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:
Mar. 30, 1993
Filed:
Jun. 13, 1989
George B Park, Wiltshire, GB;
John A Cook, Oxfordshire, GB;
Mike G Dorling, Wiltshire, GB;
David J Barker, Oxford, GB;
Robert H McLoughlin, Wiltshire, GB;
Scimat Limited, , GB;
Abstract
A microporous polymeric film of high porosity comprises a halopolymer in which the repeating units are --(C.sub.n H.sub.2n)-- and --(C.sub.m X.sub.2m)-- in which each X independently represents fluorine or chlorine and the values of n and m are greater than one and less than six. The film is the result of firstly melt processing a mixture of the halopolymer, more than 150 parts by weight of an extractable salt and not more than 80 parts by weight of an extractable polymer per 100 parts by weight of the halopolymer, the extractable polymer not being completely and homogeneously mixed with the halopolymer and being less viscous than the halopolymer when both are molten so that the surfaces of the film resulting from melt processing are rich in the extractible polymer, and secondly extracting at least some of the extractable salt to render the film porous and extracting at least some of said polymer to impart surface porosity to the film. The film has a porosity of more than 50% by volume and more usually 60-70%. The film may be used as the separator of an electrochemical cell e.g. a battery having a lithium anode and a thionyl chloride electrolyte.