JP2001265028A - Method for producing electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an electrophotographic photoreceptor by which the whitening of a photosensitive layer which causes image trouble is prevented by improving a solvent used in a coating fluid for the photosensitive layer and a photoreceptor having good performance can be obtained. SOLUTION: In the method for producing an electrophotographic photoreceptor including a step for forming a photosensitive layer containing at least an electric charge generating material, an electric charge transferring material and a resin binder on an electrically conductive substrate, a mixed solvent prepared by mixing (A) at least one of methylene chloride and tetrahydrofuran with (B) at least one solvent having <=80 mmHg vapor pressure at 25 deg.C and <=110 cal/g of heat of evaporation at the boiling point is used as a solvent for a coating fluid for the photosensitive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor (hereinafter, also simply referred to as "photoreceptor").
The present invention relates to a method for manufacturing an electrophotographic photoreceptor mainly comprising a conductive substrate and a photosensitive layer containing an organic material and used for an electrophotographic printer, a copying machine or the like.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member has a basic structure in which a photosensitive layer having a photoconductive function is laminated on a conductive substrate. In recent years, research and development has been actively conducted on so-called organic electrophotographic photoreceptors, which use organic compounds as functional components responsible for charge generation and transport, due to advantages such as material diversity, high productivity, and safety. Therefore, application to copiers, printers, and the like is being promoted.

A photoreceptor must have a function of retaining surface charges in a dark place, a function of receiving light to generate charges, and a function of receiving light and transporting charges generated.
A so-called single-layer type photoreceptor having a single-layer photosensitive layer having both of these functions, a charge-generating layer mainly responsible for charge generation at the time of photoreception, and a function of holding surface charges in a dark place and at the time of photoreception There is a so-called function-separated layered photoconductor in which functions are separated into a charge transport layer which has a function of transporting charges generated in the charge generation layer and a charge transport layer.

As described above, the organic photoreceptor has various structures and compositions. The method for producing the organic photoreceptor is to use a coating solution for a photosensitive layer formed by dissolving and / or dispersing a photosensitive layer material in a solvent. Basically, in that the photosensitive layer is formed by applying the coating solution on top and then drying to remove the solvent in the coating solution for the photosensitive layer, and / or curing the coating solution for the photosensitive layer by heating. It is almost the same. When the photoconductor has a plurality of layers, the constituent materials are dissolved in a solvent for each layer to prepare a coating solution for the photosensitive layer, and the steps of coating, drying and / or curing are repeated one layer at a time. Each layer is laminated to form a photoreceptor. In the production of a laminated photoreceptor, the charge generation layer may be formed by vacuum deposition of a photoconductive substance, but it is extremely rare that all layers are formed by a process other than the coating method. Is generally formed by a coating method.

[0005]

In recent years, along with the automation of offices, the size of electrophotographic apparatuses has been reduced,
As the weight has been reduced, the size and weight of the electrophotographic photosensitive member have been required to be reduced.
In order to realize a photoconductor capable of meeting such demands, it is necessary to form a photosensitive layer with a high-performance photoconductive material.
Until now, various functional materials have been developed and proposed.
In such a functional material, since the solubility and dispersibility in a solvent are inferior, the material may be precipitated in a coating film to cause a local defect in some cases.

In the case of a general drum-shaped photoreceptor,
As described above, a photosensitive layer coating solution formed by dissolving a photosensitive layer material in a solvent is applied on a cylindrical conductive substrate, dried, and / or cured.
When the thickness of the substrate on which the coating liquid is applied is reduced, a so-called whitening phenomenon occurs in which the photosensitive layer becomes cloudy white in the process from immediately after the application of the coating liquid on the substrate to drying and / or curing. A problem arises in that a sensitive photosensitive layer cannot be obtained. When the photoreceptor having such whitening is applied to an electrophotographic apparatus, the charge potential on the photoreceptor surface and the potential after exposure become non-uniform, and as a result, unevenness occurs in an image.

[0007] Further, since there is an improvement in printing durability as a market demand for the photoreceptor, the thickness of the charge transport layer in the laminated type photoreceptor and the thickness of the photosensitive layer in the single layer type photoreceptor are:
It is necessary to form it at 25 μm or more. On the other hand, as the film thickness increases, the whitening phenomenon is more likely to occur. Therefore, measures for preventing whitening are an important issue from this point as well.

In order to solve the above-mentioned problem, as a solvent used for a coating solution for a photosensitive layer of a photosensitive member, a material for a photosensitive layer can be uniformly dissolved or dispersed, and is coated on a conductive substrate. In this case, it is necessary to use a material that evaporates from the photosensitive layer at an appropriate speed. If the solvent evaporates rapidly, heat is removed from the substrate and the temperature difference between the surrounding environment and the photoconductor increases, so that moisture in the air condenses on the surface of the photoconductor layer, causing whitening of the photoconductor layer. On the other hand, if the evaporation rate of the solvent is low, the coating film drips and the entire photosensitive layer cannot be formed in a uniform thickness.

However, since it is extremely difficult to satisfy good solubility and dispersibility in the photosensitive layer material and an appropriate evaporation rate with one kind of solvent, it has sufficiently satisfactory performance as a solvent used for a coating solution for a photosensitive layer. At present, things have not yet been obtained.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to improve the solvent used in the coating solution for the photosensitive layer, thereby preventing the photosensitive layer from causing whitening, which is a cause of image trouble, and having good performance. An object of the present invention is to provide a method for manufacturing a photoconductor for electrophotography, which can obtain a photoconductor.

[0011]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, as a solvent used for a coating solution for a photosensitive layer, a solvent having extremely high solubility or high dispersibility in a photosensitive layer material has been specified. A good solvent for electrophotography without whitening by using a mixed solvent of the above solvent and a specific solvent having a certain solubility or dispersibility in the photosensitive layer material and having a low vapor pressure and low heat of evaporation. The inventors have found that a photoconductor can be manufactured, and have completed the present invention.

That is, in order to solve the above-mentioned problems, a method of manufacturing an electrophotographic photoreceptor of the present invention comprises forming a photosensitive layer containing at least a charge generation material, a charge transport material and a binder resin on a conductive substrate. In the method for producing an electrophotographic photoreceptor including the step of: (A) at least one of methylene chloride or tetrahydrofuran as a coating liquid solvent for a photosensitive layer coating liquid, and (B) a vapor pressure of 80 mmHg at 25 ° C. Below, and the heat of evaporation at the boiling point is 1
It is characterized by using a mixed solvent obtained by mixing at least one kind of solvent of 10 cal / g or less.

In the present invention, it is preferable that toluene or tetrahydropyran is used as the solvent (B), and the compounding amount is 5 to 50% by weight based on the coating liquid solvent. Preferably, the photosensitive layer has a thickness of 2
It is formed to 5 μm or more.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in more detail. In the method for producing an electrophotographic photoreceptor of the present invention, as a coating liquid solvent for a photosensitive layer coating liquid used when forming a photosensitive layer on a conductive substrate,
(A) at least one of methylene chloride and tetrahydrofuran, and (B) a vapor pressure at 25 ° C. of 80
mmHg or less and the heat of evaporation at the boiling point is 110 c
It is important to use a mixed solvent obtained by mixing at least one of the solvents of al / g or less, and other production conditions are not particularly limited. The photosensitive member to which the method of the present invention can be applied is not limited, and can be applied to photosensitive members having various layer configurations.

As the solvent (B) according to the present invention, it is particularly preferable to use toluene or tetrahydropyran. As the ratio of the solvent (A) and the solvent (B), the solvent (B) is preferably blended in an amount of 5 to 50% by weight, more preferably 10 to 50% by weight, based on the entire coating liquid forming solvent. .

Hereinafter, the photoreceptor according to the present invention will be described in detail. FIGS. 1A to 1C are conceptual cross-sectional views showing one embodiment of a photoconductor according to a manufacturing method of the present invention.
1 denotes a conductive substrate, 2 denotes an undercoat layer, 3 denotes a charge generation layer, 4 denotes a charge transport layer, 5 denotes a surface protective layer, and 6 denotes a photosensitive layer. FIGS. 1A and 1B show a so-called stacked type photoreceptor, in which a photosensitive layer 6 is separated into a charge generation layer 3 and a charge transport layer 4, and is a function separation type photoreceptor. The photosensitive layer in FIG. 1A is of a negative charge type in which a charge generation layer and a charge transport layer are laminated in this order, and the photosensitive layer in FIG. 1B is a charge transport layer and a charge generation layer in the reverse order of FIG. It is a stacked positively charged type.
FIG. 1C shows a so-called single-layer type photoconductor in which a single layer contains a charge generating substance and a charge transporting substance, and this photosensitive layer is mainly of a positive charging type.

The conductive substrate 1 serves not only as an electrode of the photoreceptor but also as a support for the other layers, and may be cylindrical, plate-like or film-like. A conductive material may be applied to metal, glass, resin, or the like.

The undercoat layer 2 is made of a layer mainly composed of a resin or an oxide film of alumite or the like, and prevents the injection of unnecessary electric charges from the conductive substrate 1 to the photosensitive layer 6; It can be provided as needed for the purpose of improving the adhesiveness of the layer. Resin binders include polyethylene, polypropylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, silicone resin, polyvinyl butyral resin, polyamide resin, and copolymers thereof. Can be used in combination as appropriate. Further, metal oxide fine particles and the like may be contained in the resin binder. Such metal oxide fine particles include SiO ₂ , TiO ₂ , In ₂ O ₃ , ZrO
₂ etc. can be used.

The charge generating layer 3 is formed by vacuum-depositing an organic photoconductive substance or by applying a coating liquid in which particles of the organic photoconductive substance are dispersed in a resin binder to receive light. Generate electric charge. It is important that the charge generation efficiency is high, and at the same time, the property of injecting the generated charge into the charge transport layer 4 is small, and it is desirable that the electric field dependence is small and the injection is good even at a low electric field. Since the charge generation layer only needs to have a charge generation function, its thickness is determined by the light absorption coefficient of the charge generation substance, and is generally 5 μm or less, preferably 1 μm or less. The charge generation layer is mainly composed of a charge generation substance,
It can also be formed by adding a charge transport material or the like. As the charge generating substance, phthalocyanine pigments, polycyclic quinone pigments such as anthrone, perylene pigments,
Perinone pigments, squarylium pigments, thiapyrylium pigments, quinacridone pigments and the like can be used, and these pigments may be used in combination. As the resin binder used for the charge generation layer, polycarbonate resin, polyester resin, polyamide resin, polyurethane resin,
An epoxy resin, a polyvinyl butyral resin, a polyvinyl acetal resin, a vinyl chloride resin, a phenoxy resin, a silicone resin, a methacrylic acid ester resin, and a copolymer thereof can be used in an appropriate combination.

The charge transport layer 4 is a coating film in which a charge transport material is dispersed in a resin binder. The charge transport layer 4 holds the charge of the photoreceptor as an insulator layer in a dark place, and is injected from the charge generation layer when receiving light. Exhibits the function of transporting charges. The charge transport layer 4 is mainly composed of a charge transport material and a resin binder. In the present invention, an additive such as an antioxidant may be added for the purpose of improving stability against ozone, light or heat. it can. Examples of the charge transport material include hydrazone compounds, styryl compounds, benzidine compounds, stilbene compounds, pyrazoline compounds, pyrazolone compounds, oxadiazole compounds, other amine compounds, and charge transport polymers such as polyvinyl carbazole. In addition, as the resin binder, a polycarbonate resin, a polyester resin, a polystyrene resin, a polymer and a copolymer of methacrylic acid ester, and the like can be used. However, mechanical, chemical and electrical stability, adhesion, etc. Besides, the compatibility with the charge transport material is weight. In the case where an antioxidant is added to the charge transporting layer, it is preferably 0.001 to 1 based on 100 parts by weight of the total of the charge transporting substance and the binder resin.
0 parts by weight, more preferably 0.005 to 5 parts by weight. In order to maintain a practically effective surface potential, the thickness of the charge transport layer is preferably in the range of 3 to 50 μm, and more preferably 10 to 40 μm.

The surface protective layer 5 can be provided as needed, and is made of a chemically stable substance which has excellent durability against mechanical stress. In the dark place, it has the function of receiving and holding the charge of corona discharge, and has the ability to transmit light that the charge generation layer is sensitive to, transmitting light at the time of exposure and reaching the charge generation layer, and generating It is necessary to neutralize and eliminate surface charges by receiving charges. Surface protective layer 5
Are polyvinyl butyral resin, polycarbonate resin, nylon resin, polyurethane resin, polyarylate resin, modified silicone resin such as acrylic-modified silicone resin, epoxy-modified silicone resin, alkyd-modified silicone resin, polyester-modified silicone resin, urethane-modified silicone resin, etc. It is possible to apply a silicone resin or the like as a hard coat agent. These modified silicone resins can be used alone, but for the purpose of further improving durability, SiO ₂ , TiO ₂ , In ₂ O ₃ , ZrO ₂
A mixture with a condensate of a metal alkoxy compound capable of forming a coating containing ₂ as a main component is preferable. The thickness of the surface protective layer depends on the composition of the protective layer, but can be arbitrarily set within a range that does not cause adverse effects such as an increase in residual potential when used repeatedly and continuously.

The photosensitive layer 6 in the case of a single layer type is a coating film in which a charge generating substance and a charge transporting substance are dispersed in a resin binder.
Charge transport materials, resin binders and antioxidants can be used as well. The thickness of the single-layer type photosensitive layer 6 is 3 to 50 μm in order to maintain a practically effective surface potential.
, More preferably 10 to 40 μm. In the present invention, in both cases of the laminated type and the single-layer type, it is preferable to form the photosensitive layer to a thickness of 25 μm or more. The effect can be obtained most remarkably.

Further, in both the laminated type and the single-layer type photoreceptors, for the purpose of improving the sensitivity, reducing the residual potential, and reducing the characteristic fluctuation during repeated use, etc.
If necessary, an electron accepting substance can be contained in the photosensitive layer. Examples of such electron acceptors include succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, pyromellitic acid, and trimellitic acid. And compounds having a high electron affinity such as, for example, trimellitic anhydride, phthalimide, 4-nitrophthalimide, tetracyanoethylene, tetracyanoquinodimethane, chloranil, bromanyl and o-nitrobenzoic acid.

In forming a photosensitive layer in the present invention,
A normal coating method can be used, and the photosensitive layer material, together with the mixed solvent according to the present invention as a coating solution solvent for the photosensitive layer coating solution, a paint shaker, a ball mill, a sand mill,
A coating solution is prepared by dissolving and dispersing by a known method such as ultrasonic dispersion, and this coating solution is applied by a known coating method such as a dip coating method, a spray coating method, and a bar coating. A drying step for evaporating the solvent and forming a uniform photosensitive layer is performed. As the drying step, there is vacuum drying performed without changing the temperature, but a drying furnace equipped with a heater is generally used.

[0025]

The present invention will be described below in more detail with reference to examples. In the following examples, parts are parts by weight,
% Represents weight% respectively. The vapor pressure and heat of evaporation of the solvent used are shown below. Methylene chloride (vapor pressure: 340 mmHg, heat of evaporation: 7
8.7 cal / g) Tetrahydrofuran (vapor pressure: 130 mmHg, heat of evaporation: 110 cal / g) Butanol (vapor pressure: 4.39 mmHg, heat of evaporation: 14)
1.4 cal / g) 1,3 dioxolane (vapor pressure: 90 mmHg, heat of evaporation:
115 cal / g) Toluene (vapor pressure: 24 mmHg, heat of evaporation: 86.8 c)
al / g) Tetrahydropyran (vapor pressure: 60 mmHg, heat of evaporation:
94 cal / g) In Examples, a charge transport material (hole transport material) having the following formula (CTM-1) was used, and an electron transport material having a structure of the following formula (ETM-1) was used.

Example 1 An undercoat layer dispersion having the above composition was dip-coated on an aluminum base tube, dried at 135 ° C. under normal pressure for 30 minutes, and cooled to form a 0.5 μm-thick undercoat. A layer was formed. Alcohol soluble nylon (CM8000, manufactured by Toray Industries, Inc.) 5 parts Titanium oxide fine particles treated with aminosilane 5 parts Methanol / methylene chloride mixed solvent (6/4) 90 parts

Next, a dispersion for a charge generation layer having the following composition was applied by dip coating, dried at 80 ° C. under normal pressure for 30 minutes, and cooled to form a charge generation layer having a thickness of 0.3 μm. Titanyloxyphthalocyanine 1 part Vinyl chloride copolymer resin (Nippon Zeon: MR110) 1 part Methylene chloride 98 parts

Next, a solution for a charge transport layer having the following composition was applied by dip coating, dried at 120 ° C. under normal pressure for 60 minutes, and cooled to form a charge transport layer having a thickness of 40 μm. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Kasei: TS2050) 10 parts Methylene chloride / toluene mixed solvent (95/5) 80 parts An electrophotographic photoconductor was prepared as described above.

Example 2 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Methylene chloride / toluene mixed solvent (90/10) 80 parts

Example 3 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Methylene chloride / toluene mixed solvent (70/30) 80 parts

Example 4 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Methylene chloride / toluene mixed solvent (50/50) 80 parts

Example 5 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Methylene chloride / toluene mixed solvent (30/70) 80 parts

Example 6 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Methylene chloride / tetrahydropyran mixed solvent (95/5) 80 parts

Example 7 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemicals: TS2050) 10 parts Methylene chloride / tetrahydropyran mixed solvent (90/10) 80 parts

Example 8 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Methylene chloride / tetrahydropyran mixed solvent (70/30) 80 parts

Example 9 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Methylene chloride / tetrahydropyran mixed solvent (50/50) 80 parts

Example 10 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Methylene chloride / tetrahydropyran mixed solvent (30/70) 80 parts

Example 11 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Tetrahydrofuran / toluene mixed solvent (95/5) 80 parts

Example 12 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Tetrahydrofuran / toluene mixed solvent (90/10) 80 parts

Example 13 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Tetrahydrofuran / toluene mixed solvent (70/30) 80 parts

Example 14 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Tetrahydrofuran / toluene mixed solvent (50/50) 80 parts

Example 15 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemicals: TS2050) 10 parts Tetrahydrofuran / toluene mixed solvent (30/70) 80 parts

Example 16 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Tetrahydrofuran / tetrahydropyran mixed solvent (95/5) 80 parts

Example 17 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Tetrahydrofuran / tetrahydropyran mixed solvent (90/10) 80 parts

Example 18 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemicals: TS2050) 10 parts Tetrahydrofuran / tetrahydropyran mixed solvent (70/30) 80 parts

Example 19 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Tetrahydrofuran / tetrahydropyran mixed solvent (50/50) 80 parts

Example 20 A photoconductor was prepared by the same way as that of Example 1 except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Tetrahydrofuran / tetrahydropyran mixed solvent (30/70) 80 parts

Example 21 A dispersion for an undercoat layer having the following composition was dip-coated on an aluminum base tube, dried at 100 ° C. under normal pressure for 30 minutes, and cooled to obtain a 0.2 μm-thick undercoat. A layer was formed. Vinyl chloride-vinyl acetate-vinyl alcohol copolymer (SOLBIN A: Nissin Chemical Co., Ltd.) (92% vinyl chloride, 3% vinyl acetate, 5% vinyl alcohol) 50 parts Methyl ethyl ketone 950 parts

Next, of the following materials, those other than the binder resin were dispersed in a paint shaker for 1 hour.
A binder resin was added, and the mixture was sufficiently stirred and dissolved. Further, a film was formed using a coating solution prepared by dispersing for 1 hour.
After drying for a minute, a single-layer type photosensitive layer having a thickness of 40 μm was formed. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (CTM-1) Electron transporting substance: 28 parts of electron transporting substance (ETM-1) Silicone oil: KF-54 (Shin-Etsu Chemical) Industrial Co., Ltd.) 0.1 part Binder resin: TUFZET G-400 (Idemitsu Kosan Co., Ltd.) 105 parts Methylene chloride / tetrahydropyran mixed solvent (95/5) 1000 parts

Example 22 A photoconductor was prepared by the same way as that of Example 21 except that the composition of the coating solution for the photosensitive layer was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (CTM-1) Electron transporting substance: 28 parts of electron transporting substance (ETM-1) Silicone oil: KF-54 (Shin-Etsu Chemical) Industrial Co., Ltd.) 0.1 part Binder resin: Toughzet G-400 (Idemitsu Kosan Co., Ltd.) 105 parts Methylene chloride / tetrahydropyran mixed solvent (90/10) 1000 parts

Example 23 A photoconductor was prepared by the same way as that of Example 21 except that the composition of the coating solution for the photosensitive layer was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (CTM-1) Electron transporting substance: 28 parts of electron transporting substance (ETM-1) Silicone oil: KF-54 (Shin-Etsu Chemical) Industrial Co., Ltd.) 0.1 part Binder resin: Toughzet G-400 (Idemitsu Kosan Co., Ltd.) 105 parts Methylene chloride / tetrahydropyran mixed solvent (70/30) 1000 parts

Example 24 A photoconductor was prepared by the same way as that of Example 21 except that the composition of the coating solution for photosensitive layer was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (CTM-1) Electron transporting substance: 28 parts of electron transporting substance (ETM-1) Silicone oil: KF-54 (Shin-Etsu Chemical) Industrial Co., Ltd.) 0.1 part Binder resin: Toughzet G-400 (Idemitsu Kosan Co., Ltd.) 105 parts Methylene chloride / tetrahydropyran mixed solvent (50/50) 1000 parts

Example 25 A photoconductor was prepared by the same way as that of Example 21 except that the composition of the coating solution for photosensitive layer was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (CTM-1) Electron transporting substance: 28 parts of electron transporting substance (ETM-1) Silicone oil: KF-54 (Shin-Etsu Chemical) Industrial Co., Ltd.) 0.1 part Binder resin: Toughzet G-400 (Idemitsu Kosan Co., Ltd.) 105 parts Methylene chloride / tetrahydropyran mixed solvent (30/70) 1000 parts

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows, and the thickness of the charge transport layer was changed to 25 μm. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemicals: TS2050) 10 parts Methylene chloride 80 parts

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemicals: TS2050) 10 parts Methylene chloride 80 parts

Comparative Example 3 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemicals: TS2050) 10 parts Tetrahydrofuran 80 parts

Comparative Example 4 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemicals: TS2050) 10 parts Methylene chloride / 1,3 dioxolane mixed solvent (70/30) 80 parts

Comparative Example 5 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Stilbene compound (CTM-1) 2 parts Polycarbonate resin (Teijin Chemical: TS2050) 10 parts Methylene chloride / butanol mixed solvent (70/30) 80 parts

Comparative Example 6 A photoconductor was prepared in the same manner as in Example 1, except that the composition of the coating solution for the charge transport layer was changed as follows. Charge generating substance: X-type metal-free phthalocyanine 2 parts Hole transporting substance: 65 parts of hole transporting substance (CTM-1) Electron transporting substance: 28 parts of electron transporting substance (ETM-1) Silicone oil: KF-54 (Shin-Etsu Chemical) Industrial Co., Ltd.) 0.1 part Binder resin: Toughzet G-400 (Idemitsu Kosan Co., Ltd.) 105 parts Methylene chloride 1000 parts

Evaluation method Each of the photoreceptors prepared in Examples 1 to 25 and Comparative Examples 1 to 6 was dried at room temperature for 30 minutes immediately after coating, and the surface of the coated film was visually observed. If there was whitening, the length was measured with a ruler. The results are shown in Table 1 below.

[0061]

[Table 1]

From the results of the above Examples, it was found that methylene chloride or the like was used alone as a solvent for the coating solution for the photoreceptor, or as a mixed solvent with a solvent having a vapor pressure and heat of evaporation outside the scope of the present invention. In the photoconductor of the comparative example, it was confirmed that a whitening phenomenon occurred when the photoconductor was formed with a film thickness of 25 μm or more. On the other hand, at least one of methylene chloride and tetrahydrofuran as a coating liquid solvent for the photoreceptor, a solvent having a vapor pressure at 25 ° C. of 80 mmHg or less and a heat of evaporation at a boiling point of 110 cal / g or less. Among the photoconductors of Examples using a mixed solvent of at least one of them, no whitening phenomenon was observed even when the film thickness was formed to 40 μm, and it was confirmed that a good photoconductor was obtained.

When the content of tetrahydropyran or toluene is large, the dissolving power is weakened, so that precipitation occurs on the surface of the coating film of the photoreceptor. Is preferably 50% by weight or less.

[0064]

As described above, according to the method for producing an electrophotographic photoreceptor of the present invention, by improving the solvent used in the coating solution for the photosensitive layer, the formation of the photosensitive layer, which is a cause of image disturbance, is improved. By preventing whitening, a photoconductor having good performance can be obtained. In addition, the production method of the present invention is particularly applicable as a method for producing an electrophotographic photosensitive member having a film thickness of 25 μm or more.
It has an excellent effect on prevention of the whitening phenomenon.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a photoreceptor according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive substrate 2 undercoat layer 3 charge generation layer 4 charge transport layer 5 surface protective layer 6 photosensitive layer

Claims (5)

[Claims] 1. A method for producing a photoreceptor for electrophotography, comprising a step of forming a photosensitive layer containing at least a charge generation material, a charge transport material and a binder resin on a conductive substrate. As a liquid solvent, at least one of (A) methylene chloride or tetrahydrofuran and (B) at least one of solvents having a vapor pressure at 25 ° C. of 80 mmHg or less and a heat of evaporation at a boiling point of 110 cal / g or less. A method for producing an electrophotographic photoreceptor, comprising using a mixed solvent obtained by mixing the above types. 2. The method according to claim 1, wherein toluene is used as the solvent (B). 3. The method according to claim 1, wherein tetrahydropyran is used as the solvent (B). 4. The method for producing an electrophotographic photoconductor according to claim 1, wherein the solvent (B) is blended in an amount of 5 to 50% by weight based on the solvent for the coating liquid. 5. The method of manufacturing an electrophotographic photoconductor according to claim 1, wherein said photosensitive layer is formed to a thickness of 25 μm or more.