Method for producing polyisocyanates with biuret structure

摘要

Preparing polyisocyanate comprising a biuret structure, comprises continuously reacting an excess amount of an organic isocyanate (A) comprising exclusively aliphatically and/or cycloaliphatically bonded isocyanate groups with an organic amine (B) comprising exclusively aliphatically and/or cycloaliphatically bonded primary amino groups by (a) mixing a first amount of the organic isocyanate (A) with the organic amine (B) at above 170[deg] C to form a reaction mixture stream, and (b) metering a second amount of the organic isocyanate (A) at 20-250[deg] C into the reaction mixture stream of (a). Continuously preparing a polyisocyanate comprising a biuret structure, comprises continuously reacting an excess amount of an organic isocyanate (A) comprising exclusively aliphatically and/or cycloaliphatically bonded isocyanate groups with an organic amine (B) comprising exclusively aliphatically and/or cycloaliphatically bonded primary amino groups by (a) mixing a first amount of the organic isocyanate (A) with the organic amine (B) at above 170[deg] C to form a reaction mixture stream, and (b) metering a second amount of the organic isocyanate (A) at 20-250[deg] C into the reaction mixture stream of (a), where the ratio of the parts by weight of the organic isocyanate (A) fed per unit time into step (a) to the parts by weight of the organic isocyanate (A) fed per unit time into (b) is 1:9-9: 1, and the ratio of the total number of isocyanate groups fed per unit time into both steps (a) and (b) to the number of amino groups fed in per unit time into step (a) is at least 4:1. An independent claim is included for the polyisocyanate comprising the biuret structure obtained by the above process.