JP4227288B2 - Coating liquid for charge transport layer and method for producing electrophotographic photosensitive member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a charge transport layer coating solution, and Ru der relates to a process for the preparation of electrophotographic photosensitive member had use it.
[0002]
[Prior art]
Conventionally, as an electrophotographic photoreceptor, an inorganic photoreceptor having a photosensitive layer mainly composed of an inorganic photoconductive compound such as selenium, zinc oxide, cadmium sulfide, and silicon has been widely used. However, these are not always satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc., and some inorganic photoreceptors contain substances harmful to the human body, so there are problems in disposal. is there.
[0003]
In order to overcome the drawbacks of these inorganic photoreceptors, research and development of organic photoreceptors having a photosensitive layer mainly composed of various organic photoconductive compounds have been actively conducted in recent years. In particular, the function-separated type photoconductor in which the charge generation function and the charge transport function are assigned to different substances can select each material from a wide range, and a photoconductor having a desired performance can be relatively easily obtained. Much research has been done because it can be produced, and many have been put to practical use.
[0004]
In order to produce these organic photoreceptors, a compound having a charge generation function or a charge transport function is laminated and applied on a conductive support. Therefore, it usually has a multilayer structure, and each layer is applied with a coating solution prepared by dissolving a solid compound in a solvent using various coating methods.
[0005]
However, there are surprisingly few organic solvents, especially those with high solvency and suitable boiling points suitable for industrial production.
[0006]
Of course, as long as it is a solvent used in the production of a photoreceptor, it can be used only if it has a dissolving ability and an appropriate boiling point, and does not adversely affect the characteristics as an electrophotographic photoreceptor. The need for solvents has increased in recent years.
[0007]
[Problems to be solved by the invention]
Therefore, the object of the present invention is to prevent whitening under a wide range of coating conditions when producing an electrophotographic photosensitive member, and the electrophotographic characteristics are equal to or better than those obtained when a conventional halogenated hydrocarbon solvent is used. potential characteristic over a long period of time from, durability and image characteristics, a charge transport layer coating solution of the electrophotographic photoreceptor excellent in resolution, and to provide a manufacturing how the electrophotographic photoreceptor using the same.
[0008]
[Means for Solving the Problems]
The object of the present invention is achieved by adopting the following configuration.
[0009]
(1) on the conductive support in the charge transport layer coating liquid used for forming the charge transporting layer of the electrophotographic photosensitive member obtained by laminating a charge transport layer and charge generating layer,
A coating for a charge transport layer comprising a mixed solvent comprising 1,3-dioxolane and an aromatic hydrocarbon ( excluding benzene and toluene ) , and polyarylate as a binder resin for the charge transport layer liquid.
[0010]
(2) The coating liquid for a charge transport layer according to (1), wherein the aromatic hydrocarbon ( excluding benzene and toluene ) has a boiling point of 200 ° C. or less under 101 kPa.
[0011]
(3) The mixing ratio of the 1,3-dioxolane and aromatic hydrocarbon ( excluding benzene and toluene ) is 10/90 to 90/10 (weight ratio) according to (1) or (2) Coating liquid for charge transport layer.
[0012]
(4) The charge transport layer coating solution according to any one of (1) to (3), further comprising a charge transport material .
[0015]
( 5 ) The charge transport layer coating solution according to any one of (1) to ( 4 ), further comprising an antioxidant.
[0016]
( 6 ) In a method for producing an electrophotographic photosensitive member obtained by laminating a charge generation layer and a charge transport layer on a conductive support,
The charge transport layer, (1) to (5) or the method for producing a photoreceptor and forming by using a charge transport layer coating liquid according to the.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0018]
In the case of an electrophotographic photosensitive member, particularly an organic photosensitive member, in order to form the photosensitive layer, it is a common production method to apply each solid material constituting them in a solvent.
[0019]
In the case of a laminated photoconductor having a laminated structure in which the functions of charge generation and charge transport are separated, most of the film thickness of the photosensitive layer is the charge transport layer (about 10 to 40 μm). The solvent used has high solubility and has an appropriate boiling point so that it does not remain in the photosensitive layer, the boiling point is too high, the coating solution does not sag, and it remains as an impurity and does not adversely affect the electrophotographic characteristics, etc. Various required characteristics are required.
[0020]
Recently, polycarbonates and polyarylate binders often used as binder resins for charge transport layers have been used as surface binders for electrophotographic photoreceptors as excellent binders. However, these coating solvents are often a combination of halogen-containing organic solvents such as methylene chloride, ethylene chloride, chloroform, monochlorobenzene, dichlorobenzene, or a simple substance.
[0021]
There are many halogen-free organic solvents such as acetone, acetic acid, methyl ethyl ketone, toluene, tetrahydrofuran (THF), dioxane, cyclohexanone, etc., but for polycarbonate and polyarylate binders that are excellent in strength as binder resins for the surface layer. It is easy to find a non-halogen solvent that satisfies all the necessary properties such as dissolution ability, no sagging during film formation (having an appropriate boiling point), and excellent sensitivity when it becomes an electrophotographic photoreceptor. Not. In particular, in the case of a charge transport layer, a film thickness of usually 15 μm or more is required. Therefore, when a polymerized polycarbonate or polyarylate is used as a binder, the solubility of these polymers needs to be sufficient. .
[0022]
Examples of good solvents that do not contain halogens include cyclic ether tetrahydrofuran containing oxygen atoms in the molecule and dioxane containing two oxygen atoms. Tetrahydrofuran etc. are structurally unstable and can be trapped as stabilizers. In addition, dioxane and the like are highly toxic and are suspected to be carcinogenic.
[0023]
On the other hand, 1,3-dioxolane has a high ability to dissolve various binders and has a boiling point of about 74 to 75 ° C., which is suitable as a solvent for a coating solution for a photoreceptor, but in the production of an actual photoreceptor, In order to avoid whitening (brushing) after coating, temperature and humidity control in a narrow range is required, and sensitivity may not be sufficient in terms of electrophotographic characteristics. was there.
[0024]
Above all, by using 1,3-dioxolane as a low-boiling solvent, and combining high-boiling solvents with aromatic hydrocarbons ( except benzene and toluene ), solids (CT materials, binders, etc.) are widely dissolved. Because it contains aromatic hydrocarbons, it is difficult to whiten over a wide temperature and humidity range in the coating to drying process, and it is equivalent to or more than a solvent that preferably combines halogenated hydrocarbons and halogenated aromatic hydrocarbons. Exhibits the electrophotographic characteristics of At this time, if the allowable range of the charge transport layer thickness profile (thickness sagging, etc.) is wide, it is not limited to 1,3-dioxolane, but has one or more substituents such as methyl group, ethyl group, and the like. A 1,3-dioxolane derivative having a boiling point higher than that of 1,3-dioxolane may be used alone, in combination, or in combination with 1,3-dioxolane as a 1,3-dioxolane solvent for the charge transport layer coating solution.
[0025]
The mixing ratio of 1,3-dioxolane and aromatic hydrocarbon solvent at this time can be selected from the relationship between ease of whitening and sagging of the film thickness after drying. Dioxolane / aromatic hydrocarbon = 5/95 to 95/5 (weight ratio), and more generally, the mixed solvent can be constituted with a wide mixing ratio of 10/90 to 90/10.
[0026]
As the name indicates, 1,3-dioxolane of the present invention has the following structure.
[0027]
[Chemical 1]
[0028]
1,3-dioxolane is an aliphatic group that is not found in other aliphatic hydrocarbons, alcohols, ketones, esters, carboxylic acids, ethers, and other aliphatic solvents, but is a binder such as high molecular polycarbonates and polyarylates. it is possible to lyse wood polymer and a good solvent for the coating solution of the electrophotographic photosensitive member can be sufficiently dissolve the low molecular functional materials such as a charge-transporting materials. Further, the boiling point is about 74 to 75 ° C., and evaporation characteristics suitable for the coating solvent for the photoreceptor are provided.
[0029]
On the other hand, in general, there are many aromatic hydrocarbons having various substituents such as toluene, xylene, anisole, benzyl alcohol, phenol, cresol, monochlorobenzene and dichlorobenzene, in addition to unsubstituted ones such as benzene. This aromatic hydrocarbon is applied as a constituent solvent of the coating solution, and then takes a process of removing the solvent by evaporation at high temperature drying. Therefore, if the solvent is difficult to evaporate, it exists as a residual solvent in the photosensitive layer. However, a coating solution for the surface layer is an obstacle to wear resistance. Therefore, the aromatic hydrocarbon according to the present invention is not suitable as a solvent for a coating solution for a photosensitive member if it has a boiling point far from the normal drying temperature. Therefore, the boiling point is preferably 200 ° C. or lower under normal pressure.
[0030]
Examples of the aromatic hydrocarbon having the boiling point as described above include benzene, toluene, xylene, anisole, chlorobenzene and the like. However, benzene is not included in the aromatic hydrocarbon of the present invention from the viewpoint of adverse effects on the human body and the point of whitening described later.
[0031]
By using such an aromatic hydrocarbon as a coating solution for a charge transport layer of a photoreceptor in combination with 1,3-dioxolane, not only a dehalogenated solvent is established, but also a rapid temperature during coating to drying. Because it prevents the deterioration, whitening (brushing) can be prevented over a wide range of temperatures and humidity. In addition, this combination has good electrophotographic characteristics that are not seen with other non-halogen solvents alone or in combination with non-halogen solvents. High sensitivity / maintaining low residual potential after the endurance).
[0032]
The reason for this is not clear, but an appropriate amount of aromatic hydrocarbon (slow evaporation solvent) is mixed in the low boiling point good solvent of the charge transport layer coating solution of the photoreceptor with the charge transport layer laminated on the charge generation layer. by being, even while having a high dissolving power to the binder and various charge transport materials such as polycarbonate or polyarylate of aromatic hydrocarbons, used in the charge generation layer resin (various acetal resin) Although it can be swollen, it cannot be freely dissolved. Therefore, the charge transport layer coating solution can sufficiently wet the charge generation layer while leaving the interface between the charge generation layer and the charge transport layer. As a result, the charge generation layer / charge transport layer interface having a very large area can be formed. It is considered that one of the reasons for high sensitivity is that it can be formed and the resin covering the pigment is not dissolved.
[0033]
In the case of aromatic hydrocarbons, even if a small amount remains in the photosensitive layer, the conductivity and mobility of charges are hindered compared to other aliphatic saturated hydrocarbons and highly polar organic compounds. Can be expected to be somewhat smaller.
[0034]
The residual content contained in the 1,3-dioxolane or aromatic hydrocarbon photoreceptor of the present invention varies slightly depending on the thickness of the charge transport layer, affinity with the binder, coating speed, drum diameter, process, etc. In fact, it is better to produce after confirmation by content analysis in the drum. The content control is performed by a preferable combination of drying temperature, drying time, drying air speed, air volume, and the like.
[0035]
The residual content of the coating solvent of the present invention contained in the photoreceptor can be quantified by a method well known to those skilled in the art, such as gas chromatography.
[0036]
Binder resins to be dissolved in the charge transport layer coating solution particularly suitable for the present invention include polycarbonate and polyarylate. These binders are known, and various materials such as Japanese Patent Application Laid-Open Nos. 07-092703 and Hei. 10-020523 and the like. Examples of these polycarbonates and polyarylates are shown below, but are not limited thereto. In the examples, n and m represent the degree of polymerization (molar ratio).
[0037]
[Chemical formula 2]
[0038]
In order to improve the storage stability of 1,3-dioxolane, an antioxidant (AO agent) may be added. In this case, the antioxidant used is not particularly limited in chemical structure and the like as long as it does not adversely affect the electrophotographic characteristics. Examples of the compounds preferably used include those having a hindered amine structural unit or a hindered phenol structural unit, or those having both, an organic phosphorus compound, an organic sulfur compound, a hydroquinone compound, a phenylamine compound, and the like. However, it is not limited to these.
[0039]
(1) Examples of compounds having hindered phenol structural units
[Chemical 3]
[0041]
(2) Examples of compounds having hindered amine structural units
[Formula 4]
[0043]
(3) Organophosphorus compound examples
[Chemical formula 5]
[0045]
(4) Examples of organic sulfur compounds [0046]
[ Chemical 6 ]
[0047]
(5) Hydroquinone compound examples ((3-10) and derivatives)
[0048]
[Chemical 7]
[0049]
As a preferred antioxidant, those having a hindered phenol structural unit in the molecule are advantageous in terms of the stability of the coating solution composition, the repetition characteristics of the film-formed photoreceptor and the stability of the potential. A heterogeneous mixture of inhibitors may be used.
[0050]
The addition amount of the antioxidant is preferably 30 to 1000 ppm with respect to 1,3-dioxolane. If the addition amount is small, the coating solution deteriorates with time, and if the addition amount is too large, the electrophotographic characteristics are adversely affected (sensitivity deterioration). Therefore, it is preferable to keep the addition amount as small as possible according to the desired liquid storage period.
[0051]
The structure of the electrophotographic photoreceptor used in the present invention will be described below.
[0052]
The electrophotographic photosensitive member in the present invention is a laminated type separated into a charge transport layer and a charge generation layer, and the surface layer can exhibit more functions if it is a charge transport layer.
[0053]
Any conductive support may be used as long as it has conductivity. Examples thereof include metals such as aluminum and stainless steel, metals provided with a conductive layer, paper, plastics, and the like. It is done.
[0054]
You may provide the conductive layer aiming at coat | covering the damage | wound of a support body. This can be formed by dispersing conductive powder such as carbon black and metal particles in a binder resin. The thickness of the conductive layer is 5 to 40 μm, preferably 10 to 30 μm.
[0055]
An intermediate layer having an adhesive function is provided thereon. Examples of the material for the intermediate layer include polyamide, polyvinyl alcohol, polyethylene oxide, ethyl cellulose, casein, polyurethane, and polyether urethane. These are dissolved in an appropriate solvent and applied. The thickness of the intermediate layer is 0.05 to 5 μm, preferably 0.3 to 1 μm.
[0056]
A charge generation layer is formed on the intermediate layer. The charge generation layer used in the present invention is formed by coating and drying a paint in which a charge generation material and a binder resin are dispersed in a solvent. In the case of the functional separation type, the charge generation layer may be formed by a method such as a homogenizer, ultrasonic dispersion, ball mill, vibration ball mill, sand mill, attritor, roll mill and liquid collision type high-speed disperser together with the binder resin and solvent. scatter. Examples of the charge generation material used here include pyrium, thiapyrylium dyes, phthalocyanine, anthanthrone, dibenzpyrenequinone, trisazo, cyanine, disazo, monoazo, indigo, quinacridone, and asymmetric quinocyanine pigments. Examples of the binder resin include polyester resin, polyacrylic resin, polyvinyl carbazole resin, phenoxy resin, polycarbonate resin, polystyrene resin, polyvinyl acetate resin, polysulfone resin, polyarylate resin, vinylidene chloride, polyvinyl benzal resin, polybutyral resin, and the like. Mainly used. The ratio (weight ratio) between the pigment and the binder resin is preferably 1 / 0.1 to 1/10, more preferably 1/1 to 3/1. The film thickness of the charge generation layer formed by applying and drying the dispersion is 5 μm or less, preferably 0.1 to 2 μm.
[0057]
The charge transport layer is formed by applying / drying a paint in which a charge transport material and a binder (binder) are dissolved in a mixed solvent based on the present invention. Examples of the charge transport material used include low-molecular compounds such as triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triarylmethane compounds, and thiazole compounds. Examples of the binder for the charge transport layer include polycarbonate resin, polyarylate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic ester resin, and styrene-methacrylic ester copolymer. Examples of the resin include, but are not limited to. The charge transport materials is combined with 0.5 to 2 times the amount of the binder resin, coating, drying and forming a charge transport layer. The thickness of the charge transport layer is 5 to 40 μm, preferably 15 to 30 μm.
[0058]
Next, the configuration in the vicinity of the electrophotographic photosensitive member will be described.
[0059]
FIG. 1 shows an example of a contact charging type electrophotographic apparatus. This example is a transfer type copying machine or printer, and is an example in the case of a cartridge system in which one photosensitive member, two charging rollers, four developing devices and eight cleaning blades are incorporated in nine process cartridge frames. It is.
[0060]
Reference numeral 1 denotes a drum type electrophotographic photosensitive member which is an object of the present invention. The electrophotographic photosensitive member 1 is rotationally driven at a predetermined peripheral speed (process speed) in the clockwise direction of an arrow.
[0061]
A charging roller 2 is a contact charging member as a charging unit. The charging roller 2 rotates following the rotation of the photosensitive member 1 in pressure contact with the charging roller, and a DC voltage on which an AC voltage is superimposed is applied from a bias power source (not shown). The charging roller 2 uniformly charges the peripheral surface of the photoreceptor 1 to a predetermined polarity / potential. The target image information is exposed 3 on the charging surface of the photosensitive member 1 by an exposure unit (not shown) such as a laser beam scanner, and an electrostatic latent image corresponding to the target image information is formed on the surface of the photosensitive member 1. Go.
[0062]
The formed electrostatic latent image is visualized as a transferable particle image (toner image) by regular development or reversal development with charged particles (toner) in the developing device 4.
[0063]
Next, the toner image is transferred onto a sheet 6 fed between the photoreceptor 1 and a transfer roller 5 that is in pressure contact with the photoreceptor. At this time, a bias voltage having a polarity opposite to the charge held in the toner is applied to the transfer roller 5 from a bias power source (not shown).
[0064]
The sheet 6 that has received the toner image transfer is separated from the surface of the photosensitive member 1 and conveyed to the fixing roller 7 to undergo a toner image fixing process.
[0065]
After the toner image has been transferred, the surface of the photoreceptor 1 is subjected to removal of deposits such as toner remaining after transfer by a cleaner (cleaning blade) 8 and the entire process is completed.
[0066]
A description will be given below in accordance with examples.
[0067]
【Example】
Reference example 1
At room temperature / humidity, a 30φ × 358mm A1 cylinder is used as a support, and a coating material composed of the following materials is applied onto the support by a dipping method, and heat-cured at 140 ° C. for 30 minutes for 15 μm conductivity. A layer was formed.
[0068]
Conductive pigment: SnO ₂ coated barium sulfate 10 parts Resistance adjusting pigment: Titanium oxide 2 parts Binder resin: Phenol resin 6 parts Leveling material: Silicone oil 0.001 part Solvent: Methanol / methoxypropanol 0.2 / 0.8 20 copies [0068]
Next, a solution obtained by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol was applied by a dipping method to form a 0.5 μm intermediate layer. .
[0069]
Next, 4 parts of oxytitanium phthalocyanine (TiOPc) in which the Bragg angle 2θ ± 0.2 ° of CuKα characteristic X-ray diffraction has strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° And 2 parts of polyvinyl butyral (trade name: ESREC BM2, manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone were dispersed in a sand mill apparatus containing φ1 mm glass beads for 4 hours, and then 100 parts of ethyl acetate was added to the dispersion for charge generation layer. Was prepared. This was applied by a dipping method to form a 0.2 μm charge generation layer.
[0070]
Next, the following structural formula (4)
[0071]
[Chemical 8]
[0072]
The charge transport materials 10 parts and, dissolved in polycarbonate resin (Mitsubishi Engineering Plastics Co., Ltd. Z-400) and 10 parts of 1,3-dioxolane, 40 parts of toluene (boiling point 110.6 ° C.) 40 parts solvent mixture of A coating solution for a charge transport layer was obtained.
[0073]
This coating was applied by a dipping method (constant coating speed) and dried at 120 ° C. for 1 hour to form a charge transport layer of 28 μm (near the center). At this time, when the dried charge transport layer was observed with an optical microscope and a large number of microbubbles were observed, whitening was indicated as “X”, and those not observed were indicated as “whitening”. The results are shown in Table 2.
[0074]
Further, the difference in film thickness at a position 180 mm from the upper end (uncoated side) of the charge transport layer (approximately the center of the photoconductor) and a position 20 mm is measured. The above case was evaluated as x. The results are shown in Table 2.
[0075]
Next, evaluation using a machine will be described.
[0076]
The equipment is Canon's LBP-930 (the process speed is 106mm / sec, the initial setting is double speed 212mm / sec, the laser irradiation part is attached with a filter, and the laser light quantity is reduced to 50% normal setting) and its process A cartridge was used.
[0077]
The produced electrophotographic photosensitive member is endured with letter paper at room temperature and humidity (about 23 ° C / 60%) with this device, and the sequence is an intermittent mode that stops once for each print. Table 2 shows the results of measuring the initial portion and the light potential (Vl) after 2,000 sheets.
[0078]
Reference Examples 2-13
No. described in Table 1. The solvent composition of the charge transport layer was 2 to 13, the presence or absence of addition of BHT (2,6-di-tert-butyl-4-methylphenol) as an additive, and the thickness of the charge transport layer were changed to 26 μm. Except for this, an electrophotographic photoreceptor was prepared in the same manner as in Reference Example 1, and whitening, sagging, and sensitivity (V1) before and after durability were evaluated / measured. The results are shown in Table 2.
[0079]
[Table 1]
[0080]
[Table 2]
[0081]
Comparative Examples 1-7
No. described in Table 3 An electrophotographic photosensitive member was prepared in the same manner as in Reference Example 1 except that the solvent composition of the charge transport layer was 1 to 7 and the thickness of the charge transport layer was changed to 26 μm. Sensitivity (V1) was evaluated / measured. The results are shown in Table 4.
[0082]
[Table 3]
[0083]
[Table 4]
[0084]
Reference Example 14, Example 1 5-16
No. described in Table 5 The solvent composition of the charge transport layer is 14 to 16, the polyarylate (Mw = 100,000) is used as the binder resin for the charge transport layer, and the thickness of the charge transport layer is 26 μm. An electrophotographic photosensitive member was prepared in the same manner as in Reference Example 1 except that the whitening, sagging, and sensitivity (V1) before and after durability were evaluated / measured. The results are shown in Table 6.
[0085]
Example 17
No. described in Table 5 The solvent composition of the charge transport layer is 17, the polycarbonate resin Z400 and the polyarylate (2-2) are mixed and used in a ratio of 1: 1 to the binder resin for the charge transport layer, An electrophotographic photosensitive member was prepared in the same manner as in Reference Example 1 except that the thickness of the transport layer was changed to 26 μm, and whitening, sagging, and sensitivity (V1) before and after durability were evaluated / measured. The results are shown in Table 6.
[0086]
Reference Example 18
No. described in Table 5 Reference example, except that the solvent composition of the charge transport layer is 18 and polymethyl methacrylate (Mw = 100,000) is used as the binder resin for the charge transport layer and the film thickness of the charge transport layer is changed to 26 μm. An electrophotographic photosensitive member was prepared in the same manner as in Example 1, and whitening, sagging and sensitivity (V1) before and after durability were evaluated / measured. The results are shown in Table 6.
[0087]
[Table 5]
[0088]
[Table 6]
[0089]
In addition, when the appearance was observed 12 months after the preparation of the charge transport layer coating liquids of Reference Examples 1 to 7, no change was found in Reference Examples 5 to 7 containing the additive, but the additive-free reference In Examples 1 to 4, the yellowish color slightly increased, suggesting that the cyclic ether solvent was deteriorated.
[0090]
【The invention's effect】
By combining 1,3-dioxolane and aromatic hydrocarbon solvent ( excluding benzene and toluene ) as a solvent for the coating solution for the charge transport layer, sufficient solubility of solids and wide temperature / humidity range where no whitening occurs In addition, the present invention has various characteristics required for a solvent for a charge transport layer, which has been difficult unless it is a halogen-based solvent, such that the thickness of the film is small and that the electrophotographic photosensitive member has sufficient characteristics. Could be fully satisfied with the solvent composition not limited to the halogen-based solvent.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an example of an electrophotographic apparatus.
DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging roller 3 Image exposure 4 Developing device 5 Transfer roller 6 Paper 7 Fixing roller 8 Cleaning blade 9 Cartridge frame 10 Cartridge guide

Claims (6)

In the charge transport layer coating liquid used for forming the charge transporting layer of the electrophotographic photosensitive member on a conductive support formed by laminating a charge transporting layer and the charge generation layer,
A charge transport layer coating comprising a mixed solvent comprising 1,3-dioxolane and an aromatic hydrocarbon ( excluding benzene and toluene ) and polyarylate as a binder resin for the charge transport layer liquid. The coating solution for a charge transport layer according to claim 1, wherein the aromatic hydrocarbon ( excluding benzene and toluene ) has a boiling point of 200 ° C or lower at 101 kPa. The charge transport layer coating according to claim 1 or 2, wherein a mixing ratio of the 1,3-dioxolane and the aromatic hydrocarbon ( excluding benzene and toluene ) is 10/90 to 90/10 (weight ratio). liquid.   Furthermore, the coating liquid for charge transport layers in any one of Claims 1-3 containing charge transport material. Furthermore, the coating liquid for charge transport layers in any one of Claims 1-4 containing antioxidant. In a method for producing an electrophotographic photosensitive member obtained by laminating a charge generation layer and a charge transport layer on a conductive support,
The charge transport layer, the method for producing a photoreceptor and forming by using a charge transport layer coating solution according to any one of claims 1-5.