Typical Formulation Ingredients
Ingredient
Parts by weight
Polybutadiene polyol (Liquiflex H, Petroflex)
Plasticizer (Santicizer 261, Ferro)
Tackifier (Abitol, Eastman Chemical)
Catalyst (Thorcat 535, Thor)
Thickener (Lorol C-18, BASF)
Precipitated calcium carbonate (Calofort S, Mineral Technologies)
Calcium carbonate drying agent (Eskal 430, Glasstec)
Molecular sieve (Purmol, Zettachem)
Isocyanate (M143L, Dow Chemical)
Plasticizer (Santicizer 261, Ferro)
p-toluenesulfonyl isocyanate
Silane (A-187, Momentive)
Fumed silica (Aerosil R972, Evonik)
(Source: Amstock, J.S., Handbook of Adhesives and Sealants In Construction, McGraw-Hill, New York, 2000, p. 12.12)
Typical Properties
Mixing ratio (Part A:Part B) by weight
Water vapor transmission, g/m2/24hr
Lap shear glass-to-glass, psi
Resulting Properties
The formulation above is for a general purpose two component polyurethane adhesive based on polybutadiene polyol. Using polybutadiene polyol will provide much better hydrolytic stability than other conventional polyols (e.g., polyester or polyether).
Often additives are not required to provide flexibility or toughness as in the case of epoxy formulations. Polyurethanes have the capability of providing these properties through manipulation of the resulting molecule by proper choice of isocyanate and polyol. However, additives are used mainly to stabilize the adhesive relative to moisture, oxidation, UV, etc.