Cationic deposition of polymers onto a conductive surface
AssigneeThe Dow Chemical Company
InventorsEarl H. Wagener, Ritchie A. Wessling, Dale S. Gibbs
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Abstract
A method for electrodeposition of an organic material on an electroconductive surface comprising placing the electroconductive surface to be coated in contact with an aqueous dispersion containing a water-insoluble, essentially electrically non-conductive, film-forming, organic polymer as cation-active particles wherein the cation-activity is provided at least predominantly by sulfonium cations and passing an electric current from an electrode through the latex to the electroconductive surface in such a direction that the electroconductive surface is negatively charged, i.e., becomes a cathode in an electrophoretic cell. By use of alternating current both electrodes become coated with the polymer.
Claims18
A process for applying a thin, smooth, uniform coating on an object having an electroconductive surface comprising
- (1) immersing the object in a coating bath comprising an aqueous dispersion having a pH in the range from about 2 to about 12 of cation-active particles of water-insoluble, essentially electrically non-conductive, organic, film-forming polymer wherein the cation-activity is provided at least predominantly by sulfonium cations;
- (2) passing an electric current through said bath sufficient to effect deposition of a coating of said polymer on the object by providing a difference of electrical potential between the object and an electrode that is
- (a) spaced apart from said object
- (b) in contact with said bath
- (c) electrically positive in relation to said object, said electric current autogenously stopping or becoming very low when the article is coated.
A process for applying a thin, smooth, uniform coating on an electroconductive article in an electrophoretic cell comprising a coating bath containing an aqueous dispersion of polymer having a pH in the range from about 2 to about 12, an anode, and a cathode having a surface to be coated, said process comprising connecting said anode and said cathode to a source of electromotive potential, applying said potential across said anode and said cathode to pass an electric current through the dispersion and thereby to electrodeposit a coating of polymer on said cathode surface, said aqueous dispersion comprising dispersed cation-active particles of a water-insoluble, essentially electrically non-conductive, film-forming, organic polymer wherein the cation-activity is provided at least predominantly by a sulfonium cation;
- said electric current autogenously stopping or becoming very low when the article is coated.
Dependencies are inferred from the claim text.