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

Abstract From the Canadian patent

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, wherein Rl 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 …