Thermosetting powder compositions based on polyesters and acrylic coploymers

Abstract

A thermosetting powder composition which comprises (a) a specific a carboxyl-terminated polyester and (b) a glycidyl group-containing acrylic copolymer. The carboxyl-terminated polyester (a) has an acid number of 15 to 70 mg of KOH/g and must be prepared in two steps. In the first step, a hydroxyl-terminated polyester is prepared from at least one polycarboxylic acid other than 1,4-cyclohexanedicarboxylic acid, and at least one aliphatic or cycloaliphatic polyol and in the second step, the resulting hydroxyl-terminated polyester is esterified with 1,4-cyclohexanedicarboxylic acid exclusively. In addition, the composition of the polyester (a) is very specific: it contains at least 75 mole % of terephthalic acid, at least 10 mole % of 1,4-cyclohexanedicarboxylic acid and at most 14 mole % of at least one other aromatic and/or aliphatic and/or cycloatiphatic polycarboxylic acid, based on a total carboxylic acid content of 100 mole %. The thermosetting powder compositions obtained from polyester (a) and acrylic copolymer (b) are particularly useful to prepare powder paints and varnishes; they produce coatings with a high gloss, excellent mechanical properties, and at the same time, good weatherability.

Dependencies are inferred from the claim text.