Patents by Inventor Phyllis C. Leithem

Phyllis C. Leithem 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 acid sulfite digestion of wood
    Patent number: 4295929
    Abstract: The production of chemical pulp by the acid sulfite digestion process is improved by increasing the ratio by weight of combined SO.sub.2 to wood to a range of from 4 to 12 (based on one part of combined SO.sub.2 to 100 parts of dry wood) and by increasing the minimum average rate of heating to the substantially maximum cooking temperature to 40.degree. C. per hour.
    Type: Grant
    Filed: March 19, 1980
    Date of Patent: October 20, 1981
    Assignee: International Telephone and Telegraph Corp.
    Inventor: Phyllis C. Leithem
  • Production of cellulose acetate
    Patent number: 4162359
    Abstract: Cellulose acetate is produced by subjecting highly purified cellulosic dissolving pulp to a bleaching sequence including at least one alkaline extraction stage and acetylating the bleached pulp to convert the pulp to cellulose acetate. The yellowness index of the cellulose acetate is reduced by carrying out the alkaline extraction stage in the presence of from 0.2 to 3.3%, based on dry pulp weight, of sodium or hydrogen peroxide.
    Type: Grant
    Filed: March 13, 1978
    Date of Patent: July 24, 1979
    Assignee: International Telephone and Telegraph Corporation
    Inventors: Phyllis C. Leithem, Romeo Conca