Patents by Inventor Andrew T. Graham

Andrew T. Graham 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).

  • Patent number: 5767213
    Abstract: The subject invention pertains to a process for preparing a fluid absorbent polymer wherein an ethylenically unsaturated monomer mixture is dispersed as droplets in an inert organic phase containing a hydrophobic suspending agent, such droplets being polymerized to form polymer particles having a hydrophobic surface, the improvement comprising blending the polymer particles with a hydrophilic material in the absence of an organic solvent, such as to render the hydrophobic surface hydrophilic.
    Type: Grant
    Filed: May 29, 1992
    Date of Patent: June 16, 1998
    Assignee: The Dow Chemical Company
    Inventors: Andrew T. Graham, Don L. Stevens
  • Patent number: 5629377
    Abstract: A water-absorbent resin particles that exhibits a centrifuged absorption capacity of 26 g/g or greater, an absorption under load of 24 g/g or greater at 0.6 psi load. Other aspects of the invention are processes for the preparation of such water-absorbent resin particles which comprise the inclusion of chlorine or bromine containing oxidizing agent followed by the heat-treatment to produce particles with superior centrifuged absorption capacity in combination with high absorption under load at high load, and acceptable levels of residuals. These water-absorbent resin particles provide superior performance when incorporated into absorbent structures.
    Type: Grant
    Filed: August 11, 1995
    Date of Patent: May 13, 1997
    Assignee: The Dow Chemical Company
    Inventors: Josef H. Burgert, Stephen B. Christensen, Herbert A. Gartner, Fredric L. Buchholz, Thomas C. Johnson, Andrew T. Graham
  • Patent number: 5447727
    Abstract: The subject invention provides a surface-crosslinked water-absorbent polymer having improved properties. The subject invention further pertains to a process for preparing such a polymer. Through the use of a preferred primary crosslinking agent coupled with surface crosslinking, desirable absorptive properties are achieved. Suitable primary crosslinking agents include methylenebisacrylamide, bis(acrylamido)acetic acid and its salts, allyl acrylate, allyl methacrylate and esters or amides having both a vinyl and an allyl functionality.
    Type: Grant
    Filed: October 14, 1992
    Date of Patent: September 5, 1995
    Assignee: The Dow Chemical Company
    Inventor: Andrew T. Graham
  • Patent number: 5385983
    Abstract: The subject invention provides a process for preparing a water-absorbent polymer by the addition of a surface crosslinking agent to a hydrogel. In particular, the subject invention provides a process for preparing a water-absorbent polymer by the addition of a surface crosslinking agent to a hydrogel in the absence of a surfactant.
    Type: Grant
    Filed: November 12, 1992
    Date of Patent: January 31, 1995
    Assignee: The Dow Chemical Company
    Inventor: Andrew T. Graham
  • Patent number: 5342899
    Abstract: A process is described for recycling dry aqueous fluid absorbent polymer fines into a process that includes a polymerization step for making the aqueous fluid absorbent polymer. The process requires recovering the dry polymer fines, mixing the fines with a polymerizable monomer solution for making the aqueous fluid absorbent polymer and polymerizing the mixture of fines and monomer to form the aqueous fluid absorbent polymer. In the process the fines are incorporated into the new polymer gel and becomes indistinguishable therefrom. The gel may then comminuted into a particulate dried and then separated into a portion having a desired minimum particle size in a fines portion having less than the desired size. The fines portion is then recycled up to about 30 percent by weight based on gel solids may be recycled for the preferred polyacrylate based aqueous fluid absorbent polymer.
    Type: Grant
    Filed: May 16, 1991
    Date of Patent: August 30, 1994
    Assignee: The Dow Chemical Company
    Inventors: Andrew T. Graham, Herbert Gartner