMER AMERICAS ARKEMA INC.
UTLINE Advantages of UV/EB Curing Energy Sources (UV vs EB, Lamps, LED) Photo-initiators Monomers and ligomers 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 twopart film forming methods. Energy Curing or UV/EB Curing often used interchangeably with Radiation Curing 3
PRCESS VERVIEW F UV/EB CURING UV/EB Unit UV/EB formulation CATING UNIT/ INKJET 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 4
ENERGY CURING INDUSTRIAL APPLICATINS Coatings Adhesives Graphic Arts PV Inkjet Inks Developments Heat transfer labels Lowextractable food applications Adhesives UV/EB Anaerobic Construction Laminating PSA Coatings Wood Metal Industrial ptical fiber Cosmetic Flooring/ roofing/ road marking Developments Coil Electronics Wood Metal Industrial Dry film Display ptical fiber Solar Cosmetic Flooring/roofing/road Photopolymer plates Marking Coil Liquid resists Developments Advanced Materials Artificial marble Lenses 3D printing (stereo lithography) Dental Composites Electrical insulation Vacuum impregnation Chemical thers UV/EB Intermediates ptically SAP clear adhesives Anaerobic il field Leather/ Construction textile PVC plastisol Dispersing agents Rubber Epoxy modification 5
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 UV Lamp hv (light) + free radical 6
ELECTRN BEAM CURING Electrons emitted from a filament and accelerated to high energies Can cure thick sections or through opaque substrates Radicals 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 Electron Beam 7
UV CURING - ELECTRMAGNETIC SPECTRUM Range for UV/Visible Curing 8
UV CURING LAMPS 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 9
UV-LED SPECTRAL DISTRIBUTIN UV-LED units provide a single wavelength (narrow distribution) High energy output in UVA range vs broad spectrum utput is concentrated at long UV wavelengths phoseon.com 10
WHAT S IN A TYPICAL FRMULATIN? Conventional Liquid Coating Energy Cured Formulation N/A Pigments, Fillers Leveling, Flow, Wetting Aids Defoamer, Biocide, etc Initiator Additives Photoinitiator (for UV) Pigments, Fillers Leveling, Flow, Wetting Aids Defoamer, Biocide, etc Water or Solvents Diluent Monomer reactive diluents SR351 - TMPTA Thermoplastic Polymers Binder Reactive ligomers H H 11
RADICAL PHTINITIATRS TW TYPES Norrish Type I Unimolecular Cleavage Irgacure 184 or PL-CPK (α-hydroxy ketone) H h υ + H initiation Norrish Type II Bimolecular H* Abstraction Requires a Curing Synergist Amine or Ether containing monomer H Benzophenone h υ R 2 N R " inactive + R 2 N R " H initiating H H 12
PI SELECTIN FR THRUGH AND SURFACE CURE Shorter UV wavelength Longer UV wavelength Monomer ligomer Pigments Stabilizers Fillers Additives SUBSTRATE Fillers Additives Monomer ligomer Pigments Stabilizers SUBSTRATE 200-350 nm PI Absorption 350-440 nm Use PI Cocktail for best results Clearcoats Thin coatings Surface cure Applications Pigmented coatings/inks Thick coatings (>4 mil) Through cure 13
MATCHING EMISSIN SPECTRUM F LAMPS T PHTINITIATR Emission V-bulb (300w/in) V-Bulb 200 150 100 50 V-Bulb TP 100 80 60 40 20 % Absorption Good match with V-bulb through cure Absorbance in LED range 385-405 nm Irgacure TP, PL-TP C P 0 280 310 330 350 370 390 410 430 450 0 14
RAW MATERIALS FR FREE RADICAL UV/EB CURING Acrylates: Fast cure, good properties balance, huge range of options R Methacrylates: Slower cure, can improve heat resistance and strength R ther classes such as vinyl ether, unsaturated polyester, allylics much less used 15
(METH)ACRYLATE MNMER RLE IN FRMULATIN 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 16
(METH)ACRYLATE FUNCTINALITY & PRPERTIES Property Mono Di Tri Tetra Penta Cure Speed Slow Fast Flexibility Flexible Brittle Hardness Soft Hard Solvent Resistance Less Best Shrinkage Low High 17
LIGMER RLE AND TYPES Binder Replaces Resin/Polymer from Conventional Formulation. Provides Most of the Properties of the Cured Film Epoxy Acrylates Urethane Acrylates Polyester Acrylates Amino Acrylates Specialty BPA Types most common. Hard, brittle, fast cure, yellowing Aliphatics and modified types more flexible Very flexible to very hard (functionality), tough and strong Excellent weathering for aliphatics Relatively low viscosity, good adhesion and pigment wetting Cost/Performance balance vs epoxies and urethanes Curing synergists increase surface cure Polyether/ester amines adhesion, fast cure Adhesion promoters acidic, polyester or acrylic for plastics, metal, glass 18
19 URETHANE ACRYLATE STRUCTURE & PRPERTIES
EFFECT F BACKBNE STRUCTURE N MVTR 120 100 MVTR (g*mil/m2*day) 80 60 40 20 Neat ligomer 20% HDDA 20% TCDMDA 50% TCDMDA 0 HHP HHPUA 20
CNTRLLING DIELECTRIC CNSTANT F FRMULATINS PR 13832 PR 13833 PR 13834 ligomer Description Polybutadiene Backbone Aliphatic Urethane Acrylate Polyester Backbone Aliphatic Urethane Acrylate Average Dielectric Constant (D150) 1.93 2.19 2.21 PR 13835 2.48 PR 13836 Polyether Backbone Aliphatic Urethane Acrylate 2.54 Monomer effect PR 13837 2.23 PR 13838 2.06 PR 13839 Polycarbonate Aliphatic Urethane Acrylate 2.27 21
APPLICATINS FR PRINTED/ FLEXIBLE ELECTRNICS Moisture and xygen Barrier Layer Coatings Resins for Liquid ptically Clear Adhesives (LCA) (Pressure Sensitive / Laminating/ Assembly) Adhesives 3D Printing Resins Dispersion medium for Quantum Dots ptically Clear Hard Coats Scratch Resistant Coatings Hepatic Coatings (e.g., Soft Touch) 22
CRE CMPETENCE: (METH)ACRYLATE CHEMISTRY Backbone Acrylate or Methacrylate H or CH 3 R n Functionality (Allylic, Carboxylic & Hydroxyl) Monomers: Low molecular weight Low viscosity/ reactive diluents Unique building blocks ligomers: High molecular weight; Backbone of the formulations; Provides the key properties 23