JP3333825B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor,
More specifically, the present invention relates to an improvement in an electrophotographic photosensitive member having a polymer charge transport material.

[0002]

2. Description of the Related Art As an electrophotographic method, a Carlson process and various other deformation processes are known.
Widely used in copiers and printers. Among the photoreceptors used in such an electrophotographic method, those using an organic photosensitive material have been used in recent years because of their advantages of low cost, mass productivity and no pollution. Organic electrophotographic photoreceptors include polyvinyl carbazole (PV
K), a photoconductive resin represented by PVK-TNF (2,
(4,7-trinitrofluorenone), a pigment-dispersion type represented by a phthalocyanine-binder, and a function-separated type photoreceptor using a combination of a charge generating material and a charge transporting material. In particular, a function-separated type photoconductor has attracted attention.

[0003] The mechanism of the formation of an electrostatic latent image in a function-separated type photoreceptor is that, when the photoreceptor is charged and irradiated with light, the light passes through a transparent charge transport layer and is charged by a charge generating substance in the charge generation layer. The absorbed charge-generating substance that has absorbed light generates charge carriers, which are injected into the charge-transporting layer, move in the charge-transporting layer along the electric field generated by the charging, and charge on the photoreceptor surface. Neutralized to form an electrostatic latent image. Among the function-separated photoconductors, those using a charge transport material having absorption mainly in the ultraviolet region and a charge generation material having absorption mainly in the visible region to the near infrared region are known and useful. It is.

Many charge transport materials have been developed as low molecular weight compounds. However, since low molecular weight compounds alone do not have a film-forming property, they are usually used after being dispersed and mixed with an inert polymer.
However, the charge transport layer composed of a low-molecular charge transport substance and an inert polymer is generally soft at a practical level,
In the Carlson process, there is a disadvantage that the film is easily scraped by repeated use.

Further, the charge transport layer of this structure has a limit in charge mobility, which has been an obstacle to speeding up or downsizing of the Carlson process. This is due to the fact that the content of the low-molecular charge transporting substance is usually used at 50% by weight or less. That is, the charge mobility can be certainly increased by increasing the content of the low-molecular charge transport material, but at the same time, the film-forming property deteriorates.

In order to overcome this problem, attention has been paid to polymer type charge transporting materials, for example, Japanese Patent Application Laid-Open Nos. 50-82056, 51-73888, and 54-8.
527, JP-A-54-11737, JP-A-56-150749, JP-A-57-78402, JP-A-63-285552, JP-A-1-1-1
No. 728, Japanese Unexamined Patent Publication No. 3-50555, and the like. However, the photosensitivity of a photoreceptor in which a charge transport layer composed of a polymer charge transport material and a charge generation layer are combined is significantly inferior to the case where the above-described low molecular charge transport material is used. It was strongly desired.

Further, Japanese Patent Application Laid-Open No. 5-34939 discloses that
Regarding a technique for increasing the sensitivity of a laminated electrophotographic photoreceptor using a polymer charge transport material for a charge transport layer, a technique of adding a low molecular charge transport material to a charge generation layer or a charge transport layer has been disclosed. However, when a low molecular charge transporting material is added to a photosensitive layer having a charge transporting layer composed of a polymer charge transporting material, the sensitivity is improved as compared with the case where no low molecular weight charge transporting material is added, but a satisfactory level has not been reached.

Further, attempts have been made to reduce the concentration of the charge transporting substance (charge transporting substance / binder resin ratio) in the charge transporting layer of the laminated photoreceptor and to add a low molecular charge transporting substance to the charge generating layer. (Japanese Patent Application Laid-Open No. 63-281167), although the sensitivity was improved more than when no additive was added, but it did not reach a satisfactory level. Further, in order to overcome such a drawback, it is conceivable to add a polymer charge transport material into the charge generation layer, which is an effective means.
In some cases, the pot life is poor due to poor compatibility with the charge generating substance (such as wettability and dispersibility).

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor having excellent abrasion resistance upon repeated use, low residual potential, and high-speed response, and a stable production of the electrophotographic photoreceptor. It is an object of the present invention to provide a manufacturing method which can be performed.

[0010]

According to the present invention, first, a charge generation layer containing a charge generation material and a polymer charge transport material as effective components on a conductive support, and a polymer charge transport material are provided. An electrophotographic photoreceptor obtained by laminating a charge transport layer comprising: a low-molecular charge transport material in the charge transport layer. An electrophotographic photoreceptor comprising a charge generation layer containing a charge generation material and a polymer charge transport material as effective components on a conductive support, and a charge transport layer comprising a polymer charge transport material. An electrophotographic photoreceptor characterized by containing a low-molecular charge transport material therein is provided. Thirdly, a charge generation material and a polymer charge transport material are contained as an active ingredient on a conductive support. Charge generation layer and polymer charge transport material An electrophotographic photoreceptor comprising a stack of charge transport layers comprising: a charge transport layer; and an intermediate layer comprising a low molecular charge transport material as a main component between the charge generation layer and the charge transport layer. An electrophotographic photoreceptor is provided. Fourth, in the method for producing an electrophotographic photoreceptor,
A method for producing an electrophotographic photoreceptor, characterized in that the charge generation layer is simultaneously coated and formed by using two or more spray heads, and fifthly, the dispersion state of the charge generation material is stable. An electrophotographic method comprising simultaneously coating and forming a coating liquid containing a charge generation material dispersion formed together with a certain solvent and a binder resin and a polymer charge transport material using two or more spray heads. A method of making a body is provided.

Until now, it has been considered that photocarrier generation in a function-separated type photoconductor is caused by photoexcitation of a charge generation material in a charge generation layer, and very few examples have demonstrated this. .

The present inventors have studied the photocarrier generation of a laminated photoreceptor using a bisazo pigment and a trisazo pigment for the charge generation layer. As a result, the excitons were added to the light-absorbed charge generation layer bulk. This exciton is diffused (energy transfer) to the interface between the charge generation layer and the charge transport layer, where it is dissociated into free carriers, and it is found that photocarriers are being generated, and the Japanese Journal of Applied Physics Vol. 29, No. 2, February
746-2750 and Journal of Applied Physics, Vol. 72, No. 1, pp. 117-123.

Further, the present inventors have conducted intensive studies thereafter and obtained the following findings. (1) Carrier generation at the interface between the charge generation layer and the charge transport layer is observed throughout the organic charge generation material. (2) The amount of generated photocarriers is larger as the degree of contact / mixing between the charge generating material and the low molecular charge transporting material is larger. (3) The amount of photocarrier generated also occurs between the charge generating material and the polymer charge transporting material, and the larger the amount, the greater the degree of contact / mixing. (4) When the charge transport layer is formed by a normal casting method,
A low molecular compound (low molecular charge transport material) can penetrate into the charge generation layer and sufficiently contact with the charge generation material, but a high molecular compound cannot penetrate into the charge generation layer and cannot be charged with the charge generation material. The amount of photocarriers generated is small (low sensitivity) because of insufficient contact with the substrate. Based on such new findings, the present inventors have studied the technology for increasing the sensitivity of a laminated photoreceptor using the above-described polymer charge transport material, and have completed the present invention.

As described above, the electrophotographic photoreceptor of the present invention comprises at least a charge generation layer comprising a charge generation layer and a polymer charge transport material, and a polymer charge transport material on a conductive support. In a photoreceptor having a charge transport layer as a main component laminated thereon, a charge generation layer or a charge transport layer or an intermediate layer contains a low molecular charge transport material. Such an electrophotographic photosensitive member is excellent in abrasion resistance when repeatedly used, has a small residual potential, and is excellent in high-speed response.

Such an increase in sensitivity can be considered as follows based on the above-mentioned findings. That is,
The polymer charge transporting material used in the charge transporting layer has a low molecular weight and a small diffusion constant, and cannot penetrate into the charge generating layer during cast coating. Only the interface of the layer is provided, and the carrier generation site is insufficient.

On the other hand, in the electrophotographic photoreceptor of the present invention, since a charge transporting polymer material is added in advance to the charge generating layer, a carrier generating site between the charge generating material and the charge transporting material is reduced. Is secured. Thus, even if a charge transport layer made of a polymer charge transport material is formed, the number of carrier generation sites is preserved, and high sensitivity can be exhibited. Further, by including a low-molecular charge transport material in the charge generation layer or the charge transport layer or the intermediate layer, it is possible to preferably generate photocarriers between the charge generation material and the charge transport material, A desirable high-sensitivity photoreceptor can be realized. Further, in the photoreceptor of the present invention, since the charge transport layer is composed of a polymer charge transport material or a polymer charge transport material and a low molecular charge transport material, the photocharge mobility based on the densification of charge transport sites is improved. It has a high-speed photoresponse which cannot be realized by the low-molecular-weight charge transporting material-inactive polymer system.

According to a fourth aspect of the present invention, there is provided a method for producing an electrophotographic photosensitive member having a charge generation layer containing at least a polymer charge transport material and at least a charge transport layer on a conductive support. The method is characterized in that the charge generation layer is simultaneously coated and formed using two or more spray heads. The method for producing an electrophotographic photoreceptor according to claim 5, wherein the electrophotographic photoreceptor has a photosensitive layer containing at least a polymer charge transport material and a charge generation material on a conductive support. The layer is characterized by simultaneously coating and forming a coating liquid containing at least a polymer charge transport material and a coating liquid containing at least a charge generating substance using two or more spray heads. .

In general, there are two methods for producing an electrophotographic photosensitive member, a dry film forming method and a wet coating method. However, most of organic electrophotographic photoconductors other than selenium-based and amorphous silicon-based photoconductors are formed by wet coating methods such as dip coating, spraying, and roller coating. Have been. This wet coating method has advantages such as easy area enlargement and inexpensiveness, but is easily affected by the properties (viscosity, surface tension, etc.) of the coating liquid and the base (including the substrate). It also has the disadvantage. This phenomenon is particularly remarkable in a thin film such as a charge generation layer. In other words, it is no exaggeration to say that the quality of the coating film is determined by the quality of the coating liquid and the quality of the coating liquid.

Recent electrophotographic photoreceptors are required to have high durability or high functionality, and various materials have been used, some of which are insoluble in solvents. In such a case, it is used as a dispersion, but the dispersion is generally not stable. In particular, a material such as an organic pigment may interact with an organic solvent, and problems such as aggregation and sedimentation are likely to occur. When such a problem occurs, the coating solution for the photosensitive layer or the charge generation layer leads to a coating film defect of a photoconductor to be produced, and eventually causes a defective image. Therefore, how to select the vehicle of the dispersion and how to design the dispersion are important issues. Under these circumstances, the materials that can be used are naturally limited.

On the other hand, as described above, in order to design a photoreceptor having high abrasion resistance, high sensitivity and low residual potential, it is necessary to include a polymer charge transport material in the photosensitive layer or the charge generation layer. It is important, and at present, there is a part that is inconsistent with the stability of the coating liquid, and this is an important issue in manufacturing.

The present inventors have studied this point and found that the photosensitive layer or the charge generation layer can be easily formed by simultaneously coating and forming two or more spray heads. As a result, the present invention has been completed. In other words, a coating solution using a vehicle capable of stably dispersing a charge generating substance and a coating solution containing a polymer charge transporting material are separately prepared, and the coating is performed simultaneously to obtain a stable coating film. As long as the respective liquids are not mixed, the dispersion system is not broken and the pot life can be designed to be long. In addition, by adopting such a form, the range of material selection is widened, and a more sophisticated photoconductor can be designed.

The structure of the electrophotographic photosensitive member of the present invention will be described with reference to the attached drawings. 1 and 2 are cross-sectional views showing an electrophotographic photoreceptor of the present invention.
1, a charge generation layer 13 mainly composed of a polymer charge transport material and a charge generation material, and a charge transport layer 15 mainly composed of a polymer charge transport material are laminated. 3 and 4 are cross-sectional views illustrating another configuration example of the electrophotographic photoreceptor of the present invention.
An intermediate layer containing a low-molecular-weight charge transport material as an active ingredient between a charge-generating layer 13 mainly composed of a polymer charge transport material and a charge-generating material and a charge transport layer 15 mainly composed of a polymer charge-transport material. 17 is provided.

Next, the detailed constitution of the electrophotographic photosensitive member of the present invention will be described in detail. Examples of the conductive support 11 include those exhibiting a conductivity of 10 ¹⁰ Ω or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, silver, gold, and platinum, and metals such as tin oxide and indium oxide. A film or cylindrical plastic or paper coated with an oxide by vapor deposition or sputtering, or a plate of aluminum, aluminum alloy, nickel, stainless steel, etc. I. , I .; I. , Extrusion, drawing, etc., after forming into a tube, cutting, super finishing,
A tube or the like surface-treated by polishing or the like can be used.

The charge generation layer 13 is a layer mainly composed of a charge generation material and a polymer charge transport material. Inorganic and organic materials are used for the charge generation material, and as a representative,
Monoazo pigment, disazo pigment, trisazo pigment, perylene pigment, perinone pigment, quinacridone pigment, quinone condensed polycyclic compound, squaric acid dye, phthalocyanine pigment, naphthalocyanine pigment, azulenium salt dye, selenium, selenium -Tellurium, selenium-arsenic compounds, amorphous silicon and the like are used.
Among them, organic materials represented by azo pigments, perylene pigments, perinone pigments, quinacridone pigments, quinone condensed polycyclic compounds, squaric acid dyes, phthalocyanine pigments, naphthalocyanine pigments, azulhenium salt dyes, and the like Good results are obtained when is used. The charge generation materials are used alone or in combination of two or more.

The polymer charge transporting material that can be used for the charge generation layer 13 of the present invention is not particularly limited, but includes the following. (A) Polymer having carbazole ring in main chain and / or side chain For example, JP-A-50-82056, JP-A-54-82056
Compounds described in JP-A-9632, JP-A-54-11737 and JP-A-4-183719 are exemplified. (B) Polymer having a hydrazone structure in the main chain and / or side chain For example, JP-A-57-78402, JP-A-3-5-5
Compounds described in Japanese Patent No. 0555 are exemplified. (C) Polysilylene polymer For example, JP-A-63-285552,
Compounds described in JP-A-194497 and JP-A-5-70595 are exemplified. (D) Polymer having a tertiary amine structure in the main chain and / or side chain For example, poly-p-vinyltriphenylamine, JP-A-1-1728, JP-A-1-13061, and JP-A-1-13061 -19049, JP-A-1-105260, JP-A-2-167335, JP-A-5-40
Compounds described in JP-A-350-350 and JP-A-5-66598 are exemplified. (E) Other polymers For example, a formaldehyde condensation polymer of nitropyrene, JP-A-51-73888, JP-A-56-15074
Compounds described in No. 9 are exemplified.

The polymer charge transporting material used in the present invention includes not only the above-mentioned polymers but also copolymers of known monomers,
Block polymer, graft polymer, star polymer,
It is also possible to use, for example, a crosslinked polymer having an electron donating group as disclosed in JP-A-3-109406. The polymer charge transporting material used in the present invention is, among the materials described above,
Use of those belonging to (b), (c), and (d) can provide a suitable effect. The polymer charge transporting material used in the present invention does not necessarily have to have a high molecular weight, and may be a so-called oligomer. Therefore, the weight average molecular weight of the polymer is preferably 1,000 or more, more preferably 2,000 to 2,000,000.
The polymer charge transporting material used in the present invention exhibits good photosensitivity when its ionization potential (Ip) is smaller than the value obtained by adding 0.2 eV to the Ip value of the charge generating material. The amount of the polymer charge transporting material used in the charge generation layer of the present invention is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, based on 1 part by weight of the charge generation material. .

In the second aspect, the charge generation layer 13 further contains a low molecular charge transport material in addition to the charge generation material and the polymer charge transport material. Are used.

The low-molecular charge transport materials include a hole transport material and an electron transport material. Examples of low molecular charge transport materials include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 4,8-trinitrothioxanthone,
2,6,8-trinitro-4H-indeno [1,2-
b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, 3,5-dimethyl-3 ', 5'-ditertiarybutyl-4,4'
-A known electron accepting substance such as diphenoquinone. Examples of low-molecular-weight hole transport materials include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, Other known materials such as a triarylmethane derivative, a 9-styrylanthracene derivative, a pyrazoline derivative, a divinylbenzene derivative, a hydrazone derivative, an indene derivative, and a butadiene derivative are used. These low molecular charge transport materials are used alone or in combination of two or more. The amount of the low molecular charge transporting material to be added to the charge generating layer is suitably from 0.03 to 10 parts by weight based on 1 part by weight of the charge generating material.

In the charge generation layer 13 of the present invention, an electrically inactive binder resin may be used in combination, if necessary. As the binder resin, polyamide, polyurethane, polyester, epoxy resin, polyketone,
Polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polyacrylamide, and the like are used.

The charge generation layer 13 comprises a charge generation substance together with a polymer charge transport material and a low molecular charge transport material as appropriate.
Tetrahydrofuran, cyclohexanone, dioxane,
It can be formed by dispersing in a ball mill, an attritor, a sand mill or the like using an appropriate solvent such as 2-butanone or dichloroethane, diluting the dispersion liquid appropriately, and applying. The coating can be performed by a dip coating method, a spray coating method, a bead coating method, or the like. Alternatively, a method of forming a charge generation layer by mixing a dispersion of a charge generation material and a solution containing a polymer charge transport material or by spray coating independently may be employed. In particular, the spray coating method is an extremely effective method because an electrophotographic photoreceptor having excellent abrasion resistance during repeated use, low residual potential, and high-speed response can be produced in a stable state as described above. .

Hereinafter, the spray coating method will be described in detail. One embodiment of the spray coating method of the present invention is a method of simultaneously coating and forming a charge generation layer using two or more spray heads. In this case, the charge generation layer is divided into two coating liquids consisting of a charge generation substance dispersion formed with a solvent and a binder resin in which the dispersion state of the charge generation substance is stable and a dispersion containing a polymer charge transport material. It is preferable to adopt a method in which these coating liquids are simultaneously coated and formed using two different spray heads. As the coating device, any spray device having two or more heads may be used, and any general or known coating device can be used. The thickness of the charge generation layer 13 is 0.01 to 5 μm
The degree is appropriate, and preferably 0.1 to 2 μm.

The charge transport layer 15 is a layer mainly composed of a polymer charge transport material. The charge transport layer 15 can be formed by dissolving or dispersing the polymer charge transport material in a suitable solvent, for example, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, cyclohexanone, etc., and applying and drying.
As the polymer charge transporting material, known materials including the above-mentioned polymer having an electron donating group can be used. However, those having a small molecular weight are not desirable, and those having a weight average molecular weight of 1,000 to 2,000,000 are preferred, and more preferably 10,000 to 1,000,000. However, the molecular weight is substantially determined by the solubility of the polymer in a solvent, the solution viscosity at a given molecular weight, and the like.

The polymer charge transporting material used in the charge transporting layer of the present invention has an ionizing potential (Ip)
The Ip value of the charge generation material used for the charge generation layer is 0.2
When the value is smaller than the value obtained by adding eV, good light sensitivity is exhibited. The charge transport layer 15 may have
A plasticizer, a leveling agent, and the like can be added, and if necessary, a binder resin can be used in combination.

In the first aspect, the charge transport layer 15 further contains a low molecular charge transport material. As the low molecular charge transport material, the above-mentioned materials are preferably used. The amount of the low molecular weight charge transporting material contained in the charge transporting layer is suitably from 0.1 to 60% by weight.

In the charge transport layer, a binder resin may be used in combination, if necessary. Examples of such binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and polyacetic acid. Vinyl, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd A thermoplastic or thermosetting resin such as a resin may be used. The amount of the binder resin used is 0 to 1 based on 100 parts by weight of the polymer charge transporting material.
00 parts by weight is suitable. As the plasticizer that may be added to the charge transport layer 15, those used for plasticity of general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount of the plasticizer used is 0 to the polymer component. About 30% by weight is appropriate. As the leveling agent, silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain are used in an amount of 0 to 1 wt. % Is appropriate. The thickness of the charge transport layer 15 is suitably about 5 to 100 μm.

The electrophotographic photoreceptor according to the third aspect is provided with an intermediate layer 17 containing a low molecular charge transport material as an effective component between the charge generation layer and the charge transport layer. As the low molecular charge transport material, the above-mentioned materials are preferably used. If necessary, a binder resin is used in combination for this intermediate layer. As the binder resin, the materials described above for the charge generation layer and the charge transport layer can be used. Middle layer 1
As a forming method of 7, the usual coating method as described above is employed. The thickness of the intermediate layer 17 is 0.05 to 2 μm.
The degree is appropriate.

In the electrophotographic photoreceptor of the present invention, an undercoat layer can be provided between the conductive support 11 and the photosensitive layer. The undercoat layer generally contains a resin as a main component. However, considering that the photosensitive layer is coated thereon with a solvent, these resins are preferably resins having high solubility resistance to general organic solvents. Such resins include polyvinyl alcohol, casein, water-soluble resins such as sodium polyacrylate, copolymerized nylon, alcohol-soluble resins such as methoxymethylated nylon, polyurethane, melamine resin, alkyd-melamine resin, epoxy resin, and the like. Curable resins that form a three-dimensional network structure are exemplified.

For the purpose of preventing moiré and reducing residual potential, the undercoat layer may be added with a fine powder of a metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide or the like. Is also good. These undercoat layers can be formed using an appropriate solvent and a coating method as in the above-described photosensitive layer. Further, as an undercoat layer of the present invention, a silane coupling agent, a titanium coupling agent, a chromium
A metal oxide layer formed by a gel method or the like is also useful. In addition, the undercoat layer of the present invention is provided with Al ₂ O ₃ by anodic oxidation, an organic substance such as polyparaxylylene (parylene), SiO, SnO ₂ , TiO ₂ , ITO, CeO ₂
And the like provided with an inorganic substance by a vacuum thin film production method can also be used favorably. The thickness of the undercoat layer is suitably from 0 to 5 μm.

In the electrophotographic photosensitive member of the present invention, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. Materials used for this are ABS resin, AC
S resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene, polyethylene terephthalate,
Polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone,
Examples of resins include AS resin, AB resin, BS resin, polyurethane, polyvinyl chloride, polyvinylidene chloride, and epoxy resin. For the purpose of improving abrasion resistance, the protective layer may be made of a fluororesin such as polytetrafluoroethylene, a silicone resin, or a material in which an inorganic material such as titanium oxide, tin oxide or potassium titanate is dispersed in these resins. Can be added. As a method of forming the protective layer,
A normal coating method is employed. The thickness of the protective layer is
About 0.5 to 10 μm is appropriate. In addition to the above, known materials such as iC and a-SiC formed by a vacuum thin film manufacturing method can be used as the protective layer.

In the present invention, another intermediate layer may be provided between the photosensitive layer and the protective layer. The intermediate layer generally uses a binder resin as a main component. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a normal coating method is employed as described above. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.

[0041]

The present invention will now be described in more detail with reference to the following Examples, which are provided only for illustrating the present invention in detail and do not limit the present invention. All parts in the examples are parts by weight.

Example 1 A coating solution for a charge generation layer and a coating solution for a charge transport layer having the following compositions were sequentially applied on a polyethylene terephthalate film having an aluminum conductive layer, and dried and dried to a thickness of 0.2 μm.
And a charge transport layer having a thickness of 18 μm. [Coating solution for charge generation layer] 3 parts of charge generation material having the following structure

Embedded image 3 parts of polymer having the following structure

Embedded image 180 parts of cyclohexanone 75 parts of 2-butanone [Coating solution for charge transport layer] 10 parts of polymer having the following structure

Embedded image 5 parts of low molecular charge transport material having the following structure

Embedded image 70 parts of methylene chloride

Comparative Example 1 The polymer used in the charge generation layer in Example 1 was replaced with polyvinyl butyral (Slec B, manufactured by Sekisui Chemical Co., Ltd.).
MS), except that the photoreceptor was replaced with (MS).

Example 2 A coating liquid for a charge generation layer and a coating liquid for a charge transport layer having the following compositions were sequentially coated on a polyethylene terephthalate film having an aluminum conductive layer, and dried to form a 0.3 μm thick film.
And a charge transport layer having a thickness of 23 μm. [Coating solution for charge generation layer] 3 parts of charge generation material having the following structure

Embedded image 3 parts of polymer having the following structure

Embedded image 2 parts of low molecular charge transport material having the following structure

Embedded image 180 parts of tetrahydrofuran 100 parts of 2-butanone [Coating solution for charge transport layer] 10 parts of polymer having the following structure

Embedded image 80 parts of tetrahydrofuran

Example 3 The photoconductor of Example 3 was prepared in the same manner as in Example 2 except that the polymer used in the charge transport layer was replaced with a polymer having the following structure. Was prepared.

Embedded image

Comparative Example 2 Comparative Example 2 was carried out in the same manner as in Example 2 except that the polymer used for the charge generation layer was replaced with a phenoxy resin (VYHH manufactured by UCC). Was produced.

Example 4 A coating liquid for a charge generation layer, a coating liquid for an intermediate layer, and a coating liquid for a charge transport layer having the following compositions were sequentially coated and dried on an aluminum plate having a thickness of 0.2 mm. A charge generating layer having a thickness of 23 μm, an intermediate layer having a thickness of 0.3 μm, and a charge transporting layer having a thickness of 20 μm were formed. [Coating solution for charge generation layer] 4 parts of charge generation material having the following structure

Embedded image 2 parts of polymer having the following structure

Embedded image Cyclohexanone 200 parts Methylcyclohexane 90 parts [Coating solution for intermediate layer] Low molecular charge transport material having the following structure 10 parts

Embedded image Polyvinyl butyral 6 parts (Sekisui Chemical Co., Ltd .: Eslec BL-1) 2-butanone 50 parts [Charge transport layer coating liquid] Polymer having the following structure 10 parts

Embedded image 80 parts of methylene chloride

Comparative Example 3 A photoconductor of Comparative Example 3 was prepared in the same manner as in Example 4, except that the low molecular charge transporting material was not added to the intermediate layer.

Example-5 A coating liquid for a charge transport layer, a coating liquid for a charge generation layer, and a coating liquid for a protective layer having the following compositions were sequentially coated and dried on an aluminum plate having a thickness of 0.2 mm. A charge transport layer having a thickness of 20 μm, a charge generation layer having a thickness of 0.4 μm, and a protective layer having a thickness of 3 μm were formed. [Charge transport layer coating solution] 10 parts of polymer having the following structure

Embedded image 12 parts of low molecular charge transport material having the following structure

Embedded image 80 parts of tetrahydrofuran [Coating liquid for charge generating layer] 3 parts of charge generating substance having the following structure

Embedded image 4 parts of the following polymer

Embedded image Tetrahydrofuran 100 parts Cyclohexanone 100 parts [Coating solution for protective layer] Tin oxide containing antimony oxide 10% 30 parts Styrene-methacrylic acid-N-methylol methacrylamide resin 10 parts Toluene 80 parts n-butanol 70 parts

Comparative Example 4 Comparative Example 4 was performed in the same manner as in Example 5 except that the polymer used for the charge generation layer was replaced by polysulfone (P-1700, manufactured by Nissan Chemical Industries, Ltd.). 4 was prepared.

Example -6 An undercoat layer coating solution, a charge transport layer coating solution and a charge generation layer coating solution having the following compositions were sequentially coated and dried on an aluminum plate having a thickness of 0.2 mm. An undercoat layer having a thickness of 0.5 μm, a charge transport layer having a thickness of 24 μm, and a charge generation layer having a thickness of 0.3 μm were formed. [Undercoat layer coating liquid] Water-soluble polyvinyl acetal 15 parts (Sekisui Chemical: W-101 10% aqueous solution) Water 20 parts Methanol 50 parts [Charge transport layer coating liquid] Polycarbonate 6 parts (Teijin Chemicals: Bread Light C-1400) 10 parts of a polymer having the following structure

Embedded image 80 parts of tetrahydrofuran [Coating liquid for charge generating layer] 3 parts of charge generating substance having the following structure

Embedded image 2 parts of low molecular charge transport material having the following structure

Embedded image Polymer with the following structure

Embedded image Cyclohexanone 200 parts 4-Methyl-2-pentanone 90 parts

Example 7 A coating liquid for a charge generation layer, a coating liquid for an intermediate layer, and a coating liquid for a charge transport layer having the following compositions were sequentially coated and dried on an aluminum plate having a thickness of 0.2 mm. A charge generating layer having a thickness of 23 μm, an intermediate layer having a thickness of 0.3 μm, and a charge transporting layer having a thickness of 20 μm were formed. [Charge transport layer coating solution] 10 parts of polymer having the following structure

Embedded image Toluene 80 parts [Coating solution for intermediate layer] Low molecular charge transport material having the following structure 15 parts

Embedded image Polyethylene glycol 3 parts (PEG 6000S, manufactured by Sanyo Chemical Industries) 2-butanone 150 parts [Coating solution for charge generating layer] 4 parts of charge generating material having the following structure

Embedded image 2 parts of polymer having the following structure

Embedded image Cyclohexanone 200 parts Methylcyclohexane 90 parts

Comparative Example-5 A photoconductor of Comparative Example-5 was produced in the same manner as in Example-7, except that no intermediate layer was provided.

Each of the above photoreceptors was attached to an electrostatic paper analyzer [SP-428: manufactured by Kawaguchi Electric Works], and the following measurements were performed. Voltage Vm (V) after charging for 20 seconds at a corona discharge voltage of +5.6 kV (or -5.3 kV) and potential Vo after dark decay for 20 seconds
(V), the residual potential V _R (V) after 20 seconds of exposure to white light having an intensity of 6 lux, and the exposure E1 / 2 [lux · sec] required to attenuate the potential Vo to １ ／ were measured. . The potential holding ratio is defined as follows. Potential holding ratio = Vo / Vm Further, charging and exposure under the above conditions were simultaneously performed for 30 minutes to fatigue the photoreceptor, and then the photoreceptor characteristics were measured in the same manner as above. Table 1 shows the results.

[0055]

[Table 1]

Example-8 The coating liquid for the charge generation layer in Example 1 was changed to the following (coating liquid for the charge generation layer 1, coating liquid for the charge generation layer 2), and the charge generation layer was The two coating heads were used to apply the respective coating liquids at the same time so that the discharge amount was 1: 1 to produce a charge generation layer of 0.2 μm in exactly the same manner. [Charge Generating Layer Coating Solution 1] 3 parts of a charge generating substance having the following structure

Embedded image 180 parts of cyclohexanone 75 parts of 2-butanone [Coating liquid for charge generating layer 2] 3 parts of polymer having the following structure

Embedded image Cyclohexanone 180 parts 2-butanone 75 parts

Example-9 The coating liquid for the charge generation layer in Example-2 was changed to the following (coating liquid for the charge generation layer 1, coating liquid for the charge generation layer 2), and Were prepared in exactly the same manner except that a 0.2 μm charge generation layer was formed by simultaneously applying the respective coating liquids by using two spray heads so as to have a discharge amount of 1: 1. [Charge Generating Layer Coating Solution 1] 3 parts of a charge generating substance having the following structure

Embedded image 180 parts of tetrahydrofuran 100 parts of 2-butanone [Coating liquid for charge generating layer 2] 3 parts of polymer having the following structure

Embedded image Tetrahydrofuran 180 parts 2-butanone 100 parts

Example 10 The charge generation layer coating liquid in Example 4 was changed to the following (charge generation layer coating liquid 1, charge generation layer coating liquid 2). Were prepared in exactly the same manner except that a 0.2 μm charge generation layer was formed by simultaneously applying the respective coating liquids by using two spray heads so as to have a discharge amount of 1: 1. [Charge Generating Layer Coating Solution 1] 4 parts of a charge generating material having the following structure

Embedded image Cyclohexanone 200 parts Methylcyclohexane 90 parts [Charge generating layer coating liquid 2] Polymer having the following structure 3 parts

Embedded image Cyclohexanone 180 parts Methylcyclohexane 90 parts

Each of the coating liquids described in Examples 8 to 10 and Comparative Examples 1 to 2 and 4 was prepared, and was coated at an initial stage (within one day) and three months later to prepare a photoreceptor. At this time, the state of each coating solution and the film forming property (visual observation of the coating film) were evaluated. Table 2 shows the evaluation results.

[0060]

[Table 2]

The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein a charge generation layer comprising at least a charge generation layer and a polymer charge transport material, and a charge mainly comprising the polymer charge transport material are provided on a conductive support. In a photoreceptor having a transport layer laminated thereon, the charge generation layer or the charge transport layer or the intermediate layer contains a low-molecular charge transport material, so that the photoreceptor has a small dark decay even after repeated use and a small increase in residual potential. And high sensitivity and high-speed optical response. The method for producing an electrophotographic photoreceptor according to claim 4 or 5, wherein the photosensitive layer is coated on a conductive support with at least a polymer charge transport material and at least a charge generation material. Is a process of simultaneously applying and forming a film using two or more spray heads each. Therefore, the electrophotographic photoreceptor has excellent abrasion resistance when used repeatedly, has a low residual potential, and has high-speed response. Can be manufactured in a stable state.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a schematic sectional view of the electrophotographic photosensitive member of the present invention.

FIG. 3 is a schematic sectional view of the electrophotographic photosensitive member of the present invention.

FIG. 4 is a schematic sectional view of the electrophotographic photosensitive member of the present invention.

────────────────────────────────────────────────── ─── front page continued (51) Int.Cl. ⁷ identifications FI G03G 5/07 G03G 5/07 (56) references Patent Rights 5-34938 (JP, a) Patent Rights 3-296768 (JP JP-A-6-19169 (JP, A) JP-A-3-269538 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/00

Claims (5)

(57) [Claims] 1. An electrophotographic photoreceptor comprising a charge generating layer containing a charge generating material and a polymer charge transporting material as effective components, and a charge transporting layer comprising a polymer charge transporting material laminated on a conductive support. , Wherein the charge transport layer contains a low molecular charge transport material. 2. An electrophotographic photoreceptor comprising: a charge generating layer containing a charge generating material and a polymer charge transporting material as effective components; and a charge transporting layer comprising a polymer charge transporting material laminated on a conductive support. 2. The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a low molecular charge transport material. 3. An electrophotographic photoreceptor comprising a charge generating layer containing a charge generating material and a polymer charge transporting material as effective components and a charge transporting layer comprising a polymer charge transporting material laminated on a conductive support. 3. An electrophotographic photoreceptor according to claim 1, wherein an intermediate layer mainly composed of a low-molecular charge transport material is provided between said charge generation layer and said charge transport layer. 4. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the charge generation layer is coated and formed simultaneously using two or more spray heads. 5. A coating liquid containing a charge-generating substance dispersion formed with a solvent and a binder resin in which a dispersion state of the charge-generating substance is stable and a coating liquid containing a polymer charge-transporting material, using two or more spray heads. 5. The method for producing an electrophotographic photoreceptor according to claim 4, wherein the film is formed simultaneously by coating.