Patents by Inventor Klaus-Dieter Hellwig

Klaus-Dieter Hellwig 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: 6921781
    Abstract: The present invention provides a process, which includes: coating at least a portion of a surface of at least one silica particle with at least one wax, wherein the coating is carried out in at least one gas at a temperature above the melting point of the wax and below the decomposition temperature of the wax, to obtain at least one wax-coated silica particle. Other embodiments of the present invention provides processes for impregnating the silica particle with wax and uses of the wax-coated or wax-impregnated particles.
    Type: Grant
    Filed: August 23, 2001
    Date of Patent: July 26, 2005
    Assignee: Degussa AG
    Inventors: Juergen Schubert, Klaus-Dieter Hellwig, Michael Pickel, Hans-Dieter Puetz
  • Patent number: 6800267
    Abstract: Aluminum-doped precipitated silicas having a BET surface area of more than 300 m2/g and aluminum distributed uniformly in the silica particles are prepared by sequentially heating a mixture of water and sodium silicate at a temperature of from 70 to 86° C. and adding sulfuric acid until half of the sodium silicate is neutralized, then aging the mixture for a time of from 30 to 120 minutes, adjusting the pH of the mixture with sulfuric acid to a range of from 3.0 to 7.0, thereby precipitating the aluminum-doped silica, filtering the aluminum-doped silica from the mixture to form a filtercake and washing the filtercake, followed by drying and/or grinding the washed filtercake. An aluminum salt solution is metered into the mixture at step a) and/or step c). The aluminum-doped precipitated silicas of the present invention may be used in coatings for paper and other media intended for ink jet printing.
    Type: Grant
    Filed: August 29, 2001
    Date of Patent: October 5, 2004
    Assignee: Degussa AG
    Inventors: Jürgen Schubert, Klaus-Dieter Hellwig, Astrid Muller
  • Publication number: 20020061404
    Abstract: Aluminum-doped precipitated silicas having a BET surface area of more than 300 m2/g and aluminum distributed uniformly in the silica particles are prepared by sequentially heating a mixture of water and sodium silicate at a temperature of from 70 to 86° C. and adding sulfuric acid until half of the sodium silicate is neutralized, then aging the mixture for a time of from 30 to 120 minutes, adjusting the pH of the mixture with sulfuric acid to a range of from 3.0 to 7.0, thereby precipitating the aluminum-doped silica, filtering the aluminum-doped silica from the mixture to form a filtercake and washing the filtercake, followed by drying and/or grinding the washed filtercake. An aluminum salt solution is metered into the mixture at step a) and/or step c). The aluminum-doped precipitated silicas of the present invention may be used in coatings for paper and other media intended for ink jet printing.
    Type: Application
    Filed: August 29, 2001
    Publication date: May 23, 2002
    Applicant: Degussa Ag
    Inventors: Juergen Schubert, Klaus-Dieter Hellwig, Astrid Mueller
  • Publication number: 20020055556
    Abstract: The present invention provides a process, which includes:
    Type: Application
    Filed: August 23, 2001
    Publication date: May 9, 2002
    Inventors: Juergen Schubert, Klaus-Dieter Hellwig, Michael Pickel, Hans-Dieter Puetz
  • Patent number: 4536383
    Abstract: A method for the preparation of alkali metal selenates through oxidation of powdered selenium with hydrogen peroxide and neutralization of the formed selenic acid with alkali metal hydroxide or alkali metal carbonate, wherein the selenium oxide in the first step is brought to reaction at the surface of a warmed portion of hydrogen peroxide and subsequently in a second step the resulting acid solution is partially neutralized and the remaining selenite is further converted with hydrogen peroxide to the selenate.
    Type: Grant
    Filed: October 3, 1984
    Date of Patent: August 20, 1985
    Assignee: Degussa Aktiengesellschaft
    Inventors: Lothar Kaufmann, Klaus-Dieter Hellwig