Liquid methylene diphenyl diisocyanate

摘要

The present invention relates to a process for the production of a allophanate-modified MDI which is a storage stable liquid at 25 DEG C. comprising (A) reacting (i) one equivalent of a diisocyanate and (ii) one equivalent of an aliphatic alcohol containing from 1 to about 36 carbon atoms or aromatic alcohol containing from 6 to 18 carbon atoms to form a diurethane of the diisocyanate, (B) reacting the product of (A) with 4,4'-diphenylmethane diisocyanate containing from 2 to 60% by weight 2,4'-MDI and less than 6% by weight of the 2,2'-MDI, in an amount sufficient to provide an allophanate having an isocyanate group content of about 12.0 to 30.0%.