Patents by Inventor Manfred Ehlert

Manfred Ehlert 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: 5288923
    Abstract: A process for the preparation of hydroxyalkyl ethers of diphenols is disclosed. Accordingly, aromatic polycarbonate resin is reacted with alkylene diol in the presence of a basic catalyst, at temperatures of 150.degree. to 250.degree. C. at a molar ratio of 514 10 moles of alkylene diol to 1 mole of aromatic carbonate structural units to produce the corresponding hydroxyalkyl ether. Additional embodiments entail optional reactions of the aromatic polycarbonate with cyclic alkylene carbonate and with open chain monomeric bis-(hydroxyalkyl)-carbonate. Aromatic polycarbonate waste may thus be advantageously recycled.
    Type: Grant
    Filed: January 29, 1993
    Date of Patent: February 22, 1994
    Assignee: Bayer Aktiengesellschaft
    Inventors: Gerhard Fennhoff, Wolfgang Jacob, Manfred Ehlert
  • Patent number: 5214072
    Abstract: A process for the purification of waste of thermoplastic resins containing at least one member selected from among aromatic polycarbonates, aromatic polyester carbonates and aromatic polyesters and at least one of aluminum, lacquers and dyes which waste accumulates in the production of optical moldings is disclosed. The process which entails size reduction of the waste, chemical wash and filtering steps yields purified resins suitable for thermoplastic processing.
    Type: Grant
    Filed: October 8, 1992
    Date of Patent: May 25, 1993
    Assignee: Bayer Aktiengesellschaft
    Inventors: Gerhard Fennhoff, Wolfgang Jakob, Manfred Ehlert
  • Patent number: 5151452
    Abstract: A process is disclosed for the purification of lacquer-and optionally dye and metal- containing waste of thermoplastic aromatic polycarbonates and/or thermoplastic aromatic polyester carbonates. The waste which result upon the production of moldings, such as audio compact discs, lenses for spectacles or head-lamp reflectors is processed in accordance with the invention to yield useful resin suitable for reprocessing as a molding resin. In accordance with the process, the waste is first size-reduced and then heated with acid to the reflux temperature while stirring. After a water wash there is followed a drying step. In accordance with the process, in instances where the waste does not originally contain metal, the metal in powder form is added before the acid treatment.
    Type: Grant
    Filed: September 17, 1991
    Date of Patent: September 29, 1992
    Assignee: Bayer Aktiengesellschaft
    Inventors: Gerhard Fennhoff, Wolfgang Jakob, Manfred Ehlert, Dieter Freitag