Raychem Limited

Scimat Limited

David J Barker

Robert H McLoughlin

George B Park

John A Cook

Kenneth B Pithouse

Mike G Dorling

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.

Microporous films

Curable fabric comprising first and second curing reactants, at least one of which is in the form of a fabric member, and comprising heat-recoverable fabric members.

Curable fabric

A dimensionally recoverable article, preferably a heat-recoverable article, has on at least part of a surface thereof an adhesive composition that will cure by reaction of a plurality of mutually reactive components. The components are in the form of particles which are mixed together and which will fuse when heated. Preferred adhesives are based on combinations of an epoxy with a polyamide, carboxylic acid, phenolic resin or blocked isocyanate curing agent. The particulate adhesives show a synergistic increase in rate and/or level of cure when used in conjunction with a recoverable article.

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Faringdon, United Kingdom

David J Barker