Epoxide resin-modified polyesters derived from carboxyl polyol

A water dilutable coating composition for the production of heat-curable coating, in which the binder is comprised of an epoxide resin-modified, water-dilutable polyester produced by the reaction of:

• A) a polyester (A) produced by polymerization:
• a.sub.1) a polycarboxylic acid containing at least three carboxyl groups or a reactive derivative thereof;
• a.sub.2) a polyol containing at least one carboxyl group other than components a.sub.1) a.sub.3) and a.sub.4);
• a.sub.3) a polycarboxylic acid containing two carboxyl groups or a reactive derivative thereof, and
• a.sub.4) a polyol,
• such that at least 10 mol % of the sum of components (a.sub.1), (a.sub.2), (a.sub.3), (a.sub.4), contains at least one (cyclo)aliphatic structural element having at least six carbon atoms,
• said polyester (A) further having a number average molecular weight of less than 2,000, an acid number of 35 to 240 and an OH number from 56 to 320, and said (a.sub.1) and (a.sub.3) components in the polyester being co-condensed via at least two carboxyl groups, and
• (B) 0.3 to 1.5 equivalents per polyester molecule of an epoxide resin (B) based on bisphenol and having an epoxide equivalent weight of 170 to 1,000 or a derivative thereof having at least one epoxide group per molecule, said reaction being conducted under conditions in which essentially only carboxyl groups react with epoxide groups,
• said epoxide resin-modified polyester being water-dilutable after at least part of the free carboxyl groups are neutralized.