Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2001-02-16
2002-03-05
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
C430S137140, C430S137160
Reexamination Certificate
active
06352810
ABSTRACT:
PENDING APPLICATIONS AND PATENTS
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 U.S. Pat. No. 6,268,102, filed Apr. 17, 2000, on “Toner Coagulant Processes”, 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.
In copending application U.S. Ser. No. 922,437, filed Sep. 2, 1997, on “Metal-Accelerated Toner Processes”, the disclosure of which is totally incorporated herein by reference, 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.
Illustrated in U.S. Pat. No. 5,994,020, the disclosure of which is 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;
(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; 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
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 into toner particles, and wherein aggregation can be primarily controlled by utilizing a coagulant of polyamine salts formed, for example, by reacting a diethyleneamine (DETA) or a dialkylene amine with an acid, and which salts are commercially available, and wherein there is preferably selected a latex comprised of, for example, submicron resin particles in the size range of, for example, about 0.1 to about 0.4 micron in volume average diameter, suspended in an aqueous phase of water, nonionic and anionic surfactants and optionally suspended in an anionic surfactant to which is added a colorant dispersion comprising, for example, submicron colorant particles in the size range of, for example, about 0.08 to about 0.3 micron in volume average diameter, anionic surfactant, or optionally a nonionic surfactant, or mixtures thereof, and optionally adding a wax dispersion comprising submicron wax 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 of water and an anionic surfactant, and wherein the resultant blend can be stirred and heated to a temperature below the latex resin Tg, resulting in toner aggregates to which is optionally added a second latex, followed by adjusting the pH of the mixture with a base and adding an organic or an inorganic oxidative reagent thereby preventing the formation of further cations or salts and heating the resulting mixture to a temperature above the latex resin Tg, followed by lowering the pH of the mixture with an acid to fuse the aggregates.
More specifically, the present invention is directed to the aggregation of latex, colorant like pigment, dye, or mixtures thereof, and optionally a wax in the presence of a polyamine salt, and wherein an organic or an inorganic oxidative reagent is introduced upon the completion of aggregation or heating below the latex resin Tg, and prior to coalescence or heating above the latex resin Tg wherein oxidative reagent prevents the formation of multivalent cations, such as NH3+, CH2+, and the like, and which can be introduced when the pH is lowered during coalescence, and wherein the generation of the further cations can function as a coagulant thereby initiating undesirable further growth in toner particle size. With the processes of the present invention there can be generated dry toners, for example, of 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 (GSD) of, for example, from about 1.10 to about 1.33, and more specifically, a size distribution in the range of 1.11 to 1.25, the size and size distribution being measured by a Coulter Counter, without the need to resort to conventional pulverization and classification methods. Furthermore, the present invention in embodiments enables minimum washing, for example about 2 to about 4 washings to provide a suitable toner triboelectrical charge such as greater than about 20 &mgr;C/g at about 50 percent RH. In embodiments of the present invention, organic or inorganic reagents oxidatively remove the polyamine salts initially used as a coagulating or flocculating agent after aggregation and prior to coalescence.
The present invention is, more specifically, directed to the utilization of an organic coagulating component with, for example, a resin emulsion like a styrene acrylate where the emulsion possesses, for example, a pH of about 2 to about 5, and removal of the coagulant following the aggregation of the latex, colorant and optionally wax particles by oxidative means, such as the use of sodium periodate, bleach, and the like thereby rendering the aggregate particles stable at low pH conditions. The use of oxidative reagents during the fabrication of toner particles provides, for example, wide process latitudes wherein the pH can be easily lowered to about 2.5 thereby accelerating the coalescence rate by about 1.5 times without further increases in toner particle size when compared to the use of polyaluminum chloride as a coagulant.
The toners generated with the processes of the present invention can be selected for copy and printing processes, including color processes and for imaging processes, especially xerographic processes, which usually prefer a toner transfer efficiency in excess of greater than about 90 percent, such as those with a compact machine design without a cleaner or those that are designed to provide 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 process
Hopper Michael A.
Jiang Lu
Mychajlowskij Walter
Palazzo E. O.
Xerox Corporation
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