- 1. Crosslinking Technology for Latex or Acrylic Emulsions Katie
L. Skok and Roeland J. Tuinman, PhD Auburn Hills, Michigan
2. Emulsion Polymer Isocyanate Adhesives
- An EPI consists of two components:
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- A water based emulsion polymer
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- Poly Vinyl Acetate (PVAc)
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- Ethylene Vinyl Acetates (EVA)
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- An isocyanate crosslinker
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- Emulsifiable Polymeric MDI (EPMDI)
3. Emulsion Polymer Background
- PVA and EVA Dispersion Adhesives
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- Thermoplastic (not cured)
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- Low strength at high moisture levels
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- Good flow, but little penetration into surfaces
Polyvinyl acetate homopolymer Common white glue Carpenters glue
4. Emulsion Polymer Background
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- Better resistance to water and solvents
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- More expensive than PVA type
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- Bonds a variety of substrates
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- More expensive than PVA type
Pressure Sensitive Adhesives Adhesive for carpet backing 5. MDI
Background
- M ethyleneD i-Phenyl Di- I socyanate
Polymeric MDI Fn=2.7 Pure MDIs Fn=2.0 6. Emulsifiable MDI 50/50
blend of water and MDI RUBINATE M Polymeric MDI RUBINATE 9259
Emulsifiable MDI
- Emulsifiable Polymeric MDI Advantages
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- Does not easily separate after mixing
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- Faster reactivities achieved
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- Quicker strength build up achieved
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- Stronger overall physical properties
- What is an Emulsifiable MDI?
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- An isocyanate which has been modified by adding hydrophilic
solubolising groups to become easily emulsified in water
7. Product Data
- Huntsman Product Offering
Recommended as Crosslinker for Emulsion Polymer Adhesives 139
2.67 1.23 210 30.2 RUBINATE 9259 Isocyanate 2.70 2.70 2.69
Functionality 135 1.23 190 31.2 RUBINATE M Isocyanate 135 1.23 400
31.2 SUPRASEC 9600 Isocyanate 135 1.23 220 31.0 RUBINATE 9236
Isocyanate Equivalent Weight Specific Gravity @25C Viscosity (cps)
%NCO 8. Emulsifiable MDI for Emulsion Polymer Adhesives
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- Standard product for use as a crosslinker for Latex
emulsions
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- Similar in performance to RUBINATE 9236
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- Provides an extended open time
9. Formulating Approaches
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- Hydroxy functionalized emulsion latex
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- Number of hydroxy groups can control crosslinking
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- Latex copolymers can be varied to allow a wide range of
stress-strain behaviors
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- pH of the latex will affect reactivity
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- Amount added, affects degree of crosslinking
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- Generally between 1% and 20%
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- Type can affect reactivity and build of green strength
10. Typical Emulsion Formulation 9.4% Water 0.2% Air Products
Dynol 604 Dispersant 0.2% Rohm & Haas Rocima BTNV2 Biocide 0.2%
Air Products Surfonyl DF-210 Defoamer 35.0% Celanese 10% Cevol 523
Polyvinyl Alcohol 25.0% Omya OmyaCarb 5 Calcium Carbonate 30.0% 50%
Solids; 6.0 pH; Anionic Surfactant SB Latex 85.0% Emulsion Polymer
15.0% SUPRASEC 9600 or RUBINATE 9236 MDI Isocyanate 11. Lap Shear
Adhesion * Fastest adhesive strength build up * 12. Viscosity
Profiles * Suprasec 9600 builds viscosity at a slower rate * 13.
EPI Adhesive Applications
- Adhesives for bonding wood to:
- High performance wet-use adhesives for wood bonding
Adhesive for Doors and Windows 14. Door and Window Adhesive
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- Improved adhesion at low and elevated temps
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- Good water resistance and durability
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- Faster development of adhesive strength
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- Improved physical properties
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- Adhesives used for Laminate Joints in Nonstructural Lumber
Products
15. ASTM D-5751
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- Specimens submerged under water and sealed in a vacuum at 25
inch of Hg for 30 minutes
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- Followed by pressurizing the tank to 75 PSI for 30 minutes
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- Samples are boiled for 4 hrs and then placed in an oven at 160F
for 20 hours
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- The 4 hour boil is repeated
16. Photos of ASTM-D5751 Glue line Wood Failure 17. ASTM D-5751
18. Conclusions
- The addition of a MDI crosslinker to an emulsion polymer:
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- Increases green strength development
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- Increases overall physical properties
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- Is necessary for wet use applications
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- Flexibility in reactivity rate
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- Higher physical properties than traditional MDI
19. Conclusions (cont.)
- Huntsman is a leader in Emulsifiable MDI technology
- For EPI adhesive applications use:
New Product Longer open times achieved! 20. Thank You!