Lightfast clear PUR lacquers

摘要

Binder mixtures containing (A) a polyisocyanate mixture with an NCO functionality of at least 2.8 based on hexamethylenedi-isocyanate and cycloaliphatic di-isocyanate and (B) a polyol component with an OH functionality of less than 3 comprising (B1) an ether group-free polyester based on aromatic carboxylic acid and (B2) other ether group-free polyols. Binder mixtures (I) containing (A) a polyisocyanate component with a viscosity at 23[deg]C (V23) of 2000-150000 mPa.s, an NCO content of 14-23 wt% and a calculated average NCO functionality of at least 2.8, comprising (A1) 40-80 wt% polyisocyanate(s) based on hexamethylenedi-isocyanate (HDI), with an NCO content of 16-24 wt% and (A2) 20-80 wt% polyisocyanate(s) based on cycloaliphatic di-isocyanates, with an NCO content of 10-22 wt%, (B) a polyol component with an average OH functionality (OHF) of less than 3, a viscosity of 5000-150000 mPa.s at 23[deg]C and an OH number of 400-700 mg KOH/g, comprising (B1) 50-80 wt% ether group-free polyester-polyol(s) based on aromatic carboxylic acids, with an OHF of less than 3, an OH number of 200-500 mg KOH/g and a number-average mol. wt. (M n) of 200-900 and (B2) 20-50 wt% ether group-free hydroxy-functional compounds other than (B1), with an OHF of at least 1.8 and an M n of 32-1000, (C) optionally catalysts and (D) optionally additives etc. Independent claims are also included for (1) a method for the production of (I) by mixing the components at elevated temperature (2) coatings obtained from (I) (3) substrates coated with these coatings .