THERMOSETTING COMPOSITIONS IN POWDER FORM FOR THE PREPARATION OF MATT COATINGS

摘要

Thermosetting compositions in powder form comprising as binder a mixture of a linear polyester containing carboxyl groups which has an acid value of between 20 and 50 mg of KOH/g and an acrylic copolymer containing glycidyl groups, obtained from 5 to 30 % by weight of glycidyl acrylate or methacrylate and 70% to 95 % by weight of methyl methacrylate, it being possible for up to 25 % by weight of the methyl methacrylate to be replaced with another vinyl monomer. The acrylic copolymer has a number-average molecular weight (@n) of between approximately 4,000 and approximately 10,000. These compositions are particularly useful for the preparation of paints and varnishes in powder form, which can be applied with an electrostatic spraying gun and cured at a temperature of 160 to 210 DEG C to yield matt coatings of excellent quality.