JP2008046416A - Toner for electrostatic charge image development, method for manufacturing toner for electrostatic charge image development, developer for electrostatic charge image development, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development which substantially avoids a change in the color reproducibility of a full-color image, particularly the color reproducibility of a halftone image even after long-term use. <P>SOLUTION: The toner for electrostatic charge image development comprises toner base particles containing a binder resin and a colorant and an additive, wherein each toner base particle contains hydrophobic silica having a volume average particle diameter of 80-300 nm and a shape factor SF1 of 100-120 in a layer 0.04-1 μm away from the surface of the toner base particle, and the additive has a volume average particle diameter of 80-300 nm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic charge image developing toner (hereinafter sometimes simply referred to as “toner”), a method for producing an electrostatic charge image developing toner, an electrostatic charge image developing developer (hereinafter simply referred to as “developer”). And an image forming apparatus.

  As the toner surface additive, various additives are used for the purpose of imparting fluidity to the toner, imparting chargeability, improving transferability and cleaning properties, and the like. Among them, sol-gel silica obtained by hydrolysis and condensation reaction of tetraalkoxysilane has a nearly spherical shape, relatively large particle size and uniform particle size distribution compared to general fumed silica. It is known that it is dispersed as primary particles on the surface to improve the toner fluidity and reduce the adhesion force with the photosensitive member and the intermediate transfer member, thereby greatly contributing to the improvement of the transfer efficiency. In addition, its strong structure is more resistant to stress caused by stirring in the developing machine than resin particles, and it is difficult to be deformed or embedded in the toner surface, so it has excellent chargeability, fluidity, and transferability. (For example, refer to Patent Documents 1 to 3).

  Another feature of the sol-gel silica is that it has a higher water content than general fumed silica. While the moisture content of general fumed silica is about 0.1 to 0.5% by weight, the sol-gel silica retains a moisture content of about 0.5 to 20% by weight even after being hydrophobized. To do. This is because sol-gel silica has many silanol groups on its surface and internal pores, so it can adsorb a lot of water molecules by van der Waals force, etc., especially in a low temperature and low humidity environment. In order to retain the moisture of the toner, although the negative charge imparting ability is low with respect to the toner, there is little environmental difference in the charge amount, the toner charge distribution is kept narrow, and overcharging is prevented especially in a low temperature and low humidity environment. There is an effect of preventing electrostatic aggregation between each other.

As a toner using such a sol-gel method silica, for example, in Patent Document 2, a sol-gel method silica having an average primary particle diameter of 80 to 300 nm, a water content of 3 to 15% by weight, and a volume resistivity of 1 × 10 ¹³ Ωcm or more is used. A method of externally adding to the above has been proposed.

  Patent Document 4 discloses a toner containing inorganic particles such as silica having a center particle diameter of 5 to 100 nm and hydrophobized silica, and Patent Document 5 discloses inorganic particles such as colloidal silica having a center particle diameter of 5 to 20 nm. A toner containing inorganic particles such as colloidal silica having a central particle size of 30 to 100 nm has been proposed.

  The sol-gel silica, which has a relatively large particle size and high strength, is less likely to be embedded in the toner surface due to agitation and rubbing stress of the developing machine compared to other fumed silica, and has good transferability and chargeability maintenance. However, structural degradation due to separation or embedding from the toner surface and bias to the concave portions due to long-term use is unavoidable. Although the initial charge amount of the toner to which the sol-gel silica is added shows a relatively fixed value regardless of the charge amount of the toner base particles, the toner base gradually changes as the structure of the external additive attached to the toner surface changes. There is a tendency to approach the chargeability of the particles. In particular, in the case of a full-color developing toner that uses a plurality of color toners superimposed on each other, the charge of the mother particle toner differs due to the influence of pigments, etc. Color image color reproducibility may change due to changes in density reproducibility.

JP 2001-0666820 A JP 2002-108001 A JP-A-2005-003726 JP 2001-228647 A JP 2002-082473 A

  In this way, the adherence structure of the external additive attached to the toner surface hardly changes even when the developer is stirred for a long period of time, or by rubbing stress, and the charge amount deviation of each color toner is suppressed. As a result, a toner for developing an electrostatic image in which the color reproducibility of a full-color image, in particular, a color reproducibility of a halftone image hardly changes, a method for producing such a toner for developing an electrostatic image, an electrostatic charge There is a need for a developer for image development and an image forming apparatus.

  The present invention relates to a toner for developing an electrostatic image in which the color reproducibility of a full-color image, particularly a color reproducibility of a halftone image hardly changes even after long-term use, a method for producing the electrostatic image developing toner, An electrostatic charge image developing developer containing a charge image developing toner and an image forming apparatus using the electrostatic charge image developing developer.

  The present invention includes toner base particles containing a binder resin and a colorant and an additive, and the toner base particles have a volume average particle size in the range of 80 to 300 nm and a shape factor SF1 of 100 to 120. A toner for developing electrostatic images in which a hydrophobic silica in the range of 0.04 to 1 μm from the surface of the toner base particles is contained and the volume average particle size of the additive is in the range of 80 to 300 nm. is there.

  In the electrostatic image developing toner, the hydrophobic silica is a silane having at least one organic functional group selected from a vinyl group, an epoxy group, a styryl group, a methacryloxy group, an acryloxy group, and a ureido group. It is preferable that the surface is treated with a compound.

  In the electrostatic image developing toner, the hydrophobic silica is a silane having at least one organic functional group selected from a vinyl group, an epoxy group, a styryl group, a methacryloxy group, an acryloxy group, and a ureido group. The surface treatment is preferably performed with the compound and a silane compound having at least one organic functional group selected from a methyl group, a dimethyl group, and a trimethyl group.

  The present invention also relates to a method for producing the toner for developing an electrostatic image, wherein a resin particle dispersion in which resin particles are dispersed and a colorant dispersion in which a colorant is dispersed are mixed, and the resin particles and the colorant are mixed. A silica comprising an agglomeration step for agglomerating particles to form aggregated particles, additional resin particles, and hydrophobic silica having a volume average particle size in the range of 80 to 300 nm and a shape factor SF1 in the range of 100 to 120 An adhesion step of adding the dispersion and adding the additional resin particles and the hydrophobic silica to the surface of the agglomerated particles to form the adhered particles; and a fusion step of fusing the adhered particles by heating.

  The present invention also relates to a method for producing the toner for developing an electrostatic charge image, comprising: dissolving and dispersing a binder resin and a colorant in an organic solvent; and a volume average of the dissolved and dispersed solution. A particle forming step of suspending in an aqueous solvent in which hydrophobic silica having a particle size in the range of 80 to 300 nm and a shape factor SF1 in the range of 100 to 120 is dispersed to form toner particles. .

  The present invention also provides an electrostatic charge image developing developer comprising the electrostatic charge image developing toner.

  Furthermore, the present invention is an image forming apparatus using the developer for developing an electrostatic image.

  According to the first to third aspects of the present invention, the color reproducibility of the full-color image, particularly the color reproducibility of the halftone image hardly changes even when used for a long time as compared with the case where the present configuration is not provided. An electrostatic charge image developing toner can be provided.

  According to the fourth to fifth aspects of the present invention, compared with the case where the present configuration is not provided, the color reproducibility of the full color image, particularly the color reproducibility of the halftone image is hardly changed even when used for a long time. An electrostatic charge image developing toner can be produced.

  According to claim 6 of the present invention, compared to the case without this configuration, the electrostatic charge that hardly changes in color reproducibility of a full-color image, in particular, color reproducibility of a halftone image, even when used for a long period of time. A developer for image development can be provided.

  According to the seventh aspect of the present invention, compared to the case where the present configuration is not provided, the image formation in which the color reproducibility of the full color image, particularly the color reproducibility of the halftone image hardly occurs even when used for a long time. An apparatus can be provided.

  Embodiments of the present invention will be described below.

<Toner for electrostatic image development>
The toner according to the exemplary embodiment includes toner base particles containing a binder resin and a colorant and an additive. The toner base particles have a volume average particle size in the range of 80 to 300 nm and a shape factor SF1. Hydrophobic silica in the range of 100 to 120 is contained in the layer of 0.04 to 1 μm from the surface of the toner base particles, and the volume average particle diameter of the additive is in the range of 80 to 300 nm.

  The volume average particle diameter of the hydrophobic silica contained in the toner according to the exemplary embodiment is in the range of 80 to 300 nm, and preferably in the range of 100 to 200 nm. When the volume average particle diameter of the hydrophobic silica is smaller than 80 nm, the exposure amount on the surface of the toner base particles is lowered, and thus the effect of controlling the charging of the toner cannot be obtained. Further, since the specific surface area of the silica particles increases, it is difficult to bind and hold the toner particles in the toner base particles, which is not preferable. Conversely, when the volume average particle size is larger than 300 nm, the amount of exposure to the surface of the toner base particles is improved, but it becomes difficult to uniformly disperse and maintain near the surface during toner preparation, and silica particles due to stirring stress of the developing machine, etc. Is easy to occur and the maintainability of the effect is inferior.

  The volume average particle size of the hydrophobic silica can be measured using a laser diffraction / scattering particle size distribution analyzer (LA920, manufactured by Horiba, Ltd.).

  Further, the shape factor SF1 of the hydrophobic silica contained in the toner according to the exemplary embodiment is in the range of 100 to 120, and preferably in the range of 100 to 115. When the shape factor SF1 of the hydrophobic silica exceeds 120, toner fluidity and transferability may be deteriorated.

Here, the shape factor SF1 of the hydrophobic silica is represented by the following formula.
SF1 = (ML ² / A) × (π / 4) × 100
[In the above formula, ML represents the maximum length (μm) of hydrophobic silica, and A represents the projected area (μm ² ) of hydrophobic silica. ]

The shape factor SF1 was measured as follows using a Luzex image analyzer (manufactured by Nireco Corporation, FT). First, an optical microscope image of the toner spread on the slide glass is taken into a Luzex image analyzer through a video camera, and the maximum length (ML) and projected area (A) of 50 hydrophobic silicas are measured. For silica, (ML ² / A) × (π / 4) × 100 is calculated, and a value obtained by averaging the values is determined as the shape factor SF1.

  In the toner according to the exemplary embodiment, the toner base particles contain hydrophobic silica bound in a layer of at least 0.04 to 1 μm, preferably 0.04 to 0.5 μm from the surface of the toner base particles. When the toner base particles contain hydrophobic silica in the vicinity of the surface thereof, when used as a toner for a full color toner, the difference in the charge amount of the multi-color toner used is small even if the type of pigment contained is different. .

  Here, in the present specification, the toner base particles “contain and contain” hydrophobic silica in a layer of at least 0.04 to 1 μm from the toner base particle surface means that the hydrophobic silica is on the toner base particle surface. In the toner 1 as shown in FIG. 1, the hydrophobic silica 2 is embedded in the layer of 0.04 to 1 μm from the surface of the toner base particles 3 (distance D = 1 μm in FIG. 1). The state that has been done. That is, the binding state of the hydrophobic silica to the surface of the toner base particles is different from the state of being easily detached from the surface of the toner base particles. If the hydrophobic silica 2 is present beyond a distance of 1 μm from the surface 4 of the toner base particles 3, the hydrophobic silica is almost completely buried in the toner base particles, making it difficult to control the toner charge. When the distance is less than 0.04 μm, it is almost the same as the state of adhering to the surface of the toner base particles, and the hydrophobic silica is detached from the toner base particles during long-term use. The state in which a part of the hydrophobic silica is embedded in the surface of the toner base particles and the distance from the surface of the toner base particles are determined by embedding the toner with an epoxy resin or the like by a scanning electron microscope (SEM) and cutting the toner. This can be confirmed by observing the cross section. Note that not all of the hydrophobic silica particles are necessarily embedded in the surface of the toner base particles, and some of the hydrophobic silica is in a state of adhering to the surface of the toner base particles. May be. For example, in SEM observation, 70% or more of hydrophobic silica in the hydrophobic silica present on the surface of five toners may be embedded in a layer of 0.04 to 1 μm from the surface of the toner base particles. preferable.

  As the hydrophobic silica having a volume average particle diameter in the range of 80 to 300 nm and a shape factor SF1 in the range of 100 to 120, wet process silica obtained by a wet process is preferably used.

  As a wet process silica, a general aqueous silica sol obtained by a method in which an acid is added to sodium silicate to produce a silicate sol or a method in which sodium silicate is ion-exchanged to produce a silicate sol, an aqueous silica sol medium Sol-gel silica obtained by hydrolyzing and condensing tetraalkoxysilane etc. in an organic solvent in which water is present is used. Preferably used. Specific examples of the tetraalkoxysilane used in the sol-gel silica include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, and the like. From the viewpoint of particle size distribution and the like, tetramethoxysilane and tetraethoxysilane are preferable.

  These wet process silicas need to be hydrophobized before use. Aqueous silica sol and sol-gel silica have high hydrophilicity, and if included in toner base particles as they are, the environmental stability of toner charging deteriorates, and fogging, in-machine stains, transfer defects, etc. due to low charging in a high temperature and high humidity environment. This problem is likely to occur, and problems such as a decrease in image density and transfer failure due to high charging in a low temperature and low humidity environment are likely to occur.

  As the hydrophobizing agent for the wet process silica, a silane compound having a methyl group, a dimethyl group or a trimethyl group, particularly a silane compound having a trimethyl group is preferably used for the purpose of imparting hydrophobicity to the hydrophilic silica. Specific examples include methyltrimethoxysilane, dimethyldimethoxysilane, dimethyldichlorosilane, and hexamethyldisilazane.

  Silane compounds with long-chain alkyl groups such as dimethylsilicone oil, which is used for the hydrophobization treatment of general fumed silica, and isobutyltrialkoxysilane, decyltrialkoxysilane, react with silanol groups present on the surface of silica particles. Although it is possible, it is difficult to react with the silanol groups in the internal pores, so that it is difficult to give sufficient hydrophobicity.

  In this embodiment, for the purpose of increasing the adhesion between the hydrophobic silica and the binder resin in the toner base particles, the hydrophobic silica is composed of a vinyl group, an epoxy group, a styryl group, a methacryloxy group, an acryloxy group, and a ureido group. It is preferable that the surface is hydrophobized with a silane compound having at least one organic functional group selected from among the above. As the organic functional group of the silane compound, it is preferable to use an organic functional group having high adhesion depending on the kind of the binder resin used for the toner base particles. For example, when the binder resin is a styrene-acrylic copolymer resin or a polyester resin, a silane compound having a vinyl group, a styryl group, a methacryloxy group, or an acryloxy group is preferably used. Further, when the binder resin is an epoxy resin, a silane compound having an epoxy group is preferably used, and when the binder resin is a urethane resin, a silane compound having a ureido group is preferably used.

  Specific examples of these silane compounds having an organic functional group are, for example, vinyltrichlorosilane, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and p-styryltrimethoxysilane. , 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, and the like.

  In this embodiment, in order to increase the hydrophobicity of the hydrophobic silica and further improve the adhesion to the binder resin in the toner base particles, the hydrophobic silica is selected from among methyl, dimethyl and trimethyl groups. Silane compound having at least one organic functional group selected and silane compound having at least one organic functional group selected from vinyl group, epoxy group, styryl group, methacryloxy group, acryloxy group and ureido group It is more preferable that both of these are hydrophobized. Silane compounds having at least one organic functional group selected from methyl group, dimethyl group and trimethyl group mainly contribute to hydrophobization, and include vinyl group, epoxy group, styryl group, methacryloxy group, acryloxy group and ureido The silane compound having at least one organic functional group selected from the group mainly contributes to adhesion with the binder resin. Further, in order to increase the hydrophobicity of the hydrophobic silica and further improve the adhesion to the binder resin in the toner base particles, the hydrophobic silica is at least selected from methyl group, dimethyl group and trimethyl group. A silane having at least one organic functional group selected from a vinyl group, an epoxy group, a styryl group, a methacryloxy group, an acryloxy group, and a ureido group after being surface-treated with a silane compound having one organic functional group It is particularly preferred that it has been hydrophobized with a compound.

  The method for hydrophobizing hydrophobic silica is not particularly limited, but a method in which the wet-process silica is dispersed in water or an organic solvent such as an alcohol solvent and the silane compound is added and heated to react is preferable.

  In this embodiment, the amount of hydrophobic silica added is adjusted according to the target toner charge amount, but is generally 0.5 to 10% by weight, preferably 1 to 7% by weight, based on the toner base particles. Used in a range. When the amount of hydrophobic silica added is less than 0.5% by weight, the exposure amount on the surface of the toner base particles may be lowered. When the amount added exceeds 10% by weight, particles that cannot be dispersed and held near the toner surface increase. There is a case.

The additive having a volume average particle diameter in the range of 80 to 300 nm contained in the toner is not particularly limited, and known external additives such as inorganic particles and organic particles can be used. Among them, silica, titania, and the like can be used. Organic such as alumina, cerium oxide, strontium titanate, calcium carbonate, magnesium carbonate and calcium phosphate, metal soap such as zinc stearate, fluorine-containing resin particles, silica-containing resin particles and nitrogen-containing resin particles Resin particles are preferred. Moreover, you may surface-treat on the surface of an external additive according to the objective. Examples of the surface treatment agent include a silane compound, a silane coupling agent, and a silicone oil for performing a hydrophobic treatment. Among these, the same sol-gel silica as described above is preferable from the viewpoint of transferability and chargeability. The additive is preferably externally added (externally added) to the toner base particles, and is present in a state of adhering to the surface of the toner base particles. The sol-gel silica used as an additive is preferably hydrophobized in the same manner as described above. The sol-gel silica used as an additive has a volume average particle size of 80 to 300 nm, preferably 90 to 200 nm, a moisture content of preferably 3 to 15% by weight, more preferably 5 to 10% by weight, and a volume resistivity. Is preferably 1 × 10 ¹³ Ωcm to 1 × 10 ¹⁷ Ωcm, more preferably 1 × 10 ¹⁵ Ωcm to 5 × 10 ¹⁶ Ωcm.

  If the volume average particle diameter of the sol-gel silica is less than 80 nm, the sol-gel silica particles are likely to be embedded in the surface of the toner base particles when the developer is repeatedly used. The physical adhesive force may increase and sufficient transferability may not be obtained. Further, if the volume average particle diameter of the sol-gel silica exceeds 300 nm, it is not preferable because it is easily detached from the toner base particles and may cause contamination of the photosensitive member, the developing member and the transfer member.

  If the water content of the hydrophobic silica is less than 3% by weight, the image density may be reduced due to excessive charging in a low temperature and low humidity environment. If the water content exceeds 15% by weight, the charge is low in a high temperature and high humidity environment. Fog and internal dirt may occur.

When the volume resistivity of the hydrophobic silica is less than 1 × 10 ¹³ Ωcm, the toner charge distribution on the transfer member may be deteriorated due to the transfer electric field, which may cause transfer failure. When the volume resistivity exceeds 1 × 10 ¹⁷ Ωcm, excessive charge occurs. As a result, the image density may decrease.

  In the present exemplary embodiment, the toner base particles may be a known toner mainly composed of a binder resin and a colorant, and may further contain a release agent or the like.

  Binder resins include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, methyl acrylate, ethyl acrylate, Esters of α-methylene aliphatic monocarboxylic acids such as butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl methyl ether, vinyl ethyl Examples include vinyl ethers such as ether and vinyl butyl ether; homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone. As fats, polystyrene, styrene / alkyl acrylate copolymer, styrene / alkyl methacrylate copolymer, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, styrene / maleic anhydride copolymer, polyethylene, polypropylene Etc. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin waxes and the like.

  Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brillianthamine 3B, and brillianthamine. 6B, DuPont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, etc. Or acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thio Various dyes such as Ndico, Dioxazine, Thiazine, Azomethine, Indico, Thioindico, Phthalocyanine, Aniline Black, Polymethine, Triphenylmethane, Diphenylmethane, Thiazine, Thiazole, and Xanthene Or in combination of two or more.

  In the electrostatic image developing toner according to the exemplary embodiment, the content of the colorant is preferably in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the binder resin. It is also effective to use a colorant that has been surface-treated accordingly, or to use a pigment dispersant. By appropriately selecting the type of the colorant, yellow toner, magenta toner, cyan toner, black toner and the like can be obtained.

  Examples of mold release agents include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; Plant waxes such as ester wax, carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, etc .; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, fisher Mineral waxes such as Tropsch wax, petroleum waxes, and modified products thereof can be used. The addition amount of the release agent can be added in the range of 50% by weight or less with respect to the toner.

  As other internal additives, magnetic materials such as metals such as ferrite, magnetite, reduced iron, cobalt, nickel and manganese, alloys thereof, and compounds containing these metals can be used. As the charge control agent, various commonly used charge control agents such as quaternary ammonium salts, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments can be used. In order to control the ionic strength that affects the stability at the time of aggregation and fusion integration and to reduce wastewater contamination, a charge control agent that is difficult to dissolve in water is preferable.

  Examples of inorganic particles to be wet-added include silica, alumina, titania, calcium carbonate, magnesium carbonate, and tricalcium phosphate, all of which are usually used as external additives on the toner surface, such as ionic surfactants and It can be dispersed in a polymer acid or a polymer base and added wet.

<Method for producing toner for developing electrostatic image>
As a method for producing the toner base particles of the present embodiment, the polymerizable monomer of the binder resin is emulsion-polymerized, and the formed resin dispersion and colorant, and if necessary, dispersion of other components such as wax An oil-based composition obtained by dissolving and dispersing an emulsion polymerization aggregation method to obtain toner base particles by mixing with a liquid, heat-fusing, a binder resin, a colorant, and, if necessary, other components such as wax in an organic solvent. A solution suspension method in which the components are suspended and dispersed in an aqueous medium and then the organic solvent is removed is preferably used.

  The production method by the emulsion polymerization aggregation method includes a resin particle dispersion in which resin particles are dispersed and a colorant dispersion in which a colorant is dispersed, and agglomeration step in which the resin particles and the colorant are aggregated to generate aggregated particles; A silica-containing dispersion liquid containing additional resin particles and hydrophobic silica having a volume average particle size in the range of 80 to 300 nm and a shape factor SF1 in the range of 100 to 120 is added, and the additional resin is added to the surface of the aggregated particles. An attachment step of attaching the particles and hydrophobic silica to produce attached particles, and a fusion step of fusing the attached particles by heating.

  That is, in the emulsion polymerization aggregation method, at least a resin particle dispersion in which resin particles having a volume average particle diameter of 1 μm or less are dispersed, a colorant dispersion, and a wax dispersion or an inorganic particle dispersion as necessary are mixed, and if necessary After adding a divalent or higher inorganic metal salt flocculant to produce agglomerated particles and preparing an agglomerated particle dispersion, the mixture is heated to a temperature above the glass transition point of the resin particles, fused and coalesced, washed, In this method, toner particles are obtained by drying. In this method, the resin particle dispersion is added to the aggregated particle dispersion to add resin particles to the surface of the aggregated particles before the aggregation particle fusion step. It is preferable to provide an adhesion step for adhering and forming a resin film on the toner particle surface. However, in this embodiment, the toner is added by adding hydrophobic silica together with the resin particle dispersion added in this adhesion step. In the vicinity of the surface of the base particles with the hydrophobic silica particles sintered wear it can be contained.

  As a method for dispersing the colorant, an arbitrary method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, a high-pressure disperser, an ultrasonic disperser, or the like can be adopted. It is not something.

  Waxes are dispersed in water with polymer electrolytes such as ionic surfactants, polymer acids, and polymer bases, and are granulated with a homogenizer or pressure discharge type disperser that can be heated above the melting point and impart strong shearing. A dispersion of particles of 1 μm or less can be produced.

  In the emulsion polymerization aggregation method of the present embodiment, the hydrophobic silica is bound in the 0.04 to 1 μm layer from the surface of the toner base particles by adjusting the ratio of the addition amount of the hydrophobic silica and the addition amount of the resin. It can be set as the structure contained by wearing. For example, the amount of hydrophobic silica is preferably 10 to 50% by weight and more preferably 20 to 40% by weight with respect to the amount of resin to be added. When the amount of the hydrophobic silica is less than 10% by weight, the amount of the hydrophobic silica in which the hydrophobic silica is almost completely embedded in the toner base particles is increased, which may make it difficult to control the charging of the toner. If the amount exceeds 50% by weight, the amount of hydrophobic silica that is simply attached to the surface of the toner base particles increases, so that the hydrophobic silica tends to be detached from the toner base particles during long-term use.

  In addition, the production method by the dissolution suspension method includes a dissolution / dispersion step in which a binder resin and a colorant are dissolved and dispersed in an organic solvent, and a dissolution / dispersion in which the volume average particle size is in the range of 80 to 300 nm. And a particle forming step of suspending in an aqueous solvent in which hydrophobic silica having a shape factor SF1 in the range of 100 to 120 is dispersed to form toner particles.

  That is, the dissolution suspension method is a solution (oil-based component) in which a binder resin, a colorant, and if necessary, other components such as wax and inorganic particles are dissolved and dispersed in an organic solvent that is dissolved in a trace amount in water. Is suspended in an aqueous medium with inorganic particles such as calcium carbonate and a surfactant to produce toner particles, and after removing the organic solvent, the inorganic particles and the surfactant are removed and dried in the washing step. In this embodiment, hydrophobic silica is dispersed in an aqueous medium in advance, and then a dissolved dispersion (oil component) is suspended in the vicinity of the surface of the toner base particles. The active silica particles can be bound and contained.

  The amount of hydrophobic silica to be dispersed in the aqueous medium in the above production method is such that the solid content (toner composition) of a dissolved dispersion (oil component) obtained by dissolving and dispersing a binder resin, a colorant, wax, and the like in an organic solvent. ), Preferably 0.5 to 10% by weight, more preferably 1 to 7% by weight.

  Surfactants used in emulsion production, seed polymerization, pigment dispersion, resin particles, release agent dispersion, aggregation, or stabilization thereof in the toner production process include sulfate ester, sulfonate, and phosphate ester types. , Anionic surfactants such as soaps, cationic surfactants such as amine salt type, quaternary ammonium salt type, etc., polyethylene glycol type, alkylphenol ethylene oxide adduct type, polyhydric alcohol type, etc. It is also effective to use a nonionic surfactant in combination.

<Physical properties of toner for developing electrostatic image>
The volume average particle size of the electrostatic image developing toner according to this embodiment is preferably in the range of 4 μm to 8 μm, more preferably in the range of 5 μm to 7 μm, and the number average particle size is in the range of 3 μm to 7 μm. Is preferable, and the range of 4 μm to 6 μm is more preferable.

  The volume average particle size and the number average particle size can be measured by measuring with a 100 μm aperture diameter using a Coulter Multisizer II type (manufactured by Beckman-Coulter). At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds.

  The volume average particle size distribution index GSDv of the electrostatic image developing toner according to this embodiment is 1.27 or less, preferably 1.25 or less. When GSDv exceeds 1.27, the particle size distribution is not sharp, resolution is deteriorated, and image defects such as toner scattering and fogging are caused.

The volume average particle diameter D50v and the volume average particle size distribution index GSDv can be obtained as follows. Draw cumulative distributions from the small diameter side for the particle size range (channel) divided based on the particle size distribution of the toner measured by the above-mentioned Coulter Multisizer II type (manufactured by Beckman-Coulter). In addition, the particle diameter that is accumulated 16% is defined as volume D16v and several D16p, the particle diameter that is accumulated 50% is defined as volume D50v and several D50p, and the particle diameter that is accumulated 84% is defined as volume D84v and several D84p. At this time, D50v represents the volume average particle diameter, and the volume average particle size distribution index (GSDv) is determined as (D84v / D16v) ^1/2 . In addition, (D84p / D16p) ^1/2 represents a number average particle size distribution index (GSDp).

In addition, the shape factor SF1 represented by the following formula of the toner for developing an electrostatic charge image according to this embodiment is preferably in the range of 110 to 140, more preferably in the range of 115 to 130.
SF1 = (ML ² / A) × (π / 4) × 100
[In the above formula, ML represents the maximum toner length (μm), and A represents the projected area (μm ² ) of the toner. ]
If the toner shape factor SF1 is less than 110 or exceeds 140, it may be impossible to obtain excellent chargeability, cleanability, and transferability over a long period of time.

In addition, shape factor SF1 was measured as follows using a Luzex image analyzer (manufactured by Nireco Corporation, FT). First, an optical microscopic image of toner spread on a slide glass is taken into a Luzex image analyzer through a video camera, and the maximum length (ML) and projection area (A) of 50 toners are measured. ML ² / A) × (π / 4) × 100 was calculated, and the average value was calculated as the shape factor SF1.

<Electrostatic image developer>
The toner for developing an electrostatic charge image according to the exemplary embodiment is used as it is as a one-component developer or as a two-component developer. When used as a two-component developer, it is used by mixing with a carrier.

  There is no restriction | limiting in particular as a carrier which can be used for a two-component developer, A well-known carrier can be used. Examples thereof include magnetic metals such as iron oxide, nickel and cobalt, magnetic oxides such as ferrite and magnetite, resin-coated carriers having a resin coating layer on the surface of the core material, and magnetic dispersion carriers. Further, a resin-dispersed carrier in which a conductive material or the like is dispersed in a matrix resin may be used.

  Coating resins and matrix resins used for carriers include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic. Examples thereof include, but are not limited to, acid copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenol resins, epoxy resins and the like.

  Examples of the conductive material include metals such as gold, silver and copper, carbon black, titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black. It is not limited.

  Examples of the core material of the carrier include magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to use the carrier for the magnetic brush method, it is a magnetic material. It is preferable. The volume average particle size of the core material of the carrier is generally in the range of 10 μm to 500 μm, and preferably in the range of 30 μm to 100 μm.

  In order to coat the surface of the core material of the carrier with a resin, there may be mentioned a method of coating with a coating layer forming solution in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited and may be appropriately selected in consideration of the coating resin to be used, coating suitability, and the like.

  Specific resin coating methods include an immersion method in which the carrier core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the surface of the carrier core material, and the carrier core material is fluidized air. And a kneader coater method in which the carrier core material and the coating layer forming solution are mixed in a kneader coater and the solvent is removed in a kneader coater.

  The mixing ratio (weight ratio) of the toner according to the exemplary embodiment and the carrier in the two-component developer is in the range of toner: carrier = 1: 100 to 30: 100, and 3: 100 to 20: 100. A range of the degree is more preferable.

<Image forming apparatus>
The image forming apparatus according to the present embodiment includes a charging unit that charges the surface of the electrostatic charge image carrier, and an exposure unit that exposes the charged electrostatic charge image carrier surface to form an electrostatic latent image (electrostatic charge image). And developing means for developing the electrostatic latent image formed on the surface of the electrostatic image carrier using the developer carried on the developer carrier to form a toner image, and forming on the surface of the electrostatic image carrier And a fixing unit for fixing the toner image transferred to the surface of the transfer medium, and the developer for developing the electrostatic image is included as a developer. Use developer. The image forming apparatus according to the present embodiment may include means other than the above-described means.

  An example of the image forming apparatus according to the present embodiment is schematically shown in FIG. The image forming apparatus 5 includes a charging unit 10, an exposure unit 12, an electrophotographic photosensitive member 14 that is an electrostatic charge image carrier, a developing unit 16, a transfer unit 18, a cleaning unit 20, and a fixing unit 22. Prepare.

  In the image forming apparatus 5, the charging unit 10 that is a charging unit that charges the surface of the electrophotographic photosensitive member 14 and the charged electrophotographic photosensitive member 14 are exposed around the electrophotographic photosensitive member 14 according to image information. Formed on the surface of the electrophotographic photoreceptor 14, an exposure unit 12 that is an exposure unit that forms an electrostatic charge image, a development unit 16 that is a development unit that develops the electrostatic charge image with toner and forms a toner image. A transfer unit 18 that is a transfer unit that transfers the toner image onto the surface of the transfer material 24 and a cleaning unit 20 that is a cleaning unit that removes toner remaining on the surface of the electrophotographic photosensitive member 14 after transfer are in this order. Has been placed. A fixing unit 22 that is a fixing unit (image fixing device) for fixing the toner image transferred to the transfer material 24 is disposed on the left side of the transfer unit 18.

  An operation of the image forming apparatus 5 according to the present embodiment will be described. First, the surface of the electrophotographic photosensitive member 14 is uniformly charged by the charging unit 10. Next, light is applied to the surface of the electrophotographic photosensitive member 14 by the exposure unit 12, and the charged charges in the irradiated portion are removed, and an electrostatic charge image is formed according to image information. Thereafter, the electrostatic image is developed by the developing unit 16, and a toner image is formed on the surface of the electrophotographic photoreceptor 14. For example, in the case of a digital electrophotographic copying machine using an organic photoconductor as the electrophotographic photoconductor 14 and using a laser beam as the exposure unit 12, the surface of the electrophotographic photoconductor 14 is negatively charged by the charging unit 10. Then, a digital latent image is formed in a dot shape by the laser beam light, and toner is applied to the portion irradiated with the laser beam light by the developing unit 16 to be visualized. In this case, a negative bias is applied to the developing unit 16. Next, in the transfer unit 18, a transfer material 24 such as paper is superimposed on the toner image, and a charge having a polarity opposite to that of the toner is applied to the transfer material 24 from the back side of the transfer material 24. Is transferred to the transfer material 24. The transferred toner image is subjected to heat and pressure by a fixing member in the fixing unit 22 and is fused and fixed to the transfer material 24. On the other hand, toner remaining on the surface of the electrophotographic photoreceptor 14 without being transferred is removed by the cleaning unit 20. One cycle is completed in a series of processes from charging to cleaning. In FIG. 2, the toner image is directly transferred to the transfer material 24 such as paper by the transfer unit 18, but may be transferred via a transfer body such as an intermediate transfer body.

  Hereinafter, a charging unit, an electrostatic charge image carrier, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a fixing unit in the image forming apparatus 5 of FIG. 2 will be described.

(Charging means)
For example, a charging device such as a corotron as shown in FIG. 2 is used as the charging unit 10 as a charging unit, but a conductive or semiconductive charging roll may be used. A contact charger using a conductive or semiconductive charging roll may apply a direct current to the electrophotographic photosensitive member 14 or may superimpose an alternating current. For example, the charging unit 10 charges the surface of the electrophotographic photosensitive member 14 by generating a discharge in a minute space near the contact portion with the electrophotographic photosensitive member 14. Normally, it is charged to -300 to -1000V. The conductive or semiconductive charging roll may have a single layer structure or a multiple structure. Further, a mechanism for cleaning the surface of the charging roll may be provided.

(Static charge image carrier)
The electrostatic charge image carrier has a function of forming at least a latent image (electrostatic charge image). A preferable example of the electrostatic image bearing member is an electrophotographic photosensitive member. The electrophotographic photoreceptor 14 has a coating film containing an organic photoreceptor or the like on the outer peripheral surface of a cylindrical conductive substrate. The coating film is a substrate in which a subbing layer and a photosensitive layer including a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material are formed in this order on the substrate as necessary. is there. The order of stacking the charge generation layer and the charge transport layer may be reversed. These are laminated photoconductors in which a charge generation material and a charge transport material are contained in separate layers (charge generation layer, charge transport layer), but both the charge generation material and the charge transport material are the same. A single-layer type photoreceptor included in the above layer may be used, and a laminated photoreceptor is preferable. Further, an intermediate layer may be provided between the undercoat layer and the photosensitive layer. In addition, other types of photosensitive layers such as an amorphous silicon photosensitive film may be used in addition to the organic photoreceptor.

(Exposure means)
There is no particular limitation on the exposure unit 12 that is an exposure unit, and for example, an optical system device that can expose a light source such as semiconductor laser light, LED light, or liquid crystal shutter light on the surface of the electrostatic charge image carrier in a desired image-like manner. Etc.

(Development means)
The developing unit 16 as developing means has a function of developing a latent image formed on the electrostatic charge image carrier with a developer containing toner to form a toner image. Such a developing device is not particularly limited as long as it has the above-mentioned function, and can be appropriately selected according to the purpose. For example, toner for developing an electrostatic image is used using a brush, a roller, or the like. A known developing device having a function of adhering to the electrophotographic photosensitive member 14 may be used. For the electrophotographic photosensitive member 14, a DC voltage is usually used, but an AC voltage may be superimposed and used.

(Transfer means)
As the transfer unit 18 serving as a transfer unit, for example, a charge opposite in polarity to the toner is applied to the transfer material 24 from the back side of the transfer material 24 as shown in FIG. 2, and the toner image is transferred to the transfer material 24 by electrostatic force. A transfer roll and a transfer roll pressing device using a conductive roll or a semiconductive roll that transfers directly to the surface of the transfer material 24 via the transfer material 24 can be used. . A direct current may be applied to the transfer roll as a transfer current applied to the electrostatic image carrier, or an alternating current may be applied in a superimposed manner. The transfer roll can be arbitrarily set depending on the width of the image area to be charged, the shape of the transfer charger, the opening width, the process speed (circumferential speed), and the like. Further, a single layer foam roll or the like is suitably used as a transfer roll for cost reduction. As a transfer method, a method of transferring directly to the transfer material 24 such as paper or a method of transferring to the transfer material 24 via an intermediate transfer member may be used.

  A known intermediate transfer member can be used as the intermediate transfer member. Materials used for the intermediate transfer member include polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene phthalate, PC / polyalkylene terephthalate (PAT) blend material, ethylene tetrafluoroethylene copolymer (ETFE) / PC, ETFE / PAT, PC / PAT blend materials, and the like can be mentioned. From the viewpoint of mechanical strength, an intermediate transfer belt using a thermosetting polyimide resin is preferable.

(Cleaning means)
The cleaning unit 20 as a cleaning means may be appropriately selected as long as it cleans the residual toner on the electrostatic image carrier, such as a blade cleaning method, a brush cleaning method, or a roll cleaning method. . Among these, it is preferable to use a cleaning blade. Examples of the material for the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber. Among them, it is particularly preferable to use a polyurethane elastic body because of its excellent wear resistance. However, there may be a mode in which the cleaning unit 20 is not used when toner having high transfer efficiency is used.

(Fixing means)
The fixing unit 22 serving as a fixing unit (image fixing device) fixes the toner image transferred to the transfer material 24 by heating, pressing, or heating and pressing, and includes a fixing member.

(Transfer material)
Examples of the transfer material (paper) 24 to which the toner image is transferred include plain paper, OHP sheets, and the like used in electrophotographic copying machines and printers. In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer material is as smooth as possible. For example, coated paper in which the surface of plain paper is coated with resin, art paper for printing, etc. Can be preferably used.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

(Silica Synthesis Example 1)
A stirrer, a dropping funnel, and a thermometer were set in a glass reactor. Aqueous ammonia was added to water and ethanol, and the mixture was stirred and kept at 30 ° C. Next, tetraethoxysilane was dropped into the solution over 2 hours to react. After completion of dropping, stirring was further continued at 30 ° C. for 3 hours to obtain a hydrophilic silica sol suspension having a volume average particle size of 120 nm. Hydrophobic silica sol suspension was prepared by adding 20 parts by weight of dimethyldichlorosilane to 100 parts by weight of silica particles in the hydrophilic silica sol suspension, followed by reaction at 90 ° C. for 5 hours to hydrophobize the silica. 1 (solid content 20 wt%) was obtained. The volume average particle diameter of the hydrophobic silica was 120 nm, and the shape factor SF1 was 110.

  The volume average particle size of the hydrophobic silica was measured after ultrasonically dispersing 0.1 g of the sample in 50 g of methanol using a laser diffraction / scattering particle size distribution analyzer (LA920 type, manufactured by Horiba, Ltd.).

The shape factor SF1 of hydrophobic silica was measured as follows using a Luzex image analyzer (manufactured by Nireco Corporation, FT). First, an optical microscope image of the toner spread on the slide glass is taken into a Luzex image analyzer through a video camera, and the maximum length (ML) and projected area (A) of 50 hydrophobic silicas are measured. For silica, (ML ² / A) × (π / 4) × 100 was calculated, and an average of these values was used as the shape factor SF1.

(Silica Synthesis Example 2)
A stirrer, a dropping funnel, and a thermometer were set in a glass reactor. Aqueous ammonia was added to water and ethanol, and the mixture was stirred and kept at 30 ° C. Next, tetraethoxysilane was dropped into the solution over 2 hours to react. After completion of dropping, stirring was further continued at 30 ° C. for 3 hours to obtain a hydrophilic silica sol suspension having a volume average particle size of 120 nm. After adding 10 parts by weight of 3-acryloxypropyltrimethoxysilane to 100 parts by weight of silica particles in the hydrophilic silica sol suspension, the mixture is reacted at 90 ° C. for 5 hours to form a hydrophobic silica sol suspension 2 (solid Min 20 wt%). The volume average particle diameter of the hydrophobic silica was 120 nm, and the shape factor SF1 was 112.

(Silica Synthesis Example 3)
A stirrer, a dropping funnel, and a thermometer were set in a glass reactor. Aqueous ammonia was added to water and ethanol, and the mixture was stirred and kept at 30 ° C. Next, tetraethoxysilane was dropped into the solution over 2 hours to react. After completion of dropping, stirring was further continued at 30 ° C. for 3 hours to obtain a hydrophilic silica sol suspension having a volume average particle size of 120 nm. Hydrophobic silica sol suspension was prepared by adding 20 parts by weight of dimethyldichlorosilane to 100 parts by weight of silica particles in the hydrophilic silica sol suspension, followed by reaction at 90 ° C. for 5 hours to hydrophobize the silica. Got. After adding 5 parts by weight of 3-acryloxypropyltrimethoxysilane to 100 parts by weight of silica particles in this hydrophobic silica sol suspension, the mixture is reacted at 90 ° C. for 3 hours to form hydrophobic silica sol suspension 3 (solid Min 20 wt%). The volume average particle diameter of the hydrophobic silica was 120 nm, and the shape factor SF1 was 111.

(Silica Synthesis Example 4)
A hydrophobic silica sol suspension 4 (solid content 20 wt%) having a volume average particle size of 120 nm was obtained in the same manner as in silica synthesis example 3 except that dimethyldichlorosilane was changed to hexamethyldisilazane in silica synthesis example 3. . The shape factor SF1 of the hydrophobic silica was 110.

(Silica Synthesis Example 5)
A hydrophobic silica sol suspension 5 (solid content 20 wt%) having a volume average particle size of 120 nm was obtained in the same manner as in silica synthesis example 3 except that dimethyldichlorosilane was changed to methyltrimethoxysilane in silica synthesis example 3. . The shape factor SF1 of the hydrophobic silica was 112.

(Silica Synthesis Example 6)
Hydrophobic silica sol suspension 6 having a volume average particle size of 120 nm in the same manner as in silica synthesis example 4 except that 3-acryloxypropyltrimethoxysilane was changed to 3-methacryloxypropyltrimethoxysilane in silica synthesis example 4. (Solid content 20 wt%) was obtained. The shape factor SF1 of hydrophobic silica was 111.

(Silica Synthesis Example 7)
Hydrophobic silica sol suspension 7 having a volume average particle size of 120 nm (solid) except that 3-acryloxypropyltrimethoxysilane was replaced with p-styryltrimethoxysilane in silica synthesis example 4 Min 20 wt%). The shape factor SF1 of the hydrophobic silica was 112.

(Silica Synthesis Example 8)
Hydrophobic silica sol suspension 8 having a volume average particle size of 120 nm (solid content) except that 3-acryloxypropyltrimethoxysilane was changed to vinyltrimethoxysilane in silica synthesis example 4 in the same manner as silica synthesis example 4. 20 wt%) was obtained. The shape factor SF1 of hydrophobic silica was 111.

(Silica Synthesis Example 9)
Hydrophobic silica sol suspension with a volume average particle size of 120 nm in the same manner as in silica synthesis example 4 except that 3-acryloxypropyltrimethoxysilane was changed to 3-glycidoxypropyltrimethoxysilane in silica synthesis example 4. A liquid 9 (solid content 20 wt%) was obtained. The shape factor SF1 of the hydrophobic silica was 112.

(Silica Synthesis Example 10)
Hydrophobic silica sol suspension 10 having a volume average particle size of 120 nm is the same as silica synthesis example 4 except that 3-acryloxypropyltrimethoxysilane is changed to 3-ureidopropyltriethoxysilane in silica synthesis example 4. (Solid content 20 wt%) was obtained. The shape factor SF1 of the hydrophobic silica was 112.

(Silica Synthesis Example 11)
A hydrophobic silica sol suspension 11 (solid content 20 wt%) was obtained in the same manner as in silica synthesis example 3 except that the reaction temperature at the time of silica synthesis was 35 ° C. The volume average particle diameter of the hydrophobic silica was 80 nm, and the shape factor SF1 was 109.

(Silica Synthesis Example 12)
A hydrophobic silica sol suspension 12 (solid content 20 wt%) was obtained in the same manner as in Silica Synthesis Example 3 except that the reaction temperature during the synthesis of silica was 28 ° C. The volume average particle size of the hydrophobic silica was 300 nm, and the shape factor SF1 was 114.

(Silica Synthesis Example 13)
A hydrophobic silica sol suspension 13 (solid content 20 wt%) was obtained in the same manner as in silica synthesis example 3 except that the stirring speed during silica synthesis was 1.2 times that of silica synthesis example 3. The volume average particle diameter of the hydrophobic silica was 120 nm, and the shape factor SF1 was 120.

(Silica Synthesis Example 14)
A stirrer, a dropping funnel, and a thermometer were set in a glass reactor. Aqueous ammonia was added to water and ethanol, and the mixture was stirred and kept at 40 ° C. Next, tetraethoxysilane was dropped into the solution over 2 hours to react. After completion of the dropwise addition, stirring was further continued at 40 ° C. for 3 hours to obtain a hydrophilic silica sol suspension having a volume average particle diameter of 70 nm. After adding 25 parts by weight of dimethyldichlorosilane to 100 parts by weight of the silica particles in the hydrophilic silica sol suspension, the silica is hydrophobized by reacting at 90 ° C. for 5 hours to form a hydrophobic silica sol suspension. Got. After adding 5 parts by weight of 3-acryloxypropyltrimethoxysilane to 100 parts by weight of silica particles in the hydrophobic silica sol suspension, the mixture is reacted at 90 ° C. for 3 hours to form a hydrophobic silica sol suspension 14 (solid Min 20 wt%). The volume average particle size of the hydrophobic silica was 70 nm, and the shape factor SF1 was 108.

(Silica Synthesis Example 15)
A stirrer, a dropping funnel, and a thermometer were set in a glass reactor. Aqueous ammonia was added to water and ethanol, and the mixture was stirred and kept at 27 ° C. Next, tetraethoxysilane was dropped into the solution over 2 hours to react. After completion of the dropwise addition, stirring was further continued at 27 ° C. for 3 hours to obtain a hydrophilic silica sol suspension having a volume average particle size of 350 nm. Hydrophobic silica sol suspension was prepared by adding 15 parts by weight of dimethyldichlorosilane to 100 parts by weight of silica particles in the hydrophilic silica sol suspension, followed by reaction at 90 ° C. for 5 hours to hydrophobize the silica. Got. After adding 3 parts by weight of 3-acryloxypropyltrimethoxysilane to 100 parts by weight of silica particles in the hydrophobic silica sol suspension, the mixture is reacted at 90 ° C. for 3 hours to form a hydrophobic silica sol suspension 15 (solid Min 20 wt%). The volume average particle diameter of the hydrophobic silica was 350 nm, and the shape factor SF1 was 115.

(Sol-gel method silica synthesis example 1)
A stirrer, a dropping funnel, and a thermometer were set in a glass reactor. Aqueous ammonia was added to water and ethanol, and the mixture was stirred and kept at 30 ° C. Next, tetraethoxysilane was dropped into the solution over 2 hours to react. After completion of the dropwise addition, stirring was further continued at 30 ° C. for 3 hours to obtain a hydrophilic silica sol suspension. This hydrophilic silica sol suspension was heated to 80 to 90 ° C., ethanol was removed, toluene was added, and the mixture was further heated to 90 to 100 ° C. to remove ethanol and water. Next, after adding 40 parts by weight of hexamethyldisilazane to 100 parts by weight of the silica particles in the suspension, the silica is hydrophobized by reacting at 100 ° C. for 4 hours to form a hydrophobic silica sol suspension. Got. Thereafter, this hydrophobic silica sol suspension is heated to 110 to 120 ° C. to remove toluene, dried at 150 ° C. for 10 hours in a shelf dryer, and coarse powder is removed with a sieve mesh having a mesh opening of 106 μm. Hydrophobic silica particles 1 were obtained. The hydrophobic silica particles 1 had a volume average particle size of 115 nm, a moisture content of 7.8% by weight, and a volume resistivity of 1 × 10 ¹⁶ Ωcm.

(Sol-gel method silica synthesis example 2)
A stirrer, a dropping funnel and a thermometer were set in a glass reactor. Aqueous ammonia was added to water and ethanol, and the mixture was stirred and kept at 35 ° C. Next, tetraethoxysilane was dropped into the solution over 2 hours to react. After completion of the dropping, stirring was further continued at 35 ° C. for 3 hours to obtain a hydrophilic silica sol suspension. This hydrophilic silica sol suspension was heated to 80 to 90 ° C., ethanol was removed, toluene was added, and the mixture was further heated to 90 to 100 ° C. to remove ethanol and water. Next, after adding 40 parts by weight of hexamethyldisilazane to 100 parts by weight of the silica particles in the suspension, the silica is hydrophobized by reacting at 100 ° C. for 4 hours to form a hydrophobic silica sol suspension. Got. Thereafter, this hydrophobic silica sol suspension is heated to 110 to 120 ° C. to remove toluene, dried at 150 ° C. for 10 hours in a shelf dryer, and coarse powder is removed with a sieve mesh having a mesh opening of 106 μm. Hydrophobic silica particles 2 were obtained. The hydrophobic silica particles 2 had a volume average particle size of 82 nm, a moisture content of 8.8% by weight, and a volume resistivity of 5 × 10 ¹⁵ Ωcm.

(Sol-gel method silica synthesis example 3)
A stirrer, a dropping funnel and a thermometer were set in a glass reactor. Aqueous ammonia was added to water and ethanol, and the mixture was stirred and kept at 28 ° C. Next, tetraethoxysilane was dropped into the solution over 2 hours to react. After completion of the dropping, stirring was further continued at 28 ° C. for 3 hours to obtain a hydrophilic silica sol suspension. This hydrophilic silica sol suspension was heated to 80 to 90 ° C., ethanol was removed, toluene was added, and the mixture was further heated to 90 to 100 ° C. to remove ethanol and water. Next, after adding 40 parts by weight of hexamethyldisilazane to 100 parts by weight of the silica particles in the suspension, the silica is hydrophobized by reacting at 100 ° C. for 4 hours to form a hydrophobic silica sol suspension. Got. Thereafter, this hydrophobic silica sol suspension is heated to 110 to 120 ° C. to remove toluene, dried at 150 ° C. for 10 hours in a shelf dryer, and coarse powder is removed with a sieve mesh having a mesh opening of 106 μm. Hydrophobic silica particles 3 were obtained. The hydrophobic silica particles 3 had a volume average particle size of 280 nm, a moisture content of 6.5% by weight, and a volume resistivity of 1 × 10 ¹⁶ Ωcm.

(Sol-gel method silica synthesis example 4)
A stirrer, a dropping funnel, and a thermometer were set in a glass reactor. Aqueous ammonia was added to water and ethanol, and the mixture was stirred and kept at 40 ° C. Next, tetraethoxysilane was dropped into the solution over 2 hours to react. After completion of the dropwise addition, stirring was further continued at 40 ° C. for 3 hours to obtain a hydrophilic silica sol suspension. This hydrophilic silica sol suspension was heated to 80 to 90 ° C., ethanol was removed, toluene was added, and the mixture was further heated to 90 to 100 ° C. to remove ethanol and water. Next, after adding 40 parts by weight of hexamethyldisilazane to 100 parts by weight of the silica particles in the suspension, the silica is hydrophobized by reacting at 100 ° C. for 4 hours to form a hydrophobic silica sol suspension. Got. Thereafter, this hydrophobic silica sol suspension is heated to 110 to 120 ° C. to remove toluene, dried at 150 ° C. for 10 hours in a shelf dryer, and coarse powder is removed with a sieve mesh having a mesh opening of 106 μm. Hydrophobic silica particles 4 were obtained. The hydrophobic silica particles 4 had a volume average particle size of 72 nm, a moisture content of 9.5% by weight, and a volume resistivity of 2 × 10 ¹⁵ Ωcm.

(Sol-gel method silica synthesis example 5)
A stirrer, a dropping funnel and a thermometer were set in a glass reactor. Aqueous ammonia was added to water and ethanol, and the mixture was stirred and kept at 26 ° C. Next, tetraethoxysilane was dropped into the solution over 2 hours to react. After completion of the dropping, stirring was further continued at 26 ° C. for 3 hours to obtain a hydrophilic silica sol suspension. This hydrophilic silica sol suspension was heated to 80 to 90 ° C., ethanol was removed, toluene was added, and the mixture was further heated to 90 to 100 ° C. to remove ethanol and water. Next, after adding 40 parts by weight of hexamethyldisilazane to 100 parts by weight of the silica particles in the suspension, the silica is hydrophobized by reacting at 100 ° C. for 4 hours to form a hydrophobic silica sol suspension. Got. Thereafter, this hydrophobic silica sol suspension is heated to 110 to 120 ° C. to remove toluene, dried at 150 ° C. for 10 hours in a shelf dryer, and coarse powder is removed with a sieve mesh having a mesh opening of 106 μm. Hydrophobic silica particles 5 were obtained. The hydrophobic silica particles 5 had a volume average particle size of 350 nm, a moisture content of 5.5% by weight, and a volume resistivity of 3 × 10 ¹⁶ Ωcm.

(Preparation of resin particle dispersion)
Styrene 296 parts by weight n-butyl acrylate 104 parts by weight Acrylic acid 6 parts by weight Dodecanethiol 10 parts by weight Divinyl adipate 1.6 parts by weight (manufactured by Wako Pure Chemical Industries, Ltd.)
A mixture obtained by mixing and dissolving the above components was mixed with 12 parts by weight of a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) and an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC). 8 parts by weight is added to a solution dissolved in 610 parts by weight of ion-exchanged water, dispersed in a flask, emulsified, and slowly mixed for 10 minutes to dissolve 8 parts of ammonium persulfate (Wako Pure Chemical Industries, Ltd.) 50 parts by weight of the ion-exchanged water was added, and nitrogen substitution was performed at 0.1 liter / min for 20 minutes. Then, while stirring in the flask, the contents are heated in an oil bath until the content reaches 70 ° C., and emulsion polymerization is continued for 5 hours. The resin particle dispersion has a volume average particle size of 200 nm and a solid content concentration of 40% by weight. A liquid was prepared. When a part of the dispersion was left on an oven at 100 ° C. to remove moisture, DSC (differential scanning calorimeter) measurement was performed. The glass transition point was 53 ° C. and the weight average molecular weight was 32,000. Met.

  The volume average particle diameter D50v of the resin particles in the resin particle dispersion was measured with a laser diffraction particle size distribution analyzer (LA-700 manufactured by Horiba, Ltd.).

  The molecular weight distribution of the binder resin was measured under the following conditions. GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)”, and the column uses two “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corporation)” THF (tetrahydrofuran) was used as an eluent. As experimental conditions, a THF concentration of a sample concentration of 0.5% by weight and a flow rate of 0.6 mL / min. The experiment was conducted using a sample injection amount of 10 μL, a measurement temperature of 40 ° C., and an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

  The glass transition point of the resin particles was measured using a differential scanning calorimeter (manufactured by Shimadzu Corporation, DSC-50) under a temperature rising rate of 10 ° C./min.

(Adjustment of colorant dispersion (Y))
C. I. Pigment Yellow 74 (monoazo pigment, manufactured by Dainichi Seika Co., Ltd .: Seika First Yellow 2054) 100 parts by weight Anionic surfactant (Neogen RK: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 10 parts by weight Deionized water 490 parts by weight Were mixed and dissolved, and dispersed for 10 minutes using a homogenizer (manufactured by IKA: Ultra Tarrax) to prepare a colorant dispersant (Y) having a volume average particle size of 130 nm.

(Adjustment of colorant dispersion (M))
The colorant is C.I. I. A colorant dispersion (M) was prepared in the same manner as the colorant dispersion (Y) except that it was changed to CI Pigment Red 122 (quinacridone pigment, manufactured by Dainichi Seika Co., Ltd .: Chromofine Magenta 6887).

(Preparation of colorant dispersion (C))
The colorant is C.I. I. A colorant dispersion (C) was prepared in the same manner as the colorant dispersion (Y) except that it was changed to CI Pigment Blue 15: 3 (phthalocyanine pigment, manufactured by Dainichi Seika Co., Ltd .: Cyanine Blue 4937).

(Adjustment of colorant dispersion (K))
A colorant dispersion (K) was prepared in the same manner as the colorant dispersion (Y) except that the colorant was changed to carbon black (Cabot Corp .: Regal 330).

(Preparation of release agent dispersion 1)
Paraffin wax (manufactured by Nippon Seiwa Co., Ltd .: HNP-9) 100 parts by weight Anionic surfactant (manufactured by Lion Co., Ltd .: Lipar 860K) 10 parts by weight Deionized water 390 parts by weight After mixing and dissolving the above components, Dispersing using a homogenizer (IKA: Ultra Tarrax), dispersing with a pressure discharge homogenizer, and dispersing a release agent (paraffin wax) having a volume average particle size of 220 nm. Liquid 1 was prepared.

(Carrier production)
To a kneader, 1,000 parts by weight of Mn—Mg ferrite (volume average particle size 35 μm, manufactured by Powdertech) was added, and a styrene-methyl methacrylate copolymer (polymerization ratio 40:60, Tg 90 ° C., weight average molecular weight 72,000). A solution obtained by dissolving 150 parts by weight of Token Chemical Co., Ltd. in 700 parts by weight of toluene was added, mixed at room temperature for 20 minutes, heated to 70 ° C. and dried under reduced pressure, and then taken out to obtain a coated carrier. Furthermore, the obtained coated carrier was sieved with a mesh having an opening of 105 μm, and coarse powder was removed to obtain a carrier.

<Example 1>
(Manufacture of yellow toner 1)
Resin particle dispersion 320 parts by weight Colorant dispersion (Y) 80 parts by weight Release agent dispersion 1 96 parts by weight Aluminum sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) 1.5 parts by weight Ion-exchanged water 1270 parts by weight The components were housed in a round stainless steel flask with a temperature control jacket and dispersed at 5,000 rpm for 5 minutes using a homogenizer (IKA, Ultra Tarrax T50), then moved to the flask, 25 ° C., The mixture was left stirring for 4 minutes with 4 paddles. Thereafter, the mixture was heated with a mantle heater while stirring and heated at a heating rate of 1 ° C./min until the inside became 48 ° C., and held at 48 ° C. for 20 minutes. When the volume average particle diameter of the aggregated particles becomes 4.5 μm, 115 parts by weight of the resin particle dispersion and 70 parts by weight of the hydrophobic silica sol suspension (8% by weight with respect to the total resin) are gradually added. After maintaining at 48 ° C. for 30 minutes, 1N aqueous sodium hydroxide solution was added to adjust the pH to 6.5.

  Thereafter, the temperature was raised to 95 ° C. at a rate of 1 ° C./min and held for 30 minutes. A 0.1N aqueous nitric acid solution was added to adjust the pH to 4.8, and the mixture was allowed to stand at 95 ° C. for 2 hours. Thereafter, the 1N aqueous sodium hydroxide solution was further added to adjust the pH to 6.5, and the mixture was allowed to stand at 95 ° C. for 5 hours. Thereafter, it was cooled to 30 ° C. at 5 ° C./min.

  The resulting toner particle dispersion was filtered, (A) 2,000 parts by weight of ion-exchanged water at 35 ° C. was added to the obtained toner particles, (B) allowed to stand for 20 minutes, and (C) then filtered. After the operations from (A) to (C) were repeated 5 times, the toner particles on the filter paper were transferred to a vacuum dryer and dried at 45 ° C. and 1,000 Pa or less for 10 hours. The reason why the pressure is 1,000 Pa or less is that the above-mentioned toner particles are in a water-containing state, and in the initial stage of drying, the water freezes even at 45 ° C., and then the water sublimates. This is because is not constant. However, it was stable at 100 Pa at the end of drying. After the inside of the dryer is returned to normal pressure, it is taken out to obtain toner mother particles 1, and 2.0 parts by weight of hydrophobic silica 1 is added to 100 parts by weight of the toner mother particles. Were mixed at 3,000 rpm for 3 minutes to obtain yellow toner 1. The obtained yellow toner 1 had a D50v of 5.2 μm, a glass transition temperature of 53 ° C., and a shape factor SF1 of 132.

  It was confirmed by observing the cross section of the toner with a scanning electron microscope (SEM) that a part of the hydrophobic silica particles was embedded in the 0.04 to 1 μm layer from the surface of the toner base particles. 75% of the hydrophobic silica present on the surface of the five toners was embedded in a 0.04 to 1 μm layer from the surface of the toner base particles.

(Manufacture of magenta toner 1)
A magenta toner 1 was produced in the same manner as the yellow toner 1 except that the colorant dispersion (Y) was changed to the colorant dispersion (M) that is a magenta colorant. The obtained magenta toner 1 had a D50v of 5.1 μm, a glass transition temperature of 53 ° C., and a shape factor SF1 of 134. In the same manner as in the yellow toner 1, it was confirmed that a part of the hydrophobic silica particles were embedded in the 0.04 to 1 μm layer from the surface of the toner base particles. Of the hydrophobic silica present on the surfaces of the five toners, 80% of the hydrophobic silica was embedded in the 0.04-1 μm layer from the surface of the toner base particles.

(Manufacture of cyan toner 1)
Cyan toner 1 was produced in the same manner as yellow toner 1 except that the colorant dispersion (Y) was changed to a colorant dispersion (C) that is a cyan colorant. The obtained cyan toner 1 had a D50v of 5.0 μm, a glass transition temperature of 53 ° C., and a shape factor SF1 of 132. In the same manner as in the yellow toner 1, it was confirmed that a part of the hydrophobic silica particles were embedded in the 0.04 to 1 μm layer from the surface of the toner base particles. Of the hydrophobic silica present on the surfaces of the five toners, 78% of the hydrophobic silica was embedded in a 0.04 to 1 μm layer from the surface of the toner base particles.

(Manufacture of black toner 1)
A black toner 1 was produced in the same manner as the yellow toner 1 except that the colorant dispersion (Y) was changed to the colorant dispersion (K) which is a black colorant. The obtained black toner 1 had a D50v of 5.2 μm, a glass transition temperature of 53 ° C., and a shape factor SF1 of 133. In the same manner as in the yellow toner 1, it was confirmed that a part of the hydrophobic silica particles were embedded in the 0.04 to 1 μm layer from the surface of the toner base particles. Of the hydrophobic silica present on the surfaces of the five toners, 72% of the hydrophobic silica was embedded in a 0.04 to 1 μm layer from the surface of the toner base particles.

  The volume average particle diameter of the hydrophobic silica used as the external additive was measured using a laser diffraction / scattering particle size distribution analyzer (LA920, manufactured by Horiba, Ltd.).

  Moreover, the moisture content of hydrophobic silica was measured as follows. After 2 g of a measurement sample was left to stand for 3 hours in a chamber or room at 20 ° C. and 45% RH and humidity-controlled, it was 3 in a room at 20 ° C. and 45% RH using a thermobalance (TGA-50 manufactured by Shimadzu Corporation) The heating loss was measured after heating from normal temperature to 120 ° C. at a temperature rising rate of ° C./min and holding at 120 ° C. for 30 minutes.

Moreover, the volume resistivity of hydrophobic silica was measured by the following method. That is, the measurement is a pair of 20 cm ² circular plates (made of steel) connected to an electrometer (trade name: “KEITHLEY610C”, manufactured by KEYTHLEY) and a high-voltage power supply (trade name: “FLUKE415B”, manufactured by FLUKE). Silica particles are put on the lower electrode plate of the jig so as to form a flat layer having a thickness of about 1 to 2 mm. Next, after the upper electrode plate is disposed on the silica particles, the thickness of the silica particle layer is measured in a state where a weight of 4 kg is placed on the upper electrode plate in order to remove voids in the silica particles, A voltage of 1000 V was applied to the bipolar plates, the current value was measured, and the calculation was made based on the following formula (1).
Volume resistivity ρ = V × S ÷ (A−A ₀ ) ÷ d (Ωcm) (1)
(In the formula (1), V is an applied voltage 1000 (V), S is an electrode plate area 20 (cm ² ), A is a measured current value (A), and A ₀ is an initial current value (A ), D represents the particle layer thickness (cm).)

(Manufacture of developer 1 (Y, M, C, K))
Developer 1 (Y, M, C, K) was obtained by mixing 93 parts by weight of carrier and 7 parts by weight of toner 1 (Y, M, C, K) with a V blender at 40 rpm for 20 minutes.

(Evaluation)
When the image density of Y, M, C, K, input density 100% is adjusted to 1.5 under high temperature and high humidity (28 ° C 85% RH) and low temperature and low humidity (10 ° C 15% RH) environment The densities of 50% and 20% halftone images were compared with the initial one after 500,000 sheets, and the amount of change was evaluated according to the following criteria. DocuCenterColor400CP (manufactured by Fuji Xerox Co., Ltd.) was used as the evaluation machine, C2 paper (manufactured by Fuji Xerox Co., Ltd.) was used as the paper, and developer 1 (Y, M, C, K) was used as the developer. The image density was measured using X-Rite 938 (manufactured by Nihon Hakusho Kaisha, Ltd.) Table 1 shows the results in a high temperature and high humidity environment, and Table 2 shows the results in a low temperature and low humidity environment.

[Each color density change amount (initial density-density after 500,000 sheets)]
(100% image)
○: Within 0.2 Δ: 0.2-0.3
×: 0.3 or more (50% image)
○: Within 0.1 Δ: 0.1-0.2
×: 0.2 or more (20% image)
○: Within 0.05 Δ: 0.05 to 0.1
X: 0.1 or more [4 color density difference]
(100% image)
○: Within 0.2 Δ: 0.2-0.3
×: 0.3 or more (50% image)
○: Within 0.1 Δ: 0.1-0.2
×: 0.2 or more (20% image)
○: Within 0.05 Δ: 0.05 to 0.1
X: 0.1 or more

<Examples 2 to 13>
Developers 2 to 13 (Y, M, C, and K) were obtained in the same manner as in Example 1 except that the hydrophobic silica sol suspensions 2 to 13 were used instead of the hydrophobic silica sol suspension 1 respectively. It was. Tables 1 and 2 show the results of evaluation performed in the same manner as in Example 1.

<Example 14>
Developers 14 (Y, M, C, K) were obtained in the same manner as in Example 1 except that the hydrophobic silica 2 was used instead of the hydrophobic silica 1 as an external additive. Tables 1 and 2 show the results of evaluation performed in the same manner as in Example 1.

<Example 15>
Developers 15 (Y, M, C, K) were obtained in the same manner as in Example 1 except that the hydrophobic silica 3 was used instead of the hydrophobic silica 1 as an external additive. Tables 1 and 2 show the results of evaluation performed in the same manner as in Example 1.

<Example 16>
(Manufacture of cyan toner 2)
C. I. Pigment Blue B15: 3 (phthalocyanine pigment, manufactured by Dainichi Seika Co., Ltd .: Cyanine Blue 4937) 20 parts by weight, ethyl acetate 75 parts by weight, solvent-removed Disparon DA-703-50 (polyester acid amide amine salt, Enomoto Chemical ( 4 parts by weight (manufactured by Co., Ltd.) and 1 part by weight of Solsperse 5000 (pigment derivative, manufactured by Zeneca Co., Ltd.) were dissolved and dispersed using a sand mill to prepare a pigment dispersion (C2). In addition, 30 parts by weight of paraffin wax (melting point: 89 ° C.) and 270 parts by weight of ethyl acetate as a mold release agent were wet pulverized in a state cooled to 10 ° C. using a DCP mill to prepare a mold release agent dispersion 2. Polyester resin comprising bisphenol A propylene oxide adduct, bisphenol A ethylene oxide adduct, terephthalic acid derivative (Mw = 6000, Tg 60 ° C., Tm 106 ° C., acid value 4 mg KOH / g) 136 parts by weight, pigment dispersion (C2) 34 wt. Part and 56 parts by weight of ethyl acetate were stirred, and then 275 parts by weight of the release agent dispersion 2 was added to the mixture, and the resulting mixture was stirred well until uniform (this liquid was designated as liquid A). On the other hand, 124 parts by weight of calcium carbonate dispersion obtained by dispersing 40 parts by weight of calcium carbonate in 60 parts by weight of ion-exchanged water, 99 parts by weight of a 2% by weight aqueous solution of Serogen BS-H (Daiichi Kogyo Seiyaku Co., Ltd.), ion exchange 157 parts by weight of water and 35 parts by weight of hydrophobic silica sol suspension 1 were stirred for 5 minutes using a homogenizer (Ultra Turrax, manufactured by IKA) (this liquid was designated as B liquid). Further, 370 parts by weight of the B liquid and 250 parts by weight of the A liquid were stirred using a homogenizer (Ultra Turrax, manufactured by IKA) to suspend the mixed liquid. The mixture was stirred with a propeller stirrer at room temperature and normal pressure for 48 hours to remove the solvent. Next, hydrochloric acid was added to the mixed solution to remove calcium carbonate, and then the reaction mixture was washed with water, dried and classified to obtain cyan toner 2. The volume average particle diameter of the toner was 6 μm.

(Manufacture of yellow toner 2)
The colorant is C.I. I. A yellow toner 2 was produced in the same manner as the cyan toner 2 except that it was changed to CI Pigment Yellow 74 (monoazo pigment, manufactured by Dainichi Seika Co., Ltd .: Seika First Yellow 2054).

(Manufacture of magenta toner 2)
The colorant is C.I. I. Magenta Toner 2 was prepared in the same manner as Cyan Toner 2 except that Pigment Red 122 (quinacridone pigment, manufactured by Dainichi Seika Co., Ltd .: Chromo Fine Magenta 6887) was used.

(Manufacture of black toner 2)
A black toner 2 was prepared in the same manner as the cyan toner 2 except that the colorant was changed to carbon black (manufactured by Cabot: Regal 330).

  In the same manner as in Example 1, developer 16 (Y, M, C, K) was obtained. Tables 1 and 2 show the results of evaluation performed in the same manner as in Example 1.

<Comparative Example 1>
Developers 17 (Y, M, C, K) were obtained in the same manner as in Example 1 except that the hydrophobic silica sol suspension 14 was used instead of the hydrophobic silica sol suspension 1. Tables 1 and 2 show the results of evaluation performed in the same manner as in Example 1. Further, as confirmed in the same manner as the yellow toner 1, 90% or more of the hydrophobic silica in the hydrophobic silica existing in the vicinity of the surfaces of the five toners is completely embedded in the toner base particles and exposed to the surface. It was not in a state.

<Comparative example 2>
Developers 18 (Y, M, C, K) were obtained in the same manner as in Example 1 except that the hydrophobic silica sol suspension 15 was used instead of the hydrophobic silica sol suspension 1. Tables 1 and 2 show the results of evaluation performed in the same manner as in Example 1. Further, as confirmed in the same manner as the yellow toner 1, most of the hydrophobic silica present in the vicinity of the surfaces of the five toners was not attached and held inside the toner but simply adhered to the toner surface. .

<Comparative Example 3>
Developers 19 (Y, M, C, K) were obtained in the same manner as in Example 16 except that the hydrophobic silica sol suspension 14 was used instead of the hydrophobic silica sol suspension 1. Tables 1 and 2 show the results of evaluation performed in the same manner as in Example 1. Further, as confirmed in the same manner as the yellow toner 1, 90% of the hydrophobic silica present in the vicinity of the surfaces of the five toners is completely embedded in the toner base particles and exposed on the surface. There was no state.

<Comparative Example 4>
Developer 20 (Y, M, C, K) was obtained in the same manner as in Example 16 except that the hydrophobic silica sol suspension 15 was used instead of the hydrophobic silica sol suspension 1. Tables 1 and 2 show the results of evaluation performed in the same manner as in Example 1. Further, as confirmed in the same manner as the yellow toner 1, most of the hydrophobic silica present in the vicinity of the surfaces of the five toners was not attached and held inside the toner but simply adhered to the toner surface. .

<Comparative Example 5>
Developer 21 (Y, M, C, K) was obtained in the same manner as in Example 3 except that hydrophobic silica 4 was used instead of hydrophobic silica 1 as an external additive. Tables 1 and 2 show the results of evaluation performed in the same manner as in Example 1.

<Comparative Example 6>
Developers 22 (Y, M, C, K) were obtained in the same manner as in Example 3 except that the hydrophobic silica 5 was used instead of the hydrophobic silica 1 as an external additive. Tables 1 and 2 show the results of evaluation performed in the same manner as in Example 1.

  As described above, when the developers of Examples 1 to 16 were used, the color reproducibility of the full-color image, particularly the color reproducibility of the halftone image, hardly occurred even after long-term use. On the other hand, when the developers of Comparative Examples 1 to 6 were used, the color reproducibility of the full-color image, particularly the color reproducibility of the halftone image, was changed by long-term use.

FIG. 3 is a schematic cross-sectional view illustrating an example of a surface state of a toner according to an exemplary embodiment of the present invention. 1 is a schematic diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Toner, 2 Hydrophobic silica, 3 Toner mother particle, 5 Image forming apparatus, 10 Charging part, 12 Exposure part, 14 Electrophotographic photoreceptor, 16 Developing part, 18 Transfer part, 20 Cleaning part, 22 Fixing part, 24 Cover Transfer material.

Claims (7)

Including toner base particles and an additive containing a binder resin and a colorant;
The toner base particles have a volume average particle size in the range of 80 to 300 nm and a hydrophobic silica having a shape factor SF1 in the range of 100 to 120 in the layer of 0.04 to 1 μm from the surface of the toner base particles. Contained in
The toner for developing an electrostatic charge image, wherein the additive has a volume average particle diameter in a range of 80 to 300 nm. The electrostatic image developing toner according to claim 1,
The hydrophobic silica is surface-treated with a silane compound having at least one organic functional group selected from vinyl group, epoxy group, styryl group, methacryloxy group, acryloxy group and ureido group. Toner for developing electrostatic image. The electrostatic image developing toner according to claim 1,
The hydrophobic silica is a silane compound having at least one organic functional group selected from a vinyl group, an epoxy group, a styryl group, a methacryloxy group, an acryloxy group, and a ureido group, a methyl group, a dimethyl group, and a trimethyl group. A toner for developing an electrostatic image, wherein the toner is surface-treated with a silane compound having at least one organic functional group selected from the group consisting of: A method for producing the electrostatic image developing toner according to claim 1,
A resin particle dispersion in which resin particles are dispersed and a colorant dispersion in which a colorant is dispersed, and agglomeration step for aggregating the resin particles and the colorant to produce aggregated particles;
A silica-containing dispersion containing additional resin particles and hydrophobic silica having a volume average particle size in the range of 80 to 300 nm and a shape factor SF1 in the range of 100 to 120 is added, and the surface of the aggregated particles is An attachment step of attaching additional resin particles and the hydrophobic silica to produce attached particles;
A fusion step of fusing the attached particles by heating;
A method for producing a toner for developing an electrostatic charge image, comprising: A method for producing the electrostatic image developing toner according to claim 1,
A dissolution and dispersion step of dissolving and dispersing the binder resin and the colorant in an organic solvent;
The dissolved and dispersed solution is suspended in an aqueous solvent in which hydrophobic silica having a volume average particle size in the range of 80 to 300 nm and a shape factor SF1 in the range of 100 to 120 is dispersed. A particle forming step for forming toner particles;
A method for producing a toner for developing an electrostatic charge image, comprising:   An electrostatic charge image developing developer comprising the electrostatic charge image developing toner according to claim 1.   An image forming apparatus using the developer for developing an electrostatic charge image according to claim 6.

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