Processes for producing toner

BACKGROUND

0001Disclosed herein is a toner process, and more specifically, a chemical toner processes which involves the aggregation and fusion of latex, colorant like pigment or dye, alumina particles which are added subsequent to aggregation and fusion with the colorant, and additive particles.

0002More specifically, in embodiments illustrated herein are toner processes wherein there results a toner with a positive charge, triboelectric charge stability to a variety of environmental conditions, excellent developer aging characteristics, reduced excessive negative C-zone charge to thereby provide excellent toner relative humidity (RH) sensitivity, excellent flowing toners and toners free or substantially free of undesirable clumping.

0003The toners generated with the processes disclosed can be selected for copying and printing processes, including high speed highlight color systems, trilevel color xerography, color processes, and for a number of known imaging processes, and which toners can provide, for example, high quality colored images, including excellent developed custom color 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

0004In imaging systems, especially color systems, small sized toners of, for example, from 2 to 8 microns can be of value for 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 120°C to 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 featured herein.

0005Also, it may be useful to select certain toner particle sizes, such as from 2 to 12 microns, with a high colorant, especially pigment loading, such as from 4 to 17 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 featured herein minimize, or avoid a number of these disadvantages. <patcit id="pcit0001" dnum="EP1441260A"><text>EP-A-1441260</text></patcit> (relevant with respect to Article 54(3) EPC) discloses a toner process comprising adding a sulfonated polyester resin to heated water, adding a colorant dispersion, heating the resulting mixture above the resin glass transition temperature, and then adding an aggregating agent, thereby causing aggregation and coalescence. <patcit id="pcit0002" dnum="US2003219666A"><text>US-A-2003/219666</text></patcit> discloses a toner process comprising mixing a polymer latex, a colorant dispersion, and an aggregating agent, and heating the resulting mixture above the polymer glass transition temperature, thereby causing aggregation and coalescence. The toner may contain external additives. The amount of the external additives is preferably from 0.1 to 5.0% by weight, and more preferably from 0.5 to 4.0% by weight. Examples of the additives include fine inorganic particles, fine organic particles, and lubricants. <patcit id="pcit0003" dnum="US2003175609A"><text>US-A-2003/175609</text></patcit> discloses an emulsion aggregation process for the preparation of a toner, the toner particles comprising a sulfonated polyester resin, a colorant, and an aggregating agent. The toner may contain external additives such as colloidal silica in an amount of from 0.1 to 2% by weight.

0006<patcit id="pcit0004" dnum="US6395445B"><text>US-B-6395445</text></patcit> discloses toner particles comprising a sulfonated polyester resin, a colorant, and an aggregating agent. The toner may contain surface additives such as colloidal silica, or titania, in an amount of from 0.1 to 2% by weight.

0007<patcit id="pcit0005" dnum="US6416920B"><text>US-B-6416920</text></patcit> discloses a process for the preparation of a toner comprising mixing a polymer, a colorant, and silica having an alumina coating as a coagulant. The coagulant assists in permitting aggregation and coalescence of polymer and colorant. The thickness of the alumina coating on the silica core may be up to 1.5 microns. The toner may further contain surface additives such as colloidal silica, or another metal oxide, in an amount of from 0.1 to 2% by weight.

0008<patcit id="pcit0006" dnum="US5536615A"><text>US-A-5536615</text></patcit> discloses a toner comprising a polymer, a pigment, and an optional charge adjuvant in an amount of from 0.1 to 15% by weight. Examples of the charge adjuvants include fine particles of silica, alumina, or titania.

0009Processes for the preparation of toners comprising a polymer, a colorant, and an aggregating agent are also known from <patcit id="pcit0007" dnum="US2003104296A"><text>US-A-2003/104296</text></patcit>, <patcit id="pcit0008" dnum="WO03087949A"><text>WO-A-03/087949</text></patcit>, <patcit id="pcit0009" dnum="US2003027073A"><text>US-A-2003/027073</text></patcit>, and <patcit id="pcit0010" dnum="US6190820B"><text>US-B-6190820</text></patcit>. The toners may contain fluidizers such as hydrophobic silica, titania, alumina, or ceria.

SUMMARY

0010The present invention provides a process comprising adding a sulfonated polyester to heated water, adding a colorant dispersion, and then subsequently adding an aggregating agent; heating the resulting mixture above the polyester glass transition temperature thereby causing aggregation and coalescence, optionally followed by cooling and drying, and subsequently adding alumina particles, wherein there results particles comprised of said polyester, said colorant, said aggregating agent, and said alumina present in an amount of from 4 to 12 weight percent and optionally wherein said alumina is present on the surface of said particles.

0011Preferred embodiments of the invention are set forth in the sub-claims.

0012It is a feature of the present disclosure to provide toner processes with many of the advantages illustrated herein.

0013In another feature of the present disclosure there are provided simple and economical processes for the preparation of black and colored toner compositions with excellent colorant dispersions, thus enabling the achievement of excellent color print quality; and a simple and economical chemical process for the preparation of toner compositions.

0014Additionally, another feature of the present disclosure resides in a process capable of delivering differing toner morphology particles, such as spherically shaped toner particles.

0015Moreover, in another feature of the present disclosure there are provided emulsion, aggregation, coalescence processes wherein, for example, the toner obtained has incorporated during the process, that is, subsequent to aggregation and coalescence, alumina particles.

0016Aspects disclosed herein and of the present invention in embodiments relate to the process of claim 1 comprising adding, a polymer to heated water; adding a colorant dispersion, and then subsequently adding an aggregating agent; heating the resulting mixture above about the polymer glass transition temperature thereby causing aggregation and coalescence, optionally followed by cooling and drying, and subsequently adding alumina particles, and wherein there results particles comprised of polymer, colorant, aggregating agent, and alumina, and optionally wherein the alumina is present on the surface of the particles resulting; a toner process of claim 1 comprising heating a mixture of a latex and a colorant dispersion in the presence of an aggregating agent, and subsequently adding in an amount of at least 4 weight percent to 12 wt% alumina particles, and optionally which particles primarily function as a charge enhancing additive; a toner process comprising heating a mixture of a latex aggregating agent and a colorant in the presence of water, which water is at a temperature of above 40°C and less than 100°C, which heating is accomplished below the glass transition temperature, Tg, of polymer contained in the latex, followed by a second heating above the Tg polymer temperature, and subsequently adding in an amount of at least 4 weight percent to 12 weight percent alumina particles; a process wherein the latex is a latex emulsion comprised of resin, water, and an ionic surfactant, and wherein the colorant mixture is a dispersion containing a colorant, water, and an ionic surfactant; a process wherein there is selected for the ionic surfactant a nonionic surfactant; a process wherein the alumina particles are selected in an amount of from 4 to 10 percent by weight of the toner components; a process wherein each of the surfactants is selected in an amount of from 1 to 10 weight percent based on the toner component amounts; a process wherein there can optionally be added to the latex colorant mixture a second latex, and which latex is comprised of submicron resin particles suspended in an aqueous phase containing an ionic surfactant, and wherein the second latex is optionally selected in an amount of from 10 to 40 percent by weight of the initial latex; a process wherein the temperature below the latex resin Tg is from 40°C to 60°C, thereby resulting in toner aggregates, and the temperature above the latex resin Tg is from 75°C to 97°C; a process wherein the temperature at which the aggregation is accomplished controls the size of the aggregates, and wherein the toner isolated is of from 2 to 15 microns in volume average diameter; a process wherein the colorant is a pigment; a process wherein the latex contains a polyester, such as polyester SPE2, available from Hercules Chemical; a toner and processes thereof wherein the resin is a polyester of the formula <chemistry id="chem0001" num="0001"><img file="EP1560074B1_D0001.tif" /></chemistry> wherein Y is an alkali metal, X is a glycol, and n and m each represent the number of segments; a toner wherein the polyester is present in an amount of from 80 to 98 percent by weight of the toner, the colorant is present in an amount of from 2 to 20 weight percent of the toner, the alumina is present in an amount of 5 to 12 percent by weight, and wherein the total of all the toner components is about 100 percent; a toner wherein the polyester resin contains from 0.1 to 5 weight percent of sulfonated groups; a toner wherein the alumina primarily functions to enhance the toner triboelectric charge and reduce the toner relative humidity sensitivity; a toner wherein the polyester is a sodiosulfonated polyester; a process for the preparation of toner comprising mixing alumina particles with a latex and a colorant mixture comprised of colorant, and an ionic surfactant, heating the resulting mixture below the glass transition temperature (Tg) of the latex resin, heating above the Tg of the latex resin; or alternatively adding alumina particles subsequent to the formation of toner, which particles can function as a charge enhancing additive, and optionally isolating the toner, and wherein the alumina resides on the surface of the toner; a process wherein the latex is a latex emulsion comprised of resin, water, and an ionic surfactant, and wherein the colorant mixture is a dispersion containing a pigment, water, and an ionic surfactant; a process wherein there is selected for the ionic surfactant a nonionic surfactant; a process wherein each of the surfactants is selected in an amount of from 3 to 7 weight percent based on the toner component amounts; a process wherein there is added to the mixture or resin latex and colorant a second latex, and which latex is comprised resin particles suspended in an aqueous phase containing an ionic surfactant, and wherein the second latex is selected in an amount of from 12 to 25 percent by weight of the initial latex; a process wherein the temperature below the latex resin Tg is from 40°C to 65°C, thereby resulting in toner aggregates, and the temperature above the latex resin Tg is from 77°C to 95°C; a process wherein the temperature at which the aggregation is accomplished controls the size of the aggregates, and wherein the toner isolated is from 2 to 25 microns in volume average diameter; a process wherein the colorant is carbon black, cyan, yellow, magenta, or mixtures thereof, and the toner isolated is from 2 to 25 microns in volume average diameter, and the particle size distribution thereof is optionally from 1.15 to 1.30, and wherein there is optionally added to the surface of the formed toner metal salts, metal salts of fatty acids, silicas, metal oxides, or mixtures thereof, each in an amount of from 0.1 to 10 weight percent of the obtained toner; a process wherein the colorant is a colorant dispersion comprised of <ul id="ul0001" list-style="none"><li>(i) a colorant, water, an ionic surfactant, a nonionic surfactant, or mixtures of an ionic surfactant, and a nonionic surfactant; the latex is a latex emulsion; and wherein</li><li>(ii) the colorant dispersion is blended with the latex emulsion comprised of resin, a nonionic surfactant and an ionic surfactant, and optionally adding a wax dispersion comprised of, for example, submicron particles in the diameter size range of from 0.1 to 0.4 micron dispersed in an ionic surfactant of the same charge polarity as that of the ionic surfactant in the colorant dispersion or latex emulsion;</li><li>(iii) heating the resulting mixture below or equal to the glass transition temperature (Tg) of the latex resin to form toner sized aggregates;</li><li>(iv) heating the resulting aggregate suspension above the Tg of the latex resin; adding the alumina particles and isolating the toner, which toner contains the alumina particles on the surface thereof; a process for the preparation of toner comprising</li><li>(i) providing or generating a latex emulsion of resin, water, and an ionic surfactant, and providing or generating a colorant dispersion containing a colorant, water, an ionic surfactant, or a nonionic surfactant;</li><li>(ii) optionally providing or generating a wax dispersion containing an anionic surfactant similarly charged to that of the latex surfactant emulsion;</li><li>(iii) blending (ii) with the colorant dispersion;</li><li>(iv) heating the resulting mixture below the glass transition temperature (Tg) of the latex resin;</li><li>(v) heating (vii) above the Tg of the latex resin;</li><li>(vi) followed by the addition of alumina particles in an amount of from 4 to 7 weight percent;</li><li>(vii) retaining the mixture (vi) at a temperature of from 70°C to 95°C for 3 to 10 hours;</li><li>(viii) washing the resulting toner slurry; and</li><li>(ix) isolating the toner; a process wherein the added latex contains the same resin as the initial latex of (i), or wherein the added latex contains a dissimilar resin than that of the initial latex resin (i); a process wherein aggregation of latex resin and colorant is accomplished by heating at a temperature below the glass transition temperature of the resin or polymer contained in the latex, and coalescence is accomplished by heating at a temperature of above the glass transition temperature of the polymer contained in the latex (i) to enable fusion or coalescence of colorant and latex resin, followed by the mixing of the composition resulting with alumina particles; a process wherein the aggregation temperature is from 45°C to 55°C, and the coalescence temperature is from 75°C to 97°C; a process for preparing toner particles comprising.</li><li>(i) providing or generating a latex emulsion of resin, water, and an anionic surfactant; a process wherein the latex emulsion comprises submicron resin particles in the size range of 100 to 500 nanometers, and more specifically, in the size range of 150 to 400 nanometers in water and an ionic surfactant, and more specifically, an anionic surfactant; the colorant dispersion comprises submicron pigment particles of 50 to 250 nanometers, and more specifically, of 80 to 200 nanometers in size diameter; a toner process wherein the cationic surfactant comprises, for example, dialkyl benzenealkyl ammonium chloride, lauryl trimethyl ammonium chloride, alkylbenzyl methyl ammonium chloride, alkyl benzyl dimethyl ammonium bromide, benzalkonium chloride, cetyl pyridinium bromide, C₁₂, C₁₅, C₁₇ trimethyl ammonium bromides, halide salts of quaternized polyoxyethylalkylamines, dodecylbenzyl triethyl ammonium chloride, and which coagulant surfactant component is selected in an amount of, for example, from 0.01 to 10 percent by weight of toner; a process wherein there is added during or subsequent to (v) a second latex, and which latex is comprised of submicron resin particles suspended in an aqueous phase containing an ionic surfactant, and wherein the second latex is optionally selected in an amount of 15 to 35 percent by weight of the initial latex; a process wherein the second latex (vi) is added and enables formation of a coating on the resulting toner aggregates of (v), and wherein the thickness of the formed coating is from 0.1 to 1 micron; a process wherein the aggregation temperature is from 50°C to 60°C, and the coalescence temperature is from 80°C to 95°C; a process wherein the toner colorant is carbon black, red, green, cyan, yellow, magenta, or mixtures thereof, and the toner isolated is from 1 to 25 microns in volume average diameter, and the particle size distribution thereof is optionally from 1.15 to 1.30; and wherein there is added to the surface of the formed toner metal salts, metal salts of fatty acids, silicas, metal oxides, or mixtures thereof, each in an amount of from 1 to 3 weight percent of the obtained toner.</li></ul>

0017Examples of polyester resins include copoly(1,2-propylene-dipropylene-5-sulfoisophthalate)-copoly(1,2-propylene-dipropylene terephthalate), copoly(1,2-propylene-diethylene-5-sulfoisophthalate)-copoly(1,2-propylene-diethylene terephthalate), copoly(propylene-5-sulfoisophthalate)-copoly(1,2-propylene terephthalate), copoly(1,3-butylene-5-sulfoisophthalate)-copoly(1,3-butylene terephthalate), copoly(butylenesulfoisophthalate)-copoly(1,3-butylene terephthalate) .

0018The alumina particles selected are commercially available from, for example, Alfa Aesar located in Massachusetts, USA, and more specifically, there can be selected a hydrophilic alumina such as Aluminum Oxide C (a product of Nippon Aerosil Co., Ltd.). The hydrophilicity of the alumina is usually considered sufficient when the alumina can be dispersed in water. The hydrophilic alumina particles possess an average particle size diameter of, for example, from 20 to 150 nanometers, and more specifically, from 30 to 50 nanometers. Various suitable effective amounts of the alumina particles can be selected, and more specifically, from 4 to 5 weight percent, and which particles function primarily as a toner charge enhancing additive.

0019Specific examples of aluminas that can be selected include Al₂O₃ dry powder, with a specific gravity of from 3.4 to 4 grams/cm³; a diameter of, for example, from 20 nanometers to 3 microns and available from Cabot Corporation (Massachusetts), Degussa AG (Germany), Bayer AG (Germany), H.C. Starck, Inc. (USA); 20 nanometers of alumina primary particles contained in an aqueous dispersion and available from Cabot as CAB-O-SPERSE^® PG003, other known aluminas.

0020Various known colorants, especially pigments, present in the toner in an effective amount of, for example, from 1 to 65, and more specifically, from 2 to 35 percent by weight of the toner, and yet more specifically, in an amount of from 1 to 15 weight percent, and wherein the total of all toner components is about 100 percent, include carbon black like REGAL 330^®; magnetites such as Mobay magnetites M08029™, M08060™. As colored pigments, there can be selected known cyan, magenta, yellow, red, green, brown, blue or mixtures thereof. Specific examples of colorants, especially pigments, include phthalocyanine HELIOGEN BLUE L6900™, D6840™, D7080™, D7020™, Cyan 15:3, Magenta Red 81:3, Yellow 17, the pigments of <patcit id="pcit0011" dnum="US5556727A"><text>U.S. Patent 5,556,727</text></patcit>. Examples of specific magentas that may be selected include, for example, 2,9-dimethyl-substituted quinacridone and anthraquinone dye identified in the Color Index as Cl 60710, Cl Dispersed Red 15, diazo dye identified in the Color Index as Cl 26050, Cl Solvent Red 19. Illustrative examples of specific cyans that may be selected include copper tetra(octadecyl sulfonamido) phthalocyanine, x-copper phthalocyanine pigment listed in the Color Index as Cl 74160, Cl Pigment Blue, and Anthrathrene Blue, identified in the Color Index as Cl 69810, Special Blue X-2137, while illustrative specific examples of yellows that may be selected are Diarylide Yellow 3,3-dichlorobenzidene acetoacetanilides, a monoazo pigment identified in the Color Index as Cl 12700, Cl Solvent Yellow 16, a nitrophenyl amine sulfonamide identified in the Color Index as Foron Yellow SE/GLN, Cl Dispersed Yellow 33 2,5-dimethoxy-4-sulfonanilide phenylazo-4'-chloro-2,5-dimethoxy acetoacetanilide, and Permanent Yellow FGL. Colored magnetites, such as mixtures of MAPICO BLACK™, and cyan, magenta, yellow components may also be selected as pigments. The colorants, such as pigments, selected can be flushed pigments as indicated herein.

0021More specifically, colorant examples include Pigment Blue 15:3 having a Color Index Constitution Number of 74160, Magenta Pigment Red 81:3 having a Color Index Constitution Number of 45160:3, and Yellow 17 having a Color Index Constitution Number of 21105, and known dyes such as food dyes, yellow, blue, green, red, magenta dyes. Colorants include pigments, dyes, mixtures of pigments, mixtures of dyes, mixtures of dyes and pigments, and preferably pigments.

0022Dry powder additives that can be added or blended onto the surface of the toner compositions after, for example, washing or drying include, for example, metal salts, metal salts of fatty acids, colloidal silicas, metal oxides like titanium, siloxanes, tin , mixtures thereof, which additives are each present in an amount of from about 0.1 to about 2 weight percent or other effective amounts, reference <patcit id="pcit0012" dnum="US3590000A"><text>U.S. Patents 3,590,000</text></patcit>; <patcit id="pcit0013" dnum="US3720617A"><text>3,720,617</text></patcit>; <patcit id="pcit0014" dnum="US3655374A"><text>3,655,374</text></patcit> and <patcit id="pcit0015" dnum="US3983045A"><text>3,983,045</text></patcit>. Preferred additives include zinc stearate and flow aids, such as fumed silicas like AEROSIL R972^® available from Degussa, or silicas available from Cabot Corporation or Degussa Chemicals, the coated silicas of <patcit id="pcit0016" dnum="US6004714A"><text>U.S. Patent 6,004,714</text></patcit> and <patcit id="pcit0017" dnum="US6190815B"><text>U.S. Patent 6,190,815</text></patcit>.

0023Developer compositions can be prepared by mixing the toners with known carrier particles, including coated carriers, such as steel, ferrites, reference <patcit id="pcit0018" dnum="US4937166A"><text>U.S. Patents 4,937,166</text></patcit> and <patcit id="pcit0019" dnum="US4935326A"><text>4,935,326</text></patcit>, for example from 2 percent toner concentration to 8 percent toner concentration.

0024Imaging methods are also envisioned with the toners of the present invention, reference for example a number of the patents mentioned herein, and <patcit id="pcit0020" dnum="US4265990A"><text>U.S. Patent 4.265.990</text></patcit>.

0025In embodiments thereof illustrative examples of resin, polymer or polymers disclosed herein in the latex (i) or added latex include known polymers such as methacrylates, acrylates, polyesters, polybutadienes, and other suitable polymers as illustrated herein for example. The latex polymer, or resin is generally present in the toner compositions in various suitable amounts, such as from 75 to 98 weight percent, or from 80 to 95 weight percent of the toner or of the solids, and the latex size can be, for example, from 0.05 micron to 0.5 micron in volume average diameter as measured by the Brookhaven nanosize particle analyzer. Other sizes and effective amounts of latex polymer may be selected in embodiments. The total of all toner components, such as resin, calcium stearate, and colorant, is about 100 percent, or about 100 parts.

0026The polymer selected for the process disclosed can be prepared by emulsion polymerization methods, and the monomers utilized in such processes include, for example, styrene, acrylates, methacrylates, butadiene, isoprene, acrylic acid, methacrylic acid, itaconic acid, beta carboxy ethyl acrylate, acrylonitrile. Known chain transfer agents, for example dodecanethiol, from, for example, 0.1 to 10 percent, or carbon tetrabromide in effective amounts, such as for example from 0.1 to 10 percent, can also be utilized to control the molecular weight properties of the polymer when emulsion polymerization is selected. Other processes of obtaining polymer particles of from, for example, 0.01 micron to 2 microns can be selected from polymer microsuspension process, such as disclosed in <patcit id="pcit0021" dnum="US3674736A"><text>U.S. Patent 3,674,736</text></patcit>; polymer solution microsuspension process, such as disclosed in <patcit id="pcit0022" dnum="US5290654A"><text>U.S. Patent5,290,654</text></patcit>, mechanical grinding processes, or other known processes.

0027Examples of waxes that can be selected for the processes and toners illustrated herein include polypropylenes and polyethylenes commercially available from Allied Chemical and Petrolite Corporation, wax emulsions available from Michaelman Inc. and the Daniels Products Company, EPOLENE N-15™ commercially available from Eastman Chemical Products, Inc., VISCOL 550-P™, a low weight average molecular weight polypropylene available from Sanyo Kasei K.K., and similar materials. The commercially available polyethylenes selected possess, it is believed, a molecular weight M_w of from 1,000 to 3,000, while the commercially available polypropylenes are believed to have a molecular weight of from 4,000 to 7,000. Examples of functionalized waxes include, such as amines, amides, for example AQUA SUPERSLIP 6550™, SUPERSLIP 6530™ available from Micro Powder Inc., fluorinated waxes, for example POLYFLUO 190™, POLYFLUO 200™, POLYFLUO 523XF™, AQUA POLYFLUO 411™, AQUA POLYSILK 19™, POLYSILK 14™ available from Micro Powder Inc., mixed fluorinated amide waxes, for example MICROSPERSION 19™ also available from Micro Powder Inc., imides, esters, quaternary amines, carboxylic acids or acrylic polymer emulsion, for example JONCRYL 74™, 89™, 130™, 537™, and 538™, all available from SC Johnson Wax, chlorinated polypropylenes and polyethylenes available from Allied Chemical, Petrolite Corporation and SC Johnson Wax.

0028Examples of initiators utilized for the latex preparation include water soluble initiators, such as ammonium and potassium persulfates, in suitable amounts, such as from 0.1 to 8 percent, and more specifically, from 0.2 to 5 percent (weight percent). Examples of organic soluble initiators include Vazo peroxides, such as VAZO 64™, 2-methyl 2-2'-azobis propanenitrile, and VAZO 88™, 2-2'-azobis isobutyramide dehydrate in a suitable amount, such as in the range of from 0.1 to 8 percent. Examples of chain transfer agents include dodecanethiol, octanethiol, carbon tetrabromide, in various suitable amounts, such as in an amount of from 0.1 to 10 percent, and more specifically, from 0.2 to 5 percent by weight of monomer.

0029Surfactants for the preparation of latexes and colorant dispersions can be ionic or nonionic surfactants selected in effective amounts of, for example, from 0.01 to 15, or from 0.01 to 5 weight percent of the reaction mixture. Anionic surfactants include sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate, sodium dodecylnaphthalene sulfate, dialkyl benzenealkyl, sulfates and sulfonates, abitic acid, available from Aldrich, NEOGEN R™, NEOGEN SC™ obtained from Kao. Examples of cationic surfactants are dialkyl benzenealkyl ammonium chloride, lauryl trimethyl ammonium chloride, alkylbenzyl methyl ammonium chloride, alkyl benzyl dimethyl ammonium bromide, benzalkonium chloride, cetyl pyridinium bromide, C₁₂, C₁₅, C₁₇ trimethyl ammonium bromides, halide salts of quaternized polyoxyethylalkylamines, dodecylbenzyl triethyl ammonium chloride, MIRAPOL™ and ALKAQUAT™ available from Alkaril Chemical Company, SANIZOL™ (benzalkonium chloride) available from Kao Chemicals, selected in effective amounts of, for example, from 0.01 percent to 10 percent by weight. The molar ratio of the cationic surfactant used for flocculation to the anionic surfactant used in the latex preparation is, for example, from 0.5 to 4.

0030Illustrative examples of aggregating components or agents include zinc stearate; alkali earth metal or transition metal salts; alkali (II) salts, such as beryllium chloride, beryllium bromide, beryllium iodide, beryllium acetate, beryllium sulfate, magnesium chloride, magnesium bromide, magnesium iodide, magnesium acetate, magnesium sulfate, calcium chloride, calcium bromide, calcium iodide, calcium acetate, calcium sulfate, strontium chloride, strontium bromide, strontium iodide, strontium acetate, strontium sulfate, barium chloride, barium bromide, barium iodide . Examples of transition metal salts or anions include acetates, acetoacetates, sulfates of vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, copper, zinc, cadmium, silver or aluminum salts, such as aluminum acetate, aluminum polyaluminum chloride, aluminum halides, mixtures thereof. The amount of aggregating agent selected can vary, and is, for example, from 0.1 to 10, and more specifically from 2 to 5 weight percent by weight of toner or by weight of water.

0031Examples of nonionic surfactants selected in various suitable amounts, such as 0.1 to 5 weight percent, are polyvinyl alcohol, polyacrylic acid, methalose, methyl cellulose, ethyl cellulose, propyl cellulose, hydroxy ethyl cellulose, carboxy methyl cellulose, polyoxyethylene cetyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether, dialkylphenoxy poly(ethyleneoxy) ethanol, available from Rhone-Poulenac as IGEPAL CA-210™, IGEPAL CA-520™, IGEPAL CA-720™, IGEPAL CO-890™, IGEPAL CO-720™, IGEPAL CO-290™, IGEPAL CA-210™, ANTAROX 890™ and ANTAROX 897™, can be selected.

0032The following Examples are presented.

<u>EXAMPLE I</u>

0033A polyester cyan toner was prepared by following the process as illustrated in <patcit id="pcit0023" dnum="US6395445B"><text>U.S. Patent 6,395,445</text></patcit>.

0034A sulfonated polyester resin and emulsion thereof is prepared as follows. Dimethylterephthalate (715 grams), sodium dimethyl 5-sulfoisophthalate (95.8 grams), propanediol (526 grams), diethylene glycol (48 grams), dipropylene glycol (247.1 grams), and butyltin hydroxide catalyst (1.5 grams) are charged to a 2 liter Hoppes polycondensation reactor, equipped with a heating jacket, mechanical stirrer with anchor, thermowell, reflux and take-off condenser. The mixture is heated to 190°C, and the temperature is allowed to slowly increase to about 200°C to about 202°C while the methanol byproduct is collected in a distillation receiver. The temperature is then raised to about 210°C as the pressure is reduced from atmospheric to about 8 millimeters Hg over a period of about 4.5 hours. During this time, excess glycol is collected in the distilling receiver. The product is discharged thorough a bottom drain valve to result in random copolymers thereof of 44 percent/5.9 percent/32.4 percent/3 percent/14.8 percent of dimethylterephthalate/sodium dimethyl 5-sulfoisophthalate/propanediol/diethylene glycol/dipropylene glycol. 168 Grams of the above polyester resin are then added to 1,232 grams of deionized water at 92°C in a 20 gallon reactor with stirring for 2 hours to provide an emulsion of from about 10 to about 25 weight percent of sulfonated polyester particles in water. The diameter particle size of the resin in the emulsion is typically 22 nanometers as measured by a NiComp sizer.

0035In a stainless steel 2 liter Buchi reactor equipped with two stirring blades (P4/45°), 2 baffles, and with heating supplied by an outside bath to the jacket of the reactor are added 1,400 grams of the above polyester emulsion, and 14.22 grams of FLEXIVERSE^® blue 15:3 color pigment dispersion available from Sun Chemical Company. A solution of 5 percent zinc acetate (aggregating agent) in deionized water is prepared by dissolving zinc acetate at room temperature (22°C to 25°C) in a beaker with magnetic stirring. This solution is added to a reservoir that is placed onto a balance and connected to a pump capable of accurately dispensing the zinc acetate solution between 0.0 and 9.9 ml/minute. The amount of zinc acetate selected in this Example for the aggregation is 10 percent of the weight of resin in the emulsion. The emulsion/dispersion is heated to 56°C, and the stirring speed is adjusted to 350 rpm by a tachometer. To initiate the aggregation, the pump to the zinc acetate solution is started at 9.9 ml/minute. The amount of zinc acetate in the aggregation is measured by the weight loss on the balance. When 60 percent of the total zinc acetate is added (205 grams of 5 percent solution), the pump addition rate is reduced to 1.1 ml/minute, and the addition is continued until the amount of zinc acetate equals 10 percent of the resin in the emulsion (335 grams of 5 percent solution). Samples, in amounts of 1 gram, are taken during and tested on a Coulter Counter for particle size and particle size distribution. When the particle size is 6 µm and the geometric size distribution (GSD) less than 1.2, the aggregation is stopped by lowering the temperature in the reactor to room temperature. The particles resulting are then discharged and screened through 150 and 38 µm sieves to remove coarse material with particle diameter sizes of about 40 to about 500 micrometers, and then the particles are collected by filtration on a 5 µm polypropylene filter cloth. The particles are then rinsed and washed 2 times. The filtrate conductivity is 23.4 µS. The toner particles are dried in a vacuum oven for 64 hours at room temperature. Fouled material is scraped from the reactor interior. The coarse and fouled material is then also dried and weighed to determine the mass balance. The resulting toner is comprised of the above sulfonated polyester resin, about 85 weight percent; 9 weight percent Carnauba wax; and 6 weight percent of the above cyan Blue 15:3.

0036A solution-coated carrier 35 µm in diameter and comprising a ferrite core (Powdertech Corporation, Japan), and a coating of 2.44 percent (14/66/20 PFEMA/TBMA/MMA) perfluoroethyl methacrylate/tertiarybutyl methacrylate/methyl methacrylate resin, 0.26 percent carbon black and 0.3 percent EPOSTAR S Melamine beads is used to prepare experimental developers: 10 Grams of the aforementioned carrier particles are mixed with 0.5 gram of the above prepared toner in a 60 milliliter glass bottle and conditioned for about 16 to about 18 hours in A- or C-zone environmental chambers (85 percent RH, 28°C; 15 percent RH, 10°C, respectively). After conditioning, developer is charged in a Turbula mixer for 60 minutes. Triboelectric charge was measured by obtaining toner traces on paper substrates in a charge spectrograph and measuring the deflection of the toner trace from the zero-field dot position. Typically, deflection to the right is for negative charge, left for positive charge.

0037The toner exhibited a negative charge of -19 millimeters (i.e., millimeters of average deflection in the charge spectrograph under an electric field of 100 volts per centimeter from a zero-field dot position) in C-zone and -0.5 millimeter in A-zone at very high RH sensitivity (C/A charge ratio of 38).

<u>EXAMPLE II</u>

0038The toner of Example I is blended with 4 weight percent of alumina nano-powder particles available from Alfa Aesar (MA, USA), catalog number 10459, by using a 1 liter SK-M toner mill.

0039The toner triboelectric charge is measured with the same carrier as in Example I and using the method of Example I. The toner charge is positive, +5 millimeters in A-zone and +11 millimeters in C-zone (C/A ratio 2.2).

0040Development experiments are conducted in a Xerox Corporation DC1250 printer. 450 Grams of developer at a toner/carrier ratio of 5 percent are charged in a Turbula mixer for 10 minutes and placed in the DC1250 black developer housing. Then the toner/carrier ratio is increased to 7 percent and 9 percent. Test images are obtained on the machine photoreceptor under the CAD (charge area development) conditions where the high potential on the charged photoreceptor (-650 volts) corresponds to toned image area, and the low potential on laser-discharged photoreceptor (-400 volts) corresponds to white area. The magnetic roller bias is varied between -650 V and -400.

0041DMA (developed toner mass per unit area) is measured by developing a solid area toner patch with known area and weighing the amount of developed toner by collecting it on a MILIPORE^® filter attached to a vacuum pump. The level of background development is measured by tape transfer from the white area and counting toner particles per square mm. Visible background is usually observed with about 100 to about 600 particles per square millimeter. <tables id="tabl0001" num="0001"><table frame="all"><title><b><u>TABLE 1</u></b></title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="28mm" /><colspec colnum="2" colname="col2" colwidth="17mm" /><colspec colnum="3" colname="col3" colwidth="15mm" /><colspec colnum="4" colname="col4" colwidth="27mm" /><colspec colnum="5" colname="col5" colwidth="48mm" /><thead><row><entry align="center"><b>TC</b></entry><entry align="center" valign="top"><b>Q/D, MM</b></entry><entry align="center" valign="top"><b>VBIAS</b></entry><entry align="center" valign="top"><b>DMA (MG/CM²)</b></entry><entry align="center" valign="top"><b>BKG (PARTICLES PER MM²)</b></entry></row></thead><tbody><row><entry align="center">5 percent</entry><entry align="center">3.21</entry><entry align="center">-450</entry><entry align="center">0.272</entry><entry align="center" /></row><row><entry align="center">5 percent</entry><entry align="center">3.21</entry><entry align="center">-475</entry><entry align="center">0.046</entry><entry align="center">80</entry></row><row><entry align="center">5 percent</entry><entry align="center">3.21</entry><entry align="center">-500</entry><entry align="center" /><entry align="center" /></row><row><entry align="center">5 percent</entry><entry align="center">3.21</entry><entry align="center">-450</entry><entry align="center">0.130</entry><entry align="center">40</entry></row><row><entry align="center">7 percent</entry><entry align="center">2.65</entry><entry align="center">-450</entry><entry align="center">0.206</entry><entry align="center">40</entry></row><row><entry align="center">7 percent</entry><entry align="center">2.65</entry><entry align="center">-475</entry><entry align="center">0.170</entry><entry align="center">84</entry></row><row><entry align="center">7 percent</entry><entry align="center">2.65</entry><entry align="center">-425</entry><entry align="center">0.264</entry><entry align="center">20</entry></row><row><entry align="center">9 percent</entry><entry align="center">2.50</entry><entry align="center">-425</entry><entry align="center">0.270</entry><entry align="center" /></row><row><entry align="center">9 percent</entry><entry align="center">2.50</entry><entry align="center">-425</entry><entry align="center">0.284</entry><entry align="center">40</entry></row><row><entry namest="col1" nameend="col4" align="center"><b>Developer aged off-line for 60 minutes</b></entry><entry align="center" /></row><row><entry align="center">9 percent (aged)</entry><entry align="center">2.50</entry><entry align="center">-425</entry><entry align="center">0.238</entry><entry align="center">48</entry></row></tbody></tgroup></table></tables>

0042Table 1 illustrates DMA and background at different TC (toner concentration) and development bias. Typically, a DMA of at least 0.2 mg/cm² is excellent to obtain a reasonable solid area image. The data in Table 1 indicates that the positive-charged toner of this Example II can be developed under the CAD conditions to a reasonable DMA (> 0.2 mg/cm²) with a low background in a broad range of toner concentrations.

0043After aging the developer in the no toner throughput regime for 60 minutes (an equivalent of printing 3,000 blank images) under a typical stress regime, no change in triboelectric charge (q/d) and very little change in DMA and background occurred indicating that the Example II toner is stable to mechanical aging.

<u>EXAMPLE III</u>

0044The developer in this Example contains the toner of Example II and carrier prepared by powder coating a 35 µm diameter Powdertech ferrite core with a 0.8 weight percent coating polymer blend comprising 75 percent SLS PMMA illustrated in <patcit id="pcit0024" dnum="US6355391B"><text>U.S. Patent 6,355,391</text></patcit>, the disclosure of which is totally incorporated herein by reference, 9 percent VULCAN^® carbon black (Cabot, USA), 10 percent EPOSTAR™ S melamine-formaldehyde resin powder, particle size of about 100 to about 300 nanometers (Nippon Shokubai, Japan) and 6 percent KYNAR^® (DuPont, USA). <tables id="tabl0002" num="0002"><table frame="all"><title><b><u>TABLE</u> 2</b></title><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="37mm" /><colspec colnum="2" colname="col2" colwidth="19mm" /><thead><row><entry align="center" valign="top"><b>ALUMINA CONTENT</b></entry><entry align="center" valign="top"><b>Q/D, MM</b></entry></row></thead><tbody><row><entry align="center">0.50 percent</entry><entry align="center">-30.36</entry></row><row><entry align="center">1 percent</entry><entry align="center">-17.25</entry></row><row><entry align="center">2 percent</entry><entry align="center">1.53</entry></row><row><entry align="center">4 percent</entry><entry align="center">12.31</entry></row></tbody></tgroup></table></tables>

0045Table 2 indicates, for example, how developer charge changes with alumina content; 2 percent alumina loading enables a positive charge, and 4 percent of alumina permits an excellent toner positive charge level.