Patents by Inventor Ralph Stevens

Ralph Stevens 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).

  • Process for preparing polycarbonate
    Patent number: 6555646
    Abstract: A process for quenching a catalyst used in the manufacture of polycarbonate by melt polycondensation of a dihydroxy compound and a diester. The process includes adding a quencher composition to an intermediate polycarbonate to deactivate residual catalyst. The quencher composition includes a compound having at least one sulfonic acid group and at least one amino group.
    Type: Grant
    Filed: August 30, 2001
    Date of Patent: April 29, 2003
    Assignee: General Electric Company
    Inventors: Andre Volkers, Marcel Puyn, Ralph Stevens
  • PROCESS FOR PREPARING POLYCARBONATE
    Publication number: 20030055202
    Abstract: A process for quenching a catalyst used in the manufacture of polycarbonate by melt polycondensation of a dihydroxy compound and a diester. The process includes adding a quencher composition to an intermediate polycarbonate to deactivate residual catalyst. The quencher composition includes a compound having at least one sulfonic acid group and at least one amino group.
    Type: Application
    Filed: August 30, 2001
    Publication date: March 20, 2003
    Inventors: Andre Volkers, Marcel Puyn, Ralph Stevens