Method for recovering fluorine-containing emulsifier
US7351342B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Dec 16, 2004 |
| Grant date | Apr 1, 2008 |
| Priority date | — |
| Expiry date | Jan 30, 2026 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC02F2303/16
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
An aqueous solution containing a fluorine-containing emulsifier in a low concentration of at least 1 ppm by mass and at most 1% by mass (e.g., coagulation waste water after an emulsion polymerization of a fluoropolymer and/or an aqueous solution obtained by washing with an aqueous solution a waste gas from a drying process and/or a heat treating process of the fluoropolymer) is subjected to vacuum concentration under a pressure of at most 100 kPa and a temperature of the aqueous solution of at most 100° C. by means of a heating tube surface evaporation type concentrator equipped with a heat pump or the like, and the fluorine-containing emulsifier is recovered from a highly concentrated aqueous solution containing the fluorine-containing emulsifier in a higher concentration of at least 5% by mass. According to the present method, the fluorine-containing emulsifier can be recovered with a high yield from a low-concentration liquid such as coagulation waste water of a fluoropolymer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.