JP2008026478A - Electrophotographic photoreceptor, process cartridge and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of charging ability after duration with respect to a thin film CT disadvantageous to charging ability. <P>SOLUTION: An electrophotographic photoreceptor is provided which has a conductive layer, an intermediate layer, a charge generating layer and a charge transport layer in this order on a support, wherein the charge transport layer contains a polyarylate resin, the conductive layer contains a binder resin and conductive particles which are TiO<SB>2</SB>particles coated with oxygen-deficient SnO<SB>2</SB>and have an average particle diameter of 0.2-0.6 μm, and the conductive layer has a thickness of 10-25 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member, a process cartridge having an electrophotographic photosensitive member, and an electrophotographic apparatus.

  In recent years, organic photoconductive substances have been actively developed from the viewpoint of pollution-free, high productivity, and ease of material design.

  An electrophotographic photoreceptor using an organic photoconductive substance is formed by applying a coating solution obtained by dissolving and dispersing an organic photoconductive substance or a binder resin in a solvent on a support and drying it. Those having a light-sensitive layer formed are usually used. The layer structure of the photosensitive layer is generally a laminate type (normal layer type) in which a charge generation layer and a charge transport layer are laminated in this order from the support side.

  An electrophotographic photoreceptor using an organic photoconductive material has the above-mentioned advantages, but does not satisfy all of the characteristics required as an electrophotographic photoreceptor at a high level. Further improvement in image quality and durability of output images is desired.

  In recent years, with regard to the improvement of image quality, in order to further increase the resolution of an output image, as exposure light (image exposure light) irradiated to an electrophotographic photosensitive member, light having a shorter wavelength than conventionally used light (for example, wavelength) Has been proposed (Patent Document 1).

  In addition, in the case of a layered type (forward layer type) in which a charge generation layer and a charge transport layer are stacked in this order from the support side, since the photocarrier generated in the charge generation layer crosses the charge transport layer, the image light reflection It spreads from the part and the resolution decreases. Therefore, in order to improve the resolution, a proposal has been made that the film thickness of the photosensitive layer of the electrophotographic photosensitive member is 20 μm or less (Patent Document 2).

  On the other hand, with regard to the improvement of durability, polycarbonate resin has been often used as a binder resin for the surface layer of the electrophotographic photosensitive member. However, in recent years, as a binder resin for the surface layer, more than polycarbonate resin. A proposal has been made to further improve the durability of an electrophotographic photosensitive member by using a polyarylate resin having high mechanical strength (Patent Document 3). The polyarylate resin is one type of aromatic dicarboxylic acid polyester resin.

  As a higher strength polyarylate resin, a polyarylate resin in which a diphenyl ether dicarboxylic acid structure is introduced into the dicarboxylic acid structure of the polyarylate resin has been proposed (Patent Document 4).

  An electrophotographic photosensitive member is basically composed of a support and a photosensitive layer provided on the support. However, the present situation is that the surface of the support is covered with defects and the coating property of the photosensitive layer is improved. In order to improve the adhesion between the support and the photosensitive layer, protect against electrical breakdown of the photosensitive layer, improve the chargeability, improve the charge injection property from the support to the photosensitive layer, etc. Various layers are often provided between them. The layer provided between the support and the photosensitive layer is required to have many functions such as coverage, adhesiveness, mechanical strength, conductivity, and electrical barrier properties.

  Conventionally, the following types are known as layers provided between the support and the photosensitive layer.

  (I) A resin layer not containing a conductive material.

  (Ii) A resin layer containing a conductive material.

  (Iii) A layer obtained by laminating the layer (i) above the layer (ii).

  Since the layer (i) does not contain a conductive material, the resistance of the layer is high. Moreover, in order to cover the defects on the surface of the support that has not been subjected to the surface smoothing treatment, the thickness (film thickness) must be increased.

  However, when the film thickness of the layer (i) having high resistance is increased, there arises a problem that the residual potential at the initial stage and repeated use is increased. Therefore, in order to put the layer (i) to practical use, it is necessary to reduce the defects on the surface of the support and reduce the film thickness.

  On the other hand, the layer (ii) is a layer in which a conductive material such as conductive particles is dispersed in a resin, and since the resistance of the layer can be reduced, the layer thickness is increased, It is possible to cover defects on the surface of a conductive support or a non-conductive support (such as a resin support).

  However, when the thickness of the layer (ii) is increased, it is necessary to impart sufficient conductivity to the layer as compared with the layer (i) to be reduced. Therefore, the layer (ii) In order to prevent charge injection from the substrate (ii) above to the photosensitive layer, which causes image defects, in a wide range of environmental conditions from low temperature and low humidity to high temperature and high humidity. It is preferable that a layer having an electrical barrier property is separately provided between the layer (ii) and the photosensitive layer. The layer having an electrical barrier property is a resin layer that does not contain conductive particles like the layer (i).

  That is, the layer provided between the support and the photosensitive layer preferably has the configuration (iii) in which the layer (i) and the layer (ii) are stacked.

  The structure of (iii) requires a plurality of layers to be formed, and thus the number of processes increases accordingly. However, since the allowable range of defects on the surface of the support is increased, the allowable use range of the support is greatly expanded, and production is performed. There is an advantage that improvement in performance can be achieved.

  In general, the layer (ii) is referred to as a conductive layer, and the layer (i) is referred to as an intermediate layer (undercoat layer, barrier layer).

  In addition, an aluminum tube manufactured by a manufacturing method including an extrusion step and a drawing step, and an aluminum tube manufactured by a manufacturing method including an extrusion step and a squeezing step have good dimensional accuracy as a non-cutting tube without surface cutting. It is used as a support for an electrophotographic photosensitive member that provides surface smoothness and is advantageous in terms of cost. However, the surface of the uncut aluminum tube is liable to have a rust-like convex defect, and the configuration (iii) is preferable from the viewpoint of concealing the surface defect of the support.

Examples of the conductive material used for the conductive layer include various metals, metal oxides, and conductive polymers. Among these, tin oxide (hereinafter referred to as SnO ₂ ) having excellent resistance characteristics can be used in the production of SnO ₂ conductive materials, such as antimony oxide, from the ordinary powder resistivity of 10 ⁴ to 10 ⁶ Ω · cm. Mixing (doping) a metal compound or a nonmetallic element having a valence different from that of tin, reducing the powder resistivity to 1/1000 to 1/100000, or non-doping without increasing the constituent elements Thus, there is an oxygen-deficient SnO ₂ conductive material in which the resistance of SnO ₂ is made as low as that of antimony dope.

As a prior art related to oxygen deficient SnO ₂ , a technique using oxygen deficient SnO ₂ for a conductive layer is disclosed. (Patent Document 5) In addition, a technique is disclosed in which dispersibility is improved as compared with a case where barium sulfate particles are coated with oxygen-deficient SnO ₂ and only SnO ₂ is used. (Patent Document 6) Further, although not disclosed until the embodiment of oxygen-deficient SnO ₂ , in order to improve dispersibility, barium sulfate particles are used, and in order to improve whiteness, oxidation is performed. A technique of coating SnO ₂ to coat titanium (TiO ₂ ) and further impart electrical conductivity thereon has been disclosed. (Patent Document 7)
JP 09-240051 A JP 09-304955 A Japanese Patent Laid-Open No. 10-039521 JP-A-10-020514 JP 07-295245 A Japanese Patent Laid-Open No. 06-208238 JP-A-10-186702

  However, in an electrophotographic photoreceptor having a conductive layer, an intermediate layer, a charge generation layer, and a charge transport layer in this order on a support, the electroconductive layer containing a binder resin and conductive particles. In order to achieve both durability and high image quality of the electrophotographic photosensitive member, it is only necessary to use a resin with high mechanical strength as the binder resin for the surface layer of the electrophotographic photosensitive member and to reduce the film thickness. In some cases, the potential stability of repeated use in a low-temperature and low-humidity environment may be insufficient, and improvements are desired.

  The object of the present invention is to provide an electrophotographic photosensitive member which has a conductive layer, an intermediate layer, and a photosensitive layer on a support in this order, and has high durability and excellent potential stability during repeated use. Is to provide a body. Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus that have such an electrophotographic photosensitive member and can continuously form a stable image.

The present invention provides an electrophotographic photosensitive member having a conductive layer, an intermediate layer, a charge generation layer, and a charge transport layer in this order on a support, wherein the conductive layer contains a binder resin and conductive particles. In the body,
The conductive particles are TiO ₂ particles coated with oxygen-deficient SnO ₂ , the conductive particles have an average particle size of 0.20 to 0.60 μm, and the conductive layer has a thickness of 10 to 25 μm, The charge transport layer contains a polyarylate resin. A process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

  According to the present invention, it is possible to provide an electrophotographic photoreceptor having high durability and excellent potential stability during repeated use, and a process cartridge and an electrophotographic apparatus having the electrophotographic photoreceptor.

Hereinafter, the present invention will be described in more detail.
As described above, the present invention is an electrophotographic photosensitive member having a conductive layer, an intermediate layer, a charge generation layer, and a charge transport layer in this order on a support, and the conductive layer contains a binder resin and conductive particles. In an electrophotographic photoreceptor
The conductive particles are TiO ₂ particles coated with oxygen-deficient SnO ₂ , the conductive particles have an average particle size of 0.20 to 0.60 μm, and the conductive layer has a thickness of 10 to 25 μm, The charge transport layer contains a polyarylate resin.

  First, the structure of the electrophotographic photosensitive member of the present invention will be described, and each layer will be described in order.

  As shown in FIG. 1, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a conductive layer 102, an intermediate layer 103, a charge generation layer 1041, and a charge transport layer 1042 in this order on a support 101 (see FIG. 1). 1 (a)). Further, a protective layer 105 may be provided over the charge transport layer 1042 (see FIG. 1B).

  As a support body, what has electroconductivity (conductive support body) is preferable, for example, metal supports, such as aluminum, an aluminum alloy, and stainless steel, can be used. In the case of aluminum and an aluminum alloy, an aluminum tube manufactured by a manufacturing method including an extrusion step and a drawing step, an aluminum tube manufactured by a manufacturing method including an extrusion step and a squeezing step, and cutting and electrolytic composite polishing ( An electrode having an electrolytic action and electrolysis with an electrolytic solution and polishing with a grindstone having a polishing action), wet or dry honing treatment can also be used. In addition, the above metal support or resin support (polyethylene terephthalate, polybutylene terephthalate, phenol resin, polypropylene, polystyrene resin) having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide-tin oxide alloy, or the like. Etc.) can also be used. In addition, a support in which conductive particles such as carbon black, tin oxide particles, titanium oxide particles, and silver particles are impregnated with a resin or paper, a plastic having a conductive binder resin, or the like can also be used.

In order for the charge (carriers) of the conductive layer to flow to ground, the volume resistivity of the conductive support is also determined if the surface of the support is a layer provided to provide conductivity. The volume resistivity is preferably 1.0 × 10 ¹⁰ Ω · cm or less, and more preferably 1.0 × 10 ⁶ Ω · cm or less.

  When the support is a non-conductive support, it is necessary to adopt a configuration in which the ground is taken from the conductive layer of the electrophotographic photosensitive member of the present invention.

  A conductive layer is provided on the support.

The conductive particles used in the present invention are TiO ₂ particles coated with SnO ₂ whose resistance is reduced by depleting oxygen (1 / 10,000 in powder resistivity). Oxygen deficient SnO ₂ is more reusable than SnO ₂ doped with a different element such as antimony. In addition, there is little increase in resistivity under a low humidity environment and a decrease in resistivity under a high humidity environment, and it is excellent in environmental stability.

The reason why the conductive particles used in the present invention are not particles composed only of oxygen-deficient SnO ₂ but TiO ₂ particles coated with oxygen-deficient SnO ₂ is as follows.

First, the core particles are used in order to improve the dispersibility of the conductive particles in the conductive layer. When a conductive layer coating solution is prepared using only oxygen-deficient SnO ₂ as the conductive particles, especially when the content ratio of oxygen-deficient SnO ₂ is high, aggregation of oxygen-deficient SnO ₂ is likely to occur.

Also, were used TiO ₂ particles as the core particles, the affinity of the oxide sites oxygen deficient SnO ₂ oxygen defect sites and TiO ₂ particle surface, binding the coating layer of the oxygen-deficient SnO ₂ and the core member Because is strengthened. Moreover, it is because the oxygen deficient site of oxygen deficient SnO ₂ is protected. Unlike the doped type, the oxygen deficient type may be oxidized in the presence of oxygen to lose the oxygen deficient site, resulting in a decrease in conductivity (increase in powder resistivity).

Further, when the exposure light (image exposure light) is laser light, the TiO ₂ particles that are the core material particles interfere with light reflected by the support surface during laser exposure, and interference fringes are generated in the output image. This can be suppressed.

Incidentally, (a method of coating the oxygen-deficient SnO ₂ to a method and TiO ₂ particles to produce an oxygen-deficient SnO ₂₎ oxygen-defective TiO ₂ particle production method of the SnO ₂ coated is, JP-A 07-295245 JP And Japanese Patent Laid-Open No. 04-154621.

In order to keep the volume resistivity of the conductive layer within the above range, the powder resistivity of the TiO ₂ particles coated with the oxygen-deficient SnO ₂ as the conductive particles is preferably 1 to 500 Ω · cm, particularly Is more preferably 1 to 250 Ω · cm. If the powder resistivity is too high, the residual potential may increase. On the other hand, if the powder resistivity is too low, the charging ability may decrease.

In order to stably obtain TiO ₂ particles coated with oxygen-deficient SnO ₂ having a powder resistivity in the above range, the raw material blending ratio in producing the particles may be controlled. For example, it is calculated that 100% SnO ₂ is obtained from a tin raw material, and the tin raw material required to produce 30-60 mass% SnO ₂ with respect to TiO ₂ coated with oxygen-deficient SnO ₂ What is necessary is just to mix | blend at the time of particle | grain manufacture. In other words, the coverage of oxygen-deficient SnO _{2 on} TiO ₂ is preferably 30 to 60% by mass.

  The measurement method of the powder resistivity in the present invention is as follows.

As a measuring device, a resistance measuring device Loresta (registered trademark) AP (Loresta (registered trademark) Ap) manufactured by Mitsubishi Chemical Corporation was used. The powder to be measured (= particles) was hardened at a pressure of 500 kg / cm ² to obtain a pellet-shaped measurement sample. The measurement environment is 23 ° C. and 60% RH, and the applied voltage is 100V.

Next, the average particle diameter of TiO ₂ particles coated with oxygen-deficient SnO ₂ that is conductive particles will be described.

  Even if the composition of the conductive layer is the same, the powder resistivity of the conductive particles decreases as the average particle size of the conductive particles increases, and the volume resistivity of the conductive layer also decreases.

When the average particle diameter of the TiO ₂ particles coated with oxygen-deficient SnO ₂ that is conductive particles is less than 0.20 μm, the volume resistivity of the conductive layer is increased. Need to increase usage. However, when the amount of the conductive particles used is increased, the surface roughness of the conductive layer (Rzjis: 1) suitable for suppressing the interference of light reflected on the surface of the conductive layer and generating interference fringes in the output image. ~ 3 μm) is difficult to achieve. Rzjis is defined as Rz in JISB0601 (1994). In JISB0601, Rz was revised by the 2001 standard revision, and replaced with Ry (maximum height) in 1994. Rz in 1994 was renamed Rzjis in 2001 for distinction.

  Moreover, when the usage-amount of electroconductive particle is increased, when the film thickness of a conductive layer is thickened, it will become easy to generate | occur | produce a crack and film formability may fall.

  The dispersed particles were measured by a liquid phase precipitation method using a conductive layer coating solution having a composition of only conductive particles. Specifically, the conductive layer coating solution is diluted with a solvent used therein so that the transmittance is between 0.8 and 1.0, and an ultracentrifugal automatic particle size distribution manufactured by Horiba, Ltd. The average particle diameter (volume standard D50) and the histogram of the particle size distribution were measured using a measuring apparatus (CAPA (registered trademark) 700) under the condition of a rotational speed of 3000 rpm.

  Separately, after forming the conductive layer on the aluminum sheet, the cross-section of the conductive layer was observed. As a result, the same particle size and particle size distribution results as those obtained with the coating solution containing only the conductive particles were obtained.

In the present invention, the conductive layer is a conductive layer coating solution obtained by dispersing TiO ₂ particles coated with oxygen-deficient SnO ₂ having an average particle size of 0.20 to 0.60 μm together with a binder resin and a solvent. It can be formed by coating on top and drying it. Examples of the dispersion method include a method using a paint shaker, a sand mill, a ball mill, a liquid collision type high-speed disperser, and the like.

  Solvents used in the coating liquid for the conductive layer include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether and propylene glycol monomethyl ether, , Esters such as methyl acetate and ethyl acetate, and aromatic hydrocarbons such as toluene and xylene.

  From the viewpoint of concealing surface defects of the support, the thickness of the conductive layer is preferably 10 to 25 μm, more preferably 15 to 20 μm.

  In the present invention, the film thickness of each layer of the electrophotographic photosensitive member including the conductive layer was measured with a FISHERSPEPE MMS eddy current probe EAW3.3 manufactured by Fisher Instruments Co., Ltd.

  Examples of the binder resin for the conductive layer include phenol resin, polyurethane resin, polyamide resin, polyimide resin, polyamideimide resin, polyamic acid resin, polyvinyl acetal resin, epoxy resin, acrylic resin, melamine resin, and polyester resin. These can be used alone or in combination of two or more. In addition, among various resins, from the viewpoints of suppressing migration (melting) to other layers, adhesion to the support, dispersibility / dispersion stability of conductive particles, solvent resistance after film formation, etc., the conductive layer The binder resin is preferably a curable resin, and more preferably a thermosetting resin. Specifically, a thermosetting phenol resin, a polyurethane resin, or the like is preferable.

Further, in the present invention in which the film thickness of the conductive layer is 10 to 25 μm, the conductive layer (P) is bonded to TiO ₂ particles coated with oxygen-deficient SnO ₂ having an average particle diameter of 0.20 to 0.60 μm. The mass ratio (P / B) to the resin resin (B) is preferably 2.3 / 1 to 3.3 / 1. If the mass ratio (P / B) is too small, the volume resistivity of the conductive layer increases, or if the mass ratio (P / B) is too large, the average particle diameter in the conductive layer is 0.20 to 0.60 μm. TiO ₂ particles coated with the oxygen deficient SnO ₂ are difficult to bind, and cracks are likely to occur.

Further, in order to suppress the interference of light reflected on the surface of the conductive layer and the generation of interference fringes in the output image, the conductive layer is provided with a binder resin and an oxygen-deficient type having an average particle size of 0.20 to 0.60 μm. In addition to the TiO ₂ particles coated with SnO ² , it is also possible to add a surface roughening agent for roughening the surface of the conductive layer. As the surface roughness imparting material, resin particles having an average particle diameter of 1 to 3 μm are preferable, and examples thereof include curable rubber, polyurethane resin, epoxy resin, alkyd resin, phenol resin, polyester resin, silicone resin, and acrylic-melamine resin. Examples include curable resin particles. Among these, silicone resin particles that are difficult to aggregate are preferable. Since the specific gravity (0.5 to 2) of the resin particles is smaller than the specific gravity (4 to 7) of the TiO ₂ particles coated with oxygen-deficient SnO ₂ , the surface of the conductive layer is efficiently formed when the conductive layer is formed. It can be roughened. However, since the volume resistivity of the conductive layer tends to increase as the content of the surface roughening agent in the conductive layer increases, in order to keep the volume resistivity of the conductive layer within the above range, The content of the surface roughening agent is preferably 15 to 25% by mass with respect to the binder resin in the conductive layer.

  Further, a leveling agent may be added to improve the surface property of the conductive layer, and pigment particles may be contained in the conductive layer in order to improve the concealing property of the conductive layer.

  An intermediate layer is provided on the conductive layer.

In order to prevent charge injection from the conductive layer to the photosensitive layer, it is necessary to provide an intermediate layer having an electrical barrier property between the conductive layer and the photosensitive layer. The volume resistivity of the intermediate layer is 1.0 × It is preferably 10 ^{9 to} 1.0 × 10 ¹³ Ω · cm. If the volume resistivity of the intermediate layer is too small, the electrical barrier property becomes poor, and the occurrence of spots and fog due to charge injection from the conductive layer tends to become remarkable. On the other hand, if the volume resistivity of the intermediate layer is too large, the flow of charges (carriers) is stagnant during image formation, and the residual potential tends to increase (lack of potential stability).

  The method for measuring the volume resistivity of the intermediate layer in the present invention is as follows.

  First, an intermediate layer to be measured is formed on an aluminum sheet with a film thickness of about 2 to 5 μm, and a thin gold film is formed on the intermediate layer by vapor deposition. The flowing current value was measured with a pA meter. The measurement environment is RH%, and the applied voltage is 100V. A stable value 1 minute after the start of current value measurement was read, and the volume resistivity of the intermediate layer was derived.

  The intermediate layer can be formed by applying an intermediate layer coating solution containing a binder resin on the conductive layer and drying it.

  As the binder resin for the intermediate layer, water-soluble resins such as polyvinyl alcohol, polyvinyl methyl ether, polyacrylic acids, methyl cellulose, ethyl cellulose, polyglutamic acid, casein, and starch, polyamide resins, polyimide resins, polyamideimide resins, and polyamic acid resins , Melamine resin, epoxy resin, polyurethane resin, polyglutamate resin and the like. In order to effectively develop the electrical barrier property, the binder resin of the intermediate layer is preferably a thermoplastic resin from the viewpoints of coatability, adhesion, solvent resistance, resistance, and the like. Specifically, a thermoplastic polyamide resin or the like is preferable. The polyamide resin is preferably a low crystalline or non-crystalline copolymer nylon that can be applied in a solution state. Moreover, it is preferable that the film thickness of an intermediate | middle layer is 0.1-2 micrometers.

  Further, in order to prevent the flow of electric charges (carriers) in the intermediate layer, the intermediate layer may contain an electron transport material (electron accepting material such as an acceptor).

  A charge generation layer is provided on the intermediate layer.

  Examples of the charge generating material used in the electrophotographic photoreceptor of the present invention include azo pigments such as monoazo, disazo, and trisazo, phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, indigo pigments such as indigo and thioindigo, Perylene pigments such as perylene acid anhydride and perylene imide, polycyclic quinone pigments such as anthraquinone and pyrenequinone, squarylium dyes, pyrylium salts and thiapyrylium salts, triphenylmethane dyes, selenium, selenium-tellurium, amorphous Examples include inorganic substances such as silicon, quinacridone pigments, azurenium salt pigments, cyanine dyes, xanthene dyes, quinoneimine dyes, styryl dyes, cadmium sulfide, and zinc oxide. Among these, metal phthalocyanines such as oxytitanium phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine are particularly preferable.

  Examples of the binder resin used for the charge generation layer include polycarbonate resin, polyester resin, polyarylate resin, butyral resin, polystyrene resin, polyvinyl acetal resin, diallyl phthalate resin, acrylic resin, methacrylic resin, vinyl acetate resin, phenol resin, Examples thereof include silicone resins, polysulfone resins, styrene-butadiene copolymer resins, alkyd resins, epoxy resins, urea resins, vinyl chloride-vinyl acetate copolymer resins. These can be used singly or in combination of two or more as a mixture or copolymer.

  The charge generation layer can be formed by applying a charge generation layer coating solution obtained by dispersing a charge generation material together with a binder resin and a solvent and drying the coating solution. Examples of the dispersion method include a method using a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor, a roll mill and the like. The ratio between the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10 (mass ratio), and more preferably in the range of 3: 1 to 1: 1 (mass ratio).

  The solvent used in the coating solution for the charge generation layer is selected from the solubility and dispersion stability of the binder resin and charge generation material used, and the organic solvents include alcohols, sulfoxides, ketones, ethers, esters, aliphatic halogens. Hydrocarbons and aromatic compounds.

  When applying the coating solution for the charge generation layer, for example, a coating method such as a dip coating method (a dip coating method), a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, or a blade coating method is used. be able to.

  The thickness of the charge generation layer is preferably 5 μm or less, and more preferably 0.1 to 2 μm.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and the like can be added to the charge generation layer as necessary. Further, in order to prevent the flow of electric charges (carriers) in the charge generation layer, the charge generation layer may contain an electron transport material (electron accepting material such as an acceptor).

  A charge transport layer is provided on the charge generation layer.

  Examples of the charge transport material used in the electrophotographic photoreceptor of the present invention include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triallylmethane compounds, and the like.

  The binder resin used for the charge transport layer of the electrophotographic photoreceptor of the present invention uses a polyarylate resin from the viewpoint of durability and the like. Commonly used binder resins for charge transport layers include, for example, acrylic resins, styrene resins, polyester resins, polycarbonate resins, polyarylate resins, polysulfone resins, polyphenylene oxide resins, epoxy resins, polyurethane resins, alkyd resins, unsaturated Resins etc. are mentioned, and these may be used as a mixture or copolymer in one or more kinds.

  Specific examples of preferable polyarylate resins include polyarylate resins containing a polymer having a structural unit represented by the following formula (1).

（式中、Ｒ_１１〜Ｒ_４４は水素原子、ハロゲン原子、置換されてもよいそれぞれアルキル基、アリール基またはアルケニル基を示し、ｎは０〜７の整数を示す）
また、別の好ましいポリアリレート樹脂の具体例として、下記式（２）で示される構成単位を有する重合体を含有するポリアリレート樹脂が挙げられる。

(Wherein R _{11 to} R ₄₄ represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkenyl group, each of which may be substituted, and n represents an integer of 0 to 7)
Moreover, the polyarylate resin containing the polymer which has a structural unit shown by following formula (2) as a specific example of another preferable polyarylate resin is mentioned.

（Ｒ^１１〜Ｒ^２８のうちは、それぞれ独立に水素、炭素数１〜４のアルキル基、アリール基、炭素数１〜３のアルコキシ基を示す。Ｘは、単結合、酸素原子、硫黄原子、または、下記式（３）で示される構造を有する２価の基を示す。

(In R ^{11 to} R ²⁸ , each independently represents hydrogen, an alkyl group having 1 to 4 carbon atoms, an aryl group, or an alkoxy group having 1 to 3 carbon atoms. X represents a single bond, an oxygen atom, a sulfur atom, Or the bivalent group which has a structure shown by following formula (3) is shown.

式（３）中、Ｒ^３１およびＲ^３２は、それぞれ独立に、水素原子、アルキル基、フッ化アルキル基、アルコキシ基、または、アリール基を示す、あるいは、Ｒ^３１とＲ^３２とが結合して形成されるシクロアルキリデン基、または、フルオレニリデン基を示す。）
電荷輸送層は、電荷輸送物質と結着樹脂を溶剤に溶解して得られる電荷輸送層用塗布液を塗布し、これを乾燥させることによって形成することができる。電荷輸送物質と結着樹脂との割合は、２：１〜１：２（質量比）の範囲が好ましい。

In formula (3), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group, or R ³¹ and R ³² are bonded to each other. A cycloalkylidene group or a fluorenylidene group to be formed is shown. )
The charge transport layer can be formed by applying a charge transport layer coating solution obtained by dissolving a charge transport material and a binder resin in a solvent and drying it. The ratio between the charge transport material and the binder resin is preferably in the range of 2: 1 to 1: 2 (mass ratio).

  Solvents used in the charge transport layer coating solution include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, ethers such as dimethoxymethane and dimethoxyethane, aromatic hydrocarbons such as toluene and xylene, chlorobenzene and chloroform. In addition, a hydrocarbon substituted with a halogen atom such as carbon tetrachloride is used.

  When applying the coating solution for the charge transport layer, for example, a coating method such as a dip coating method (dip coating method), a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, a blade coating method, or the like is used. be able to.

  The thickness of the charge transport layer is preferably 5 to 40 μm, and more preferably 10 to 20 μm from the viewpoint of charging uniformity.

  In addition, an antioxidant, an ultraviolet absorber, a plasticizer, and the like can be added to the charge transport layer as necessary.

  Further, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. The protective layer can be formed by applying a protective layer coating solution obtained by dissolving the various binder resins described above in a solvent and drying the coating solution. The thickness of the protective layer is preferably 0.5 to 10 μm, and particularly preferably 1 to 5 μm.

  Next, FIG. 2 shows an example of a schematic configuration of an electrophotographic apparatus provided with the process cartridge of the present invention.

  In FIG. 2, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member, which is driven to rotate at a predetermined peripheral speed in the direction of the arrow about the shaft 2.

  The peripheral surface of the electrophotographic photosensitive member 1 that is driven to rotate is uniformly charged to a predetermined positive or negative potential by the charging unit 3, and then output from an exposure unit (not shown) such as slit exposure or laser beam scanning exposure. The exposure light (image exposure light) 4 is received. In this way, electrostatic latent images corresponding to the target image are sequentially formed on the peripheral surface of the electrophotographic photosensitive member 1. The voltage applied to the charging unit 3 may be only a DC voltage or a DC voltage on which an AC voltage is superimposed.

  The electrostatic latent image formed on the peripheral surface of the electrophotographic photosensitive member 1 is developed with toner of the developing unit 5 to become a toner image. Next, the toner image formed and supported on the peripheral surface of the electrophotographic photosensitive member 1 is transferred from the transfer material supply unit (not shown) by the transfer bias from the transfer unit (transfer roller) 6 to the electrophotographic photosensitive member 1 and the transfer unit. 6 (contact portion) is sequentially transferred onto a transfer material (paper or the like) P taken out and fed in synchronization with the rotation of the electrophotographic photosensitive member 1.

  The transfer material P that has received the transfer of the toner image is separated from the peripheral surface of the electrophotographic photosensitive member 1 and is introduced into the fixing means 8 to undergo image fixing, and is printed out of the apparatus as an image formed product (print, copy). Be out.

  The surface of the electrophotographic photosensitive member 1 after the transfer of the toner image is cleaned by a cleaning means (cleaning blade or the like) 7 to remove the developer (toner) remaining after transfer, and further from a pre-exposure means (not shown). After being subjected to the charge removal process by the pre-exposure light 11, it is repeatedly used for image formation. As shown in FIG. 2, when the charging unit 3 is a contact charging unit using a contact charging member such as a charging roller, the configuration is formed on, for example, a conductive support and on the outer periphery thereof. And a surface layer formed thereon (outer periphery). In addition, the surface roughness of the charging roller is preferably 5 μm or less from the viewpoint of suppressing image unevenness due to contamination of the charging roller due to adhesion of toner, toner external additives, and paper powder during continuous paper feeding.

  Among the components such as the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, the transfer unit 6 and the cleaning unit 7 described above, a plurality of components are housed in a container and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. In FIG. 2, the electrophotographic photosensitive member 1, the contact charging means 3, the developing means 5 and the cleaning means 7 are integrally supported to form a cartridge, and electrophotographic using a guide means 10 such as a rail of the electrophotographic apparatus main body. The process cartridge 9 is detachable from the apparatus main body.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to these. In the examples, “part” means “part by mass”.

1. 1. Preparation of coating solution 1-1. Coating liquid for conductive layer As conductive particles, 55.0 parts of TiO ₂ particles coated with oxygen-deficient SnO ₂ (powder resistivity 100 Ω · cm, SnO ₂ coverage (mass ratio) 40%), 36.5 parts of phenol resin (trade name: Pryofen J-325, manufactured by Dainippon Ink & Chemicals, Inc., resin solid content 60%) as a resin and 35.0 parts of methoxypropanol as a solvent are mixed. Then, the dispersion for conductive layer was prepared by dispersing for 3.0 hours with a sand mill using glass beads having a diameter of 1.0 mm.

  In this dispersion for conductive layer, 3.9 parts of silicone resin particles (trade name: Tospearl (registered trademark) 120, manufactured by GE Toshiba Silicone Co., Ltd., average particle size 2 μm) as a surface roughening agent, as a leveling agent Silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.) was added and stirred to prepare a coating solution for the conductive layer.

1-2. Intermediate layer coating solution N-methoxymethylated nylon (trade name: Toresin (registered trademark) EF-30T, Teikoku Chemical Industry Co., Ltd.) 4.5 parts and copolymer nylon resin (Amilan (registered trademark) CM8000, Toray Industries, Inc. 1.5 parts of (made by Co., Ltd.) was dissolved in a mixed solvent of 65.0 parts of methanol / 30.0 parts of n-butanol to prepare a coating solution for intermediate layer.

1-3. Coating solution for charge generation layer As charge generation material, Bragg angles (2θ ± 0.2 °) of CuKα characteristic X-ray diffraction are 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25. 10.0 parts of crystalline hydroxygallium phthalocyanine having strong peaks at 1 ° and 28.3 °, polyvinyl butyral as a binder resin (trade name: ESREC (registered trademark) BX-1, manufactured by Sekisui Chemical Co., Ltd.) ) And 250 parts of cyclohexanone as a solvent were mixed and dispersed for 1.0 hour in a sand mill using glass beads having a diameter of 1 mm. Next, 250 parts of ethyl acetate was added to prepare a charge generation layer coating solution.
1-4. Charge transport layer coating solution 10.0 parts of an amine compound having a structure represented by the following formula (4) as a charge transport material; and

結着樹脂として下記式（５）と下記式（６）で示される構成単位が７：３の割合で共重合したポリアリレート樹脂（Ｍｗ：６８０００）１０．０部を、

10.0 parts of polyarylate resin (Mw: 68000) in which the structural units represented by the following formula (5) and the following formula (6) are copolymerized at a ratio of 7: 3 as a binder resin,

ジメトキシメタン３０.０部／クロロベンゼン７０.０部の混合溶媒に溶解して、電荷輸送層用塗布液を調製した。なお、テレフタル酸塩化物とイソフタル酸塩化物の混合比はモル比で１：１とした。

A charge transport layer coating solution was prepared by dissolving in a mixed solvent of 30.0 parts of dimethoxymethane / 70.0 parts of chlorobenzene. The mixing ratio of terephthalic acid chloride and isophthalic acid chloride was 1: 1 by molar ratio.

2. Production of Photoreceptor An aluminum cylinder (JIS-A3003, aluminum alloy) having a length of 260.5 mm and a diameter of 30 mm manufactured by an extrusion / pulling-out process was used as a support for the photoreceptor.

  A conductive layer having a thickness of 15 μm is obtained by dip-coating the above-described coating solution for a conductive layer on the above-mentioned support in an environment of 23 ° C. and 60% RH, and drying and thermosetting it at 140 ° C. for 30 minutes. Formed.

  Next, an intermediate layer having a thickness of 0.60 μm was formed by dip-coating the conductive layer on the conductive layer using the above-described intermediate layer coating solution and drying it at 100 ° C. for 10 minutes.

  Subsequently, the charge generation layer having a film thickness of 0.16 μm was formed by dip-coating on the intermediate layer using the above-described coating solution for charge generation layer and drying it at 100 ° C. for 10 minutes.

  Finally, a charge transport layer having a thickness of 15 μm was formed by dip-coating on the charge generation layer using the above-described charge transport layer coating solution and drying at 120 ° C. for 30 minutes.

  In this manner, an electrophotographic photoreceptor having a charge transport layer as a surface layer was produced.

3. Evaluation 3-1. Potential Evaluation The produced electrophotographic photoreceptor was evaluated according to the following.

As an evaluation apparatus, a laser beam printer LBP-2510 manufactured by Canon Inc. (charging (primary charging): contact charging method, process speed: 94.2 mm / s), charging potential (dark part potential) of the electrophotographic photosensitive member is used. It was modified so that it could be adjusted.
The evaluation was performed in an environment at room temperature of 15 ° C. and humidity of 10%.

The exposure amount (image exposure amount) of the 780 nm laser light source of the evaluation apparatus was set so that the light amount on the surface of the electrophotographic photosensitive member was 0.3 μJ / cm ² .

  To measure the surface potential (dark part potential and bright part potential) of the electrophotographic photosensitive member, replace the jig and the developing device fixed so that the potential measuring probe is positioned 130 mm from the end of the electrophotographic photosensitive member. Then, it was carried out at the developing unit position.

  The dark part potential (VD) of the non-exposed part of the electrophotographic photosensitive member was set to −450 V, and the bright part potential (VL) that was light-attenuated from the dark part potential (VD) by irradiation with laser light was evaluated.

  In addition, using a laser beam printer LBP-2510 manufactured by Canon Inc., output 5000 images in an intermittent mode in which a character image with a printing rate of 2% is stopped once each time an image is output on letter paper. The bright part potential (VL) after outputting 5000 images was evaluated by the above-described evaluation apparatus. The results are shown in Table 1.

3-2. Scratch evaluation The film thickness at the start of evaluation of the electrophotographic photosensitive member and the film thickness after outputting 5000 images were measured to evaluate the amount of scraping from the initial stage. The film thickness was measured with a film thickness measuring device, Fischer MMS Eddy Current Probe EAW3.3, manufactured by Fischer Corporation. The results are shown in Table 1.

3-3. Image Evaluation The produced electrophotographic photoreceptor is mounted on a laser beam printer LBP-2510 manufactured by Canon Inc. in an environment with a room temperature of 15 ° C. and a humidity of 10% and a room temperature of 30 ° C. and a humidity of 80%. Then, evaluation of the initial image and the image after endurance of 5000 sheets was performed. The electrophotographic photosensitive member to be evaluated was mounted on a cyan process cartridge of LBP-2510 and evaluated at a cyan process cartridge station.

  Then, one solid white image was output for image evaluation at the start of evaluation and at the end of 5000 sheets. If there is no occurrence of fog or spots, nothing is stated. The results are shown in Table 1.

  An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the following points were changed in Example 1. The results are shown in Table 1.

The conductive particles of the conductive layer were changed to 55.0 parts of TiO ₂ particles coated with oxygen-deficient SnO ₂ (powder resistivity 800 Ω · cm, SnO ₂ coverage (mass ratio) 25%). The average particle diameter of the TiO ₂ particles coated with this oxygen-deficient SnO ₂ was 0.20 μm.

  An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the following points were changed in Example 1. The results are shown in Table 1.

The conductive particles of the conductive layer were changed to 55.0 parts of TiO ₂ particles coated with oxygen-deficient SnO ₂ (powder resistivity 30 Ω · cm, SnO ₂ coverage (mass ratio) 65%). The average particle diameter of the TiO ₂ particles coated with this oxygen-deficient SnO ₂ was 0.57 μm.

In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the film thickness of the conductive layer was changed to 10 μm. The results are shown in Table 1.

In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the film thickness of the conductive layer was changed to 25 μm. The results are shown in Table 1.

  An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the following points were changed in Example 1. The results are shown in Table 1.

  6.0 parts of an amine compound having a structure represented by the following formula (7), 2.0 parts of an amine compound having a structure represented by the formula (4) as a charge transport material for the charge transport layer, and

電荷輸送層の結着樹脂として、下記式（８）で示されるポリアリレート樹脂（Ｍｗ：１３００００）１０．０部を用いた。

As the binder resin for the charge transport layer, 10.0 parts of polyarylate resin (Mw: 130000) represented by the following formula (8) was used.

  An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the following points were changed in Example 1. The results are shown in Table 1.

  As the charge transport material for the charge transport layer, 1.0 part of an amine compound having a structure represented by the following formula (9) and 9.0 parts of an amine compound having a structure represented by the formula (4) were used.

  An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the following points were changed in Example 1. The results are shown in the table.

  As the charge transport material of the charge transport layer, 5.0 parts of an amine compound having a structure represented by the following formula (10) and 5.0 parts of an amine compound having a structure represented by the formula (4) were used.

  In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the thickness of the charge transport layer was changed to 8 μm. The results are shown in Table 1.

In Example 1, an electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the thickness of the charge transport layer was changed to 25 μm. The results are shown in Table 1.

(Comparative Example 1)
An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the following points were changed in Example 1. The results are shown in Table 1.
The conductive particles of the conductive layer were changed to 55.0 parts of TiO ₂ particles coated with oxygen-deficient SnO ₂ (powder resistivity 0.8 Ω · cm, SnO ₂ coverage (mass ratio) 70%). . The average particle diameter of the TiO ₂ particles coated with the oxygen-deficient SnO ₂ was 0.65 μm.

(Comparative Example 2)
An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the following points were changed in Example 1. The results are shown in Table 1.

The conductive particles of the conductive layer were changed to 55.0 parts of TiO ₂ particles coated with oxygen-deficient SnO ₂ (powder resistivity 1200 Ω · cm, SnO ₂ coverage (mass ratio) 20%). The average particle diameter of the barium sulfate particles coated with the oxygen-deficient SnO ₂ was 0.19 μm.

(Comparative Example 3)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the film thickness of the conductive layer was changed to 5 μm. The results are shown in Table 1.

(Comparative Example 4)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the film thickness of the conductive layer was changed to 30 μm. The results are shown in Table 1.

(Comparative Example 5)
An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the following points were changed in Example 1. The results are shown in Table 1.

TiO ₂ particles coated with 10% by mass of antimony oxide-doped SnO ₂ (powder resistivity 15 Ω · cm, SnO ₂ coverage (mass ratio) 40%) 55.0 Changed to the department. The average particle diameter of the barium sulfate particles coated with this oxygen-deficient SnO ₂ was 0.36 μm.

(Comparative Example 6)
In Example 9, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 9 except that the following points were changed. The results are shown in Table 1.

  As a binder resin for the charge transport layer, 10.0 parts of polycarbonate resin (trade name: Z050, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was used.

(Comparative Example 7)
In Comparative Example 6, an electrophotographic photoreceptor was prepared and evaluated in the same manner as Comparative Example 6 except that the thickness of the charge transport layer was changed to 25 μm. The results are shown in Table 1.

注１）Ｌ／Ｌ：室温１５℃、湿度１０％の環境下
注２）Ｈ／Ｈ：室温３０℃、湿度８０％の環境下

Note 1) L / L: Room temperature 15 ° C, humidity 10% Note 2) H / H: Room temperature 30 ° C, humidity 80%

An example of the layer structure of the electrophotographic photosensitive member of the present invention will be shown. 1 shows an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Support body 102 Conductive layer 103 Intermediate layer 1041 Charge generation layer 1042 Charge transport layer 105 Protective layer 1 Electrophotographic photosensitive member 2 Axis 3 Charging means (primary charging means)
4 exposure light (image exposure light)
5 Developing means 6 Transfer means (transfer roller)
7 Cleaning means (cleaning blade)
8 Fixing means 9 Process cartridge 10 Guide means 11 Pre-exposure light P Transfer material (paper, etc.)

Claims (3)

An electrophotographic photoreceptor having a conductive layer, an intermediate layer, a charge generation layer, and a charge transport layer in this order on a support, wherein the conductive layer contains a binder resin and conductive particles.
The conductive particles are TiO ₂ particles coated with oxygen-deficient SnO ₂ , the conductive particles have an average particle size of 0.20 μm to 0.60 μm, and the conductive layer has a thickness of 10 μm to 25 μm. An electrophotographic photoreceptor, wherein the charge transport layer contains a polyarylate resin.   The electrophotographic photosensitive member according to claim 1, a charging unit for charging the surface of the electrophotographic photosensitive member, and an electrostatic latent image on the surface of the electrophotographic photosensitive member is developed with toner to form a toner image. Developing means, transfer means for transferring the toner image on the surface of the electrophotographic photosensitive member to a transfer material, and cleaning means for cleaning the toner remaining on the surface of the electrophotographic photosensitive member after transfer. A process cartridge which integrally supports at least one means selected from a group and is detachable from an electrophotographic apparatus main body.   The electrophotographic photosensitive member according to claim 1, a charging unit for charging the surface of the electrophotographic photosensitive member, and an electrostatic latent image is formed on the surface of the electrophotographic photosensitive member charged by the charging unit by exposure. An exposure means for developing, an electrostatic latent image formed on the surface of the electrophotographic photosensitive member formed by the exposure means with toner to form a toner image, and formed by the development means An electrophotographic apparatus comprising transfer means for transferring a toner image on the surface of the electrophotographic photosensitive member to a transfer material.

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