Polyisocyanate based upon 4,4'-and 2,4'-diphenyl-methane dllsocyanates and use thereof in a rim process

摘要

A novel polyisocyanate which is liquid and room temperature stable and has an isocyanate group content of from 10 to 30% by weight is prepared by reacting: a) an isocyanate mixture of 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and an amount of an isocyanate based upon diphenylmethane diisocyanate having an isocyanate functionality of more than 2, such that the total isocyanate mixture a) has an average isocyanate functionality of from 2.02 to 2.50, and b) one or more polyols selected from the group consisting of 1) diols having molecular weights of from 1000 to 5000, 2) triols having molecular weights of from 1000 to 6000, and 3) mixtures thereof. When used in a RIM process, parts are produced which have excellent low temperature impact properties.