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UV Curable Adhesives – Achieving Success through Formulation
2017 Adhesives and Sealant ConventionApril 4, 2017Atlanta, GA
Neil Cramer, Mike Idacavage, Ashten Vogelsberg, Tara Scott and Amelia Davenport
Colorado Photopolymer Solutions
Mechanical Bonding Increase roughness by abrading surface Chemically etch the surface Swell substrate to promote penetration of
coating (Plastics)
Chemical Bonding Surface Modification Residual Functional Groups
Diffusive Polymer Entanglement
Dispersive Van Der Waals
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Adhesion promoters are materials that are added to a formulation to enhance adhesion
Typically added in relatively small amounts There are a wide range of different types of
adhesion promoters for different substrates and applications
• Acrylic acrylates• Carbonyls• Chlorinated• Phosphates
• Carboxylic Acid Groups
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ASTM Tape Test Procedure Glass, Steel, ABS, PC –
substrate
125 um drawdown bar
Irradiate with broadband or LED
Cross hatch with razor blade
Peel with scotch tape
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Formulations contain 4 wt% photoinitiator HCPK Broadband UV light source 125 µm drawdown bar Adhesion tested using a cross hatch adhesion tape test
TMP(EO)3TA Exhibits good adhesion to PC & ABS w/o adhesion promoters Exhibits poor adhesion to glass & structural steel
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Formulations contain 10 wt% added adhesion promoter
TMP(EO)3TA Exhibits poor adhesion to glass & structural steel w/CEA Exhibits good adhesion to glass & structural steel w/Phosphate
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Aliphatic Urethane Acrylate Exhibits good adhesion to PC & ABS w/o adhesion promoters Exhibits poor adhesion to glass & structural steel
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Formulations contain 10 wt% added adhesion promoter
Aliphatic Urethane Acrylate Exhibits good adhesion to glass & structural steel w/CEA Exhibits good adhesion to glass & structural steel w/Phosphate
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Thiol-Ene Exhibits good adhesion to PC & ABS w/o adhesion promoters Exhibits poor adhesion to glass & structural steel
SH
SH
HS
= =
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Formulations contain 10 wt% added adhesion promoter
Thiol-Ene Exhibits poor adhesion to glass & structural steel w/CEA Exhibits good adhesion to glass & structural steel w/Phosphate
SH
SH
HS
= =
=
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Good adhesion to PC & ABS – across all systems Adhesion to Glass & Structural Steel varies w/CEA – Formulation
Dependent Adhesion to Glass & Structural Steel good w/Phosphate –
Formulation Independent
Three different formulation chemistries Four different common substrates Two different common adhesion promoters
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No significant differences in adhesion
HCPK vs TPO as photoinitiator Formulations with HCPK were cured with a broadband mercury
source Formulations with TPO were cured with a 385 nm LED
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Photoinitiator does not affect adhesion Irradiation source does not affect adhesion
TMP(EO)3TA CEA/Phosphate –HCPK/TPO
Aliphatic Urethane Diacrylate CEA/Phosphate –HCPK/TPO
Thiol-Ene CEA/Phosphate –HCPK/TPO
Broadband vs 385 nm vs 405 nm
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ViscosityWetting/Diffusive
Modulus, Shrinkage & StressFilm Integrity/Surface Interaction
Polymerization MechanismShrinkage, Stress, Surface Interaction
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Film Integrity: Film Thickness & Modulus
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Adhesion is better for rubbery materials18
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CEA is a relatively poor adhesion promoter for glass with TMP(EO)3TA & Thiol-Ene
~ 30 wt% CEA is required for adhesion to steel Results are formulation dependent
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~ 8 – 20 wt% Phosphate is required for adhesion to glass ~ 5 - 20 wt% Phosphate is required for adhesion to steel Results are formulation dependent
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OLIGOMER
ADDITIVES
MONOMERS
PHOTOINITIATORS
Fully Formulated Industrial Metal Coating
Component PropertiesBase Acrylate Monomer (50-80%) Base Properties & Viscosity
Oligomer (10-25%) ToughThiol Monomer (5-25%) Reduce Oxygen Inhibition
Adhesion Promoter (5-15%) Adhere to MetalsPhotoinitiator (1-6%) Achieve Rapid Curing
Inhibitor (< 1%) Stabilize Formulation[Optional] White Pigment (1-5%) Colored Resin
[Optional] Glass Filler (1-5%) Increase Viscosity/Scratch Resistance
Formulation Tested on metal for Adhesion using cross-hatch testing
Adhesion properties are independent of photoinitiator type and irradiation source
Phosphate is a good all-purpose adhesion promoterFormulations may be hazy
Thicker formulations (~250 um) exhibit better adhesion than thinner formulations (~ 50 um)
Rubbery materials exhibit better adhesion than glassy materials
Optimized adhesion promoter concentrations are formulation and thickness dependent
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IGM Resins Donation of materials
Miwon North America Inc Donation of materials
Dymax Oligomers & Coatings BlueWave® 405 nm LED Flood System
Sartomer Donation of materials
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Thank You!
Contact information:Dr. Mike J. IdacavageVP Business DevelopmentColorado Photopolymer Solutions1880 S. Flatiron Ct, Suite JBoulder, CO 80301303-551-3213mike.idacavage@cpspolymers.comwww.cpspolymers.com
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