Process for electrodeposition of graft copolymer

Claim 2

In a process for electrocoating with paint a cathodically-charged substrate immersed in a coating bath containing an aqueous dispersion of said paint, said bath having a cathode zone containing said substrate and an anode zone containing a charged anode, the charged electrodes being maintained in electrical contact with each other by means of said bath, wherein said bath comprises a cationic film-forming polymer, an acidic ionizing agent, the improvement which comprises: employing an organic acid which is volatile at temperatures used to crosslink the film-forming polymer as the acidic ionizing agent; employing as the cationic film-forming polymer a graft copolymer comprising a mono-epoxide portion grafted onto an acrylic-amine backbone portion, which portions consist essentially of, by weight based on the graft copolymer about: (a) 25-60% of an acrylic-amine backbone copolymer contributing:

Claim 3

7-35% of secondary amine acrylate or methacrylate, giving 0.08 to 0.2 equivalent of tertiary amine per 100 grams of graft copolymer, 7-17% of hydroxy-functional acrylate or methacrylate, 3-7.3% ethyl acrylate or methyl methacrylate, and 0.3-0.7% mercaptoethanol, giving primary terminal hydroxyl functionality, graft copolymerized with (b) and (c): (b) 33-60% of an epoxy-fatty acid copolymer of a condensation polymer of equimolar proportions of epichlorohydrin and bisphenol A, said condensation polymer being reacted with fatty acid in the range of 1/1.4-1.7, and (c) 7-15% of a glycidyl ester of a tertiary carboxylic acid containing 7 to 9 carbon atoms, and subsequently curing the paint to crosslink the film-forming polymers.

Claim 4

7-35% of secondary amine acrylate or methacrylate, giving 0.08 to 0.2 equivalent of tertiary amine per 100 grams of graft copolymer, 7-17% of hydroxy-functional acrylate or methacrylate, 3-7.3% ethyl acrylate or methyl methacrylate, and 0.3-0.7% mercaptoethanol, giving primary terminal hydroxyl functionality, graft copolymerized with (b) and (c): (b) 33-60% of an epoxy-fatty acid copolymer of a condensation polymer of equimolar proportions of epichlorohydrin and bisphenol A, said condensation polymer being reacted with fatty acid in the range of 1/1.4-1.7, and (c) 7-15% of a glycidyl ester of a tertiary carboxylic acid containing 7 to 9 carbon atoms, and subsequently curing the paint to crosslink the film-forming polymers.

Claim 5

In a process for electrocoating with paint a cathodically-charged substrate immersed in a coating bath containing an aqueous dispersion of said paint, said bath having a cathode zone containing said substrate and an anode zone containing a charged anode, the charged electrodes being maintained in electrical contact with each other by means of said bath, wherein said bath comprises a cationic film-forming polymer, an acidic ionizing agent, and a crosslinking agent, the improvement which comprises: employing an organic acid which is volatile at temperatures used to crosslink the film-forming polymer as the acidic ionizing agent; employing as the cationic film-forming polymer a graft copolymer of claim 1, and employing as the crosslinking agent a composition which is nonreactive in the bath but reactive with said film-forming polymer at elevated temperatures to crosslink the polymers to form a durable paint film, and subsequently curing the paint to crosslink the film-forming polymers.

Claim 6

In a process for electrocoating with paint a cathodically-charged substrate immersed in a coating bath containing an aqueous dispersion of said paint, said bath having a cathode zone containing said substrate and an anode zone containing a charged anode, the charged electrodes being maintained in electrical contact with each other by means of said bath, wherein said bath comprises a cationic film-forming polymer, an acidic ionizing agent, and a crosslinking agent, the improvement which comprises: employing an organic acid which is volatile at temperatures used to crosslink the film-forming polymer as the acidic ionizing agent; employing as the cationic film-forming polymer a graft copolymer of claim 1, and employing as the crosslinking agent a composition which is nonreactive in the bath but reactive with said film-forming polymer at elevated temperatures to crosslink the polymers to form a durable paint film, and subsequently curing the paint to crosslink the film-forming polymers by heating the coated substrate to a temperature of at least about 175° C. for at least about 30 minutes.