COATING POWDER

摘要

Powered coating compositions composed of a bonding agent of unsaturated polyester resin and hardening catalyst and bonding agent. The composition, prior to the addition of any catalyst, is a mixture of (I) about 85 to 100 weight percent of a mixture of polyester resins, which itself comprises about 70 to about 98 weight percent of a first polyester resin composed of at least one unsaturated polyester resin, the first resin: (i) having a melting point of at least 70 DEG C as measured with the ring-and-ball method, (ii) occurring as a free-flowing powder at temperatures of up to 25 DEG C, (iii) having a degree of unsaturation of at least 15 calculated as weight percent maleic anhydride to the total polyester, and (iv) yielding a product having an elongation at break of at most 10% upon curing with styrene; (b) about 2 to about 30 weigth percent of a second polyester resin composed primarily of at least one unsaturated polyester resin, the second resin yielding a product having an elongation at break of at least 50% upon curing with styrene and the amount and the melting point of the second resing being such that a mixture of the first and the second resin has a melting point by the ring-and-ball method of at least 40 DEG C; and (II) about 0 to about 15 weight percent relative to the first and second resins of one or more copolymerizable monomers and/or prepolymers having a boiling point of at least 200 DEG C. Such compositions are very suitable for preparing a top coat using the in-mold coating technique.