Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2000-04-26
2002-02-12
Rodee, Christopher (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
C430S137110, C430S137170
Reexamination Certificate
active
06346358
ABSTRACT:
PENDING APPLICATIONS AND PATENTS
Illustrated in U.S. Ser. No. 09/558,538 now U.S. Pat. No. 6,309,787, filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, is a process comprising aggregating an encapsulated colorant with colorant particles, and wherein said encapsulated colorant is generated by a miniemulsion polymerization.
Illustrated in U.S. Ser. No. 08/959,798, pending entitled “Toner Processes”, the disclosure of which is totally incorporated herein by reference, is a process for the preparation of toner comprising
(i) aggregating a colorant dispersion containing a suitable surfactant with a latex emulsion containing an anionic surfactant, a nonionic surfactant, and a water miscible chain transfer agent, or a nonionic surfactant with chain transfer characteristics to form toner sized aggregates;
(ii) coalescing or fusing the aggregates; and optionally
(iii) isolating, washing, and drying the resulting toner.
Illustrated in U.S. Pat. No. 5,944,650 and U.S. Pat. No. 5,766,818, the disclosures of each application being totally incorporated herein by reference, are cleavable surfactants and the use thereof in emulsion/aggregation and coalescence toner processes.
In U.S. Pat. No. 5,766,817, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner comprising
(i) aggregating a colorant dispersion with a latex miniemulsion containing polymer, an ionic surfactant, a cosurfactant, and a nonionic surfactant;
(ii) coalescing or fusing the aggregates generated; and optionally
(iii) cooling, isolating, washing, and drying the toner, and wherein the polymer in the miniemulsion is of a diameter of from about 50 to about 500 nanometers. The miniemulsion processes and the miniemulsions of this patent may be selected for the preparation of the encapsulated colorants of the present invention.
BACKGROUND OF THE INVENTION
The present invention is generally directed to colorant and toner processes, and more specifically, to processes which select aggregation and coalescence, or fusion of a polymer latex, colorant, such as pigment, dye, or mixtures thereof, and optional additive particles. In embodiments, the present invention is directed to processes which provide toner compositions with a volume average diameter of, for example, from about 1 micron to about 25 microns, and preferably from about 2 microns to about 12 microns, and a narrow particle size distribution of, for example, about 1.1 to about 1.45, both as measured by the Coulter Counter method. The resulting toners can be selected for known electrophotographic imaging and printing processes, including digital processes.
The present invention in aspects thereof is directed to a process for the preparation of toners by generating encapsulated colorant latexes or encapsulated colorants prepared by miniemulsion polymerization, wherein the miniemulsion latex emulsion is preferably submicron in size, of from, for example, about 100 nanometers to about 1,000 nanometers and preferably from about 200 nanometers to about 600 nanometers in volume average diameter, and contains a nonionic surfactant and an ionic surfactant of opposite charge polarity to that of the nonionic surfactant, thereafter heating the resulting mixture at, for example, below about the latex resin glass transition temperature, and more specifically, from about 35° C. to about 60° C. (Centigrade) to form toner sized aggregates of from about 2 microns to about 20 microns in volume average diameter, and which toner is comprised of polymer, colorant, especially pigment and optionally known toner additive particles, followed by heating the aggregate suspension above about the latex resin, or polymer glass transition temperature, and more specifically, at, for example, from about 70° C. to about 100° C. to effect coalescence or fusion of the components of the aggregates and to form mechanically stable integral toner particles. The miniemulsion can contain colorant, monomer, water, surfactants, and preferably a cosurfactant, such as an alcohol, an alkane, an ether, an alcohol ester, an amine, an alkyl thiol, a halide, or a carboxylic acid ester, which cosurfactant is preferably inert, nonvolatile, water insoluble, liquid at a temperature of from about 40° C. to about 90° C., and preferably contains a terminal aliphatic hydrocarbyl group with at least about 10 carbon atoms, and more specifically, from about 12 to about 24 carbon atoms, and mixtures thereof, and more specifically, an aliphatic alcohol with at least about 8 carbon atoms, such as from about 10 to about 25 carbon atoms, and an alkane with from about 10 to about 30 carbon atoms. The cosurfactant primarily functions to reduce the diffusion of monomer out of the monomer droplet and enables relatively stable miniemulsions because, it is believed, of the formation of intermolecular complexes at the oil/water interface. The complexes are believed to be liquid condensed and electrically charged thus creating a low, for example from about 0.5 dyne/centimeter to about 5 dynes/centimeter interfacial tension and high resistance to droplet coalescence.
The microencapsulation of colorant is an important area of research in paint and toner industries. Several benefits generated with encapsulation in accordance with the present invention include (1) improved particle dispersion in a resin matrix; (2) improved mechanical properties; (3) protection of the colorant from outside influences during toner processing; (4) protection of the matrix polymer from interaction with the colorant; and (5) excellent colorant encapsulation and uniform or substantial uniform toner triboelectric charging values, or passivation of the colorant.
With the present invention in embodiments, there is selected an encapsulated colorant generated by miniemulsion polymerization process. Aggregation/coalescence of the encapsulated colorant enable the generation of different color toners with uniform tribocharging. This results in toners with similar charging behavior independent of the colorant type.
The aforementioned toners are especially useful for imaging processes, especially xerographic processes, which usually require high toner transfer efficiency, such as those having a compact machine design without a cleaner, or those that are designed to provide high quality colored images with excellent image resolution and signal-to-noise ratio, and image uniformity.
PRIOR ART
There is illustrated in U.S. Pat. No. 4,996,127 a toner of associated particles of secondary particles comprising primary particles of a polymer having acidic, or basic polar groups and a coloring agent. The polymers selected for the toners of the '127 patent can be prepared by an emulsion polymerization method, see for example columns 4 and 5 of this patent. In column 7 of this '127 patent, it is indicated that the toner can be prepared by mixing the required amount of coloring agent and optional charge additive with an emulsion of the polymer having an acidic or basic polar group obtained by emulsion polymerization. In U.S. Pat. No. 4,983,488, there is disclosed a process for the preparation of toners by the polymerization of a polymerizable monomer in the presence of a colorant and/or a magnetic powder to prepare a principal resin component and then effecting coagulation of the resulting polymerization liquid in such a manner that the particles in the liquid after coagulation have diameters suitable for a toner. It is indicated in column 9 of this patent that coagulated particles of 1 to 100, and particularly 3 to 70, are obtained. The disadvantages of, for example, wide particle size distributions hence classification is usually required resulting in low toner yields, are illustrated in U.S. Pat. No. 4,797,339, wherein there is disclosed a process for the preparation of toners by resin emulsion polymerization, wherein similar to the '127 patent certain polar resins are selected; and U.S. Pat. No. 4,558,108, wherein there is disclosed a process for the preparati
Palazzo E. O.
Rodee Christopher
Xerox Corporation
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