JP2000267323A - Electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] By laminating an undercoat layer unaffected by changes in temperature and humidity and a uniform charge generation layer free of coating film defects, it has stable electric characteristics, and has background stains and black spots. The present invention provides an electrophotographic photoreceptor excellent in durability, which does not cause image defects such as, for example, and does not cause a decrease in charging potential or a rise in residual potential even when used repeatedly. SOLUTION: In an electrophotographic photoconductor in which an undercoat layer and a photosensitive layer are sequentially provided on a conductive support, the undercoat layer contains an organometallic compound, a binder resin and a titanium oxide pigment, Further, the photosensitive layer contains a titanium-based phthalocyanine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor (hereinafter, also simply referred to as "photoreceptor"), and more particularly, to an electrophotographic photoreceptor for improving an undercoat layer and a photosensitive layer.

[0002]

2. Description of the Related Art An electrophotographic photoreceptor basically has a structure in which a photosensitive layer is provided on a conductive support (hereinafter, simply referred to as a "support"). Between the support and the photosensitive layer, between the support and the photosensitive layer, for the purpose of improving the coating uniformity of the photosensitive layer and the photosensitive layer, covering defects on the surface of the support, preventing charge injection from the support to the photosensitive layer, and the like. It has been practiced to provide an undercoat layer in which an inorganic pigment is dispersed.

[0003] The undercoat layer is required to have the above-mentioned performance, and at the same time, it is necessary not to degrade the electrophotographic characteristics by providing the undercoat layer. It is required that electrical characteristics such as charge potential, residual potential and sensitivity are stable.

In order to prevent laser light interference,
Alternatively, when an inorganic pigment is dispersed in the undercoat layer in order to adjust the electric resistance of the undercoat layer, a smooth surface property free from unevenness defects and pinhole defects due to aggregation of the inorganic pigment is required.

On the other hand, in an electrophotographic process, when a so-called contact charging system is applied, in which a charged member to which a voltage is applied is brought into direct contact with the surface of the photoreceptor to uniformly charge the surface of the photoreceptor, an undercoat layer is used. Must have a withstand voltage with respect to the charging voltage and do not cause image defects due to electrical breakdown.

As the resin used for such an undercoat layer, for example, a cellulose resin, a polyamide resin,
Polymer materials such as polyvinyl alcohol-based resins and polyester-based resins are known. However, when used alone as it is, the electrical insulation is high, causing a decrease in sensitivity and an increase in the residual potential. Particularly when used in a low-temperature and low-humidity environment, the electric resistance of the undercoat layer becomes extremely high. As a result, a reduction in image density or a ghost (afterimage defect) is caused. In addition, in order to sufficiently cover defects on the surface of the support,
Alternatively, when the thickness of the undercoat layer is increased for the purpose of adjusting the withstand voltage, the sensitivity also decreases and the residual potential increases similarly, so that the resin cannot be used alone for practical purposes.

As a method for preventing the occurrence of these problems and adjusting the electric resistance of the undercoat layer, for example, A
1, metal powder such as Ni, indium oxide, tin oxide,
A method of containing a conductive metal oxide such as zinc oxide, a method of containing a conductive polymer such as polypyrrole and polyaniline, and a method of containing an ionic conductive resin represented by polyamide have been proposed.

However, when dispersing metal powder or conductive metal oxide, it is technically difficult to finely disperse and uniformly disperse the metal powder or conductive metal oxide, so that a coating defect due to agglomeration of particles tends to occur. In addition, when a conductive polymer is used, problems remain in solubility, pot life of a coating solution, and the like. Furthermore, in the case of using a solvent-soluble polyamide resin as the ion conductive resin, the initial electrical characteristics can be appropriately adjusted because the electric resistance is relatively low as compared with other resins, but the hygroscopicity is extremely high, In particular, it is easily affected by atmospheric humidity, and environmental stability is a major problem.

On the other hand, in a layer structure in which a photosensitive layer is provided on a support via an undercoat layer, the photosensitive layer is often formed by a dip coating method, a spray coating method, or the like. Depending on the type of the solvent used, the undercoat layer may be dissolved or deteriorated, causing potential unevenness and image unevenness due to unevenness in the coating film of the charge generating layer.

On the other hand, in the electrophotographic application apparatus, with the development of digitization technology in recent years, laser printers,
2. Description of the Related Art Digital recording apparatuses such as a laser facsimile and a digital copying machine have been widely put into practical use. Many of these devices employ a latent image forming method of irradiating a photoconductor with a semiconductor laser beam. However, in order to reduce the size and cost of the device, a light source having an oscillation wavelength in a long wavelength region of 750 nm or more is used. Is used, the photoreceptor used is 750 to 8
High sensitivity is required in a long wavelength region of 50 nm. Due to such demands for photosensitivity characteristics, photoconductive materials used for photoconductors in recent years include conventional Se and Cd
Instead of inorganic pigments such as S and ZnO, organic materials such as squarium pigments, phthalocyanine pigments, pyrylium pigments, perylene pigments, and azo pigments are used.

In particular, phthalocyanine pigments have high sensitivity characteristics up to a relatively long wavelength region and exhibit various photoconductive characteristics depending on the type of central metal and crystal form thereof. Has been widely adopted. For example, divalent metal phthalocyanines include ε-type copper phthalocyanine and γ-type metal-free phthalocyanine, and trivalent and tetravalent metal phthalocyanines include chloroaluminum phthalocyanine, chloroaluminum phthalocyanine chloride, titanium phthalocyanine, and chloromethane. Indium phthalocyanine and the like; and further, Ti, Sn, Pb
And various phthalocyanines containing In addition, these phthalocyanines are subjected to a solvent or solvent vapor treatment, or a sublimation treatment to increase the sensitivity, or by introducing or derivatizing various substituents, and further perform dimerization, trimerization, or the like to increase the wavelength, Methods for increasing the sensitivity have been reported.

However, the phthalocyanine conventionally reported is, for example, a Bragg angle 2θ = 9.6 in an X-ray diffraction spectrum using Cu-Kα characteristic X-ray proposed in Japanese Patent Application Laid-Open No. Sho 64-17066. ± 0.2 °
And 27.3 ± 0.2 °, showing a strong peak. This crystalline phthalocyanine is a strongly agglomerated massive particle,
In many cases, many impurities are incorporated between the particles, and the crystal diameter grows due to crystal growth during crystallization, and the charge generation layer formed by using this has problems in dispersibility and coating uniformity. there were. In addition, problems such as charge reduction and repeated fatigue occur due to aggregated particles and residual impurities,
Insufficient light absorption characteristics cause a decrease in carrier generation efficiency of the charge generation layer and a decrease in carrier injection efficiency to the charge transport layer, resulting in defects such as background stain on images and black spots. Had.

[0013]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to form an undercoat layer which is not affected by changes in temperature and humidity, thereby providing an electrophotographic device having stable electric characteristics. To provide a photoreceptor for use.

Another object of the present invention is to form a uniform charge-generating layer free from coating film defects by using a pigment for a charge-generating layer having good dispersibility, thereby reducing background contamination and black spots. An object of the present invention is to provide an electrophotographic photosensitive member that does not cause image defects.

Still another object of the present invention is to laminate the undercoat layer and the charge generation layer so that the charge potential does not decrease and the residual potential does not increase even when used repeatedly. Another object of the present invention is to provide an electrophotographic photosensitive member having excellent durability.

[0016]

Means for Solving the Problems In order to solve the above-mentioned problems, an electrophotographic photoreceptor of the present invention comprises an electrophotographic photosensitive member comprising a conductive support, on which an undercoat layer and a photosensitive layer are sequentially provided. In the body, the undercoat layer contains an organometallic compound, a binder resin and a titanium oxide pigment, and the photosensitive layer contains a titanium-based phthalocyanine.

In the present invention, the organometallic compound is preferably a metal complex or a metal salt of an aromatic carboxylic acid.

It is preferable that the binder resin is selected from the group consisting of a styrene resin having a hydroxyl group, a copolymer with a different resin, and derivatives thereof.

Further, it is preferable that the titanium oxide pigment is surface-treated with a silane coupling agent.

In the photoreceptor of the present invention, the photosensitive layer is
It is also preferable that the charge generation layer is a stacked type including a charge generation layer and a charge transport layer, and the titanium-based phthalocyanine is contained in the charge generation layer.

Further, it is preferable that the titanium-based phthalocyanine contained in the photosensitive layer is non-crystalline particles having oxytitanium or titanium halide in the central nucleus and exhibiting no strong X-ray diffraction peak.

Further, it is preferable that the titanium phthalocyanine has a sulfate ion concentration of 2000 ppm or less.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail. The photoreceptor has a basic structure in which a photosensitive layer is provided on a conductive substrate, and generally includes a laminated photoreceptor in which the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer.
There is a single layer type photoreceptor having a single layer structure having both functions of charge generation and charge transport in one layer, but in the present invention, any structure may be used. Hereinafter, the photoconductor of the present invention will be described in detail by taking a laminated photoconductor as an example.

The support used in the photoreceptor of the present invention includes metals such as aluminum, nickel, chromium, and stainless steel, and aluminum, titanium, nickel, chromium, stainless steel, tin oxide, indium oxide, and the like.
Examples include a plastic film provided with a thin film of ITO or the like, or paper or plastic coated or immersed with a conductivity-imparting agent. These supports are drum-shaped,
It is used in the form of a sheet, plate, or the like, but is not limited thereto. Furthermore, if necessary, the surface of the support may be subjected to an oxidizing treatment, a chemical treatment, a coloring treatment, or an irregular reflection treatment by sandblasting or the like.

Next, the undercoat layer in the present invention will be described. The undercoat layer of the photoreceptor of the present invention is formed using a binder resin. As the binder resin, the following structural formula (A): A styrene resin having a hydroxyl group as shown by is preferred. Or a copolymer with a different resin, for example, methyl methacrylate resin, hydroxyethyl methacrylate resin, hydroxyethyl acrylate resin, butyl acrylate resin, styrene resin, phenylmaleide resin, maleic acid resin, fumaric acid resin Or a derivative such as a sulfonated, tert-butylated, styrenated, aminated, or brominated product.

The undercoat layer according to the present invention contains an organometallic compound. As such an organometallic compound, a metal complex or a metal salt of an aromatic carboxylic acid is preferable. As the aromatic carboxylic acid, for example, benzene having a carboxyl group, naphthalene, an aromatic ring such as anthracene, or an aromatic heterocyclic ring such as carbazole can be mentioned, and these are, as a substituent, an oxygen atom in the group. It may have an alkyl group, an aryl group, an aralkyl group, a hydroxyl group, a nitro group, a cyano group, a halogen atom, or the like which may be possessed. Further, the metal forming the metal complex or metal salt of the aromatic carboxylic acid is not particularly limited, but Al, Ni, Sn, Zn, Cr, C
o, Fe and the like. As an example of a metal complex of an aromatic carboxylic acid, bis (3,5-di-tert-) synthesized from sodium tert-butylsalicylate zinc chloride is used.
The structural formula (B) of zinc butylsalicylate is shown below.

In the case where the conductivity of the undercoat layer is adjusted by mixing a conductive polymer such as polyaniline or polypyrrole, or in the case of adjusting the conductivity by mixing an ionic conductive resin such as a polyamide resin, the influence of a change in humidity may be caused. In a low humidity environment, the conductivity is greatly reduced, causing a decrease in sensitivity. However, in the undercoat layer of the present invention, since the conductivity is generated by the ions generated by the dissociation of the metal salt, the undercoat layer is hardly affected by humidity and the like, and stable electric characteristics can be obtained with respect to environmental changes. . Al, Ni
When the conductivity is adjusted with a metal powder such as, for example, indium oxide, tin oxide, zinc oxide, and a conductive inorganic pigment such as carbon black, coating film defects due to agglomeration of particles are likely to occur. Since the undercoat layer is of a melting type, a uniform and smooth undercoat layer can be formed. Further, the undercoat layer according to the present invention can be made thicker even when the film thickness is set to, for example, 5 to 10 μm, since the sensitivity does not decrease and the residual potential does not increase. As a result, the surface defects of the support can be sufficiently covered, and at the same time, the withstand voltage becomes high, so that the dielectric breakdown can be prevented even in the electrophotographic apparatus to which the contact charging system is applied.

In the present invention, the amount of the organometallic compound added to the binder resin is preferably 0.1 to 30.
%, More preferably 1 to 10% by weight, but can be appropriately determined depending on the electric resistance required for the undercoat layer and the compatibility with the binder resin.

Further, the undercoat layer according to the present invention contains a titanium oxide pigment. When the photoreceptor is used in an electrophotographic apparatus that uses laser light as a light source, it is necessary to prevent printing defects caused by interference between incident light and reflected light. For example, inorganic pigments such as metal oxides and metal nitrides Is preferable, and among them, a titanium oxide pigment is effective in terms of hiding properties and refractive index.

As the titanium oxide pigment in the present invention,
It is preferable to use one that has been surface-treated with a silane coupling agent. Depending on the binder resin and the solvent, minute defects due to aggregation of the pigment may occur. Therefore, the pigment surface is treated with a silane coupling agent to improve dispersibility. As the silane coupling agent used in the present invention, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane,
γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, β-3,4-epoxycyclohexyltrimethoxysilane and the like can be mentioned. The amount of the silane coupling agent to be applied to the titanium oxide pigment is preferably 0.5 to 5% by weight.

The average particle size of the inorganic pigment such as a titanium oxide pigment is preferably 0.5 μm or less. If it exceeds 0.5 μm, the particles tend to agglomerate, causing image defects such as black spots and background stains. In order to cause the scattering of laser light, the particle diameter is preferably about half of the light wavelength (0.4 to 0.8 μm).
Use about particles.

In the present invention, the amount of the inorganic pigment such as a titanium oxide pigment is preferably 50 to 300% by weight based on the binder resin. If the amount is less than 50% by weight, the light scattering effect is insufficient. On the other hand, if the amount exceeds 300% by weight, image defects due to charge reduction occur, and at the same time, aggregation and sedimentation of the pigment in the coating liquid are apt to occur. Problems arise.

When the photosensitive layer is applied by a dipping method or a spray method after the formation of the undercoat layer, the undercoat layer is dissolved or deteriorated depending on the kind of the solvent used for the photosensitive layer coating solution. In some cases, a resin having a functional group that causes a crosslinking reaction with a hydroxyl group, for example, a melamine resin, a benzoguanamine resin, a urea resin, an isocyanate resin, an epoxy resin, a phenol resin, etc. It is preferable to mix an organic acid cross-linking agent such as an acid, trimellitic acid, pyromellitic acid, and maleic acid to make it insoluble in a solvent. Further, for the purpose of adjusting the plasticity of the undercoat layer, for example, polyvinyl butyral resin, polyvinyl alcohol resin, polyvinyl acetate resin, polyacrylate resin, polymethacrylate resin,
A thermoplastic resin such as a polyester resin, a polyamide resin, a polystyrene resin, and a polycarbonate resin may be mixed and used.

Next, the charge generation layer in the present invention will be described. In the present invention, as a photoconductive material contained in the charge generation layer, titanium-based phthalocyanine, preferably non-crystalline titanium having oxytitanium or titanium halide in the central nucleus, and showing no strong X-ray diffraction peak Phthalocyanine is used. Titanium-based phthalocyanine is a phthalocyanine containing titanium metal, oxygen or chlorine (or the like) as a central nucleus,
For example, oxytitanium phthalocyanine (TiOP
c) and titanium phthalocyanine dichloride (TiCl
₂ Pc), or a phthalocyanine in which one or more benzene rings are chlorinated, and a solvent-soluble phthalocyanine in which one or two or more benzene rings are tert-butylated. Further, the above-mentioned phthalocyanine may be dimerized, trimerized, or the like.

The method of synthesizing phthalocyanine includes a phthalodinitrile method in which phthalodinitrile and a metal chloride are heated and melted or heated in the presence of an organic solvent, and a phthalic anhydride in which phthalic anhydride is heated and melted in the presence of urea and a metal chloride in the presence of an organic solvent. Examples include, but are not limited to, a Weyler method in which heating is performed below, a method in which cyanobenzamide is reacted with a metal salt at a high temperature, and a method in which dilithium phthalocyanine is reacted with a metal salt.

The phthalocyanine after synthesis is washed with alkali, methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran, pyridine, quinoline, toluene, xylene, chloroform, carbon tetrachloride, dichloromethane, dichloroethane, trichloropropane, dimethylformamide and the like. It is preferable to remove unreacted substances and ionic impurities by sublimation or to purify and further sublimate. Further, in the case where chemical treatment is performed by an acid pasting method in which phthalocyanine is dissolved or sulfated in 95% or more sulfuric acid and poured into ice water to reprecipitate, sulfate ions remaining in the crystal are reduced by the photoreceptor. In order to significantly deteriorate the charging characteristics and the sensitivity characteristics, the residual sulfate ion concentration is preferably 2000 ppm or less, more preferably 500 ppm or less.

In the phthalocyanine thus obtained, the particles are often strongly agglomerated to form secondary particles. Therefore, in the photoreceptor which is contained in the charge generation layer as it is, A decrease in the number of carriers generated due to a decrease in light absorption efficiency causes a problem such as a decrease in sensitivity. In addition, since the charge generation layer becomes non-uniform due to the aggregated particles, the efficiency of carrier injection into the charge transport layer also decreases, and problems arise in charging characteristics and repetition potential stability. In order to prevent these, for example, agglomeration between particles is reduced by a method such as an acid pasting method or an acid slurry method, and then extremely fine primary particles can be obtained by mechanically pulverizing the particles. Examples of the pulverizing device include, but are not limited to, an attritor, a roll mill, a ball mill, a sand mill, an agitator, and a stamp mill.

The phthalocyanine that has undergone such a process is a non-crystalline phthalocyanine that does not show a strong X-ray diffraction peak and contains no aggregated particles, so that it has excellent pigment dispersibility and uniform charge generation without coating film defects. Layers can be formed. In addition, since there is no impurity remaining between the aggregated particles, there is no deterioration of the charging characteristics and no repeated potential fluctuation.

As the binder resin used for the charge generation layer, polyester resin, polycarbonate resin, polyvinyl butyral resin, polyvinyl acetate resin, polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, acrylic resin, Silicone resin and the like can be mentioned. The amount of phthalocyanine mixed with these binder resins is preferably 30 to 70% by weight, and the thickness of the charge generation layer is 0.1 to 2 μm.
About m is appropriate.

The charge transport layer comprises a charge transporting substance such as a hydrazone compound, a triphenylamine compound, a stilbene compound, an enamine compound, a polycyclic aromatic compound, a nitrogen-containing heterocyclic compound, or a resin compatible with these substances. For example, it can be obtained by dissolving in a suitable solvent together with a polyester resin, a polycarbonate resin, a polyvinyl butyral vinyl acetate resin, a polystyrene resin, and the like, applying the resulting solution on the charge generation layer to a thickness of about 5 to 40 μm, and drying.
Examples of the charge transporting substance used in the present invention are represented by the following structural formula (I-
1) to (I-12), and typical examples of the polycarbonate resin as a binder resin include the following structural formulas (II-1) to
The results are shown in (II-7).

[0041]

[0042]

[0043]

Various antioxidants can be added to the charge transport layer for the purpose of preventing deterioration due to light, heat, ozone and the like. The following structural formulas (III-1) to (III-
45) shows typical examples of such antioxidants. Incidentally, the electrophotographic photoreceptor of the present invention is not limited to the negatively-charged laminated structure in which the charge transport layer is formed on the charge generation layer as described above. The present invention is also applicable to a positively charged single-layer structure formed by mixing a substance and a binder resin.

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

The present invention will be described below in detail with reference to examples.
In addition, "part" in an example shows a weight part. Example 1 15 parts of a copolymer of p-vinylphenol and styrene as a styrene resin having a hydroxyl group (linker CST: manufactured by Maruzen Petrochemical Co., Ltd.) and a butylated melamine resin (Uban 21R: Mitsui Toatsu Chemicals, Inc.) )) And 1 part of zinc bis (3,5-di-tert-butylsalicylate) represented by the structural formula (B) in 60 parts of tetrahydrofuran, and γ-aminopropyltrimethoxy 20 parts of titanium oxide (TA-200, manufactured by Fuji Titanium Industry Co., Ltd.) surface-treated with silane was placed in a ball mill pot, and alumina balls having a diameter of 10 mm were filled and dispersed by ball milling for 48 hours. Using this coating solution, an outer diameter of 30
dip coating on the surface of the aluminum cylindrical support of mmφ,
It was dried at 140 ° C. for 60 minutes to form a 10 μm-thick undercoat layer.

On the other hand, 20.4 parts of o-phthalodinitrile and 7.6 parts of titanium tetrachloride were combined with α-chloronaphthalene 5
After performing a heat reaction at 200 ° C. for 2 hours in 0 parts, the solvent was removed by steam distillation, the solution was purified with a 2% aqueous hydrochloric acid solution, then with a 2% aqueous sodium hydroxide solution, washed with acetone and dried.
Oxytitanium phthalocyanine was synthesized. 2 parts of the obtained phthalocyanine was gradually dissolved in 40 parts of 98% sulfuric acid at 5 ° C., and the mixture was stirred for about 1 hour while maintaining the temperature at 5 ° C. or less. Subsequently, the sulfuric acid solution was stirred at high speed.
The solution was slowly added to 0 parts of ice water, and the precipitated crystals were filtered. The crystals were washed with distilled water until the sulfate ion concentration became 500 ppm or less, purified with acetone, and dried to obtain oxytitanium phthalocyanine. Further, the oxytitanium phthalocyanine was ground by ball milling. The oxytitanium phthalocyanine thus obtained was composed of fine primary particles of 0.2 μm or less, and did not show a strong diffraction peak as shown in the X-ray diffraction diagram of FIG.

Next, a resin solution obtained by dissolving 1 part of polyvinyl butyral resin (Eslec BL-S, manufactured by Sekisui Chemical Co., Ltd.) in 98 parts of tetrahydrofuran and 1 part of oxytitanium phthalocyanine obtained by the above-mentioned method are mixed. And
Ball milling was performed in the same manner as in the undercoat layer.
This dispersion was applied by dip coating on the undercoat layer described above, and then dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.4 μm.

Further, 5 parts of the hydrazone compound represented by the structural formula (I-1), 5 parts of the hydrazone compound represented by the structural formula (I-2), and 5 parts of the hydrazone compound represented by the structural formula (II-4) Bisphenol A-type biphenyl copolymerized polycarbonate (Tufzet, manufactured by Idemitsu Kosan Co., Ltd., 10 parts) and 1 part of the hindered phenol compound represented by the structural formula (III-2) are uniformly mixed with 79 parts of methylene chloride. After dissolving it and applying it on the charge generating layer in the same manner as described above, 100
Drying was performed at 30 ° C. for 30 minutes to form a charge transport layer having a thickness of 25 μm.

Example 2 20.4 parts of o-phthalodinitrile, 7.6 of titanium tetrachloride
After heating the reaction in 50 parts of α-chloronaphthalene at 200 ° C. for 2 hours, the solvent was removed by steam distillation, the solution was purified with a 2% aqueous hydrochloric acid solution, and then dried to synthesize titanium phthalocyanine dichloride. Next, a charge generation layer and a charge transport layer were applied on the same undercoating layer as in Example 1 by using the obtained titanium phthalocyanine dichloride instead of oxytitanium phthalocyanine in the same manner as in Example 1. A photoreceptor was produced.

Example 3 A copolymer of p-vinylphenol and methyl methacrylate as a styrene resin having a hydroxyl group (Linker CM
M: manufactured by Maruzen Petrochemical Co., Ltd.), 18 parts of trimellitic acid, and the following structural formula (C): And a titanium oxide surface-treated with γ-methacryloxypropyltrimethoxysilane (2 parts of bis (3,5-di-tert-butylsalicylic acid)) in 58 parts of tetrahydrofuran, Co., Ltd., TR-600) (20 parts) was placed in a ball mill pot, filled with alumina balls having a diameter of 10 mm, and dispersed by ball milling for 48 hours. An outer diameter of 3
It was dip-coated on the surface of a 0 mmφ aluminum cylindrical support and dried at 140 ° C. for 60 minutes to form a 15 μm-thick undercoat layer. On this undercoat layer, a charge generating layer and a charge transport layer were formed in exactly the same manner as in Example 1 to produce a photoreceptor.

Example 4 In place of the titanium oxide surface-treated with γ-aminopropyltrimethoxysilane used in the undercoat layer in Example 1, titanium oxide not subjected to surface treatment (TA Titanium, manufactured by Fuji Titanium Industry Co., Ltd.) An undercoat layer was prepared in the same manner as in Example 1 except that -200) was used. Next, a charge generating layer and a charge transporting layer were applied in the same manner as in Example 1 to produce a photoreceptor.

Example 5 20.4 parts of o-phthalodinitrile, 7.6 of titanium tetrachloride
After heating the reaction in 50 parts of α-chloronaphthalene at 200 ° C. for 2 hours, the solvent was removed by steam distillation, the solution was purified with a 2% aqueous hydrochloric acid solution and then a 2% aqueous sodium hydroxide solution, washed with acetone and dried. Oxytitanium phthalocyanine was synthesized. The obtained oxytitanium phthalocyanine was composed of crystalline aggregates of 1 μm or more, and showed a strong diffraction peak as shown in the X-ray diffraction diagram of FIG. Except for using this oxytitanium phthalocyanine, in the same manner as in Example 1, a subbing layer, a charge generation layer and a charge transport layer were applied to prepare a photoreceptor.

Example 6 In the synthesis step of oxytitanium phthalocyanine in Example 1, oxytitanium phthalocyanine which was not washed with distilled water and purified with acetone was used in the same manner as in Example 1 except that oxytitanium phthalocyanine was not used. A coating solution was prepared. The oxytitanium phthalocyanine crystal used here had a sulfate ion concentration of 2500 ppm. Next, after applying an undercoat layer in the same manner as in Example 1, a charge generation layer was formed using the obtained charge generation layer coating solution,
Further, a charge transport layer was formed to prepare a photoreceptor.

Comparative Example 1 An undercoat layer was prepared in the same manner as in Example 1 except that no metal complex was added to the undercoat layer in Example 1.
A charge generating layer and a charge transporting layer were applied in the same manner as in Example 1 to produce a photoreceptor.

The electrical characteristics of the photoreceptor thus manufactured were evaluated by the following procedure using a photoreceptor process tester. Attach the photoreceptor to the tester and set the peripheral speed to 60 mm / s
While rotating at, the surface of the photoreceptor is -600 with a corotron.
V, and the potential at the time of non-irradiation of light was defined as the dark portion potential (charged potential). Subsequently, light having a wavelength of 780 nm and an irradiance of ² μW / cm ² was irradiated, and the potential after 0.2 seconds was defined as a bright portion potential (residual potential). Such a cycle of charging and exposure is repeated 10,000 times in an environment of a temperature of 23 ° C. and a relative humidity of 45% and in an environment of a temperature of 10 ° C. and a relative humidity of 20%, and the fluctuation amount of the dark part potential and the light part potential, respectively. Was measured. Further, the photoconductor was mounted on a laser beam printer, and an initial printing test was performed under the above-described environment. The results of these measurements are shown in Tables 1 and 2 below. In the evaluation of the initial images in the table, a good one was evaluated as ○, a fog having poor ground fogging or density unevenness was evaluated as Δ, and an image with poor density due to poor density was evaluated as x.

[0062]

[Table 1] (Measurement environment: 23 ° C / 45% RH)

[0063]

[Table 2] (Measurement environment: 10 ° C / 20% RH)

As is clear from the results of Tables 1 and 2, the photosensitive members of Examples 1 to 6 have no change in potential even after 10,000 cycles, and the photosensitive members of Examples 1 to 3 Was able to obtain a better initial image and was found to have very good performance.

[0065]

According to the electrophotographic photoreceptor of the present invention,
By providing the undercoating layer containing the organometallic compound, the binder resin, and the titanium oxide pigment, it is possible to obtain stable image quality without being affected by changes in the use environment in terms of charging, residual potential, and sensitivity. Even if the thickness of the undercoat layer is set to be large, the residual potential is low, and no electric charge is accumulated even when the undercoat layer is used repeatedly. Therefore, it is necessary to sufficiently cover the surface defects of the support with the thickness of the undercoat layer. The cost for the surface processing and cleaning of the support can be greatly reduced. Further, since it has a high withstand voltage against a charging potential, an image defect caused by dielectric breakdown can be prevented, particularly when a contact charging method is used.

When the binder resin is a resin having a hydroxyl group, the adhesion between the support and the photosensitive layer can be strengthened, and the photosensitive layer applied and formed on the undercoat layer can be made uniform.

Further, since the light can be scattered by including the inorganic pigment in the undercoat layer, an image defect due to light interference can be prevented even in an electrophotographic apparatus using laser light as a light source.

Further, the titanium-based phthalocyanine contained in the charge generation layer is made to be non-crystalline and free of agglomerated particles by not exhibiting a strong X-ray diffraction peak, thereby providing excellent pigment dispersibility. In addition, it is possible to form a uniform charge generating layer without coating film defects, and at the same time, it is possible to obtain a photosensitive member having high sensitivity and excellent in repeated potential stability.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram according to an example of the present invention.

FIG. 2 is an X-ray diffraction diagram according to another embodiment of the present invention.

Claims (7)

[Claims] 1. An electrophotographic photoconductor in which an undercoat layer and a photosensitive layer are sequentially provided on a conductive support, wherein the undercoat layer contains an organometallic compound, a binder resin, and a titanium oxide pigment. And an electrophotographic photoreceptor, wherein the photosensitive layer contains titanium-based phthalocyanine. 2. The electrophotographic photoconductor according to claim 1, wherein the organometallic compound is a metal complex or a metal salt of an aromatic carboxylic acid. 3. The electrophotographic photoconductor according to claim 1, wherein the binder resin is selected from the group consisting of a styrene resin having a hydroxyl group, a copolymer with a different resin, and a derivative thereof. 4. The electrophotographic photoconductor according to claim 1, wherein said titanium oxide pigment is surface-treated with a silane coupling agent. 5. The photosensitive layer according to claim 1, wherein the photosensitive layer is of a laminated type including a charge generating layer and a charge transporting layer, and the titanium-based phthalocyanine is contained in the charge generating layer. Electrophotographic photoreceptor. 6. The electrophotographic photoconductor according to claim 5, wherein the titanium-based phthalocyanine is an amorphous particle having oxytitanium or titanium halide in a central nucleus and not showing a strong X-ray diffraction peak. 7. The electrophotographic photoreceptor according to claim 5, wherein a sulfate ion concentration of the titanium-based phthalocyanine is 2000 ppm or less.