| 摘要 |
Electrocoating compositions comprise (i) a partial ester of a diol e.g. neopentyl glycol or 2,2 - bis(4 - hydroxycyclohexyl)propane and an addition product of a drying oil fatty acid ester e.g. linseed oil and an alpha-beta-ethylenically unsaturated dicarboxylic acid or anhydride e.g. maleic anhydride or itaconic anhydride and (ii) a substantially completely etherified aminoplast e.g. hexakis (methoxymethyl)melamine. The addition product of (i) may also include units from an additional olefinic comonomer e.g. styrene, a substituted styrene, an alkyl acrylate or methacrylate, a diolefin or acrylonitrile. Free acid groups in (i) may be neutralized e.g. with a water-soluble amine or metal or quaternary ammonium hydroxide. The pH of the composition should be at least 7, preferably 7.5 to 10.5. The composition may also contain various organic and inorganic pigments, a corrosion inhibitor such as strontium chromate, dispersing on surface-active agents, antioxidants, driers, anti-foaming agents and bactericides. Electrocoating.-The compositions may be coated on iron, steel, aluminium, galvanized steel, phosphatized steel, zinc or copper at a voltage of 1 to 1000 and a current density of 0.1 to 15 amp/sq. ft. from an aqueous bath containing 1 to 20% of the composition. The coating may be baked at 300 DEG to 400 DEG F. for 10 to 30 minutes.ALSO:Electro-coating compositions comprise (i) a partial ester of a diol and an addition product of a drying oil fatty acid ester and an alpha-betaethylenically unsaturated dicarboxylic acid or anhydride or itaconic anhydride and (ii) a substantially completely etherified aminoplast. The addition product of (i) may also include units from an additional olefinic comonomer e.g. styrene, a substituted styrene, an alkyl acrylate or methacrylate, a diolefin or acrylonitrile. Free acid groups in (i) may be neutralized e.g. with a water-soluble amine or metal or quaternary ammonium hydroxide. The pH of the composition should be at least 7, preferably 7.5 to 10.5. The composition may also contain various organic and inorganic pigments, a corrosion inhibitor such as strontuim chromate, dispersing on surface-active agents, antioxidants, driers, anti-foaming agents and bactericides. Electro-coating The compositions may be coated on iron, steel, aluminium, galvanized steel, phosphatized steel, zinc or copper at a voltage of 1 to 1000 and a current density of 0.1 to 15 amp/sq. ft. from an aqueous bath containing 1 to 20% of the composition. The coating may be baked at 300 to 400 DEG F., for 10 to 30 minutes.
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