JP2007199238A - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor excellent in electrical properties and cracking resistance, and an image forming apparatus capable of obtaining a high-quality image. <P>SOLUTION: The electrophotographic photoreceptor comprises a conductive substrate and a charge transport layer containing a compound of formula (1), wherein R<SP>1</SP>-R<SP>15</SP>are each H, CF<SB>3</SB>(CF<SB>2</SB>)<SB>n</SB>CH<SB>2</SB>O- or the like, provided that at least one of R<SP>1</SP>-R<SP>15</SP>is CF<SB>3</SB>(CF<SB>2</SB>)<SB>n</SB>CH<SB>2</SB>O-, and (n) is an integer of 0-3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photoreceptor and an image forming apparatus.

  As an electrophotographic photosensitive member used in an image forming apparatus or the like, an electrophotographic photosensitive member having a conductive substrate and a photosensitive layer provided on the conductive substrate is known. The electrophotographic photosensitive member is produced by applying a coating solution in which a hole transport agent, a binder resin or the like is dissolved in a solvent, onto a conductive substrate, and drying to form a photosensitive layer.

As the hole transport agent, a compound represented by the following formula (3) is known (Patent Document 1). In formula (3), R ^{31 to} R ³⁵ are each a hydrogen atom, a lower alkyl group, an alkoxy group, a halogen atom, an aryl group which may have a substituent, or the like, and m is 0 or 1 It is.

Although the electrophotographic photoreceptor containing the compound represented by formula (3) in the photosensitive layer is excellent in electrical characteristics, the compound represented by formula (3) has solubility in a solvent and compatibility with a binder resin. Since it is scarce, the photosensitive layer becomes brittle and cracks may occur in the photosensitive layer.
JP 07-173112 A

  Accordingly, an object of the present invention is to provide an electrophotographic photoreceptor excellent in electrical characteristics and crack resistance and an image forming apparatus capable of obtaining a high-quality image.

  The electrophotographic photosensitive member of the present invention has a conductive substrate and a photosensitive layer provided on the conductive substrate, and the photosensitive layer contains a compound represented by the following formula (1) and a binder resin. It is the layer which carries out.

In formula (1), R ^{1 to} R ¹⁵ are each a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an aryl group which may have a substituent, or CF ₃ (CF ₂ ) _n CH ₂ O— And at least one of R ^{1 to} R ¹⁵ is CF ₃ (CF ₂ ) _n CH ₂ O—, and n is an integer of 0 to 3.

The photosensitive layer is a laminated photosensitive layer comprising a charge generation layer and a charge transport layer, and the charge transport layer is preferably a layer containing a compound represented by formula (1) and a binder resin.
In the compound represented by the formula (1), it is preferable that two or more of R ^{1 to} R ⁵ are CF ₃ (CF ₂ ) _n CH ₂ O—.
The binder resin is preferably a resin having any of structural units represented by the following formulas (2-1) to (2-3).

In formulas (2-1) to (2-3), R ^{21 to} R ²⁶ are a hydrogen atom or an optionally substituted alkyl group having 1 to 12 carbon atoms, and a to f are Each is an integer from 0 to 4.

  The image forming apparatus of the present invention includes an electrophotographic photosensitive member of the present invention, a charging unit that charges the surface of the electrophotographic photosensitive member, and an exposing unit that exposes the surface of the electrophotographic photosensitive member to form an electrostatic latent image. A charge removing unit that develops the electrostatic latent image as a toner image and a transfer unit that transfers the toner image from the electrophotographic photosensitive member to the transfer target, and removes the charge on the surface of the electrophotographic photosensitive member. It has no means.

The electrophotographic photoreceptor of the present invention is excellent in electrical characteristics and crack resistance.
The image forming apparatus of the present invention can obtain a high-quality image.

<Electrophotographic photoreceptor>
Examples of the electrophotographic photosensitive member include (i) a multilayer electrophotographic photosensitive member and (ii) a single layer type electrophotographic photosensitive member. In the present invention, the electrical characteristics such as sensitivity and the stability of the electrical characteristics are included. Therefore, (i) a multilayer electrophotographic photosensitive member is preferable.

(I) Laminated electrophotographic photoreceptor:
FIG. 1 is a schematic cross-sectional view showing an example of a laminated electrophotographic photosensitive member. The multilayer electrophotographic photoreceptor 10 includes a conductive substrate 12, a charge generation layer 16 provided on the conductive substrate 12 via an undercoat layer 14, and a charge transport layer 18 provided on the charge generation layer 16. And have. In the multilayer electrophotographic photoreceptor 10, a multilayer photosensitive layer is constituted by the charge generation layer 16 and the charge transport layer 18.

  The multilayer electrophotographic photoreceptor 10 is not limited to that shown in FIG. 1, and as shown in FIG. 2, a charge transport layer 18 is provided on a conductive substrate 12 with an undercoat layer 14 interposed therebetween. The charge generation layer 16 may be provided on the transport layer 18. However, in the present invention, it is preferable to provide the charge transport layer 18 on the charge generation layer 16 in terms of maintaining the electrical characteristics and image characteristics during durability. The undercoat layer 14 may be omitted, and a charge generation layer may be provided directly on a conductive substrate or a conductive substrate on which an oxide film is formed.

(Charge transport layer)
The charge transport layer is a layer containing a compound represented by the following formula (1) as a hole transport agent and a binder resin. Hereinafter, the compound represented by Formula (1) is referred to as Compound (1), and the structural unit represented by Formula (2) is referred to as Structural Unit (2). Other compounds and structural units are also described in the same manner.

R ^{1 to} R ¹⁵ are each a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an aryl group which may have a substituent, or CF ₃ (CF ₂ ) _n CH ₂ O—.
Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, t-butyl group, 2-ethylpentyl, 2-ethylhexyl and the like.
Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.
Examples of the aryl group include a phenyl group, a naphthyl group, an anthracenyl group, and a phenanthrenyl group.
One or more of R ^{1 to} R ¹⁵ are CF ₃ (CF ₂ ) _n CH ₂ O—, and _{two of} R ^{1 to} R ^{5 in} terms of solubility in a solvent and compatibility with a binder resin. The above is preferably CF ₃ (CF ₂ ) _n CH ₂ O—.

n is an integer of 0-3.
Compound (1) has two bisphenylbutadiene structures in the molecule, and one or more of R ^{1 to} R ¹⁵ are CF ₃ (CF ₂ ) _n CH ₂ O—, so that it can be dissolved in a solvent. Excellent compatibility with binder resin.

  The charge transport layer may contain other hole transport agents. Other hole transporting agents include triarylamine compounds excluding compound (1) and oxadiazole compounds such as 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole , Styryl compounds such as 9- (4-diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, organic polysilane compounds, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds Compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds and other nitrogen-containing cyclic compounds, condensed polycyclic compounds, etc. It is done. A hole transport agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the binder resin include polycarbonate resins such as bisphenol Z type, bisphenol ZC type, bisphenol C type, bisphenol A type, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer. Polymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer Thermoplastic resins such as coalescence, alkyd resin, polyamide resin, polyurethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin; silicone resin, epoxy resin, phenol resin , Urea resins, thermosetting resins such as melamine resin, epoxy acrylate, urethane - photocurable resins such as acrylate. Binder resin may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the binder resin, a polycarbonate resin having any one of the structural units (2-1) to (2-3) is preferable from the viewpoint that the electrical characteristics of the electrophotographic photosensitive member and the wear resistance in durability are good.

In formulas (2-1) to (2-3), R ^{21 to} R ²⁶ are a hydrogen atom or an optionally substituted alkyl group having 1 to 12 carbon atoms, and a to f are Each is an integer from 0 to 4.

10-500 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of the hole transport agent of a charge transport layer, 25-200 mass parts is more preferable.
The charge transport layer may contain a known additive as long as the electrophotographic characteristics are not adversely affected. Examples of additives include antioxidants, radical scavengers, singlet quenchers, deterioration inhibitors such as ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers. , Wax, acceptor, donor and the like.
The thickness of the charge transport layer is preferably 2 to 100 μm, and more preferably 5 to 50 μm.

(Charge generation layer)
The charge generation layer is a layer containing a charge generation agent and a binder resin. Examples of the binder resin include those similar to the charge transport layer.

  Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, diketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments, Organic photoconductors such as pyrylium pigment, ansanthrone pigment, triphenylmethane pigment, selenium pigment, toluidine pigment, pyrazoline pigment, quinacridone pigment; selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon, etc. And inorganic photoconductive agents. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the charge generation agent, a compound (4) having a large absorbance in the red or near infrared region and a large charge generation efficiency is preferable.

  In formula (4), M is 2H, TiO, or GaOH.

The content of the charge generating agent in the charge generating layer is preferably 5 to 1000 parts by mass, more preferably 30 to 500 parts by mass with respect to 100 parts by mass of the binder resin.
The charge generation layer may contain a known additive as long as it does not adversely affect the electrophotographic characteristics. Examples of additives include antioxidants, radical scavengers, singlet quenchers, deterioration inhibitors such as ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers. , Wax, acceptor, donor and the like.
The thickness of the charge generation layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 3 μm.

(Conductive substrate)
Examples of the conductive substrate include metals such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, and anodizing the metal An oxide film formed by treatment; a plastic material on which the metal is deposited or laminated; and a glass coated with aluminum iodide, tin oxide, indium oxide, or the like.
Examples of the shape of the conductive substrate include a sheet shape and a drum shape. The shape of the conductive substrate may be appropriately determined according to the structure of the image forming apparatus.

(Underlayer)
The undercoat layer is a layer containing fine particles of metal or metal oxide and a binder resin. Examples of the binder resin include those similar to the charge transport layer.

  Examples of the metal or metal oxide fine particles include aluminum, iron, copper, titanium oxide, silica, alumina, zirconium oxide, tin oxide, zinc oxide, and indium oxide, and titanium oxide is preferable. Titanium oxide is preferably surface-treated with alumina and silica and further surface-treated with methylhydrogenpolysiloxane or the like.

10-1000 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of the metal of a subbing layer, or metal oxide fine particles, 30-400 mass parts is more preferable.
The thickness of the undercoat layer is preferably from 0.1 to 10 μm, more preferably from 0.5 to 5 μm.

Each layer is formed, for example, by applying a coating solution in which the material of each layer is dissolved or dispersed in a solvent on the lower layer and drying it.
The coating liquid is prepared by dissolving or dispersing each component in a solvent using a roll mill, a ball mill, an attritor, a paint shaker, an ultrasonic disperser or the like. As a coating method, a known method may be used.

Examples of the solvent include alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; dichloromethane, dichloroethane, Halogenated hydrocarbons such as chloroform, carbon tetrachloride and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate Dimethylformaldehyde, dimethylformamide, dimethyl sulfoxide and the like. A solvent may be used individually by 1 type and may be used in mixture of 2 or more types.
In order to improve the dispersibility of each component and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent and the like may be added to the coating solution.

(Ii) Single layer type electrophotographic photoreceptor:
FIG. 3 is a schematic cross-sectional view showing an example of a single layer type electrophotographic photosensitive member. The single-layer type electrophotographic photoreceptor 20 has a conductive substrate 12 and a photosensitive layer 22 provided on the conductive substrate 12 with an undercoat layer 14 interposed.
The single-layer electrophotographic photoreceptor 20 is not limited to that shown in FIG. 3, and the undercoat layer 14 may be omitted.

Examples of the conductive substrate and the undercoat layer are the same as those of the multilayer electrophotographic photosensitive member.
The photosensitive layer is a layer containing a hole transport agent, a charge generator, a binder resin, and, if necessary, an electron transport agent.
Examples of the charge generating agent, hole transporting agent, binder resin, and the like are the same as in the multilayer electrophotographic photosensitive member.

  As electron transport agents, quinone derivatives, anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, trinitrothioxanthone derivatives, 3,4,5,7-tetranitro-9-fluorenone derivatives, dinitroanthracene derivatives, dinitroacridine derivatives, nitroantharaquinone Derivatives, dinitroanthraquinone derivatives, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, dibromomaleic anhydride, etc. It is done. An electron transfer agent may be used individually by 1 type, and may be used in combination of 2 or more type.

The photosensitive layer may contain known additives as long as the electrophotographic characteristics are not adversely affected. Examples of additives include antioxidants, radical scavengers, singlet quenchers, deterioration inhibitors such as ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers. , Wax, acceptor, donor and the like.
In order to improve the sensitivity of the photosensitive layer, known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator.

20-500 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of a hole transport agent, 30-200 mass parts is more preferable.
0.1-50 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of an electric charge generating agent, 0.5-30 mass parts is more preferable.
When the electron transport agent is contained, the content of the electron transport agent is preferably 5 to 100 parts by mass and more preferably 10 to 80 parts by mass with respect to 100 parts by mass of the binder resin.
The thickness of the photosensitive layer is preferably 5 to 100 μm, more preferably 10 to 50 μm.

  The photosensitive layer is formed by, for example, applying a hole transporting agent, a charge generating agent, a binder resin, and, if necessary, a coating solution in which an electron transporting agent is dissolved or dispersed in a solvent on a conductive substrate and drying it. It is formed.

  In the electrophotographic photosensitive member of the present invention described above, since the photosensitive layer contains the compound (1) excellent in solubility in a solvent and compatibility with a binder resin, it is excellent in crack resistance. Moreover, since the photosensitive layer contains the compound (1), the electrical characteristics are excellent.

<Image forming apparatus>
FIG. 4 is a schematic configuration diagram showing an example of the image forming apparatus of the present invention. The image forming apparatus 30 includes a charging unit 34, an exposure unit 36, a developing unit 38, a transfer unit 40, and a cleaning unit 42 in this order along the rotation direction of the rotatable drum-shaped electrophotographic photosensitive member 32. It does not have a charge eliminating means for removing the charge on the surface of the photoreceptor.

The electrophotographic photosensitive member 32 is the electrophotographic photosensitive member of the present invention, in which a photosensitive layer is provided on a drum-shaped conductive substrate.
The charging unit 34 is a unit that charges the surface of the electrophotographic photosensitive member 32, and examples thereof include a corona charging device, a charging roller, and a charging brush.
The exposure unit 36 is a unit that exposes the surface of the electrophotographic photosensitive member 32 to form an electrostatic latent image.
The developing unit 38 is a unit that develops an electrostatic latent image as a toner image using toner.
The transfer unit 40 is a unit that transfers the toner image from the electrophotographic photosensitive member 32 to a transfer target (not shown).
The cleaning means 42 is means for removing paper dust and the like adhering to the photosensitive drum, and examples thereof include an elastic blade and a fur brush.

Examples of the image forming apparatus include a copying machine, a facsimile machine, and a laser beam printer.
In the image forming apparatus described above, since the electrophotographic photosensitive member of the present invention is excellent in electrical characteristics and in particular, the exposure memory is very small, a memory image is not generated even if a charge eliminating unit is not provided. High-quality images can be obtained. Further, since there is no static elimination means, the image forming apparatus can be reduced in size, the initial cost can be reduced, and the like.

[Production Example 1]
(A) Process:
Into the flask, 18.7 g of compound (5) and 20 g of triethyl phosphite were added and stirred for 4 hours while heating at 130 ° C. After cooling to room temperature, excess triphosphorous acid triethyl ester was distilled off under reduced pressure to obtain 16.6 g of Compound (6).

(B) Process:
To the flask, 16.6 g of the compound (6) was added, argon gas replacement was performed, 100 mL of dried tetrahydrofuran (THF) and 29 g of 28% sodium methoxide were added, and the mixture was stirred at 25 ° C. for 30 minutes. Next, 15 g of compound (7) was dissolved in 300 mL of dry THF and added to the reaction solution, and stirred at room temperature for 6 hours. Thereafter, the reaction solution was poured into ion exchange water, extracted with toluene, and the organic layer was washed 5 times with ion exchange water. Subsequently, the organic layer was dried with anhydrous sodium sulfate, and the solvent was distilled off. Thereafter, the residue was purified by recrystallization from a toluene / methanol mixed solvent to obtain 19.3 g of Compound (8).

(C) Process:
A flask was charged with 4.3 g of compound (8), 1.0 g of bicyclohexylbiphenylphosphine, 0.1 g of palladium bis (dibenzylideneacetone), 1.2 g of t-BuONa, and 2.1 g of compound (9-1). 150 mL was added and stirred for 6 hours while heating at 130 ° C. After cooling to room temperature, the organic layer was washed three times with ion exchange water, the organic layer was dried and adsorbed using anhydrous sodium sulfate and activated clay, and xylene was distilled off under reduced pressure. Finally, the residue was purified by column chromatography (developing solvent: chloroform / hexane) to obtain 3.9 g of compound (1-1).

[Production Example 2]
Compound (1-2) was produced in the same manner as in Production Example 1, except that 3.2 g of compound (9-2) was used instead of 2.1 g of compound (9-1).

[Other hole transport agents]
As other hole transport agents, compounds (1-3) to (1-7) and compounds (10-1) to (10-3) were prepared.

[Production Example 3]
25 g of o-phthalonitrile, 28 g of titanium tetrabutoxide and 300 g of quinoline were added to a flask purged with argon, and the temperature was raised to 150 ° C. while stirring. Next, after evaporating the vapor generated from the reaction system, the temperature was raised to 215 ° C. while stirring, and the reaction was continued with stirring for 2 hours while maintaining this temperature.
After completion of the reaction, when the reaction mixture is cooled to 150 ° C., the reaction mixture is removed from the flask, the solid contained in the reaction mixture is filtered off with a glass filter, and the resulting solid is washed successively with N, N-dimethylformamide and methanol. And vacuum drying to obtain 24 g of a blue-violet solid.

10 g of a blue-violet solid was added to 100 mL of N, N-dimethylformamide, and the mixture was heated to 130 ° C. with stirring and stirring was continued for 2 hours. Heating was stopped when 2 hours had passed, and after cooling to 23 ± 1 ° C., stirring was also stopped. In this state, the liquid was allowed to stand for 12 hours for stabilization treatment.
The solid contained in the liquid was filtered off with a glass filter, and the obtained solid was washed with methanol and then vacuum-dried to obtain 9.83 g of crude crystals of titanyl phthalocyanine.

  5 g of crude crystals of titanyl phthalocyanine were added to 100 mL of concentrated sulfuric acid and dissolved. Then, this solution was dropped into water under ice cooling, stirred for 15 minutes at room temperature, and further allowed to stand at around 23 ± 1 ° C. for 30 minutes for recrystallization. Next, the crystals are filtered off with a glass filter, and the obtained solid is washed with water until the washing solution becomes neutral. Stir for 10 hours.

The solid contained in the liquid was filtered off with a glass filter, and the obtained solid was vacuum-dried at 50 ° C. for 5 hours to obtain 4.1 g of crystals (blue powder) of titanyl phthalocyanine.
The titanyl phthalocyanine has no peaks at Bragg angles 2θ ± 0.2 ° = 7.4 ° and 26.2 ° even when immersed in the initial and 1,3-dioxolane or tetrahydrofuran for 7 days, and It was confirmed that there was no peak of temperature change from 50 ° C. to 400 ° C. other than the peak around 90 ° C. accompanying vaporization of adsorbed water.

[Binder resin]
The binder resin has a polycarbonate resin having a structural unit (11-1), a polycarbonate resin having a structural unit (11-2), a polycarbonate resin having a structural unit (11-3), and a structural unit (11-4). A polycarbonate resin, a polycarbonate resin having a structural unit (11-5), and a polycarbonate resin having a structural unit (11-6) were prepared. In the formula, the number on the lower right outside the parentheses indicates the proportion (%) of the structural unit.

[Example 1]
After surface treatment with alumina and silica, 2 parts by mass of titanium oxide (manufactured by Teica, prototype SMT-02, number average primary particle size 10 nm) surface-treated with methyl hydrogen polysiloxane while being wet-dispersed, and 6,12 , 66, 610 quaternary copolymerized polyamide resin (Amilan CM8000, manufactured by Toray Industries, Inc.) is dispersed in 10 parts by mass of methanol and 2 parts by mass of butanol using a bead mill for 5 hours to disperse. A coating solution was prepared.
After filtering the coating solution for the undercoat layer with a 5 μm filter, it is applied to an aluminum drum having a diameter of 30 mm and a total length of 238.5 mm as a conductive substrate by dip coating, and heat-treated at 130 ° C. for 30 minutes to form a film. A subbing layer having a thickness of 2 μm was formed.

Subsequently, 1 part by mass of titanyl phthalocyanine produced in Production Example 3 as a charge generator, 0.5 part by mass of polyvinyl acetal resin (manufactured by Sekisui Chemical Co., Ltd., ESREC KS-5) as a binder resin, and phenoxy resin (manufactured by InChem, 0.5 parts by mass of PKKH) was dispersed in 40 parts by mass of propylene glycol monomethyl ether as a solvent and 40 parts by mass of tetrahydrofuran using a bead mill for 2 hours to prepare a coating solution for charge generation layer.
The charge generation layer coating solution is filtered through a 3 μm filter, then applied onto the undercoat layer by dip coating, and dried at 50 ° C. for 5 minutes to form a charge generation layer having a thickness of 0.3 μm. did.

Next, 80 parts by mass of the compound (1-1) as a hole transporting agent and 10 parts by mass of m-terphenyl as an additive were added to 150 parts by mass of tetrahydrofuran, followed by ultrasonic treatment to prepare a primary dispersion. . The solid content concentration of the primary dispersion was 37.5% by mass.
The following resin solution was added to 240 parts by mass of the primary dispersion and subjected to ultrasonic treatment to prepare a secondary dispersion. The solid content concentration of the secondary dispersion was 25.7% by mass. In this way, a coating solution for a charge transport layer was prepared.
Resin solution: A solution obtained by dissolving 100 parts by mass of a polycarbonate resin (viscosity average molecular weight 30,500) having the structural unit (11-1) as a binder resin in 400 parts by mass of tetrahydrofuran as a solvent.
The charge transport layer coating solution is applied onto the charge generation layer in the same manner as the charge generation layer coating solution and dried at 130 ° C. for 30 minutes to form a charge transport layer with a thickness of 20 μm. A photoreceptor was obtained.

(Solubility)
The primary dispersion was visually observed and evaluated as “◯” when there was no undissolved residue and “×” when there was undissolved residue. The results are shown in Table 2.
(Compatibility)
The secondary dispersion was visually observed and evaluated as ◯ when there was no microcrystal and x when there was microcrystal. The results are shown in Table 2.

(Crack resistance)
The lower end 5 cm of the electrophotographic photosensitive member is immersed in olive oil (manufactured by BESCO), and changes in the photosensitive layer after 12 hours are observed with an optical microscope, and the total length of cracks per 1 cm ^{2 of} the photosensitive layer surface. Was evaluated. A total of cracks of less than 1 cm was evaluated as ◎, a total of cracks of 1 cm or more and less than 2 cm was evaluated as ◯, a total of cracks was evaluated as 2 cm or more and less than 3 cm, and a rating of 3 cm or more was evaluated as ×. The results are shown in Table 2.

(Electrical characteristics)
The electrophotographic photosensitive member was attached to a commercially available printer (Okidata Corporation, MicroLine-22N) employing a negatively charged reversal development process, and 2000 sheets were printed under a room temperature environment. After printing, the potential at the development position was measured using a surface potentiometer, and the electrical characteristics (surface potential, bright potential, exposure memory) were evaluated. The surface potential is determined as (V ₀ -V _ob ) from the blank portion potential (V ₀ ), the bright potential from the solid portion potential, and the exposure memory from the next blank portion potential (V _ob ) of the front exposure portion. It was. The results are shown in Table 2.

(image)
The image of the 2000th printed material was visually evaluated. The exposure memory printed a solid black image on the first round of the photoconductor, and judged based on the presence or absence of an image on the front circumference in the gray image on the second round.
The case where no exposure memory was found ◎, the case where the exposure memory could not be known without gazing, ◯, the case where a light exposure memory was produced, and the case where the degree of exposure memory was large and clearly understood were evaluated as x. The results are shown in Table 2.

[Examples 2 to 12, Comparative Examples 1 to 8]
A laminated electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the hole transport agent and / or the binder resin were changed to those shown in Table 2. The results are shown in Table 2.

  The electrophotographic photosensitive member of the present invention is useful for an image forming apparatus that requires a high-quality image because it is excellent in electrical characteristics and crack resistance.

1 is a schematic cross-sectional view showing an example of a laminated electrophotographic photoreceptor. It is a schematic sectional drawing which shows the other example of a laminated type electrophotographic photoreceptor. It is a schematic sectional drawing which shows an example of a single layer type electrophotographic photoreceptor. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Stack type electrophotographic photosensitive member 12 Conductive substrate 16 Charge generation layer 18 Charge transport layer 20 Single layer type electrophotographic photosensitive member 22 Photosensitive layer 30 Image forming apparatus 32 Electrophotographic photosensitive member 34 Charging means 36 Exposure means 38 Developing means 40 Transfer means

Claims (5)

A conductive substrate;
A photosensitive layer provided on the conductive substrate,
An electrophotographic photoreceptor, wherein the photosensitive layer is a layer containing a compound represented by the following formula (1) and a binder resin.

In formula (1), R ^{1 to} R ¹⁵ are each a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an aryl group which may have a substituent, or CF ₃ (CF ₂ ) _n CH ₂ O— And at least one of R ^{1 to} R ¹⁵ is CF ₃ (CF ₂ ) _n CH ₂ O—, and n is an integer of 0 to 3. The photosensitive layer is a laminated photosensitive layer composed of a charge generation layer and a charge transport layer,
The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer is a layer containing a compound represented by formula (1) and a binder resin. _3. The electrophotographic photosensitive member according to claim 1, wherein the compound represented by formula (1) has two or more of R ^{1 to} R ⁵ being CF ₃ (CF ₂ ) _n CH ₂ O—. The electrophotographic photosensitive member according to claim 1, wherein the binder resin is a resin having any of structural units represented by the following formulas (2-1) to (2-3).

In formulas (2-1) to (2-3), R ^{21 to} R ²⁶ are a hydrogen atom or an optionally substituted alkyl group having 1 to 12 carbon atoms, and a to f are Each is an integer from 0 to 4. An electrophotographic photosensitive member according to any one of claims 1 to 4,
Charging means for charging the surface of the electrophotographic photosensitive member;
Exposure means for exposing the surface of the electrophotographic photosensitive member to form an electrostatic latent image; and
Developing means for developing the electrostatic latent image as a toner image;
A transfer means for transferring the toner image from the electrophotographic photosensitive member to the transfer target, and
An image forming apparatus having no charge eliminating means for removing electric charges on the surface of an electrophotographic photosensitive member.

Images