AQUEOUS POLYISOCYANATE CROSSLINKING AGENTS MODIFIED WITH HYDROXYCARBOXYLIC ACIDS AND PYRAZOLE-BASED BLOCKING AGENTS

摘要

The present invention relates to aqueous or water dilutable blocked polyisocyanates containing a) a polyisocyanate component and, based on the equivalents of isocyanate groups, b) 60 to 85 equivalent % of a pyrazole blocking agent, c) 15 to 40 equivalent % of a monohydroxycarboxylic acid to impart hydrophilic properties and d) 0 to 15 equivalent % of a difunctional chain extender containing OH and/or NH2 groups, wherein the amounts of a) to d) are selected so that the equivalent ratio of NCO groups of component a) to isocyanate-reactive groups of components b), c) and d) is 1:0.8 to 1:1.2. The present invention also relates to a process for preparing these polyisocyanate crosslinking agents and to their use in combination with polyhydroxyl compounds which are soluble and/or dispersible in water as binders for aqueous stoving lacquers.