| abstract |
This invention provides a process for producing a polyurethane resin from a hydrogenated polydiene diol or polyol having a functional group equivalent weight of 750 to 10000, a reinforcing agent having a functional group equivalent weight of 30 to 200, and a polyisocyanate. In a preferred embodiment, the process comprises reacting at least one of a polydiene diol or a reinforcing diol or triol with the polyisocyanate at an NCO/functional group molar ratio of 0.4 to 0.7 or a functional group/NCO molar ratio of 0.25 to 0.55 to form a stable reaction product, adding to this reaction product an additional sufficient amount of the polyisocyanate and, as needed, one or both of the polydiene diol or the reinforcing agent to bring the NCO/OH functional group ratio up to from 0.9 to 1.1 and to achieve a polydiene agent content of 35 to 80 wt.% (on solids basis) and a reinforcing agent content of 2 to 17 wt.% (on solids basis), and reacting this final mixture to form a cross-linked polyurethane product. This process can also be carried out at an OH/NCO ratio of 0.9 to 1.1 using a blocked polyisocyanate wherein the intermediate reaction product is a stable polyurethane resin. |