Patents by Inventor Valdis Ansis Augstkalns

Valdis Ansis Augstkalns 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 of preparing high molecular weight polyamide with recovery of diamine and return of same to polymerization system
    Patent number: 3937686
    Abstract: In the preparation of high molecular weight polyamides, vaporization of the organic diamine employed results in its loss. The effect of the loss can be reduced by collecting the vapor given off during the evaporation and/or polymerization steps, condensing it, passing the condensate through a selected ion-exchange resin, and obtaining the diamine by contacting the resin with either a strong inorganic acid or an aqueous solution of an organic dicarboxylic acid used in making high molecular weight polyamides depending upon the resin employed. When the diacid is used, the salt so obtained can be used in preparing high molecular weight polyamides.
    Type: Grant
    Filed: January 10, 1974
    Date of Patent: February 10, 1976
    Assignee: C/O E. I. Du Pont de Nemours & Co.
    Inventor: Valdis Ansis Augstkalns