JP4700495B2 - Electrostatic latent image developing carrier, developer, image forming method, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an electrostatic latent image developing carrier and developer suitably used for electrophotography, electrostatic recording, electrostatic printing, and the like, an image forming method, a process cartridge, and an image forming apparatus.

The dry development method used in electrophotography forms a visible image by electrostatically attaching toner rubbed with a charging member to an electrostatic latent image.
In this dry development method, a so-called one-component development method mainly composed of toner, glass beads, a magnetic carrier, or a coated carrier whose surface is coated with a resin and a toner are mixed and used. There is a so-called two-component development system.

In the developer used in the two-component development system, minute toner particles are held on the surface of a relatively large core material by the electric force generated by friction between both particles, and this developer is close to the electrostatic latent image. Then, the toner particles overcome the binding force with the core material by the electric field formed by the electrostatic latent image, and are developed on the electrostatic latent image. The developer is repeatedly used while replenishing the toner consumed by the development.
For this reason, the core material must be triboelectrically charged with a desired polarity and a sufficient charge amount at all times during long-time use. However, collision between particles, mechanical stirring in the particles and the developing device, or heat generated by these causes the toner to be fused to the surface of the core material, so-called spent toner is generated, and the charging characteristics of the core material decrease with use time. To do. As a result, the background of the image and toner scattering occur, so that the entire developer needs to be replaced.

  In order to prevent such spending, the life of the carrier is extended by coating the surface of the core material with a resin having a low surface energy, such as a fluororesin or a silicone resin. For example, a carrier coated with a room temperature curable silicone resin and a positively chargeable nitrogen resin (see Patent Document 1), a carrier coated with a coating material containing at least one modified silicone resin (see Patent Document 2), a room temperature curable silicone A carrier having a coating layer containing a resin and a styrene-acrylic resin (see Patent Document 3), a carrier in which the core particle surface is coated with two or more layers of silicone resin so that there is no adhesion between the layers (see Patent Document 4) ), A carrier in which silicone resin is applied in multiple layers on the core particle surface (see Patent Document 5), a carrier whose surface is coated with a silicon resin containing silicon carbide (see Patent Document 6), and exhibits a critical surface tension of 20 dyn / cm or less. A positively chargeable carrier coated with a material (see Patent Document 7) and coated with a coating material containing a fluorine alkyl acrylate. And a carrier, the developer comprising a toner containing a containing chromium azo dye (see Patent Document 8), and the like.

  Recently, in order to improve image quality, the toner tends to have a smaller particle size, and as a result, toner spent on the carrier is likely to occur. In addition, in conventional spray coating, it is difficult to uniformly wet the carrier surface with a coating material, and therefore it is difficult to produce a carrier having a coating film and a core material with a uniform film thickness and film quality. It has become. Furthermore, in the case of a full color toner, a resin with a low softening point is used in order to obtain a sufficient color tone. Therefore, the spent amount to the carrier is larger than that of the black toner, and the toner charge amount is reduced. Scattering and background contamination occur. As described above, in the full-color electrophotographic system, when the toner charge amount is lowered, there is a problem that the image density particularly in the highlight portion is easily changed and the high image quality cannot be maintained.

  In addition, in order to improve the durability of the carrier, it has been shown that a coating in which fine particles and a conductivity-imparting material are dispersed in a resin matrix of a low surface energy substance is provided to control the spent resistance, coating strength, and electrical characteristics. However, since the dispersion liquid in which the fine particles are added to the organic solvent is spray-coated at a high temperature, there is a problem that it is difficult to make the charge amount uniform due to aggregation of the fine particles.

Conventional spray coating also has manufacturing problems such as regulation of volatile organic compounds (VOC) by organic solvents used when forming a coating layer on the surface of the core material, generation of waste liquid, and the need for drying energy. Yes.
In order to solve these problems, as a carrier production method using a dry powder process that does not use an organic solvent, there is a carrier particle production method using a supercritical fluid (see Patent Document 12). The content is that the coating resin is melted and coated in a heated state, and since the resin material is an acrylic resin, the above-mentioned problem of spent is not solved.

As described above, from the viewpoint of global environmental load and resource saving, there are many problems to be improved in the conventional carrier manufacturing method and carrier.
Japanese Patent Laid-Open No. 55-127469 Japanese Patent Laid-Open No. 55-157751 JP-A-56-140358 JP-A-57-96355 JP 57-96356 A JP 58-207054 A JP-A-61-1110161 JP-A-62-273576 JP-A-9-319161 JP-A-9-269614 Japanese Patent Laid-Open No. 10-186731 US Pat. No. 5,514,512

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention provides a carrier having a coating layer, which has good toner chargeability and stability over time, good adhesion to a core material, and a coating layer having a uniform thickness. And a developer using the carrier, an image forming method using the developer, a process cartridge, and an image forming apparatus.

  In order to solve the above-mentioned problems, the present inventors have made extensive studies, and as a result, using either a supercritical fluid or a subcritical fluid instead of a conventional organic solvent as a solvent, Because the tension is as close to zero as possible, even fine irregularities on the surface of the core material can be wetted with the coating agent solution, and the carrier has a uniform thin film with high adhesion between the core material, the fine particles, and the coating layer. It has been found that a carrier that can be coated, has high mechanical strength, and has excellent toner chargeability and stability over time can be obtained.

The present invention is based on the above knowledge, and the above-mentioned problems are solved by the following <1> to <20> inventions (hereinafter referred to as the present invention 1 to 20).
<1> A carrier in which a coating layer is formed on the surface of a core material by dissolving or dispersing at least a coating resin in a fluid containing at least a supercritical fluid or a subcritical fluid, and the coating layer contains fine particles. A carrier for developing an electrostatic latent image.
<2> In a fluid containing at least a supercritical fluid or a subcritical fluid, a solution or dispersion produced by dissolving or dispersing at least the coating resin is sprayed onto the core material to form a coating layer on the surface of the core material. A carrier for developing an electrostatic latent image, wherein the carrier layer contains fine particles.
<3> In a fluid containing at least a supercritical fluid or a subcritical fluid, the solution is rapidly expanded by releasing the pressure of the solution or dispersion formed by dissolving or dispersing at least the core material and the coating resin. A carrier for developing an electrostatic latent image, wherein the carrier has a coating layer formed on a surface of a core material, and the coating layer contains fine particles.
<4> In a fluid containing at least a supercritical fluid or a subcritical fluid, at least the core material and the coating resin are dissolved or dispersed to control the pressure or temperature of the solution or dispersion to reduce the solubility. A carrier for developing an electrostatic latent image, wherein the carrier has a coating layer formed on a surface of a core material, and the coating layer contains fine particles.
<5> The electrostatic latent image developing carrier according to any one of <1> to <4>, wherein the fine particles are made of a material having a composition different from that of the coating layer.
<6> The electrostatic latent image developing carrier according to any one of <1> to <5>, wherein the fine particles are a metal oxide.
<7> The electrostatic latent image developing carrier according to any one of <1> to <6>, wherein the supercritical fluid or the subcritical fluid is carbon dioxide.
<8> The electrostatic latent image developing carrier according to any one of <1> to <7>, wherein an entrainer is mixed with the supercritical fluid or the subcritical fluid.
<9> The <8> description, wherein an entrainer content in a mixed fluid of at least one of the supercritical fluid or the subcritical fluid and the entrainer is 0.1 to 10% by mass. Carrier for electrostatic latent image development.
<10> The electrostatic latent image according to <8> or <9>, wherein the entrainer is a poor solvent for the core material, the fine particles, and the coating resin under normal temperature and normal pressure. Image development carrier.
<11> The carrier according to any one of <8> to <10>, wherein the entrainer is at least one selected from the group consisting of methanol, ethanol, and propanol.
<12> The electrostatic latent image developing carrier according to any one of <1> to <11>, wherein the coating resin is a silicone resin represented by the following structural formula (1).

(In the structural formula (1), R represents a hydrogen atom, a hydroxyl group, an alkoxy group, an alkyl group, or an aryl group.)
<13> The carrier for developing an electrostatic latent image according to <12>, wherein the silicone resin is solid at normal temperature and pressure.
<14> The carrier for developing an electrostatic latent image according to <12> or <13>, wherein the silicone resin has a silanol concentration of 1 to 40% by mass.
<15> The electrostatic latent image developing carrier according to any one of <12> to <14>, wherein the silicone resin has a weight average molecular weight (Mw) of 500 to 100,000.
<16> The carrier for developing an electrostatic latent image according to any one of <1> to <15>, wherein the core material has a volume average particle diameter of 20 to 50 μm.
<17> An electrostatic latent image developer comprising the carrier according to any one of <1> to <16> and a toner.
<18> An electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier, a developing step of developing the electrostatic latent image using a developer to form a visible image, An image forming method including at least a transfer step of transferring the visible image to a recording medium and a fixing step of fixing the transfer image transferred to the recording medium, wherein the developer is described in <18>. An image forming method comprising an electrostatic latent image developer.
<19> Development for forming a visible image by developing an electrostatic latent image carrier carrying at least an electrostatic latent image and developing the electrostatic latent image carried on the electrostatic latent image carrier using a developer. A process cartridge, wherein the developer is the electrostatic latent image developer described in <18>.
<20> An electrostatic latent image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the electrostatic latent image carrier, and an electrostatic latent image formed on the electrostatic latent image carrier. Developing means for developing an image using a developer to form a visible image; Transfer means for transferring a visible image formed on the electrostatic latent image carrier onto a recording medium; An image forming apparatus comprising at least a fixing unit for fixing a transferred image, wherein the developer is the electrostatic latent image developer described in <18>.

  According to the carrier of the first to fourth aspects of the present invention, at least a coating resin is dissolved or dispersed in a fluid containing at least a supercritical fluid or a subcritical fluid to form a coating layer on the surface of the core material. Since the coating layer contains fine particles, it is possible to obtain a carrier having a coating layer with a uniform thickness that has good toner chargeability and stability over time and good adhesion to the core material.

  According to the carrier of the present invention 5 to 6, since the fine particles are made of a material different from the coating layer component such as a metal oxide, the wear of the coating layer can be reduced and the charging stability can be improved. The stability with time can be improved.

  According to the carrier of the present invention 7, since the supercritical fluid or subcritical fluid is carbon dioxide, a supercritical state can be easily created, and it is nonflammable, highly safe, and has a hydrophobic surface. In addition, since it is gasified just by returning to normal pressure, it can be easily recovered and reused. The obtained carrier does not need to be dried, and no waste liquid is generated.

  According to the carriers of the present inventions 8 to 11, since the mixed fluid of the supercritical fluid or the subcritical fluid and the entrainer is used, the solubility of the coating resin can be improved.

  According to the carriers of the present invention 12 to 15, since the silicone resin having the above structure is used, a coating layer having good durability can be formed.

  According to the carrier of the present invention 16, since the volume average particle diameter of the core material is 20 to 50 μm, it can be adapted to high image quality such as prevention of carrier scattering and image quality deterioration.

  According to the developer of the present invention 17, since the carrier of the present invention is mixed, a developer having excellent toner chargeability and stability over time can be provided.

  According to the image forming method of the present invention 18, since the electrostatic latent image is developed using the developer of the present invention, a high-quality image having excellent temporal stability can be formed.

  According to the process cartridge of the present invention 19 and the image forming apparatus of the present invention 20, since the electrostatic latent image is developed using the developer of the present invention, a high-quality image having excellent temporal stability is obtained. be able to.

-Supercritical fluid and subcritical fluid-
The supercritical fluid has properties that are intermediate between gas and liquid, such as mass transfer (as fast as liquid) and heat transfer (as liquid) and low viscosity (as gas). In addition, it means a fluid whose density, dielectric constant, solubility parameter, free volume, and the like can be continuously changed greatly by changing temperature and pressure. Furthermore, since the supercritical fluid has an extremely small interfacial tension as compared with an organic solvent, even a minute undulation (surface) can follow and can be wetted (contacted with the supercritical fluid).
The supercritical fluid exists as a non-condensable high-density fluid in a temperature and pressure range that exceeds the limit (critical point) where gas and liquid can coexist, does not cause condensation even when compressed, and exceeds the critical temperature. And, as long as it is a fluid in a state of a critical pressure or higher, it can be used without any particular limitation.In the present invention, it can be appropriately selected according to the purpose, but those having a low critical temperature and critical pressure are preferred, The subcritical fluid can be used without particular limitation as long as it exists as a high-pressure liquid in the temperature and pressure regions near the critical point, and can be appropriately selected according to the purpose in the present invention.

Examples of the supercritical fluid or subcritical fluid include carbon monoxide, carbon dioxide, ammonia, nitrogen, water, methanol, ethanol, ethane, propane, 2,3-dimethylbutane, benzene, chlorotrifluoromethane, and dimethyl ether. Are preferable. Among these, carbon dioxide can easily be in a supercritical state with a critical pressure of 7.3 MPa and a critical temperature of 31 ° C., and is nonflammable and highly safe, and since it is a non-aqueous solvent, a carrier with a hydrophobic surface can be obtained. In addition, since it is gasified simply by returning to normal pressure (releasing the pressure), it can be easily recovered and reused. The obtained carrier does not need to be dried, and since it does not generate waste liquid, it is friendly to the global environment. preferable.
The supercritical fluid or the subcritical fluid may be used alone as a single substance, or two or more kinds may be used in combination as a mixture. When two or more types are used in combination, it is only necessary to hold a supercritical fluid or a subcritical fluid.

The critical temperature and critical pressure of the supercritical fluid are not particularly limited and may be appropriately selected depending on the intended purpose. However, the critical temperature is preferably −273 to 300 ° C., preferably in the range of 0 to 200 ° C. Is more preferable. The lower the critical pressure, the more advantageous, for example, in terms of apparatus load, equipment cost, operating energy, etc., but in practice, 1 to 100 MPa is preferable, and the range of 1 to 50 MPa is more preferable. preferable.
In the present invention, the coating layer can be formed on the surface of the core material by positively utilizing the properties of the supercritical fluid or the subcritical fluid.
In addition, since the supercritical fluid can be easily separated from the target product and can be recovered and reused, it is possible to realize an innovative carrier production method with low environmental load that does not use conventional water or organic solvents.

In addition to the supercritical fluid or the subcritical fluid, other fluids can be used in combination. Such other fluid is preferably one that can easily control the solubility of the coating resin. Specifically, methane, ethane, propane, ethylene, and the like are preferable.
In addition to the supercritical fluid or the subcritical fluid, an entrainer (azeotropic agent) may be added. By adding this entrainer, the solubility of the coating resin can be improved. There is no restriction | limiting in particular as an entrainer, Although it can select suitably according to the objective, A polar organic solvent is preferable in this invention. Examples of the polar organic solvent include methanol, ethanol, propanol, butanol, hexane, toluene, ethyl acetate, chloroform, dichloromethane, ammonia, melamine, urea, thioethylene glycol, and the like. Among these, a lower alcohol solvent of about C _{1 to} C ₆ (preferably about C _{1 to} C ₄ ) exhibiting poor solvent properties at normal temperature and normal pressure is preferable.

The entrainer used in the present invention includes a core material and a coating resin, those in which fine particles do not dissolve, those that slightly swell or wet, specifically, a solubility parameter [SP value] and The difference from the [SP value] of the coating resin to be used is preferably 1.0 or more, more preferably 2.0 or more. For example, for a silicone resin, it is preferable to use alcohols such as methanol, ethanol and n-propanol having a high [SP value], or n-hexane, n-heptane and the like having a low [SP value]. If the difference in [SP value] is large, wetting of the coating resin with respect to the core material becomes worse, and good dispersion of the coating resin cannot be obtained. 5 is preferred.
Moreover, 0.1-10 mass% is preferable and, as for content of the entrainer in the mixed fluid of a supercritical fluid or a subcritical fluid, and an entrainer, 0.5-5 mass% is more preferable. When the content is less than 0.1% by mass, the effect as an entrainer (azeotropic effect) may be difficult to obtain. When the content exceeds 10% by mass, the properties of the entrainer as a liquid become strong. It may be difficult to obtain a supercritical or subcritical state.

-Resin for coating-
The coating resin used in the present invention is not particularly limited and may be appropriately selected from known resins according to the purpose. For example, amino resins, polyvinyl resins, polystyrene resins, halogens Olefin resin, polyester resin, polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, copolymer of vinylidene fluoride and acrylic monomer , Copolymers of vinylidene fluoride and vinyl fluoride, fluoroterpolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride, and non-fluorinated monomers (triple fluoride copolymers), silicone Resin, and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, a silicone resin is particularly preferable because of its high effect.

  The silicone resin that can be particularly preferably used is not particularly limited and can be appropriately selected from generally known silicone resins according to the purpose. For example, the silicone resin represented by the following structural formula (1) can be used. A straight silicone resin is preferred.

  In the structural formula (1), R represents a hydrogen atom, a hydroxyl group, an alkoxy group, a lower alkyl group, or an aryl group. Examples of the alkoxy group include a methoxy group and an ethoxy group. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Examples of the aryl group include a phenyl group, a tolyl group, and a xylyl group.

  The weight average molecular weight (Mw) of the silicone resin as a coating resin that can be used in the present invention is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 500 to 100,000, preferably 1,000 to A range of 10,000 is more preferred.

The molecular weight can be measured by the following method.
Gel permeation chromatography (GPC) measuring device: GPC-8220GPC (manufactured by Tosoh Corporation)
Column: TSKgel SuperHZM-H 15cm triple (made by Tosoh Corporation)
Temperature: 40 ° C
Solvent: THF
Flow rate: 0.35 ml / min
Sample: 0.4 ml of 0.15% sample was injected Sample pretreatment: 0.15 wt% of toner was dissolved in tetrahydrofuran (THF: Wako Pure Chemical Industries, Ltd.), and then filtered through a 0.2 μm filter. Used as 100 μl of the sample solution is injected and measured. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts (ie, the molecular weight calculated in terms of polystyrene). . As standard polystyrene samples for creating a calibration curve, Showdex STANDARD Std.No S-7300, S-210, S-390, S-875, S-1980, S-10.9, S-629, S-3.0 and S-0.580 toluene was used. An RI (refractive index) detector was used as the detector.

A silicone resin as a coating resin is preferably a solid at room temperature and normal pressure because it is superior in handling property, film formability, and film thickness controllability than liquid.
The silanol concentration of the silicone resin as the coating resin that can be used in the present invention is preferably 1 to 40% by mass, more preferably 1 to 20% by mass, and still more preferably 1 to 10% by mass for crosslinking after film formation. . When the silanol concentration exceeds 40% by mass, the crosslinked film tends to be hard and brittle, the durability is deteriorated, and unreacted silanol groups remain, so that the environmental stability of the carrier may be deteriorated. If it is less than 1%, the coating performance as a coating resin may be inferior.

As said silicone resin, what was synthesize | combined suitably may be used and a commercial item may be used. As this commercial item, as a straight silicone resin, KR271, KR255, KR220L, KR152 manufactured by Shin-Etsu Chemical Co., Ltd .; SR2400, SR2406, SR2410, 217 Flakes Resin, 220 Flakes Resin, 233 Flakes Resin manufactured by Toray Dow Corning 249 Flake Resin, Z-6018 Intermediate, and the like.
Examples of the modified silicone resin include KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), KR305 (urethane modified) manufactured by Shin-Etsu Chemical Co., Ltd .; SR2115 (epoxy) manufactured by Toray Dow Corning. Modification), SR2110 (alkyd modification), and the like.
It is possible to use the silicone resin alone, but it is also possible to simultaneously use a component that undergoes a crosslinking reaction, a charge amount adjusting component, and the like.

−Core material−
The core material used in the present invention is not particularly limited, and can be appropriately selected according to the purpose from those known as two-component carriers for electrophotography. For example, ferrite, magnetite, iron, nickel can be used. Preferably mentioned. In addition, in consideration of the environmental aspects that have advanced remarkably in recent years, if ferrite is used, for example, Mn ferrite, Mn-Mg ferrite, Mn-Mg-Sr ferrite, etc. should be used instead of the conventional copper-zinc ferrite. Is preferred.
The core material preferably has a volume average particle size of 20 μm or more from the viewpoint of prevention of carrier adhesion (scattering) to the electrostatic latent image carrier, and is intended to prevent deterioration of image quality such as prevention of occurrence of carrier streaks. To 100 [mu] m or less is preferable, and in particular, a volume average particle size of 20 to 50 [mu] m is more preferable for high image quality in recent years.
The measurement of the particle size of the core material was performed using a “Microtrac particle size analyzer SRA;

-Fine particles-
The fine particles used in the present invention are not particularly limited, and can be appropriately selected from those known as two-component carriers for electrophotography according to the purpose. For example, metal powders and various metal oxide particles Inorganic fine particles such as are preferably used. Among them, metal oxide particles such as silicon oxide, titanium oxide, and alumina can easily obtain particles having a uniform fine particle diameter, and various electrical characteristics and mechanical strength can be obtained depending on the particles used. It is also important that the fine particles are thermally stable even when the carrier is heated to a high temperature during the condensation curing of the silicone resin.

  Further, it is particularly preferable that the fine particles are fine particles having a hardness higher than that of the silicone polymer constituting the outer shell. In this case, the coating layer of the carrier is a contact portion between the carrier and the carrier, between the carrier and the toner, and between the carrier and the member in the developing device, and this portion has many opportunities to contact with other members. Since the core material is a hard magnetic powder, it is preferable that the fine particles have high hardness as well. That is, grinding can be prevented by having a higher hardness than the silicone polymer. The above metal oxide particles are representative of high hardness particles.

Moreover, the following fine particles can be contained in the material constituting the carrier surface for the purpose of adjusting electric resistance. An appropriate amount of one or more kinds may be used as necessary.
Conductive ZnO, metal powder such as Al, SnO ₂ doped with SnO2 and various elements made by various methods, borides, eg _{TlB 2, ZnB 2, MoB 2} , silicon carbide and the conductive polymer (polyacetylene , Polyparaphenylene, poly (para-phenylene sulfide), polypyrrole, parylene), carbon black and the like.

The most suitable silicone compound for the film has a high electric resistance and is generally known to have a high resistance. Therefore, it is preferable to use at least one kind of particles having a volume resistance of 10 ⁻⁶ Ωcm or less as a resistance adjuster for film resistance.

  Further, it is important that the conductive fine particles introduced for the purpose of adjusting the electric resistance have a sufficiently small particle diameter with respect to the film and can be uniformly dispersed in the film. It is not preferable to disturb the uneven shape of the film by the introduction of these conductive fine particles, and it is important for the effect of the film form to be expected to achieve uniform charge, toner retention and developability. . As a material satisfying these conditions, conductively treated metal oxide fine particles, carbon black, and the like are preferably used.

  On the other hand, if an extremely low resistance material such as carbon black is dispersed in a silicone film, the electrical properties of the film will change sensitively with respect to the carbon black content, so care must be taken when handling it. . For example, it is difficult to handle such as non-uniformity in electrical resistance between carriers, and carrier characteristics that are difficult to stabilize in response to slight process variations in the manufacturing process. This can be avoided by controlling the content accurately and making the dispersibility uniform in the film, but the electrical resistance control material contained in the film is a mixture of conductive carbon particles and non-conductive metal oxide particles. It may be used.

When the carrier thus obtained is used as a two-component developer, the measured electric resistance is preferably in the range of 10 ⁻⁷ to 10 ⁻¹⁶ Ωcm. The electrical resistance must be appropriately selected according to the development process using the carrier, but when it becomes 10 ⁻⁷ Ωcm or less, the spike shape of the carrier brush (magnetic brush) held on the developer carrier is not good. This is not preferable because the image density becomes dark and conspicuous. Also, if it exceeds 10 ⁻¹⁶ Ωcm, density difference between the edge part and the solid part of the image or density difference between the line image and the solid image may occur. Inconveniences such as carrier development (carrier adhesion) on the non-image portion of the toner are likely to occur.

  The electric resistance of the carrier is a value obtained from a current value and an applied voltage when a carrier is filled between two parallel electrodes and a potential difference is provided between the electrodes. Specifically, a container having electrodes arranged in parallel at an interval of 2 mm is filled with a carrier, and a direct current resistance at a potential difference of 500 V between both electrodes is measured by a 4329A High Resistance Meter manufactured by Yokogawa Hewlett-Packard Co., Ltd.

  For the same reason, the thickness of the carrier film is preferably set as appropriate so that the electric resistance is within an appropriate range. However, as silicone has a volume shrinkage during the condensation reaction, the film thickness increases. , There is a drawback that non-uniform reaction within the film tends to occur. Therefore, the film thickness is more preferably 1.0 μm or less.

The method for forming the coating layer is not particularly limited as long as the coating resin is dissolved or dispersed in the fluid containing the supercritical fluid or the subcritical fluid, and can be appropriately selected according to the purpose.
An apparatus for forming the coating layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a pressure-resistant container for dissolving or dispersing at least the coating resin, and the supercritical fluid The apparatus provided with the pressurization pump which supplies is mentioned suitably. As a treatment method using the apparatus, first, at least a coating resin is charged in the pressure vessel, the supercritical fluid is supplied into the pressure vessel by a pressure pump, and the supercritical fluid is supplied to the coating resin. A contact layer is formed on the surface of the core material by contact. When the supercritical fluid is returned to normal temperature and normal pressure, the supercritical fluid becomes a gas, so that removal of the solvent is unnecessary and waste water generated by washing is unnecessary, reducing the environmental load. The

  The temperature at which the coating layer is formed on the surface of the core material is not particularly limited as long as it is equal to or higher than the critical temperature of the supercritical fluid or the subcritical fluid to be used, and can be appropriately selected according to the purpose. However, 0-100 degreeC is specifically preferable and the range of 20-80 degreeC is more preferable. When the said temperature exceeds 100 degreeC, a core material may melt | dissolve.

  The pressure for forming the coating layer on the surface of the core material is not particularly limited as long as it is equal to or higher than the critical pressure of the supercritical fluid or the subcritical fluid to be used, and can be appropriately selected according to the purpose. However, the range of 1-60 MPa is preferable.

Here, a method for forming a coating layer on the surface of the core material will be described. As shown in FIG. 1, the apparatus used in the method for producing a carrier of the present invention is one having a reaction vessel 119 with a volume of about 1,000 cm ³ , for example. In FIG. 1, 112 is an entrainer tank (azeotropic agent reservoir), 113 and 114 are pressure pumps, 116 is a temperature sensor, 133 is an injection nozzle, and 134 is a pressure sensor.
Carbon dioxide (CO ₂ ) was used as the supercritical fluid gas. A composition containing a coating resin was put into the reaction vessel 119.

The carbon dioxide gas supplied from the gas cylinder 111 was pressurized by the pressurizing pump 113 and introduced into the reaction vessel 119 via the valve 117. At this time, the valve 115 is closed, and carbon dioxide gas is not introduced into the ejection container 132 side. Further, the pressure reducing valve 118 for discharging and ejecting is kept closed, carbon dioxide is introduced in a high pressure state, and the pressure in the reaction vessel 119 is increased. Further, the temperature in the reaction vessel 119 was adjusted to 320 K (to a temperature lower than 50 ° C.) by the heater 137.
The pressure in the reaction vessel 119 is set to 7.3 MPa or more to bring the reaction vessel 119 into a supercritical state. In addition, the valves 115 and 117 were adjusted so that the pressure in the reaction vessel 119 was set to 20 MPa, and the composition containing the coating resin in the reaction vessel 119 was set in a dissolved state. In this state, the valves 115 and 117 were closed, and this dissolved state was maintained in the reaction vessel 119 for 120 minutes to sufficiently diffuse and circulate the supercritical fluid. Thereafter, the valve 118 was opened, the pressure in the reaction vessel was adjusted to 10 MPa, and maintained for 60 minutes. Thereafter, carbon dioxide gas was again introduced from the high pressure pump side, and introduction of carbon dioxide was continued while maintaining the pressure in the reaction vessel at 10 MPa. At this time, the supercritical fluid carbon dioxide contained in the mixed solution and the composition containing at least the coating resin dissolved in the supercritical carbon dioxide were recovered by the recovery mechanism illustrated in FIGS. Further, the carbon dioxide and the composition containing at least the coating resin are separated from each other by a separation device (not shown) and reused. The line from the coating agent dissolution tank to the raw material recovery tank is as follows: coating agent dissolution tank → valve 5 → carrier processing tank → valve 7 → decompression pump 1 → raw material recovery tank.

  By continuing the introduction of supercritical carbon dioxide in this way, the composition containing at least the coating resin dissolved in the reaction vessel 119 (resin composition that does not contribute to the formation of the coating layer) is all discharged out of the vessel. In the reaction vessel 119, only the carrier having a coating layer formed on the surface of the core material and the supercritical carbon dioxide fluid are contained. Thereafter, when the valve is opened, the supercritical carbon dioxide fluid is vaporized and the carrier is manufactured.

Specifically, a coating layer can be formed on the surface of the core material using the apparatus shown in FIG.
As shown in FIG. 7, a coating resin and a catalyst are charged into a coating agent dissolution tank 119, the valve 3 (117) is opened while stirring, and carbon dioxide is supplied by the pressure pump 1 (113) to 25 MPa. After reaching 80 ° C., the valve 3 was closed. The carrier processing tank 132 was charged with ferrite core material and fine particles, and the valve 6 was opened while stirring, and carbon dioxide was supplied by the pressure pump 1 to 25 MPa and 80 ° C., and then the valve 6 was closed.
Next, the valve 3, the valve 5 and the valve 7 are opened, and the pressurizing pump 1 and the depressurizing pump 1 are operated to control the internal pressure to maintain the inside of the carrier processing tank at 25 MPa and 80 ° C. for 1 hour. The coating agent was saturated in the carrier treatment tank 132 by circulation (under normal pressure, flow rate = 1 L / min). Subsequently, the valve 3 was closed and the pressure was returned to normal pressure by the vacuum pump 1 over 2 hours. The coating agent that was not used could be recovered from both the coating agent dissolution tank and the raw material recovery tank and reused.
The resulting ferrite core material coated with the silicone resin was heated at 200 ° C. for 1 hour to produce a carrier.

Further, using the apparatus shown in FIG. 8, a silicone resin and a catalyst were charged as a coating resin in the coating agent dissolution tank 119.
The carrier processing column is charged with ferrite core material and fine particles, and the valve 3 is opened while stirring the coating agent dissolution tank 119. Carbon dioxide is supplied by the pressure pump 1 to 25 MPa and 60 ° C., and then the valve 3 is set. Closed.
Next, the valve 3, the valve 5 and the valve 7 are opened and the pressure pump 1 and the pressure reduction pump 1 are operated to control the internal pressure to maintain the inside of the carrier processing column at 25 MPa and 60 ° C. for 1 hour. Was allowed to flow (under normal pressure, flow rate = 1 L / min), and the coating agent was saturated in the carrier treatment column. The valve 3 was closed and the pressure was returned to normal pressure with the vacuum pump 1 over 2 hours. The coating agent that was not used could be recovered from both the coating agent dissolution tank and the raw material recovery tank and reused.
The obtained ferrite core material coated with the silicone resin was heated at 200 ° C. for 1 hour to produce a carrier.

Further, using the apparatus shown in FIG. 9, a silicone resin and a catalyst are charged as a coating resin in the coating agent dissolution tank, and the valve 3 is opened and stirred while supplying carbon dioxide with the pressure pump 1. A carrier coating solution was prepared at 0 ° C.
Next, a ferrite core material and fine particles are charged into a fluidized bed type carrier treatment tank, the valve 6 is opened, the inside of the tank is set to 3 MPa and 100 ° C., the valve 6 is closed, and then the valves 5 and 7 are opened. The vacuum pump 1 was operated, the internal pressure was controlled so that the inside of the carrier treatment tank did not become 7 MPa or more, and the carrier coat liquid was applied over 40 minutes while stirring. The coating agent that was not used could be recovered from both the coating agent dissolution tank and the raw material recovery tank and reused.
The resulting ferrite core material coated with the silicone resin was heated at 200 ° C. for 1 hour to produce a carrier.

Further, using the apparatus shown in FIG. 10, a silicone resin and a catalyst are charged as a coating resin in a coating agent dissolution tank, a ferrite core material and fine particles are charged in a carrier treatment tank, and valves 3 and 5 are opened. While supplying carbon dioxide with the pressure pump 1 and stirring, a ferrite dispersion was produced at 15 MPa and 80 ° C. The obtained ferrite dispersion was sprayed (rapid expansion) from a nozzle of a spray tank in an atmosphere of 30 ° C. under normal pressure. The coating agent that was not used could be recovered from both the coating agent dissolution tank and the raw material recovery tank and reused.
The resulting ferrite core material coated with the silicone resin was heated at 200 ° C. for 1 hour to produce a carrier.

(Developer)
The developer of the present invention is a two-component developer containing the carrier produced as described above and a toner.
The mixing ratio of the toner and the carrier in the developer is 1 to 10.0 parts by mass of the toner with respect to 100 parts by mass of the carrier.
The toner includes at least a binder resin and a colorant, and further includes a release agent, a charge control agent, and other components as necessary.

<Toner>
The method for producing the toner used in the present invention is not particularly limited and can be appropriately selected according to the purpose. The toner base particles are obtained by emulsifying, suspending or agglomerating the oil phase in an aqueous medium. There are a suspension polymerization method, an emulsion polymerization method, a polymer suspension method and the like to be formed. Among these, the polymer suspension method is particularly preferable.

-Binder resin-
The binder resin is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, a homopolymer of styrene such as polystyrene, poly-p-styrene, polyvinyltoluene, or a substituted product thereof. Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer Polymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer Polymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone Copolymer, styrene-butadiene copolymer, styrene-isopropyl copolymer, styrene-copolymer such as styrene-maleic ester copolymer, polythyme methacrylate resin, polybutyl methacrylate resin, polyvinyl chloride resin , Polyvinyl acetate resin, polyethylene resin, polyester resin, polyurethane resin, epoxy resin, polyvinyl butyral resin, polyacrylic acid resin, rosin resin, modified rosin resin, terpene resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic A group petroleum resin can be used alone or in combination.

-Colorant-
The colorant is not particularly limited and may be appropriately selected from known dyes and pigments according to the purpose. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), Cadmium yellow, Yellow iron oxide, Ocher, Yellow lead, Titanium yellow, Polyazo yellow, Oil yellow, Hansa yellow (GR, A, RN, R), Pigment yellow L, Benzidine yellow (G, GR) , Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Tan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimony Zhu, Permanent Red 4R, Parallel , Faise red, parachlor ortho nitroaniline red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Risor Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, rhodamine lake Y, alizarin lake, thioindigo red B, thioindigo maroon, oil le Quinacridone red, pyrazolone red, polyazo red, chrome vermilion, benzidine orange, perinone orange, oil orange, cobalt blue, cerulean blue, alkaline blue rake, peacock blue rake, Victoria blue rake, metal-free phthalocyanine blue, phthalocyanine blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine Blue, Bitumen, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Oxidation Chrome, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Guri Enlake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, lithopone, and the like.
These may be used individually by 1 type and may use 2 or more types together.
The content of the colorant in the toner is preferably 1 to 15% by mass, and more preferably 3 to 10% by mass.

  The colorant may be used as a master batch combined with a resin. The resin is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, styrene or a substituted polymer thereof, styrene copolymer, polymethyl methacrylate resin, polybutyl Methacrylate resin, polyvinyl chloride resin, polyvinyl acetate resin, polyethylene resin, polypropylene resin, polyester resin, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic hydrocarbon resin, alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin and the like. These may be used individually by 1 type and may use 2 or more types together.

-Release agent-
There is no restriction | limiting in particular as said mold release agent, According to the objective, it can select suitably from well-known things, For example, waxes etc. are mentioned suitably.
Examples of the waxes include carbonyl group-containing waxes, polyolefin waxes, long chain hydrocarbons, and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, a carbonyl group-containing wax is preferable.
Examples of the carbonyl group-containing wax include polyalkanoic acid esters, polyalkanol esters, polyalkanoic acid amides, polyalkylamides, dialkyl ketones, and the like. Examples of the polyalkanoic acid ester include carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, and 1,18-octadecane. Examples thereof include diol distearate. Examples of the polyalkanol ester include tristearyl trimellitic acid and distearyl maleate. Examples of the polyalkanoic acid amide include dibehenyl amide. Examples of the polyalkylamide include trimellitic acid tristearylamide. Examples of the dialkyl ketone include distearyl ketone. Of these carbonyl group-containing waxes, polyalkanoic acid esters are particularly preferred.
Examples of the polyolefin wax include polyethylene wax and polypropylene wax.
Examples of the long chain hydrocarbon include paraffin wax and sazol wax.

There is no restriction | limiting in particular as melting | fusing point of the said mold release agent, Although it can select suitably according to the objective, 40-160 degreeC is preferable, 50-120 degreeC is more preferable, The range of 60-90 degreeC is especially preferable. .
When the melting point is less than 40 ° C., the wax may adversely affect the heat-resistant storage stability, and when it exceeds 160 ° C., cold offset may easily occur during fixing at a low temperature.
The melt viscosity of the release agent is preferably 5 to 1000 cps (5 to 1000 mPa · S), more preferably 10 to 100 cps, as measured at a temperature 20 ° C. higher than the melting point of the wax.
If the melt viscosity is less than 5 cps, the releasability may be lowered, and if it exceeds 1000 cps, the effect of improving hot offset resistance and low-temperature fixability may not be obtained.

There is no restriction | limiting in particular as content in the said toner of the said mold release agent, Although it can select suitably according to the objective, 1-40 mass% (weight%) is preferable and the range of 3-30 mass% is preferable. More preferred.
When the content exceeds 40% by mass, the fluidity of the toner may be deteriorated.

-Charge control agent-
The charge control agent is not particularly limited, and a positive or negative charge control agent can be appropriately selected and used depending on whether the charge charged on the photoconductor is positive or negative.
As the negative charge control agent, for example, a resin or compound having an electron donating functional group, an azo dye, a metal complex of an organic acid, or the like can be used. Specifically, Bontron (product numbers: S-31, S-32, S-34, S-36, S-37, S-39, S-40, S-44, E-81, E-82, E -84, E-86, E-88, A, 1-A, 2-A, 3-A) (above, manufactured by Orient Chemical Industry Co., Ltd.)), Kaya Charge (part numbers: N-1, N-2), Kaya Set Black (Part No .: T-2, 004) (Nippon Kayaku Co., Ltd.), Eisenspiron Black (T-37, T-77, T-95, TRH, TNS-2) FCA-1001-N, FCA-1001-NB, FCA-1001-NZ (manufactured by Fujikura Kasei Co., Ltd.), and the like.
As the positive charge control agent, for example, a basic compound such as a nigrosine dye, a cationic compound such as a quaternary ammonium salt, a metal salt of a higher fatty acid, or the like can be used. Specifically, Bontron (part numbers: N-01, N-02, N-03, N-04, N-05, N-07, N-09, N-10, N-11, N-13, P -51, P-52, AFP-B) (above, manufactured by Orient Chemical Co., Ltd.), TP-302, TP-415, TP-4040 (above, manufactured by Hodogaya Chemical Co., Ltd.), Copy Blue PR, Copy Charge ( Product number: PX-VP-435, NX-VP-434) (manufactured by Hoechst), FCA (Product number: 201, 201-B-1, 201-B-2, 201-B-3, 201-PB, 201-PZ, 301) (above, manufactured by Fujikura Kasei Co., Ltd.), PLZ (product numbers: 1001, 2001, 6001, 7001) (above, manufactured by Shikoku Kasei Kogyo Co., Ltd.), and the like.
These may be used individually by 1 type and may use 2 or more types together.

  The addition amount of the charge control agent is determined by the toner production method including the type of the binder resin and the dispersion method, and is not limited to a specific one. 0.1-10 mass parts is preferable with respect to 0.2-5 mass parts. When the addition amount exceeds 10 parts by mass, the chargeability of the toner is too large, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is reduced, and the image density is increased. If the amount is less than 0.1 parts by mass, the charge rise and charge amount are insufficient, and the toner image may be easily affected.

  In addition to the binder resin, the release agent, the colorant, and the charge control agent, the toner material includes inorganic fine particles, a fluidity improver, a cleaning property improver, a magnetic material, a metal soap, and the like as necessary. Can be added.

Examples of the inorganic fine particles include silica, titania, alumina, cerium oxide, strontium titanate, calcium carbonate, magnesium carbonate, calcium phosphate, etc., and silica hydrophobized with silicone oil, hexamethyldisilazane, or the like. It is more preferable to use fine particles or titanium oxide subjected to a specific surface treatment.
Examples of the silica fine particles include, for example, Aerosil (product numbers: 130, 200 V, 200 CF, 300, 300 CF, 380, OX50, TT600, MOX80, MOX170, COK84, RX200, RY200, R972, R974, R976, R805, R811, R812, T805, R202, VT222, RX170, RXC, RA200, RA200H, RA200HS, RM50, RY200, REA200 (above, manufactured by Nippon Aerosil Co., Ltd.), HDK (Part No .: H20, H2000, H3004, H2000 / 4, H2050EP, H2015EP, H3050EP) , KHD50), HVK2150 (above, manufactured by Wacker Chemical Co., Ltd.), Cabogil (Part No .: L-90, LM-130, LM-150, M-5, PTG, MS-55, H-5) HS-5, EH-5, LM-150D, M-7D, MS-75D, TS-720, TS-610, TS-530) (or, can be used Cabot Corp.).
The addition amount of the inorganic fine particles is preferably 0.1 to 5.0 parts by mass, and more preferably 0.8 to 3.2 parts by mass with respect to 100 parts by mass of the toner base particles.

  The above toner materials are mixed, and the mixture is charged into a melt kneader and melt kneaded. As the melt kneader, for example, a uniaxial or biaxial continuous kneader or a batch kneader using a roll mill can be used. For example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type extruder manufactured by Toshiba Machine Co., Ltd., twin screw extruder manufactured by Casey Kay Co., Ltd. Preferably used. This melt-kneading is preferably performed under appropriate conditions so as not to cause the molecular chains of the binder resin to be broken. Specifically, the melt kneading temperature is performed with reference to the softening point of the binder resin. If the temperature is higher than the softening point, cutting is severe, and if the temperature is too low, dispersion may not proceed.

  In pulverization, the kneaded product obtained by the kneading is pulverized. In this pulverization, it is preferable that the kneaded material is first coarsely pulverized and then finely pulverized. At this time, a method of pulverizing by colliding with a collision plate in a jet stream, pulverizing particles by colliding with each other in a jet stream, or pulverizing with a narrow gap between a mechanically rotating rotor and a stator is preferably used.

In the classification, the pulverized product obtained by the pulverization is classified and adjusted to particles having a predetermined particle diameter. Classification can be performed, for example, by removing fine particle portions by a cyclone, a decanter, centrifugation, or the like.
After the pulverization and classification are completed, the pulverized product is classified into an air stream by centrifugal force or the like to produce a toner having a predetermined particle size.

  Further, in order to improve the fluidity, storage stability, developability and transferability of the toner, inorganic fine particles such as hydrophobic silica fine powder may be further added to and mixed with the toner base particles produced as described above. In general, a powder mixer is used to mix the additives, but it is preferable to equip a jacket or the like to adjust the internal temperature. In order to change the load history applied to the additive, the additive may be added midway or gradually. In this case, you may change the rotation speed, rolling speed, time, temperature, etc. of a mixer. Also, a strong load may be given first, then a relatively weak load, or vice versa. Examples of the mixing equipment that can be used include a V-type mixer, a rocking mixer, a Ladige mixer, a Nauter mixer, and a Henschel mixer. Next, the toner is obtained by passing through a sieve of 250 mesh or more to remove coarse particles and aggregated particles.

  The shape, size, etc. of the toner are not particularly limited and can be appropriately selected according to the purpose. The average circularity, volume average particle size, volume average particle size and number are as follows. It is preferable to have a ratio to the average particle size (volume average particle size / number average particle size).

The average circularity is a value obtained by dividing the perimeter of an equivalent circle having the same projected shape as the toner shape by the perimeter of the actual particles, and is preferably 0.900 to 0.980, for example, 0.950 to 0 .975 is more preferred. Note that particles having an average circularity of less than 0.94 are preferably 15% or less.
If the average circularity is less than 0.900, satisfactory transferability and a high-quality image free from dust may not be obtained. If the average circularity exceeds 0.980, image formation employing blade cleaning or the like is employed. In the system, defective cleaning occurs on the photoconductor and the transfer belt, and in the case of image formation with a high image area ratio such as a photographic image, an untransferred image is formed due to defective paper feeding, etc. The accumulated toner may become a transfer residual toner on the photoconductor, resulting in background smearing of the image, or it may contaminate the charging roller for charging the photoconductor in contact with the original charging ability. It may become impossible to demonstrate.

  The average circularity is measured using a flow type particle image analyzer (“FPIA-2100”; manufactured by Sysmex Corporation), and analyzed using analysis software (FPIA-2100 Data Processing Program for FPIA version 00-10). It was. Specifically, 0.1 to 0.5 ml of 10 wt% surfactant (alkylbenzene sulfonate Neogen SC-A; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is added to a glass 100 ml beaker, and each toner 0.1 0.5 g was added and stirred with microspatel, and then 80 ml of ion-exchanged water was added. The obtained dispersion was subjected to a dispersion treatment for 3 minutes with an ultrasonic disperser (manufactured by Honda Electronics Co., Ltd.). The shape and distribution of the toner were measured using the FPIA-2100 until the density of the dispersion was 5000 to 15000 / μl. In this measurement method, it is important that the concentration of the dispersion liquid is 5000 to 15000 / μl from the viewpoint of measurement reproducibility of the average circularity. In order to obtain the dispersion concentration, it is necessary to change the conditions of the dispersion, that is, the amount of surfactant to be added and the amount of toner. The amount of the surfactant varies depending on the hydrophobicity of the toner as in the measurement of the toner particle diameter described above. If it is added in a large amount, noise due to bubbles is generated. If the amount is too small, the toner cannot be sufficiently wetted. It becomes insufficient. Further, the amount of toner added varies depending on the particle size, and it is small for small particle sizes and needs to be increased for large particle sizes. When the toner particle size is 3 to 10 μm, the toner amount is 0.1 to 0.3. By adding 5 g, the dispersion concentration can be adjusted to 5000 to 15000 / μl.

The volume average particle diameter of the toner is not particularly limited and may be appropriately selected depending on the intended purpose. For example, it is preferably 3 to 10 μm, and more preferably 3 to 8 μm.
When the volume average particle size is less than 3 μm, in the case of a two-component developer, the toner may be fused to the surface of the carrier during a long period of stirring in the developing device, and the charging ability of the carrier may be reduced. Therefore, it becomes difficult to obtain a high-resolution and high-quality image, and when the balance of the toner in the developer is performed, the fluctuation of the toner particle diameter may increase.

  The ratio of the volume average particle diameter to the number average particle diameter (volume average particle diameter / number average particle diameter) in the toner is preferably 1.00 to 1.25, more preferably 1.10 to 1.25.

  The volume average particle diameter, and the ratio of the volume average particle diameter to the number average particle diameter (volume average particle diameter / number average particle diameter) are determined using a particle size measuring device (“Multisizer III” manufactured by Beckman Coulter, Inc.). The measurement was performed with an aperture diameter of 100 μm, and analysis was performed with analysis software (Beckman Coulter Multisizer 3 Version 3.51). Specifically, 0.5 ml of 10 wt% surfactant (alkylbenzene sulfonate Neogen SC-A; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is added to a 100 ml glass beaker, 0.5 g of each toner is added, and the mixture is mixed with a micropartel. Then, 80 ml of ion exchange water was added. The obtained dispersion was subjected to a dispersion treatment for 10 minutes with an ultrasonic disperser (W-113MK-II, manufactured by Honda Electronics Co., Ltd.). The dispersion was measured using the Multisizer III and Isoton III (manufactured by Beckman Coulter, Inc.) as the measurement solution. In the measurement, the toner sample dispersion was dropped so that the concentration indicated by the apparatus was 8 ± 2%. In this measurement method, it is important that the concentration is 8 ± 2% from the viewpoint of the reproducibility of the particle size. Within this concentration range, no error occurs in the particle size.

  The coloration of the toner is not particularly limited and may be appropriately selected according to the purpose, and may be at least one selected from black toner, cyan toner, magenta toner, and yellow toner. Can be obtained by appropriately selecting the type of the colorant, and is preferably a color toner.

(Container with developer)
The developer-containing container is obtained by accommodating the developer of the present invention in a container.
There is no restriction | limiting in particular as said container, It can select suitably from well-known things, For example, what has a developer container main body and a cap etc. are mentioned suitably.
The size, shape, structure, material and the like of the developer container body are not particularly limited and can be appropriately selected according to the purpose. For example, the shape is preferably cylindrical. A spiral irregularity is formed on the peripheral surface, the toner as the contents can be transferred to the discharge port side by rotating, and a part or all of the spiral part has a bellows function, etc. Is particularly preferred.
The material of the developer container main body is not particularly limited, and those having good dimensional accuracy are preferable. For example, a resin is preferable, and among them, for example, polyester resin, polyethylene resin, polypropylene resin, polystyrene resin, Preferable examples include vinyl chloride resin, polyacrylic acid, polycarbonate resin BS resin, and polyacetal resin.
Such a container containing a developer is easy to store and transport, has excellent handleability, and is preferably used for replenishing the developer by being detachably attached to the process cartridge and image forming apparatus of the present invention described later. Can do.

(Process cartridge)
The process cartridge of the present invention develops an electrostatic latent image carrier carrying an electrostatic latent image and the electrostatic latent image carried on the electrostatic latent image carrier using a developer to form a visible image. And at least developing means for forming the film, and other means appropriately selected as necessary.
The developing means includes at least a developer container that contains the developer of the present invention, and a developer carrier that carries and conveys the developer contained in the developer container. Further, a layer thickness regulating member for regulating the thickness of the toner layer to be carried may be provided.

Here, for example, as shown in FIG. 2, the process cartridge includes a photosensitive member 101, includes a charging unit 102, a developing unit 104, and a cleaning unit 107, and further includes other members as necessary. Become. Reference numeral 103 denotes exposure means.
As the photoreceptor 101, the same one as an image forming apparatus described later can be used.
An arbitrary charging member is used as the charging unit 102.
The process cartridge of the present invention can be detachably provided in various electrophotographic apparatuses, and is preferably provided detachably in the electrophotographic apparatus of the present invention described later.

(Image forming method and image forming apparatus)
The image forming method of the present invention includes at least an electrostatic latent image forming step, a developing step, a transfer step, and a fixing step, and other steps appropriately selected as necessary, for example, a static elimination step, a cleaning step. , Including recycling process, control process, etc.
The image forming apparatus of the present invention includes at least an electrostatic latent image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, and a fixing unit, and further appropriately selected as necessary. It has other means, for example, static elimination means, cleaning means, recycling means, control means and the like.

The electrostatic latent image forming step is a step of forming an electrostatic latent image on the electrostatic latent image carrier.
The electrostatic latent image carrier (sometimes referred to as “electrophotographic photosensitive member” or “photosensitive member”) is not particularly limited in terms of material, shape, structure, size, etc. Although it can be selected as appropriate, the shape thereof is preferably a drum shape, and examples of the material thereof include inorganic photoreceptors such as amorphous silicon and selenium, organic photoreceptors (OPC) such as polysilane and phthalopolymethine, and the like. Is mentioned. Among these, amorphous silicon or the like is preferable in terms of long life.

The formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the electrostatic latent image carrier and then performing imagewise exposure, and is performed by the electrostatic latent image forming unit. be able to.
The electrostatic latent image forming means includes, for example, at least a charger that uniformly charges the surface of the electrostatic latent image carrier and an exposure device that exposes the surface of the electrostatic latent image carrier imagewise. Prepare.

The charging can be performed, for example, by applying a voltage to the surface of the electrostatic latent image carrier using the charger.
The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charging device including a conductive or semiconductive roll, brush, film, rubber blade, etc. And non-contact chargers using corona discharge such as corotrons and corotrons.
Further, the charger is preferably one that is arranged in contact or non-contact with the electrostatic latent image carrier and charges the surface of the electrostatic latent image carrier by applying DC and AC voltages in a superimposed manner.
Further, the charger is a charging roller disposed in a non-contact proximity to the electrostatic latent image carrier via a gap tape, and the electrostatic latent image is carried by applying a direct current and an alternating voltage to the charging roller. Those that charge the body surface are preferred.

The exposure can be performed, for example, by exposing the surface of the latent electrostatic image bearing member imagewise using the exposure device.
The exposure device is not particularly limited as long as it can expose the surface of the electrostatic latent image carrier charged by the charger so as to form an image to be formed, and is appropriately selected according to the purpose. For example, various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system can be used.
In the present invention, a back light system in which imagewise exposure is performed from the back side of the electrostatic latent image carrier may be employed.

-Development process and development means-
The developing step is a step of developing the electrostatic latent image using the developer of the present invention to form a visible image.
The visible image can be formed, for example, by developing the electrostatic latent image using the developer of the present invention, and can be performed by the developing unit.
The developing means is not particularly limited as long as it can be developed using, for example, the developer of the present invention, and can be appropriately selected from known ones. For example, the developer of the present invention is accommodated. It is preferable to have at least a developing device capable of applying the developer to the electrostatic latent image in a contact or non-contact manner, and a developing device including the developer-containing container is more preferable.

  The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multi-color developing unit. For example, a developer having a stirrer for charging the developer by frictional stirring and a rotatable magnet roller is preferable.

In the developing device, for example, the toner and the carrier are mixed and agitated, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. . Since the magnet roller is disposed in the vicinity of the electrostatic latent image carrier (photoconductor), a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is electrically attracted. It moves to the surface of the electrostatic latent image carrier (photoconductor) by force. As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the electrostatic latent image carrier (photoconductor).
The developer accommodated in the developing device is the developer of the present invention.

-Transfer process and transfer means-
The transfer step is a step of transferring the visible image onto a recording medium. After the primary transfer of the visible image onto the intermediate transfer member using an intermediate transfer member, the visible image is transferred onto the recording medium. A primary transfer step of forming a composite transfer image by transferring a visible image onto an intermediate transfer body using two or more colors, preferably full color toner as the toner, and a composite transfer image; A mode including a secondary transfer step of transferring the transfer image onto the recording medium is more preferable.
The transfer can be performed, for example, by charging the latent electrostatic image bearing member (photoconductor) of the visible image using a transfer charger, and can be performed by the transfer unit. The transfer means includes a primary transfer means for transferring a visible image onto an intermediate transfer member to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium. Embodiments are preferred.
The intermediate transfer member is not particularly limited and may be appropriately selected from known transfer members according to the purpose. For example, a transfer belt and the like are preferable.

The transfer means (the primary transfer means and the secondary transfer means) is a transfer for peeling and charging the visible image formed on the electrostatic latent image carrier (photoconductor) to the recording medium side. It is preferable to have at least a vessel. There may be one transfer means or two or more transfer means.
Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is not particularly limited and can be appropriately selected from known recording media (recording paper).

The fixing step is a step of fixing the visible image transferred to the recording medium using a fixing device, and may be performed each time the toner of each color is transferred to the recording medium, or for the toner of each color. You may perform this simultaneously in the state which laminated | stacked this.
There is no restriction | limiting in particular as said fixing device, Although it can select suitably according to the objective, A well-known heating-pressing means is suitable. Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt.
The fixing device includes a heating body including a heating element, a film in contact with the heating body, and a pressure member in pressure contact with the heating body through the film, and the film and the pressure member It is preferably a unit that heats and fixes a recording medium on which an unfixed image is formed.
The heating in the heating and pressing means is usually preferably 80 to 200 ° C.
In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing step and the fixing unit depending on the purpose.

The neutralization step is a step of performing neutralization by applying a neutralization bias to the electrostatic latent image carrier, and can be suitably performed by a neutralization unit.
The neutralization means is not particularly limited, and may be appropriately selected from known neutralizers as long as it can apply a neutralization bias to the electrostatic latent image carrier. Preferably mentioned.

The cleaning step is a step of removing the electrophotographic toner remaining on the electrostatic latent image carrier, and can be suitably performed by a cleaning unit.
The cleaning means is not particularly limited as long as it can remove the electrophotographic toner remaining on the electrostatic latent image carrier, and can be appropriately selected from known cleaners. Suitable examples include brush cleaners, electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

The recycling step is a step of recycling the electrophotographic color toner removed in the cleaning step to the developing unit, and can be suitably performed by the recycling unit.
There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.

The control means controls the steps, and each step can be suitably performed by the control means.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

  An embodiment of the image forming method of the present invention will be described with reference to FIG. An image forming apparatus 100 shown in FIG. 3 includes a photosensitive drum 10 (hereinafter referred to as “photosensitive member 10”) as the electrostatic latent image carrier, a charging roller 20 as the charging unit, and an exposure as the exposure unit. The apparatus 30 includes a developing device 40 as the developing means, an intermediate transfer member 50, a cleaning device 60 as the cleaning means having a cleaning blade, and a static elimination lamp 70 as the static elimination means.

  The intermediate transfer member 50 is an endless belt, and is designed to be movable in the direction of an arrow by three rollers 51 that are arranged inside and stretched. Part of the three rollers 51 also functions as a transfer bias roller that can apply a predetermined transfer bias (primary transfer bias) to the intermediate transfer member 50. The intermediate transfer body 50 is provided with a cleaning device 90 having a cleaning blade in the vicinity thereof, and for transferring (secondary transfer) a developed image (toner image) to a transfer sheet 95 as a final transfer material. A transfer roller 80 serving as a transfer unit to which a transfer bias can be applied is disposed to face the transfer roller 80. Around the intermediate transfer member 50, a corona charger 58 for applying a charge to the toner image on the intermediate transfer member 50 is arranged between the photosensitive member 10 and the intermediate transfer member 50 in the rotation direction of the intermediate transfer member 50. It is disposed between the contact portion and the contact portion between the intermediate transfer member 50 and the transfer paper 95.

  The developing device 40 includes a developing belt 41 as the developer carrying member, and a black developing unit 45K, a yellow developing unit 45Y, a magenta developing unit 45M, and a cyan developing unit 45C provided around the developing belt 41. . The black developing unit 45K includes a developer accommodating portion 42K, a developer supplying roller 43K, and a developing roller 44K. The yellow developing unit 45Y includes a developer accommodating portion 42Y, a developer supplying roller 43Y, and a developing roller 44Y. The magenta developing unit 45M includes a developer accommodating portion 42M, a developer supplying roller 43M, and a developing roller 44M, and the cyan developing unit 45C includes a developer accommodating portion 42C and a developer supplying roller 43C. And a developing roller 44C. The developing belt 41 is an endless belt, is rotatably stretched around a plurality of belt rollers, and a part thereof is in contact with the photoconductor 10.

  In the image forming apparatus 100 shown in FIG. 3, for example, the charging roller 20 uniformly charges the photosensitive drum 10. The exposure device 30 performs imagewise exposure on the photosensitive drum 10 to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 10 is developed by supplying toner from the developing device 40 to form a visible image (toner image). The visible image (toner image) is transferred (primary transfer) onto the intermediate transfer member 50 by the voltage applied from the roller 51, and further transferred (secondary transfer) onto the transfer paper 95. As a result, a transfer image is formed on the transfer paper 95. The residual toner on the photoconductor 10 is removed by the cleaning device 60, and the charge on the photoconductor 10 is temporarily removed by the charge eliminating lamp 70.

  Another mode for carrying out the image forming method of the present invention by the image forming apparatus of the present invention will be described with reference to FIG. The image forming apparatus 100 shown in FIG. 4 does not include the developing belt 41 in the image forming apparatus 100 shown in FIG. 3, and a black developing unit 45K, a yellow developing unit 45Y, a magenta developing unit 45M, and the like around the photoconductor 10. Except for the fact that the cyan developing unit 45C is arranged directly opposite, it has the same configuration as the image forming apparatus 100 shown in FIG. In FIG. 4, the same components as those in FIG. 3 are denoted by the same reference numerals.

Another mode for carrying out the image forming method of the present invention by the image forming apparatus of the present invention will be described with reference to FIG. The tandem image forming apparatus shown in FIG. 5 is a tandem type color image forming apparatus. The tandem image forming apparatus includes a copying apparatus main body 150, a paper feed table 200, a scanner 300, and an automatic document feeder (ADF) 400.
The copying apparatus main body 150 is provided with an endless belt-like intermediate transfer member 50 at the center. The intermediate transfer member 50 is stretched around the support rollers 14, 15 and 16, and can be rotated clockwise in FIG. 5. An intermediate transfer member cleaning device 17 for removing residual toner on the intermediate transfer member 50 is disposed in the vicinity of the support roller 15. The intermediate transfer member 50 stretched between the support roller 14 and the support roller 15 is a tandem type in which four image forming units 18 of yellow, cyan, magenta, and black are arranged to face each other along the conveyance direction. A developing device 120 is disposed. An exposure device 21 is disposed in the vicinity of the tandem developing device 120. A secondary transfer device 22 is disposed on the side of the intermediate transfer member 50 opposite to the side on which the tandem developing device 120 is disposed. In the secondary transfer device 22, a secondary transfer belt 24, which is an endless belt, is stretched around a pair of rollers 23, and the transfer paper conveyed on the secondary transfer belt 24 and the intermediate transfer body 50 are in contact with each other. Is possible. A fixing device 25 is disposed in the vicinity of the secondary transfer device 22. The fixing device 25 includes a fixing belt 26 that is an endless belt, and a pressure roller 27 that is pressed against the fixing belt 26.
In the tandem image forming apparatus, a sheet reversing device 28 for reversing the transfer paper for image formation on both sides of the transfer paper is disposed in the vicinity of the secondary transfer device 22 and the fixing device 25. .

  Next, formation of a full-color image (color copy) using the tandem developing device 120 will be described. That is, first, a document is set on the document table 130 of the automatic document feeder (ADF) 400, or the automatic document feeder 400 is opened and the document is set on the contact glass 32 of the scanner 300. 400 is closed.

  When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the contact glass 32. Immediately after that, the scanner 300 is driven, and the first traveling body 33 and the second traveling body 34 travel. At this time, light from the light source is irradiated by the first traveling body 33 and reflected light from the document surface is reflected by the mirror in the second traveling body 34 and is received by the reading sensor 36 through the imaging lens 35 to be color. An original (color image) is read and used as black, yellow, magenta, and cyan image information.

  Each image information of black, yellow, magenta and cyan is stored in each image forming unit 18 (black image forming unit, yellow image forming unit, magenta image forming unit, and cyan image forming unit) in the tandem type developing device 120. Each of the image forming means forms toner images of black, yellow, magenta, and cyan. That is, each image forming means 18 (black image forming means, yellow image forming means, magenta image forming means, and cyan image forming means) in the tandem developing device 120 is respectively shown in FIG. A photoconductor 10 (black photoconductor 10K, yellow photoconductor 10Y, magenta photoconductor 10M, and cyan photoconductor 10C), a charger 60 for uniformly charging the photoconductor, and each color image information An exposure unit that exposes the photoconductor on each color image-corresponding image (L in FIG. 6) to form an electrostatic latent image corresponding to each color image on the photoconductor, and the electrostatic latent image Are developed with each color toner (black toner, yellow toner, magenta toner, and cyan toner) to form a toner image with each color toner, and the toner image is intermediately transferred. A transfer charger 62 for transferring onto the body 50, a photoconductor cleaning device 63, and a static eliminator 64 are provided, and each single color image (black image, yellow image, Magenta image and cyan image) can be formed. The black image, the yellow image, the magenta image, and the cyan image formed in this way are formed on the black photoconductor 10K on the intermediate transfer member 50 that is rotated by the support rollers 14, 15, and 16, respectively. The black image, the yellow image formed on the yellow photoconductor 10Y, the magenta image formed on the magenta photoconductor 10M, and the cyan image formed on the cyan photoconductor 10C are sequentially transferred (primary transfer). Is done. Then, the black image, the yellow image, the magenta image, and the cyan image are superimposed on the intermediate transfer member 50 to form a composite color image (color transfer image).

  On the other hand, in the paper feed table 200, one of the paper feed rollers 142 is selectively rotated to feed out a sheet (recording paper) from one of the paper feed cassettes 144 provided in multiple stages in the paper bank 143. Each sheet is separated and sent to the paper feed path 146, transported by the transport roller 147, guided to the paper feed path 148 in the copying machine main body 150, and abutted against the registration roller 49 and stopped. Alternatively, the sheet feed roller 142 is rotated to feed out sheets (recording paper) on the manual feed tray 54, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped. . The registration roller 49 is generally used while being grounded, but may be used in a state where a bias is applied to remove paper dust from the sheet. Then, the registration roller 49 is rotated in synchronization with the synthesized color image (color transfer image) synthesized on the intermediate transfer member 50, and a sheet (recording paper) is interposed between the intermediate transfer member 50 and the secondary transfer device 22. The secondary color transfer device 22 transfers the composite color image (color transfer image) onto the sheet (recording paper), thereby transferring the color image onto the sheet (recording paper). Is formed. The residual toner on the intermediate transfer member 50 after image transfer is cleaned by the intermediate transfer member cleaning device 17.

  The sheet (recording paper) on which the color image has been transferred is conveyed by the secondary transfer device 22 and sent to the fixing device 25, where the combined color image (color) is generated by heat and pressure. (Transfer image) is fixed on the sheet (recording paper). Thereafter, the sheet (recording paper) is switched by the switching claw 55 and discharged by the discharge roller 56 and stacked on the discharge tray 57, or switched by the switching claw 55 and reversed by the sheet reversing device 28 and transferred again. After being guided to the position and recording an image on the back surface, the image is discharged by the discharge roller 56 and stacked on the discharge tray 57.

  In the image forming apparatus and the image forming method of the present invention, the development including the carrier of the present invention having a coating layer having high mechanical strength, excellent toner chargeability, stability over time, good adhesion, and uniform thickness. Since the agent is used, high-quality images can be obtained efficiently.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to these Examples at all.

(Production Example 1)
-Production of Toner 1-
It is represented by 100 parts by mass of a polyester resin (weight average molecular weight = 12,000), 2 parts by mass of a copper phthalocyanine pigment, and the following structural formula (2) (nonylene perfluoroether, i-iodine salt of p-trimethylaminopropylamidophenyl). 2 parts by mass of the charge control agent was kneaded at 120 ° C. using a hot roll, cooled and solidified, then pulverized and classified to obtain a cyan toner having a volume average particle diameter of 7.1 μm.

  To 100 parts by mass of the obtained toner, 0.5 part by mass of silica R972 (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to prepare toner 1.

(Production Example 2)
-Production of Toner 2-
100 parts by mass of a polyester resin (weight average molecular weight = 12,000), 5 parts by mass of carbon black, and 2 parts by mass of a chromium-containing azo dye represented by the following structural formula (3) were kneaded at 120 ° C. using a hot roll. After cooling, solidifying, pulverizing and classifying, a black toner having a volume average particle size of 7.3 μm was obtained.

  To 100 parts by mass of the obtained toner, 0.5 part by mass of silica R972 (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to prepare toner 2.

(Production Example 3)
<Preparation of Toner 3>
-Synthesis of organic fine particle emulsion-
In a reaction vessel in which a stir bar and a thermometer are set, 683 parts by weight of water, 11 parts by weight of a sodium salt of ethylene oxide methacrylate adduct sulfate (Eleminol RS-30, manufactured by Sanyo Chemical Industries Ltd.), 83 parts by weight of styrene Then, 83 parts by weight of methacrylic acid, 110 parts by weight of butyl acrylate, and 1 part by weight of ammonium persulfate were charged and stirred for 15 minutes at 400 rpm, whereby a white emulsion was obtained. This emulsion was heated to raise the system temperature to 75 ° C. and reacted for 5 hours. Further, 30 parts by mass of a 1% ammonium persulfate aqueous solution was added, and the mixture was aged at 75 ° C. for 5 hours to obtain an aqueous vinyl resin (a copolymer of methacrylic acid-butyl acrylate-methacrylic acid ethylene oxide adduct sulfate sodium salt). A dispersion was obtained. This is designated as [fine particle dispersion 1].
The volume average particle size of the fine particles contained in the obtained [fine particle dispersion 1] was measured by a particle size distribution measuring apparatus (“LA-920”, manufactured by Horiba, Ltd.) using a laser scattering method, and found to be 105 nm. Met. In addition, a part of [Fine Particle Dispersion 1] was dried to isolate only the resin component. The glass transition temperature (Tg) of this resin was 59 ° C., and the weight average molecular weight (Mw) was 150,000.

-Preparation of aqueous phase-
990 parts by mass of water, 83 parts by mass of [fine particle dispersion 1], 37 parts by mass of a 48.5% aqueous solution of dodecyl diphenyl ether disulfonate (Eleminol MON-7, manufactured by Sanyo Chemical Industries), and 90 parts by mass of ethyl acetate The mixture was stirred to obtain a milky white liquid. This liquid is designated [Aqueous Phase 1].

-Synthesis of low molecular weight polyester-
In a reaction vessel equipped with a condenser, a stirrer and a nitrogen introduction tube, 229 parts by mass of bisphenol A ethylene oxide 2-mole adduct, 529 parts by mass of bisphenol A propylene oxide 3-mole adduct, 208 parts by mass of terephthalic acid, 46 parts by mass of adipic acid Part and 2 parts by mass of dibutyltin oxide were reacted at 230 ° C. for 8 hours under normal pressure. Next, after reacting under reduced pressure of 10 to 15 mmHg for 5 hours, 44 parts by mass of trimellitic anhydride was put in a reaction vessel and reacted at 180 ° C. and normal pressure for 2 hours to obtain [Low molecular weight polyester 1].
The obtained [low molecular weight polyester 1] had a glass transition temperature (Tg) of 45 ° C., a weight average molecular weight (Mw) of 5,800, a number average molecular weight of 2,600, and an acid value of 24.

-Synthesis of polyester prepolymer-
In a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 682 parts by mass of bisphenol A ethylene oxide 2 mol adduct, 81 parts by mass of bisphenol A propylene oxide 2 mol adduct, 283 parts by mass of terephthalic acid, trimellitic anhydride 22 parts by mass of acid and 2 parts by mass of dibutyltin oxide were added and reacted at 230 ° C. for 8 hours under normal pressure. Further, the reaction was carried out under reduced pressure of 10 to 15 mmHg for 5 hours to obtain [Intermediate polyester 1].
The obtained [Intermediate polyester 1] had a number average molecular weight of 2,100, a weight average molecular weight of 9,500, a glass transition temperature (Tg) of 55 ° C., an acid value of 0.5, and a hydroxyl value of 51.
Next, 410 parts by mass of [Intermediate Polyester 1], 89 parts by mass of isophorone diisocyanate and 500 parts by mass of ethyl acetate are placed in a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, and are heated at 100 ° C. for 5 hours. Reaction was performed to obtain [Prepolymer 1].
The obtained [Prepolymer 1] had a free isocyanate mass% of 1.74%.

-Synthesis of ketimine-
In a reaction vessel equipped with a stirrer and a thermometer, 170 parts by mass of isophoronediamine and 75 parts by mass of methyl ethyl ketone were charged and reacted at 50 ° C. for 5 hours to obtain [ketimine compound 1].
The amine value of the obtained [ketimine compound 1] was 418.

-Preparation of masterbatch (MB)-
1200 parts by mass of water, 540 parts by mass of carbon black (PBk-7: Printex 60, manufactured by Degussa) [DBP oil absorption = 114 ml / 100 mg, pH = 10], 1200 parts by mass of polyester resin (manufactured by Sanyo Chemical Industries, Ltd., RS801) And mixed with a Henschel mixer (Mitsui Mining Co., Ltd.). The obtained mixture was kneaded at 150 ° C. for 30 minutes using two rolls, rolled and cooled, and pulverized with a pulverizer to obtain a master batch. This is designated as [Masterbatch 1].

-Preparation of oil phase-
In a reaction vessel equipped with a stir bar and a thermometer, 300 parts by weight of [low molecular weight polyester 1], 90 parts by weight of carnauba wax, 10 parts by weight of rice wax, and 1000 parts by weight of ethyl acetate were charged and stirred at 79 ° C. And then rapidly cooled to 4 ° C. Using a bead mill (Ultra Visco Mill, manufactured by Imex Co., Ltd.), the liquid feeding speed is 1 kg / hr, the disk peripheral speed is 6 m / sec, and 0.5 mm zirconia beads are filled by 80% by volume, and dispersion is performed under conditions of 3 passes. And a wax dispersion having a volume average particle size of 0.6 μm was obtained.
Next, 500 parts by mass of [Masterbatch 1] and 640 parts by mass of a 70% ethyl acetate solution of [Low molecular weight polyester 1] were added and mixed for 10 hours. % [Oil phase 1] adjusted to% was produced.

-Preparation of polymerized toner-
[Oil Phase 1] 73.2 parts by mass, [Prepolymer 1] 6.8 parts by mass, [Ketimine Compound 1] 0.48 parts by mass in a well-mixed [Emulsified oil phase 1] with [Water Phase 1] 120 parts by mass were added, mixed for 1 minute with a homomixer, and then allowed to converge with a paddle for 1 hour with gentle stirring to obtain [Emulsion slurry 1].
The obtained [Emulsion slurry 1] was desolvated at 30 ° C. for 1 hour, further aged at 60 ° C. for 5 hours, washed with water, filtered and dried, and then sieved with a mesh of 75 μm, and the volume average particle diameter A toner having 6.1 μm and a number average particle size of 5.4 μm was obtained. Toner 3 was prepared by mixing 0.7 parts by mass of hydrophobic silica and 0.3 parts by mass of hydrophobic titanium oxide with 100 parts by mass of this toner using a Henschel mixer.

-Production of carrier 1-
Using the apparatus shown in FIG. 7, in a coating agent dissolution tank (internal volume 200 mL), a silicone resin represented by the following structural formula (4) (made by Toray Dow Corning Co., Ltd., SR-213 solvent-removed product, 200 parts by weight of the weight average molecular weight (Mw) = 4,000) and 10 parts by weight of the catalyst [(CH ₃ ) ₂ Sn (OCOCH ₃ ) ₂ ] were charged. After supplying carbon (purity = 99.5%, manufactured by Gastec Service Co., Ltd.) to 25 MPa and 80 ° C., the valve 3 was closed. In the carrier treatment tank (inner volume 400 ml), 500 parts by mass of ferrite core material (saturated magnetic moment at 1 k gauss = 65 emu / g) having a volume average particle diameter of 50 μm, alumina (Sumitomo Chemical Industries Sumiko Random AA-03 0. 3 μm Axial ratio 1.1) 5 parts by mass were charged, and the valve 6 was opened while stirring, and carbon dioxide (purity = 99.5%, manufactured by Ota Oxygen Co., Ltd.) was supplied with the pressure pump 1 at 25 MPa, 80 ° C. After that, the valve 6 was closed.

Next, the valve 3, the valve 5 and the valve 7 are opened, the pressurizing pump 1 and the decompressing pump 1 are operated, and the processing liquid is kept for 1 hour while controlling the internal pressure so that the inside of the carrier processing tank is maintained at 25 MPa and 80 ° C. Was allowed to flow (under normal pressure, flow rate = 1 L / min) to saturate the coating agent in the carrier treatment tank. The valve 3 was closed and the pressure was returned to normal pressure with the vacuum pump 1 over 2 hours. The coating agent that was not used was recovered from both the coating agent dissolution tank and the raw material recovery tank and could be reused.
The obtained ferrite core material coated with the silicone resin was heated at 200 ° C. for 1 hour to obtain a carrier 1.

-Production of carrier 2-
Using the apparatus shown in FIG. 8, a silicone resin represented by the structural formula (4) above (made by Toray Dow Corning Co., Ltd., SR-213 solvent-free product, weight) in a coating agent dissolution tank (internal volume 100 mL) 200 parts by mass of average molecular weight (Mw) = 4,000) and 10 parts by mass of catalyst [(CH ₃ ) ₂ Sn (OCOCH ₃ ) ₂ ] were charged.
In the carrier treatment tank (internal volume 125 ml), 500 parts by mass of ferrite core material (saturation magnetic moment at 1 k gauss = 65 emu / g) having a volume average particle size of 50 μm, alumina (Sumitomo Chemical Industries Sumiko Random AA-03 0. 3 μm Axial ratio 1.1) 5 parts by mass are charged, while the inside of the coating agent dissolution tank is stirred, the valve 3 is opened, and carbon dioxide (purity = 99.5%, manufactured by Gastec Service Co., Ltd.) is supplied with the pressure pump 1. After supplying the pressure to 25 MPa and 60 ° C., the valve 3 was closed. Next, the valve 3, the valve 5, and the valve 7 are opened, the pressure pump 1 and the pressure reduction pump 1 are operated, and the treatment liquid is treated for 1 hour while controlling the internal pressure so that the inside of the carrier treatment tank is maintained at 25 MPa and 60 ° C. Was allowed to flow (under normal pressure, flow rate = 1 L / min) to saturate the coating agent in the carrier treatment tank. The valve 3 was closed and the pressure was returned to normal pressure with the vacuum pump 1 over 2 hours. The coating agent that was not used was recovered from both the coating agent dissolution tank and the raw material recovery tank and could be reused.
The obtained ferrite core material coated with the silicone resin was heated at 200 ° C. for 1 hour to obtain a carrier 2.

-Production of carrier 3-
Using the apparatus shown in FIG. 9, in the coating agent dissolution tank (internal volume 500 mL), a silicone resin represented by the above structural formula (4) (manufactured by Toray Dow Corning Co., Ltd., SR-213 solvent-removed product, 100 parts by weight of the weight average molecular weight (Mw) = 4,000) and 5 parts by weight of the catalyst [(CH ₃ ) ₂ Sn (OCOCH ₃ ) ₂ ] were charged, the valve 3 was opened, and carbon dioxide (purity) was obtained with the pressure pump 1 = 99.5%, manufactured by Gastec Service Co., Ltd.) and stirred at 35 MPa and 40 ° C. to prepare a carrier coat solution.
Next, 500 parts by mass of ferrite core material (saturation magnetic moment at 1 k gauss = 65 emu / g) having a volume average particle diameter of 50 μm, fluidized bed type carrier treatment tank (internal volume 1000 ml), alumina (Sumitomo Chemical Co., Ltd. Sumiko Random) AA-03 0.3 μm Axial ratio 1.1) Charge 5 parts by mass, open valve 6, set the tank to 3 MPa and 100 ° C., close valve 6, then open valve 5 and valve 7 to reduce pressure The pump 1 was operated, the internal pressure was controlled so that the inside of the carrier treatment tank did not become 7 MPa or more, and the carrier coat liquid was applied over 40 minutes while stirring. The coating agent that was not used was recovered from both the coating agent dissolution tank and the raw material recovery tank and could be reused.
The obtained ferrite core material coated with the silicone resin was heated at 200 ° C. for 1 hour to obtain a carrier 3.

-Production of carrier 4-
Using the apparatus shown in FIG. 10, in the coating agent dissolution tank (internal volume 500 mL), a silicone resin represented by the above structural formula (4) (manufactured by Toray Dow Corning Co., Ltd., a solvent removal product of SR-213, 50 parts by mass of weight average molecular weight (Mw) = 4,000) and 2.5 parts by mass of catalyst [(CH ₃ ) ₂ Sn (OCOCH ₃ ) ₂ ] were charged, and a ferrite core material was placed in a carrier treatment tank (internal volume 1000 ml). (Saturated magnetic moment at 1 k gauss = 65 emu / g) 500 parts by mass, 5 parts by mass of alumina (Sumitomo Chemical AA-03 0.3 μm axial ratio 1.1 manufactured by Sumitomo Chemical Co., Ltd.) are charged, and valves 3 and 5 are opened. Then, carbon dioxide (purity = 99.5%, manufactured by Gastec Service Co., Ltd.) is supplied with the pressurizing pump 1, and a ferrite dispersion is prepared at 15 MPa and 80 ° C. with stirring. .
The obtained ferrite dispersion was sprayed (rapid expansion) from a nozzle of a spray tank in an atmosphere of 30 ° C. under normal pressure. The coating agent that was not used was recovered from both the coating agent dissolution tank and the raw material recovery tank and could be reused.
The obtained ferrite core material coated with the silicone resin was heated at 200 ° C. for 1 hour to obtain a carrier 4.

[ Reference Example 5]
-Production of carrier 5-
In Example 1, the carrier coating agent was changed to an epoxy-modified silicone resin (SR2115, manufactured by Toray Dow Corning Co., Ltd.), except that the pressure during the treatment was changed to 30 MPa and the temperature was changed to 100 ° C. Thus, carrier 5 was produced.

-Production of carrier 6-
In Example 1, the carrier coating agent was changed to a silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., KR271), the processing pressure was changed to 35 MPa, and the temperature was changed to 100 ° C. 6 was produced.

-Production of carrier 7-
A carrier 7 was produced in the same manner as in Example 1 except that 2.5 parts by mass of the aminosilane coupling agent [NH ₂ (CH ₂ ) ₃ Si (OCH ₃ ) ₃ ] was added.

-Production of carrier 8-
In Example 4, silicone resin (217 Flake Resin, manufactured by Toray Dow Corning Co., Ltd.) was used as the carrier coating agent, and ethanol was used as the entrainer by 0.5% by mass (about 5 g / L per internal volume) with the pressure pump 2. The carrier 8 was prepared in the same manner as in Example 4 except that a ferrite dispersion was prepared at 30 MPa and 80 ° C. and sprayed in an atmosphere of 50 ° C.

-Production of carrier 9-
In Example 8, the carrier 9 was changed in the same manner as in Example 8 except that 5% by mass of methanol was added as an entrainer instead of a silicone resin (220 Flakes Resin, manufactured by Toray Dow Corning) as the carrier coating agent. Produced.

-Production of carrier 10-
In Example 8, a carrier 10 was prepared in the same manner as in Example 8 except that 1% by mass of propanol was added as an entrainer instead of silicone resin (249 Flakes Resin, manufactured by Toray Dow Corning Co., Ltd.) as the carrier coating agent. Was made.

-Production of carrier 11-
In Example 2, a carrier 11 was produced in the same manner as in Example 2 except that a ferrite core material having a volume average particle size of 35 μm was used.

-Production of carrier 12-
In Example 1, the carrier coating agent was changed to silicone resin (249 Flake Resin, manufactured by Toray Dow Corning Co., Ltd.), the pressure in the carrier treatment tank was changed to 30 MPa, and the pressure reduction speed was constantly increased with the pressure reduction pump 1 over 10 minutes. A carrier 12 was produced in the same manner as in Example 1 except that the pressure was returned.

-Production of carrier 13-
In Example 12, the carrier 13 was produced in the same manner as in Example 12 except that the decompression speed was returned to normal pressure with the decompression pump 1 over 1 hour.

-Production of carrier 14-
A carrier 14 was produced in the same manner as in Example 12 except that the fine particles were changed to alumina (Sumitomo Chemical AA-04 0.4 μm axial ratio 1.1 manufactured by Sumitomo Chemical Co., Ltd.) in Example 12.

-Production of carrier 15-
A carrier 15 was produced in the same manner as in Example 12, except that the fine particles were changed to silica (Admafine SO-C3 1.0 μm axial ratio 1.1 manufactured by Admatechs) in Example 12.

-Production of carrier 16-
A carrier 16 was produced in the same manner as in Example 12 except that the fine particles were changed to titanium oxide (TTO-D-1 1.0 μm axial ratio 2.9 manufactured by Ishihara Sangyo Co., Ltd.) in Example 12.

[Comparative Example 1]
-Production of comparative carrier 1-
1000 g of a toluene solution (solid concentration 10% by mass) of a silicone resin (weight average molecular weight = 4,000) represented by the following structural formula (5), 5 g of a catalyst [(CH ₃ ) ₂ Sn (OCOCH ₃ ) ₂ ], A dispersion of 45% by mass of alumina (Sumitomo Random AA-04 0.4 μm axial ratio 1.1) manufactured by Sumitomo Chemical Co., Ltd. with respect to the solid content of the resin, a ferrite core material having a volume average particle size of 35 μm (at 1 k Gauss) (Saturation magnetic moment = 63 emu / g) 5 kg is applied using a fluidized bed type coating apparatus in an atmosphere of 100 ° C. at a rate of about 50 g / min for 20 minutes, and the resulting silicone resin is applied. The ferrite particles thus prepared were heated at 200 ° C. for 1 hour to produce a comparative carrier 1.

[Comparative Example 2]
-Production of comparative carrier 2-
In Comparative Example 1, a comparative carrier 2 was produced in the same manner as in Comparative Example 1, except that the volume average particle diameter of the ferrite core material was changed to 50 μm.

[Examples 17 to 24 and Examples 26 to 38, Reference Example 25, and Comparative Examples 3 to 6]
The produced carriers 1 to 16 and comparative carriers 1 and 2 and toners 1 to 3 are combined as shown in Table 1 below, and Examples 17 to 24, Examples 26 to 38, and Reference Example 25 are combined in a conventional manner. , as well as to prepare the developers of Comparative examples 3-6.

<Image density>
Next, each developer obtained was attached to a copy paper (TYPE6000 <70W>, manufactured by Ricoh Co., Ltd.) using a tandem color electrophotographic apparatus (image Neo 450, manufactured by Ricoh Co., Ltd.). A solid image having an amount of 1.00 ± 0.05 mg / cm ² was formed. The solid image was repeatedly formed on 1 million copy sheets.
The image density of the obtained solid image was observed visually at the initial stage and after endurance of 1 million sheets, and evaluated based on the following criteria. Note that the higher the image density obtained, the higher the density image can be formed. This evaluation corresponds to an embodiment of the process cartridge, the image forming apparatus, and the image forming method of the present invention.
〔Evaluation criteria〕
A: There was no change in image density and high image quality was obtained at the initial stage and after endurance of 1 million sheets
◯: After 1 million sheets were used, the image density was slightly reduced, but high image quality was obtained.
(Triangle | delta): After 1 million sheet endurance, the image density fell and the image quality fell.
X: After enduring 1 million sheets, the image density was remarkably lowered and the image quality was greatly lowered.

<Toner scattering>
The degree of toner contamination in the machine when 1 million sheets of a chart with an image area ratio of 5% were continuously output was visually evaluated in four stages according to the following criteria.
〔Evaluation criteria〕
A: There is no toner contamination in the machine and it is in an excellent state.
◯: There is no toner contamination in the machine and it is in a good state.
Δ: There is toner contamination in the machine, but it is a practically usable level.
X: Toner contamination in the machine is severe and the level is not practical.

<Soil dirt>
The degree of background contamination of the image background when a million sheets of an image area ratio of 5% were continuously output was visually evaluated according to the following criteria.
〔Evaluation criteria〕
○: No background stains in the image background.
Δ: Soil is slightly generated in the background portion of the image.
X: Soil is generated in the background portion of the image.

<Comprehensive evaluation>
From the above evaluation results, the following criteria were used for overall evaluation. The results are shown in Table 1.
〔Evaluation criteria〕
◎: Very good ○: Good ×: Bad

From the results of Table 1, the developers of Examples 17 to 24 and Examples 26 to 38 and Reference Example 25 using the carriers 1 to 16 processed with the supercritical fluid were compared with the developers of Comparative Examples 3 to 6. As a result, it was confirmed that there was no toner scattering and scumming and a high image density was obtained.

It is the schematic which shows an example of the apparatus used in the manufacturing method of the carrier of this invention. It is a schematic explanatory drawing which shows an example of the process cartridge of this invention. It is a schematic explanatory drawing which shows an example which enforces the image forming method of this invention with the image forming apparatus of this invention. It is a schematic explanatory drawing which shows the other example which implements the image forming method of this invention with the image forming apparatus of this invention. FIG. 2 is a schematic explanatory diagram illustrating an example in which the image forming method of the present invention is carried out by the image forming apparatus (tandem color image forming apparatus) of the present invention. FIG. 6 is a partially enlarged schematic explanatory diagram of the image forming apparatus shown in FIG. 5. 1 is a schematic view of an apparatus used for a carrier manufacturing method of Example 1. FIG. FIG. 6 is a schematic view of an apparatus used in the carrier manufacturing method of Example 2. FIG. 6 is a schematic view of an apparatus used in the carrier manufacturing method of Example 3. FIG. 6 is a schematic view of an apparatus used in the carrier manufacturing method of Example 4.

Explanation of symbols

10 Photoconductor (Photoconductor drum)
10K black photoconductor 10Y yellow photoconductor 10M magenta photoconductor 10C cyan photoconductor 14 support roller 15 support roller 16 support roller 17 intermediate transfer cleaning device 18 image forming means 20 charging roller 21 exposure device 22 secondary transfer device 23 Roller 24 Secondary transfer belt 25 Fixing device 26 Fixing belt 27 Pressure belt 28 Sheet reversing device 30 Exposure device 32 Contact glass 33 First traveling member 34 Second traveling member 35 Imaging lens 36 Reading sensor 40 Developing device 41 Developing belt 42K Developer container 42Y Developer container 42M Developer container 42C Developer container 43K Developer supply roller 43Y Developer supply roller 43M Developer supply roller 43C Developer supply roller 44K Developer roller 44Y Developer roller 44M Developer Roller 44C Developing roller 45K Black developing unit 45Y Yellow developing unit 45M Magenta developing unit 45C Cyan developing unit 49 Registration roller 50 Intermediate transfer member 51 Roller 52 Separating roller 53 Manual feed path 54 Manual feed tray 55 Switching claw 56 Discharge roller 57 discharge tray 58 corona charger 60 cleaning device 61 developing device 62 transfer charger 63 photoconductor cleaning device 64 static eliminator 70 static elimination lamp 80 transfer roller 90 cleaning device 95 transfer paper 10 image forming device 10 photoconductor 102 charging means 103 exposure 104 Developing means 105 Transfer body 106 Transfer means 107 Cleaning means 120 Tandem developer 121 Heating roller 122 Fixing roller 123 Fixing belt 124 Pressure roller 125 Heating source 126 Cleaning Roller 127 Temperature sensor 130 platen 142 paper feed roller 143 paper bank 144 sheet cassette 145 separating roller 146 feed path 147 transport rollers 148 feed path 150 copier main body 200 feeder table 300 Scanner 400 automatic document feeder (ADF)

Claims (12)

Dissolving or dispersing at least a silicone resin represented by the following structural formula (1) in a fluid containing a supercritical fluid or subcritical fluid that is at least carbon dioxide ;
Forming a coating layer composed of the silicone resin and fine particles made of a metal oxide of 0.3 μm to 1.0 μm on the surface of the ferrite core material;
A method for producing a carrier for developing an electrostatic latent image, comprising:
In the structural formula (1), R represents a hydrogen atom, a hydroxyl group, an alkoxy group, an alkyl group, or an aryl group. A step of dissolving or dispersing at least a silicone resin represented by the following structural formula (1) in a fluid containing at least carbon dioxide supercritical fluid or subcritical fluid to produce a solution or dispersion;
Spraying the solution or dispersion on a ferrite core material to form a coating layer comprising fine particles of the silicone resin and 0.3 to 1.0 μm metal oxide on the surface of the ferrite core material;
A method for producing a carrier for developing an electrostatic latent image, comprising:
In the structural formula (1), R represents a hydrogen atom, a hydroxyl group, an alkoxy group, an alkyl group, or an aryl group. A step of dissolving or dispersing at least a ferrite core material and a silicone resin represented by the following structural formula (1) in a fluid containing at least carbon dioxide supercritical fluid or subcritical fluid to generate a solution or dispersion. When,
The pressure of the solution or dispersion is released to rapidly expand the solution, and a coating layer composed of the silicone resin and fine particles composed of a metal oxide of 0.3 μm to 1.0 μm is formed on the surface of the ferrite core material. Forming, and
A method for producing a carrier for developing an electrostatic latent image, comprising:
In the structural formula (1), R represents a hydrogen atom, a hydroxyl group, an alkoxy group, an alkyl group, or an aryl group. A step of dissolving or dispersing at least a ferrite core material and a silicone resin represented by the following structural formula (1) in a fluid containing at least carbon dioxide supercritical fluid or subcritical fluid to generate a solution or dispersion. When,
Controlling the pressure or temperature of the solution or dispersion to lower the solubility, and covering the ferrite core material surface with a coating layer comprising the silicone resin and fine particles comprising a metal oxide of 0.3 μm to 1.0 μm Forming, and
A method for producing a carrier for developing an electrostatic latent image, comprising:
In the structural formula (1), R represents a hydrogen atom, a hydroxyl group, an alkoxy group, an alkyl group, or an aryl group. 5. The method for producing a carrier for developing an electrostatic latent image according to claim 1, wherein the fine particles comprising the metal oxide are made of a material having a composition different from that of the coating layer. 6. The electrostatic latent image developing carrier according to claim 1, wherein an entrainer (azeotropic agent) is contained in the fluid containing at least the supercritical fluid or subcritical fluid which is carbon dioxide. Manufacturing method. The entrainer content in the mixed fluid of at least one of the supercritical fluid or subcritical fluid that is carbon dioxide and the entrainer is in a range of 0.1 mass% to 10 mass%. Item 7. A method for producing an electrostatic latent image developing carrier according to Item 6. The electrostatic latent image according to claim 6 or 7, wherein the entrainer is a poor solvent for the ferrite core material, the fine particles comprising the metal oxide, and the silicone resin under normal temperature and normal pressure. A method for producing a developing carrier. 9. The method for producing a carrier for developing an electrostatic latent image according to claim 6, wherein the entrainer is at least one selected from the group consisting of methanol, ethanol, and propanol. 10. The method for producing a carrier for developing an electrostatic latent image according to claim 1, wherein the silicone resin is solid at normal temperature and pressure. The method for producing a carrier for developing an electrostatic latent image according to any one of claims 1 to 10, wherein the silicone resin has a weight average molecular weight (Mw) in the range of 500 to 100,000. The method for producing a carrier for developing an electrostatic latent image according to any one of claims 1 to 11, wherein the ferrite core material has a volume average particle diameter in a range of 20 µm to 50 µm.