Patents by Inventor Stephen A. Spearman

Stephen A. Spearman 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 purification and isolation of diaminophenylindane
    Patent number: 4454347
    Abstract: Crystalline 5(6)-amino-1-(4-aminophenyl)-1,3,3-trimethylindane is made by crystallizing the diamino reaction mass from a toluene/heptane solution. The material has been previously purified through a combination of acetic acid washing and treatment with acidic clay. The diamino material, also known as DAPI, is a potential stabilizer, curing agent, and one of the monomers used to produce a polyimide resin.
    Type: Grant
    Filed: February 11, 1983
    Date of Patent: June 12, 1984
    Assignee: Ciba-Geigy Corporation
    Inventors: Marc E. Parham, Stephen A. Spearman, Gleason O. Cookson