Novel urethanediols and polyurethanes therefrom

Abstract

Reaction of a large excess of 1,4-butanediol with methylenebis (4-phenyl isocyanate) gives a mixture of urethanediols which is a suitable curing agent for isocyanate-terminated polyurethane prepolymers, especially prepolymers made from methylenebis (4-phenyl isocyanate) and polyols. It is desirable to have a urethanediol mixture in which at least about 88 weight percent consists of the reaction product of 2 moles of 1,4-butanediol with 1 mole of the diisocyanate, about 10 weight percent of the reaction product of 3 moles of 1,4-butanediol with 2 moles of the diisocyanate, and no more than about 2 weight percent of 1,4-butanediol. The novel cured polyurethanes have higher hardness and better overall physical properties than methylenebis-(4-phenyl isocyanate)-based polyurethanes cured with conventional commercial diols providing "hard" cured products.

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