JP2000147808A - Photoconductor, organic pigment-dispersed liquid and manufacture of photoconductor by using same, electrophotographic method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor high in sensitivity and superior in potential stability and dispersibility of a coating liquid in manufacture and prevented from occurrence of abnormal images in repeated uses by incorporating titanylphthalocyanine and a specified bisazo pigment in a photoconductive layer. SOLUTION: The photoconductive layer contains the titanylphthalocyanine and the bisazo pigment represented by the formula in which each of R1 and R2 is a halogen atom or an optionally substituted alkyl, such alkoxy, such amino, nitro, or cyano group; each of (p) and (q) is an integer of 0-3; and each of Cp1 and Cp2 is a coupler residue. The titanylphthalocyanine to be used is, preferably, the one having crystal forms having main peaks in Bragg angles 2θ of 9.6 deg.±0.2 deg., 24.0 deg.±0.2 deg., and 27.2 deg.±0.2 deg. in the X ray diffraction spectrum using CuKα characteristic X-ray (1.54Å).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and an electrophotographic method and an electrophotographic apparatus using the same. The present invention relates to an electrophotographic photoreceptor excellent in stability of residual potential and excellent in production, and an electrophotographic method and an electrophotographic apparatus using the same.

[0002]

2. Description of the Related Art Conventional electrophotographic photoconductors, particularly electrophotographic organic photoconductors using an organic photoconductor, have lower cost and toxicity than inorganic photoconductors in which a selenium film is formed by a vacuum deposition method. There are many merits such as little or no easiness of film formation, and it is becoming the mainstream of current electrophotographic photoreceptors.

An organic photoreceptor is a so-called single-layer photoreceptor in which a coating solution for a photosensitive layer containing a charge generating substance, a charge transport substance, a binder resin and the like is formed on a conductive support by dip coating or the like.
There is a laminated photoreceptor in which a charge generation layer is formed on a conductive support using a coating liquid containing a charge generation substance, and then a charge transport layer is formed using a coating liquid containing a charge transport substance. In the laminated photoreceptor,
An undercoat layer, a protective layer, or the like may be applied for the purpose of improving image quality or durability.

[0004] In recent years, the development of information processing system machines using the electrophotographic system 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.

The photosensitive wavelength region of a function-separated type electrophotographic photosensitive member varies depending on the charge generating substance. Examples of charge generation materials having high sensitivity around 800 nm include metal-free phthalocyanine, copper phthalocyanine, aluminum chlorophthalocyanine,
Phthalocyanine compounds such as chloroindium phthalocyanine, magnesium phthalocyanine, zinc phthalocyanine, titanyl phthalocyanine, and vanadyl phthalocyanine are known. Particularly, phthalocyanine compounds having high sensitivity to long wavelengths include τ-type and η-type non-metallic phthalocyanines described in JP-A-58-182639, and 61-type.
Nos. 109056, 62-134651, 64-17066, JP-A-1-172449, JP-A-2-289658, and 3-128973
There are titanyl phthalocyanine described in Japanese Patent Application Laid-Open Publication No. Hei. 2-26863 and vanadyl phthalocyanine described in Japanese Patent Application Laid-Open Publication No. 3-269633.

Further, as the performance of laser printers, copiers, and the like has become higher, electrophotographic photoconductors have been required to have higher and higher sensitivity, and various improvements have been attempted based on the phthalocyanine compounds. For example, a photoreceptor in which a phthalocyanine compound, a perylene compound and a hole transport material are dispersed in a binder resin disclosed in JP-A-62-54266, a phthalocyanine compound disclosed in JP-A-63-313165 and a specific disazo compound are disclosed. A photoreceptor in which a mixture of compounds is used as a charge generation layer; a photoreceptor in which a specific perylene compound and titanyl phthalocyanine are used as a charge generation material and a specific diamine derivative is used as a charge transporting material disclosed in JP-A-3-1150; A photoreceptor provided with a layer in which a titanyl phthalocyanine and a polycyclic quinone compound are separately or mixed as shown in JP-A-376661, a mixture of titanyl phthalocyanine and a specific phthalocyanine compound shown in JP-A-3-157666 as a charge generating substance, Photoreceptor using a specific hydrazone compound as a charge transporting substance, 3-1. Specific disazo compound and titanyl phthalocyanine shown in 6049 discloses a charge generating material, a photosensitive body or the like has been disclosed that certain stilbene compounds and the charge transport material.

On the other hand, the conditions of the electrophotographic photosensitive member repeatedly used in the Carlson process and similar processes include sensitivity, receiving 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 photoconductors, it has been empirically known that many photoconductors have a decrease in chargeability and an increase in residual potential due to repeated use, which govern the life characteristics of the photoconductor. This is no exception. Therefore, the stability of a photoreceptor using titanyl phthalocyanine by repeated use is not yet sufficient, and there has been an eager desire to complete the technology. Although the cause is not clear due to long-term use, there is a problem in that an abnormal image such as white spots or background stain is generated on the image. For this reason, the material of the intermediate layer between the support and the photosensitive layer is restricted, or two laminated intermediate layers are required. Further, when the dispersibility of the coating liquid during the production is low, not only the productivity is lowered, but also the electrostatic characteristics of the electrophotographic photoreceptor become unstable, and there is a problem that the quality in an image is also lowered. .

[0010] Titanyl phthalocyanine has many types of crystal forms, and each crystal form often changes to another crystal form by contact with an organic solvent. For this reason, in the preparation of a dispersion containing titanyl phthalocyanine, selection of the preparation method, dispersion conditions, and the like greatly affects not only the dispersibility but also the electrostatic characteristics of the produced electrophotographic photosensitive member. This is because the generation of electric charges due to the dissociation of excitons depends on the surface area, particle size, and the like of the particles.
On the other hand, particles are crushed and refined due to the progress of crushing and dispersion,
Conversely, when the particles are overdispersed, the particles are aggregated and the dispersibility is reduced. Therefore, it is difficult to obtain a good dispersion state and the required electrostatic properties only by increasing the dispersion time. It is. Therefore, in order to obtain the required electrostatic characteristics, it is necessary to optimize the dispersion method and its conditions.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive material having high sensitivity, excellent potential stability upon repeated use, no abnormal images, and excellent dispersibility of a coating solution during production. Is to provide the body. Another object of the present invention is to provide a stable electrophotographic method which has high sensitivity, has excellent potential stability upon repeated use, and has no abnormal images. Still another object of the present invention is to provide a stable electrophotographic apparatus having high sensitivity, excellent potential stability upon repeated use, and free from abnormal images.

[0012]

Documents using a mixture of a phthalocyanine and a bisazo pigment for an electrophotographic photoreceptor include, for example, JP-A-3-37666 and JP-A-3-3.
No. 7,666, JP-A-7-152163, and the like. However, the relationship between the abnormal image and the dispersibility of the coating liquid has not been clarified. The present inventors have conducted intensive studies to solve the above problems, and have completed the present invention.

According to the present invention, first, there is provided a photoconductor having a layer containing at least titanyl phthalocyanine and at least one of bisazo pigments represented by the following general formula (1): Provided.

Embedded image (Wherein R ₁ and R ₂ are a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group,
It represents a nitro group, a cyano group, a hydroxyl group, a substituted or unsubstituted amino group, and p and q each represent an integer of 0 to 3. Cp ₁ and Cp ₂ represent a coupler residue. )

Second, an electrophotographic photosensitive member having a photosensitive layer containing at least titanyl phthalocyanine and one or more bisazo pigments represented by the general formula (1) on a conductive support. A body is provided.

Third, a charge generation layer containing at least titanyl phthalocyanine and one or more bisazo pigments represented by the general formula (1) on a conductive support, The present invention provides an electrophotographic photoreceptor characterized by laminating a charge transport layer.

Fourthly, there is provided an organic pigment dispersion liquid characterized by dispersing at least titanyl phthalocyanine and one or more bisazo pigments represented by the general formula (1) in an organic solvent.

Fifth, there is provided a method for producing the first photoconductor produced through a step of applying and drying the fourth dispersion.

Sixthly, there is provided a method for producing the above-mentioned second or third electrophotographic photosensitive member, which is produced through a step of applying and drying the above-mentioned fourth dispersion liquid.

Seventh, in an electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and charge elimination are repeatedly performed on the electrophotographic photosensitive member, the electrophotographic photosensitive member is the second or third photosensitive member. An electrophotographic method is provided.

Eighth, 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, wherein the electrophotographic photosensitive member is An electrophotographic device is provided, which is a second or third photoconductor.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The basic structure of the titanyl phthalocyanine pigment (TiOPc) used in the present invention is represented by the following general formula (2).

Embedded image (In the formula, X ₁ , X ₂ , X ₃ , and X ₄ each independently represent various halogen atoms, and n, m, l, and k each independently represent a number from 0 to _4. )

Various crystal forms of TiOPc are known, and are disclosed in JP-A-59-49544 and JP-A-59-16.
6959, JP-A-61-239248, JP-A-62-67094, JP-A-63-366, JP-A-63-116158, JP-A-63-1
JP-A-96067 and JP-A-64-17066 disclose TiOPc having different crystal forms.

As the titanyl phthalocyanine used in the present invention, all known crystal forms (including amorphous forms) can be used, and in particular, Cu-Kα characteristic X-rays (wavelength 1.
In the X-ray diffraction spectrum using (54 °), (i)
Main peak of Bragg angle 2θ is at least 9.6 ° ±
0.2 °, 24.0 ° ± 0.2 ° and 27.2 ° ±
Having a crystal form at 0.2 °, (ii) a main peak at a Bragg angle 2θ of at least 7.5 ° ± 0.2 °, 2
12. having crystal forms at 5.3 ° ± 0.2 ° and 28.6 ° ± 0.2 °, (iii) at least 9.3 ° ± 0.2 ° with a major peak at Bragg angle 2θ, 13. 1 ° ±
Those having crystal forms at 0.2 ° and 26.2 ° ± 0.2 ° are preferably used.

Methods for obtaining a desired crystal form (including an amorphous form) include a method according to a known method in a synthesis process, a method in which crystals are changed in a washing and purification process, and a method in which a special crystal conversion step is provided. Any method is acceptable.

The bisazo pigment of the general formula (1) used in the present invention is

Embedded image (Wherein R ₁ and R ₂ are a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group,
It represents a nitro group, a cyano group, a hydroxyl group, a substituted or unsubstituted amino group, and p and q each represent an integer of 0 to 3. Cp ₁ and Cp ₂ represent a coupler residue. ) Where Cp ₁ and Cp ₂ are represented by the following formulas (k1) to (k1).
And a coupler residue represented by (k10).

[0026]

Embedded image (R ₁ and R ₂ represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and R ₁ and R ₂ represent a nitrogen atom bonded thereto. R ₃ represents a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a nitro group, a cyano group, a hydroxyl group, a substituted or unsubstituted amino group, n represents an integer of 0 to 5.)

[0027]

Embedded image (R ₁ and R ₂ are a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted styryl group,
Represents a substituted or unsubstituted heterocyclic group, and R ₁ and R ₂ may form a ring together with the carbon atom bonded thereto. R
₃ is a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a nitro group, a cyano group,
Represents a hydroxyl group, a substituted or unsubstituted amino group,
n represents the integer of 0-5. )

[0028]

Embedded image (R ₁ and R ₂ represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and R ₁ and R ₂ represent nitrogen bonded to them. R ₃ may be a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a nitro group, a cyano group, a hydroxyl group, or a substituted or unsubstituted amino group. And R ₃ may form a ring, and n represents an integer of 0 to 4.)

[0029]

Embedded image (R ₁ and R ₂ are a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted styryl group,
Represents a substituted or unsubstituted heterocyclic group, wherein R ₁ and R ₂ may form a ring together with a carbon atom bonded thereto.
R ₃ is a halogen atom, a substituted or unsubstituted alkyl group,
It represents a substituted or unsubstituted alkoxy group, nitro group, cyano group, hydroxyl group, substituted or unsubstituted amino group, and R ₃ may form a ring. n represents the integer of 0-4. )

[0030]

Embedded image (R ₁ and R ₂ represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and R ₁ and R ₂ represent nitrogen bonded to them. R ₃ may be a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a nitro group, a cyano group, a hydroxyl group, or a substituted or unsubstituted amino group. , N is 0-6
Represents an integer. )

[0031]

Embedded image (R ₁ and R ₂ represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and R ₁ and R ₂ represent nitrogen bonded to them. X may form a ring together with the atom, and X represents a heterocyclic ring or a substituent thereof.)

[0032]

Embedded image (R ₁ represents a substituted or unsubstituted alkyl group, a carbamoyl group, a carboxyl group, or an ester thereof;
1 represents a hydrocarbon ring group or a substituted product thereof. )

[0033]

Embedded image (R ₁ represents a substituted or unsubstituted hydrocarbon group.)

[0034]

Embedded image (Y represents an aromatic hydrocarbon divalent group or a heterocyclic divalent group containing a nitrogen atom in the ring.)

[0035]

Embedded image (R ₁ and R ₂ represent a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a nitro group, a cyano group, a hydroxyl group, or a substituted or unsubstituted amino group; Represents an integer of 0 to 5)

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating an organic photoconductive layer used in the present invention. A single-layer photosensitive layer 33 having a charge generation material and a charge transport material as main components is provided on a conductive support 31. . FIG. 2 and FIG. 3 are cross-sectional views showing another example of the configuration of the organic photoconductive layer used in the present invention. The charge generation layer 35 mainly composed of a charge generation material and the electric charge mainly composed of a charge transport material are shown. The transport layer 37 has a stacked configuration.
The organic photoconductive layer having such a configuration can be used as it is as an organic photoreceptor for electrophotography. In addition, a counter electrode (not shown) is provided on the conductive support 31 to form an optical sensor, a photovoltaic cell, or the like. Can also be used.

The conductive support 31 has a volume resistance of 10
Those exhibiting a conductivity of ¹⁰ Ωcm or less, for example, aluminum, nickel, chromium, nichrome, copper, gold, silver, metals such as platinum, tin oxide, metal oxides such as indium oxide, by evaporation or sputtering, Film or cylindrical plastic or paper coated, or plates made of aluminum, aluminum alloy, nickel, stainless steel, etc. and extruded, made into a tube by a method such as drawing, cutting, super finishing, polishing etc. Surface-treated tubes and the like 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 to the above, a support obtained by dispersing a conductive powder on 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. As the conductive powder, carbon black, acetylene black, aluminum, nickel, iron, nichrome, copper, zinc,
Metal powder such as silver, or metal oxide powder such as conductive tin oxide and ITO can be used. Here, binder resins used simultaneously include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, and vinyl chloride-vinyl acetate copolymer. Coalescence, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene,
Thermoplastic resins such as poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin, thermosetting resins, and photo-curing 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 dispersion.

Further, a conductive material is formed by a heat-shrinkable tube in which a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, or Teflon contains the conductive powder on a suitable cylindrical substrate. Those provided with a layer can also be favorably used as the conductive support 31 of the present invention.

Next, the photosensitive layer will be described. The photosensitive layer may be a single layer or a stacked layer, but for convenience of explanation, the case where the photosensitive layer is composed of the charge generation layer 35 and the charge transport layer 37 will be described first.

The charge generation layer 35 is a layer mainly composed of the above-mentioned TiOPc as a charge generation material and the azo pigment of the general formula (1). The charge generation layer 35 is formed by dispersing the charge generation material together with a binder resin in a suitable solvent as required, applying the dispersion on a conductive support, and drying.

As the crystal form of TiOPc used in the present invention, all known crystal forms (including amorphous forms) can be used and are useful, but are not necessarily limited thereto. In addition, the azo pigment of the general formula (1) basically tends to show an amorphous shape, but is not necessarily limited thereto. The ratio of TiOPc to the azo pigment of the general formula (1) used in the present invention is such that the azo pigment of the general formula (1) is 0.01 to 100 parts by weight relative to 1 part by weight of the TiOPc, and is preferably. 0.1 to 90 parts by weight. These pigments can be mixed by dispersing TiOPc and the azo pigment of the general formula (1) simultaneously from the beginning in the following solvent, or by dispersing the TiOPc of the general formula (1) The azo pigment may be added and mixed, or the order may be reversed. Further, those obtained by separately dispersing TiOPc and the azo pigment of the general formula (1) may be mixed later.

As the non-aqueous solvent used as the dispersion medium, known ones can be widely used, and in particular, isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochloroethane Chlorobenzene, cyclohexane, toluene, xylene, ligroin and the like can be preferably used. These solvents are used alone or as a mixture. These solvents may be used as a mixture from the beginning, or T
After dispersing the iOPc and / or the azo pigment of the general formula (1), a diluting solvent may be mixed.

The binder resins that may be used as appropriate include polyamides, polyurethanes, polyesters,
Epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene,
Polyacrylamide and the like are used.

Ratio between binder resin and pigment (weight ratio)
Is preferably 0/3 to 3/1, more preferably 0/2.
２2/1. The binder resin may be added before the dispersion, or may be added after only the TiOPc and the general formula (1) and / or the azo pigment and the solvent are dispersed. Moreover, it is also possible to add during the dispersion.

As the material of the medium at the time of wet dispersion, zirconia, glass, alumina, non-oxide, metal and the like can be used. As a dispersion means for obtaining a dispersion by wet dispersion, known methods such as a ball mill, an attritor, a sand mill, a vibration mill, a disk vibration mill, a paint shaker, and a jet mill can be used. However, since the conditions for preparing the target dispersion differ depending on the respective dispersion conditions, they cannot be defined uniformly. It can be considered that the reason is that the ratio of the pulverizing power, the dispersing power, the grinding power and the like differs depending on the dispersing means or the use conditions, and that the dispersing conditions also differ depending on the type of the solvent used. The coating method of the coating solution includes dip coating, spray coating, beat coating,
Methods such as nozzle coating, spinner coating, and ring coating can be used.

In the charge generation layer 35, in addition to the above-described TiOPc and the azo pigment of the general formula (1), other charge generation materials can be used in combination. Representative examples thereof include an azo pigment and a perylene-based pigment. Pigments, perinone-based pigments, quinacridone-based pigments, quinone-based condensed polycyclic compounds, squaric acid-based dyes, other phthalocyanine-based pigments, naphthalocyanine-based pigments, and azurenium salt-based dyes 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 a charge transporting substance and a binder resin in a suitable solvent, applying the solution on the charge generating layer, and drying. Also,
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 substance 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-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5
-Electron accepting substances such as dioxides and benzoquinone derivatives.

Examples of the hole transport material include poly-N-vinylcarbazole and its derivatives, poly-γ-galvazolylethylglutamate 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 derivative, triarylmethane derivative, 9
-Known materials such as styryl anthracene derivative, pyrazoline derivative, divinylbenzene derivative, hydrazine derivative, indene derivative, butadiene derivative, pyrene derivative, bisstilbene derivative, enamine derivative and the like. 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 polyacetic acid. Vinyl, 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 resin And a thermoplastic or thermosetting resin such as phenolic resin and alkyd resin.

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.

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. As the leveling agent, silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain are used in an amount of 0 to 1 weight based on the binder resin. % Is appropriate.

Next, the case where the photosensitive layer has a single-layer structure 33 will be described. A photoconductor in which the above-described TiOPc and the azo pigment of the general formula (1) are dispersed in a binder resin can be used. The single-layer photosensitive layer can be formed by dispersing a charge generating substance, a charge transporting substance, and a binder resin in a suitable solvent by the above-described method, and applying and drying this. Further, the photosensitive layer may be of a function-separated type to which the above-mentioned charge transport material is added, and can be used favorably. If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.

As the binder resin, in addition to using the binder resin described above for the charge transport layer 37 as it is, the charge generation layer 3
The binder resins described in 5 may be mixed and used. Of course, the above-mentioned polymer charge transport materials can also be used favorably. The amount of the charge generating substance is preferably 5 to 40 parts by weight, and the amount of the charge transporting substance is 0 to 100 parts by weight of the binder resin.
190 parts by weight is preferable, and 50 to 150 parts are more preferable.
Parts by weight. The single-layer photosensitive layer is formed by dip coating or spraying a coating liquid obtained by dispersing a charge generating substance and a binder resin together with a charge transporting substance, if necessary, using a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexane using a dispersing machine or the like. It can be formed by coating with a coat or bead coat. The thickness of the single-layer photosensitive layer is suitably about 5 to 100 μm.

In the electrophotographic photoreceptor of the present invention, an undercoat layer can be provided 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 a resin include water-soluble resins such as polyvinyl alcohol, casein and sodium polyacrylate, alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy resin. Curable resins that form a three-dimensional network structure, such as resins, are exemplified. Further, a fine powder pigment of a metal oxide exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the undercoat layer in order to prevent moiré and reduce residual potential.

These undercoat layers can be formed using an appropriate solvent and a coating method as in the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, the undercoat layer of the present invention, A1 ₂
O ₃ provided by anodic oxidation, organic substances such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , Ti
Those provided with an inorganic substance such as O 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 0 to 5 μm
Is appropriate.

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, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene, polyethylene terephthalate,
Polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone,
Examples include resins such as polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, and epoxy resin. Other protective layers include fluororesins such as polytetrafluoroethylene, silicone resins, and inorganic materials such as titanium oxide, tin oxide, and potassium titanate dispersed in these resins for the purpose of improving abrasion resistance. Can be added. As a method for forming the protective layer, an ordinary coating method is employed. The thickness of the protective layer is suitably about 0.1 to 10 μm. In addition to the above, a-C,
A known material such as a-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. 4 is a schematic diagram 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.

Referring to FIG. 4, this electrophotographic apparatus includes a static elimination exposure section 2, a charging charger 3, an eraser 4, an image exposure section, which are close to the upper surface of a drum-shaped photosensitive member 1 and are arranged in a counterclockwise direction along the circumference. Part 5, developing unit 6, pre-transfer charger 7, transfer charger 10, separation charger 11, separation claw 12, pre-cleaning charger 13, fur brush 1
4. A cleaning blade 15 is sequentially provided. Further, a registration roller 8 for feeding the transfer paper 9 between the photoreceptor 1 and the transfer charger 10 and the separation charger 11 is additionally provided. The photoreceptor 1 comprises a drum-shaped conductive support and a photosensitive layer in close contact with the upper surface thereof, and rotates counterclockwise.

In the electrophotographic method using the above-described electrophotographic apparatus, the photoreceptor 1 rotates counterclockwise, is negatively (or positively) charged by the charging charger 3, and is exposed from the image exposing unit 5 by exposure. Then, an electrostatic latent image is formed on the photoconductor 1. As the transfer means, generally, the above-described charger can be used, but as shown in the figure, a combination of a transfer charger and a separation charger is effective.

The light sources such as the image exposure section 5 and the neutralizing lamp 2 include a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, and a light emitting diode (LE).
D), semiconductor lasers (LD), electroluminescence (EL), and other general light-emitting materials 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 irradiates the photoreceptor with light by providing a transfer step, a charge removal step, a cleaning step, or a pre-exposure step using light irradiation in addition to the step shown in FIG.

In the developing unit 6, the electrostatic latent image is developed by attaching toner onto the photoreceptor 1 and the charged state of the toner image is adjusted by the pre-transfer charger 7, and then transferred onto the transfer paper 9 by the transfer charger 10. The toner image is transferred, the electrostatic adhesion between the photoconductor 1 and the transfer paper 9 is eliminated by the separation charger 11, and the transfer paper 9 is separated from the photoconductor 1 by the separation claw 12. After the transfer paper 9 is separated, the surface of the photoconductor 1 is cleaned by the pre-cleaning charger 13, the fur brush 14, and the cleaning blade 15. This cleaning can also be performed by removing the remaining toner using only the cleaning blade 15.

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 if it is developed with toner of positive (negative) polarity, a negative image can be obtained. A known method is applied to such a developing unit.
In addition, a known method is used for the charge removing means.

In this example, the conductive support is shown as a drum, but a sheet or an endless belt can be used. As the pre-cleaning charger, known charging means such as a contron, a scorotron, a solid state charger (solid state charger), a charging roller and the like can be used. Although the above-mentioned charging means can be usually used for the transfer charger and the separation charger, a charger in which the transfer charger and the separation charger are integrated as shown in FIG. 5 is efficient and preferable. As the cleaning member, a known member such as a blade fur brush or a mag fur brush can be used.

FIG. 5 is a schematic diagram illustrating another example of the electrophotographic process of the present invention. In this example, the belt-shaped photoconductor 21 has a TiOPc photoconductive layer, is driven by a driving roller 22a or 22b, is charged by a charger 23, is exposed by an image exposure source 24, and is developed (not shown). Transfer by the transfer charger 25, exposure before cleaning by the exposure unit 26 before cleaning, cleaning by the cleaning brush 27,
A series of image formations consisting of the static elimination by is performed repeatedly. In this case, the exposure of the exposed portion before cleaning is performed by the photosensitive member 2
1 from the conductive support side. Of course, in this case, the conductive support is translucent.

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. 5, 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 charge erasing exposure 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, pre-exposure of image exposure, and other known light irradiation steps are provided. Light irradiation can also be performed on the body.

The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, or may be incorporated in the apparatus in the form of a process cartridge. The process cartridge includes a photoreceptor, and further includes a charging unit, an exposing unit, a developing unit, a transferring unit, a cleaning unit, and a discharging unit.
Devices (parts). There are many shapes and the like of the process cartridge. As a general example, there is a process cartridge shown in FIG. The process cartridge shown in FIG. 6 includes a charging charger 1 arranged around a photoconductor 16.
7, a compact structure including a cleaning brush 18, an image exposure unit 19, a developing roller 20, and the like.

[0072]

The present invention will be described below with reference to examples.
The present invention is not limited by these embodiments. All parts are parts by weight.

(Example 1) A partially stabilized zirconium ball was filled in a Pyrex glass ball mill pot having an internal volume of 1 liter, and the following materials were charged.
Rolled and dispersed for 0 hour to obtain a dispersion. TiOPc pigment powder: 2 parts Azo pigment of the following structural formula (of the general formula (1)): 1 part

Embedded image Polyvinyl butyral: 1.5 parts 2-butanone: 200 parts

Comparative Example 1 The following materials were charged into the same ball mill pot as used in Example 1, and then tumbled and dispersed at room temperature for 60 hours to obtain a dispersion. TiOPc pigment powder: 2 parts Polyvinyl butyral: 1.5 parts 2-butanone: 200 parts

Example 2 The following materials were charged into the same ball mill pot as used in Example 1, and then tumbled and dispersed at room temperature for 20 hours to obtain a dispersion. TiOPc pigment powder: 2 parts Azo pigment of the following structural formula (of general formula (1)): 2 parts

Embedded image Polyvinyl butyral: 1 part Tetrahydrofuran: 200 parts

(Comparative Example 2) The following materials were charged into the same ball mill pot as used in Example 1, and then tumbled and dispersed at room temperature for 20 hours to obtain a dispersion. Azo pigment of the general formula (1) used in Example 2: 2 parts Polyvinyl butyral: 0.5 parts Tetrahydrofuran: 200 parts

Example 3 The following materials were charged into the same ball mill pot as used in Example 1, and then tumbled and dispersed at room temperature for 5 hours. TiOPc pigment powder: 3 parts Polyvinyl butyral: 1 part Tetrahydrofuran: 100 parts Next, the following materials were charged, and the mixture was further dispersed for 12 hours to obtain a target dispersion. Azo pigment of the following structural formula (of the general formula (1)): 1 part

Embedded image 2-butanone: 100 parts

Example 4 The following materials were placed in the same ball mill pot as used in Example 1, and then tumbled and dispersed at room temperature for 5 hours. TiOPc pigment powder: 3 parts Azo pigment of the following structural formula (of general formula (1)): 1.5
Department

Embedded image Polyvinyl butyral: 1 part Tetrahydrofuran: 150 parts Next, the following materials were charged, and the mixture was further dispersed for 12 hours to obtain a target dispersion. TiOPc pigment powder: 2 parts Ethyl cellosolve: 50 parts

Example 5 The following materials were placed in the same ball mill pot as used in Example 1, and then tumbled and dispersed at room temperature for 10 hours to obtain a dispersion. Azo pigments of the following structural formula (of general formula (1)): 1.3
Department

Embedded image Polyvinyl butyral: 1 part Tetrahydrofuran: 50 parts At the same time, the following materials were charged into the same ball mill pot as used in Example 1, and then tumbled and dispersed at room temperature for 10 hours to obtain a dispersion. TiOPc pigment powder: 2 parts Ethyl cellosolve: 150 parts Next, these dispersions were mixed and further dispersed for 10 hours to obtain a dispersion.

Each of the dispersions of Examples 1 to 5 and Comparative Examples 1 and 2 prepared as described above was used to prepare an inner diameter of 5 mm and a length of 30 cm.
And left for two days. The length of the resulting supernatant (the length at which the dispersion became transparent) was measured. Next, using each of the prepared dispersions of Examples 1 to 5 and Comparative Examples 1 and 2, a titanyl phthalocyanine having a dry film thickness of about 0.3 μm and / or a general film was formed on a polyethylene terephthalate film on which aluminum was deposited by a blade coating method. An organic photoconductive layer in which the bisazo pigment represented by the formula (1) was dispersed was formed. The state of the coating film at this time was visually determined.

Table 1 shows the results of the above measurements. As is evident from the results in Table 1, the photoconductor or electrophotographic photoreceptor produced using the organic pigment dispersion of the present invention has a favorable photoconductive layer, so that desirable photoconductive properties can be obtained.

[0082]

[Table 1]

Next, an undercoat layer coating solution having the following composition, the pigment dispersions of Examples 1 to 5 and Comparative Examples 1 and 2, and a charge transport coating solution having the following composition were formed on an aluminum cylinder. Coating and drying were successively performed to provide a subbing layer having a dry film thickness of 3.5 μm, a charge generation layer having a thickness of 0.2 μm, and a charge transport layer having a thickness of 24 μm. These will be referred to as the photoconductors of Examples 1 to 5 and Comparative Examples 1 and 2 described above. (Undercoat layer coating solution) Titanium dioxide powder 15 parts Polyvinyl butyral 3 parts Epoxy resin 3 parts 2-butanone 150 parts (Charge transport layer coating solution) Polycarbonate 10 parts Charge transport material of the following structural formula 8 parts

Embedded image 80 parts of methylene chloride

Each of the above photoreceptors is described in JP-A-60-10016.
The following measurement was performed with the evaluation device disclosed in Japanese Patent Publication No. Charged at corona discharge voltage -5.7 [kV] 20
V [mV] after 20 seconds, potential Vo after 20 seconds of dark decay
[V], the potential Vo is reduced by 1 /
The amount of exposure E _1/5 [lx · s] required to attenuate to 5 was measured. The potential holding ratio is defined as follows. Potential holding ratio = Vo / Vm Each of the above electrophotographic photosensitive members was attached to the electrophotographic process shown in FIG. Was printed, and the printed image at that time was evaluated.

Table 2 shows the above results. As is clear from the results shown in Table 2, the electrophotographic photoreceptor of the present invention maintains good image quality even in a large number of printings.

[0086]

[Table 2]

[0087]

According to the present invention, a dispersion of a photoconductive pigment excellent in dispersion stability and coating stability is prepared by preparing a mixed dispersion comprising titanyl phthalocyanine and an azo pigment having a specific chemical structure. Can be produced. Also,
According to the present invention, it is possible to form a highly sensitive photoconductive layer composed of titanyl phthalocyanine and an azo pigment having a specific chemical structure. Further, according to the present invention, there is provided an electrophotographic method and an electrophotographic apparatus including a photoconductor having a photoconductive layer made of titanyl phthalocyanine and an azo pigment having a specific chemical structure, so that high quality free of abnormal images is provided. Is provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an electrophotographic photosensitive member used in the present invention.

FIG. 2 is a schematic sectional view of another electrophotographic photosensitive member used in the present invention.

FIG. 3 is a schematic sectional view of still another electrophotographic photosensitive member used in the present invention.

FIG. 4 is a schematic diagram for explaining the electrophotographic apparatus of the present invention.

FIG. 5 is a schematic diagram for explaining the electrophotographic apparatus of the present invention.

FIG. 6 is a schematic diagram illustrating a typical electrophotographic apparatus of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Minoru Umeda 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H068 AA34 AA35 BA39 BA47 EA13 EA14 FA13 FA19 FA27

Claims (8)

[Claims] 1. A photoconductor comprising a layer containing at least titanyl phthalocyanine and one or more bisazo pigments represented by the following general formula (1). Embedded image (Wherein R ₁ and R ₂ are a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group,
It represents a nitro group, a cyano group, a hydroxyl group, a substituted or unsubstituted amino group, and p and q each represent an integer of 0 to 3. Cp ₁ and Cp ₂ represent a coupler residue. ) 2. An electrophotographic photoreceptor comprising a conductive support and a photosensitive layer containing at least titanyl phthalocyanine and one or more bisazo pigments represented by the general formula (1). 3. A charge generation layer comprising at least a titanyl phthalocyanine and one or more bisazo pigments represented by the general formula (1) on a conductive support, and a charge mainly composed of a charge transport material. An electrophotographic photosensitive member comprising a transport layer laminated thereon. 4. An organic pigment dispersion comprising at least titanyl phthalocyanine and one or more bisazo pigments represented by the general formula (1) dispersed in an organic solvent. 5. The method for producing a photoconductor according to claim 1, which is produced through a step of applying and drying the dispersion of claim 4. 6. The method for producing an electrophotographic photoreceptor according to claim 2, which is produced through a step of applying and drying the dispersion of claim 4. 7. An electrophotographic method wherein an electrophotographic photosensitive member is repeatedly subjected to at least charging, image exposure, development, transfer, cleaning, and charge elimination.
Or an electrophotographic method, characterized in that it is the photoconductor of item 3. 8. 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,
An electrophotographic apparatus, wherein the electrophotographic photosensitive member is the photosensitive member according to claim 2 or 3.