Patents by Inventor Thomas Stährfeldt

Thomas Stährfeldt 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: 6504043
    Abstract: The present invention relates to a process for preparing a colour-stable, aqueous dimethylaminoacetonitrile solution from a formaldehyde source, dimethylamine and hydrocyanic acid, wherein the reaction mixture contains 2,4-diamino-6-phenyl-1,3,5-triazine(benzoguanamine) in a concentration of from 0.001 to 5% by weight, based on formaldehyde, prior to the reaction and the starting substances are used stoichiometrically or in a ratio of 0.98-1.02 mol of formaldehyde and 0.95-1.10 mol of dimethylamine per mol of hydrocyanic acid. The resulting product remains colour-stable without a further purification step even after prolonged storage.
    Type: Grant
    Filed: March 5, 2001
    Date of Patent: January 7, 2003
    Assignee: Clariant GmbH
    Inventors: Rainer Fell, Götz Wilbert, Thomas Stährfeldt
  • Patent number: 6420461
    Abstract: The present invention relates to novel compounds of the formula (III) in which the substituents are as defined in the description, to a process for their preparation and to mixtures with other compounds. The compounds of the formula (III) are suitable for stabilizing organic material against the effect of light and heat.
    Type: Grant
    Filed: November 12, 1999
    Date of Patent: July 16, 2002
    Assignee: Clariant GmbH
    Inventors: Thomas Stährfeldt, Mathias Mehrer, Matthias Zäh, Gerhard Pfahler
  • Patent number: 6225385
    Abstract: The present invention relates to a stabilizer mixture prepared by partially condensing PCl3 with 2,2′-dimethyl-4,4′-dihydroxy-5,5′-di-tert-butyldiphenyl sulfide, where the phosphorus content is from 2 to 4% by weight and the content of 2,2′-dimethyl-4,4′-dihydroxy-5,5′-di-tert-butyldiphenyl sulfide is from 0.5 to 50% by weight. The stabilizer mixture has very good solubility in organic solvents and in the polymer and has very good stabilizing action.
    Type: Grant
    Filed: March 19, 1999
    Date of Patent: May 1, 2001
    Assignee: Clariant GmbH
    Inventors: Thomas Stährfeldt, Alexander Lichtblau, Gerhard Pfahler, Karl Gaa
  • Patent number: 6194493
    Abstract: The present invention relates to the use of compounds of the formula (I) where the substituents are as defined in the description as a stabilizer for organic material against the harmful effect of light, oxygen and heat.
    Type: Grant
    Filed: September 3, 1998
    Date of Patent: February 27, 2001
    Assignee: Clariant GmbH
    Inventors: Thomas Stährfeldt, Mathias Mehrer