Coating compositions for glass substrates

摘要

The present invention relates to aqueous polyurethane coating compositions wherein the binder contains a) a polyol component, which is soluble or dispersible in water and is the reaction product of a polyisocyanate component containing 50 to 100 wt. % of 4,4'-diisocyanatodicyclohexylmethane, a polyol component containing one or more polyether polyols and having an OH number of 25 to 350 mg KOH/g solids and an isocyanate-reactive component containing at least one group capable of salt formation and b) a polyisocyanate component, which is soluble or dispersible in water, has blocked isocyanate groups and is the reaction product of a polyisocyanate having an isocyanurate group content of 2 to 30 wt. %, a reversible, monofunctional blocking agent for isocyanate groups, a nonionic hydrophilic component and a stabilizing component which has 1 to 2 hydrazide groups and a molecular weight of 70 to 300, wherein the equivalent ratio of blocked isocyanate groups of component b) to hydroxyl groups of component a) is at least 0.8:1. The present invention also relates to the use of the binders for coating any glass surfaces, especially glass bottles.