Crosslinkers For Latex Adhesives 2008
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Transcript of Crosslinkers For Latex Adhesives 2008
- 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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- Styrene- Butadiene (SB)
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- Acrylics
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- An isocyanate crosslinker
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- Polymeric MDI (PMDI)
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- Emulsifiable Polymeric MDI (EPMDI)
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3. Emulsion Polymer Background
- PVA and EVA Dispersion Adhesives
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- Nontoxic
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- Low VOC
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- Dispersed in water
- Limitations
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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
- SB latex
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- Better resistance to water and solvents
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- Good low temp properties
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- More expensive than PVA type
- Acrylic emulsions
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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
- MDI
- 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
- RUBINATE 9236Isocyanate
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- Standard product for use as a crosslinker for Latex emulsions
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- Improves adhesion
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- Chemical resistance
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- Physical properties
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- SUPRASEC 9600Isocyanate
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- Similar in performance to RUBINATE 9236
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- Provides an extended open time
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- Strength build maximized
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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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- Isocyanate
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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
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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:
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- Phenolic papers
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- Plastics
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- Metals
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- Wood
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- Concrete
- High performance wet-use adhesives for wood bonding
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- Edge to edge
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- Finger joints
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- Laminating
Adhesive for Doors and Windows 14. Door and Window Adhesive
- Benefits of an EPI
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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
- Test Requirements
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- ASTM D 5751
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- Adhesives used for Laminate Joints in Nonstructural Lumber Products
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15. ASTM D-5751
- Dry
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- Specimens tested as is
- Vacuum/Pressure test
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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 tested wet
- Boiling
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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
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- Samples tested wet
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
- Emulsifiable MDIs:
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- Provide better mixing
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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:
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- Rubinate 9236
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- Fast strength build up
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- Fast viscosity build up
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- Suprasec 9600
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- Fast strength build up
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- Slower viscosity build
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New Product Longer open times achieved! 20. Thank You!