Polyurethanes are normally prepared by reacting a hydroxyl compound with a di or polyisocyanate. Isocyanates are much more versatile in their reaction permitting many other links to form. In polyurethane applications also urea-linkagesisocyanurate, amide and carbodiimide linkages can be formed. The high Tg of the urea linkage and the high heat resistance of the isocyanurate linkage make these linkage of considerable importance in polyurethanes. Every end use and every application requires a different polyol and isocyanate.  This is an overview of the most common applications of polyurethanes and the composition of these systems. Because of the many different applications and end-uses there are many other modifications in polyols and isocyanates and other additives in use.

    Index    
System Coatings Elastomer Adhesives Flame retardant Foam rigid Foam flexible Prepolymer
Polyol Polyester Polyether      Acrylic Polyether Polyester Polyester polyether aromatic High functional polyether Low functionality high mw foams Polyether low functionality
MW 500-5000 2000-5000 500-2000 500-1500 1000-6000 1000-3000
Functionality 2.5-3 2-3 2-3 3-5 2-3 2-3
Isocyanate IPDI, MDI, TDI MDI, TDI, IPDI TDI, MDI TDI, MDI MDI, TDI MDI, TDI, IPDI
Crosslinker HDI-trimer IPDI-trimer           
Catalyst DBTDL t-Amine Trimerization K-salt t-Amine t-Amine, Sn octoate No catalyst or low level
Blowing Agent Not used Not used HCFC, CO2, Pentane HCFC, CO2, Pentane HCFC, CO2, Pentane, Acetone Not used
Surfactant Flow and leveling Not used Silicone Silicone Silicone Not used
Additives Pigments UV-absorber  Antioxidant Phosphate, Chorine, Nitrogen  Antioxidant Antioxidant Antioxidant
Prepolymers can be used in many PU applications

Last edited on:

November 19, 2006

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