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Randal L Perry

Robert S Mallouk

Phillip A Branca

Daniel E Hubis

A composite, porous, liquid-permeable article is provided which is a multilayer structure of discrete, bonded layers of porous, expanded polytetrafluoroethylene (EPTFE). The composite has its interior and exterior surfaces coated with a perfluoro ion exchange polymer to render the composite hydrophilic so as to resist gas locking in aqueous media. Initially, the diaphragm may also contain a water-soluble surfactant to assist in initial water penetration into the pores of the composite. An improved electrolytic cell is provided having the composite diaphragm as the porous separator in the electrolysis of alkali halide solutions. The diaphragm is also useful as an improved filter medium.

Electrolytic cell with composite, porous diaphragm

A composite, porous, liquid-permeable article is provided which is a multilayer structure of discrete, bonded layers of porous, expanded polytetrafluoroethylene (EPTFE), which composite has its interior and exterior surfaces coated with a perfluoro ion exchange polymer to render the composite hydrophilic so as to resist gas locking in aqueous media wherein a composite diaphragm made therefrom, may also contain a water-soluble surfactant to assist in initial water penetration into the pores of the composite whereby an improved electrolytic cell is provided having the composite diaphragm as the porous separator in the electrolysis of alkali halide solutions and wherein the diaphragm is also useful as an improved filter medium.

Composite, porous diaphragm

A dimensionally stable, composite membrane of a microporous film in laminar contact with a continuous perfluoro ion exchange resin layer is provided. The composite membrane comprises a continuous perfluoro ion exchange polymer layer which has an original, as-prepared, length, width and thickness, the ion exchange polymer layer being in laminar attachment to a film of a microporous material, preferably porous, expanded polytetrafluoroethylene (EPTFE), the microporous film having essentially the same length and width as the as-prepared continuous perfluoro ion exchange layer. The perfluoro ion exchange layer is swollen with a hydrophilic liquid to an extent that the hydrophilic liquid exceeds 20% by weight of the swollen, continuous perfluoro ion exchange layer. The swollen ion exchange layer exhibits less than a 5% increase in either length or width from its original, as-prepared, state, but it exhibits a substantial increase in thickness over its original, as-prepared, state. The method of use of a dimensionally stable, expanded polytetrafluoroethylene (EPTFE) and perfluoro ion exchange resin composite membrane in a facilitated transport unit operation is also provided, the composite membrane comprising a continuous perfluoro ion exchange polymer layer in laminar attachment to a film of porous EPTFE, the perfluoro ion exchange layer being swollen with a hydrophilic liquid. The method is used in the facilitated transport separation of acid gas from a hydrocarbon stream.

Composite membrane for facilitated transport processes

An abrasion-resistant, tear-resistant, multilayer composite membrane, useful in electrolysis, is provided comprising a continuous perfluoro ion exchange polymer film attached to a reinforcing fabric by means of a porous, expanded polytetrafluoroethylene (EPTFE) interlayer. The fabric and EPTFE are rendered hydrophilic and non-gas-locking by coating the interior and exterior surfaces thereof with a perfluoro ion exchange resin of equivalent weight less than 1000. The composite preferably is treated with an ionic perfluoro surfactant. Also provided is a multilayer composite according to the above in which the continuous perfluoro ion exchange film is itself a multilayer construction of a perfluorosulfonate polymer and a thin layer of perfluorocarboxylate polymer in which the perfluorosulfonate polymer interfaces with the EPTFE and the interior and exterior surfaces of the EPTFE and fabric are coated with perfluorosulfonate polymer. Also provided are a method of making the composites and methods of use for these fabric reinforced thin membrane structures as separators in electrolytic cells, and as selective barriers in permeation separation and facilitated transport operations.

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Wilmington, DE, United States of America

Randal L Perry