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: 5565296
    Abstract: A process for the preparation of polymer compositions which comprises mixing a conductive component with an anionic polymeric latex containing a polymer; adding a cationic surfactant, or flocculant whereby the aggregation of the latex particles and the conductive component particles results; subsequently adding colloidal stabilizer, followed by the addition of a base to obtain a pH of from about 7 to about 12; heating above about the polymer glass transition temperature thereby enabling the severage, or breakage of the formed aggregated particles; further heating above about the polymer glass transition temperature enabling the coalescence of the polymer and conductive component particles; and optionally washing and drying the resulting coalesced product.
    Type: Grant
    Filed: July 3, 1995
    Date of Patent: October 15, 1996
    Assignee: Xerox Corporation
    Inventors: Grazyna E. Kmiecik-Lawrynowicz, Richard P. N. Veregin, Raj D. Patel, Michael A. Hopper, Maria V. McDougall
  • Patent number: 5561025
    Abstract: A process for the preparation of polymer latex particles which comprises the emulsion polymerization of a mixture of monomer, polar comonomer, water, surfactant, initiator, and a water phase termination agent, and wherein the water phase termination agent is selected from the group consisting of butanethiol, pentanethiol, hexanethiol, heptanethiol, octanethiol, and carbon tetrabromide (CBr.sub.4).
    Type: Grant
    Filed: July 3, 1995
    Date of Patent: October 1, 1996
    Assignee: Xerox Corporation
    Inventors: Francisco E. Torres, Raj D. Patel, Michael A. Hopper, Grazyna E. Kmiecik-Lawrynowicz
  • Patent number: 5554480
    Abstract: A process for the preparation of fluorescent toner compositions comprising(i) preparing a pigment dispersion in a solvent, which dispersion is comprised of a pigment or dye, an ionic surfactant and optionally a charge control agent;(ii) shearing the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, a nonionic surfactant and resin particles, thereby causing a flocculation or heterocoagulation of pigment, resin particles and charge control agent to form electrostatically bound toner size aggregates; and(iii) heating the statically bound aggregated particles to form said toner composition comprised of polymeric resin, pigment and optionally a charge control agent, and wherein the pigment or dye is excitable by ultraviolet light in the frequency range of from about 254 to about 366 nanometers and fluoresces in the visible spectrum of from about 400 to about 700 nanometers.
    Type: Grant
    Filed: September 1, 1994
    Date of Patent: September 10, 1996
    Assignee: Xerox Corporation
    Inventors: Raj D. Patel, H. Bruce Goodbrand, Grazyna E. Kmiecik-Lawrynowicz, Michael A. Hopper, Melvin D. Croucher, James M. Duff
  • Patent number: 5536615
    Abstract: A process for the preparation of liquid developers comprising:(i) preparing a pigment dispersion, which dispersion is comprised of a pigment, and an ionic surfactant;(ii) shearing said pigment dispersion with a latex or emulsion blend comprised of a nonionic surfactant, resin, and a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and optionally adding further anionic, or nonionic surfactant to stabilize the aggregates obtained in (iii);(iii) heating the above resulting sheared aqueous blend below about the glass transition temperature (Tg) of the resin to form toner size aggregates with a narrow particle size distribution;(iv) heating said bound aggregates above about the Tg of the resin to form toner size particles in an aqueous medium and which particles possess a narrow particle size distribution; and(v) separating from the aqueous medium toner particles of resin and pigment, and dispersing said toner particles in a carrier fluid.
    Type: Grant
    Filed: July 5, 1995
    Date of Patent: July 16, 1996
    Assignee: Xerox Corporation
    Inventors: Michael A. Hopper, Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz, Peter G. Odell, Bernard Grushkin, George A. Gibson
  • Patent number: 5527658
    Abstract: A process for the preparation of toner comprising:(i) preparing a pigment dispersion comprised of pigment, an ionic surfactant, and optionally a charge control agent;(ii) shearing said pigment dispersion with a latex comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, and a nonionic surfactant;(iii) heating the above sheared blend of (ii) about below the glass transition temperature (Tg) of the resin, to form electrostatically bound toner size aggregates with a volume average diameter of from between about 2 and about 15 microns and with a narrow particle size distribution as reflected in the particle diameter GSD of between about 1.15 and about 1.30, followed by the addition of a water insoluble transition metal containing powder ionic surfactant in an amount of from between about 0.05 and about 5 weight percent based on the weight of the aggregates; and(iv) heating said bound aggregates about above the Tg of the resin to form toner.
    Type: Grant
    Filed: March 13, 1995
    Date of Patent: June 18, 1996
    Assignee: Xerox Corporation
    Inventors: Michael A. Hopper, Raj D. Patel, H. Bruce Goodbrand, Grazyna E. Kmiecik-Lawrynowicz
  • Patent number: 5525452
    Abstract: A process for the preparation of toner compositions comprising (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant, and optionally a charge control agent;(ii) shearing said pigment dispersion with an aqueous latex or emulsion blend comprised of a nonionic surfactant, resin, and a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant;(iii) heating the above sheared blend below about the glass transition temperature (Tg) of the resin to form electrostatically bound toner size aggregates with a narrow particle size distribution;(iv) heating the electrostatically bound aggregates above about the Tg of the resin, which heating is accomplished at a pH of from about 4.0 to about 6.0 while continuously stirring the electrostatically bound aggregates to form toner particles;(v) washing the toner particles with a basic aqueous solution, which solution is of a pH of from between about 10.0 and about 12.
    Type: Grant
    Filed: July 3, 1995
    Date of Patent: June 11, 1996
    Assignee: Xerox Corporation
    Inventors: Michael A. Hopper, Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz
  • Patent number: 5514763
    Abstract: A toner composition includes a styrene/butadiene resin having a weight average molecular weight of less than about 70,000 and a number average molecular weight of from about 8,000 to about 12,000, has a glass transition temperature of from about 50.degree. C. to about 60.degree. C. and provides excellent gloss and high fix properties at a low fusing temperature. The styrene/butadiene resin is produced by an emulsion polymerization process that includes forming an emulsion of a surfactant, styrene monomer, butadiene monomer and a water-soluble monomer in water, and then polymerizing the monomers in the presence of a water-soluble initiator.
    Type: Grant
    Filed: September 26, 1994
    Date of Patent: May 7, 1996
    Assignee: Xerox Corporation
    Inventors: Grazyna E. Kmiecik-Lawrynowicz, T. Brian McAneney, Raj D. Patel, Michael A. Hopper, David J. Sanders
  • Patent number: 5501935
    Abstract: A process for the preparation of toner compositions consisting essentially of(i) preparing a pigment dispersion, which dispersion is comprised of a pigment, an ionic surfactant, and optionally a charge control agent;(ii) shearing said pigment dispersion with a latex or emulsion blend comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, and a nonionic surfactant;(iii) heating the above sheared blend below about the glass transition temperature (Tg) of the resin to form electrostatically bound toner size aggregates with a narrow particle size distribution;(iv) subsequently adding further anionic or nonionic surfactant solution to minimize further growth in the coalescence (v); and(v) heating said bound aggregates above about the Tg of the resin and wherein said heating is from a temperature of about 103.degree. to about 120.degree. C., and wherein said toner compositions are spherical in shape.
    Type: Grant
    Filed: January 17, 1995
    Date of Patent: March 26, 1996
    Assignee: Xerox Corporation
    Inventors: Raj D. Patel, Michael A. Hopper, Paul J. Gerroir, Grazyna E. Kmiecik-Lawrynowicz
  • Patent number: 5496676
    Abstract: A process comprising:(i) preparing a pigment dispersion comprised of pigment, ionic surfactant, and optional charge control agent;(ii) mixing at least two resins in the form of latexes, each latex comprising a resin, ionic and nonionic surfactants and optionally a charge control agent, and wherein the ionic surfactant has a countercharge to the ionic surfactant of (i) to obtain a latex blend;(iii) shearing said pigment dispersion with the latex blend of (ii) comprised of resins, counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant;(iv) heating the above sheared blends of (iii) below about the glass transition temperature (Tg) of the resin, to form electrostatically bound toner size aggregates with a narrow particle size distribution; and(v) subsequently adding further anionic surfactant solution to minimize further growth of the bound aggregates (vi);(vi) heating said bound aggregates above about the glass transition temperature Tg of the r
    Type: Grant
    Filed: March 27, 1995
    Date of Patent: March 5, 1996
    Assignee: Xerox Corporation
    Inventors: Melvin D. Croucher, Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz, Michael A. Hopper, Bernard Grushkin
  • Patent number: 5482812
    Abstract: A process for the preparation of toner compositions or toner particles comprising:(i) providing an aqueous pigment dispersion comprised of a pigment, an ionic surfactant, and optionally a charge control agent;(ii) providing a wax dispersion comprised of wax, a dispersant comprised of nonionic surfactant, ionic surfactant or mixtures thereof;(iii) shearing a mixture of the wax dispersion and the pigment dispersion with a latex or emulsion blend comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant;(iv) heating the above sheared blend below about the glass transition temperature (Tg) of the resin to form electrostatically bound toner size aggregates with a narrow particle size distribution;(v) adding additional ionic surfactant to the aggregated suspension of (iv) to ensure that no, or minimal additional particle growth of the electrostatically bound toner size aggregates occurs on further increasing the temperature to co
    Type: Grant
    Filed: November 23, 1994
    Date of Patent: January 9, 1996
    Assignee: Xerox Corporation
    Inventors: Michael A. Hopper, Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz, Stephan V. Drappel, Paul J. Gerroir
  • Patent number: 5418108
    Abstract: A process for the preparation of toner compositions with controlled particle size and selected morphology comprising(i) preparing a pigment dispersion in water, which dispersion is comprised of pigment, ionic surfactant, and optionally a charge control agent;(ii) shearing the pigment dispersion with a polymeric latex comprised of resin of submicron size, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and charge control agent, and generating a uniform blend dispersion of solids of resin, pigment, and optional charge control agent in the water and surfactants;(iii) (a) continuously stirring and heating the above sheared blend to form electrostatically bound toner size aggregates; or(iii) (b) further shearing the above blend to form electrostatically bound well packed aggregates; or(iii) (c) continuously shearing the above blend, while heating
    Type: Grant
    Filed: June 25, 1993
    Date of Patent: May 23, 1995
    Assignee: Xerox Corporation
    Inventors: Grazyna E. Kmiecik-Lawrynowicz, Raj D. Patel
  • Patent number: 5405728
    Abstract: A process for the preparation of toner compositions comprising(i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant and optionally a charge control agent;(ii) shearing the pigment dispersion with a latex containing a controlled solid contents of from about 50 weight percent to about 20 percent of polymer or resin, counterionic surfactant and nonionic surfactant in water, counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and charge control agent to form a dispersion of solids of from about 30 weight percent to 2 percent comprised of resin, pigment and optionally charge control agent in the mixture of nonionic, anionic and cationic surfactants;(iii) heating the above sheared blend at a temperature of from about 5.degree. to about 25.degree. C.
    Type: Grant
    Filed: June 25, 1993
    Date of Patent: April 11, 1995
    Assignee: Xerox Corporation
    Inventors: Michael A. Hopper, Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz
  • Patent number: 5403693
    Abstract: A process for the preparation of toner compositions with controlled particle size comprising:(i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant in amounts of from about 0.
    Type: Grant
    Filed: June 25, 1993
    Date of Patent: April 4, 1995
    Assignee: Xerox Corporation
    Inventors: Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz, Michael A. Hopper
  • Patent number: 5391456
    Abstract: A process for the preparation of toner compositions comprising:(i) forming a dispersion of resin in an aqueous ionic surfactant solution;(ii) preparing pigment dispersions in water of three different pigments each of a dissimilar color, each dispersion being comprised of a pigment dispersed in water and which preparation utilizes nonionic dispersants, and optionally an ionic surfactant;(iii) blending the prepared resin dispersed as a latex with two, or optionally three of the different color pigment dispersions of step (ii);(iv) adding an aqueous solution of counterionic surfactant as a coagulant to the formed resin-pigment blends, while continuously subjecting the mixture to high shear, to induce a homogeneous gel of the flocculated resin-pigments blend;(v) heating the above sheared gel at temperatures between about 20.degree. C. and about 5.degree. C.
    Type: Grant
    Filed: February 28, 1994
    Date of Patent: February 21, 1995
    Assignee: Xerox Corporation
    Inventors: Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz, Michael A. Hopper, Melvin D. Croucher
  • Patent number: 5370963
    Abstract: A process for the preparation of toner compositions with controlled particle size comprising:(i) preparing a pigment dispersion in water, which dispersion is comprised of pigment, an ionic surfactant, and an optional charge control agent;(ii) shearing at high speeds the pigment dispersion with a polymeric latex comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant thereby forming a uniform homogeneous blend dispersion comprised of resin, pigment, and optional charge agent;(iii) heating the above sheared homogeneous blend below about the glass transition temperature (Tg) of the resin while continuously stirring to form electrostatically bounded toner size aggregates with a narrow particle size distribution;(iv) heating the statically bound aggregated particles above about the Tg of the resin particles to provide coalesced toner comprised of resin, pigment, and optional charge control agent, and subsequently optionally ac
    Type: Grant
    Filed: June 25, 1993
    Date of Patent: December 6, 1994
    Assignee: Xerox Corporation
    Inventors: Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz, Michael A. Hopper
  • Patent number: 5370964
    Abstract: A process for the preparation of toner comprising:(i) preparing a pigment dispersion in water, which dispersion is comprised of pigment, an ionic surfactant, and an optional charge control agent;(ii) shearing the pigment dispersion with a polymeric latex comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, and which latex contains a nonionic surfactant thereby forming a homogeneous or a uniform blend;(iii) heating the above sheared homogeneous blend below about the glass transition temperature (Tg) of the resin to form electrostatically bound toner size aggregates;(iv) reshearing the above electrostatically bound toner aggregates (iii) to fragment or break down said toner aggregates of (iii) into smaller average diameter particle size;(v) heating the resulting formed sheared homogeneous blend (iv) comprised of resin, pigment particles, and the ionic, counterionic and nonionic surfactants in water below about the glass transition temperature (T
    Type: Grant
    Filed: November 29, 1993
    Date of Patent: December 6, 1994
    Assignee: Xerox Corporation
    Inventors: Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz, Michael A. Hopper, Melvin D. Croucher, T. Hwee Ng, William J. Dale
  • Patent number: 5366841
    Abstract: A process for the preparation of toner compositions comprising:(i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant and optionally a charge control agent;(ii) shearing the pigment dispersion with a latex blend comprised of resin particles, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and charge control agent to form a uniform dispersion of solids in the water, and surfactant;(iii) heating the above sheared blend at a critical temperature region about equal to or above the glass transition temperature (Tg) of the resin, while continuously stirring, to form electrostatically bounded toner size aggregates with a narrow particle size distribution and wherein said critical temperature is from about 0.degree. C. to about 10.degree. C.
    Type: Grant
    Filed: September 30, 1993
    Date of Patent: November 22, 1994
    Assignee: Xerox Corporation
    Inventors: Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz, Michael A. Hopper, Melvin D. Croucher
  • Patent number: 5364729
    Abstract: A process for the preparation of toner compositions comprising:(i) preparing a pigment dispersion, which dispersion is comprised of a pigment, an ionic surfactant, and optionally a charge control agent;(ii) shearing said pigment dispersion with a latex or emulsion blend comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant;(iii) heating the above sheared blend below about the glass transition temperature (Tg) of the resin, to form electrostatically bound toner size aggregates with a narrow particle size distribution; and(iv) heating said bound aggregates above about the Tg of the resin.
    Type: Grant
    Filed: June 25, 1993
    Date of Patent: November 15, 1994
    Assignee: Xerox Corporation
    Inventors: Grazyna E. Kmiecik-Lawrynowicz, Raj D. Patel, Michael A. Hopper
  • Patent number: 5348832
    Abstract: A toner composition comprised of pigment, and a sulfonated polyester of the formula or as essentially represented by the formula ##STR1## wherein M is an ion independently selected from the group consisting of hydrogen, ammonium, an alkali metal ion, an alkaline earth metal ion and a metal ion; R is independently selected from the group consisting of aryl and alkyl; R' is independently selected from the group consisting of alkyl and oxyalkylene; and wherein n and o represent random segments; and wherein the sum of n and o are equal to 100 mole percent.
    Type: Grant
    Filed: June 1, 1993
    Date of Patent: September 20, 1994
    Assignee: Xerox Corporation
    Inventors: Guerino G. Sacripante, Raj D. Patel, Grazyna E. Kmiecik-Lawrynowicz
  • Patent number: 5346797
    Abstract: A process for the preparation of toner compositions comprising(i) preparing a pigment dispersion in a solvent, which dispersion is comprised of a pigment, an ionic surfactant and optionally a charge control agent;(ii) shearing the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, a nonionic surfactant and resin particles, thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and charge control agent to form electrostatically bound toner size aggregates; and(iii) heating the statically bound aggregated particles to form said toner composition comprised of polymeric resin, pigment and optionally a charge control agent.
    Type: Grant
    Filed: February 25, 1993
    Date of Patent: September 13, 1994
    Assignee: Xerox Corporation
    Inventors: Grazyna E. Kmiecik-Lawrynowicz, Raj D. Patel, Guerino G. Sacripante