GB1438726A - Aqueous thermosetting compositions - Google Patents

Abstract

1438726 Artificial resin coating composition DESOTO Inc 13 Nov 1973 [16 Nov 1972] 52673/73 Heading C3R An aqueous thermosetting coating composition of solids content #55% wt. comprises a medium containing by wt. #80 parts water for every 20 parts volatile organic solvent and, dispersed therein (1) an oil-free non-gelled OH- functional acidic polyester, (2) 5-40% wt., based on total resin solids, of at least one heathardening formaldehyde condensate, and (3) 5-40% wt., based on total resin solids of at least one adduct, of M.W. 300-5000 of ethylene oxide, 1,2-propylene oxide, or a C 3-14 lactone with a C # 3 aliphatic polyhydric alcohol; where polyester (1) is formed by reaction of a polycarboxylic acid component, of which a tricarboxylic acid component provides at least 70% of the acid functionality, with a stoichiometric excess of a polyalcohol component, consisting of at least one diol, providing 1À1-2 OH equivalents per -COOH equivalent in the polycarboxylic acid, the polyester having acid number 45-60 and being dispersed in the aqueous medium by means of a base. The acid component may include a saturated or aromatic dicarboxylic acid component, e.g. adipic, succinic, o-, iso-, or tere-phthalic acid, or ophthalic anhydride. The tricarboxylic acid component may be trimellitic or α-(2-carboxyethyl)-glutaric anhydride. The diol may be, e.g. ethylene, propylene, butylene, or diethylene glycol, but is preferably a glycol containing a tertiary C atom, e.g. the ester diol The volatile organic solvent may be MEK, 2- ethoxyethanol, 2 - butoxyethanol, or dioxane. The base may be, e.g. NH 3 , triethylamine, or dimethylethanolamine, and may partially or completely neutralize the polyester. The composition may have pH 6-11. The formaldehyde condensate may be urea-formaldehyde, hexamethoxymethylmelamine or transethers thereof, or benzoguanamine-formaldehyde, or acid derivatives thereof; or an "A" stage resol. The polyhydric alcohol in adduct (3) may be glycerol, a sorbitol, trimethylol propane, or pentaerithritol. The composition may be pigmented with TiO 2 of weight equal to the resin solids. Baking temperature may be, e.g. 300- 625‹ F. The substrate may be Zn-phosphatetreated steel.