Patent ID: 6991746

Claim:
A process for the production of a prepolymer of a polymeric allophanate modified diphenylmethane diisocyanate, said prepolymer having an NCO group content of about 10 to about 28%, and comprising: (I) adding: (4) at least one catalyst stopper to (B) a polymeric allophanate modified diphenylmethane diisocyanate having an NCO group content of 12 to 30% by weight, and comprising: (A) an allophanate modified diphenylmethane diisocyanate having an NCO group content of 20 to 32% and which comprises the reaction product of: (1) one or more OH-group containing compounds selected from the group consisting of (a) aliphatic alcohols, (b) aromatic alcohols, (c) aliphatic diols, and (d) mixtures thereof: and (2) diphenylmethane diisocyanate comprising: (a) from 0 to 60% by weight of 2,4′-diphenylmethane diisocyanate, (b) less than 6% by weight of 2,2′-diphenylmethane diisocyanate, and (c) the balance being 4,4′-diphenylmethane diisocyanate, with the %'s by weight of (2)(a), (2)(b) and (2)(c) totaling 100% by weight of (2), in the presence of (3) one or more allophanate catalysts; wherein (A) said allophanate-modified diphenylmethane diisocyanate is held at a temperature of from about 20 to 70° C. from about 1 hour to about 30 days to form (B) said polymeric allophanate modified diphenylmethane diisocyanate, (II) reacting the polymeric allophanate which contains catalyst stopper from (I), with (C) an OH-group containing compound selected from the group consisting of: (1) one or more polyether polyols containing from about 1.5 to about 6 hydroxyl groups and having a molecular weight of about 300 to about 6,000; (2) one or more low molecular weight diols having a molecular weight of about 76 to about 200; (3) one or more polyester polyols containing from about 1.5 to about 3 hydroxyl groups and having a molecular weight of about 300 to about 3,000; and (4) mixtures thereof.