JP2000231210A - Electrophotographic photoreceptor, electrophotographic method, electrophotographic apparatus, and process cartridge for electrophotographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable electrophotographic photoreceptor which does not cause a decrease in chargeability and a rise in residual potential even when repeatedly used without losing high sensitivity, and is repeated without losing high sensitivity. Provide a stable electrophotographic method that does not cause a decrease in chargeability and increase in residual potential even when used, and a stable electron that does not cause a decrease in chargeability and increase in residual potential even after repeated use without losing high sensitivity. To provide a photographic device and a process cartridge for an electrophotographic device. An electrophotographic photoreceptor having a photosensitive layer formed by laminating a charge generation layer containing at least an organic pigment and a charge transport layer on a conductive support has a water vapor permeability of the charge transport layer of 100 g · m ⁻² · day ⁻¹ or less, and the average particle size of the organic pigment contained in the charge generation layer is 0.1.
An electrophotographic photosensitive member having a thickness of 5 μm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photoreceptor,
More specifically, the present invention relates to an electrophotographic method, an electronic apparatus, and a process cartridge for an electrophotographic apparatus using the same. The present invention relates to an electrophotographic method, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus.

[0002]

2. Description of the Related Art In recent years, the development of information processing systems using electrophotography has been remarkable. In particular, optical printers that convert information into digital signals and record information with light have significantly improved print quality and reliability. This digital recording technology is applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. In addition, since a copier equipped with the digital recording technology in a conventional analog copy is added with various information processing functions, its demand is expected to increase more and more in the future.

At present, semiconductor lasers (LDs) and light-emitting diodes (LEDs) that are small, inexpensive and highly reliable have been widely used as light sources for optical printers. The emission wavelength of currently used LEDs is 660 nm, and L
The emission wavelength range of D is in the near infrared region. Therefore, development of an electrophotographic photosensitive member having high sensitivity from a visible light region to a near infrared light region is desired.

The photosensitive wavelength range of an electrophotographic photosensitive member is almost determined by the photosensitive wavelength range of a charge generating substance used in the photosensitive member. Therefore, many charge generation substances such as various azo pigments, polycyclic quinone pigments, trigonal selenium, various phthalocyanine pigments, etc. have been developed. Among them, titanyl phthalocyanine (abbreviated as TiOPc) is 60
In order to show high sensitivity to long wavelength light from 0 to 800 nm,
It is extremely important and useful as a material for a photoreceptor for an electrophotographic printer or a digital copying machine in which a light source is an LED or LD.

On the other hand, the conditions of the electrophotographic photosensitive member repeatedly used in the Carlson process and similar processes include sensitivity, accepting potential, potential holding property, potential stability,
It is required that the electrostatic characteristics represented by the residual potential and the spectral characteristics be excellent. In particular, for high-sensitivity photoreceptors, the chargeability decreases and the residual potential increases due to repeated use.
It is empirically known that many photoconductors control the life characteristics of the photoconductor.

One of the causes is considered to be the influence of the reactive gas in the atmosphere in which the photosensitive member is used. The photoreceptor use atmosphere includes an atmosphere of an environment in which a system including an electrophotographic method, an apparatus, and a process is placed, and ozone, NOx, and the like generated from a portion related to charging such as a scorotron in the system. No.

As measures against such a reactive gas, for example, JP-A-2-37359 and JP-A-8-2
As described in Japanese Patent No. 72126, increasing the gas barrier property of the charge transport layer is one means, but there are cases where it is not always satisfactory. Further, the charge / photosensitivity of the photoreceptor directly relates to the lower layer (mostly the charge generation layer) below the charge transport layer, and at present the approach from the charge generation layer has not been made.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a stable electrophotographic photoreceptor which does not lose its chargeability and does not increase its residual potential even when repeatedly used without losing high sensitivity. Another object of the present invention is to provide a stable electrophotographic method which does not cause a decrease in chargeability and a rise in residual potential even when repeatedly used without losing high sensitivity. It is another object of the present invention to provide a stable electrophotographic apparatus and a process cartridge for the electrophotographic apparatus which do not cause a decrease in chargeability and an increase in residual potential even when repeatedly used without losing high sensitivity.

[0009]

Means for Solving the Problems The present inventors have studied in view of the above-mentioned problems, and as a result, have found that the water vapor permeability of the charge transport layer is 100 g · m ⁻² · day ⁻¹ or less, and the charge generation The average particle size of the organic pigment contained in the layer is 0.5 μ
It has been found that the above problems can be solved by using a photoreceptor having a diameter of m or more, and the present invention has been completed.

Therefore, according to the present invention, there is provided (1) an electrophotographic photosensitive member having a photosensitive layer comprising a conductive support and a charge generating layer containing at least an organic pigment and a charge transport layer laminated on the conductive support. The water vapor permeability of the charge transport layer is 100 g
M- ² · day ^-1 or less, and the average particle size of the organic pigment contained in the charge generation layer is 0.5 μm or more ”; (3) The electrophotographic photoreceptor according to the above (1), wherein the pigment is titanyl phthalocyanine; (3) the organic pigment is at least CuKα characteristic X-ray (wavelength 1.
(5) The electrophotographic photoreceptor according to the above (1), wherein the maximum diffraction peak at a Bragg angle of 2θ with respect to 514 °) is titanyl phthalocyanine at 27.2 ± 0.2 °. The electrophotographic photoreceptor according to any one of the above items (1) to (3), wherein the binder resin used in the charge transport layer is at least polycarbonate.

According to the present invention, (5) the invention is characterized in that “the polycarbonate is a polycarbonate containing at least a structure represented by the following formula (1) and / or the following formula (2) in a repeating unit: The electrophotographic photoreceptor according to the above (4), "

[0012]

Embedded image … (1)

[0013]

Embedded image … (2)

(6) Any of the above items (1) to (4), wherein the charge transport layer contains a polycarbonate containing at least a triarylamine structure in a main chain and / or a side chain. Or the electrophotographic photosensitive member according to item 1).

According to the present invention, (7) "Electrophotographic feeling"
At least charge, image exposure, development, transfer,
Electrophotography method that repeats cleaning and static elimination
The electrophotographic photoreceptor is placed on at least a conductive support.
Contains organic pigments having a uniform particle size of 0.5 μm or more
Charge generation layer and water vapor permeability of 100 gm^-2・ Day
^-1Electrophotographic photoreceptor obtained by laminating the following charge transport layers
And (8) "the electrophotographic method described above."
Characterized in that the organic pigment is titanyl phthalocyanine
The electrophotographic method according to the above (7) ", (9)
"The organic pigment is at least CuKα characteristic X-ray (wavelength
1.514 °) maximum diffraction peak of Bragg angle 2θ
Titanyl phthalocyanine at 27.2 ± 0.2 °
The electronic photograph according to the above (7), wherein
A "true way" is provided.

According to the present invention, there is provided (10) an electrophotographic apparatus comprising at least a charging unit, an image exposing unit, a developing unit, a transferring unit, a cleaning unit, a discharging unit, and an electrophotographic photosensitive member. The electrophotographic photoreceptor has a charge generation layer containing at least an organic pigment having an average particle size of 0.5 μm or more on a conductive support, and a charge transport layer having a water vapor transmission rate of 100 g · m ⁻² · day ⁻¹ or less. (11) An electrophotographic apparatus according to (10), wherein the organic pigment is titanyl phthalocyanine. Apparatus ", (12)" the organic pigment has a maximum diffraction peak of 27.2 ± 0.2 ° at a Bragg angle 2θ with respect to at least the characteristic X-ray (wavelength 1.514 °) of CuKα.
(11) The electrophotographic apparatus according to the above (11), wherein the titanyl phthalocyanine is used.

Furthermore, according to the present invention, there is provided (13) a process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member has an average particle size on at least a conductive support. 0.5 μm in size
An electrophotographic photoreceptor comprising an electrophotographic photosensitive member comprising a charge generation layer containing an organic pigment as described above and a charge transport layer having a water vapor transmission rate of 100 g · m ⁻² · day ⁻¹ or less. Process cartridge ", (14)" a process cartridge for an electrophotographic apparatus according to the above (13), wherein the organic pigment is titanyl phthalocyanine ", and (15)" the organic pigment is at least CuKα. (13) The electrophotographic apparatus according to the above (13), wherein the titanyl phthalocyanine has a maximum diffraction peak at a Bragg angle 2θ of 27.2 ± 0.2 ° with respect to characteristic X-rays (wavelength 1.514 °). Process cartridge "is provided.

The water vapor transmission rate of the charge transport layer greatly depends on the material, structure, and film thickness used for the charge transport layer. Materials with good film-forming properties and high gas barrier properties are effectively used,
Such materials include polycarbonate,
Useful. Among them, the materials represented by the above formulas (1) and (2) are very useful because they have relatively high gas barrier properties and excellent wear resistance. The material represented by the formula (1) has particularly high durability. Also,
Polymeric charge transporting materials having both a function as a charge transporting material and a function as a binder resin are effectively used, and among them, polycarbonates containing at least a triarylamine structure in a main chain and / or a side chain are very useful.

The charge transport layer is generally constituted as a mixture of a low molecular material and a high molecular material. Usually, it is used in the form of a so-called solid solution in which a low molecular material is compatible with a high molecular material. In the case of such a configuration, the low molecular weight material fills the voids (free volume) existing in the solid state polymer material due to the difference in molecular size, thereby improving the gas barrier property. For this reason, molecularly dispersed polymers are a useful construction method. However, the charge transport layer made of a molecular dispersion polymer is generally soft, and has a drawback that the Carlson process easily causes film shaving due to repeated use.
Since the abrasion of the charge transport layer having this configuration depends on the concentration of the low-molecular material, it can be improved by setting the minimum use amount according to the purpose. Addition of a material exhibiting a plasticizing effect on a polymer is an extremely effective means when a polymer having a large free volume is used.

Further, even when the same material is used and the charge transport layer is manufactured with the same configuration, the water vapor permeability depends in a manner inversely proportional to the thickness of the charge transport layer. That is, in the charge transport layer as described above, the gas barrier property improves as the film thickness increases. However, if the thickness of the charge transport layer is too large, side effects such as a decrease in the response speed of the photoreceptor, bleeding of an electric charge, and easy occurrence of image blur and thickening may occur. It is important to set an appropriate film thickness in consideration of such points.

As described above, the water vapor transmission rate depends on the material used, the composition, the film thickness, etc., but the influence of the reactive gas has a large effect on the layer below the charge transport layer.
100g ・ m ^-2・ day ^-1 irrespective of composition and film thickness
It is important that: Note that a commercially available measuring device can be used for measuring the water vapor permeability.

With respect to the charge generating material, phthalocyanines are usefully used for an LD light source. Among them, titanyl phthalocyanine, and among them, the maximum diffraction peak of the Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.514 °) of CuKα is 27. Titanyl phthalocyanine at 2 ± 0.2 ° is particularly useful as a sensitive material. The average particle size of the charge generation material in the charge generation layer used in the present photoreceptor is preferably 0.5 μm or more, and the average particle size may be any value as long as it can be formed as a coating film, but is preferably about 2 μm or less. preferable. This is because when the reactive gas that has passed through the charge transport layer attacks the charge generating substance,
It is considered that the effect substantially depends on the surface area of the charge generation material, and the surface area depends on the particle size.

With respect to the particle size of the pigment, a method of directly observing the charge generation layer (for example, by slicing a thin section of the photosensitive layer and observing it with a transmission electron microscope) is most preferable, but the charge generation layer is formed. It is also possible to measure the particle size in the coating liquid for the measurement and substitute it. in this case,
It is also possible to use a commercially available particle size distribution analyzer, but hang the coating liquid thinly on a conductive-treated net,
Drying and observation with a transmission electron microscope or the like is preferable because it is closest to the actual photoconductor.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an electrophotographic photoreceptor used in the present invention. A charge generating layer (35) containing a charge generating material as a main component and a charge transporting material on a conductive support (31). And a charge transporting layer (37) whose main component is.

As the conductive support (31), those having a conductivity of not more than 10 ¹⁰ Ω · cm, such as aluminum, nickel, chromium, nichrome, copper, gold, silver,
Metals such as platinum, tin oxide, metal oxides such as indium oxide, coated on film or cylindrical plastic or paper by evaporation or sputtering,
Alternatively, a plate made of aluminum, an aluminum alloy, nickel, stainless steel, or the like, or a tube formed by extruding, drawing, or the like, and then surface-treated such as cutting, superfinishing, or polishing can be used. Further, an endless nickel belt and an endless stainless belt disclosed in JP-A-52-36016 can also be used as the conductive support (31).

In addition, a support obtained by dispersing a conductive powder in a suitable binder resin on the above support and applying the same can also be used as the conductive support (31) of the present invention. This conductive powder includes carbon black, acetylene black, aluminum, nickel, iron, nichrome, copper,
Metal powder such as zinc and silver, conductive tin oxide, IT
And metal oxide powders such as O. The binder resins used simultaneously include polystyrene and styrene-
Acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride,
Polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, Thermoplastic, thermosetting resins or photo-curing resins such as alkyd resins. Such a conductive layer can be provided by dispersing the conductive powder and the binder resin in an appropriate solvent, for example, tetrahydrofuran, dichloromethane, methyl ethyl ketone, toluene, or the like, and applying the resulting dispersion.

Further, a conductive layer is formed on a suitable cylindrical substrate by a heat-shrinkable tube in which the above-mentioned conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester polystyrene, polyvinylidene chloride, polyethylene, chloride rubber, and Teflon. Can be favorably used as the conductive support (31) of the present invention.

Next, the photosensitive layer will be described. The photosensitive layer is composed of a laminate of a charge generation layer (35) and a charge transport layer (37).

The charge generation layer (35) is a layer containing a charge generation material as a main component. The charge generation layer (35) is prepared by dispersing the charge generation material together with a binder resin as necessary in a suitable solvent by using a ball mill, an attritor, a sand mill, ultrasonic waves, or the like, and coating this on a conductive support. , Formed by drying.

The charge generation layer (35) includes a monoazo pigment,
Disazo pigments, triazozo pigments, perylene pigments, perinone pigments, quinacridone pigments, quinone condensed polycyclic compounds, squaric acid dyes, other phthalocyanine pigments, naphthalocyanine pigments, azulhenium salt dyes and the like are used. Can be In particular, phthalocyanines are usefully used. Among them, titanyl phthalocyanine, and among them, titanyl phthalocyanine having a maximum diffraction peak of Bragg angle 2θ with respect to characteristic X-ray (wavelength 1.514 °) of CuKα at 27.2 ± 0.2 ° is It is particularly useful as a sensitive material. At this time, it is very important that the average particle size of the charge generation material used for the charge generation layer (35) is 0.5 μm or more. This size varies depending on the material used, the dispersing device, and the dispersing conditions, but it is preferable to conduct sufficient experiments before use to determine the conditions.

If necessary, the binder resin used for the charge generation layer (35) includes polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, Polystyrene, polysulfone, poly-N-vinylcarbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide,
Polyamide, polyvinyl pyridine, cellulosic resin,
Casein, polyvinyl alcohol, polyvinylpyrrolidone, and the like. The amount of the binder resin is 0 to 500 parts by weight, preferably 10 to 100 parts by weight of the charge generating substance.
~ 300 parts by weight is suitable.

Examples of the solvent used herein include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. No. The coating method of the coating solution includes dip coating, spray coating, beat coating, nozzle coating, spinner coating,
A method such as a ring coat can be used. The thickness of the charge generation layer (35) is suitably about 0.01 to 5 μm, and preferably 0.1 to 2 μm.

The charge transporting layer (37) can be formed by dissolving or dispersing the charge transporting substance and the binder resin in a suitable solvent, applying the solution on the charge generating layer, and drying. If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.

The charge transport material includes a hole transport material and an electron transport material. Examples of the charge transport material include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone,
2,4,8-trinitrothioxanthone, 2,6,8-
Examples thereof include electron accepting substances such as trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and benzoquinone derivatives.

Examples of the hole transport material include poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, polysilane, Oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives,
α-phenylstilbene derivative, benzidine derivative,
Diarylmethane derivatives, triarylmethane derivatives,
9-styrylanthracene derivatives, pyrazoline derivatives,
Other known materials such as a divinylbenzene derivative, a hydrazone derivative, an indene derivative, a butadiene derivative, a pyrene derivative, a bisstilbene derivative, an enamine derivative and the like can be used. These charge transport materials are used alone or in combination of two or more.

Examples of the binder resin include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and polystyrene. Vinyl acetate, polyvinylidene chloride, polyalate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane Thermoplastic or thermosetting resins such as resin, phenolic resin, and alkyd resin are exemplified. Among them, the polycarbonates represented by the above formulas (1) and (2) can be used favorably because they are materials having relatively high gas barrier properties and excellent abrasion resistance.

The amount of the charge transporting substance is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, per 100 parts by weight of the binder resin.
Parts by weight are appropriate. The charge transport layer has a thickness of 5-1.
It is preferable that the thickness be about 00 μm. As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.

For the charge transporting layer, a polymer charge transporting material having both a function as a charge transporting material and a function as a binder resin is preferably used. The charge transport layer composed of such a polymer charge transport material is extremely excellent in abrasion resistance. As the polymer charge transport material, known materials can be used, but polycarbonates containing a triarylamine structure in the main chain and / or side chain are preferably used.
Among them, the polymer charge transport materials represented by the formulas (3) to (12) are preferably used, and these are exemplified below and specific examples are shown.

[0039]

Embedded image (3) In the formula, R ₁ , R ₂ and R ₃ are each independently a substituted or unsubstituted alkyl group or a halogen atom, R ₄ is a hydrogen atom or a substituted or unsubstituted alkyl group, R ₅ and R ₆ Is a substituted or unsubstituted aryl group, o, p, and q are each independently an integer of 0 to 4, k and j represent compositions, and 0.1 ≦
k ≦ 1, 0 ≦ j ≦ 0.9, n represents the number of repeating units and is an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula.

[0040]

Embedded image ... (4) In the formula, R ₁₀₁ and R ₁₀₂ each independently represent a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4; Y is a single bond;
~ 12 linear, branched or cyclic alkylene groups,
-O -, - S -, - SO -, - SO 2 -, - CO -, -
CO—O—Z—O—CO— (wherein, Z represents an aliphatic divalent group) or

[0041]

Embedded image In the formula, a is an integer of 1 to 20, b is an integer of 1 to 2000,
R ₁₀₃ and R ₁₀₄ represent a substituted or unsubstituted alkyl group or aryl group. ). Where R ₁₀₁ and R ₁₀₂ ,
R ₁₀₃ and R ₁₀₄ may be the same or different.

[0042]

Embedded image ... (4) wherein R ₇ and R ₈ are a substituted or unsubstituted aryl group, A
r ₁ , Ar ₂ and Ar ₃ represent the same or different arylene groups. X, k, j and n are the same as in the case of equation (3).

[0043]

Embedded image ... (5) wherein R ₉ and R ₁₀ are a substituted or unsubstituted aryl group;
Ar ₄ , Ar ₅ and Ar ₆ represent the same or different arylene groups. X, k, j and n are the same as in the case of equation (3).

[0044]

Embedded image ... (6) wherein R ₁₁ and R ₁₂ are a substituted or unsubstituted aryl group;
Ar ₇ , Ar ₈ and Ar ₉ are the same or different arylene groups, p
Represents an integer of 1 to 5. X, k, j and n are
This is the same as in the case of equation (3).

[0045]

Embedded image ... (7) wherein R ₁₃ and R ₁₄ are a substituted or unsubstituted aryl group;
Ar ₁₀ , Ar ₁₁ and Ar ₁₂ are the same or different arylene groups,
X ₁ and X ₂ represent a substituted or unsubstituted ethylene group or a substituted or unsubstituted vinylene group. X, k, j and n are the same as in the case of equation (3).

[0046]

Embedded image (8) In the formula, R ₁₅ , R ₁₆ , R ₁₇ , and R ₁₈ are substituted or unsubstituted aryl groups, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ , and Ar ₁₆ are the same or different arylene groups, Y ₁ and Y ₂ , Y ₃ represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, and a vinylene group; Is also good. X, k, j and n are
This is the same as in the case of equation (3).

[0047]

Embedded image ... (9) In the formula, R ₁₉ and R ₂₀ represent a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ and Ar ₁₉ represent the same or different arylene groups. X, k, j and n are the same as in the case of equation (3).

[0048]

Embedded image ... (10) In the formula, R ₂₁ represents a substituted or unsubstituted aryl group, and Ar ₂₀ , Ar ₂₁ , Ar ₂₂ and Ar ₂₃ represent the same or different arylene groups. X, k, j and n are the same as in the case of equation (3).

[0049]

Embedded image (11) In the formula, R ₂₂ , R ₂₃ , R ₂₄ , and R ₂₅ are a substituted or unsubstituted aryl group, Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ , Ar ₂₈
Represents the same or different arylene groups. X, k, j and n are the same as in the case of equation (3).

[0050]

Embedded image ... (12) In the formula, R ₂₆ and R ₂₇ are a substituted or unsubstituted aryl group;
Ar ₂₉ , Ar ₃₀ and Ar ₃₁ represent the same or different arylene groups. X, k, j and n are the same as in the case of equation (3).

In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer (37). As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount of the plasticizer is suitably about 0 to 30% by weight based on the binder resin. Examples of the leveling agent include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain. 1% by weight is suitable.

The electrophotographic photosensitive member of the present invention may have an undercoat layer between the conductive support (31) and the photosensitive layer. The undercoat layer generally contains a resin as a main component. However, considering that the photosensitive layer is coated thereon with a solvent, these resins are resins having high solvent resistance to general organic solvents. desirable. Examples of such resins include polyvinyl alcohol, casein, water-soluble resins such as sodium polyacrylate, copolymerized nylon, alcohol-soluble resins such as methoxymethylated nylon, polyurethane, melamine resin, phenolic resin, alkyd-melamine resin,
A curable resin that forms a three-dimensional network structure, such as an epoxy resin, may be used. In addition, in the undercoat layer, titanium oxide, silica, alumina,
A fine powder pigment of a metal oxide such as zirconium oxide, tin oxide, or indium oxide may be added.

These undercoat layers can be formed by using a suitable solvent and a coating method as in the above-mentioned photosensitive layer. Further, a silane coupling agent, a titanium coupling agent, a chromium coupling agent or the like can be used as the undercoat layer in the present invention. In addition, the undercoat layer according to the present invention may be provided with Al ₂ O ₃ provided by anodic oxidation,
Organic substances such as polyparaxylylene (parylene) and Si
Those provided with an inorganic substance such as O ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ by a vacuum thin film forming method can also be used favorably. In addition, known materials can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.

In the electrophotographic photosensitive member of the present invention, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. The material used for the protective layer is ABS resin, AC
S resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenolic resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene, Polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer,
Polyurethane, polyvinyl chloride, polyvinylidene chloride,
Examples of the resin include an epoxy resin. Other protective layers include fluororesins such as polytetrafluoroethylene, silicone resins, and those obtained by dispersing inorganic materials such as titanium oxide, tin oxide, and potassium titanate in these resins for the purpose of improving abrasion resistance. Can be added. As a method for forming the protective layer, a normal coating method is employed. The thickness of the protective layer is suitably about 0.1 to 10 μm. Also,
In addition to the above, a-C and a-
A known material such as SiC can be used as the protective layer.

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

Next, the electrophotographic method and the electrophotographic apparatus of the present invention will be described in detail with reference to the drawings. FIG. 2 is a schematic view for explaining the electrophotographic process and the electrophotographic apparatus of the present invention, and the following modified examples also belong to the category of the present invention.

In FIG. 2, the photosensitive member (1) has a charge generation layer containing an organic pigment having an average particle size of 0.5 μm or more on a conductive support and a water vapor transmission rate of 100 g · m ⁻² · day.
^-1 . The photoconductor (1) has a drum shape, but may have a sheet shape or an endless belt shape. Charging charger (3),
The pre-transfer charger (7), the transfer charger (10), the separation charger (11), the separation claw (12), and the pre-cleaning charger (13) include a corotron, a scorotron, a solid-state charger (solid state charger),
A known means such as a charging roller is used.

As the transfer means, the above-mentioned charger can be generally used. However, as shown in the figure, a combination of a transfer charger and a separation charger is effective.

Light sources such as an image exposure section (5) and a neutralizing lamp (2) include a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electro-optical device. A general light-emitting material such as luminescence (EL) can be used. To irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used.

Such a light source or the like is provided with a process such as a transfer process using light irradiation in addition to the process shown in FIG. 5, a charge removal process, a cleaning process, or a pre-exposure process. Is done.

The toner developed on the photoreceptor (1) by the developing unit (6) is transferred to the transfer paper (9), but not all of the toner is transferred.
Some toner remains on the top. Such toner is removed from the photoreceptor by the fur brush (14) and the blade (15). Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.

When a positive (negative) charge is applied to the electrophotographic photosensitive member and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. If this is developed with toner of negative (positive) polarity (electrostatic detection fine particles), a positive image can be obtained, and positive (negative)
Developing with a polar toner gives a negative image. A known method can be applied to such a developing unit.
In addition, a known method is used for the charge removing means.

FIG. 3 shows another example of the electrophotographic process according to the present invention. The photoreceptor (21) is composed of a charge generation layer containing an organic pigment having an average particle size of 0.5 μm or more on a conductive support and a charge transport layer having a water vapor transmission rate of 100 g · m ⁻² · day ⁻¹ , Drive rollers (22a), (2
2b), charging by a charger (23), image exposure by a light source (24), development (not shown), transfer using a charger (25), exposure before cleaning by a light source (26), brush (27) ) And static elimination by the light source (28) are repeatedly performed. In FIG. 3, the photosensitive member (21) (in this case, the support is transparent) is irradiated with light for pre-cleaning exposure from the support side.

The above illustrated electrophotographic process is an example of the embodiment of the present invention, and other embodiments are of course possible. For example, in FIG. 3, the pre-cleaning exposure is performed from the support side, but this may be performed from the photosensitive layer side, or the image exposure and the irradiation of the static elimination light may be performed from the support side.

On the other hand, in the light irradiation step, image exposure, pre-cleaning exposure, and charge removal exposure are shown, but in addition, pre-transfer exposure, image exposure pre-exposure, and other known light irradiation steps are provided. Light irradiation can also be performed on the body.

The image forming means of the present invention as described above may be fixedly incorporated in a copying machine, a facsimile, or a printer, or may be incorporated in such a device in the form of a process cartridge. The process cartridge is one device (part) that includes a photoconductor and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge removing unit. There are many shapes and the like of the process cartridge, but as a general example,
FIG. 4 shows an example. The photoreceptor (16) has a charge generation layer containing an organic pigment having an average particle size of 0.5 μm or more on a conductive support and a water vapor transmission rate of 100 g · m ⁻² · d.
ay- ¹ .

[0067]

The present invention will be described below with reference to examples.
The present invention is not limited by the embodiments. All parts are parts by weight. First, a specific synthesis example of a titanyl phthalocyanine pigment used in Examples will be described.

(Synthesis Example) 52.5 parts of phthalodinitrile and 400 parts of 1-chloronaphthalene are stirred and mixed, and 19 parts of titanium tetrachloride are added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 200 ° C, and the reaction temperature was increased to 190 ° C to 210 ° C.
The reaction was carried out by stirring for 5 hours while keeping the temperature in between. After the completion of the reaction, the mixture was allowed to cool to 130 ° C., filtered while hot, washed with 1-chloronaphthalene until the powder turned blue, washed several times with methanol, and further washed with hot water at 80 ° C. After washing twice, it was dried to obtain 42.2 parts of a crude titanyl phthalocyanine pigment. Six parts of the obtained crude titanyl phthalocyanine pigment subjected to the washing with hot water was treated with 96% sulfuric acid 1
The mixture was stirred and dissolved in 00 g at 3 to 5 ° C, and filtered. The obtained sulfuric acid solution was added dropwise to 3.5 liters of ice water with stirring, and the precipitated crystals were filtered, and then repeatedly washed with water until the washing liquid became neutral to obtain a wet cake of titanyl phthalocyanine pigment. 150 parts of 1,2-dichloroethane was added to the wet cake, and the mixture was stirred at room temperature for 2 hours. Then, 250 parts of methanol was further added, followed by stirring and filtration.
This was washed with methanol and dried to obtain 4.9 parts of a titanyl phthalocyanine pigment.

An X-ray diffraction spectrum of the obtained titanyl phthalocyanine pigment was measured under the following conditions. X-ray tube: Cu Voltage: 40 kV Current: 20 mA Scanning speed: 1 ° / min Scanning range: 3 ° to 40 ° Time constant: 2 seconds

FIG. 5 shows an X-ray diffraction spectrum of the titanyl phthalocyanine pigment obtained according to the synthesis example. It can be seen that the obtained titanyl phthalocyanine pigment has a crystal form having a main peak at a Bragg angle of 2θ of 27.2 ° ± 0.2 °.

Example 1 An undercoat layer coating solution having the following composition on an electroformed nickel belt, average particle size 0.55 μm
The coating liquid for the charge generation layer containing the pigment particles and the coating liquid for the charge transport layer are sequentially coated and dried to form a 3 μm undercoat layer, a 0.3 μm charge generation layer, and a 22 μm charge transport layer (water vapor). A transmittance of about 35 g · m ⁻² · day ⁻¹ ) was formed to produce a laminated photoreceptor of the electrophotographic photoreceptor of the present invention. [Undercoat layer coating liquid] Titanium dioxide powder 15 parts Polyvinyl butyral 6 parts 2-butanone 150 parts [Charge generation layer coating liquid] The above-mentioned titanyl phthalocyanine powder 3 parts Polyvinyl butyral 2 parts 2-butanone 170 parts [Charge transport layer] Coating liquid] 10 parts of polycarbonate of the following structural formula

[0072]

Embedded image 7 parts of charge transport material of the following structural formula

[0073]

Embedded image

Methylene chloride 80 parts

Incidentally, the water vapor permeability of the charge transport layer was measured using a fully automatic water vapor permeability tester (DR. GEORGES HL).
YSSY: L80-4000H). The particle size of the coating solution for the charge generation layer was determined by scooping the coating solution on a 150-mesh copper net having a collodion film and a conductive carbon layer, drying the coating solution, and then using a transmission electron microscope (TEM, TEM). Hitachi: H-500H).

Example 2 A photoconductor was prepared in the same manner as in Example 1, except that the coating solution for the charge transport layer in Example 1 was changed to the following. (Water vapor permeability of the charge transport layer:
Approximately 32 g · m ⁻² · day ⁻¹ ) [Coating solution for charge generation layer] 10 parts of polycarbonate having the following structural formula

[0077]

Embedded image 8 parts of charge transport material of the following structural formula

[0078]

Embedded image

80 parts of methylene chloride

(Comparative Example 1) The coating liquid for a charge generation layer in Example 1 was changed to a dispersion liquid containing pigment particles having an average particle size of 0.3 μm without changing the composition ratio by changing the dispersion conditions. An electrophotographic photoreceptor was produced in the same manner as in Example 1 except for the above.

(Comparative Example 2) Charge generation layer in Example 1
Example 1 except that the coating solution for
Similarly, a photoreceptor was prepared. (Water vapor permeability: about 110
g ・ m^-2・ Day ^-1[Charge transport layer coating solution] A type polycarbonate 10 parts Charge transport material of the following structural formula 7 parts

[0082]

Embedded image

[0083] 80 parts of methylene chloride

The electrophotographic photosensitive members prepared as described above were evaluated for their electrophotographic characteristics as follows using an apparatus disclosed in Japanese Patent Application Laid-Open No. 60-100167.

First, at a discharge voltage of -6.0 kV, corona charging is performed for 20 seconds, and then dark attenuated for 20 seconds.
2.5 μW / cm ² light (780 ± 10 n) after dark decay
m) was irradiated. At this time, the potential V20 after 20 seconds of charging
(V) and the exposure amount E1 / 5 [μJ / cm ² ] necessary for optically attenuating the surface potential after dark decay to 1/5 were measured.

After measuring the electrostatic characteristics of the photoreceptor in the initial state, the photoreceptor was subjected to an ozone concentration of 5 ppm, a temperature and humidity of 25 ° C. /
It was left in an environment of 55% RH for 2 days, and the electrostatic characteristics were evaluated again by the above-mentioned device. Further, charging and exposure were performed for one hour in the above-described cycle, the photoreceptor was fatigued, and the electrostatic characteristics at that time were evaluated. Table 1 shows the above results.

[0087]

[Table 1] Table 1 shows that the electrophotographic photoreceptors of Examples 1 and 2 are excellent in gas resistance and maintain stable electrostatic characteristics even after repeated use.

(Examples 3 and 4 and Comparative Examples 3 and 4) The electrophotographic photosensitive members produced in Examples 1 and 2 and Comparative Examples 1 and 2 were subjected to an electrophotographic process shown in FIG. No) and the image exposure light source is 780 nm
As a reaction body laser (image writing by a polygon mirror), a probe of a surface voltmeter was inserted so that the surface potential of the photoconductor immediately before development could be measured. As the initial characteristics, the surface potential of the image-exposed area and the image non-exposed area was measured, and then the photosensitive member was subjected to an ozone concentration of 5 ppm, a temperature and humidity of 25 ° C./55.
% RH for 2 days, return to the above device again, print 10,000 sheets continuously, and measure the surface potential of the image exposed part and image non-exposed part at the beginning and after 10,000 sheets did. Table 2 shows the results.

[0089]

[Table 2] Table 2 shows that the electrophotographic photoreceptors of Examples 3 and 4 have excellent gas resistance and maintain a stable surface potential even after repeated use.

(Example 5) After the surface of an aluminum cylinder was subjected to anodizing treatment, sealing treatment was performed. On top of this,
A charge generation layer coating solution containing pigment particles having an average particle size of 0.6 μm having the following composition, and a charge transport layer coating solution were sequentially applied and dried to form a 0.3 μm charge generation layer, 28 μm each.
μm charge transport layer (water vapor permeability: about 95 gm ^-2
ay ^-1 ), and a laminated photoreceptor was prepared in which the electrophotographic photoreceptor of the present invention was prepared. [Coating solution for charge generation layer] 5 parts of the titanyl phthalocyanine powder described above 5 parts of polyvinyl butyral 2 parts 170 parts of 2-butanone [Coating solution for charge transport layer] 9.3 parts of polymer charge transport material having the following structural formula

[0091]

Embedded image

0.7 part of a plasticizer having the following structure

[0093]

Embedded image

80 parts of methylene chloride

Example 6 Same as Example 3 except that the parts by weight of the polymer charge transporting substance and the plasticizer in the coating liquid for the charge transporting layer in Example 5 were changed to 9 parts and 1 part, respectively. A photoreceptor was prepared.

(Comparative Example 5) The coating liquid for a charge generation layer in Example 5 was changed to a dispersion liquid containing pigment particles having an average particle size of 0.35 μm without changing the composition ratio by changing the dispersion conditions. An electrophotographic photoreceptor was produced in the same manner as in Example 5 with the changes.

Comparative Example 6 Example 5 was repeated except that the coating solution for the charge transport layer in Example 5 was changed to one having the following composition.
It was produced in exactly the same way. (Water vapor permeability: about 200g
m ^-2 · day ^-1 )

[Charge Transport Layer Coating Solution] 9 parts of a polymer charge transport material having the following structural formula

[0099]

Embedded image

80 parts of methylene chloride

The electrophotographic photoreceptor thus constructed is the fourth
After being mounted on the electrophotographic process cartridge shown in the figure, it was mounted on an image forming apparatus. However, the image exposure light source was a 780 nm reaction laser (image writing with a polygon mirror). After evaluating the initial image, the photoreceptor was once taken out of the apparatus, stored in an environment of NOx (NO + NO ₂ ) concentration of 20 ppm, temperature and humidity of 23 ° C. and 50% RH for 2 days, and mounted again in the image forming apparatus. 8000 sheets were continuously printed, and the initial and 8000th images were evaluated. Table 3 shows the results.

[0102]

[Table 3] Table 3 shows that the photoreceptors of Examples 4 to 6 can obtain good images both at the initial stage and after repeated use.

Example 7 An undercoat layer coating solution having the following composition was coated on an aluminum cylinder with an average particle size of 0.6.
The charge generation layer coating liquid containing the pigment particles of μm and the charge transport layer coating liquid were sequentially coated and dried to obtain 3.5 μm each.
m undercoat layer, 0.3 μm charge generation layer, and 25 μm charge transport layer water vapor permeability: about 30 g · m ⁻² · day ⁻¹ ) to form the electrophotographic photoreceptor of the present invention. The body was made. [Undercoat layer coating liquid] Titanium dioxide powder 60 parts Alkyd resin 18 parts Melamine resin 10 parts 2-butanone 210 parts [Charge generation layer coating liquid] Titanyl phthalocyanine powder 4 parts Polyvinyl acetal 2 parts 2-butanone 120 parts [Coating solution for charge transport layer] 10 parts of polycarbonate having the following structural formula

[0104]

Embedded image 7 parts of charge transport material of the following structural formula

[0105]

Embedded image

80 parts of methylene chloride

Example 8 An electrophotographic photoreceptor was produced in exactly the same manner as in Example 7, except that the content of the polycarbonate and the charge transport material in the coating solution for the charge transport layer in Example 7 were changed to 10 parts and 8 parts, respectively. Was prepared.

(Comparative Example 7) The coating liquid for a charge generation layer in Example 7 was changed to a dispersion containing pigment particles having an average particle size of 0.25 μm without changing the composition ratio by changing the dispersion conditions. An electrophotographic photoreceptor was manufactured in the same manner as in Example 7, except that the above conditions were changed.

The electrophotographic photosensitive member produced as described above was mounted on the electrophotographic process shown in FIG. 4 (however, an image exposure light source was an LD having a light emission at 780 nm), and 20,000 sheets were continuously printed. Was performed, and image evaluation of 20,000 sheets at that time was performed. Table 4 shows the above results.

[0110]

[Table 4] Table 4 shows that the electrophotographic photoreceptors of Examples 7 and 8 have excellent characteristics.

[0111]

As is apparent from the above detailed and specific description, in the present invention, the water vapor permeability of the charge transport layer is 100 g · m ⁻² · day ⁻¹ or less, and the charge generation layer has The average particle size of the contained organic pigment is 0.5 μ
With a configuration of m or more, a stable electrophotographic photoreceptor can be provided in which gas resistance can be improved without losing high sensitivity and chargeability does not decrease even when used repeatedly. Further, a stable electrophotographic method is provided in which the chargeability does not decrease even when repeatedly used without losing high sensitivity. Further, the present invention has an extremely excellent effect of providing a stable electrophotographic apparatus and a process cartridge for the electrophotographic apparatus which do not cause a reduction in chargeability even when repeatedly used without losing high sensitivity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a schematic view for explaining an electrophotographic process and an electrophotographic apparatus of the present invention.

FIG. 3 is a schematic diagram illustrating another example of the electrophotographic process of the present invention.

FIG. 4 is a view showing a process cartridge of the present invention.

FIG. 5 is a view showing an X-ray diffraction spectrum of a titanyl phthalocyanine pigment used in the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 2 static elimination lamp 3 charging charger 4 eraser 5 image exposure unit 6 developing unit 7 pre-transfer charger 8 registration roller 9 transfer paper 10 transfer charger 11 separation charger 12 separation claw 13 pre-cleaning charger 14 fur brush 15 cleaning brush 16 photoconductor 17 Charging Charger 18 Cleaning Brush 19 Image Exposure Unit 20 Developing Roller 21 Photoconductor 22a Driving Roller 22b Driving Roller 23 Charging Charger 24 Image Exposure Source 25 Transfer Charger 26 Pre-Cleaning Exposure 27 Cleaning Brush 28 Static Elimination Light Source 31 Conductive Support 35 Charge Generation Layer 37 charge transport material

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) G03G 5/05 101 G03G 5/05 101 F term (Reference) 2H068 AA13 AA19 AA21 AA28 AA29 BA39 BB26 BB49 FA27 4J002 CG011 CG021 EU026 FD096 GP03

Claims (15)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer formed by laminating a charge generation layer containing at least an organic pigment and a charge transport layer on a conductive support, wherein the charge transport layer has a water vapor permeability of 100 g. An electrophotographic photoreceptor characterized by having an average particle size of at most 0.5 μm and an m− ² · day ⁻¹ or less and an organic pigment contained in the charge generation layer. 2. The electrophotographic photosensitive member according to claim 1, wherein the organic pigment is titanyl phthalocyanine. 3. The organic pigment is titanyl phthalocyanine having a maximum diffraction peak at a Bragg angle 2θ of at least 27.2 ± 0.2 ° with respect to characteristic X-rays (wavelength 1.514 °) of CuKα. The electrophotographic photosensitive member according to claim 1. 4. The electrophotographic photoreceptor according to claim 1, wherein the binder resin used in the charge transport layer contains at least polycarbonate. 5. The electrophotographic photosensitive member according to claim 4, wherein the polycarbonate is a polycarbonate containing at least a structure represented by the following formula (1) and / or the following formula (2) in a repeating unit. body. Embedded image ... (1) … (2) 6. The electrophotographic photosensitive member according to claim 1, wherein the charge transport layer contains a polycarbonate containing at least a triarylamine structure in a main chain and / or a side chain. body. 7. An electrophotographic method in which an electrophotographic photosensitive member is repeatedly subjected to at least charge, image exposure, development, transfer, cleaning, and charge elimination, wherein the electrophotographic photosensitive member has an average particle size of at least 0 on a conductive support. An electrophotographic photosensitive member comprising: a charge generation layer containing an organic pigment having a particle size of 0.5 μm or more and a charge transport layer having a water vapor transmission rate of 100 g · m ⁻² · day ⁻¹ or less. Photo method. 8. The electrophotographic method according to claim 7, wherein the organic pigment is titanyl phthalocyanine. 9. The organic pigment is a titanyl phthalocyanine having a maximum diffraction peak at a Bragg angle 2θ of at least 27.2 ± 0.2 ° with respect to characteristic X-rays (wavelength 1.514 °) of CuKα. The electrophotographic method according to claim 7. 10. At least charging means, image exposure means,
An electrophotographic apparatus comprising a developing unit, a transfer unit, a cleaning unit, a charge removing unit, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member has an average particle size of at least 0.5 μm on at least a conductive support. A charge generation layer containing an organic pigment and a water vapor transmission rate of 100 g · m ⁻² · day
^An electrophotographic apparatus comprising an electrophotographic photoreceptor obtained by laminating a charge transport layer of ^-1 or less. 11. The electrophotographic apparatus according to claim 10, wherein the organic pigment is titanyl phthalocyanine. 12. The method according to claim 1, wherein the organic pigment has a Bragg angle of 2θ with respect to at least CuKα characteristic X-rays (wavelength 1.514 °).
11. The titanyl phthalocyanine whose maximum diffraction peak is at 27.2 ± 0.2 °.
2. The electrophotographic apparatus according to claim 1. 13. A process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member has an average particle size of at least 0.5 μm on at least a conductive support. And a charge transport layer having a water vapor permeability of 100 g · m ⁻² · day ⁻¹ or less. 14. The process cartridge according to claim 13, wherein the organic pigment is titanyl phthalocyanine. 15. The organic pigment according to claim 1, wherein said organic pigment has a Bragg angle 2θ with respect to at least CuKα characteristic X-rays (wavelength 1.514 °).
14. The titanyl phthalocyanine having a maximum diffraction peak at 27.2 ± 0.2 °.
4. The process cartridge for an electrophotographic apparatus according to 1.