Cycloaliphatic diisocyanate based rim elastomers

A process for the production of a polyurethane/urea molding from a reaction injection molding process, wherein said reaction mixture comprises:

• a) an isocyanate component consisting essially of cycloaliphatic diisocyanate,
• and
• b) an isocyanate-reactive component comprising:
• b1) from 40 to 90% by weight of one or more isocyanate-reactive compounds having a molecular weight of from about 500 to 8000 and containing an average number of functional groups of from 1.5 to 4.0, wherein said functional groups being selected from the group consisting of hydroxyl groups, primary amine groups and secondary amine groups, with the OH:NH equivalent ratio being from 0:1 to 1:1,
• and
• b2) from 10 to 60% by weight of one or more organic chain extenders having molecular weights of from about 60 to 500, and being selected from the group consisting of diols, triols, primary aliphatic amines, secondary aliphatic amines, amino alcohols and mixtures thereof, wherein said chain extender or mixture thereof has an OH:NH equivalent ratio of from 1:2 to 10:1,
• wherein the percent by weight of components b1) and b2) totalling 100% of component b),
• and
• c) from 0. 1 to 10% by weight, based upon the weight of component b), of one or more catalyst for catalyzing the reaction between the isocyanate groups and the isocyanate-reactive groups,
• wherein the reaction mixture is processed via a one-shot process at an isocyanate index of from 80 to 130.