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. 20, 2011
Filed:
Sep. 28, 2007
Kotaro Takita, Nasusiobara, JP;
Shintaro Kikuchi, Saitama, JP;
Kotaro Takita, Nasusiobara, JP;
Shintaro Kikuchi, Saitama, JP;
Abstract
A microporous 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 extruding a combination of a diluent or solvent and a polyolefin resin composition comprising (a) from about 74 to about 99% of a first polyethylene resin having a weight average molecular weight of from about 2.5×10to about 5×10and a molecular weight distribution of from about 5 to about 100, (b) from about 1 to about 5% of a second polyethylene resin having a weight average molecular weight of from about 5×10to about 1×10and a molecular weight distribution of from about 5 to about 100, and (c) from 0 to about 25% of a polypropylene resin having a weight average molecular weight of from about 3×10to about 1.5×10, a molecular weight distribution of from about 1 to about 100, and a heat of fusion of 80 J/g or higher, percentages based on the mass of the polyolefin composition; cooling the extrudate to form a high polyolefin content cooled extrudate; stretching the cooled extrudate in at least one direction at a high stretching temperature to form a stretched sheet; removing at least a portion of the diluent or solvent from the stretched sheet to form a membrane; stretching the membrane to a high magnification in at least one direction to form a stretched membrane; and heat-setting the stretched membrane to form the microporous membrane.