Blocked polyisocyanates for the production of powder coatings with flat finishes

摘要

The present invention is directed to coating compositions comprising a) polyisocyanates having a content of isocyanate groups blocked by blocking agents of about 10 to 35% by weight and containing about 0.5 to 10.0% by weight of structural units corresponding to the formula -CO-NH-NH-CO- and b) polyhydroxy polyacrylates in an amount sufficient to provide an equivalent ratio of blocked isocyanate groups to hydroxyl groups of about 0.5:1.0 to 2.0:1.0. The present invention is also directed to the coatings prepared from these coating compositions. Finally, the present invention is directed to blocked polyisocyanates which have a content of isocyanate groups blocked by blocking agents of about 10 to 35% by weight and about 0.5 to 10.0% by weight (calculated as -CO-NH-NH-CO-, MW 86) of structural units corresponding to the formula -CO-NH-NH-CO-Q- wherein Q represents NH-NH-CO- or the group R-(CO-NH-NH-CO-)n R is an n+1 valent hydrocarbon radical and n has a value from 1 to 3.