Crosslinkable thermoplastic polyurethane

摘要

The TPU of this invention contains unsaturation in its polymeric backbone. The unsaturation can be present in the soft segment or in the hard segment or in both the soft and hard segments of the TPU. The TPU can be molded like a thermoplastic, and can be subsequently crosslinked by exposure to electron beam irradiation into thermoset articles having excellent chemical resistance, dimensional stability, set properties, heat resistance, oxidative resistance, and creep resistance. In one embodiment, the TPUs of this invention are the reaction product (1) a hydroxyl terminated intermediate, (2) a polyisocyanate, (3) a saturated glycol chain extender, and (4) a glycol chain extender containing carbon-carbon double bonds, such as the allyl moieties present in trimethylolpropane monoallyl ether. In another embodiment of this invention, the thermoplastic polyurethane which is crosslinkable by e-beam irradiation is comprised of the reaction product of (1) a saturated hydroxyl terminated intermediate, (2) an unsaturated hydroxyl terminated intermediate, wherein the unsaturated hydroxyl terminated intermediate contains carbon-carbon double bonds, (3) a polyisocyanate, and (4) a saturated glycol chain extender.

主权项

1. A crosslinkable thermoplastic polyurethane (TPU) for use in forming a desired shape by melt processing, said TPU comprising of the reaction product of (1) an unsaturated hydroxyl terminated intermediate, (2) an optional saturated hydroxyl terminated intermediate selected from a hydroxyl terminated polyether intermediate, a hydroxyl terminated polyester intermediate, a hydroxyl terminated polycarbonate intermediate, a hydroxyl terminated polycaprolactone intermediate, and mixtures thereof, (3) a polyisocyanate, and (4) a saturated glycol chain extender, wherein after being formed into a desired shape said TPU is capable of being crosslinked by exposure to e-beam radiation, gamma rays, ultra violet, and free radical generators, wherein the unsaturated hydroxyl terminated intermediate is of the structural formula:wherein A independently represents —R1OH and a moiety selected from the structure represented as follows:and R1, R2, R3 and R4 can be the same or different and represent divalent linear and branched alkylene moieties that contain from 1 to about 10 carbon atoms, R1 can also represent a divalent ether group represented by —R5—O—R5—, wherein R5 independently is selected from a divalent alkylene moiety containing 1 to 5 carbon atoms, the ratio of n:m ranges from about 0 to about 35, and y is an integer ranging from about 1 to about 20.