Patent ID: 8669323

Claim:
A process for preparing a nanoparticle-modified polyisocyanate having free NCO groups, which comprises A) reacting 1) nanoparticles having an average particle size, as determined by dynamic light scattering, of smaller than 200 nm with 2) an alkoxysilyl- and an NCO-containing adduct of the formula (I) OCN—R 1 —NHCO-QR 2 Z—SiX a Y 3-a (I) wherein, R 1 represents a substituent selected from the group consisting of C 1 -C 14 linear groups, C 3 -C 14 cyclic aliphatic groups, C 6 -C 14 araliphatic groups, and C 6 -C 14 aromatic groups; Q represents a substituent selected from the group consisting of oxygen, sulphur, and nitrogen; R 2 when Q is nitrogen, represents a substituent selected from the group consisting of hydrogen, C 1 -C 12 alkyl groups, C 6 -C 20 aryl groups, C 6 - C 20 aralkyl groups, and aspartic ester radicals; X represents a hydrolysable group; Y independently of one another, represent an alkyl group; Z represents a C 1 -C 12 alkylene group; and a represents an integer from 1 to 3; to form products of the reaction; and B) blending the products of the reaction with a polyisocyanate having free NCO groups, wherein the nanoparticle-modified polyisocyanate has an NCO content after 90 days of more than 80% of the initial NCO content measured in accordance with DIN EN ISO 11909.