Toner preparation process

Abstract: A process for the preparation of toner with a first aggregation of sulfonated polyester, and thereafter a second aggregation with a colorant dispersion and an alkali halide.

Description: The present invention is generally directed to toner processes, and more specifically, to aggregation processes for the preparation of toner resins, especially polyesters, and toner compositions thereof. In embodiments, the present invention is directed to the economical in situ, chemical or direct preparation of toners and toner resins comprising an initial preaggregation of submicron, for example equal to about 1 µm (micron), or less than one µm (micron) in average volume diameter, sized sulfonated polyester particles to a size about equal to that of the colorant dispersion, followed by a second aggregation to toner sized particles without the utilization of the known pulverization and/or classification methods, and wherein in embodiments toner compositions with an average volume diameter of from 1 to 25, and preferably from 1 to 10 µm (microns) and narrow GSD of, for example, from 1.16 to 1.26 or 1.18 to 1.28 as measured on the Coulter Counter can be obtained, and which toners contain certain polyester resins. The stepwise preparation of chemical toners enables, for example, additional process control of the aggregation, thereby reducing colorant rejection, and increasing the latitude of resins that can be aggregated with colorant, especially pigment The resulting toners can be selected for known electrophotographic imaging methods, printing processes, including color processes, digital methods, and lithography. The process of the present invention in embodiments enables the utilization of polymers obtained by polycondensation reactions, such as polyesters, and more specifically, the sulfonated polyesters as illustrated in U.S. Patents 5,348,832; 5,658,704 and 5,604,076, and which polyesters can be selected for low melting toners. There is illustrated in U.S. Patent 4,996,127 a toner of associated particles comprising primarily particles of a polymer with acidic or basic polar groups, and which toners can be prepared by emulsion polymerization. In U.S. Patent 4,983,488, there is disclosed a process for the preparation of toners by the polymerization of a polymerizable monomer dispersed by emulsification in the presence of a colorant and/or a magnetic powder to prepare a principal resin component, and then effecting coagulation of the resulting polymerization liquid in such a manner that the particles in the liquid after coagulation have diameters suitable for a toner. It is indicated in column 9 of this patent that coagulated particles of 1 to 100, and particularly 3 to 70 are obtained. US-A-5 660 965 and US-A-5 593 807 disclose a process for the preparation of toner comprising the step of mixing an emulsion latex comprised of sulfonated polyester, a colorant dispersion and an alkali halide, for aggregation. A feature of the present invention relates to a sequential controlled aggregation of resin with a colorant to enable toners with predictable toner sizes and narrow GSDs. It is another feature of the present invention to provide dry toner compositions comprised of a sulfonated polyester resin and colorant, and which toner is prepared by the initial aggregation of dispersed submicron sulfonated polyester particles to a larger, primary particle size, and the subsequent second aggregation of the polyester and toners thereof comprised, for example, of the sulfonated polyester and a colorant, such as pigment, dye, or mixtures thereof, and toner additives, such as charge additives, surface additives, and the like. In another feature of the present invention there are provided simple and economical chemical processes for the stepwise preparation of black and colored toner compositions with, for example, excellent colorant, such as pigment dispersion and narrow GSD. Another feature of the present invention provides a simple sequential, such as a stepwise process for the preparation of toner size partides in the size range of from 3 to 7 µm (3 to 7 microns) with a narrow GSD in the range of from 1.18 to 1.26, and wherein the toner particles are comprised of a colorant, especially pigment and sulfonated polyester resin, and wherein for the processes there are selected alkali halides, such as beryllium chloride, beryllium bromide, beryllium iodide, magnesium chloride, magnesium bromide, magnesium iodide, calcium chloride, calcium bromide, calcium iodide, strontium chloride, strontium bromide, strontium iodide, barium chloride, barium bromide, barium iodide, and the like. In a further feature of the present invention there is provided a process for the preparation of toner compositions with an average particle volume diameter of from between 1 to 20 µm (1 to 20 microns), and preferably from 1 to 9 µm (1 to about 9 microns), and with a narrow GSD of from 1.12 to 1.30, and preferably from 1.14 to 1.25 as measured by a Coulter Counter, and wherein the initial size of the aggregated sulfonated polyester particles are increased, for example, by 4 to 8 times, like from 20 nanometers to 150 nanometers, or alternatively from 20 nanometers to 150 to 250 nanometers. In another feature of the present invention there is provided a composite toner of sulfonated polymeric resin with colorant, such as pigment and optional charge control agent in high yields of from 90 percent to 100 percent by weight of toner without resorting to classification. In yet another feature of the present invention there are provided toner compositions with low fusing temperatures of from 110°C to 150°C and with excellent blocking characteristics at from 50°C to 60°C. Moreover, in another feature of the present invention there are provided toner compositions with a high projection efficiency, such as from 75 to 95 percent efficiency as measured by the Match Scan II spectrophotometer available from Milton-Roy. In a further feature of the present invention there are provided compositions which in minimal, low or no paper cur. The present invention provides a process for the preparation of a toner comprising a first aggregation of dispersed sulfonated polyester particles and thereafter a second aggregation with a colorant dispersion and an alkali halide. Preferred embodiments of the present invention are set forth in the sub-claims. Embodiments of the present invention relate to a process for the preparation of toner, which process comprises a first aggregation of predispersed submicron sulfonated polyester particles with an alkali halide, and thereafter a second aggregation of the larger submicron sulfonated polyester particles prepared in the first aggregation with a colorant dispersion and an alkali halide; a process for the preparation of toner which comprises a first aggregation of dispersed sulfonated polyester particles resulting in larger submicron sized particles, and thereafter a second aggregation of the resulting sulfonated polyester particles with a colorant dispersion and an alkali halide, and wherein the first aggregation is accomplished by the mixing and heating of the sulfonated polyester and a dicationic salt; and wherein the second aggregation comprises an additional heating and mixing wherein the larger submicron sulfonated polyester particles prepared in the first aggregation together with the colorant, wherein the colorant is a pigment; and the alkali halide is magnesium chloride; a process wherein the partially sulfonated polyester is dispersed from, for example, a 5 to about 50 weight percent solids content in warm water, from 5°C to 15°C above the polyester polymer glass transition temperature, and there is formed submicron particles in the size range of, for example, from 5 to 80 nanometers, and wherein the first aggregation step which is accomplished by the addition of an alkali halide, such as MgCl 2 , or similar dicationic salt solution (1 percent by weight in water) can occur prior or subsequent to heating to the optimum aggregation temperature of from 35°C to 75°C, and which heating can be continued for from 15 to 480 minutes until the desired aggregate particle size is obtained, for example from 70 to 150 nanometers; effecting further aggregation of the resulting preaggregated latex with a dispersed colorant, such as pigment available from Sun Chemical, as an 20 to 50 weight percent of predispersed pigment dispersion in water with a mean pigment size in the range of from 50 to 150 nanometers; and further diluting with water, such as with 150 milliliters of dionized water, and the slow dropwise addition of about 50 milliliters of the alkali halide, such as MgCl 2 or similar dicationic solution, at or near the optimum aggregation temperature is accomplished. The aggregation progress can be monitored by both optical microscopy and Coulter Counter particle size measurements. Further, alkali halide, such as MgCl 2 or similar dicationic salt, can then be added and the temperature increased slightly, for example from 0.2°C to 5°C, thereby permitting a more rapid aggregation. After a period of time, for example from 30 minutes to 5 hours, the desired final toner size, for example from 4 to 8 µm (microns), and narrow particle size distribution (GSD), from 1.1 to 1.5, result. The process of the present invention involves, for example, i) dispersing the sulfonated polyester resin in water, which water is at a temperature of from 40°C to 95°C and preferably between 5°C to 15°C above the polyester glass transition temperature, and which dispersing is accomplished by a high speed shearing polytron device operating at speeds of from 100 to 5,000 revolutions per minute thereby enabling the formation of submicron sized particles, and which particles are of a volume average diameter of from 5 to 80 nanometers; ii) an initial aggregation of the dispersed sulfonated polyester particles to submicron particles of from 50 to 200 nanometers, or more specifically, wherein the particles grow from about 5 to about 50 to about 200 nanometers, or from about 80 to about 90 to about 200 nanometers by the addition of a small amount of a solution containing a dicationic salt; iii) adding a colorant like a pigment dispersion, available from Sun Chemical, as an 20 to 50 weight of predispersed pigment in water with a mean pigment size in the range of 50 to 150 nanometers, which dispersion is further diluted with, for example, 150 to 200 millimeters of Dl (deionized) water, and wherein the aggregation rate can be controlled, for example, by the dropwise addition of alkali halide, such as a dicationic salt, from 1 to 150 milliliters, preferably, 1 percent by weight in water, and with heating near the optimum aggregation temperature, for example between 40°C to 60°C, and preferably between 48°C and 52°C, until optimum toner sized aggregates are obtained as monitored by both optical microscopy and Coulter Counter particle size measurements; iv) optionally, but preferably recovering the toner, or toner particles by known methods, such as filtration; washing, and v) drying the toner particles with, for example, a vacuum; and vi) adding to the dry toner particles, or toner of resin and colorant, known toner additives, such as wax, as charge additives, surface flow additives, and the like. For the process, there can be selected various pigments, dyes, mixtures thereof, and the like, such as cyan, black, magenta, and yellow pigmented dispersions or mixtures thereof obtained, for example, as a predispersed form with, for example, from 20 to 60 weight percent of solids. Disclosed is a process for the preparation of toner, which process comprises a first aggregation of sulfonated polyester and thereafter a second aggregation with a colorant dispersion and an alkali halide. Preferably, the process comprises (i) said sulfonated polyester is dispersed in water, which water is at a temperature of from 40°C to 95°C, or between 5°C to 15°C above the polyester polymer glass transition temperature, and which dispersing is accomplished by a high speed shearing polytron device operating at speeds of from 100 to 5,000 revolutions per minute thereby enabling the formation of submicron sized particles; (ii) accomplishing an initial aggregation of the dispersed sulfonated polyester particles to larger submicron particles of from 50 to 200 nanometers by the addition of a solution containing a monocationic salt, a dicationic salt, or an electrolyte solution; (iii) adding a colorant dispersion with from 20 to 50 weight percent of predispersed colorant in water with a mean colorant size in the range of from 50 to 150 nanometers, and which dispersion is further diluted with deionized water, and controlling the aggregation rate by the dropwise addition of said salt, or said electrolyte, and then heating near the aggregation temperature of from 40°C to 60°C until toner sized aggregates are obtained as monitored by both optical microscopy and Coulter Counter particle size measurements; cooling; and (iv) recovering said toner composition, or said toner particles; (v) drying said toner particles; and (vi) optionally adding to said dry toner particles, or toner of resin and colorant, wax, charge additives, and surface flow additives. It is preferred that the first aggregation is accomplished by heating. It is preferred that the obtained colored toner has a narrow GSD in the range of from 1.18 to 1.28. It is also preferred that the alkali halide is beryllium chloride, beryllium bromide, beryllium iodide, magnesium chloride, magnesium bromide, magnesium iodide, calcium chloride, calcium bromide, calcium iodide, strontium chloride, strontium bromide, strontium iodide, barium chloride, barium bromide, or barium iodide; and the concentration thereof is optionally in the range of from 0.1 to 5 weight percent. The halide is typically chloride, bromide, iodide, or fluoride. The present invention provides also a process for the preparation of a toner, which process comprises a (1) first aggregation of dispersed sulfonated polyester particles and thereafter a (2) second aggregation thereof with a colorant dispersion and an alkali halide, and wherein the first aggregation is accomplished by the mixing and heating of said sulfonated polyester and a dicationic salt, or alkali halide. It is preferred that the colorant is a pigment. It is also preferred that the colorant is a pigment or a dye, and the alkali halide is magnesium chloride. The colorant is usually a cyan, black, magenta, yellow dispersion or mixtures thereof with from 20 to 60 weight percent solids of colorant. Preferably, the sulfonated polyester is of the formula wherein Y is an alkali metal, X is a glycol, and n and m represent the number of segments. Thereby it is preferred that the glycol is neopentyl glycol, ethylene glycol, propylene glycol, butylene glycol, propanediol, diethylene glycol, or mixtures thereof. It is preferred that the first aggregation is accomplished by increasing the ionic strength of the sulfonated polyester by the addition of a monocationic salt. Said salt is preferably sodium chloride. Typically, the sulfonated polyester is a dispersion comprised of from 5 to 30 weight percent solids, and the colorant dispersion contains from 20 to 50 weight percent of colorant. Preferably, the sulfonated polyester has a degree of sulfonation of from 2.5 to 20 mol percent, more preferably, from 5 to 10 mol percent. It is preferred that the toner particle size is from 3 to 7 µm (microns) in volume average diameter. Said toner is typically isolated, filtered, washed with water, and dried. Preferably, there is added to the surface of the formed toner of sulfonated polyester and colorant, 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. It is further preferred that the particle size of the dispersed sulfonated polyester (ii) is from 5 to 200 nanometers. In a preferred embodiment, the polyester is random sulfonated copolyester comprised of, on a mol percent basis of the polymer repeat unit, approximately 0.47 of terephthalate/0.03 of sodium sulfoisophthalate/0.475 of 1,2 propanediol/0.025 of diethylene glycol, and which polyester possesses an M w of about 3,790, an M n of about 2,560, and a Tg of about 54.6°C. The present invention is also directed to a process for the preparation of a toner which comprises a (1) first aggregation of resin particles, and thereafter a (2) second aggregation thereof with a colorant and an alkali halide, and wherein the first aggregation is accomplished by the heating of said resin and said alkali halide. It is preferred that for said first aggregation there is added an alkali halide. It is also preferred that said resins are sulfonated polyester particles of (1) are submicron in size, and heating involves a first heating to enable aggregation, and a second heating to enable coalescence of the toner aggregates formed. The sulfonated polyester is, for example, of the formula wherein Y is an alkali metal, such as a sodium; X is a glycol, such as an aliphatic glycol, or mixture of glycols, such as neopentyl glycol, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, propanediol, especially 1,2-propanediol, diethylene glycol, or mixtures thereof; and n and m represent the number of segments. In embodiments, the first aggregation can be accomplished by an increase in the heating temperature of from 2 to 10°C; the first aggregation can be accomplished by increasing the ionic strength from, for example, 0.001 to 5 and preferably from 0.01 to 2 Molar ionic strength (determined by known methods), of the sulfonated polyester by the addition of, for example, a dicationic salt; wherein the salt selected is magnesium chloride; the sulfonated polyester is a dispersion comprised of 5 to 30 weight percent of solids, and the colorant dispersion is comprised of pigment containing, for example, from 20 to 50 percent solids; the sulfonated polyester possesses a degree of sulfonation of from 2.5 to 20, or from 4 to 15 mol percent; the sulfonated polyester possesses a degree of sulfonation of from 5 to 10 mol percent; the alkali metal halide is comprised of an alkali metal halide, such as for example beryllium chloride, beryllium bromide, beryllium iodide, magnesium chloride, magnesium bromide, magnesium iodide, calcium chloride, calcium bromide, calcium iodide, strontium chloride, strontium bromide, strontium iodide, barium chloride, barium bromide, barium iodide, and the like, and the concentration thereof is optionally in the range of from 0.1 to 5 weight percent; the toner particle size is from 3 to 7 µm (microns) in volume average diameter; the toner is filtered, washed with water, and dried; there is added to the surface of the formed toner of sulfonated polyester and colorant, 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; and the polyester is random sulfonated copolyester comprised of, on a mol percent basis of the polymer repeat unit, approximately 0.47 of terephthalate/0.03 of sodium sulfoisophthalate/0.475 of 1,2 propanediol/0.025 of diethylene glycol, and which polyester possesses an M w of about 3,790, an M n of about 2,560, and a Tg of about 54.6°C. The initial aggregation, or preaggregation can be accomplished by the addition of, for example, a dicationic salt to a previously dispersed sulfonated polyester in an effective amount, for example a salt amount of from 0.05 to 5, and preferably from 0.05 to 1 part or weight percent based on the amount of total components of polyester and salt; or alternatively the initial aggregation can be achieved by an increase in ionic strength from 0.001 M to 2 M (molar) by the addition of from 1 to 50 milliliters of a neutral monocationic salt, such as sodium chloride; or wherein the initial aggregation can be achieved by the use of an electrolyte solution of, for example, Isotone II (Coulter Electronics) in an amount of from 30 milliliters to 50 milliliters; and heating, for example, at a temperature of from 40°C to 60°C, and preferably from 40°C to 45°C. More specifically, the initial aggregation can be accomplished in embodiments as follows: dispersing between 50 and 200 grams of the sulfonated polyester resin in water to yield 5 to 40 weight and preferably 20 weight percent of solids, which water is at a temperature of from 40°C to 95°C, and which dispersing is accomplished by a high speed shearing polytron device operating at speeds of from 100 to 5,000 revolutions per minute thereby enabling the formation of submicron sized particles, and which particles are of a volume average diameter of from 5 to 80 nanometers; optionally followed by the controlled addition of a small amount (between 1 to 50 milliliters) of a 1 weight percent solution containing an alkali salt or alternatively an electrolyte solution, which upon heating the sulfonated polyester/coagulate solution to between 40°C and 60°C and preferably between 40°C and 45°C until an average volume particle size of between 150 to 300 nanometers, and preferably between 160 to 250 nanometers are obtained. Aggregate growth of the latex can be monitored by the particle size growth observed in a Nicomp Particle sizer, and the visible observable size increase with a optical microscope. The latex dispersion changes from a nearly transparent blue-hued solution to a visibly white latex. The advantage of an initial aggregation primarily assures control of the aggregate growth, and control and stability of the aggregation in the colorant, such as pigment, since, for example, the particle sizes of the latex and pigment are similar. In the second aggregation, the predispersed polyester obtained from the first or preaggregation step and a colorant, especially a pigment dispersion, are further aggregated by the use of an alkali halide, such as magnesium chloride. This can be achieved by adding the colorant dispersion to the mixture and controlling the aggregation rate by the controlled addition of dicationic salt, such as MgCl 2 , with heating between 40°C to 60°C and preferably between 48°C to 52°C until optimum toner sized aggregates are obtained. The toner particles are recovered preferably by filtration, followed by vacuum drying the toner particles, and thereafter optionally adding to the dry toner comprised of resin and colorant, known toner additives, such as charge additives, surface flow additives, and the like. Embodiments of the present invention include a process for the preparation of toner particles comprised of resin and colorant, such as pigment, and which process comprises an initial aggregation of the dispersed sulfonated polyester particles to a size similar to the dispersed pigmented particles, followed by a second aggregation to provide particles of 5 to 7 µm (microns) in size diameter; a process for the preparation of toner compositions by a stepwise aggregation comprising: i) dispersing the sulfonated polyester resin in water, which water is at a temperature of from 40°C to 95°C, and which dispersing is accomplished by a high speed shearing polytron device operating at speeds of from 100 to 5,000 revolutions per minute thereby enabling the formation of submicron sized particles, and which particles are of a volume average diameter of from 5 to 80 nanometers; ii) an initial aggregation of the dispersed sulfonated polyester particles to larger submicron particles above (i) of from 50 to 300 nanometers and preferably between 100 to 250 nanometers by the addition of a small (1 to 20 weight percent of the original solution) amount of a solution containing a mono- or dicationic salt, or an electrolyte solution of, for example, Isotone II; iii) adding a pigment dispersion to the mixture resulting and controlling the aggregation rate by, for example, the controlled addition of dicationic salt, such as MgCl 2 , and with heating from 40°C to 60°C, and preferably between 48°C to 52°C, and until toner sized aggregates are obtained; iv) optionally, but preferably recovering the toner composition, or particles by, for example, known methods, such as filtration; v) drying the toner particles with, for example, a vacuum; and vi) optionally adding to the dry toner particles, or toner of resin and colorant toner additives, such as charge additives, surface flow additives, and the like. Various known colorants, especially pigments, present in the toner in an effective amount of, for example, from 1 to 65, preferably from 2 to 35 percent by weight of the toner, and more preferably in an amount of from 1 to 15 weight percent, include carbon black like REGAL 330®; magnetites, such as Mobay magnetites M08029™, MO8060™; and the like. As colored pigments, there can be selected known cyan, magenta, yellow, red, green, brown, blue or mixtures thereof. Specific examples of colorants, especially pigments, indude phthalocyanine HELIOGEN BLUE L6900™, D6840™, D7080™, D7020™, cyan 15:3, magenta Red 81:3, Yellow 17, the pigments of U.S. Patent 5,556,727, and the like. More 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. Colorants include pigments, dyes, mixtures of pigments, mixtures of dyes, and mixtures of dyes and pigments, and the like, and preferably pigments. 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, negative charge enhancing additives like aluminum complexes, and the like. Surface additives that can be added to the toner compositions after washing or drying include, for example, metal salts, metal salts of fatty acids, colloidal silicas, metal oxides like titanium, tin and the like, mixtures thereof and the like, which additives are usually present in an amount of from 0.1 to 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 flow aids, such as fumed silicas like AEROSIL R972® available from Degussa, or silicas available from Cabot Corporation or Degussa Chemicals, each in amounts of from 0.1 to 2 percent, which can be added during the aggregation process or blended into the formed 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 are also envisioned with the toners of the present invention, reference for example a number of the patents mentioned herein, and U.S. Patent 4,265,990. The following Examples are being submitted to further define various species of the present invention. Also, parts and percentages are by weight unless otherwise indicated. EXPERIMENTAL PREPARATION OF SULFONATED POLYESTERS: Preparation of Linear Moderately Sulfonated Polyester A (DF209): A linear sulfonated random copolyester resin comprised of, on a mol percent, approximately 0.47 of terephthalate, 0.030 of sodium sulfoisophthalate, 0.455 of neopentyl glycol, and 0.045 of diethylene glycol was prepared as follows. In a one liter Parr reactor equipped with a bottom drain valve, double turbine agitator, and distillation receiver with a cold water condenser were charged 388 grams of dimethylterephthalate, 44.55 grams of sodium dimethylsulfoisophthalate, 310.94 grams of neopentyl glycol (1 mole excess of glycols), 22.36 grams of diethylene glycol (1 mole excess of glycols), and 0.8 gram of butyltin hydroxide oxide as the catalyst. The reactor was then heated to 165°C with stirring for 3 hours whereby 115 grams of distillate were collected in the distillation receiver, and which distillate was comprised of about 98 percent by volume of methanol and 2 percent by volume of neopentylglycol as measured by the ABBE refractometer available from American Optical Corporation. The resulting mixture was then heated to 190°C over a one hour period, after which the pressure was slowly reduced from atmospheric pressure to about 34.7 kPa (260 Torr) over a one hour period, and then reduced to 0.67 kPa (5 Torr) over a two hour period with the collection of approximately 122 grams of distillate in the distillation receiver, and which distillate was comprised of approximately 97 percent by volume of neopentylglycol and 3 percent by volume of methanol as measured by the ABBE refractometer. The pressure was then further reduced to about 0.13 kPa (1 Torr) over a 30 minute period whereby an additional 16 grams of neopentylglycol were collected. The reactor was then purged with nitrogen to atmospheric pressure, and the polymer discharged through the bottom drain onto a container cooled with dry ice to yield 460 grams of the 3.0 mol percent sulfonated polyester resin, copoly(neopentylene-diethylene)terephthalate-copoly(sodium sulfoisophthalate dicarboxylate). The sulfonated polyester resin glass transition temperature was measured to be 54.7°C (onset) utilizing the 910 Differential Scanning Calorimeter available from E.I. DuPont operating at a heating rate of 10°C per minute. The sulfonated polyester product number average molecular weight was measured to be 2,560 grams per mole, and the weight average molecular weight was measured to be 3,790 grams per mole using tetrahydrofuran as the solvent. A particle size of 31 nanometers (volume weighted) was measured using a Nicomp particle sizer. Preparation of Linear Moderately Sulfonated Polyester B (DF210): A linear sulfonated random copolyester resin comprised of, on a mol percent, approximately 0.465 of terephthalate, 0.035 of sodium sulfoisophthalate, 0.475 of 1,2-propanediol, and 0.025 of diethylene glycol was prepared as follows. In a one liter Parr reactor equipped with a bottom drain valve, double turbine agitator, and distillation receiver with a cold water condenser were charged 388 grams of dimethylterephthalate, 44.55 grams of sodium dimethylsulfoisophthalate, 310.94 grams of 1,2-propanediol (1 mole excess of glycols), 22.36 grams of diethylene glycol (1 mole excess of glycols), and 0.8 gram of butyltin hydroxide oxide as the catalyst. The reactor was then heated to 165°C with stirring for 3 hours whereby 115 grams of distillate were collected in the distillation receiver, and which distillate was comprised of about 98 percent by volume of methanol and 2 percent by volume of 1,2-propanediol as measured by the ABBE refractometer available from American Optical Corporation. The mixture was then heated to 190°C over a one hour period, after which the pressure was slowly reduced from atmospheric pressure to about 34.7 kPa (260 Torr) over a one hour period, and then reduced to 0.67 kPa (5 Torr) over a two hour period with the collection of approximately 122 grams of distillate in the distillation receiver, and which distillate was comprised of approximately 97 percent by volume of 1,2-propanediol and 3 percent by volume of methanol as measured by the ABBE refractometer. The pressure was then further reduced to about 0.13 kPa (1 Torr) over a 30 minute period whereby an additional 16 grams of 1,2-propanediol were collected. The reactor was then purged with nitrogen to atmospheric pressure, and the polymer discharged through the bottom drain onto a container cooled with dry ice to yield 460 grams of the 3.5 mol percent sulfonated polyester resin, copoly(1,2-propylene-diethylene)terephthalate-copoly(sodium sulfoisophthalate dicarboxylate). The sulfonated polyester resin glass transition temperature was measured to be 59.5°C (onset) utilizing the 910 Differential Scanning Calorimeter available from E.I. DuPont operating at a heating rate of 10°C per minute. The sulfonated polyester product number average molecular weight was measured to be 3,250 grams per mole, and the weight average molecular weight was measured to be 5,290 grams per mole using tetrahydrofuran as the solvent. A particle size of 57 nanometers (volume weighted) was measured using a Nicomp particle sizer. Preparation of Latex Stock Solutions: Submicron dispersions of the appropriate sulfonated polyester, such as those prepared above, in distilled deionized water were prepared by first heating the water to 10°C to 15°C above the glass transition temperature of the sulfonated polyester polymer and then slowly adding the polymer with stirring until it has fully dispersed. The latexes usually had a characteristic blue tinge and particle sizes in the range of from 5 to 150 nanometers. Stock solutions are stable indefinitely. PREPARATION OF CHEMICAL TONERS VIA A STEPWISE AGGREGATION PROCESS EXAMPLE I An Emulsion Aggregation Stepwise Procedure to Prepare a Cyan Chemical Toner with MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester solids with the polyester A (DF209) prepared above and a particle size of 31 nanometers was introduced into a 1 liter reaction kettle, along with 70 milliliters of a 1 percent solution of MgCl 2 in distilled deionized water. The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex had grown from 31 to 120 nanometers. The growth of the particles was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the cyan dispersion (Sun Chemical 40 percent solids), mean pigment size of 90 nanometers, was further dispersed with 150 milliliters of distilled deionized water and was then added to the above latex particles. Fifty (50) additional milliliters of the 1 percent MgCl 2 were then added dropwise to the solution and the temperature retained at about 50°C for 5 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 3.0 µm (microns). An additional 20 milliliters of the 1 percent MgCl 2 solution were added dropwise and the temperature increased to 52°C. After 2 hours, a sample of about 5 grams was removed and observed under a microscope, and there were revealed spherical toner particles containing both pigment and polymer. A final cyan toner, particle size of 5.0 µm (microns) with a GSD of 1.3, resulted with the toner being comprised of 96.25 weight percent of the sulfonated polyester A (DF209) and 3.5 weight percent of the cyan pigment EXAMPLE II An Emulsion Aggregation Stepwise Procedure to Prepare a Cyan Chemical Toner with Electrolyte and MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester B (DF210) prepared above solids and a particle size of 31 nanometers was introduced into an one liter reaction kettle, along with 30 milliliters of Isotone II (a coulter electrolyte solution). The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex grew from 31 nanometers to 120 nanometers. The growth of the particle was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the cyan dispersion (Sun Chemical 40 percent solids), with a mean pigment size of 90 nanometers, were further dispersed with a 150 milliliters of distilled deionized water, and then added to the above Latex A particles. 50 Milliliters of the 1 percent MgCl 2 were added dropwise to the resulting solution and the temperature retained at about 50°C for a period of 11.75 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 2.7 µm (microns). An additional 15 milliliters of the 1 percent MgCl 2 solution were added dropwise and the temperature increased to 52°C. After 2 hours, a sample was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final cyan toner with a particle size of 4.1 µm (microns) and a GSD of 1.2 was obtained, and which toner was comprised of 96.25 weight percent of the sulfonated polyester A (DF210) and 3.5 weight percent of the cyan pigment. EXAMPLE III An Emulsion Aggregation Stepwise Procedure to Prepare a Cyan Chemical Toner with NaCl and MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester A (DF209) or B (DF210) prepared above solids and a particle size of 31 nanometers was introduced into a 1 liter reaction kettle along with 31 milliliters of a 1 weight percent NaCI solution. The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex grew from 30 to 120 nanometers. The growth of the particle was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the cyan dispersion (Sun Chemical 40 percent solids), mean pigment size of 90 nanometers, was further dispersed with 150 milliliters of distilled deionized water and was then added to the above latex particles. 50 Milliliters of the 1 percent MgCl 2 were added dropwise to the resulting solution and the temperature held between 45°C to 50°C for a period of 11.75 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 2.7 µm (microns). An additional 15 milliliters of the 1 percent MgCl 2 solution was added dropwise and the temperature increased to 52°C. After 2 hours, a sample was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final cyan toner, particles size of 4.1 µm (microns) and a GSD of 1.2, was obtained with the toner being comprised of 96.25 weight percent of the sulfonated polyester and 3.5 weight percent of the cyan pigment. EXAMPLE IV An Emulsion Aggregation Stepwise Procedure to Prepare a Magenta Chemical Toner with MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester A (DF209) or B (DF210) prepared above solids and a particle size of 31 nanometers was introduced into a 1 liter reaction kettle along with 70 milliliters of a 1 percent solution of MgCl 2 in distilled deionized water. The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex had grown from 31 to 120 nanometers. The growth of the particles was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the magenta dispersion (Sun Chemical 40 percent solids), with a mean pigment size of 80 nanometers, were further dispersed with 150 milliliters of distilled deionized water and then added to the above latex particles. Fifty more milliliters of the 1 percent MgCl 2 were added dropwise to the resulting solution and the temperature held at about 50°C for 5 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 3.0 µm (microns). An additional 20 milliliters of the 1 percent MgCl 2 solution were added dropwise and the temperature increased to 52 °C. After 2 hours, a sample, about 10 grams, was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final magenta toner with a particle size of 5.0 µm (microns) and a GSD of 1.3 resulted. The aforementioned resulting toner was comprised of 95.0 weight percent of the sulfonated polyester and 5.0 weight percent of the magenta pigment. EXAMPLE V An Emulsion Aggregation Stepwise Procedure to Prepare a Magenta Chemical Toner with Electrolyte and MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester A (DF209) or B (DF210) prepared above solids and a particle size of 31 nanometers was introduced into a 1 liter reaction kettle along with 30 milliliters of Isotone II (a coulter electrolyte solution). The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex grew from 31 to 120 nanometers. The growth of the particle was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the magenta dispersion (Sun Chemical 40 percent solids), with a mean pigment size of 90 nanometers, further dispersed with 150 milliliters of distilled deionized water were then added to the above latex particles. 50 Milliliters of the 1 percent MgCl 2 were added dropwise to the solution and the temperature held to about 50°C for a period of 11.75 hours. The growth in pigmented particles was dearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 2.7 µm (microns). An additional 15 milliliters of the 1 percent MgCl 2 solution were added dropwise and the temperature increased to 52°C. After 2 hours, a sample was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final magenta toner with a size of 4.1 µm (microns) and a GSD of 1.2 was obtained, and wherein the toner was comprised of 95.0 weight percent of the sulfonated polyester and 5.0 weight percent of magenta pigment EXAMPLE VI An Emulsion Aggregation Stepwise Procedure to Prepare a Magenta Chemical Toner with NaCl and MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester A (DF209) or B (DF210) prepared above solids and a particle size of 30 nanometers was introduced into a 1 liter reaction kettle along with 30 milliliters of a one weight percent NaCI solution. The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex grew from 30 to 120 nanometers. The growth of the particles were also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the magenta dispersion (Sun Chemical 40 percent solids) with a mean pigment size of 90 nanometers further dispersed with a 150 milliliters of distilled deionized water were then added to the latex particles. 50 Milliliters of the 1 percent MgCl 2 were added dropwise to the resulting solution and the temperature held at about 50°C for a period of 11.75 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 2.7 µm (microns). An additional 15 milliliters of the 1 percent MgCl 2 solution was added dropwise and the temperature increased to 52°C. After 2 hours, a sample was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final magenta toner particle size of 4.1 µm (microns) with a GSD of 1.2 was obtained, and wherein the toner was comprised of 95.0 weight percent of the sulfonated polyester and 5.0 weight percent of the magenta pigment. EXAMPLE VII An Emulsion Aggregation Stepwise Procedure to Prepare a Black Chemical Toner with MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester A (DF209) or B (DF210) prepared above solids and a particle size of 31 nanometers was introduced into a 1 liter reaction kettle along with 70 milliliters of a 1 percent solution of MgCl 2 in distilled deionized water. The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex had grown from 31 to 120 nanometers. The growth of the particle was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the black dispersion (Sun Chemical 40 percent solids) with a mean pigment size of 90 nanometers further were dispersed with 150 milliliters of distilled deionized water and then added to the latex particles. Fifty more milliliters of the 1 percent MgCl 2 were added dropwise to the solution and the temperature held at about 50°C for 5 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 3.0 µm (microns) An additional 20 milliliters of the 1 percent MgCl 2 solution were added dropwise and the temperature increased to 52°C. After 2 hours, a sample was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final black toner particle size of 5.0 µm (microns) with a GSD of 1.3 was obtained, and which toner was comprised of 94.0 weight percent of the sulfonated polyester and 6.0 weight percent of the above black pigment. EXAMPLE VIII An Emulsion Aggregation Stepwise Procedure to Prepare a Black Chemical Toner with Electrolyte and MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester A (DF209) or B (DF210) prepared above solids and a particle size of 31 nanometers was introduced into a 1 liter reaction kettle along with 30 milliliters of Isotone II (a coulter electrolyte solution). The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex grew from 31 to 120 nanometers. The growth of the particle was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the yellow dispersion (Sun Chemical 40 percent solids) with a mean pigment size of 90 nanometers were further dispersed with 150 milliliters of distilled deionized water and then added to the latex particles. 50 Milliliters of the 1 percent MgCl 2 were added dropwise to the solution and the temperature held at about 50°C for a period of 11.75 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 2.7 µm (microns). An additional 15 milliliters of the 1 percent MgCl 2 solution were added dropwise and the temperature increased to 52°C. After 2 hours, a sample was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final black toner particle size of 4.1 µm (microns) in volume average throughout and as determined by a Coulter Counter with a GSD of 1.2 was observed, and this toner contained 94.0 weight percent of the sulfonated polyester and 6.0 weight percent of black pigment. EXAMPLE IX An Emulsion Aggregation Stepwise Procedure to Prepare a Black Chemical Toner with NaCl and MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester A (DF209) prepared above solids and a particle size of 31 nanometers was introduced into a 1 liter reaction kettle together with 30 milliliters of a one weight percent NaCI solution. The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex grew from 31 to 120 nanometers. The growth of the particles was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the black dispersion (Sun Chemical 40 percent solids) with a mean pigment size of 90 nanometers were further dispersed with 150 milliliters of distilled deionized water and then added to the latex particles. 50 Milliliters of the 1 percent MgCl 2 were added dropwise to the solution and the temperature held at about 50°C for a period of 11.75 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 2.7 µm (microns). An additional 15 milliliters of the 1 percent MgCl 2 solution were added dropwise and the temperature increased to 52°C. After 2 hours, a sample was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final black toner particle size of 4.1 µm (microns) with a GSD of 1.2 was observed. This toner contained 94.0 weight percent of the sulfonated polyester and 6.0 weight percent of black pigment EXAMPLE X An Emulsion Aggregation Stepwise Procedure to Prepare a Yellow Chemical Toner with MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester A (DF209) prepared above solids and a particle size of 31 nanometers was introduced into a 1 liter reaction kettle along with 70 milliliters of a 1 percent solution of MgCl 2 in distilled deionized water. The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex had grown from 31 to 120 nanometers. The growth of the particles was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the yellow dispersion (Sun Chemical 40 percent solids) with mean pigment size of 90 nanometers were further dispersed with a 150 milliliters of distilled deionized water and then added to the latex particles. Fifty more milliliters of the 1 percent MgCl 2 were added dropwise to the solution and the temperature held at about 50°C for 5 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 3.0 µm (microns). An additional 20 milliliters of the 1 percent MgCl 2 solution were added dropwise and the temperature increased to 52°C. After 2 hours, a sample was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final yellow toner particle size of 5.0 µm (microns) with a GSD of 1.3 was observed, and the toner contained 92.0 weight percent of the sulfonated polyester and 8.0 weight percent of yellow pigment. EXAMPLE XI An Emulsion Aggregation Stepwise Procedure to Prepare a Yellow Chemical Toner with Electrolyte and MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester A (DF209) prepared above solids and a particle size of 31 nanometers was introduced into a 1 liter reaction kettle along with 30 milliliters of Isotone II (a coulter electrolyte solution). The reaction kettle was heated to about 45°C for 3 hours. The particle size of the latex grew from 31 to 120 nanometers. The growth of the particles was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the yellow dispersion (Sun Chemical 40 percent solids) whose mean pigment size of 90 nanometers was further dispersed with a 150 milliliters of distilled deionized water and then added to the latex particles. 50 Milliliters of the 1 percent MgCl 2 were added dropwise to the solution and the temperature held at about 50°C for a period of 11.75 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 2.7 µm (microns). An additional 15 milliliters of the 1 percent MgCl 2 solution were added dropwise and the temperature increased to 52°C. After 2 hours, a sample was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final yellow toner with a particle size of 4.1 µm (microns) and a GSD of 1.2 was observed, and wherein this yellow toner contained 92.0 weight percent of the sulfonated polyester and 8.0 weight percent of yellow pigment. EXAMPLE XII An Emulsion Aggregation Stepwise Procedure to Prepare a Yellow Chemical Toner with NaCI and MgCl 2 : A 150 milliliter solution of Latex A containing 20 percent by weight of predispersed sulfonated polyester A (DF209) prepared above solids and a particle size of 31 nanometers was introduced into a 1 liter reaction kettle, along with 30 milliliters of a one weight percent NaCI solution. The reaction kettle was heated to between 50°C to 52°C for 3 hours. The particle size of the latex increased from 31 to 120 nanometers. The growth of the particles was also apparent by the transition from a nearly clear blue tinged solution to visible white submicron latex particles. 3.0 Grams of the yellow dispersion (Sun Chemical 40 percent solids) with a mean pigment size of 90 nanometers was further dispersed with a 150 milliliters of distilled deionized water and was then added to the latex particles. 50 Milliliters of the 1 percent MgCl 2 were added dropwise to the solution and the temperature held between 45°C to 50°C for a period of 11.75 hours. The growth in pigmented particles was clearly visible in a laboratory microscope and the particle size, as measured on a Coulter Counter, was 2.7 µm (microns). An additional 15 milliliters of the 1 percent MgCl 2 solution were added dropwise and the temperature increased to 52°C. After 2 hours, a sample was removed and observed under a microscope which revealed spherical particles containing both pigment and polymer. A final yellow toner with a particle size of 4.1 µm (microns) and with a GSD of 1.2 was obtained, and which toner contained 92.0 weight percent of the sulfonated polyester and 8.0 weight percent of yellow pigment

Claims: A process for the preparation of a toner comprising a first aggregation of dispersed sulfonated polyester particles and thereafter a second aggregation with a colorant dispersion and an alkali halide. The process of claim 1 wherein said sulfonated polyester is in the form of dispersed particles, and wherein the first aggregation is accomplished by the mixing and heating of said sulfonated polyester and a dicationic salt, or alkali halide. The process of claim 1 wherein (i) said sulfonated polyester is dispersed in water, which water is at a temperature of from 40°C to 95°C, or between 5°C to 15°C above the polyester polymer glass transition temperature, and which dispersing is accomplished by a high speed shearing polytron device operating at speeds of from 100 to 5,000 revolutions per minute thereby enabling the formation of submicron sized particles; (ii) accomplishing an initial aggregation of the dispersed sulfonated polyester particles to larger submicron particles of from 50 to 200 nanometers by the addition of a solution containing a monocationic salt, a dicationic salt, or an electrolyte solution; (iii) adding a colorant dispersion with from 20 to 50 weight percent of predispersed colorant in water with a mean colorant size in the range of from 50 to 150 nanometers, and which dispersion is further diluted with deionized water, and controlling the aggregation rate by the dropwise addition of said salt, or said electrolyte, and then heating near the aggregation temperature of from 40°C to 60°C until toner sized aggregates are obtained as monitored by both optical microscopy and Coulter Counter particle size measurements; cooling; and (iv) recovering said toner composition, or said toner particles; and (v) drying said toner particles. The process of claim 2 wherein the sulfonated polyester is of the formula wherein Y is an alkali metal, X is a glycol, and n and m represent the number of segments. The process of claim 2 or 4 wherein the first aggregation is accomplished by increasing the ionic strength of the sulfonated polyester by the addition of a monocationic salt. The process of claim 1 or 3 wherein there is obtained a colored toner with a narrow GSD in the range of from 1.18 to 1.28. The process of any of claims 2, 4 or 5 wherein there is added to the surface of the formed toner of sulfonated polyester and colorant, 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. The process of any of claims 2, 4, 5 or 7 wherein the polyester is random sulfonated copolyester comprised of, on a mol percent basis of the polymer repeat unit, approximately 0.47 of terephthalate/0.03 of sodium sulfoisophthalate/0.475 of 1,2 propanediol/0.025 of diethylene glycol, and which polyester possesses an M w of about 3,790, an M n of about 2,560, and a Tg of about 54.6°C.

Inventors: FOUCHER DANIEL A, MYCHAIJLOWSKIJ WALTER, PATEL RAJ D, SACRIPANTE GUERINO G, FOUCHER, DANIEL A., MYCHAIJLOWSKIJ, WALTER, PATEL, RAJ D., SACRIPANTE, GUERINO G.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1999
Main classification: G03G9
IPC codes: G03G9