JPH0915878A - Image forming method - Google Patents

Abstract

PURPOSE: To provide an image forming method using an organic photoreceptor and a two-component developer containing carrier and toner in which image quality can be satisfactorily held even when image formation is performed in large quantities. CONSTITUTION: In an image forming method for repeating processes of charging, image exposure, development, transfer and cleaning by use of an organic photoreceptor to form a number of images, the photoreceptor has a charge generating layer and a plurality of charge transfer layers laminated thereon on a conductive support body, the charge transfer layer on a top surface layer contains an inorganic particle, a two-component developer consisting of carrier and toner is used for development, and a space (DsD) between a developer layer support body and the photoreceptor in developing area is 300-1000μm, and the space between the developer layer support body and a developer layer regulating plate (Hcut plate) is narrower than it by 0-200μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming method used in an image forming process of a copying machine, a printer, etc.
It relates to a combination of developing conditions.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming method, a developing method using a two-component developer consisting of a toner and a carrier after forming an electrostatic latent image on a photosensitive member uses a magnetic toner. It is widely used as well as the developing method using a component developer. The developing method using a two-component developer is superior to the developing method using a one-component developer in charge controllability for toner and is widely used from low speed machines to high speed machines. There are the following problems in the developing method using.

That is, in recent years, as an electrophotographic photoreceptor, an organic electrophotographic photoreceptor having a wide selection of materials instead of an inorganic photoreceptor such as selenium and excellent in environmental suitability has come to occupy the mainstream. However, when an image is formed with a combination of an organic photoconductor and a two-component developer, the initial image is good, but since the photoconductor wears at a high rate, the image tends to deteriorate, and tens of thousands to hundreds of thousands of images are generated. In the fields of medium- and high-speed copying machines and printers that perform image formation, image quality has gradually deteriorated.

In particular, in the case of an insulating carrier having a high electric resistance as a carrier, in order to obtain a desired image density, the distance (Dsd) between the developer layer carrier and the photoreceptor in the developing region, the developer layer carrier and the developer layer. It is necessary to adjust the requirements governing the development conditions such as the distance from the regulation plate (Hcut plate) in μm units. However, in the conventional organic photoconductors in which the photoconductor is greatly worn and is likely to be scratched, even if these distances are strictly adjusted, the optimum conditions are immediately displaced and the image quality tends to be deteriorated.

On the other hand, as a method for increasing the surface hardness of the photoconductor and improving the susceptibility of the photoconductor to scratches, JP-A-59-22 has
No. 3443 discloses a photoconductor in which a metal oxide fine powder is not contained in a protective layer. However, providing a protective layer on the photosensitive layer causes a decrease in the sensitivity of the photoconductor and an increase in residual charge, and the image quality deteriorates when images are repeatedly formed. On the other hand, JP-A-60-57847 discloses a photoconductor in which colloidal silica particles are added to a photosensitive layer. However, when colloidal silica is used, uniform dispersion in a binder is difficult, The effect of scratch resistance is not always sufficient. Further, Japanese Patent Application Laid-Open No. 61-163345 discloses a photoconductor containing silica particles or the like in the entire charge transport layer of the photoconductor. There is another problem that the amount of light scattering increases, resulting in a blurred image with reduced resolution, which is not a sufficient solution.

[0006]

The present invention provides an image forming method using an organic photoconductor, which maintains good image quality even when a large amount of images are formed. Another object of the present invention is to provide an image forming method using a two-component developer containing a carrier and a toner, which maintains good image quality even when a large amount of images are formed.

[0007]

The object of the present invention can be achieved by adopting the following constitution.

[1] Using an organic photoreceptor, charging, image exposure,
In an image forming method of forming a large number of images by repeating development, transfer and cleaning steps, a photoreceptor has a charge generation layer on a conductive support and a plurality of charge transport layers laminated on the charge generation layer. In addition, the outermost surface charge transport layer contains inorganic particles, a two-component developer consisting of a carrier and a toner is used for development, and the distance (Dsd) between the developer layer carrier and the photoconductor in the development region is 300. The image forming method is characterized in that the gap between the developer layer carrier and the developer layer regulating plate (Hcut plate) is narrower than the above by 0 to 200 μm.

[2] The image forming method as described in [1], wherein the inorganic particles are inorganic particles having a Mohs hardness of 5 or more and a volume average particle diameter of 0.05 to 2 μm.

[3] The carrier has an electric resistance value of 10
The image forming method according to [1], which is an insulating carrier having a resistance of ¹² Ω · cm or more.

[4] The photoreceptor has a Mohs hardness of the outermost surface layer of 5 or more and contains spherical inorganic particles, and the film strength of the photosensitive layer is 20 using a diamond needle having a tip radius of 0.3 mm.
Depth of scratch when vertical load of 0g is applied 0.1μm-1μ
The image forming method as described in [1], [2] or [3], wherein the image forming method is an organic electrophotographic photosensitive member of m.

The present invention solves the problems of the image forming method using a combination of a two-component developer comprising an organic photoreceptor and a toner and a carrier.

The layer structure of the photoconductor used in the present invention has what is called a plurality of charge transport layers, and the plurality of charge transport layers are formed on a conductive support provided with a charge generation layer. . The second charge-transporting layer forms the outermost surface layer of the photoconductor, and by containing inorganic particles and a charge-transporting substance, increase in residual potential and decrease in sensitivity due to repeated use of the photoconductor. Can be prevented.

FIG. 1 is a schematic sectional view showing the relationship between the photoconductor 10 and the developing device 13 in the present invention. The developer 40 is agitated by the agitator 6, and the toner and the carrier are frictionally charged and fed to the developer layer carrier 3 while being charged. Further, by the rotation of the developer layer carrier 3 in the direction of the arrow and the action of the built-in NS bipolar magnets 4, the Hcut plate (developer layer regulating plate) 5 is fed. Here, the developer is regulated to have a predetermined layer thickness and is conveyed in the direction of the photoconductor 10, and is conveyed to the region (developing region) where the gap between the developer layer carrier 3 and the photoconductor 10 is the narrowest for development.

The interval (Dsd) between the developer layer carrying member and the photosensitive member in the developing region is 1 in FIG. 1, and the interval between the developer layer carrying member and the developer layer regulating plate (Hcut plate). And refers to 2.

In the present invention, 1 is 300 to 1000 μm, 2
Is narrower than that by 0 to 200 μm. 1
If (Dsd) is narrower than this range, a proper development density cannot be obtained, and streak-like defects may occur on the screen. However, if it is wider than this range, the image quality is deteriorated, such as resolution and uneven development density. On the other hand, if 2 is less than this range, the maximum image density is lowered, and if it is more than this range, an appropriate development density cannot be obtained, and streaky defects may occur on the screen.

Reference numeral 7 is an adjusting roller for keeping the amount of the developer toward the Hcut plate substantially constant, and 8 is a scraper for temporarily separating the developed developer layer from the developer layer carrier 3.

Further, the developer layer regulating plate (Hc
The ut plate) is not particularly limited in terms of material as long as it reliably regulates the developer layer and has durability, but a metal plate such as aluminum, true chew or stainless steel is preferable in terms of strength.

(Construction of Carrier of the Present Invention) The carrier used in the present invention is not particularly limited, but a coated carrier in which core particles are coated with a resin is desirable.

The resin for coating in the present invention is not particularly limited, and a material having high resistance can be used. Specifically, styrene, styrenes such as α-methylstyrene, methacrylic acid or acrylic acid derivatives such as methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, cyclohexyl methacrylate, ethylene, propylene, etc. Olefins,
Vinyl carboxylic acids such as vinyl acetate and vinyl benzoate,
Vinyl-based polymers composed of halogen-based monomers such as vinylidene fluoride and tetrafluoroethynylene, halogen-containing acrylic acid or methacrylic acid derivatives such as tetrafluoropropyl methacrylate and pentafluoropropyl methacrylate (these are A polymer or a homopolymer).

The coating film thickness of the resin is preferably 0.1 to 10.0 μm, more preferably 0.5 to 5.0 μm.
When this film thickness is thin, the resistance value decreases, and when the film thickness is excessive, it becomes difficult to hold this film uniformly, causing the coating resin to be released and causing problems such as image fog. To occur.

The volume resistivity is preferably 10 ¹² Ω · cm or more, and the upper limit is preferably 10 ¹⁵ Ω · cm or less, but this value indicates a value measured by static resistance. Specifically, it is determined from the resistance between the carrier layers under the load of 200 g / cm ² and the electric field of 1000 V / cm using the following calculation formula. The measurement environment is 20 ° C./50% RH.

Volume resistivity (Ω · cm) = (R × S) / t Here, R represents resistance (Ω), S represents cross-sectional area (cm ² ) of the carrier sample, and t represents carrier sample. Thickness (c
m).

As the magnetic particles serving as nuclei constituting the carrier, any particles having ferromagnetism such as iron, Cu-Zn ferrite, Cu-Mg ferrite and magnetite can be used. The magnetic particles have a volume average particle diameter of 30 to 200 μm, preferably 35 to 150 μm.

In the present invention, the method for producing the carrier is not particularly limited, and a solution of the resin in a solvent is sprayed onto the core particles of the carrier and dried to coat the core particles with the resin. Or a method of mixing the core particles of the carrier and the fine particles of the coating resin, then a method of coating by applying a mechanical impact force, further after mixing the carrier core particles with the coating resin particles, heat is added There is a method of coating. Further, a method of laminating and coating resin layers is also a preferably used method.

(Construction of Toner) The toner contains a binder resin, a colorant and, if necessary, other additives. The binder resin that constitutes the toner is not particularly limited, and various conventionally known resins can be used. For example, styrene resin, acrylic resin, styrene / acrylic resin, polyester resin, etc. may be mentioned. The colorant that constitutes the toner is not particularly limited, and various conventionally known materials are used. For example, carbon black, nigrosine dye, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red,
Examples include quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, and rose bengal. Examples of other additives include charge control agents such as salicylic acid derivatives and azo-based metal complexes, and fixing improvers such as low molecular weight polyolefins and carnauba wax.

Further, from the viewpoint of imparting fluidity, inorganic fine particles may be added to the colored particle toner. As the inorganic fine particles, inorganic oxide particles such as silica, titania, and alumina are preferable, and further, these inorganic fine particles are preferably hydrophobized with a silane coupling agent, a titanium coupling agent, or the like.

The particle size of the toner is 5 to 15 in terms of volume average particle size.
μm A particularly preferable range is 6.0 to 10.0 μm.

(Construction of Photoreceptor) As the inorganic particles contained in the outermost surface layer of the electrophotographic photoreceptor of the present invention, it is necessary to increase the film strength and to have strength itself, so that the Mohs hardness is 5 or more. It is considered as particles and does not adversely affect the electrophotographic performance.

Examples of such inorganic particles include oxides such as cerium oxide, chromium oxide, aluminum oxide, magnesium oxide, silicon oxide, tin oxide, zirconium oxide, iron oxide and titanium oxide; calcium sulfate, barium sulfate and sulfuric acid. Sulfates such as aluminum; silicates such as calcium silicate and magnesium silicate; nitrides such as boron nitride and titanium nitride; silicon carbide, titanium carbide,
Carbides such as boron carbide, tungsten carbide, and zirconium carbide; borides such as zirconium boride and titanium boride, and the like can be used, and one of these can be used, or two or more can be used as necessary.

The inorganic particles have a volume average particle size of 0.05 to
2.0 μm, preferably a ratio of major axis / minor axis of 2.0
Less than substantially spherical particles.

The volume average particle diameter of the inorganic particles is 0.05 μm.
If it is less than m, sufficient mechanical strength of the surface of the photoreceptor cannot be obtained, and the surface area of the particles becomes large. As a result, the amount of adsorbed water increases and the surface of the photoreceptor wears and is damaged during repeated image formation, resulting in electron Photo performance deteriorates. On the other hand, if it exceeds 2.0 μm, the surface roughness of the photoconductor becomes large, and the cleaning blade is worn or damaged to deteriorate the cleaning characteristics, resulting in poor cleaning and easy occurrence of image blur.

The inorganic particles being substantially spherical means that the surface shape can be distinguished by an electron microscope (diameter 1 to 10 mm).
When the particles are expanded to, the particles are not indefinite and are considered to be spherical with the major axis / minor axis ratio of less than 2.0. In that case, the wear coefficient of the surface of the photoconductor can be reduced. These effects cannot be expected for conventionally used inorganic fine particles, that is, for inorganic particles of less than 0.05 μm. The volume average particle size of the inorganic particles is measured by a laser diffraction / scattering particle size distribution measuring device LA-700 (manufactured by Hikiba Seisakusho).

The inorganic particles are preferably hydrophobized with a hydrophobizing agent such as a titanium coupling agent, a silane coupling agent, a polymeric fatty acid or a metal salt thereof.

Examples of the titanium coupling agent include tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzene sulfonyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate and the like. Further, as the silane coupling agent, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltri Methoxysilane,
Examples thereof include dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane and the like.

The fatty acids include undecyl acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid,
Long-chain fatty acids such as pentadecanoic acid, stearic acid, heptadecanoic acid, arachidic acid, montanic acid, oleic acid, linoleic acid, and arachidonic acid are mentioned, and their metal salts are zinc, iron, magnesium, aluminum, calcium, sodium, lithium. Salts with metals such as.

These compounds are preferably added in an amount of 1 to 10% by weight with respect to the above-mentioned inorganic particles for coating, and preferably 3 to 7% by weight. Further, these materials can be used in combination, and the surface of the inorganic particles is usually covered with a monomolecular layer or a layer close thereto.

In the present invention, silica particles are particularly preferably used as the inorganic particles contained in the outermost surface layer of the photoreceptor, and further silica particles having low hygroscopicity and few active hydroxyl groups on the surface are preferably used. To be

In the present invention, these inorganic particles are contained at least in the outermost surface layer of the electrophotographic photosensitive member together with the binder. The proportion of the inorganic particles in the outermost surface layer is usually 1% by weight or more and 200% by weight or less, based on the binder. It is preferably used in an amount of 3% by weight or more and 100% by weight or less.

The film strength of the photoconductor can be measured by using a HEIDON-18 type surface property measuring device (manufactured by Shinto Kagaku Co., Ltd.). That is, a vertical load of 200 g is applied to the surface of the photoconductor through a hemispherical diamond needle having a tip radius of 0.3 mm, the needle is moved at a speed of 10 mm / sec to make a scratch, and the depth of the scratch is measured by a laser microscope. (Lase
(made by rtec), and the depth (μm) was defined as the film strength.

Examples of the charge generating substance (CGM) contained in the above-mentioned photoreceptor are phthalocyanine pigment, polycyclic quinone pigment, azo pigment, perylene pigment, indigo pigment,
Examples thereof include quinacridone pigments, azurenium pigments, squarylium dyes, cyanine dyes, pyrylium dyes, thiopyrylium dyes, xanthene dyes, triphenylmethane dyes and styryl dyes, and these charge generating substances (CG
M) is used alone or together with a suitable binder resin to form a layer.

The charge transport material (CTM) contained in the photosensitive layer 6 is, for example, an oxazole derivative, an oxadiazole derivative, a thiazole derivative, a thiadiazole derivative, a triazole derivative, an imidazole derivative,
Imidazolone derivatives, imidazoline derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds,
Benzidine compound, pyrazoline derivative, stilbene compound, amine derivative, oxazolone derivative, benzothiazole derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative, phenazine derivative, aminostilbene derivative, poly-N-vinylcarbazole, poly-1- Vinylpyrene, poly-9-
Vinyl anthracene and the like can be mentioned. These charge transport materials (CTM) are usually layered with a binder.

Among these, particularly preferable charge transporting substances (CTM) are compounds represented by the following general formula.

[0044]

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(In the formula, Ar ₁ , Ar ₂ and Ar ₄ each represents a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group,
Ar ₃ represents a substituted or unsubstituted divalent aromatic hydrocarbon group or heterocyclic group, and R ₂ represents a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group. n is 1 or 2. Ar ₄ and R ₂ may combine with each other to form a ring. )

[0046]

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(In the formula, R ₃ and R ₄ each represent a substituted or unsubstituted aromatic hydrocarbon group, a heterocyclic group or an alkyl group, which may be linked to each other to form a ring. R ₅ is hydrogen. An atom or a substituted or unsubstituted aromatic hydrocarbon group, a heterocyclic group or an alkyl group, Ar ₅ represents a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group, and m is 0 or 1. is there.)

[0048]

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(Wherein Y is a substituted or unsubstituted phenyl group,
Naphthyl group, Piriniru group, a fluorenyl group, a carbazolyl group, a diphenyl group, and 4,4'-alkylidene-diphenyl group, Ar _6, Ar ₇ are each substituted, an unsubstituted aromatic hydrocarbon group or a heterocyclic group. l represents an integer of 1 to 3. )

[0050]

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(In the formula, Ar ₈ , Ar ₉ , Ar ₁₀ and Ar ₁₁ each represent a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group, and Ar ₁ , Ar ₂ and Ar ₃ are as described above. Among these, specific compound examples preferably used in the photoreceptor of the present invention are shown below.

[0052]

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[0053]

[Chemical 6]

[0054]

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[0055]

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[0056]

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[0057]

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As the binder resin contained in the photosensitive layer 6 having the single layer structure and the charge generation layer (CGL) and the charge transport layer (CTL) in the case of the laminated structure, a polyester resin,
Polystyrene resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polycarbonate resin, polyvinyl butyral resin, polyvinyl acetate resin, styrene-butadiene resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-
Examples thereof include maleic anhydride copolymer resin, urethane resin, silicone resin, epoxy resin, silicone-alkyd resin, phenol resin, polysilane resin and polyvinylcarbazole.

The binder resin contained in the uppermost layer of each photoconductor is preferably one that is resistant to mechanical impact, has high abrasion resistance, and does not impair electrophotographic performance. Preferred binder resins include the following general formulas (I) and (I
Examples thereof include polycarbonate resins having a structural unit of I), (III) or (IV).

[0060]

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(In the formula, R _{1 to} R ₈ are hydrogen atoms, halogen atoms, substituted or unsubstituted C 1-10 alkyl groups, cycloalkyl groups or aryl groups, and Z is 4-11 carbon atoms. A saturated or unsaturated carbocycle-forming residue having R, R
₉ is an alkyl group or an aryl group having 1 to 9 carbon atoms. )

[0062]

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(In the formula, R ₁₁ to R ₁₈ each independently represent a hydrogen atom, a halogen atom, an alkyl group or an aryl group.)

[0064]

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(In the formula, R _{21 to} R ₂₈ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group.)

[0066]

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(In the formula, R _{31 to} R ₄₆ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group or an aryl group, k and m are positive integers, and k / m Is selected to be 1 to 10.) The polycarbonate resin having the structural unit represented by the general formula is preferably one having a weight average molecular weight of 30,000 or more.

Next, as a solvent or a dispersion medium used when forming each of the layers, n-butylamine, diethylamine, ethylenediamine, isopropanolamine,
Triethanolamine, triethylenediamine, N, N
-Dimethylformamide, acetone, methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1 −
Examples thereof include trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropinal, ethyl acetate, butyl acetate, dimethyl sulfoxide, and methyl cellosolve. The present invention is not limited to these, but when a ketone solvent is used, the sensitivity and potential change during repeated use are further improved. These solvents can be used alone or as a mixture of two or more solvents.

In the present invention, the weight ratio of the charge generating substance to the binder resin in the charge generating layer is preferably 1: 5 to 5: 1. The thickness of the charge generation layer is preferably 5 μm or less,
It is particularly preferably 0.05 to 2 μm.

The charge transport layer is formed by dissolving the above charge transport substance and the binder resin in an appropriate solvent, and coating and drying the solution. The mixing ratio of the charge transport material and the binder resin is preferably 10: 1 to 1:10 by weight.

The thickness of the charge transport layer is 5 to 50 as a whole.
μm, particularly 10 to 40 μm is preferable.

Next, as the electroconductive support of the electrophotographic photosensitive member of the present invention, 1) a metal plate such as an aluminum plate and a stainless plate, 2) aluminum, palladium, gold on a support such as paper or a plastic film. 3) A thin metal layer such as is provided by lamination or vapor deposition, 3) A layer of a conductive compound such as a conductive polymer, indium oxide or tin oxide is provided by coating or vapor deposition on a support such as paper or plastic film The thing etc. are mentioned.

(Image Forming Method) FIG. 2 is a schematic sectional view of an image forming apparatus using the present invention, and the present invention will be further described with reference to this.

In forming an image, the photoconductor 10 starts rotating in the clockwise direction, and an electrostatic latent image is formed on the photoconductor surface by the image exposure light from the image exposure means 12. The image information to be written is based on the information provided from a document reading unit (not shown), and the photoconductor is the charger 1.
1 uniformly charges before image exposure.

The electrostatic latent image on the photoreceptor surface is developed by the developing means 13 to form a toner image. The toner image is transferred by the transfer unit 15 onto the transfer paper (transfer material) supplied from the paper supply unit 17 at the same timing. The transfer paper peeled off from the photoconductor by the separating means 16 carries a toner image and is conveyed to the fixing means 20 by the conveying means 19 to fix the toner image and then discharged from the inside of the image forming apparatus.

After the transfer paper is separated from the photosensitive member, the toner and the like remaining on the surface of the photosensitive member are removed by the cleaning means 21, and then the process of charging and image exposure is repeated for the next image formation. By repeating this, a large number of images are formed.

The charging, image exposure, transfer and cleaning steps in the present invention, and the transfer material separating step or the heat fixing step which are likely to be mounted in an actual apparatus to which the image forming method of the present invention is applied are performed. The materials used in the technical field to which the invention belongs can be widely used.

[0078]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto. In the text, “parts” means “parts by weight”.

1. Preparation of Photoreceptor An undercoat layer made of polyamide resin and having a thickness of 0.3 μm was provided on an aluminum drum having a diameter of 80 mm. Then, as a charge generation layer, a mixed solution comprising 10 parts of polyvinyl butyral and 1600 parts of methyl ethyl ketone was prepared with respect to 30 parts of perylene compound (CGM-1), and after dispersion, the mixture was applied onto the undercoat layer and dried, Film thickness is 0.3 μm
Was formed.

Next, as a charge transport material, 500 parts of a styryl compound (T-31), 600 parts of a bisphenol Z type polycarbonate resin, and 3000 g of dichloromethane.
To prepare a mixed solution, and applied on the charge generation layer,
It was dried to form a first charge transport layer having a film thickness of 25 μm. Further, the particles shown in Table 1 below were added to the solution for the charge transport layer, and a sufficiently dispersed solution was formed on the first charge transport layer as a second charge transport layer to a thickness of 5 μm.

[0081]

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[0082]

[Table 1]

2. Developer carrier: Ferrite particles having a volume average particle size of 65 μm are coated with styrene / acrylic resin to have a volume resistance of 10 ¹³ Ω.
cm resin coated carrier was prepared.

Toner: Styrene / acrylic resin 100
Parts, carbon black 6 parts, number average molecular weight (Mn: 24
00) 4 parts of polypropylene were mixed, melted, kneaded, pulverized and classified to obtain colored particles having a volume average particle diameter of 8.4 μm. To this, 0.8% by weight of hydrophobic silica was added to obtain a toner.

Developer: The above toner and carrier are mixed,
A developer having a toner concentration of 6% was prepared. 3. Performance Evaluation Using the above developers, changing the combination conditions of the photoconductors 1 to 4, the distance between the photoconductor and the developer layer carrier (DSd) and the distance between the Hcut plate and the developer layer carrier (Hcut plate space). And evaluated.

For evaluation, Konica U-BIX4155 is used.
Using Konica Corp., test chart papers are photographed up to 100,000 sheets, and the image density, resolution and fog after 100,000 copies are comprehensively judged by reflection densitometer measurement and visual observation. did. The results are summarized in Table 2 below.

Evaluation Criteria Image Density: Black image reflection density (Sakura densitometer measurement) is 1.2 or more is good (high) Resolution: 5 lines / mm or more is good, 3 lines / mm is bad ( Low)

[0088]

[Table 2]

As is clear from Table 2, the condition No. 1 to 3, 6, 9 and 10 and 12 show good characteristics, but it is understood that there is a problem in any of the characteristics under other conditions.

[0090]

According to the present invention, it is possible to provide an image forming method using an organic photoconductor, which maintains good image quality even when a large amount of images are formed. Further, in an image forming method using a two-component developer containing a carrier and a toner, it is possible to provide an image forming method which maintains good image quality even when a large amount of images are formed.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing the relationship between a photoconductor and a developing device according to the present invention.

FIG. 2 is a schematic sectional view of an image forming apparatus according to the present invention.

[Explanation of symbols]

1 Interval between developer layer carrier and photoconductor (Dsd) 2 Interval between developer layer carrier and developer layer regulating plate (Hcut plate) 3 Developer layer carrier 4 NS bipolar magnet 5 Developer layer regulating plate (Hcut plate) 10 Photoreceptor 13 Developing device 40 Developer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03G 15/09 G03G 9/10

Claims (4)

[Claims] 1. An organic photoreceptor is used for charging, image exposure, development,
In an image forming method of forming a large number of images by repeating the steps of transfer and cleaning, a photoreceptor has a charge generation layer on a conductive support and a plurality of charge transport layers laminated thereon, In addition, the outermost surface charge transport layer contains inorganic particles, a two-component developer consisting of carrier and toner is used for development, and the distance (Dsd) between the developer layer carrier and the photoconductor in the development region is 300 to 1000 μm. The image forming method is characterized in that the gap between the developer layer carrying member and the developer layer regulating plate (Hcut plate) is narrower by 0 to 200 μm than the above. 2. The image forming method according to claim 1, wherein the inorganic particles are inorganic particles having a Mohs hardness of 5 or more and a volume average particle diameter of 0.05 to 2 μm. 3. The carrier has an electric resistance value of 10 ¹² Ω ·
The image forming method according to claim 1, wherein the image forming method is an insulating carrier having a cm or more. 4. A vertical load of 200 g is applied by using a diamond needle having a Mohs hardness of 5 or more in the outermost surface layer and spherical inorganic particles, and having a film strength of the photosensitive layer having a tip radius of 0.3 mm. The image forming method according to claim 1, 2 or 3, wherein the scratch is a depth of 0.1 µm to 1 µm.