Process for the production of modified polyisocyanates, the compounds obtainable by this process and their use in polyurethane lacquers

摘要

The present invention relates to a process for the production of modified organic polyisocyanates containing urethane, carboxylic acid anhydride and biuret groups by reacting excess quantities of organic diisocyanates with a modifying agent containing (a) hydroxy carboxylic acids corresponding to the following general formula <IMAGE> wherein R1, R2 and R3 represent alkyl groups and at least one of which contains a hydroxyl group and, optionally, (b) water wherein the molar ratio of (a) to (b) is about 0.02:1 to 1:0 and the ratio of mols of starting diisocyanate to mols of modifying agent (a) and (b) is about 3:1 to 24:1. The present invention also relates to the modified polyisocyanates obtained by this process and to the use of these polyisocyantes, optionally blocked with blocking agents for isocyante groups, as the polyisocyanate component in polyisocyanate addition reactions.