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:
Sep. 28, 1999
Filed:
Oct. 31, 1995
Kazuo Wakimura, Osaka-fu, JP;
Tadaharu Hase, Osaka-fu, JP;
Yoshihiro Sezaki, Osaka-fu, JP;
Koji Fujita, Osaka-fu, JP;
Takeshi Isobe, Osaka-fu, JP;
Shin-ichi Tadokoro, Niigata-ken, JP;
Rensuke Ikarashi, Niigata-ken, JP;
Mitsui Chemicals, Inc., Tokyo, JP;
Kuraray Co., Ltd., Okayama-ken, JP;
Abstract
A process for producing refined methacrylic acid comprising the steps of oxidizing methacrolein and the like catalytically in a vapor phase to form a methacrylic acid-containing gas, cooling and condensing the gas to an aqueous methacrylic acid solution, adding to the solution an organic solvent that forms two liquid phases with water to carry out an extraction operation and thereby to obtain an extract, bringing the extract into contact with water to mix them together, separating the mixture into an organic phase and a water phase, and distilling the organic phase. According to this process, highly refined methacrylic acid containing little dibasic acids such as maleic acid and citraconic acid can be obtained economically and without increasing wastes that are unrecoverable to the process.