THERMOSETTING POWDER BASED ON AN UNSATURATED POLYESTER RESIN AND PROCESS FOR ITS PREPARATION

摘要

A thermosetting powder based on a homogeneous mixture containing 50 to 92% by weight of an unsaturated polyester resin having a softening temperature of at least 50 DEG C. 50 to 30% bij weight of a prepolymer of a diallylester of an aromatic dicarboxylic acid, 3 to 20% by weight of a high boiling, crosslinking monomer and 0.1 to 5% by weight of hardening catalyst, all weight percentages relating to the overall quantity of the polymerizable components. A process for the preparation of the thermosetting powder by melting and mixing the polyester resin and at least the greater part of the other polymerizable components except the catalyst subsequently the catalyst and the remaining portion of the polymerizable components is rapidly admixed to the melt at a temperature that is at least 20 DEG lower than the temperature corresponding to a half life time of 1 minute in which operation the time during which the catalyst is exposed to the higher temperature is max. 30 sec. after which the mixture is rapidly cooled and ground.