Patents by Inventor Raj D. Patel

Raj D. Patel 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: 5344738
    Abstract: A process for the preparation of toner compositions with a volume median particle size of from about 1 to about 25 microns, which process comprises:(i) preparing by emulsion polymerization an anionic charged polymeric latex of submicron particle size, and comprised of resin particles and anionic surfactant;(ii) preparing a dispersion in water, which dispersion is comprised of optional pigment, an effective amount of cationic flocculant surfactant, and optionally a charge control agent;(iii) shearing the dispersion (ii) with the polymeric latex thereby causing a flocculation or heterocoagulation of the formed particles of optional pigment, resin and charge control agent to form a high viscosity gel in which solid particles are uniformly dispersed;(iv) stirring the above gel comprised of latex particles, and oppositely charged dispersion particles for an effective period of time to form electrostatically bound relatively stable toner size aggregates with narrow particle size distribution; and(v) heating the ele
    Type: Grant
    Filed: June 25, 1993
    Date of Patent: September 6, 1994
    Assignee: Xerox Corporation
    Inventors: Grazyna E. Kmiecik-Lawrynowicz, Raj D. Patel, Michael A. Hopper
  • Patent number: 5302486
    Abstract: A process for the preparation of an encapsulated toner composition comprised of a core and a shell thereover, which process comprises mixing an organic phase comprised of an olefinic monomer, pigment, and a first resin A soluble in the organic phase; dispersing the organic phase into microdroplets in an aqueous solution comprised of a surfactant; subjecting the resulting mixture to free radical polymerization by heating wherein the olefinic monomer is converted to a second resin B; and wherein said resin B is incompatible with said resin A and phase separates whereby a core and shell results.
    Type: Grant
    Filed: April 17, 1992
    Date of Patent: April 12, 1994
    Assignee: Xerox Corporation
    Inventors: Raj D. Patel, Guerino G. Sacripante, Grazyna Kmiecik-Lawrynowicz
  • Patent number: 5290654
    Abstract: A process for the preparation of toner compositions which comprises dissolving a polymer, and optionally a pigment in an organic solvent; dispersing the resulting solution in an aqueous media containing a surfactant, or mixture of surfactants; stirring the mixture with optional heating to remove the organic solvent thereby obtaining suspended particles of about 0.05 micron to about 2 microns in volume diameter; subsequently homogenizing the resulting suspension with an optional pigment in water and surfactant; followed by aggregating the mixture by heating thereby providing toner particles with an average particle volume diameter of from between about 3 to about 21 microns when said pigment is present.
    Type: Grant
    Filed: July 29, 1992
    Date of Patent: March 1, 1994
    Assignee: Xerox Corporation
    Inventors: Guerino G. Sacripante, James M. Duff, Grazyna Kmiecik-Lawrynowica, Raj D. Patel
  • Patent number: 5283153
    Abstract: A process for the preparation of encapsulated toner compositions which comprises dispersing a mixture of addition monomers, an optional preformed polymer resin, a free radical initiator, a colorant comprised of a pigment, dye or mixtures thereof, and shell forming monomer in an aqueous medium containing a cellulose polymer and a first ionic surfactant thereby forming a stable microdroplet suspension; and subsequently adding an aqueous solution of a second stabilizing surfactant followed by the formation of a soluble monomer forming shell wall by interfacial polymerization, and thereafter initiating and completing the core resin-forming free radical polymerization by heating thereby resulting in toner compositions with an average volume particle size of from about 3 to about 7 microns.
    Type: Grant
    Filed: April 15, 1992
    Date of Patent: February 1, 1994
    Assignee: Xerox Corporation
    Inventors: Guerino G. Sacripante, Grazyna E. Kmiecik-Lawrynowicz, Hock S. Tan, Raj D. Patel
  • Patent number: 5223370
    Abstract: An encapsulated toner composition and process thereof, which toner is comprised of a core comprised of a polymer resin or resins, color pigment, dye, or mixtures thereof, and thereover an inner shell resin comprised, for example, of a polyurea, and thereover an outer shell coating comprised of an alkyl cellulose. The colored encapsulated toners are useful in reprographic processes wherein, for example, low gloss is desired.
    Type: Grant
    Filed: December 6, 1991
    Date of Patent: June 29, 1993
    Assignee: Xerox Corporation
    Inventors: Guerino G. Sacripante, Raj D. Patel, Grazyna Kmiecik-Lawrynowicz, Hock S. Tan, Walter Mychajlowskij
  • Patent number: 5213938
    Abstract: A process for the preparation of toner compositions which comprises the oxidation and metal chelation of the surface thereof; and a process for the preparation of toners which comprises the oxidation and metal chelation of the surface thereof, and subsequently coalescence by the absorption or sticking thereto of a fluoro containing polymer.
    Type: Grant
    Filed: April 15, 1992
    Date of Patent: May 25, 1993
    Assignee: Xerox Corporation
    Inventors: Guerino G. Sacripante, Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz, Lurdes M. Martins
  • Patent number: 4727011
    Abstract: An improved process for the preparation of encapsulated toner compositions which comprises mixing in the absence of solvent a core monomer, an initiator, pigment particles, a first shell monomer, stabilizer, and water; thereafter adding a second shell monomer thereby enabling an interfacial polymerization reaction between the first, and second shell monomers; and subsequently affecting a free radical polymerization of the core monomer.
    Type: Grant
    Filed: October 16, 1986
    Date of Patent: February 23, 1988
    Assignee: Xerox Corporation
    Inventors: Hadi K. Mahabadi, Raj D. Patel, Steve W. Webb, Joseph D. Wright