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AssigneesAsahi Glass Company, Limited, Sasakura Engineering Co., Ltd.
InventorsHiroshi Funaki, Koichi Yanase, Hiroki Kamiya, Masao Uehara, Kenichiro Nagatomo, Yasushi Nishimura, Shiro Ohno, Satoru Hirano
Estimating the term…
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.
A method for recovering a fluorine-containing emulsifier, which comprises subjecting an aqueous solution (A) containing a fluorine-containing emulsifier in a concentration of at least 1 ppm by mass and at most 1% by mass, to vacuum concentration under a pressure of at most 100 kPa and a temperature of the aqueous solution (A) of at most 100° C., to obtain a concentrated aqueous solution (B) containing the fluorine-containing emulsifier in a higher concentration, and recovering the fluorine-containing emulsifier from the aqueous solution (B).
Dependencies are inferred from the claim text.