The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 11, 1994
Filed:
Dec. 15, 1993
Chlorine Engineers Corp. Ltd., Tokyo, JP;
Abstract
Waste solution of developer, used as developer for a positive type photo resist and containing tetraalkylammonium hydroxide is neutralized with carbon dioxide, and it is filtered through a separation membrane. After removing precipitates of insoluble organic substances, it is sent to an anode chamber of an electrolytic cell divided by a cation exchange membrane, and electrolysis is performed. Low grade organic compounds in aqueous solution of tetraalkylammonium hydroxide obtained from a cathode chamber of a first stage electrolytic cell are oxidized and decomposed and are then supplied to an anode chamber of the next stage electrolytic cell, and high purity tetraalkylammonium hydroxide aqueous solution is obtained from the cathode chamber. Or, the solution is sent to an anode chamber of a multi-chamber electrolytic cell, where a plurality of ion exchange membranes are furnished and an intermediate chamber is provided between the anode chamber and the cathode chamber, low grade organic substances in the intermediate chamber are oxidized and decomposed, and high purity tetraalkylammonium hydroxide aqueous solution is obtained from the cathode chamber through electrolysis.