JPH08123101A - Electrophotographic image forming method, electrophotographic device and electrophotographic unit - Google Patents

Abstract

PURPOSE: To stabilize dark part potential and sensitivity and to obviate the occurrence of image defects even at the time of repetitively using under high temp. and high humidity by subjecting an electrophotographic photoreceptor contg. specific azo pigments in photosensitive layers to electrostatic charging, image exposing and developing. CONSTITUTION: This electrophotographic forming method includes an electrostatic charging stage for electrostatically charging the electrophotographic photoreceptor contg, the azo pigments expressed by the formula in the photosensitive layers by direct electrostatic charging, an image exposing stage for forming an electrostatic latent image by subjecting the electrostatically charged electrophotographic photoreceptor to image exposing and a developing stage for developing the electrophotographic photoreceptor formed with the electrostatic latent image. In the formula, Cp1 and Cp2 denote coupler residues. The photoreceptor has the photosensitive layers on a base. The layers formed by laminating a charging generating layer contg. a charge generating material which generates charges by exposing and a charge transfer layer contg. a charge transfer material which transfers the charges are usable as the photosensitive layers. The charge generating layer is formable by coating a coating material prepd. by vapor deposition of the charge generating material of the azo pigments expressed by the formula or dispersing the material together with a suitable binder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming method using direct charging, an electrophotographic apparatus and an electrophotographic apparatus unit.

[0002]

2. Description of the Related Art Inorganic photoconductive materials such as selenium, cadmium sulfide and zinc oxide have been used as photoconductive materials for electrophotographic photoreceptors. On the other hand, organic photoconductive materials such as polyvinylcarbazole, oxadiazole, and phthalocyanine have advantages such as pollution-free and high productivity compared with inorganic photoconductive materials, but some sensitization methods are proposed because they have low sensitivity. Has been done. As an effective sensitizing method, it is known to use a function-separated type photoreceptor in which a charge generation layer and a charge transport layer are laminated.

With the recent demand for higher speed and higher image quality of electrophotographic devices, many disazo pigments have been proposed as highly sensitive photoconductive materials. For example, JP-A-54-1451
42, JP-A-59-229564 and JP-A-2-164874 report disazo pigments having high sensitivity to white light.

[0004]

In the corona charging method, when a disazo pigment is used as a charge generating material of a photoreceptor, if it is repeatedly used, the corona product such as ozone or NOx generated during corona charging lowers the dark area potential. Or the sensitivity may decrease. Therefore, when repeatedly used, image defects such as image blurring and image density reduction may occur. In particular, image defects tended to increase under high temperature and high humidity.

On the other hand, a direct charging method has recently been studied as a charging method replacing the corona charging method.

The object of the present invention is to provide an electrophotographic image in which dark area potential and sensitivity are stable and image defects such as image blurring and image density reduction do not occur even when repeatedly used under any environment, especially under high temperature and high humidity. An object is to provide a forming method, an electrophotographic apparatus, and an electrophotographic apparatus unit.

[0007]

That is, according to the present invention, the following general formula (1), general formula (1)

[0008]

[Chemical 13] (In the formula, Cp1 and Cp2 coupler residues are shown.) The electrophotographic photosensitive member containing the azo pigment represented by the formula (3) is charged by direct charging, and the charged electrophotographic photosensitive member is imagewise exposed. And an image exposing step for forming an electrostatic latent image, and a developing step for developing the electrophotographic photosensitive member on which the electrostatic latent image is formed, the electrophotographic image forming method.

The present invention also relates to an electrophotographic photoreceptor containing an azo pigment represented by the general formula (1) in a photosensitive layer, and a method for directly charging the electrophotographic photoreceptor by contacting the electrophotographic photoreceptor. A charging member, an image exposure unit that forms an electrostatic latent image by performing image exposure on the charged electrophotographic photosensitive member, and a developing unit that develops the electrophotographic photosensitive member on which the electrostatic latent image is formed. This is an electrophotographic apparatus characterized by the above.

Further, the present invention relates to an electrophotographic photosensitive member containing an azo pigment represented by the general formula (1) in a photosensitive layer, and directly charging the electrophotographic photosensitive member by contacting the electrophotographic photosensitive member. The electrophotographic apparatus unit is characterized in that it has a charging member integrally connected thereto and is detachable from the apparatus main body.

In the electrophotographic image forming method of the present invention, an azo pigment having a specific structure is used as the charge generating material contained in the photosensitive layer of the photoreceptor, and the photoreceptor is charged by a direct charging member to which a voltage is applied. It is carried out by bringing it into contact with a photoconductor (this charging method is hereinafter referred to as direct charging).

That is, as shown in FIG. 1, the charging member 1 directly contacts the outer peripheral surface of the drum-shaped electrophotographic photosensitive member 12 rotating in the direction of arrow A, and the photosensitive member 12 is positively moved by the direct charging member 1. Alternatively, it is charged to a predetermined negative voltage. A direct or negative DC voltage is applied to the direct charging member 1. The DC voltage applied directly to the charging member 1 is -2000V to +
2000V is preferred. The pulsating voltage may be applied to the charging member 1 directly by superposing an AC voltage in addition to the DC voltage. The AC voltage superimposed on the DC voltage is preferably a peak-to-peak voltage of 4000 V or less.

A desired voltage may be instantly applied to the direct charging member 1, but the applied voltage may be gradually increased in order to protect the photosensitive member.

The direct charging member 1 may be rotated in the same direction as the photosensitive member 12 or in the opposite direction, or may be slid on the outer peripheral surface of the photosensitive member without being rotated.
Further, the direct charging member 1 may have a function of cleaning the residual toner on the photoconductor 12. In this case, it is not necessary to provide the cleaning means 10.

The charged photoconductor 12 is then subjected to optical image exposure 6 (slit exposure, laser beam scanning exposure, etc.) by image exposure means (not shown). As a result, electrostatic latent images corresponding to the exposed image are sequentially formed on the peripheral surface of the photoconductor. The electrostatic latent image is then toner-developed by the developing means 7, and the toner development is carried out by the transfer charging means 8 from a paper feeding portion (not shown) between the photoconductor 12 and the transfer charging means 8.
It is sequentially transferred onto the surface of the recording material 9 fed in synchronization with the rotation of 2. The recording material 9 having undergone the image transfer is separated from the surface of the photoconductor and introduced into an image fixing means (not shown) to be subjected to the image fixing and printed out as a copy.

After the image transfer, the surface of the photoconductor 12 is cleaned by the cleaning means 10 to remove the residual toner after transfer, and is precharged by the pre-exposure 11 to be repeatedly used for image formation.

The electrophotographic apparatus is constructed by integrally combining a plurality of constituent elements such as the above-mentioned photosensitive member and developing means as an apparatus unit, and this unit is detachably attached to the apparatus main body. May be. For example, as shown in FIG. 2, at least the photoconductor 12, the direct charging member 1 and the developing means 7 are housed in a container 20 to form one electrophotographic apparatus unit, and this apparatus unit is used as a guide means such as a rail of the apparatus main body. It may be detachable. The cleaning means 10 may or may not be provided inside the container 20. In addition, as shown in FIG.
Also, the direct charging member 1 is housed in the first container 21 to form a first electrophotographic apparatus unit, and at least the developing means 7 is provided in the second
The second electrophotographic apparatus unit is stored in the container 22 of
The first device unit and the second device unit may be detachable. The cleaning means 10 may or may not be provided inside the container 21. 2 and 3, the direct charging member 23 is used as the transfer charging means. As the direct charging member 23, one having the same configuration as the direct charging member 1 can be used. It is preferable to apply a DC voltage of 400V to 1000V to the direct charging member 23 used as the transfer charging means. Reference numeral 24 is a fixing means.

The photoconductor 12 has a photosensitive layer on a support. As the photosensitive layer, a laminate of a charge generation layer and a charge transport layer can be used. The charge generation layer contains a charge generation material that generates charges upon exposure. The charge transport layer contains a charge transport material that transports charges. In the present invention, an azo pigment having a specific structure represented by the following general formula (1) is used as the charge generating material. The charge generation layer and the charge transport layer are the charge generation layer from the conductive support side,
The order of charge transport layers and vice versa can be used. General formula (1)

[0019]

Embedded image (In the formula, Cp1 and Cp2 represent coupler residues.) The charge generation layer is formed by vapor-depositing the charge generation material of the azo pigment, or by coating with a coating material dispersed with a suitable binder (without a binder). It can be formed by working.

The azo pigments used in the present invention are preferably disazo pigments represented by the formulas (2) to (4). Equation (2)

[0021]

[Chemical 15] Formula (3)

[0022]

Embedded image Formula (4)

[0023]

[Chemical 17]

The binder used in the charge generating layer can be selected from a wide range of insulating resins or organic photoconductive polymers. For example, as the insulating resin, polyvinyl butyral,
Polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate (Polycarbonate Z, modified polycarbonate, etc.), polyester, phenoxy resin, acrylic resin, polyacrylamide, polyamide, cellulose resin, urethane resin, epoxy resin,
Examples thereof include casein and polyvinyl alcohol. Examples of the organic photoconductive polymer include polyvinylcarbazole, polyvinylanthracene, polyvinylpyrene and the like.

The thickness of the charge generation layer is 0.01 to 15 μm,
Further, 0.05 to 5 μm is preferable, and the weight ratio of the charge generating material to the binder is preferably 10: 1 to 1:20.

The organic solvent used for coating the charge generating layer is selected from the solubility and dispersion stability of the resin and charge generating material used, but alcohols, sulfoxides, ethers, esters, and aliphatic halogens. Chemical hydrocarbons or aromatic compounds can be used.

The charge transport layer is formed by dissolving the charge transport material in a binder having a film-forming property. Examples of the charge transport material used in the present invention include hydrazone compounds,
Examples thereof include stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds and triarylamine compounds. These charge transport materials are 1
They may be used alone or in combination of two or more.

As the binder used in the charge transport layer,
Examples thereof include polyvinyl butyral, polyester, polycarbonate (polycarbonate Z, modified polycarbonate, etc.), nylon, polyimide, polyarylate, polyurethane, styrene-butanediene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer and the like. The organic solvent used for coating the charge transport layer is the same as that used for coating the charge generation layer.

The thickness of the charge transport layer is preferably 5 to 50 μm, more preferably 8 to 20 μm, and the weight ratio of the charge transport material to the binder is 5: 1 to 1: 5, further 3: 1 to 1: 3. preferable.

The charge generation layer and the charge transport layer can be applied by a coating method such as a dip coating method, a spray coating method, a Mayer bar coating method, a blade coating method and the like.

The photosensitive layer may be a single layer containing both the charge generating material and the charge transporting material, without being divided into two layers of the charge generating layer and the charge transporting layer.

The support can be formed of a conductive material such as aluminum, aluminum alloy, stainless steel, or the like. In addition, a support having a conductive surface layer formed on the surface of a support such as plastic, paper or metal can also be used. As the conductive surface layer, a vacuum deposited film of aluminum, an aluminum alloy, an indium oxide-tin oxide alloy, or the like, or a coating film in which conductive particles (for example, carbon black, tin oxide particles, etc.) are mixed in a binder and applied Can be used. The thickness of the conductive surface layer is preferably 1 to 30 μm.

If desired, an undercoat layer having a barrier function or an adhesive function may be provided between the support or the conductive surface layer and the photosensitive layer. The subbing layer can be formed of, for example, casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, modified polyamide, polyurethane, gelatin, aluminum oxide and the like. The thickness of the undercoat layer is 5 μm or less, further 0.5 to 3 μm
Is preferred. The undercoat layer preferably has a thickness of 10 ⁷ Ω · cm or more.

If desired, a protective layer may be provided on the photosensitive layer. For the protective layer, a resin such as polyvinyl butyral, polyester, polycarbonate (polycarbonate Z, modified polycarbonate, etc.), nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer, or the like is used. It can be formed by dissolving in a solvent, coating on the photosensitive layer and drying. The thickness of the protective layer is preferably 0.05 to 20 μm.
Further, an ultraviolet absorber or the like may be included in the protective layer.

The direct charging member 1 is roller-shaped, brush-shaped,
Any shape such as a blade shape, a belt shape, or a flat plate shape may be adopted. The direct charging member shown in FIGS. 4 and 5 is a roller-shaped member, and the elastic layer 3 is formed around the rod-shaped conductive core member 2.
It has a conductive layer 4 and a resistance layer 5.

As the conductive core material 2, a metal such as iron, copper or stainless steel, a conductive resin such as a carbon dispersed resin or a metal particle dispersed resin can be used, and the shape thereof is rod-like, plate-like or the like. Can be used.

The elastic layer 3 is a layer that is rich in elasticity and has a low hardness, and from the viewpoint of the adhesion to the photoreceptor and the vibration absorption,
The rubber hardness measured by a JIS-A type measuring instrument (trade name Telock GS-706: manufactured by Teclock Co., Ltd.) conforming to the measuring method of SK-6301 is 35 degrees or less, further 30 degrees or less, and particularly 12 degrees to 25 degrees. The range of is preferable. The thickness of the elastic layer 3 is 1.5 mm or more, and further 2 mm.
Above all, the range of 3 mm to 13 mm is particularly preferable. Examples of the material used for the elastic layer 3 include rubber or sponge such as chloroprene rubber, isoprene rubber, EPDM rubber, polyurethane rubber, epoxy rubber, and butyl rubber, styrene-butadiene thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyester-based thermoplastic. Examples thereof include plastic elastomers and thermoplastic elastomers such as ethylene-vinyl acetate-based thermoplastic elastomers. If necessary, conductive particles may be added to the elastic layer 3 in order to adjust its resistance.

The conductive layer 4 is a layer having high electric conductivity,
Volume resistivity is 10 ⁷ Ω · cm or less, and further 10 ⁶ Ω · c
It is preferably m or less, particularly in the range of 10 ⁻² Ω · cm to 10 ⁶ Ω · cm. The thickness of the conductive layer 4 is preferably a thin layer in order to convey the flexibility of the lower elastic layer 3 to the upper resistance layer 5, and is preferably 3 mm or less, more preferably 2 mm or less, and particularly 20.
The range of μm to 1 mm is preferable.

The material used for the conductive layer 4 may be a metal vapor deposition film, a conductive particle dispersed resin, a conductive resin, or the like. Examples of the metal vapor deposition film include those obtained by vapor deposition of metals such as aluminum, indium, nickel, copper, and iron. Examples of the conductive particle-dispersed resin include those in which conductive particles such as carbon, aluminum, nickel, and titanium oxide are dispersed in a resin such as urethane, polyester, vinyl acetate-vinyl chloride copolymer, and polymethylmethacrylate. To be Examples of the conductive resin include quaternary ammonium salt-containing polymethylmethacrylate, polyvinylaniline, polyvinylpyrrole, polydiacetylene, and polyethyleneimine.
Among these, the conductive particle-dispersed resin is preferable from the viewpoint of controlling the conductivity.

The resistance layer 5 is formed so as to have a higher resistance than the conductive layer 4, and has a volume resistivity of 10 ⁶ to 10 ^12.
Ω · cm, more preferably 10 ⁷ to 10 ¹¹ Ω · cm, and semiconductive resin, conductive particle-dispersed insulating resin and the like can be used. As the semiconductive resin, for example, ethyl cellulose, nitrocellulose, methoxymethylated nylon, ethoxymethylated nylon, copolymerized nylon,
Examples thereof include resins such as polyvinylpyrrolidone and casein, and mixtures of these resins. As the conductive particle-dispersed insulating resin, for example, carbon, aluminum,
Conductive particles such as indium oxide, titanium oxide, urethane, polyester, vinyl acetate-vinyl chloride copolymer,
An insulating resin such as polymethacrylic acid is dispersed in a small amount to adjust the resistance.

The film thickness of the resistance layer 5 is 1 μm or less from the viewpoint of charging property.
It is preferably 500 μm, particularly preferably 50 μm to 20 μm. The resistance layer 5 may be divided into two layers, an internal resistance layer and a surface resistance layer.

The internal resistance layer preferably has a resistance higher than the volume resistivity of the conductive layer 4 in the range of 10 to 10 ⁶ times, particularly 10 ² to 10 ⁵ times. The volume resistivity of the internal resistance layer is preferably in the range of 10 ⁶ Ω · cm to 10 ¹² Ω · cm, particularly preferably in the range of 10 ⁷ Ω · cm to 10 ¹¹ Ω · cm.
The film thickness of the internal resistance layer is preferably 1 μm to 450 μm, and particularly preferably 50 μm to 200 μm.

The material used for the internal resistance layer is, for example, a resin such as ethyl cellulose, nitrocellulose, methoxymethylated nylon, ethoxymethylated nylon, copolymerized nylon, polyvinylpyrrolidone or casein, or a mixture of these resins, or a mixture thereof. Semi-conductive resin in which a small amount of conductive particles are dispersed in resin, carbon, aluminum, indium oxide, conductive particles such as titanium oxide, urethane, polyester, vinyl acetate-vinyl chloride copolymer, polymethacrylate ester, etc. Conductive particle-dispersed insulating resin whose resistance is adjusted by dispersing a small amount in the insulating resin, epichlorohydrin rubber, epichlorohydrin-ethylene oxide rubber, polyurethane rubber, epoxy rubber, butyl rubber, chloroprene rubber, styrene-
Examples thereof include rubber such as butadiene rubber, a mixture of these rubbers, and semiconductive rubber in which conductive particles are dispersed and contained in these rubbers. Among these, semiconductive rubbers such as epichlorohydrin rubber and epichlorohydrin-ethylene oxide rubber are preferable.

When the internal resistance layer is made of resin,
From the viewpoint of flexibility, the tensile modulus of elasticity of the resin is 200 kgf / m
m²Below, especially 50kgf / mm²~ 150kgf /
mm ²Is preferred. The internal resistance layer is made of rubber.
If the rubber hardness is 35% or less,
Is preferably in the range of 10 degrees to 30 degrees.

As in the case of the internal resistance layer, the surface resistance layer has a higher resistance in the range of 10 to 10 ⁶ times, especially 10 ² to 10 ⁵ times the volume resistivity of the conductive layer 4. Is preferred. The resistance of the surface resistance layer may be lower, higher, or the same as that of the inner resistance layer. From the viewpoint of charging uniformity, the resistance of the internal resistance layer is preferably 1 to 50 times, and particularly 2 to 10 times higher than that of the surface resistance layer.
The volume resistivity of the surface resistance layer is 10 ⁶ Ω · cm to 10 ¹² Ω ·
The range is preferably in the range of 10 ⁷ Ω · cm to 10 ¹¹ Ω · cm. Further, the film thickness of the surface resistance layer is preferably thinner than the film thickness of the internal resistance layer so as not to impair the flexibility of the lower internal resistance layer, and is 0.1 μm to 50 μm.
m, particularly preferably in the range of 1 μm to 30 μm.

Examples of the material used for the surface resistance layer include resins such as the above-mentioned semiconductive resin and conductive particle dispersed insulating resin.

In addition to these layers, the direct charging member 1 may be provided with other layers such as an adhesive layer for improving the adhesiveness of each layer.

The direct charging member 1 is manufactured, for example, as follows.

First, a metal rod is prepared as the conductive core material 2. The elastic layer 3 is provided by molding the material of the elastic layer 3 on the metal rod by melt molding, injection molding, dip coating or spray coating.

Next, the material of the conductive layer 4 is formed on the elastic layer 3 by melt molding, injection molding, dip coating or spray coating to provide the conductive layer 4.

Finally, the resistance layer 5 is provided by coating the material of the resistance layer 5 on the conductive layer 4 by dip coating, spray coating, gravure coating, or the like.

The direct charging member shown in FIG. 6 is a flat charging member. A conductive layer 4 and a resistance layer 5 are provided on the elastic layer 3. In this case, there is no conductive core material 2.

The direct charging member in FIG. 7 is a blade-shaped charging member. A metal plate is used as the conductive core material 2, and the elastic layer 3 and the resistance layer 5 are formed thereon. In the direct charging member shown in FIG. 7, the elastic layer 3 is made conductive, so that the conductive layer 4 is not provided.

The direct charging member shown in FIGS. 8 and 9 is a brazing direct charging member in which the conductive fibers 26 are radially provided. The conductive fibers 26 are radially provided around the conductive core material 2 by the adhesive layer 25.

The conductive fiber 26 is a fiber having high electric conductivity, and has a volume resistivity of 10 ⁸ Ω · cm or less, and further 10 ⁶
It is preferably Ω · cm or less, and particularly preferably in the range of 10 ⁻² Ω · cm to 10 ⁻⁶ Ω · cm. Further, it is desirable that the thickness of one conductive fiber 26 is thin in order to maintain flexibility, and the diameter is 1 to 100 μm, further 5 to 50 μm, and particularly 8 to 30.
The range of μm is preferred. The length of the conductive fiber 26 is 2 to 1
It is preferably 0 mm, more preferably 3 to 8 mm.

As a material for forming the conductive fiber 26,
For example, the above-mentioned conductive particle dispersed resin, conductive resin, etc.
Can be used. In addition, carbon fiber is also conductive fiber
26 can be used. Used for conductive fiber 26
As the carbon fiber, for example, polyacrylonitrile
Partially carbonize fibers at processing temperatures of about 500-750 ° C
The carbon fiber thus obtained can be preferably used. this
About 10 carbon fibers ²-10^FiveHas a resistance of Ω · cm
ing. This type of carbon fiber is from Celanese
It is commercially available under the trade name CELECT675.

A resistance layer may be provided on the surface of the conductive fiber 26 for controlling the resistance. Conductive fiber 26
As the resistance layer provided in the above, the same one as the resistance layer 5 described in FIGS. 4 to 6 is used. The resistance layer provided on the conductive fiber 26 has a thickness of 0.01 μm to 5.0 μm, and further 0.5.
μm to 2.0 μm is preferable.

An example of the method of manufacturing the conductive fiber 26 is shown below.

First, carbon disulfide is added to alkali cellulose to prepare sodium cellulose xanthate. Next, conductive carbon is added to and dispersed in a dilute alkaline solution of sodium cellulose xanthate. Disperse this dispersion liquid from a spinning nozzle into a mixed aqueous solution of sulfuric acid and sodium sulfate,
The conductive cellulose fibers are formed by coagulating into a fibrous form while applying an appropriate tension.

When the resistance layer is provided on the surface of the conductive fiber, the resistance layer material is dissolved in a solvent, coated on the fiber, and dried.
A conductive fiber having a resistance layer is obtained.

The electrophotographic apparatus shown in FIG. 10 has the roller-shaped direct charging member 1 used in the electrophotographic apparatus of FIG.
This is a brush-shaped direct charging member 100 instead.

The direct charging member shown in FIGS. 11 and 12 has a conductive fiber 26 provided on one surface of a metal flat plate 27 with an adhesive layer 25 interposed therebetween.

The electrophotographic apparatus shown in FIG. 13 has the roller-shaped direct charging member 1 used in the electrophotographic apparatus of FIG.
Brush-like direct charging member 10 shown in FIGS. 11 and 12.
1, the roller-shaped direct charging member 23 of FIG. 2 used as the transfer charging means is replaced by the brush-shaped direct charging member 102.
It is a substitute.

The conductive fibers 26 are preferably provided on the surface of the adhesive layer 25 at a density of 1 × 10 ^{4 to} 5 × 10 ⁶ fibers / cm ² .

According to the present invention, the dark potential and the light potential of the electrophotographic photosensitive member can be kept constant even in an environment of high temperature and high humidity. Therefore, even if copying is continuously performed, no image defect occurs and a high quality image can be obtained.

[0066]

The present invention will be described in more detail with reference to the following examples. The "parts" shown below are "parts by weight". [Manufacturing Example 1] The direct charging member shown in FIG. 4 was manufactured as follows.

First, an iron core having a diameter of 3 mm and a length of 340 mm is used as a conductive core material, and JISK-63 is provided around the core material.
A chloroprene rubber having a rubber hardness of 15 ° measured by a JIS-A type measuring device (rubber hardness meter TECLOCK GS-706 manufactured by TECLOCK) based on No. 01, a thickness of 3.5.
mm and a width of 330 mm were melted to provide an elastic layer.

Next, a conductive carbon particle-dispersed polyurethane paint (trade name: Shintron, manufactured by Shinto Paint Co., Ltd.) was dip-coated on the elastic layer, and after drying, a conductive layer having a thickness of 1 mm was provided.

Next, 10 parts of epichlorohydrin rubber (trade name: hydrin, manufactured by Zeon Corporation), 1 part of silicresyl phosphate (TCP), 0.3 part of zinc oxide, and powdered sulfur 0.
2 parts, vulcanization accelerator (trimercaptotriazine) 0.1
And 90 parts of tetrahydrofuran (THF) are mixed,
This mixed solution is applied onto the conductive layer by dip coating and dried to a film thickness of 90
The internal resistance layer has a thickness of μm.

Next, 1 part of conductive carbon (trade name: Ketzen Black, manufactured by Lion), 19 parts of methoxymethylated nylon and 0.01 part of a surfactant (trade name: sorbitol, manufactured by Ajinomoto) are mixed with 80 parts of methanol. And dispersed by a ball mill to prepare a coating liquid. This coating solution was spray-coated on the internal resistance layer so that the film thickness after drying was 10 μm to form a surface resistance layer. Thus, the direct charging member shown in FIG. 4 was obtained.

The conductive layer, the internal resistance layer and the surface resistance layer are separately applied by dip coating on an aluminum sheet,
The volume resistivity of each layer was measured.

The volume resistivity was measured by Hewlett-Packard Company 16008A Resistivity C.
It was measured under an applied voltage of 10 V, a temperature of 22 conductivity, and a humidity of 60%.

The measurement result shows that the conductive layer is 4 × 10 ⁴ Ω · cm,
Internal resistance layer 7 × 10 ⁹ Ω · cm, surface resistance layer 2 × 1
It was ⁰⁹ Ω · cm.

[Production Example 2] A roller-like direct charging member was produced as follows.

100 parts of chloroprene rubber, 5 parts of conductive carbon (trade name: Ketzen black, manufactured by Lion) and a surfactant (trade name: sorbitol, manufactured by Ajinomoto) 0.0
5 parts were melt-kneaded. Next, diameter 5mm, length 350mm
The melted and kneaded chloroprene rubber was provided around the stainless steel core material described in (1) to have a thickness of 6.5 mm and a width of 320 mm to form a roller-like direct charging member as a conductive elastic layer.

The volume resistance of this conductive elastic layer was measured in the same manner as in Production Example 1 above. As a result, it was 4 × 10 ⁶ Ω · cm.

[Manufacturing Example 3] The direct charging member shown in FIG. 8 was manufactured as follows.

First, an iron core having a diameter of 3 mm and a length of 340 mm was used as a conductive core material, and 10 parts of conductive carbon (trade name: Conductectex C-975, Colombian carbon) and polyvinyl were formed on the outer peripheral surface of the core material. A dispersion containing 90 parts of butyral (trade name: S-REC BLS, manufactured by Sekisui Chemical Co., Ltd.) dispersed in 300 parts of methyl ethyl ketone was applied to a film thickness of 1 mm to form an adhesive layer.

As the conductive fiber, the conductive cellulose fiber produced by the above-mentioned method was used. The diameter of this conductive fiber was 10 μm, and the resistance value was 5 × 10 ⁵ Ω · cm. This conductive fiber was cut into a length of 5 mm, provided on the adhesive layer so as to have a density of 1 × 10 ⁵ fibers / cm ² , and the adhesive layer was dried by heating. Thus, the direct charging member shown in FIG. 8 was obtained.

[Manufacturing Example 4] The direct charging member shown in FIG. 11 was manufactured as follows.

First, the width is 5 mm, the thickness is 1 mm, and the length is 350.
The dispersion liquid used in Production Example 3 was applied to one surface of a stainless steel plate having a thickness of 1 mm so as to have a film thickness of 1 mm to form an adhesive layer.

Next, carbonized acrylonitrile fiber (resistance value 3 × 10 ⁶ Ω · cm, diameter 8 μm) was used for length 3
The adhesive layer was cut to a size of 5 mm and provided on the adhesive layer so as to have a density of 5 × 10 ⁴ lines / cm ² , and the adhesive layer was dried by heating. Thus, the direct charging member shown in FIG. 11 was obtained. [Example 1] 50 parts of titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts of resol type phenol resin, 20 parts of methyl cellosolve, 5 parts of methanol and silicone oil (polydimethylsiloxane polyoxyalkylene) Copolymer, average molecular weight 3000)
0.002 part was dispersed for 2 hours in a sand mill using glass beads having a diameter of 1 mm to prepare a conductive surface layer coating material.

Aluminum cylinder (outer diameter 30 mm,
(Length: 350 mm, thickness: 0.8 mm), the above coating material is applied by the dipping method and dried at 140 ° C. for 30 minutes,
A conductive surface layer having a film thickness of 20 μm was formed.

Next, a solution prepared by dissolving 5 parts of N-methoxymethylated nylon resin in a mixed solvent of 70 parts of methanol and 25 parts of butanol was applied to the conductive surface layer by a dipping method and dried to obtain a layer having a thickness of 1 μm. A pull layer was provided.

Next, the disazo pigment 4 represented by the formula (2)
And the formula (2)

[0086]

Embedded image Polyvinyl butyral resin 2 parts and cyclohexanone 1
It was added to 00 parts and dispersed for 1 hour with a sand mill using glass beads having a diameter of 1 mm, and 100 parts of methyl ethyl ketone was added to dilute it. The solution thus obtained is applied onto the undercoat layer and dried at 80 ° C. for 10 minutes to give a film thickness of 0.1.
A 5 μm charge generation layer was formed.

Next, the following structural formula

[0088]

[Chemical 19] A solution was prepared by dissolving 8 parts of the charge transport material represented by and 10 parts of a bisphenol Z-type polycarbonate resin (number average molecular weight 22,000) in 60 parts of monochlorobenzene,
This solution was applied on the charge generation layer by a dipping method. This was dried at a temperature of 110 ° C. for 1 hour to form a charge transport layer having a thickness of 20 μm to manufacture an electrophotographic photoreceptor.

Example 2 An electrophotographic photosensitive member was produced in the same manner as in Example 1, except that the disazo pigment of Example 1 was replaced by the disazo pigment represented by the formula (3). Formula (3)

[0090]

Embedded image

Example 3 An electrophotographic photosensitive member was manufactured in the same manner as in Example 1 except that the disazo pigment of Example 1 was replaced with the disazo pigment represented by the formula (4). Formula (4)

[0092]

[Chemical 21]

Comparative Example 1 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the disazo pigment of Example 1 was replaced with the disazo pigment represented by the structural formula below.

[0094]

[Chemical formula 22]

Examples 1, 2 and 3 created as described above
The electrophotographic photoreceptors of No. 3 and Comparative Example 1 were installed in the electrophotographic apparatus shown in FIG. 1 and a durability test was conducted.

The electrophotographic apparatus used was a copying machine NP-2020 manufactured by Canon Inc. modified to a direct charging system.
The charging member of Production Example 1 was used as the direct charging member. A DC voltage of -720 V and a peak-to-peak voltage of 15
An AC voltage of 00V was superimposed and applied to set the dark potential of the photoconductor to -700V. Next, the photosensitive member was imagewise exposed with white light to set the bright portion potential to -150V.

An endurance test was carried out under the environment of a temperature of 30 ° C. and a humidity of 90%, in which each of the photoconductors was set to the above potential and copying was continuously performed on 50,000 sheets of recording paper. The durability test was evaluated by a change in dark area potential, a change in bright area potential, and image quality. FIG. 14 shows changes in the dark part potential and changes in the bright part potential of the above-described four types of photoconductors.

In Examples 1, 2 and 3, the potential was stable, and images of high image quality with no image defects were obtained.

In Comparative Example 1, a fog image was obtained after 25,000 sheets.

[Comparative Examples 2 to 4] A photoconductor similar to that of Example 1 and a corona charging type copying machine (trade name: NP-202).
No. 0 (manufactured by Canon Inc.) was used and a durability test was conducted in the same manner as in Example 1 (Comparative Example 2). A durability test was conducted in the same manner as in Comparative Example 2 except that the same photoreceptor as that in Example 2 was used (Comparative Example 3). A durability test was conducted in the same manner as in Comparative Example 2 except that the same photoreceptor as that in Example 3 was used (Comparative Example 4). FIG. 15 shows changes in the dark part potential and changes in the bright part potential of the above three types of photoconductors.

In Comparative Example 2, the image density started to decrease from 25,000 sheets.

In Comparative Example 3, the image density started to decrease from 16,000 sheets.

In Comparative Example 4, the image density started to decrease from 10,000 sheets.

Example 4 As the charge transport material, the following structural formula was used.

[0105]

[Chemical formula 23] An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the compound represented by

The electrophotographic photosensitive member thus prepared is shown in FIG.
The durability test was performed in the same manner as in Example 1 except that the apparatus was installed in the electrophotographic apparatus shown in FIG.

The electrophotographic apparatus used is a copying machine NP-2020 made by Canon Inc. modified to a direct charging system.
The charging member of Production Example 1 was used as the direct charging member 1, and the charging member of Production Example 2 was used as the direct charging member 23.

FIG. 16 shows changes in the dark portion potential and changes in the light portion potential of the above-mentioned photoconductor. As is apparent from FIG. 16, the potential was stable, and the image obtained was of high quality with no image defects.

Example 5 As the charge transport material, the following structural formula was used.

[0110]

[Chemical formula 24] An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the compound represented by

The electrophotographic photosensitive member thus prepared is shown in FIG.
The durability test was performed in the same manner as in Example 1 except that the apparatus was installed in the electrophotographic apparatus shown in FIG.

The electrophotographic apparatus used is a direct charging member 1.
The charging member of Production Example 1 is used as the above, and the charging member of Production Example 2 is used as the direct charging member 23.

FIG. 16 shows changes in the dark portion potential and changes in the bright portion potential of the above-mentioned photoconductor. As is apparent from FIG. 16, the potential was stable, and the image obtained was of high quality with no image defects.

[Embodiment 6] A photoreceptor similar to that of Embodiment 1 and the electrophotographic apparatus shown in FIG.
A durability test was conducted in the same manner as in.

The electrophotographic apparatus used is a copying machine NP-2020 manufactured by Canon Inc. modified to a direct charging system.
The charging member of Production Example 3 was used as the direct charging member 1.

As a result of the durability test, the same results as in Example 1 were obtained.

Example 7 An endurance test was conducted in the same manner as in Example 1 except that the same electrophotographic photoreceptor as in Example 4 and the electrophotographic apparatus shown in FIG. 13 were used.

The electrophotographic apparatus used is a copying machine NP-2020 made by Canon Inc. modified to a direct charging system.
Using the charging member of Production Example 4 as the direct charging member 101,
The charging member of Production Example 3 was used as the direct charging member 23.

As a result of the durability test, the same results as in Example 4 were obtained.

[0120]

According to the electrophotographic image forming method, electrophotographic apparatus and electrophotographic apparatus unit of the present invention, the potential is stable and image defects do not occur even when repeatedly used under high temperature and high humidity.

[Brief description of drawings]

FIG. 1 is a front view showing an example of an electrophotographic apparatus of the present invention.

FIG. 2 is a front view showing another example of the electrophotographic apparatus of the present invention.

FIG. 3 is a front view showing another example of the electrophotographic apparatus of the present invention.

FIG. 4 is a front view showing an example of a direct charging member used in the electrophotographic apparatus of the present invention.

5 is a side sectional view of the direct charging member shown in FIG.

FIG. 6 is a front view showing another example of the direct charging member used in the electrophotographic apparatus of the present invention.

FIG. 7 is a front view showing another example of the direct charging member used in the electrophotographic apparatus of the present invention.

FIG. 8 is a front view showing another example of the direct charging member used in the electrophotographic apparatus of the present invention.

9 is a side sectional view of the direct charging member shown in FIG.

FIG. 10 is a front view showing another example of the electrophotographic apparatus of the present invention.

FIG. 11 is a front view showing another example of the direct charging member used in the electrophotographic apparatus of the present invention.

12 is a side view of the direct charging member shown in FIG.

FIG. 13 is a front view showing another example of the electrophotographic apparatus of the present invention.

FIG. 14 is a graph showing durability test results of Examples 1 to 3 and Comparative Example 1.

FIG. 15 is a graph showing the results of durability tests of Comparative Examples 2-4.

FIG. 16 is a graph showing the results of durability tests of Examples 4 and 5.

[Explanation of symbols]

 1, 100, 101 Direct charging member 7 Developing means 8 Transfer charging means 9 Recording material 10 Cleaning means 12 Photoreceptor

Claims (19)

[Claims] 1. A photosensitive layer having the following general formula (1) and general formula (1): (In the formula, Cp1 and Cp2 coupler residues are shown.) An electrophotographic photosensitive member containing an azo pigment represented by the formula (3) is charged by direct charging, and image exposure is performed on the charged electrophotographic photosensitive member. And an image exposing step for forming an electrostatic latent image, and a developing step for developing the electrophotographic photosensitive member on which the electrostatic latent image is formed. 2. The azo pigment has the formula (2): The electrophotographic image forming method according to claim 1, which is a disazo pigment represented by: 3. The azo pigment has the formula (3), the formula (3): The electrophotographic image forming method according to claim 1, which is a disazo pigment represented by: 4. The azo pigment has the formula (4), the formula (4): The electrophotographic image forming method according to claim 1, which is a disazo pigment represented by: 5. The electrophotographic image forming method according to claim 1, wherein the direct charging is performed by a direct charging member to which a DC voltage is applied. 6. The electrophotographic image forming method according to claim 5, wherein an AC voltage is superimposed on the DC voltage. 7. A photosensitive layer having the following general formula (1) and general formula (1): (In the formula, Cp1 and Cp2 coupler residues are shown.), An electrophotographic photoreceptor containing an azo pigment, and a direct charging member that contacts the electrophotographic photoreceptor to charge the electrophotographic photoreceptor. An image exposure unit that forms an electrostatic latent image by performing image exposure on the charged electrophotographic photosensitive member; and a developing unit that develops the electrophotographic photosensitive member on which the electrostatic latent image is formed. Electrophotographic device. 8. The azo pigment has the formula (2), the formula (2): The electrophotographic apparatus according to claim 7, which is a disazo pigment represented by: 9. The azo pigment has the formula (3): The electrophotographic apparatus according to claim 7, which is a disazo pigment represented by: 10. The azo pigment has the formula (4): The electrophotographic apparatus according to claim 7, which is a disazo pigment represented by: 11. The electrophotographic apparatus according to claim 7, wherein the direct charging member has a roller shape. 12. The electrophotographic apparatus according to claim 7, wherein the direct charging member has a brush shape. 13. A photosensitive layer having the following general formula (1) and general formula (1) (In the formula, Cp1 and Cp2 coupler residues are shown.) An electrophotographic photosensitive member containing an azo pigment, and a direct charging member for contacting the electrophotographic photosensitive member to charge the electrophotographic photosensitive member are provided. An electrophotographic apparatus unit, characterized by being integrally connected and detachably attached to the apparatus body. 14. The electrophotographic apparatus unit according to claim 13, further comprising a developing means for developing the electrostatic latent image formed on the electrophotographic photosensitive member. 15. The azo pigment has the formula (2), the formula (2): The electrophotographic apparatus unit according to claim 13, which is a disazo pigment represented by: 16. The azo pigment has the formula (3): The electrophotographic apparatus unit according to claim 13, which is a disazo pigment represented by: 17. The azo pigment has the formula (4): The electrophotographic apparatus unit according to claim 13, which is a disazo pigment represented by: 18. The electrophotographic apparatus unit according to claim 13, wherein the direct charging member has a roller shape. 19. The electrophotographic apparatus unit according to claim 13, wherein the direct charging member has a brush shape.