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:
Oct. 20, 1998
Filed:
Feb. 07, 1997
Nitto Denko Corporation, Osaka, JP;
Abstract
A separator for battery which exhibits a low electrical resistivity at normal time, good SD characteristics and a high mechanical strength is disclosed. A high molecular weight polypropylene having a weight average molecular weight of 500,000 or more and a polyethylene having a melting point of from 100.degree. to 140.degree. C. are extruded through a T-die film-forming machine to prepare a laminate film comprising a laminate of the high molecular polypropylene layer and the polyethylene layer. The laminate film is stretched at a temperature as low as from -20.degree. C. to 80.degree. C. by 10% to 100% based on the length of the original film, stretched at a temperature as high as 80.degree. C. to 130.degree. C. by 60% to 300% based on the length of the unstretched film, and then shrunk at the same temperature by 5% to 30% based on the length of the stretched film to render the film porous. Thus, a porous laminate film having a Gurley value of from 200 to 1,500 is prepared as a separator for battery.