Patents by Inventor Stephen B. Willis

Stephen B. Willis 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).

  • Preparation of ferric aminopolycarboxylate solutions having improved stability
    Patent number: 5898078
    Abstract: A process for preparing a ferric chelate of an aminopolycarboxylic acid wherein an iron-containing material is reacted with an aminopolycarboxylic acid chelant in the presence of a base, which comprises employing reactants such that the molar ratio of chelant to iron is from about 0.8 to about 0.99, is disclosed. In preferred embodiments the chelate is a ferric ammonium ethylenediaminetetraacetic acid chelate. The inventive chelates show a reduced tendency to form a dark precipitate upon standing. This process is particularly suitable for use in preparing chelates for use in applications such as photographic bleaching. The corresponding ferric chelate composition and products prepared by the described process are also disclosed.
    Type: Grant
    Filed: January 22, 1998
    Date of Patent: April 27, 1999
    Assignee: The Dow Chemical Company
    Inventors: George M. St. George, Stephen B. Willis, David A. Wilson
  • Modified polyalkylenepolyamines
    Patent number: 4519843
    Abstract: An aqueous hydraulic cement slurry is disclosed which comprises water, a hydraulic cement, a surfactant and, as a fluid loss additive, epihalohydrin derivatives of polyalkylenepolyamines.
    Type: Grant
    Filed: August 8, 1984
    Date of Patent: May 28, 1985
    Assignee: The Dow Chemical Company
    Inventors: Stephen B. Willis, Pamela J. Boyce
  • Modified polyalkylenepolyamines
    Patent number: 4482667
    Abstract: Modified polyalkylenepolyamine compositions are prepared which are useful as fluid loss additives.
    Type: Grant
    Filed: March 5, 1984
    Date of Patent: November 13, 1984
    Assignee: The Dow Chemical Company
    Inventors: Stephen B. Willis, Pamela J. Boyce
  • Aqueous hydraulic cement slurry
    Patent number: 4461856
    Abstract: An aqueous hydraulic cement slurry is disclosed which comprises water, a hydraulic cement, a surfactant and, as a fluid loss additive, epihalohydrin derivatives of polyalkylenepolyamines.
    Type: Grant
    Filed: November 3, 1983
    Date of Patent: July 24, 1984
    Assignee: The Dow Chemical Company
    Inventors: Stephen B. Willis, Pamela J. Boyce