JP6891504B2 - Carrier, two-component developer using it, replenisher developer, image forming apparatus, process cartridge, and image forming method - Google Patents

Description

The present invention relates to a carrier, a two-component developer using the carrier, a supplementary developer, an image forming apparatus, a process cartridge, and an image forming method.

In image formation by the electrophotographic method, an electrostatic latent image is formed on an electrostatic latent image carrier such as a photoconductive substance, and a charged toner is adhered to the electrostatic latent image to form a toner image. After that, the toner image is transferred to a recording medium, fixed, and becomes an output image. In recent years, the technology of copiers and printers using the electrophotographic method has been rapidly expanding from monochrome to full color, and the full color market tends to expand.

In full-color image formation, generally, three color toners of yellow, magenta, and cyan, or four color toners in which black is added are laminated to reproduce all colors. Therefore, in order to obtain a clear full-color image with excellent color reproducibility, it is necessary to smooth the surface of the fixed toner image to reduce light scattering. For this reason, the image gloss of conventional full-color copiers and the like is often 10 to 50% with medium to high gloss.

Generally, as a method for fixing a dry toner image on a recording medium, a contact heat fixing method in which a roller or a belt having a smooth surface is heated and pressure-bonded with the toner is often used. Such a method has high thermal efficiency, enables high-speed fixing, and can give gloss and transparency to the color toner image, but on the other hand, the surface of the heat-fixing member and the molten toner are brought into contact with each other under pressure. Since the toner image is peeled off after being formed, a part of the toner image adheres to the surface of the fixing roller and is transferred to another image, that is, a so-called offset phenomenon occurs.

For the purpose of preventing such an offset phenomenon, the surface of the fixing roller is formed of silicone rubber or fluororesin having excellent mold releasability, and the surface of the fixing roller is coated with an oil for preventing toner sticking such as silicone oil. The method of doing is generally adopted. However, although such a method is extremely effective in preventing the offset of the toner, there is a problem that a device for supplying oil is required and the fixing device becomes large.

For this reason, in monochrome image formation, an oilless system that does not apply oil to the fixing roller by using a toner that has a large viscoelasticity at the time of melting and contains a mold release agent so that the melted toner does not break internally, or There is a tendency to adopt a system in which the amount of oil applied is very small.

On the other hand, also in full-color image formation, as in monochrome image formation, an oilless system tends to be adopted for the purpose of downsizing and simplifying the configuration of the fixing device. However, in full-color image formation, in order to smooth the surface of the fixed toner image, it is necessary to reduce the viscoelasticity of the toner at the time of melting, so that an offset occurs as compared with the case of forming a matte monochrome image. It is easy and difficult to adopt an oilless system. Further, when a toner containing a release agent is used, the adhesiveness of the toner is increased and the transferability to a recording medium is lowered. Further, there is a problem that the durability is lowered due to the filming of the toner and the lowering of the chargeability.

On the other hand, as carriers, prevention of toner filming, formation of uniform surface, prevention of surface oxidation, prevention of deterioration of humidity sensitivity, extension of developer life, prevention of adhesion of photoconductor to surface, photosensitization For the purpose of protecting the body from scratches or wear, controlling the polarity of charge, adjusting the amount of charge, etc., the surface of the carrier core material is coated with a resin with low surface energy, such as fluororesin or silicone resin. The life has been extended.

Examples of carriers coated with a low surface energy resin include carriers coated with a room temperature curable silicone resin and a positively charged nitrogen resin described in JP-A-55-127569 of Patent Document 1, and JP-A-A of Patent Document 2. A carrier coated with a coating material containing at least one modified silicone resin described in Japanese Patent Application Laid-Open No. 55-157751, a room temperature curable silicone resin described in Japanese Patent Application Laid-Open No. 56-140358 of Patent Document 3, and a styrene / acrylic resin. Carrier having a resin-coated layer, a carrier described in JP-A-57-96355 of Patent Document 4 with two or more layers of silicone resin so as not to have adhesiveness between layers, Patent Document 5 A carrier in which a silicone resin is coated in multiple layers on the surface of the core particles described in JP-A-57-96356, and a carrier in which the surface is coated with a silicone resin containing silicon carbide described in JP-A-58-207054 of Patent Document 6. , A positively charged carrier coated with a material exhibiting a critical surface tension of 20 dyn / cm or less described in JP-A-61-10161 of Patent Document 7, and a fluoroalkyl carrier described in JP-A-62-273576 of Patent Document 8. Examples thereof include a carrier coated with a coating material containing an acrylate and a developer composed of a toner containing a chromium-containing azo dye.

However, recently, carriers have a long life, and image forming devices have been used everywhere in the world to provide stable images in a wide range of environments from high temperature and high humidity to low temperature and low humidity. Is required. In particular, at high temperature and high humidity, fluctuations in the amount of charge and resistance of carriers become large, and it is difficult to maintain image quality. This is because the amount of water in the air increases, chemical and physical adsorption to the carrier progresses, and the carrier quality changes.

Examples of carriers that provide stable images under high temperature and high humidity include, for example, Japanese Patent Application Laid-Open No. 2001-343790 of Patent Document 9, Japanese Patent Application Laid-Open No. 2007-17838 of Patent Document 10, and Japanese Patent Application Laid-Open No. 2015-2015 of Patent Document 11. It is described in Japanese Patent Application Laid-Open No. 179258. However, all of these Patent Documents 8 to 10 are related to fluctuations in the amount of charge due to moisture adsorption of carriers, and there is no disclosure regarding fluctuations in carrier resistance in the prior art, and there is room for improvement at present.

An object of the present invention is to provide a carrier that enables high image quality and high durability even under high temperature and high humidity.

The above problem is solved by the following configuration 1).
1) A carrier having a core and a coating layer covering the core.
The coating layer contains conductive fine particles and contains
The carrier, wherein the conductive fine particles contain tungsten-doped tin oxide that has been surface-treated with any one selected from vinyltriethoxysilane, n-octyltriethoxysilane, and p-styryltrimethoxysilane.

According to the present invention, it is possible to provide a carrier that enables high image quality and high durability even under high temperature and high humidity.

It is a figure explaining the cell for measuring the volume resistivity in this invention. It is a figure which shows an example of the process cartridge of this invention.

Hereinafter, embodiments of the present invention will be described in detail.
The carrier of the present invention has a core and a coating layer that covers the core, and the coating layer contains conductive fine particles, and the conductive fine particles contain surface-treated tungsten-doped tin oxide. It is a feature.

In the prior art, there are some conductive fine particles in which a core such as a metal is coated with a conductive material. However, such conductive fine particles have a large particle size, and the toner spend is increased due to the high hardness. It is easy to progress and is not preferable.
On the other hand, according to the study of the present inventor, tungsten-doped tin oxide has a small powder resistivity, does not contaminate the toner even when used as a color developer, and has easy control of the primary particle size. It was found that it has characteristics such as being present. In the present invention, by adopting this tungsten-doped tin oxide, resistance is stable for a long period of time even under high temperature and high humidity, toner spent is suppressed, excellent charge stability is achieved, and high image quality and high durability are achieved. It is possible to provide a carrier that enables it.

The tungsten-doped tin oxide in the present invention is surface-treated. Tungsten-doped tin oxide tends to aggregate, so surface treatment is required to improve dispersibility. By performing the surface treatment, the adsorption of chemical moisture at the portion exposed on the carrier surface under high temperature and high humidity is suppressed. Further, by performing surface treatment to improve the dispersibility, tungsten-doped tin oxide is uniformly present in the coating layer. Then, the unevenness derived from the conductive fine particles on the carrier surface is reduced, so that the specific surface area of the carrier is reduced, and physical moisture adsorption under high temperature and high humidity can be suppressed. For the above reason, it is possible to suppress fluctuations in carrier resistance due to moisture adsorption even under high temperature and high humidity, and it is possible to output a stable image.

For the surface treatment of tungsten-doped tin oxide in the present invention, various known surface treatment agents can be used as long as the above effects can be obtained. Suitable surface treatment agents include silane coupling agents, for example, amino-based silane coupling agents, methacryoxy-based silane coupling agents, vinyl-based silane coupling agents, mercapto-based silane coupling agents, alkyl-based silane cups. Examples thereof include a ring agent and a styryl-based silane coupling agent.

The amount of the surface treatment agent adhered is, for example, 0.1 to 10% by mass, preferably 1 to 5% by mass, based on the tungsten-doped tin oxide. The surface treatment can be performed by a known stirring device.

The primary particle size of tungsten-doped tin oxide is preferably 50 nm to 300 nm, preferably 100 nm to 250 nm. When the conductive fine particles are 50 nm or more, the dispersibility is improved, the particles are less likely to exist in the coating layer in an aggregated state, the specific surface area of the carrier can be reduced, and physical moisture adsorption can be suppressed. Further, when it is 300 nm or less, it is not subject to a stirring hazard in the developing machine, and it is possible to avoid a decrease in resistance due to scraping of the coating layer and a decrease in the amount of charge due to the progress of toner spent.
The primary particle size of tungsten-doped tin oxide can be measured using, for example, Nanotrack UPA-EX150 (manufactured by Nikkiso Co., Ltd.), and the primary particle size of the present invention is an average primary particle size.

It is preferable that the powder specific resistance of the tungsten-doped tin oxide is small because the carrier resistance can be adjusted by adding a small amount. The powder resistivity of tungsten-doped tin oxide is preferably 20 Ω · cm or less. Since the powder specific resistance is 20 Ω · cm or less, the amount used for adjusting the resistance of the carrier can be reduced, the unevenness of the coating layer and the formation of a strong coating layer can be suppressed, and the toner spent and the charge can be reduced. Can be prevented.
The powder resistivity can be measured using, for example, an LCR meter AR-480D type (manufactured by Keisei).

In the present invention, the conductive fine particles are preferably composed of the tungsten-doped tin oxide as described above, but if necessary, other conductive fine particles may be added in an amount of 50% by mass or less based on the total conductive fine particles. It can also be used in a range. The primary particle size of the other conductive fine particles is preferably in the range of the primary particle size of the tungsten-doped tin oxide.

The content of tungsten-doped tin oxide is, for example, 20 to 60% by mass, preferably 30 to 50% by mass, based on the entire coating layer.

The carrier of the present invention preferably has a volume average particle diameter of 32 μm or more and 40 μm or less. When the volume average particle diameter of the carrier is 32 μm or more, carrier adhesion can be prevented, and when it is 40 μm or less, the reproducibility of image details is improved and a fine image can be formed.
The volume average particle size can be measured using, for example, the Microtrack particle size distribution meter model HRA9320-X100 (manufactured by Nikkiso Co., Ltd.).

The carrier of the present invention preferably has a volume resistivity of 10 to 14 (LogΩ · cm). When the volume resistivity is 10 (LogΩ · cm) or more, carrier adhesion in the non-image portion can be prevented, and when it is 14 (LogΩ · cm) or less, the edge effect becomes an allowable level.

The volume resistivity can be measured using the cell shown in FIG. Specifically, first, the carrier (3) is placed in a cell composed of a fluororesin container (2) in which an electrode (1a) having a surface area of 2.5 cm × 4 cm and an electrode (1b) are housed at a distance of 0.2 cm. ) Is filled, and tapping is performed 10 times with a drop height of 1 cm and a tapping speed of 30 times / minute. Next, a DC voltage of 1000 V was applied between the electrodes (1a) and (1b), and the resistance value r [Ω] 30 seconds later was measured using a high resistance meter 4329A (manufactured by Hewlett-Packard Japan). Then, the volume resistivity [Ω · cm] can be calculated from the following equation 2.

The coating layer of the carrier can contain a resin. As the resin, a silicone resin, an acrylic resin, or a combination thereof can be used. Acrylic resin has strong adhesiveness and low brittleness, so it has excellent wear resistance. On the other hand, because of its high surface energy, toner component spends accumulate when combined with toner that is easy to spend. This may cause problems such as a decrease in the amount of charge. In that case, this problem can be solved by using a silicone resin in combination, which has an effect that it is difficult to spent the toner component because the surface energy is low and it is difficult for the accumulation of the spent component to proceed due to film scraping. Since the silicone resin has weak adhesiveness and high brittleness, it also has a weakness of poor wear resistance. Therefore, it is preferable to use these two types of resins in a well-balanced manner. For example, in the coating layer, the silicone resin is preferably added in an amount of 10 to 80% by mass, and the acrylic resin is preferably added in an amount of 5 to 30% by mass.

The term "silicone resin" as used herein refers to all generally known silicone resins, such as straight silicones consisting only of organoshirosan bonds, silicone resins modified with alkyds, polyesters, epoxys, acrylics, urethanes, etc. However, it is not limited to this. For example, as commercially available straight silicone resins, KR271, KR255, KR152 manufactured by Shin-Etsu Chemical Co., Ltd., SR2400, SR2406, SR2410 manufactured by Toray Dow Corning Silicone Co., Ltd. and the like can be mentioned. In this case, it is possible to use the silicone resin alone, but it is also possible to use other components that undergo a cross-linking reaction, a charge amount adjusting component, and the like at the same time. Further, as the modified silicone resin, KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), KR305 (urethane modified) manufactured by Shin-Etsu Chemical Co., Ltd., SR2115 (epoxy modified) manufactured by Toray Dow Corning Silicone Co., Ltd. , SR2110 (alkyd modification) and the like.

Further, as the resin used for the coating layer, an acrylic copolymer composed of the monomers A, B and C as shown in the following general formulas (1) to (3) may be used. In the copolymer, the coating film is extremely tough and difficult to scrape, high durability can be achieved, and even if the coating layer is thinned, the core is not easily exposed by use.

In the general formulas (1) to (3), R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 4 carbon atoms, and R ³ represents an alkyl group having 1 to 8 carbon atoms. Alternatively, it represents an alkoxy group having 1 to 4 carbon atoms, m represents an integer of 1 to 8, X represents 10 mol% to 40 mol%, Y represents 10 mol% to 40 mol%, and Z represents 30 mol% to 80 mol%. Represents. And 60 mol% <Y + Z <90 mol%.

Examples of the polycondensation catalyst used for preparing the acrylic copolymer include titanium-based catalysts, tin-based catalysts, zirconium-based catalysts, and aluminum-based catalysts. Among the titanium-based catalysts produced, titanium diisopropoxybis (ethylacetacetate) is the most preferable catalyst. It is considered that this is because the effect of promoting the condensation reaction of the silanol group is large and the catalyst is not easily deactivated.

The term "acrylic resin" as used herein refers to all resins having an acrylic component, and is not particularly limited. Further, although it is possible to use the acrylic resin alone, it is also possible to use at least one or more other components that undergo a cross-linking reaction at the same time. Examples of the other components that undergo a cross-linking reaction here include, but are not limited to, amino resins and acidic catalysts. The amino resin referred to here refers to, but is not limited to, guanamine, melamine resin, and the like. Further, as the acidic catalyst referred to here, any catalyst having a catalytic action can be used. For example, it has a reactive group such as a fully alkylated type, a methylol group type, an imino group type, and a methylol / imino group type, but is not limited thereto.

Further, it is more preferable that the coating layer contains a crosslinked product of an acrylic resin and an amino resin.
As a result, fusion between the coating layers can be suppressed while maintaining appropriate elasticity.
The amino resin is not particularly limited, but a melamine resin and a benzoguanamine resin are preferable because the charging ability of the carrier can be improved. Further, when it is necessary to appropriately control the charging ability of the carrier, the melamine resin and / or the benzoguanamine resin may be used in combination with another amino resin.

As the acrylic resin that can be crosslinked with the amino resin, one having a hydroxyl group and / or a carboxyl group is preferable, and one having a hydroxyl group is more preferable. As a result, the adhesion to the core material particles and the conductive fine particles can be further improved, and the dispersion stability of the conductive fine particles can also be improved. At this time, the hydroxyl value of the acrylic resin is preferably 10 mgKOH / g or more, and more preferably 20 mgKOH / g or more.

In the present invention, the composition for forming the coating layer preferably contains a silane coupling agent.
Thereby, the conductive fine particles can be stably dispersed.
The silane coupling agent is not particularly limited, but is r- (2-aminoethyl) aminopropyltrimethoxysilane, r- (2-aminoethyl) aminopropylmethyldimethoxysilane, r-methacryloxypropyltrimethoxysilane, N. -Β- (N-vinylbenzylaminoethyl) -r-aminopropyltrimethoxysilane hydrochloride, r-glycidoxypropyltrimethoxysilane, r-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, Vinyl triacetoxysilane, r-chloropropyltrimethoxysilane, hexamethyldisilazane, r-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, r-chlor Propylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, allyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, dimethyldiethoxysilane, 1,3-divinyltetramethyl Examples thereof include disilazane and methacryloxyethyldimethyl (3-trimethoxysilylpropyl) ammonium chloride, and two or more of them may be used in combination.

Commercially available silane coupling agents include AY43-059, SR6020, SZ6023, SH6026, SZ6032, SZ6050, AY43-310M, SZ6030, SH6040, AY43-026, AY43-031, sh6062, Z-6911, sz6300, sz6075, sz6079, sz6083, sz6070, sz6072, Z-6721, AY43-004, Z-6187, AY43-021, AY43-043, AY43-040, AY43-047, Z-6265, AY43-204M, AY43-048, Z- 6403, AY43-206M, AY43-206E, Z6341, AY43-210MC, AY43-083, AY43-101, AY43-013, AY43-158E, Z-6920, Z-6940 (manufactured by Toray Silicone Co., Ltd.) and the like. ..

When a silicone resin is used, the amount of the silane coupling agent added is preferably 0.1 to 10% by mass with respect to the silicone resin. If the amount of the silane coupling agent added is less than 0.1% by mass, the adhesiveness between the core material particles and the conductive fine particles and the silicone resin is lowered, and the coating layer may fall off during long-term use. If it exceeds 10% by mass, filming of the toner may occur during long-term use.

The film thickness of the coating layer in the present invention is, for example, 0.1 μm to 1.0 μm, preferably 0.3 μm to 0.8 μm.

The core in the carrier of the present invention is not particularly limited as long as it is a magnetic material, but is not particularly limited. Ferromagnetic metals such as iron and cobalt; iron oxides such as magnetite, hematite and ferrite; various alloys and compounds; Examples thereof include resin particles dispersed therein. Among them, Mn-based ferrite, MnMg-based ferrite, MnMg-Sr ferrite and the like are preferable from the viewpoint of the environment.

The volume average particle size of the core is not particularly limited, but it is preferably 20 μm or more from the viewpoint of preventing carrier adhesion and carrier scattering, and it is possible to prevent the occurrence of abnormal images such as carrier streaks and reduce the image quality. From the viewpoint of prevention, those having a diameter of 100 μm or less are preferable, and those having a diameter of 20 to 60 μm can be more preferably responded to the recent improvement in image quality. The volume average particle size can be measured using, for example, the Microtrack particle size distribution meter model HRA9320-X100 (manufactured by Nikkiso Co., Ltd.).

The two-component developer of the present invention has the carrier and toner of the present invention.
The toner contains a binder resin and a colorant, but may be either a monochrome toner or a color toner. Further, the toner particles may contain a mold release agent in order to apply to an oilless system in which the fixing roller is not coated with the toner sticking prevention oil. Such toners are generally prone to filming, but the carriers of the present invention can suppress filming, so that the developer of the present invention maintains good quality for a long period of time. Can be done.
Further, color toners, particularly yellow toners, generally have a problem that color stains are generated due to scraping of the coating layer of the carrier, but the developer of the present invention can suppress the occurrence of color stains.

In the two-component developer of the present invention, when the whole is 100 parts by mass, for example, the carrier is preferably used in the range of 88 to 98 parts by mass, and the toner is used in the range of 2 to 12 parts by mass. Is preferable.

The toner can be produced by using a known method such as a pulverization method or a polymerization method. For example, when a toner is produced by using a pulverization method, first, the melt-kneaded product obtained by kneading the toner material is cooled, then pulverized and classified to produce parent particles. Next, in order to further improve the transferability and durability, an external additive is added to the parent particles to prepare a toner.

At this time, the apparatus for kneading the toner material is not particularly limited, but is a batch type two-roll; Banbury mixer; KTK type twin-screw extruder (manufactured by Kobe Steel Co., Ltd.), TEM type twin-screw extruder (Toshiba Machine Co., Ltd.). Continuous twin-screw extruder such as twin-screw extruder (manufactured by KCK), PCM-type twin-screw extruder (manufactured by Ikekai Iron Works), KEX-type twin-screw extruder (manufactured by Kurimoto Iron Works); Examples thereof include a continuous type uniaxial kneader such as Ko Nida (manufactured by Buss).

When crushing the cooled melt-kneaded product, it is roughly pulverized using a hammer mill, a rotoplex, or the like, and then finely pulverized using a pulverizer using a jet stream, a mechanical pulverizer, or the like. be able to. It is preferable to grind so that the average particle size is 3 to 15 μm.
Further, when classifying the crushed melt-kneaded product, a wind power classifier or the like can be used. It is preferable to classify the matrix particles so that the average particle size is 5 to 20 μm.
Further, when the external additive is added to the matrix particles, the external additive is crushed and adheres to the surface of the matrix particles by mixing and stirring using mixers.

The binder resin is not particularly limited, but is a homopolymer of styrene such as polystyrene, polyp-styrene, polyvinyltoluene and its substitution product; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene. -Vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer , Styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinylmethyl ether copolymer, styrene-vinylmethylketone copolymer, styrene-butadiene Styrene-based copolymers such as copolymers, styrene-isoprene copolymers, styrene-maleic acid ester copolymers; polymethylmethacrylate, butylpolymethacrylate, vinyl chloride, vinylacetate, polyethylene, polyester, polyurethane , Epoxy resin, polyvinyl butyral, polyacrylic acid, rosin, modified rosin, terpen resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic petroleum resin and the like, and two or more of them may be used in combination.
The binder resin for pressure fixing is not particularly limited, but is a polyolefin such as low molecular weight polyethylene and low molecular weight polypropylene; ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, and styrene-methacrylic acid copolymer. , Ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, olefin copolymer such as ionomer resin; epoxy resin, polyester, styrene-butadiene copolymer, polyvinylpyrrolidone, Examples thereof include a methyl vinyl ether-maleic anhydride copolymer, a maleic acid-modified phenol resin, and a phenol-modified terpene resin, and two or more of them may be used in combination.

The colorant (pigment or dye) is not particularly limited, but Cadmium Yellow, Mineral Fast Yellow, Nickel Titanium Yellow, Nabres Yellow, Naftor Yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow GR, Kinolin Yellow Lake, Yellow pigments such as permanent yellow NCG and tartrazine lake; orange pigments such as molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indance lem brilliant orange RK, benzidine orange G, indance lem brilliant orange GK; red iron oxide, cadmium Red pigments such as Red, Permanent Red 4R, Resole Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamin Lake B, Alizarin Lake, Brilliant Carmine 3B; Fast Violet B, Methyl Violet Lake Purple pigments such as cobalt blue, alkaline blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, indanslen blue BC and other blue pigments; chrome green, chromium oxide, pigment Green pigments such as Green B and Malakite Green Lake; azine pigments such as carbon black, oil furnace black, channel black, lamp black, acetylene black and aniline black, metal salt azo pigments, metal oxides, composite metal oxides, etc. Examples include black pigments, and two or more of them may be used in combination.

The release agent is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters, paraffin wax, amide wax, polyhydric alcohol wax, silicone varnish, carnauba wax, and ester wax. , Two or more types may be used together.

In addition, the toner may further contain a charge control agent. The charge control agent is not particularly limited, but is niglosin; an azine dye having an alkyl group having 2 to 16 carbon atoms (see Japanese Patent Publication No. 42-1627); I. Basic Yellow 2 (CI 41000), C.I. I. Basic Yellow 3, C.I. I. Basic Red 1 (CI 45160), C.I. I. Basic Red 9 (CI 42500), C.I. I. Basic Violet 1 (CI 42535), C.I. I. Basic Violet 3 (CI 42555), C.I. I. Basic Violet 10 (CI 45170), C.I. I. Basic Violet 14 (CI 42510), C.I. I. Basic Blue 1 (CI 42025), C.I. I. Basic Blue 3 (CI 51005), C.I. I. Basic Blue 5 (CI 42140), C.I. I. Basic Blue 7 (CI 42595), C.I. I. Basic Blue 9 (CI 52015), C.I. I. Basic Blue 24 (CI 52030), C.I. I. Basic Blue25 (CI52025), C.I. I. Basic Blue 26 (CI44045), C.I. I. Basic Green 1 (CI 42040), C.I. I. Basic dyes such as Basic Green 4 (CI 42000); rake pigments of these basic dyes; C.I. I. Quadruple ammonium salts such as Solvent Black 8 (CI 26150), benzoylmethylhexadecylammonium chloride, decyltrimethyl chloride; dialkyltin compounds such as dibutyl and dioctyl; dialkyltinborate compounds; guanidine derivatives; vinyls with amino groups Polyamine resins such as based polymers and condensed polymers having an amino group; described in Japanese Patent Publication No. 41-20153, Japanese Patent Publication No. 43-27596, Japanese Patent Publication No. 44-6397, and Japanese Patent Publication No. 45-26478. Metal complex salts of monoazo dyes; Sartylic acid described in Japanese Patent Publication No. 55-42752, Japanese Patent Publication No. 59-7385; Zn, Al, Co, Cr, Fe, etc. of dialkylsartylic acid, naphthoic acid, dicarboxylic acid, etc. Metal complexes; sulfonated copper phthalocyanine pigments; organic boron salts; fluorine-containing quaternary ammonium salts; calix-allene compounds and the like, but two or more of them may be used in combination. For color toners other than black, a metal salt of a white salicylic acid derivative or the like is preferable.

The external additive is not particularly limited, but is an inorganic particle such as silica, titanium oxide, alumina, silicon carbide, silicon nitride, or boron nitride; a poly having an average particle size of 0.05 to 1 μm obtained by a soap-free emulsion polymerization method. Examples thereof include resin particles such as methyl methacrylate particles and polystyrene particles, and two or more of them may be used in combination. Of these, metal oxide particles such as silica and titanium oxide whose surface is hydrophobized are preferable. Furthermore, by using silica that has been hydrophobized and titanium oxide that has been hydrophobized in combination, and by increasing the amount of titanium oxide that has been hydrophobized compared to silica that has been hydrophobized, it is possible to deal with humidity. A toner having excellent charge stability can be obtained.

The replenishing developer of the present invention contains a carrier and toner, and the carrier is the carrier of the present invention.
By applying the replenishing developer of the present invention to an image forming apparatus that forms an image while discharging excess developing agent in the developing apparatus, stable image quality can be obtained for an extremely long period of time. That is, the deteriorated carriers in the developing apparatus and the non-deteriorated carriers in the replenishing developing agent are replaced to keep the charge amount stable for a long period of time, and a stable image can be obtained. This method is particularly effective when printing a high image area. When printing a high image area, the carrier charge deterioration due to the toner spent on the carrier is the main carrier deterioration. However, by using this method, the carrier replenishment amount increases when the image area is high, so that the deteriorated carriers are replaced. The frequency goes up. As a result, a stable image can be obtained over an extremely long period of time.
The mixing ratio of the replenishing developer is preferably 2 to 50 parts by mass of toner with respect to 1 part by mass of the carrier. When the amount of toner is less than 2 parts by mass, the amount of replenished carriers is too large, the carrier supply is excessive, and the carrier concentration in the developing apparatus becomes too high, so that the charged amount of the developer tends to increase. Further, as the amount of charge of the developer increases, the developing ability decreases and the image density decreases. On the other hand, if it exceeds 50 parts by mass, the carrier ratio in the replenishing developer is reduced, so that the carriers in the image forming apparatus are less replaced, and the effect on carrier deterioration cannot be expected.

The image forming apparatus of the present invention includes an electrostatic latent image carrier, a charging means for charging the electrostatic latent image carrier, and an exposure means for forming an electrostatic latent image on the electrostatic latent image carrier. A developing means for developing a toner image by developing an electrostatic latent image formed on the electrostatic latent image carrier with the two-component developer of the present invention, and an electrostatic latent image carrier formed on the electrostatic latent image carrier. It has a transfer means for transferring the toner image to a recording medium and a fixing means for fixing the toner image transferred to the recording medium.
Further, the image forming method of the present invention includes a step of forming an electrostatic latent image on an electrostatic latent image carrier and a two-component development of the electrostatic latent image formed on the electrostatic latent image carrier. A step of developing with an agent to form a toner image, a step of transferring the toner image formed on the electrostatic latent image carrier to a recording medium, and a step of fixing the toner image transferred to the recording medium. Has a process.
The configuration of the image forming apparatus and method used in the present invention is not limited to the above-described embodiment, and an image forming apparatus and method having another configuration can be used as long as it has the same function. It is also possible to adopt it.

FIG. 2 shows an example of the process cartridge of the present invention. The process cartridge (10) has a photoconductor (11) as an electrostatic latent image carrier, a charging device (12) for charging the photoconductor (11), and an electrostatic latent image formed on the photoconductor (11). After transferring the toner image formed on the developing apparatus (13) and the photoconductor (11) that develops with the developer of the present invention to form a toner image to a recording medium, it remains on the photoconductor (11). A cleaning device (14) for removing the toner is integrally supported, and the process cartridge (10) is removable from the main body of an image forming device such as a copying machine or a printer.

Hereinafter, a method of forming an image using an image forming apparatus equipped with a process cartridge (10) will be described. First, the photoconductor (11) is rotationally driven at a predetermined peripheral speed, and the peripheral surface of the photoconductor (11) is uniformly charged to a positive or negative predetermined potential by the charging device (12). Next, exposure light is irradiated to the peripheral surface of the photoconductor (11) from an exposure device (not shown) such as a slit exposure type exposure device or an exposure device that scans and exposes with a laser beam, and an electrostatic latent image is sequentially formed. To. Further, the electrostatic latent image formed on the peripheral surface of the photoconductor (11) is developed by the developing apparatus (13) using the developer of the present invention to form a toner image. Next, the toner image formed on the peripheral surface of the photoconductor (11) is synchronized with the rotation of the photoconductor (11), and is synchronized with the rotation of the photoconductor (11) from the paper feed unit (not shown) to the photoconductor (11) and the transfer device (not shown). ) Are sequentially transferred to the transfer paper which is the recording medium fed between). Further, the transfer paper on which the toner image is transferred is separated from the peripheral surface of the photoconductor (11), introduced into a fixing device (not shown), fixed, and then used as a copy of the image forming device. It is printed out to the outside. On the other hand, the surface of the photoconductor (11) after the toner image is transferred is cleaned by removing the residual toner by the cleaning device (14), and then statically removed by the static eliminator (not shown), and repeated. Used for image formation.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In addition, "part" represents a mass part.

(Core manufacturing method)
MnCO ₃ , Mg (OH) ₂ , and Fe ₂ O ₃ powders were weighed and mixed to obtain a mixed powder. This mixed powder was calcined in an air furnace at 900 ° C. for 3 hours in an air atmosphere, and the obtained calcined product was cooled and then pulverized to obtain a powder having a diameter of about 1 μm. This powder was added with 1% by mass of a dispersant together with water to form a slurry, and this slurry was supplied to a spray dryer for granulation to obtain granulated products having an average particle size of about 40 μm. This granulated product was loaded into a baking furnace and baked in a nitrogen atmosphere at 1250 ° C. for 5 hours. After crushing the obtained fired product with a crusher, the particle size was adjusted by sieving to obtain spherical ferrite particles C1 having a volume average particle size of about 35 μm.
The volume average particle size was set to a material refractive index of 2.42, a solvent refractive index of 1.33, and a concentration of about 0.06 in water using the Microtrack particle size distribution meter model HRA9320-X100 (manufactured by Nikkiso Co., Ltd.). Was measured.

(Production Example 1 of Conductive Fine Particles)
1 liter of water was heated to 65 ° C., and 10.3 g of ferric chloride and 0.08 g of sodium tungstate were dissolved in 1.7 liters of 2N hydrochloric acid, and 12 mass% ammonia water was added as a suspension. The mixture was added dropwise over 12 minutes so that the pH became 7 to 8. After the dropping, the suspension was filtered and washed, and the obtained cake was dried at 110 ° C. The dry powder was then treated in a nitrogen stream at 500 ° C. for 1 hour.
The obtained fired product is pulverized, and 4% by mass of vinyltriethoxysilane (VTES) is added and treated with stirring in a Henschel mixer heated to 70 ° C. Further, the treated product was heat-treated at 100 ° C. for 1 hour to obtain conductive fine particles P1 having an average particle size of 40 nm and a powder specific resistance of 5.0 Ω · cm.
The average particle size was measured using Nanotrack UPA-EX150 (manufactured by Nikkiso Co., Ltd.) in water with a material refractive index of 1.66 and a solvent refractive index of 1.33.
For the powder resistivity of the conductive fine particles, 5 g of the sample powder ^{was compression-molded at 10 kg / cm 2} , and then an LCR meter AR-480D manufactured by Keisei Co., Ltd. was connected to measure the resistance value. At the same time, the thickness of the sample at that time was measured and converted into the powder resistivity value.

(Production Example 2 of Conductive Fine Particles)
In the conductive fine particle production example 1, 12.8 g of stannic chloride, 0.10 g of sodium tungstate, and the same as P1 except that the dropping time was 15 minutes, the average particle size was 50 nm, and the powder resistivity was 4. Conductive fine particles P2 of 5 Ω · cm were obtained.

(Production Example 3 of Conductive Fine Particles)
In the conductive fine particle production example 1, 25.7 g of stannic chloride, 0.20 g of sodium tungstate, and the dropping time was set to 30 minutes in exactly the same manner as in P1, with an average particle size of 100 nm and a powder resistivity. Conductive fine particles P3 of 2 Ω · cm were obtained.

(Production Example 4 of Conductive Fine Particles)
3. In the conductive fine particle production example 1, 77.0 g of stannic chloride, 0.60 g of sodium tungstate, and the same as P1 except that the dropping time was 90 minutes, the average particle size was 300 nm, and the powder resistivity was 4. Conductive fine particles P4 of 9 Ω · cm were obtained.

(Production Example 5 of Conductive Fine Particles)
In Production Example 1 of Conductive Fine Particles, the average particle size was 330 nm, the powder resistivity was 5. Conductive fine particles P5 of 4 Ω · cm were obtained.

(Example 6 of Production of Conductive Fine Particles)
In the conductive fine particle production example 3, the average particle size is 100 nm and the powder resistivity is 12.1 Ω · cm in exactly the same manner as P3 except that vinyltriethoxysilane is changed to n-octyltriethoxysilane (n-OTES). Conductive fine particles P6 were obtained.

(Production Example 7 of Conductive Fine Particles)
In the conductive fine particle production example 3, the average particle size is 100 nm and the powder resistivity is 11.4 Ω · cm in exactly the same manner as P3 except that vinyl triethoxysilane is changed to p-styryltrimethoxysilane (p-STMS). Conductive fine particles P7 were obtained.

(Comparative Example 1 for Production of Conductive Fine Particles)
In Example 3 of Production of Conductive Fine Particles, conductive fine particles P1'with an average particle size of 100 nm and a powder specific resistance of 4.3 Ω · cm were obtained in exactly the same manner as in P3 except that no surface treatment was performed.

(Production Example 8 of Conductive Fine Particles)
100 g of aluminum oxide (AKP-30 manufactured by Sumitomo Chemical Co., Ltd.) was dispersed in 1 liter of water to form a suspension, and this solution was heated to 65 ° C. In the suspension, 12.8 g of stannic chloride and 0.10 g of sodium tungstate were dissolved in 1.7 liters of 2N hydrochloric acid, and 12 mass% aqueous ammonia was added so that the pH of the suspension was 7 to 8. Was added dropwise over 15 minutes. After the dropping, the suspension was filtered and washed, and the obtained cake was dried at 110 ° C. The dry powder was then treated in a nitrogen stream at 500 ° C. for 1 hour.
The obtained fired product is pulverized, and 4% by mass of vinyltriethoxysilane is added and treated with stirring in a Henschel mixer heated to 70 ° C. Further, the treated product was heat-treated at 100 ° C. for 1 hour to obtain conductive fine particles P8 having an average particle size of 330 nm and a powder specific resistance of 8.1 Ω · cm.

[Carrier Manufacturing Example 1]
(Carrier coating layer)
-Silicone resin solution [solid content 20% by mass (SR2410: manufactured by Toray Dow Corning Silicone)] 648 parts-Titanium catalyst [solid content 60% by mass (TC-750: manufactured by Matsumoto Fine Chemical Co., Ltd.)] 4 parts by mass-aminosilane [Solid content 100% by mass (SH6020: manufactured by Toray Dow Corning Silicone Co., Ltd.)] 3.2 parts, 110 parts of conductive fine particles P1 and 1000 parts of toluene are dispersed for 10 minutes with a homomixer, and the acrylic resin and silicone resin are mixed. A coating film forming solution was obtained. Using 1: 5000 parts of C as the core material, the coating film forming solution was applied to the surface of the core material with a spira coater (manufactured by Okada Seiko Co., Ltd.) at a temperature inside the coater at 55 ° C. and dried. .. The obtained carrier was left in an electric furnace at 200 ° C. for 1 hour for firing.
After cooling, the ferrite powder bulk was crushed using a sieve having a mesh size of 63 μm to obtain a carrier 1 having a volume average particle size of 36 μm and a volume resistivity of 13.2 (LogΩ · cm).
The volume average particle size was set to a material refractive index of 2.42, a solvent refractive index of 1.33, and a concentration of about 0.06 in water using the Microtrack particle size distribution meter model HRA9320-X100 (manufactured by Nikkiso Co., Ltd.). Was measured.

The volume resistivity is obtained from the fluororesin container (2) in which the electrodes (1a) and electrodes (1b) having a surface area of 2.5 cm × 4 cm are housed at a distance of 0.2 cm using the cell shown in FIG. The cell is filled with the carrier (3), and after tapping 10 times with a drop height of 1 cm and a tapping speed of 30 times / minute, a DC voltage of 1000 V is applied between the electrodes (1a) and (1b). The resistivity value r [Ω] 30 seconds after the application was measured using a high resistance meter 4329A (manufactured by Yokogawa Hulett Packard), and the volume resistivity [Ω · cm] was calculated from the following equation (2). did.

(Carrier Manufacturing Example 2)
Carrier Production In Example 1, a carrier 2 having a volume average particle diameter of 36 μm and a volume resistivity of 13.1 LogΩ · cm was obtained in exactly the same manner as the carrier 1 except that P2 was made 110 parts as conductive fine particles.

(Carrier Manufacturing Example 3)
Carrier Production In Example 1, a carrier 3 having a volume average particle diameter of 36 μm and a volume resistivity of 13.1 LogΩ · cm was obtained in exactly the same manner as in the carrier 1, except that P3 was 110 parts as conductive fine particles.

(Carrier Manufacturing Example 4)
Carrier Production In Example 1, a carrier 4 having a volume average particle diameter of 36 μm and a volume resistivity of 13.3 LogΩ · cm was obtained in exactly the same manner as in the carrier 1, except that P4 was 110 parts as conductive fine particles.

(Carrier Manufacturing Example 5)
Carrier Production In Example 1, a carrier 5 having a volume average particle diameter of 36 μm and a volume resistivity of 13.2 LogΩ · cm was obtained in exactly the same manner as in the carrier 1 except that P5 was 110 parts as conductive fine particles.

(Carrier Manufacturing Example 6)
Carrier Production In Example 1, a carrier 6 having a volume average particle diameter of 36 μm and a volume resistivity of 13.5 LogΩ · cm was obtained in exactly the same manner as the carrier 1 except that P6 was 110 parts as conductive fine particles.

(Carrier Manufacturing Example 7)
Carrier Production In Example 1, a carrier 7 having a volume average particle diameter of 36 μm and a volume resistivity of 13.5 LogΩ · cm was obtained in exactly the same manner as the carrier 1 except that P7 was 110 parts as conductive fine particles.

(Carrier Manufacturing Comparative Example 1)
Carrier Production In Example 1, a carrier 1'with a volume average particle diameter of 36 μm and a volume resistivity of 13.1 LogΩ · cm was obtained in exactly the same manner as the carrier 1 except that P1'was made 110 parts as conductive fine particles. ..

(Carrier Manufacturing Example 8)
Carrier Production In Example 1, a carrier 8 having a volume average particle diameter of 36 μm and a volume resistivity of 13.3 LogΩ · cm was obtained in exactly the same manner as in the carrier 1, except that P8 was 110 parts as conductive fine particles.
Table 1 shows the obtained carrier physical characteristics.

(Toner manufacturing example)
[Synthesis example of polyester resin A]
Put 443 parts of PO adduct (hydroxyl value 320) of bisphenol A, 135 parts of diethylene glycol, 422 parts of terephthalic acid and 2.5 parts of dibutyltin oxide in a reaction vessel equipped with a thermometer, agitator, a cooler and a nitrogen introduction tube. Then, the reaction was carried out at 200 ° C. until the acid value became 10, to obtain [polyester resin A]. The Tg of this resin was 63 ° C., and the peak number average molecular weight was 6000.

[Synthesis example of polyester resin B]
Put 443 parts of PO adduct (hydroxyl value 320) of bisphenol A, 135 parts of diethylene glycol, 422 parts of terephthalic acid and 2.5 parts of dibutyltin oxide in a reaction vessel equipped with a thermometer, agitator, a cooler and a nitrogen introduction tube. Then, the reaction was carried out at 230 ° C. until the acid value became 7, to obtain [polyester resin B]. The Tg of this resin was 65 ° C., and the peak number average molecular weight was 16000.

[Manufacturing of parent toner particles 1]
・ Polyester resin A ・ ・ ・ ・ 40 parts ・ Polyester resin B ・ ・ ・ ・ 60 parts ・ Carnauba wax ・ ・ ・ ・ 1 part ・ Carbon black (# 44 manufactured by Mitsubishi Chemical Co., Ltd.) ・ ・ ・ ・ 15 parts The above toner composition The materials are mixed with a Henschel mixer (Henschel 20B manufactured by Mitsui Mining Co., Ltd. at 1500 rpm for 3 minutes) and kneaded with a uniaxial kneader (small bus co-kneader manufactured by Buss) under the following conditions (set temperature). : Feed amount: 2 kg / Hr) and [maternal toner A1] were obtained at an inlet portion of 100 ° C. and an outlet portion of 50 ° C.

Further, the [matrix toner A1] is kneaded, rolled and cooled, crushed with a pulperizer, and further, an I type mill (IDS-2 type manufactured by Nippon Pneumatic Co., Ltd., using a flat type collision plate, air pressure: 6.8 atm). Fine pulverization was performed at / cm ² and feed amount: 0.5 kg / hr), and further classification was performed (132 MP manufactured by Alpine Co., Ltd.) to obtain [maternal toner particles 1].

(External agent treatment)
To 100 parts of "maternal toner particles 1", 1.0 part of hydrophobic silica fine particles (R972: manufactured by Nippon Aerosil Co., Ltd.) was added as an external additive and mixed with a Henshell mixer to obtain toner particles (hereinafter, "toner"). 1 ").

[Preparation of developers 1-8, 1']
7.0 parts of toner 1 (7.2 μm) obtained in the toner production example was added to the carriers 1 to 8 and 1'(93 parts) obtained in the carrier production example, and the mixture was stirred with a ball mill for 20 minutes. The developers 1 to 8 and 1'were prepared.

[Developer characteristic evaluation]
Using the obtained developer, image evaluation was performed using Ricoh Pro C901 (Ricoh digital color copier / printer multifunction device) manufactured by Ricoh in an environment of a temperature of 40 ° C. and a humidity of 70%. Specifically, first, using the developing agents 1 to 8 and 1'of Examples and Comparative Examples, printing was performed up to 1 million sheets running at an image area ratio of 20%, and various evaluations were performed.

(1) Amount of change in volume resistivity The initial carrier volume resistivity (LogR1) is a common logarithmic value of the carrier volume resistivity measured in the same manner as the above [volume resistivity]. The volume resistivity (LogR2) of the carrier after running 1 million sheets was measured in the same manner as above except that the carrier from which the toner of each color in the developer after running was removed was used by using a blow-off device.
The volume resistivity difference (LogR2-LogR1) between the initial stage and after printing 1 million sheets was evaluated according to the following criteria.
0 or more and less than 0.2: ○ (good)
0.2 or more and less than 0.5: △ (usable)
0.5 or more: × (defective)

(2) Adhesion of edge carriers When adhesion of carriers occurs, it causes scratches on the photoconductor drum and the fixing roller, resulting in deterioration of image quality. Even if carriers adhered to the photoconductor, only some of the carriers were transferred to the paper, so the evaluation was performed by the following method.
After printing 1 million sheets, the image (10 mm) of Ricoh Pro C901 under the developing conditions (charging potential (Vd): -700V, potential after exposure of the part corresponding to the image part (edge part): -200V, development bias: DC-500V). The number of carriers adhering to (the edge portion of a solid image of × 10 mm) was counted on the photoconductor to evaluate the adhering edge carriers.
The symbols in the table are: ○: good, Δ: usable, ×: defective.

(3) Toner scattering After printing 1 million sheets, the state of toner scattered from the developing section to the outside of the developing section was visually evaluated according to the following criteria.
No scattering or slight toner adhering to the outside of the developing area: ○ (good)
Toner adheres to the developing part, but does not scatter outside the machine: △ (usable)
Scattered outside the machine: × (defective)

The results of each of the above evaluations are shown in Table 2.

From the results in Table 2, the carrier of the present invention of the example is superior in volume resistivity change amount, edge carrier adhesion, and toner scattering as compared with the comparative example, and exhibits high image quality and high durability even under high temperature and high humidity. I found out.

1a Electrode 1b Electrode 2 Fluororesin container 3 Carrier 10 Process cartridge 11 Photoreceptor 12 Charging device 13 Developing device 14 Cleaning device

JP-A-55-127569 Japanese Unexamined Patent Publication No. 55-157751 Japanese Patent Application Laid-Open No. 56-140358 Japanese Unexamined Patent Publication No. 57-96355 Japanese Unexamined Patent Publication No. 57-96356 Japanese Unexamined Patent Publication No. 58-207054 Japanese Unexamined Patent Publication No. 61-110161 Japanese Unexamined Patent Publication No. 62-273576 Japanese Unexamined Patent Publication No. 2001-343790 Japanese Unexamined Patent Publication No. 2007-17838 Japanese Unexamined Patent Publication No. 2015-179258

Claims (8)

A carrier having a core and a coating layer covering the core.
The coating layer contains conductive fine particles and contains
The carrier, wherein the conductive fine particles contain tungsten-doped tin oxide that has been surface-treated with any one selected from vinyltriethoxysilane, n-octyltriethoxysilane, and p-styryltrimethoxysilane. The carrier according to claim 1, wherein the primary particle size of the tungsten-doped tin oxide is 50 nm to 300 nm. A two-component developer comprising the carrier and toner according to claim 1 or 2. The two-component developer according to claim 3, wherein the toner is a color toner. A replenishing developer containing a carrier and toner, which contains 2 to 50 parts by weight of the toner with respect to 1 part by mass of the carrier, and the carrier is the carrier according to any one of claims 1 to 4. A replenishing developer characterized by. An electrostatic latent image carrier, a charging means for charging the electrostatic latent image carrier, an exposure means for forming an electrostatic latent image on the electrostatic latent image carrier, and an electrostatic latent image carrier. A developing means for developing a toner image by developing the electrostatic latent image formed in the above using the two-component developer according to claim 3 or 4, and a toner image formed on the electrostatic latent image carrier. An image forming apparatus comprising: a transfer means for transferring a toner image to a recording medium, and a fixing means for fixing a toner image transferred to the recording medium. The second aspect of claim 3 or 4, wherein the electrostatic latent image carrier, the charging member for charging the surface of the electrostatic latent image carrier, and the electrostatic latent image formed on the electrostatic latent image carrier are described in claim 3 or 4. A process cartridge characterized by having a developing unit for developing with a component developer and a cleaning member for cleaning the electrostatic latent image carrier. The step of forming an electrostatic latent image on the electrostatic latent image carrier and the electrostatic latent image formed on the electrostatic latent image carrier are subjected to the two-component developer according to claim 3 or 4. It includes a step of developing to form a toner image, a step of transferring the toner image formed on the electrostatic latent image carrier to a recording medium, and a step of fixing the toner image transferred to the recording medium. An image forming method characterized by the fact that.

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