Patents by Inventor Joachim Stedefeder

Joachim Stedefeder 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).

  • Manufacture of paper having a high dry strength and a low wet strength
    Patent number: 4294873
    Abstract: A process for the manufacture of paper having a high dry strength and a low wet strength, by treating the surface of the paper with an aqueous solution of an alkali metal and/or alkaline earth metal salt of a polymer of (a) from 91 to 100% by weight of acrylic acid and/or methacrylic acid and (b) from 0 to 9% by weight of acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinyl acetate, maleic anhydride, diisobutylene, an ester of acrylic acid and/or an ester of methacrylic acid, which has a viscosity of from 5 to 100 mPas in 2% strength aqueous solution at 20.degree. C., and drying the impregnated paper. The polymer is generally employed in an amount of from 1 to 4% by weight, based on dry paper, and increases the dry strength of the paper without substantially increasing the wet strength.
    Type: Grant
    Filed: January 3, 1980
    Date of Patent: October 13, 1981
    Assignee: BASF Aktiengesellschaft
    Inventors: Juergen Hartmann, Joachim Stedefeder, Walter Denzinger, Sigberg Pfohl
  • Water-soluble alkaline earth metal salts of polymers of acrylic acid, and their use as sizes
    Patent number: 4167485
    Abstract: A process for sizing staple fiber yarns by applying an aqueous sizing liquor which contains an alkaline earth metal salt of a copolymer containing from 90 to 30% by weight of acrylic acid and/or methacrylic acid and from 10 to 70% by weight of acrylonitrile and/or methacrylonitrile, which copolymer has a viscosity of from 50 to 1,000 cp in 15% strength aqueous solution at 85.degree. C., and drying the treated yarns. The sized films obtained are moisture-insensitive and have good heat stability.
    Type: Grant
    Filed: March 28, 1978
    Date of Patent: September 11, 1979
    Assignee: BASF Aktiengesellschaft
    Inventors: Wolfgang Schenk, Joachim Stedefeder, Heinz Leitner, Hans-Uwe Schenck
  • Process for preparing polymers in powder form
    Patent number: 4135043
    Abstract: Polymers in powder form are manufactured by polymerizing water-soluble ethylenically unsaturated monomers, which form hydrophilic polymers, in a powder bed of polymers of water-soluble ethylenically unsaturated compounds in the presence of polymerization initiators and water as an auxiliary liquid, the water being entirely or partially removed from the polymerization zone by evaporation during the polymerization.
    Type: Grant
    Filed: August 1, 1977
    Date of Patent: January 16, 1979
    Assignee: BASF Aktiengesellschaft
    Inventors: Bernd Kast, Joachim Stedefeder, Axel Sanner, Hans-Uwe Schenck, Richard Thoma, Hermann Fischer
  • Purification of copolymers containing crotonic acid
    Patent number: 4086413
    Abstract: Copolymers of crotonic acid are purified, to remove monomeric crotonic acid, by extracting the copolymers with water at from 50.degree. to 120.degree. C and stirring the system, the flow energy of the water and the energy of stirring being chosen so that the polymer particles just remain suspended.
    Type: Grant
    Filed: May 2, 1977
    Date of Patent: April 25, 1978
    Assignee: BASF Aktiengesellschaft
    Inventors: Joachim Stedefeder, Ingo H. Dorn, Horst Kuhn, Walter Kastenhuber, Wolfgang Linke