Patent ID: 6887399

Claim:
A process for the production of a polymeric allophanate modified diphenylmethane diisocyanate having an NCO group content of 12 to 30% by weight, comprising: (I) reacting: (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 2,4â€²-diphenylmethane diisocyanate, (b) less than 6% by weight of 2,2â€²-diphenylmethafle diisocyanate, and (c) the balance being 4,4â€²-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, at temperatures of about 80 to about 110Â° C. to form (A) an allophanate-modified diphenylmethane diisocyanate; and (II) cooling (A) said allophanate-modified diphenylmethane diisocyanate to a temperature of about 20 to about 70Â° C. for about 1 hour to about 30 days, thereby forming (B) a polymeric allophanate modified diphenylmethafle diisocyanate.