Patents by Inventor John W. Richter

John W. Richter 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).

  • Reducing surface tension with N-type betaines of 2-hydroxyl-1,1,2,3,3-pentahydroperfluoroalkylamines
    Patent number: 4388212
    Abstract: Amphoteric N-type betaines represented by the formula: ##STR1## wherein R.sub.1 is C.sub.4 -C.sub.20 perfluoroalkyl;R.sup.1 and R.sup.2 are methyl or, together with the N atom to which they are bonded, form a piperidino, morpholino, or N-alkyl (C.sub.1 -C.sub.4)piperazino group; and m is a whole number between 1 and 4 are highly effective in reducing the surface tension of water and of aqueous solutions of inorganic electrolytes, and can be used in environments where non-amphoteric surfactants would fail, e.g. highly acidic oil well applications.
    Type: Grant
    Filed: May 6, 1981
    Date of Patent: June 14, 1983
    Assignee: E. I. Du Pont de Nemours & Co.
    Inventor: John W. Richter
  • N-type betaines of 2-hydroxy-1,1,2,3,3-pentahydroperfluoroalkylamines
    Patent number: 4283533
    Abstract: Amphoteric N-type betaines represented by the formula: ##STR1## wherein: R.sub.f is C.sub.4 -C.sub.20 perfluoroalkyl;R.sup.1 and R.sup.2 are methyl or, together with the N atom to which they are bonded, form a piperidino, morpholino, orN-alkyl(c.sub.1 -C.sub.4)piperazino group; and m is a whole number between 1 and 4 are highly effective in reducing the surface tension of water and of aqueous solutions of inorganic electrolytes, and can be used in environments where non-amphoteric surfactants would fail, e.g. highly acidic oil well applications.
    Type: Grant
    Filed: November 9, 1979
    Date of Patent: August 11, 1981
    Assignee: E. I. Du Pont de Nemours and Company
    Inventor: John W. Richter
  • Aromatic polyimide, polyester and polyamide separation membranes
    Patent number: RE30351
    Abstract: Gas separation membranes are made from aromatic polyimides, polyesters and polyamides in which the repeating unit of the main polymer chain(a) has at least one rigid divalent subunit, the two main chain single bonds extending from which are not colinear,(b) is sterically unable to rotate 360.degree. around at least one of these bonds, and(c) has 50% or more of its main chain atoms as members of aromatic rings.
    Type: Grant
    Filed: May 18, 1976
    Date of Patent: July 29, 1980
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: Harvey H. Hoehn, John W. Richter