Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2002-03-01
2003-10-28
Chapman, Mark A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
C523S335000
Reexamination Certificate
active
06638677
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is generally directed to toner processes, and more specifically, to aggregation and coalescence processes for the preparation of toner compositions. In embodiments, the present invention is directed to the economical chemical in situ preparation of toners without the utilization of the known pulverization and/or classification methods, and wherein in embodiments toner compositions with a volume average diameter of from about 1 to about 25, and more specifically, from about 1 to about 10 microns and narrow GSD of, for example, from about 1.14 to about 1.25 each as measured on the Coulter Counter can be obtained. The resulting toners can be selected for known electrophotographic imaging, digital, printing processes, including color processes, and lithography.
In reprographic technologies, such as xerographic and ionographic devices, toners with volume average diameter particle sizes of from about 9 microns to about 20-microns are effectively utilized. Moreover, in xerographic technologies, such as the high volume Xerox Corporation 5090 copier-duplicator, high resolution characteristics and low image noise are highly desired, and can be attained utilizing the small sized toners of the present invention with, for example, a volume average particle diameter of from about 2 to about 11 microns, and more specifically, less than about 7 microns, and with a narrow geometric size distribution (GSD) of from about 1.16 to about 1.3. Additionally, in xerographic systems wherein process color is utilized, such as pictorial color applications, small particle size colored toners, more specifically of from about 3 to about 9 microns, are desired to avoid paper curling. Also, it is preferable to select small toner particle sizes, such as from about 1 to about 7 microns, and with higher colorant loading, such as from about 5 to about 12 percent by weight of toner, such that the mass of toner layers deposited onto paper is reduced to obtain the same image quality and resulting in a thinner plastic toner layer on paper after fusing, thereby minimizing or avoiding paper curling. Toners prepared in accordance with the present invention enable in embodiments the use of lower image fusing temperatures, such as from about 120° C. to about 160° C., thereby avoiding or minimizing paper curl. Lower fusing temperatures minimize the loss of moisture from paper, thereby reducing or eliminating paper curl. The use of PTFE as a copolymer together with the polyester resin reduces the gloss of the image by about 12 to about 40 gloss units, thereby generating a matte finish image. Furthermore, by altering the amounts of PTFE, the gloss of the toner image can be matched to the paper.
For example, when a low gloss image of, more specifically, from about 1 to about 30 gloss is desired, low gloss paper is utilized, such as from about 1 to about 30 gloss units as measured by the Gardner Gloss metering unit, and which after image formation with small particle size toners, more specifically of from about 3 to about 5 microns, and fixing thereafter, results in a low gloss toner image of from about 1 to about 30 gloss units as measured by the Gardner Gloss metering unit. Alternatively, when higher image gloss is desired, such as from about 30 to about 60 gloss units as measured by the Gardner Gloss metering unit, higher gloss paper is utilized, such as from about 30 to about 60 gloss units, and which after image formation with small particle size toners of the present invention of, more specifically, from about 3 to about 5 microns, and fixing thereafter results in a higher gloss toner image of from about 30 to about 60 gloss units as measured by the Gardner Gloss metering unit. The aforementioned toner to paper matching can be attained with, for example, small particle size toners, such as less than about 7 microns, and more specifically, less than about 5 microns, such as from about 1 to about 4 microns, whereby the pile height of the toner layer or layers is considered low and acceptable.
PRIOR ART
Numerous processes are known for the preparation of toners, wherein a resin is melt kneaded or extruded with a pigment, micronized and pulverized to provide toner particles with a volume average particle diameter of from about 9 microns to about 20 microns and with broad geometric size distribution of from about 1.26 to about 1.5. In these processes, it is usually necessary to subject the aforementioned toners to classification such that the geometric size distribution of from about 1.2 to about 1.4 is attained. Also, in the aforementioned conventional. process, low toner yields after classifications may be obtained. Generally, during the preparation of toners with average particle size diameters of from about 11 microns to about 15 microns, toner yields are from about 70 percent to about 85 percent after classification. Additionally, during the preparation of smaller sized toners with particle sizes of from about 7 microns to about 11 microns, lower toner yields may be obtained after classification, such as from about 50 percent to about 70 percent. With the processes of the present invention in embodiments, small average particle sizes of, for example, from about 3 microns to about 15 microns, and more specifically, about 5 microns are attained without resorting to classification processes, and wherein narrow geometric size distributions are attained, such as from about 1.16 to about 1.30, and more specifically from about 1.16 to about 1.25. High toner yields are also attained such as from about 90 percent to about 98 percent in embodiments of the present invention. In addition, by the toner particle preparation process of the present invention in embodiments, small particle size toners of from about 3 microns to about 7 microns can be economically prepared in high yields, such as from about 90 percent to about 98 percent by weight based on the weight of all the toner ingredients, such as toner resin and colorant.
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 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, are obtained. The disadvantage, for example, of poor GSD requires classification resulting in low toner yields, reference for example 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 wherein flocculation as in the present invention is not believed to be disclosed; and U.S. Pat. No. 4,558,108, wherein there is disclosed a process for the preparation of a copolymer of styrene and butadiene by specific suspension polymerization.
In U.S. Pat. No. 5,290,654, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toners comprised of dispersing a polymer solution comprised of an organic solvent and a polyester, and homogenizing and heating the mixture to remove the solvent and thereby form toner c
Farrugia Valerie M.
Patel Raj D.
Vanbesien Daryl
Zwartz Edward G.
Chapman Mark A.
Palazzo E. O.
Xerox Corporation
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