Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2001-07-06
2002-09-24
Goodrow, John (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
C430S137170
Reexamination Certificate
active
06455220
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is generally directed to toner processes, and more specifically, to processes which utilize aggregation and coalescence, or fusion of latexes, colorant, such as pigment, dye, or mixtures thereof, and optional additive particles. In embodiments, the present invention is directed to processes which provide custom color toner compositions with, for example, a volume average diameter of from about 1 micron to about 25 microns, and more specifically, from about 2 microns to about 12 microns, and a narrow particle size distribution of, for example, about 1.10 to about 1.45 as measured by the Coulter Counter method. The resulting custom color toners can be selected for known electrophotographic imaging and printing processes, including digital color processes.
The present invention in aspects thereof is directed to a process for the preparation of custom toners by mixing a number of polymer encapsulated colorant latex particles, and more specifically, by blending and aggregating a number, such as four, different colorant polymer encapsulated miniemulsion latexes, and wherein each of the miniemulsion latex emulsions is comprised of monomer particles, more specifically submicron in size of from, for example, about 100 nanometers to about 1,000 nanometers, and more specifically, from about 200 nanometers to about 600 nanometers in volume average diameter, a nonionic surfactant and an ionic surfactant of opposite charge polarity to that of the ionic surfactant in the colorant dispersion, heating to accomplish polymerization of the monomer, thereafter heating the resulting mixture at, for example, below about the polymer 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 25 microns in volume average diameter, and which toner is comprised of polymer, colorants, and optional additive particles, followed by heating the aggregate suspension above about the 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 custom toner particles. Each miniemulsion can contain, for example, a latex of water, polymer or resin, and colorant, oil, or monomer, water, surfactants, and more specifically, a cosurfactant, such as an alcohol, an alkane, an ether, an alcohol ester, an amine, a halide, or a carboxylic acid ester, which cosurfactant is more specifically inert, nonvolatile, water insoluble, and is a liquid at a temperature of, for example, from about 40° C. to about 90° C., and 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 since, it is believed, there is formed 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 dyne/centimeter interfacial tension and high resistance to droplet coalescence.
With the present invention in embodiments, there is selected colorant encapsulated latexes containing a polymer generated by miniemulsion polymerization process. Aggregation/coalescence of the colorant encapsulated polymer latexes permit, for example, the generation of a wide range of colored toner compositions with, for example, high colorant loading, narrow particle size distribution, and excellent projection efficiency.
Other advantages in embodiments include, for example, (1) excellent particle dispersion in the resin matrix; (2) acceptable mechanical properties; (3) protection of the colorant from outside influences during toner processing; (4) protection of the matrix or toner resin from interaction with the colorant; and (5) the generation of custom color toners with uniform triboelectric charging characteristics independent of the colorant present and wherein the colorant is passivated. When the xerographic properties, such as triboelectric charge (tribo), admix, developer stability, humidity sensitivity, and the like of highlight color and black toners, are substantially equivalent, the toners can be considered triboelectrically passivated. One primary main advantage of a blended mixture of two passivated toners is their interchangeability.
Embodiments of the present invention are directed to processes for the preparation of toners, and more specifically, highlight color toners and custom color toners. A highlight color toner can be a single toner of a single color of, for example, a saturated hue, which can be utilized with a second color toner like a black toner. These colored toners may be imaged on documents with twin engine xerographic copiers or printers, where each engine comprises a separate charging, exposure, development, transfer, and cleaning component, one for each color toner, or with a single engine xerographic copier or printer which utilize two separate development stations, one for each color, and where the paper, transparency, or other throughput substrate makes either one or two cycles. An example of a single engine printing/copying device with only one cycle can be referred to as trilevel xerography. Applications for highlight color include, for example, emphasizing important information, headlining titles in documents, slides, overhead transparencies, figures and the like. The image color density of a highlight color may be controlled by the developed toner mass per unit area, for example, the higher the toner mass per unit area, the darker the color. Typical highlight colors are common colors desired by many different types of customers, such as red, blue, brown, green, and the like, and wherein a custom color toner can be a very specific highlight color toner. Often toners with these colors are used for corporate logos, letterhead, government flags, or official document seals, where the color coordinates are specified. Examples of custom colors are Xerox Corporation Blue®, IBM Blue®, Blue CrossBlue®, and the like. Other custom colors may include gold, silver, fluorescent colors, and the like.
The aforementioned toners are especially useful for imaging processes, especially xerographic processes, which usually enable 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, improved signal-to-noise ratio, and image uniformity.
PRIOR ART
There is illustrated in U.S. Pat. No. 4,996,127, the disclosure of which is totally incoporated herein by reference, 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 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, the disclosure of which is totally incoporated herein by reference, there is disclosed a process for the preparation of toners by the polymerization of a polymerizable monomer dispersed by emulsification 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 pa
Goodrow John
Palazzo E. D.
Xerox Corporation
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