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. 21, 2015
Filed:
Jan. 31, 2013
Sumitomo Chemical Company, Limited, Chuo-ku, Tokyo, JP;
Daizaburo Yashiki, Niihama, JP;
Toshiki Innami, Niihama, JP;
Sumitomo Chemical Company, Limited, Tokyo, JP;
Abstract
Provided is a method for reproducibly and efficiently producing a polyolefin porous film having a porous structure suitable for a separator for a battery without requiring a special apparatus. The method according to the present invention is a method for producing a polyolefin porous film, the method including conveying a raw material polyolefin sheet having pores into a furnace of a tenter type stretching machine, and tenter-stretching the sheet in a plurality of stretching regions in the furnace to produce a polyolefin porous film, wherein the plurality of stretching regions include at least two stretching regions having different film widening speeds, and the temperature of a stretching region having a high film widening speed is lower than that of a stretching region having a low film widening speed in the at least two stretching regions, and a stretching region having the highest film widening speed is situated in the front stage with respect to a stretching region having the lowest film widening speed.