JP4208383B2 - Coating liquid for charge transport layer and method for producing electrophotographic photosensitive member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present inventionFor charge transport layers used to form charge transport layers for electrophotographic photoreceptorsCoatingLiquidAnd use itWasElectrophotographic photoreceptorManufacturing methodConcerningThe
[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, each layer is usually formed by applying a coating solution having a multilayer structure, in which a solid compound is dissolved 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 that whitening does not occur under a wide range of application conditions when producing an electrophotographic photosensitive member, and the electrophotographic characteristics are equal to or better than those obtained when a conventional halogen-based solvent is used. Coating liquid for charge transport layer of electrophotographic photoreceptor excellent in potential characteristics from the initial stage of formation over a long period of time, and using the sameOf electrophotographic photoreceptorManufacturing methodThe lawIt is to provide.
[0008]
[Means for Solving the Problems]
  The object of the present invention is achieved by adopting the following configuration.
(1) In a coating solution for a charge transport layer used for forming the charge transport layer of an electrophotographic photoreceptor obtained by laminating a charge generation layer and a charge transport layer on a conductive support,
TheMethoxymethaneAndTylene glycol dimethyl etherAnd YoshiMixtures composed of aromatic hydrocarbons (excluding benzene)Contains solventA coating solution for a charge transport layer.
(2) BeforeRecordingWith methoxymethaneSaidWith ethylene glycol dimethyl etherSaidThe mixing ratio with the aromatic hydrocarbon is 5 to 40/30 to 70/10 to 60 (weight ratio) (1)InThe coating liquid for charge transport layers as described.
(3) The coating liquid for a charge transport layer according to (1) or (2), wherein the aromatic hydrocarbon is at least one selected from xylene and structural isomers thereof.
(4)Furthermore, as a binder resin for the charge transport layerPolycarbonate or polyarylateContains(1)-Coating liquid for charge transport layers in any one of (3).
(5)furtherAntioxidantTheContainsDo(1)-Coating liquid for charge transport layers in any one of (4).
(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 comprises:(1)-(5)For charge transport layer according to any one ofCoating liquidThe method for producing an electrophotographic photosensitive member according to the above, wherein
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0010]
  In the case of electrophotographic photoreceptors, particularly organic photoreceptors, each of the constituents of them is formed to form the photosensitive layer.Solid materialIt is a general manufacturing method to apply the solution in a solvent.
[0011]
  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.
[0012]
  Recently, the charge transport layerBinder resinPolycarbonates and polyarylate binders that are often used in the field have been used as excellent binders for the surface layer of electrophotographic photoreceptors. However, these coating solvents are combined with halogen-containing organic solvents such as methylene chloride, ethylene chloride, chloroform, monochlorobenzene and dichlorobenzene.WowIn many cases, it is a single item or a single item.
[0013]
  There are many halogen-free organic solvents such as acetone, acetic acid, methyl ethyl ketone, toluene, tetrahydrofuran (THF), dioxane, cyclohexanone, etc.Binder resinAs a high-strength polycarbonate and polyarylate binder, the ability to dissolve, no dripping when forming a coating (having an appropriate boiling point), and excellent sensitivity when it becomes an electrophotographic photoreceptor, It has been difficult to find a non-halogen solvent that satisfies all the necessary properties such as the above. In particular, in the case of a charge transport layer, a film thickness of usually 15 μm or more is required, so a polymerized polycarbonate or polyarylate is used as a binder.resinWhen used as, for example, it is necessary that the solubility of these polymers is sufficient.
[0014]
  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.
[0015]
  Dimethoxymethane has a boiling point of about 42.5 ° C. and other non-halogen solvents (Binder resin(Solvents that can swell or dissolve) (as coating solvents for charge transport layers), although they exhibit excellent boiling point characteristics (low boiling point), various charge transport materialsFeeThe solubility is small, and it is not insoluble in the binder, but it remains in the degree of swelling.
[0016]
  Above all, a mixture of dimethoxymethane and ethylene glycol dimethyl ether is used as a low boiling solvent, and aromatic hydrocarbons (excluding benzene) are combined with the high boiling solvent.WowBySolid content(Charge transport materialIt is difficult to whiten over a wide temperature and humidity range in the coating to drying process, and it is also halogenated hydrocarbon and halogenated aromatic carbonized. Preferred combination of hydrogenWowExhibits electrophotographic characteristics equivalent to or better than the soaked solvent.
[0017]
  In addition, at this time,DimethoxymethaneWhen, Ethylene glycol dimethyl ether and,Aromatic hydrocarbonPlainThe desired mixing ratio can be selected based on the relationship between the ease of whitening and the film thickness sagging after drying.And ethylene glycol dimethyl ether,Aromatic hydrocarbonsWhenMixing ratio(Dimethoxymethane / ethylene glycol dimethyl ether / aromatic hydrocarbon)Is 5 to 40/30 to 70/10 to 60 (weight ratio).
[0018]
  The dimethoxymethane of the present invention is also called methylal by a general name and has the following structure.
[0019]
H ₃C-O-CH₂-O-CH₃
  Dimethoxymethane cannot be completely mutually dissolved with binder polymers such as polymer polycarbonate and polyarylate than other aliphatic solvents such as aliphatic hydrocarbons, alcohols, ketones, esters, carboxylic acids and ethers. , Can be swelled (swells), and charge transport material in small quantitiesFeeIt is a solvent suitable for a coating solution for an electrophotographic photoreceptor capable of dissolving a low molecular functional material such as the above. Particularly, the boiling point is about 42.5 ° C., and it has evaporation characteristics particularly suitable for a low boiling point coating solvent for a photoreceptor.
[0020]
  In addition, the ethylene glycol dimethyl ether of the present invention, as its name,DimethoxymethaneIt has the same ether structure and has the following structure.
[0021]
H ₃C-O-CH₂CH₂-O-CH₃
[0022]
  Ethylene glycol dimethyl ether is an aliphatic hydrocarbon not found in other aliphatic hydrocarbons, alcohols, ketones, esters, carboxylic acids, ethers, and other aliphatic solvents, but it binds high molecular weight polycarbonate, polyarylate, etc. It is possible to dissolve polymer materials and charge transport materialsFeeIt is a good solvent for the coating solution of the electrophotographic photosensitive member that can sufficiently dissolve low molecular weight functional materials such as the above. However, the boiling point is about 82 ° C.DimethoxymethaneCompared to the above, it has higher evaporating characteristics, and the single product is difficult to use, such as whitening of the charge transport layer coating solution and insufficient sensitivity.
[0023]
  On the other hand, in general, there are many aromatic hydrocarbons having 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 passes through a step of removing the solvent by evaporation at high temperature, so if it is a solvent that is difficult to evaporate, it exists as a residual solvent in the photosensitive layer. If it is a coating solution for the surface layer, it becomes an obstacle to wear resistance. Therefore, the aromatic hydrocarbon according to the present invention is not suitable as a solvent for the photoreceptor coating solution if it has a boiling point far from the normal drying temperature, and therefore the boiling point is preferably 200 ° C. or less under normal pressure.
[0024]
  Examples of the aromatic hydrocarbon having the boiling point as described above include benzene, toluene, xylene, anisole, chlorobenzene and the like. However, benzene is a knowledge of adverse effects on the human body.andFrom the viewpoint of preventing whitening described later, it is not included in the aromatic hydrocarbon of the present invention. Chlorobenzene should only be used in exceptional manufacturing processes where a solvent recovery system is in place if pursuing the establishment of a dehalogenated solvent.
[0025]
  Among these aromatic hydrocarbons, xyleneandThe range of 135 to 145 ° C., which is the boiling point of the structural isomer, is a component that does not rapidly evaporate as a high-boiling solvent of the coating liquid for the charge transport layer (from the viewpoint of wettability with the charge generation layer described later). / It is considered to be an appropriate temperature range having the contradicting characteristics of not being a component that tends to remain.
[0026]
[Chemical 1]
  Such aromatic hydrocarbonsDimethoxymethaneCombined with ethylene glycol dimethyl etherWowBy applying a coating solution for the charge transport layer of the photosensitive member, not only can a dehalogenated solvent be possible, but also a rapid temperature drop during coating to drying is prevented, so whitening (brushing) over a wide range of temperature and humidity In addition, this combinationWowOther non-halogen solvents alone or combinations of non-halogen solventsWowIt is possible to develop good electrophotographic characteristics (maintaining high sensitivity / low residual potential from the initial stage of the photoreceptor to after the endurance) under a wide use environment that cannot be seen in the conventional case.
[0027]
  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. As a result, binders such as aromatic hydrocarbon polycarbonate and polyarylate and various charge transport materialsFeeAlthough the resin used in the charge generation layer (various acetal resins, etc.) can swell but cannot be freely dissolved, the charge generation layer and the charge transport layer The charge transport layer coating solution can sufficiently wet the charge generation layer while leaving the interface, and as a result, a charge generation layer / charge transport layer interface having a very large area can be formed, and the pigment can be used. It is considered that one reason for the high sensitivity is that the covering resin is not dissolved.
[0028]
  Furthermore, although it is difficult to consider at this stage, there are three different types: a low-boiling solvent with a poor solubility having a similar chemical structure and a high-boiling aromatic solvent with a good solubility in medium-boiling ethylene glycol dimethyl ether. Coating for charge transport layer by mixing solvent with propertiesLiquidBy using it as a solvent, it is possible to have stable electrophotographic characteristics over a wide use environment of low temperature / low humidity to high temperature / high humidity.
[0029]
  Of the present inventionDimethoxymethane andThe residual content in ethylene glycol dimethyl ether and aromatic hydrocarbon photoreceptors varies slightly depending on the thickness of the charge transport layer, affinity with the binder, coating speed, drum diameter, process, etc. It should be produced 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.
[0030]
  Of the present inventionSolvent for coating solution for charge transport layerThe residual content contained in the photoconductor can be quantified by methods well known to those skilled in the art, such as gas chromatography.
[0031]
  Binder resins to be dissolved in the charge transport layer coating solution particularly suitable for the present invention include polycarbonate and polyarylate.resinIs known, and is described in various materials such as JP-A-07-092703 and JP-A-10-020523. 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).
[0032]
[Chemical formula 2]
  the aboveDimethoxymethaneIn addition, an antioxidant (AO agent) may be added to increase the storage stability of ethylene glycol dimethyl ether. 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 compounds preferably used include those having a hindered amine structural unit or a hindered phenol structural unit, or those having both, organic phosphorus compounds, organic sulfur compounds, hydroquinone compounds, phenylamine compounds, and the like. However, it is not limited to these.
  (1) Examples of compounds having hindered phenol structural units
[0033]
[Chemical 3]
  (2) Examples of compounds having hindered amine structural units
[0034]
[Formula 4]
  (3) Examples of organophosphorus compounds
[0035]
[Chemical formula 5]
  (4) Examples of organic sulfur compounds
[0036]
S(C₂H₄COOC₁₂H₂₅)₂  (3-8)
S (C₂H₄COOC₁₄H₂₉)₂  (3-9)
  (5) Hydroquinone compound examples ((3-10) and derivatives)
[0037]
[Chemical 6]
  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.
[0038]
  The amount of antioxidant added isDimethoxymethane10 ppm to 500 ppm with respect to the total solvent amount of ethylene glycol dimethyl ether, and if the addition amount is small, the coating solution deteriorates with time.fastIf the addition amount is too large, the electrophotographic characteristics are adversely affected (sensitivity degradation, increase in residual potential, etc.).
[0039]
  The structure of the electrophotographic photoreceptor used in the present invention will be described below.
[0040]
  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.
[0041]
  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.
[0042]
  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.
[0043]
  An intermediate layer with an adhesive function on itProvide. 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.
[0044]
  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 generating material used here include pyrium, thiapyrylium dyes, phthalocyanine, anthanthrone, dibenzpyrenequinone, trisazo, cyanine, disazo, monoazo, indigo, quinacridone, and asymmetric quinocyanine pigments. As the binder resin, for example, 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 are mainly used. 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.
[0045]
  The charge transport layer is mainly formed by applying / drying a paint in which a charge transport material and a binder (binder) are dissolved in a mixed solvent according to 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 resin. However, it is not limited to these. Charge transport materialFeeIs combined with 0.5 to 2 times the amount of binder resin, coated and dried to form a charge transport layer. The thickness of the charge transport layer is 5 to 40 μm, preferably 15 to 30 μm.
[0046]
  Next, the configuration in the vicinity of the electrophotographic photosensitive member will be described.
[0047]
  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.
[0048]
  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.
[0049]
  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. An exposure unit (not shown) exposes target image information 3 on the charged surface of the photosensitive member 1, and an electrostatic latent image corresponding to the target image information is formed on the surface of the photosensitive member 1. .
[0050]
  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.
[0051]
  Next, the toner image is transferred to 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).
[0052]
  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.
[0053]
  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.
[0054]
【Example】
  A description will be given below in accordance with examples.
[0055]
  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.
Conductive pigment: SnO₂Coated barium sulfate 10 parts
Resistance control pigment: Titanium oxide 2 parts
Binder resin: 6 parts of phenol resin
Leveling material: 0.001 part of silicone oil
Solvent: methanol, methoxypropanol 0.2 / 0.8 20 parts
  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. .
[0056]
  Next, the Bragg angle 2θ ± 0.2 ° of CuKα characteristic X-ray diffraction is 9.0 °, 14.2 °, 23.9 °.and4 parts of oxytitanyl phthalocyanine (TiOPc) having a strong peak at 27.1 °andAfter dispersing 2 parts of polyvinyl butyral (trade name: ESREC BM2, manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone with a sand mill apparatus with φ1 mm glass beads for 4 hours, 100 parts of ethyl acetate was added to prepare a dispersion for charge generation layer. . This was applied by a dipping method to form a 0.2 μm charge generation layer.
[0057]
  Next, the following structural formula (4)
[0058]
[Chemical 7]
The charge transport materialFee10 parts and 10 parts polycarbonate resin (Mitsubishi Engineering Plastics Z-400)DimethoxymethaneIt was dissolved in a mixed solvent of 15 parts, 40 parts of ethylene glycol dimethyl ether and 25 parts of toluene to prepare a coating solution for a charge transport layer.
[0059]
  This paint was applied by a dipping method (coating speed constant) and dried at 120 ° C. for 1 hour to form a charge transport layer of 30 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.
[0060]
  Further, the difference in film thickness is measured at a position 180 mm from the upper end (uncoated side) of the charge transport layer (approximately the center of the photosensitive member) and a position 20 mm from the top, and when the difference in film thickness is less than 4 μm, sag: ◯ 4 μm The above case was evaluated as x. The results are shown in Table 2.
[0061]
  Next, evaluation using a machine will be described.
[0062]
  The equipment is Canon LBP-930 (the process speed was 106mm / second, the initial setting was 212mm / second, the laser irradiation part was filtered, and the laser light intensity was reduced to 50% of normal setting)andThe process cartridge was used.
[0063]
  The created electrophotographic photosensitive member is endured with letter paper at room temperature and normal 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.
[0064]
  In addition, the initial potential (V1) of the same undurable new photoconductor with the same apparatus is also measured under high temperature and high humidity (HH: 35 ° C / 80% RH) and low temperature and low humidity (LL: 12 ° C / 12% RH) environment. Difference from V1 under normal temperature and humidity (Δ amount) (| HHOrTable 2 also shows V1-V1 at normal temperature and humidity at LL.
[0065]
  Examples 2-14:
  No. described in Table 1. 2-14 charge transport layersCoating liquidThe solvent composition of BHT (2,6-Di-tert-butyl-4-methylphenol) and an electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the thickness of the charge transport layer was changed to 26 μm, and whitening, sagging, durability Table 2 shows the Δ amount between the front and rear sensitivity (V1) and V1 at normal temperature and humidity.
[0066]
[Table 1]
[0067]
[Table 2]
  Comparative Examples 1-8:
  No. described in Table 3 1 to 8 charge transport layersCoating liquidThe electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the solvent composition was changed to 26 μm, and the sensitivity (V1) before and after whitening, sagging, durability, and normal temperature and humidity were obtained. The amount of Δ with respect to V1 below is shown in Table 4.
[0068]
[Table 3]
[0069]
[Table 4]
  Examples 15-17:
  No. described in Table 5 15 to 17 charge transport layersCoating liquidFor the charge transport layerBinder resinThe electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the polyarylate (Mw = 100,000) of (2-2) was used and the film thickness of the charge transport layer was changed to 26 μm. Table 6 shows the amount of Δ between sagging and sensitivity (V1) before and after durability and V1 under normal temperature and humidity.
[0070]
  Example 18:
  No. described in Table 5 18 charge transport layersCoating liquidFor the charge transport layerBinder resinIn the same manner as in Example 1, except that the polycarbonate resin Z400 and the polyarylate (2-2) were mixed at a ratio of 1: 1 and the thickness of the charge transport layer was changed to 26 μm. A photographic photoreceptor was prepared, and Table 6 shows the Δ amount between whitening, sagging, sensitivity before and after durability (V1), and V1 at normal temperature and humidity.
[0071]
  Example 19:
  No. described in Table 5 19 charge transport layersCoating liquidFor the charge transport layerBinder resinAn electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that polymethyl methacrylate (Mw = 100,000) was used and the film thickness of the charge transport layer was changed to 26 μm. Table 6 shows Δ amounts of (V1) and V1 under normal temperature and normal humidity.
[0072]
[Table 5]
[0073]
[Table 6]
  In addition, Example No. When the appearance was observed 12 months after the preparation of the charge transport layer coating liquids 1 to 6, no change was observed in Examples 5 to 6 containing the additive, but Examples 1 to 4 without addition were added. All of the samples slightly increased in yellowishness, suggesting the deterioration of the ether solvent.
[0074]
【The invention's effect】
  DimethoxymethaneWhenEthylene glycol dimethyl ether and aromatic hydrocarbonsElementary (Except benzene)WhenCombineWowBy using it as a solvent for the charge transport layer coating solution,Solid contentIt is difficult unless it is a halogen-based solvent that has sufficient solubility, high temperature / humidity range that does not whiten, little sagging of film thickness, and sufficient characteristics as an electrophotographic photoreceptor under a wide range of usage conditions. For charge transport layerCoating liquidThe present invention was able to satisfy all of the various properties required for the solvent with a solvent configuration 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.
[Explanation of symbols]
  1 Photoconductor
  2 Charging roller
  3 Image exposure
  4 Developer
  5 Transfer roller
  6 paper
  7 Fixing roller
  8 Cleaning blade
  9 Cartridge frame
  10 Cartridge guide

Claims (6)

In a coating solution for a charge transport layer used for forming the charge transport layer of an electrophotographic photosensitive member obtained by laminating a charge generation layer and a charge transport layer on a conductive support,
Di-methoxy methane and d Ji glycol dimethyl ether and Kaoru aromatic hydrocarbons (excluding benzene) and to contain a mixed solvent composed of a charge transport layer coating liquid, wherein Rukoto. For the charge transport layer according to 請 Motomeko 1 mixture ratio of Ru Der 5-40 / 30-70 / 10-60 (by weight) before and pheasant methoxymethane and the ethylene glycol dimethyl ether and the aromatic hydrocarbon Coating liquid. The aromatic charge transport layer coating solution according to at least one Der Ru請 Motomeko one or two selected from hydrocarbons xylene and its structural isomers. Furthermore , the coating liquid for charge transport layers in any one of Claims 1-3 which contains a polycarbonate or a polyarylate as binder resin for charge transport layers. Further the charge transport layer coating solution according to claim 1 containing an 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 method for producing an electrophotographic photosensitive member according to claim 1, wherein the charge transport layer is formed using the charge transport layer coating solution according to claim 1.