JP2005055565A - Image forming method, image forming apparatus and process cartridge for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method applicable to a high endurance digital high-speed electrophotographic process with laser light as a writing light source, excellent in wear resistance, nearly free of deterioration of a photoreceptor such as filming, and capable of giving a stable excellent image in a high-definition electrophotographic process, and to provide an image forming apparatus and a process cartridge for the image forming apparatus. <P>SOLUTION: In the image forming method in which a photoreceptor is subjected to at least charging, imagewise exposure, development, transfer, fixation and cleaning, the photoreceptor has a protective layer containing inorganic fine particles comprising alumina or titanium oxide, and a toner for development is obtained by sticking two or more kinds of inorganic fine particles different from each other in average particle diameter to a surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming method, an image forming apparatus, and a process cartridge for an image forming apparatus. More specifically, the photoconductor has high wear durability and suppresses filming due to adhesion of an external toner additive to the surface of the photoconductor. The present invention relates to an image forming method capable of obtaining a stable image, an image forming apparatus, and a process cartridge for the image forming apparatus.

An electrophotographic method using the Carlson process and various modifications of this process is widely used in the electrophotographic field such as a copying machine, a facsimile machine, and a printer.
As an electrophotographic photosensitive member (hereinafter sometimes simply referred to as a photosensitive member) used in this electrophotographic method, an organic photosensitive material has been widely used in recent years because of advantages such as low cost, mass productivity, and non-pollution. It is becoming.
Further, not only the photoreceptor but all units constituting the electrophotographic system have extremely high demands for durability and stability from the viewpoint of resource saving and energy saving.

  The mechanism of electrostatic latent image formation on the photoreceptor is that, after the photoreceptor is charged and irradiated with light, the light is absorbed by the charge generation material, and the charge generation material that has absorbed the light generates charge carriers, and this charge is generated. The carrier is injected into the charge transport material, moves in the charge transport layer or photosensitive layer according to the electric field generated by charging, and forms an electrostatic latent image by neutralizing the charge on the surface of the photoreceptor. is there.

  In addition to those using a photoconductive resin typified by polyvinyl carbazole (PVK), a charge transfer complex type typified by 2,4,7-trinitrofluorenone (TNF) -PVK, Known are pigment dispersion type typified by phthalocyanine-binder, function separation type photoreceptor using a combination of a charge generation material and a charge transport material, etc. Has been.

Various types of organic photoreceptor materials have been developed in the past, but in order to make these excellent photoreceptors that can be put to practical use, sensitivity, acceptance potential, potential retention, potential stability, residual potential, Various characteristics such as electrophotographic characteristics such as spectral characteristics, mechanical durability such as abrasion resistance, and chemical stability against heat, light, discharge products, and the like are required.
In particular, downsizing of the electrophotographic system is desired, and the diameter of the photoreceptor is inevitably reduced, and a demand for durability against the abrasion phenomenon of the photoreceptor that progresses in accordance with the number of sheets passing is increasing. Yes.

As described above, there has been a strong demand for mechanical durability, mainly wear resistance. However, in conventional organic photoreceptors (OPC) and electrophotographic processes using the same, the wear resistance of organic substances. However, at present, sufficient durability has not been obtained.
Further, the requirement for wear resistance is also due to the fact that it is essential to reduce the thickness of the photosensitive layer for higher definition output images, and the margin for wear is becoming stricter.
The reason why the photosensitive layer thickness has a great influence on the high definition of the output image is considered as follows.

For example, in the case of stacked negatively charged OPC, electrons are absorbed by the substrate among positive and negative carriers generated in the charge generation layer by exposure incident light, but the holes move through the charge transport layer to form electrons on the surface of the photoreceptor. Recombine and disappear. Due to this annihilation, the electric field that pulls the holes to the surface of the photoreceptor gradually weakens, and the holes move toward areas that are not exposed to light. This is said to be a diffusion phenomenon of carriers toward the surface of the photoreceptor, which prevents formation of a latent image faithful to the incident incident light and causes image deterioration such as a reduction in resolution.
In this diffusion phenomenon, the thickness of the charge transport layer is greatly affected, and reducing the layer thickness is very effective for maintaining the resolution.

Further, in recent years, in laser exposure, which has become mainstream, the exposure is different from the exposure of a conventional halogen lamp or the like, and the incident photon flow rate relating to the exposure is about 10 ⁷ times larger than that of a halogen lamp. Therefore, the density of the generated carriers becomes extremely large, and the electric field flowing out of the charge transport layer weakens the electric field of the charge generation layer, which affects the carrier moving speed and causes the carriers generated near the center of the laser beam to the surface of the photoreceptor. Arrival will also be delayed.
The space charge distribution generated in this way tends to cause carrier diffusion in the direction parallel to the surface of the photoreceptor, and has a greater effect on resolution reduction.

By the way, in an organic photoreceptor, as a method for improving wear resistance, a method of providing a protective layer containing a filler made of a metal or a metal oxide is disclosed (for example, see Patent Document 1). In this method, the average particle size of the filler is set to 0.3 μm or less to increase the transparency of the protective layer and to suppress an increase in residual potential.
Further, in the charge transport layer containing the filler, the refractive index difference between the filler and the charge transport layer is 0.1 or more, and 1 × 10 ⁴ to 2 × 10 ⁵ particles having a particle diameter of 1 to ³ μm per 1 mm ^2. What is contained is disclosed (for example, refer to Patent Document 2).
On the other hand, in order to suppress filming due to the adhesion of the toner component to the photoreceptor, the surface of the photoreceptor has a protective layer containing fine particles, and the polymer or polymerisable as a binder resin for the toner constituting the developer The thing using the thing which has as a main component the crosslinking component obtained by making the carboxyl group and the polyvalent metal compound which exist in a monomer react is disclosed (for example, refer patent document 3). This reduces the proportion of low molecular weight components that tend to adhere to the photoreceptor protective layer containing fine particles and suppresses the occurrence of image defects.
Similarly, as a method for suppressing filming on a photoreceptor having a surface layer reinforced with inorganic fine particles, inorganic particles having a volume average particle diameter of 0.05 to 2 μm are contained in the photoreceptor surface layer, and the surface roughness thereof. A toner is disclosed in which Rz is 0.05 μm or more and a toner contains a release agent having a number average domain diameter of 0.1 to 1.1 μm (for example, see Patent Document 4).
Further, fine particles having a volume resistivity of 1 × 10 ⁸ to 1 × 10 ¹² Ωcm and a number average particle size of 20 to 100 nm are adhered to the surface layer of the photoreceptor, and the developer is the same as the spherical toner particles having a sphericity of less than 120. There has been disclosed a technique that achieves cleaninglessness by including a toner having externally attached fine particles having conditions (see, for example, Patent Document 5).

According to the conventional technology described above, in which a filler is contained in the outermost surface layer such as the protective layer of the photoconductor, it is very effective in improving the durability such as the wear resistance of the photoconductor. When it is contained, there is a new problem that filming due to a toner component or the like is likely to occur. However, in order to solve the filming problem when such a filler is contained, the conventional filming suppression means is not yet sufficient.
That is, there is no photoconductor using a conventionally proposed filler that is excellent in both durability and filming resistance, and its appearance is desired, but there is no proposal yet.

JP 57-30864 A JP-A-8-234455 JP-A-8-234482 JP-A-8-262756 JP-A-11-52610

  The object of the present invention is to eliminate such drawbacks of the prior art, and in particular, can be applied to a high-endurance digital high-speed electrophotographic process using a laser beam that has become mainstream in recent years as a writing light source, and has excellent wear resistance. PROBLEM TO BE SOLVED: To provide an image forming method, an image forming apparatus, and a process cartridge for the image forming apparatus capable of giving a stable and excellent image to a high-definition electrophotographic process with extremely little deterioration of the photoreceptor such as filming. It is what.

An object of the present invention is to provide an image forming method of (1) “at least a photoreceptor subjected to charging, image exposure, development, transfer, fixing and cleaning treatment, wherein the photoreceptor comprises alumina or titanium oxide. An image forming method comprising: a protective layer containing inorganic fine particles, and a toner to be developed having two or more inorganic fine particles having different average particle sizes attached to the surface thereof; The image forming method as described in item (1) above, wherein the photosensitive member protective layer contains a charge transport material, and (3) “inorganic fine particles adhering to the developed toner surface” The image forming method according to the item (1) or (2), wherein the average particle size is smaller than the average particle size of the inorganic fine particles contained in the photosensitive member protective layer ”, (4)“ Adhered to the toner surface to be developed The average particle size of the largest group of inorganic fine particles is 3 to 20 times the average particle size of the smallest group, wherein the average particle size is any one of (1) to (3) (5) “Charging means for the photosensitive member is in contact with or in close proximity to the photosensitive member”. (1) to (4) above Any one of the image forming methods ", (6)" Charging is imparted to the photosensitive member by applying a voltage in which an alternating current component is superimposed on a direct current component to the charging member. This is solved by the “image forming method described in item (5)”.
Further, the above-mentioned problem is (7) “image forming apparatus having at least a charging member, an image exposing unit, a developing unit, a transferring unit, a fixing unit, and a cleaning unit on the photosensitive member, wherein the photosensitive member is alumina. Or a developing means for developing using a toner having a protective layer containing inorganic fine particles made of titanium oxide and having two or more kinds of inorganic fine particles having different average particle diameters attached to the surface. (8) "The image forming apparatus according to (7) above, wherein the photoconductor protective layer contains a charge transport material", (9) "The above" The average particle diameter of the inorganic fine particles attached to the toner surface is smaller than the average particle diameter of the inorganic fine particles contained in the photosensitive member protective layer. The item (7) or (8), Image forming apparatus ", (10) Item (7) to Item (9), wherein the average particle size of the largest group of inorganic fine particles adhering to the toner surface is 3 to 20 times the average particle size of the smallest group. The image forming apparatus according to any one of Items 1 to 3, wherein the charging means for the photosensitive member is disposed in contact with or close to the photosensitive member. The image forming apparatus according to any one of Items (10) and (12) “Charging is applied to the photosensitive member by applying a voltage in which an AC component is superimposed on a DC component to a charging member. This is solved by the image forming apparatus according to item (11).
Further, the above-mentioned problem is (13) “a process cartridge comprising at least one of a photoconductor, a charging unit, an image exposing unit, a developing unit, a transferring unit, a fixing unit, and a cleaning unit. Alternatively, the image forming apparatus includes at least developing means for developing using a photosensitive member containing inorganic fine particles made of titanium oxide in a protective layer and a toner in which two or more types of inorganic fine particles having different average particle sizes are attached to the surface. This is solved by a process cartridge for an image forming apparatus.

In order to solve the above-mentioned problems, the present inventors examined a mechanism that causes filming on the surface of the photoreceptor.
As a result, in the photoreceptor in which the filler is contained in the outermost surface layer such as a protective layer, the adhesion between the cleaning blade and the photoreceptor surface may be deteriorated due to the non-uniformity, and the dispersion state is particularly insufficient. In this case, due to the agglomerates, cleaning failure occurs due to a decrease in adhesion between the surface of the photoreceptor and the cleaning blade. It has been found that the cleaning failure causes filming of the toner component on the surface of the photoconductor, which tends to adversely affect the electrostatic stability and image quality of the photoconductor.
It was also confirmed in our examination that even with the same photoreceptor, filming can be suppressed by making the presence of the filler in the protective layer favorable and using a specific developer.
The inventors of the present invention focused on the state of the photoreceptor surface and the state of the developer used in order to deal with such a filming problem, and as a result of intensive studies by comparing with the filming state, It came to completion.

The photoreceptor used in the present invention is one in which inorganic fine particles are contained in the protective layer in order to improve the wear resistance. As the inorganic fine particles, alumina or titanium oxide is used, and they may be hydrophobized by surface treatment. Hydrophobic treatment improves the adhesion of the inorganic fine particles to the binder component in the layer and can further improve the wear resistance.
Here, when the wear state and filming state of the photoconductor were examined in detail, it was found that the photoconductor was greatly affected by the external additive of the toner used. Silica and titanium oxide are added to the toner for the purpose of improving fluidity and adjusting charging properties, and are externally added to the toner particle surfaces. These external additives are embedded in the toner particles over time or separated from the toner particles and become free, but this free external additive greatly affects the above-mentioned wear or filming. It became clear. Furthermore, submicron fine particles are exclusively used as the size of the external additive, but the wear and filming conditions differ depending on the size and the relative size of the inorganic fine particles contained in the protective layer of the photoreceptor. This can be considered that the liberated external additive is held in the vicinity of the edge of the cleaning blade, and the surface of the photoreceptor is worn by the interaction with the cleaning blade, or is fixed to the surface of the photoreceptor to cause filming.

The present invention uses a toner external additive having at least two different particle sizes smaller than the inorganic fine particles contained in the protective layer of the photoreceptor, thereby maintaining the wear resistance of the photoreceptor. This is a situation where there is very little ming.
In the present invention, “the average particle diameter is different” means that the average particle diameter of the largest group of inorganic fine particles is 1.8 times or more than the average particle diameter of the smallest group of inorganic fine particles. The range of the size of the external additive for effectively preventing wear and filming is when the average particle size of the largest group is 3 to 20 times the average particle size of the smallest group, and more preferably Is 5 to 15 times. In addition, the amount of the largest group of external additives is preferably set in a range not exceeding ½ by weight with respect to the total amount of external additives. May deteriorate the wear durability of the photoreceptor.

Photoreceptor wear is thought to be caused by the external toner additive sliding on the surface of the protective layer when pressed by a cleaning blade, and the photoconductor wear proceeds. It is thought that it grows by being deposited while being pushed into the body surface.
However, when each constituent member is set in the range as in the present invention, the cleaning blade moving on the surface of the photoreceptor is intermittently supported by the inorganic fine particles present on the surface of the protective layer. It is considered that a slight separation from the protective layer of the blade or an effect of reducing the contact pressure is produced, and as a result, it is considered that wear can be suppressed. The minute separation by the inorganic fine particles present on the surface layer does not cause toner particles to slip through, and does not lead to poor cleaning. Concerning filming, it is thought that the main phenomenon is due to the deposition of the toner external additive, and as in the present invention, it is difficult to deposit due to the presence of external additives of different sizes, and even larger particles. It is thought that there is an action of scraping off the sediment. In addition, it is important that the size of the external additive is at least smaller than the inorganic fine particles in the photosensitive member protective layer. Otherwise, the wear resistance is impaired.

The configuration of the cleaning unit used in the image forming apparatus of the present invention is preferably a versatile urethane rubber blade, but the blade edge portion that contacts the photosensitive member with respect to the blade mounting portion is located on the opposite side in the rotational direction. The above-described effect can be expected in the configuration by the counter arrangement.
In particular, when a spherical toner (including a substantially spherical shape) that tends to cause poor cleaning is used, in the present invention, the blade edge receives resistance intermittently by inorganic fine particles held on the surface of the photosensitive member. The wedge shape at the tip is restored and good cleaning can be expected.

  According to the present invention, it can be preferably applied to a highly durable digital high-speed electrophotographic process using a laser beam as a writing light source, which has become the mainstream in recent years, has excellent wear resistance, extremely little deterioration of the photoreceptor such as filming, and high An image forming method, an image forming apparatus, and a process cartridge for an image forming apparatus that can provide a stable and excellent image for a fine electrophotographic process can be provided.

Hereinafter, the present invention will be described with reference to the drawings.
First, the photoconductor used in the present invention will be described.
The photoreceptor may be a single layer or a laminate, but a function separation type laminate type will be described as an example.
FIG. 1 is a schematic cross-sectional view of a multilayer electrophotographic photosensitive member used in the present invention.
FIG. 2 is a schematic cross-sectional view of another laminated electrophotographic photosensitive member used in the present invention.
The electrophotographic photosensitive member used in the present invention is provided with a photosensitive layer (2) on a conductive support (conductive substrate) (1), and this photosensitive layer (2) is mainly composed of a charge generating material. And a charge transport layer (4) mainly composed of a charge transport material.
And a protective layer (5) is formed as a surface layer of such an electrophotographic photoreceptor. This protective layer (5) will be described later.

The conductive support (1) has a volume resistance of 10 ¹⁰ Ωcm or less, such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, and other metals, tin oxide, indium oxide, etc. Metal oxide film or cylindrical plastic or paper coated by vapor deposition or sputtering, aluminum, aluminum alloy, nickel, stainless steel plate or the like, and then cutting, superfinishing, polishing, etc. It consists of a tube surface treated with

The charge generation layer (3) is a layer mainly composed of a charge generation material.
As the charge generation material, an inorganic or organic material is used, and typical examples include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, quinone condensed polycyclic compounds, squarics. Examples include acid dyes, phthalocyanine pigments, naphthalocyanine pigments, azulenium salt dyes, selenium, selenium-tellurium alloys, selenium-arsenic alloys, and amorphous silicon.
These charge generation materials may be used alone or in combination of two or more.

In the charge generation layer (3), the charge generation material is dispersed by a ball mill, attritor, sand mill or the like using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, 2-butanone or dichloroethane together with a binder resin, and a dispersion is applied. Can be formed. The application is performed by a dip coating method, a spray coating method, a bead coating method, or the like.
Examples of the binder resin used as appropriate include polyamide resins, polyurethane resins, polyester resins, epoxy resins, polyketone resins, polycarbonate resins, silicone resins, acrylic resins, polyvinyl butyral resins, polyvinyl formal resins, polyvinyl ketone resins, polystyrene resins, poly resins. An acrylic resin, a polyamide resin, etc. can be mentioned.
The amount of the binder resin is suitably 0 to 2 parts with respect to 1 part of the charge generating material on a weight basis.
The charge generation layer (3) can also be formed by a known vacuum thin film production method.
The film thickness of the charge generation layer (3) is usually 0.01 to 5 μm, preferably 0.1 to 2 μm.

The charge transport layer (4) can be formed by dissolving or dispersing a charge transport material and a binder resin in an appropriate solvent, and applying and drying the solution. Moreover, a plasticizer, a leveling agent, etc. can also be added as needed.
Among charge transport materials, low molecular charge transport materials include electron transport materials and hole transport materials.

Examples of the electron transport material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2, 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene-4-one, 1,3,7-tri Examples thereof include electron accepting substances such as nitrodibenzothiophene-5,5-dioxide.
These electron transport materials may be used alone or as a mixture of two or more.

Examples of hole transport materials include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane. , Styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like.
These hole transport materials may be used alone or as a mixture of two or more.

When a polymer charge transport material is used as the charge transport material, it may be dissolved or dispersed in an appropriate solvent, and coated and dried to form a charge transport layer.
The polymer charge transport material may be a material having a charge transporting substituent in the main chain or side chain in the low molecular charge transport material.
Particularly preferred polymer charge transport materials are polycarbonate, polyurethane, polyester, polyether, etc. Among them, use of a polycarbonate having a triarylamine structure is advantageous.
If necessary, an appropriate amount of a binder resin, a low molecular charge transport material, a plasticizer, a leveling agent, a lubricant and the like can be added to the polymer charge transport material.

  The binder resin used in the charge transport layer (4) together with the charge transport material includes polystyrene resin, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, polychlorinated resin. Vinyl resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate resin, polyvinylidene chloride resin, polyarylate resin, phenoxy resin, polycarbonate resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl toluene resin And thermoplastic or thermosetting resins such as acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.

  Examples of the plasticizer added to the charge transport layer (4) as needed include general-purpose plasticizers such as dibutyl phthalate and dioctyl phthalate, and the amount used is 0 based on the weight of the binder resin. About 30% is appropriate.

Examples of leveling agents added to the charge transport layer (4) include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. The amount is suitably about 0 to 1% based on the weight of the binder resin.
Examples of the solvent include tetrahydrofuran, dioxane, toluene, 2-butanone, monochlorobenzene, dichloroethane, methylene chloride and the like.

  The thickness of the charge transport layer (4) may be appropriately selected in the range of 5 to 30 μm according to the desired photoreceptor characteristics. As described above in the prior art, the charge transport layer is preferably thin from the viewpoint of high definition, and considering laser exposure, the thickness is preferably 20 μm or less, more preferably 15 to 18 μm. Here, the lower limit is comprehensively determined from the uniformity of the film, the chargeability, and the electric field required in the development process. In any case, in order to realize a thin film, it is necessary to greatly increase the wear resistance, and the importance of the protective layer as in the present invention is very high.

In the present invention, the content of the charge transport material contained in the charge transport layer is preferably 40% by weight or more of the charge transport layer.
If it is less than 40% by weight, a sufficient light decay time in a high-speed electrophotographic process cannot be obtained in pulsed light exposure in laser writing on a photoreceptor, which is not preferable.

The charge transport layer mobility in the photoreceptor is 3 × 10 ⁻⁵ cm ² / V · s under the condition of the charge transport layer electric field strength in the range of 2.5 × 10 ^{5 to} 5.5 × 10 ⁵ V / cm. It is preferable that it is above, and it is more preferable that it is 7 × 10 ⁻⁵ cm ² / V · s or more.
This mobility can be adjusted as appropriate to achieve this under each use condition.
This mobility may be obtained by a conventionally known Time Of Flight method.

In the laminated electrophotographic photoreceptor used in the present invention, an undercoat layer can be formed between the conductive support (1) and the photosensitive layer.
This subbing layer generally comprises a resin as a main component, but these resins are resins that are highly soluble in general organic solvents in consideration of applying a photosensitive layer thereon using a solvent. It is desirable.
Examples of such resins include polyvinyl alcohol resins, caseins, water-soluble resins such as sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane resins, melamine resins, alkyd-melamine resins, and epoxy resins. Examples thereof include curable resins that form an equal three-dimensional network structure.
Further, fine powder of metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the undercoat layer in order to prevent moire and reduce residual potential.
This undercoat layer can be formed by using an appropriate solvent and coating method as in the case of the photosensitive layer.
Furthermore, it is also useful to use a metal oxide layer formed by, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent or the like as the undercoat layer.
In addition, the undercoat layer is formed by anodizing Al ₂ O ₃ , organic matter such as polyparaxylylene (parylene), inorganic matter such as SiO, SnO ₂ , TiO ₂ , ITO, CeO ₂ It is also effective to form the film by a vacuum thin film manufacturing method.
The thickness of the undercoat layer is suitably from 0 to 5 μm.

In the multilayer electrophotographic photoreceptor, a protective layer (5) containing a filler is formed on the photosensitive layer (2) as a surface layer for the purpose of protecting the photosensitive layer and improving durability.
Materials used for the protective layer (5) include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether resin, allyl resin, phenol resin, polyacetal resin, polyamide resin, polyamideimide resin, Polyacrylate resin, polyallylsulfone resin, polybutylene resin, polybutylene terephthalate resin, polycarbonate resin, polyethersulfone resin, polyether resin, polyethylene terephthalate resin, polyimide resin, acrylic resin, polymethylpentene resin, polypropylene resin, polyphenylene oxide resin, Examples of the resin include polysulfone resin, AS resin, AB resin, BS resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, and epoxy resin.

A filler is added to the protective layer (5) for the purpose of improving wear resistance and filming resistance. In the present invention, inorganic fine particles made of alumina or titanium oxide are used as the filler.
The amount of these fillers added to the protective layer (5) is usually 10 to 40%, preferably 20 to 30% on a weight basis.
If the amount of the filler is less than 10%, the wear is large and the durability is inferior. If it exceeds 40%, the bright portion potential at the time of exposure increases remarkably, and the sensitivity reduction cannot be ignored.
The average particle size of the filler is 0.3 to 1.2 μm, preferably 0.3 to 0.7 μm. When the particle size is small, the wear resistance is not sufficient, When the particle size is large, writing light is scattered, which is not preferable.

Furthermore, a dispersion aid can be added to the protective layer (5) in order to improve the dispersibility of the filler.
As the added dispersion aid, those used in coatings and the like (for example, modified epoxy resin condensates, unsaturated polycarboxylic acid low molecular weight polymers, etc.) can be used as appropriate, and the amount is usually a filler based on weight. The amount is 0.5 to 4%, preferably 1 to 2%.

In addition, it is very effective to add the above-mentioned charge transporting material to the protective layer (5), and the amount of addition may be the same as that of the charge transporting layer, and the characteristics for exposure such as reduction of residual potential can be improved. Can do.
In the case of a low molecular charge transport material on a weight basis, the amount of the charge transport material added is preferably 20 to 60% of the solid content excluding the filler, and the exposure characteristics are within the range where the mechanical characteristics of the protective layer are not impaired. Add to the extent to improve.
In the case of the polymer charge transport material, since it has a function as a binder itself, the addition amount can be further increased and the solid content excluding the filler can be 20 to 95%.
In general, it is known that the film strength of a film in which a low molecular charge transport material is added to a binder resin is lowered according to the amount of the added resin. Furthermore, when the inorganic fine particles are added, it is necessary to maintain good adhesion with the binder, and in particular, the retention of the inorganic fine particles on the surface layer is important from the viewpoint of wear resistance. Usually, when the surface-treated inorganic fine particles are used, the affinity with the binder is improved and the strength of the film itself can be improved.
Further, an antioxidant can be added as necessary. The antioxidant will be described later.
As a method for forming the protective layer (5), a normal coating method such as a spray method is adopted, and the thickness of the protective layer (5) is suitably about 0.5 to 10 μm, preferably about 4 to 6 μm.

In the present invention, another intermediate layer can be formed between the photosensitive layer and the protective layer.
In the intermediate layer, a binder resin is generally used as a main component.
Examples of the binder resin include polyamide resin, alcohol-soluble nylon, water-soluble polyvinyl butyral resin, polyvinyl butyral resin, and polyvinyl alcohol resin.
As the method for forming the intermediate layer, the above-described normal coating method is adopted, and the thickness of the intermediate layer is suitably about 0.05 to 2 μm.

  In the present invention, in order to improve environmental resistance, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, an antioxidant, a plasticizer, a lubricant, an ultraviolet absorber, and a low molecular charge transport material are used for each layer. And leveling agents can be added.

  Antioxidants that can be added to each layer include phenol compounds such as 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n -Octadecyl-3- (4-hydroxy-3,5-di-tert-butylphenol), 2,2-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2-methylene-bis- ( 4-ethyl-6-tert-butylphenol), 4,4-thiobis- (3-methyl-6-tert-butylphenol), 4,4-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1 , 3-Tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4 − Droxybenzyl) benzene, tetrakis- [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, bis [3,3-bis (4-hydroxy-3-tert-butyl) Phenyl) butyric acid] glycol ester, tocopherols and the like.

  As paraphenylenediamines, N-phenyl-N-isopropyl-p-phenylenediamine, N, N-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N , N-di-isopropyl-p-phenylenediamine, N, N-dimethyl-N, N-di-t-butyl-p-phenylenediamine, and the like.

  As hydroquinones, 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) -5-methylhydroquinone and the like.

  Examples of organic sulfur compounds include dilauryl-3,3-thiodipropionate, distearyl-3,3-thiodipropionate, and ditetradecyl-3,3-thiodipropionate.

  Examples of the organic phosphorus compounds include triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, and tri (2,4-dibutylphenoxy) phosphine.

  Plasticizers that can be added to each layer include phosphate ester plasticizers such as triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, Examples include tri-2-ethylhexyl phosphate and triphenyl phosphate.

  As phthalate ester plasticizers, dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, phthalic acid Dinonyl, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, dioctyl fumarate, etc. Is mentioned.

  Examples of the aromatic carboxylate plasticizer include trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate, and the like.

  As an aliphatic dibasic ester plasticizer, dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, adipate-n-octyl-n-decyl, Diisodecyl adipate, dicapryl adipate, di-2-ethylhexyl azelate, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2-sebacate Examples thereof include ethoxyethyl, dioctyl succinate, diisodecyl succinate, dioctyl tetrahydrophthalate, and di-n-octyl tetrahydrophthalate.

  Examples of the fatty acid ester derivative plasticizer include butyl oleate, glycerin monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, and tributyrin.

  Examples of the oxyester plasticizer include methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, and tributyl acetyl citrate.

  Epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil, butyl epoxy stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate, etc. Is mentioned.

  Examples of the dihydric alcohol ester plasticizer include diethylene glycol dibenzoate and triethylene glycol di-2-ethylbutyrate.

  Examples of the chlorine-containing plasticizer include chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, and methoxychlorinated fatty acid methyl.

  Examples of the polyester plasticizer include polypropylene adipate, polypropylene sebacate, polyester, and acetylated polyester.

  As sulfonic acid derivative plasticizers, p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide Etc.

  Examples of the citric acid derivative plasticizer include triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, and acetyl citrate-n-octyldecyl.

  Other examples include terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietic acid, and the like.

  Examples of ultraviolet absorbers that can be added to each layer include 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2,4-trihydroxybenzophenone, 2,2,4,4-tetrahydroxybenzophenone as benzophenone ultraviolet absorbers. 2,2-dihydroxy 4-methoxybenzophenone and the like.

  Examples of the salicylate ultraviolet absorber include phenyl salicylate, 2,4 di-t-butylphenyl 3,5-di-t-butyl 4-hydroxybenzoate, and the like.

  As a benzotriazole ultraviolet absorber, (2-hydroxyphenyl) benzotriazole, (2-hydroxy5-methylphenyl) benzotriazole, (2-hydroxy5-methylphenyl) benzotriazole, (2-hydroxy-3-tert-butyl) 5-methylphenyl) 5-chlorobenzotriazole and the like.

  Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3-diphenyl acrylate, methyl 2-carbomethoxy 3 (paramethoxy) acrylate, and the like.

  Examples of the quencher (metal complex salt) ultraviolet absorber include nickel (2,2thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate and the like.

  As HALS (hindered amine) -based UV absorbers, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1 -[2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) Propionyloxy] -2,2,6,6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2 , 4-dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine and the like.

  In this way, the present invention uses an electrophotographic photosensitive member in which a photosensitive layer and a protective layer are formed on a conductive substrate, and an undercoat layer and an intermediate layer are formed as desired. The protective layer is made of alumina or titanium oxide as a filler. By including the inorganic particles, the resistance to abrasion is improved and the durability is improved, but not only this, but also two or more kinds of inorganic particles having different average particle diameters are attached to the surface as external additives. In combination with the use of toner, filming on the surface of the photoreceptor is extremely effectively suppressed.

Subsequently, an image forming method and an image forming apparatus of the present invention will be described.
FIG. 3 is a schematic view showing an image forming method and an image forming apparatus of the present invention.
The photoconductor (6) has a drum shape, but may be a sheet or an endless belt.
Around the photoreceptor (6), a pre-transfer charger (7), a transfer charger, a separation charger, and a pre-cleaning charger (8) are arranged as necessary, and corotron, scorotron, solid state charger (solid state Charger) and known means such as a charging roller are arranged.

The charging member (9) may be in contact with the photosensitive member. However, by providing an adjacent gap with an appropriate gap (about 10 to 200 μm) between them, the wear amount of both can be reduced and the charging member Toner filming can be suppressed and can be preferably used.
In particular, in the photoreceptor of the present invention, good characteristics can be maintained by providing a gap of about 50 μm, which is considered to be because the influence of the surface state of the protective layer can be reduced.
The voltage applied to the charging member (9) is effective when the AC component is superimposed on the DC component in order to stabilize charging and suppress charging unevenness.
However, while charging is stabilized, it has been found that the surface layer of the photoconductor used during the process is more easily worn than when only the DC component is applied. Also in this case, the photoconductor of the present invention can maintain good characteristics without any problem because of its high wear resistance.
As the transfer means, the above charger can generally be used, but those using a transfer belt (10) as shown in FIG. 3 are effective.
Further, light sources such as the image exposure unit (11) and the charge removal lamp (12) include fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LD), electroluminescence (EL). ) And other luminescent materials can be used.
Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.
These light sources are used not only for the process shown in FIG. 3 but also for a transfer process using light irradiation, a static elimination process, a cleaning process, a pre-exposure process, etc., and irradiate the photoreceptor (6) with light.

Further, the developing unit (13) transfers the toner developed on the photoconductor (6) to the transfer paper (14), but not all is transferred to the photoconductor (6). Some toner remains, and such toner is removed from the photoreceptor (6) by the fur brush (15) and the cleaning blade (16).
Although cleaning may be performed only with a cleaning blade, a cleaning brush such as a fur brush is often used in combination.
When the electrophotographic photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member.
If this is developed with negative (positive) polarity toner (electrodetection fine particles), a positive image can be obtained, and if developed with positive (negative) polarity toner, a negative image can be obtained.
In this developing means, a toner formed by adhering two or more kinds of inorganic fine particles having different average particle diameters to the surface is supplied to the surface of the photoreceptor to develop the electrostatic latent image. Thus, filming can be effectively prevented.
Moreover, a means known per se can be applied as the charge eliminating means.
In the figure, (17) is a registration roller, and (18) is a separation claw.
The present invention is an image forming method and an image forming apparatus using an electrophotographic photosensitive member for such image forming means.

  That is, the present invention relates to an image forming method and an image forming apparatus that perform at least charging, image exposure, development, transfer, fixing, and cleaning processes, using the electrophotographic photosensitive member having the protective layer, and the protective layer The image forming method and the image forming apparatus are characterized in that the inorganic fine particles therein are subjected to a surface treatment to enhance adhesion to the binder resin.

The image forming unit may be fixedly incorporated in a copying apparatus, a facsimile machine, or a printer, but may be incorporated in these apparatuses and made detachable in the form of a process cartridge.
FIG. 4 is a schematic view showing an example of a process cartridge for an image forming apparatus according to the present invention.
The process cartridge shown in FIG. 4 has a drum-shaped photoconductor (101) that rotates in the direction of the arrow, and in the periphery thereof, a contact charging device (102), an image exposure (103) from an exposure device, A developing device (104), a contact transfer device (106), a cleaning unit (107), a static elimination lamp (108), a fixing device (109), and the like are provided, and a transfer body (105) is supplied thereto. The protective layer of the photoreceptor (101) contains inorganic particles made of alumina or titanium oxide, and the developing device (104) contains two or more kinds of inorganic particles having different average particle diameters as a developing toner. The toner adhered to the surface is supplied to the surface of the photoreceptor, and the electrostatic latent image is developed.
Here, the process cartridge includes a photosensitive member, and includes at least one of a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit. Parts).
Therefore, the present invention is not limited to the process cartridge shown in FIG. 4, and is a process cartridge for an image forming apparatus having a photoreceptor and at least one of charging, image exposure, development, transfer, fixing, and cleaning means. And at least developing means for developing using the electrophotographic photosensitive member and the toner.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited at all by these Examples.
All parts are parts by weight.
<Preparation of photoconductor for evaluation>
A subbing layer coating solution, a charge generation layer coating solution, a charge transport layer coating solution and a protective layer coating solution having the following composition are applied in that order on an aluminum substrate having a diameter of 30 mm, dried, and dried under 3.5 μm. An electrophotographic photoreceptor comprising a pulling layer, a 0.15 μm charge generation layer, and an 18 μm charge transport layer was prepared.
At this time, the coating of each layer was performed by a dip coating method.
[Undercoat layer coating solution]
400 parts of titanium dioxide powder (Ishihara Sangyo, Taipei CR-EL)
Melamine resin 65 parts (Dainippon Ink Chemical Co., Ltd., Super Becamine G-821-60)
120 parts alkyd resin (Dainippon Ink & Chemicals, Beckosol 1307-60-EL)
2-butanone 400 parts [charge generation layer coating solution]
Titanyl phthalocyanine 7 parts Polyvinyl butyral 5 parts (Union Carbide, XYHL)
2-butanone 400 parts [charge transport layer coating solution]
10 parts of polycarbonate (Teijin Chemicals, PCX-5)
8 parts of charge transport material of the following structural formula

テトラヒドロフラン ２００部

Tetrahydrofuran 200 parts

(Example 1)
A 5 μm protective layer containing 25 wt% of alumina fine particles (AA-03 manufactured by Sumitomo Chemical Co., Ltd., average particle size: 0.3 μm) was laminated as a protective layer on the above photoconductor to complete the photoconductor.
A polycarbonate similar to that used for the charge transport layer was used as the alumina fine particles and the binder, 30 wt% of the charge transport material of the structural formula (1) was contained, and a protective layer was laminated by a spray method.
Using the photoreceptor thus produced, durability was evaluated by the electrophotographic process shown in FIG.
In addition, as the external additive for the toner used, silica (manufactured by Clariant, H2000, 1 part, average particle diameter 0.01 μm) and another silica (manufactured by Shin-Etsu Chemical Co., Ltd., TSX53, 1 part, average particle diameter 0.15 μm) ) And titanium oxide (manufactured by Teika, MT150AI, 0.6 part, average particle size 0.015 μm) were used.
At this time, image exposure was 780 nm laser exposure, and charging was performed by applying AC (2 kHz, 1.8 kVpp) + DC (−750 V) to the charging roller.
The process speed of this process was 125 mm / s.
The output image remained almost unchanged with no change even after the initial and continuous feeding of 50,000 sheets, and no reduction in resolution was observed.
Further, the wear amount of the photoconductor after 50,000 continuous sheets passed was 2.1 μm, and no adhesion of foreign matter to the surface was observed by observation with a microscope 500 times.

(Example 2)
Durability was evaluated by an electrophotographic process in the same manner as in Example 1 except that the inorganic fine particles added to the photoreceptor protective layer of Example 1 were changed to the following.
Titanium oxide fine particles (manufactured by Ishihara Sangyo Co., Ltd., CR97, average particle size of 0.25 μm) were used as inorganic fine particles to be added to the protective layer, the addition amount was 20 wt%, and the thickness of the protective layer was 2 μm.
When the durability in the electrophotographic process was evaluated in the same manner as in Example 1, the output image was almost good even at the initial stage and after 50,000 continuous sheets.
Further, the wear amount of the photoconductor after 50,000 continuous sheets passed was 1.2 μm, and no foreign matter adhered to the surface as observed with a microscope 500 times.

(Comparative Example 1)
Instead of the toner used in Example 1, silica (Clariant, H2000, 2.4 parts, average particle size 0.01 μm) and titanium oxide (Taika, MT150AI, 0.6 parts, average) were used as external additives. Durability was evaluated by an electrophotographic process in the same manner as in Example 1 except that a material having a particle size of 0.015 μm) was used.
The output image was almost good in the initial stage, but some halftone unevenness was recognized after 10,000 sheets.
Further, the wear amount of the photoconductor after 50,000 continuous sheets passed was 1.6 μm, and when observed with a microscope 500 times, streaked foreign matter adhered to the surface. It was considered that the unevenness of halftone was caused by the adhesion of the foreign matter, and a characteristic that was clearly inferior with a decrease in resolution was recognized.

(Example 3)
As an external additive, the toner of Example 1 was prepared using silica (Clariant, H2000, 1.2 parts, average particle size 0.01 μm), and another silica (Nippon Aerosil, RX50, 1 part, average particle size 0). .04 μm) and titanium oxide (Taika, MT150AI, 0.6 parts, average particle size 0.015 μm) were used in the same manner as in Example 1 except that they were externally added. Evaluation was conducted.
The output image remained almost unchanged with no change even after the initial and continuous feeding of 50,000 sheets, and no reduction in resolution was observed.
Further, the wear amount of the photoconductor after 50,000 continuous sheets passed was 1.9 μm, and no adhesion of foreign matter to the surface was observed by observation with a microscope 500 times.

(Comparative Example 2)
Durability was evaluated by an electrophotographic process in the same manner as in Example 1 except that the inorganic fine particles added to the photoreceptor protective layer of Example 1 were changed to the following. As inorganic fine particles added to the protective layer, silica fine particles (manufactured by Shin-Etsu Chemical Co., Ltd., KMPX100, average particle size 0.1 μm) were used, the addition amount was 30 wt%, and the thickness of the protective layer was 5 μm.
Although the output image was good in the initial stage, slight density unevenness was observed after 10,000 sheets.
Further, the wear amount of the photoconductor after 50,000 continuous sheets passed was 4.5 μm, and it was confirmed that the roughness due to surface wear was large by observation with a microscope 500 times.

Example 4
As an external additive, the toner of Example 1 was prepared using silica (manufactured by Clariant, H1303, 1.2 parts, average particle size 0.012 μm), and another silica (manufactured by Shin-Etsu Chemical Co., Ltd., TSX63, 0.8 parts, average particles). In the same manner as in Example 1, except that the diameter was changed to 0.21 μm) and titanium oxide (Taika, MT150AI, 0.6 part, average particle diameter 0.015 μm) was added externally. Durability evaluation was performed.
The output image remained almost unchanged with no change even after the initial and continuous feeding of 50,000 sheets, and no reduction in resolution was observed.
Further, the wear amount of the photoconductor after 50,000 continuous sheets passed was 3.5 μm, and no adhesion of foreign matter to the surface was observed by observation with a microscope 500 times.

(Comparative Example 3)
In Example 3, durability was evaluated by an electrophotographic process in the same manner as in Example 3 except that no protective layer was provided on the photoreceptor.
When the durability in the electrophotographic process was evaluated in the same manner as in Example 3, the output image was almost good in the initial stage, but severe halftone unevenness was observed after 10,000 sheets.
In addition, the wear amount of the photoconductor after continuous feeding of 50,000 sheets was 2.1 μm. In observation with a microscope of 500 times, adhesion of oblong foreign matters having a size of about 10 μm was observed on the entire surface.

(Example 5)
As an external additive, the toner of Example 3 was prepared using silica (manufactured by Clariant, H2000, 1.2 parts, average particle diameter 0.01 μm) and another silica (manufactured by Nippon Aerosil Co., Ltd., RY50, 1 part, average particle diameter 0). .04 μm) and titanium oxide (Taika, MT150AI, 0.6 parts, average particle size 0.015 μm) were used in the same manner as in Example 3 except that they were externally added. Evaluation was conducted.
The output image remained almost unchanged with no change even after the initial and continuous feeding of 50,000 sheets, and no reduction in resolution was observed.
The abrasion amount of the photoconductor after 50,000 continuous sheets passed was 2.2 μm, and no foreign matter adhered to the surface when observed with a microscope 500 times.

1 is a schematic cross-sectional view of a multilayer electrophotographic photosensitive member used in the present invention. It is a schematic sectional drawing of the other laminated electrophotographic photosensitive member used for this invention. 1 is a schematic view showing an image forming method and an image forming apparatus of the present invention. FIG. 2 is a schematic diagram illustrating an example of a process cartridge for an image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Photosensitive layer 3 Charge generation layer 4 Charge transport layer 5 Protective layer 6 Photoconductor 7 Charger before transfer 8 Charger before cleaning 9 Charging member 10 Transfer belt 11 Image exposure part 12 Static elimination lamp 13 Development unit 14 Transfer paper 15 Fur brush 16 Cleaning blade 17 Registration roller 18 Separation claw 101 Photosensitive drum 102 Contact charging device 103 Image exposure 104 Developing device 105 Transfer body 106 Contact transfer device 107 Cleaning blade 108 Static elimination lamp 109 Fixing device

Claims (13)

An image forming method carried out by subjecting at least a photoreceptor to charging, image exposure, development, transfer, fixing and cleaning, wherein the photoreceptor has a protective layer containing inorganic fine particles made of alumina or titanium oxide, An image forming method, wherein the toner to be developed is formed by adhering two or more kinds of inorganic fine particles having different average particle diameters to the surface. The image forming method according to claim 1, wherein the photoconductor protective layer contains a charge transport material. 3. The image forming method according to claim 1, wherein an average particle diameter of the inorganic fine particles attached to the developed toner surface is smaller than an average particle diameter of the inorganic fine particles contained in the photoreceptor protective layer. . 4. The average particle size of the largest group of inorganic fine particles adhering to the toner surface to be developed is 3 to 20 times the average particle size of the smallest group. The image forming method described in 1. 5. The image forming method according to claim 1, wherein the charging means for the photosensitive member is disposed in contact with or in proximity to the photosensitive member. 6. The image forming method according to claim 5, wherein the charging member is charged by applying a voltage in which an alternating current component is superimposed on a direct current component to the charging member. An image forming apparatus having at least a charging unit, an image exposing unit, a developing unit, a transferring unit, a fixing unit, and a cleaning unit on a photoconductor, wherein the photoconductor has a protective layer containing inorganic fine particles made of alumina or titanium oxide. An image forming apparatus comprising: a developing unit configured to develop using toner having two or more kinds of inorganic fine particles having different average particle sizes attached to the surface thereof. The image forming apparatus according to claim 7, wherein the photoconductor protective layer contains a charge transport material. 9. The image forming apparatus according to claim 7, wherein an average particle size of the inorganic fine particles attached to the toner surface is smaller than an average particle size of the inorganic fine particles contained in the photoreceptor protective layer. 10. The average particle diameter of the largest group of inorganic fine particles attached to the toner surface is 3 to 20 times the average particle diameter of the smallest group. Image forming apparatus. The image forming apparatus according to claim 7, wherein the charging unit for the photosensitive member is disposed in contact with or close to the photosensitive member. 12. The image forming apparatus according to claim 11, wherein the charging member is charged by applying a voltage in which an alternating current component is superimposed on a direct current component to the charging member. A process cartridge comprising a photosensitive member and at least one of a charging unit, an image exposure unit, a developing unit, a transfer unit, a fixing unit, and a cleaning unit, and contains inorganic fine particles made of alumina or titanium oxide in a protective layer. A process cartridge for an image forming apparatus, comprising at least developing means for developing using a toner formed by attaching a photosensitive member and two or more kinds of inorganic fine particles having different average particle diameters to the surface.

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