Polyester coil coating, process of coating a coil, and coated coil

Abstract

A coil coating composition producing a coil coating with excellent properties at a lower peak metal temperature includes (a) a first, branched polyester with an hydroxyl number of at least about 80 mg KOH/g, (b) a second, essentially linear polyester with an hydroxyl number of at least about 44 mg KOH/g, and (c) a crosslinking agent. The branched polyester is prepared by condensation of a polyol component consisting essentially of a flexibilizing diol, a branched diol, and, optionally, a polyol having at least three hydroxyl groups and a polyacid component consisting essentially of one or more aromatic or cycloaliphatic dicarboxylic acids and polymerizable anhydrides and esters thereof and, optionally, a polyacid having at least three carboxylic acid groups or poymerizable anhydrides or esters thereof, wherein at least one of the polyol having at least three hydroxyl groups and the polyacid having at least three carboxyl groups or an anhydride or methyl ester thereof is included. The essentially linear polyester is prepared by condensation of a polyol component consisting essentially of a flexibilizing diol and a branched diol and a polyacid component consisting essentially of one or more aromatic or cycloaliphatic dicarboxylic acids and polymerizable anhydrides and esters thereof. The branched diols of the first and second polyesters are independently selected from the group consisting of 2-methyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, propylene glycol, neopentyl glycol, and combinations thereof.

Dependencies are inferred from the claim text.