JPH11202522A - Electrophotographic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-resolution electrophotographic image forming device equipped with an electrophotographic photoreceptor whose surface protecting layer is made to have an optically uniform state and to be free from light diffusion and bleeding, and which has both of mechanical characteristics such as low surface energy, hardness and strength and electrical durability such as arc-proof discharging and capable of preventing the occurrence of defective cleaning. SOLUTION: As for the electrophotographic copying device equipped with the electrophotographic photoreceptor with the photosensitive layer formed on a supporting body, an electrifying means, an image exposing means, a developing means, a transfer means and a cleaning means, the outermost surface layer of the photoreceptor is the surface protecting layer containing colloidal silica and siloxane resin, and the cleaning means consists of a cleaning blade, and the ratio of the hardness of the cleaning blade to that of the surface protecting layer is controlled to be 0.1 to 1.

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 apparatus having an electrophotographic photosensitive member having a surface protective layer, and more particularly, to a semiconductor laser or an LED.
The present invention relates to an electrophotographic image forming apparatus capable of stably obtaining an image with higher resolution than before, particularly a high-gradation full-color image using a conventional photograph or the like by a digital method using spot light using a conventional method.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors, of course, have required sensitivity, electrical characteristics, optical characteristics, and the like according to the electrophotographic process to be applied. The surface is directly subjected to an electrical or mechanical influence by a charging process such as corona charging and roller charging, a developing process, a transfer process, a cleaning process, and the like, so that the surface thereof is required to have durability.

More specifically, durability is required against abrasion and scratches on the surface of the photoreceptor due to rubbing, and deterioration of the surface of the electric photoreceptor, which is likely to occur during charging under high humidity. In particular, in a charging method using a discharge phenomenon such as a roller charging method, durability against high-energy arc discharge is required.

There is also a problem that toner adheres to the surface of the photoreceptor due to repetition of development and cleaning with the toner. For this purpose, improvement in the cleaning property of the surface of the photoreceptor is required.

[0005] In order to satisfy the various characteristics required for the photoreceptor surface as described above, attempts have been made to provide a surface protective layer mainly composed of various resins on the photosensitive layer. For example, JP-A-57-30843 proposes a protective layer in which resistance is controlled by adding metal oxide particles as conductive particles.

It has also been studied to improve the physical properties of the photoreceptor surface by adding various substances to the charge transport layer as well as the protective layer. For example, the following are reported as additives focusing on low surface energy of silicone resins.

[0007] Silicone oil (JP-A-61-1329)
No. 54), polydimethylsiloxane, silicone resin powder (JP-A-4-324454), crosslinked silicone resin, poly (carbonate silicon) block copolymer, silicone-modified polyurethane, silicone-modified polyester, thermosetting silicone resin (Tokuhei 5-46
No. 940) As a typical polymer having a low surface energy, there is a fluoropolymer, and the following can be added as the fluoropolymer.

[0008] Polytetrafluoroethylene powder, carbon fluoride powder

[0009]

However, a surface protective layer containing a metal oxide or the like can have a certain degree of hardness, but has a problem in cleaning properties because the surface energy tends to increase. Silicone resins are excellent in that they have low surface energy, but they do not show sufficient compatibility with other resins, so they tend to agglomerate in the added system, causing light scattering or bleeding and biasing the surface. There is a problem that stable characteristics are not exhibited. When the silicone resin alone is used, the hardness is insufficient,
When a solvent system that does not attack the photosensitive layer, for example, alcohol or water, is used, the surface energy of the silicone resin tends to be large, so that there is a problem in cleaning properties and the like.

In addition, since a fluorine-based polymer represented by polytetrafluoroethylene, which is a polymer having a low surface energy, is generally insoluble in a solvent and has poor dispersibility, it is difficult to obtain a smooth photoreceptor surface. Difficulty and low refractive index tend to cause light scattering, which causes a problem of deterioration of the latent image.

In addition, polymer compounds such as polycarbonate, polyacrylester, polyester, and polytetrafluoroethylene generally have insufficient arc discharge resistance, and are easily deteriorated because the polymer main chain is cut by discharge. There was a problem.

For this reason, in an electrophotographic photosensitive member having a photosensitive layer on a support, attempts have been made to provide a surface protective layer containing a siloxane resin containing colloidal silica as an outermost surface layer. Is extremely smooth, there has been a problem that the cleaning blade and the surface protective layer adhere to each other during cleaning in the electrophotographic process to cause defective cleaning.

An object of the present invention is to provide a surface protective layer which is free from light scattering and bleed and has an optically uniform state, and has low surface energy and mechanical properties such as hardness and strength. An object of the present invention is to provide a high-resolution electrophotographic image forming apparatus which is compatible with electric durability such as arc discharge property and does not cause cleaning failure.

[0014]

That is, the present invention relates to an electrophotographic photoreceptor having a photosensitive layer on a support, an electrophotographic apparatus having a charging unit, an image exposing unit, a developing unit, a transfer unit and a cleaning unit. The outermost surface layer of the photoreceptor is a surface protective layer containing colloidal silica and a siloxane resin, the cleaning means is a cleaning blade, and the hardness ratio of the cleaning blade to the surface protective layer is 0.1 to 1. An electrophotographic image forming apparatus characterized in that:

The siloxane resin described in the present invention means a silicone resin obtained by condensation of a silicon compound having three hydrolyzable groups such as an OH group and an OR group per silicon atom or a partially condensed oligomer.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The surface protective layer of the electrophotographic photosensitive member contains colloidal silica and a siloxane resin, and the composition for an electrophotographic photosensitive member surface protective layer used in the present invention is applied to the surface of the electrophotographic photosensitive member and dried. And formed by curing. The composition for an electrophotographic photosensitive member surface protective layer used in the present invention comprises at least the following three components (a) to (c). (A) Colloidal silica (b) Siloxane resin formed by partial condensation of R-Si (OR ') ₃ (where R is an alkyl group having 1 to 3 carbon atoms, a vinyl group, C _n F _{2n + 1} C ₂ H ₄ — group (n = 1 to 1)
8) represents at least one group selected from the group consisting of a γ-glycidoxypropyl group and a γ-methacryloxypropyl group. R 'represents at least one group selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 3 carbon atoms. (C) at least one solvent selected from the group consisting of lower aliphatic alcohols and water. The composition for a surface protective layer of an electrophotographic photoreceptor is a mixed solution of colloidal silica and a siloxane resin of 1 to 50% by weight of a lower alcohol-water. Those dispersed therein are preferred. If the solids content exceeds 50% by weight, the composition is liable to be deteriorated, and it is difficult to form a good coating film due to gelation or the like. If it is less than 1% by weight, the strength of the formed surface protective layer tends to be insufficient.

The proportion of colloidal silica in the solid content is preferably from 10 to 70% by weight, and the content of the siloxane resin is preferably from 30 to 90% by weight. If the ratio of the siloxane resin to the solid content is less than 30% by weight, the film tends to be brittle and a good film is not easily formed and cracks and the like tend to be easily formed. If the ratio of the colloidal silica is less than 10% by weight, the formed surface protective layer has Hardness tends to be insufficient.

As the colloidal silica, a commercially available aqueous dispersion type is used (trade names “Ludox” and “Na”).
lcoag "). The particle size is preferably from 5 to 150 nm, and from the viewpoint of dispersion stability and optical characteristics, from 10 nm to 30 nm.
nm is more preferable. As colloidal silica, the content of an alkali metal oxide such as Na ₂ O is preferably less than 2% by weight. As the dispersing solvent, a mixed solvent system of water and a lower aliphatic alcohol such as methanol, ethanol, isopropanol, t-butanol and n-butanol is preferable, but other water-soluble solvents such as glycol and acetone may be further added. Good.

The composition for the surface protective layer of the electrophotographic photoreceptor can be adjusted to pH 3.0 to 6.0 by using an inorganic acid or an organic acid.
It is preferably adjusted to an acidic state of 0. If a strong acid is used, the stability of the composition and the like are likely to be unfavorably affected.
Is adjusted to an acidic state.

The composition for the surface protective layer of the electrophotographic photosensitive member applied to the surface of the electrophotographic photosensitive member is dried and then heat-cured to exhibit hardness, strength, low surface energy and discharge resistance. Thermal curing proceeds more completely at higher temperatures,
It is selected in a range that does not adversely affect the characteristics of the electrophotographic photosensitive member. The thermosetting is preferably carried out at 80 to 180 ° C, more preferably at 100 to 150 ° C.

The longer the thermal curing time, the more the curing proceeds, but the thermal curing time is selected within a range that does not adversely affect the characteristics of the electrophotographic photosensitive member at the processing temperature. The heat curing treatment time is generally about 10 minutes to 12 hours.

After drying, the surface protective layer obtained by thermosetting contains at least a component represented by SiO ₂ as colloidal silica and a siloxane resin represented by RSiO _3/2 .

Here, R is an alkyl group having 1 to 3 carbon atoms,
Vinyl _{group, C n F 2n + 1 C} 2 H 4 - group (n = 1~18),
represents at least one group selected from the group consisting of a γ-glycidoxypropyl group and a γ-methacryloxypropyl group.

The thickness of the surface protective layer is preferably from 0.1 to 4 μm. If the thickness is less than 0.1 μm, the surface hardness and strength are not sufficient, and the durability tends to decrease. If the thickness exceeds 4 μm, the contrast potential formed by a latent image during development tends to deteriorate. More preferably, it is 0.2 to 3 μm.

The surface protective layer preferably has a low surface energy in order to satisfy the cleaning property and the stain resistance. The low surface energy measured by the contact angle of water is preferably 90 degrees or more. If the angle is less than 90 degrees, a charge product, toner, or falling off from paper is liable to adhere to the surface due to repeated use in the electrophotographic process, and deterioration of a latent image (image deletion) due to poor cleaning or a decrease in surface resistance is likely to occur. It is more preferably at least 95 degrees.

Further, as a feature of the surface protective layer, since it contains colloidal silica and a siloxane resin, an extremely high surface hardness can be obtained as compared with ordinary organic compounds. The surface hardness is appropriately selected from the balance with various physical properties depending on the content of the colloidal silica and the structure of the siloxane resin, and the pencil hardness of the film formed on the glass plate is preferably 5H or more. If it is less than 5H, the toner and paper powder used in the electrophotographic process are apt to cause scratches and scraping.

In the present invention, the hardness ratio of the cleaning blade of the cleaning device to the surface protective layer is 0.1.
It needs to be 1 to 1. Because the surface protection layer is very hard and smooth, if the polyurethane mainly used for the cleaning blade is very soft,
This is because the surface protective layer and the cleaning blade adhere to each other, resulting in poor cleaning.

Since the cleaning blade is generally made of a rubber-like resin, it is difficult to measure the pencil hardness. Therefore, each hardness is represented by Vickers hardness, and the measurement is performed by the Fisher scope H1.
The measurement was carried out by a 00V load automatic conversion type dynamic film hardness tester (trade name: Fisher Scope H100V, manufactured by Helmto Fisher Co., Ltd .; hereinafter, referred to as Fisher Scope). With this apparatus, elastic hardness when a certain load is applied and plastic hardness after removing the load can be measured. Elastic hardness was used as an index of hardness. When the hardness of the glass plate and the aluminum plate was measured using this apparatus, the elastic hardness was 8800 (N / mm ² ) and 930, respectively.
(N / mm ² ).

However, in the case of rubber, the hardness and the area of the contact surface are different due to the difference in the tensile strength at the time of mounting and the pressure applied to the photoreceptor. Performed under the same conditions.

The volume resistance of the surface protective layer is 1 × 10 ⁹ to 1 ×.
It is preferably 10 ¹⁵ Ωcm. 1 × 10 ⁹ Ωcm
If it is less than 1 × 10 ¹⁵ Ωcm, the charge of the latent image formed is liable to be diffused, and if it exceeds 1 × 10 ¹⁵ Ωcm, the charge cannot move sufficiently until development after exposure as an electrophotographic photoreceptor, and apparently the sensitivity is lowered. , The residual potential tends to be high.

In addition, the residual potential tends to increase not only due to the potential resistance but also due to the remaining hydrolyzable groups such as silanol groups. Preferably, the ratio of the hydrolyzable group in terms of SiOH group is 0.1% by weight or less, more preferably 0.01% by weight or less.

For the surface protective layer, a resin composition containing colloidal silica and a siloxane resin as essential components is used.
US Patent No. 4027073 and US Patent No. 39447
It can be produced by the method described in JP-A-02.

The silicone hard coat resin comprises a hydrolytic condensate of a polyfunctional organosilicon compound having a hydrolyzable group in the molecule. The greater the number of functional groups, the higher the strength, and the resulting resin becomes harder. Among them, 4
In the case of using colloidal silica in place of the functional organosilicon and using trifunctional organosilicon, the hardness is adjusted by adjusting the particle size of colloidal silica, the amount of colloidal silica added, and the hydrolytic condensation of the trifunctional organosilicon. A resin which is high and excellent in film forming properties can be obtained. A preferred colloidal silica has an average particle diameter of 5 to 150 nm, which is dispersed in a lower alcohol containing water within the above-described range, and a trifunctional organosilicon compound having a hydrolyzable group is acidified or alkalinized. It is produced by hydrolysis in the presence. After completion of the reaction, a lower alcohol, a curing catalyst, a leveling agent and the like are further added as necessary. This is coated on a plastic substrate by dip, spray, bar coating, spin coating, or the like. After removing the solvent, a coating is generally formed by heating and curing at 80 to 150 ° C. The curing temperature is preferably performed at a temperature equal to or lower than the thermal deformation temperature of the coated base plastic. The siloxane resin thus formed has a pencil hardness of several H-9.
H hardness can be exhibited. Depending on the applied substrate material, the hard coat resin may be subjected to a surface treatment with a silane compound called a silane coupling agent, or a chemical or physical method, for the purpose of improving adhesion to the substrate surface. It is common practice to modify the surface to improve adhesion.

An example of producing an electrophotographic photosensitive member having a surface protective layer according to the present invention will be described below.

As the support of the electrophotographic photosensitive member, any support can be used as long as it has conductivity. The support itself has conductivity, such as aluminum, aluminum alloy, copper, zinc, and the like. Stainless steel, chrome, titanium, nickel, magnesium, indium,
In addition to gold, platinum, silver and iron, aluminum, indium oxide, tin oxide, gold and the like are formed on a dielectric support such as plastic by vapor deposition or the like to form a conductive layer,
What mixed conductive fine particles with plastic or paper can be used. For these supports, uniform conductivity is required and a smooth surface is important. Since the surface smoothness greatly affects the uniformity of the undercoat layer, charge generation layer and charge transport layer formed thereon, the surface roughness is preferably 1.0 μm or less. Irregularities exceeding 1.0 μm change the local electric field applied to a thin layer such as an undercoat layer or a charge generation layer, so that the characteristics thereof greatly change, and defects such as charge injection and residual potential unevenness occur. Easy to occur. In particular, a conductive layer obtained by dispersing and applying conductive fine particles in a polymer binder is easy to form, and is suitable for forming a uniform surface. The primary particle size of the conductive fine particles used at this time is preferably 100 nm or less, more preferably 50 nm.
The following are used: As the conductive fine particles, conductive zinc oxide, conductive titanium oxide, Al, Au, Cu, A
g, Co, Ni, Fe, carbon black, ITO, tin oxide, indium oxide, indium and the like are used,
These may be used by coating the surface of the insulating fine particles. The content of the conductive fine particles is used so that the volume resistance is sufficiently low, and is preferably 1 × 10 ¹⁰ Ωcm.
It is added so as to have the following resistance. More preferably 1
It is used at × 10 ⁸ Ωcm or less.

When exposure is performed using a coherent light source such as a laser, it is possible to form irregularities on the surface of the conductive support in order to prevent image deterioration due to interference. At this time, irregularities of about 1 / 2λ of the wavelength used are dispersed at a period of 10 μm or less by dispersing an insulator such as silica beads having a diameter of several μm or less so that defects such as charge injection and unevenness of residual potential do not easily occur. It can be formed and used.

An undercoat layer having an injection blocking function and an adhesion function can be provided between the conductive support and the photosensitive layer.
The undercoat layer can be formed of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, polyamide, polyurethane, gelatin, or the like. The thickness of the undercoat layer is preferably 0.1 to 10 μm, more preferably 0.3 to 3 μm.

The photosensitive layer may be of a function-separated type comprising a charge generation layer and a charge transport layer, or a single layer type in which charge generation and charge transport are performed in the same layer.

As the charge generating material, for example, selenium
Tellurium, pyrylium dye, thiopyrylium dye, phthalocyanine pigment, anthantrone pigment, dibenzopyrenequinone pigment, pyranthrone pigment, trisazo pigment, disazo pigment, azo pigment, indigo pigment, quinacridone pigment and Cyanine pigments and the like are used.

The charge transporting compound is roughly classified into an electron transporting compound and a hole transporting compound.

As the charge transporting compound, 2,4,7-
Examples thereof include electron accepting compounds such as trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, chloranil, tetracyanoquinodimethane, and alkyl-substituted diphenoquinone, and those obtained by polymerizing these electron accepting compounds. . Examples of the hole transporting compound include polycyclic aromatic compounds such as pyrene and anthracene, heterocyclic compounds such as carbazole, indole, oxazole, thiazole, oxathiazole, pyrazole, pyrazoline, thiadiazole and triazole, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone and N, N
Hydrazone-based compounds such as -diphenylhydrazino-3-methylidene-9-ethylcarbazole, α-phenyl-
4'-N, N-diphenylaminostilbene and 5-
(4- (di-p-tolylamino) benzylidene) -5H
-Styryl compounds such as dibenzo (a, d) cycloheptene, benzidine compounds and triarylamine compounds or polymer compounds having a group consisting of these compounds in the main chain or side chain (poly-N-vinylcarbazole, polyvinyl Anthracene).

Next, specific examples of the charge transporting compound are shown below.

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[0078]

Embedded image As the charge generation material and the charge transporting compound, a binder polymer is used as necessary. Examples of the binder polymer include styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, polymers and copolymers of vinyl compounds such as vinylidene fluoride and trifluoroethylene, polyvinyl alcohol, polyvinyl acetal, polycarbonate, Examples include polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicon resin, epoxy resin and the like.

In particular, as the polymer compound for the charge transport layer used in the present invention, a compound compatible with the charge transport compound is used. Representative polymer compounds include polyester, polycarbonate, polystyrene, polymethacrylate, and polyacrylate.

The charge transporting compound used in the charge transporting layer is preferably 20 to 70% by weight based on the solid content of the charge transporting layer. When the content is less than 20% by weight, sufficient charge transfer ability is hardly obtained, so that the residual potential is likely to increase. If it exceeds 70% by weight, the mechanical strength of the charge transport layer tends to decrease, so that it is difficult to obtain sufficient durability.

The amount of the polymer compound used in the charge transport layer is preferably 20 to 80% by weight based on the solid content of the charge transport layer. If it exceeds 80% by weight, it is difficult to obtain sufficient charge transfer ability, so that an increase in residual potential, a decrease in electrical durability, a reduction in the effect of lowering surface energy, and the like are likely to occur. If it is less than 20% by weight, the mechanical strength of the charge transporting layer is reduced, so that it is difficult to obtain sufficient durability.

When used as a single-layer photoreceptor, good properties can be obtained by using a composition comprising a combination of the above-mentioned charge generating material, charge transporting compound and polymer compound.

Additives other than the above compounds can be used in the photosensitive layer in order to improve mechanical properties and durability. As such additives, an antioxidant, an ultraviolet absorber, a stabilizer, a crosslinking agent, a lubricant, a conductivity control agent, and the like are used.

On the photosensitive layer formed as described above, the above-mentioned surface protective layer used in the present invention is formed. The solvent used in the composition for forming the surface protective layer preferably does not attack the photosensitive layer, and is applied by a dip coating method, a blade coating method, a roll coating method, or the like. Even in the case where a solvent that attacks the photosensitive layer is used, the influence can be reduced by using the spray coating method.

FIG. 1 is a plan view showing a schematic cross section of the electrophotographic photosensitive member used in the present invention.

FIG. 2 is a schematic configuration diagram of an example of the image forming apparatus. The image forming apparatus of this example is a laser printer using an electrophotographic process.

Reference numeral 1 denotes a roller charger in contact with the photoreceptor, and the outer peripheral surface of the photoreceptor is charged to approximately -680V.

The charged photosensitive member is exposed to an exposure device 3
As a result, a laser beam corresponding to the image signal is irradiated, and a latent image is formed on the photosensitive drum 2. The latent image is magnetic 1
The reversal development is performed as a toner image by the reversal developing device 4 using the component insulating negative toner.

On the other hand, a transfer material P is supplied from a paper supply unit (not shown) as a recording material, and is introduced at a predetermined timing into a pressure nip (transfer portion) between the rotary photosensitive member 2 and the transfer roller 5. A transfer bias voltage is applied to the transfer roller 5. The transfer material P introduced into the transfer section is conveyed narrowly through the transfer section, and the toner image formed and carried on the surface of the photoreceptor 2 is sequentially transferred to the front side by electrostatic force and pressing force. . The transfer material P to which the toner image has been transferred is separated from the surface of the photoreceptor 2 and introduced into a fixing device of a heat fixing type (not shown) to fix the toner image and to form an image product (print or copy). It is discharged outside the device. The transfer residual toner present on the photoconductor 2 is scraped off by the cleaning device 6 to clean the photoconductor.

[Examples] Hereinafter, specific examples will be described.
The present invention will be described in more detail.

Example 1 30.0 g of an aqueous dispersion of colloidal silica (solid content 40% by weight) was placed in a flask,
While stirring, 1/3 of the whole mixture of 21.5 g of methyltrimethoxysilane and 3.5 g of acetic acid was added. After the addition, the mixed solution was heated to 55 ° C., and when a sudden heat generation was observed, the mixture was immediately cooled with ice, and the temperature in the flask was raised to 50 to 60 ° C.
And the remaining mixture was added. Reaction solution is 20
Cool to 0 ° C. and stir for 30 minutes when the temperature stabilizes. Thereafter, the reaction solution was diluted with 17.8 g of isopropyl alcohol, and 2.8 g of dibutyltin di-2-ethylhexoate was obtained.
Was slowly added, 2.4 g of benzyltrimethylammonium acetate was added as a curing catalyst, and 0.16 g of a 10% by weight solution of polyether-modified dimethyl silicone in ethanol was added. The resulting reaction mixture was free of precipitate.

(Example 2) The composition for a surface protective layer of Example 1 was applied to a glass plate using a bar coat, and dried and heat-treated at 110 ° C for 4 hours. After drying, a transparent and uniform film of 1 μm was obtained. Observation of the obtained sample with a microscope revealed that a uniform film was formed.

Further, this sample was subjected to a spectrophotometer for 60 minutes.
When the absorption at a wavelength of 0 nm was measured, the film thickness was 1 μm.
A value of 0.001 was obtained as the absorbance per unit, and the sample was transparent.

When the contact angle of water was measured, the surface energy was as low as 90 °, which is good. The pencil hardness was 9H, which was extremely hard, and the volume resistance measured with a comb electrode was 1 × 10 ¹⁵ Ωcm. there were.

When the Vickers hardness of this sample was measured with a Fisher scope, the elastic hardness was 14
It was 800 N / mm ² , which was extremely hard.

Next, an electrophotographic photosensitive member was prepared. An aluminum cylinder having an outer diameter of 30 mm formed by mirror finishing and having anodized aluminum formed by anodic oxidation was used as a conductive support.

Next, as a charge generating layer, 5 parts (by weight, hereinafter the same) of the following bisazo pigment was added to a solution prepared by dissolving 2 parts of polyvinyl benzal (a degree of benzalization of 75% by weight or more) in 95 parts of cyclohexanone. For 20 hours. This dispersion was applied on a conductive support by a dip coating method so that the film thickness after drying was 0.2 μm.

[0098]

Embedded image Next, 5 parts of a triarylamine compound having the following structural formula and 5 parts of a polycarbonate resin (trade name: Z-400, manufactured by Mitsubishi Gas Chemical Co., Ltd.) were added to tetrahydrofuran 70
The solution for the charge transport layer dissolved in the portion was dried on the charge generation layer by a dip coating method and then applied to a thickness of 12 μm.

[0099]

Embedded image Next, the composition of Example 1 was applied on the charge transport layer by a dip coating method, and dried and heat-treated at 110 ° C. for 4 hours to obtain a film thickness of 1.0 μm to prepare an electrophotographic photosensitive member. The Vickers hardness of this photoreceptor measured by a Fisher scope was 520 N / mm ² .

Electrophotographic characteristics were measured at a wavelength of 680 nm after charging at -700 V. As a result, E1 / 2 (exposure amount at which the charging potential decreases to -350 V) = 1.2 μJ / cm ² and a residual potential of 28 V were good. .

The electrophotographic photoreceptor was mounted on a Canon laser beam printer (roller charging system LBP-8, Mar
kIV). The cleaning blade was made of urethane rubber, was brought into contact with the drum surface at an angle of 22 degrees, and was pressed with a linear pressure of 50 g / cm. The elastic hardness of the cleaning blade in this state is 54 N / mm.
² , and the hardness ratio between the blade and the photoreceptor in this embodiment is 0.1.
It was one. An image output with excellent uniformity was obtained at the initial stage and after the 5,000-sheet durability test, and the cleaning property was also good. When the contact angle of water on the surface of the photoreceptor was measured, it was as good as 93 degrees after the 5000 sheet durability test, compared with 96 degrees at the beginning.

Comparative Example 1 An electrophotographic photosensitive member was manufactured in the same manner as in Example 2. The electrophotographic photoreceptor was installed in a Canon laser beam printer (roller charging system). At this time, the photoreceptor was brought into contact with the drum axis of the photoreceptor at an angle of 26 degrees, and the pressure of the cleaning blade pressed against the drum surface was 20 g /. cm. When the hardness of the cleaning blade under this condition was measured with a Fisher scope, it was 28 N / mm ² , and the hardness ratio between the blade and the photosensitive member was 0.056. Initial charging -60
When the image was evaluated at 0 V, an image output with excellent uniformity was obtained at the initial stage, and the gradation reproducibility was 2 at 400 dpi.
Although the gradation was very good at 56 gradations, when 1,000 sheets were output, the amount of transfer residual toner increased, and uneven charging due to poor cleaning caused image deterioration.

Comparative Example 2 An electrophotographic photosensitive member was manufactured in the same manner as in Example 2. This electrophotographic photosensitive member was installed in a Canon laser beam printer (roller charging system).
A silicon rubber blade was used as a cleaning blade, and the cleaning blade was brought into contact with the drum surface at an angle of 26 degrees, and the pressing pressure was set to 60 g / cm. When the hardness of the cleaning blade in this state was measured with a Fisher scope, it was 775 N / mm ² , and the hardness ratio between the blade and the photosensitive member was 1.55. Initial charging -60
When the image was evaluated at 0 V, a uniform image output was initially obtained, but the blade was turned up after 1200 sheets output due to a high hardness ratio, resulting in poor cleaning.

[0104]

As described above, the composition containing colloidal silica and siloxane resin is used as the surface protective layer of the photosensitive layer, and the hardness ratio between the cleaning blade and the surface protective layer is set to 0.1 to 1. Thus, an electrophotographic image forming apparatus having excellent abrasion resistance and cleaning properties has been realized.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an electrophotographic photoreceptor used in the present invention, in which a composition containing colloidal silica and a siloxane resin is used for a surface protective layer.

FIG. 2 is a schematic diagram of an electrophotographic image forming apparatus of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihiro Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masataka Kawahara 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Non Corporation (72) Inventor ▲ Yoshi ▼ Kazuo Naga 3-3-2 Shimomaruko, Ota-ku, Tokyo Canon Corporation

Claims (7)

[Claims] 1. An electrophotographic apparatus having an electrophotographic photoreceptor having a photosensitive layer on a support, a charging unit, an image exposing unit, a developing unit, a transfer unit and a cleaning unit, wherein the outermost surface layer of the photoreceptor is colloidal silica. An electrophotographic image forming apparatus, wherein the cleaning means is a cleaning blade, and a hardness ratio of the cleaning blade to the surface protective layer is 0.1 to 1. . 2. The electrophotographic image forming apparatus according to claim 1, wherein said photosensitive layer has a charge generation layer and a charge transport layer. 3. The electrophotographic image forming apparatus according to claim 1, wherein the contact angle of water of the surface protective layer is 95 degrees or more. 4. The surface protective layer has a volume resistance of 1 × 10 ^9.
The electrophotographic image forming apparatus according to claim 1, wherein the density is from 1 to 10 ¹⁵ Ωcm. 5. The following formula (I) RSiO _3/2 (I) wherein the surface protective layer is condensed in the presence of colloidal silica, wherein R is an alkyl group having 1 to 3 carbon atoms, a vinyl group, C
_{n F 2n + 1 C 2 H} 4 - group (n = 1~18), representing the γ- glycidoxypropyl group and γ- methacryloxypropyl least one group selected from the group consisting of propyl group. 2. The electrophotographic image forming apparatus according to claim 1, further comprising a compound represented by the formula: 6. The electrophotographic image forming apparatus according to claim 1, wherein the surface protective layer has a pencil hardness of 5H or more. 7. The thickness of the surface protective layer is 0.2 to 3 μm.
The electrophotographic image forming apparatus according to claim 1, wherein