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. 08, 2002
Filed:
Aug. 30, 1999
Philip D. Radovanovic, Minneapolis, MN (US);
Mario A. Perez, Burnsville, MN (US);
Scott D. Thomas, Woodbury, MN (US);
3M Innovative Properties Company, Saint Paul, MN (US);
Abstract
Microporous material comprising a polypropylene polymer having at least 20 percent crystallinity; and a compatible, amorphous, glassy polymer, wherein said polymers are miscible in a compound when heated above the melting temperature of the polypropylene polymer and wherein a polypropylene polymer phase separates from the compound when cooled below the crystallization temperature of the polypropylene polymer. Microporous material is made by a thermally induced phase separation process using a compound such as mineral oil to form one phase containing both polymers. The pores of the microporous material resist collapse during processing. Membranes made of this material are useful as battery separators having a good combination of strength, porosity, and ionic resistance when imbibed with an electrolyte.