Patents by Inventor David Holroyd

David Holroyd 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).

  • Production of paper and paper board
    Patent number: 4913775
    Abstract: Paper or paper board is made by passing an aqueous cellulosic suspension through a centriscreen or other shear device and then draining the purified suspension, and an improved combination of retention, drainage, drying and formation is achieved by adding to the suspension an excess of high molecular weight linear synthetic cationic polymer before shearing the suspension and adding bentonite after shearing.
    Type: Grant
    Filed: June 27, 1988
    Date of Patent: April 3, 1990
    Assignee: Allied Colloids Ltd.
    Inventors: John Langley, David Holroyd
  • Production of paper and paperboard
    Patent number: 4753710
    Abstract: Paper or paper board is made by passing an aqueous cellulosic suspension through a centriscreen or other shear device and then draining the purified suspension, and an improved combination of retention, drainage, drying and formation is achieved by adding to the suspension an excess of high molecular weight linear synthetic cationic polymer before shearing the suspension and adding bentonite after shearing.
    Type: Grant
    Filed: January 27, 1987
    Date of Patent: June 28, 1988
    Assignee: Allied Colloids Limited
    Inventors: John Langley, David Holroyd