JP2000242010A - Photoconductor, organic pigment dispersion, method for producing photoconductor using the same, electrophotographic method, and electrophotographic apparatus - Google Patents

Abstract

(57) [Problem] To provide an electrophotographic photoreceptor having high sensitivity, excellent potential stability in repeated use, no abnormal image, and excellent dispersibility of a coating solution during production. Another object of the present invention is to provide a stable electrophotographic method which has high sensitivity, has excellent potential stability in repeated use, and has no abnormal image. Another object of the present invention is to provide a stable electrophotographic apparatus having high sensitivity, excellent potential stability in repeated use, and free from abnormal images. A photoconductor having a layer containing at least titanyl phthalocyanine and a squarium pigment represented by the general formula (1). Embedded image

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 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 by light have remarkably improved in 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 6
Since it shows high sensitivity to long wavelength light of 00 to 800 nm, it is extremely important and useful as a material for a photoreceptor for an electrophotographic printer or a digital copying machine whose light source is an LED or LD.

[0005] The photosensitive wavelength region of a function-separated type electrophotographic photosensitive member varies depending on the charge generating substance. As the charge generating material having high sensitivity around 800 nm, 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 wavelength include τ-type and η-type metal-free phthalocyanines described in JP-A-58-182639, and
JP-A-109056, JP-A-62-134651, JP-A-64-17066, and JP-A-1-17224.
No. 59, No. 2-289658, No. 3-1
No. 28973, titanyl phthalocyanine,
JP-A-1-268763, JP-A-3-269063
There is a vanadyl phthalocyanine shown in Japanese Patent Publication No.

[0006] As the performance of laser printers and copiers 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 transporting material disclosed in JP-A-62-54266 are dispersed in a binder resin, a phthalocyanine compound disclosed in JP-A-63-313165 and a specific A photoreceptor using a mixture of disazo compounds as a charge generation layer, a photoreceptor using a specific perylene compound and titanyl phthalocyanine as a charge generation material, and a specific diamine derivative as a charge transport material disclosed in JP-A-3-1150; JP-A-3-37661 discloses a photoreceptor provided with a layer in which a titanyl phthalocyanine and a polycyclic quinone compound are separately or mixed, and charges a mixture of a titanyl phthalocyanine and a specific phthalocyanine compound shown in JP-A-3-157666. A photoreceptor that uses a specific hydrazone compound as a charge transport material as a substance; Flat 3-19604
No. 9 discloses a photoreceptor using a specific disazo compound and titanyl phthalocyanine as a charge generating substance and a specific stilbene compound as a charge transporting substance.

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 govern the life characteristics of photoconductors, and titanyl phthalocyanine 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 after a long-term use, there is a problem that an abnormal image such as white spots or background stains occurs 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.

Furthermore, if the dispersibility of the coating liquid during production is low,
Not only does the productivity drop, but the electrostatic characteristics of the electrophotographic photoreceptor become unstable, and the quality of the image also deteriorates. 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 charges due to the dissociation of excitons depends on the surface area and particle size of the particles. On the other hand, particles are refined by the progress of crushing and dispersion, but conversely aggregation of particles occurs when overdispersion occurs, and dispersibility is reduced. It is difficult to obtain the dispersed state and the required electrostatic characteristics. Therefore, in order to obtain the required electrostatic characteristics, it is necessary to optimize the dispersion method and its conditions.

Documents using a mixture of a phthalocyanine and a bisazo pigment for an electrophotographic photoreceptor include, for example, JP-A-03-37666 and JP-A-07-152163. However, there are problems with abnormal images and dispersibility of the coating liquid, and it has been desired to solve the above problems with a mixed system of titanyl phthalocyanine and another pigment.

[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. 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]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and have completed the present invention. Therefore, according to the present invention, there is provided (1) a photoconductor having a layer containing at least titanyl phthalocyanine and a squarium pigment represented by the general formula (1);

[0013]

Embedded image Is provided.

According to the present invention, (2) "an electrophotographic photosensitive member characterized by having a photosensitive layer containing at least titanyl phthalocyanine and the squarium pigment on a conductive support"; An electrophotographic photoreceptor characterized by laminating a charge generation layer containing at least titanyl phthalocyanine and the squarium pigment on a conductive support, and a charge transport layer containing a charge transport material as a main component. Is provided.

Further, according to the present invention, there is provided (4) an "organic pigment dispersion comprising at least titanyl phthalocyanine and the squarium pigment dispersed in an organic solvent".

According to the present invention, there is provided (5) a process comprising applying and drying a dispersion obtained by dispersing at least titanyl phthalocyanine and the squarium pigment in an organic solvent, and drying the dispersion. A method for producing the electrophotographic photosensitive member according to the above mode (2) or (3) ".

Further, according to the present invention, (6) In the electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and charge elimination are repeatedly performed on the electrophotographic photosensitive member, (2) or the electrophotographic method according to the above (3). "

According to the present invention, there is provided (7) 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 the above mode (2) or (3).

The basic structure of the titanyl phthalocyanine pigment used in the present invention is represented by the following general formula (2).

[0020]

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 systems are known for TiOPc, 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 crystalline forms (including amorphous forms) can be used, and particularly, 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 major peak at a Bragg angle 2θ of at least 7.5 ° ± 0.2 °,
12. having crystal forms at 25.3 ° ± 0.2 ° and 28.6 ° ± 0.2 °, (iii) at least 9.3 ° ± 0.2 °, with a major peak at a Bragg angle 2θ of 13. 1 °
Those having crystal forms at ± 0.2 ° and 26.2 ° ± 0.2 ° are preferably used.

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

As the squarium pigment in the present invention, a compound represented by the following general formula (1) can be used.

[0025]

Embedded image

Next, the general formula (1) used in the present invention
Table 1 shows specific examples of the compound represented by.

[0027]

[Table 1]

[0028]

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 organic photoconductive layer used in the present invention. On a conductive support (31), a single-layer photosensitive layer (3) containing a charge generation material and a charge transport material as main components is shown.
3) is provided.

FIGS. 2 and 3 are cross-sectional views showing another example of the structure of the organic photoconductive layer used in the present invention, wherein a charge generating layer (35) containing a charge generating material as a main component and a charge transporting material. And a charge transporting layer (37) whose main component is. 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, It can also be used for photovoltaic cells and the like.

As the conductive support (31), a conductive support having a volume resistivity of 10 ¹⁰ Ω · cm or less, for example, 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 subjecting to a surface treatment 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, A thermoplastic, thermosetting resin, or photocurable resin such as an alkyd resin may be used. Such a conductive layer is formed by mixing these conductive powders and a binder resin with a suitable solvent, for example, THF, MDC, MEK,
It can be provided by dispersing and applying in toluene or the like.

Further, the heat-shrinkable tube containing the above-mentioned conductive powder in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon, etc. on a suitable cylindrical substrate is used for the conductive material. 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 laminate, 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 squarium pigment of the general formula (1). The charge generation layer (35)
The charge generation material is formed by dispersing the charge generation material in a suitable solvent together with a binder resin as required, coating the resultant 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. The squarium pigment of the general formula (1) basically tends to show an amorphous shape, but is not necessarily limited thereto. TiO used in the present invention
The ratio of Pc to the squarium pigment of the general formula (1) is Ti
OPc is 1 and the squarium pigment of the general formula (1) is 0.01 to 100, preferably 0.1 to 90.
It is. The method of mixing these pigments may be such that TiOPc and the squarium pigment of the general formula (1) are simultaneously dispersed from the beginning in the following solvent, or the square of the general formula (1) is An helium pigment may be added, or the order may be reversed. Further, TiOPc and the squarium pigment of the general formula (1) separately dispersed may be mixed later.

As the non-aqueous solvent as a dispersion medium, known ones can be widely used. Isopropanol, acetone, methyl ethyl ketone (MEK), cyclohexanone, tetrahydrofuran (THF), dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane (MD
C), dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like can be preferably used. These solvents are used alone or as a mixture. These solvents may be mixed and used from the beginning, or the diluting solvent may be mixed after dispersing TiOPc and / or the squarium pigment of the general formula (1) using these solvents.

Examples of the binder resin that may be used as appropriate include polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polyacrylamide and the like. Used. The ratio between the binder resin and the pigment is preferably from 0/3 to 3/1, and more preferably from 0/2 to 2/1. The binder resin may be added before dispersion, or
And / or the general formula (1) and / or the squarium pigment may be added after being dispersed only with the solvent. Moreover, it is also possible to add during the dispersion.

As the material of the medium, zirconia, glass, alumina, non-oxide, metal and the like can be used.

As a dispersion means for obtaining a dispersion by wet dispersion, a known method 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.

As a method for applying the coating solution, a dip coating method, a spray coat, a bead coat, a nozzle coat, a spinner coat, a ring coat or the like can be used.
In the charge generation layer (35), it is possible to use other charge generation materials in addition to the above-mentioned TiOPc and the squarium pigment of the general formula (1), and typical examples thereof include an azo pigment and a perylene pigment. And 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.
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 this 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-
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 derivative, triarylmethane derivative, 9
-Known materials such as styryl anthracene derivative, pyrazoline derivative, divinylbenzene derivative, hydrazone 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 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.

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 squarium pigment of the general formula (1) are dispersed in a binder resin can be used. The single-layer photosensitive layer can be formed by dissolving or dispersing a charge generating substance, a charge transporting substance, and a binder resin in a suitable solvent, and applying and drying the same. 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, the charge transport layer (3
In addition to using the binder resin described in 7) as it is, the binder resin described in the charge generation layer (35) may be mixed and used. 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 1 part by weight based on 100 parts by weight of the binder resin.
It is preferably 90 parts by weight, more preferably 50 to 150 parts by weight. The single-layer photosensitive layer comprises a charge-generating substance, a binder resin together with a charge-transporting substance, if necessary, tetrahydrofuran,
It can be formed by applying a coating liquid dispersed by a disperser or the like using a solvent such as dioxane, dichloroethane, or cyclohexane by a dip coating method, a spray coat, a bead coat, or the like. The thickness of the single-layer photosensitive layer is suitably about 5 to 100 μm.

The electrophotographic photoreceptor 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 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 includes Al
₂ O ₃ provided by anodic oxidation, organic material 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, polymethylbenten, 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 fluorine resins 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, a normal 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 formed by a vacuum thin film forming method,
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 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. 4, the electrophotographic apparatus includes a static elimination exposure section (2), a charging charger (3), and a counter-clockwise direction that is close to the upper surface of a drum-shaped photoconductor (1) and along the circumference. Eraser (4), image exposure unit (5), developing unit (6), pre-transfer charger (7), transfer charger (10), separation charger (1)
1), separation claw (12), charger (1
3), fur brush (14), cleaning brush (1
5) is sequentially attached. Further, a registration roller (8) for feeding the transfer paper (9) between the photoreceptor (1), the transfer charger (10) and the separation charger (11) is 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 electrophotographic apparatus, the photoreceptor (1) rotates counterclockwise, is negatively (or positively) charged by the charging charger (3), and is exposed to an image. By the exposure from (5), 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 source used in the image exposure section (5), the neutralizing lamp (2), etc. includes a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), and a semiconductor laser (LD). And a light emitting material such as electroluminescence (EL). 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. 4, a charge removal process, a cleaning process, or a pre-exposure process. Can also be used.

In the developing unit (6), toner is adhered to the photoreceptor (1) to develop an electrostatic latent image, and the pre-transfer charger (7) adjusts the charged state of the toner image. (10) Transfer paper (9)
The toner image is transferred to the photosensitive member (1) and the electrostatic adhesion between the photoconductor (1) and the transfer paper (9) is eliminated by the separation charger (11). ). After the transfer paper (9) is separated, the surface of the photoconductor (1) is cleaned with the pre-cleaning charger (13), fur brush (14), and cleaning brush (15). This cleaning can also be performed by removing the remaining toner using only the cleaning brush (15).

When the photosensitive member is negatively (or positively) charged and subjected to image exposure, a negative (or positive) electrostatic latent image is formed on the photosensitive member. If this is developed with a positively (or negatively) charged toner (electrostatic fine particles), a positive image can be obtained, and if it is developed with a negatively (or positively) charged toner, a negative image can be obtained. A known method can be applied to such a developing means, and a known method is also used for the charge removing means.

In this example, the conductive support is shown as a drum, but a sheet or an endless belt may be used. As the pre-cleaning charger, known charging means such as a corotron, a scorotron, a solid 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. 4 is efficient and preferable. As the cleaning brush, a known brush such as a fur brush or a mag fur brush can be used.

FIG. 5 is a schematic diagram for explaining another example of the electrophotographic process according to the present invention. In this example,
The belt-shaped photoreceptor (21) has a TiOPc photosensitive layer having a specified impurity content, is driven by drive rollers (22a) and (22b), and is charged by a charging charger (23). Image exposure by exposure source (24), development (not shown), transfer by transfer charger (25), pre-cleaning exposure by pre-cleaning exposure unit (26), cleaning by cleaning brush (27), by static elimination light source (28) A series of image formation including static elimination is repeatedly performed. In this case, the exposure of the exposed portion before cleaning is performed from the conductive support side of the photoconductor (21). Of course, in this case, the conductive support is translucent.

The above-described electrophotographic process exemplifies an embodiment of the present invention, and other embodiments are of course possible. For example, in FIG. 5, the pre-cleaning exposure can be performed from the photosensitive layer side, and the exposure of the image exposure section and the charge removal exposure section can be performed from the conductive support side. On the other hand, the light irradiation step includes image exposure,
Although the pre-cleaning exposure and the static elimination exposure are shown, the photoreceptor can be irradiated with light by further providing a pre-transfer exposure, an image exposure pre-exposure, and other known light irradiation steps.

The image forming means of the present invention as described above may be fixedly incorporated in an apparatus such as a copying machine, a facsimile, a printer, or the like, but may be incorporated in the apparatus in the form of a process cartridge. Is also good. The process cartridge is one device (part) including a photoconductor, and further including a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a discharging unit. There are many shapes and the like of the process cartridge. As a general example, the one shown in FIG. 6 can be mentioned. The process cartridge shown in FIG. 6 includes a charging charger (17), a cleaning brush (18), an image exposure unit (19), and a developing roller (2) arranged around a photoconductor (16).
0) and the like.

[0061]

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.

(Example 1) A partially stabilized zirconium ball was charged into 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 Squarium pigment (A, B: dye No. 1) 1 part Polyvinyl butyral 1.5 parts 2-butanone 200 parts

(Comparative Example 1) 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 60 hours to obtain a dispersion. TiOc 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 Squarium pigment (A: Dye No. 1, B: Dye No. 2) 2 parts 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. Example 2 Squarium pigment 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 further dispersed for 12 hours to obtain a target dispersion. Squarium pigment (A: Dye No. 5, B: Dye No. 7) 1 part 2-butanone 100 parts

Example 4 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 Squarium pigment (A: Dye No. 3, B: Dye No. 5) 1.5 parts Polyvinyl butyral 1 part Tetrahydrofuran 150 parts Next, the following materials were charged, and further dispersed for 12 hours. The desired dispersion was obtained. 2 parts of TiOPc pigment powder 50 parts of ethyl cellosolve

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. Squarium pigment (A: Dye No. 3, B: Dye No. 11) 1.3 parts Polyvinyl butyral 1 part Tetrahydrofuran 50 parts At the same time, in the same ball mill pot as used in Example 1, each of the following After charging the raw materials, they were 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 placed in a glass tube having an inner diameter of 5 mm and a length of 30 cm and left for 2 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 an aluminum-deposited polyethylene terephthalate film by a blade coating method. An organic photoconductive layer in which the squarium pigment represented by the formula (1) was dispersed was formed. The state of the coating film at this time was visually determined.
Table 2 shows the results of the above measurements.

[0070]

[Table 2]

Next, an undercoat layer coating solution of the following composition, the pigment dispersions of Examples 1 to 5 and Comparative Examples 1 and 2, and a charge transport layer coating solution of the following composition were placed on an aluminum cylinder. , Sequentially applied and dried, each having a dry film thickness of 3.5 μm
Was provided with a subbing layer, a 0.2 μm charge generation layer, and a 24 μm charge transport layer, to produce a laminated photoreceptor. These will be referred to as the photoconductors of Examples 1 to 5 and Comparative Examples 1 and 2 described above. ◎ Coating liquid for undercoat layer 15 parts of titanium dioxide powder 3 parts for polyvinyl butyral 3 parts for epoxy resin 150 parts for 2-butanone ◎ Coating liquid for charge transport layer 10 parts Polycarbonate 10 parts Charge transport material of the following structural formula 8 parts

[0072]

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. A potential Vm (V) 20 seconds after charging at a corona discharge voltage of -5.7 kV, a potential Vo (V) 20 seconds after dark decay,
The exposure amount E _1/5 [lx · s] required to attenuate the potential Vo to １ ／ with white light having an intensity of 61 × was measured. The potential holding ratio is defined as follows. Potential holding ratio = Vo / Vm

Each of the above electrophotographic photosensitive members was mounted in the electrophotographic process shown in FIG.
(It is assumed that the LD emits light at 0 nm), and 10,000 sheets were continuously printed, and the printed image at that time was evaluated. Table 3 shows the above results.

[0075]

[Table 3]

[0076]

As described above, according to the present invention, according to the present invention, by preparing a mixed dispersion comprising titanyl phthalocyanine and a squarium pigment, dispersion stability and coating stability can be improved. An excellent photoconductive pigment dispersion can be prepared. According to the present invention,
A highly sensitive photoconductive layer composed of titanyl phthalocyanine and squarium pigment can be formed. Further, according to the present invention, an electrophotographic method and an electrophotographic apparatus including a photoconductor having a non-conductive layer composed of titanyl phthalocyanine and a squarium pigment are provided, so that a high-quality printing system that does not generate an abnormal image is provided. Is done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an organic photoconductive layer according to the present invention.

FIG. 2 is a cross-sectional view showing another configuration example of the organic photoconductive layer in the present invention.

FIG. 3 is a cross-sectional view showing another configuration example of the organic photoconductive layer in the present invention.

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

FIG. 5 is a schematic view illustrating another example of the electrophotographic process of the present invention.

FIG. 6 is a view showing a general example of the shape of the process cartridge of 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 Unit 27 Cleaning Brush 28 Static Elimination Light Source 31 Conductive Support 33 Single Layer photosensitive layer 35 charge generation layer 37 charge transport layer

 ──────────────────────────────────────────────────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 AA19 AA31 AA34 AA35 BA35 BA39 EA13 EA14 EA19 FA13

Claims (7)

[Claims] 1. A photoconductor comprising a layer containing at least titanyl phthalocyanine and a squarium pigment represented by the general formula (1). Embedded image 2. An electrophotographic photoreceptor comprising a conductive support and a photosensitive layer containing at least titanyl phthalocyanine and the squarium pigment. 3. An electrophotograph, wherein a charge generation layer containing at least titanyl phthalocyanine and the squarium pigment and a charge transport layer containing a charge transport material as a main component are laminated on a conductive support. Photoconductor. 4. An organic pigment dispersion obtained by dispersing at least titanyl phthalocyanine and the squarium pigment in an organic solvent. 5. The method according to claim 2 or 3, wherein the composition is produced through a step of applying and drying a dispersion obtained by dispersing at least titanyl phthalocyanine and the squarium pigment in an organic solvent. For producing an electrophotographic photoreceptor. 6. An electrophotographic method in which an electrophotographic photoreceptor is repeatedly subjected to at least charging, image exposure, development, transfer, cleaning, and charge elimination, wherein the electrophotographic photoreceptor according to claim 2 or 3 is used. An electrophotographic method characterized by being a body. 7. 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,
4. An electrophotographic apparatus, wherein the electrophotographic photosensitive member is the photosensitive member according to claim 2 or 3.