Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2001-03-19
2002-07-09
RoDee, Christopher (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
51
Reexamination Certificate
active
06416920
ABSTRACT:
PENDING APPLICATIONS AND PATENTS
In copending application U.S. Ser. No. 922,437, abandoned the disclosure of which is totally incorporated herein by reference, there is illustrated, for example, a process for the preparation of toner comprising
(i) aggregating with a metal complex, or metal ion a colorant dispersion with a latex emulsion and optional additives to form aggregates;
(ii) coalescing or fusing the aggregates; and optionally
(iii) isolating, washing, and drying the toner.
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.
In copending application U.S. Ser. No. 09/551,465, now U.S. Pat. No. 6,268,102 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 is a polyaluminum sulfosilicate.
Also illustrated in U.S. Pat. No. 5,994,020 and U.S. Pat. No. 6,130,021, the disclosures of which are totally incorporated herein by reference, are toner preparation processes, and more specifically, a process for the preparation of toner comprising
(i) preparing, or providing a colorant dispersion;
(ii) preparing, or providing a functionalized wax dispersion comprised of a functionalized wax contained in a dispersant mixture comprised of a nonionic surfactant, an ionic surfactant, or mixtures thereof;
(iii) shearing the resulting mixture of the functionalized wax dispersion (ii) and the colorant dispersion (i) with a latex. or emulsion blend comprised of resin contained in a mixture of an anionic surfactant and a nonionic surfactant in the presence of a coagulant;
(iv) heating the resulting sheared blend of (iii) below about the glass transition temperature (Tg) of the resin particles;
(v) optionally adding additional anionic surfactant to the resulting aggregated suspension of (iv) to prevent, or minimize additional particle growth of the resulting electrostatically bound toner size aggregates during coalescence (iv);
(vi) heating the resulting mixture of (v) above about the Tg of the resin; and optionally,
(vii) separating the toner particles; and a process for the preparation of toner comprising blending a latex emulsion containing resin, colorant, and a polymeric additive; adding an acid to achieve a pH of about 2 to about 4 for the resulting mixture; heating at a temperature about equal to, or about below the glass transition temperature (Tg) of the latex resin to initiate aggregation; optionally adding an ionic surfactant stabilizer; heating at a temperature about equal to, or about above about the Tg of the latex resin; and optionally cooling, isolating, washing, and drying the toner.
The appropriate components and processes of the above recited copending applications and patents may be selected for the processes of the present invention in embodiments thereof.
BACKGROUND OF THE INVENTION
The present invention is generally directed to toner processes, and more specifically, to chemical processes which involve the aggregation and fusion of latex resin, colorant like pigment, or dye, and additive particles into toner particles, and wherein aggregation can be primarily controlled by utilizing a cationic coagulant of a silica, such as a colloidal silica with an alumina coating, that is for example, a colloidal dispersion of discrete spherical silica particles of pure, about 100 percent, amorphous silicon dioxide and wherein the surface is modified to attain cationic properties with a coating of Al
2
O
3
on the silica core thereby providing a functionalized colloidal silica, which silica is commercially available and is commercially used in water purification industries, and wherein there is selected a latex comprised, for example, of submicron resin particles in the size range of, for example, about 0.1 to about 0.3 micron in volume average diameter, suspended in an aqueous phase comprised of a mixture of water, an anionic surfactant and a colorant dispersion comprising submicron pigment particles in the size range of, for example, about 0.08 to about 0.3 micron in volume average diameter as measured by a disc centrifuge suspended in an aqueous phase of water and an anionic surfactant and optionally a nonionic surfactant or mixtures thereof, which are blended together in the presence of a coagulant, and wherein the resultant blend is stirred and heated to a temperature below the resin Tg, resulting in aggregates to which optionally is added a second latex to provide a coating on the formed toner aggregates, followed by adjusting the pH of the mixture with a base, and heating the mixture to a temperature above the resin Tg, followed by adjusting the pH of the mixture with an acid to fuse the aggregates. More specifically, the present invention is generally directed to the aggregation and coalescence or fusion of latex, colorant like pigment, dye, and additives like a wax in the presence of colloidal aluminized silica, which is, for example, in the diameter size range of about 0.005 about 0.2 micron, and wherein there are generated 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 with a narrow particle size distribution of, for example, from about 1.10 to about 133, and more specifically, a size distribution in the range of about 1.11 to about 1.28, the size and size distribution being measured by a Goulter Counter without the need to resort to conventional pulverization and classification methods. Furthermore, the present invention in embodiments enables minimum washings, for example about 2 to about 4 washings to provide a suitable toner triboelectrical charge in the range of about −40 to about −20 &mgr;C/g at 20 percent RH. The toners generated can be selected for known electrophotographic imaging and printing processes, including digital color processes such as the Xerox 5090 or the Xerox Docutech 265.
Toners prepared by the process of the present invention possess a number of advantages as compared to a number of known emulsion aggregation processes, which advantages include, for example, the ability to control the finish of the fused developed toner image, for example a glossy or a matte image by controlling the amount of the colloidal aluminized silica used as the coagulant, wherein the lower the concentration of the aluminized silica in a toner formulation, for example less than about 3.5 percent by weight of the toner, there results a glossy image.
Another advantage of the present invention in embodiments resides in using a colloidal aluminized silica as a coagulant to allow for the full incorporation of the silica into the toner particles as compared to using colloidal silica in the toner formulation, which is then aggregated with other known coagulants, such as polyaluminum chloride (PAC) or polyaluminum sulfosilicate (PASS) wherein the silica retention for the latter two situations is, for example, less than about 20 percent. Furthermore, another advantage of the present invention in embodiments resides in an increase of reactor productivity by 50 to 60 percent as compared to a number of known emulsion aggregation processes where the coagulants utilized are PAC and PASS. Additionally, with the invention processes in embodiments toner washing can be reduced by about 60 to about 75 percent and the triboelectric charging values of the toner obtained remain substantially constant irrespective of the colorant selected. Furthermore, when the toners generated are roll milled and aged over a period of, for example, about 2 to about 3 hours there results stable and negative toner charging with, for example, no or minimal wrong sign positively charged toner.
The toners gene
Hopper Michael A.
Patel Raj D.
Vanbesien Daryl
Palazzo E. O.
RoDee Christopher
Xerox Corporation
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