Powdery polyurethane lacquers based on polyester resins and blocked isocyanates

摘要

A powdery polyurethane lacquer which comprises (a) a hydroxyl-group containing polyester resin with an OH number of 40-240 and (b) an epsilon -caprolactam-blocked polyisocyanate, selected from the group consisting of triisocyanatoisocyanurate of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate and mixtures of said triisocyanatoisocyanurate with monomeric or oligomeric 3-isocyanatomethyl-3,5,5-trimethyl-cyclohexylisocyanate; wherein the epsilon -caprolactam-blocked triisocyanatoisocyanurate has at least two blocked isocyanate groups and wherein the epsilon -caprolactam-polyisocyanate is present in an amount sufficient to cause hardening of said mixture of (a) and (b). The lacquer is especially useful for electrostatic coating of substrates.