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:
May. 22, 1990
Filed:
Aug. 29, 1988
Central Glass Company, Limited, Ube, JP;
Abstract
A fluorocarbon carboxylic acid Rf(COOH).sub.m (Rf is C.sub.1 -C.sub.10 perfluoroalkyl group, m is 1 or 2) is prepared by the steps of hydrolyzing Rf(COF).sub.m with water to obtain an acidic solution, neutralizing the acidic solution with aqueous solution of KOH to form Rf(COOK).sub.m, precipitating and separating Rf(COOK).sub.m from the solution and converting Rf(COOK).sub.m into Rf(COOH).sub.m by acid decomposition. The content of free fluorine can extremely be reduced by treating Rf(COOK).sub.m with sulfuric acid and silica. The mother liquor is recycled after removing KF by treatment with a metal hydroxide and replenishing with KOH. In preparing a fluorocarbon sulfonic acid RfSO.sub.3 H (Rf is C.sub.1 -C.sub.3 perfluoroalkyl group) in substantially the same way, RfSO.sub.3 K is formed in aqueous solution of KOH by bringing gaseous RfSO.sub.2 F into contact with the KOH solution under normal pressure, while controlling the feed rate of RfSO.sub.2 F per unit area of gas-liquid contact at a sufficiently low level.