| 摘要 |
PURPOSE: Provided is rigid polyurethane or urethane-modified polyisocyanurate foams, to processes for their preparation and to polyol blends for use in the processes. CONSTITUTION: Isocyanate-reactive composition comprises a polyester polyol, an amine catalyst and a carboxylic acid characterised in that carboxylic acid contains at least one OH, SH, NH2 or NHR functional group wherein R is an alkyl, cycloalkyl or aryl group. the carboxylic acid corresponds to the formula X - R' - (COOT)= wherein X is OH, SH, NH2 or NHR, R' is an at least divalent hydrocarbon moiety, n is an integer having a value of at least 1 and m is an integer having a value of at least 1.
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