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. 27, 2011
Filed:
Apr. 09, 2007
Kotaro Takita, Tochigi-ken, JP;
Shintaro Kikuchi, Saitama-ken, JP;
Kotaro Takita, Tochigi-ken, JP;
Shintaro Kikuchi, Saitama-ken, JP;
Tonen Chemical Corporation, Tokyo, JP;
Abstract
A microporous polyolefin membrane having a structure in which its pore size distribution curve obtained by mercury intrusion porosimetry has at least two peaks, which is produced by (1) extruding a melt-blend of (a) (i) a polyethylene resin containing 7% or less by mass of ultra-high-molecular-weight polyethylene having a weight-average molecular weight of 1×10or more, or (ii) a mixture of 75% by mass or more of said polyethylene resin and 25% or less by mass of polypropylene, and (b) a membrane-forming solvent, (2) stretching a gel-like sheet obtained by cooling an extrudate, (3) washing it, (4) stretching the resultant microporous membrane to 1.1-1.8 fold in at least one direction, and (5) heat-setting it at a temperature in a range of the stretching temperature of the microporous membrane plus or minus 5 degrees centigrade.