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Toner aggregation processes

  • US 5,496,676 A
  • Filed: 03/27/1995
  • Issued: 03/05/1996
  • Est. Priority Date: 03/27/1995
  • Status: Expired due to Term
First Claim
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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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