JP2002169307A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having stable electrical characteristics, high durability and high optical responsiveness in various environments. SOLUTION: The multilayer electrophotographic photoreceptor including an undercoat layer, an electric charge generating layer and an electric charge transferring layer on an electrically conductive substrate is used in an electrophotographic process having >=100 mm/sec process speed. The undercoat layer contains titanium oxide, the ratio of an electric charge transferring material to a binder in the electric charge transferring layer is (10:14) to (10:20) and mobility in 20 V/μm electric field intensity is >=1×10-6 cm2/Vsec. When acicular or dendritic titanium oxide is used in the undercoat layer, environmental dependence is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated electrophotographic photosensitive member, and more particularly, to a laminated electrophotographic photosensitive member in which a photosensitive layer containing an organic material is laminated on a conductive support. The present invention relates to an electrophotographic apparatus such as an electrophotographic printer, a copying machine, a facsimile, etc. using such a laminated electrophotographic photoconductor.

[0002]

2. Description of the Related Art F. The electrophotography technology according to the invention of Carlson is widely used in various printers and facsimiles in recent years, not only in the field of copiers but also in the fields of printers and facsimiles because of the ability to obtain images with immediacy, high quality and high storability. Is showing. This electrophotographic process basically includes “uniform charging of a photoconductor”, “formation of an electrostatic latent image by image exposure”, “development of the latent image with toner”, and “transfer of the toner image to paper ( Intermediate process), and an "image formation by fixing" process.

With respect to the photoreceptor which is the core of the electrophotographic technology, the photoreceptor using an organic photoconductive material has no pollution, low cost, and has a high degree of freedom in material selection. Many advantages have been proposed and put into practical use. The photosensitive layer of such an organic photoreceptor mainly comprises a layer in which an organic photoconductive material is dispersed in a binder resin, and a layer in which a charge generation material is dispersed in a binder resin (charge generation layer) and a charge transport material in a binder. A multilayer structure in which layers (charge transport layers) dispersed in a resin are stacked, a single layer structure in which both a charge generation material and a charge transport material are dispersed in a binder resin, and the like have been proposed. Above all, a function-separated type photoconductor in which a charge transport layer is laminated on a charge generation layer as a photosensitive layer is excellent in electrophotographic characteristics and durability, and has been widely put to practical use. This charge transporting layer is composed of a material having a charge transporting material and a binder resin as main components, and its weight ratio (charge transporting material / binder-resin) is generally used in a range of 10/15 to 10/6. .

However, electrophotographic devices such as digital copiers and printers have recently been reduced in size and speed, and both photosensitizer characteristics have been increased in both sensitivity to respond to higher speeds and longer life due to improved wear resistance. Has been requested. Among these, the former can be achieved by increasing the content of the charge transporting material to achieve a certain degree of sensitivity, but the durability is inferior because the binder resin is reduced.
Furthermore, if the transporting ability of the charge transporting material itself is small, a large improvement effect cannot be obtained even if the charge transporting material / binder resin ratio is increased. Conversely, when the amount of the binder resin is increased, the durability is improved, but on the other hand, the light responsiveness is reduced, which makes application to a high-speed process difficult. In addition, due to poor light responsiveness, if the photoreceptor is repeatedly used in a state where the surface potential is not sufficiently attenuated, a potential change accompanying a rise in the residual potential increases, thereby causing a problem such as early deterioration of image quality. Accompany. Means for avoiding such adverse effects and obtaining a photoreceptor with high photoresponsiveness and high durability include charge transporting materials
There are a method using a material having a higher mobility and a method using a material having a higher sensitivity as a charge generating substance. Recently, a method using these materials in combination has been proposed. For example, JP-A-6-202357 discloses the method. Describes that a charge transport layer having a specific high mobility is used in combination with a highly sensitive oxotitanyl phthalocyanine as a charge generating substance.

[0005]

As described above, various methods have been proposed to achieve both high light responsiveness and high durability in order to cope with high-speed machines. However, even with these conventional techniques, various methods have been proposed. Sufficient high sensitivity and high durability are not completely satisfied. In particular, charge transport materials for achieving high mobility generally have large environmental dependence, and even if they are excellent under normal temperature / humidity environments, their characteristics are dramatically different under other environments, especially at low temperatures / low humidity. May worsen. Furthermore, there is a problem of matching with the charge transport layer and repetition characteristics even in increasing the sensitivity by the charge generation material, and at present it is not sufficient for practical use.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have intensively studied the characteristics of a charge transport material, a binder resin and the like. A new type of laminated electronic device that has improved performance and can respond to environmental changes by using a specific undercoat layer, and can be used in an electrophotographic process with a process speed of 100 mm / sec or more. Succeeded in developing photoreceptors.

That is, the present invention provides a laminated electrophotographic photosensitive member described below and an electrophotographic apparatus using the photosensitive member. (1) An electrophotographic photoreceptor used in an electrophotographic process at a process speed of 100 mm / sec or more in a laminated electrophotographic photoreceptor including an undercoat layer, a charge generation layer, and a charge transport layer on a conductive support. Wherein the undercoat layer contains titanium oxide, the charge transport material / binder ratio in the charge transport layer is 10/14 to 10/20, and the mobility is 1 × 10 ^{−6 at an} electric field strength of 20 V / μm.
A photoconductor for multilayer electrophotography having a cm ² / Vsec or more. (2) The laminated electrophotographic photoconductor according to (1), wherein the titanium oxide contained in the undercoat layer has a needle-like and / or dendritic shape. (3) The titanium oxide / binder ratio in the undercoat layer is 10 /
The laminated electrophotographic photoconductor according to (1) or (2), wherein the photoconductor is 90 to 99/1. (4) The charge transport layer contains a styryl enamine compound represented by the following general formula I as a charge transport material (1)
The laminated electrophotographic photosensitive member according to any one of (1) to (3).

Embedded image [In the formula, Ar ₁ represents an aryl group which may have a substituent, Ar ₂ represents a phenylene group, a naphthylene group or an anthrylene group which may have a substituent, and R represents a hydrogen atom, a lower alkyl group. Or X represents an alkoxy group, X is a hydrogen atom,
It represents an alkyl group which may have a substituent or an aryl group which may have a substituent, and Y represents an aryl group which may have a substituent. (5) The laminated electrophotographic photoconductor according to any one of (1) to (3), wherein the charge transport layer contains a triphenylamine compound represented by the following general formula II as a charge transport material.

Embedded image [Wherein, R ₁ , R ₂ and R ₃ are the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkoxycarbonyl group or a substituted amino group;
Represents an integer of 1 to 5, and q represents an integer of 1 to 4. (6) The charge transport layer contains a bisamine-based compound represented by the following general formula III as a charge transport material (1) to (1).
(3) The laminated electrophotographic photosensitive member according to (3).

Embedded image [Wherein, Ar ₁ and Ar ₂ are the same or different and represent an aryl group, a heterocyclic group, an aralkyl group or a heterocyclic-substituted alkyl group, and R ₄ and R ₅ are the same or different and have 1 to 3 carbon atoms. Represents an alkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, r is an integer of 1 to 4, and s is an integer of 1 to 3; (7) The multilayer electrophotography according to (1) to (6), wherein the binder resin contained in the charge transport layer is a polycarbonate resin having a structural unit represented by the following general formula IV as a main repeating unit. Photoconductor.

Embedded image (8) The laminated electrophotographic photoreceptor according to (1) to (7), wherein at least two or more kinds of polycarbonate resins are used as the binder resin contained in the charge transport layer. (9) The charge generation layer contains phthalocyanine (1)
The laminated electrophotographic photoconductor according to any one of (8) to (8). (10) The photoconductor for laminated electrophotography according to (9), wherein the phthalocyanine in the charge generation layer is oxotitanyl phthalocyanine. (11) The oxotitanyl phthalocyanine in the charge generation layer exhibits a peak at least at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in an X-ray diffraction spectrum using Cu-kα ray (10). ). (12) The undercoat layer contains titanium oxide, the charge transport material / binder ratio is 10/14 to 10/20, and the mobility is 1 × 10 ^{−6 at an} electric field strength of 20 V / μm.
A stack type electrophotographic photoreceptor having a charge transfer layer of not less than 100 cm ² / Vsec has a process speed of 100 mm / sec.
(c) An electrophotographic apparatus used in the electrophotographic process.

(Operation) With the above configuration, the electric characteristics are more stable than conventional photoreceptors in various environments, and high durability and
An electrophotographic photoreceptor having high photoresponsiveness can be realized, and spectral sensitivity suitable for the wavelength of the semiconductor laser can be obtained. Therefore, it is possible to realize an electrophotographic apparatus that can be mounted on a higher-speed machine that requires higher durability than ever.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The electrophotographic photoreceptor according to the present invention is used in an electrophotographic process having a process speed of 100 mm / sec or more. The photosensitive layer includes an undercoat layer and a charge generation layer as shown in FIG. This is a function-separated type photoconductor having a configuration in which a charge transport layer is laminated.

As the conductive support, for example, aluminum, copper, brass, zinc, nickel, stainless steel, chromium,
Metal and alloy materials such as molybdenum, vanadium, indium, titanium, gold and platinum can be used, and in addition, polyester film, paper and metal film on which aluminum, aluminum alloy, tin oxide, gold and indium oxide are deposited or coated Plastics and papers containing conductive particles, plastics containing a conductive polymer, and the like can be used. These materials are used after being processed into a cylindrical shape, a cylindrical shape, or a thin film sheet shape.

An undercoat layer is introduced between the conductive support and the photosensitive layer. The undercoat layer is generally made of an anodized aluminum film, an inorganic layer such as aluminum oxide or aluminum hydroxide, or an organic layer such as polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, or polyamide. Layer or organic layer containing inorganic or inorganic conductive pigments such as metals such as aluminum, copper, tin, zinc and titanium or metal oxides such as zinc oxide, aluminum oxide and titanium oxide. Although used, in the present invention, an organic layer containing titanium oxide is particularly used. In the present invention, among such titanium oxides, needle-like and dendritic titanium oxides whose particle shapes are as shown in FIGS. 2 and 3 are preferable.

Of the above two types of shapes, the needle shape (FIG. 2) is an elongated shape including a rod shape, a column shape, a spindle shape, etc., and has a ratio a between the major axis length a and the minor axis length b. / B indicates an aspect ratio of 1.5 or more. Therefore, it is not necessarily required to be extremely elongated, and the tip does not need to be sharp. The average value of the aspect ratio is 1.5
The range is preferably from 300 to 300, more preferably from 2 to 10. If it is smaller than this range, it is difficult to obtain the effect as a needle, and if it is larger than this range, the effect as a needle does not change.

On the other hand, the dendritic shape (FIG. 3) refers to an elongated and branched shape including a rod shape, a column shape, a spindle shape and the like. Therefore, the shape does not always have to be extremely elongated, and the shape does not need to be sharp and sharp. The particle diameter of the dendritic titanium oxide particles preferably has a minor axis length of 1 μm or less and a major axis length of 100 μm or less, but a minor axis length of 0.5 μm or less and a major axis length of 10 μm or less. More preferred. When the particle size is not within this range, it is difficult to obtain a coating liquid for an undercoat layer having dispersion stability even if surface treatment is performed with a metal oxide or an organic compound.

The particle size and aspect ratio can be measured by a method such as a weight sedimentation method or a light transmission type particle size distribution measuring method. Is preferred. In the present invention, a mixture of acicular or dendritic titanium oxide particles and granular titanium oxide particles may be used. When using any of acicular, dendritic, and granular titanium oxides, the crystal forms of titanium oxide include anatase type, rutile type, and amorphous, and any of them may be used. May be.

The volume resistivity of the titanium oxide particles is preferably 10 ⁵ to 10 ¹⁰ Ωcm. If the volume resistivity of the powder is smaller than 10 ⁵ Ωcm, the resistance value of the undercoat layer decreases and the powder does not function as a charge blocking layer. For example, in the case of metal oxide particles subjected to a conductive treatment such as a tin oxide conductive layer doped with antimony, 1
⁰ 0 Ωcm~10 ¹ very volume resistance of the powder is lowered and the [Omega] cm, the undercoat layer using the same in order to deteriorate the charging property as a photoreceptor characteristic does not function as a charge blocking layer, the image It cannot be used because of fogging and black spots. If the volume resistivity of the powder of titanium oxide particles is increased to 10 ¹⁰ Ωcm or more and becomes equal to or greater than the volume resistivity of the binder resin itself, the resistivity of the undercoat layer is too high, and light irradiation is performed. The transport of the generated carriers is sometimes suppressed and prevented, and the residual potential increases and the photosensitivity decreases, which is not preferable.

The surface of the dendritic titanium oxide particles is coated with a metal oxide such as Al ₂ O ₃ , ZrO _2, or a mixture thereof, as long as the volume resistivity of the titanium oxide particles is maintained within the above range. It is preferable to use one that has been made.
When using titanium oxide particles whose surface is untreated, the titanium oxide particles to be used are fine particles. Particle aggregation is inevitable. Therefore, when the undercoat layer is formed, a defect of the coating film or coating unevenness occurs to cause an image defect. In addition, since the injection of charges from the conductive support is likely to occur, the chargeability of the minute region is reduced and black spots are generated. Therefore, the surface of the titanium oxide particles is coated with a metal oxide such as Al ₂ O ₃ , ZrO ₂ or a mixture thereof to prevent the aggregation of the titanium oxide and to provide an undercoating layer having excellent dispersibility and storage stability. A coating liquid is obtained. Further, since the injection of charges from the conductive support can be prevented, an electrophotographic photoreceptor having excellent image characteristics without black spots can be obtained. Examples of the metal oxide covering the surface of titanium oxide include Al ₂ O ₃ , Zr
O ₂ is preferred. Further, when a surface treatment is performed using both Al ₂ O ₃ and a metal oxide different in ZrO ₂ , more excellent image characteristics can be obtained, so that a more preferable effect is exhibited. When a surface treatment such as SiO ₂ is performed, the surface is hydrophilic, so that the surface is hardly adapted to an organic solvent, dispersibility of titanium oxide is reduced, and aggregation is easily caused. Further, when the surface of titanium oxide is coated with a magnetic metal oxide such as Fe ₂ O ₃ , a chemical interaction occurs with the phthalocyanine pigment contained in the photosensitive layer, and the photoreceptor characteristics, especially It is not preferable because the sensitivity and the charging property decrease.

A metal oxide coating the surface of titanium oxide;
Al used as₂O₃, ZrO ₂And surface treatment amount
Therefore, 0.1 wt% to 20 wt% of titanium oxide
% Is preferred. Even if the processing amount is less than 0.1 wt%
If the surface of titanium oxide can not be coated enough
Therefore, the effect of the surface treatment is hardly exhibited. 20wt%
If the processing amount exceeds
As a result, the characteristics will not change and
Is not preferable because of high cost.

As the organic compound covering the surface of the titanium oxide, a general coupling agent can be used. Examples of the type of the coupling agent include a silane coupling agent such as an alkoxysilane compound, a silylation agent in which atoms such as halogen, nitrogen, and sulfur are bonded to silicon, a titanate coupling agent, and an aluminum coupling agent. Can be For example, silane coupling agents include tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, ethyltrimethoxysilane, diethyldimethoxysilane, phenyltriethoxysilane, aminopropyltrimethoxysilane, γ-
(2-aminoethyl) aminopropylmethyldimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, 3- (1-aminopropoxy) -3,3-dimethyl-1-propenyltrimethoxysilane, (3-acryloxypropyl ) Trimethoxysilane, (3-acryloxypropyl) methyldimethoxysilane, (3-acryloxypropyl) dimethylmethoxysilane, N-3
Alkoxysilane compounds such as-(acryloxy-2-hydroxypropyl) -3-aminopropyltriethoxysilane; chlorosilanes such as methyltrichlorosilane, methyldichlorosilane, dimethyldichlorosilane and phenyltrichlorosilane; hexamethyldisilazane; octamethyl Examples include silazanes such as cyclotetrasilazane, titanate coupling agents such as isopropyltriisostearoyl titanate and bis (dioctyl pyrophosphate), and aluminum coupling agents such as acetoalkoxyaluminum diisopropylate.
It is not limited to these. Also, surface treatment of metal oxide particles by these coupling agents,
When used as a dispersant, one or more coupling agents may be used in combination. The method of subjecting the metal oxide particles to surface treatment is roughly classified into a pretreatment method and an integral blend method, and the pretreatment methods are further divided into a wet method and a dry method. Wet methods include water treatment,
Known methods such as a direct dissolution method, an emulsion method, and an amine adduct method can be used as the water treatment method. In addition, the surface of the titanium oxide particles has a volume resistivity of the powder of the titanium oxide particles before and after the treatment with the coupling agent and before and after addition to the organic solvent as a dispersant. As long as the value is maintained in the above range, the surface of the titanium oxide particles may be untreated, and further, Al ₂ O ₃ , ZrO
_It may be coated with a metal oxide such as ₂ or a mixture thereof.

As the binder resin used for the undercoat layer, polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin,
Resins such as starch, polyurethane, polyimide, and polyamide can be used, but polyamide resins are preferably used. The reason is that, as a property of the binder resin, that the solvent used when forming the photosensitive layer on the undercoat layer does not dissolve or swell, etc., and has excellent adhesion with the conductive support, This is because characteristics such as flexibility are required. More preferably, among the polyamide resins, an alcohol-soluble nylon resin can be used. For example, so-called copolymerized nylon obtained by copolymerizing 6-nylon, 66-nylon, 610-nylon, 11-nylon, 12-nylon, etc.
Nylon is chemically modified, such as alkoxymethyl-modified nylon and N-alkoxyethyl-modified nylon.

In the present invention, the content of the acicular or dendritic titanium oxide particles is from 10 wt% to 99 wt%.
Or less, preferably 30 wt% or more and 99 wt% or less, more preferably 35 wt% or more and 95 wt% or less. If the content is less than 10% by weight, the sensitivity is reduced, the electric charge is accumulated in the undercoat layer, the residual potential is increased, and it is impossible to suppress the potential fluctuation due to the environmental change.
On the other hand, if the content exceeds 99% by weight, the storage stability of the coating solution for the undercoat layer deteriorates, and the precipitation of titanium oxide particles tends to occur, which is not preferable.

In the present invention, a common organic solvent can be used as the organic solvent used for the coating solution for the undercoat layer. However, when a more preferable alcohol-soluble nylon resin is used as the binder resin, 1 to
4 alone and a group consisting of other organic solvents such as dichloromethane, chloroform, 1,2-dichloroethane, 1,2-dichloropropane, toluene, tetrahydrofuran, 1,3-dioxolane and the like. It is preferable to use a system and a mixed system of organic solvents. Here, by mixing the above-mentioned organic solvent, the dispersibility of titanium oxide is improved as compared with the alcohol-based solvent alone, and the storage stability of the coating solution can be prolonged and the coating solution can be regenerated. In addition, when the conductive support is immersed and coated in the undercoat layer coating solution to form the undercoat layer, coating defects and unevenness of the undercoat layer are prevented, and the photosensitive layer formed thereon is uniformly formed. By being able to be applied, it is possible to form an electrophotographic photoreceptor having very excellent image characteristics without film defects.

The thickness of the undercoat layer is preferably
0.01 μm or more and 20 μm or less, more preferably 0.0 μm or less
The range is 5 μm or more and 10 μm or less. If the thickness of the undercoat layer is less than 0.01 μm, the undercoat layer will not substantially function as an undercoat layer, and will not cover the defects of the conductive support to obtain uniform surface properties. Cannot be prevented, and the chargeability is reduced. On the other hand, when the thickness is larger than 20 μm, it is difficult to manufacture the photoconductor when the undercoat layer is applied by dip coating, and the sensitivity of the photoconductor is lowered.

As a method for producing the undercoat layer, a coating liquid for an undercoat layer prepared by adding a solvent and a binder resin to the above-mentioned inorganic pigment and dispersing the mixture using a disperser such as a ball mill, a Dyno mill, or an ultrasonic oscillator is used. In the case of a sheet, it can be produced by a baker applicator, a bar coater, casting, spin coating or the like, and in the case of a drum, it can be produced by a spray method, a vertical ring method, a dip coating method or the like.

The charge generation layer contains, as a main component, a charge generation material that generates charges by light irradiation, and may contain a known binder, plasticizer, and sensitizer as necessary. As the charge generating material, perylene imide, perylene pigments such as perylene anhydride, quinacridone, polycyclic quinone pigments such as anthraquinone, metal and metal-free phthalocyanine, phthalocyanine pigments such as halogenated metal-free phthalocyanine, squarium dye, Azurenium dye, thiapyrylium dye,
And azo pigments having a carbazole skeleton, styrylstilbene skeleton, triphenylamine skeleton, dibenzothiophene skeleton, oxadiazole skeleton, fluorenone skeleton, bisstilbene skeleton, distyryloxadiazole skeleton or distyrylcarbazole skeleton. Particularly high charge generation pigments include metal-free phthalocyanine pigments, oxotitanyl phthalocyanine pigments, bisazo pigments containing a fluorene ring and a fluorenone ring, bisazo pigments composed of aromatic amines, and trisazo pigments, and have high sensitivity. A photoreceptor can be provided. Further, among oxotitanyl phthalocyanines, X
Bragg angle (2θ ± 0.2 °) of X-ray diffraction spectrum 2
A crystal form showing a diffraction peak at 7.3 ° is more preferable because of higher sensitivity.

As a method for producing the charge generating layer, a coating liquid obtained by adding an organic solvent to the fine particles of these charge generating materials, and pulverizing and dispersing the fine particles with a ball mill, a sand grinder, a paint shaker, an ultrasonic disperser or the like is used. In the case of a sheet, it is produced by a baker applicator, a bar coater, casting, spin coating or the like, and in the case of a drum, it is produced by a spray method, a vertical ring method, or a dip coating method.
In order to increase the binding property, as a binder resin, for example, polyester resin, polyvinyl acetate, polyacrylate, polycarbonate, polyarylate, polyvinyl acetoacetal, polyvinyl propional,
Various binder resins such as polyvinyl butyral, phenoxy resin, epoxy resin, urethane resin, melamine resin, silicone resin, acrylic resin, cellulose ester, cellulose ether, and vinyl chloride-vinyl acetate copolymer resin may be added. The film thickness is usually 0.05 to
5 μm is preferable, and 0.1 to 1 μm is particularly preferable.
In addition, the charge generation layer may contain various additives such as a leveling agent, an antioxidant, and a sensitizer for improving coating properties, if necessary.

The charge transport layer provided on the charge generation layer has a charge transport material capable of receiving and transporting charges generated by the charge generation material and a binder as essential components. Are poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives, imidazole derivatives , 9- (p-Diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, pyrazoline derivatives, phenylhydrazones, hydrazone derivatives, triphenylamine compounds, tetra Electron-donating substances such as enyldiamine-based compounds, triphenylmethane-based compounds, stilbene-based compounds, and azine compounds having a 3-methyl-2-benzothiazoline ring, or fluorenone derivatives, dibenzothiophene derivatives, indenothiophene derivatives, and phenanthrene Examples thereof include electron accepting substances such as quinone derivatives, indenopyridine derivatives, thioxanthone derivatives, benzo [c] cinnoline derivatives, phenazine oxide derivatives, tetracyanoethylene, tetracyanoquinodimethane, promanyl, chloranil, and benzoquinone. Among these, specific styryl enamine compounds, triphenylamine compounds, and bisamine compounds are more preferable in the present invention because the materials themselves have high hole transport ability and can maintain high sensitivity even in a binder-rich state. .

Specific examples of the styryl enamine-based compound (general formula I) include the following compounds.

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The following compounds may be mentioned as triphenylamine compounds (general formula II).

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The following compounds are mentioned as the bisamine compound (general formula III).

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A charge transport layer is formed in such a manner that these charge transport materials are bound to a binder resin. As the binder resin used for the charge transport layer, any resin having compatibility with the charge transport material may be used.For example, polycarbonate and copolymerized polycarbonate, polyarylate, polyvinyl butyral, polyamide, polyester, polyketone, epoxy resin, Polyurethane, polyvinyl ketone,
Polystyrene, polyacrylamide, phenolic resin,
Phenoxy resins, polysulfone resins and the like, and copolymer resins thereof. These may be used alone or in combination of two or more. Among them, the bisphenol Z-type polycarbonate represented by the general formula IV is particularly preferable because of its excellent abrasion resistance, and a mixed system of this and other polycarbonates is preferable because it may have an effect of improving electric properties and film-forming properties. . The solvent that dissolves these materials is
Alcohols such as methanol and ethanol, acetone,
Ketones such as methyl ethyl ketone and cyclohexanone,
Ethers such as ethyl ether and tetrahydrofuran,
Chloroform, dichloroethane, aliphatics such as dichloromethane, halogen hydrocarbons, benzene, chlorobenzene,
There are aromatics such as toluene. The charge transport material / binder resin ratio is usually about 10/15 to 10/6, but in the present invention, from the viewpoint of improving the abrasion resistance, the charge transport material / binder resin is used in a ratio of 10/14 to 1/10.
0/20 is preferred. The coating solution for a charge transport layer of the present invention contains additives such as a plasticizer, an antioxidant, an ultraviolet absorber, and a leveling agent in order to improve film formability, flexibility, coatability and the like. Is also good. As a coating method, the same method as that for the undercoat layer and the charge generation layer is used.

Among the effects obtained by the present invention, it can be said that the improvement in durability and high-speed response is mainly due to the improvement of the charge transport layer. In the present invention, the charge transporting material / binder ratio of the charge transporting layer is set to a high speed machine because the conventional charge transporting material / binder ratio cannot provide an appropriate abrasion resistance and cannot be accommodated by a recent higher speed machine. It is possible to achieve both high sensitivity and high durability by using a specific charge transport material with extremely high transport capacity as the charge transport material after optimizing it to obtain high abrasion resistance compatible with I have. Until now, an appropriate sensitivity could not be obtained unless the charge transport material / binder ratio was set to about 10/10 to 10/12. However, in the photoreceptor of the present invention, the charge transport material / binder ratio was low. 10 /
Even when the binder is very rich such as 14 to 10/20, the mobility at an electric field strength of 20 V / μm is 1 × 1.
0 ^{-6 cm} 2 ^/ possible and compatible enough can respond sensitivity and abrasion resistance in recent high-speed machine for which the Vsec or higher than it has become possible.

However, the charge transporting materials having extremely high transporting abilities as described above are generally highly environmentally dependent, and even if excellent sensitivity is obtained under normal temperature / normal humidity environments, they are extremely sensitive under low temperature / low humidity environments. Worsens. In the present invention, a stable electron under various environments is introduced by introducing a subbing layer containing a titanium oxide, particularly a dendritic or acicular one, between the charge generating layer and the conductive support. This makes it possible to manufacture a photoreceptor having photographic characteristics. Improvement of the environmental stability by the undercoat layer is achieved by increasing the contact area between the pigment particles in the undercoat layer and increasing the number of electron transport paths from the photosensitive layer to the conductive support. The lowering of the transporting ability in the underlying charge transporting layer is compensated for by the number of transporting paths in the undercoating layer, thereby preventing deterioration in sensitivity. In the case of conventionally used granular titanium oxide, since the shape is an isotropic shape, the effect is not obtained because the contact area is not increased unless the content is increased, but the content is excessive. However, adverse effects such as minute black spots occur on the output image, and the environmental dependency cannot be completely improved. Titanium oxide having a dendritic or acicular shape specified in the present invention has a completely anisotropic shape, that is, an extremely large size in a specific direction. In the direction, contact between neighboring titanium oxide particles is likely to occur, and a larger contact area is obtained as a whole than in the case of granular titanium oxide having the same content. Therefore, in the undercoat layer containing the titanium oxide having the shape specified in the present invention, a large contact area can be achieved even at a much lower content than in the case of the conventional granular titanium oxide, so that there is no significant adverse effect on the environment. It is thought that dependency can be improved.

(Examples) Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 30 parts by weight of dendritic titanium oxide (TTO-D-1 manufactured by Ishihara Sangyo) and a copolymer nylon resin (CM80 manufactured by Toray Industries, Inc.) as a binder resin
00) 30 parts by weight were added to a mixed solvent of 564 parts by weight of methyl alcohol and 376 parts by weight of 1,3-dioxolane, and then dispersed by a paint shaker for 8 hours to prepare a coating liquid for an undercoat layer. This coating liquid is filled in a coating tank, and the diameter 4
An aluminum cylindrical support having a total length of 0 mm and a length of 340 mm was used as a conductive support, and a film thickness of 1.0 was obtained by dip coating.
A μm undercoat layer was formed on a conductive support.

Next, as the oxotitanyl phthalocyanine represented by the following general formula, the Bragg angle (2θ ± 0.2 °) in Cu-kα characteristic X-ray diffraction is at least 2
A mixture of 2 parts by weight of an oxotitanyl phthalocyanine pigment having a clear diffraction peak at 7.3 °, 1 part by weight of polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd .: Eslec BM-S) and 97 parts by weight of methyl ethyl ketone was mixed with a paint shaker. Dispersion treatment was performed to prepare a coating solution for a charge generation layer, and a charge generation layer having a thickness of 0.4 μm was formed on the undercoat layer in the same manner as in the above-described undercoat layer.

Embedded image (Wherein, X _{1 to} X ₄ are the same or different and represent a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group;
l, m, and n are integers of 0 to 4. )

Subsequently, 10 parts by weight of a styryl enamine compound represented by the structural formula of Exemplified Compound I-3 (HCT-202 manufactured by Hodogaya Chemical Co., Ltd.) and 10 parts by weight of the polycarbonate resin represented by the general formula IV (manufactured by Mitsubishi Engineering-Plastics Corporation: 16 parts by weight of Iupilon (Z200))
Furthermore, dimethylpolysiloxane (KF: manufactured by Shin-Etsu Chemical Co., Ltd.)
-96) to the binder resin at a ratio of 0.02 wt%, and a solid content of 23 using tetrahydrofuran as a solvent.
A coating solution for a charge transport layer of wt% is prepared, filled in a coating tank, and applied on the charge generating layer by a dip coating method.
After drying at 0 ° C. for 1 hour, a charge transporting layer having a thickness of 23 μm was formed to prepare a photoreceptor sample.

Example 2 The procedure of Example 1 was repeated except that a needle-like product (STR-60N, manufactured by Sakai Chemical Co.) was used as the titanium oxide contained in the undercoat layer coating solution. Each coating solution was prepared in the same manner as in Example 1 to prepare a photoconductor sample.

Example 3 In Example 1, 6 parts by weight of titanium oxide and 5 parts of a binder resin were used as the coating solution for the undercoat layer.
Except for using 4 parts by weight, each coating solution was prepared in the same manner as in Example 1 to prepare a photoreceptor sample.

(Example 4) Each coating solution was prepared in the same manner as in Example 1 except that the amount of the polycarbonate resin of the coating solution for the charge transport layer was changed to 14 parts by weight, and a photoreceptor sample was prepared. did.

Example 5 Each of the coating solutions was prepared in the same manner as in Example 1 except that the amount of the polycarbonate resin of the coating solution for the charge transport layer was changed to 20 parts by weight to prepare a photoreceptor sample. did.

Example 6 In Example 1, the amount of the polycarbonate resin in the coating solution for the charge transport layer was 7.2 parts by weight, and another type of polycarbonate resin was bisphenol A type polycarbonate represented by the following structural formula. Each coating solution was prepared in the same manner as in Example 1 except that 8.8 parts by weight of a copolymer resin of biphenyl and polysiloxane was added to make 16 parts by weight as a total binder resin, and a photoreceptor sample was prepared.

Embedded image

Example 7 The procedure of Example 1 was repeated except for using a triphenylamine compound represented by the structural formula of Exemplified Compound II-2 in place of the styrylenamine compound. A coating solution was prepared, and a photoreceptor sample was prepared.

Example 8 Each coating solution was prepared in the same manner as in Example 1 except that a bisamine compound represented by the structural formula of Exemplified Compound III-2 was used in place of the styryl enamine compound. Was prepared to prepare a photoreceptor sample.

(Comparative Example 1) In Example 1, the coating solution for the charge generation layer was directly applied on the conductive support by the dip coating method, and then the coating solution for the charge transport layer was applied thereon. A photoreceptor sample without a pulling layer was prepared.

Comparative Example 2 The procedure of Example 1 was repeated except that the titanium oxide contained in the undercoat layer coating liquid was a granular one (TTO55A, manufactured by Ishihara Sangyo Co., Ltd.). In the same manner, each coating solution was prepared, and a photoreceptor sample was prepared.

(Comparative Example 3) In Example 3, 3 parts by weight of titanium oxide and 5 parts of binder resin were used as the undercoat layer coating solution.
Except for using 7 parts by weight, each coating solution was prepared in the same manner as in Example 3 to prepare a photoreceptor sample.

Comparative Example 4 Each coating solution was prepared in the same manner as in Example 1 except that a hydrazone compound represented by the following structural formula was used as the charge transporting material.
A photoreceptor sample was prepared.

Embedded image

Comparative Example 5 A photoreceptor sample was prepared by preparing each coating solution in the same manner as in Example 1 except that the amount of the polycarbonate resin of the coating solution for the charge transport layer was changed to 10 parts by weight. did.

Comparative Example 6 A photoreceptor sample was prepared by preparing each coating solution in the same manner as in Example 1 except that the polycarbonate resin of the coating solution for the charge transport layer was changed to 25 parts by weight. did.

(Comparative Example 7) In Example 1, a polycarbonate resin (C-1400 manufactured by Teijin Chemicals Ltd.) having the following structural unit as a repeating unit was used as the polycarbonate resin of the coating solution for the charge transport layer, and the solvent was dichloromethane. Each coating liquid was prepared in the same manner as in Example 1 except that the above-mentioned was used, and a photoreceptor sample was prepared.

Embedded image

(Comparative Example 8) In Example 1, the oxotitanyl phthalocyanine pigment having a clear peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° was used as the oxotitanyl phthalocyanine in the coating solution for the charge generation layer. A photoreceptor sample was prepared in exactly the same manner as in Example 1, except that oxotitanyl phthalocyanine of α-type crystal having no clear peak was used instead.

(Evaluation) Electrophotography produced in this way
Photoreceptor samples were processed at a process speed of 117 mm / s
ec digital copier (AR-C1 manufactured by Sharp Corporation)
50) as a stability test of electrical characteristics
Charge potential V under humidity (22 ° C / 65%)₀And laser dew
Surface potential V after light_L, And low temperature / low humidity (5 ° C / 20%)
V of time _LAnd V at normal temperature / humidity_LDifference from ΔV_LMeasure
Was. In addition, initial and 40,000 pieces of durability test
Comparison of image characteristics and film reduction after Aging
The amount was measured. In addition, the mobility of the charge transport layer is
Test machine CYNTHIA (GENTEC)
It was measured by the holographic TOF method. These results are tabulated.
It is shown in FIG.

[Table 1]

As shown in Table 1 above, in Comparative Example 1 without the undercoat layer and in Comparative Example 2 using the undercoat layer containing the particulate titanium oxide, the mobility and the film reduction were largely different from those of the Examples. no although, the occurrence of fog and black spots can also be confirmed in the image evaluation after the deterioration of △ V _L due to environmental change is intense live action.
In Comparative Example 3 using titanium oxide having the shape specified in the present invention, the content of the titanium oxide was also small, so that the potential of the exposed portion was already high even under normal temperature / humidity, and the potential fluctuation due to environmental changes was not suppressed. In Comparative Example 4 in which a material having a low transporting ability was used as the charge transporting material, Comparative Example 5 in which the charge transporting material / binder resin ratio was higher than the value specified in the present invention, and Comparative Example 6 in which the ratio was reduced, the environmental change was not significant. Although not much different from the example, there is an adverse effect on the amount of film reduction and mobility, and
It is clear that when the charge transport material is excessively charged, the instability to the environment has not been suppressed by the introduction of the undercoat layer, and the high speed, long life, and stability cannot be fully achieved. Also, in Comparative Example 7 using a binder resin that has been conventionally used well, although not as large as in Comparative Example 5, the film loss was large and the adverse effect on image evaluation was obvious, and a crystal type different from the crystal type specified in the present invention was used. Comparative Example 8 using the charge generating material also has the undercoat layer and the charge transporting layer specified in the present invention, but the sensitivity of the charge generating layer itself is poor due to the low ability of the charge generating layer itself. It appears as.

On the other hand, in each of Examples 1 to 8 in which the undercoat layer specified by the present invention was introduced and the charge transport layer having the mobility specified by the present invention was formed, the mobility of the charge transport layer was reduced with a small reduction in film thickness. In addition to the high, the change in the surface potential of the laser exposed part due to environmental changes is also smaller than the comparative example,
It is clear that not only the durability and the light response but also the environmental stability have been improved. In more detail, Examples 1, 2, 5 to 8 are also excellent in image evaluation, and it is clear that long life and high-speed compatibility can be realized more stably than conventional photoconductors in all environments. Appears in.

[0055]

As described above in detail, according to the present invention, an electrophotographic photosensitive member having more stable electric characteristics, higher durability and higher photoresponsiveness under various environments than conventional photosensitive members is provided. Thus, a spectral sensitivity suitable for the wavelength of the semiconductor laser can be obtained. Therefore, an electrophotographic apparatus that can be mounted on a higher-speed machine that requires high durability can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a layer configuration of a laminated photoconductor in which an intermediate layer is provided between a photoconductive layer and a conductive support.

FIG. 2 is a cross-sectional view of acicular titanium oxide.

FIG. 3 is a cross-sectional view of dendritic titanium oxide.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive support 2 charge generating material 3 charge transport material 4 photosensitive layer 5 charge transport layer 6 charge transport layer 7 intermediate layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 5/06 371 G03G 5/06 371 5/14 101 5/14 101E 101C (72) Inventor Yuriko Shindo Osaka (22) Inventor Yoshihide Shimoda 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture Sharp Corporation F-term (reference) AA35 AA45 BA12 BA13 BA16 BA39 BB26 CA29

Claims (12)

[Claims] 1. A laminated electrophotographic photoreceptor comprising an undercoat layer, a charge generation layer and a charge transport layer on a conductive support,
An electrophotographic photosensitive member used in an electrophotographic process having a process speed of 100 mm / sec or more, wherein the undercoat layer contains titanium oxide, and the charge transport material / binder ratio in the charge transport layer is 10/14 to 10 / 20 and the mobility is 1 × at an electric field strength of 20 V / μm.
A laminated electrophotographic photoconductor, which has a resistivity of 10 ⁻⁶ cm ² / Vsec or more. 2. The laminated electrophotographic photoconductor according to claim 1, wherein the titanium oxide contained in the undercoat layer has a needle-like and / or dendritic shape. 3. The photoconductor according to claim 1, wherein the ratio of titanium oxide / binder in the undercoat layer is 10/90 to 99/1. 4. The photosensitive material according to claim 1, wherein the charge transport layer contains a styryl enamine compound represented by the following general formula I as a charge transport material. body. Embedded image [In the formula, Ar ₁ represents an aryl group which may have a substituent, Ar ₂ represents a phenylene group, a naphthylene group or an anthrylene group which may have a substituent, and R represents a hydrogen atom, a lower alkyl group. Or X represents an alkoxy group, X is a hydrogen atom,
It represents an alkyl group which may have a substituent or an aryl group which may have a substituent, and Y represents an aryl group which may have a substituent. ] 5. The laminated electrophotographic device according to claim 1, wherein the charge transport layer contains a triphenylamine compound represented by the following general formula II as a charge transport material. Photoconductor. Embedded image [Wherein, R ₁ , R ₂ and R ₃ are the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkoxycarbonyl group or a substituted amino group;
Represents an integer of 1 to 5, and q represents an integer of 1 to 4. ] 6. The photoconductor of claim 1, wherein the charge transport layer contains a bisamine compound represented by the following general formula III as a charge transport material. . Embedded image [Wherein, Ar ₁ and Ar ₂ are the same or different and represent an aryl group, a heterocyclic group, an aralkyl group or a heterocyclic-substituted alkyl group, and R ₄ and R ₅ are the same or different and have 1 to 3 carbon atoms. Represents an alkyl group, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group having 1 to 3 carbon atoms, a halogen atom or a hydrogen atom, r is an integer of 1 to 4, and s is an integer of 1 to 3; ] 7. The method according to claim 1, wherein the binder resin contained in the charge transport layer is a polycarbonate resin having a structural unit represented by the following general formula IV as a main repeating unit. The photoconductor for laminated electrophotography. Embedded image 8. The photosensitive material according to claim 1, wherein the binder resin contained in the charge transport layer comprises at least two kinds of polycarbonate resins. body. 9. The photoconductor according to claim 1, wherein the charge generation layer contains phthalocyanine. 10. The laminated electrophotographic photoconductor according to claim 9, wherein the phthalocyanine in the charge generation layer is oxotitanyl phthalocyanine. 11. The oxotitanyl phthalocyanine in the charge generation layer has at least a Bragg angle (2θ ± 0.2 °) in an X-ray diffraction spectrum using Cu-kα ray.
11. The laminated electrophotographic photoconductor according to claim 10, wherein the photoconductor shows a peak at 3 [deg.]. 12. An undercoat layer containing titanium oxide, a charge transport material / binder ratio of 10/14 to 10/20, and a mobility of 1 × at an electric field strength of 20 V / μm.
A lamination type electrophotographic photosensitive member having a charge transfer layer of 10 ⁻⁶ cm ² / Vsec or more has a process speed of 100 m.
An electrophotographic apparatus used in an electrophotographic process of m / sec or more.