JP2002023405A - Positive-chargeable electrophotographic photoreceptor, manufacturing method of the same, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive-chargeable electrophotographic photoreceptor capable of uniformly transferring a toner image by a stable nip pressure, and also, provided with high resolution, also, with improved cleaning characteristics, electrostatic charging characteristics and optical sensitivity, and to provide a method for manufacturing the photoreceptor, and to provide an image forming device. SOLUTION: The positive-chargeable electrophotographic photoreceptor is constituted by successively and cylindrically laminating a conductive foam body layer whose volume resistivity is <=107 Ω.cm and whose ASKER C hardness is 10 to 50 deg., a conductive surface layer constituted of conductive rubber whose volume resistivity is <=107 Ω.cm and whose hardness by JISK6301A is 30 to 70 deg., a conductive undercoat layer whose volume resistivity is <=107 Ω.cm and an organic photoreceptive layer on the rotary shaft, and the film thickness of the conductive foam body layer is controlled to be 3 to 15 mm, and the film thickness of the conductive surface layer is controlled to be 0.6 to 2 mm, and the ASKER C hardness from the conductive surface layer side of the conductive substrate constituted of the conductive foam body layer and the conductive surface layer is controlled to be 20 to 50 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positively charged electrophotographic photosensitive member, a method of manufacturing the same, and an image forming apparatus, which can secure a uniform developing nip pressure with a one-component contact developing roller and can stably transfer images. The present invention relates to a positively chargeable electrophotographic photoreceptor capable of enabling uniform transfer by a nip pressure, having high resolution, excellent cleaning characteristics, and excellent charging characteristics and photosensitivity, a method for manufacturing the same, and an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus, a photosensitive drum is rotatably supported on a main body of the image forming apparatus. During an image forming operation, an electrostatic latent image is formed on a photosensitive layer of the photosensitive drum. In a system in which an image is visualized using a one-component developer of a developing device, when the photosensitive drum is made of a rigid body, a very thin toner layer, for example, a toner layer having a thickness of one toner particle is provided on a developing roller. It is necessary to make contact with the surface of the photosensitive drum on which the latent image has been formed, or to face the photosensitive drum at a small interval. However, it is difficult to manufacture the photoconductor drum with high precision.If there is a slight distortion on the peripheral surface of the photoconductor drum or if there is a manufacturing variation, a large gap is formed between the drum and the developing roller. There is a problem that the image quality is deteriorated, and there is a problem that the drum surface is damaged when pressed. For this reason, techniques such as forming a photoreceptor into a belt and employing an intermediate transfer belt have been developed.
This requires two rollers, which is an obstacle to downsizing the copier.

[0003] For this reason, the development of a system in which an organic photosensitive layer is applied and formed on an elastic roller base to form a photosensitive drum and the surface of the photosensitive drum can be elastically deformed has been developed. For example, Japanese Patent Publication No. 4-69383 discloses that a photosensitive member support layer is fitted on a non-foamed or foamed elastic roller base such as rubber as an elastic roller base with a thin-film sleeve made of aluminum, nickel, stainless steel or the like. It is formed so that only the part where the external pressure acts on the drum is deformed but the other parts are not deformed, and it is possible to completely return to the original sleeve state when the external force is removed Has been described. The publication also discloses that a conductive rubber layer may be used as a photoreceptor support layer, but does not disclose a configuration suitable for an electrophotographic photoreceptor for positive charging.

When a conductive rubber layer is formed on the conductive foam layer, for example, by coating, the coating liquid penetrates into the conductive foam layer unless the foam diameter of the conductive foam layer is at least 20 μm or less. However, there is a problem that the elasticity of the conductive foam layer cannot be utilized due to curing, and even if applied, the smoothness of the surface of the applied layer is rough, and there is also a problem that it is difficult to form a toner image and perform cleaning after transfer. is there. In the case of an elastic photoreceptor, if the diameter of the photoreceptor is reduced, when exposure and development are simultaneously performed on the photoreceptor drum, distortion caused by pressure contact with the developing roller extends to the surface of the photoreceptor at the time of exposure. This causes a problem that the latent image formed on the surface of the photosensitive layer is disturbed, but the above-mentioned publication discloses specific teaching regarding the case where the conductive foam layer and the conductive rubber layer are combined. Absent.

On the other hand, as an electrophotographic photoreceptor, there is an electrophotographic photoreceptor for negative charging, which obtains an image output by charging the surface of the photoreceptor to a negative polarity. In addition, a large amount of ozone is generated due to the application of a negative high voltage to the corotron which gives a charge, which causes problems such as environmental problems and adverse effects on peripheral components in the electrophotographic apparatus. Therefore, the development of a positively charged electrophotographic photoreceptor is underway. There is a problem that the electrophotographic photoreceptor for use has poor charging characteristics and is not suitable for practical use.

Japanese Unexamined Patent Publication (Kokai) No. 63-70258 discloses an electrophotographic photoreceptor for positive charging in which a conductive substrate and an organic photosensitive layer are combined with each other in order to solve a decrease in charging potential due to charge injection from the conductive substrate. It discloses that by providing a metal layer having a large work function such as palladium or gold so as to form a barrier between the layers, charge injection into the photosensitive layer can be prevented, the charging potential can be increased, and dark decay can be reduced. There is a problem that it is not practical to provide a metal layer such as palladium and gold.

[0007] Japanese Patent No. 2855548 discloses that a conductive base material is made of a carbon-based conductive thermoplastic resin composition having a work function of 4.2 eV or more, and a charge generating material is made of an organic pigment. It discloses that positive charges on the surface of the photoreceptor are more easily injected into the conductive substrate than in the case of aluminum having a small function, and that a photoreceptor having excellent charging characteristics can be obtained. Is not disclosed. As described above, in the method of making the surface of the photosensitive drum elastically deformable, a photosensitive member suitable for positive charging has not yet been provided.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to secure a uniform developing nip pressure with a one-component contact developing roller, and to enable uniform toner image transfer with a stable nip pressure during transfer. Another object of the present invention is to provide a positively charged electrophotographic photosensitive member having high resolution, excellent cleaning characteristics, and excellent charging characteristics and photosensitivity, a method for manufacturing the same, and an image forming apparatus.

[0009]

According to the present invention, there is provided an electrophotographic photosensitive member for positive charging, comprising a conductive foam layer having a volume resistance of 10 ⁷ Ω · cm or less and an Asker C hardness of 10 to 50 degrees on a rotating shaft. ,
A conductive skin layer made of a conductive rubber having a volume resistance of 10 ⁷ Ω · cm or less and a hardness of 30 to 70 degrees according to JIS K6301A, a conductive undercoat layer with a volume resistance of 10 ⁷ Ω · cm or less, and an organic photosensitive layer. In the electrophotographic photosensitive member for positive charging, which is sequentially laminated in a cylindrical shape, the conductive foam layer has a thickness of 3 mm to 15 mm, and the conductive skin layer has a thickness of 0.6 mm to 2 mm. The Asker C hardness from the conductive skin layer side of the conductive substrate composed of the conductive foam layer and the conductive skin layer is set to 20 to 50 degrees.

Method for producing the electrophotographic photosensitive member for positive charging of the present invention
The method is that the volume resistance is 10 on the axis of rotation. ⁷Ω ・ cm or less
Conductor foam tube with Scar C hardness of 10 to 50 degrees
Cover to form a conductive foam layer with a film thickness of 3 to 15 mm
After the formation, the volume resistance is further reduced to 1 on the conductive foam layer.
0⁷Ω · cm or less, hardness according to JIS K6301A is 3
Coating a conductive rubber tube of 0 to 70 degrees with a film thickness
Forming a conductive skin layer of 0.6 mm to 2 mm;
Conductivity of conductive substrate consisting of foam layer and conductive skin layer
Asker C hardness from the skin layer side is 20 degrees to 50 degrees,
Next, a conductive subbing layer and an organic photosensitive layer are formed on the conductive skin layer.
Are sequentially applied and formed.

An image forming apparatus according to the present invention is an image forming apparatus for transferring a toner image formed on a photoreceptor onto an intermediate transfer member, and transferring and fixing the toner image on the intermediate transfer member onto a material to be transferred. The photoreceptor has a volume resistance of 10 on the rotation axis.
Conductive foam layer of Asker C hardness of 10 to 50 degrees below ^{7 Ω} · cm, JISK volume resistivity is less 10 ⁷ Ω · cm
A conductive skin layer made of conductive rubber having a hardness of 30 ° to 70 ° according to 6301A, a conductive undercoat layer having a volume resistance of 10 ⁷ Ω · cm or less, and an organic photosensitive layer are sequentially laminated in a cylindrical shape. The film thickness of the permeable foam layer is 3 mm to 15 mm,
The conductive skin layer has a thickness of 0.6 to 2 mm, and has an Asker C hardness of 20 degrees from the conductive skin layer side of the conductive substrate including the conductive foam layer and the conductive skin layer. ~
It is an electrophotographic photosensitive member for positive charging at 50 degrees.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 are views for explaining a cross section of a positive charging electrophotographic photosensitive member having a different rotation axis in the positive charging electrophotographic photosensitive member of the present invention. FIG. 1 shows a case where the rotating shaft is a metal shaft, and FIG.
FIG. 3 shows a case where the rotating shaft allows the metal pipe 2 to rotate through the bush 3.
This is a case where a photoconductor in which a conductive skin layer, a conductive subbing layer, and an organic photosensitive layer are sequentially laminated is rotatable via the flange 4. 1 to 3, 1 is a metal shaft, 2 is a metal pipe, 3
Is a bush, 4 is a flange, 5 is a conductive foam layer, 6 is a conductive skin layer, 7 is a conductive subbing layer, and 8 is an organic photosensitive layer.

The electrophotographic photosensitive member for positive charging of the present invention will be described.

When the rotating shaft shown in FIG. 1 is the metal shaft 1, the metal shaft 1 is exemplified by a metal shaft made of iron or aluminum having a diameter of 6 mm to 20 mm. A member for rotatably supporting the main body of the forming apparatus.

When the metal pipe 2 shown in FIG. 2 is used, a metal sleeve made of a material such as aluminum or iron,
For example, an iron pipe (STKM, φ28.6 mm, thickness 1.
2 mm), and the bush 2 is a member for rotatably supporting the electrophotographic photosensitive member on the main body of the image forming apparatus, and a material such as free-cutting steel (SUM) is used. Inserted into the pipe 1 by press fitting or friction welding, etc.
Fixed.

The photosensitive member shown in FIG. 3 has a conductive foam layer, a conductive skin layer, a conductive undercoat layer (not shown in FIG. 2) and an organic photosensitive layer on the metal pipe 2 of FIG. A metal flange 4 is provided at both ends of a photoconductor in which layers (not shown because it is the same as in FIG. 2) are sequentially laminated, and the metal flange 4 is pressed against each part of the end of the photoconductor. The photosensitive member can be driven to rotate by a drive shaft (not shown) fixed to the flange. This makes it possible to transmit the rotational force directly to each part through the flange. Therefore, when a hard roller, for example, a metal developing roller 11 having a roughened surface is brought into contact with the photoconductor, pressure contact development is performed. The effect of the twist of the conductive foam layer on the photoreceptor can be reduced, and the deterioration of image quality can be reduced.

The conductive foam layer 5 has a volume resistance of 10 ⁷ Ω · cm in which carbon black, metal powder and the like are kneaded.
Or less, preferably 5 × 10 ⁶ Ω · cm or less.
It is composed of foam such as propylene-diene rubber (EPDM rubber), silicon rubber, CR rubber, NBR rubber, SBR rubber, IIR rubber, and has Asker C hardness of 10 to 50.
The conductive foam tube having a thickness of 8 mm to 20 mm is press-fitted and fixed to the rotating shaft in FIGS. 1 to 3 and then ground and polished to a thickness of 3 mm to 15 mm.
The conductive foam tube may be formed by extrusion molding by a known method by extrusion molding. The inner diameter of the tube may be made slightly smaller than the outer diameter of each of the metal shaft 1 and the metal pipe 2 so that the metal shaft is formed. 1, or the metal pipe 2 can be fixed with increased adhesion, and a special adhesive can be eliminated. When an adhesive is used, a normal rubber-based adhesive may be used within a range that does not affect electric resistance.

As the conductive foam, silicone rubber, EPDM rubber, CR,
Rubber foams are preferred, and EPDM rubber foams are particularly preferred. The foamed shape of the conductive foam is, for example, a single bubble state or a continuous bubble state in which cells having a diameter of 100 μm to 800 μm are independent from each other, and the number of cells is preferably 32 / inch to 254 / inch.

The conductive skin layer 6 is made of conductive rubber.
As conductive rubber, a volume resistance of 10 ⁷ Ω · cm or less,
Preferably, the conductive rubber is 5 × 10 ⁶ Ω · cm or less. Examples thereof include silicon rubber, EPDM rubber, CR rubber, NBR rubber, SBR rubber, and IIR rubber into which carbon black, metal powder, and the like are kneaded. C. or higher, rubber hardness of 30 to 7 according to JIS K6301A
Silicon rubber, EPDM rubber, and CR rubber are preferred from the viewpoint of being in the range of 0 degrees, being excellent in workability, being excellent in solvent resistance, and the like.

The conductive rubber layer is formed by pressing and fixing a conductive rubber tube having a single-layer thickness of 1 mm to 4 mm onto the conductive foam layer pressed onto the metal shaft 1 or the metal pipe 2 prepared above. After that, the one-sided film was ground and polished to a thickness of 0.6 mm to 2 mm. The conductive rubber tube may be molded by a known method by extrusion molding, but the inner diameter of the conductive rubber tube may be slightly smaller than the outer diameter of the conductive foam layer laminated on the rotating shaft, so that the conductive foam is formed. The layer can be fixed with high adhesion to the layer, and a special adhesive can be eliminated. When an adhesive is used, a normal rubber-based adhesive may be used within a range that does not affect electric resistance. The outer surface of the conductive rubber layer 3 may have a surface roughness (Ra) of about 0.2 μm to 2 μm and a surface roughness (Rmax) of 10 μm or less by cutting or polishing. Accordingly, even when the thickness of the organic photosensitive layer is set to 15 μm to 40 μm, it is possible to eliminate potential unevenness at the time of exposure and soiling at the time of development.

As will be described later, a conductive undercoat layer and an organic photosensitive layer are provided on the conductive skin layer. The conductive skin layer is applied to a coating solution for forming the conductive undercoat layer and the organic photosensitive layer. On the other hand, it is good to have solvent resistance. In addition, the coating liquid used for forming the conductive undercoat layer or the organic photosensitive layer penetrates and deteriorates the photosensitive performance and the conductive foam layer when applied directly on the conductive foam layer. However, by forming a conductive skin layer on the conductive foam layer, there is an advantage that the conductive skin layer acts as a barrier layer.

The electrophotographic photoreceptor for positive charging according to the present invention is characterized in that a laminated structure comprising the above-mentioned conductive foam layer and conductive skin layer is used as a conductive substrate. The layer and the conductive skin layer are each appropriately selected in film thickness and hardness and laminated, and the conductive substrate has a single film thickness of 3 mm to 15 mm.
mm.

The Asker C hardness of the conductive substrate from the conductive skin layer side is preferably 20 to 50 degrees, more preferably 22 to 40 degrees. If the Asker C hardness is lower than 20 degrees, there is a problem of displacement due to rotational stress, and if it exceeds 50 degrees, there is a problem that the rotational load due to the contact depth increases. Further, the permanent compression strain can be set to 40% or less, preferably 30% or less.

As shown in FIG. 5, a developing roller (DR) comprising a positively charged electrophotographic photosensitive member (OPC) and a rigid body
When the developing roller shaft load is set to 1.0 kgf / cm to 2.2 kgf / cm, the amount of deformation (digging amount) in the radial direction of the photosensitive member is set to 0.1 mm to
It can be in the range of 0.4 mm.

According to the electrophotographic photosensitive member for positive charging of the present invention, only the vicinity of the pressure contact portion with the developing roller can be deformed, and a uniform developing nip pressure with the one-component contact developing roller can be secured. Further, at the time of transfer, a uniform toner image can be transferred by a stable nip pressure.
A photoconductor having high resolution and excellent cleaning characteristics can be obtained.

On the conductive skin layer of the conductive substrate,
It is preferable to form a conductive undercoat layer 7 for the purpose of preventing a decrease in the sensitivity of the photosensitive layer. The conductive undercoat layer is preferably solvent-resistant to a solvent of an organic photosensitive layer coating solution described later. Good.

Such a conductive undercoat layer is made of a polyamide resin, a polyvinyl butyral resin, a urethane resin, acetyl cellulose, methyl cellulose, ethyl cellulose, benzyl cellulose, hydroxyethyl cellulose, or the like, and a conductive substance and a solvent. The conductive thermoplastic resin composition is formed on the conductive skin layer by coating. The conductive undercoat layer is preferably excellent in adhesiveness with the conductive skin layer and also excellent in flexibility, and when using the EPDM rubber as the conductive skin layer, a polyamide resin, a polyvinyl butyral resin, and a urethane resin are preferable. .

As polyamide resins, "FR-101", "FR-104", and "FR-10" manufactured by Lead City Co., Ltd.
5 "," FR-301 "," CM400 "manufactured by Toray Industries, Inc.
0 "," CM8000 "and the like. Examples of the polyvinyl butyral resin include “BL-1”, “BL-2”, and “B” of “SREC B” manufactured by Sekisui Chemical Co., Ltd.
LS "and" BM-1 ". Examples of the urethane resin include a polyether urethane resin, a polyester urethane resin, and a polycarbonate urethane resin.

Examples of the conductive substance include conductive carbon, conductive silica, and conductive titanium. As conductive carbon, furnace black is preferable because it has few impurities and excellent conductivity, and among them, XCF (Extra
Conductive Furnace Black), SCF (Super Conductiv
e Furnace Black), CF (Conductive Furnace Black)
, SAF (Super Abrasion Furnace Black) is preferable, and a BET specific surface area by nitrogen gas adsorption is preferably 80 or more.
Those having 0 m ² / g or more are preferred. XCF includes "Ketjen Black EC" from Ketjen Black International and "Vulcan XC-72" from Cabot.
For example, Cabot's "Vulcan SC"
"Vulcan P", Degussa's "Colux L", etc. CF is Cabot's "Vulcan C"
Columbian's "Conductex S"
As examples of SAF, "Asahi # 9" by Asahi Carbon Co., "Diablack A" by Mitsubishi Chemical Corporation, "Vulcan 9" by Cabot Co., etc., and a mixture thereof may be used.
When the carbon black content is 50% or more, the carbon black as a whole has a BET specific surface area of 750 m ² / g or more, preferably 800 m ² / g by nitrogen gas adsorption.
As described above, in particular, at least 900 m ² / g, other carbon black such as acetylene black may be used in combination. The conductive substance is added in an amount of 2 parts by weight to 35 parts by weight, preferably 4 parts by weight to 25 parts by weight, based on 100 parts by weight of the resin. In addition, a polymer dispersant, an antioxidant, and the like are appropriately added. Contained.

As the solvent, those having no solubility in the conductive skin layer are preferable.
When made of rubber, water, methanol, ethanol,
Butyl alcohol, methyl ethyl ketone, propylene glycol and the like are exemplified, and when composed of CR rubber, water, methanol, ethanol, butyl alcohol,
Propylene glycol and the like are exemplified, and the above components are mixed and dispersed using a paint shaker, a sand mill, a ball mill, or the like to obtain a conductive undercoat layer forming composition.

The composition for forming a conductive undercoat layer is applied by dip coating, ring coating, spray coating or the like, and has a film thickness after drying of 3 μm to 20 μm, preferably 5 μm.
m to 15 μm, and a volume resistance of 10 ⁷ Ω · cm or less,
Preferably, the conductive undercoat layer has a flexibility of 5 × 10 ⁶ Ω · cm or less.

The conductive undercoat layer may be provided on the conductive skin layer via an insulating layer, if necessary, for the purpose of smoothing the surface of the conductive skin layer. The insulating layer may be formed using a composition for forming an insulating layer composed of the resin and the solvent described in the above-described conductive undercoat layer, and the thickness of the insulating layer is obtained by subjecting the photoreceptor to image exposure. It is formed by applying a flexible film having a thickness of, for example, 0.1 μm to 0.2 μm after drying, which enables easy charge transfer under an electric field generated at the time.

The organic photosensitive layer 8 provided on the conductive undercoat layer can be formed by using a so-called function-separated type photoconductor in which a charge generation layer and a charge transport layer are sequentially laminated on the conductive undercoat layer. Although good, a single-layer photoreceptor is preferred from the viewpoint of long life. The single-layer organic photoreceptor layer comprises a charge generator, a charge transport agent, a sensitizer, and the like, and a binder.

Examples of the charge generator include phthalocyanine pigments, azo pigments, quinone pigments, perylene pigments, quinocyanone pigments, indigo pigments, bisbenzimidazole pigments, and quinacridone pigments, and preferably phthalocyanine pigments. And azo pigments. Examples of the charge transport agent include hydrazone-based, stilbene-based, phenylamine-based, arylamine-based, diphenylbutadiene-based, and oxazole-based organic hole-transporting compounds. Examples of the sensitizer include various electron-withdrawing organic compounds. Examples thereof include paradiphenoquinone derivatives, naphthoquinone derivatives, and chloranil, which are also known as electron transporting agents. Examples of the binder include thermoplastic resins such as a polycarbonate resin, a polyarylate resin, and a polyester resin.

The composition ratio of each component is 40% by weight of a binder.
To 75% by weight, a charge generator of 0.5% to 20% by weight,
10% to 50% by weight of a charge transport agent, 0.5% to 30% by weight of a sensitizer, preferably 45% to 65% by weight of a binder, 1% to 20% by weight of a charge generator, and charge transport. 20% by weight to 40% by weight of sensitizer, 2% by weight to 2% by weight of sensitizer
5% by weight. Each component is pulverized, dispersed and mixed together with an organic solvent such as toluene and methyl ethyl ketone by a stirrer such as a homomixer, a ball mill, a sand mill, an attritor, and a paint conditioner to obtain a coating liquid. The coating solution is applied and dried by a dip coating, a ring coating, a spray coating, or the like to have a dried film thickness of 15 μm to 40 μm, preferably 20 μm to 35 μm.

The electrophotographic photosensitive member for positive charging of the present invention thus formed has an outer diameter of 2 in the case shown in FIG.
It is preferable that the outer diameter is 0 mm to 30 mm, and the outer diameter is 30 mm to 80 mm in the case shown in FIGS.

The work function (φ) defining the electrophotographic photoreceptor of the present invention is determined by using a surface analyzer (A manufactured by Riken Keiki Co., Ltd.)
C-1). The work function (φ _R ) of the conductive foam layer is determined by the type of the resin constituting the foam,
It can be changed by the composition, and can be changed from 4.4 eV to 4.9.
eV, preferably 4.5 eV to 4.8 eV.

The work function (φ _Is ) of the conductive rubber layer can be changed depending on the type and composition of the conductive rubber.
5 eV to 5.0 eV, preferably 4.6 eV to 4.9 e
V is recommended. In the case of EPDM rubber (ethylene-propylene-diene rubber), the work function in the above range can be obtained by changing the ratio of constituent monomer components and the molecular weight.

The work function (φ _UCL ) of the conductive undercoat layer is set to 4.6 eV to 5.7 eV, preferably 4.7 eV to 5.5 eV.

The work function of the organic photosensitive layer (φ _Opc )
Is 4.0 eV to 5.6 eV, preferably 4.2 eV.
eV to 5.5 eV. In the present invention, the work function in each layer _{preferably satisfies} the following relationship at the same time: φ _UCL > φ _Opc φ _UCL > φ _Is > φ _R , whereby the charging potential is high and the photo-decay residual potential is simultaneously And an electrophotographic photoreceptor for positive charging which is low in photosensitivity and excellent in photosensitivity.

In general, a structure in which layers having different work functions are stacked has an electron injecting property from a layer having a small work function to a layer having a large work function. The detailed reason for the electrophotographic photoreceptor for positive charging of the present invention is unknown, but when the surface of the organic photosensitive layer is positively charged, in the dark, φ _UCL > φ _Opc to make the electroconductive layer conductive. Electron injection from the conductive undercoat layer to the organic photosensitive layer can be suppressed, and the injection of negative charges induced in the conductive substrate composed of the conductive foam layer and the conductive skin layer is suppressed. It is considered that the positive chargeability of the photosensitive layer surface is improved.

At the time of exposure, φ _UCL > between the conductive undercoat layer, the conductive skin layer, and the conductive foam layer.
Due to the relation of φ _Is > φ _R , electrons can be injected from the conductive foam layer or the conductive skin layer to the conductive subbing layer, so that holes, which are carriers generated in the organic photosensitive layer,
Recombination with negative charges induced on the back side of the substrate can be facilitated, and an electrophotographic photoreceptor having a low light-decay residual potential and improved photosensitivity is considered.

Next, the image forming apparatus of the present invention will be described. FIG. 4 is a diagram showing one configuration example of an image forming apparatus equipped with a developing device according to the present invention.
This is an apparatus that can form a full-color image using a developing device using four colors of toner (developer) including yellow Y, cyan C, magenta M, and black K.

In FIG. 4, reference numeral 100 denotes an image carrier cartridge having an image carrier unit incorporated therein. In this example, the photosensitive member cartridge is configured as a photosensitive member cartridge, and the positively charged electrophotographic photosensitive member (latent image carrier) 140 of the present invention is rotationally driven in a direction indicated by an arrow in FIG. Around the photoreceptor 140, along a rotation direction thereof, a charging roller 160 as a charging unit, a developing device 10 (Y, M, C, K) as a developing unit, an intermediate transfer device 30,
And a cleaning unit 170.

The charging roller 160 contacts the outer peripheral surface of the photoconductor 140 and uniformly charges the outer peripheral surface. On the outer peripheral surface of the uniformly charged photoconductor 140, a selective exposure L1 according to desired image information is performed by the exposure unit 40, and an electrostatic latent image is formed on the photoconductor 140 by the exposure L1. . The electrostatic latent image is developed by applying a developer by the developing device 10.

As a developing device, a developing device 10 for yellow is used.
Y, Magenta developing device 10M, Cyan developing device 10
A developing device 10K for C and black is provided. These developing units 10Y, 10C, 10M, and 10K are:
Each of them is configured to be swingable, and only the developing roller (developer carrier) 11 of one developing device is selectively
40 can be pressed against. Therefore, these developing units 10 apply any one of the toners of yellow Y, magenta M, cyan C, and black K to the photoconductor 14.
0 to develop the electrostatic latent image on the photoconductor 140. The developing roller 11 is formed of a hard roller, for example, a metal roller having a roughened surface. The developed toner image is transferred onto the intermediate transfer belt 36 of the intermediate transfer device 30. After the transfer, the cleaning unit 170
The cleaner includes a cleaner blade for scraping off the toner T remaining on and adhering to the outer peripheral surface of the photoconductor 140, and a receiving portion for receiving the toner scraped off by the cleaner blade.

The intermediate transfer device 30 includes a driving roller 31 and
Four driven rollers 32, 33, 34, 35 and an endless intermediate transfer belt 36 stretched around these rollers.
And The drive roller 31 has a gear (not shown) fixed to an end thereof and the drive gear 19 of the photoconductor 140.
0, the photosensitive drum 140 is driven to rotate at substantially the same peripheral speed as the photosensitive member 140.
6 is driven to circulate at substantially the same peripheral speed as the photoconductor 140 in the direction of the arrow shown in the figure.

The driven roller 35 is disposed at a position where the intermediate transfer belt 36 is pressed against the photosensitive member 140 by its own tension with the driving roller 31.
A primary transfer portion T1 is formed at a pressure contact portion between the intermediate transfer belt 36 and the intermediate transfer belt 36. The driven roller 35 is disposed near the primary transfer portion T1 on the upstream side in the circulation direction of the intermediate transfer belt 36.

The driven roller 31 has an intermediate transfer belt 36
A primary transfer voltage is applied to the conductive layer of the intermediate transfer belt 36 via the electrode roller (not shown). The driven roller 32 is a tension roller, and urges the intermediate transfer belt 36 in the tension direction by an urging means (not shown). The driven roller 33 is a backup roller that forms the secondary transfer portion T2. A secondary transfer roller 38 is opposed to the backup roller 33 via an intermediate transfer belt 36. A secondary transfer voltage is applied to the secondary transfer roller 38, and the secondary transfer roller 38 can be moved toward and away from the intermediate transfer belt 36 by a contact / separation mechanism (not shown). The driven roller 34 is a backup roller for the belt cleaner 39. The belt cleaner 39 includes a cleaner blade 39a that comes into contact with the intermediate transfer belt 36 and scrapes off the toner remaining on and attached to the outer peripheral surface thereof, and a receiving portion 39b that receives the toner scraped off by the cleaner blade 39a. ing. The belt cleaner 39 can be moved toward and away from the intermediate transfer belt 36 by a contact / separation mechanism (not shown).

The intermediate transfer belt 36 is composed of a multi-layer belt having a conductive layer and a resistance layer formed on the conductive layer and pressed against the photoconductor 140. The conductive layer is formed on an insulating substrate made of a synthetic resin, and a primary transfer voltage is applied to the conductive layer via the above-described electrode roller. The conductive layer is exposed in the form of a strip by removing the resistive layer in the form of a strip at the side edge of the belt, and the electrode roller comes into contact with the exposed portion.

In the course of circulating the intermediate transfer belt 36, the toner image on the photosensitive member 140 is transferred onto the intermediate transfer belt 36 in the primary transfer section T1, and the toner image transferred onto the intermediate transfer belt 36 is Is transferred to a sheet (recording material) S such as paper supplied between the secondary transfer roller 38 and the secondary transfer unit T2. The sheet S is fed from the sheet feeding device 50, and is supplied to the secondary transfer portion T2 at a predetermined timing by the gate roller pair G. 51 is a paper feed cassette, and 52 is a pickup roller.

The sheet S to which the toner image has been transferred in the secondary transfer portion T2 passes through the fixing device 60, where the toner image is fixed, and is formed on the case 80 of the apparatus main body through the paper discharge path 70. The sheet is discharged onto the received sheet receiving portion 81. In this image forming apparatus, as a paper discharge path 70,
It has two paper discharge paths 71 and 72 independent of each other, and the sheet that has passed through the fixing device 60 is discharged through one of the paper discharge paths 71 or 72. The paper discharge paths 71 and 72 also constitute a switchback path.
When an image is formed on both sides of a sheet, the discharge path 71
Alternatively, the sheet once entering the sheet 72 is fed again to the secondary transfer portion T2 through the return path 73.

The outline of the operation of the entire image forming apparatus as described above is as follows. (1) When a print command signal (image formation signal) from a host computer (not shown) (personal computer or the like) (not shown) is input to the control unit 90 of the image forming apparatus, the photosensitive member 14
0, each roller 11 of the developing device 10 and the intermediate transfer belt 36 are driven to rotate. (2) The outer peripheral surface of the photoconductor 140 is uniformly charged by the charging roller 160. (3) The outer peripheral surface of the uniformly charged photoconductor 140 is subjected to selective exposure L1 according to the image information of the first color (for example, yellow) by the exposure unit 40 to form an electrostatic latent image for yellow. Is done. (4) Only the developing roller of the developing unit 10Y for the first color, for example, yellow, contacts the photoconductor 140, whereby the electrostatic latent image is developed, and the yellow toner image of the first color is changed to the photoconductor. 140 is formed. (5) A primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the intermediate transfer belt 36, and the toner image formed on the photoconductor 140 is transferred onto the intermediate transfer belt 36 in the primary transfer portion T1. Is done. At this time, the secondary transfer roller 38 and the belt cleaner 39
6 away. (6) After the toner remaining on the photoconductor 140 is removed by the cleaning unit 170, the photoconductor 140 is neutralized by the neutralization light L2 from the neutralization unit 41. (7) The above operations (2) to (6) are repeated as necessary. That is, according to the content of the print command signal,
The second color, the third color, and the fourth color are repeated, and a toner image corresponding to the content of the print command signal is formed on the intermediate transfer belt 36.
It is formed by being superposed on the top. (8) The sheet S is fed from the sheet feeding device 50 at a predetermined timing, and immediately before or after the leading end of the sheet S reaches the secondary transfer portion T2 (in short, at a desired position on the sheet S, the intermediate transfer is performed). When the toner image on the belt 36 is transferred, the secondary transfer roller 38
6, the secondary transfer voltage is applied, and the toner image on the intermediate transfer belt 36 (basically, a full color image in which four color toner images are superimposed) is transferred onto the sheet S. Further, the belt cleaner 39 comes into contact with the intermediate transfer belt 36, and the toner remaining on the intermediate transfer belt 36 after the secondary transfer is removed. (9) The toner image is fixed on the sheet S by passing the sheet S through the fixing device 60, and thereafter, the sheet S is directed to a predetermined position (in the case of non-double-sided printing, the sheet S is directed to the sheet receiving portion 81 to perform double-sided printing). In the case of (1), the sheet is conveyed to the return path 73 via the switchback path 71 or 72).

In the image forming apparatus according to the present invention, the photosensitive member 1
The developing roller 11 and the intermediate transfer medium 36 are brought into contact with 40. The electrophotographic photoreceptor for positive charging according to the present invention uses a photosensitive drum as a conductive substrate comprising a conductive foam layer and a conductive skin layer, and combines a flexible conductive foam layer and a hard conductive skin layer. By setting the Asker C hardness from the conductive skin layer side of the conductive substrate to 20 degrees to 50 degrees,
Only the portion where the external pressure is applied by the developing roller 11 or the intermediate transfer medium 36 is deformed, but the other portions are not deformed, and it is possible to completely return to the original sleeve state when the external force is removed. This is possible, and there is no problem such as damaging the drum surface even when pressed.
The intermediate transfer medium 13 may be formed of a rigid body or an elastic body.

Further, the image forming apparatus of the present invention can
Conductive foam layer and conductive skin layer as electrophotographic photoreceptor
On the conductive substrate consisting of, following the conductive substrate
A structure in which a conductive undercoat layer and an organic photosensitive layer are sequentially laminated
And the work function of the conductive foam layer is φ_R, Conductive skin
The work function of the layer is φ_Is, The work function of the conductive underlayer is φ
_UCL, Work function of organic photosensitive layer φ_OpcAnd the following
  , Formula φ_UCL> Φ_Opc φ_UCL> Φ_Is > Φ_R High charge by satisfying the relationship of
Potential is obtained, and the light attenuation residual potential is low.
An image forming apparatus that can be improved.

[0056]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. (Example 1) An electrophotographic photosensitive member for positive charging of the present invention will be described with reference to FIG. In FIG. 3, the metal pipe 2 is φ35 m
m (outer diameter), 1.5 mm thick aluminum pipe (6063
The inside of the pipe is subjected to a spigot process for the insertion portion of the flange 4. The flange 4 is a die-cast product made of aluminum and is pressed into a metal pipe. At the center of the flange 4 is formed a hole through which the rotary drive shaft passes.

(Formation of Conductive Foam Layer) A conductive EPDM foam tube formed by extrusion molding into a tubular shape (manufactured by Kuraray Plastics Co., Ltd.), φ30 mm (inner diameter), single-layer thickness 10 mm, volume resistance 1 0.7 × 10 ³ Ω · c
m, Asker C hardness 40 degrees, average foam cell diameter 260 μm
After press-fitting the cell number 98 / inch 2 onto the metal pipe 2 obtained above, the surface thereof is polished to obtain a single film thickness of 5 / cell.
mm of a conductive foam layer was formed. The work function of the conductive foam layer was measured using a surface analyzer (AC- manufactured by Riken Keiki Co., Ltd.).
It was 4.68 eV when measured under the conditions of the irradiation light quantity of 500 nW using 1).

(Formation of the conductive skin layer)
Conductive EPDM rubber tube molded into a cylindrical shape by extrusion molding with a diameter of m (manufactured by Toshin Rubber Chemical Industry Co., Ltd.), φ42 mm (inner diameter), single-layer thickness 3 mm, volume resistance 2.3 × 10 ⁵ Ω · c
m, JISK6301A (hardness: 52 degrees)} was press-fitted onto the conductive foam layer obtained above, and the surface was polished to form a conductive skin layer having a one-layer thickness of 1.2 mm. The surface roughness (Ra) of the conductive skin layer was 0.591 μm and the surface roughness (Rmax) was 4.737 μm. The work function of the conductive skin layer was measured in the same manner as the conductive foam layer. However, it was 4.73 eV.

The Asker C hardness of the obtained conductive foam layer and the conductive skin layer measured from the side of the conductive skin layer was 45 degrees.

(Formation of Conductive Subbing Layer) Next, the following composition: Polyamide resin (“FR-105” manufactured by Lead City Co., Ltd.) (7.1% solid content) Ethanol solution 200 Parts by weight-Conductive carbon black ("Vulcan XC72R" manufactured by Cabot Co., Ltd.) A coating liquid for forming a conductive undercoat layer consisting of 0.8 parts by weight was prepared.

A conductive substrate having the above-mentioned conductive skin layer on the surface is dipped in this coating solution, applied, dried and cured at 70 ° C. for 6 hours to form a conductive undercoat layer having a thickness of 10 μm. Formed. The work function of the conductive underlayer is 5.18.
eV.

Next, a composition for an organic photosensitive layer: 21 parts by weight of a polycarbonate resin (manufactured by Teijin Chemicals Ltd.); 2 parts by weight of a metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals, Inc.); and a hydrazone compound (Anan Co., Ltd.) 10 parts by weight ・ Sensitizer (3,5-dimethyl-3 ′, 5′-di (t) butyl-4,4′-diphenoquinone) 5 parts by weight ・ Toluene 180 parts by weight in a paint conditioner For 3 hours to prepare a coating solution. A conductive substrate having the above-mentioned conductive undercoat layer on its surface is dipped in this coating solution, dried at 70 ° C. for 2 hours, and an organic photosensitive layer having a dry film thickness of 25 μm is laminated.
An electrophotographic photosensitive member for positive charging was produced. The work function of the organic photosensitive layer surface was 5.09 eV.

The axial load of the developing roller and the amount of deformation in the radial direction of the photoreceptor when the developing roller {18 mm (outer diameter)}, which is an aluminum rigid body having a roughened surface, is pressed against the obtained photoreceptor. Fig. 5 shows the relationship between the "black triangle"
Indicated by

As can be seen from FIG. 5, in this photoreceptor, the developing roller shaft load is 1 kgf / cm to 2 kgf / cm.
cm, the deformation amount was in the range of 0.1 mm to 0.18 mm.

As for the permanent compression strain, ASTM. D
395 (pressurized to a state where the thickness is compressed to 25%, and then left for 22 hours under a temperature condition of 70 ° C.
Thereafter, the amount of distortion remaining when the pressure was released was 30%.

Example 2 Conductivity E used in Example 1
After press-fitting the PDM foam tube onto the metal pipe 2 obtained in Example 1, the surface was polished to form a conductive foam layer having a thickness of 6 mm on one side. When the work function of this conductive foam layer was measured in the same manner as in Example 1, it was 4.68 eV.

Next, the conductive EPD used in Example 1 was used.
After press-fitting the M rubber tube onto the conductive foam layer obtained above, the surface was polished to form a conductive skin layer having a one-layer thickness of 0.8 mm. The surface roughness of this conductive skin layer (R
a) is 0.363 μm, and the surface roughness (Rmax) is 3.2.
When the work function of the conductive skin layer was measured in the same manner as in Example 1, it was 4.73 eV.

The Asker C hardness of the obtained conductive substrate comprising the conductive foam layer and the conductive skin layer was 40 degrees.

On the obtained conductive substrate, a conductive subbing layer and an organic photosensitive layer were laminated in the same manner as in Example 1 to produce a positively charged electrophotographic photosensitive member.

The amount of deformation of the obtained photoreceptor was measured in the same manner as in Example 1.
The amount of deformation at 5 kgf / cm to 2 kgf / cm could be in the range of 0.15 mm to 0.25 mm. Further, the permanent compression set was 28%.

(Embodiment 3) Conductivity E used in Embodiment 1
After the PDM foam tube was compressed between metal rollers and subjected to a pseudo open-celling treatment, it was press-fitted onto the metal pipe 2 obtained in Example 1, the surface thereof was polished, and the thickness of one side was 9 mm. A conductive foam layer was formed. When the work function of this conductive foam layer was measured in the same manner as in Example 1, it was 4.68 eV.

Next, the conductive EPDM used in the examples
After the rubber tube was press-fitted onto the conductive foam layer obtained above, the surface was polished to form a conductive skin layer having a thickness of 1.0 mm. The surface roughness of this conductive skin layer (R
a) is 0.590 μm, and the surface roughness (Rmax) is 4.3.
The work function of the conductive skin layer was measured in the same manner as in Example 1. As a result, it was 4.73 eV.

The Asker C hardness of the obtained conductive substrate comprising the conductive foam layer and the conductive skin layer was 24 degrees.

On the obtained conductive substrate, a conductive subbing layer and an organic photosensitive layer were laminated in the same manner as in Example 1 to produce an electrophotographic photosensitive member for positive charging.

The obtained photoreceptor was used in Example 1
Similarly to the above, the relationship between the axial load of the developing roller and the amount of deformation (bite-in amount) in the radial direction of the photoconductor was measured, and the result is indicated by "black circle" in FIG. As can be seen from the figure, in this photoreceptor, the developing roller shaft load is 1.0 kgf / cm to 2.0 kgf / cm.
The amount of deformation at 2 kgf / cm is 0.1 mm to 0.4
mm range. Further, the permanent compression set was 25%.

(Example 4) A conductive silicon foam tube extruded and foamed into a cylindrical shape (manufactured by Kuraray Plastics Co., Ltd.), φ30 mm (inner diameter), single-layer thickness 10 m
m, volume resistance 4.5 × 10 ⁴ Ω · cm, Asker C hardness 40 degrees, average foam cell diameter 200 μm, single cell 1
After press-fitting 27 / inch 2 onto the metal pipe 2 obtained in Example 1, the surface was polished to form a conductive foam layer having a thickness of 6 mm on one side. When the work function of this conductive foam layer was measured in the same manner as in Example 1, it was 4.77 eV.

Next, a conductive silicone rubber tube molded in a cylindrical shape in the same manner as described above was manufactured by Toshin Rubber Chemical Industry Co., Ltd.
42mm (inner diameter), single-layer thickness 3mm, volume resistance 4.3 × 1
0 ⁵ Ω · cm, after JISK6301A a (hardness) 50 °} was injected to the resulting conductive foam layer above, polished the surface to form a conductive surface layer of KatamakuAtsu 1.2mm . The surface roughness (Ra) of this conductive skin layer was 0.789.
μm, the surface roughness (Rmax) is 6.863 μm,
The work function of this conductive skin layer was measured in the same manner as the conductive foam layer, and was 4.88 eV.

The Asker C hardness of the obtained conductive substrate comprising the conductive foam layer and the conductive skin layer was 40 degrees.

An electroconductive undercoat layer and an organic photosensitive layer were laminated on the obtained electroconductive substrate in the same manner as in Example 1 to produce an electrophotographic photoconductor for positive charging.

The obtained photoreceptor was used in Example 1
When the amount of deformation was measured in the same manner, the load of the developing roller shaft was 1
The amount of deformation is set to 0.1 kgf / cm to 2 kgf / cm.
The range was 15 mm to 0.25 mm. Further, the permanent compression set was 10%.

(Comparative Example 1) A conductive EPDM rubber tube molded into a cylindrical shape by extrusion molding (manufactured by Toshin Rubber Chemical Industry Co., Ltd.), φ30 mm (inner diameter), single-layer thickness 10 mm, volume resistance 2.5 × 10 ⁵ Ω · cm, JISK6301A (hardness) 60 °} was press-fitted onto the metal pipe obtained in Example 1, and the surface was polished to form a conductive skin layer having a thickness of 7 mm on one side. The surface roughness (Ra) of this conductive skin layer is 0.464 μm, and the surface roughness (Rmax) is 5.893 μm.
m.

A conductive subbing layer and an organic photosensitive layer were laminated on the obtained conductive substrate in the same manner as in Example 1 to produce a positively charged electrophotographic photosensitive member.

The result of measuring the amount of deformation of the obtained photoreceptor in the same manner as in Example 1 is shown by "black rhombus" in FIG. The obtained photoreceptor required a developing roller shaft load of 3.23 kgf / cm to obtain a deformation of 0.15 mm.
Further, the permanent compression set was 30%.

(Comparative Example 2) A conductive EPDM rubber tube formed into a cylindrical shape by extrusion molding (manufactured by Toshin Rubber Chemical Industry Co., Ltd.), φ30 mm (inner diameter), single-layer thickness 10 mm, volume resistance 6.7 × 10 ⁵ Ω · cm, JIS K6301A (hardness) 50 °} was press-fitted onto the metal pipe obtained in Example 1, and the surface was polished to form a conductive skin layer having a thickness of 7 mm on one side. The surface roughness (Ra) of this conductive skin layer is 0.523 μm, and the surface roughness (Rmax) is 6.031 μm.
m.

A conductive subbing layer and an organic photosensitive layer were laminated on the obtained conductive substrate in the same manner as in Example 1 to produce a positively charged electrophotographic photosensitive member.

The results of measuring the amount of deformation of the obtained photoreceptor in the same manner as in Example 1 are shown by "black squares" in FIG. The obtained photoreceptor required a developing roller shaft load of 2.79 kgf / cm to obtain a deformation of 0.15 mm.
Further, the permanent compression set was 29%.

(Evaluation of Charging Characteristics, Light Sensitivity, and Light Attenuation Residual Potential) For each of the obtained electrophotographic photosensitive members, the photoinduced discharge curve (PIDC) was measured by using a charging characteristics measuring device (PDT-A) manufactured by QEA. (2000 LTM), the applied voltage was +6.5 kV, and the process speed was 200 mm / sec.

The light half-life exposure amount E_1/2(Luxsec)
Is the initial surface potential V₀From 1 / 2V ₀Attenuate to
This is the amount of exposure required to Also, the light attenuation residual potential
(V) is an exposure energy of 3 μJ / cm^TwoIs the measured value at
You. The charge measurement substrate was kept at room temperature and humidity for 24 hours in the dark.
After standing, it was used for measurement.

In each of the obtained electrophotographic photosensitive members, the work function of the conductive foam layer (φ _R ), the work function of the conductive skin layer (φ _Is ), the work function of the conductive subbing layer (φ _UCL ), Table 1 below shows the relationship between the work function (φ _Opc ) of the organic photosensitive layer and the work function (φ _Opc ).
Shown in

[0090]

[Table 1]

Table 2 shows the charging characteristics, photosensitivity and light-decay residual potential of each electrophotographic photosensitive member.

[0092]

[Table 2]

[0093] from the table, φ _UCL> φ _Opc and φ _UCL>
By satisfying the relationship of φ _Is > φ _R at the same time, it is understood that a high charging potential can be obtained, and a light attenuation residual potential is low, thereby improving photosensitivity.

[0094]

According to the electrophotographic photoreceptor for positive charging of the present invention, a uniform developing nip pressure with the one-component contact developing roller can be secured, and a uniform toner image can be transferred by a stable nip pressure during transfer. It has high resolution, excellent cleaning characteristics, and excellent charging characteristics and photosensitivity.

In the method for producing a positively charged electrophotographic photoreceptor of the present invention, a conductive substrate is formed using a conductive foam tube and a conductive skin layer tube, and a conductive undercoat layer is formed. By forming the conductive substrate by coating, the conductive substrate can be made resistant to a coating solution, and a stable positively charged electrophotographic photosensitive member that does not change with time can be obtained.

Further, the image forming apparatus of the present invention can be an image forming apparatus which is free from problems such as deterioration of image quality and damage to the drum surface, has a high charging potential, has a low light attenuation residual potential and is excellent in photosensitivity.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view of a positively charged electrophotographic photosensitive member of the present invention.

FIG. 2 is an explanatory cross-sectional view of another electrophotographic photosensitive member for positive charging according to the present invention.

FIG. 3 is an explanatory cross-sectional view of another electrophotographic photosensitive member for positive charging according to the present invention.

FIG. 4 is a diagram for explaining the image forming apparatus of the present invention.

FIG. 5 is a diagram illustrating a relationship between a developing roller axial load and a deformation amount (biting amount) in a photoconductor radial direction in the electrophotographic photoconductor for positive charging according to the present invention and a comparative example.

[Explanation of symbols]

1 is a pipe, 2 is a metal pipe, 3 is a bush, 4 is a flange, 5 is a conductive foam layer, 6 is a conductive skin layer, 7 is a conductive undercoat layer, 8 is an organic photosensitive layer, and 10 is a developing device. , 11 a developing roller, 36 an intermediate transfer medium, T2 a secondary transfer device, 50 a paper feed tray, 60 fixing device, 70 a discharge path, 7 a paper discharge tray, and 140 an electrophotographic photosensitive member.

Claims (3)

[Claims] 1. A volume resistance of 10 ⁷ Ω · cm on a rotating shaft.
A conductive foam layer having an Asker C hardness of 10 to 50 degrees, a volume resistance of 10 ⁷ Ω · cm or less and JIS K6301
For positive charging, a conductive skin layer made of a conductive rubber having a hardness of 30 ° to 70 ° A, a conductive undercoat layer having a volume resistance of 10 ⁷ Ω · cm or less, and an organic photosensitive layer are sequentially laminated in a cylindrical shape. In the electrophotographic photoreceptor, the conductive foam layer has a thickness of 3 mm to 15 mm, and the conductive skin layer has a thickness of 0.6 mm to 2 mm, and the conductive foam layer and the conductive skin An electrophotographic photoreceptor for positive charging, wherein Asker C hardness from the conductive skin layer side of the conductive substrate comprising the layers is 20 to 50 degrees. 2. A volume resistivity of 10 ⁷ Ω · cm on a rotating shaft.
After forming a conductive foam layer having a thickness of 3 mm to 15 mm by coating a conductive foam tube having an Asker C hardness of 10 to 50 degrees, a volume resistance is further reduced on the conductive foam layer. A conductive skin tube having a thickness of 0.6 mm to 2 mm is formed by coating a conductive rubber tube having a hardness of 30 to 70 degrees according to JIS K6301A at 10 ⁷ Ω · cm or less, and forming a conductive layer with the conductive foam layer. Asker C hardness from the conductive skin layer side of the conductive substrate composed of the conductive skin layer is set to 20 to 50 degrees, and then a conductive subbing layer and an organic photosensitive layer are sequentially formed on the conductive skin layer. A method for producing a positively charged electrophotographic photoreceptor, comprising: 3. An image forming apparatus for transferring a toner image formed on a photosensitive member onto an intermediate transfer member, and transferring and fixing the toner image on the intermediate transfer member onto a transfer material, wherein the photosensitive member is on the rotating shaft, the volume resistivity is 10 ⁷ Ω · cm Asker C hardness below 10 to 50 degrees of the conductive foam layer, the volume resistivity JISK6301A by hardness of 30 to 70 degrees below 10 ⁷ Ω · cm A conductive skin layer made of conductive rubber,
A conductive undercoat layer and an organic photosensitive layer each having a volume resistance of 10 ⁷ Ω · cm or less are sequentially laminated in a cylindrical shape, and the conductive foam layer has a thickness of 3 mm to 15 mm, and the conductive skin layer Having a thickness of 0.6 mm to 2 mm, and a positive charge having an Asker C hardness of 20 to 50 degrees from the conductive skin layer side of a conductive substrate composed of a conductive foam layer and a conductive skin layer. An image forming apparatus characterized by being an electrophotographic photosensitive member for use.