Patents by Inventor David C. K. Chang

David C. K. Chang 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: 6689457
    Abstract: The present invention provides compositions comprising a graphite, binder precursor and low polarity solvent that upon hardening form layers of an electrically conductive material. The compositions of the present invention are sprayable by an internally charged electrostatic sprayer.
    Type: Grant
    Filed: October 17, 2001
    Date of Patent: February 10, 2004
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: David C. K. Chang, Monica A. Pickett, Debra Feldman Singer, Aleksandr Sorser, Debra Sue Strickland
  • Patent number: 5955532
    Abstract: This invention is directed to an aqueous coating composition containing about 40-90% by weight, based on the weight of the coating composition, of an aqueous carrier and 10-60% by weight, based on the weight of the coating composition, of a binder of(a) about 50 to 98%, based on the weight of the binder, of a crosslinked graft copolymer comprising:(i) 2 to 98%, based on the weight of the graft copolymer, of a polymeric backbone of polymerized mono ethylenically unsaturated monomers and 0.5-10.
    Type: Grant
    Filed: July 17, 1997
    Date of Patent: September 21, 1999
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: David C.K. Chang, Michael Fryd
  • Patent number: 5104922
    Abstract: A stable waterborne high solids metallic flake pigment dispersion containing an aqueous carrier, film forming binder and metallic flake pigment and having a solids content of about 40-90% by weight; wherein the film forming polymer is a phosphated acrylic polymer neutralized with ammonia or a primary, secondary or tertiary amine and contains metallic flake pigments in a pigment to binder weight ratio of about 30/100-1000/100 and is non-reactive with the binder and the dispersion has a pH of about 7-9.
    Type: Grant
    Filed: October 22, 1990
    Date of Patent: April 14, 1992
    Assignee: E. I. Du Pont de Nemours and Company
    Inventor: David C. K. Chang
  • Patent number: 5100735
    Abstract: An improved process for forming a multilayer finish on a substrate by applying a layer of a waterborne basecoating composition to the substrate, at least partially drying the coating, applying a layer of a solvent based high solids clear coating to the basecoating and curing the coatings; the improvement that is used therewith is as follows:A. a waterborne basecoating composition that has a film forming binder of an acrylic polymer neutralized with ammonia, a primary amine or a secondary amine without the presence of a tertiary amine a water dispersible or water dilutable alkylated melamine formaldehyde resin and the composition contains pigments in a pigment to binder weight ratio of about 0.5/100 to 200/100;B. a high solids solvent based clear coating composition having a film forming binder of an acrylic polymer, a polyester or a polyesterurethane and an alkylated melamine formaldehyde crosslinking agent and about 0.
    Type: Grant
    Filed: July 25, 1990
    Date of Patent: March 31, 1992
    Assignee: E. I. Du Pont de Nemours and Company
    Inventor: David C. K. Chang
  • Patent number: 4812506
    Abstract: A blocked acid catalyst of an aromatic sulfonic acid blocked with amino methyl propanol and coating compositions containing the blocked acid catalyst.
    Type: Grant
    Filed: May 15, 1987
    Date of Patent: March 14, 1989
    Assignee: E. I Du Pont De Nemours and Company
    Inventors: Thomas C. Gilmer, David C. K. Chang
  • Patent number: 4731290
    Abstract: An improved process for applying a multilayer finish on a primer coated substrate by using a guide coating composition that is applied over the primer of the substrate and then a water borne base coating composition containing metallic pigments and a clear coating composition are applied; before the base coating composition is applied, the guide coating composition is dried at ambient temperatures or at elevated temperatures but not fully cured or crosslinked; the guide coating contains a polymeric latex in an aqueous carrier, preferably an acrylic latex, and optionally, a crosslinking agent and metallic flake pigments; the process improves the appearance, particularly head-on-brightness of water borne basecoat/clear coat finishes in which the base coat contains metallic flake pigments.
    Type: Grant
    Filed: September 11, 1986
    Date of Patent: March 15, 1988
    Assignee: E. I. Du Pont de Nemours and Company
    Inventor: David C. K. Chang