Process for removing acid from cathodic electrocoating baths
US4775478A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 28, 1987 |
| Grant date | Oct 4, 1988 |
| Priority date | — |
| Expiry date | Aug 28, 2007 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC25D13/24
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
The present invention relates to a novel process for removing acids from cathodic electrocoating baths, in which electrically conductive substrates are coated with cationic resins present in the form of aqueous dispersions, part or all of the dip-coating bath being subjected to an ultrafiltration in which the ultrafiltration membrane retains the cationic resin and an ultrafiltrate is formed which contains water, solvent, low molecular weight substances and ions, and part or all of the ultrafiltrate being recycled to the coating bath, in which process PA0 (a) part or all of the ultrafiltrate, before recycling to the electrocoating bath and PA0 (b) an aqueous solution of an organic or inorganic base, which may or may not contain salts, are each introduced into one or more chambers, separated from one another by an anion exchange membrane, of an exchange cell, solutions (a) and (b) being led over the surface of the membrane.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.