Polyurethane compositions made from hydroxy-terminated polydiene polymers

A silane capped polyurethane composition made by reacting at least a stoichiometric amount of a isocyanatosilane with a polyurethane resin composition comprising 40 to 90%w (on solids basis) of a polydiene diol or polyol having a hydroxyl equivalent weight of 750 to 10000, 2 to 25%w of a reinforcing agent having a functional group equivalent weight of 30 to 200, and reacted with a polyisocyanate at an NCO/functional group molar ratio of 0.4 to 0.7, wherein the polyisocyanate has more than two isocyanate groups when reacted with the polydiene diol, or two or more isocyanate groups when reacted with the polydiene polyol.

A roofing membrane comprising an EPDM composition coated with a polyurethane resin composition made by a process for producing a polyurethane resin from a polydiene diol (or polyol) having a hydroxyl equivalent weight of 750 to 10000, a reinforcing agent having a functional group equivalent weight of 30 to 200, and a polyisocyanate curing agent which comprises:

• (a) reacting at least one of the polydiene diol (or polyol) or the reinforcing, agent with the polyisocyanate at an functional group/NCO ratio of from 0.25 to 0.55 to form a stable isocyanate terminated reaction product, wherein the polyisocyanate has more than two isocyanate groups
• (b) adding to the product of (a) an additional sufficient amount of one or both of the polydiene diol (or polyol) or the reinforcing agent and, as needed, the polyisocyanate to bring the functional group/NCO ratio up to 0.9 to 1.1 and to achieve a polydiene diol or polyol content of 35 to 80%w (on solids basis) and a reinforcing agent content of 2 to 17% (on solids basis), and
• (c) reacting the mixture of (b) to form a crosslinked polyurethane product.