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. 13, 2015
Filed:
Feb. 24, 2012
William Winchin Yen, Acton, MA (US);
William Winchin Yen, Acton, MA (US);
APOROUS, INC., Tyngsboro, MA (US);
Abstract
The present invention is directed to a sheet product and to a method of forming the sheet product suitable for use as a battery separator. The method comprises forming a mixture of a thermoplastic polymer and fluid having a high vapor pressure, shaping the mixture into a sheet material and subjecting the sheet material to stretching/fluid vaporization at high temperature to form an intermediate material having a ratio of percent fluid to percent polymer crystallinity of between 0.15 and 1 followed by a second stretching/fluid vaporization at a lower temperature while removing a portion of the remainder of the fluid from the sheet. The resultant sheet is annealed and remainder of fluid removed to form a sheet product having a thickness comprising a stratified structure of small and larger pore layered configuration across its thickness.