A polyisocyanate composition, suitable for use in the production of elastomers by the RIM process, said composition being the product of reacting an alcohol and/or thiol having an average hydroxyl and/or thiol functionality of from about 1.5 to about 4 and an average hydroxyl and/or thiol equivalent weight of at least 500 with at least 2 equivalents, per hydroxyl and/or thiol equivalent, of an organic polyisocyanate under such conditions that at least about 20% of the initially formed urethane and/or thiourethane groups are converted to allophanate and/or thioallophanate groups.
This invention relates to a continuous process for the production of allophanate modified diphenylmethane diisocyanates having an NCO group content of 19 to 32% and an urethane content of less than 2 area % by GPC analysis. The process comprises (1) continuously reacting (a) diphenylmethane diisocyanate and (b) an alcohol, in the presence of (c) at least 25 ppm of an allophante catalyst, based on the combined weight of the diphenylmethane diisocyanate and the alcohol, in a reactor in an oxygen-free environment; (2) continuously treating the product exiting the reactor with a catalyst stopper at the reaction temperature; and (3) cooling the resultant product.
Allophanate-modified 1,3-phenylene diisocyanates or 1,1-biphenyl diisocyanates or 1,1'-oxy-bis-(isocyanato benzenes) which are storage stable liquid at 25.degree. C. are made by reacting the diisocyanate and a mono-alcohol to form an isocyanate containing urethane groups. The urethane groups in the diisocyanate are then converted to allophanate groups. The resultant product which has an isocyanate group content of from about 10 to about 40% may be further reacted with isocyanate-reactive compounds to produce an allophanate-modified diisocyanate prepolymer containing urethane or urea groups having an isocyanate group content of from about 5 to about 40.0%. The liquid, storage-stable, allophanate-modified diisocyanates produced by these processes are particularly useful in the production of elastomers and flexible foams.
Disclosed herein are processes for the production of allophanate-modified diphenylmethane diisocyanate prepolymers and the products produced by the processes which are both stable and liquid at 25.degree. C. by reacting (i) 4,4'-diphenyl-methane diisocyanate containing from 2 to 60% by weight 2,4'-MDI and less than 6% by weight of the 2,2'-MDI with (ii) an aromatic alcohol containing between 6 and 18 carbon atoms such as phenol, with the resulting product being converted to the allophanate having an isocyanate group content of from 12 to 32% by weight.
The present invention relates to a process for the production of a allophanate-modified MDI which is a storage stable liquid at 25.degree. 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%.
The present invention relates to a stable, liquid MDI prepolymer containing an allophanate-modified MDI, having an NCO content of 12 to 32.5% comprising a reaction product of an aliphatic alcohol and diphenylmethane diisocyanate comprising about 2 to 60% by weight 2,4'-diphenylmethane diisocyanate and less than 6% by weight of the 2,2'-diphenylmethane diisocyanate, and the rest being 4,4'-diphenylmethane diisocyanate.
