Patent ID: 6262186
Filing Date: 2001-07-17
Classification: C08G,Y10T

Abstract:
A curable powder coating composition comprising a modified epoxy functional polyester produced by reacting an epihalohydrin in the presence of a base with at least one carboxyl functional polyester resin (II) produced by reacting:(a) at least one aromatic, aliphatic or cycloaliphatic dicarboxylic acid A comprising two aromatic or secondary aliphatic carboxyl groups, or the anhydride thereof;(b) at least one diol B having two aliphatic hydroxyl groups which are independently a primary or secondary hydroxyl group; optionally,(c) compound C1having one monofunctional primary or secondary hydroxyl and/or at least one compound C2 having one primary or secondary hydroxyl group and one tertiary aliphatic carboxyl group; optionally,(d) a dihydroxymonocarboxylic acid D having a tertiary aliphatic carboxyl group and two aliphatic hydroxyl groups, which each independently is primary or secondary hydroxyl; and, optionally,(e) a trihydroxyalkane (E1) or tetrahydroxyalkane (E2);in a molar ratio of A:B:C1:C2:D:E1:E2 of (X+Y+1):X:M:N:Y:Z:Q, wherein X is from 2 to 8, Y is from 0 to 8, M+N is from 0 to 2, Y is from 0 to 8, Z is from 0 and Q is from 0 to 2, at a temperature of from 100.degree. C. to 220.degree. C. until a predominant part of the non-tertiary carboxy groups initially present in the reaction mixture has been reacted, thereby producing an epoxy functional polyester (III) having an epoxy group content of from 500-3000 and a number average molecular weight M.sub.n, of from 500-10,000, and subsequently reacting said epoxy functional polyester (III) with an isocyanate (IV) in a molar ratio of III:IV such that all of the terminal hydroxyl groups have are reacted.