Patent ID: 6187875
Filing Date: 2001-02-13
Classification: C08G,C09D

Abstract:
A powder coating composition curable at a temperature of at least 120.degree. C., comprising:(i) an epoxy resin having an epoxy group content (ECG) of from 2000 mmol/kg to 1400 mmol/kg; and(ii) a linear carboxylic acid functional polyester resin produced by reaction of:(a) at least one aromatic and/or cycloaliphatic dicarboxylic acid compound A, comprising two aromatic and/or secondary aliphatic carboxyl groups in the 1,2-position, or an anhydride thereof;(b) at least one hydroxyl monocarboxylic acid B.sub.1, comprising two aliphatic hydroxyl groups, which groups each independently may be primary or secondary hydroxyl groups and wherein the carboxylic acid group is a tertiary carboxyl group, mixed with a cycloaliphatic diol B.sub.2 in an amount of at least 5 wt %, relative to the weight of B.sub.1 and B.sub.2 together;(c) an aliphatic dicarboxylic acid C, comprising an alkylene group having from 3 to 8 carbon atoms and having two terminal aliphatic carboxyl groups; and(d) an aromatic monocarboxylic acid D selected from the group of benzoic acid, orthotoluic acid, and paratoluic acid;wherein the molar ratio of the compounds A:B.sub.1 +B.sub.2 :C:D is X:Y+X+Z.sub.1 :Y:Z.sub.2, wherein X ranges from 1 to 8, Y ranges from 1 to 8, Z.sub.1 ranges from -3 to 3 and Z.sub.2 ranges from 1 to 2;wherein at least 90% of all the hydroxyl groups supplied into the reaction mixture, have been reacted; andwherein a total amount of the epoxy resin and the linear carboxylic acid functional polyester resin comprises from 55 to 80 wt % of the epoxy resin and from 45 to 20 wt % of the polyester resin.