Crosslinkers For Latex Adhesives 2008
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Crosslinkers For Latex Adhesives 2008

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Crosslinkers For Latex Adhesives 2008 Crosslinkers For Latex Adhesives 2008 Presentation Transcript

  • Crosslinking Technology for Latex or Acrylic Emulsions Katie L. Skok and Roeland J. Tuinman, PhD Auburn Hills, Michigan
  • Emulsion Polymer Isocyanate Adhesives
    • An EPI consists of two components:
      • A water based emulsion polymer
        • Poly Vinyl Acetate (PVAc)
        • Ethylene Vinyl Acetates (EVA)
        • Styrene- Butadiene (SB)
        • Acrylics
      • An isocyanate crosslinker
        • Polymeric MDI (PMDI)
        • Emulsifiable Polymeric MDI (EPMDI)
  • Emulsion Polymer Background
    • PVA and EVA Dispersion Adhesives
      • Nontoxic
      • Low VOC
      • Dispersed in water
    • Limitations
      • Thermoplastic (not cured)
      • Low strength at high moisture levels
      • Good flow, but little penetration into surfaces
    Polyvinyl acetate homopolymer Common white glue Carpenters glue
  • Emulsion Polymer Background
    • SB latex
      • Better resistance to water and solvents
      • Good low temp properties
      • More expensive than PVA type
    • Acrylic emulsions
      • Bonds a variety of substrates
      • More expensive than PVA type
    Pressure Sensitive Adhesives Adhesive for carpet backing
  • MDI Background
    • MDI
    • M ethylene D i-Phenyl Di- I socyanate
    Polymeric MDI Fn=2.7 Pure MDI’s Fn=2.0
  • Emulsifiable MDI 50/50 blend of water and MDI RUBINATE® M Polymeric MDI RUBINATE 9259 Emulsifiable MDI
    • Emulsifiable Polymeric MDI Advantages
      • Does not easily separate after mixing
      • Faster reactivities achieved
      • Quicker strength build up achieved
      • Stronger overall physical properties
    • What is an Emulsifiable MDI?
      • An isocyanate which has been modified by adding hydrophilic solubolising groups to become easily emulsified in water
  • 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
  • Emulsifiable MDI for Emulsion Polymer Adhesives
    • RUBINATE 9236 Isocyanate
      • Standard product for use as a crosslinker for Latex emulsions
          • Improves adhesion
          • Chemical resistance
          • Physical properties
    • SUPRASEC 9600 Isocyanate
      • Similar in performance to RUBINATE 9236
          • Provides an extended open time
          • Strength build maximized
  • Formulating Approaches
      • Hydroxy functionalized emulsion latex
        • Number of hydroxy groups can control crosslinking
        • Latex copolymers can be varied to allow a wide range of stress-strain behaviors
        • pH of the latex will affect reactivity
      • Isocyanate
        • Amount added, affects degree of crosslinking
          • Generally between 1% and 20%
        • Type can affect reactivity and build of green strength
  • 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
  • Lap Shear Adhesion * Fastest adhesive strength build up *
  • Viscosity Profiles * Suprasec 9600 builds viscosity at a slower rate *
  • EPI Adhesive Applications
    • Adhesives for bonding wood to:
      • Phenolic papers
      • Plastics
      • Metals
      • Wood
      • Concrete
    • High performance wet-use adhesives for wood bonding
      • Edge to edge
      • Finger joints
      • Laminating
    Adhesive for Doors and Windows
  • Door and Window Adhesive
    • Benefits of an EPI
      • Improved adhesion at low and elevated temps
      • Good water resistance and durability
      • Faster development of adhesive strength
      • Improved physical properties
    • Test Requirements
      • ASTM D 5751
        • Adhesives used for Laminate Joints in Nonstructural Lumber Products
  • ASTM D-5751
    • Dry
      • Specimens tested “as is”
    • Vacuum/Pressure test
      • Specimens submerged under water and sealed in a vacuum at 25 inch of Hg for 30 minutes
      • Followed by pressurizing the tank to 75 PSI for 30 minutes
      • Samples tested wet
    • Boiling
      • Samples are boiled for 4 hrs and then placed in an oven at 160F for 20 hours
      • The 4 hour boil is repeated
      • Samples tested wet
  • Photos of ASTM-D5751 Glue line Wood Failure
  • ASTM D-5751
  • Conclusions
    • The addition of a MDI crosslinker to an emulsion polymer:
      • Increases green strength development
      • Increases overall physical properties
      • Is necessary for “wet use” applications
    • Emulsifiable MDI’s:
      • Provide better mixing
      • Flexibility in reactivity rate
      • Higher physical properties than traditional MDI
  • Conclusions (cont.)
    • Huntsman is a leader in Emulsifiable MDI technology
    • For EPI adhesive applications use:
      • Rubinate 9236
        • Fast strength build up
        • Fast viscosity build up
      • Suprasec 9600
        • Fast strength build up
        • Slower viscosity build
    New Product Longer open times achieved!
  • Thank You!