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:
Apr. 06, 2004
Filed:
Oct. 17, 2001
Kazuyori Yoshimi, Kurashiki, JP;
Kuraray Co., Ltd., Kurashiki, JP;
Abstract
The present invention provides a method for producing an ethylene-vinyl acetate copolymer (EVA) containing 5 mol % to 60 mol % of ethylene, by copolymerizing ethylene and vinyl acetate with a polymerization initiator, in which an aliphatic alcohol having not more than four carbon atoms is used as the polymerization solvent, the contents of acetaldehyde and a saturated acetic ester with respect to vinyl acetate are not more than 200 ppm, and 10 ppm to 1500 ppm, respectively, and polymerization is carried out at a temperature of 30° C. to 150° C. EVA obtained by the foregoing method may be saponified to obtain a saponified ethylene-vinyl acetate copolymer (EVOH). According to the present invention, at least one of (i) improved melt-extrusion stability, (ii) improved melt-moldability, (iii) reduced discoloration, and (iv) reduced gelation is achieved.