Sumitomo Electric Fine Polymer, Inc.

Aya Murata

Fumihiro Hayashi

Atsushi Uno

Hiroyuki Tsujiwaki

A porous polytetrafluoroethylene film comprising a fluororesin containing polytetrafluoroethylene as a main component, wherein an envelope surface area of resin fibers included per film having an area of 1 mand a thickness of 25 &#x3bc;m is 4,000 mor more, and a melting point peak is 333&#xb0; C. or lower.

Porous polytetrafluoroethylene film and method for producing same

A porous polytetrafluoroethylene composite includes a porous polytetrafluoroethylene film, a porous support layer that supports the porous polytetrafluoroethylene film, an adhesive layer bonded to the porous polytetrafluoroethylene film, and a porous reinforcement layer bonded to the adhesive layer, in which the adhesive layer is a layer composed of a fluororesin having a melting point, or a glass transition point when a melting point is not clearly defined, of lower than 260&#xb0; C.

Porous polytetrafluoroethylene composite and method for producing the same

Provided is a method for producing a porous polytetrafluoroethylene film having good chemical resistance, good heat resistance, a high porosity, and good dimensional stability. The method for producing a porous polytetrafluoroethylene film includes a stretching step of stretching a sheet-like molded body composed of a fluororesin containing polytetrafluoroethylene as a main component in a longitudinal direction and/or a lateral direction at a temperature lower than a melting point of the fluororesin to make a porous fluororesin film, and, after the stretching step, an annealing step of holding the porous fluororesin film in a shape-fixed state, and maintaining the porous fluororesin film at a temperature lower than the melting point of the fluororesin but not lower than a temperature 30&#xb0; C. lower than the melting point for 1 to 20 hours.

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Osaka, Japan

Aya Murata