Process for the preparation of ester resins

Glycidyl polyethers are esterified by fatty acids in the presence of a catalyst which is stannous carbonate or a compound of formula in which R is a hydrocarbon radical, R1 is an acyl or aryl radical, p = 0 or 2 and m = 1 or 0. Suitable compounds are: stannous oxide, stannous hydroxide, stannous salts of weak acids, e.g. stannous stearate or octoate, and dialkyltin dicarboxylates. They may be used in an amount of 0.001 to 1% by wt. of the glycidyl polyether; the latter may be derived from 2,2-bis-(4-hydroxyphenyl) propane. The fatty acid may be an ethylenically unsaturated monocarboxylic acid, e.g. derived from a drying or semi-drying oil.