JP2005345734A - Method for manufacturing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing toner having uniform particle shape and size and excellent characteristics as an electrostatic charge developing toner, by which coarsening of toner particles by sticking can be prevented and a component giving adverse influences on the electrification performance of the toner is prevented from remaining in the toner particles. <P>SOLUTION: The method for manufacturing toner includes: a synthetic resin particle production step of mixing a resin kneaded material which can be granulated in a melted state and contains at least a synthetic resin and a coloring agent but no organic solvent, in water in the presence of a water-soluble polymer dispersant while heating or heating and pressurizing to produce synthetic resin particles containing the colorant; and a cooling step of cooling a mixture containing the synthetic resin particles containing the colorant in the presence of a water dispersion liquid containing a hardly water-soluble alkaline earth metal salt. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a toner manufacturing method.

  As OA devices have been remarkably developed, printers, facsimiles, copiers, and the like that perform image formation using an electrophotographic system that is high-speed and excellent in image quality have become widespread. In the electrophotographic system, an electrostatic charge image is formed on the surface of a photoconductor using a photoconductive substance by various means, the electrostatic charge image is developed with toner, and the toner image is transferred to paper or the like. Image formation is performed by fixing to a material.

  Manufacturing methods of toner for developing an electrostatic image (hereinafter referred to as “electrostatic image developing toner”) are roughly classified into a dry method and a wet method. Examples of the dry method include a pulverization method. In the pulverization method, a binder resin and a colorant are kneaded and pulverized and classified. Since the toner obtained by the dry method has a relatively wide particle size distribution, the charging performance tends to vary. When an image is formed using toner with varying charging performance, for example, color unevenness occurs in the formed image, which is not preferable.

  On the other hand, in the wet method, a toner having a small particle size distribution and a small variation in charging performance can be manufactured relatively easily. Therefore, the wet method is often used for manufacturing the toner.

  Examples of the wet method include a suspension polymerization method, an emulsion polymerization aggregation method, a phase inversion emulsification method, a dissolution suspension method, and an emulsion dispersion method. (1) In the suspension polymerization method, a binder resin monomer dispersed in a dispersion medium by a suspension stabilizer is polymerized in the presence of a colorant, and the resulting binder resin particles include the colorant. This is a method for obtaining toner. (2) The emulsion polymerization aggregation method is a method in which a resin dispersion and a colorant dispersion in which a colorant is dispersed in a dispersion medium are mixed to form aggregated particles, and the aggregated particles are heated and fused to obtain a toner. It is. (3) In the phase inversion emulsification method, a water-dispersible resin and a colorant are dissolved or dispersed in an organic solvent, and a neutralizing agent and water for neutralizing the dissociating group of the water-dispersible resin are added to the solution. In this method, resin droplets containing a colorant and the like are generated and phase-inverted and emulsified to obtain a toner. (4) In the dissolution suspension method, a binder resin and a colorant are dissolved or dispersed in an organic solvent in which the binder resin can be dissolved, and a water-insoluble alkaline earth metal salt such as calcium phosphate or calcium carbonate is dissolved. This is a method in which an aqueous dispersion is mixed and granulated, and an organic solvent is removed to obtain a toner (for example, see Patent Documents 1 to 7). (5) In the emulsification dispersion method, a binder resin and a colorant are dissolved or dispersed in a water-insoluble organic solvent, and this solution or dispersion is emulsified and dispersed in an aqueous dispersion, and then the organic solvent is removed to remove the toner. (See, for example, Patent Documents 8 to 13).

  However, there are also problems to be solved by the wet method. For example, depending on the pressure (reduced pressure), temperature, and time when removing the organic solvent that dissolves or disperses the binder resin, the shape of the toner particles becomes non-uniform, and the charging performance varies. In addition, a small amount of an organic solvent for dissolving or dispersing the binder resin, a monomer of the binder resin, and the like may remain in the obtained toner particles, thereby varying the charging performance of the toner particles. For example, in the above suspension polymerization method, suspension stabilizers and monomers remain on the surface of the obtained toner particles, thereby deteriorating the charging performance of the toner particles. The removal of the suspension stabilizer and the monomer requires a complicated process and increases the production cost of the toner. Furthermore, organic solvents, binder resin monomers, and the like that are frequently used in the wet method have a large environmental load, which requires processing equipment and increases manufacturing costs.

  In addition, as a wet method, without using an organic solvent, a melt of a resin having an ionic group and a colorant and an aqueous medium containing a substance that neutralizes the ionic group are mixed under heat and pressure. A method for obtaining toner is also known (see, for example, Patent Document 14). When this method is used, the residual components such as the organic solvent and the monomer which deteriorate the charging performance do not occur, but there is a problem that the toner particles to be produced adhere and become coarse. In order to prevent this, it is necessary to precisely control various conditions such as the liquid temperature in the mixed system after mixing, but in reality such control is very difficult.

  The toner obtained by these methods has a high level of characteristics such as the image quality (image density, presence or absence of white background fogging) of the image formed on the transfer material and the transfer rate to the transfer material. is not.

JP-A-7-152202 JP-A-7-168395 JP-A-7-168396 JP 7-219267 A JP-A-8-179555 JP-A-8-179556 Japanese Patent Laid-Open No. 9-230624 JP-A-7-325429 JP-A-7-325430 JP 7-333890 A JP-A-7-333899 JP 7-333901 A JP 7-333902 A Japanese Patent No. 3351505

  When toner is manufactured by a wet method, if organic solvents, binder resin monomers, etc. are used, the final shape of the resulting toner becomes non-uniform due to the removal of these substances, and the charging performance varies. Cause problems.

  On the other hand, a method for obtaining a toner by mixing a melt of a resin having an ionic group and a colorant and an aqueous medium containing a substance that neutralizes the ionic group under heating and pressure without using an organic solvent. According to this, there is a problem that toner particles to be produced adhere to each other and become coarse.

  In addition, the toner obtained by these methods has a high level of characteristics such as the image quality (image density, presence or absence of white background fogging) of the image formed on the transfer material, and the transfer rate to the transfer material. It is not something you have.

  An object of the present invention is to prevent coarsening due to adhering toner particles to be produced, and to prevent a component that adversely affects the charging performance of the toner from remaining in the toner particles. To provide a method for producing a toner which is uniform and excellent in various characteristics as an electrostatic charge developing toner.

The present invention relates to a synthetic resin particle that generates an aqueous slurry containing a colorant-containing synthetic resin particle by heating or heat-pressing a resin kneaded material containing at least a synthetic resin and a colorant that can be granulated in a molten state in water. Generation process;
And a cooling step of cooling an aqueous slurry containing the colorant-containing synthetic resin particles.
The resin kneaded product does not contain an organic solvent,
Generating colorant-containing synthetic resin particles in the presence of a water-soluble polymer dispersant in the synthetic resin particle generation step;
In the cooling step, a toner dispersion method is characterized in that an aqueous dispersion containing a hardly water-soluble alkaline earth metal salt is added to an aqueous slurry containing colorant-containing synthetic resin particles.

  According to the present invention, the toner of the present invention is produced by a production process comprising a synthetic resin particle production process for producing colorant-containing synthetic resin particles and a cooling process for cooling an aqueous slurry containing the colorant-containing synthetic resin particles. .

  In this synthetic resin particle production step, a colorant is obtained by heating or heat-pressing a resin kneaded product containing at least a synthetic resin and a colorant that can be granulated in a molten state in water containing a water-soluble polymer dispersant. An aqueous slurry containing the contained synthetic resin particles can be generated. Since a water-soluble polymer dispersant is present in water, the dispersion system is stable, and colorant-containing synthetic resin particles that are fine particles of uniform shape can be generated.

  Moreover, as a synthetic resin contained in the resin kneaded material, a synthetic resin that can be granulated in a molten state may be used, and it is not necessary to use a synthetic resin that dissolves in an organic solvent. Accordingly, the synthetic resin can be selected from a wide range of synthetic resins that can be granulated in a molten state in consideration of the low-temperature fixability and durability of the toner particles finally obtained. Further, since it is not necessary to use a synthetic resin that dissolves in an organic solvent, an organic solvent that adversely affects charging performance does not remain in the toner particles. Therefore, there is no need to provide a step for removing the organic solvent, and the synthetic resin particles from which the organic solvent has been removed, which has been a problem in the conventional toner manufacturing method using the organic solvent, are subjected to treatment such as classification and drying. Therefore, there is no problem that the shape of the toner particles finally obtained is non-uniform.

  In the cooling step described above, by adding an aqueous dispersion containing a poorly water-soluble alkaline earth metal salt to an aqueous slurry containing colorant-containing synthetic resin particles, preventing coarsening due to toner particles adhering to each other Can do.

  Furthermore, the removal of the hardly water-soluble alkaline earth metal salt from the surface of the colorant-containing synthetic resin particles can be performed by a simple operation of adding an aqueous solution containing an ionic substance to the aqueous slurry. Is advantageous. The surface of the particles from which the hardly water-soluble alkaline earth metal salt has been removed is in a smooth state having no irregularities due to the adhesion of the hardly water-soluble alkaline earth metal salt.

  In order to remove the hardly water-soluble alkaline earth metal salt dissolved by the water-soluble polymer dispersant and the ionic substance in the aqueous slurry from the aqueous slurry, for example, a simple operation of washing with water is performed. Well, industrially advantageous.

  The toner particles obtained by the production method of the present invention have a volume average particle diameter of about 3 to 15 μm, a uniform particle shape and size, and no variation in charging performance. For example, electrophotographic image formation It can be preferably used as an electrostatic charge developing toner for an apparatus. When the toner particles are used in an electrophotographic image forming apparatus, the toner particles are transferred to a transfer material at a high rate, and an image with high image density and no white background fog can be easily formed.

  In addition, the present invention is characterized in that at least one of a polycarboxylic acid compound and polyvinyl alcohol is used as the water-soluble polymer dispersant.

  According to the present invention, at least one of a polycarboxylic acid compound and polyvinyl alcohol can be preferably used as the water-soluble polymer dispersant. When these compounds are used, the resin kneaded material is easily atomized, and colorant-containing synthetic resin particles having a uniform shape and size that are smooth and free from cracks can be obtained particularly efficiently. In particular, since the polycarboxylic acid compound is easily soluble in water, concentration adjustment and washing are easy.

  In addition, the present invention is characterized in that the addition amount of the hardly water-soluble alkaline earth metal salt is in the range of 10 to 250 parts by weight with respect to 100 parts by weight of the resin kneaded product.

  According to the present invention, when the addition amount of the hardly water-soluble alkaline earth metal salt is in the range of 10 parts by weight or more and 250 parts by weight or less with respect to 100 parts by weight of the resin kneaded material, the aggregated and coarsened colorant is contained. Synthetic resin particles are not generated.

  In the present invention, the poorly water-soluble alkaline earth metal salt is at least one of a calcium carbonate salt and a calcium phosphate salt.

  According to the present invention, since the calcium carbonate salt and the calcium phosphate salt are decomposed by, for example, an acid or alkali ionic substance, it can be easily removed from the surface of the colorant-containing synthetic resin particles. Furthermore, when calcium carbonate salt or calcium phosphate salt is used as the poorly water-soluble alkaline earth metal salt, the surface smoothness is particularly excellent. Can be efficiently suppressed.

  According to this invention, uniform refinement | miniaturization of a coloring agent containing synthetic resin particle is realizable by using a water-soluble polymer dispersing agent in a synthetic resin particle production | generation process. Furthermore, by using an aqueous dispersion of a hardly water-soluble alkaline earth metal salt in the cooling step, it is possible to prevent coarsening due to adhesion of the colorant-containing synthetic resin particles.

  In the synthetic resin particle generation step, synthetic resin particles are generated in the presence of a water-soluble polymer dispersant in water, so a synthetic resin that can be granulated in a molten state may be used, and a synthetic resin that dissolves in an organic solvent is used. There is no need. Accordingly, a wide variety of synthetic resins that can be granulated in a molten state can be selected appropriately in consideration of the low-temperature fixability and durability of the finally obtained toner particles. In addition, since the resin kneaded product does not contain an organic solvent, a component that adversely affects the charging performance does not remain in the toner particles, and there is no need to provide a step of removing the organic solvent. Therefore, the conventional problem that the shape of the finally obtained toner particles becomes non-uniform by performing treatment such as classification and drying on the synthetic resin particles from which the organic solvent has been removed does not occur.

  Furthermore, since an aqueous dispersion of a hardly water-soluble alkaline earth metal salt is used in the cooling step, the surface of the particles is excellent in surface smoothness without leaving irregularities due to adhesion of the hardly water-soluble alkaline earth metal salt. In order to remove the poorly water-soluble alkaline earth metal salt from the surface of the colorant-containing synthetic resin particles, for example, by adding an ionic substance, the poorly water-soluble alkaline earth metal adhered to the surface of the colorant-containing synthetic resin particles Since it is performed by a simple operation of dissolving the metal salt in water, it is industrially advantageous. Further, in order to remove the hardly water-soluble alkaline earth metal salt dissolved by the water-soluble polymer dispersant and the ionic substance from the aqueous slurry, for example, it is possible to perform only a simple operation of washing with water. Is advantageous.

  The toner particles obtained by the production method of the present invention have a volume average particle diameter of about 3 to 15 μm, uniform particle shape and size, no variation in charging performance, for example, electrostatic charge such as electrophotography It can be suitably used as a developing toner. When the toner is used in an electrophotographic system, it is possible to easily form a high-quality image having a high image density and no white background fog, which is transferred to a transfer material at a high rate.

  According to the present invention, at least one of a polycarboxylic acid compound and polyvinyl alcohol can be preferably used as the water-soluble polymer dispersant. Since the polycarboxylic acid compound is easily soluble in water, the concentration adjustment and washing are easy. Further, when a polycarboxylic acid compound is used, the resin kneaded product can be easily atomized, and colorant-containing synthetic resin particles having a uniform shape and size that are smooth and free from cracks can be obtained particularly efficiently. .

  According to the present invention, when the addition amount of the hardly water-soluble alkaline earth metal salt is in the range of 10 parts by weight to 250 parts by weight with respect to 100 parts by weight of the resin kneaded product, the colorant-containing synthetic resin particles are aggregated. Does not become coarse.

  According to the present invention, the calcium carbonate salt and the calcium phosphate salt are decomposed by an ionic substance such as an acid or alkali, and therefore can be easily removed from the surface of the synthetic resin particles. Furthermore, when calcium carbonate salt or calcium phosphate salt is used as the poorly water-soluble alkaline earth metal salt, the surface smoothness is particularly excellent. Can be efficiently suppressed.

  FIG. 1 is a flowchart illustrating a toner manufacturing method according to the present exemplary embodiment. Manufacturing starts from step S0. In step S1, a mixture containing at least a synthetic resin and a colorant that can be granulated in a molten state is dry-mixed with a mixer and then melt-kneaded while heating to produce a resin kneaded product. In step S2, a water-soluble polymer dispersant is dissolved in water to prepare an aqueous solution containing the water-soluble polymer dispersant. In the present embodiment, step S1 may be performed before step S2, and step S2 may be performed before step S1. In step S3, the resin kneaded product is heated or heated and pressurized in water in which a water-soluble polymer dispersant is present, and mixed to form a colorant-containing synthetic resin particle (hereinafter simply referred to as “synthetic resin particle”). ) Containing an aqueous slurry. In step S4, the aqueous slurry containing synthetic resin particles is cooled, and an aqueous dispersion of a hardly water-soluble alkaline earth metal salt is added. Further, the hardly water-soluble alkaline earth metal adhering to the surface of the synthetic resin particles is removed. This removal is performed, for example, by adding an ionic substance. In step S5, toner particles and the like are washed, only the toner particles are separated and dried, and then the production of the toner is finished in step S6.

  The synthetic resin used in step S1 is used as a binder resin for toner particles. The synthetic resin is not particularly limited as long as it can be granulated in a molten state, and known resins can be used, and examples thereof include polyester, polyurethane, epoxy resin, and acrylic resin. Also, different synthetic resins can be used in combination.

  Polyester is synthesized by an ordinary polycondensation reaction. For example, a polyester can be obtained by subjecting a polybasic acid and a polyhydric alcohol to a dehydration condensation reaction in the presence or absence of an organic solvent and in the presence of a catalyst. At this time, a methethanol polycondensation reaction may be performed using a methyl esterified product of the polybasic acid as a part of the polybasic acid. Here, as the polybasic acid, those commonly used as polyester monomers can be used, for example, aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid and naphthalenedicarboxylic acid. And aliphatic carboxylic acids such as maleic anhydride, fumaric acid, succinic acid, alkenyl succinic anhydride and adipic acid. A polybasic acid can be used individually by 1 type, or can use 2 or more types together. Polyhydric alcohols commonly used as polyester monomers can be used, for example, aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol and glycerin, cyclohexanediol, cyclohexanedi Examples include alicyclic polyhydric alcohols such as methanol and hydrogenated bisphenol A, aromatic diols such as an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A. A polyhydric alcohol can be used individually by 1 type, or can use 2 or more types together. The polycondensation reaction between the polybasic acid and the polyhydric alcohol may be terminated when the acid value and softening point of the resin to be produced reach predetermined values. At this time, for example, by appropriately changing the blending ratio of polybasic acid and polyhydric alcohol, the reaction rate, etc., the carboxyl group content at the terminal of the polyester can be adjusted, and the characteristics of the resulting polyester are adjusted accordingly. can do. Moreover, when trimellitic anhydride is used as the polybasic acid, a carboxyl group can be easily introduced into the main chain of the polyester, and the resulting polyester can be modified.

  Although it does not restrict | limit especially as a polyurethane, For example, an acidic group or a basic group containing polyurethane can be used preferably. The acidic group or basic group-containing polyurethane can be produced according to a known method. For example, an acid group or basic group-containing diol, polyol and polyisocyanate may be subjected to addition polymerization. Examples of the acidic group or basic group-containing diol include dimethylolpropionic acid and N-methyldiethanolamine. Examples of the polyol include polyether polyols such as polyethylene glycol, polyester polyols, acrylic polyols, and polybutadiene polyols. Examples of the polyisocyanate include tolylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Each of these components can be used alone or in combination of two or more.

  Although it does not restrict | limit especially as an epoxy resin, An acidic group or a basic group containing epoxy resin can be used preferably. An acidic group or basic group-containing epoxy resin is produced, for example, by adding or addition polymerizing a base epoxy resin with a polycarboxylic acid such as adipic acid and trimellitic anhydride or an amine such as dibutylamine or ethylenediamine. be able to.

  Although the acrylic resin is not particularly limited, an acidic group-containing acrylic resin can be preferably used. The acidic group-containing acrylic resin is, for example, an acrylic resin monomer or an acrylic resin monomer containing an acidic group or a hydrophilic group and / or a vinyl having an acidic group or a hydrophilic group when an acrylic resin monomer or an acrylic resin monomer and a vinyl monomer are polymerized. It can manufacture by using a system monomer together. Known acrylic resin monomers can be used, for example, acrylic acid that may have a substituent, methacrylic acid that may have a substituent, acrylic ester that may have a substituent, and a substituent. Methacrylic acid ester and the like. Acrylic resin monomers can be used alone or in combination of two or more. As the vinyl monomer, known monomers can be used, and examples thereof include styrene, α-methylstyrene, vinyl bromide, vinyl chloride, vinyl acetate, acrylonitrile and methacrylonitrile. A vinyl monomer can be used individually by 1 type, or can use 2 or more types together. The polymerization is performed by solution polymerization, suspension polymerization, emulsion polymerization, or the like using a general radical initiator.

  Among these synthetic resins, polyester is preferable. Polyester is excellent in transparency, and can impart good powder fluidity, low-temperature fixability, secondary color reproducibility and the like to the obtained toner particles, and is therefore suitable as a binder resin for color toners. Further, polyester and acrylic resin may be grafted.

  In consideration of easy granulation operation, kneadability with the colorant and uniform shape and size of the toner particles obtained, a synthetic resin having a softening point of 150 ° C. or lower is preferable, and 60 to A synthetic resin at 150 ° C. is particularly preferred. Among these, a synthetic resin having a weight average molecular weight of 5,000 to 500,000 is preferable.

  Synthetic resins can be used alone or in combination of two or more. Furthermore, even if it is the same resin, multiple types which are different in any or all of molecular weight, monomer composition, etc. can be used.

  As the colorant mixed with the synthetic resin, known organic dyes, organic pigments, inorganic dyes, inorganic pigments, and the like can be used. If the specific example of a coloring agent is shown for every color, it will be as follows.

  Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, magnetic ferrite, and magnetite.

  Examples of yellow colorants include chrome lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, and benzidine. Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94 and C.I. I. Pigment yellow 138, and the like.

  Examples of the orange colorant include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment orange 31 and C.I. I. And CI Pigment Orange 43.

  Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risol red, pyrazolone red, watching red, calcium salt, lake red C, lake red D, and brilliant carmine 6B. Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178 and C.I. I. And CI Pigment Red 222.

  Examples of purple colorants include manganese purple, fast violet B, and methyl violet lake.

  Examples of blue colorants include bitumen, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated products, first sky blue, induslen blue BC, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16 and C.I. I. And CI Pigment Blue 60.

  Examples of the green colorant include chrome green, chromium oxide, pigment green B, micalite green lake, final yellow green G, and C.I. I. And CI Pigment Green 7.

  Examples of the white colorant include compounds such as zinc white, titanium oxide, antimony white, and zinc sulfide.

  One colorant can be used alone, or two or more different colorants can be used in combination. Moreover, even if it is the same color, 2 or more types can be used together.

  The use ratio of the synthetic resin and the colorant is not particularly limited, but is usually 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of the synthetic resin.

  The resin kneaded material can contain a wax in addition to the synthetic resin and the colorant, if necessary. As the wax, those commonly used in this field can be used. For example, natural wax such as carnauba wax and rice wax, synthetic wax such as polypropylene wax, polyethylene wax and Fischer Tropu, coal-based wax such as montan wax, alcohol And waxes such as ester waxes. Waxes can be used alone or in combination of two or more.

  Further, the resin kneaded material can contain, for example, general toner additives such as a charge control agent in addition to the synthetic resin and the colorant.

  For example, the resin kneaded product is prepared by dry-mixing various additives such as a synthetic resin, a colorant, and, if necessary, a wax and a charge control agent in a mixer, and then a temperature equal to or higher than the melting temperature of the synthetic resin (usually 80 It can be produced by melt-kneading while heating to about ~ 200 ° C, preferably about 100 to 150 ° C. Here, known mixers can be used. For example, Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), super mixer (trade name, manufactured by Kawata Co., Ltd.) and Mechano Mill (trade name, Okada Seiko (trade name) Henschel type mixing devices such as Co., Ltd.), Ongmill (trade name, manufactured by Hosokawa Micron Co., Ltd.), Hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.) and Cosmo System (trade name, Kawasaki Heavy Industries, Ltd.) ))). For the melt-kneading, a general kneader such as a twin screw extruder, a three-roller, or a lab blast mill can be used. More specifically, for example, a uniaxial or biaxial extruder such as TEM-100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87 (trade name, manufactured by Ikekai Co., Ltd.), knee An open roll type such as Dix (trade name, manufactured by Mitsui Mining Co., Ltd.) can be used.

  Examples of the water-soluble polymer dispersant used in step S2 include polycarboxylic acids such as polyacrylic acid and polystyrene acrylic acid, ammonium salts of polycarboxylic acids, metal salts of polycarboxylic acids, polyvinyl alcohol, polyvinyl pyrrolidone, Examples include compounds such as hydroxyethyl cellulose, carboxymethyl cellulose, and cellulose gum. The water-soluble polymer dispersant is preferably easily soluble in water in order to facilitate concentration adjustment and washing. Furthermore, a polymer dispersant capable of preparing an aqueous solution having a concentration of 10 weight percent or more at room temperature is preferable. Among the water-soluble polymer dispersants described above, polycarboxylic acid salts such as ammonium salts and metal salts of polycarboxylic acids such as polyacrylic acid and polystyrene acrylic acid are readily soluble in water, which is desirable. The water-soluble polymer dispersant may be used alone or in combination of two or more.

  The weight average molecular weight of the water-soluble polymer dispersant by GPC (gel permeation chromatography) is usually preferably about 5000 to 50000, more preferably about 5000 to 20000.

  The water-soluble polymer dispersant is preferably used in the range of 100 to 500 parts by weight with respect to 100 parts by weight of the resin kneaded product. If the amount used is less than 100 parts by weight, the shape and particle size distribution width of the resulting synthetic resin particles may be increased. On the other hand, when the amount used exceeds 500 parts by weight, it is preferable because the viscosity of the aqueous medium tends to be high, foaming is increased, and the dispersed suspension particles of the resulting synthetic resin may be dispersed unstable. Absent.

  In step S3, the resin kneaded material and an aqueous solution of a water-soluble polymer dispersant are mixed under heating or under pressure and heating. It is preferable to perform mixing while applying a shearing force. As the resin kneaded material, a material obtained by melt-kneading a synthetic resin, a colorant or the like may be used as it is, or a solidified material after melt-kneading or a material obtained by heating the solidified material to a molten state may be used. The heating temperature can be appropriately selected from a wide range depending on the kind of synthetic resin contained in the resin kneaded product and its characteristics (for example, molecular weight and softening point), and finally the particle size of the toner particles to be obtained. It is preferably between the softening temperature of the synthetic resin contained in the kneaded product and the decomposition temperature of the synthetic resin. The pressure is not particularly limited, and the mixing operation can be easily carried out according to the type of synthetic resin contained in the resin kneaded product, and the pressure at which toner particles having a desired particle size and shape can be obtained may be appropriately selected. .

  More specifically, the resin kneaded material and the aqueous solution of the water-soluble polymer dispersant are mixed using, for example, an emulsifier and a disperser.

  As an emulsifier and a disperser, a resin kneaded product and an aqueous solution of a water-soluble polymer dispersant can be received batchwise or continuously, and have a heating means or a heating and pressing means, and the resin kneaded product and An apparatus capable of mixing the aqueous solution under heating or heating and pressurization to produce synthetic resin particles and discharging the synthetic resin particles in a batch or continuous manner is preferable. Moreover, it is preferable that an emulsifier and a disperser have a stirring means and can mix a resin kneaded material and the aqueous solution of a water-soluble polymer dispersant under stirring. In the emulsifier and the disperser, it is preferable that the stirring vessel for mixing the resin kneaded material and the aqueous solution of the water-soluble polymer dispersant has a temperature adjusting means. The stirring vessel preferably has pressure resistance, more preferably pressure resistance, and includes a pressure control valve and the like. If such a stirring vessel is used, the temperature in the vessel is kept almost constant, and the pressure is controlled to a constant pressure in consideration of the melting temperature of the synthetic resin and the vapor pressure of the aqueous solution. In addition, when using at 100 degreeC or more, since it will be used by a pressurization state, it is desirable for an emulsifier and a disperser to be equipped with a mechanical seal, and to be able to seal a stirring container.

  Such emulsifiers and dispersers are commercially available. Specific examples thereof include, for example, Ultra Thalax (trade name, manufactured by IKA Japan Co., Ltd.), Polytron homogenizer (trade name, manufactured by Kinematica), TK Auto Homo Mixer (trade name, manufactured by Tokushu Kika Kogyo Co., Ltd.) ) And other batch type emulsifiers, Ebara Milder (trade name, manufactured by Ebara Manufacturing Co., Ltd.), TK Pipeline Homomixer, TK Homomic Line Flow, Fill Mix (all trade names, Special Machine Industries Co., Ltd.) ), Colloid mill (trade name, manufactured by Shinko Pantech Co., Ltd.), slasher, trigonal wet pulverizer (all trade names, manufactured by Mitsui Miike Chemical Co., Ltd.), Cavitron (trade name, Euro Co., Ltd.) Tech), fine flow mill (manufactured by Taiheiyo Kiko Co., Ltd.) and other continuous emulsifiers, Claremix (trade name, manufactured by M Technique Co., Ltd.) and Irumikkusu (trade name, Kika Kogyo Co., Ltd.), and the like.

  In step S4, the aqueous slurry, which is an aqueous solution containing the granulated synthetic resin particles, is cooled. After the step of generating the synthetic resin particles, it is preferable that the heating is stopped to naturally cool the synthetic resin particles.

  When the cooling temperature is equal to or higher than the melting temperature of the synthetic resin, the synthetic resin particles may be fused to each other even if the synthetic resin particles are dispersed by the dispersant. For this reason, it is preferable to continue stirring during the cooling step.

  In addition, if pressure is applied in the process of generating synthetic resin particles, the aqueous slurry will boil if pressure is not applied at a temperature of 100 ° C. or higher. It is preferable to do this. This is because if the aqueous slurry is boiled, a lot of bubbles are generated and subsequent processing becomes difficult. Moreover, it is preferable when it is 50 degrees C or less to return to atmospheric pressure. Furthermore, it is preferable to return to atmospheric pressure after the mixture in the container has cooled to room temperature.

  In the cooling step of cooling the aqueous slurry containing synthetic resin particles, an aqueous dispersion of a hardly water-soluble alkaline earth metal salt is added to an aqueous solution containing synthetic resin particles granulated into fine particles. In order to prevent the synthetic resin particles from adhering to each other and becoming coarse, it is preferable to add an aqueous dispersion of a hardly water-soluble alkaline earth metal salt between the maximum temperature during heating and the softening temperature of the synthetic resin particles. . Furthermore, it is preferable to add an aqueous dispersion of a hardly water-soluble alkaline earth metal salt to the aqueous solution containing the granulated synthetic resin particles simultaneously with stopping the heating.

  As the poorly water-soluble alkaline earth metal salt used in the present invention, known ones can be used. The reason why a poorly water-soluble substance is used is that it is impossible to prevent the synthetic resin particles from adhering to each other and becoming coarse because a highly water-soluble substance cannot cover the surface of the synthetic resin particles. is there. The poorly water-soluble alkaline earth metal salt preferably has a solubility of 50 mg or less with respect to 1 liter of water at 20 ° C., and more preferably 30 mg or less. Moreover, in order to coat | cover uniformly the surface of the synthetic resin particle in an aqueous slurry, it is preferable to have water dispersibility. Furthermore, if a substance that is poorly water-soluble but is not decomposed by an ionic substance such as an acid or an alkali is used, an extra and complicated process for removing the substance coated on the surface of the synthetic resin particles is required. . Accordingly, alkaline earth metal salts that are poorly water-soluble, have water dispersibility, and are decomposed by ionic substances are preferred. Among alkaline earth metal salts, calcium carbonate salts and calcium phosphate salts are preferably water-insoluble, water-dispersible, and decomposed by ionic substances, so that they can be preferably used.

  As calcium carbonate salts, there are three types of calcium carbonate (water solubility 14 mg / liter, 20 ° C.), aragonite (water solubility 15 mg / liter, 20 ° C.) and vaterite (water solubility 24 mg / liter, 20 ° C.). There are forms, both of which are sparingly water-soluble. In addition, calcium carbonate reacts with an acid in an aqueous system by adjusting the pH of the aqueous system to an acidic side, preferably 1 to 3 with an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid, and calcium ions, water, carbon dioxide, Disassembled into Of these, calcium ions dissolve in water, and carbon dioxide is a gas and is naturally discharged out of the system. Therefore, calcium carbonate can be easily removed from the surface of the resin particles by adding an acid. Furthermore, since the starting temperature of the thermal decomposition of calcium carbonate is around 850 ° C., it is stable even when exposed to a general synthetic resin melting temperature (usually about 100 to 300 ° C.). Calcium carbonate includes heavy calcium carbonate, light calcium carbonate, and colloidal calcium carbonate mainly due to the difference in production method. Among these, colloidal calcium carbonate excellent in dispersibility in water is preferable.

As the calcium phosphate salt, known ones can be used, and examples include calcium hydrogen phosphate, calcium dihydrogen phosphate, tricalcium phosphate, and hydroxyapatite, which may be used alone, but as a mixture of two or more types It may be used. The calcium phosphate salt reacts with an acid in an aqueous system by adjusting the pH of the aqueous system to an acidic side, preferably 1 to 3 with an inorganic acid such as hydrochloric acid, sulfuric acid and nitric acid, and calcium chloride, water and phosphate ions. And decompose. Since these are dissolved in water, they are discharged out of the system by washing. Therefore, the calcium phosphate salt can be easily removed from the surface of the resin particles by adding an acid. Furthermore, the thermal decomposition start temperature of calcium phosphate salt is high, and it is stable even when exposed to a general synthetic resin melting temperature (usually about 100 to 300 ° C.). Of the calcium phosphate salts, hydroxyapatite is more preferable in consideration of poor water solubility, acid solubility, crystal size, and the like. Hydroxyapatite is represented by the structural formula of 3Ca ₃ (PO ₄ ) ₂ .Ca (OH) ₂ . Tricalcium phosphate slowly changes to hydroxyapatite in the presence of moisture. That is, hydroxyapatite is less soluble in water and is more stable to water.

  The slightly water-soluble alkaline earth metal salt is preferably used in an amount of 10 to 250 parts by weight with respect to 100 parts by weight of the resin kneaded product. When the amount used is less than 10 parts by weight, the improvement in dispersibility and its stability is small as compared with the dispersed suspension particles of the synthetic resin obtained with the water-soluble polymer dispersant aqueous solution. On the other hand, if the amount used exceeds 250 parts by weight, the viscosity of the aqueous medium tends to be high, and the dispersed suspension particles of the synthetic resin obtained with the aqueous polymer dispersant solution may be unstable. Therefore, it is not preferable.

  The hardly water-soluble alkaline earth metal salt is present in the form of secondary particles in which primary particles are aggregated in the aqueous dispersion. The average dispersion diameter of the secondary particles is preferably 1 μm or less. This is because if the thickness is significantly larger than 1 μm, the surface of the synthetic resin particles may not be uniformly coated, and consequently, the synthetic resin particles may not be prevented from adhering to each other. In addition, since calcium carbonate and calcium phosphate quickly aggregate and become stable secondary particles and cannot exist as primary particles, these secondary particles have a primary particle diameter of less than 0.1 μm. Don't be.

  The aqueous dispersion containing the hardly water-soluble alkaline earth metal salt may contain a known surfactant or the like as the dispersion stabilizer. The dispersion stabilizer improves the dispersibility by preventing aggregation of the hardly water-soluble alkaline earth metal salt in water. When a dispersion stabilizer is added, a hardly water-soluble alkaline earth metal salt is likely to exist in a form close to primary particles in water, so water dispersibility is good, and dispersibility may decrease even when the concentration is increased. Therefore, it is easy to adjust the density. Examples of the surfactant include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium dodecylbenzene sulfonate, sodium oleate, sodium laurate, sodium stearate and potassium stearate. . Surfactant can be used individually by 1 type, or can use 2 or more types together.

  A slightly water-soluble alkaline earth metal salt is removed from the surface of the synthetic resin particles. For example, it is preferable to add an ionic substance to an aqueous dispersion containing synthetic resin particles after natural cooling.

  Here, as the ionic substance, as long as it has solubility in water and dissociates to increase the solubility of the poorly water-soluble alkaline earth metal salt in water, there is no particular limitation. Any of an acidic substance and an alkaline substance may be used. The ionic substance may be in any state of gas, liquid or solid, but it is preferably added in the form of an aqueous solution that can be dissolved quickly and the amount of addition can be easily adjusted.

  When using an acidic substance, it is preferable to use an aqueous solution of an inorganic acid or an aqueous solution of an organic acid. Known inorganic acids can be used, and examples thereof include water-soluble inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and carbonic acid. Known organic acids can be used, and examples thereof include water-soluble organic acids such as formic acid and acetic acid. Thereby, the poorly water-soluble alkaline earth metal salt on the surface of the synthetic resin particles is removed.

  A well-known thing can be used as an alkaline substance, For example, water-soluble inorganic alkalis, such as ammonia, sodium hydroxide, and potassium hydroxide, are mentioned.

In step S5, the synthetic resin particles are washed, separated and dried.
The synthetic resin particles are washed, for example, by washing the synthetic resin particles with water. The washing of synthetic resin particles is a process performed to remove impurities that affect the charge amount of the toner particles obtained, and the conductivity of the supernatant water after washing the synthetic resin particles using a conductivity meter, etc. It is preferable to repeatedly wash with water until the value reaches 50 μS / cm or less. Thereby, the charge amount of the toner particles can be made more uniform. The water used for washing is preferably water having a conductivity of 20 μS / cm or less. In order to obtain such water, for example, an activated carbon method, an ion exchange method, a distillation method and a reverse osmosis method can be used. Of course, water may be prepared by combining two or more of these methods. The washing of synthetic resin particles with water may be carried out either batchwise or continuously. Further, the temperature of the washing water is not particularly limited, but washing at 10 to 80 ° C. is preferable. In this embodiment, washing may be performed before the synthetic resin particles that are the toner base are separated, or washing may be performed after the synthetic resin particles are separated.

  Separation of the synthetic resin particles can be performed according to a known method, and examples thereof include filtration, suction filtration, and centrifugation.

  Next, the synthetic resin particles are classified as necessary, and then dried to obtain toner particles. When drying the synthetic resin particles, it is preferable to dry them after checking the presence or absence of impurities with a conductivity meter or the like. A well-known method can be employ | adopted for drying, for example, a freeze-drying method, an airflow type drying method, etc. are mentioned.

The toner particles thus obtained can be used as it is as an electrostatic charge developing toner. An external additive can also be added to the toner particles. Examples of the external additive include silica and titanium oxide. These external additives may be subjected to various surface modifications such as surface modification with a silane coupling agent. The use ratio of the toner particles and the external additive is not particularly limited, but usually 0.1 to 5 parts by weight of the external additive may be used with respect to 100 parts by weight of the toner particles.
After these steps, the production of the toner is finished in step S6.

  The toner obtained by the production method of the present invention can be used as a one-component developer and a two-component developer. When used as a one-component developer, for example, when non-magnetic toner is used, there is a method of transporting by using a blade and a fur brush, frictionally charging with a developing sleeve, and attaching the toner onto the sleeve. .

  When used as a two-component developer, a carrier is used as a developer together with the toner obtained by the production method of the present invention. The carrier used together with the toner obtained by the production method of the present invention is not particularly limited, but mainly covers single and composite ferrites composed of iron, copper, zinc, nickel, cobalt, manganese, chromium elements, and carrier core particles. A material whose surface is coated with a substance is used. The coating material is appropriately selected according to the components contained in the toner. Styrene resin, acrylic resin, polyacid, polyvinyl butyral, nigrosine, amino acrylate resin, basic dye and its lake, silica fine powder and alumina fine powder. A coating substance can be used individually by 1 type, or can use 2 or more types together. The average particle size of the carrier is 10 to 100 μm, preferably 20 to 50 μm.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited by these. In the following, “parts” and “%” mean “parts by weight” and “% by weight”, respectively, unless otherwise specified.

[water]
In the following Examples and Comparative Examples, for preparing an aqueous solution of a water-soluble polymer dispersant, for preparing an aqueous dispersion of a slightly water-soluble alkaline earth metal salt, for cleaning synthetic resin particles as a toner base, and ionic For the preparation of the substance aqueous solution, water having a conductivity of 0.5 μS / cm was used. This washing water was prepared from tap water using an ultrapure water production apparatus (trade name: Ultra Pure Water System CPW-102, manufactured by ADVANTEC). The electrical conductivity of water was measured using Lacom Tester EC-PHCON10 (trade name, manufactured by Inoue Seieido).

[Particle size and particle size distribution of synthetic resin particles]
Further, the particle size (volume average particle size, number average particle size) and particle size distribution of the resulting synthetic resin particles (toner base) were measured using Coulter Multisizer II (trade name, manufactured by Coulter Inc.). The number of measured particles was 50,000 counts, and the aperture diameter was 100 μm.

[Average circularity]
Furthermore, the average circularity of the obtained synthetic resin particles (toner base material) was measured using a flow type particle image analyzer (trade name: FPIA-2000, manufactured by Toa Medical Electronics Co., Ltd.). The average circularity is defined by (peripheral length of a circle having the same projection area as the particle image) / (peripheral length of the particle projection image) in the particle image detected by the measuring apparatus, and takes a value of 1 or less. The closer to 1, the closer the toner particle shape is to a true sphere.

[Preparation of water in which ionic substances are dissolved]
The water in which the ionic substance was dissolved was prepared by dissolving a predetermined amount of the ionic substance in the water. The water in which the ionic substance was dissolved was added after stirring, after heating was stopped, and the mixture in the container was cooled to room temperature and the pressure was returned to atmospheric pressure. In the examples and comparative examples, dilute hydrochloric acid (concentration 1 mol / L) was used as the ionic substance.

Hereinafter, examples and comparative examples will be described.
(Example 1)
[Preparation of resin kneaded material]
Polyester resin (glass transition point (Tg) 62 ° C., softening point 110 ° C.) 100 parts, colorant (carbon black) 5 parts, wax (polyethylene) 2 parts and charge control agent (trade name: Bontron E-84, Orient Chemical) After mixing and dispersing 1 part in a Henschel mixer for 30 minutes, melt kneading and dispersing using an extruder (trade name, Nidicus MOS140-800, Mitsui Mining Co., Ltd.) to prepare a resin kneaded product did.

[Preparation of aqueous dispersion of water-soluble polymer dispersant]
20 parts of polyacrylic acid (weight average molecular weight 10,000) ammonium salt and 480 parts of water were mixed to prepare a 4% aqueous dispersion of a water-soluble polymer dispersant.

[Preparation of aqueous dispersion of sparingly water-soluble alkaline earth metal salt]
On the other hand, 12 parts of calcium carbonate having a primary particle size of 0.1 μm and 88 parts of water were put into a disperser (trade name: Filmix 56 type, manufactured by Tokushu Kika Kogyo Co., Ltd.) and dispersed at 8000 rpm for 60 minutes. A 12% aqueous dispersion of calcium carbonate, a poorly water-soluble alkaline earth metal salt, was prepared. The average dispersion diameter of the calcium carbonate after dispersion is measured by a laser diffraction / scattering particle size distribution measuring device (trade name: LA-920, manufactured by HORIBA, Ltd.) with a 50% frequency particle diameter (median diameter) on a volume basis. As a result, it was 0.70 μm. In the following Examples and Comparative Examples, those prepared by diluting with water to a predetermined concentration were used.

[Synthetic resin particle granulation process]
Into a metal container equipped with a pressure regulating valve, heating means and rotor-stator stirring means (diameter 30 mm), 20 parts of the resin kneaded material and 500 parts of a 4% aqueous solution of ammonium polyacrylate are charged at 150 ° C. and 5 atm. The mixture was stirred and mixed for 10 minutes while heating and pressing (8000 rpm).

[Cooling process]
Thereafter, the heating was stopped, and 500 parts of a 0.4% aqueous dispersion of calcium carbonate was added. After this mixture was naturally cooled to 20 ° C. with stirring, dilute hydrochloric acid (concentration 1 mol / L) was added as an ionic substance. Then, the pH of the mixture was adjusted to 1, and calcium carbonate was completely decomposed and removed from the surface of the synthetic resin particles.

[Washing / separation / drying process]
Thereafter, water having a conductivity of 0.5 μS / cm was added to the mixture for washing. Cleaning is performed by mixing the mixture and water (conductivity 0.5 μS / cm), adjusting the solid content to 10% by adding the water, and then stirring (300 rpm) for 30 minutes with a turbine-type stirring blade. The same washing operation was repeated until the conductivity of the supernatant liquid separated from the mixture by centrifugation was 10 μS / cm or less. Thereafter, the synthetic resin particles in the mixture were separated by centrifugation and dried to obtain 20 parts of synthetic resin particles.

[Observation of coarse particles and post-treatment]
The obtained synthetic resin particles were observed with a scanning electron microscope (SEM). As a result, a plurality of finely divided particles were not adhered and coarse particles were not included, and the surface was smooth and spherical synthetic resin. Particles were observed. The synthetic resin particles obtained above are dispersed in water, classified in water by a sedimentation method, and after removing fine particles of 2 μm or less, freeze-dried, volume average particle size 8.9 μm, circularity 0.97 Toner particles were obtained. To 100 parts of the toner particles, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle size of 20 nm were mixed to obtain a toner.

(Example 2)
The volume average particle diameter is the same as in Example 1 except that 500 parts of a 5% aqueous dispersion of calcium carbonate is used as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. Synthetic resin particles as a toner base material having a diameter of 8.9 μm and a circularity of 0.97 were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 3)
The volume average particle diameter is the same as in Example 1, except that 500 parts of a 10% aqueous dispersion of calcium carbonate is used as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. Synthetic resin particles as a toner base material having a diameter of 8.9 μm and a circularity of 0.97 were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

Example 4
The same procedure as in Example 1 was performed, except that 500 parts of a 20% aqueous dispersion of ammonium polyacrylate was used as the aqueous dispersion of the water-soluble polymer dispersant. Synthetic resin particles as a toner base having a diameter of 0.9 μm and 1 μm were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 5)
The volume average particle size is the same as in Example 4 except that 500 parts of a 5% aqueous dispersion of calcium carbonate is used as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. Synthetic resin particles as a toner base having a diameter of 7.1 μm and a circularity of 0.97 were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 6)
The volume average particle size is the same as in Example 4 except that 500 parts of a 10% aqueous dispersion of calcium carbonate is used as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. Synthetic resin particles as a toner base having a diameter of 7.1 μm and a circularity of 0.97 were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 7)
As an aqueous dispersion of a hardly water-soluble alkaline earth metal salt, a 5% aqueous dispersion of hydroxyapatite (primary particle diameter 0.1 μm, 50% frequency particle diameter 1. 0 μm) The same procedure as in Example 5 was performed except that 500 parts were used, and classification and drying were performed to obtain synthetic resin particles as a toner base having a volume average particle size of 7.1 μm and a circularity of 0.97. . A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle size of 20 nm were mixed with 100 parts of the toner particles to produce the toner of the present invention.

(Example 8)
As an aqueous dispersion of a hardly water-soluble alkaline earth metal salt, a 5% aqueous dispersion of tricalcium phosphate (primary particle diameter 0.1 μm, 50% frequency particle diameter 2 on the volume basis) instead of the calcium carbonate aqueous dispersion. 0.0 μm) Except that 500 parts were used, the same operation as in Example 5 was performed, classification and drying were performed to obtain synthetic resin particles as a toner base having a volume average particle diameter of 7.1 μm and a circularity of 0.97. It was. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

Example 9
The same operation as in Example 1 was performed except that 500 parts of a 4% aqueous solution of an ammonium salt of polystyrene acrylic acid (weight average molecular weight 10,000, acid value 200) was used as the aqueous dispersion of the water-soluble polymer dispersant. Then, classification and drying were performed to obtain synthetic resin particles as a toner base having a volume average particle size of 8.7 μm and a circularity of 0.97. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 10)
The volume average particle size is the same as in Example 9, except that 500 parts of a 5% aqueous dispersion of calcium carbonate is used as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. Synthetic resin particles, which are toner bases having a size of 8.7 μm and a circularity of 0.97, were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 11)
The volume average particle size is the same as in Example 9, except that 500 parts of a 10% aqueous dispersion of calcium carbonate is used as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. Synthetic resin particles, which are toner bases having a size of 8.7 μm and a circularity of 0.97, were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 12)
A volume average particle size of 6 was obtained by performing the same operation as in Example 9 except that 500 parts of a 20% aqueous dispersion of polystyrene ammonium acrylate was used as the aqueous dispersion of the water-soluble polymer dispersant. Synthetic resin particles as a toner base having a diameter of 0.7 μm and a circularity of 0.97 were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 13)
The volume average particle size is the same as in Example 12 except that 500 parts of a 5% aqueous dispersion of calcium carbonate is used as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. Synthetic resin particles as a toner base having a diameter of 6.7 μm and a circularity of 0.97 were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 14)
The volume average particle size is the same as in Example 12, except that 500 parts of a 10% aqueous dispersion of calcium carbonate is used as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. Synthetic resin particles as a toner base having a diameter of 6.7 μm and a circularity of 0.97 were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 15)
The classification and drying were carried out in the same manner as in Example 9, except that 500 parts of a 10% aqueous solution of polyvinyl alcohol (polyvinyl alcohol weight average molecular weight 17000, Ken value 80) was used as the aqueous dispersion of the water-soluble polymer dispersant. To obtain synthetic resin particles as a toner base having a volume average particle diameter of 7.8 μm and a circularity of 0.97. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 16)
The volume average particle size is the same as in Example 15 except that 500 parts of a 5% aqueous dispersion of calcium carbonate is used as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. Synthetic resin particles as a toner base having a diameter of 7.8 μm and a circularity of 0.97 were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Example 17)
The volume average particle size is the same as in Example 15 except that 500 parts of a 10% aqueous dispersion of calcium carbonate is used as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. Synthetic resin particles as a toner base having a diameter of 7.8 μm and a circularity of 0.97 were obtained. A portion of the sample was collected, dried, and observed with a scanning electron microscope (SEM). As a result, the particles were not adhered and coarsened, and the surface was smooth and spherical synthetic resin particles. Was observed. Subsequently, 0.7 parts of silica particles hydrophobized with a silane coupling agent having an average primary particle diameter of 20 nm were mixed with 100 parts of the toner particles to obtain a toner.

(Comparative Example 1)
In a metal container equipped with a pressure regulating valve, a heating means and a rotor stator type stirring means (caliber 30 mm), 20 parts of a resin kneaded product and 500 parts of a 20% aqueous solution of ammonium polyacrylate are charged at 150 ° C. and 5 atm. The mixture was stirred for 10 minutes while heating and pressing (8000 rpm). Thereafter, the heating was stopped, and the mixture was naturally cooled to 20 ° C. without adding the calcium carbonate aqueous dispersion, and then washed with water having a conductivity of 0.5 μS / cm added to the mixture. Thereafter, the synthetic resin particles in the mixture were separated by centrifugation and dried to obtain 20 parts of synthetic resin particles. The resulting synthetic resin particles contained many particles that were adhered to each other and coarsened, and could not be used as toner particles.

(Comparative Example 2)
In a metal container equipped with a pressure regulating valve, a heating means and a rotor stator type stirring means (caliber 30 mm), 20 parts of a resin kneaded product and 500 parts of a 20% aqueous solution of ammonium polyacrylate are charged at 150 ° C. and 5 atm. The mixture was stirred for 10 minutes while heating and pressing (8000 rpm). Thereafter, heating was stopped, 500 parts of a 12% aqueous dispersion of calcium carbonate was added, and after the mixture was naturally cooled to 20 ° C., dilute hydrochloric acid was added as an ionic substance, and the pH of the mixture was adjusted to 1. The calcium carbonate on the surface of the synthetic resin particles was completely decomposed and removed. The resulting synthetic resin particles contained many particles that were adhered to each other and coarsened, and could not be used as toner particles.

(Comparative Example 3)
The same operation as in Comparative Example 1 was conducted except that 500 parts of a 12% aqueous dispersion of hydroxyapatite was used instead of the aqueous calcium carbonate dispersion as the aqueous dispersion of the hardly water-soluble alkaline earth metal salt. The hydroxyapatite was decomposed and washed with water, and the synthetic resin particles were washed with water. The resulting synthetic resin particles contained many particles that were adhered to each other and became coarse, and should be used as toner particles. I could not.

(Comparative Example 4)
The same procedure as in Comparative Example 1 was performed except that 500 parts of a 20% aqueous solution of ammonium polystyrene acrylate was used in place of the aqueous ammonium polyacrylate as the aqueous dispersion of the water-soluble polymer dispersant. Synthetic resin particles contained many particles that adhered to each other and became coarse, and could not be used as toner particles.

(Comparative Example 5)
The same procedure as in Comparative Example 2 was performed except that 500 parts of a 20% aqueous solution of ammonium polystyrene acrylate was used in place of the aqueous ammonium polyacrylate as the aqueous dispersion of the water-soluble polymer dispersant. Synthetic resin particles contained many particles that adhered to each other and became coarse, and could not be used as toner particles.

(Comparative Example 6)
The same operation as in Comparative Example 3 was performed except that 500 parts of a 20% aqueous solution of ammonium polystyrene acrylate was used in place of the aqueous ammonium polyacrylate as the aqueous dispersion of the water-soluble polymer dispersant. Synthetic resin particles contained many particles that adhered to each other and became coarse, and could not be used as toner particles.

(Test example)
The toner particles obtained in each of Examples 1 to 17 and a ferrite core carrier having an average particle diameter of 60 μm were adjusted and mixed so that the toner concentration was 5% by weight to prepare a two-component developer.

Using this developer, using a laser printer (trade name: AR-C150, manufactured by Sharp Corporation), the toner adhesion amount on “full color exclusive paper” product number: PP106A4C, A4 size, manufactured by Sharp Corporation) Was adjusted to 0.8 mg / cm ² and printed, and an image sample was prepared using an external fixing machine.

  Each image sample was prepared, and the optical density, white background fog and transfer rate were evaluated and comprehensively evaluated.

[Optical density]
Measurement was performed with a spectrocolorimetric densitometer (trade name: X-Rite 938, manufactured by Japan Planographic Printing Equipment Co., Ltd.).

[White background fog]
In the case of black toner, the whiteness of full-color dedicated paper (PP106A4C) is measured in advance with a whiteness meter (manufactured by Nippon Denshoku Industries Co., Ltd.), and this value is taken as the first measured value. Next, three originals including a white circle having a diameter of 55 mm are copied, and the white portion of the obtained copy is measured with the whiteness meter, and this value is set as a second measurement value. The value obtained by subtracting the second measurement value from the first measurement value was defined as fog density (%), and if the value was 2.0% or less, it was judged as good.

[Transfer rate]
Calculation was made from the toner weight Mp on the paper surface of the sample copied on the predetermined chart and the toner weight Md remaining on the photoreceptor, and a case where it was 85% or more was judged acceptable. The transfer rate (%) is obtained by the following equation.
Transfer rate (%) = [Mp / (Md + Mp)] × 100

〔Comprehensive evaluation〕
Evaluation was made according to the following criteria.
◯: No resin particle aggregation, optical density of 1.4 or more, fog density of 2.0% or less, transfer rate of 85% or more ×: not satisfying the above conditions Table 1 shows the results.

  From Table 1, it is clear that the toner particles obtained by the production method of the present invention have a preferable particle size and shape as toner particles, and can form an image with high image density and no white background fog on the transfer paper.

3 is a flowchart showing a toner manufacturing method of the present embodiment.

Claims (4)

A synthetic resin particle production step for producing an aqueous slurry containing the colorant-containing synthetic resin particles by heating or heat-pressing a resin kneaded product containing at least a synthetic resin and a colorant that can be granulated in a molten state;
And a cooling step of cooling an aqueous slurry containing the colorant-containing synthetic resin particles.
The resin kneaded product does not contain an organic solvent,
Generating colorant-containing synthetic resin particles in the presence of a water-soluble polymer dispersant in the synthetic resin particle generation step;
And an aqueous dispersion containing a hardly water-soluble alkaline earth metal salt to an aqueous slurry containing colorant-containing synthetic resin particles in the cooling step.   2. The toner production method according to claim 1, wherein at least one of a polycarboxylic acid compound and polyvinyl alcohol is used as the water-soluble polymer dispersant.   The method for producing a toner according to claim 1 or 2, wherein the addition amount of the hardly water-soluble alkaline earth metal salt is in the range of 10 to 250 parts by weight with respect to 100 parts by weight of the resin kneaded product. .   The method for producing a toner according to claim 1, wherein the hardly water-soluble alkaline earth metal salt is at least one of a calcium carbonate salt and a calcium phosphate salt.

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