Patents by Inventor David J. Hasler

David J. Hasler 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: 4264412
    Abstract: Fibre recovery process for pressure-sensitive carbonless copying paper which comprises defibrating the wastage in aqueous media, preferably in the presence of a cationic quaternary ammonium surface active agent, treating the wastage with acid to destroy the microcapsules, and bleaching the defibrated wastage with a bleaching agent.
    Type: Grant
    Filed: May 22, 1979
    Date of Patent: April 28, 1981
    Assignee: The Wiggins Teape Group Limited
    Inventors: David J. Hasler, Peter Sinclair, Eileen H. Burns
  • Patent number: 4105823
    Abstract: A method of encapsulating finely divided particulate material, such as minute droplets of a water-immiscible liquid, to produce microcapsules in which the particulate material is surrounded by polymeric shells, comprising the steps of forming a dispersion of the particulate material in an aqueous medium containing a water-soluble ureaformaldehyde precondensate, a water-soluble melamineformaldehyde precondensate and a water-soluble polymer which is capable of being cross-linked by said precondensates, and condensing said precondensates by acid catalysis with resultant cross-linking of the polymer about the particulate material so as to form the polymeric shells. The polymer may be a cellulose derivative, starch, a starch derivative, a polyacid, a polyester, a polyanhydride copolymer, a polyacrylamide or a polyacrylamide copolymer, and is preferably an acrylamide/acrylic acid copolymer.
    Type: Grant
    Filed: November 15, 1976
    Date of Patent: August 8, 1978
    Assignee: Wiggins Teape Limited
    Inventors: David J. Hasler, Thomas A. McGhee