JPH11143097A - Electrophotographic photoreceptor, electrophotographic method, electrophotographic apparatus, and process cartridge for electrophotographic apparatus - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a stable electrophotographic photoreceptor which does not cause a decrease in chargeability and an increase in residual potential even when used repeatedly. SOLUTION: In an electrophotographic photosensitive member in which a photosensitive layer containing titanyl phthalocyanine is provided on a conductive support, a reduction potential is -0.15 ± 0.05 volt with respect to titanyl phthalocyanine per unit weight. Wherein the content of the electron-accepting impurities is 0.9 or less as a value defined by the following I value. _{^{I = i d Lm -2/3 t -1/6}} ····· ( Equation A) (wherein, i _d is the cathode side of the diffusion limiting current in an electrochemical analysis using the dropping mercury electrode [.mu.A ], L is the volume (l) of the solvent that dissolves the test substance, m is the flow rate of mercury at the dropping mercury electrode (mg / s), and t is the dropping time of mercury (s).)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member, an electrophotographic method and an electrophotographic apparatus using the same, and a process cartridge for the electrophotographic apparatus.
The present invention relates to an electrophotographic photosensitive member excellent in stability of a charged potential and a residual potential of a photosensitive member even after repeated use, an electrophotographic method and an electrophotographic apparatus using the same, and a process cartridge for the electrophotographic device.

[0002]

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

At present, small, inexpensive and highly reliable semiconductor lasers (LDs) and light emitting diodes (LEDs) are 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 materials such as various azo pigments, polycyclic quinone pigments, trigonal selenium, and various phthalocyanine pigments have been developed. Among them,
Since titanyl phthalocyanine (abbreviated as TiOPc) has high sensitivity to long-wavelength light of 600 to 800 nm, it is extremely important as a material for a photoreceptor for an electrophotographic printer or a digital copying machine whose light source is an LED or LD. Useful.

On the other hand, conditions of an electrophotographic photosensitive member repeatedly used in the Carlson process and similar processes include sensitivity, reception potential, potential retention, potential stability, residual potential, and electrostatic characteristics represented by spectral characteristics. It is required to be excellent. In particular, it has been empirically known that, for high-sensitivity photoconductors, a decrease in chargeability and an increase in residual potential due to repeated use dominate the life characteristics of the photoconductor. is not. 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.

[0006] Literature relating to the synthesis method of phthalocyanine and electrophotographic properties is disclosed in, for example, JP-A-57-14874.
No. 5, JP-A-59-36254, JP-A-59-36254
-44054, JP-A-59-31965,
JP-A-61-239248, JP-A-62-670
No. 94 publication. However, TiOPc
The relationship between the purity of the toner and the electrostatic characteristics of the photoreceptor has not been clarified.

[0007]

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

[0008]

Means for Solving the Problems The present inventors have proposed TiOP.
Focusing on the purity of c, the inventors of the present invention have made intensive studies on components that adversely affect the electrostatic characteristics of the photoreceptor after repeated use in order to solve the above problems, and have completed the present invention. That is, according to the present invention, (1) in an electrophotographic photosensitive member having a photosensitive layer containing titanyl phthalocyanine on a conductive support, the reduction potential of the titanyl phthalocyanine per unit weight is reduced. -0.15 ± 0.05
An electrophotographic photosensitive member, wherein the content of the electron-accepting impurities in volts is 0.9 or less as a value defined by the following I value:

Equation 5] _{^{I = i d Lm -2/3 t -1/6}} ····· ( Equation A) (wherein, i _d is the cathode side of the diffusion limitations in electrochemical analysis using the dropping mercury electrode The current value [μA], L is the volume (l) of the solvent in which the test substance is dissolved, m is the flow rate of mercury (mg / s) at the dropping mercury electrode, and t is the dropping time (s) of mercury. (2) "Titanyl phthalocyanine has at least 9.6 ° ± 0.2 °, 24.0 ° ± 0.2 °, and 27.25 ° main peaks at Bragg angle 2θ in X-ray diffraction spectrum with respect to Cu-Kα ray.
The electrophotographic photoreceptor according to the above (1), which has a crystal form at 2 ° ± 0.2 °;
(3) “Titanyl phthalocyanine has a main peak at a Bragg angle 2θ of at least 7.5 ° ± 0.2 ° and 25.3 ° ±± in an X-ray diffraction spectrum with respect to Cu—Kα radiation.
The electrophotographic photoreceptor according to the above (1), wherein the titanyl phthalocyanine has a crystal form at 0.2 ° and 28.6 ° ± 0.2 °.
In the X-ray diffraction spectrum for Cu-Kα ray, the main peak at Bragg angle 2θ was at least 9.3 ° ± 0.2.
°, 13.1 ° ± 0.2 °, and 26.2 ° ± 0.2 ° in the form of a crystal. Is done.

(5) An electrophotographic method in which at least charging, image exposure, development, transfer, cleaning and charge elimination are repeatedly performed on an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member contains titanyl phthalocyanine, and The content of an electron-accepting impurity having a reduction potential of -0.15 ± 0.05 volts with respect to the titanyl phthalocyanine per weight is 0.9 or less as defined by the above I value. An electrophotographic method "is provided.

Further, (6) "at least a charging means, an image exposing means, a developing means, a transferring means, a cleaning means,
An electrophotographic apparatus comprising a static eliminator and an electrophotographic photoreceptor, wherein the electrophotographic photoreceptor contains titanyl phthalocyanine, and has a reduction potential of -0.15 ± with respect to the titanyl phthalocyanine per unit weight. An electrophotographic apparatus, wherein the content of the electron-accepting impurity of 0.05 volts is 0.9 or less as defined by the above-mentioned I value ",
And (7) a process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member contains titanyl phthalocyanine, and a reduction potential of the titanyl phthalocyanine per unit weight. A process cartridge for an electrophotographic apparatus, characterized in that the content of the electron-accepting impurity of -0.15 ± 0.05 volts is 0.9 or less as defined by the above I value. .

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

[0012]

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

Various crystal forms 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 crystal forms can be used.
In an X-ray diffraction spectrum using characteristic X-rays (wavelength 1.54 °), (i) main peaks at Bragg angles 2θ are at least 9.6 ° ± 0.2 °, 24.0 ° ± 0.2 °, and 27 ° Having a crystal form at 2 ° ± 0.2 °, (i
i) Main peak of Bragg angle 2θ is at least 7.5 °
± 0.2 °, 25.3 ° ± 0.2 ° and 28.6 ° ±
(Iii) having a main peak at a Bragg angle 2θ of at least 9.3 ° ± 0.2 °,
Those having crystal forms at 13.1 ° ± 0.2 ° and 26.2 ° ± 0.2 ° are preferably used.

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

As described above, TiOPc exhibiting high sensitivity
In the case of a photoreceptor using the same, repeated use in the Carlson process and similar processes causes a decrease in chargeability and an increase in residual potential, and thus determines the life of the photoreceptor. The present inventors have paid attention to the purity of TiOPc, studied the components that adversely affect the electrostatic characteristics after repeated use of the photoreceptor in order to solve this problem, and as a result, inevitably generated when synthesizing TiOPc. It was found that the content of an electron accepting compound exhibiting a specific reduction potential among the target impurities governs the above characteristics. Based on this knowledge, TiO
In the process of synthesizing and purifying Pc, it was confirmed that when the content of the electron accepting substance could be reduced to a specific value or less, the repetition characteristics of the above physical properties would be excellent, and the present invention was completed. .

The reason why an electron-accepting compound exhibiting a specific reduction potential causes a decrease in chargeability and an increase in residual potential due to repeated use of the TiOPc photoreceptor is not clear, but is presumed as follows. That is, photocarriers are generated in TiOPc following photon absorption, of which electrons are trapped in the electron accepting compound, probably by the action of energy levels. It is considered that this electron trap causes a rise in the residual potential. Further, the trapped electrons induce the injection of holes from the conductive substrate, which is considered to reduce the chargeability of the photoconductor.

On the other hand, the amount of impurities generated during the synthesis of TiOPc depends on the type of reaction material, purity and synthesis conditions, and the generated impurities are separated from TiOPc through separation operations such as generation and washing. For example, it is obvious that the reaction temperature and reaction time, the type of solvent used for washing, the number of washings and the temperature, and the like have a considerable influence on the purity, and the generation of by-products is inevitable. Therefore, the amount of impurities contained in TiOPc finally used for the photoreceptor cannot be unconditionally defined through processes such as reaction and purification. However, it is needless to say again that it is desirable to control and define the amount of the specific impurity contained in the photoconductor in order to improve the photoconductor characteristics in repeated use.

Next, a method for quantifying impurities will be described.
For example, alcohol, ketone,
Extraction is performed with a polar solvent such as an ester, and the extraction is performed until the extraction amount becomes saturated. Then, the extraction solvent and TiOP
After separating the c-powder by filtration or the like, the solvent is evaporated to separate extracted impurities. The impurities mentioned here include those that do not affect the electrostatic characteristics of the photoconductor and those that do not. A predetermined amount of acetonitrile and an unrelated salt (supporting electrolyte) such as tetraethylammonium perchlorate and tetrabutylammonium perchlorate are added to the separated impurities and dissolved to prepare a test solution. The test solution can be quantified by an electrochemical analysis means such as a polarograph, etc., for an electron-accepting compound exhibiting a specific target reduction potential. For polarographic analysis, see Ele by AJ Bard and LRFaulkner.
ctrochemical Methods ”in Wiley, 1980. Here, a dropping mercury electrode is used as a working electrode, a noble metal such as platinum or gold is used as a counter electrode, and a saturated sweet pepper electrode (SC) is used as a reference electrode.
It can be measured by the potential scanning method using a potentiostat using E).

FIG. 1 shows an example of a typical polarograph of a test solution prepared by the above-described method. −0.15 V vs. S
A reduction current centered around EC is observed. A current value perpendicular to the X axis (electrode potential axis) intersecting with a line segment ab extending the residual current on the anode side than the reduction current is observed and a line cd parallel to ab in a region where the reduction reaction current is saturated. i
_d [μA] is defined. This current value is given by the following Ilkovich equation (1). ^{_{i d = 708nCD 1/2 m 2/3 t}} 1/6 (1) ( wherein, n the number of electrons for the reaction, C is the reactant concentrations (m
mol / l), and D is the diffusion coefficient of the reactant (cm ² /
s) and m are the flow rate of mercury at the dropping mercury electrode (mg /
s) and t are mercury drop times (s). Note that C is expressed by the following equation (2). C = M / L (2) (where M is extracted from 1 gram of TiOPc)
0.15Vvs. The amount (m mol) of the electron accepting substance reduced near the SEC, and L is the volume (l) of acetonitrile that dissolves the electron accepting substance. From the equations (1) and (2), the quantification of the electron accepting substance independent of the experimental conditions contained in 1 gram of TiOPc can be defined and expressed by the I value shown in the following equation (3). . ^{_{I = i d Lm -2/3 t -1/6}} = 708nMD 1/2 (3) The unit of I value is ^{(μA · l · s 1/2 ·} mg -2/3).

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 2 is a cross-sectional view showing an electrophotographic photosensitive member used in the present invention.
A single-layer photosensitive layer (33) containing a charge generation material and a charge transport material as main components is provided. FIG. 3 and FIG. 4 are cross-sectional views showing another configuration example of the electrophotographic photoreceptor used in the present invention.
And a charge transport layer (37) mainly composed of a charge transport material.

As the conductive support (31), those exhibiting conductivity of not more than 10 ¹⁰ Ωcm, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, Film or cylindrical plastic or paper coated with metal oxides such as indium oxide by vapor deposition or sputtering, or plates of aluminum, aluminum alloy, nickel, stainless steel, etc., and methods such as extrusion and drawing A pipe or the like that has been surface-treated by cutting, superfinishing, polishing, or the like after it has been formed into a tube can be used. Also, Japanese Unexamined Patent Publication No. Sho 52-3
The endless nickel belt and the endless stainless belt disclosed in Japanese Patent Application Laid-Open No. 6016 are also applicable to the conductive support (3).
It can be used as 1).

In addition, the above-mentioned support obtained by dispersing a conductive powder in a suitable binder resin 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,
Metal powder of copper, zinc, silver, etc. or conductive tin oxide, ITO
And the like. Further, the binder resin used simultaneously, polystyrene, 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 , Thermoplastics such as polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin,
A thermosetting resin or a photocurable resin is used. Such a conductive layer may be formed by applying the conductive powder and the binder resin to a suitable solvent, for example, THF (tetrahydrofuran),
It can be provided by dispersing and applying to MDC (dichloromethane), MEK (methyl ethyl ketone), 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 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 containing TiOPc as a main component in which the content of the electron-accepting compound as an impurity described above as a charge generation material is a specific amount or less. The charge generation layer (35) is prepared by dispersing the TiOPc together with a binder resin, if necessary, in an appropriate solvent using a ball mill, an attritor, a sand mill, ultrasonic waves, or the like, and applying the dispersion on a conductive support. , Formed by drying. The binder resin used for the charge generation layer (35) as necessary includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin,
Acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N-vinylcarbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide , Polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone and the like. The amount of the binder resin is 0 to 5 with respect to 100 parts by weight of the charge generating substance.
00 parts by weight, preferably 10 to 300 parts by weight, is suitable.

The charge generation layer (35) includes the above-described TiOP
In addition to c, other charge generating materials can be used in combination, and typical examples thereof include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, and quinone condensed polycyclic compounds. And squaric acid dyes, phthalocyanine pigments, naphthalocyanine pigments, and azulenium salt dyes.

The solvents used herein include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane,
Examples include toluene, xylene, and ligroin. As a method of applying the coating liquid, a method such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, and ring coating can be used. Charge generation layer (3
The film thickness of 5) is suitably about 0.01 to 5 μm, and preferably 0.1 to 2 μm.

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

The charge transport material includes a hole transport material and an electron transport material. Examples of the electron transporting 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
Electron accepting substances such as 8-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-carbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole Derivatives,
Oxadiazole derivative, imidazole derivative, monoarylamine derivative, diarylamine derivative, triarylamine derivative, stilbene derivative, α-phenylstilbene derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9-styrylanthracene derivative, pyrazoline Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bis-stilbene derivatives,
Other known materials such as enamine derivatives may be used. These charge transport materials are used alone or in combination of two or more.

Examples of the binder resin include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and polystyrene. Vinyl acetate, polyvinylidene chloride, polyarylate, 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,
Thermoplastic or thermosetting resins such as phenolic resins and alkyd resins are exemplified. The amount of the charge transporting material is suitably 20 to 300 parts by weight, preferably 40 to 150 parts by weight based on 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably about 5 to 100 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 general plasticizers for general resins, such as dibutyl phthalate and dioctyl phthalate, can be used as they are.
About 0% by weight is appropriate. 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 TiOPc in which the content of the electron-accepting compound as an impurity described above is set to a specific amount or less is dispersed in a binder resin can be used. The single-layer photosensitive layer can be formed by dissolving or dispersing the charge-generating substance, the charge-transporting substance, and the binder resin in a suitable solvent, coating and drying. 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, spray coating, bead coating, or the like.
The thickness of the single-layer photosensitive layer is suitably about 5 to 100 μm.

The electrophotographic photosensitive member used in the present invention includes:
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 case of the above-described photosensitive layer.

Further, a silane coupling agent, a titanium coupling agent, a chromium coupling agent or the like can be used as the undercoat layer of the photoreceptor in the present invention.
In addition, the undercoat layer of the present invention is provided with Al ₂ O ₃ by anodic oxidation, an organic substance such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, Ce.
Those provided with an inorganic substance such as O ₂ by a vacuum thin film manufacturing method can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.

The electrophotographic photosensitive member used in the present invention includes:
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, ACS 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, polystyrene, AS resin, butadiene
Examples include styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, and epoxy resin.

For the purpose of improving abrasion resistance, a fluororesin such as polytetrafluoroethylene, a silicone resin, and titanium oxide,
A dispersion of an inorganic material such as tin oxide or potassium titanate can be added. As a method of forming the protective layer,
A normal coating method is employed. In addition, the thickness of the protective layer is 0.1.
About 1 to 10 μm is appropriate. In addition to the above, known materials such as a-carbon and a-SiC formed by a vacuum thin film manufacturing method 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. In the intermediate layer, a binder resin is generally used 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. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.

Hereinafter, the electrophotographic method and the electrophotographic apparatus of the present invention will be described in detail with reference to the drawings. FIG. 5 is a schematic diagram for explaining one example of 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. 5, the electrophotographic apparatus includes a static elimination exposure section (2), a charging charger (3), and an erasing counterclockwise in proximity to the upper surface of a drum-shaped photoconductor (1) and along the circumference. -Charger (4), image exposure section (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 positively or negatively charged by the charging charger (3), and further has an eraser ( After the residual toner is cleaned by 4), an electrostatic latent image is formed on the photoconductor 1 by exposure from the image exposure unit 5. As the transfer means, generally, the above-mentioned 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) and the static elimination lamp (2) is a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), A light-emitting substance such as electroluminescence (EL) can be used. To irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used. Such a light source or the like is provided with a process such as a transfer process using light irradiation, a charge removal process, a cleaning process, or a pre-exposure process in addition to the process illustrated in FIG. Can also be used.

In the developing unit (6), toner is adhered to the photoreceptor (1) to develop an electrostatic latent image, and the charging state of the toner image is adjusted by the pre-transfer charger (7). (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 by the pre-cleaning charger (13), the fur brush (14) and the cleaning brush (15). This cleaning is performed using a cleaning brush (1
It can also be performed by removing the remaining toner only by 5).

When image exposure is performed by applying positive (or negative) charge to the photoconductor, a positive (or negative) electrostatic latent image is formed on the photoconductor. If this is developed with a positively (or negatively) charged toner (electrostatic detection fine particles), a positive image can be obtained. Conversely, if the positively (or negatively) charged toner is developed, a negative image can be obtained. An image is obtained. A known method can be applied to such development, 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 can be used. As the pre-cleaning charger, known charging means such as a corotron, 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 generally 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 brush, a known brush such as a fur brush or a mag fur brush can be used.

FIG. 6 is a schematic diagram illustrating another example of another electrophotographic process of the present invention. In this example, the belt-shaped photoreceptor (21) has a TiOPc photosensitive layer in which a specific impurity content is specified, and a driving roller (22).
a) and (22b) driven by the charging charger (2).
3) charging, image exposure by an image exposure source (24), development (not shown), transfer by a transfer charger (25),
Pre-cleaning exposure by a pre-cleaning exposure unit (26), cleaning by a cleaning brush (27),
A series of image operations including static elimination by the static elimination light source (28) are sequentially and 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 electrophotographic process illustrated above is an example of an embodiment of the present invention, and other embodiments are of course possible. For example, in FIG. 6, the exposure before cleaning can be performed from the photosensitive layer side, and the exposure of the image exposure section and the charge removal exposure section can also be performed from the conductive support side.

On the other hand, as the light irradiation step, image exposure, pre-cleaning exposure, and charge elimination exposure are shown. In addition, pre-transfer exposure, pre-exposure of image exposure, and other known light irradiation steps are provided. The body can also be subjected to the light irradiation of the present invention.

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 such an apparatus in the form of a process cartridge. Is also good. The process cartridge has a built-in photoconductor, charging means,
This is one device (part) including an exposure unit, a development unit, a transfer unit, a cleaning unit, a charge removal unit, and the like. There are many shapes and the like of the process cartridge, and a general example is shown in FIG. The process cartridge shown in FIG. 7 has a compact structure including a charging charger (17), a cleaning brush (18), an image exposure unit (19), a developing roller (20) and the like arranged around a photoconductor (16). Having.

[0049]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited by these Examples. In the examples, "parts" are all parts by weight. First, a specific example of synthesis of an otitititanyl phthalocyanine pigment used in an example will be described.

Synthesis Example 52.5 parts of phthalodinitrile and 400 parts of 1-chloronaphthalene were stirred and mixed, and titanium tetrachloride 19
Drop the part. After the completion of the dropwise addition, the temperature was gradually raised to 200 ° C, while maintaining the reaction temperature between 190 ° C and 210 ° C.
The reaction was performed with stirring for 5 hours. After the reaction is completed, allow to cool 1
When the temperature reached 30 ° C., the mixture was filtered while hot, then washed with 1-chloronaphthalene until the powder turned blue, then washed several times with methanol, and further washed several times with hot water at 80 ° C., It was dried to obtain 42.2 parts of a crude titanyl phthalocyanine pigment. 6 parts of the obtained crude titanyl phthalocyanine pigment subjected to the hot water washing treatment was added to 100 g of 96% sulfuric acid at 3 to 5 ° C.
The mixture was stirred, dissolved, and filtered. The obtained sulfuric acid solution was dropped into 3.5 liters of ice water with stirring, and the precipitated crystals were filtered and then washed repeatedly with water until the washing liquid became neutral, to obtain a wet cake of titanyl phthalocyanine pigment. 1,2-dichloroethane 15 was added to this wet cake.
0 parts and stirred at room temperature for 2 hours.
0 parts was further added, and the mixture was stirred and filtered. This was washed with methanol and dried to obtain 4.9 parts of a titanyl phthalocyanine pigment.

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

FIG. 8 shows an X-ray diffraction spectrum of the titanyl phthalocyanine pigment obtained according to the synthesis example. The obtained titanyl phthalocyanine pigment has a main peak of Bragg angle 2θ of at least 9.6 ° ± 0.2 °, 24.0 ° ±
It can be seen that it has crystal forms at 0.2 ° and 27.2 ° ± 0.2 °.

One gram of this TiOPc was weighed and extracted all day and night using 200 g of a methanol solvent.
After cooling, methanol was removed by suction filtration.
It was separated from OPc and dried and solidified to obtain the target impurity.
It had a tan color. This impurity was dissolved in acetonitrile containing 0.1 M tetraethylammonium perchlorate to make a final volume of 25 ml. When this test solution was subjected to cathode running by a polarographic method using a dropping mercury electrode, -0.15 V as shown in FIG.
vs. A reduction wave centered around SEC was observed. Mercury dropping rate (m), respectively measured dropwise time (t), the value of actually measured i _d, L = 0.025 with (3) the result of substituting the expression, I value of this sample 0.60 It turned out to be.

Further, five types of TiOPc were produced by changing the reaction conditions (temperature, time, material purity), sulfuric acid treatment conditions, and methanol washing conditions of the above synthesis examples. All obtained the same result as the X-ray diffraction spectrum shown in FIG.
With respect to the five types of TiOPc thus produced, I values were measured in exactly the same manner. These results are summarized in Table 1.

[0055]

[Table 1]

Examples 1 to 4 and Comparative Examples 1 to 2 An undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following compositions were sequentially applied to an aluminum cylinder, dried and laminated. A photoreceptor was produced. (Undercoat layer coating liquid) Titanium dioxide powder 15 parts Polyvinyl butyral 3 parts Epoxy resin 3 parts 2-butanone 150 parts (Charge generating layer coating liquid) 3 parts of the above-mentioned TiOPc pigment powder (y-1 to y-6) Polyvinyl butyral 2 parts Tetrahydrofuran 50 parts 4-methyl-2-pentanone 90 parts (Coating solution for charge transport layer) Polycarbonate 10 parts Methylene chloride 80 parts Charge transport material of the following structural formula 8 parts

[0057]

Embedded image

Each of the above electrophotographic photosensitive members was mounted in the electrophotographic process shown in FIG. 5 (however, the image exposure light source was set to 780).
In addition, a probe of a surface voltmeter was inserted so that the surface potential (dark portion potential) of the photoconductor immediately before development could be measured. Printing was continuously performed on 10,000 sheets, and the surface potentials of the image-exposed portion and the image non-exposed portion at that time were measured at the initial stage and after 10,000 sheets. Table 2 shows the results.

[0059]

[Table 2]

Examples 5 to 8 and Comparative Examples 3 to 4 Six types of TiOPc (y-1) prepared according to the above-mentioned synthesis examples.
To y-6), after performing solvent treatment using 2-butanone as the treatment solvent, drying and solidifying the solvent as it is, and taking out the TiOPc powder to be referred to as b-1 to b-6. . FIG. 9 shows an X-ray diffraction spectrum of titanyl phthalocyanine b-1. This titanyl phthalocyanine pigment has a main peak of Bragg angle 2θ of at least 7.5 °.
± 0.2 °, 25.3 ° ± 0.2 ° and 28.6 ° ±
It can be seen that it has a crystal form at 0.2 °. Note that similar X-ray diffraction patterns were obtained for b-2 to b-6. A coating solution for an undercoat layer, a coating solution for a charge generation layer, and a coating solution for a charge transporting layer having the following compositions were sequentially applied and dried on an electroformed nickel belt to prepare a laminated photoreceptor.

(Undercoat layer coating liquid) Titanium dioxide powder 5 parts Alcohol-soluble nylon 4 parts Methanol 50 parts Isopropanol 20 parts (Charge generating layer coating liquid) TiOPc pigment powder (b-1 to b-6) 4 parts Polyvinyl Butyral 2 parts Cyclohexanone 50 parts Tetrahydrofuran 100 parts (Coating solution for charge transport layer) Polycarbonate
10 parts Tetrahydrofuran 80 parts Charge transport material of the following structural formula 9 parts

[0062]

Embedded image

Each of the electrophotographic photosensitive members thus constructed is
Installed in the electrophotographic process shown in the figure (however, there was no pre-cleaning exposure), the image exposure light source was a 780 nm semiconductor laser (image writing with a polygon mirror) so that the surface potential of the photoconductor immediately before development could be measured. An electrometer probe was inserted. Printing was continuously performed on 8000 sheets, and the surface potentials of the image-exposed area and the image non-exposed area at that time were measured at the initial stage and after 80 million sheets. Table 3 shows the results.

[0064]

[Table 3]

Examples 9 to 12 and Comparative Examples 5 to 6 Six types of TiOPc (y-1) prepared by the above-mentioned synthesis examples were used.
To y-6), after the solvent treatment was performed using tetrahydrofuran as the treatment solvent, the solvent was dried and solidified as it was, and the TiOPc powder taken out was referred to as a-1 to a-6. FIG. 10 shows an X-ray diffraction spectrum of titanyl phthalocyanine a-1. The titanyl phthalocyanine pigment has at least 9.3 ° ± 0.2 °, 13.1 ° ± 0.2 °, and 26.31 ° main peak at Bragg angle 2θ.
It can be seen that the crystal has a crystal form at 2 ° ± 0.2 °. Note that similar X-ray diffraction patterns were obtained for a-2 to a-6. After anodizing the surface of the aluminum cylinder, a sealing treatment was performed. On this, a charge generation layer coating solution and a charge transport layer coating solution having the following compositions were sequentially applied and dried to form a 0.2 μm charge generation layer and a 20 μm charge transport layer, respectively. A photoreceptor was produced.

(Coating solution for charge generation layer) TiOc pigment powder (a-1 to a-6) 3 parts Polyvinyl butyral 1 part 250 parts cyclohexanone 50 parts cyclohexane (Coating liquid for charge transport layer) 10 parts polycarbonate 80 parts methylene chloride 7 parts of charge transport material of the following structural formula

[0067]

Embedded image

Each of the electrophotographic photosensitive members thus constructed was
After installing in the electrophotographic process cartridge shown in the figure,
Mounted on an image generation device. However, if the image exposure light source is 78
As a semiconductor laser of 0 nm (image writing by a polygon mirror), a probe of a surface voltmeter was inserted so that the surface potential of the photoconductor immediately before development could be measured. 5000 sheets were continuously printed, and the surface potentials of the image-exposed portion and the non-image-exposed portion at that time were measured at the initial stage and after 50 million sheets. Table 4 shows the results.

[0069]

[Table 4]

[0070]

As is apparent from the detailed and concrete description, according to the present invention, the reduction potential is -0.15 ± 0.0 with respect to titanyl phthalocyanine per unit weight.
When the content of the electron-accepting impurity of 5 volts is 0.9 or less as the value defined by the above-mentioned I value, the photoreceptor using titanyl phthalocyanine does not lose high sensitivity and can be charged even when repeatedly used. Provided is a stable electrophotographic photoreceptor that does not cause a decrease and a rise in the residual potential, and a stable electrophotographic method that does not cause a decrease in chargeability and a rise in the residual potential even when repeatedly used without losing high sensitivity Further, a very excellent effect of providing a stable electrophotographic apparatus and a process cartridge for the electrophotographic apparatus which does not cause a decrease in chargeability and an increase in residual potential even when repeatedly used without losing high sensitivity is exhibited. You.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a reduction current value in an electrochemical analysis using a mercury dropping electrode according to the present invention.

FIG. 2 is a cross-sectional view illustrating a layer structure of a photoconductor of the present invention.

FIG. 3 is a cross-sectional view illustrating another layer structure of the photoconductor of the present invention.

FIG. 4 is a sectional view showing still another layer structure of the photoreceptor of the present invention.

FIG. 5 is an example of a schematic diagram illustrating an electrophotographic process and an electrophotographic apparatus of the present invention.

FIG. 6 is another example of a schematic diagram illustrating another electrophotographic process and an electrophotographic apparatus of the present invention.

FIG. 7 is an example of a process cartridge of the present invention.

FIG. 8 is a view showing an X-ray diffraction spectrum of the TiOPc powder in the present invention.

FIG. 9 is a diagram showing an X-ray diffraction spectrum of TiOPc powder in the present invention.

FIG. 10 is a view showing an X-ray diffraction spectrum of the TiOPc powder in the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor 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 photosensitive layer 35 charge generation layer 37 charge transport layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takayoshi Tanno 1-3-6 Nakamagome, Ota-ku, Tokyo Stock inside Ricoh Company (72) Inventor Tamotsu Ariga 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Inside the company Ricoh

Claims (7)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer containing titanyl phthalocyanine on a conductive support, wherein the reduction potential of the titanyl phthalocyanine per unit weight is -0.15 ± 0.1. The content of the electron-accepting impurity of 05 volts is 0.9 at the value defined by the following I value.
An electrophotographic photoreceptor characterized by the following. [Number 1] _{^{I = i d Lm -2/3 t -1/6}} ····· (Equation A) (wherein, i _d is the cathode side of the diffusion limitations in electrochemical analysis using the dropping mercury electrode The current value [μA], L represents the volume (l) of the solvent for dissolving the test substance, m represents the flow rate of mercury (mg / s) at the dropping mercury electrode, and t represents the mercury dropping time (s).) 2. The method according to claim 1, wherein the titanyl phthalocyanine is Cu-Kα.
Angle 2θ in X-ray diffraction spectrum for X-ray
At least 9.6 ° ± 0.2 °, 24.
2. The electrophotographic photoreceptor according to claim 1, wherein the photoreceptor has a crystal form at 0 ° ± 0.2 ° and 27.2 ° ± 0.2 °. 3. The method according to claim 1, wherein the titanyl phthalocyanine is Cu-Kα.
Angle 2θ in X-ray diffraction spectrum for X-ray
At least 7.5 ° ± 0.2 °, 25.
2. The electrophotographic photoreceptor according to claim 1, wherein the photoreceptor has a crystal form at 3 ° ± 0.2 ° and 28.6 ° ± 0.2 °. 4. The method according to claim 1, wherein the titanyl phthalocyanine is Cu-Kα.
Angle 2θ in X-ray diffraction spectrum for X-ray
12. at least 9.3 ° ± 0.2 °;
2. The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor has a crystal form at 1 ° ± 0.2 ° and 26.2 ° ± 0.2 °. 5. An electrophotographic method in which an electrophotographic photosensitive member is repeatedly subjected to at least charge, image exposure, development, transfer, cleaning and charge removal, wherein the electrophotographic photosensitive member contains titanyl phthalocyanine, and The reduction potential is -0.15 ± to titanyl phthalocyanine
An electrophotographic method, wherein the content of 0.05 volt electron accepting impurities is 0.9 or less as defined by the following I value. [Number 2] _{^{I = i d Lm -2/3 t -1/6}} ····· (Equation A) (wherein, i _d is the cathode side of the diffusion limitations in electrochemical analysis using the dropping mercury electrode The current value [μA], L represents the volume (l) of the solvent for dissolving the test substance, m represents the flow rate of mercury (mg / s) at the dropping mercury electrode, and t represents the mercury dropping time (s).) 6. 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 contains titanyl phthalocyanine. The content of the electron-accepting impurities having a reduction potential of -0.15 ± 0.05 volts with respect to the titanyl phthalocyanine per unit weight is 0.9 or less as defined by the following I value: An electrophotographic apparatus, comprising: Equation 3] _{^{I = i d Lm -2/3 t -1/6}} ····· (Equation A) (wherein, i _d is the cathode side of the diffusion limitations in electrochemical analysis using the dropping mercury electrode The current value [μA], L represents the volume (l) of the solvent for dissolving the test substance, m represents the flow rate of mercury (mg / s) at the dropping mercury electrode, and t represents the mercury dropping time (s).) 7. A process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member contains titanyl phthalocyanine, and a reduction potential of the titanyl phthalocyanine per unit weight. Wherein the content of an electron-accepting impurity of -0.15 ± 0.05 volts is 0.9 or less as defined by the I value. Equation 4] _{^{I = i d Lm -2/3 t -1/6}} ····· ( Equation A) (wherein, i _d is the cathode side of the diffusion limitations in electrochemical analysis using the dropping mercury electrode The current value [μA], L represents the volume (l) of the solvent for dissolving the test substance, m represents the flow rate of mercury (mg / s) at the dropping mercury electrode, and t represents the mercury dropping time (s).)