Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Patent
1995-12-21
1997-04-22
Martin, Roland
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
430110, G03G 9087, G03G 9093
Patent
active
056228066
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 0.5 to about 10 percent by weight to water, and an optional 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;
(iii) stirring the resulting sheared viscous mixture of (ii) at from about 300 to about 1,000 revolutions per minute to form electrostatically bound substantially stable toiler size aggregates with a narrow particle size distribution;
(iv) reducing the stirring speed in (iii) to from about 100 to about 600 revolutions per minute, and subsequently adding further anionic or nonionic surfactant in the range of from about 0.1 to about 10 percent by weight of water to control, prevent, or minimize further growth or enlargement of the particles in the coalescence step (v);
(v) heating and coalescing from about 5.degree. to about 50.degree. C. above about the resin glass transition temperature, Tg, which resin Tg is from between about 45.degree. C. to about 90.degree. C., the statically bound aggregated particles to form said toner composition comprised of resin, pigment and optional charge control agent;
(vi) washing the aggregated particles at a temperature of from about 15.degree. C. to about 5.degree. C. below the glass transition temperature of the resin, and subsequently filtering the aggregated particles until substantially all of the surfactant has been removed from the aggregated particles, followed by subsequent driving of the particles at a temperature of from about 15.degree. C. to about 5.degree. C. below the glass transition temperature of the resin; and
(vii) subsequently adding to said toner product a first layer of a hydrophilic oxide, and a second layer of a hydrophobic oxide.
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McDougall Maria N. V.
Veregin Richard P. N.
Martin Roland
Palazzo E. O.
Xerox Corporation
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