JP2002023402A - Positive chargeable electrophotographic photorecptor, manufacture 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, which is provided with high resolution and also with improved cleaning characteristics, charging characteristics and optical sensitivity, and to provide a photoreceptor manufacturing method and an image forming device. SOLUTION: The positive chargeable electrophotographic photoreceptor is constituted by successively and cylindrically laminating a conductive foam body whose volume resistivity is <=107 Ω.cm and whose ASKER C hardness is 10 to 50 deg., a conductive surface layer constituted of conductive hardened resin whose volume resistivity is 107 Ω.cm and whose hardness by JISK6253D is 80 to 100 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 layer is controlled to be 3 to 15 mm, the film thickness of the conductive surface layer is controlled to be 40 to 200 μm, besides, the ASKER C hardness of the conductive substrate constituted of the conductive foam 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 cured resin having a volume resistance of 10 ⁷ Ω · cm or less and a hardness of 80 to 100 degrees according to JIS K6253D, a conductive undercoat layer having a volume resistance of 10 ⁷ Ω · cm or less, an organic photosensitive layer Are sequentially laminated in a cylindrical shape, the thickness of the conductive foam layer is 3 mm to 15 mm, and the thickness of the conductive skin layer is 40 μm to 200 μm, It is characterized in that 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.
0⁷Hardness according to JIS K6253D of 8 or less at Ω · cm
Coating a conductive cured resin tube of 0 to 100 degrees to form a film
Forming a conductive skin layer having a thickness of 40 μm to 200 μm;
Of a conductive substrate comprising a conductive foam layer and a conductive skin layer
Asker C hardness from the conductive skin layer side is 20 to 50 degrees
Then, a conductive subbing layer is formed on the conductive skin layer.
The photosensitive layer is formed by coating sequentially.

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 a conductive cured resin having a hardness of 6253D of 80 to 100 degrees, and a volume resistance of 10 ⁷ Ω · cm.
The following conductive undercoat layer and organic photosensitive layer are sequentially laminated in a cylindrical shape, and the thickness of the conductive foam layer is 3 mm to 15 m.
m, and the thickness of the conductive skin layer is 40 μm to 200 μm.
μm, and a positively charged electrophotographic photoreceptor having an Asker C hardness of 20 to 50 degrees from the conductive skin layer side of a conductive substrate comprising a conductive foam layer and a conductive skin layer. It is characterized by.

[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. By setting the inner diameter of the tube to be slightly smaller than the outer diameter of each of the metal shaft 1 and the metal pipe 2, 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, and the like are used from the viewpoint of heat resistance of 120 ° C. or more, excellent workability, excellent solvent resistance, and excellent compression set. Foams of rubber and NBR rubber are preferred, and EPDM rubber foams are particularly preferred. The foamed shape of the conductive foam is 100 μm in diameter.
An example is a closed cell state in which bubbles of up to 800 μm are independent of each other, or an open cell state, and the number of cells is 32 / inch to 254 /
It should be inches.

The conductive skin layer 6 is made of a conductive cured resin. The conductive cured resin layer is formed using a cured resin tube having a volume resistance of 10 ⁷ Ω · cm or less, preferably 5 × 10 ⁶ Ω · cm or less. As the cured resin, a thermosetting resin, a photocurable resin, or a resin cured using a curing agent such as polyether urethane, for example, a polyimide resin, an epoxy resin, a urethane resin, a polyester resin. , Alkyd resin, phenolic resin,
An example is a tube formed by extrusion curing molding using a urea melamine resin or an acrylic resin. The conductive skin layer preferably has excellent adhesiveness to the conductive foam layer and has flexibility. From the viewpoint of flexibility, a tube made of a polyimide resin is preferable. Further, a cured product of an epoxy resin shown below may be used.

As the epoxy resin, compounds of the following structural formula

[0021]

Embedded image Bisphenol epoxides exemplified by (bisphenol AD), compounds of the following structural formula

[0022]

Embedded image Phenolic epoxides such as alkylphenol diglycidyl ethers, and compounds of the following structural formulas

[0023]

Embedded image And a compound of the following structural formula

[0024]

Embedded image A sulfur-containing epoxide such as thiochol-digsidyl, a compound of the following structural formula

[0025]

Embedded image And silicon-containing epoxides such as glycidyl silicon.

The amine-based curing agent in polyether urethane is a compound of the following structural formula

[0027]

Embedded image And aliphatic amines such as (norbornanediamine, 2,5- (2,6-) bis (aminomethyl) bicyclo (2,2,1) heptane).

Examples of the conductive substance contained in the conductive skin layer 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 (ExtraConductive Furnace Bla
ck), SCF (Super Conductive Furnace Black), CF
(Conductive Furnace Black), SAF (Super Abrasio
n Furnace Black) is preferable, and among them, those having a BET specific surface area of 800 m ² / g or more by nitrogen gas adsorption are preferable. XCF includes “Ketjen Black EC” by Ketjen Black International, Cabot
Cab as SCF such as "Vulcan XC-72"
Og's “Vulcan SC”, “Vulcan P”, etc.
Cab as CF, such as "Salux Colux L"
OT's "Vulcan C", etc .; Coloumbian's "Conductex SC", etc .; SAF asahi Carbon's "Asahi # 9"; Mitsubishi Chemical's "Diablack A";Cabot's"Vulcan9" etc. And a mixture thereof may be used. When the carbon black is 50% or more, the carbon black as a whole has a BET specific surface area of 750 m ² / g or more by nitrogen gas adsorption,
Preferably at least 800 m ² / g, especially 900 m ² / g, other carbon black such as acetylene black may be used in combination. The conductive material may be added at a ratio of 2 parts by weight to 50 parts by weight, preferably 4 parts by weight to 30 parts by weight based on 100 parts by weight of the cured resin.
In addition, the conductive skin layer may appropriately contain a polymer dispersant or the like.

The conductive skin layer made of a conductive curable resin must have a heat resistance of 120 ° C. or higher.
It is required that the hardness according to 53D is in the range of 80 to 100 degrees, the workability is excellent, the solvent resistance is excellent, and the like, and commercially available as a polyimide resin tube, for example, manufactured by Gunze Co., Ltd. “Engineering plastic, volume resistance 5.3 × 10 ⁶ Ω · cm, inner diameter 4
0 mm, one-side film thickness 75 μm, hardness 100 degrees according to JIS K6253D), “Engineering plastic, volume resistance 6.4 × 1 manufactured by Inoac Corporation.
0 ⁵ Ω · cm, inner diameter 49 mm, single layer thickness 70 μm, JIS
93 degrees according to K6253D) or the like.

The conductive skin layer made of a conductive cured resin is
The conductive cured resin tube is similarly pressed and fixed on the conductive foam layer pressed into the metal shaft 1 or the metal pipe 2 and, if necessary, ground and polished to obtain a film thickness of 40 μm or more.
The thickness is 200 μm. The conductive curable resin tube may be obtained by hardening and molding the conductive curable resin by centrifugal molding, but the inner diameter thereof should be slightly smaller than the outer diameter of the conductive foam layer covering the rotating shaft. Thereby, the adhesiveness to the conductive foam layer can be increased and fixed, 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. When a conductive skin layer is formed using a conductive cured resin tube, the surface can be made excellent in smoothness, and the surface roughness (Ra) is 0.05 μm or more.
The surface roughness (Rmax) can be set to 0.25 μm or less and the surface roughness (Rmax) can be set to 2.50 μm or less.

As will be described later, a conductive undercoat layer or an organic photosensitive layer is provided on the conductive skin layer. The conductive skin layer is applied to a coating solution for forming the conductive undercoat layer or 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. Although this may be a cause, the formation of the conductive cured resin layer on the conductive foam layer has the advantage of acting as a barrier layer.

The electrophotographic photoreceptor for positive charging of 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 appropriately selected in thickness and hardness to be laminated, and the thickness of one side of the conductive substrate is 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 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 of increase in rotational load due to contact depth.
The compression set is 40% or less, preferably 30% or less.
% 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 2.5 kgf / cm, the amount of deformation (digging amount) in the radial direction of the photoconductor is set to 0.1 mm to
It can be in the range of 0.38 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 formed of a polyamide resin, polyvinyl butyral resin, 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 flexibility as well as excellent in adhesion to the conductive skin layer, and when using EPDM rubber as the conductive elastic body, polyamide resin, polyvinyl butyral resin, and 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.

As the conductive substance, the conductive substance described in the section of the conductive skin layer is similarly used, and 2 to 35 parts by weight, preferably 4 to 35 parts by weight based on 100 parts by weight of the resin.
25 parts by weight, in addition, a polymeric dispersant,
An antioxidant and the like are appropriately contained.

As the solvent, those having no solubility in the conductive skin layer are preferable, and examples thereof include water, methanol, ethanol, butyl alcohol, methyl ethyl ketone, and propylene glycol. Use is made of a paint shaker, a sand mill, a ball mill or the like. And mix the above components
The composition is dispersed to form 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 dried film thickness 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 preferable that the charge transfer is easily performed under an electric field generated at the time and the film thickness is flexible, for example, 0.1 μm to 0.2 μm after drying.

The organic photosensitive layer 8 provided on the conductive undercoat layer is 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, and has a long service life. It is a single-layer photoreceptor from the viewpoint of. The single layer organic photoreceptor layer
It comprises a charge generating agent, a charge transporting 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, 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 form a coating liquid. The coating liquid has a thickness of 15 μm to 4 μm after being dried on the conductive undercoat layer by dip coating, ring coating, spray coating or the like.
It is applied and dried at 0 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 a surface analyzer (AC- manufactured by Riken Keiki Co., Ltd.).
1), and the work function (φ _R ) of the conductive foam layer can be changed depending on the type and composition of the resin constituting the foam, from 4.4 eV to 4.9 e.
V, preferably 4.5 eV to 4.8 eV.

The work function (φ _IS ) of the conductive cured resin layer, which is the conductive skin layer, is 4.5 eV to 5.0 eV, preferably 4.6 eV to 4.9 eV.

The work function (φ _UCL ) of the conductive undercoat layer is set to 4.6 eV to 5.7 eV, and 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, it is preferable that the work function in each layer simultaneously satisfies the following relationship: φ _UCL > φ _Opc φ _UCL > φ _Is > φ _R , whereby the charge potential is high and the light An electrophotographic photosensitive member for positive charging having a low attenuation residual potential and excellent photosensitivity can be obtained.

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 is in contact with the outer peripheral surface of the photosensitive member 140 to uniformly charge 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,
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 between the driven roller 35 and the driven 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 multilayer belt having a conductive layer and a resistance layer formed on the conductive layer and pressed against the photosensitive member 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 portion T1, and the toner image transferred onto the intermediate transfer belt 36 is Is transferred to a sheet (recording material) S, such as a sheet, 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 of the present invention has a conductive substrate having a laminated structure of 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 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. Can be
When the external force is removed, it is possible to completely return to the original sleeve state, 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.

In the image forming apparatus of the present invention, the work function of the conductive foam layer in the electrophotographic photosensitive member for positive charging is φ
_R , when the work function of the conductive skin layer is φ _Is , the work function of the conductive undercoat layer is φ _UCL , and the work function of the organic photosensitive layer is φ _Opc , the following equation is obtained: φ _UCL > φ _Opc φ _UCL > φ by those satisfying _is> phi _R relationships simultaneously, high with charging potential is obtained, the optical attenuation residual potential are those that can be an image forming apparatus which can improve a light sensitivity lower.

[0067]

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 an aluminum pipe (6063 series) having a diameter of 35 mm (outer diameter) and a thickness of 1.5 mm, and the inside of the pipe is subjected to a spigot process for an insertion portion of the flange 4. And is press-fitted into a metal pipe, and a hole through which a rotary drive shaft passes is opened at the center of the flange 4.

(Formation of Conductive Foam Layer) A conductive NBR foam tube formed by extrusion molding into a tubular shape, manufactured by Inoac Corporation, φ30 mm
(Inner diameter), single-layer thickness 10 mm, volume resistance 5.8 × 10 ⁵ Ω
・ Cm, Asker C hardness 25 degrees, average foam cell diameter 300
After a single cell of 85 μm and a cell number of 85 / inch｝ were pressed into the metal pipe 2 obtained above, the surface was polished to form a conductive foam layer having a thickness of 8.5 mm on one side. The work function of the conductive foam layer was 4.63 eV when measured using a surface analyzer (AC-1 manufactured by Riken Keiki Co., Ltd.) under the condition of an irradiation light amount of 500 nW.

(Formation of Conductive Skin Layer) Next, a conductive polyimide resin tube (manufactured by Inoac Corporation), φ49 mm (inner diameter), thickness 70 μm, volume resistance 6.4 × 10 ⁵ Ω · cm, JISK6253D (hardness) ) 93 °), a commercially available conductive rubber-based adhesive was thinly applied onto the conductive foam layer obtained above, dried and pressed, to form a conductive skin layer having a single-layer thickness of 70 μm. The surface roughness (Ra) of this conductive skin layer was 0.135 μm, the surface roughness (Rmax) was 2.481 μm, and the work function of this conductive skin layer was measured in the same manner as the conductive foam layer. However, it was 4.83 eV.

The Asker C hardness of the obtained conductive substrate comprising the conductive foam layer and the conductive skin layer was 35 degrees.

(Formation of conductive undercoat layer) Next, the following composition: polyamide resin ("FR-105" manufactured by Lead Co., Ltd.) (solid content: 10%, ethanol solution): 200 parts by weight Conductive carbon black (“Vulcan XC72R” manufactured by Cabot Co.) 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.) 10 parts by weight ・ Toluene 180 parts by weight ・ 5,5 parts by weight of 3,5-dimethyl-3 ′, 5′-ditertiarybutyl-4,4′-diphenoquinone as a sensitizer are dispersed in a paint conditioner for 100 minutes. Mix to prepare a coating solution, apply this coating solution on the conductive undercoat layer with a wire bar, and dry at 70 ° C. for 2 hours.
An organic photosensitive layer having a dry film thickness of 21 μm was laminated to prepare an electrophotographic photosensitive member for positive charging. The work function of the organic photosensitive layer surface is
It was 5.09 eV.

The axial load of the developing roller and the amount of deformation in the radial direction of the photosensitive member when the obtained photosensitive member is pressed against a developing roller {φ18 mm (outer diameter)} which is a rigid aluminum member having a roughened surface. FIG. 5 illustrates the relationship with (amount of bite) as “two-layer sponge A”.

As can be seen from the drawing, this photosensitive member can have a deformation amount in the range of 0.1 mm to 0.22 mm when the axial load of the developing roller is 1 kgf / cm to 2.5 kgf / cm.

Further, regarding the compression set, ASTM, D3
95 (pressurized to a state where the thickness is compressed to 25%, and then left for 22 hours at a temperature of 70 ° C.
Thereafter, the amount of distortion remaining when the pressurization was released was 25%.

(Example 2) Conductive N used in Example 1
In place of BR, conductive EPDM foam tube (manufactured by Kuraray Plastics Co., Ltd.), φ30 mm (inner diameter), single-layer thickness 12 mm, volume resistance 4.3 × 10 ⁵ Ω · cm, Asker C hardness 20 degrees, average foam cell After a single cell having a diameter of 320 μm and a cell number of 79 / inch｝ were pressed into the metal pipe 2 obtained in Example 1, the surface was polished to form a conductive foam layer having a thickness of 9 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, in place of the conductive cured resin tube used in Example 1, a conductive polyimide resin tube of the same manufacturer (φ49 mm (inner diameter), thickness 80 μm, volume resistance 6.5 × 10 ⁵ Ω · cm, JISK6253D
(Hardness) 93 °) A conductive skin layer having a thickness of 80 μm was formed in the same manner except that｝ was used. The surface roughness (Ra) of this conductive skin layer was 0.140 μm, and the surface roughness (Rm
ax) was 2.538 μm, and the work function of this conductive skin layer was measured in the same manner as in the case of the conductive foam layer, and was found to be 4.83 eV.

The Asker C hardness of the obtained conductive substrate composed of the conductive foam layer and the conductive skin layer was 31 degrees.

A conductive undercoat 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 obtained photoreceptor was used in Example 1
When the amount of deformation was measured in the same manner as in FIG. 5, the amount of deformation when the developing roller shaft load was 0.9 kgf / cm to 2.0 kgf / cm was 0.10 mm as shown in FIG. 5 as a two-layer sponge B. ０．２0.20 mm range. The compression set was 28%.

(Embodiment 3) Conductive N used in Embodiment 1
In a BR foam tube, the average foam cell diameter is 450 μm,
After a tube having a cell number of 56 / inch was press-fitted onto the metal pipe 2 obtained in Example 1, the surface was polished to form a 8.5-mm-thick conductive foam layer. When the work function of this conductive foam layer was measured in the same manner as in Example 1, it was 4.63 eV.

Next, in place of the conductive cured resin tube used in Example 1, a conductive epoxy resin tube (manufactured by Inoac Corporation, φ49 mm (inner diameter), thickness 75 μm, volume resistance 6.3 × 10 ⁶ Ω)・ C
m, JISK6253D (hardness: 98 degrees)}, except that a conductive skin layer having a single film thickness of 75 μm was formed in the same manner. The surface roughness (Ra) of this conductive skin layer is 0.10
The surface roughness (Rmax) was 1.384 μm, and the work function of the conductive skin layer was measured in the same manner as the conductive foam layer. As a result, it was 4.81 eV.

The Asker C hardness of the obtained conductive substrate comprising the conductive foam layer and the conductive skin layer was 22 degrees.

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 obtained photoreceptor was used in Example 1
The deformation amount was measured in the same manner as described above, and as shown in FIG. 5 as a two-layer sponge C, the deformation amount when the developing roller shaft load was 1.00 kgf / cm to 2.50 kgf / cm was 0.16 mm.範 囲 0.38 mm. The compression set was 20%.

(Comparative Example 1) 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 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.

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 obtained photoreceptor was used in Example 1
Similarly, the result of measuring the amount of deformation is shown in FIG. 5 as “hardness 60”. The obtained photoreceptor requires a developing roller shaft load of 3.23 kgf / cm to obtain a deformation amount of 0.15 mm.
Needed the power of The 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 degrees) 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.

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.

Further, the obtained photoreceptor was used in Example 1
Similarly, the result of measuring the amount of deformation is shown in FIG. 5 as “hardness 50”. The obtained photoreceptor required a developing roller shaft load of 2.79 kgf / cm to obtain a deformation of 0.15 mm. The compression set was 29%.

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

Incidentally, the light half-life exposure amount E _1/2 (μJ / cm ² )
Is the amount of exposure necessary to attenuate the surface potential from the initial surface potential V ₀ to 1/2 V ₀ . The light attenuation residual potential (V) is a value measured at an exposure energy of 3 μJ / cm ² . The charge measurement substrate was left for 24 hours in the dark at normal temperature and normal humidity before 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 undercoat 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

[0097]

[Table 1] Table 2 shows the charging characteristics, photosensitivity, and light-decay residual potential of each electrophotographic photosensitive member.

[0098]

[Table 2] From the table, φ _UCL > φ _Opc and φ _UCL > φ _Is
> By shall satisfy phi _R relationships simultaneously,
It can be seen that a high charging potential is obtained, and a light-decay residual potential is low, so that photosensitivity can be improved.

[0099]

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 showing a relationship between a developing roller shaft load and a deformation amount (biting amount) in a radial direction of the photoreceptor in the electrophotographic photoreceptor for positive charging of the present invention.

[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 or less, a volume resistance of 10 ⁷ Ω · cm or less and JISK6253
A positively charged layer in which a conductive skin layer made of a conductive cured resin having a hardness of 80 to 100 degrees according to D, a conductive subbing 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 for use, the conductive foam layer has a thickness of 3 mm to 15 mm, and the conductive skin layer has a thickness of 40 μm to 200 μm, and the conductive foam layer and the conductive skin layer An electrophotographic photosensitive member for positive charging, wherein Asker C hardness from the conductive skin layer side of the conductive substrate comprising: 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 covering 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 layer having a thickness of 40 μm to 200 μm is formed by coating a conductive cured resin tube having a hardness of 80 to 100 degrees according to JIS K6253D at 10 ⁷ Ω · cm or less, and forming a conductive foam layer with the conductive foam layer. The Asker C hardness from the conductive skin layer side of the conductive substrate composed of the skin layer is set to 20 to 50 degrees, and then a conductive undercoat layer and an organic photosensitive layer are sequentially formed on the conductive skin layer. A method for producing an electrophotographic photosensitive member for positive charging, characterized by 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 material to be transferred, wherein the photosensitive member comprises: on the rotating shaft, the volume resistivity is 10 Asker C hardness of 10 to 50 degrees below ⁷ Omega · cm conductive foam layer, the volume resistivity is 10 ⁷ Omega · cm hardness in JISK6253D below is 80 degrees to 100 degrees A conductive skin layer made of a conductive cured resin, 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, and the thickness of the conductive foam layer is 3 mm. １５15 mm, and the thickness of the conductive skin layer is 40 μm to 200 μm, and 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 Electrophotographic photoreceptor for positive charging at 20 to 50 degrees An image forming apparatus wherein there.