Process for preparation of acrylonitrile-modified toner compositions

Abstract: There is provided a toner comprised of colorant, and an addition polymer resin generated from about 55 to about 80 weight percent of styrene, from about 1 to about 25 weight percent of acrylate, from about 1 to about 20 weight percent of acrylonitrile, and from about 0.5 to about 5 weight percent of acrylic acid. There is also provided a process for the preparation of said toner.

Description: 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 a chemical preparative process for toners without resorting to conventional pulverization and/or classification methods, thus rendering the present process economical. For the relatively low molecular weight styrene based resins which are utilized in the toner compositions of the present invention in embodiments, the inclusion of an acrylonitrile moiety in the resin composition in an effective amount is of importance to achieving excellent image fix and gloss characteristics, as well as improving the toner's resistance to frictional and mechanical breakage in development housings. U.S. Patent 4,996,127 describes 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. Also, see column 9, lines 50 to 55, wherein a polar monomer, such as acrylic acid, in the emulsion resin is necessary, and toner preparation is not obtained without the use, for example, of acrylic acid polar group, see Comparative Example I. U.S. Patent 4,983,488, describes 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. This process is thus directed to the use of coagulants, such as inorganic magnesium sulfate, which results in the formation of particles with a wide GSD. US-A-5 501 935 describes a process for preparing a toner by mixing a pigment dispersion containing an ionic surfactant with a latex or emulsion blend containing a resin and a counterionic surfactant, heating the obtained blend to form electrostatically bound toner size aggregates, heating said bound aggregates to provide stable toner compositions. The present invention is the provision of processes for the preparation of toner compositions the resins of which are derived from the polymerization of a mixture of styrene, acrylate, acrylonitrile and acrylic acid as defined in claim 1, and which compositions enable excellent image fix and gloss characteristics ideal for xerographic color applications, and improved crease resistance. The present invention is the provision of processes for the economical, direct preparation of toner compositions with specific toner resins which enable improved image fix to paper as generally characterized by lower image crease, and excellent image gloss as characterized by high image gloss value, and wherein the toner particle size is in the range of from about 1 to about 20 microns, or more preferably from 2 to 10 microns in volume average diameter, and which toners possess a narrow GSD of less than 1.35, and preferably of from 1.15 to 1.25, thus enabling enhanced image resolution, lower image pile height, and thus eliminating or minimizing undesirable image text feel and paper curl. The present invention there is provided a process for the preparation of toner comprising: (i) preparing in the presence of an ionic surfactant and an optional nonionic surfactant a latex emulsion generated from the emulsion polymerization of a mixture of from 55 to 80 weight percent of styrene, from 1 to 25 weight percent of acrylate, from 1 to 20 weight percent of acrylonitrile, and from 0.5 to 5 weight percent of acrylic acid; (ii) mixing said latex emulsion by high shear blending with an aqueous pigment dispersion comprised of pigment and an ionic surfactant that is of opposite charge polarity to the ionic surfactant in said latex emulsion; (iii) heating the resultant flocculant mixture at a temperature that is 30°C below to 10°C above the Tg of the latex resin to form electrostatically bound toner sized aggregates; (iv) subsequently heating said aggregate suspension at a temperature of from 10°C to 50°C above the Tg of the latex resin; and optionally (v) followed by washing, drying, and dry blending the toner with surface additives. In embodiments, the present invention is directed to processes for the preparation of toner compositions which comprises blending, by means of a high shearing device such as a Brinkmann polytron, a sonicator or microfluidizer, an aqueous pigment dispersion containing water, a pigment or pigments, such as carbon black like REGAL 330®, phthalocyanine, quinacridone or RHODAMINE B™ type, and a cationic surfactant, such as benzalkonium chloride, and optional known charge control additives with a latex emulsion obtained from emulsion polymerization of a mixture of acrylonitrile, acrylate, styrene, and acrylic acid, and which latex emulsion contains an anionic surfactant, such as sodium dodecylbenzene sulfonate, and a nonionic surfactant; heating the resulting flocculant mixture at a temperature from 30°C to 1°C below the Tg of the latex resin to induce formation of toner sized aggregates comprised of latex, pigment, and optional additive particles; effecting coalescence of the aggregates at a temperature of from 10°C to 50°C above the Tg of the resin in the presence of additional anionic surfactant, wherein the constituents of the aggregates coalesce or fuse together to form integral toner particles; followed by cooling and isolating the resultant toner product by washing with water, and drying by means of an Aeromatic fluidized bed dryer, freeze dryer, or spray dryer to provide toners comprised of the aforementioned resin, pigment, and optional charge control additive, and which toners have a particle size of from 1 to 20 microns, and more specifically, from 2 to 10 microns in volume average particle diameter, and a GSD of from 1.15 to 1.25 as measured by the Coulter Counter. Embodiments of the present invention include a process for the preparation of toner compositions comprised of pigment, optional toner additives, and certain important emulsion polymer resins derived from emulsion polymerization of a mixture of acrylonitrile, acrylate, styrene, and acrylic acid monomers, comprising: (i) preparing, or providing a latex emulsion by emulsion polymerization of acrylonitrile, acrylate, styrene, and acrylic acid in the presence of an anionic surfactant and a nonionic surfactant, and wherein acrylonitrile of 1 to 20 weight percent, acrylate of 10 to 30 weight percent, styrene of 55 to 80 weight percent, and acrylic acid of 0.5 to about 5 weight percent are selected; (ii) blending the resulting latex emulsion with optional additives and an aqueous pigment dispersion containing a cationic surfactant by means of a high shearing device to provide a flocculant mixture; (iii) heating the flocculent mixture with gentle stirring at a temperature of from about 30°C to about 1°C below the resin Tg to form electrostatically bound aggregates of latex, pigment, and optional additive particles, such as wax, charge control agent, and wherein the aggregate size is in the range of from 2 to 10 microns in volume average diameter, and the aggregate GSD is from 1.15 to 1.25; (iv) heating the aggregate suspension at 65°C to 110°C in the presence of additional anionic surfactant to convert the aggregates into integral toner particles comprised of a pigment, optional additives, and a polymer resin of acrylontrile, acrylate, styrene, and acrylic acid monomer, followed by cooling; and (v) isolating the toner product by washing, followed by drying, and optionally blending with surface additives. Also, in embodiments the present invention is directed to processes for the preparation of toner compositions which comprises (i) preparing a pigment mixture by dispersing optional charge control additives and a pigment, such as carbon black like REGAL 330®, HOSTAPERM PINK™, or PV FAST BLUE™ of from 1 to 20 percent by weight of toner in an aqueous mixture containing a cationic surfactant such as dialkylbenzene dialkylammonium chloride, for example SANIZOL B-50™ available from Kao, or MIRAPOL™ available from Alkaril Chemicals, utilizing a high shearing device, such as a Brinkman Polytron or IKA homogenizer; (ii) adding the resulting pigment dispersion to a latex emulsion derived from the emulsion polymerization of a mixture of acrylonitrile, acrylate, styrene, and acrylic acid in the presence of an anionic surfactant, such as sodium dodecylsulfate, dodecylbenzene sulfonate or NEOGEN R™, and a nonionic surfactant, such as polyethylene glycol or polyoxyethylene glycol nonyl phenyl ether or IGEPAL 897™ obtained from GAF Chemical Company; (iii) homogenizing the above mixture using a high shearing device, such as a Brinkman Polytron or IKA homogenizer, at a speed of from 3,000 revolutions per minute to 10,000 revolutions per minute for a duration of from 1 minute to 120 minutes, and heating the resultant mixture at a temperature of from 30°C below to 1°C below the Tg of the latex resin while mechanically stirred at a speed of from 250 to 500 rpm to effect formation of electrostatically bound aggregates of from 2 microns to 10 microns in volume average diameter; (iv) subsequently heating the aggregate mixture at 65°C to 110°C for a duration of 30 minutes to a few, such as tow or three hours in the presence of additional anionic surfactant in the amount of from 0.01 percent to 5 percent by weight to form integral toner particles of from 2 to 10 microns in volume average diameter, and a GSD of from 1.15 to 1.25 as measured by the Coulter Counter; cooling and (v) isolating the toner particles by washing, filtering and drying, thereby providing toner particles with a toner composition comprised of an acrylonitrile-acrylate-styrene-acrylic acid resin, pigment, and optional charge control additives. Flow additives to improve flow properties may be optionally added to the toner obtained by blending with the toner, which additives include AEROSILS® or silicas, metal oxides like tin, titanium and the like, metal salts of fatty acids like zinc stearate, and which additives each can be present in various effective amounts, such as from 0.1 to 5 percent by weight of toner. Embodiments of the present invention include a toner comprised of pigment, and an addition polymer resin generated from 55 to 80 weight percent of styrene, from about 1 to 25 weight percent of acrylate, from 1 to 20 weight percent of acrylonitrile, and from 0.5 to 5 weight percent of acrylic acid. Preferably, the resin is obtained from emulsion polymerization. Preferably, the resin possesses a weight average molecular weight (M W ) of from 18,000 to 35,000, more preferably 20,000 to 30,000, and a number average molecular weight (M n ) of from 5,000 to 10,000, more preferably 5,000 to 8,000 relative to styrene standards. Of importance with respect to the toner compositions of the present invention is the selection of a acrylonitrile-acrylate-styrene-acrylic acid resin which is obtained from emulsion polymerization of acrylonitrile, acrylate, styrene, and acrylic acid in respective effective amounts of about 1 to 20 weight percent, 10 to 30 weight percent, 55 to 80 weight percent, and 0.5 to 5 weight percent. Illustrative examples of the acrylate monomers utilized in the preparation of acrylonitrile-acrylate-styrene-acrylic acid latex resins for the toner compositions of the present invention include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, and the like. Preferred amounts of the selected resin in the toner compositions of the present invention range from 80 weight percent to 98 weight percent of the toner. Various known colorants or pigments present in the toners in an effective amount of, for example, from 1 to 25 percent by weight of the toner, and preferably in an amount of from 1 to 15 weight percent, that can be selected include carbon black like REGAL 330®; magnetites, such as Mobay magnetites MO8029™, MO8060™; Columbian magnetites; MAPICO BLACK™ and surface treated magnetites; Pfizer magnetites CB4799™, CB5300™, CB5600™, MCX6369™; Bayer magnetites, BAYFERROX 8600™, 8610™; Northern Pigments magnetites, NP-604™, NP-608™; Magnox magnetites TMB-100™, or TMB-104™: As colored pigments, there can be selected cyan, magenta, yellow, red, green, brown, blue or mixtures thereof. The toner may also include known charge additives in effective amounts of, for example, from 0.1 to 5 weight percent such as alkyl pyridinium halides, bisulfates, the charge control additives of U.S. Patents 3,944,493; 4,007,293; 4,079,014; 4,394,430 and 4,560,635, which illustrates a toner with a distearyl dimethyl ammonium methyl sulfate charge additive; nitrobenzene sulfonates; TRH a known charge enhancing additive aluminum complex, BONTRON E-84™ and BONTRON E-88™, and other known charge enhancing additives, and the like. Mixtures of charge additives may also be selected. Surfactants in amounts of, for example, 0.01 to 15 weight percent in embodiments include, for example, nonionic surfactants such as dialkylphenoxypoly(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™. An effective concentration of the nonionic surfactant is in embodiments, for example, from about 0 to 5 percent by weight of total reaction mixture. Examples of ionic surfactants include anionic and cationic with examples of anionic surfactants being, for example, sodium dodecylsulfate, sodium dodecylbenzene sulfonate, sodium dodecylnaphthalene sulfate, dialkyl benzenealkyl, sulfates and sulfonates, abitic acid, available from Aldrich, NEOGEN R™, NEOGEN SC™ obtained from Kao. An effective concentration of the anionic surfactant generally employed is, for example, from 0.01 to 5 percent by weight, and preferably from 0.01 to 3 percent by weight of monomers used to prepare the copolymer resin particles of the emulsion or latex blend. Examples of the cationic surfactants selected for the toners and processes of the present invention include, for example, dialkyl benzenealkyl ammonium chloride, lauryl trimethyl ammonium chloride, alkylbenzyl methyl ammonium chloride, alkyl benzyl dimethyl ammonium bromide, benzalkonium chloride, cetyl pyridinium bromide, C 12 , C 15 , C 17 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, and the like, and mixtures thereof. This surfactant is utilized in various effective amounts, such as for example from 0.01 percent to 5 percent by weight of total reaction mixture. Preferably, the molar ratio of the cationic surfactant used for flocculation to the anionic surfactant used in the latex preparation is in the range of from 0.5 to 4, and preferably from 0.5 to 2. Examples of the additional anionic surfactants which are added just before the coalescence step to prevent further growth in aggregate size with increasing temperature include sodium dodecylbenzene sulfonate, sodium dodecylnaphthalene sulfate, dialkyl benzenealkyl sulfates and sulfonates, available from Aldrich, NEOGEN R™, NEOGEN SC™ obtained from Kao. An effective concentration of the surfactant that serves to stabilize the aggregate size during coalescence ranges, for example, from 0.01 to 5 percent by weight, and preferably from 0.01 to 3 percent by weight of total reaction mixture. Surface additives that can be added to the toner compositions after washing and drying include, for example, those mentioned herein, such as metal salts, metal salts of fatty acids, colloidal silicas, mixtures thereof, which additives are usually present in an amount of from about 0.1 to about 2 weight percent, reference U.S. Patents 3,590,000; 3,720,617; 3,655,374 and 3,983,045. Preferred additives include zinc stearate and AEROSIL R972® available from Degussa in amounts of from 0.1 to 2 percent, which can also be added during the aggregation or coalescence step, the washing or dry blending step wherein additives are mechanically coated onto the surface of the toner product. Developer compositions can be prepared by mixing the toners obtained with the processes of the present invention with known carrier particles, including coated carriers, such as steel, ferrites, and the like, reference U.S. Patents 4,937,166 and 4,935,326, for example from 2 percent toner concentration to 8 percent toner concentration. Imaging methods, especially xerographic imaging and printing processes are also envisioned with the toners of the present invention, and U.S. Patent 4,265,660. EXAMPLE I An organic phase was prepared by dissolving 4.0 grams of carbon tetrabromide in a mixture of 308.0 grams of styrene, 20.0 grams of acrylonitrile, 72.0 grams of butylacrylate, 12.0 grams of acrylic acid, and 14.0 grams of dodecanethiol. An aqueous phase was prepared by mixing an aqueous solution of 4.0 grams of ammonium persulfate in 100 milliliters of water with 500 milliliters of an aqueous solution of 10.0 grams of anionic surfactant, NEOGEN R™ (which contains 60 weight percent of active sodium dodecyl benzene sulfonate in water), and 8.6 grams of nonionic surfactant, ANTAROX CA 897™ (which contains 70 weight percent of active polyoxyethylene nonyl phenyl ether in water). The organic phase was then added to the aqueous phase, and stirred at room temperature, about 25°C, for 30 minutes. Subsequently, the mixture was heated to 70°C at a rate of 1°C per minute, and retained at this temperature for 6 hours. The resulting latex polymer had an M W of 19,400, an M n of 5,100, and a mid-point Tg of 57.0°C. 260 Grams of the above latex emulsion and 230 grams of an aqueous pigment dispersion containing 7.5 grams of dispersed BHD 6000 Sunsperse Cyan Pigment (54.4 weight percent of pigment) obtained from Sun Chemicals, and 2.6 grams of cationic surfactant, SANIZOL B™, were simultaneously added to 400 grams of water with high shear stirring by means of a polytron. The mixture was transferred to a 2 liter reaction vessel and heated at a temperature of 52°C for 1.5 hours before 20 milliliters of 20 percent aqueous NEOGEN R™ solution were added. Subsequently, the mixture was heated to 95°C and retained there for a period of 4 hours, followed by cooling, and isolating the toner by filtration. The resulting toner product showed a particle size of 6.9 microns in volume average diameter, and a GSD of 1.22 as measured with a Coulter Counter. Standard fusing properties of the toner compositions of the present invention were evaluated as follows: unfused images of toner on paper with a controlled toner mass per unit area of 1.2 milligrams/cm 2 were generated as follows. A suitable electrophotographic developer was generated by mixing from 2 to 10 percent by weight of the above prepared 6.9 micron toner in volume average diameter toner with a suitable electrophotographic carrier, such as, for example, a 90 micron diameter ferrite core, spray coated with 0.5 weight percent of a terpolymer of poly(methyl methacrylate), styrene, and vinyltriethoxysilane, and roll milling the mixture for 10 to 30 minutes to produce a tribocharge of between -5 to -20 microcoulombs per gram of toner as measured with a Faraday Cage. The developer was then introduced into a small electrophotographic copier, such as Mita DC-111, in which the fuser system had been disconnected. Between 20 and 50 unfused images of a test pattern consisting of a 65 millimeter by 65 millimeter square solid area were produced on 8 1/2 by 11 inch sheets of a typical electrophotographic paper such as Xerox Image LX paper. The unfused images were then fused by feeding them through a hot roll fuser system consisting of a fuser roll and pressure roll with Viton surfaces, both of which were heated to a controlled temperature. Fused images were produced over a range of hot roll fusing temperatures of from about 130°C to about 210°C. The toner had a gloss, T(G 50 ) of 144°C and an MFT of 136°C. The gloss of the fused images was measured according to TAPPI Standard T480 at a 75° angle of incidence and reflection, using a Novo-Gloss Statistical Glossmeter, Model GL-NG1002S from Paul N. Gardner Company, Inc. The degree of permanence of the fused images was evaluated by the Crease Test. The fused image was folded under a specific weight with the toner image to the inside of the fold. The image was then unfolded and any loose toner wiped from the resulting crease with a cotton swab. The average width of the paper substrate, which shows through the fused toner image in the vicinity of the crease, was measured with a custom built image analysis system. The fusing performance of a given toner is traditionally judged from the fusing temperatures required to achieve acceptable image gloss and fix. For high quality color applications, an image gloss greater than 50 gloss units is preferred. The minimum fuser temperature required to produce a gloss of 50 is defined as T(G 50 ) for a given toner. Similarly, the minimum fuser temperature required to produce a crease value less than the maximum acceptable crease is known as the Minimum Fix Temperature (MFT) for a given toner. In general, it is desirable to have both T(G 50 ) and MFT as low as possible such as below 190°C, and preferably below 170°C, in order to minimize the power requirements of the hot roll fuser and prolong its serviceable life. The toner as prepared in this Example possessed a T(G 50 ) of 139°C and an MFT of 144°C. EXAMPLE II An organic phase was prepared by dissolving 4.0 grams of carbon tetrabromide in a mixture of 280.0 grams of styrene, 20.0 grams of acrylonitrile, 100.0 grams of butylacrylate, 8.0 grams of acrylic acid, and 8.0 grams of dodecanethiol. An aqueous phase was prepared by mixing an aqueous solution of 4.0 grams of ammonium persulfate in 100 milliliters of water with 500 milliliters of an aqueous solution of 10.0 grams of anionic surfactant, NEOGEN R™ (which contains 60 weight percent of active sodium dodecyl benzene sulfonate in water) and 8.6 grams of nonionic surfactant, ANTAROX CA 897™ (which contains 70 weight percent of active polyoxyethylene nonyl phenyl ether in water). The organic phase was then added to the aqueous phase, and stirred at room temperature for 30 minutes. The resulting mixture was heated to 70°C at a rate of 1°C per minute, and retained at this temperature for 6 hours. The resulting latex polymer displayed an M W of 23,900, an M n of 7,900, and a mid-point Tg of 53.7°C. 260 Grams of the above latex emulsion and 230 grams of an aqueous pigment dispersion containing 7.5 grams of dispersed BHD 6000 Sunsperse Cyan Pigment (54.4 weight percent of pigment) obtained from Sun Chemicals, and 2.6 grams of cationic surfactant, SANIZOL B™, were simultaneously added to 400 grams of water with high shear stirring by means of a polytron. The mixture was transferred to a 2 liter reaction vessel and heated at a temperature of 50°C for 1.0 hour before 20 milliliters of 20 percent aqueous NEOGEN R™ solution were added. Subsequently, the mixture was heated to 95°C and held there for a period of 3 hours. The resulting toner product after cooling and isolation evidenced a particle size of 7.1 microns in volume average diameter and a GSD of 1.20 as measured with a Coulter Counter. The toner was evaluated in accordance with the procedure of Example I, and a T(G 50 ) of 137°C and an MFT of 139°C were obtained. EXAMPLE III An organic phase was prepared by dissolving 4.0 grams of carbon tetrabromide in a mixture of 288.0 grams of styrene, 40.0 grams of acrylonitrile, 72.0 grams of butylacrylate, 8.0 grams of acrylic acid, and 8.0 grams of dodecanethiol. An aqueous phase was prepared by mixing an aqueous solution of 4.0 grams of ammonium persulfate in 100 milliliters of water with 500 milliliters of an aqueous solution of 10.0 grams of anionic surfactant, NEOGEN R™ (which contains 60 weight percent of active sodium dodecyl benzene sulfonate in water) and 8.6 grams of nonionic surfactant, ANTAROX CA 897™ (which contains 70 weight percent of active polyoxyethylene nonyl phenyl ether in water). The organic phase was then added to the aqueous phase, and stirred at room temperature for 30 minutes. The resulting mixture was heated to 70°C at a rate of 1°C per minute and retained at this temperature for 6 hours. The resulting latex polymer displayed an M W of 21,300, an M n of 5,600, and a mid-point Tg of 59.8°C. 260 Grams of the above latex emulsion and 230 grams of an aqueous pigment dispersion containing 7.5 grams of dispersed BHD 6000 Sunsperse Cyan Pigment (54.4 weight percent of pigment) obtained from Sun Chemicals, and 2.6 grams of cationic surfactant, SANIZOL B™, were simultaneously added to 400 grams of water with high shear stirring by means of a polytron. The mixture was transferred to a 2 liter reaction vessel and heated at a temperature of 55°C for 2.0 hours before 45 milliliters of 20 percent aqueous NEOGEN R™ solution were added. Subsequently, the mixture was heated to 95°C and held there for a period of 3 hours, followed by cooling to room temperature. The resulting toner product showed a particle size of 7.6 microns and a GSD of 1.24 as measured with a Coulter Counter. The toner was evaluated in accordance with the procedure of Example I, and a T(G 50 ) of 152°C and an MFT of 165°C were obtained. EXAMPLE IV An organic phase was prepared by dissolving 4.0 grams of carbon tetrabromide in a mixture of 220.0 grams of styrene, 80.0 grams of acrylonitrile, 100 grams of butylacrylate, 8.0 grams of acrylic acid, and 12.0 grams of dodecanethiol. An aqueous phase was prepared by mixing an aqueous solution of 4.0 grams of ammonium persulfate in 100 milliliters of water with 500 milliliters of an aqueous solution of 10.0 grams of anionic surfactant, NEOGEN R™ (which contains 60 weight percent of active sodium dodecyl benzene sulfonate in water) and 8.6 grams of nonionic surfactant, ANTAROX CA 897™ (which contains 70 weight percent of active polyoxyethylene nonyl phenyl ether in water). The organic phase was then added to the aqueous phase, and stirred at room temperature for 30 minutes. The resulting mixture was heated to 70°C at a rate of 1°C per minute, and retained at this temperature for 6 hours. The resulting latex polymer displayed an M W of 22,300, an M n of 5,800, and a mid-point Tg of 55.8°C. 260 Grams of the above latex emulsion and 230 grams of an aqueous pigment dispersion containing 7.5 grams of dispersed BHD 6000 Sunsperse Cyan Pigment (54.4 weight percent of pigment) obtained from Sun Chemicals, and 2.6 grams of cationic surfactant, SANIZOL B™, were simultaneously added to 400 grams of water with high shear stirring by means of a polytron. The mixture was transferred to a 2 liter reaction vessel and heated at a temperature of 52°C for 3.0 hours before 30 milliliters of 20 percent aqueous NEOGEN R™ solution were added. Subsequently, the mixture was heated to 95°C and held there for a period of 3 hours, followed by cooling and isolation or separation of the toner. The resulting toner product showed a particle size of 7.0 microns and a GSD of 1.21 as measured with a Coulter Counter. The toner was evaluated in accordance with the procedure of Example I, and a T(G 50 ) of 142°C and an MFT of 146°C were obtained. EXAMPLE V An organic phase was prepared by dissolving 4.0 grams of carbon tetrabromide in a mixture of 260.0 grams of styrene, 60.0 grams of acrylonitrile, 80.0 grams of butylacrylate, 8.0 grams of acrylic acid, and 10.0 grams of dodecanethiol. An aqueous phase was prepared by mixing an aqueous solution of 4.0 grams of ammonium persulfate in 100 milliliters of water with 500 milliliters of an aqueous solution of 10.0 grams of anionic surfactant, NEOGEN R™ (which contains 60 weight percent of active sodium dodecyl benzene sulfonate in water) and 8.6 grams of nonionic surfactant, ANTAROX CA 897™ (which contains 70 weight percent of active polyoxyethylene nonyl phenyl ether in water). The organic phase was then added to the aqueous phase, and stirred at room temperature for 30 minutes. The resulting mixture was heated to 70°C at a rate of 1°C per minute, and held at this temperature for 6 hours. The resulting latex polymer displayed an M W of 23,500, an M n of 6,100, and a mid-point Tg of 56.3°C. 260 Grams of the above latex emulsion and 230 grams of an aqueous pigment dispersion containing 7.5 grams of dispersed BHD 6000 Sunsperse Cyan Pigment (54.4 weight percent of pigment) obtained from Sun Chemicals, and 2.6 grams of cationic surfactant, SANIZOL B™, were simultaneously added to 400 grams of water with high shear stirring by means of a polytron. The mixture was transferred to a 2 liter reaction vessel and heated at a temperature of 54°C for 3.0 hour before 35 milliliters of 20 percent aqueous NEOGEN R™ solution were added. Subsequently, the mixture was heated to 95°C and held there for a period of 3 hours, followed by cooling and isolation of the toner. The resulting toner product showed a particle size of 7.2 microns in volume average diameter and a GSD of 1.26 as measured with a Coulter Counter. The toner was evaluated in accordance with the procedure of Example I, and a T(G 50 ) of 139°C and an MFT of 149°C were obtained.

Claims: A process for the preparation of toner comprising: (i) preparing in the presence of an ionic surfactant and an optional nonionic surfactant a latex emulsion generated from the emulsion polymerization of a mixture of from 55 to 80 weight percent of styrene, from 1 to 25 weight percent of acrylate, from 1 to 20 weight percent of acrylonitrile, and from 0.5 to 5 weight percent of acrylic acid; (ii) mixing said latex emulsion by high shear blending with an aqueous pigment dispersion comprised of pigment and an ionic surfactant that is of opposite charge polarity to the ionic surfactant in said latex emulsion; (iii) heating the resultant flocculant mixture at a temperature that is 30°C below to 10°C above the Tg of the latex resin to form electrostatically bound toner sized aggregates; (iv) subsequently heating said aggregate suspension at a temperature of from 10°C to 50°C above the Tg of the latex resin; and optionally (v) followed by washing, drying, and dry blending the toner with surface additives. The process in accordance with claim 1 wherein the aggregate size, and thus the final toner particle size is from 1 to 20 µm in volume average diameter, and wherein the final toner particle size distribution is narrow as defined by GSD of less than 1.35. The process in accordance with either of claims 1 or 2 wherein the nonionic surfactant is selected from the group consisting of polyvinyl alcohol, 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, and dialkylphenoxy poly(ethyleneoxy)ethanol, and wherein the anionic surfactant is selected from the group consisting of sodium dodecyl sulfate, sodium dodecylbenzene sulfate, and sodium dodecylnaphthalene sulfate.

Inventors: KMIECIK-LAWRYNOWICZ GRAZYNA E, MYCHAJLOWSKIJ WALTER, NG HWEE T, ONG BENG S, PATEL RAJ D, SANDERS DAVID J, KMIECIK-LAWRYNOWICZ, GRAZYNA E., MYCHAJLOWSKIJ, WALTER, NG, HWEE T., ONG, BENG S., PATEL, RAJ D., SANDERS, DAVID J.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1997
Main classification: G03G9
IPC codes: G03G9