Toner aggregation processes
First Claim
1. A process comprising:
- (i) preparing a pigment dispersion comprised of pigment, ionic surfactant, and optional charge control agent;
(ii) mixing at least two resins of different molecular composition, molecular weight or Tg 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 resins, 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 resins to form stable toner particles; and
optionally(vii) separating and drying the toner.
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Accused Products
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 resin to form stable toner particles; and optionally
(vii) separating and drying the toner.
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Citations
48 Claims
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1. A process comprising:
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(i) preparing a pigment dispersion comprised of pigment, ionic surfactant, and optional charge control agent; (ii) mixing at least two resins of different molecular composition, molecular weight or Tg 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 resins, 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 resins to form stable toner particles; and
optionally(vii) separating and drying the toner. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 41, 42, 45, 46)
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35. A process for the preparation of toner particles with a particle size of from about 1 to about 25 microns in average volume diameter comprising:
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(i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment with a diameter of from about 0.01 to about 1 micron, and an ionic surfactant; (ii) mixing at least two latexes comprised of resins of different molecular composition, molecular weight or Tg, ionic and nonionic surfactants and optionally a charge control agent, and wherein the ionic surfactant employed has countercharging characteristics with reference to the ionic surfactant of (i); (iii) shearing the pigment dispersion with a mixture of the latex blend (ii) comprised of resins, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant, and wherein said blend is submicron in size of from about 0.01 to about 1 micron, thereby which shearing enables a flocculation or heterocoagulation of the formed particles of pigment, and resin to form a uniform dispersion of solids in the water and surfactant; (iv) heating the above sheared blend at a temperature of from about 5°
to about 20°
C. below the Tg of the resins to form electrostatically bound toner size aggregates with a narrow particle size distribution;
followed by the addition of further anionic surfactant;(v) heating the electrostatically bound toner size aggregate particles at a temperature of from about 5°
to about 50°
C. above the Tg of the resins to provide a mechanically stable toner composition comprised of polymeric resin and pigment; and
optionally(vi) separating said toner particles; and (vii) drying said toner particles. - View Dependent Claims (43, 44)
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47. A process for the preparation of toner compositions comprising:
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(i) preparing a pigment dispersion comprised of pigment, ionic surfactant, and optional charge control agent; (ii) preparing a latex blend of two or more latexes containing resins of different molecular composition, molecular weight or Tg with a polytron or a mixer operating for a period of from about 0.5 to 2 minutes to obtain a latex blend; (iii) shearing said pigment dispersion with the latex blend (ii) comprised of resins, 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 blends of (iii) below about the glass transition temperature (Tg) of the resins to form electrostatically bound toner size aggregates with a narrow particle size distribution; (v) subsequently adding further anionic surfactant solution to minimize further growth of the aggregates in the coalescence step (vi); and (vi) heating said bound aggregates above about the Tg of the resins.
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48. A process for the preparation of toner comprising:
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(i) preparing a pigment dispersion comprised of pigment, ionic surfactant, and optional charge control agent; (ii) mixing a first and a second latex, each latex comprising a resin of different molecular composition, molecular weight or Tg from the resin of the other latex, ionic and nonionic surfactants and optionally a charge control agent, and wherein the ionic surfactant possesses a countercharge opposite to that of said ionic surfactant used in (i) and wherein a latex blend results; (iii) shearing said pigment dispersion with the latex blend of (ii) comprised of resins, a counterionic surfactants with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant; (iv) heating the above sheared blends below about the glass transition temperature (Tg) of the latex resins to form electrostatically bound toner size aggregates with a narrow particle size distribution; (v) subsequently adding further an ionic surfactant solution to minimize further growth of the aggregates in the coalescence step (vi); (vi) heating said bound aggregates above about the Tg of the latex resins to form stable toner particles; and
optionally(vii) separating the toner particles from the aqueous medium by filtration, washing the toner to remove traces of surfactant, and drying to produce an electrophotographic toner.
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Specification