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. 23, 1991
Filed:
Aug. 09, 1989
Harlan B Johnson, Rittman, OH (US);
Samuel B Laferty, Akron, OH (US);
Melvin P Wagner, Wadsworth, OH (US);
Shantilal M Mohnot, Copley, OH (US);
PPG Industries, Inc., Pittsburgh, PA (US);
Abstract
Described is a porous flexible sheet of about 93 to 99.5 weight percent amorphous precipitated silica and from about 0.5 to about 7 weight percent fibrillated, unsintered polymeric material, e.g., polytetrafluoroethylene. The sheet is useful as a separator in absorbed electrolyte gas recombinant batteries, e.g., lead-acid batteries, and has a tensile strength of less than 75 pounds per square inch (0.5 MPa). The sheet preferably has a porosity of from 85 to 92 percent and exhibits an electrical resistance of less than 3.5 milliohm-in.sup.2 /10 mil when saturated with 37 percent sulfuric acid. The sheet is prepared by subjecting a dry homogeneous mixture of the silica and polymeric material, e.g., polytetrafluoroethylene, in the above proportions to mechanical shear blending forces to fibrillate the polymer and thereafter dry forming the resulting admixture into sheet form.