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. 12, 2015
Filed:
Sep. 03, 2013
Nippon Shokubai Co., Ltd., Osaka, JP;
Nippon Shokubai Co., Ltd., Osaka, JP;
Abstract
A process for producing (meth)acrylic acid comprising the step of repeating a crystallization operation 'n' times to produce purified (meth)acrylic acid from crude (meth)acrylic acid, wherein: the each crystallization operation comprises a crystallizing step and a melting step; a polymerization inhibitor is not added to a (meth)acrylic acid melt obtained in the melting step of the first to n−1crystallization operation(s) and a (meth)acrylic acid solution subjected to the crystallizing step of the second to ncrystallization operation(s); and a concentration of a polymerization inhibitor in a (meth)acrylic acid solution subjected to the crystallizing step of the first crystallization operation is adjusted so that a concentration of the polymerization inhibitor in a (meth)acrylic acid solution subjected to the crystallizing step of the ncrystallization operation is 2 ppm by mass or higher.