JP6102639B2 - Electrophotographic photosensitive member, electrophotographic cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photoreceptor containing a stilbene compound having a specific structure in a photosensitive layer, which can be suitably used as a charge transport material for an electrophotographic photoreceptor, and an electrophotographic cartridge using the electrophotographic photoreceptor. And an image forming apparatus.

The electrophotographic technique is widely used in the fields of copiers, various printers, printing machines, etc. because it is excellent in immediacy and provides high-quality images. As an electrophotographic photoreceptor that is the core of electrophotographic technology, an electrophotographic photoreceptor using an organic photoconductive material (hereinafter simply referred to as “photosensitive material”) that has advantages such as non-pollution, easy film formation, and easy manufacture. Also referred to as "body").
In recent years, the use of image forming apparatuses such as electrophotographic copying machines has been expanded, and the market demand for image quality has been increasing. In particular, in office documents, in addition to the development of mapping technology and latent image forming technology for input, the types of character hieroglyphics are more abundant and finer at the time of output. Due to the spread and development, the reproducibility of a latent image with extremely high image quality that has few defects and unclearness in printed images is required.

  Furthermore, it is a common recognition in the industry that with the recent high performance and low cost of electrophotographic equipment, it is essential to increase the sensitivity of the electrophotographic photosensitive member and reduce the cost of the original material. Of these, in order to achieve high sensitivity, it is necessary not only to optimize the charge generation material, but also to develop a charge transport material with a good matching with it. It is necessary to develop charge transport materials that can be purified by reaction routes and simple purification steps. For this reason, high performance of charge transport materials having a low molecular weight has been attracting attention. The low molecular weight organic photoconductive material has the advantage of low production cost, and the physical properties or electrophotographic characteristics of the coating can be controlled by selecting the type and composition ratio of the binder to be used together. This is preferable because it is relatively easy.

  A stilbene compound is known as a low molecular weight charge transport material suitable for the above purpose. (For example, Patent Documents 1 to 3)

JP 2011-048199 A JP 2011-118342 A JP 2011-095418 A

  However, the stilbene compounds described in Patent Documents 1 to 3 have relatively good electrical properties when contained in the photosensitive layer, but have insufficient acid gas resistance, and are used repeatedly. The generation of memory, which is thought to be caused by the injection of positive charge into the photoreceptor, was significant. Here, the memory is a phenomenon in which an exposure history remains at the time of the next development at the time of image formation, and the previous image appears overlapping with the image to be formed next time. In particular, the occurrence of a positive type memory (a phenomenon in which an exposure history appears as a dark memory image in the next development) is remarkable, and improvement has been demanded.

As described above, the conventional techniques are not sufficiently effective in achieving high image quality of electrophotography, and there is still room for improvement.
The present invention has been made in view of the present situation, and the object thereof is an electrophotographic photosensitive member having good characteristics in photosensitivity and residual potential, excellent acid gas resistance, and repeated use. Another object of the present invention is to provide an electrophotographic photosensitive member that does not generate a positive type memory, and an electrophotographic cartridge and an image forming apparatus using the photosensitive member.

The present inventor has characteristics such as photosensitivity and residual potential that are inferior to those of conventional photoreceptors by containing a stilbene compound having a specific structure represented by the general formula [1] in the photosensitive layer of the electrophotographic photoreceptor. In addition, the acid gas resistance is improved relatively well and the generation of positive type memory can be suppressed. Photosensitivity, residual potential, endurance potential stability, environmental stability, halftone area blank The present invention has been found to exhibit excellent characteristics such as ghost (positive memory), etc., and the following invention has been completed.

That is, the first gist of the present invention is an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer comprises a stilbene compound having a structure represented by the following general formula [1]. The electrophotographic photosensitive member contains at least one kind (claim 1).

(In the formula [1], Ar ¹ represents an aryl group which may have an organic group having 1 to 4 carbon atoms as a substituent, R represents an alkyl group having 1 to 4 carbon atoms, Ar ² And Ar ³ each independently represents a hydrogen atom or an aryl group optionally having an alkyl group having 1 to 4 carbon atoms as a substituent, provided that Ar ² and Ar ³ are simultaneously a hydrogen atom. except for)
The second gist of the present invention is the above-described electrophotographic photosensitive member of the present invention, charging means for charging the electrophotographic photosensitive member, and an image for forming an electrostatic latent image by image exposure on the charged electrophotographic photosensitive member. An exposure unit; a developing unit that develops the electrostatic latent image with toner; a transfer unit that transfers the toner to a transfer target; a fixing unit that fixes the toner transferred to the transfer target; and the electrophotographic photosensitive member An electrophotographic cartridge comprising at least one selected from cleaning means for collecting the toner adhering to the body (claim 2).

  The third gist of the present invention is the above-described electrophotographic photosensitive member of the present invention, charging means for charging the electrophotographic photosensitive member, and exposure means for forming an electrostatic latent image by exposing the charged electrophotographic photosensitive member. And a developing unit that develops the electrostatic latent image with toner, a transfer unit that transfers the toner to a transfer target, and a fixing unit that fixes the toner transferred to the transfer target. The present invention resides in an image forming apparatus (claim 3).

The stilbene compound of the present invention has good characteristics such as photosensitivity and residual potential, and has strong acid gas resistance and good stability when used repeatedly. When used in an electrophotographic photosensitive member, it is possible to provide an electrophotographic photosensitive member that exhibits excellent electric potential stability during durability and environmental stability, and printing can be performed by using this electrophotographic photosensitive member. In some cases, it is possible to provide an electrophotographic cartridge and an image forming apparatus that are free from image defects such as white spots or ghosts in a solid portion or a halftone portion.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. 1 is an X-ray diffraction pattern of oxytitanium phthalocyanine used in Examples. It is IR spectrum of exemplary compound CT-1 of this invention. It is IR spectrum of exemplary compound CT-5 of this invention. It is IR spectrum of exemplary compound CT-9 of this invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiment, and various modifications can be made within the scope of the present invention. it can.
<< Stilbene compound having a structure represented by the general formula [1] >>
The stilbene compound used in the present invention has a structure represented by the following general formula [1].

(In the formula [1], Ar ¹ represents an aryl group which may have an organic group having 1 to 4 carbon atoms as a substituent, R represents an alkyl group having 1 to 4 carbon atoms, Ar ² And Ar ³ each independently represents a hydrogen atom or an aryl group optionally having an alkyl group having 1 to 4 carbon atoms as a substituent, provided that Ar ² and Ar ³ are simultaneously a hydrogen atom. except for)
In the formula [1], Ar ¹ is an aryl group optionally having an organic group having 1 to 4 carbon atoms as a substituent. Examples of such a substituent include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a dialkylamino group having 2 to 4 carbon atoms. Specifically, a methyl group, Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, methoxy group, ethoxy group, propoxy group, butoxy group, N, N-dimethylamino group, N, N-diethylamino group Etc. Among these, an organic group having 1 to 2 carbon atoms is more preferable from the viewpoint of electrical characteristics and production cost, and specific examples include a methyl group, a methoxy group, an ethyl group, and an ethoxy group. In view of improvement of acid resistance and positive memory, an alkyl group such as a methyl group or an ethyl group is particularly preferable. Moreover, when it has a substituent, 1-3 are preferable, and 1 or 2 is especially preferable.

In the formula [1], examples of the aryl group represented by Ar ¹ include a phenyl group, a naphthyl group, a fluorenyl group, an anthryl group, a phenanthryl group, and a pyrenyl group. Among them, a phenyl group is particularly preferable in terms of acid gas resistance and positive memory improvement.
In the formula [1], Ar ² and Ar ³ are each independently a hydrogen atom or an aryl group optionally having an alkyl group having 1 to 4 carbon atoms as a substituent. Examples of the substituent that the aryl group may have include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Among these, from the viewpoint of electrical characteristics and production cost, an alkyl group having 1 to 2 carbon atoms is more preferable, and a methyl group is particularly preferable. The number of substituents for one aryl group is preferably 1 to 2, particularly preferably 1. In view of improvement of acid resistance and positive memory, it is preferable not to have a substituent.

In the formula [1], Ar ² and Ar ³ may be the same or different and are a hydrogen atom or an aryl group. Examples of the aryl group include a phenyl group, a naphthyl group, a fluorenyl group, an anthryl group, a phenanthryl group, and a pyrenyl group. Among them, a phenyl group is preferable in terms of improving acid gas resistance and positive memory, and it is particularly preferable that one is a phenyl group and the other is a hydrogen atom. Ar ² and Ar ³ are simultaneously hydrogen atoms.

In said formula [1], R is a C1-C4 alkyl group. Examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, and the like. Among these, a methyl group is particularly preferable from the viewpoint of electrical characteristics and production cost.
The molecular weight of the formula [1] is usually 560 or less, preferably 460 or less. When this range is satisfied, the cleaning performance is improved when the actual image is evaluated, and it is easy to prevent noise and filming. This is presumably because the surface hardness of the photoreceptor is high by using a low molecular charge transport material. Therefore, in the general formula [1], Ar ^{1 to} Ar ³ or a substituent thereof, and further a substituent R is preferably adjusted in view of the molecular weight. On the other hand, the lower limit is preferably 420 or more from the viewpoint of electrical characteristics.

As typical examples of the stilbene compounds having the structure represented by the above formula [1], the following exemplified compounds CT-1 to CT-10 can be mentioned. However, the stilbene compounds related to the present invention are not limited to these.

≪Electrophotographic photoreceptor≫
The configuration of the electrophotographic photosensitive member of the present invention will be described below. The structure of the electrophotographic photosensitive member of the present invention is not particularly limited as long as the photosensitive layer containing the stilbene compound represented by the above formula [1] is provided on the conductive support. Among them, a multilayer photoreceptor in which a charge generation layer and a charge transport layer are laminated is preferable, and in particular, the charge transport layer of the multilayer photoreceptor contains a stilbene compound represented by the above formula [1]. It is preferable to do.

<Conductive support>
There are no particular restrictions on the conductive support, but for example, metal materials such as aluminum, aluminum alloys, stainless steel, copper and nickel, and conductive powders such as metal, carbon and tin oxide can be added to make the conductive material conductive. Mainly used are resin, glass, paper, or the like obtained by depositing or applying the applied resin material or a conductive material such as aluminum, nickel, ITO (indium tin oxide) on the surface. These may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and arbitrary ratios. As a form of the conductive support, a drum form, a sheet form, a belt form or the like is used. Furthermore, a conductive material having an appropriate resistance value may be used on a conductive support made of a metal material in order to control conductivity and surface properties and to cover defects.

Moreover, when using metal materials, such as an aluminum alloy, as an electroconductive support body, you may use, after giving an anodic oxide film. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method.
The surface of the conductive support may be smooth, or may be roughened by using a special cutting method or performing a polishing treatment. Further, it may be roughened by mixing particles having an appropriate particle size with the material constituting the conductive support. In order to reduce the cost, it is possible to use the drawing tube as it is without performing the cutting process.

<Underlayer>
An undercoat layer may be provided between the conductive support and the photosensitive layer described later for improving adhesion and blocking properties. As the undercoat layer, a resin or a resin in which particles such as a metal oxide are dispersed is used. The undercoat layer may be a single layer or a plurality of layers.

  Examples of metal oxide particles used for the undercoat layer include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, titanium Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium acid and barium titanate. One kind of these particles may be used alone, or a plurality of kinds of particles may be mixed and used. Among these metal oxide particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or silicon. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. Moreover, the thing of a several crystal state may be contained.

In addition, various particle sizes of metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is preferably 10 nm or more and 100 nm or less, and particularly 10 nm or more and 50 nm or less. preferable. This average primary particle size can be obtained from a TEM photograph or the like.
The undercoat layer is preferably formed in a form in which metal oxide particles are dispersed in a binder resin. The binder resin used for the undercoat layer is epoxy resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, polyimide resin, chloride resin. Cellulose esters such as vinylidene resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacryl resin, polyacrylamide resin, polyvinyl pyrrolidone resin, polyvinyl pyridine resin, water-soluble polyester resin, nitrocellulose Resin, cellulose ether resin, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, zirconium chelate compound, zirconium The organic zirconium compound alkoxide compounds, titanyl chelate compounds, organic titanyl compounds such as titanium alkoxide compounds include known binder resins such as a silane coupling agent. These may be used alone or in combination of two or more in any combination and ratio. Moreover, you may use with the hardening | curing form with the hardening | curing agent. Among these, alcohol-soluble copolymerized polyamides, modified polyamides, and the like are preferable because they exhibit good dispersibility and coatability.

The use ratio of the inorganic particles to the binder resin used in the undercoat layer can be arbitrarily selected. From the viewpoint of the stability of the dispersion and the coating property, the binder resin is usually 10% by mass or more, It is preferable to use in the range of 500 mass% or less.
The thickness of the undercoat layer is arbitrary as long as the effects of the present invention are not significantly impaired, but the viewpoint of improving the electrical characteristics, strong exposure characteristics, image characteristics, repeat characteristics, and coating properties during production of the electrophotographic photosensitive member. Therefore, it is usually 0.01 μm or more, preferably 0.1 μm or more, and usually 30 μm or less, preferably 20 μm or less. A known antioxidant or the like may be mixed in the undercoat layer. For the purpose of preventing image defects, pigment particles, resin particles and the like may be included.

<Photosensitive layer>
The photosensitive layer is formed on the above-mentioned conductive support (or on the undercoat layer when the above-described undercoat layer is provided). The photosensitive layer is a layer containing the stilbene compound represented by the general formula [1] described above, and includes a charge generation material and a charge transport material (a stilbene compound represented by the general formula [1]). And a single layer structure in which they are dispersed in a binder resin (hereinafter referred to as “single layer type photosensitive layer” as appropriate) and a charge generating material is dispersed in the binder resin. Functional separation of a layered structure composed of two or more layers including a charge generation layer and a charge transport layer (including a stilbene compound represented by the general formula [1]) dispersed in a binder resin Type (hereinafter referred to as “laminated photosensitive layer” as appropriate), but any form may be used.

In addition, as the laminated photosensitive layer, a charge-generating layer and a charge transport layer are laminated in this order from the conductive support side, and conversely, a charge transport layer and a charge generation layer are formed from the conductive support side. There are reverse laminated photosensitive layers provided in order, and any of them can be adopted, but a forward laminated photosensitive layer that can exhibit the most balanced photoconductivity is preferable.
<Laminated photosensitive layer>
[Charge generation layer]
The charge generation layer of the laminated photosensitive layer (function-separated type photosensitive layer) contains a charge generation material, and usually contains a binder resin and other components used as necessary. Such a charge generation layer is prepared, for example, by dissolving or dispersing a charge generation material and a binder resin in a solvent or dispersion medium to prepare a coating solution, and in the case of a sequentially laminated photosensitive layer, this is formed on a conductive support. (If an undercoat layer is provided, it can be obtained on the undercoat layer). In the case of a reverse laminated type photosensitive layer, it can be obtained by coating on a charge transport layer and drying.

  Examples of the charge generation material include inorganic photoconductive materials such as selenium and its alloys, cadmium sulfide, and organic photoconductive materials such as organic pigments. Organic photoconductive materials are preferred, and organic photoconductive materials are particularly preferable. Pigments are preferred. Examples of organic pigments include phthalocyanine pigments, azo pigments, dithioketopyrrolopyrrole pigments, squalene (squarylium) pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, and benzimidazole pigments. . Among these, phthalocyanine pigments or azo pigments are particularly preferable. When organic pigments are used as the charge generating substance, usually, fine particles of these organic pigments are used in the form of a dispersion layer bound with various binder resins.

When using a phthalocyanine pigment as a charge generation material, specifically, metal such as metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, aluminum, or oxides thereof, halides, Those having each crystal form of coordinated phthalocyanines such as hydroxides and alkoxides, and phthalocyanine dimers using oxygen atoms as bridging atoms are used. In particular, titanyl phthalocyanines (also known as oxytitanium) such as X-type, τ-type metal-free phthalocyanine, A-type (also known as β-type), B-type (also known as α-type), and D-type (also known as Y-type), which are highly sensitive crystal types Phthalocyanine), vanadyl phthalocyanine, chloroindium phthalocyanine, hydroxyindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and type I, type II, etc. The [mu] -oxo-aluminum phthalocyanine dimer is preferred.

  Among these phthalocyanines, A-type (also known as β-type), B-type (also known as α-type), and powder X-ray diffraction angle 2θ (± 0.2 °) are 27.1 ° or 27.3 °. D-type (Y-type) titanyl phthalocyanine, II-type chlorogallium phthalocyanine, V-type hydroxygallium phthalocyanine, hydroxygallium phthalocyanine having the strongest peak at 28.1 °, or 26. Hydroxygallium phthalocyanine having no peak at 2 °, a clear peak at 28.1 °, and a full width at half maximum W of 25.9 ° of 0.1 ° ≦ W ≦ 0.4 ° G-type μ-oxo-gallium phthalocyanine dimer and the like are particularly preferable.

  When a metal-free phthalocyanine compound or a metal-containing phthalocyanine compound is used as the charge generation material, a highly sensitive photoreceptor can be obtained with respect to a laser beam having a relatively long wavelength, for example, a laser beam having a wavelength around 780 nm. Further, when an azo pigment such as monoazo, diazo, or trisazo is used, white light, laser light having a wavelength around 660 nm, or laser light having a relatively short wavelength (for example, a wavelength in the range of 380 nm to 500 nm). It is possible to obtain a photoreceptor having sufficient sensitivity to the laser beam).

  The phthalocyanine compound may be a single compound or several mixed or mixed crystal states. As the mixed state in the phthalocyanine compound or crystal state here, those obtained by mixing the respective constituent elements later may be used, or the mixed state in the production / treatment process of the phthalocyanine compound such as synthesis, pigmentation, crystallization, etc. It may be the one that gave rise to. As such treatment, acid paste treatment, grinding treatment, solvent treatment and the like are known. In order to generate a mixed crystal state, as described in JP-A-10-48859, two types of crystals are mixed, mechanically ground and made amorphous, and then converted into a specific crystal state by solvent treatment. The method of doing is mentioned.

  On the other hand, when an azo pigment is used as a charge generation material, various known azo pigments can be used as long as they have sensitivity to a light source for light input. Trisazo pigments are preferably used. Examples of preferred azo pigments are shown below.

  When the organic pigments exemplified above are used as the charge generation material, one kind may be used alone, or two or more kinds of pigments may be mixed and used. In this case, it is preferable to use a combination of two or more kinds of charge generating materials having spectral sensitivity characteristics in different spectral regions of the visible region and the near red region, and it is more preferable to use a combination of an azo pigment and a phthalocyanine pigment.

The binder resin used for the charge generation layer constituting the multilayer photosensitive layer is not particularly limited. For example, polyvinyl butyral resin, polyvinyl formal resin, partially acetalized polyvinyl butyral resin in which part of butyral is modified with formal, acetal, or the like. Polyvinyl acetal resin, polyarylate resin, polycarbonate resin, polyester resin, modified ether polyester resin, phenoxy resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polystyrene resin, acrylic resin, methacrylic resin, etc. Polyacrylamide resin, polyamide resin, polyvinyl pyridine resin, cellulose resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, Vinyl chloride such as zein, vinyl chloride-vinyl acetate copolymer, hydroxy-modified vinyl chloride-vinyl acetate copolymer, carboxyl-modified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer -Insulating resin such as vinyl acetate copolymer, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, styrene-alkyd resin, silicon-alkyd resin, phenol-formaldehyde resin, and poly-N-vinylcarbazole , Organic photoconductive polymers such as polyvinyl anthracene and polyvinyl perylene. Any one of these binder resins may be used alone, or two or more thereof may be mixed and used in any combination.

Specifically, the charge generation layer is prepared by dispersing a charge generation material in a solution obtained by dissolving the above-described binder resin in an organic solvent to prepare a coating solution, which is then formed on a conductive support (when an undercoat layer is provided). Is formed by coating (on the undercoat layer).
The solvent used for preparing the coating solution is not particularly limited as long as it dissolves the binder resin. For example, saturated aliphatic solvents such as pentane, hexane, octane, and nonane, and aromatics such as toluene, xylene, and anisole. Group solvents, halogenated aromatic solvents such as chlorobenzene, dichlorobenzene, chloronaphthalene, amide solvents such as dimethylformamide, N-methyl-2-pyrrolidone, methanol, ethanol, isopropanol, n-butanol, benzyl alcohol, etc. Alcohol solvents, aliphatic polyhydric alcohols such as glycerin and polyethylene glycol, chain or cyclic ketone solvents such as acetone, cyclohexanone, methyl ethyl ketone, 4-methoxy-4-methyl-2-pentanone, methyl formate, ethyl acetate, Acetic acid n-bu Chains such as ester solvents such as benzene, halogenated hydrocarbon solvents such as methylene chloride, chloroform, 1,2-dichloroethane, diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve, etc. Or cyclic ether solvents, acetonitrile, dimethyl sulfoxide, sulfolane, aprotic polar solvents such as hexamethylphosphoric triamide, n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, triethylenediamine, triethylamine-containing nitrogen Compound, mineral oil such as ligroin, water and the like. Any one of these may be used alone, or two or more of these may be used in combination. In addition, when providing the above-mentioned undercoat layer, what does not melt | dissolve this undercoat layer is preferable.

  In the charge generation layer, the mixing ratio (mass ratio) of the binder resin and the charge generation material is usually 10 parts by mass or more, preferably 30 parts by mass or more, and usually 1000 parts by mass with respect to 100 parts by mass of the binder resin. The range is not more than part by mass, preferably not more than 500 parts by mass. The film thickness of the electrification generation layer is usually in the range of 0.1 μm or more, preferably 0.15 μm or more, and usually 10 μm or less, preferably 0.6 μm or less. If the ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to aggregation of the charge generation material. On the other hand, if the ratio of the charge generating substance is too low, the sensitivity as a photoreceptor may be reduced.

As a method for dispersing the charge generation material, a known dispersion method such as a ball mill dispersion method, an attritor dispersion method, or a sand mill dispersion method can be used. At this time, it is effective to refine the particles to a particle size in the range of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.
[Charge transport layer]
The charge transport layer of the multilayer photoreceptor contains a charge transport material and usually contains a binder resin and other components used as necessary. Specifically, such a charge transport layer is prepared by dissolving or dispersing a charge transport material or the like and a binder resin in a solvent to prepare a coating solution. In addition, in the case of a reverse lamination type photosensitive layer, it can be obtained by coating and drying on a conductive support (on the undercoat layer when an undercoat layer is provided).

As the charge transport material, it is preferable to use a stilbene compound having a structure represented by the general formula [1] of the present invention. The stilbene compounds of the present invention may be used singly or in combination of two or more in any ratio.
In addition to the stilbene compound having a structure represented by the general formula [1] of the present invention, other known charge transport materials may be used in combination. When other charge transport materials are used in combination, the type is not particularly limited, but for example, carbazole derivatives, hydrazone compounds, aromatic amine derivatives, enamine derivatives, butadiene derivatives, and those obtained by bonding a plurality of these derivatives are preferable. More specifically, it is described in JP-A-2-230255, JP-A-63-225660, JP-A-58-198043, JP-B-58-32372, and JP-B-7-21646. Compounds are preferably used. Any one of these charge transport materials may be used alone, or a plurality of types may be used in any combination. When the stilbene compound of the present invention is used in combination with another known charge transport material, the content ratio (% by mass) of the charge transport material to be used in the total amount of the charge transport material is not particularly limited. It is within the range of 1% or more and 30% or less, and preferably 1% or more and 20% or less. In order to more effectively exert the role of the stilbene compound having the structure represented by the general formula [1] of the present invention, the content ratio of other known charge transport materials is in the range of 3% to 10%. It is more preferable that

  The binder resin is used for securing the film strength. Examples of the binder resin for the charge transport layer include polymers and copolymers of vinyl compounds such as butadiene resin, styrene resin, vinyl acetate resin, vinyl chloride resin, acrylic ester resin, methacrylic ester resin, vinyl alcohol resin, and ethyl vinyl ether. Polymer, polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal, polycarbonate resin, polyester resin, polyarylate resin, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicon resin, silicon-alkyd resin, poly-N -Vinyl carbazole resin etc. are mentioned. Among these, polycarbonate resin or polyarylate resin is preferable. These binder resins can also be used after being crosslinked by heat, light or the like using an appropriate curing agent. Any one of these binder resins may be used alone, or two or more thereof may be used in any combination.

  As for the ratio of the binder resin to the charge transport material, the charge transport material is usually used at a ratio of 20 parts by mass or more with respect to 100 parts by mass of the binder resin. Among these, 30 parts by mass or more is preferable from the viewpoint of residual potential reduction, and 40 parts by mass or more is more preferable from the viewpoint of stability and charge mobility when repeatedly used. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, the charge transport material is usually used at a ratio of 150 parts by mass or less. Among these, 110 parts by mass or less is preferable from the viewpoint of compatibility between the charge transport material and the binder resin, 90 parts by mass or less is more preferable from the viewpoint of printing durability, and 80 parts by mass or less is most preferable from the viewpoint of scratch resistance.

The thickness of the charge transport layer is not particularly limited, but is usually 5 μm or more, preferably 10 μm or more, on the other hand, usually 50 μm or less, preferably 45 μm or less, from the viewpoint of long life, image stability, and high resolution. Is in the range of 30 μm or less.
<Single layer type photosensitive layer>
In addition to the charge generation material and the charge transport material, the single-layer type photosensitive layer is formed using a binder resin in order to ensure film strength, as with the charge transport layer of the multilayer photoreceptor. Specifically, a charge generation material, a charge transport material, and various binder resins are dissolved or dispersed in a solvent to prepare a coating solution, and on a conductive support (or an undercoat layer when an undercoat layer is provided). It can be obtained by coating and drying.

The types of the charge transport material and the binder resin and the usage ratios thereof are the same as those described for the charge transport layer of the multilayer photoreceptor. A charge generating material is further dispersed in a charge transport medium comprising these charge transport material and binder resin.
As the charge generation material, the same materials as those described for the charge generation layer of the multilayer photoreceptor can be used. However, in the case of a photosensitive layer of a single layer type photoreceptor, it is necessary to sufficiently reduce the particle size of the charge generating material. Specifically, the range is usually 1 μm or less, preferably 0.5 μm or less.

If the amount of the charge generating material dispersed in the single-layer type photosensitive layer is too small, sufficient sensitivity cannot be obtained, but if it is too large, there are adverse effects such as a decrease in chargeability and a decrease in sensitivity. The total amount of the layer-type photosensitive layer is usually 0.5% by mass or more, preferably 1% by mass or more, and usually 50% by mass or less, preferably 20% by mass or less.
In addition, the usage ratio of the binder resin and the charge generation material in the single-layer type photosensitive layer is such that the charge generation material is usually 0.1 parts by weight or more, preferably 1 part by weight or more, based on 100 parts by weight of the binder resin. It is 30 mass parts or less, Preferably it is set as the range of 10 mass parts or less.
The film thickness of the single-layer type photosensitive layer is usually 5 μm or more, preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less.

<Other functional layers and additives>
For the purpose of improving film-forming properties, flexibility, coating properties, stain resistance, gas resistance, light resistance, etc., in both the photosensitive layer and each layer constituting it, both in the multilayer type photosensitive member and the single layer type photosensitive member. Additives such as well-known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, and visible light shielding agents may be included.

Further, in both the laminated type photoreceptor and the single layer type photoreceptor, the photosensitive layer formed by the above procedure may be the uppermost layer, that is, the surface layer, but another layer may be provided on the photosensitive layer and used as the surface layer. Good.
For example, a protective layer may be provided for the purpose of preventing the photosensitive layer from being worn out or preventing or reducing the deterioration of the photosensitive layer due to discharge products generated from a charger or the like.
The protective layer is formed by containing a conductive material in a suitable binder resin, or a copolymer using a compound having charge transporting ability such as a triphenylamine skeleton described in JP-A-9-190004. Can be formed.

Examples of the conductive material used for the protective layer include aromatic amino compounds such as TPD (N, N′-diphenyl-N, N′-bis- (m-tolyl) benzidine), antimony oxide, indium oxide, tin oxide, and oxide. Metal oxides such as titanium, tin oxide-antimony oxide, aluminum oxide, and zinc oxide can be used, but are not limited thereto.
As the binder resin used for the protective layer, known resins such as polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, and siloxane resin can be used. Also, a skeleton having a charge transporting ability such as a triphenylamine skeleton as described in JP-A-9-190004 and a copolymer of the above resin can be used.

The electrical resistance of the protective layer is usually in the range of 10 ⁹ Ω · cm to 10 ¹⁴ Ω · cm. When the electric resistance is higher than the range, the residual potential is increased, resulting in an image with much fogging. On the other hand, when the electric resistance is lower than the range, the image is blurred and the resolution is reduced. Further, the protective layer must be configured so as not to substantially prevent transmission of light irradiated during image exposure.
Further, for the purpose of reducing the frictional resistance and wear on the surface of the photoconductor, and increasing the transfer efficiency of the toner from the photoconductor to the transfer belt and paper, etc., the surface layer is made of fluorine resin, silicon resin, polyethylene resin, or the like. You may contain the particle | grains which consist of these resin, and the particle | grains of an inorganic compound. Alternatively, a layer containing these resins and particles may be newly formed as a surface layer.

<Method for forming each layer>
Each layer constituting the above-described photoreceptor is formed by dip coating, spray coating, nozzle coating, bar coating, roll coating, blade coating on a conductive support obtained by dissolving or dispersing a substance to be contained in a solvent. It is formed by repeating a coating / drying step sequentially for each layer by a known method such as coating.

  There are no particular restrictions on the solvent or dispersion medium used for the preparation of the coating solution, but specific examples include alcohols such as methanol, ethanol, propanol and 2-methoxyethanol, tetrahydrofuran, 1,4-dioxane, dimethoxyethane and the like. Ethers, esters such as methyl formate and ethyl acetate, acetone, methyl ethyl ketone, cyclohexanone, ketones such as 4-methoxy-4-methyl-2-pentanone, aromatic hydrocarbons such as benzene, toluene, xylene, dichloromethane, Chlorinated hydrocarbons such as chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, trichloroethylene, n-butylamine, isopropanolamine, Diethyl Min, triethanolamine, ethylenediamine, nitrogen-containing compounds such as triethylenediamine, acetonitrile, N- methylpyrrolidone, N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like. Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and kinds.

The amount of the solvent or the dispersion medium used is not particularly limited, but considering the purpose of each layer and the properties of the selected solvent / dispersion medium, it is appropriately determined so that the physical properties such as the solid content concentration and viscosity of the coating liquid are within a desired range. It is preferable to adjust.
For example, in the case of a charge transport layer of a single layer type photoreceptor or a function separation type photoreceptor, the solid content concentration of the coating solution is usually 5% by mass or more, preferably 10% by mass or more, and usually 40% by mass or less. The range is preferably 35% by mass or less. In addition, the viscosity of the coating solution is usually 10 mPa · s or higher, preferably 50 mPa · s or higher, and usually 500 mPa · s or lower, preferably 400 mPa · s or lower, at the temperature during use.

  In the case of a charge generation layer of a multilayer photoreceptor, the solid content concentration of the coating solution is usually 0.1% by mass or more, preferably 1% by mass or more, and usually 15% by mass or less, preferably 10% by mass. % Or less. In addition, the viscosity of the coating solution is usually 0.01 mPa · s or higher, preferably 0.1 mPa · s or higher, and usually 20 mPa · s or lower, preferably 10 mPa · s or lower, at the temperature during use.

Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a wire bar coating method, a blade coating method, a roller coating method, an air knife coating method, and a curtain coating method. Other known coating methods can also be used.
The coating solution is preferably dried by touching at room temperature, followed by heating or drying in a temperature range of usually 30 ° C. or more and 200 ° C. or less for 1 minute to 2 hours, while still or blowing. Further, the heating temperature may be constant, or heating may be performed while changing the temperature during drying.

≪Image forming device≫
Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention (an image forming apparatus of the present invention) will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.

As shown in FIG. 1, the image forming apparatus includes an electrophotographic photosensitive member 1, a charging device 2, an exposure device 3, and a developing device 4, and further, a transfer device 5, a cleaning device 6, and a fixing device as necessary. A device 7 is provided.
The electrophotographic photoreceptor 1 is not particularly limited as long as it is the above-described electrophotographic photoreceptor of the present invention, but in FIG. 1, as an example, a drum in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. The photoconductor is shown. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged along the outer peripheral surface of the electrophotographic photoreceptor 1.

  The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. As the charging device, a corona charging device such as a corotron or a scorotron, a direct charging device (contact type charging device) for charging a direct charging member to which a voltage is applied by contacting the photosensitive member surface, and the like are often used. Examples of the direct charging device include a charging roller and a charging brush. In FIG. 1, a roller-type charging device (charging roller) is shown as an example of the charging device 2. As the direct charging means, either charging with air discharge or injection charging without air discharge is possible. Moreover, as a voltage applied at the time of charging, it is possible to use only a direct current voltage or to superimpose an alternating current on a direct current.

  The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, if exposure is performed with monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength of 600 nm to 700 nm, slightly shorter wavelength, monochromatic light with a wavelength of 380 nm to 500 nm, or the like. Good.

  The type of the developing device 4 is not particularly limited, and an arbitrary device such as a dry development method such as cascade development, one-component insulating toner development, one-component conductive toner development, or two-component magnetic brush development, or a wet development method is used. be able to. In FIG. 1, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. This replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicon resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.
The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

  The regulating member 45 is formed of a resin blade such as silicon resin or urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such a metal blade with a resin. The regulating member 45 contacts the developing roller 44 and is pressed against the developing roller 44 side with a predetermined force by a spring or the like (a general blade linear pressure is 5 to 500 g / cm). If necessary, the regulating member 45 may be provided with a function of imparting charging to the toner T by frictional charging with the toner T.

The agitator 42 is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.
The type of the toner T is arbitrary, and in addition to the powdery toner, a polymerized toner using a suspension polymerization method, an emulsion polymerization method, or the like can be used. In particular, when a polymerized toner is used, a toner having a small particle diameter of about 4 to 8 μm is preferable, and the toner particles are used in various shapes ranging from a nearly spherical shape to a shape outside the spherical shape on the potato. be able to. The polymerized toner is excellent in charging uniformity and transferability and is suitably used for high image quality.

  The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like disposed so as to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium) P. Is.

  There is no restriction | limiting in particular about the cleaning apparatus 6, Arbitrary cleaning apparatuses, such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, can be used. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner. However, when there is little or almost no toner remaining on the surface of the photoreceptor, the cleaning device 6 may be omitted.

  The fixing device 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 1 shows an example in which a heating device 73 is provided inside the upper fixing member 71. The upper and lower fixing members 71 and 72 are known heat fixings such as a fixing roll in which a metal base tube such as stainless steel or aluminum is coated with silicon rubber, a fixing roll in which Teflon (registered trademark) resin is coated, or a fixing sheet. A member can be used. Further, each of the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P.
The type of the fixing device is not particularly limited, and a fixing device of an arbitrary method such as heat roller fixing, flash fixing, oven fixing, pressure fixing, or the like can be provided.

In the electrophotographic apparatus configured as described above, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.
Subsequently, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. The developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1.

The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.
When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.

After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.
In addition to the above-described configuration, the image forming apparatus may be configured to perform, for example, a static elimination process. The neutralization step is a step of neutralizing the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the neutralizing device. In addition, the light used in the static elimination process is often light having an exposure energy that is at least three times that of the exposure light.

The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.
The electrophotographic photosensitive member 1 is combined with one or more of the charging device 2, the exposure device 3, the developing device 4, the transfer device 5, the cleaning device 6, and the fixing device 7 to form an integrated cartridge ( The electrophotographic photosensitive member cartridge may be configured to be detachable from the main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. In this case, for example, when the electrophotographic photosensitive member 1 and other members are deteriorated, the electrophotographic photosensitive member cartridge is removed from the main body of the image forming apparatus, and another new electrophotographic photosensitive member cartridge is mounted on the main body of the image forming apparatus. This facilitates maintenance and management of the image forming apparatus.

Hereinafter, the present invention will be described in more detail with reference to production examples, examples and comparative examples. In addition, the following examples are shown in order to explain the present invention in detail, and the present invention is not limited to the following examples unless it is contrary to the gist thereof.
<Production of stilbene compound having a structure represented by the general formula [1]>
(Production Example 1: Production of Exemplified Compound CT-1)

In a nitrogen atmosphere, 6.13 g (20 mmol) of compound (A), 5.55 g (20 mmol) of compound (B), 50 ml of xylene and 2.31 g (24 mmol) of sodium tert-butoxide were charged into the reactor and stirred. Then, 1 ml of a xylene solution containing 0.7 mg of palladium acetate and 2.35 mg of tricyclohexylphosphine was added. Thereafter, the reactor was heated to 140 ^° C. and kept at that temperature for 2 to 3 hours for reaction. After completion of the reaction, the mixture was cooled, and 50 ml of toluene and 50 ml of water were added to separate the layers. The organic layer was washed 3 times with 50 ml / water, dried by contact with magnesium sulfate, and concentrated under reduced pressure. The obtained crude product was dissolved in a mixed solution of toluene / hexane (v / v = 1: 1) by heat, and then passed through column chromatography (silica gel 250 g, developing solvent: toluene / hexane = 1/1). Exemplified compound CT-1 was obtained as light yellow crystals (5.64 g, yield 62%). An IR spectrum (JASCO FT / IR-350 spectrophotometer) of this compound is shown in FIG.

  (Production Example 2: Production of Exemplified Compound CT-5)

Under a nitrogen atmosphere, 6.13 g (20 mmol) of compound (A), 6.14 g (22 mmol) of compound (C), 50 ml of xylene and 2.31 g (24 mmol) of sodium tert-butoxide were charged into the reactor and stirred. Then, 1 ml of a xylene solution containing 0.7 mg of palladium acetate and 2.35 mg of tricyclohexylphosphine was added. Thereafter, the reactor was heated to 140 ^° C. and kept at that temperature for 2 to 3 hours for reaction. After completion of the reaction, the mixture was cooled, and 50 ml of toluene and 50 ml of water were added to separate the layers. The organic layer was washed 3 times with 50 ml / water, dried by contact with magnesium sulfate, and concentrated under reduced pressure. The obtained crude product was dissolved in a mixed solution of toluene / hexane (v / v = 1: 1) by heat, and then passed through column chromatography (silica gel 250 g, developing solvent: toluene / hexane = 1/1). Exemplified compound CT-5 was obtained as pale yellow crystals (7.13 g, yield 78%). The IR spectrum (JASCO FT / IR-350 spectrophotometer) of this compound is shown in FIG.
(Production Example 3: Production of Exemplified Compound CT-9)

In a nitrogen atmosphere, 5.99 g (16.5 mmol) of compound (D), 3.95 g (15 mmol) of compound (E), 50 ml of xylene and 1.73 g (18 mmol) of sodium tert-butoxide were charged into the reactor and stirred. Then, 1 ml of a xylene solution containing 0.7 mg of palladium acetate and 2.35 mg of tricyclohexylphosphine was added. Thereafter, the reactor was heated to 140 ^° C. and kept at that temperature for 2 to 3 hours for reaction. After completion of the reaction, the mixture was cooled, and 50 ml of toluene and 50 ml of water were added to separate the layers. The organic layer was washed 3 times with 50 ml / water, dried by contact with magnesium sulfate, and concentrated under reduced pressure. The obtained crude product was dissolved in a mixed solution of toluene / hexane (v / v = 1: 1) by heat, and then passed through column chromatography (silica gel 250 g, developing solvent: toluene / hexane = 1/1). Exemplified compound CT-9 was obtained as light yellow crystals (4.26 g, yield 52%). The IR spectrum (JASCO FT / IR-350 spectrophotometer) of this compound is shown in FIG.

<Production of electrophotographic photoreceptor>
(Example 1: Electrophotographic photoreceptor R1)
Using a conductive support with an aluminum vapor deposition layer (thickness 70 nm) formed on the surface of a biaxially stretched polyethylene terephthalate resin film (thickness 75 μm), on the aluminum vapor deposition layer of the conductive support, the following undercoat layer Dispersion liquid with a bar coater, film thickness after drying is 1.25μm
The undercoat layer was formed by coating and drying.

The undercoat layer dispersion was prepared by the following method. That is, rutile type titanium oxide having an average primary particle diameter of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by mass of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide Disperse the surface-treated titanium oxide obtained by mixing in a fluid mixing kneader ("SMG300" manufactured by Kawata Co., Ltd.) and mixing at high speed at a rotational peripheral speed of 34.5 m / sec using a methanol / 1-propanol ball mill. Thus, a dispersion slurry of hydrophobized titanium oxide was obtained. The dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (F)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula ( G)] / hexamethylenediamine [compound represented by the following formula (H)] / decamethylene dicarboxylic acid [compound represented by the following formula (I)] / octadecamethylene dicarboxylic acid [
The compound molar ratio of the compound represented by the following formula (J)] is a polyamide pellet obtained by stirring and mixing with a copolyamide pellet having a composition molar ratio of 60% / 15% / 5% / 15% / 5%. Is dissolved, and then ultrasonic dispersion treatment is performed, so that the mass ratio of methanol / 1-propanol / toluene is 71/2 and the hydrophobically treated titanium oxide / copolymer polyamide is contained at a mass ratio of 3/1. An undercoat layer dispersion having a solid content concentration of 18.0% was obtained.

  Next, 10 parts of oxytitanium phthalocyanine having a powder X-ray diffraction spectrum shown in FIG. In addition to 150 parts of 2-dimethoxyethane, pulverization and dispersion treatment was performed with a sand grind mill to prepare a pigment dispersion. 160 parts by mass of the pigment dispersion thus obtained, 100 parts by mass of a 5% 1,2-dimethoxyethane solution of polyvinyl butyral (trade name # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.), and an appropriate amount of 1,2-dimethoxy Ethane was mixed to finally produce a dispersion having a solid concentration of 4.0%.

The dispersion was applied on the undercoat layer with a wire bar so that the film thickness after drying was 0.4 μm, and then dried to form a charge generation layer. Next, 50 parts by mass of the crystal of the exemplified compound CT-1 obtained in Production Example 1, 100 parts by mass of the following polycarbonate resin (R), 0.05 part by mass of silicone oil as a leveling agent, a mixed solvent of tetrahydrofuran and toluene (tetrahydrofuran 80 wt%, toluene 20 wt%) was mixed with 640 parts to prepare a charge transport layer forming coating solution. This solution is applied onto the above-described charge generation layer using an applicator so that the film thickness after drying is 25 μm, and dried at 125 ° C. for 20 minutes to form a charge transport layer, whereby the photosensitive sheet R1 is obtained. Produced. The viscosity average molecular weight of the polycarbonate resin (R) was 30,000.

The measuring method of the viscosity average molecular weight of the used binder resin is as follows. Dissolve the resin in dichloromethane to prepare a solution with a concentration C of 6.00 g / L. The flow time t of the sample solution is measured in a constant temperature water bath set to 20.0 ° C. using an Ubbelohde capillary viscometer with a flow time t ₀ of the solvent (dichloromethane) of 136.16 seconds. The viscosity average molecular weight Mv is calculated according to the following formula.

a = 0.438 × η _sp +1 η _sp = t / t ₀ −1
b = 100 × η _sp / C C = 6.00 (g / L)
η = b / a
Mv = 3207 × η ^1.205
(Examples 2 to 3: electrophotographic photoreceptors R2 to R3)
Electrophotographic photoreceptors R2 to R3 as Examples 2 to 3 were obtained in the same manner as Example 1, except that CT-5 or CT-9 was used as the charge transport material instead of the exemplified compound CT-1. It was.

(Comparative Example 1: Electrophotographic photoreceptor P1)
An electrophotographic photoreceptor P1 as a comparative example was obtained in the same manner as in Example 1 except that the charge transport material CT-11 exemplified in Patent Document 1 was used instead of the exemplified compound CT-1.

(Comparative Example 2: Electrophotographic photoreceptor P2)
An electrophotographic photoreceptor P2 as a comparative example was obtained in the same manner as in Example 1 except that the known compound CT-12 was used instead of the exemplified compound CT-1.

(Comparative Example 3: Electrophotographic photoreceptor P3)
An electrophotographic photoreceptor P3 as a comparative example was obtained in the same manner as in Example 1 except that the known compound CT-13 was used instead of the exemplified compound CT-1.

(Comparative Example 4: Electrophotographic photoreceptor P4)
An electrophotographic photoreceptor P4 as a comparative example was obtained in the same manner as in Example 1 except that the known compound CT-14 was used instead of the exemplified compound CT-1.

(Example 4: Electrophotographic photoreceptor Q1)
100 parts by mass of polyarylate resin (Q) having the following repeating structure (viscosity average molecular weight 43,000), 80 parts by mass of crystals of CT-1 obtained in Production Example 1 as a charge transport material, and the following formula as an antioxidant 8 parts by mass of the represented compound (AOX1) and 0.05 parts by mass of silicone oil as a leveling agent are dissolved in 640 parts by mass of a mixed solvent of THF / toluene (8/2 (mass ratio)) to form a coating solution for forming a charge transport layer. A photoreceptor sheet Q1 was produced by the same production method as in Example 1.

(Examples 5 to 6: electrophotographic photoreceptors Q2 to Q3)
Electrophotographic photoreceptors Q2 to Q3 as Examples 5 to 6 were obtained in the same manner as Example 4 except that CT-5 and CT-9 were used as charge transport materials in place of the exemplified compound CT-1. It was.
(Comparative Example 5: electrophotographic photoreceptor P5)
An electrophotographic photoreceptor P5 as Comparative Example 5 was obtained in the same manner as Example 4 except that the charge transport material CT-11 used in Comparative Example 1 was used instead of the exemplified compound CT-1.

(Comparative Example 6: electrophotographic photoreceptor P6)
An electrophotographic photoreceptor P6 as Comparative Example 6 was obtained in the same manner as Example 4 except that the charge transport material CT-12 used in Comparative Example 2 was used instead of the exemplified compound CT-1.
(Comparative Example 7: electrophotographic photoreceptor P7)
An electrophotographic photoreceptor P7 as Comparative Example 7 was obtained in the same manner as in Example 4 except that the charge transport material CT-13 used in Comparative Example 3 was used instead of the exemplified compound CT-1.

(Comparative Example 8: electrophotographic photosensitive member P8)
An electrophotographic photoreceptor P8 as Comparative Example 8 was obtained in the same manner as Example 4 except that the charge transport material CT-14 used in Comparative Example 4 was used instead of the exemplified compound CT-1.
[Characteristic evaluation]
The following electrical property tests were conducted on the produced electrophotographic photoreceptors R1 to R3, Q1 to Q3, and P1 to P8.

<Electrical characteristics test>
An electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404 to 405) is used, and the photoreceptor sheet has an outer diameter of 80 mm. After the aluminum drum and the aluminum substrate of the photosensitive sheet are connected to each other, the drum is rotated at a constant rotational speed of 60 rpm to charge, expose, measure potential, and remove static electricity. An electrical property evaluation test by cycle was performed. At that time, when the initial surface potential of the photosensitive member is charged to −700 V (the same applies below minus) and the halogen lamp light is converted to 780 nm monochromatic light with an interference filter and exposed at 1.0 μJ / cm ^2. After exposure, the surface potential after exposure (hereinafter sometimes referred to as Vl) was measured. In measuring Vl, the time required from the exposure to the potential measurement was set to 100 ms, which was a fast response condition. The photoreceptor surface potential is -700 V to -3.
The half exposure energy E _1/2 (μJ / cm ² ) required to reach 50 V was determined. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%.

  Tables 1 and 2 show the electrical property evaluation results of the electrophotographic photoreceptors R1 to R3, P1 to P4, Q1 to Q3, and P5 to P8, respectively, for each binder resin.

As shown in Tables 1 and 2, the stilbene compounds CT-1, CT-5 or CT-9 of the present invention have good compatibility regardless of the type of binder resin as the charge transport material, and all show good electrical characteristics. (Examples 1 to 6).
In contrast, the charge transport materials CT-12, CT-13, and CT-14, which are known stilbene compounds, are clearly inferior to the charge transport material of the present invention in terms of electrical characteristics (Comparative Example 2). ~ 4, and 6-8).
On the other hand, the analog charge transport material CT-11 of the present invention described in Patent Document 1 is found to be as good as the charge transport material of the present invention in terms of electrical characteristics (Comparative Example 1, Five).

<Evaluation of ozone resistance>
(Examples 7 to 9, Comparative Example 9)
The method of the ozone exposure test is described below. Using EPA8200 manufactured by Kawaguchi Denki Co., Ltd., Examples 4-6 above
The photosensitive sheet Q1 to Q3 (Examples 7 to 9) used in Example 1 and the photosensitive sheet P5 (Comparative Example 9) used in Comparative Example 5 were charged by applying a current of 25 μA to the corotron charger, and the charging was performed. The value was V1. After that, these photoconductors were exposed to ozone at a concentration of 150 ppm for 5 hours a day for 2 days (total exposure amount 750 ppm · hour). After exposure, the charge value was similarly measured, and this value was designated as V2. The charge retention before and after ozone exposure is calculated as (V2 / V1) * 100 (%) and shown in [Table 3].

Similarly to the electrical property evaluation method described above, after 10 seconds of exposure, residual potentials before and after exposure to ozone (respectively Vr1 and Vr2) were measured, and the difference ΔVr (Vr2−Vr1) was obtained. These results are shown in [Table 3].

  As can be seen from Table 3, the photoconductor using the stilbene-based charge transport materials CT-1, CT-5 and CT-9 of the present invention is the analog charge transport material CT of the present invention described in Patent Document 1. The photoretention rate after exposure to ozone is higher than that of photoconductors using -11, and the residual potential difference before and after exposure to ozone after 10 seconds of exposure is small. Therefore, the electrophotographic photoreceptor using the stilbene-based charge transport material of the present invention has better acid resistance and better electrical stability than the photoreceptor using a known analog charge transport material. It was confirmed.

<Image formation test and photoreceptor stability / durability test>
(Examples 10 to 12)
The coating solution for the charge generation layer and the charge transport layer prepared in the same manner as the electrophotographic photoreceptors Q1 to Q3 is immersed on an aluminum tube having a diameter of 3 cm and a length of 25.4 cm that has been anodized and sealed. The electrophotographic photosensitive drums S1 to S3 having a charge generation layer of 0.3 μm and a charge transport layer of 20 μm were prepared as Examples 10 to 12, respectively, by coating and drying sequentially by a coating method. These electrophotographic photosensitive drums were mounted on a laser printer, Laser Jet 4 (LJ4) manufactured by Hewlett-Packard Company, and an image test was performed. After the initial image is printed, 10,000 sheets are continuously printed, and the presence or absence of image deterioration such as positive-type memory, halftone part white spots, or density reduction is visually observed, and the results are shown in [Table 4]. Show.

(Comparative Examples 10-13)
In the procedure of Example 10, the same procedure was used except that the charge transport layer coating solution prepared in the same manner as the electrophotographic photoreceptors P5 to P8 was used. As Comparative Examples 10 to 13, the electrophotographic photoreceptor drum P10 was used.
-P13 was prepared and an image test was performed. The results are shown in [Table 4].

(*) The following symbols indicate the appearance of image defects observed when image evaluation is performed by the method specified above.
A: Good and no defects are visible.
○: Almost no defects are visible.
Δ: The defects are slightly visible.
X: Defects are clearly visible.

  [Table 4] As can be seen, electrophotography using charge transport materials CT-11, CT-12, CT-13 and CT-14 having a stilbene structure but not the structure of formula [I] Some photoreceptors showed image defects even in the initial stage (Comparative Examples 11 to 12), and all of them were observed to have image defects (Comparative Examples 10 to 13). In contrast, the electrophotographic photosensitive member using the stilbene-based charge transport material represented by the formula [I] according to the present invention has been confirmed to have very good repetitive characteristics with almost no problems even after repeated use. (Examples 10 to 12).

  The present invention can be carried out in any field that requires an electrophotographic photosensitive member, and is suitable for use in, for example, a copying machine, a printer, a printing machine, and the like.

1 Photoconductor (Electrophotographic photoconductor)
2 Charging device (charging roller; charging unit)
3 Exposure equipment (exposure section)
4 Development device (development unit)
DESCRIPTION OF SYMBOLS 5 Transfer apparatus 6 Cleaning apparatus 7 Fixing apparatus 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 45 Control member 71 Upper fixing member (fixing roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper (paper, medium)

Claims (3)

An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer contains at least one stilbene compound having a structure represented by the following general formula [1]. Electrophotographic photoreceptor.

(In the formula [1], Ar ¹ represents an aryl group which may have an organic group having 1 to 4 carbon atoms as a substituent, R represents an alkyl group having 1 to 4 carbon atoms, Ar ² and Ar ³ each independently represents a hydrogen atom or an aryl group optionally having an alkyl group having 1 to 4 carbon atoms as a substituent, provided that Ar ² and Ar ³ are simultaneously a hydrogen atom. except)   The electrophotographic photosensitive member according to claim 1, charging means for charging the electrophotographic photosensitive member, image exposure means for forming an electrostatic latent image on the charged electrophotographic photosensitive member by image exposure, and the electrostatic latent image An electrophotographic apparatus comprising at least one means selected from a developing means for developing an image with toner, a transferring means for transferring the toner to a transfer member, and a cleaning means for collecting the toner adhering to the electrophotographic photosensitive member. cartridge. 2. The electrophotographic photosensitive member according to claim 1, charging means for charging the electrophotographic photosensitive member, exposure means for forming an electrostatic latent image by exposing the charged electrophotographic photosensitive member, and the electrostatic latent image. An image forming apparatus comprising: a developing unit that develops toner with toner; a transfer unit that transfers the toner to a transfer target; and a fixing unit that fixes the toner transferred to the transfer target.

Images