Patents by Inventor Hawk S. Wan

Hawk S. Wan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Process for making a microporous membrane from a blend containing a poly (phenylene sulfide) polymer, an amorphous polymer, and optionally a solvent
    Patent number: 5888434
    Abstract: The invention relates to a process for preparing a microporous membrane from an unsulfonated poly(phenylene sulfide) polymer by forming a mixture of an unsulfonated poly(phenylene sulfide) polymer, an amorphous polymer, and optionally a plasticizer, heating the resulting mixture, extruding or optionally casting the mixture into a membrane, controlled cooling (quenching) or coagulating the membrane, and leaching the membrane, while optionally drawing the membrane before, during, and/or after leaching.
    Type: Grant
    Filed: February 3, 1993
    Date of Patent: March 30, 1999
    Assignee: The Dow Chemical Company
    Inventors: Robert D. Mahoney, Jiro Kawamoto, Richard A. Lundgard, Mark F. Sonnenschein, Hawk S. Wan, H. Nelson Beck
  • Process of making microporous hollow fiber or film membrane of poly(phenylene sulfide) (PPS)
    Patent number: 5246647
    Abstract: The present invention relates to a process for preparing a microporous permselective membrane from a poly(phenylene sulfide) (PPS) polymer, an organic compound which substantially solubilizes the PPS below its melting point to form a homogenous mixture, heating the resulting mixture, extruding or casting the mixture into a membrane (fiber or film), quenching or coagulating the membrane, and leaching the membrane, while optionally drawing the membrane before, during, after leaching, or a combination thereof. In one embodiment, the solvent optionally includes an organic non-solvent to assist in obtaining the desired microporsity. The permselective polymers are useful to separate gaseous or liquid components from a mixture of components.
    Type: Grant
    Filed: August 19, 1991
    Date of Patent: September 21, 1993
    Assignee: The Dow Chemical Company
    Inventors: Henry N. Beck, Robert D. Mahoney, Hawk S. Wan, Chieh-Chun Chau, Timothy M. Finney, Ritchie A. Wessling, Jiro Kawamoto, Mark F. Sonnenschein
  • Process of making microporous membranes from poly(etheretherketone)-type polymers and low melting point crystallizable polymers
    Patent number: 5227101
    Abstract: The invention relates to a process for preparing a microporous membrane from an unsulfonated poly(etheretherketone)-type polymer by forming a mixture of an unsulfonated poly(etheretherketone)-type polymer, a low melting point crystallizable polymer, and a plasticizer, heating the resulting mixture, extruding or casting the mixture into a membrane, quenching or coagulating the membrane, and leaching the membrane, while optionally drawing the membrane before, during, after leaching, or a combination thereof.
    Type: Grant
    Filed: December 21, 1990
    Date of Patent: July 13, 1993
    Assignee: The Dow Chemical Company
    Inventors: Robert D. Mahoney, H. Nelson Beck, Richard A. Lundgard, Hawk S. Wan, Jiro Kawamoto, Mark F. Sonnenschein
  • Isotropic microporous syndiotactic polystyrene membranes and processes for preparing the same
    Patent number: 5015275
    Abstract: This invention relates to semi-permeable isotropic syndiotactic polystyrene microporous membranes and processes for preparing such membranes.
    Type: Grant
    Filed: July 14, 1989
    Date of Patent: May 14, 1991
    Assignee: The Dow Chemical Company
    Inventors: Henry N. Beck, Robert D. Mahoney, Hawk S. Wan, Richard A. Lundgard
  • Anisotropic microporous syndiotactic polystyrene membranes and a process for preparing the same
    Patent number: 4980101
    Abstract: This invention relates to semi-permeable anisotropic syndiotatic polystyrene microporous membranes and a process for preparing such membranes.
    Type: Grant
    Filed: July 14, 1989
    Date of Patent: December 25, 1990
    Assignee: The Dow Chemical Company
    Inventors: Henry N. Beck, Robert D. Mahoney, Hawk S. Wan, Richard A. Lundgard
  • Process for preparing membranes from tetrahalobisphenol polycarbonates
    Patent number: 4975228
    Abstract: A process for the preparation of a membrane comprising bisphenol-based polycabonate wherein at least 25 percent by weight of the bisphenol moieties are tetrahalogenated wherein the halogen is Cl or Br, and the membrane prepared by such process.
    Type: Grant
    Filed: July 29, 1988
    Date of Patent: December 4, 1990
    Assignee: The Dow Chemical Company
    Inventors: Edgar S. Sanders, Jr., Hawk S. Wan, Henry N. Beck