Electrically insulative powder coatings and compositions and methods for making them

摘要

The present invention provides powder compositions comprising from 20 to 90 phr of one or more than one silicone resin having a glass transition temperature (Tg) of at least 40 DEG C, from 10 to 80 phr of one or more than one resin chosen from glycidyl functional acrylic resin, mixtures of aromatic epoxy resin or novolac resin with carboxyl functional acrylic resin carboxyl functional polyester resin or glycidyl functional acrylic resin, and one or more than one filler, such as wollastonite, barium sulfate, mica, talc, alumina, layered silicates like montmorillonite, and mixtures thereof. The one or more than one silicone resin may or may not be flaked and may or may not contain silanol groups. The compositions of the present invention provide single layer or multilayer powder coatings that are free of voids larger than 30 mu m in diameter, and which may meet the UL Class H (180 DEG C) certification for electrical insulation applications. Further, the compositions may be used to provide powder coatings, films, moldings, electrical potting compounds and electrical encapsulation compounds.