Process for producing solid or microcellular polyurethane elastomers having improved green strength

Claim 1

A process for producing a solid or microcellular polyether polyurethane elastomer having improved green strength which comprises forming and curing a reaction mixture containing: (a) a polyether polyol, (b) a diol extender selected from the group consisting of short-chain alkane diols, short-chain cycloaliphatic diols, and short-chain oxyalkylene glycols, (c) an organic polyisocyanate in an amount that provides from 0.8 to 1.3 isocyanato groups per active-hydrogen group in the reaction mixture, wherein said organic polyisocyanate comprises a major amount of 4,4'-diphenylmethane diisocyanate and a minor amount of ##STR10## (d) from about 0.200 to about 0.400 parts by weight per 100 parts by weight of the active hydrogen-containing components in the reaction mixture of a dialkyltin dimercaptide carboxylic acid ester catalyst of the formula: ##STR11## wherein R is an alkyl group selected from the group consisting of methyl, butyl and octyl, x is an integer of from 1 to 4 and y is an integer of from 1 to 10, said catalyst being present in from about 1.5 to about 8 times a catalytic amount, said reaction mixture containing from 95 to 25 parts by weight of (a) and from 5 to 75 parts by weight of (b) per 100 parts by weight of (a) and (b), with the proviso that when a microcellular polyether polyurethane is being produced, the reaction mixture also contains: (e) a blowing agent in an amount sufficient to produce a microcellular structure in the elastomer.