Patent ID: 6436263
Filing Date: 2002-08-20
Classification: C25D

Abstract:
An electrodeposition coating system comprising:a first electrode as an article to be coated provided in an electrodeposition bath and a plurality of second electrodes provided in association with the first electrode, wherein current is passed between the first electrode and the second electrodes through an aqueous solution of a substance contained in the electrodeposition bath, to electrodeposit the substance for forming a coating film onto the article to be coated, wherein each of the second electrodes comprises an electrode and a membrane which separates the electrode from the aqueous solution, wherein a second set of the second electrodes each comprise a low acid removal membrane electrode, wherein each of the second electrodes in the second set is provided with a corrosion resistant electrode material and a second membrane having a function of precluding most of a flow of an ionized neutralizing agent in the aqueous solution from being extracted, and wherein a first set of the second electrodes each comprise a high acid removal membrane electrode, wherein each of the second electrodes in the first set is provided with an electrode material and a membrane having a function of osmotically extracting the neutralizing agent from the aqueous solution, wherein a number of the low acid removal membrane electrodes and the high acid removal membrane electrodes are placed along a bath paint tank wall, wherein each of the high acid removal membrane electrodes is coupled to a first electrolyte circulation system to flow electrolyte from a first end of the high acid removal membrane electrode to a second end of the high acid removal membrane electrode between its first membrane and its electrode material, wherein each of the low acid removal membrane electrodes is coupled to a second electrolyte circulation system to flow electrolyte from a first end of the low acid removal membrane electrode to a second end of the low acid removal membrane electrode between its second membrane and its corrosion resistant electrode material, wherein the second electrolyte circulation system operates independently from the first electrolyte circulation system, wherein each of the first and second electrolyte circulation systems are provided with a corresponding first or second conductivity control system, wherein each of the first and second electrolyte conductivity control system is selectively activated if conductivity of the electrolyte in the corresponding first or second electrolyte circulation system exceeds a pre-set reference conductivity value and operates to introduce D.I. water to the electrolyte of the corresponding first or second electrolyte circulation system as a dilution media, wherein the second conductivity control system has a higher pre-set reference conductivity value than that of the first conductivity control system.