DK0686176T3 - Powder coatings based on carboxyl group-containing polyesters and suitable crosslinking agents, as well as coating process - Google Patents

Abstract

The invention concerns coating powders based on carboxyl-group-containing polyesters and suitable cross-linking agents. The coating powders contain as a film-forming material a mixture of A) 70 to 96 % by wt. of a mixture of one or more polyesters (A1) having an acid number in the range 10 to 150 mg KOH/g, preferably in the range 30 to 100 mg KOH/g, and a cross-linking agent (A2) consisting of compounds with an average of more than one epoxy group per molecule and/or of beta -hydroxyalkylamides, the ratio of the number of acid groups in the polyester or polyesters to the number of epoxy groups and/or beta -hydroxyalkylamide groups in the cross-linking agent being 0.6:1 to 1.6:1, preferably 0.9:1 to 1.1:1, and (B) 30 to 4 % by wt. of one or more acrylated polyurethane resins containing 2 to 10 % by wt., preferably 4 to 6 % by wt., of ethylenically unsaturated double bonds (calculated as C = C, molecular weight = 24), the sum of components A and B being 100 % by wt. The invention concerns also a process for manufacturing coated sheet metal, using said coating powders.