Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2002-09-27
2004-06-29
Goodrow, John L (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
C430S137100
Reexamination Certificate
active
06756176
ABSTRACT:
In U.S. Pat. No. 6,132,924, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner comprising mixing a colorant, a latex, and two coagulants, followed by aggregation and coalescence, and wherein one of the coagulants may be polyaluminum chloride.
Illustrated in U.S. Pat. No. 6,638,677, entitled Toner Processes, the disclosure of which is totally incorporated herein by reference, is a process comprising heating a latex, a colorant dispersion, a polytetrafluoroethylene dispersion, and an organo metallic complexing component.
Illustrated in U.S. Pat. No. 5,945,245, the disclosure of which is totally incorporated herein by reference, is a process for the preparation of toner compositions comprising:
(i) preparing an emulsion latex comprised of sodio sulfonated polyester resin particles of from about 5 to about 500 nanometers in size diameter, by heating said resin in water at a temperature of from about 65° C. to about 90° C.;
(ii) preparing a pigment dispersion in water by dispersing in water from about 10 to about 25 weight percent of sodio sulfonated polyester, and from about 1 to about 5 weight percent of pigment;
(iii) adding the pigment dispersion to a latex mixture comprised of sulfonated polyester resin particles in water with shearing, followed by the addition of an alkali halide in water until aggregation results, as indicated by an increase in the latex viscosity of from about 2 centipoise to about 100 centipoise;
(iv) heating the resulting mixture at a temperature of from about 45° C. to about 55° C., thereby causing further aggregation and enabling coalescence, resulting in toner particles of from about 4 to about 9 microns in volume average diameter and with a geometric distribution of less than about 1.3; and optionally
(v) cooling the product mixture to about 25° C. and followed by washing and drying.
BACKGROUND
The present invention is directed to a toner process, and more specifically, to chemical toner processes which involve the aggregation and fusion of latex, colorant like pigment or dye, and additive particles.
In embodiments, the present invention is directed to toner compositions and processes thereof, wherein the surface layer of the toner is comprised of a linear sulfonated polyester resin rendered hydrophobic by a wet chemical surface treatment with aqueous solutions of various water soluble alkyl carboxylate metal salts or water insoluble fatty acid metal salts thereby, for example, reducing excessive C-zone charge (20 percent relative humidity) from about −175 microcoulombs per gram to about +13 microcoulombs per gram. More specifically, in embodiments the present invention relates to toner processes wherein there is selected a metal stearate like calcium stearate, and which stearate, for example, reduces excessive negative C-zone charge to thereby provide excellent toner relative humidity (RH) sensitivity, which stearate is also effective at low, for example from about 0.0025 to about 3 percent by weight of the toner components, and which can tune the charging properties of the toner, for example change the toner charge from a positive charge to a negative charge and further wherein the calcium stearate can provide in embodiments excellent flowing toners and toners free or substantially free of undesirable clumping.
The toners generated with the processes of the present invention can be selected for copying and printing processes, including color processes, and for imaging processes, and which toners can provide, for example, high quality colored images with excellent image resolution, acceptable signal-to-noise ratio, and image uniformity. Also, the toners obtained with the processes illustrated herein can be selected for digital imaging systems and processes.
REFERENCES
In xerographic systems, especially color systems, small sized toners of, for example, from about 2 to about 8 microns can be important to the achievement of high image quality for process color applications. It is also important to have a low image pile height to eliminate, or minimize image feel and avoid paper curling after fusing. Paper curling can be particularly pronounced in xerographic color processes primarily because of the presence of relatively high toner coverage as a result of the application of three to four color toners. During fusing, moisture escapes from the paper due to high fusing temperatures of from about 120° C. to about 200° C. In the situation wherein only one layer of toner is selected, such as in one-color black or highlight color xerographic applications, the amount of moisture driven off during fusing can be reabsorbed by the paper, and the resulting print remains relatively flat with minimal paper curl. In process color where toner coverage is high, the relatively thick toner plastic covering on the paper can inhibit the paper from reabsorbing the moisture, and cause substantial paper curling. These and other imaging shortfalls and problems are avoided or minimized with the toners and processes of the present invention.
Also, it may be useful to select certain toner particle sizes, such as from about 2 to about 10 microns, with a high colorant, especially pigment loading, such as from about 4 to about 15 percent by weight of toner, so that the mass of toner necessary for attaining the required optical density and color gamut can be significantly reduced to eliminate or minimize paper curl. Lower toner mass also ensures the achievement of image uniformity. However, higher pigment loadings often adversely affect the charging behavior of toners. For example, the charge levels may be too low for proper toner development or the charge distributions may be too wide and toners of wrong charge polarity may be present. Furthermore, higher pigment loadings may also result in the sensitivity of charging behavior to charges in environmental conditions, such as temperature and humidity. Toners prepared in accordance with the processes of the present invention minimize, or avoid these disadvantages.
There is illustrated in U.S. Pat. No. 4,996,127, the disclosure of which is totally incorporated 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 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, the disclosure of which is totally incorporated 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 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 microns, are obtained. In U.S. Pat. No. 4,797,339, the disclosure of which is totally incorporated herein by reference, 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 in U.S. Pat. No. 4,558,108, the disclosure of which is totally incorporated herein by reference, there is disclosed a process for the preparation of a copolymer of styrene and butadiene by specific suspension polymerization.
Polyester based chemical toners substantially free of encapsulation are also known, reference U.S. Pat. No. 5,593,807, the disclosure of which is totally incorporated herein by reference, whe
Farrugia Valerie M.
Stegamat Reza
Veregin Richard P. N.
Goodrow John L
Palazzo E. O.
Xerox Corporation
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