Patents by Inventor Bappalige N. Achar

Bappalige N. Achar 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).

  • Patent number: 4649189
    Abstract: Imide-linked bisphthalonitrile compounds are prepared by combining a dicyano aromatic diamine and an organic dianhydride to produce an amic acid linked bisphthalonitrile copound. The amic acid linked bisphthalonitrile compound is dehydrocyclized to produce the imide-linked bisphthalonitrile compounds. The imide-linked bisphthalonitrile compounds may be polymerized to produce a phthalocyanine polymer by heating the imide-linked bisphthalonitrile compound, either alone or in the presence of a metal powder or a metal salt. These compounds are useful in the coating, laminating and molding arts. The polymers are useful in composite matrix resins where increased fire resistance, toughness and resistance to moisture are required, particularly as secondary structures in aircraft and spacecraft.
    Type: Grant
    Filed: July 12, 1985
    Date of Patent: March 10, 1987
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Bappalige N. Achar, George M. Fohlen, John A. Parker
  • Patent number: 4537834
    Abstract: Metal, preferably divalent copper, cobalt or nickel, phthalocyanine tetraamines are used as curing agents for epoxides. The resulting copolymers have high thermal and chemical resistance and are homogeneous. They are useful as binders for laminates, e.g. graphite cloth laminate.
    Type: Grant
    Filed: April 11, 1984
    Date of Patent: August 27, 1985
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Bappalige N. Achar, George M. Fohlen, John A. Parker
  • Patent number: 4522755
    Abstract: Metal 4, 4', 4", 4"'-tetracarboxylic phthalocyanines (MPTC) are prepared by reaction of trimellitic anhydride, a salt or hydroxide of the desired metal (or the metal in powdered form), urea and a catalyst. A purer form of MPTC is prepared than heretofore. These tetracarboxylic acids are then polymerized by heat to sheet polymers which have superior heat and oxidation resistance. The metal is preferably a divalent metal having an atomic radius close to 1.35.ANG..
    Type: Grant
    Filed: September 15, 1983
    Date of Patent: June 11, 1985
    Assignee: The United States of America as represented by the United States National Aeronautics and Space Administration
    Inventors: Bappalige N. Achar, George M. Fohlen, John A. Parker
  • Patent number: 4499260
    Abstract: Method of forming 4,4',4",4'"-tetraamino phthalocyanines by reducing 4,4',4",4'"-tetranitro phthalocyanines, polymerization of the metal tetraamino phthalocyanines with a tetracarboxylic dianhydride (preferably aromatic) or copolymerization with a tetracarboxylic dianhydride and a diamine (preferably also aromatic) to produce amic acids which are then dehydrocyclized to imides. Thermally and oxidatively stable polymers result which form tough, flexible films, etc.
    Type: Grant
    Filed: November 10, 1982
    Date of Patent: February 12, 1985
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Bappalige N. Achar, George M. Fohlen, John A. Parker
  • Patent number: 4450268
    Abstract: The invention relates to metal, primarily divalent metal such as divalent copper, cobalt and nickel, 4,4',4", 4'" phthalocyanine tetracarboxylic acids and to polymers prepared by heating the same, and to a method of preparing the tetracarboxylic acids.A method is provided for preparing the aforesaid tetracarboxylic acids in purer form than heretofore. Upon heating these acids decarboxylate and produce polymers.These polymers have diphenyl (conjugated) types of linkage; they are thermally and oxidatively stable and useful as sheet polymers for various purposes such as heat shielding.The monomeric tetracarboxylic acid is shown in FIG. 1, the polymer in FIG. 2 and thermal resistance in FIG. 3.The monomeric tetracarboxylic acids are prepared in purer form than heretofore, the resulting polymers are more stable thermally and oxidatively than metal phthalocyanine polymers and monomers heretofore made.
    Type: Grant
    Filed: September 8, 1982
    Date of Patent: May 22, 1984
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Bappalige N. Achar, George M. Fohlen, John A. Parker