JP2001175010A - Electrophotographic photoreceptor and electrophotographic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic photoreceptor free from image defects, excellent in stability upon potential, having high durability and excellent durability against optical fatigue and an electrophotographic device provided with the electrophotographic photoreceptor. SOLUTION: In the electrophotographic photoreceptor provided with a photosensitive layer containing >=2 kinds of charge generating materials having spectral sensitivity in different spectral regions on a conductive supporting body, an organic sulfur based antioxidant is contained in the photosensitive layer.

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 more particularly, to an electrophotographic photoreceptor which has excellent potential stability upon repeated use and does not generate abnormal images such as black spots, and an electrophotographic photoreceptor using the same. It relates to a photographic device and a process cartridge.

[0002]

2. Description of the Related Art In recent years, electrophotographic photoreceptors using an organic photoconductive material have remarkably advanced from advantages such as productivity and economic efficiency. On the other hand, for such electrophotographic photoconductors, an electrophotographic apparatus using a semiconductor laser as a light source such as a laser printer and a digital copier has emerged, and further, from the viewpoint of common use of photoconductors, a wide spectral sensitivity from a visible to a near infrared region. It is required to have characteristics.

Heretofore, it has been proposed to use two or more kinds of pigments having different spectral sensitivity characteristics as a charge generating material used for such a photoreceptor (JP-A-63-14826).
4, JP-A-01-177553, JP-A-01-2700
No. 50). However, when two or more kinds of pigments are used as the charge generation material, the spectral sensitivity range is widened, but two or more energy levels are generated in the charge generation layer, so that the characteristics of the pigment itself cannot be utilized. From the viewpoint of prescription, it has been difficult to achieve both a rise in the residual potential and a fall in the charging potential.

As a light source used in a digital recording apparatus, a semiconductor laser is used in many cases because of its small size, low cost, simplicity, and the like. It is limited to the near infrared region of 750 nm or more. Therefore, the electrophotographic photosensitive member used in these apparatuses is at least 750 to 850.
It is required to have photosensitivity in the wavelength region of nm.

As an organic photoconductive material satisfying this requirement,
Squarium pigments, phthalocyanine pigments, eutectic complexes of pyrylium dyes with polycarbonate, pyrrolopyrrole pigments, azo pigments, etc. are known.In particular, phthalocyanine pigments have a spectral absorption up to a relatively long wavelength region and have a high light sensitivity. In addition, since various variations can be obtained depending on the type of the central metal and the crystal form, researches on electrophotographic photoreceptors for semiconductor lasers have been actively conducted.

[0006] The phthalocyanine pigments having good sensitivity known so far include ε-type copper phthalocyanine, X-type metal-free phthalocyanine, τ-type metal-free phthalocyanine, vanadyl phthalocyanine, titanyl phthalocyanine and the like. Sensitivity, charging ability, and repetition durability are not yet sufficient, and further improvement has been desired.

[0007] To solve these problems, Japanese Patent Application Laid-Open No.
Japanese Patent Application Publication No. 11 (JP-A) No. 11 attempts to solve the problem of the charged potential by adding an azo compound in addition to the phthalocyanine compound. However, the problem on the image (black spots) is mentioned only at the initial image level. There was still a problem with the durability on the image.

The addition of an organic sulfur compound as an antioxidant to the photosensitive layer is disclosed in Japanese Patent Application Laid-Open No. 01-4494.
5, JP-A-01-200261 and JP-A-06-2739
53, JP-A-07-295250 and the like, the effects of which are to suppress the increase in residual potential and to prevent deterioration of the photoreceptor characteristics due to light irradiation, and do not describe any improvement in the image quality level.

Conventionally, charging by a corona charging method has been used. However, when the electrophotographic process by corona charging is repeated, the ozone concentration increases, and the safety of the use environment is significantly impaired. The contact charging system has been used. The contact charging method produces much less ozone than the corona charging method, so that the problem of environmental safety is improved. However, on the other hand, the problems specific to the contact charging method include problems such as abrasion of the photoconductor, non-uniform charging, and discharge breakdown of the photoconductor caused by directly applying a high voltage to the photoconductor. In this case, unevenness in image density and black spots are more likely to occur than in the corona charging method. Therefore, although a contact charging system is desired from the viewpoint of environmental safety, a durable electrophotographic photoreceptor that can cope with these processes and is durable is strongly demanded.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an electrophotographic photosensitive member using two or more kinds of pigments having different spectral sensitivity characteristics as a charge generating material has no image defect. It is an object of the present invention to provide an electrophotographic photoreceptor that is excellent in electric potential stability, highly durable, and resistant to light fatigue, and an electrophotographic apparatus and a process cartridge equipped with the photoreceptor. Make it an issue.

[0011]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, by including an organic sulfur-based antioxidant in the photosensitive layer, high durability and light The inventors have found that an electrophotographic photosensitive member having resistance to fatigue can be obtained, and have completed the present invention. That is,
According to the present invention, the following inventions are provided. (1) In an electrophotographic photosensitive member having a photosensitive layer containing two or more kinds of charge generating substances having different spectral sensitivity characteristics on a conductive support, an organic sulfur-based antioxidant is contained in the photosensitive layer. An electrophotographic photoreceptor, comprising:

(2) The electrophotographic photoreceptor according to the above (1), wherein the charge generating substances are an asymmetric disazo pigment and a phthalocyanine pigment represented by the following general formula (I). .

[0013]

Embedded image (In the formula, A represents a divalent residue bonded to the nitrogen atom of the azo group by a carbon atom. Cp ₁ and Cp ₂ represent coupler residues having different structures from each other.)

(3) In the electrophotographic photoreceptor described in the above (2), the asymmetric disazo pigment is represented by the following general formula (I)
An electrophotographic photoreceptor characterized by being a compound represented by I) is provided.

[0015]

Embedded image (In the formula, Cp ₁ and Cp ₂ represent coupler residues having different structures from each other.)

(4) The electrophotographic photosensitive member according to (2), wherein the phthalocyanine pigment is a τ-type or X-type non-metallic phthalocyanine pigment.

(5) The electrophotographic photosensitive member according to (1), wherein the organic sulfur-based antioxidant is a compound represented by the following general formula (III).

[0018]

Embedded image (In the formula, n is an integer of 8 to 25.)

(6) In an electrophotographic apparatus having at least a charging means, an exposing means, a reversal developing means, a transferring means and a cleaning means, the electrophotographic photosensitive member mounted on the electrophotographic apparatus is as described in (1) to (6) above. An electrophotographic apparatus characterized in that the electrophotographic photoreceptor is any one of the above.

(7) The electrophotographic apparatus according to (6), wherein the charging means is arranged in contact with the photosensitive member.

(8) An electrophotographic apparatus in which any of the above electrophotographic photosensitive members and at least one means selected from charging means, image exposing means, developing means, transferring means and cleaning means are integrated. A process cartridge which is detachably formed on a main body.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
As described above, the present invention relates to an electrophotographic photosensitive member in which a photosensitive layer containing at least two or more types of charge generating substances having different spectral sensitivity characteristics is provided on a conductive support. By containing an antioxidant, the above-described effects can be obtained, but other additives such as a hindered phenol antioxidant, a phosphorus antioxidant, and a photodegradation inhibitor have no effect at all. Only one effect of improving image quality or preventing light deterioration can be obtained. The reason why the sulfur-based antioxidant is excellent is that it effectively acts on the difference in energy gap caused by using two or more charge generating substances, and has the effect of eliminating and reducing the trap level. Further, it is considered that this is because the compatibility with the binder and the charge transport material used in the photosensitive layer is excellent, and no precipitation occurs.

Further, among the organic sulfur-based antioxidants, it is preferable to use the compound represented by the above general formula (III). It is not clear why the compound of the above general formula (III) is preferable, but it is suggested that the compound of the formula (III) has a suitable compatibility in the photosensitive layer due to having an ester group. On the other hand, if n is less than 8, sublimation tends to occur, and if n is more than 25, compatibility in the photosensitive layer becomes poor, and precipitation occurs.

The organic sulfur-based antioxidant used in the present invention is not particularly limited as long as it is an antioxidant containing a sulfur atom, and various conventionally known ones can be used. Specific examples of the organic sulfur-based antioxidant are shown in Tables 1 and 2, but the present invention is not limited to these.

[0025]

[Table 1]

[0026]

[Table 2]

The charge generating substance used in the present invention comprises two or more kinds of charge generating substances having different spectral sensitivity characteristics. A photoreceptor using two or more kinds of charge generating substances having different spectral sensitivity characteristics is conventionally known, and in the present invention, two or more kinds of charge generating substances having different spectral sensitivity properties can be used in combination. In the present invention, it is preferable to use an extremely sensitive asymmetric disazo pigment represented by the general formula (I) as the charge generating substance. These asymmetric disazo pigments, either by sequentially reacting the corresponding a coupler corresponding to the diazonium salt compound and Cp ₁ or Cp ₂ in two steps, or diazonium salt compounds obtained by the first coupling reaction between Cp ₁ or Cp ₂ Can be obtained by further reacting the remaining coupler.
Tables 3 to 11 show examples of A, Cp ₁ and Cp ₂ of these asymmetric disazo pigments.

[0028]

[Table 3]

[0029]

[Table 4]

[0030]

[Table 5]

[0031]

[Table 6]

[0032]

[Table 7]

[0033]

[Table 8]

[0034]

[Table 9]

[0035]

[Table 10]

[0036]

[Table 11]

Among these asymmetric disazo pigments, A
The compound represented by the above general formula (II) having a fluorenone central skeleton represented by -20 is particularly preferred from the viewpoint of sensitivity and potential stability.

As the phthalocyanine pigment, all phthalocyanine pigments generally used for electrophotographic photoreceptors can be used, but X-type metal-free phthalocyanine pigments and τ-type metal-free phthalocyanine pigments are used. Although the reason for this is not clear, the HOMO level of the metal-free phthalocyanine pigments classified into the X-type and the τ-type is close to the HOMO level of the asymmetric disazo pigment, and is caused by mixing the pigments by interacting. It is considered that the sensitizing effect is effectively generated, and problems such as a residual potential and a decrease in charged potential are less likely to occur in terms of electrostatic characteristics.

The τ-type metal-free phthalocyanine pigment is Cu-
In the X-ray diffraction spectrum using the Kα characteristic X-ray (wavelength: 1.541 °), the main peak at Bragg angle 2θ was 7.
6 °, 9.2 °, 16.8 °, 17.4 °, 20.4
°, 20.9 °, 21.7 °, 27.6 ° (±
0.2 °), which is a metal-free phthalocyanine pigment present in JP-A-58-182639 and JP-A-60-1.
No. 9154 can be obtained.

The X-ray metal-free phthalocyanine pigment is Cu-
In the X-ray diffraction spectrum using the Kα characteristic X-ray (wavelength: 1.541 °), the main peak at Bragg angle 2θ was 7.
5 °, 9.1 °, 16.7 °, 17.3 °, 22.3
°, 28.8 ° (each ± 0.2 °) is a metal-free phthalocyanine pigment, US Pat.
U.S. Pat. No. 3,594,163, JP-B-49-4338,
It can be obtained by the method described in JP-A-60-24389.

Hereinafter, the present invention will be described in relation to the layer constitution of the electrophotographic photosensitive member. FIG. 1 is a cross-sectional view showing an example of the configuration of the electrophotographic photoreceptor of the present invention, in which a photosensitive layer 15 containing two or more kinds of charge generating substances according to the present invention on a conductive support 11.
Are laminated. FIG. 2 is a cross-sectional view showing another configuration example of the electrophotographic photoreceptor of the present invention, which has a configuration in which at least a charge generation layer 17 and a charge transport layer 19 are laminated on a conductive support 11. FIG. 3 is a cross-sectional view showing still another configuration example of the electrophotographic photoreceptor of the present invention. An intermediate layer 13 is provided between a conductive support 11 and a charge generation layer 17. FIG. 4 is a cross-sectional view showing still another configuration example of the electrophotographic photoreceptor of the present invention, in which a protective layer 21 is provided on a charge transport layer 19.

The function-separated type photosensitive member shown in FIGS. 2, 3 and 4 will be described below. Examples of the conductive support 11 include those having conductivity of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, and platinum, tin oxide, and indium oxide. Metal oxides coated on film or cylindrical plastic or paper by vapor deposition or sputtering, or plates made of aluminum, aluminum alloy, nickel, stainless steel, etc., and extruded and drawn out into a tube. Thereafter, a tube or the like that has been subjected to surface treatment such as cutting, superfinishing, and 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 11.

In addition to the above, 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 11 of the present invention. As the conductive powder, carbon black, acetylene black, aluminum, nickel, iron, nichrome, copper, zinc,
Metal powder such as silver, or metal oxide powder such as conductive titanium oxide, conductive tin oxide, and ITO may be used.
In addition, the binder resin used simultaneously, polystyrene,
Styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer,
Polyester, polyvinyl 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- Thermoplastic, thermosetting or photocurable resins such as N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenolic resin, and alkyd resin.
Such a conductive layer can be provided by dispersing the conductive powder and the binder resin in an appropriate solvent, for example, tetrahydrofuran, dichloromethane, 2-butanone, toluene, or the like, and applying the dispersion.

Further, heat shrinkage of a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) or the like containing the conductive powder on a suitable cylindrical substrate. A conductive layer provided with a tube can also be favorably used as the conductive support 11 of the present invention.

The charge generation layer 17 is formed by dispersing at least two or more kinds of charge generation substances, preferably an asymmetric disazo pigment and a phthalocyanine pigment, in a binder resin as required. As the charge generating substance, titanyl phthalocyanine, vanadyl phthalocyanine, copper phthalocyanine, hydroxygallium phthalocyanine, phthalocyanine-based pigments such as metal-free phthalocyanine, monoazo pigments, bisazo pigments, asymmetric disazo pigments, trisazo pigments, tetraazo pigments, pyrrolopyrrole pigments, anthraquinone pigments , Perylene pigments, polycyclic quinone pigments, indigo pigments, squarium pigments and other known materials can be used, but it is preferable to use asymmetric disazo pigments and phthalocyanine pigments. That is, it is known that asymmetric disazo pigments have high sensitivity in the visible region, and phthalocyanine pigments have high sensitivity in the near-infrared region. Further, both have good dispersibility and are easy to obtain an interaction (sensitizing effect). There are things. Accordingly, the charge generation layer 17 is obtained by dispersing these components in an appropriate solvent using a ball mill, an attritor, a sand mill, ultrasonic waves, or the like, applying the dispersion on the conductive support 11 or the intermediate layer 13, and drying the dispersion. It is preferable to form with.

The binder resin used for the charge generation layer 17 includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl formal, polyvinyl butyral,
Polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone and the like can be used. As the binder resin used for the charge generation layer 17, polyvinyl butyral is preferably used.

The weight ratio of the asymmetric disazo pigment to the phthalocyanine pigment is preferably from 1/5 to 5/1. As a result, whether the phthalocyanine content is high or low, the panchromaticity of sensitivity is impaired, and the chargeability during electrostatic fatigue and the chargeability during light irradiation are reduced. The amount of the binder resin is suitably from 10 to 500 parts by weight, preferably from 25 to 300 parts by weight, per 100 parts by weight of the charge generating substance.

The thickness of the charge generation layer is 0.01 to 5 μm, preferably 0.1 to 2 μm. Solvents used in preparing the charge generating layer coating liquid include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane,
Monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like can be mentioned. As a method of applying the coating solution, a method such as a dip coating method, a spray coat, a bead coat, a nozzle coat, a spinner coat, and a ring coat can be used.

The charge transporting layer 19 can be formed by dissolving or dispersing a charge transporting substance and a 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 materials include a hole transport material and an electron transport material. As the charge transport material, for example,
Chloranil, bromoanil, tetracyanoethylene,
Tetracyanoquinodimethane, 2,4,7-trinitro-
9-fluorenone, 2,4,5,7-tetranitro-9
Fluorenone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2
-B] Electron accepting substances such as 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, o-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives,
Known materials such as a butadiene derivative, a pyrene derivative, a bisstilbene derivative, an enamine derivative, and other polymerized hole transport substances are exemplified.

Examples of the binder resin used for the charge transport layer include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyvinylidene chloride, polyarylate, and 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, alkyd resin, 15825
No. 0, JP-A-6-51544, and thermoplastic or thermosetting resins such as various polycarbonate copolymers.

The amount of the charge transporting substance is 20 to 300 parts by weight, preferably 40 to 15 parts by weight, per 100 parts by weight of the binder resin.
0 parts by weight is suitable. The charge transport layer has a thickness of 5 to 5.
Preferably, the thickness is about 50 μm. As the solvent used here, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, dichloromethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.

In the present invention, a leveling agent may be added to the charge transport layer 19. 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 can be used. ~
One part by weight is suitable.

The organic sulfur-based antioxidant shown in the present invention can be added to the charge generation layer and / or the charge transport layer in the case of the function-separated type photoreceptor shown in FIGS. 2, 3 and 4. . When added to the charge generation layer, charge generation material 1
It is preferable to add 0.5 to 10 parts by weight to 00 parts by weight.
It is preferable to add 0.1 to 5 parts by weight to 00 parts by weight. If the amount is less than this, the effect cannot be sufficiently exhibited, and if the amount is more than this, adverse effects such as an increase in residual potential occur.
Further, other antioxidants may be used in combination. As such an antioxidant, an antioxidant such as a hindered phenol compound, a phosphorus compound, a hindered amine compound, a pyridine derivative, a piperidine derivative, and a morpholine derivative can be used, and among them, a hindered phenol compound is used in combination. Is preferred. The organic sulfur-based antioxidant used in the present invention is added to the photosensitive layer in the case of the single-layer type shown in FIG. Here, the addition amount of the organic sulfur-based antioxidant is preferably 0.5 to 20 parts by weight based on 100 parts by weight of the charge generating substance, and 0.2 to 10 parts by weight based on 100 parts by weight of the charge transporting substance. Can be used.

Further, the intermediate layer 13 may be added with a fine powder pigment of a metal oxide such as titanium oxide, aluminum oxide, silica, zirconium oxide, tin oxide, indium oxide or the like for preventing moire and reducing residual potential. Good. Further, as the intermediate layer 13, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, a titanyl chelate compound, a zirconium chelate compound, a titanyl alkoxide compound, and an organic titanyl compound can be used.
These intermediate layers 13 can be formed using an appropriate solvent, dispersion, and coating method as in the above-described photosensitive layer. In addition, the intermediate layer 13 is formed by providing Al ₂ O ₃ by anodic oxidation, an organic substance such as polyparaxylylene, SiO ₂ , S
Those provided with an inorganic substance such as nO ₂ , TiO ₂ , ITO, CeO ₂ by a vacuum thin film forming method can also be used favorably. The thickness of the intermediate layer 13 is suitably from 0 to 10 μm.

The protective layer 21 is provided for the purpose of improving the durability of the photoreceptor. Materials used for the protective layer 21 include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, and the like. Phenolic 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
Resins such as 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, titanium oxide, tin oxide,
Inorganic materials such as potassium titanate can be added

As a method for forming the protective layer 21, a usual coating method can be used. The thickness of the protective layer 21 is suitably from 0.1 to 10 μm. In addition to the above, known materials such as aC and a-SiC formed by a vacuum thin film manufacturing method can be used as the protective layer 21. In the present invention, another intermediate layer (not shown) can be provided between the photosensitive layer 15 and the protective layer 21. The other intermediate layer generally uses a resin as a main component. Examples of these resins include polyamide, alcohol-soluble nylon resin, water-soluble butyral resin, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the another intermediate layer, a normal coating method can be used as described above. Incidentally, the film thickness is suitably 0.05 to 2 μm.

The electrophotographic apparatus according to the present invention has at least charging, exposure, reversal development, transfer, and cleaning means, and any means may be a commonly used means. As the charging method, for example, any of corotron using corona discharge, scorotron charging, and contact charging using a conductive roller or a brush may be used. As a developing method, a general method of developing a magnetic or non-magnetic one-component developer or a two-component developer in a contact or non-contact manner is used, and in each case, a reversal development for developing a light potential portion is used. . As a transfer method, any of a method using corona discharge, a method using a transfer roller, and the like may be used. As a cleaning method, blade cleaning is generally often used, but the developing unit may be used as a cleaning step. In addition, as an electrophotographic device,
A plurality of components such as the above-described electrophotographic photosensitive member and the developing and cleaning processes may be integrally connected as an apparatus unit, and this unit may be configured to be detachable from the apparatus main body. For example, as shown in FIG.
In addition, in the clockwise direction along the circumference, the charge removing exposure unit 32, the charging charger 33, the image exposure unit 35, the developing unit 36,
An electrophotographic apparatus in which the transfer / separation unit 40 and the cleaning unit 44 are sequentially provided can be provided. In an electrophotographic apparatus having a contact charging step as shown in the present invention, the effect of the present invention is remarkably exhibited. The reason for this is as described above, but it is also conceivable that the influence of contamination (volatile gas or bleed-out compound generated from the molded member) from the contact charging member is further reduced. The process cartridge of the present invention includes the electrophotographic photosensitive member according to the present invention, a charging unit, an image exposure unit,
At least one means selected from the group consisting of a developing means, a transfer means and a cleaning means is formed integrally and detachably on the main body of the electrophotographic apparatus. The effect of the present invention is remarkably exhibited also in such a process cartridge.

[0060]

Next, the present invention will be described with reference to examples. The parts and percentages shown below are based on weight. Example 1 70 parts of titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd.), 15 parts of alkyd resin (Beccolite M6401-50-S (solid content: 50%): manufactured by Dainippon Ink and Chemicals, Inc.), melamine resin (Super A mixture consisting of 10 parts of Becamine L-121-60 (solid content: 60%) (manufactured by Dainippon Ink and Chemicals, Inc.) and 100 parts of methyl ethyl ketone was dispersed in a ball mill for 72 hours to prepare an intermediate layer coating liquid. This was applied on an aluminum drum having a diameter of φ30 mm and a length of 340 mm, and dried at 130 ° C. for 20 minutes to produce an intermediate layer having a thickness of 3 μm. Next, 4.0 parts of a symmetric disazo pigment represented by the following structural formula (IV) and 3.0 parts of a trisazo pigment represented by the following structural formula (V) were combined with polyvinyl butyral (Eslec BM).
-S: Sekisui Chemical Co., Ltd.) 1.4 parts of cyclohexanone 15
The mixture was added to the resin solution dissolved in 0 parts and dispersed in a ball mill for 72 hours. After dispersion is completed, cyclohexanone 210
The mixture was dispersed for 3 hours to prepare a charge generation layer coating solution. This was applied onto the above-mentioned intermediate layer and dried at 130 ° C. for 10 minutes to produce a charge generation layer having a thickness of 0.20 μm.

[0061]

Embedded image

[0062]

Embedded image

Next, 7.5 parts of a charge transport material represented by the following structural formula (VI), 10 parts of polycarbonate (Z type: viscosity average molecular weight of 40,000), 0.07 parts of the organic sulfur compound shown in S-1 and silicone oil (K
F-50: manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in 100 parts of toluene to prepare a charge transport layer coating solution. This was applied on the charge generation layer and dried at 135 ° C. for 25 minutes to form a charge transport layer having a thickness of 28 μm. Thus, the electrophotographic photoreceptor of Example 1 was obtained.

[0064]

Embedded image

Example 2 In Example 1, the organic sulfur-based compound was changed to Exemplified Compound N
o. An electrophotographic photoreceptor of Example 2 was produced in the same manner as in Example 1 except that (III) -5 was used.

Comparative Example 1 An electrophotographic photosensitive member of Comparative Example 1 was prepared in the same manner as in Example 1 except that no organic sulfur compound was added.

Comparative Example 2 In the same manner as in Example 1, except that 2,6-di-tert-butyl-p-cresol, which is a phenolic antioxidant, was used in place of the organic sulfur compound. An electrophotographic photosensitive member of Comparative Example 2 was produced.

The electrophotographic photoreceptors of Examples 1 and 2 and Comparative Examples 1 and 2 obtained as described above were evaluated using a digital copying machine, Imagio MF250M (manufactured by Ricoh). The evaluation of fatigue was performed by using a photoreceptor under a white fluorescent
Left at the position x for 60 minutes, and the unexposed portion potential VD (-V)
Was evaluated from the change.

[0069]

ΔVD = VD (initial) −VD (after light irradiation) Note that the potential is the potential of the unexposed portion in a state where the light amount is halved by attaching an ND0.5 filter to the exposed portion and the electrometer is provided at the developing position. VD (-V) was measured. The initial VD was adjusted to about -900 V by adjusting the voltage applied to the charging member. As the image evaluation, temperature 25 ° C / humidity 50% R
In an environment of H, 50,000 sheets of chart paper with a black solid portion of 5% were continuously used using recording paper, and 0.1% was printed on the white portion of the recording paper.
The number of copies when black spots of not less than 1 mm / cm 2 or more and the presence or absence of an abnormal image such as a decrease in density other than the black spots and background stains were measured. Table 12 shows the results.

[0070]

[Table 12]

Example 3 An electrophotographic photoreceptor of Example 3 was produced in the same manner as in Example 1, except that the trisazo pigment was changed to a τ-type non-metallic phthalocyanine pigment which is a phthalocyanine pigment.

Example 4 In Example 3, the organic sulfur-based compound was changed to the exemplified compound N
o. An electrophotographic photoreceptor of Example 4 was produced in the same manner as in Example 3 except that (III) -6 was used.

Comparative Example 3 An electrophotographic photosensitive member of Comparative Example 3 was prepared in the same manner as in Example 3 except that no organic sulfur compound was added.

Comparative Example 4 The procedure of Example 3 was repeated, except that 2,6-di-tert-butyl-p-cresol, a phenolic antioxidant, was used in place of the organic sulfur compound. An electrophotographic photosensitive member of Comparative Example 4 was produced.

The electrophotographic photosensitive members of Examples 3 and 4 and Comparative Examples 3 and 4 obtained as described above were evaluated in the same manner as in Example 1. Table 13 shows the results.

[0076]

[Table 13]

Example 5 Example 1 was the same as Example 1 except that the symmetric disazo pigment was replaced by the following structural formula (VII), which is an asymmetric disazo pigment, and the trisazo pigment was replaced by a τ-type metal-free phthalocyanine, which was a phthalocyanine pigment. Thus, an electrophotographic photosensitive member of Example 5 was produced.

[0078]

Embedded image

Examples 6 to 16 The electrophotographic photosensitive members of Examples 6 to 16 were prepared in the same manner as in Example 5 except that the asymmetric disazo pigment, the phthalocyanine pigment and the organic sulfur compound in Example 5 were changed as shown in Table 14. The body was made.

[0080]

Embedded image

[0081]

[Table 14]

Comparative Examples 5 to 16 Comparative Example 5 was carried out in the same manner as in Example 5 except that the additives represented by Table 15 and Table 16 were used as the asymmetric disazo pigment, the phthalocyanine pigment, and the organic sulfur compound in Example 5. ~ 16 electrophotographic photosensitive members were produced.

[0083]

[Table 15]

[0084]

[Table 16]

The electrophotographic photosensitive member produced as described above was evaluated in the same manner as in Example 1. The results are shown in Tables 17 and 18.

[0086]

[Table 17]

[0087]

[Table 18]

[0088]

As described above, the first aspect of the present invention relates to a photosensitive layer containing two or more kinds of charge generating substances having spectral sensitivity characteristics in different spectral regions, wherein the photosensitive layer contains an organic sulfur-based antioxidant. According to this, it effectively acts on a difference in energy gap caused by using two or more kinds of charge generating substances, and as shown in the above table, there is no deterioration due to light, and black spots and abnormal images A highly durable electrophotographic photosensitive member free of generation can be obtained.

According to a second aspect of the present invention, in the above structure, the charge generation material is an asymmetric disazo pigment and a phthalocyanine pigment represented by the general formula (I). Those having wide spectral sensitivity characteristics and high sensitivity can be obtained.

The invention according to claim 3 is characterized in that, in the above constitution, the asymmetric disazo pigment is a compound represented by the general formula (II), and this compound has sensitivity and potential stability among the asymmetric disazo pigments. It is particularly preferable also from the point of view.

According to a fourth aspect of the present invention, in the above structure, the phthalocyanine pigment is a τ-type or X-type non-metallic phthalocyanine pigment.
A sensitizing effect caused by mixing the pigment can be effectively generated, and also the residual potential and
Problems such as lowering of the charged potential hardly occur.

The invention of claim 5 is characterized in that, in the above constitution, the organic sulfur-based antioxidant is a compound represented by the general formula (III), and this compound is appropriately compatible in the photosensitive layer. Therefore, favorable results can be obtained in terms of the resistance of the photosensitive member to light degradation and the durability of images.

The invention according to claim 6 is an electrophotographic apparatus equipped with the electrophotographic photoreceptor having the above-mentioned constitution, wherein the electrophotographic photoreceptor has an excellent action in a wavelength region from a visible region to a near infrared region. It is possible to obtain a durable image having excellent resistance to light fatigue and no black spots or abnormal images.

According to a seventh aspect of the present invention, in the above electrophotographic apparatus, there is provided an apparatus having a contact charging means. By mounting the highly durable photosensitive member according to the present invention as described above, a high voltage is directly applied to the photosensitive member. Even with this, it is possible to obtain an excellent deterrent effect in preventing the occurrence of image density unevenness and black spots.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a layer configuration of an electrophotographic photosensitive member.

FIG. 2 is a schematic cross-sectional view illustrating the layer configuration of the electrophotographic photosensitive member.

FIG. 3 is a schematic cross-sectional view illustrating a layer configuration of the electrophotographic photosensitive member.

FIG. 4 is a schematic cross-sectional view illustrating a layer configuration of the electrophotographic photosensitive member.

FIG. 5 is a schematic configuration diagram illustrating an example of an electrophotographic apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Conductive support 13 Intermediate layer 15 Photosensitive layer 17 Charge generation layer 19 Charge transport layer 21 Protective layer photoconductor 31 Photoconductor 32 Static elimination exposure part 33 Charger 35 Image exposure part 36 Developing unit 40 Transfer / separation unit 44 Cleaning unit

Claims (8)

[Claims] 1. An electrophotographic photosensitive member comprising a conductive support and a photosensitive layer containing two or more kinds of charge generating substances having different spectral sensitivity characteristics, wherein the photosensitive layer contains an organic sulfur-based antioxidant. An electrophotographic photoreceptor characterized in that: 2. The electrophotographic photoreceptor according to claim 1, wherein said two or more kinds of charge generating substances are represented by the following general formula (I):
An electrophotographic photosensitive member comprising an asymmetric disazo pigment and a phthalocyanine pigment represented by the formula: Embedded image (In the formula, A represents a divalent residue bonded to the nitrogen atom of the azo group by a carbon atom. Cp ₁ and Cp ₂ represent coupler residues having different structures from each other.) 3. The electrophotographic photoreceptor according to claim 2, wherein the asymmetric disazo pigment is a compound represented by the following general formula (II). Embedded image (In the formula, Cp ₁ and Cp ₂ represent coupler residues having different structures from each other.) 4. The electrophotographic photoreceptor according to claim 2, wherein said phthalocyanine pigment is a τ-type or X-type metal-free phthalocyanine pigment. 5. The electrophotographic photosensitive member according to claim 1, wherein the organic sulfur-based antioxidant is a compound represented by the following general formula (III). Embedded image (In the formula, n is an integer of 8 to 25.) 6. An electrophotographic apparatus having at least a charging unit, an exposure unit, a reversal developing unit, a transfer unit and a cleaning unit, wherein the electrophotographic photosensitive member mounted on the electrophotographic apparatus is any one of claims 1 to 5. An electrophotographic apparatus, comprising: 7. The electrophotographic apparatus according to claim 6, wherein
An electrophotographic apparatus, wherein the charging unit has a configuration in which the charging unit is arranged in contact with a photoconductor. 8. The electrophotographic photosensitive member according to claim 1, and at least one unit selected from a charging unit, an image exposing unit, a developing unit, a transferring unit, and a cleaning unit. A process cartridge formed and detachable from an electrophotographic apparatus main body.