Water-Thinnable Epoxy Resin Esters and the preparation thereof

1,156,444. Epoxy resin esters. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 17 Jan., 1968, No. 2509/68. Heading C3B. [Also in Division C7] Water thinnable condensation products are obtained by: (1) reacting a hydroxyl group containing polyglycidyl ether of bisphenol A having an OH equivalency (i.e. the number of actual and potential OH groups per molecule) between 5 and 10 with (a) an aromatic monocarboxylic acid, e.g. benzoic acid, and then (b) with an ethylenically unsaturated fatty acid, e.g. a drying oil acid. The number of COOH groups in (a) and (b) is substantially equal to the OH groups of the polyglycidyl ether and the ratio of (a) to (b) lies in the range 10: 90 to 60: 40; this step is carried out at elevated temperature with separation of the water formed. (2) The resultant polyester is then reacted with at least 4% by wt. of an ethylenically unsaturated polycarboxylic acid or anhydride, e.g. maleic, and (3) at least 50% of the COOH groups of step (2) are neutralized, e.g. with a caustic alkali or an amine. The reactions may be carried out in the presence of an esterification catalyst, e.g. stannous octoate. A lyotropic solvent, e.g. ethylene glycol monobutyl ether may be added after stage (2). The products are useful in the manufacture of water thinnable paints and varnishes, which may be used in electrophosetic deposition.