LOW SURFACE ENERGY POLYISOCYANATES AND THEIR USE IN ONE- OR TWO-COMPONENT COATING COMPOSITIONS

摘要

The present invention is directed to a polyisocyanate mixture i) having an NCO content of 5 to 35% by weight and a monomeric diisocyanate content of less than 3% by weight, and prepared from a polyisocyanate adduct, ii) containing allophanate groups in an amount such that there are more equivalents of allophanate groups than urethane groups and such that the polyisocyanate mixture remains stable and homogeneous in storage for 1 month at 25.degree.C and iii) containing siloxane groups (calculated as SiO, MW 44) in an amount of 0.002 to 50% by weight, wherein the preceding percentages are based on the solids content of the polyisocyanate mixture and wherein the siloxane groups are incorporated by reacting an isocyanate group with a compound containing one or more hydroxyl groups directly attached to a carbon atom and one or more siloxane groups. The present invention is also directed to a process for the production of this polyisocyanate mixture and to its use, optionally in blocked form, as an isocyanate component in one- or two-component coating compositions.