GB1219950A - Electrophoretic coating process - Google Patents

Abstract

1,219,950. Artificial resin compositions. AMERICAN CYANAMID CO. 2 Oct., 1968 [20 Nov., 1967], No. 46872/68. Headings C3B, C3P and C3R. [Also in Divisions C2 and C7] A composition for electrodeposition comprises an aqueous dispersion of a mixture, by wt., based on total solids of (A)+(B), of (A) a water-insoluble substantially fully-etherified tetramethylol guanamine containing on the average 13 C atoms exclusive of those in the triazine ring, 5-40%; and (B) a waterdispersible, non-gelled, ionically-charged, polymeric material which is heat-reactive with (A), 95-60%. (A) has formula where R, R<SP>1</SP>, R<SP>2</SP> and R<SP>3</SP> are the same or dif ferent C 1-8 alkyl radicals, and Z is H, a C 1-8 alkyl radical, or an aryl radical; however (A) may also unavoidably contain some incompletely methylolated and etherified guanamine. Tetramethylol benzoguanamine methyl ethers are prepared by heating a mixture of CH 3 OH, NaOH, and paraformaldehyde to 45‹ C., holding for 15 minutes, and adding benzoguanamine. The mixture is refluxed and then cooled to 28‹ C. HNO 3 is added, and later neutralized with NaOH. The mixture is then vacuum concentrated, and CH 3 OH and HNO 3 added. The mixture is held at 32-35‹ C. for 1 hr., neutralized with NaOH, and vacuum concentrated. Polymeric material (B) contains carboxyl, alcoholic hydroxyl, or amide group to cross-link with (A). (B) may be cationic or anionic. It may be a polyester or maleinized oil or be prepared by vinyl or epoxy polymerization. Preparation of B: (i) butyl acrylate, acrylic acid, butyl mercaptan, and cumene hydroperoxide are reacted in dioxane. The copolymer is dissolved in aqueous ammonia, (ii) styrene, ethyl acrylate, acrylic acid, and hydroxy ethyl methacrylate are reacted in the presence of a solution of NaHCO 3 , Na lauryl sulphate, and ammonium persulphate, (iii) styrene ethyl acrylate, acrylic acid, and acylamide are reacted in the presence of a solution of NaHCO 3 , Na lauryl sulphate, and ammonium persulphate, (iv) 4,4<SP>1</SP>-dihydroxy diphenyl dimethyl methane, epichlorohydrin, and tetraethylene pentamine are reacted in toluene; the resin is dissolved in aq. acetic acid. Examples of (B) are: maleinized polyester prepared from styrene/ allyl alcohol copolymer, tall-oil fatty acid, and maleic anhydride; butylacrylate/styrene/acrylic acid copolymer; styrene/ethyl acrylate/acrylic acid/hydroxyethyl methacrylate tetrapolymer; styrene/ethyl acrylate/acrylic acid/acrylamide tetrapolymer; alkyd prepared from stearic acid, trimellitic anhydride, phthalic anhydride, and styrene/allyl alcohol copolymer. The compositions may contain surfactants; other solvents, e.g. dioxane or 2-butoxyethanol; or pigments, e.g. TiO 2 or Fe 2 O 3 . For electrodeposition, the compositions may contain 3-30% total resins solids. The pH may be 1-11. The compositions may be deposited on steel or Al panels, at 100 v. for 1 minute or 35 v. for 3 minutes. The coated panels are then baked at 300-350‹ F.