Patents by Inventor Hershel B. Prindle

Hershel B. Prindle 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).

  • Epoxy resins cured with salicyloyl hydrocarbylamines
    Patent number: 4410681
    Abstract: Epoxy resins are cured with salicyloyl hydrocarbyl amines such as N,N'-disalicyloyl-1,2-propylenediamine. The cured resins have an improvement in one or more properties such as color, tensile strength and flexural strength or improved pot life when compared to amine curing agents such as methylene dianiline.
    Type: Grant
    Filed: March 22, 1982
    Date of Patent: October 18, 1983
    Assignee: The Dow Chemical Company
    Inventor: Hershel B. Prindle
  • Preparation of phenolphthalein using cation exchange resins and aryl phosphites
    Patent number: 4252725
    Abstract: A process for the preparation of phenol-phthalein wherein phenol and phthalic anhydride are reacted in the presence of a crosslinked sulfonic cation exchange resin in the acid form and wherein the water content of the reaction mixture is reduced by the use of aryl phosphites.The sulfonic cation exchange resin can be in the macroporous form or in the gel form. The range of useful crosslinking is 4-40 percent for the macroporous resin and 2-16 percent for the gel resin.
    Type: Grant
    Filed: March 9, 1979
    Date of Patent: February 24, 1981
    Assignee: The Dow Chemical Company
    Inventors: Hershel B. Prindle, George E. Ham