JP2010020320A - Method of producing developing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method of producing a developing agent having a narrow particle size distribution and providing good image quality. <P>SOLUTION: A dispersion liquid prepared by mixing a granular mixture containing a binder resin and a colorant with an aqueous medium is subjected to mechanical shearing to finely divide the granular mixture, thereby forming fine particles, and the fine particles are agglomerated to form agglomerated particles. The fine particles are agglomerated while stirring the dispersion liquid containing the fine particles in a stirring section including a main stirrer with a low circumferential speed of a stirring member and a sub-stirrer with a high circumferential speed of a stirring member so that stirring of the dispersion liquid in the main stirrer is assisted by the sub-stirrer, thereby the fine particles are agglomerated while applying sufficient shear to the dispersion liquid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a developer for developing an electrostatic charge image and a magnetic latent image in electrophotography, electrostatic printing, magnetic recording, and the like.

  In electrophotography, an electric latent image is formed on an image carrier, and then the latent image is developed with toner. After the toner image is transferred to a transfer material such as paper, it is fixed by means such as heating and pressing. To do. The toner to be used is not only a conventional single color black, but also forms an image using a plurality of colors of toner in order to form a full color image.

  The toner includes a two-component developer used by mixing with carrier particles and a one-component developer used as a magnetic toner or a nonmagnetic toner. These toners are usually produced by a kneading and pulverizing method. This kneading and pulverizing method is a method for producing desired toner particles by melt-kneading a binder resin, a release agent such as a pigment and wax, a charge control agent and the like, finely pulverizing them after cooling, and classifying them. Depending on the purpose, inorganic and / or organic fine particles are added to the surface of the toner particles produced by the kneading and pulverization method to obtain a toner.

  In the case of toner particles produced by a kneading and pulverizing method, it is difficult to intentionally control the shape. In particular, when a highly pulverizable material is used, it is easy to be finely divided. In a two-component developer, the finely divided toner adheres to the carrier surface and the charge deterioration of the developer is accelerated. In the case of the developer, the finely divided toner is scattered, the developability is lowered with the change in the toner shape, and the image quality is deteriorated. Further, when pulverization occurs at the interface between the binder resin and the wax, the wax is detached from the toner, and contamination such as a developing roll, an image carrier, and a carrier is likely to occur, and the reliability as a developer may be reduced. .

  Under such circumstances, in recent years, an emulsion polymerization aggregation method has been proposed as a toner production method in which the shape and surface composition of toner particles are intentionally controlled (see, for example, Patent Document 1 and Patent Document 2).

  In the emulsion polymerization aggregation method, a resin dispersion is prepared by emulsion polymerization, while a colorant dispersion in which a colorant is dispersed in a solvent is prepared and mixed to form aggregated particles corresponding to the toner particle size. Thereafter, the toner particles are obtained by fusing to obtain toner particles. According to this emulsion polymerization aggregation method, the toner shape can be arbitrarily controlled from an indeterminate shape to a spherical shape by selecting the heating temperature condition.

  In the emulsion polymerization aggregation method, it can be obtained by aggregating and fusing at least a dispersion of resin fine particles and a dispersion of a colorant under predetermined conditions. However, the emulsion polymerization aggregation method has limitations on the types of resins that can be synthesized and is suitable for the production of styrene acrylic copolymers, but it is possible to apply polyester resins that are known to have good fixability. Can not.

  On the other hand, there is a phase inversion emulsification method in which a pigment dispersion or the like is added to a solution dissolved in an organic solvent and water is added to the solution dissolved in an organic solvent as a method for producing a toner using a polyester resin, but the organic solvent is removed and recovered. There is a need. Although a method for producing fine particles by mechanical stirring in an aqueous medium without using an organic solvent has been proposed, it is necessary to supply a molten resin or the like to a stirring device, and handling is difficult (for example, And Patent Document 3). Further, the degree of freedom in shape control is low, and the toner shape cannot be arbitrarily controlled from an indeterminate shape to a spherical shape.

  On the other hand, a method has been developed in which particles containing polyester resin are refined and grown to a toner particle size. However, in this method, a large increase in viscosity occurs when the fine particles are aggregated, and the solid content concentration is high. Thus, it is difficult to obtain a toner having a desired particle size distribution (see, for example, Patent Document 4).

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a developer having a narrow particle size distribution and capable of forming an image with good image quality.

The method for producing a developer of the present invention includes a step of mixing a granulated mixture containing at least a binder resin and a colorant with an aqueous medium to form a dispersion,
The dispersion is subjected to mechanical shearing, the granulated mixture is refined to form fine particles, and the fine particles are aggregated while the dispersion containing the fine particles is agitated in a stirring unit. In the method for producing a developer comprising the step of forming
The stirring unit includes a main stirrer provided with a stirring member rotating at a peripheral speed A (m / s), a sub stirrer provided with a stirring member rotating at a peripheral speed B (m / s), and the dispersion A line for introducing the liquid from the main stirrer to the sub stirrer and a line for returning the dispersion liquid from the sub stirrer to the main stirrer. A stirring assist mechanism that satisfies the relationship represented by 5 ≦ B / A ≦ 15,
In the step of forming the agglomerated particles, a major part of the dispersion containing the fine particles is stirred in a main stirrer, and a part of the dispersion containing the fine particles is introduced into a sub-stirrer. It is characterized in that the fine particles are agglomerated while assisting agitation by returning the agitation with faster rotation to the main agitator.

  When the method of the present invention is used, a developer having a narrow particle size distribution and capable of forming an image with good image quality is obtained.

FIG. 1 is a flowchart showing an example of a method for producing a developer according to the present invention. FIG. 2 is a schematic view of an example of a stirring unit used in the present invention.

  Embodiments of the present invention will be described below.

The method for producing the developer of the present invention includes:
A step of mixing a granulated mixture containing at least a binder resin and a colorant with an aqueous medium to form a dispersion;
Subjecting the dispersion to mechanical shearing, refining the granulated mixture to form fine particles, and aggregating the fine particles to form aggregated particles,
Aggregation of the fine particles is performed while stirring the dispersion containing the fine particles in a stirring portion having two stirrers having different peripheral speeds of the stirring member.

  The stirring unit used in the present invention includes a main stirrer provided with a stirring member rotating at a peripheral speed A (m / s) and a sub-stirring provided with a stirring member rotating at a peripheral speed B (m / s). , A line for introducing the dispersion liquid from the main stirrer and feeding it to the sub stirrer, and a line for returning the dispersion liquid from the sub stirrer to the main stirrer, and the peripheral speeds A and B are 1.5 ≦ B / A And a stirring assist mechanism that satisfies the relationship represented by ≦ 15.

  In the formation process of the aggregated particles used in the present invention, a major part of the dispersion liquid containing fine particles is stirred in the main stirrer, and a part of the dispersion liquid containing the fine particles is introduced into the sub-stirrer. By returning to the main stirrer what has been stirred at a faster peripheral speed than the vessel, the sub-stirrer assists the stirring of the dispersion liquid in the main stirrer, and agglomerates the fine particles while applying sufficient shear to the dispersion.

  In a method for producing an electrophotographic toner in which fine particles are aggregated in an aqueous medium to obtain a desired particle size, a batch method is usually employed. In the batch method, a stirring blade is provided in a container in which the dispersion liquid is placed, and the dispersion liquid in the container is mixed and stirred by the stirring blade. This method is widely adopted because of its good productivity, but it is difficult to mix the dispersion uniformly. Therefore, when the batch method is adopted in the aggregation process, the particle size distribution of the obtained electrophotographic toner becomes broad or coarse particles are generated.

  On the other hand, the dispersion can be uniformly stirred by stirring in a container sufficiently small with respect to the size of the stirring blade. Further, by adjusting the rotation speed of the stirring blade, appropriate shear can be imparted to the dispersion, but since only a small amount of the dispersion can be treated, productivity is low.

  In the present invention, by using a combination of both of these agitation containers, it is possible to provide a method for producing a toner having a uniform particle size distribution that ensures productivity.

  The main stirrer used in the present invention includes a stirring member that rotates at a peripheral speed A. On the other hand, the volume of the sub-stirrer used in the present invention is sufficiently smaller than the volume of the main stirrer. Since the sub-stirrer is small in volume, the load applied to the stirrer is reduced, so that the peripheral stirrer B of the sub-stirrer is rotated more rapidly than the peripheral speed A of the stirrer of the main stirrer is rotated faster. It is easier to rotate the stirring member of the vessel faster than the peripheral speed A.

  By using the present invention, a partial amount of the dispersion containing fine particles is introduced into the sub-stirrer, and the stirrer with faster rotation than the main stirrer is returned to the main stirrer, so that the main stirrer is insufficiently stirred. Therefore, even if the viscosity of the dispersion liquid increases, the viscosity of the dispersion liquid can be lowered and the fine particles can be aggregated more uniformly without increasing the peripheral speed A of the stirring member of the main stirrer. Can do.

  For example, when a polyester resin is used as the binder resin, this polyester resin has a carboxyl group at the terminal, and therefore, when the polyester resin fine particles are aggregated, pseudo-crosslinking via the carboxyl group occurs, and a sudden viscosity change occurs. cause. For this reason, compared with the case where a styrene acrylic resin particle is aggregated, a coarse particle is easy to generate | occur | produce.

  On the other hand, using the production method of the present invention, a part of the dispersion liquid is taken out of the container from the main stirrer, and generated in the dispersion liquid by applying strong shearing with a fast stirrer with a sub-stirrer capable of imparting high shear. The coarse particles can be crushed and fed into the main stirrer.

  Depending on the intensity of stirring when the fine particles are aggregated and grown to a desired particle size, the particle size obtained varies greatly. In the present invention, the peripheral speed A (m / s) of the stirring member of the main stirrer and the peripheral speed B (m / s) of the stirring member of the sub stirrer satisfy the relationship of 1.5 ≦ B / A ≦ 15. By satisfying, a developer having a desired particle size distribution can be produced. In the case of 1.5> B / A, since the difference in shearing force between the peripheral speeds A and B is small, the generated coarse particles cannot be crushed by shearing at the peripheral speed B, and the resulting particle size distribution is broad. On the other hand, when B / A> 15, the shearing force due to the peripheral speed B is too much larger than the shearing force due to the peripheral speed A, so that not only the coarse particles but also many of the produced aggregates are crushed, and the toner The particle size does not grow. As a result, a toner having a desired particle size distribution cannot be produced.

  The particle size of the toner particles obtained is not determined only by stirring, but is determined by many factors such as the type of coagulant and the amount added. Therefore, the appropriate peripheral speeds of A and B vary depending on conditions, but by adjusting to satisfy the condition 1.5 ≦ B / A ≦ 15 defined in the present invention, desired particles can be easily obtained. A toner having a diameter can be produced.

  By using the production method of the present invention, in the step of creating colored fine particles in an aqueous medium and growing them to a desired toner particle size, the toner is grown in a facility having two stirrers, whereby a high concentration dispersion is achieved. A toner having a desired particle size distribution can be obtained even in the liquid.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a flowchart showing an example of a method for producing a developer according to the present invention.

  As shown in the figure, in the electrophotographic toner manufacturing method of the present invention, first, at least a binder resin and a colorant are prepared.

  Subsequently, a coarsely granulated mixture containing a binder resin and a colorant is prepared (Act 1). The coarsely granulated mixture is obtained, for example, by a step of melt-kneading and roughly pulverizing a mixture containing a binder resin and a colorant. Alternatively, it is obtained by granulating a mixture containing a binder resin and a colorant.

  The coarsely granulated mixture preferably has a volume average particle size of 0.012 mm to 0.2 mm. If the volume average particle size is less than 0.012 mm, the energy for coarse crushing increases and the productivity tends to decrease. If it exceeds 0.2 mm, there is a tendency that clogging occurs in the piping or the like provided in the miniaturization apparatus, and the obtained particle size distribution becomes large.

  Next, the coarsely granulated mixture is dispersed in an aqueous medium to form a mixed liquid of the coarsely granulated mixture (Act 2).

  In the step of forming a mixed liquid of the coarsely granulated mixture, at least one of a surfactant and a pH adjuster such as a basic compound can be optionally added to the aqueous medium.

  By adding a surfactant, it can be easily dispersed in an aqueous medium by the action of the surfactant adsorbed on the surface of the mixture. Moreover, self-dispersibility can be improved by increasing the dissociation degree of the dissociable functional group on the surface of the mixture or increasing the polarity by adding a pH adjuster.

  Subsequently, the obtained mixed liquid can be heated to a desired temperature. The temperature of the mixed solution can be set to be equal to or higher than the glass transition temperature of the binder resin used for miniaturization. Further, the higher the temperature, the finer the colored particles, which is advantageous. However, since the hydrolysis is accelerated, the fixability tends to be deteriorated.

  The mixed liquid heated to these desired temperatures is subjected to mechanical shearing, and the coarsely granulated mixture is finely granulated to prepare a mixed liquid containing fine particles (Act 3).

  The fine particles preferably have a volume average particle diameter of 0.05 to 10 μm.

  Next, although these mixed liquids are cooled to below the glass transition temperature of the resin, they may be cooled to a desired temperature for agglomeration.

  A material that promotes particle growth is added to the cooled mixed liquid so as to obtain a desired toner particle size. In the step of forming aggregated particles, a plurality of fine particles may be aggregated using at least one process of pH adjustment, addition of a surfactant, addition of a water-soluble metal salt, addition of an organic solvent, and temperature adjustment. it can. It is possible to control the shape of the aggregated particles obtained by adjusting these processes.

  In the method of the present invention, the fine particles are aggregated using a stirrer equipped with two stirrers.

  In FIG. 2, the schematic of an example of the stirring part used for this invention is shown.

  As shown in the figure, the stirring unit 10 has a dispersion 11 and includes a main stirrer 1 including a motor 3 and a stirring member 2 including a stirring blade 4, and a stirring member 7. The sub-stirrer 6 having a small volume, the line 8 for introducing the partial amount 11 ′ of the dispersion 11 from the main stirrer 1 to the sub-stirrer 6, and the dispersion 11 ′ from the sub-stirrer 6 to the main stirrer 1. It has a return line 9.

  Here, the peripheral speed A of the stirring blade 4 and the peripheral speed B of the stirring member 7 are adjusted so as to satisfy the condition 1.5 ≦ B / A ≦ 15 defined in the present invention.

  A major part of the dispersion liquid containing fine particles in the stirring unit 10 is stirred in the main stirrer 1 and a part of the dispersion liquid containing fine particles is introduced into the sub-stirrer 6. By returning the material stirred at a faster peripheral speed B to the main stirrer 1, stirring of the dispersion 11 in the main stirrer 1 is assisted by the sub-stirrer 6 and sufficient dispersion is applied to the dispersion 11. Aggregate the microparticles (Act 4).

  Subsequently, in order to improve the stability of the agglomerated particles, the agglomerated particles are fused at a constant temperature, but there is no particular limitation as long as the temperature at which the agglomerates are integrated. Is preferably fused at a temperature of about +5 to +80 degrees with respect to the glass transition temperature. Further, the growth and fusion of the particles may be performed simultaneously or individually as described above.

  The agglomerated particles or the stabilized agglomerated particles preferably have a volume average particle diameter of 1 to 10 μm.

  The agglomerated particles or stabilized agglomerated particles preferably have a circularity of 0.8 to 1.0.

  Subsequently, the dispersion containing the aggregated particles or stabilized aggregated particles is cooled to, for example, 5 ° C. to below the glass transition temperature, and then the conductivity of the cleaning waste liquid is 200 μS using, for example, a filter press. The toner particles are obtained by washing (Act 5) until / cm or less and drying.

  Examples of the binder resin used in the present invention include polystyrene, styrene / butadiene copolymer, styrene resin such as styrene / acrylic copolymer, polyethylene, polyethylene / vinyl acetate copolymer, polyethylene / norbornene copolymer, Examples thereof include ethylene resins such as polyethylene / vinyl alcohol copolymers, polyester resins, acrylic resins, phenol resins, epoxy resins, allyl phthalate resins, polyamide resins, and maleic resins. These resins may be used alone or in combination of two or more.

  The binder resin preferably has an acid value of 1 or more.

  Examples of the colorant used in the present invention include carbon black, organic or inorganic pigments and dyes. For example, carbon black includes acetylene black, furnace black, thermal black, channel black, ketjen black, and the like. Examples of yellow pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 74, 81, 83, 93, 95, 97, 98, 109, 117, 120, 137, 138, 139, 147, 151, 154, 167, 173, 180, 181, 183, 185, C.I. I. Bat yellow 1, 3, 20, etc. are mentioned. These may be used alone or in combination. Examples of magenta pigments include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 150, 163, 184, 185, 202, 206, 207, 209, 238, C.I. I. Pigment violet 19, C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35, etc. are mentioned. These may be used alone or in combination. Examples of cyan pigments include C.I. I. Pigment blue 2, 3, 15, 16, 17, C.I. I. Bat Blue 6, C.I. I. Acid Blue 45 and the like. These may be used alone or in combination.

  In the coarsely granulated mixture, at least one of a wax and a charge control agent can be further added.

  Examples of the wax include aliphatic hydrocarbon wax such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax, and acid value polyethylene wax. Wax oxides, or block copolymers thereof, candelilla wax, carnauba wax, waxy wax, jojoba wax, plant wax such as rice wax, beeswax, lanolin, whale wax, animal wax, ozokerite, Mineral waxes such as ceresin and petrolactam, waxes based on fatty acid esters such as montanic acid ester wax and castor wax, and fatty acid esters such as deoxidized carnauba wax. Or and the like that were de-oxidation all. Further, saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkyl carboxylic acids having a long-chain alkyl group, unsaturated fatty acids such as brassic acid, eleostearic acid, valinalic acid, stearyl alcohol , Saturated alcohols such as eicosyl alcohol, behenyl alcohol, carnauvir alcohol, seryl alcohol, melyl alcohol, or long chain alkyl alcohols having a long chain alkyl group, polyhydric alcohols such as sorbitol, linoleic acid amide, oleic acid Amide, fatty acid amide such as lauric acid amide, methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, saturated fatty acid bis amide such as hexamethylene bis stearic acid amide, Unsaturated fatty acid amides such as lenbis oleic acid amide, hexamethylene bis oleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide, m-xylene bis stearic acid amide, Aromatic bisamides such as N, N'-distearylisophthalic acid amide, fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally referred to as metal soap), aliphatic Hydroxyl obtained by hydrogenating waxes grafted to hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid, partially esterified products of fatty acids and polyhydric alcohols such as behenic acid monoglycerides, and vegetable oils and fats. Methyl Este Having a Group Compounds.

  As the charge control agent for controlling the triboelectric charge amount, for example, a metal-containing azo compound is used, and the metal element is preferably a complex, complex salt of iron, cobalt, chromium, or a mixture thereof. In addition, a metal-containing salicylic acid derivative compound can be used, and the metal element is preferably a complex, complex salt of zirconium, zinc, chromium, boron, or a mixture thereof.

  Examples of the surfactant that can be used in the present invention include anionic surfactants such as sulfate ester, sulfonate, phosphate, and soap, amine salts, quaternary ammonium salts, and the like. Nonionic surfactants such as cationic surfactants, polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols can be mentioned.

  Examples of the mechanical stirrer used in the present invention include Ultra Tarrax (manufactured by IKA Japan), TK auto homomixer (manufactured by Primix), TK pipeline homomixer (manufactured by Primix), and TK Philmix. Medialess agitation such as (Primix), Claremix (M Technique), Claire SS5 (M Technique), Cavitron (Eurotech), Fine Flow Mill (Pacific Kiko) Machine, Viscomill (made by Imex), Apex mill (made by Kotobuki Kogyo Co., Ltd.), Starmill (made by Ashizawa, Finetech), DCP Super Flow (made by Japan Eirich), MP Mill (made by Inoue Manufacturing Co., Ltd.), Spike Mill (Inoue Manufacturing Co., Ltd.) ), Mighty mill (Inoue Seisakusho), SC mill (three I made mine Co., Ltd.), and the media stirring machine and the like, such as.

  In the present invention, a mixture containing at least a resin and a pigment or a kneaded product is atomized using a mechanical stirrer while being heated, but after atomization, the mixture may be once cooled to a desired temperature, You may set to the desired temperature which aggregates.

  In the present invention, a mixture containing a binder resin and a colorant can be kneaded to prepare a coarsely granulated mixture.

  The kneader to be used is not particularly limited as long as melt kneading is possible, and examples thereof include a single screw extruder, a twin screw extruder, a pressure kneader, a Banbury mixer, and a Brabender mixer. Specifically, FCM (made by Kobe Steel), NCM (made by Kobe Steel), LCM (made by Kobe Steel), ACM (made by Kobe Steel), KTX (made by Kobe Steel), GT (manufactured by Ikegai Co., Ltd.), PCM (manufactured by Ikegai Co., Ltd.), TEX (manufactured by Nippon Steel Works Co., Ltd.), TEM (manufactured by Toshiba Machine Co., Ltd.), ZSK (manufactured by Warner Company), and Nidex (manufactured by Mitsui Mining Company) It is done.

  In the present invention, when the fine particles are aggregated, a water-soluble metal salt can be used. Examples of water-soluble metal salts include metal salts such as sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, magnesium sulfate, aluminum chloride, and aluminum sulfate, and polyaluminum chloride and polyaluminum hydroxide. Inorganic metal salt polymers such as polysulfide calcium.

  In the present invention, an organic solvent may be used when the fine particles are aggregated. Examples of the organic solvent include methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-2-propanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol and other alcohols, acetonitrile, 1,4- And dioxane.

  In the present invention, the obtained aggregated particles can be used as a core to form a coating resin layer. The coating method is not particularly limited.

  For example, in the case of dry mixing, as a device for coating by mechanical stirring, a hybridizer (manufactured by Nara Machinery Co., Ltd.), a cosmos system (manufactured by Kawasaki Heavy Industries, Ltd.), a mechanofusion (manufactured by Hosokawa Micron) , Mechanomyl (Okada Seiko Co., Ltd.) can be used. Heat treatment may be performed to make the surface of the coated particles more uniform, and a surfing system (manufactured by Nippon Pneumatic Industry Co., Ltd.) is preferably used.

  Further, additional fine particles may be added to the obtained dispersion to coat with heteroaggregation. Further, a desired monomer is additionally added to the obtained dispersion and adsorbed onto the particles, and then may be coated by polymerization, or may be heteroaggregated at the stage where the monomer has grown to fine particles without being adsorbed. You can do them in parallel.

  The additional fine particles preferably contain at least a resin component. Further, the additional fine particles preferably have a volume average particle diameter of 0.03 to 1 μm.

  In the present invention, in order to adjust fluidity and chargeability with respect to the toner particles, 0.01 to 20% by weight of inorganic fine particles may be added to and mixed with the toner particle surface with respect to the total weight of the toner. As such inorganic fine particles, silica, titania, alumina, strontium titanate, tin oxide and the like can be used alone or in admixture of two or more.

  The inorganic fine particles are preferably surface-treated with a hydrophobizing agent from the viewpoint of improving environmental stability. In addition to such inorganic oxides, resin fine particles having a size of 1 μm or less may be externally added to improve cleaning properties.

  As a mixing machine for inorganic fine particles, for example, Henschel mixer (manufactured by Mitsui Mining), super mixer (manufactured by Kawata), ribocorn (manufactured by Okawara Seisakusho), nauter mixer (manufactured by Hosokawa Micron), turbulator (Hosokawa Micron) Co., Ltd.), cyclomix (manufactured by Hosokawa Micron Co., Ltd.), spiral pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.), and Ladige mixer (manufactured by Matsubo Co., Ltd.).

  In the present invention, coarse particles and the like may be further screened. As the sieving equipment used for the sieve, Ultrasonic (manufactured by Sakae Sangyo Co., Ltd.), Gyroshifter (Tokuju Kogakusha Co., Ltd.), Vibrasonic System (manufactured by Dalton Co., Ltd.), Soniclean (manufactured by Shinto Kogyo Co., Ltd.), Turbo Screener (Manufactured by Turbo Kogyo Co., Ltd.), micro shifter (manufactured by Hadano Sangyo Co., Ltd.), circular vibrating sieve, etc.

  90 parts by weight of polyester resin as binder resin (glass transition temperature 58 degrees, acid value 6, weight average molecular weight Mw 13,658), 5 parts by weight of cyan pigment as colorant, 4 parts by weight of ester wax, and zirconia metal as charge control agent After mixing 1 part by weight of the complex, the mixture was melt-kneaded in a biaxial kneader set at 120 ° C. to obtain a kneaded product.

  The obtained kneaded product was coarsely pulverized to a mean volume particle size of 1.2 mm using a hammer mill manufactured by Nara Machinery Co., Ltd., to obtain coarse particles. Subsequently, the mixture was further pulverized using a pulverizer manufactured by Hosokawa Micron Co., Ltd. to obtain medium crushed particles having an average volume particle diameter of 58 μm.

  30 parts by weight of the crushed particles obtained, 1 part by weight of sodium dodecylbenzenesulfonate as an anionic surfactant, 1 part by weight of triethylamine as an amine compound, and 68 parts by weight of ion-exchanged water were stirred with an IKA homogenizer and mixed. Liquid 1 was obtained.

  Next, the obtained mixed liquid 1 is put into a nanomizer (Yoshida Kikai Kogyo Co., Ltd., adding a heating system to the YSNM-2000AR) whose heating system temperature is set to 120 ° C., and is repeatedly treated three times at a processing pressure of 150 MPa. went. The volume average particle size of the colored fine particles obtained after cooling was measured with SALD7000 (manufactured by Shimadzu Corporation), and as a result, it was 0.70 μm. This liquid is referred to as atomized dispersion liquid 1.

Example 1
A 5 L tank is equipped with a paddle of φ100 (mm), and the dispersion is supplied from the bottom of the tank to the Cavitron DC1010. After passing through the agitator of the Cavitron, the apparatus has a mechanism that returns the dispersion to the tank. .

  Disperse 3 kg of dispersion 1 into a 5 L tank, stir the paddle at 500 rpm (circumferential speed 2.6 m / s), set the rotation speed of the cavitron to 1150 rpm (circumferential speed 4.1 m / s), 1 was circulated. The paddle's peripheral speed is A, and the cavitron's peripheral speed is B.

  In the above state, the temperature of the dispersion was controlled at 30 ° C., and then 0.9 kg of 5% sulfuric acid band aqueous solution was added. After dropping the sulfuric acid band, the temperature was raised to 60 degrees at a rate of 0.5 ° C./min while circulating the dispersion. As a result of maintaining the temperature at 60 ° C. and stirring for 1 hour, an aggregate having a volume average particle diameter of 9.2 μm could be obtained. The volume average particle size was measured with a Beckman Coulter Coulter Counter (aperture diameter 20 mm). Thereafter, in order to maintain the particle size, an additional 0.6 kg of 20% sodium dodecylbenzenesulfonate aqueous solution was added, the temperature was raised to 85 ° C. at a rate of 0.5 ° C./min, and held at 85 ° C. for 2 hours. did. After cooling, the resulting dispersion was allowed to stand for 24 hours to allow solids to settle and the supernatant was visually observed. As a result, the supernatant was transparent.

  The solid content of the obtained dispersion was repeatedly centrifuged using a centrifuge, the supernatant was removed, and washed with ion-exchanged water, and washed until the supernatant had a conductivity of 5 μS / cm. Thereafter, the toner was dried with a vacuum dryer until the water content became 0.3% by weight to obtain toner particles.

  After drying, as additives, 2 parts by weight of hydrophobic silica and 0.5 parts by weight of titanium oxide were adhered to the surface of the toner particles to obtain a desired toner for electrophotography.

  The volume average particle diameter of the obtained electrophotographic toner was measured with a Beckman Coulter Coulter Counter (aperture diameter 20 μm), and as a result, it was 9.4 μm, and CV value ((standard deviation / average particle diameter) × 100). Was 22.2. When there are coarse particles in the toner, the aperture is clogged and the particle size cannot be measured. In addition, color spots and vitiligo are generated in the output image, causing a defective image.

  As a result of measuring the circularity with FPIA2100 manufactured by Sysmex Corporation, it was 0.98.

  The obtained electrophotographic toner was put into a multi-function machine e-STUDIO 281c manufactured by TOSHIBA TEC, and an image was output. As a result, a good image without image defect could be obtained.

Examples 2 to 8 and Comparative Examples 1 and 2
A toner was prepared under the same conditions as in Example 1 except that the peripheral speed A and the peripheral speed B were changed as shown in Table 1 below.

  In Examples 2 to 8, the supernatants of the obtained dispersions were transparent, and no coarse particles were generated. No defects were observed in the image. In Comparative Example 1, the supernatant was transparent, but due to the presence of coarse particles, the particle size could not be measured. In addition, color spots were generated in the image. In Comparative Example 2, the supernatant of the dispersion was cloudy. If the supernatant of the dispersion is not transparent, it may cause image defects due to a decrease in yield and a failure to take in a specific material. Coarse particles were not generated, and the volume average particle size was 7.02 μm. In addition, fixing failure occurred in the image.

  DESCRIPTION OF SYMBOLS 1 ... Main stirrer, 2 ... Stirring member, 3 ... Motor, 4 ... Stirring blade, 6 ... Substirring device, 7 ... Stirring member, 8, 9 ... Line, 10 ... Stirring part, 11 ... Dispersion

Japanese Patent Laid-Open No. 63-282275 JP-A-6-250439 JP-A-9-311502 JP 2007-323071 A

Claims (6)

A step of mixing a granulated mixture containing at least a binder resin and a colorant with an aqueous medium to form a dispersion;
The dispersion is subjected to mechanical shearing, the granulated mixture is refined to form fine particles, and the fine particles are aggregated while the dispersion containing the fine particles is stirred in a stirring unit. Comprising the step of forming particles,
The stirring unit includes a main stirrer provided with a stirring member rotating at a peripheral speed A (m / s), a sub stirrer provided with a stirring member rotating at a peripheral speed B (m / s), and the dispersion A line for introducing the liquid from the main stirrer to the sub stirrer, and a line for returning the dispersion liquid from the sub stirrer to the main stirrer, the peripheral speeds A and B being 1.5 ≦ A stirring assist mechanism that satisfies the relationship represented by B / A ≦ 15,
In the step of forming the agglomerated particles, a major part of the dispersion containing the fine particles is stirred in a main stirrer, and a part of the dispersion containing the fine particles is introduced into a sub-stirrer. A method for producing a developer, wherein the fine particles are agglomerated while assisting agitation by returning the agitation at a faster rotation to the main agitator.   2. The step of mixing the granulated mixture with an aqueous medium to form a dispersion, wherein at least one of a surfactant and a basic compound is further added to the dispersion. The method described.   The method according to claim 1, further comprising forming toner particles using the fine particles, wherein the toner particles have a circularity of 0.8 to 1.0.   The method according to any one of claims 1 to 3, wherein a film layer is formed by heteroaggregation by adding additional fine particles using the aggregated particles as a core.   The method according to claim 4, wherein the additional fine particles have a volume average particle diameter of 0.03 to 1 μm.   The process of forming the aggregated particles includes at least one of pH adjustment, addition of a surfactant, addition of a water-soluble metal salt, addition of an organic solvent, and temperature adjustment. 2. The method according to item 1.

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