JP5482399B2 - Electrophotographic photosensitive member, electrophotographic photosensitive member cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member, an electrophotographic cartridge, 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").
The photosensitive layer of the photoreceptor is usually composed of a binder resin and a photoconductive substance, and polycarbonate is often used as the binder resin in terms of electrical characteristics and mechanical durability. The polycarbonate resin has a repeating structure derived from an aromatic polyhydric alcohol in its repeating structure, and in particular, a polycarbonate resin having a repeating structure derived from 2,2-bis (4-hydroxyphenyl) propane Is often used.

  Furthermore, it is a common recognition in the industry that in recent years, with the high performance and cost reduction of electrophotographic equipment, it is essential to increase the sensitivity of the photoreceptor 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.

As a conventional technique, a low molecular weight triarylamine-stilbene conjugated compound can be used as a charge transport material. For example, triarylamine described in Patent Document 1
It has been proposed that a stilbene conjugated compound (hereinafter also simply referred to as “stilbene compound”) can be used as a charge transport material. In addition, 2,2-bis (4-hydroxyphenyl)
A polycarbonate resin obtained by polymerizing a propane phenyl group with a methyl group or copolymerized with other bisphenol components is described in the same document as being preferably used as a binder resin for a photosensitive layer. .

Japanese Unexamined Patent Publication No. 4-039667

However, since the repeating structure derived from 2,2-bis (4-hydroxyphenyl) propane has high crystallinity, the polycarbonate resin containing only it in the main chain has poor solution stability, and is a solution dissolved in a solvent. When trying to use, a uniform solution can be obtained in the initial stage immediately after dissolution, but there is a problem that crystallization gradually proceeds and the gel content tends to increase. It has also been clarified that a photoreceptor using this polycarbonate resin is prone to cleaning failure when used repeatedly.

Further, the charge transport material described in Patent Document 1 has various problems. For example, the compound Q having the following structure is poorly compatible with the binder resin, causing a problem of crystal precipitation when used in a high number of parts.

In addition, Compound Y having the following structure has relatively good initial electrical characteristics when used in combination with a polycarbonate resin, but it tends to cause streaks and white spots in halftone portions when repeatedly used. was there.

  The present invention has been made in view of the present situation, and an object of the present invention is to use an electrophotographic photosensitive member that does not cause image defects such as poor cleaning, streaks, and white spots in a halftone portion, and the photosensitive member. An object is to provide an electrophotographic cartridge and an image forming apparatus.

The present inventor has found that image defects such as poor cleaning, streaks, and white spots in halftone portions do not occur when a specific stilbene compound and a polycarbonate resin having a specific structure are used in combination in an electrophotographic photosensitive member. The present 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 includes a polycarbonate resin having a repeating structure represented by the following formula [1]; An electrophotographic photoreceptor comprising a stilbene compound represented by the following formula [2] (see claim 1).

(In Formula [1], R ^{10 to} R ¹⁷ may be the same or different and each represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen group. R ¹⁸ and R ¹⁹ are each independently selected. And represents a hydrogen atom, an alkyl group, or an aryl group, provided that R ^{10 to} R ¹⁷ must not be hydrogen atoms at the same time.)

(In the formula [2], Ar ⁴ and Ar ⁵ represent a phenyl group having at least one alkyl group having 1 to 4 carbon atoms, and R ⁹ represents an alkyl group having 2 to 4 carbon atoms. A, B May be the same or different and represents an organic group having 1 to 4 carbon atoms, and m and n each represents an integer of 0 to 4).
A second aspect of the present invention is an electrophotographic photosensitive member according to the first aspect, a charging means for charging the electrophotographic photosensitive member, and an electrostatic latent image obtained by performing image exposure on the charged electrophotographic photosensitive member. An image exposing means for forming the electrostatic latent image, a developing means for developing the electrostatic latent image with toner, a transferring means for transferring the toner from the electrophotographic photosensitive member to the transfer target, and the residual on the electrophotographic photosensitive member after transfer The electrophotographic cartridge includes at least one of cleaning means for removing the toner to be removed (claim 2).

According to a third aspect of the present invention, there is provided an electrophotographic photosensitive member according to the first aspect, charging means for charging at least the electrophotographic photosensitive member, and electrostatic exposure by performing image exposure on the charged electrophotographic photosensitive member. An image forming apparatus comprising: an image exposure unit that forms a latent image; a developing unit that develops the electrostatic latent image with toner; and a transfer unit that transfers the toner to a transfer target ( (Claim 3)
.

  By using the specific stilbene compound of the present invention and a polycarbonate resin having a specific structure in an electrophotographic photosensitive member, an electrophotographic cartridge and image formation free from image defects such as defective cleaning, streaks, and white spots in halftone portions are obtained. An apparatus can be provided. In addition, when this electrophotographic photosensitive member is used for printing, there is no generation of reversal of the cleaning blade and rubbing noise.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. It is an X-ray diffraction diagram showing a powder X-ray diffraction spectrum of oxytitanium phthalocyanine used to adjust the coating solution L for forming a charge generation layer used in Examples and Comparative Examples of the present invention. FIG. 3 is an X-ray diffraction diagram showing a powder X-ray diffraction spectrum of oxytitanium phthalocyanine used for preparing the charge generation layer forming coating solution M used in Examples and Comparative Examples of the present 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 compounds≫
The stilbene compound of the present invention has a structure represented by the following general formula [2].

(In the formula [2], Ar ⁴ and Ar ⁵ represent a phenyl group having at least one alkyl group having 1 to 4 carbon atoms, and R ⁹ represents an alkyl group having 2 to 4 carbon atoms. A, B May be the same or different and represents an organic group having 1 to 4 carbon atoms, and m and n each represents an integer of 0 to 4).
In the above formula [2], the substituent of Ar ⁴ or Ar ⁵ is an alkyl group having 1 to 4 carbon atoms, specifically, methyl group, ethyl group, n-propyl group, isopropyl group, n- A butyl group, an isobutyl group, and a tert-butyl group are mentioned. Among them, a methyl group and an ethyl group are preferable in terms of electrical characteristics, and a methyl group is particularly preferable.

In the formula [2], R ⁹ is an alkyl group having 2 to 4 carbon atoms, and examples thereof include an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. From the viewpoint of electrical characteristics and production cost, R ⁹ is particularly preferably an ethyl group, an n-propyl group or an isopropyl group. When the number of carbon atoms is 2 to 4, an electrophotographic photoreceptor having good charge transport material solubility and good electrical characteristics can be obtained. On the other hand, when the number of carbon atoms in the alkyl group is 5 or more, there is a risk that electrical characteristics and acid gas resistance will deteriorate.

In the formula [2], A and B are organic groups having 1 to 4 carbon atoms, and examples thereof include an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms. Are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, methoxy,
An ethoxy group, a propoxy group, a butoxy group, etc. are mentioned. Among these, a substituent having 1 carbon atom is particularly preferable from the viewpoint of electrical characteristics and production cost.

In the formula [2], m and n are each an integer of 0 to 4, and an integer of 0 to 1 is preferable, but from the viewpoint of production cost, m = n = 0 is particularly preferable.
The molecular weight of the formula [2] is usually 500 or less, preferably 460 or less. When the photosensitive layer contains a charge transporting agent that satisfies this range, the surface hardness of the photoreceptor is increased, and the cleaning performance is improved when evaluating actual images, and it is easy to prevent abnormal noise and filming. . Therefore, in the formula [1], it is particularly preferable to adjust the substituents Ar ⁴ and Ar ⁵ and R ⁹ , A, B, m, and n in view of the molecular weight. On the other hand, the lower limit is preferably 400 or more from the viewpoint of electrical characteristics.

As a typical example of the stilbene compound represented by the formula [2], the following exemplified compound CT-1
-CT-10 is mentioned. However, the charge transport material according to the present invention is not limited to these compounds.

≪Polycarbonate resin≫
The polycarbonate resin of the present invention has a repeating structure represented by the following formula [1].

(In Formula [1], R ^{10 to} R ¹⁷ may be the same or different and each represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen group. R ¹⁸ and R ¹⁹ are each independently selected. And represents a hydrogen atom, an alkyl group, or an aryl group, provided that R ^{10 to} R ¹⁷ must not be hydrogen atoms at the same time.)
In the above formula [1], specific examples of the substituents R ^{10 to} R ¹⁷ include an alkyl group and aryl, and R ^{10 to} R ¹⁷ may be the same or different. When the substituents R ^{10 to} R ¹⁷ are alkyl groups, the carbon number of the alkyl group is usually 1 or more, on the other hand, usually 10 or less, from the viewpoint of electrical characteristics,
Preferably it is 6 or less, more preferably 2 or less, and methyl is particularly preferred in view of the mechanical properties as a binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer. When the substituents R ^{10 to} R ¹⁷ are aryl groups, they are usually aromatic hydrocarbon groups having 1 to 3 rings such as a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group, from the viewpoint of production cost. Preferably, they are a phenyl group and a naphthyl group, and more preferably a phenyl group from the viewpoint of compatibility with the charge transport material.

From the viewpoint of adhesiveness, it is more preferable to have one or two substituents for the phenyl group of the above formula [1], and from the viewpoint of improving surface hardness, it should have one substituent. Particularly preferred. In this case, the substituent is preferably an alkyl group from the viewpoint of electrical characteristics, more preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group from the viewpoint of production cost.
In the above formula [1], R ¹⁸ and R ¹⁹ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Considering the mechanical properties as a binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, the alkyl group is usually an alkyl group having 1 to 6 carbon atoms, such as a methyl group or an ethyl group. , A propyl group, an isopropyl group and the like, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is particularly preferable from the viewpoint of wear resistance. As the aryl group, a phenyl group and a naphthyl group are preferable, and a phenyl group is particularly preferable.

As a representative example of the repeating unit of the polycarbonate resin represented by the formula [1],
The following exemplary compounds B-1 to B-6 are mentioned. However, the polycarbonate resin according to the present invention is not limited to these compounds.

  The polycarbonate resin of the present invention may be a polymer obtained by polymerizing a single repeating unit as described above, or may be a copolymer obtained from a combination of two or more. As the copolymerization component, for example, those having the repeating structure shown below are preferable, and those having the structure shown in B-9 below are more preferable from the viewpoint of improving electrical characteristics and surface properties of the photoreceptor.

In the above polycarbonate resin, the weight ratio of the partial structure represented by the formula [1] is preferably as large as possible from the viewpoints of electrical characteristics and wear resistance. Specifically, the partial structure represented by the formula [1] is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more with respect to the total weight of the polycarbonate resin. In particular, the content is desirably 100% by mass.

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

<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 (I) described above, and the charge generation material and the charge transport material (including the stilbene compound) are present in the same layer. A single layer structure in which they are dispersed in a binder resin (hereinafter referred to as “single layer type photosensitive layer” as appropriate), a charge generation layer in which a charge generation material is dispersed in a binder resin, and a charge transport material ( A functionally-separated layered structure composed of two or more layers including a charge transport layer dispersed in a binder resin (including a stilbene compound) (hereinafter referred to as “laminated photosensitive layer” as appropriate). However, any form may be sufficient. 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. Among them, a disazo pigment, a trisazo pigment and a phthalocyanine pigment are preferably used in combination. More preferred.

  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 compounding 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 0.1 μm or more, preferably 0.15 μm or more, and usually 10 μm.
m 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, the stilbene compound of the present invention is preferably used. As the stilbene-based compound of the present invention, the same compounds may be used alone, or a plurality of compounds may be combined at an arbitrary ratio.
In addition to the stilbene compound of the present invention, other known charge transport materials may be used in combination. When other charge transport materials are used in combination, the kind thereof is not particularly limited. For example, a charge transport material having the following structure can be preferably used together.

(In general formula [4], X represents a cycloaliphatic alkyl group, R ¹ represents an alkyl group, an aralkyl group, or an aryl group, R ² represents a hydrogen atom, a methyl group, or a phenyl group, and R ³ , R ⁴ represents a hydrogen atom, an aryl group or an alkyl group, R ⁵ represents hydrogen or an alkyl group, and n represents an integer of 0 to 3)

(In the general formula [5], Ar ¹ and Ar ² represent an aryl group or an aralkyl group, Ar ³ represents an arylene group, R ⁶ represents a hydrogen atom or an alkyl group, and R ⁷ and R ⁸ represent an alkyl group or an aryl group)
Specific examples of these charge transport materials used in combination include the following exemplified compounds CT-11 and CT-12. However, it is not limited to these compounds.

  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, but is 1% by mass. It is preferably within the range of 20% by mass or less, and particularly preferably within the range of 3% by mass or more and 10% by mass or less in order to more effectively exert the role of the stilbene compound of the present invention.

The binder resin is used for securing the film strength, and the polycarbonate resin of the present invention is preferably used. Any one of the polycarbonate resins of the present invention may be used alone, or two or more may be used in any combination.
In addition to the polycarbonate resin of the present invention, other known binder resins may be used in combination. For example, 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, ethyl vinyl ether, polyvinyl butyral resin, polyvinyl formal Resins, partially modified polyvinyl acetals, polycarbonate resins, polyester resins, polyarylate resins, polyamide resins, polyurethane resins, cellulose ester resins, phenoxy resins, silicon resins, silicon-alkyd resins, poly-N-vinylcarbazole resins, and the like. Of these, polycarbonate resins and polyarylate resins are preferred. Any one of these binder resins used in combination may be used alone, or two or more may be used in any combination.

The ratio of the binder resin and the charge transport material in the charge transport layer is such that the charge transport material is used in 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>
The single-layer type photosensitive layer is formed using a binder resin in order to ensure film strength, in the same manner as the charge transport layer of the multilayer photoconductor, in addition to the charge generation material and the charge transport material. 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 use ratios thereof are the same as those described for the charge transport layer of the multilayer photoreceptor. A charge generation material is further dispersed in a charge transport medium comprising these charge transport materials and a 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 mass or more, preferably 1 part by mass or more, and usually 100 parts by mass 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>
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. Further, 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. This developing roller 44
The surface may be smoothed or roughened if 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 silicon 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 departing from the gist thereof. Note that “parts” used in this example represents “parts by weight” unless otherwise specified.
[Calculation method of viscosity average molecular weight]
The viscosity average molecular weight of the polycarbonate resin contained in the charge transport layer was calculated as follows.

The polycarbonate resin was dissolved in dichloromethane to prepare a solution having a concentration C of 6.00 [g / L]. The flow time t [s] of the sample solution was measured in a constant temperature water bath set to 20.0 ° C. using an Ubbelohde capillary viscometer with a flow time t ₀ [s] of the solvent (dichloromethane) of 136.16 seconds. . And the viscosity average molecular weight Mv was computed according to the following formula | equation.
a = 0.438 × η _sp +1
η _sp = (t / t ₀ ) −1
t ₀ = 136.16 [s]
b = 100 × η _sp / C
C = 6.00 [g / L]
η = b / a
Mv = 3207 × η ^1.205
[Manufacture of coating solution for charge transport layer formation]
<Production Example 1>
100 parts of polycarbonate resin having the above repeating structure B-1 (viscosity average molecular weight 50,000)
80 parts of CT-1 as a charge transport material, 8 parts of a compound (AOX1) represented by the following formula as an antioxidant, and 0.05 part of silicone oil as a leveling agent, THF / toluene (8/2) (Weight ratio)) was dissolved in 640 parts of a mixed solvent to prepare a coating solution for forming a charge transport layer.

<Production Example 2>
A charge transport layer forming coating solution was prepared in the same manner as in Production Example 1 using CT-2 instead of CT-1 used in the charge transport layer forming coating solution of Production Example 1.
<Production Example 3>
A coating solution for forming a charge transport layer was prepared in the same manner as in Production Example 1 using CT-3 instead of CT-1 used for the coating solution for forming a charge transport layer in Production Example 1.

<Production Example 4>
Except for using the polycarbonate resin (viscosity average molecular weight 40,000) having the repeating structure B-2 instead of the polycarbonate resin (repeating structure B-1) used in the coating liquid for forming the charge transport layer in Production Example 1, In the same manner as in Production Example 1, a coating solution for forming a charge transport layer was prepared.
<Production Example 5>
Except for using the polycarbonate resin (viscosity average molecular weight 40,000) having the repeating structure B-9 instead of the polycarbonate resin (repeating structure B-1) used in the coating liquid for forming the charge transport layer in Production Example 1, In the same manner as in Production Example 1, a coating solution for forming a charge transport layer was prepared.

<Production Example 6>
Except for using the polycarbonate resin having the repeating structure B-11 (viscosity average molecular weight 43,000) instead of the polycarbonate resin (repeating structure B-1) used in the coating liquid for forming the charge transport layer of Production Example 1, In the same manner as in Production Example 1, a coating solution for forming a charge transport layer was prepared.
<Production Example 7>
Except for using the polycarbonate resin (viscosity average molecular weight 38,000) having the repeating structure B-12 instead of the polycarbonate resin (repeating structure B-1) used in the coating liquid for forming the charge transport layer in Production Example 1, In the same manner as in Production Example 1, a coating solution for forming a charge transport layer was prepared.

<Production Example 8>
A charge transport layer forming coating solution was prepared in the same manner as in Production Example 1 using CT-3 instead of CT-1 used in the charge transport layer forming coating solution of Production Example 7.
<Comparative Production Example 1>
Instead of CT-1 used in the charge transport layer forming coating solution of Production Example 1, the charge transport material X described in Patent Document 1 was used, and the charge transport layer forming coating solution was prepared in the same manner as in Production Example 1. Although it was prepared, turbidity was generated in the liquid and CTM crystal precipitation was observed.

<Comparative Production Example 2>
Instead of the polycarbonate resin (repeated structure B-1) used in the coating liquid for forming the charge transport layer in Production Example 3, a polycarbonate resin (viscosity average molecular weight 40,000) having the following repeated structure B-16 was used. Charge transport layer in the same manner as in Production Example 3, except that dichloroethane was used in place of the / solvent (8/2 (weight ratio)) mixed solvent (because gelation of the coating liquid occurred in the THF / toluene mixed solvent) A forming coating solution was prepared.

<Comparative Production Example 3>
Instead of CT-1 used in the charge transport layer forming coating solution of Production Example 1, the charge transport material Y described in Patent Document 1 was used, and the charge transport layer forming coating solution was prepared in the same manner as in Production Example 1. Prepared.
<Comparative Production Example 4>
A polycarbonate resin having a repeating structure B-9 (viscosity average molecular weight 40,000) was used in place of the polycarbonate resin (repeating structure B-1) used in the charge transport layer forming coating solution of Comparative Production Example 3. In the same manner as in Comparative Production Example 3, a coating solution for forming a charge transport layer was prepared.

<Comparative Production Example 5>
A coating solution for forming a charge transport layer was prepared in the same manner as in Production Example 1 using Compound Z represented by the following formula instead of CT-1 used for the coating solution for forming a charge transport layer in Production Example 1.

<Example 1>
On the aluminum cylinder having a mirror-finished outer diameter of 30 mm, length of 260.5 mm, and wall thickness of 0.75 mm, the following undercoat layer forming coating solution, charge generating layer forming coating solution, and charge transport layer The undercoat layer, the charge generation layer, and the charge transport layer are formed so that the coating liquid for formation is sequentially applied by a dip coating method, and the film thickness after drying is 1.3 μm, 0.4 μm, and 25 μm, respectively. A photoreceptor drum was obtained.

[Manufacture of coating solution for forming undercoat layer]
The undercoat layer forming coating solution was prepared as follows. 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 were mixed using a Henschel mixer. The surface-treated titanium oxide obtained by mixing was dispersed by a ball mill in a mixed solvent having a methanol / 1-propanol weight ratio of 7/3 to obtain a surface-treated titanium oxide dispersed slurry. 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 [compound represented by the following formula (G)] / hexamethylenediamine [compound represented by the following formula (H)] / decamethylene dicarboxylic acid [compound represented by the following formula (J) ] / Octadecamethylene dicarboxylic acid [compound represented by the following formula (K)]
After stirring and mixing the copolyamide pellets having a composition molar ratio of 60% / 15% / 5% / 15% / 5% with heating, the polyamide pellets are dissolved and then subjected to ultrasonic dispersion treatment. By performing the measurement, the weight ratio of methanol / 1-propanol / toluene is 7/1/2 and the surface-treated titanium oxide / copolymerized polyamide is contained at a weight ratio of 3/1. A layer forming coating solution was prepared.

[Manufacture of coating solution for forming charge generation layer]
The charge generation layer forming coating solution was prepared as follows. As a charge generation material, 20 parts of oxytitanium phthalocyanine and 280 parts of 1,2-dimethoxyethane showing the X-ray diffraction spectrum by CuKα characteristic X-rays in FIG. 3 are mixed, and pulverized and dispersed in a sand grind mill for 1 hour. Processing was performed. Subsequently, 10 parts of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denkabutyral” # 6000C) was added to 255 parts of 1,2-dimethoxyethane and 4-methoxy-4-methyl. A binder liquid obtained by dissolving in 85 parts of 2-pentanone and 230 parts of 1,2-dimethoxyethane were mixed to prepare a coating solution L for forming a charge generation layer.

As a charge generation material, 20 parts of oxytitanium phthalocyanine showing X-ray diffraction spectrum by CuKα characteristic X-ray in FIG. 4 and 280 parts of 1,2-dimethoxyethane are mixed and pulverized in a sand grind mill for 4 hours to be atomized and dispersed. Processing was performed. Subsequently, 10 parts of polyvinyl butyral (trade name “Denka Butyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) was added to 255 parts of 1,2-dimethoxyethane and 4-methoxy-4-methyl. A binder liquid obtained by dissolving in 85 parts of 2-pentanone and 230 parts of 1,2-dimethoxyethane were mixed to prepare a coating solution M for forming a charge generation layer.

The charge generation layer forming coating solution L and the charge generation layer forming coating solution M were mixed at a weight ratio of 8: 2 to prepare a charge generation layer forming coating solution used in this example.
The coating liquid prepared in Production Example 1 was used as the coating liquid for forming the charge transport layer.
The obtained electrophotographic photosensitive drum was subjected to the following electrical property test.
[Electrical characteristics test]
Using an electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, page 404-405), the above photosensitive drum is rotated at a constant speed. It was rotated at 60 rpm, and an electrical property evaluation test was performed by a cycle of charging, exposure, potential measurement, and static elimination. At that time, the initial surface potential of the photoconductor is-(minus, the same applies hereinafter) 700 V.
The surface potential after exposure (hereinafter referred to as VL) after 100 milliseconds when the halogen lamp light is exposed to 1.0 μJ / cm ² using a 780 nm monochromatic light with an interference filter. Measured). In the VL measurement, the time required from the exposure to the potential measurement was set to 100 ms, which was a fast response condition. Further, the half-exposure energy E _1/2 (μJ / cm ² ) required until the photoreceptor surface potential was changed from −700 V to −350 V was obtained. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%. The results obtained are shown in Table 1. In Table 1, “CTM” represents “charge transport material”.

[Image characteristics test]
Next, using the photosensitive drum produced above and a toner having an average particle diameter of 6.0 μm and an average circularity of 0.990, it was mounted on an actual machine and subjected to an image characteristic test.
The image characteristic test was performed using a color printer HP Color LaserJet 4700dn (cleaning blade, counter contact method) manufactured by Hewlett-Packard Company.

The produced photosensitive drum and toner were mounted on a cyan process cartridge, and this cartridge was mounted on a printer. 10,000 images were formed under an environment of a temperature of 25 ° C. and a humidity of 50%, and the streaks, white spots in the halftone portion, and the presence or absence of poor cleaning were evaluated. The presence or absence of abnormal noise during printing was also observed at the same time.
In the image forming apparatus using the electrophotographic photosensitive member of Example 1, after 10,000 sheet image formation,
A good image without image deterioration such as streak or poor cleaning was obtained. There was almost no white spot in the halftone area. In addition, no abnormal noise was generated during printing. The results are also summarized in Table 1.

<Examples 2 to 8>
Instead of the charge transport layer forming coating solution prepared in Production Example 1 used in Example 1, the same procedure as in Example 1 was used except that the charge transport layer forming coating solution prepared in Production Examples 2 to 8 was used. Thus, a photoreceptor was manufactured. Further, the electrical property test and the image property test were performed in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Examples 1-5>
Similar to Example 1 except that the charge transport layer forming coating solution prepared in Comparative Production Examples 1 to 5 was used instead of the charge transport layer forming coating solution prepared in Production Example 1 used in Example 1. Thus, a photoreceptor was produced. Further, the electrical property test and the image property test were performed in the same manner as in Example 1. The results are shown in Table 1. In Comparative Example 1, since many crystals were precipitated, measurement of electrical characteristics was not achieved.

* Since many crystals were precipitated, the properties could not be measured.
** The following symbols indicate the image defects (or how the rubbing sound is generated) observed when image evaluation is performed by the method specified above.
A: Good and no defects are visible.
○: Almost no defects are visible.

(Triangle | delta): A defect is seen lightly or a rubbing sound is heard.
X: Defects can be clearly seen or rubbing noise can be heard clearly.
As can be seen from the comparison of Examples 1 to 8 and Comparative Example 5 in terms of electrical characteristics, the photoreceptor using the charge transport material of the present invention represented by the general formula [2] is It can be seen that the electrical characteristics are superior to the stilbene-based charge transport material Z having a similar structure outside the scope of the invention. In addition, since the stilbene-based charge transport material Q is poorly compatible with the binder resin, the electrophotographic photosensitive member using the stilbene-based charge transport material Q precipitates a lot of crystals after coating, and light attenuation is hardly seen. The properties were not measured (Comparative Example 1). On the other hand, it can be seen that the stilbene charge transport material Y outside the scope of the present invention is better than the charge transport material of the present invention represented by the general formula [2] in terms of electrical characteristics (Comparative Examples 3 to 4).

As can be seen from the comparison between Examples 1 to 8 and Comparative Examples 2 to 5 in Table 1, in the actual photograph result, the polycarbonate resin of the present invention represented by the general formula [1] and the general formula [2] are represented. It was found that by using in combination with the charge transport material of the present invention, a good image can be obtained without occurrence of streaks, white spots in the halftone portion, and poor cleaning. On the other hand, when a polycarbonate resin (repeating unit B-16) outside the scope of the present invention is used, it is preferable in terms of electrical characteristics, but cleaning failure occurs (see Comparative Example 2).

In addition, when the polycarbonate resin of the present invention is used in combination with the stilbene-based charge transport material Y outside the scope of the present invention, streaks and white spots in the halftone portion are generated (Comparative Examples 3 to 4).
Furthermore, from the results in Table 2, it is clear that not only the compatibility with the binder resin is good when using the stilbene-based charge transport material of the present invention (see Comparative Example 1), but also noise during printing can be suppressed. It became. In Comparative Example 5, abnormal noise occurs.

Further, when the polycarbonate resin of the present invention and the stilbene-based charge transport material Z outside the scope of the present invention are used in combination, various image defects are generated after printing 10,000 sheets (see Comparative Example 5).
While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. The electrophotographic photosensitive member and the image forming apparatus accompanying such changes are also within the technical scope of the present invention, and can be appropriately changed without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. Must be understood as encompassed by.

The present invention can be carried out in any field that requires an electrophotographic photoreceptor, 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)

In an electrophotographic photoreceptor having a photosensitive layer on a conductive support, the photosensitive layer has the following formula [1
An electrophotographic photoreceptor comprising a polycarbonate resin having a repeating structure represented by the formula [2] and a stilbene compound represented by the following formula [2]:

(In Formula [1], R ^{10 to} R ¹⁷ may be the same or different and each represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a halogen group. R ¹⁸ and R ¹⁹ are each independently selected. And represents a hydrogen atom, an alkyl group, or an aryl group, provided that R ^{10 to} R ¹⁷ must not be hydrogen atoms at the same time.)

(In the formula [2], Ar ⁴ and Ar ⁵ represent a phenyl group having at least one alkyl group having 1 to 4 carbon atoms, and R ⁹ represents an alkyl group having 2 to 4 carbon atoms. A, B May be the same or different and represents an organic group having 1 to 4 carbon atoms, and m and n each represents an integer of 0 to 4). 2. The electrophotographic photosensitive member according to claim 1, charging means for charging the electrophotographic photosensitive member, image exposing means for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic Among developing means for developing a latent image with toner, transfer means for transferring the toner from the electrophotographic photosensitive member to a transfer target, and cleaning means for removing toner remaining on the electrophotographic photosensitive member after transfer, An electrophotographic cartridge comprising at least one. The electrophotographic photosensitive member according to claim 1, a charging unit that charges at least the electrophotographic photosensitive member, an image exposing unit that performs image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image, An image forming apparatus comprising: a developing unit that develops the electrostatic latent image with toner; and a transfer unit that transfers the toner to a transfer target.

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