Typical Formulation Ingredients
Phase
Ingredient
Parts by weight
A
Polybutadiene resin (Poly bd R45HTLO, Cray Valley)
A
Chain extender (2-ethyl-1,3-hexanediol)
A
Filler calcium carbonate (Super-Pflex 200, Specialty Minerals)
A
Filler calcium carbonate (Ultra-Pflex, Minerals Technology Inc.)
A
Carbon black (Sterling R, Cabot Corporation)
A
Plasticizer (Santicizer 278, Valtris)
A
Fumed silica (Cab-O-Sil TS-720, Cabot Corporation)
A
Antioxidant (Vanox NBC, R.T. Vanderbilt)
A
Silane (Silquest A-187, Momentive)
B
Polyfunctional MDI liquid (Isonate 143L, Dow Chemical Co.) (NCO/OH = 0.95)
B
Polyfunctional MDI liquid (Isonate 143L, Dow Chemical Co.) (NCO/OH = 0.926)
Typical Properties
Good adhesion to metals and glass
Low temperature flexibility
Property retention with age
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.
Source: Yoo, T. and Chao, H., “Hydroxyl-Terminated Polybutadiene Liquid Resins for Adhesives Applications”, Adhesivesmag.com, January 6, 2017.