Siloxane-modified polyisocyanates, process for their preparation and their use for the finishing of patent leather

摘要

Polyisocyanates with siloxane groups and containing 15-22 wt.% isocyanate groups have: (i) 50-80% of the isocyanate groups bonded to aromatic groups; (ii) 20-50% of the isocyanate groups bonded to aliphatic groups; and (iii) a content of 1.5-6 wt.% (w.r.t. the isocyanate) predominantly straight chain polydimethylsiloxane groups bonded via urethane groups. Also claimed is the preparation of the polyisocyanates.