Polyurethane elastomer derived from graft of ethylenically unsaturated monomer on polyalkylene ether glycol

Claim 1

A thermally stable polyurethane elastomer which is a reaction product of: (a) a graft polyol prepared by the in situ polymerization of ethylenically unsaturated monomeric material in a poly(oxypropylene)-poly(oxyethylene)glycol of molecular weight from about 1750 to 4000 and containing from 30% to 50% oxyethylene groups by weight, the amount of polymerized monomer in the graft polyol being from 5 to 50% by weight; (b) methylenebis(4-phenylisocyanate); and (c) 1,4-butanediol; the NCO/OH equivalents ratio being from 0.95 to 1.2 and the molar ratio of (c) to (a) being from 4/1 to 12/1; said elastomer having a hardness of about 40 to 55 Shore D, an elongation of greater than 300%, an ultimate tensile strength of at least 2500 psi and a Die C tear strength of at least 500 pli, said elastomer displaying improved thermal stability as evidenced by its ability to retain at least twice as much of its original tensile strength, after exposure to a temperature of 415° F. for twenty minutes, as an otherwise similar elastomer in which (a) contains 10% or less of oxyethylene groups.