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Rim process for the production of elastic moldings

  • US 4,218,543 A
  • Filed: 01/15/1979
  • Issued: 08/19/1980
  • Est. Priority Date: 05/21/1976
  • Status: Expired due to Term
First Claim
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1. In a process for the production of polyurethane elastomer moldings having a compact surface skin from a reaction mixture by a reaction injection molding process, wherein said reaction mixture comprises the following components:

  • (a) 4,4'"'"'-diisocyanatodiphenylmethane,polyisocyanates based on 4,4'"'"'-diisocyanatodiphenylmethane or mixtures thereof;

    (b) hydroxyl group containing compounds having molecular weights of from 1800 to 12,000;

    (c) a chain extender; and

    (d) a catalyst for the reaction between hydroxyl groups and isocyanate groups;

    the improvement wherein said chain extender is miscible with component (b) in any proportion and is an active aromatic diamine having alkyl groups of from 1 to 3 carbon atoms in the ortho-positions to each amino group, and wherein said components are processed via the one-shot process whereby (a) is mixed simultaneously either with (b), (c), and (d) or with a non-reacted premixture of some or all of (b), (c), and (d) or with a non-reacted premixture of some or all of (b), (c) and (d), with the proviso that at least two of said alkyl substituents contain 2 or 3 carbon atoms.

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