| 摘要 |
A synthetic resin is obtained by forming an adduct from an a ,b -ethylenically unsaturated dicarboxylic acid or anhydride therof and a drying oil and/or semi-drying oil and/or a fatty acid thereof and/or resinic acids and/or partly hydrogenated resinic acids and/or esters of the aforementioned acids with polyhydric alcohols, partly esterifying the adduct with mono- and polyhydric alcohols or with polyhydric alcohols alone, and then completely or partly neutralizing the free carboxyl groups of the partly esterified adduct with ammonia or strong organic nitrogen-containing bases. The molar ratio of unsaturated dicarboxylic acids to fatty acids or resinic acids used to form the adduct is between 1:0.5 and 1:2, and the ratio of carboxyl groups to hydroxyl groups at the start of the partial esterification is between 1:0.7 and 1:1.9. The resins are water-dilutable and on addition of water and, where required, pigments and/or fillers, form coating compositions which may be applied electrophoretically, the resulting film being hardened by stoving. Viscosity-reducing compounds of formula R1-O-CH2-R2-(O-CH2-R2)n -O-R1 where R1 is an alkyl or acyl radical, R2 is -CH2- or -CH2-CH2- and n is 0 or 1, may be added to the resins. In examples adducts are formed by reacting maleic anhydride and fumaric acid with reaction mixtures obtained from ricinene oil, soya bean oil, dehydrated castor oil, safflower oil, rosin and pentaerythritol; the adducts are partly esterified with butanol and trimethylol propane, trimethylol propane alone, and with butanol and glycerin, and the products are neutralized with aqueous ammonia, triethylamine and dimethyl ethanolamine; aqueous compositions are prepared from the neutralized resins, Indian red being used as a pigment and glycol diethyl ether and ethylene glycol acetate as viscosity reducing compounds.ALSO:Electrically conductive material is coated by immersing it in an aqueous bath containing a water-dilutable synthetic resin obtained by forming an adduct from an a , b -ethylenically unsaturated dicarboxylic acid or anhydride thereof and a drying oil and/or semi-drying oil and/or a fatty acid thereof and/or resinic acids and/or partly hydrogenated resinic acids and/or esters of the aforementioned acids with polyhydric alcohols, partly esterifying the adduct with mono- and polyhydric alcohols or with polyhydric alcohols alone, and then completely or partly neutralizing the free carboxyl groups of the partly esterified adduct with ammonia or strong organic nitrogen-containing bases, and passing an electric current through the bath employing the conductive material as an anode. The molar ratio of unsaturated dicarboxylic acids to fatty acids or resinic acids used to form the adduct is between 1:0.5 and 1:2, and the ratio of carboxyl groups to hydroxyl groups at the start of the partial esterification is between 1:0.7 and 1:1.9. Pigments and/or fillers may be added and the resulting coatings may be hardened by stoving. Viscosity-reducing compounds of formula R1-O-CH2-R2-(O-CH2-R2) n-O-R1, where R1 is an alkyl or acyl radical, R2 is -CH2- or -CH2-CH2-and n is 0 or 1, may be added to the resins. In Examples adducts are formed by reacting maleic anhydride and fumaric acid with reaction mixtures obtained from ricinene oil, soya bean oil, dehydrated castor oil, safflower oil, rosin and pentaerythritol; the adducts are partly esterified with butanol and trimethylol propane, trimethylol propane alone, and with butanol and glycerine, and the products are neutralized with aqueous ammonia, triethylamine and dimethyl ethanolamine; aqueous compositions are prepared from the neutralized resins, Indian red being used as a pigment and glycol diethyl ether and ethylene glycol acetate as viscosity reducing compounds, and the compositions used to coat metal objects electro-phoretically with a D.C. voltage of about 100 volts.
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