The modified alkyd resins comprise a mixt. of compsns. (A) and (B) where (A) comprises 60-80 wt.% of dried fatty acids and/or oils having an iodine number of at least 110 pref. 130-170, up to 10 wt.% of aromatic- and/or aliphatic monocarboxylic acid, 10-25 wt.% of a polyol contg. 3-6 OH gps. per mol. and 10-20 wt.% of polycarboxylic acids or their anhydrides contg. 2-4 carboxyl gps. per mol. (A) has an acid number of no more than 30, pref. 20 mg KOH/g and a limiting viscosity value (measured in CCl4 at 20 deg.C of 4.5 to 6.0 ml/g. (B) comprises 15-40 wt.% of a conversion prod. obtd. either from 2 mol. of an OH-functional alkylether contg. at least 2 allylether gps. per mol. and 1 mol. of a tricarboxylic acid anhydride or from 1 mol. of an OH-functional alkyl ether contg. 3 or more alkylether gps. per mol. and 1 mol. of a dicarboxylic acid anhydride, and has an acid number corresp. to 1 free carboxylic acid gp. per mol. (A) and (B) are esterified at 170-230 deg.C to give an acid number of no more than 20 mg KOH/g and a limiting viscosity number (measured in chloroform at 20 deg.C) of 5.5 pref. 6.0-9.0 ml/g. The sum of the percentage values for the compsn. of the combinations of (A) and (B) and of (A1) to (A4) taken as solids amounts to 100.
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