Patent ID: 6063824
Filing Date: 2000-05-16
Classification: C08G

Abstract:
A microcellular polyurethane elastomer containing urea groups, comprising the reaction product ofa) an isocyanate component consisting essentially of diphenylmethane 4,4'-diisocyanate withb) at least one oligomeric polyhydroxyl compound having a number average molar mass of from 1000 to 5000 g/mol and a functionality of from 1.7 to 3, and, optionally,c) low molecular weight chain extenders and/or crosslinkers in the presence ofd) a blowing agentand, optionally,e) a catalyst, andf) auxiliaries and/or additives,said elastomer having a urea content of from 14 to 18% by weight, defined as the amount in percent of urea of the empirical formula C.sub.14 H.sub.12 ON.sub.2 formed from diphenylmethane diisocyanate, based on the total amount of the elastomer after urea formation, and having, after heating at from 100 to 120.degree. C. for from 8 to 24 hours, a melting range of from 130.degree. C. as the minimum lower limit to 230.degree. C. as the minimum upper limit, measured by differential scanning calorimetry (DSC) at a heating rate of 20.degree. C./min, which melting range can be set by adding Bronstedt or Lewis acid reagents in an amount of from 0.01 to 5% by weight, based on the weight of the components a), b), e) and, if used, c).