Electrophotographic photoreceptor, process cartridge and image forming apparatus equipped with the same

Abstract

To provide an electrophotographic photoreceptor which suppresses damage to a photosensitive layer due to external light, has electrical properties that does not deteriorate during repetitive use, and allows for continuously obtaining good images, and to provide a process cartridge having the same and an image forming device.SOLUTION: An electrophotographic photoreceptor is provided, comprising at least a photosensitive layer, or at least a photosensitive layer and a protective layer laminated on the photosensitive layer. Either or both of the photosensitive layer and the protective layer contain(s) a perimidine compound represented by a general formula (I), where X represents a hydrogen atom, an alkyl group having 1-6 carbon atoms, or an alkoxy group having 1-6 carbon atoms, and m represents an integer of 1 to 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrophotographic photoreceptor, a process cartridge and an image forming apparatus equipped with the same. More specifically, the present invention relates to an electrophotographic photoreceptor in which damage to a photosensitive layer caused by external light is suppressed, electrical properties are not deteriorated during repeated use, and good image quality can be continuously obtained, and to a process cartridge and an image forming apparatus equipped with the same. [Background technology]

[0002] In recent years, organic photoreceptors using organic photoconductive materials (hereinafter referred to as "electrophotographic photoreceptors" or simply "photoreceptors") have been widely used as electrophotographic photoreceptors. However, organic photoreceptors have a problem in terms of light resistance, in that the photosensitive layer is deteriorated by light. Normally, photoconductors are used in a light-shielded state inside image forming devices such as copiers and laser printers, and are not exposed to external light such as fluorescent lights, but the photoconductor is exposed to external light when assembling the machine (image forming device) or replacing the photoconductor, for example when a paper jam occurs and the photoconductor is removed from the machine. Since the light intensity of external light is much stronger than the exposure intensity for image formation within the machine, exposure of the photoconductor to external light can cause significant damage, which can cause problems in image formation.

[0003] Therefore, various efforts have been made to solve the above problems. For example, JP 10-048856 A (Patent Document 1) proposes a photoreceptor containing a fluorene compound of a specific structure and a compound having a maximum absorption wavelength in the range of 380 to 480 nm, JP 2016-143024 A (Patent Document 2) proposes a photoreceptor having a photosensitive layer containing a benzophenone-based ultraviolet absorber having an absorption wavelength in the range of 280 to 380 nm, and JP 2012-103333 A (Patent Document 3) proposes a photoreceptor having a photosensitive layer containing a light-absorbing compound having at least one maximum value of absorbance in the range of 420 to 520 nm. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-048856 [Patent Document 2] JP2016-143024A [Patent Document 3] JP2012-103333A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned prior art, a light absorbing compound having a specific wavelength or an ultraviolet absorbing agent is added to the photosensitive layer of the photoreceptor to reduce light damage to the photoreceptor. However, these added compounds significantly deteriorate the electrical properties of the photoreceptor when it is used repeatedly, which causes problems such as fogging and reduced image density. Therefore, an object of the present invention is to provide an electrophotographic photoreceptor which suppresses damage to the photosensitive layer caused by external light, does not deteriorate electrical characteristics during repeated use, and can continuously produce good image quality, as well as a process cartridge and an image forming apparatus equipped with the same. [Means for solving the problem]

[0006] As a result of extensive research aimed at solving the above problems, the inventors have discovered that by incorporating a specific perimidine compound in both or either one of the photosensitive layer and protective layer of a photoconductor, damage to the photosensitive layer caused by external light can be suppressed, electrical properties do not deteriorate during repeated use, and good image quality can be continuously obtained, thereby providing an electrophotographic photoconductor, and further a process cartridge and image forming apparatus equipped therewith, which have led to the completion of the present invention.

[0007] Thus, according to the present invention, there is provided an electroconductive electrophotographic recording medium comprising at least a photosensitive layer, or at least a photosensitive layer and a protective layer laminated on the photosensitive layer, on a conductive support, The photosensitive layer and / or the protective layer may be formed of a compound represented by the general formula (I): [ka] (In the formula, X is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and m is an integer of 1 to 6.) The present invention provides an electrophotographic photoreceptor comprising a perimidine compound represented by the following formula:

[0008] According to the present invention, there is also provided an image forming apparatus comprising at least the above-mentioned electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, exposure means for exposing the charged electrophotographic photosensitive member to light to form an electrostatic latent image, developing means for developing the electrostatic latent image formed by exposure to form a toner image, transfer means for transferring the toner image formed by development onto a recording medium, fixing means for fixing the transferred toner image on the recording medium to form an image, cleaning means for removing and recovering toner remaining on the electrophotographic photosensitive member, and discharging means for discharging surface charge remaining on the electrophotographic photosensitive member.

[0009] Furthermore, according to the present invention, there is provided a process cartridge comprising the above-mentioned electrophotographic photosensitive member, and at least one selected from a charging means for charging the electrophotographic photosensitive member, a developing means for developing an electrostatic latent image formed by exposure to light to form a toner image, and a cleaning means for removing toner remaining on the electrophotographic photosensitive member. Effect of the Invention

[0010] According to the present invention, it is possible to provide an electrophotographic photoreceptor in which damage to the photosensitive layer caused by external light is suppressed, there is no deterioration in electrical characteristics during repeated use, and good image quality can be continuously obtained, as well as a process cartridge and an image forming apparatus equipped with the same. The above-mentioned perimidine compound can absorb external light in the entire wavelength range of 480 to 600 nm, and does not absorb light in the wavelength range of 600 to 800 nm, such as exposure light from a laser of an image forming apparatus or static electricity removal light, so it is considered that the damage to the photosensitive layer caused by external light can be suppressed (reduced) without impairing the exposure light or static electricity removal light. In addition, the above-mentioned perimidine compound does not deteriorate the electrical properties of the photoconductor during repeated use. Furthermore, since the photoconductor of the present invention is prevented from being damaged by external light, the process cartridge equipped therewith is easy to handle. The above prior art does not describe or suggest the above perimidine compounds.

[0011] Damage to photoconductors caused by external light from fluorescent lamps and LEDs occurs when the external light penetrates the charge transport layer and acts on the charge generating material, generating charge traps.General fluorescent lamps have light wavelength components of around 440, 490, 550, 580, and 620 nm, while white LEDs have light wavelength components of 460 nm and 500 to 700 nm.When these lights penetrate the charge transport layer, they act on the charge generating material and generate charge traps. FIG. 4 shows the absorption spectrum of the perimidine compound represented by general formula (I) of the present invention, which has absorption in a wide range from 480 to 600 nm. It is considered that, when added to a charge transport layer or a protective layer, it functions as a light absorbing compound and can effectively block the action of the above-mentioned light wavelength components on the charge generating substance. In addition, light wavelength components of 600 to 800 nm must be transmitted because they are used in LEDs and laser beams that expose a photoconductor to form an electrostatic latent image, and LEDs that remove residual surface charges on a photoconductor, etc. The perimidine compound of the present invention represented by the general formula (I) does not absorb light in the 600 to 800 nm range, and is therefore considered to be very suitable with little adverse effect on electrical properties.

[0012] The photoreceptor of the present invention exhibits the above-mentioned effects more effectively when any one of the following conditions (1) to (6) is satisfied. (1) The perimidine compound is a compound in which the substituent X in the general formula (I) is a hydrogen atom and the index m is 6. (2) The photosensitive layer is a laminated type photosensitive layer in which a charge generating layer containing a charge generating substance and a charge transport layer containing a charge transport substance are laminated in this order from the conductive support side, and the charge transport layer contains a perimidine compound. (3) The perimidine compound is contained in an amount of 0.05 to 1.5% by mass based on the total solid content of the charge transport layer. (4) The charge transport layer has a thickness of 18 to 42 μm. (5) The protective layer contains a perimidine compound in an amount of 0.3 to 7% by mass based on the total solid content of the protective layer. (6) The protective layer has a thickness of 3 to 7 μm. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic cross-sectional view showing the configuration of a main part of a photoreceptor 1 of the present invention. [Diagram 2] 1 is a schematic cross-sectional view showing the configuration of a main part of a photoreceptor 2 of the present invention. [Diagram 3] 1 is a schematic side view illustrating a configuration of a main part of an image forming apparatus according to the present invention. [Figure 4] FIG. 1 is a diagram showing the absorption spectrum of a perimidine compound represented by general formula (I) of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (1) Electrophotographic Photoreceptor The photoreceptor of the present invention comprises at least a photosensitive layer on a conductive support, or at least a photosensitive layer and a protective layer laminated on the photosensitive layer, The photosensitive layer and / or the protective layer may be formed of a compound represented by the general formula (I):

[0015] [ka]

[0016] (In the formula, X is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and m is an integer of 1 to 6.) The composition is characterized in that it contains a perimidine compound represented by the following formula (hereinafter also referred to as "the perimidine compound of the present invention"). Below, (1) the photoreceptor will be described with respect to its structure and constituent materials, and (2) an image forming apparatus and (3) a process cartridge equipped with the photoreceptor will be described.

[0017] <Photoconductor> The photoreceptor of the present invention comprises at least a photosensitive layer on a conductive support, or at least a photosensitive layer and a protective layer laminated on the photosensitive layer. The photoreceptor of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto. The photoreceptor of the present invention may have an undercoat layer between the conductive support and the photosensitive layer, and may also have a protective layer on the photosensitive layer, i.e., the charge transport layer, as described below.

[0018] FIG. 1 is a schematic cross-sectional view showing the configuration of a main part of a photoreceptor 1 of the present invention. The photoreceptor 1 is a laminated photoreceptor (also referred to as a "function-separated photoreceptor") in which an undercoat layer 18 is provided on a conductive support 11, and a photosensitive layer 14 having a laminated structure (also referred to as a "laminated photosensitive layer" or "function-separated photosensitive layer") is provided on the undercoat layer 18, in which a charge generating layer 15 containing a charge generating substance 12, a charge transport substance 13, a binder resin 17 for binding the charge generating substance 12, and a charge transport layer 16 containing a perimidine compound 19 of the present invention are laminated in this order. As described above, the photosensitive layer of the photoreceptor of the present invention is a laminated type photosensitive layer in which a charge generating layer containing a charge generating substance and a charge transport layer containing a charge transport substance are laminated in this order from the conductive support side, and it is preferable that the charge transport layer contains the perimidine compound.

[0019] Fig. 2 is a schematic cross-sectional view showing the configuration of the main part of photoreceptor 2 of the present invention, and this photoreceptor 2 is a laminated type photoreceptor having a protective layer 20 containing perimidine compound 19 of the present invention on the outer side (photosensitive side) of photoreceptor 1 in Fig. 1. In photoreceptor 2, charge transport layer 16 does not contain perimidine compound 19 of the present invention, but in the photoreceptor of the present invention, both charge transport layer 16 and protective layer 20 may contain perimidine compound 19 of the present invention, or either one of charge transport layer 16 and protective layer 20 may contain perimidine compound 19 of the present invention. Each component will be described below.

[0020] <Conductive support 11> The conductive support has a function as an electrode for the photoreceptor and a function as a support member, and the material constituting the conductive support is not particularly limited as long as it is a material used in the relevant technical field. Specific examples include metal materials such as aluminum, aluminum alloys, copper, zinc, stainless steel, and titanium, as well as polymer materials such as polyethylene terephthalate, nylon, and polystyrene, whose surfaces are laminated with metal foil, subjected to metal vapor deposition, or vapor-deposited or coated with a layer of a conductive compound such as a conductive polymer, tin oxide, or indium oxide, as well as hard paper and glass. Among these, aluminum is preferred from the viewpoint of ease of processing, and aluminum alloys such as JIS 3003, JIS 5000, and JIS 6000 are particularly preferred. The shape of the conductive support is not limited to a cylindrical shape (drum shape) as shown in FIG. 5, but may be a sheet shape, a columnar shape, an endless belt shape, or the like. In addition, the surface of the conductive support may be subjected to anodizing film treatment, surface treatment with chemicals or hot water, coloring treatment, or diffuse reflection treatment such as surface roughening, as necessary, to prevent interference fringes caused by laser light, within a range that does not affect image quality.

[0021] <Undercoat layer (also called "middle layer") 18> The photoreceptor of the present invention preferably includes an undercoat layer 18 between the conductive substrate 11 and the photosensitive layer 14 . The undercoat layer generally covers the unevenness of the surface of the conductive support to make it uniform, improves the film-forming property of the photosensitive layer, here the charge generating layer, suppresses the peeling of the photosensitive layer from the conductive support, and improves the adhesion between the conductive support and the photosensitive layer. Specifically, it prevents the injection of charges from the conductive support into the photosensitive layer, prevents the chargeability of the photosensitive layer from decreasing, and prevents fogging of the image (so-called black spots).

[0022] The undercoat layer can be formed, for example, by dissolving a binder resin in a suitable solvent to prepare a coating liquid for the undercoat layer, coating this coating liquid on the surface of the conductive support, and removing the organic solvent by drying.

[0023] Examples of the binder resin include the same binder resin as that contained in the photosensitive layer described below, as well as natural polymeric materials such as casein, gelatin, polyvinyl alcohol, and ethyl cellulose, and one or more of these can be used. The binder resin is required to have properties such as not dissolving or swelling in the solvent used when forming the photoreceptor layer on the undercoat layer, excellent adhesion to the conductive support, and flexibility. Therefore, among the above-mentioned binder resins, polyamide resins are preferred, and alcohol-soluble nylon resins are particularly preferred. Examples of alcohol-soluble nylon resins include homopolymer or copolymer nylons such as 6-nylon, 66-nylon, 610-nylon, 11-nylon, and 12-nylon, and resins obtained by chemically modifying nylons such as N-alkoxymethyl-modified nylons.

[0024] Examples of solvents for dissolving or dispersing resin materials include water, alcohols such as methanol, ethanol, and butanol, glymes such as methyl carbitol and butyl carbitol, chlorine-based solvents such as dichloroethane, chloroform, and trichloroethane, acetone, dioxolane, mixed solvents of two or more of these solvents, etc. Among these solvents, non-halogenated organic solvents are preferably used in consideration of the global environment.

[0025] The coating liquid for forming the undercoat layer may also contain metal oxide particles 19 . The metal oxide particles can easily adjust the volume resistivity of the undercoat layer, can further suppress the injection of charges into the photosensitive layer, and can maintain the electrical characteristics of the photoreceptor under various environments. Examples of metal oxide particles include titanium oxide, aluminum oxide, aluminum hydroxide, and tin oxide. The ratio (C / D) of the total mass C of the binder resin and metal oxide particles to the mass D of the solvent in the coating liquid for the undercoat layer is preferably from 1 / 99 to 40 / 60, particularly preferably from 2 / 98 to 30 / 70. The ratio E / F of the mass E of the binder resin to the mass F of the metal oxide particles is preferably 90 / 10 to 1 / 99, and particularly preferably 70 / 30 to 5 / 95.

[0026] In order to disperse the metal oxide particles in the coating liquid for the undercoat layer, known devices such as a ball mill, a sand mill, an attritor, a vibration mill, an ultrasonic disperser, and a paint shaker may be used. The coating method for the undercoat layer coating liquid may be appropriately selected from among the most suitable methods taking into consideration the physical properties of the coating liquid and productivity, and examples of the method include spraying, bar coating, roll coating, blade coating, ring coating, and dip coating. Among these, the dip coating method is a method in which a substrate is immersed in a coating tank filled with a coating liquid, and then pulled up at a constant speed or a gradually changing speed to form a layer on the surface of the substrate, and is relatively simple and has excellent productivity and cost, so that it can be suitably used for manufacturing photoreceptors. The apparatus used for the dip coating method may be provided with a coating liquid dispersion device, typically an ultrasonic generator, in order to stabilize the dispersibility of the coating liquid.

[0027] The solvent in the coating film may be removed by natural drying, but the solvent in the coating film may also be removed forcibly by heating. The temperature in such a drying step is not particularly limited as long as it is a temperature at which the solvent used can be removed, but a temperature of about 50 to 140°C is appropriate, and a temperature of about 80 to 130°C is particularly preferable. If the drying temperature is less than 50°C, the drying time may be long and the solvent may not evaporate sufficiently and remain in the photoreceptor layer, while if the drying temperature exceeds about 140°C, the electrical characteristics of the photoreceptor may deteriorate during repeated use, resulting in poor quality of the obtained image. Such temperature conditions are common not only to the formation of the undercoat layer, but also to the formation of layers such as the photosensitive layer, which will be described later, and other treatments.

[0028] The thickness of the undercoat layer is not particularly limited, but is preferably 0.01 to 20 μm, and more preferably 0.05 to 10 μm. If the thickness of the undercoat layer is less than 0.01 μm, it will not function as an undercoat layer, and it may not be possible to cover defects in the conductive support to obtain a uniform surface, and it may not be possible to prevent injection of charges from the conductive support into the photosensitive layer. On the other hand, if the thickness of the undercoat layer is more than 20 μm, it is difficult to form a uniform undercoat layer, and the sensitivity of the photoreceptor may also decrease. When the conductive support is made of aluminum, a layer containing alumite (alumite layer) may be formed as the undercoat layer.

[0029] <Charge generating layer 15> The charge generating layer has a function of generating charges by absorbing light irradiated by, for example, semiconductor laser light in an image forming apparatus, and contains a charge generating substance as a main component and, if necessary, a binder resin and additives.

[0030] The charge generating material can be a compound used in the field, specifically, azo pigments such as monoazo pigments, bisazo pigments and trisazo pigments; indigo pigments such as indigo and thioindigo; perylene pigments such as peryleneimide and perylene acid anhydride; polycyclic quinone pigments such as anthraquinone and pyrenequinone; phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine such as titanyl phthalocyanine; organic photoconductive materials such as squarylium dyes, pyrylium salts, thiopyrylium salts, triphenylmethane dyes; and inorganic photoconductive materials such as selenium and amorphous silicon, and can be appropriately selected and used from those having sensitivity in the exposure wavelength range. These charge generating materials can be used alone or in combination of two or more. Among these charge generating materials, those represented by the following general formula (A):

[0031] [ka]

[0032] (In the formula, X 1 , X 2 , X 3 and X 4 are the same or different and each is a halogen atom, an alkyl group, or an alkoxy group, and r, s, y, and z are the same or different and each is an integer of 0 to 4. It is preferable to use titanyl phthalocyanine represented by the following formula: Titanyl phthalocyanine is a charge generating material that has high charge generation efficiency and charge injection efficiency in the emission wavelength range (near infrared light) of laser light and LED light that are currently in common use, and generates a large amount of charge by absorbing light, and can efficiently inject the generated charge into charge transport material 13 without accumulating it inside.

[0033] The titanyl phthalocyanine represented by the general formula (A) can be produced by known production methods, such as the method described in Phthalocyanine Compounds by Moser, Frank H. and Arthur L. Thomas, Reinhold Publishing Corp., New York, 1963. For example, among the titanyl phthalocyanine compounds represented by the general formula (A), in the case of an unsubstituted titanyl phthalocyanine in which r, s, y, and z are 0, it can be obtained by synthesizing dichlorotitanyl phthalocyanine by heating and melting phthalonitrile and titanium tetrachloride or by heating and reacting them in a suitable solvent such as α-chloronaphthalene, and then hydrolyzing the resultant with a base or water. Alternatively, the titanyl phthalocyanine composition can be produced by reacting isoindoline with a titanium tetraalkoxide such as tetrabutoxytitanium under heating in a suitable solvent such as N-methylpyrrolidone.

[0034] The method for forming the charge generation layer includes a method of vacuum-depositing the charge generation material on the conductive support, and a method of dispersing the charge generation material in a solvent and applying a coating liquid for the charge generation layer onto the conductive support. Among these, a method of dispersing the charge generation material in a binder resin solution obtained by mixing a binder resin in a solvent by a conventionally known method and applying the coating liquid for the charge generation layer onto the conductive support is preferred. This method will be described below.

[0035] The binder resin is not particularly limited, and any resin known in the art can be used. Examples of the binder resin include polyester, polystyrene, polyurethane, phenolic resin, alkyd resin, melamine resin, epoxy resin, silicone resin, acrylic resin, methacrylic resin, polycarbonate, polyarylate, polyphenoxy, polyvinyl butyral, and polyvinyl formal resins, as well as copolymer resins containing two or more of the repeating units constituting these resins. Examples of the copolymer resin include insulating resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and acrylonitrile-styrene copolymer resin. These resins can be used alone or in combination of two or more.

[0036] Examples of the solvent include halogenated hydrocarbons such as dichloromethane and dichloroethane, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran (THF) and dioxane, alkyl ethers of ethylene glycol such as 1,2-dimethoxyethane, aromatic hydrocarbons such as benzene, toluene and xylene, and aprotic polar solvents such as N,N-dimethylformamide and N,N-dimethylacetamide. These solvents can be used alone or in combination of two or more.

[0037] The compounding ratio between the charge generating substance and the binder resin is preferably such that the proportion of the charge generating substance is within a range of 10 to 99 mass %. If the ratio of the charge generating material is less than 10% by mass, the sensitivity may decrease. On the other hand, if the ratio of the charge generating material is more than 99% by mass, not only the film strength of the charge generating layer decreases, but also the dispersibility of the charge generating material decreases, the number of coarse particles increases, and the surface charge decreases in areas other than those that should be erased by exposure, resulting in image defects, particularly image fogging called black spots, in which toner adheres to a white background and tiny black spots are formed.

[0038] Before dispersing the charge generating material in the binder resin solution, the charge generating material may be pulverized in advance using a pulverizer such as a ball mill, a sand mill, an attritor, a vibration mill, or an ultrasonic disperser. Examples of dispersing machines used when dispersing the charge generating material in the binder resin solution include a paint shaker, a ball mill, a sand mill, etc. Appropriate dispersion conditions may be selected so as to prevent the incorporation of impurities due to wear of the container and members constituting the dispersing machine. The coating liquid for the charge generating layer may be applied by the same method as the coating liquid for the undercoat layer, and a dip coating method is particularly preferred.

[0039] The thickness of the charge generating layer is not particularly limited, but is preferably 0.05 to 5 μm, and more preferably 0.1 to 1 μm. If the thickness of the charge generating layer is less than 0.05 μm, the efficiency of light absorption decreases, and the sensitivity of the photoconductor may decrease. On the other hand, if the thickness of the charge generating layer is more than 5 μm, the charge transfer inside the charge generating layer becomes the rate-limiting step in the process of erasing the charge on the surface of the photoconductor, and the sensitivity of the photoconductor may decrease.

[0040] <Charge transport layer 16> The charge transport layer has the function of receiving the charges generated by the charge generating substance and transporting them to the surface of the photoreceptor, and contains a charge transport substance, a filler, a binder resin, the perimidine compound of the present invention as required, and other additives.

[0041] The perimidine compound of the present invention has the general formula (I):

[0042] [ka]

[0043] (In the formula, X is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and m is an integer of 1 to 6.) It is expressed as: Examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, and n-hexyl. Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, tert-butoxy, n-pentyloxy, and n-hexyloxy. Among these, from the viewpoints of obtaining the excellent effects of the present invention and of easy availability of materials, a perimidine compound in which the substituent X in the general formula (I) is a hydrogen atom and the index m is 6, namely, the compound X is a hydrogen atom (CI Solvent Red 179), is particularly preferred.

[0044] The perimidine compound of the present invention can be synthesized by the method described in Examples 1 and 4 of JP-A-2001-501667. In addition, there are commercially available products such as Amesolve Red A manufactured by American Dyestuff, KP Plast Red H2G manufactured by Kiwa Chemical Industry Co., Ltd., and Red E2G manufactured by Toyo Science Co., Ltd., which can be used in the present invention.

[0045] As the charge transport material, compounds used in the art can be used. Specific examples thereof include carbazole derivatives, pyrene derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, polycyclic aromatic compounds, indole derivatives, pyrazoline derivatives, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, triarylmethane derivatives, phenylenediamine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, benzidine derivatives, polymers having groups derived from these compounds in the main chain or side chain (poly-N-vinylcarbazole, poly-1-vinylpyrene, ethylcarbazole-formaldehyde resin, triphenylmethane polymer, poly-9-vinylanthracene, etc.), and polysilanes. These charge transport materials can be used alone or in combination of two or more.

[0046] Among these various charge transport materials, in terms of electrical properties, durability and chemical stability, stilbene derivatives, butadiene derivatives, enamine derivatives and compounds in which a plurality of these compounds are combined are preferred, and stilbene derivatives are more preferred, and are represented by the following general formula (II):

[0047] [ka]

[0048] (In the formula, R 1 , R 2 , R 5 and R 6 are the same or different and each is an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom; m, n, p, and q are the same or different and each is an integer of 0 to 3; R 3 and R 4 are the same or different and are a hydrogen atom or an alkyl group. Particularly preferred is a stilbene compound represented by the following formula:

[0049] The substituent R in the general formula (II) 1 , R 2 , R 5 and R 6 This article explains: Examples of the alkyl group include alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, and n-hexyl. Examples of the alkoxy group include alkoxy groups having 1 to 6 carbon atoms, such as methoxy, ethoxy, n-propoxy, isopropoxy, tert-butoxy, n-pentyloxy, and n-hexyloxy. Examples of the aryl group include phenyl, naphthyl, anthryl, phenanthryl, fluorenyl, biphenylyl, and o-terphenyl. Aralkyl groups include, for example, benzyl, phenethyl, benzhydryl, trityl, and the like. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine.

[0050] Substituent R 1 , R 2 , R 5 and R 6 The indices m, n, p and q are the same or different and are integers of 0 to 3, and when the index is 2 or more, each substituent may be different from each other. In addition, the substituent R in the general formula (II) 3 and R 4 Examples of the alkyl group include alkyl groups having 1 to 3 carbon atoms, such as methyl, ethyl, n-propyl, and isopropyl. The stilbene compound represented by the general formula (II) can be synthesized, for example, by the method described in Japanese Patent No. 3272257.

[0051] Examples of the stilbene compound represented by the general formula (II) include the following compounds (1) to (3), with compound (1) being particularly preferred in terms of electrical properties and solubility.

[0052] [ka]

[0053] The method for forming the charge transport layer is preferably a method in which a charge transport material and the perimidine compound of the present invention are added to a binder resin solution obtained by mixing a binder resin in a solvent, and the resulting mixture is dispersed by a conventionally known method to form a charge transport layer coating liquid, which is then applied onto the charge generating layer. This method will be described below.

[0054] The binder resin is not particularly limited, and any resin known in the art can be used, for example, vinyl polymer resins such as polymethyl methacrylate, polystyrene, polyvinyl chloride, and copolymer resins thereof, as well as resins such as polycarbonate, polyester, polyester carbonate, polysulfone, polyphenoxy, epoxy resin, silicone resin, polyarylate, polyphenylene oxide, polyamide, polyether, polyurethane, polyacrylamide, and phenol resin, and thermosetting resins obtained by partially crosslinking these resins, etc. These binder resins can be used alone or in combination of two or more. Among these, polycarbonate resins and polyarylate resins are particularly preferred because they have excellent compatibility with charge transport materials and are also excellent in electrical insulation, transparency, electrical properties, film properties, abrasion resistance, and the like.

[0055] The ratio A / B of the charge transport material (A) to the binder resin (B) is preferably from 10 / 12 to 10 / 30. If the ratio A / B is less than 10 / 30 and the ratio of the binder resin is high, when the charge transport layer is formed by dip coating, the viscosity of the coating liquid increases, leading to a decrease in the coating speed and a significant decrease in productivity. In addition, if the amount of solvent in the coating liquid is increased to suppress the increase in the viscosity of the coating liquid, a blushing phenomenon may occur and the formed charge transport layer may become cloudy. On the other hand, if the ratio A / B exceeds 10 / 12 and the ratio of the binder resin is low, the printing durability may be lower than when the ratio of the binder resin is high, and the amount of wear of the photosensitive layer may increase.

[0056] The perimidine compound is preferably contained in an amount of 0.05 to 1.5% by mass based on the total solid content of the charge transport layer. If the content of the perimidine compound is less than 0.05% by mass, the effect on light resistance may not be sufficient. On the other hand, if the content of the perimidine compound is more than 1.5% by mass, the electrical properties may deteriorate. The content of the perimidine compound is more preferably 0.15 to 0.80% by mass.

[0057] The charge transport layer may contain additives such as a plasticizer or a leveling agent, if necessary, in order to improve film formability, flexibility and surface smoothness. Examples of the plasticizer include dibasic acid esters such as phthalic acid esters, fatty acid esters, phosphate esters, chlorinated paraffin, and epoxy type plasticizers. The leveling agent may be, for example, a silicone-based leveling agent. The charge transport layer may contain fine particles of an inorganic or organic compound in order to increase the mechanical strength and improve the electrical characteristics.

[0058] Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and monochlorobenzene, halogenated hydrocarbons such as dichloromethane and dichloroethane, ethers such as THF, dioxane, and dimethoxymethyl ether, and aprotic polar solvents such as N,N-dimethylformamide. If necessary, solvents such as alcohols, acetonitrile, or methyl ethyl ketone can also be added. Among these solvents, non-halogenated organic solvents are preferably used in consideration of the global environment. These solvents can be used alone or in combination of two or more.

[0059] The charge transport layer is formed, for example, in the same manner as in the case of forming the above-mentioned charge generation layer 15, by preparing a coating liquid for the charge transport layer by dissolving or dispersing the charge transport material 13 and the binder resin 17, and, if necessary, the above-mentioned additives, in an appropriate solvent, and applying this coating liquid onto the charge generation layer 15 by a spray method, a bar coating method, a roll coating method, a blade method, a ring method, a dip coating method, or the like. Among these coating methods, the dip coating method is particularly excellent in various respects as described above, and is therefore often used in forming the charge transport layer.

[0060] The charge transport layer preferably has a thickness of 18 to 42 μm. If the thickness of the charge transport layer is less than 18 μm, the effect on light resistance may not be sufficient. On the other hand, if the thickness of the charge transport layer is more than 42 μm, the electrical characteristics may deteriorate. The thickness of the charge transport layer is more preferably 25 to 37 μm.

[0061] <Protective layer> The photoreceptor of the present invention may have a protective layer on the photosensitive layer as shown in FIG. The protective layer has a function of improving the durability of the photoreceptor, and contains a binder resin, the perimidine compound of the present invention as necessary, and other additives. The protective layer may also contain one or more of the same charge transport materials as the charge transport layer in order to stabilize the electrical characteristics. As the binder resin, a resin having binding properties used in the relevant field can be used, such as polystyrene, polyacetal, polyethylene, polycarbonate, polyarylate, polysulfone, polypropylene, polyvinyl chloride, etc. These binder resins can be used alone or in combination of two or more. Among these, polycarbonate and polyarylate are particularly preferable in consideration of wear characteristics and electrical characteristics.

[0062] The protective layer may also contain a filler material for the purpose of improving abrasion resistance. Examples of organic filler materials include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, and a-carbon powder. Examples of inorganic filler materials include metal powders such as copper, tin, aluminum, and indium, metal oxides such as silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, antimony-doped tin oxide, and tin-doped indium oxide, and inorganic materials such as potassium titanate. In terms of the hardness of the filler, inorganic filler materials are particularly preferred. The average primary particle size of the filler is preferably 0.01 to 0.5 μm from the viewpoints of the light transmittance and abrasion resistance of the protective layer. The filler material may be surface-treated with an inorganic or organic substance in order to improve dispersibility in a coating liquid for coating formation, etc. Examples of the surface-treatment include treatment with a silane coupling agent, a fluorine-based silane coupling agent, or a higher fatty acid as a water-repellent treatment, and treatment of the filler surface with alumina, zirconia, tin oxide, or silica. The higher the content of the filler material in the protective layer, the better the abrasion resistance, but it may cause adverse effects such as deterioration of electrical properties and reduction in the writing light transmittance of the protective layer. Therefore, the content of the filler material is approximately 50% by mass or less, preferably 30% by mass or less, based on the total solid content.

[0063] The perimidine compound is preferably contained in an amount of 0.3 to 7% by mass based on the total solid content of the protective layer. If the content of the perimidine compound is less than 0.3% by mass, the effect on light resistance may not be sufficient. On the other hand, if the content of the perimidine compound is more than 7% by mass, the electrical properties may deteriorate. The content of the perimidine compound is more preferably 1 to 4% by mass.

[0064] The protective layer preferably has a thickness of 3 to 7 μm. If the thickness of the protective layer is less than 3 μm, the durability and light resistance may not be sufficiently improved. On the other hand, if the thickness of the protective layer is more than 7 μm, the electrical properties may deteriorate. The thickness of the protective layer is more preferably 4 to 6 μm.

[0065] (2) Image forming apparatus 100 The image forming apparatus of the present invention is characterized by comprising at least the photoconductor of the present invention, charging means for charging the photoconductor, exposure means for exposing the charged photoconductor to form an electrostatic latent image, developing means for developing the electrostatic latent image formed by exposure to form a toner image (visible image), transfer means for transferring the toner image formed by development onto a recording medium, fixing means for fixing the transferred toner image on the recording medium to form an image, cleaning means for removing and recovering toner remaining on the photoconductor, and discharging means for discharging surface charge remaining on the photoconductor. The image forming apparatus of the present invention and its operation will be described with reference to the drawings, but the present invention is not limited to the following description.

[0066] FIG. 2 is a schematic side view showing the configuration of the image forming apparatus of the present invention. 2 includes the photoreceptor 1 of the present invention, an exposure means (semiconductor laser) 31, a charging means (charger) 32, a developing means (developer) 33, a transfer means (transfer charger) 34, a conveyor belt (not shown), a fixing means (fixer) 35, and a cleaning means (cleaner) 36. Reference numeral 51 denotes a recording medium (recording paper or transfer paper).

[0067] Photoconductor 1 is rotatably supported by the main body of image forming apparatus 100, and is driven to rotate around rotation axis 44 in the direction of arrow 41 by driving means (not shown). The driving means includes, for example, an electric motor and a reduction gear, and transmits its driving force to a conductive support constituting the core body of photoconductor 1, thereby driving and rotating photoconductor 1 at a predetermined peripheral speed. Charging means (charger) 32, exposure means 31, developing means (developer) 33, transfer means (transfer charger) 34, and cleaning means (cleaner) 36 are provided in this order along the outer circumferential surface of photoconductor 1 from the upstream side to the downstream side in the rotation direction of photoconductor 1 indicated by arrow 41.

[0068] The charger 32 is a charging means for uniformly charging the outer circumferential surface of the photoreceptor 1 to a predetermined potential. The exposure means 31 has a semiconductor laser as a light source, and irradiates the surface of the photoreceptor 1 between the charger 32 and the developer 33 with a laser beam light output from the light source, thereby exposing the charged outer peripheral surface of the photoreceptor 1 according to image information. The light is repeatedly scanned in the direction of extension of the rotation axis 44 of the photoreceptor 1, which is the main scanning direction, and these are focused to sequentially form electrostatic latent images on the surface of the photoreceptor 1. In other words, the charge amount of the photoreceptor 1, which has been uniformly charged by the charger 32, differs depending on whether it is irradiated with the laser beam or not, and an electrostatic latent image is formed.

[0069] The developing device 33 is a developing means that develops the electrostatic latent image formed on the surface of the photoconductor 1 by exposure with a developer (toner), and is provided facing the photoconductor 1. The developing device 33 includes a developing roller 33a that supplies toner to the outer peripheral surface of the photoconductor 1, and a casing 33b that rotatably supports the developing roller 33a about a rotation axis parallel to the rotation axis 44 of the photoconductor 1 and contains a developer including toner in its internal space.

[0070] The transfer charger 34 is a transfer means that transfers a toner image, which is a visible image formed on the outer peripheral surface of the photoconductor 1 by development, onto a transfer paper 51, which is a recording medium, supplied between the photoconductor 1 and the transfer charger 34 from the direction of the arrow 42 by a transport means (not shown). The transfer charger 34 is, for example, a contact type transfer means that includes a charging means and transfers the toner image onto the transfer paper 51 by applying a charge of the opposite polarity to that of the toner to the transfer paper 51.

[0071] The cleaner 36 is a cleaning means for removing and recovering the toner remaining on the outer peripheral surface of the photoreceptor 1 after the transfer operation by the transfer charger 34, and includes a cleaning blade 36a for removing the toner remaining on the outer peripheral surface of the photoreceptor 1, and a recovery casing 36b for containing the toner removed by the cleaning blade 36a. The cleaner 36 is also provided together with a static elimination lamp (not shown).

[0072] Furthermore, in the image forming apparatus 100, a fixing device 35, which is a fixing means for fixing a transferred image, is provided downstream of the conveyance of the transfer paper 51 that has passed between the photoconductor 1 and the transfer charger 34. The fixing device 35 includes a heating roller 35a having a heating means (not shown), and a pressure roller 35b that is provided opposite the heating roller 35a and is pressed against the heating roller 35a to form a contact portion. Reference numeral 37 denotes a separating means for separating the transfer paper from the photosensitive member, and reference numeral 38 denotes a casing for accommodating the above-mentioned means of the image forming apparatus.

[0073] The image forming operation by this image forming apparatus 100 is carried out as follows. First, when the photoconductor 1 is rotated in the direction of arrow 41 by the driving means, the surface of the photoconductor 1 is uniformly charged to a predetermined positive potential by the charger 32, which is provided upstream of the image-forming point of the light by the exposure means 31 in the rotational direction of the photoconductor 1.

[0074] Next, light according to image information is irradiated from exposure means 31 onto the surface of photoreceptor 1. This exposure removes surface charge from the areas of photoreceptor 1 irradiated with light, creating a difference in surface potential between the areas irradiated with light and the areas not irradiated with light, forming an electrostatic latent image. Toner is supplied from a developing device 33, which is provided downstream in the rotational direction of the photoconductor 1 from the imaging point of the light by the exposure means 31, to the surface of the photoconductor 1 on which the electrostatic latent image is formed, thereby developing the electrostatic latent image and forming a toner image.

[0075] In synchronization with the exposure of the photoconductor 1, a transfer paper 51 is supplied between the photoconductor 1 and the transfer charger 34. The transfer charger 34 gives the supplied transfer paper 51 a charge of the opposite polarity to that of the toner, and the toner image formed on the surface of the photoconductor 1 is transferred onto the transfer paper 51. The transfer paper 51 onto which the toner image has been transferred is transported by the transport means to the fixing device 35, and is heated and pressurized as it passes through the contact area between the heating roller 35a and the pressure roller 35b of the fixing device 35, and the toner image is fixed onto the transfer paper 51 to form a robust image. The transfer paper 51 on which the image has been formed in this way is discharged to the outside of the image forming apparatus 100 by the transport means.

[0076] Meanwhile, the toner remaining on the surface of the photoreceptor 1 after the transfer of the toner image by the transfer charger 34 is peeled off from the surface of the photoreceptor 1 and collected by the cleaner 36. The charge on the surface of the photoreceptor 1 from which the toner has been removed in this manner is removed by light from a discharging lamp, and the electrostatic latent image on the surface of the photoreceptor 1 disappears. The photoreceptor 1 is then rotated again, and the series of operations starting with charging are repeated again to form images continuously.

[0077] (3) Process cartridge The process cartridge of the present invention is characterized by comprising the photosensitive member of the present invention, and at least one selected from a charging means for charging the photosensitive member, a developing means for developing an electrostatic latent image formed by exposure to light to form a toner image, and a cleaning means for removing toner remaining on the photosensitive member.

[0078] For example, the process cartridge of the present invention is constructed by integrating the photoconductor, charging device, developing device, and cleaning device of the present invention with a support member. When such a process cartridge is incorporated into the image forming apparatus 100, each of the components of the process cartridge is provided in the image forming apparatus 100. The process cartridge is detachable from the image forming apparatus 100, which makes it easy to replace it when it becomes worn out. EXAMPLES

[0079] The present invention will be specifically described below with reference to examples and comparative examples based on the drawings, but the present invention is not limited to these examples.

[0080] Example 1 Three parts by weight of titanium oxide (manufactured by Ishihara Sangyo Kaisha, Ltd., product name: Tiebaque TTO-D-1) and two parts by weight of copolymer polyamide (nylon) (manufactured by Toray Industries, Inc., product name: Amilan (registered trademark), grade: CM8000) were added to 25 parts by weight of methyl alcohol, and the mixture was dispersed for eight hours using a paint shaker to prepare 3 liters of a coating solution for the undercoat layer. The obtained undercoat layer coating liquid was filled into a coating layer, and an aluminum drum-shaped support having a diameter of 30 mm and a length of 255 mm as the conductive support 11 was immersed in it and then removed. The obtained coating film was allowed to dry naturally, thereby forming an undercoat layer 18 with a thickness of 1 μm on the conductive support 11.

[0081] Titanyl phthalocyanine represented by the following structural formula, which was to be used as a charge generating material, was prepared in advance. [ka]

[0082] 29.2 g of diiminoisoindoline and 200 ml of sulfolane were mixed, and 17.0 g of titanium tetraisopropoxide was added and reacted under a nitrogen atmosphere at 140° C. for 2 hours. The resulting reaction mixture was allowed to cool, and the precipitate was collected by filtration, washed successively with chloroform and a 2% aqueous hydrochloric acid solution, further washed successively with water and methanol, and dried to obtain 25.5 g of blue-purple crystals. As a result of chemical analysis of the obtained compound, it was confirmed that it was titanyl phthalocyanine represented by the above structural formula (yield 88.5%). 1 part by weight of the obtained titanyl phthalocyanine and 1 part by weight of butyral resin (manufactured by Sekisui Chemical Co., Ltd., product name: S-LEC BM-2) were added to 98 parts by weight of methyl ethyl ketone, and the mixture was dispersed for 2 hours using a paint shaker to prepare 3 liters of a coating solution for the charge generating layer. The obtained coating liquid for the charge generating layer was applied onto the undercoat layer by the same dipping method as in the formation of the undercoat layer, and the obtained coating film was allowed to dry naturally to form a charge generating layer having a thickness of 0.3 μm.

[0083] Next, 250 g of compound (1) as a charge transport material, 375 g of polycarbonate (manufactured by Teijin Chemical Co., Ltd., product name: TS2050), and 1.15 g of the compound of general formula (I) (manufactured by American Dyestuff, product name: Amesolve Red A) were added to 2500 g of tetrahydrofuran, mixed, and stirred in a ball mill for 15 hours to prepare 3126 g of a coating solution for the charge transport layer. The obtained coating solution for the charge transport layer was applied onto the charge generation layer by the same immersion method as in the formation of the undercoat layer, and the obtained coating film was dried at 120°C for 1 hour to form a charge transport layer with a thickness of 36 μm, thereby obtaining the photoreceptor shown in Figure 1. Compound (1) (stilbene compound) previously prepared according to the method described in Japanese Patent No. 3272257 was used as the charge transport material.

[0084] Example 2 A photoreceptor was produced in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was changed from 1.15 g to 4.38 g.

[0085] Example 3 A photoreceptor was prepared in the same manner as in Example 1, except that the thickness of the charge transport layer was changed from 36 μm to 26 μm.

[0086] Example 4 A photoreceptor was produced in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was changed from 1.15 g to 0.31 g.

[0087] Example 5 A photoreceptor was produced in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was changed from 1.15 g to 9.50 g.

[0088] Example 6 A photoreceptor was produced in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was changed from 1.15 g to 0.25 g.

[0089] Example 7 A photoreceptor was produced in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was changed from 1.15 g to 10.1 g.

[0090] Example 8 A photoreceptor was prepared in the same manner as in Example 5, except that the thickness of the charge transport layer was changed from 36 μm to 18 μm.

[0091] Example 9 A photoreceptor was prepared in the same manner as in Example 4, except that the thickness of the charge transport layer was changed from 36 μm to 42 μm.

[0092] Example 10 A photoreceptor was prepared in the same manner as in Example 5, except that the thickness of the charge transport layer was changed from 36 μm to 17 μm.

[0093] Example 11 A photoreceptor was prepared in the same manner as in Example 4, except that the thickness of the charge transport layer was changed from 36 μm to 44 μm.

[0094] Example 12 In the same manner as in Example 1, an undercoat layer and a charge generating layer were formed. Next, 250 g of compound (1) as a charge transport material and 375 g of polycarbonate (manufactured by Teijin Chemical Co., Ltd., product name: TS2050) were added to 2500 g of tetrahydrofuran, mixed, and stirred in a ball mill for 15 hours to prepare 3125 g of a coating solution for the charge transport layer. The obtained coating liquid for the charge transport layer was applied onto the charge generation layer by the same immersion method as in the case of forming the undercoat layer, and the obtained coating film was dried at 120°C for 1 hour to form a charge transport layer with a thickness of 30 μm.

[0095] Next, 120 g of silica particles (manufactured by Nippon Aerosil Co., Ltd., product name: AEROSIL (registered trademark) RX200), 250 g of compound (1) as a charge transport material, 375 g of polycarbonate (manufactured by Teijin Chemical Co., Ltd., product name: TS2050), and 9.05 g of a compound of general formula (I) (manufactured by American Dyestuff, product name: Amesolve Red A) were added to 3500 g of tetrahydrofuran, mixed, and stirred for 15 hours in a ball mill. A 5-pass dispersion process was performed using a particle dispersion device (manufactured by Microfluidics, model: M-110P) to prepare 4041 g of a coating solution for a protective layer. The obtained protective layer coating liquid was applied onto the charge transport layer by a spray method, and the obtained coating film was dried at 120°C for 1 hour to form a protective layer with a thickness of 4.5 μm, thereby obtaining the photoreceptor shown in Figure 2. Compound (1) (stilbene compound) previously prepared according to the method described in Japanese Patent No. 3272257 was used as the charge transport material.

[0096] Example 13 A photoreceptor was produced in the same manner as in Example 12, except that in the preparation of the protective layer coating solution, the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was changed from 9.05 g to 29.40 g.

[0097] Example 14 A photoreceptor was prepared in the same manner as in Example 12, except that the thickness of the protective layer was changed from 4.5 μm to 5.5 μm.

[0098] Example 15 A photoreceptor was produced in the same manner as in Example 12, except that in the preparation of the protective layer coating solution, the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was changed from 9.05 g to 3.00 g.

[0099] (Example 16) A photoreceptor was produced in the same manner as in Example 12, except that in the preparation of the protective layer coating solution, the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was changed from 9.05 g to 3.00 g.

[0100] (Example 17) A photoreceptor was produced in the same manner as in Example 12, except that in the preparation of the protective layer coating solution, the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was changed from 9.05 g to 1.50 g.

[0101] (Example 18) A photoreceptor was produced in the same manner as in Example 12, except that in the preparation of the protective layer coating solution, the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was changed from 9.05 g to 1.15 g.

[0102] (Example 19) A photoreceptor was prepared in the same manner as in Example 16, except that the thickness of the protective layer was changed from 4.5 μm to 3.0 μm.

[0103] (Example 20) A photoreceptor was prepared in the same manner as in Example 15, except that the thickness of the protective layer was changed from 4.5 μm to 7.0 μm.

[0104] Example 21 A photoreceptor was prepared in the same manner as in Example 16, except that the thickness of the protective layer was changed from 4.5 μm to 2.0 μm.

[0105] Example 22 A photoreceptor was prepared in the same manner as in Example 15, except that the thickness of the protective layer was changed from 4.5 μm to 8.0 μm.

[0106] Example 23 A photoreceptor was produced in the same manner as in Example 12, except that 1.15 g of the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was added in preparing the coating liquid for the charge transport layer.

[0107] (Example 24) A photoreceptor was prepared in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, TPD (triphenylamine dimer) (manufactured by Tokyo Chemical Industry Co., Ltd., product name: D2448) was used instead of the charge transport material compound (1).

[0108] Comparative Example 1 A photoreceptor was produced in the same manner as in Example 1, except that 1.15 g of the compound of general formula (I) (manufactured by American Dyestuff, trade name: Amesolve Red A) was not used in the preparation of the coating liquid for the charge transport layer.

[0109] Comparative Example 2 A photoreceptor was prepared in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, a benzophenone-based ultraviolet absorber (2-hydroxy-4-methoxybenzophenone, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of the compound of general formula (I) (manufactured by American Dyestuff, product name: Amesolve Red A).

[0110] Comparative Example 3 A photoconductor was prepared in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, the compound of general formula (I) (manufactured by American Dyestuff, product name: Amesolve Red A) was replaced with the compound described in Example 1 of JP2012-103333 (manufactured by American Dyestuff, product name: Amesolve Red H).

[0111] Comparative Example 4 A photoconductor was prepared in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, the compound of general formula (I) (manufactured by American Dyestuff, product name: Amesolve Red A) was replaced with the compound described in Example 1 of JP-A-10-048856 (manufactured by American Dyestuff, product name: Amesolve Yellow Y).

[0112] [evaluation] The photoreceptors prepared in Examples 1 to 24 and Comparative Examples 1 to 4 were attached to the units of a digital copier (Model: MX-B455W, manufactured by Sharp Corporation) modified for testing, and electrical characteristics and light exposure were evaluated.

[0113] [Electrical characteristics (sensitivity)] The developing unit was removed from the copier and a surface potential meter (Trek Japan: Model 344) was installed in the developing area instead. In an environment with a temperature of 25°C and a relative humidity of 50%, the surface potential of the photoconductor without exposure was adjusted to -600V, and the surface potential VL(-V) of the black area was measured under that condition. From the results obtained, the sensitivity was evaluated according to the following criteria. <Judgment criteria> A: VL(-V)<80 Can be used without problems in high-speed multifunction machines or printers that require high sensitivity B: 80≦VL(-V)<110 Can be used without problems on low to medium speed multifunction devices or printers C: 110≦VL(-V)<140 If you have a slow, inexpensive multifunction device or printer, the density may be a little low, but it can be used without any problems. D: 140≦VL(-V) Poor sensitivity, low concentration, and problematic for practical use

[0114] [Light exposure evaluation] The surface of the photoreceptor was masked with black paper except for a part of it, and the unmasked part was irradiated with light from a white fluorescent lamp with a light intensity of 400 Lux for 5 minutes, after which it was left for 5 minutes and the halftone image was confirmed. The obtained images were evaluated according to the following criteria. <Judgment criteria> VG: No difference between irradiated and non-irradiated areas G: There is a slight difference between the irradiated and non-irradiated areas, but the difference is not significant. NB: There is a slight difference between the irradiated and non-irradiated areas, but this does not affect the actual use. B: There is a large difference between the irradiated and non-irradiated areas, which is problematic in practical use.

[0115] <Overall rating> Based on the above evaluation results, the photoreceptors were comprehensively evaluated according to the following criteria. VG: VG rating in all categories, very good condition G: Some items may be rated G, but all items are rated G or higher. Can be used without problems unless it is a high-quality multifunction device or printer. NB: Although some items have an NB rating, all items have an NB rating or higher, and can be used without problems if it is an inexpensive multifunction device or printer. B: Any item is rated B and cannot be used. The configurations of the prepared photoreceptors and the evaluation results are shown in Tables 1 and 2.

[0116] [Table 1]

[0117] [Table 2]

[0118] The results in Tables 1 and 2 reveal the following: (1) In electrophotographic photoreceptors having a charge transport layer and a protective layer, photoreceptors containing the perimidine compound of the present invention in either or both of the charge transport layer and the protective layer (Examples 1 to 23) have better electrical properties and excellent resistance to exposure to external light, compared with a photoreceptor not containing the perimidine compound of the present invention (Comparative Example 1), a photoreceptor containing a benzophenone-based ultraviolet absorber (Comparative Example 2), a photoreceptor containing the compound described in Example 1 of JP-A No. 2012-103333 (Patent Document 3) (Comparative Example 3), and a photoreceptor containing the compound described in Example 1 of JP-A No. 10-048856 (Patent Document 1) (Comparative Example 4).

[0119] (2) From the results of Examples 4 to 7, it is found that the amount of the perimidine compound of the present invention added to the charge transport layer is preferably 0.05 to 1.5 mass % based on the total solid content of the charge transport layer. If the amount added is less than 0.05%, the effect on light resistance is insufficient, and if the amount added exceeds 1.5 mass %, the electrical characteristics are deteriorated. Furthermore, from the results of Examples 1 and 2, it is found that a more preferable amount added is 0.15 to 0.80 mass %.

[0120] (3) From the results of Examples 8 to 12, it is found that the thickness of the charge transport layer is preferably 18 to 42 μm. If the thickness is thinner than 18 μm, the effect on light resistance is insufficient, and if the thickness exceeds 42 μm, the electrical characteristics are deteriorated. Furthermore, from the results of Examples 1 and 3, it is found that a more preferable thickness is 25 to 37 μm.

[0121] (4) From the results of Examples 15 to 18, it is found that the amount of the perimidine compound of the present invention added to the protective layer is preferably 0.3 to 7 mass % based on the total solid content of the protective layer, and that if the amount added is less than 0.3%, the effect on light resistance is insufficient, and if the amount added exceeds 7 mass %, the electrical characteristics are deteriorated. Furthermore, from the results of Examples 12 and 13, it is found that a more preferable amount added is 1.0 to 4.0 mass %.

[0122] (5) From the results of Examples 19 to 22, it is found that the thickness of the protective layer is preferably 3 to 7 μm. If the thickness is thinner than 3 μm, the effect on light resistance is insufficient, and if the thickness exceeds 7 μm, the electrical characteristics are deteriorated. Furthermore, from the results of Examples 12 and 14, it is found that a more preferable thickness is 4 to 6 μm. [Explanation of symbols]

[0123] 1, 2 Electrophotographic photoreceptor 11 Conductive support 12 Charge generating materials 13 Charge transport materials 14 Photosensitive layer (laminated photosensitive layer) 15 Charge generation layer 16 Charge transport layer 17 Binder resin (binding resin) 18 Undercoat layer (middle layer) 19 Perimidine Compounds 20 protective layer

[0124] 31 Exposure means (semiconductor laser) 32 Charging means (charger) 33 Developing means (developer) 33a Developing roller 33b Casing 34 Transfer means (transfer charger) 35 Fixing means (fixing device) 35a Heating roller 35b Pressure roller 36 Cleaning means (cleaner) 36a cleaning blade 36b Recovery casing 37 Separation means 38 Housing 41, 42 arrow mark 44 Rotation axis 51 Recording media (recording paper or transfer paper) 100 Image forming apparatus (laser printer)

Claims

1. A conductive substrate is provided with at least a photosensitive layer, or at least a photosensitive layer and a protective layer laminated on the photosensitive layer, The photosensitive layer and / or the protective layer may be formed of a compound represented by the general formula (I): 【Chemistry 1】 (In the formula, X is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and m is an integer of 1 to 6.) The compound contains a perimidine compound represented by the formula: When the photosensitive layer is selected, the photosensitive layer is a laminated type photosensitive layer in which a charge generating layer containing a charge generating substance and a charge transport layer containing a charge transport substance are laminated in this order from the conductive support side, and the charge transport layer contains the perimidine compound in a ratio of 0.18 to 0.70% by mass with respect to the total solid content of the charge transport layer, When the protective layer is selected, the protective layer contains the perimidine compound in an amount of 0.3 to 7% by mass based on the total solid content of the protective layer.

2. 2. The electrophotographic photoreceptor according to claim 1, wherein the perimidine compound is a compound of general formula (I) in which the substituent X is a hydrogen atom and the index m is 6.

3. 3. The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer has a thickness of 18 to 42 μm.

4. 4. The electrophotographic photoreceptor according to claim 1, wherein the protective layer has a thickness of 3 to 7 μm.

5. 5. A process cartridge comprising: the electrophotographic photosensitive member according to claim 1; and at least one selected from a charging unit that charges the electrophotographic photosensitive member, a developing unit that develops an electrostatic latent image formed by exposure to light to form a toner image, and a cleaning unit that removes toner remaining on the electrophotographic photosensitive member.

6. 5. An image forming apparatus comprising at least the electrophotographic photoreceptor according to claim 1, a charging means for charging the electrophotographic photoreceptor, an exposure means for exposing the charged electrophotographic photoreceptor to light to form an electrostatic latent image, a developing means for developing the electrostatic latent image formed by exposure to form a toner image, a transfer means for transferring the toner image formed by development onto a recording medium, a fixing means for fixing the transferred toner image on the recording medium to form an image, a cleaning means for removing and recovering toner remaining on the electrophotographic photoreceptor, and a discharging means for discharging surface charge remaining on the electrophotographic photoreceptor.

Images