Method for regenerating tetraalkylammonium hydroxide
US5354434A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 15, 1993 |
| Grant date | Oct 11, 1994 |
| Priority date | — |
| Expiry date | Dec 15, 2013 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC02F2201/46115
- WIPO fieldChemical engineering
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.