Continuous process for the production of MDI allophanates
AssigneeBayer Aktiengesellschaft
InventorsWilliam E. Slack, Hersel T. Kemp, II, William E. Miller
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Abstract
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.
Claims24
A continuous process for the production of an allophanate modified polyisocyanate having an NCO group content of 19 to 32%, and having an urethane content of less than 2 area % by GPC analysis, comprising
- (1) continuously reacting
- (a) diphenylmethane diisocyanate comprising:
- (i) from about 0 to about 60% by weight of 2,4′-diphenylmethane diisocyanate,
- (ii) less than 6% by weight of 2,2′-diphenylmethane diisocyanate, and
- (iii) the balance being 4,4′-diphenylmethane diisocyanate,
- with the sum of the %'s by weight of (1)(a)(i), (1)(a)(ii) and (1)(a)(iii) totaling 100% by weight of (1)(a) the diphenylmethane diisocyanate;
- and
- (b) an alcohol;
- in the presence of
- (c) at least 25 ppm of an allophanate catalyst, based on the combined weight of the diphenylmethane diisocyanate and the alcohol;
- in at least one reactor at a temperature of from 80 to 110° C. for 0.5 to 4 hours, 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.
Dependencies are inferred from the claim text.