POLYURETHANES AND POLYURETHANE-UREAS HAVING IMPROVED PROPERTIES

摘要

A microcellular polyurethane or polyurethane-urea foam elastomer is described which comprises the reaction product of a reactant (A) with a reactant (B) wherein: (A) is a prepolymer having a -NCO free group content comprised between 2%-25% (% w/w), which comprises the reaction product of (a1) one or more aliphatic, cycloaliphatic and/or aromatic diisocyanates excluding 3,3'-dimethyl- 4,4'-diphenyIene diisocyanate (TODI), or one or more polyisocyanates or mixture of diisocyanates and polyisocyanates; with (a2a) one or more polyester macrodiols, having a number average molecular weight comprised between 600-6000 and a number of -OH groups per molecule equal to about 2; and wherein (B) is a compound selected from the group consisting of (b1) a diol or polyol having a molecular weight or number average molecular weight lower than 500; (b2) a primary or secondary aliphatic, cycloaliphatic amine or aliphatic, cycloaliphatic aromatic disecondary diamine or a blocked amine having a molecular weight lower than 500; (b3) one or more polyester macrodiols having a number average molecular weight comprised between 500-6000 and a number of -OH group per molecule equal to about 2; (b4) a mixture formed of two or more compounds (bl), (b2) e (b3) as above defined, said (A)+(B) reaction product being obtained in the presence of water and/or physical or chemical blowing agent, and of a catalyst for the formation urethane and/or ureic groups.