Bha Group, Inc.

Bha Technologies, Inc.

Micell Technologies, Inc.

Robert John Klare

James P DeYoung

James B McClain

Greg Strugalski

David Elliot Chubin

James Deyoung

The present invention is a method for modifying at least one property of a porous membrane. The method comprises the steps of providing a porous membrane. The method also includes exposing the membrane to a fluid at supercritical conditions. At least one property of the membrane is modified while the membrane is exposed to the fluid at supercritical conditions. The condition of the fluid is changed in such a manner that the porous membrane retains the modified property. The present invention is also sheet material that is water-resistant, moisture vapor transmissive and air permeable. The sheet material comprises a membrane having an open pore structure including surfaces defining a plurality of interconnecting pores extending through the membrane and between major sides of said membrane in which the pores have an average pore size. The membrane is made from a material tending to absorb oils and contaminating agents. A uniform coating of precipitated fluorinated urethane polymer material on at least portions of the surfaces of the nodes and fibrils defining the pores. The precipitated fluorinated urethane polymer material provides oil and contaminating agent resistance of at least a number 6 by AATCC 118 testing and an air permeability of at least 0.20 CFM per square foot by ASTM D737 testing.

Treatment of porous article

A composite article, in an exemplary embodiment, includes a porous membrane formed from a first material, a coating formed from a second material applied to at least a portion of the porous membrane, and a third material covering at least a portion of the porous membrane. The third material is substantially incompatible with the first material. The second material of the coating is compatible with the first material and the third material. The coating is positioned between the first material and the third material The third material is connected to the first material by the coating on the porous membrane.

Composite membrane

A method of making a composite membrane with ion exchange properties includes, in an exemplary embodiment, forming a porous membrane from a first material, dissolving a coating material in a fluid at supercritical conditions, and exposing the porous membrane to the coating material dissolved in the supercritical fluid. The method also includes precipitating a uniform coating of the coating material onto an exterior surface of the porous membrane by changing the supercritical conditions of the fluid to a non-supercritical condition, and applying an ion exchange material to the coated porous membrane so that the ion exchange material is in intimate contact with substantially all of the coated surfaces of the porous membrane.

Method of making a composite membrane

An air permeable composite article that in one embodiment includes a porous base membrane that includes a plurality of nodes and fibrils defining a plurality of interconnecting pores extending through the porous base membrane with each node and fibril having a surface. The composite article also includes a precipitated coating material deposited on the surfaces of the plurality of nodes and fibrils. The coating material includes a copolymer formed from a fluorinated acrylate or methacrylate, an n-alkyl acrylate or methacrylate, and an isocyanate crosslinker. The precipitated coating material provides oil and contaminating agent resistance of at least a number six measured in accordance with AATCC 118 test method.

Composite membrane having oleophobic properties

A method of treating a membrane comprises the steps of providing a membrane with surfaces that define a plurality of pores extending through the membrane. Providing a dispersion of oleophobic fluoropolymer solids. Stabilizing the dispersion with a stabilizing agent. Diluting the dispersion with a wetting agent. Wetting surfaces which define the pores in the membrane with the diluted and stabilized dispersion. Removing the wetting agent and the stabilizing agent from the membrane. Coalescing the oleophobic fluoropolymer solids of the dispersion on surfaces that define pores in the membrane. A composite membrane comprises a porous membrane having a plurality of interconnecting pores extending through the membrane and made from a material which tends to absorb oils and certain contaminating surfactants. A coating is disposed on surfaces of the nodes and fibrils defining the interconnecting passages in the membrane. The coating comprises oleophobic fluoropolymer solids coalesced on surfaces of the nodes and fibrils to provide oil and surfactant resistance to the composite membrane without completely blocking pores in the membrane. The composite membrane is gas permeable, liquid penetration resistant and capable of moisture vapor transmission at a rate of at least 70,000 gr/mday.

Porous membrane structure and method

A method of treating a membrane comprises the steps of providing a membrane with surfaces that define a plurality of pores extending through the membrane. Providing a dispersion of oleophobic fluoropolymer solids. Stabilizing the dispersion with a stabilizing agent. Diluting the dispersion with a wetting agent. Wetting surfaces which define the pores in the membrane with the diluted and stabilized dispersion. Removing the wetting agent and the stabilizing agent from the membrane. Coalescing the oleophobic fluoropolymer solids of the dispersion on surfaces that define pores in the membrane. A composite membrane comprises a porous membrane having a plurality of interconnecting pores extending through the membrane and made from a material which tends to absorb oils and certain contaminating surfactants. A coating is disposed on surfaces of the nodes and fibrils defining the interconnecting passages in the membrane. The coating comprises oleophobic fluoropolymer solids coalesced on surfaces of the nodes and fibrils to provide oil and surfactant resistance to the composite membrane without completely blocking pores in the membrane. The composite membrane is gas permeable, liquid penetration resistant and capable of moisture vapor transmission at a rate of at least 70,000 gr/m day.

A method of treating a membrane ( ) comprises the steps of providing a membrane ( ) with a structure of node ( ) and fibrils ( ). Surfaces of the nodes ( ) and fibrils ( ) define a plurality of pores ( ) extending through the membrane ( ). The membrane ( ) is made from an expanded polytetrafluoroethylene material. A water-based dispersion of oleophobic fluoropolymer solids in a water-soluble solvent is provided. The dispersion has surface tension and relative contact angle properties such that the diluted dispersion is incapable of wetting the polytetrafluoroethylene material of the membrane ( ). The dispersion is diluted with a liquid wetting agent so the diluted dispersion can wet the membrane ( ). Surfaces of the nodes ( ) and fibrils ( ) are coated with the solids in the diluted dispersion. The wetting agent material and other fugitive material are removed. Solids in the diluted dispersion are thermally coalesced on surfaces of the nodes ( ) and fibrils ( ) without completely blocking the pores ( ) in the membrane ( ).

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St. Joseph, MO, United States of America

Robert John Klare