JP2009204695A - Developer for electrophotography, developer cartridge for electrophotography, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer for electrophotography, restraining offset due to contamination of a fixing means and maintaining charge applying capability of carrier, a developer cartridge for electrophotography storing the developer for electrophotography, and a process cartridge and an image forming apparatus using the developer for electrophotography. <P>SOLUTION: The developer for electrophotography contains toner, the volume mean particle diameter of which is 0.2-1 μm, and to which inorganic particles with the sphericity of 0.8 or less are externally added, and carrier whose core material with magnetic powder dispersed in the resin has a volume mean particle diameter of 0.05-1 μm, and which is coated with a coating resin layer containing fine particles with the sphericity of ≥0.8. The developer cartridge for electrophotography stores the developer for electrophotography. The process cartridge and the image forming apparatus use the developer for electrophotography. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic developer, an electrophotographic developer cartridge, a process cartridge, and an image forming apparatus.

  Methods for visualizing image information through an electrostatic charge image such as electrophotography are currently used in various fields. Conventionally, in electrophotography, an electrostatic latent image is formed on a photosensitive member or an electrostatic recording body by using various means, and electro-sensitive fine particles called toner are attached to the electrostatic latent image, thereby static electricity. A method of developing and visualizing an electrostatic latent image is generally used.

  The developer used here is a two-component developer that imparts an appropriate amount of positive or negative charge to the toner by triboelectrically charging both the carrier particles called the carrier and the toner, and a toner such as a magnetic toner. It is roughly classified into a one-component developer used alone. In particular, the two-component developer allows the carrier itself to have functions such as agitation, conveyance, and charging, and can separate the functions required for the developer. Currently widely used.

  As a developing method using the two-component developer, a developer magnetic brush is brought into contact with the photosensitive member, the peripheral speed of the developing sleeve is increased with respect to the peripheral speed of the photosensitive member, and an alternating electric field and a DC electric field are superimposed. Then, a developing method is used.

Under such circumstances, a carrier in which a magnetic powder-dispersed core material is coated with a fluororesin containing fine particles has been proposed (see, for example, Patent Document 1).
JP 2004-361929 A

In order to improve the maintainability of the charge imparting ability of the carrier, there are methods of (1) appropriate wear of the coating resin and (2) suppression of contamination due to adhesion of the toner component. In order to achieve the aim, the balance has been improved. However, the balance of the aim is lost due to various image forming modes and the external environment, and as a result, the improvement in maintainability is insufficient.
For example, when a carrier coated with a low surface energy material is used to suppress contamination due to toner component adhesion, and when an image is formed with an image having a high image density, contamination due to toner component adhesion is suppressed. In addition, the effect of maintaining the charge imparting ability can be obtained. On the other hand, when an image is formed with an image having a low image density, wear of the coating resin layer is promoted and not only the charge imparting ability is lowered but also the wear pieces. Therefore, the toner image is transferred and reaches the fixing means, causing stain on the fixing means, resulting in an offset and an image defect.

In addition, attempts have been made to harden the coating layer by coating with a thermosetting resin to suppress wear of the coating resin layer, but conversely, fixing by adhesion of toner components by image formation at a high image density. Contamination of the means progresses and the charge imparting ability decreases.
The present invention has been made in view of the above problems, and an electrophotographic developer capable of suppressing offset caused by contamination of fixing means and maintaining the charge imparting ability of a carrier, and the electrophotographic developer The object is to provide an electrophotographic developer cartridge for storing the toner, a process cartridge using the electrophotographic developer, and an image forming apparatus.

The above problem is solved by the following means. That is,
The invention according to claim 1
A toner with externally added inorganic particles having a volume average particle size of 0.2 μm or more and 1 μm or less and a sphericity of 0.8 or less, and a core material in which magnetic powder is dispersed in a resin, have a volume average particle size of An electrophotographic developer comprising: a carrier coated with a coating resin layer containing fine particles having a sphericity of not less than 0.05 μm and not more than 1 μm and a sphericity of not less than 0.8.

The invention according to claim 2
The image forming apparatus is detachable and contains at least a developer to be supplied to toner image forming means provided in the image forming apparatus.
The electrophotographic developer cartridge according to claim 1, wherein the developer is the electrophotographic developer according to claim 1.

The invention according to claim 3
A toner image forming unit that stores the electrophotographic developer according to claim 1 and forms a toner image from the electrostatic latent image formed on the surface of the electrostatic latent image holding member with the developer. At least one selected from the group consisting of a holding body, a charging means for charging the surface of the electrostatic latent image holding body, and a cleaning means for removing toner remaining on the surface of the electrostatic latent image holding body. A process cartridge is provided.

The invention according to claim 4
An electrostatic latent image carrier;
Charging means for charging the surface of the electrostatic latent image holding member;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the electrostatic latent image holding member;
Toner image forming means for developing the electrostatic latent image with a developer to form a toner image;
Transfer means for transferring the toner image to a recording medium;
Fixing means for fixing the toner image on the recording medium;
With
An image forming apparatus according to claim 1, wherein the developer is the electrophotographic developer according to claim 1.

According to the first aspect of the present invention, there is provided an electrophotographic developer capable of suppressing the offset caused by the fouling of the fixing unit and maintaining the charge imparting ability of the carrier.
According to the second aspect of the present invention, there is provided an electrophotographic developer cartridge capable of suppressing the offset due to the fouling of the fixing means and maintaining the charge imparting ability of the carrier.

According to the third aspect of the present invention, there is provided a process cartridge capable of suppressing the offset due to the fouling of the fixing means and maintaining the charge imparting ability of the carrier.
According to the fourth aspect of the present invention, there is provided an image forming apparatus capable of suppressing the offset due to the fouling of the fixing unit and maintaining the charge imparting ability of the carrier.

An embodiment of the present invention will be described.
The electrophotographic developer of this embodiment (hereinafter sometimes referred to as “developer of this embodiment”) is an inorganic material having a volume average particle size of 0.2 μm to 1 μm and a sphericity of 0.8 or less. A coating resin in which a toner to which particles are externally added and a core material in which magnetic powder is dispersed in a resin contain fine particles having a volume average particle size of 0.05 μm to 1 μm and a sphericity of 0.8 or more And a carrier coated with a layer.

  The developer of this embodiment includes a carrier in which the core material is coated with a coating resin layer containing fine particles having a volume average particle diameter of 0.05 μm or more and 1 μm or less and a sphericity of 0.8 or more. By causing the carrier to wear at the interface when it receives a rubbing force, the size of the wear piece can be controlled. As a result, the coating resin layer is evenly worn and the charge imparting ability can be maintained.

In addition, the core material in which the magnetic powder used in the carrier is dispersed in the resin is (1) the surface is a resin, (2) large surface irregularities, (3) light specific gravity, (4) spherical It has the characteristic of being. By having the characteristics that (1) the surface is a resin and (2) the surface unevenness is large, the adhesion with the coating resin layer is improved and the interfacial peeling of the coating resin can be suppressed (interfacial peeling). Since the coated resin is large, it is transferred and finally reaches the fixing means and contaminates the fixing means).
Furthermore, (3) the specific gravity is light, and (4) the spherical shape makes it possible to suppress local damage due to contact between carriers in the trimming part of the developing means, and large coating resin layer wear Generation of fragments can be suppressed.

  On the other hand, when images with high area coverage are continuously formed, surface contamination due to adhesion of toner components is accelerated rather than wear of the coating resin layer. However, by adding inorganic particles having a volume average particle size of 0.2 μm or more and 1 μm or less and a sphericity of 0.8 or less to the toner as an external additive, the inorganic particles have the role of an abrasive, and the carrier coating By polishing the resin layer, it is possible to suppress surface contamination due to adhesion of toner components. When an image is formed with an image having a high area coverage, it is contaminated by the adhesion of the toner component. This contamination is polished by using the toner to which the inorganic particles are externally added.

First, the carrier contained in the developer of this embodiment will be described.
−Core material−
The core material in the carrier of the present embodiment is formed by dispersing magnetic powder in a resin.
Examples of the magnetic powder include magnetic metals such as iron, steel, nickel, and cobalt, and alloys thereof with manganese, chromium, rare earth elements, and the like (for example, nickel-iron alloys, cobalt-iron alloys, aluminum-iron alloys, etc.) ), And magnetic oxides such as ferrite and magnetite. Among these, magnetite is preferable because it is advantageous in terms of stable characteristics and low toxicity.
These magnetic powders are preferably used as a single species. When used as a single species, it is easy to maintain the generation of hemispherical particles, and it is possible to suppress further progress of destruction from the hemispherical particles to become irregularly shaped fine particles. It is possible to suppress the occurrence of a color point failure caused by.

The magnetic powder should have a particle size range of 1/400 to 1/50 and more preferably 1/300 to 1/70 with respect to the volume average particle size of the carrier. preferable. If the particle size of the magnetic powder is 1/400 or more than the assumed particle size of the carrier, the fracture mode of the carrier tends to exhibit hemispherical particles, and if it is 1/50 or less, excessive generation of hemispherical particles is suppressed. can do.
The shape of the magnetic powder is preferably a polyhedron having a number of faces of hexahedron or more, or a granular or spherical particle. If needle-shaped or spindle-shaped magnetic powder is not used, hemispherical particles are likely to be generated, and it is difficult to form irregularly shaped fine particles.

  The content of the magnetic powder in the core material is preferably in the range of 30% by mass to 95% by mass, more preferably in the range of 45% by mass to 90% by mass, and more preferably 60% by mass to 90%. More preferably, it is in the range of mass% or less. If the content is less than 30% by mass, the magnetic susceptibility per carrier is low, so that the binding force cannot be obtained, resulting in scattering and the like. May become hard and easy to break, stress on the toner may increase, and the image may become rough. On the other hand, when the amount exceeds 95% by mass, the crushed form of the carrier may further progress from a hemispherical shape to generate acute-angle particles.

As the resin component constituting the core material of the magnetic powder dispersed carrier, it is preferable to use a curable resin. Specifically, those polymerized using phenols and aldehydes are preferable, and examples thereof include crosslinked styrene resins, acrylic resins, styrene-acrylic copolymer resins, phenol resins, and the like. Resins are preferred.
These resin components are preferably used as a single species. If it is used as a single species, the carrier can be easily crushed in a hemispherical shape, and further prevented from being broken into pieces.

The volume average particle size of the core material is preferably 10 μm or more and 120 μm or less, more preferably 20 μm or more and 60 μm or less. The true specific gravity of the core material is preferably 2 g / cm ³ or more and 6 g / cm ³ or less.

-Coating resin layer-
The coating resin layer covers the surface of the core material.
As the resin used for the coating resin layer, a known resin can be used as long as it is used as a material for the coating resin layer for the carrier, and two or more kinds of resins may be blended.
The resins constituting the coating resin layer are roughly classified into a charge imparting resin for imparting chargeability to the toner and a resin having a low surface energy.

Here, examples of the charge imparting resin for imparting negative chargeability to the toner include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Furthermore, polystyrene resins such as polyvinyl and polyvinylidene resins, acrylic resins, polymethyl methacrylate resins, styrene-acrylic copolymer resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, ethyl cellulose Examples thereof include cellulose resins such as resins.
Examples of the charge imparting resin for imparting positive chargeability to the toner include polystyrene resins, halogenated olefin resins such as polyvinyl chloride, polyester resins such as polyethylene terephthalate resins and polybutylene terephthalate resins, and polycarbonate resins. Can be mentioned.

Examples of resins having low surface energy include polyethylene resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, polytrifluoroethylene resins, polyhexafluoropropylene resins, copolymers of vinylidene fluoride and acrylic monomers, And a copolymer of vinylidene fluoride and vinyl fluoride, a fluoroterpolymer such as a terpolymer of tetrafluoroethylene, vinylidene fluoride, and a non-fluorinated monomer, and a silicone resin.
The resin for the coating resin layer is preferably a thermoplastic resin.

  The coating resin layer may contain conductive powder as necessary.

The coating resin layer in the carrier contains fine particles having a volume average particle diameter of 0.05 μm or more and 1 μm or less and a sphericity of 0.8 or more. By containing the fine particles, the coating resin is peeled off from the interface between the fine particles and the coating resin, which contributes to a reduction in the diameter of the wear pieces of the coating resin layer. The fine particles may be either inorganic particles or resin particles, but are preferably harder than the coating resin.
As the inorganic _{particles, SiO 2, TiO 2, Al} 2 O 3, CuO, ZnO, SnO 2, CeO 2, Fe 2 O 3, MgO, BaO, CaO, K 2 O, Na 2 O, ZrO 2, CaO・ Inorganic oxides such as SiO ₂ , K ₂ O. (TiO ₂ ) n, Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO _{4 and the} like, particularly silica fine particles, titania fine particles, alumina Fine particles are preferred.
The resin particles include polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic. Acid copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polyurethanes, polycarbonates, phenol resins, amino resins, melamine resins, benzoguanamine resins, urea resins, amide resins, epoxy resins, etc. In particular, those having a crosslinked structure are preferred.

  The fine particles have a volume average particle size of 0.05 μm to 1 μm, preferably 0.05 μm to 0.80 μm, and more preferably 0.10 μm to 0.60 μm. The volume average particle diameter of the particles can be measured with a laser diffraction / scattering particle size distribution analyzer.

  The fine particles have a sphericity of 0.8 or more, preferably 0.85 or more, and more preferably 0.9 or more. The sphericity can be obtained from the Wadell's true sphericity shown below.

  Here, the surface area of the sphere having the same volume as the actual particles was calculated from the average particle diameter. Further, the actual particle surface area was substituted from the BET specific surface area using Shimadzu powder specific surface area measuring apparatus SS-100 type.

  Moreover, 1 mass% or more and 50 mass% or less are preferable, and, as for the preferable content in the coating resin layer of the said fine particle, 3 mass% or more and 30 mass% or less are more preferable.

  The coating amount of the coating resin layer is preferably 0.5% by mass or more and 5.0% by mass or less, and 1.0% by mass or more and 4.0% by mass or less of the total mass of the electrophotographic carrier. More preferred. When the coating amount is less than 0.5% by mass, the coating amount is decreased and the carrier surface may not be sufficiently covered.

  A typical method for forming the coating resin layer on the surface of the core material is to dissolve the resin in a resin-soluble solvent to form a resin layer forming solution, and immerse the core material powder in the resin layer forming solution. Dipping method, spraying method in which the resin layer forming solution is sprayed on the surface of the core material, fluidized bed method in which the core material is floated by flowing air, and the core material in the kneader coater. Although the kneader coater method etc. which mix the resin layer formation solution and then remove a solvent are mentioned, it does not specifically limit to the thing using a solution.

  The solvent used in the resin layer forming solution is not particularly limited as long as it dissolves the resin. Examples thereof include aromatic hydrocarbons such as xylene and toluene; ketones such as acetone and methyl ethyl ketone; tetrahydrofuran and dioxane. Ethers such as chloroform; halides such as chloroform and chlorine tetrachloride.

  The volume average particle diameter of the carrier of the present embodiment is preferably 20 μm or more and 100 μm or less, and more preferably 25 μm or more and 50 μm or less. The volume average particle diameter of the carrier can be measured by a laser diffraction / scattering particle size distribution analyzer.

Next, the toner will be described. The toner preferably contains a binder resin and a colorant.
A toner having a volume average particle diameter of 2 μm or more and 8 μm or less can be preferably used.
The volume particle size distribution index GSDv of the toner is preferably 1.25 or less. By setting the volume particle size distribution index within the above range, toner particles that are larger or smaller than the central particle diameter of the toner can be reduced. improves.
The particle size distribution of the toner was determined by the following method. For the particle size range (channel) obtained by dividing the measured particle size distribution, draw the volume cumulative distribution from the smaller particle size, define the volume average particle size to be 16% cumulative as D16, and the volume average to be 50% cumulative The particle size is defined as D50v. Furthermore, the volume average particle diameter that is 84% cumulative is defined as D84.
The volume average particle diameter in the present invention is D50v, and GSDv was calculated by the following equation.
GSDv = (D84 / D16) ^0.5

Further, by using the toner having a shape factor SF1 (ML ² / A) in the range of 120 or more and 140 or less, the contact area with the carrier can be kept moderate, so that high developability and high image quality are achieved. An image can be obtained.
The toner shape factor SF1 can be obtained by sampling the toner particles to be measured, analyzing the projected image of the toner particles photographed with an optical microscope with an image analysis device, and averaging the values of 1000 toner particles. The value obtained in this way was taken as the toner shape factor SF1. In the case of a true sphere, the toner shape factor SF1 is 100, and the larger the value, the more indefinite the shape is from the true sphere.
SF1 = (R ² × π) / (A × 4) × 100
(In the above formula, R represents the maximum toner length, and A represents the projected area of the toner.)

The toner used in the exemplary embodiment is not particularly limited by the manufacturing method, and a known manufacturing method can be used.
The toner can be produced, for example, by kneading, pulverizing, and classifying a binder resin and a colorant, and if necessary, a release agent, a charge control agent, and the like. Method of changing shape by force or thermal energy, emulsion polymerization of polymerizable monomer of binder resin, dispersion of formed dispersion, colorant, release agent, and charge control agent as required Emulsion polymerization agglomeration method to obtain toner particles by mixing and agglomerating and heat fusing the liquid, polymerizable monomer and colorant, release agent, and charge control agent if necessary Suspension polymerization in a water-based solvent for polymerization, suspension resin and colorant, and if necessary, a release agent, charge control agent, etc. in a water-based solvent for granulation A dissolution suspension method or the like can be used.

Further, a manufacturing method may be performed in which the toner obtained by the above method is used as a core, and further, aggregated particles are attached and heat-fused to have a core-shell structure. In particular, a wet process toner that makes it easy to obtain a spherical toner is preferably used, and toner particles obtained by an emulsion polymerization agglomeration method are preferably used because toner particles having a sharp distribution can be obtained.
In the emulsion polymerization aggregation method, a resin particle dispersion in which resin particles having a particle diameter of 1 μm or less are dispersed, a colorant dispersion in which a colorant is dispersed, and the like are mixed to aggregate the resin particles and the colorant into a toner particle diameter. (Hereinafter, sometimes referred to as “aggregation step”). The agglomerated particles that have undergone the aggregating step include a step of heating the resin particles to a temperature equal to or higher than the glass transition point of the resin particles to fuse the agglomerates to form toner particles (hereinafter also referred to as “fusion step”).

In the aggregation step, the resin particle dispersion, the colorant dispersion, and, if necessary, the particles in the release agent dispersion are aggregated to form aggregated particles having a toner particle size. The agglomerated particles are formed by heteroaggregation or the like. For the purpose of stabilizing the agglomerated particles and controlling the particle size / particle size distribution, the ionic surfactant having a polarity different from that of the agglomerated particles, or a monovalent or more monovalent metal salt or the like is used. A charged compound is added.
Here, “toner particle size” refers to the volume average particle size of the following toner.

  In the fusing step, the resin particles in the aggregated particles are melted under a temperature condition equal to or higher than the glass transition point, and the aggregated particles change from an irregular shape to a more spherical shape. Thereafter, the aggregate is separated from the aqueous medium, and washed and dried as necessary to form toner particles.

  Binder resins include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate , Α-methylene aliphatic monocarboxylic acid esters such as ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl Homopolymers and copolymers of vinyl ethers such as methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone, etc. , Polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene, polypropylene, etc. be able to. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

  Colorants include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black. Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. And CI Pigment Blue 15: 3.

If necessary, a release agent may be added to the toner. The release agent is generally used for the purpose of improving the releasability. Specific examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide Plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc. Mineral / petroleum waxes; ester waxes such as fatty acid esters, montanic acid esters, and carboxylic acid esters. In this embodiment, these mold release agents may be used individually by 1 type, and may use 2 or more types together.
The addition amount of these release agents is preferably 1% by mass or more and 20% by mass or less, more preferably 5% by mass or less and 15% by mass or less with respect to the total amount of toner particles.

The toner can contain a charge control agent as required. Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents having polar groups can be used.
When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination.
The toner in this embodiment may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

The inorganic oxide fine particles added to the toner include SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na _{2. O,} it can be cited _{ZrO 2, CaO · SiO 2,} K 2 O · (TiO 2) n, Al 2 O 3 · 2SiO 2, CaCO 3, MgCO 3, BaSO 4, MgSO 4 , and the like. Of these, silica fine particles and titania fine particles are particularly preferable.

  It is desirable that the surface of the inorganic oxide fine particles is previously hydrophobized. This hydrophobization treatment can improve the powder fluidity of the toner. Moreover, it is excellent in the environmental stability of charging and is effective without causing carrier deterioration.

  The hydrophobizing treatment can be performed by immersing the inorganic oxide in a hydrophobizing agent. Although there is no restriction | limiting in particular as said hydrophobic treatment agent, For example, a silane coupling agent, silicone oil, a titanate coupling agent, an aluminum coupling agent etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are preferred.

  As the silane coupling agent, for example, any type of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyl Triethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltriethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N- (trimethylsilyl) ) Urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysila , Γ-methacryloxypropyl trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyl Examples include trimethoxysilane and γ-chloropropyltrimethoxysilane.

  The amount of the hydrophobizing agent varies depending on the kind of the inorganic oxide fine particles and cannot be defined unconditionally, but is usually 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the inorganic oxide fine particles. preferable.

  The toner is externally added with inorganic particles having a volume average particle diameter of 0.2 μm or more and 1 μm or less and a sphericity of 0.80 or less (hereinafter sometimes referred to as “specific inorganic particles”). The specific inorganic particles have a volume average particle size of 0.2 μm to 1 μm, preferably 0.3 μm to 0.9 μm, and more preferably 0.4 μm to 0.8 μm. When the volume average particle size of the specific inorganic particles is less than 0.2 μm, carrier surface contamination due to the toner component when images having high area coverage are continuously formed cannot be suppressed, and the charge imparting ability of the carrier is reduced. If it exceeds 1 μm, the polishing force of the resin coating layer on the carrier surface becomes strong, so the wear pieces of the resin coating layer are large and the amount of wear also increases. As a result, contamination of the fixing member occurs, resulting in an offset. The volume average particle diameter of the specific inorganic particles can be measured with a laser diffraction / scattering particle size distribution analyzer.

  The specific inorganic particles have a sphericity of 0.80 or less and preferably 0.75 or less. When the sphericity of the specific inorganic particles exceeds 0.80, the polishing force on the resin coating layer on the carrier surface is reduced, and the carrier surface contamination due to the toner component when images with high area coverage are continuously formed is suppressed. The charge imparting ability of the carrier is lowered, and in-machine contamination due to the low-charged toner occurs. The sphericity of the specific inorganic particles can be obtained in the same manner as the sphericity of the fine particles.

Specific inorganic particles include SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO ₂ , CaO.・ SiO ₂ , K ₂ O. (TiO ₂ ) n, Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO ₄ , SrTiO ₃ , BaTiO ₃ , TiO (OH) ₂ , Al (OH) ₃ and the _{like, TiO 2, Al 2 O 3} , CeO 2, SrTiO 3 is preferable.

  The external addition amount of the specific inorganic particles with respect to the toner is preferably 0.1% by mass or more and 5.0% by mass or less, and more preferably 0.3% by mass or more and 2.0% by mass or less. The external addition amount of the specific inorganic particles can be measured with a fluorescent X-ray measuring apparatus.

  As a method of externally adding the specific inorganic particles to the toner (the toner before externally adding the toner base particles, the specific inorganic particles, etc. may be referred to as “toner base particles”), a V-type blender, a Henschel mixer, a redige It can carry out by well-known mixers, such as a mixer.

  The electrophotographic developer of this embodiment preferably contains 1 to 30 parts by mass of toner, more preferably 2 to 20 parts by mass with respect to 100 parts by mass of the electrophotographic carrier, More preferably, 3 parts by mass or more and 15 parts by mass or less are included. The carrier and the toner can be mixed using a V-type blender or a Nauta mixer.

[Electrophotographic developer cartridge, process cartridge, and image forming apparatus]
Next, the electrophotographic developer cartridge of the present embodiment (hereinafter sometimes abbreviated as “cartridge”) will be described. The cartridge according to this embodiment is detachable from the image forming apparatus, and stores at least a developer to be supplied to a toner image forming unit provided in the image forming apparatus. It is characterized by being a developer.

  In addition, the process cartridge of the present embodiment accommodates the developer of the present embodiment described above, and forms a toner image from the electrostatic latent image formed on the surface of the electrostatic latent image holding member with the developer. A group consisting of an image forming means, an electrostatic latent image holding member, a charging means for charging the surface of the electrostatic latent image holding member, and a cleaning means for removing toner remaining on the surface of the electrostatic latent image holding member. And at least one selected from the above.

  Furthermore, the image forming apparatus of the present embodiment forms an electrostatic latent image on the surface of the electrostatic latent image holding member, a charging unit that charges the surface of the electrostatic latent image holding member, and the electrostatic latent image holding member. Electrostatic latent image forming means, toner image forming means for developing the electrostatic latent image with a developer to form a toner image, transfer means for transferring the toner image to a recording medium, and fixing the toner image on the recording medium At least a fixing unit, and the developer is the electrophotographic developer of the present embodiment described above.

  The image forming apparatus according to the present embodiment includes at least the electrostatic latent image holding member, the electrostatic latent image forming unit, the toner image forming unit, the transfer unit, and the fixing unit. There is no particular limitation as long as it is present, but other means may be included.

  Hereinafter, the cartridge and the image forming apparatus of this embodiment will be specifically described with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment of the image forming apparatus of the present embodiment. An image forming apparatus 10 shown in FIG. 1 includes an electrostatic latent image holding body 12, a charging unit 14, an electrostatic latent image forming unit 16, a toner image forming unit 18, a transfer unit 20, a cleaning unit 22, a charge eliminating unit 24, and a fixing unit. 26 and a cartridge 28 are provided.
Note that the developer stored in the toner image forming unit 18 and the cartridge 28 is the developer of this embodiment.

  FIG. 1 shows only the toner image forming means 18 and the cartridge 28 containing the developer according to the present embodiment, but in addition to these, the toner image forming means and the cartridge containing other developer are also shown. It is also possible to have a configuration that is provided at the same time.

  The image forming apparatus shown in FIG. 1 is an image forming apparatus having a configuration in which a cartridge 28 can be attached and detached. The cartridge 28 is connected to the toner image forming means 18 through a developer supply pipe 30. Therefore, when image formation is performed, the developer of the present embodiment stored in the cartridge 28 is supplied to the toner image forming unit 18 through the developer supply rod 30, so that the present embodiment can be performed over a long period of time. It is possible to form an image using the developer. Further, when the amount of developer stored in the cartridge 28 is reduced, the cartridge 28 can be replaced.

  Around the electrostatic latent image holding body 12, a charging means 14 for uniformly charging the surface of the electrostatic latent image holding body 12 in order along the rotation direction (arrow A direction) of the electrostatic latent image holding body 12, an image The electrostatic latent image forming unit 16 forms an electrostatic latent image on the surface of the electrostatic latent image holding body 12 according to the information, and the toner image forming unit 18 supplies the developer of the present embodiment to the formed electrostatic latent image. A drum-shaped transfer means 20 that is in contact with the surface of the electrostatic latent image holding body 12 and can be driven to rotate in the direction of arrow B as the electrostatic latent image holding body 12 rotates in the direction of arrow A; A cleaning device 22 that abuts on the surface of the body 12 and a neutralizing means 24 that neutralizes the surface of the electrostatic latent image holding body 12 are disposed.

  A recording medium 50 transported in the direction of arrow C by a transport unit (not shown) from the opposite side to the direction of arrow C can be inserted between the electrostatic latent image holding body 12 and the transfer unit 20. A fixing unit 26 having a built-in heating source (not shown) is arranged on the electrostatic latent image holding body 12 in the direction of arrow C. The fixing unit 26 is provided with a pressure contact portion 32. Further, the recording medium 50 that has passed between the electrostatic latent image holding body 12 and the transfer means 20 can be inserted through the pressure contact portion 32 in the direction of arrow C.

As the electrostatic latent image holding member 12, for example, a photosensitive member or a dielectric recording member can be used.
As the photoreceptor, for example, a photoreceptor having a single layer structure or a photoreceptor having a multilayer structure can be used. As the material of the photoconductor, an inorganic photoconductor such as selenium or amorphous silicon, an organic photoconductor, or the like can be considered.

  Examples of the charging means 14 include a contact charging device using a conductive or semiconductive roller, brush, film, rubber blade, etc., a non-contact type charging device such as corotron charging or scorotron charging using corona discharge, etc. Any known means can be used.

As the latent image forming means 16, in addition to the exposure means, any conventionally known means capable of forming a signal capable of forming a toner image at a desired position on the surface of the recording medium can be used.
As the exposure means, for example, a conventionally known exposure means such as a combination of a semiconductor laser and a scanning device, a laser scanning writing device comprising an optical system, or an LED head can be used. In order to realize a preferable mode of producing a uniform and high-resolution exposure image, it is preferable to use a laser scanning writing device or an LED head.

  Specifically, as the transfer unit 20, for example, a conductive or semiconductive roller, brush, film, rubber blade, or the like to which a voltage is applied is used, and the electrostatic latent image holding member 12 and the recording medium 50 are used. A charged toner particle is formed by corona charging the back surface of the recording medium 50 with a means for transferring a toner image composed of charged toner particles, a corotron charger using a corona discharge, or a scorotron charger. Conventionally known means such as a means for transferring a toner image comprising the above can be used.

  A secondary transfer unit can also be used as the transfer unit 20. That is, although not shown, the secondary transfer unit is a unit that transfers the toner image to the intermediate transfer member and then secondary-transfers the toner image from the intermediate transfer member to the recording medium 50.

  Examples of the cleaning unit 22 include a cleaning blade and a cleaning brush.

  Examples of the charge eliminating unit 24 include a tungsten lamp and an LED.

  As the fixing unit 26, for example, a heat fixing unit that fixes a toner image by heating and pressing such as a heating roll and a pressure roll, or a light fixing unit that heats and fixes a toner image by light irradiation with a flash lamp or the like. Etc. are available.

  The recording medium 50 is not particularly limited, and conventionally known media such as plain paper and glossy paper can be used. A recording medium having a base material and an image receiving layer formed on the base material can also be used.

  Next, image formation using the image forming apparatus 10 will be described. First, as the electrostatic latent image holding body 12 rotates in the direction of arrow A, the surface of the electrostatic latent image holding body 12 is charged by the charging unit 14, and the electrostatic latent image holding body 12 surface is charged with the electrostatic latent image. An electrostatic latent image corresponding to the image information is formed by the image forming means 16, and a toner image is formed on the surface of the electrostatic latent image holding body 12 on which the electrostatic latent image is formed according to the color information of the electrostatic latent image. A toner image is formed by supplying the developer of this embodiment from the means 18.

  Next, the toner image formed on the surface of the electrostatic latent image holding body 12 is brought into contact with the electrostatic latent image holding body 12 and the transfer unit 20 as the electrostatic latent image holding body 12 rotates in the arrow A direction. Move to the department. At this time, the recording medium 50 is inserted through the contact portion in the direction of arrow C by a paper conveyance roll (not shown), and the electrostatic latent image is transferred by the voltage applied between the electrostatic latent image holder 12 and the transfer means 20. The toner image formed on the surface of the image carrier 12 is transferred to the surface of the recording medium 50 at the contact portion.

  The toner remaining on the surface of the electrostatic latent image holding body 12 after the toner image is transferred to the transfer unit 20 is removed by the cleaning blade of the cleaning unit 22 and the charge is removed by the charge removing unit 24.

  The recording medium 50 having the toner image transferred onto the surface in this way is conveyed to the pressure contact portion 32 of the fixing unit 26 and passes through the pressure contact portion 32 to be pressed by a built-in heating source (not shown). The surface of the section 32 is heated by the heated fixing means 26. At this time, an image is formed by fixing the toner image on the surface of the recording medium 50.

  FIG. 2 is a schematic diagram showing another preferred embodiment of the image forming apparatus of the present embodiment. The image forming apparatus 11 shown in FIG. 2 includes a process cartridge 38 that is detachably attached to an image forming apparatus main body (not shown), an electrostatic latent image forming unit 16, and a transfer unit 20.

  In the process cartridge 38, the electrostatic latent image holding body 12 is mounted in a housing 36 provided with an opening 34 for exposure, and the charging unit 14, the toner image forming unit 18, and the cleaning unit 22 are attached to the periphery of the process cartridge 38. (Not shown) are combined and integrated. The process cartridge 38 is not limited to this, and may include the toner image forming unit 18 and at least one selected from the group consisting of the electrostatic latent image holding body 12, the charging unit 14, and the cleaning unit 22. .

  On the other hand, the electrostatic latent image forming unit 16 is disposed at a position where the electrostatic latent image holding body 12 can be exposed from the opening 34 of the housing 36 of the process cartridge 38. The transfer means 20 is disposed at a position facing the electrostatic latent image holding body 12.

Hereinafter, the present embodiment will be described more specifically by way of examples, but the present embodiment is not limited to these. In the description of the toner and the carrier, “part” means “part by mass” unless otherwise specified.
In the production of toner, carrier, and electrostatic latent image developer, each measurement was performed by the following method.
(Volume average particle diameter of fine particles)
The volume average particle size of the fine particles contained in the coating resin layer of the carrier and the particles externally added to the toner base particles are measured with respect to pure water using a laser diffraction / scattering particle size distribution analyzer LS13320 (manufactured by Coulter). Measurement was performed by dispersing fine particles (particles) in an aqueous solution of polyoxyethylene octylphenyl ether having a concentration of 0.2% by mass (pump speed: 85%).

(Sphericity)
As the sphericity of the fine particles contained in the coating resin layer of the carrier and the particles externally added to the toner base particles, the following Wadell's true sphericity was adopted.

  Here, the surface area of the sphere having the same volume as the actual particles was calculated from the average particle diameter. Further, the actual particle surface area was substituted from the BET specific surface area using Shimadzu powder specific surface area measuring apparatus SS-100 type.

(Toner shape factor SF1)
In the present embodiment, the average shape index SF1 = (ML ² / A) of the toner means a value calculated by the following formula, and ML ² / A = 100 in the case of a true sphere.
SF1 = ML ² / A = (maximum length) ² × π × 100 / (area × 4)
As a specific method for obtaining the shape factor SF1, a toner image is taken from an optical microscope into an image analyzer (LUZEX III, manufactured by Nireco Corporation), an equivalent circle diameter is measured, and the maximum length and area are individually measured. The value of ML ² / A in the above formula is determined for the particles of.

(Measurement of volume average particle diameter of toner base particles)
When the particle diameter to be measured is 2 μm or more, the particle size is measured using Multisizer II type (Beckman-Coulter) as the measuring device and ISOTON-II (Beckman-Coulter) as the electrolyte. did.

As a measurement method, 0.5 to 50 mg of a measurement sample was added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant, and this was added to 100 ml of the electrolytic solution. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for 1 minute, and the particle size is in the range of 2.0 to 60 μm using the Multisizer II type aperture having an aperture diameter of 100 μm. The particle size distribution of the particles was measured. The number of particles to be measured was 50,000.
For the divided particle size range (channel), the measured particle size distribution is a cumulative distribution drawn from the small diameter side for each volume and number, and the particle size that is 50% cumulative in volume is defined as the volume average particle size D50v. The value was defined as the volume average particle size.

<Example 1>
(Preparation of core material A)
Add 50 parts of phenol, 140 parts of 20% formalin, 400 parts of magnetite (average particle diameter 0.20 μm, spherical, 2% by mass KR43S treated product), 42 parts of 10% by mass ammonia water, and 60 parts of ion exchange water, and mix and stir. However, after gradually raising the temperature to 85 ° C. and reacting and curing for 4 hours, cooling, filtration, washing and drying were performed to obtain a core material A having a volume average particle size of 35.4 μm.

(Preparation of carrier A)
Toluene: 120 parts Styrene-methacrylate copolymer (mass ratio 20:80, Mw: 80,000): 2.5 parts Melamine resin fine particles (volume average particle diameter: 0.2 μm, sphericity: 0.91) : 0.3 part The above components were stirred / dispersed with a stirrer for 60 minutes to prepare a coating layer (coating resin layer) forming solution a.
Further, 122.8 parts of the coating layer forming solution a and the core material A thus obtained were placed in a vacuum degassing kneader (trade name: KHO-5, manufactured by Inoue Seisakusho Co., Ltd.) and stirred at 60 ° C. for 20 minutes. Thereafter, while further heating, the carrier A was produced by depressurizing and deaeration and drying, and passing through a mesh having an opening of 106 μm.

(Preparation of Toner A)
100 parts of toner base particles (volume average particle size: 6.0 μm, shape factor SF1: 135, Cyan) synthesized by the emulsion aggregation coalescence method, 1.5 parts of dry process silica (volume average particle size: 40 nm) are added. , 1 part of anatase-type titanium oxide (volume average particle diameter: 20 nm) and 0.5 part of cerium oxide (volume average particle diameter: 0.65 μm, sphericity: 0.68) were externally added using a Henschel mixer, Coarse particles were removed using a sieve having an opening of 106 μm to prepare toner A.

(Preparation of developer A)
100 parts of carrier A and 8 parts of toner A were mixed with a V blender, and sieved through a 500 μm mesh to prepare developer A.

<Example 2>
(Preparation of carrier B)
Carrier B was prepared in exactly the same manner as Carrier A except that 0.2 parts of silica fine particles (sol-gel method, volume average particle size: 0.058 μm, sphericity: 0.92): 0.2 parts were used instead of melamine resin fine particles. .
(Preparation of developer B)
Developer B was prepared in exactly the same manner as Developer A, except that carrier B was used instead of carrier A.

<Example 3>
(Preparation of carrier C)
-Toluene: 120 parts-Styrene-methacrylate copolymer (mass ratio 10:90, Mw: 40,000): 3.0 parts-Polymethyl methacrylate-based crosslinked fine particles (volume average particle diameter: 0.9 μm, sphericity: 0.93): 0.4 part The above components were stirred / dispersed with a stirrer for 60 minutes to prepare a coating layer forming solution c.
Further, 123.4 parts of the coating layer forming solution c and the core material A thus obtained were placed in a vacuum degassing type kneader (trade name: KHO-5, manufactured by Inoue Seisakusho Co., Ltd.) and stirred at 60 ° C. for 20 minutes. After that, while further heating, the carrier C was produced by depressurizing and deaeration and drying, and passing through a mesh having an opening of 106 μm.
(Preparation of developer C)
Developer C was produced in the same manner as Developer A except that Carrier C was used instead of Carrier A.

<Example 4>
(Preparation of carrier D)
Carrier D was prepared in the same manner as Carrier A except that 0.2 parts of silica fine particles (wet method, volume average particle size: 0.13 μm, sphericity: 0.82): 0.2 parts were used instead of melamine resin fine particles. .
(Preparation of developer D)
Developer D was prepared in exactly the same manner as Developer A, except that carrier D was used instead of carrier A.

<Example 5>
(Production of Toner E)
Toner E was prepared in the same manner as toner A, except that strontium titanate (volume average particle diameter: 0.23 μm, sphericity: 0.75) was used instead of cerium oxide.
(Preparation of developer E)
Developer E was prepared in exactly the same manner as Developer A, except that toner E was used instead of toner A.

<Example 6>
(Production of Toner F)
Toner F was produced in the same manner as toner A, except that alumina (volume average particle size: 0.90 μm, sphericity: 0.78) was used instead of cerium oxide.
(Preparation of developer F)
Developer F was prepared in exactly the same manner as Developer A, except that toner F was used instead of toner A.

<Comparative Example 1>
(Preparation of carrier G)
A carrier G was produced in the same manner as the carrier A except that Cu · Zn ferrite particles (particle size: 35 μm) were used instead of the core material A.
(Preparation of developer G)
Developer G was prepared in exactly the same manner as Developer A, except that carrier G was used instead of carrier A.

<Comparative Example 2>
(Preparation of carrier H)
Carrier H was prepared in exactly the same manner as Carrier A except that melamine resin fine particles were not used.
(Preparation of developer H)
Developer H was prepared in exactly the same manner as Developer A, except that carrier H was used instead of carrier A.

<Comparative Example 3>
(Preparation of Toner I)
Toner I was obtained in exactly the same manner as in the preparation of toner A except that cerium oxide was not added.
(Preparation of developer I)
Developer I was prepared in exactly the same manner as Developer A, except that toner I was used instead of toner A.

<Comparative example 4>
(Preparation of Carrier J)
Carrier J was prepared in exactly the same manner as Carrier A except that 0.2 parts of silica fine particles (sol-gel method, volume average particle size: 0.045 μm, sphericity: 0.93) instead of melamine resin fine particles were used. .
(Preparation of developer J)
Developer J was prepared in exactly the same manner as Developer A, except that carrier J was used instead of carrier A.

<Comparative Example 5>
(Preparation of carrier K)
Melamine resin fine particles (volume average particle size: 1.2 μm, sphericity: 0.93): Carrier K was prepared in exactly the same manner as carrier A, except that 0.3 part was used.
(Preparation of developer J)
Developer K was prepared in exactly the same manner as Developer A, except that carrier K was used instead of carrier A.

<Comparative Example 6>
(Preparation of carrier L)
Carrier K was prepared in the same manner as Carrier A except that 0.2 parts of silica fine particles (wet method, volume average particle size: 0.12 μm, sphericity: 0.76): 0.2 parts were used instead of melamine resin fine particles. .
(Preparation of developer L)
Developer L was produced in the same manner as Developer A except that Carrier L was used instead of Carrier A.

<Comparative Example 7>
(Preparation of Toner M)
Toner M was produced in the same manner as toner A, except that alumina (volume average particle size: 0.60 μm, sphericity: 0.84) was used instead of cerium oxide.
(Preparation of developer M)
Developer M was produced in the same manner as Developer A, except that toner M was used instead of toner A.

<Comparative Example 8>
(Preparation of toner N)
Toner N was prepared in the same manner as toner A, except that cerium oxide (volume average particle diameter: 1.1 μm, sphericity: 0.76) was used.
(Preparation of developer N)
Developer N was prepared in exactly the same manner as Developer A, except that toner N was used instead of toner A.

<Comparative Example 9>
(Production of Toner O)
Toner O was produced in the same manner as toner A, except that titanium oxide (rutile type, volume average particle size: 0.16 μm, sphericity: 0.55) was used instead of cerium oxide.
(Preparation of developer O)
Developer O was prepared in exactly the same manner as Developer A, except that toner O was used instead of toner A.

<Evaluation>
The following evaluation was performed on each of the obtained developers.
(Chargeability evaluation)
First, the same developer is put into two developing machines, and the developer on the mag sleeve in the developing machine is collected from one of the developing machines before the start of printing the charge amount of the developer (initial charge amount). , Measured with TB200 (manufactured by Toshiba Corporation). Furthermore, using Docu Center Color 450, two developing machines are set, and in an environment of 20 ° C. and 50%, one developing machine prints a chart with an image density of 0.1% and the other developing machine prints with a chart of 20%. The image is formed on a total of 50,000 sheets in 5 jobs per job, the carrier is taken out from the developer after the image is formed by blow-off, and the removed carrier is used as a new toner (when an image is formed). The charge amount was measured in combination with the same type of toner), and the value (average value) divided by the initial charge amount was evaluated as the chargeability. The evaluation criteria are as follows. The results are shown in Table 1.
[Evaluation criteria]
A: 0.90 to 1.00
○: 0.80 to 0.89
Δ: 0.70 to 0.79
X: Less than 0.70

(Fouling evaluation of fixing means)
Using Docu Center Color 450, a total of 50,000 images were formed with 5 images per job in an image density of 0.1% and 20% in an environment of 20 ° C. and 50%. The presence or absence was subjected to sensory evaluation. The evaluation criteria are as follows. The results are shown in Table 1.
[Evaluation criteria]
○: No fouling of fixing means Δ: Fouling of fixing means but no image quality failure ×: Image quality failure occurred

1 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment of an image forming apparatus of the present embodiment. It is a schematic diagram which shows another suitable one Embodiment of the image forming apparatus of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 11 ... Image forming apparatus 12 ... Electrostatic latent image holding body 14 ... Charging means 16 ... Electrostatic latent image forming means 18 ... Toner image forming means 20 ... Transfer means 26 ... Fixing means 28 ... cartridge 34 ... opening 36 ... casing 38 ... process cartridge

Claims (4)

A toner to which inorganic particles having a volume average particle size of 0.2 μm or more and 1 μm or less and a sphericity of 0.8 or less are externally added;
A carrier in which a core material in which magnetic powder is dispersed in a resin is coated with a coating resin layer containing fine particles having a volume average particle size of 0.05 μm or more and 1 μm or less and a sphericity of 0.8 or more;
An electrophotographic developer comprising: The image forming apparatus is detachable and contains at least a developer to be supplied to toner image forming means provided in the image forming apparatus.
The electrophotographic developer cartridge according to claim 1, wherein the developer is the electrophotographic developer according to claim 1. A toner image forming unit that stores the electrophotographic developer according to claim 1 and forms a toner image from the electrostatic latent image formed on the surface of the electrostatic latent image holding member with the developer. At least one selected from the group consisting of a holding body, a charging means for charging the surface of the electrostatic latent image holding body, and a cleaning means for removing toner remaining on the surface of the electrostatic latent image holding body. A process cartridge comprising: An electrostatic latent image carrier;
Charging means for charging the surface of the electrostatic latent image holding member;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the electrostatic latent image holding member;
Toner image forming means for developing the electrostatic latent image with a developer to form a toner image;
Transfer means for transferring the toner image to a recording medium;
Fixing means for fixing the toner image on the recording medium;
With
The image forming apparatus according to claim 1, wherein the developer is the electrophotographic developer according to claim 1.

Images