JP2007334336A - Electrographic photoreceptor, image forming apparatus, and electrophotographic cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrographic photoreceptor capable of exhibiting electrical properties of high sensitivity and a low residual potential under various environments, and is capable of forming a high definition image. <P>SOLUTION: An electrographic photoreceptor has an underlying layer, which is formed on a conductive support and contains metal oxide particles and binder resin, and a photosensitive layer formed on the underlaying layer, and the underlying layer is so formed such that the volume average particle diameter, measured by a dynamic light-scattering method, of the metal oxide particle in a solution dispersed in a solvent including methanol and 1-propanol mixed with a weight ratio of 7:3 is 0.1 μm or smaller, and the cumulative 90% grain diameter is set to 0.3 μm or smaller, as well as, the photosensitive layer includes a specified arylamine compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member having an undercoat layer, an image forming apparatus using the same, and an electrophotographic cartridge.

In recent years, electrophotographic technology has been widely used and applied not only in the field of copying machines but also in the field of various printers because of its immediacy and high-quality images. Electrophotographic photoreceptors (hereinafter referred to simply as “photoreceptors”), which are the core of electrophotographic technology, have advantages such as non-pollution and easy manufacturing compared to inorganic photoconductive materials as photoconductive materials. An organic photoconductor using an organic photoconductive material having the above has been developed.
Usually, the organic photoreceptor is formed by forming a photosensitive layer on a conductive support. As a type of the photoreceptor, a so-called single-layer photoreceptor having a single-layer photosensitive layer (single-layer photosensitive layer) in which a photoconductive material is dissolved or dispersed in a binder resin; a charge containing a charge generating substance A so-called laminated photoreceptor having a photosensitive layer (laminated photosensitive layer) composed of a plurality of layers formed by laminating a generation layer and a charge transporting layer containing a charge transporting substance is known.

In an organic photoreceptor, various defects may be seen in an image formed using the photoreceptor due to changes in the usage environment of the photoreceptor or changes in electrical characteristics due to repeated use. One technique for improving this is to provide an undercoat layer having a binder resin and titanium oxide particles between a conductive substrate and a photosensitive layer in order to stably form a good image. (For example, refer to Patent Document 1).
The layer of the organic photoreceptor is usually formed by applying and drying a coating solution in which a material is dissolved or dispersed in various solvents because of its high productivity. At this time, in the undercoat layer containing the titanium oxide particles and the binder resin, since the titanium oxide particles and the binder resin exist in an incompatible state in the undercoat layer, the undercoat layer forming coating solution is The coating liquid is formed by dispersing titanium oxide particles.

  Conventionally, such a coating liquid is produced by wet-dispersing titanium oxide particles in an organic solvent with a known mechanical grinding device such as a ball mill, a sand grind mill, a planetary mill, or a roll mill for a long time. It was common (see, for example, Patent Document 1). When the titanium oxide particles in the coating solution for forming the undercoat layer are dispersed using a dispersion medium, the material of the dispersion medium is made of titania or zirconia, so that an electron having excellent charge exposure repeatability even under low temperature and low humidity conditions. It is disclosed that a photographic photoreceptor can be provided (see, for example, Patent Document 2).

  In addition, in organic photoreceptors, for example, hydrazone compounds, triphenylamine compounds, benzidine compounds, stilbene compounds, butadiene compounds, and the like are known as hole transport materials that are charge transport materials. As a transport material, for example, a diphenoquinone compound is known.

The charge transport material is selected in consideration of characteristics required for the photoreceptor. The characteristics required of the photoreceptor include, for example, (1) high chargeability due to corona discharge in a dark place, (2) little attenuation of charge charged by corona discharge in a dark place, (3 ) Charge dissipates rapidly by light irradiation, (4) Residual charge after light irradiation is small, (5) Residual potential increase and initial potential decrease little during repeated use, (6) Temperature and For example, there is little change in electrophotographic characteristics due to environmental changes such as humidity.
To date, various charge transport materials including hydrazone compounds have been proposed for the purpose of improving such characteristics (see, for example, Patent Documents 3 to 8).

Japanese Patent Laid-Open No. 11-202519 Japanese Patent Laid-Open No. 6-273963 Japanese Patent Publication No.55-42380 Japanese Patent Publication No.58-32372 JP 61-295558 A JP 58-198043 A Japanese Patent Publication No. 5-42661 Japanese Patent Publication No. 7-21646

  With recent downsizing, cost reduction, and speedup of image forming apparatuses, a heater for keeping the temperature of the photoreceptor constant is often not used. A photoreceptor used in such an image forming apparatus is required to maintain high responsiveness in any environment in order to maintain high image quality (particularly in a color machine).

  The various charge transport materials described above are useful as hole transport agents for electrophotographic photoreceptors, particularly when a hole transport agent having a stilbene skeleton is used in the photosensitive layer of an electrophotographic photoreceptor. Gives a photoreceptor excellent in responsiveness. Naturally, when a hole transporting agent having a stilbene skeleton is used in the photosensitive layer of the electrophotographic photosensitive member, image deterioration due to poor responsiveness at low temperatures is reduced. Due to the improvement of image quality requirements, the requirements may not be fully satisfied.

  The present invention was devised in view of the above problems, and can provide an electrophotographic photosensitive member that can exhibit high-sensitivity and low-residual-potential electrical characteristics in various environments and can form high-quality images, and An object of the present invention is to provide an image forming apparatus and an electrophotographic cartridge using the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have paid attention to the combination of the undercoat layer and the charge transport material, the specific undercoat layer, the specific arylamine compound, particularly the stilbene structure. The present inventors have found that a photoconductor excellent in sensitivity, residual potential, and repetitive characteristics and excellent in image defects can be obtained when used in combination with an arylamine compound having the above.

（式（Ｉ）において、Ａｒ¹〜Ａｒ⁶はそれぞれ独立に置換基を有しても良い芳香族残基を表し、Ｘは置換基を有していてもよい有機残基を表し、Ｒ¹〜Ｒ⁴はそれぞれ独立に置換基を有しても良い不飽和基を表し、ｎ₁は１又は２を表し、ｎ₀及びｎ₂〜ｎ₆は０〜２の整数を表す。） That is, the gist of the present invention is an electrophotographic photoreceptor having an undercoat layer containing metal oxide particles and a binder resin on a conductive support, and a photosensitive layer formed on the undercoat layer. The volume average particle size of the undercoat layer measured by the dynamic light scattering method of the metal oxide particles in a liquid in which methanol and 1-propanol are mixed in a solvent mixed at a weight ratio of 7: 3 is 0. 1. An electrophotographic photosensitive member characterized by having a cumulative 90% particle diameter of 0.3 μm or less and a compound represented by the following formula (I) in the photosensitive layer: 1 μm or less (Claim 1).

(In the formula (I), Ar ^{1 to} Ar ⁶ each independently represents an aromatic residue which may have a substituent, X represents an organic residue which may have a substituent, R ¹ to R ⁴ also have independently substituent represents an unsaturated group, n ₁ is 1 or 2, n ₀ and n ₂ ~n ₆ represents an integer of 0 to 2.)

（式（ＩＩ）において、Ｒ⁵〜Ｒ⁹は、それぞれ独立に、水素原子、又は、置換基を有しても良いアルキル基もしくはアリール基を表し、ｎ₇は０〜５の整数を表す。） At this time, in the formula (I), it is preferable that Ar ^{1 to} Ar ⁶ are all benzene residues.
In the formula (I), R ^{1 to} R ⁴ are also preferably represented by the following formula (II) (Claim 3).

(In the formula (II), R ^{5 to} R ⁹ each independently represents a hydrogen atom or an alkyl group or an aryl group which may have a substituent, and n ₇ represents an integer of 0 to 5. )

  Another gist of the present invention is an image exposure for forming an electrostatic latent image by performing image exposure on the electrophotographic photosensitive member and the charging means for charging the electrophotographic photosensitive member. 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.

  Still another subject matter of the present invention is the above-described electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, and image exposure for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image. At least one of: developing means for developing the electrostatic latent image with toner; transfer means for transferring the toner to a transfer target; and cleaning means for collecting the toner adhering to the electrophotographic photosensitive member. The present invention resides in an electrophotographic cartridge (claim 5).

  According to the present invention, an electrophotographic photosensitive member capable of exhibiting high sensitivity and low residual potential electrical characteristics in various environments and capable of forming a high quality image, and an image forming apparatus and an electronic device using the same A photographic cartridge can be provided.

  Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and can be arbitrarily modified without departing from the spirit of the present invention. Can be implemented.

  The electrophotographic photosensitive member of the present invention is configured to have an undercoat layer containing metal oxide particles and a binder resin on a conductive support, and a photosensitive layer formed on the undercoat layer. Is. In the electrophotographic photoreceptor of the present invention, the undercoat layer includes a metal oxide particle having a predetermined particle size distribution, and the photosensitive layer contains a specific arylamine compound.

[I. Conductive support]
There are no particular restrictions on the conductive support, but for example, metallic materials such as aluminum, aluminum alloy, stainless steel, copper and nickel; conductive powders such as metal, carbon and tin oxide were mixed to impart conductivity. Resin material: Resin, glass, paper, or the like obtained by depositing or coating a conductive material such as aluminum, nickel, or ITO (indium tin oxide alloy) on its surface is mainly used.
As the form of the conductive support, for example, a drum shape, a sheet shape, a belt shape or the like is used. Further, a conductive material having an appropriate resistance value may be coated on a conductive support made of a metal material in order to control conductivity, surface properties, etc. or to cover defects.

Further, when a metal material such as an aluminum alloy is used as the conductive support, it may be used after anodizing. When the anodizing treatment is performed, it is desirable to perform a sealing treatment by a known method.
For example, an anodic oxidation film is formed by anodizing in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, boric acid, sulfamic acid, etc. Oxidation treatment gives better results. In the case of anodic oxidation in sulfuric acid, the sulfuric acid concentration is 100 to 300 g / L, the dissolved aluminum concentration is 2 to 15 g / L, the liquid temperature is 15 to 30 ° C., the electrolysis voltage is 10 to 20 V, and the current density is 0.5 to Although it is preferable to set within the range of ² A / dm ² , it is not limited to the above conditions.

  It is preferable to perform a sealing treatment on the anodic oxide film thus formed. The sealing treatment may be carried out by a known method. For example, it is immersed in an aqueous solution containing nickel fluoride as a main component, or immersed in an aqueous solution containing nickel acetate as a main component. It is preferable that high temperature sealing treatment is performed.

  The concentration of the nickel fluoride aqueous solution used in the case of the low-temperature sealing treatment can be appropriately selected, but more preferable results are obtained when it is used in the range of 3 to 6 g / L. In order to smoothly proceed with the sealing treatment, the treatment temperature is usually 25 ° C or higher, preferably 30 ° C or higher, and usually 40 ° C or lower, preferably 35 ° C or lower. Further, from the same viewpoint, the nickel fluoride aqueous solution pH is preferably 4.5 or more, preferably 5.5 or more, and usually 6.5 or less, preferably 6.0 or less. As the pH adjuster, for example, oxalic acid, boric acid, formic acid, acetic acid, sodium hydroxide, sodium acetate, aqueous ammonia and the like can be used. The treatment time is preferably in the range of 1 to 3 minutes per 1 μm film thickness. In order to further improve the physical properties of the film, for example, cobalt fluoride, cobalt acetate, nickel sulfate, a surfactant or the like may be contained in the nickel fluoride aqueous solution. Subsequently, it is washed with water and dried to finish the low temperature sealing treatment.

  On the other hand, as the sealing agent in the case of the high temperature sealing treatment, for example, an aqueous solution of metal salt such as nickel acetate, cobalt acetate, lead acetate, nickel acetate-cobalt and barium nitrate can be used. It is preferable to use an aqueous solution. The concentration in the case of using an aqueous nickel acetate solution is preferably 5 to 20 g / L. The treatment temperature is usually 80 ° C. or higher, preferably 90 ° C. or higher, and usually 100 ° C. or lower, preferably 98 ° C. or lower, and the pH of the nickel acetate aqueous solution is 5.0 to 6.0. It is preferable. Here, as a pH adjuster, ammonia water, sodium acetate, etc. can be used, for example. The treatment time is usually 10 minutes or longer, preferably 20 minutes or longer. In this case, in order to improve the physical properties of the film, for example, sodium acetate, organic carboxylic acid, anionic or nonionic surfactant may be contained in the nickel acetate aqueous solution. Furthermore, you may process by the high temperature water or high temperature steam which does not contain salt substantially. Subsequently, it is washed with water and dried to finish the high temperature sealing treatment.

  When the average thickness of the anodic oxide coating is thick, strong sealing conditions may be required due to high concentration of the sealing liquid and high temperature / long time treatment. In this case, productivity is deteriorated and surface defects such as stains, dirt, and dusting are likely to occur on the coating surface. From such a point, it is preferable that the average film thickness of the anodic oxide coating is usually 20 μm or less, particularly 7 μm or less.

  The surface of the conductive support may be smooth, or may be roughened by using a special cutting method or polishing. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the support. In order to reduce the cost, it is possible to use the drawing tube as it is without cutting. Especially when using non-cutting aluminum supports such as drawing, impact processing, ironing, etc., the process eliminates dirt, foreign matter, etc. on the surface, small scratches, etc., and a uniform and clean support can be obtained. Therefore, it is preferable.

[II. Undercoat layer]
The undercoat layer is a layer containing metal oxide particles and a binder resin. The undercoat layer may contain other components as long as the effects of the present invention are not significantly impaired.
The undercoat layer according to the present invention is provided between the conductive support and the photosensitive layer, improves the adhesion between the conductive support and the photosensitive layer, conceals dirt and scratches on the conductive support, impurities And at least functions such as prevention of carrier injection due to non-uniformity of surface properties, improvement of non-uniformity of electrical characteristics, prevention of lowering of surface potential due to repeated use, and prevention of local surface potential fluctuations that cause image quality defects It is a layer which has any one and is not essential for the expression of photoelectric characteristics.

[II-1. Metal oxide particles]
[II-1-1. Types of metal oxide particles]
As the metal oxide particles according to the present invention, any metal oxide particles that can be used for an electrophotographic photoreceptor can be used.
Specific examples of metal oxides forming the metal oxide particles include metal oxides containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide and iron oxide; calcium titanate And metal oxides containing a plurality of metal elements such as strontium titanate and barium titanate. Among these, metal oxide particles made of a metal oxide having a band gap of 2 to 4 eV are preferable. If the band gap is too small, carrier injection from the conductive support tends to occur, and image defects such as black spots and color spots are likely to occur. Moreover, if the band gap is too large, the charge transfer is hindered by the trapping of electrons, and the electrical characteristics may be deteriorated.

  As the metal oxide particles, only one type of particles may be used, or a plurality of types of particles may be used in any combination and ratio. In addition, the metal oxide particles may be formed from only one kind of metal oxide, or may be formed by using two or more kinds of metal oxides in any combination and ratio. good.

  Among the metal oxides forming the metal oxide particles, titanium oxide, aluminum oxide, silicon oxide and zinc oxide are preferable, titanium oxide and aluminum oxide are more preferable, and titanium oxide is particularly preferable.

  The crystal form of the metal oxide particles is arbitrary as long as the effects of the present invention are not significantly impaired. For example, the crystal form of metal oxide particles using titanium oxide as a metal oxide (that is, titanium oxide particles) is not limited, and any of rutile, anatase, brookite, and amorphous can be used. Further, the crystal form of the titanium oxide particles may include those in a plurality of crystal states from those having different crystal states.

Further, the surface of the metal oxide particles may be subjected to various surface treatments. For example, treatment with a treating agent such as 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 organic silicon compound may be performed.
In particular, when titanium oxide particles are used as the metal oxide particles, the surface treatment is preferably performed with an organosilicon compound. Examples of the organosilicon compound include silicone oils such as dimethylpolysiloxane and methylhydrogenpolysiloxane; organosilanes such as methyldimethoxysilane and diphenyldimethoxysilane; silazanes such as hexamethyldisilazane; vinyltrimethoxysilane and γ-mercaptopropyl. Examples thereof include silane coupling agents such as trimethoxysilane and γ-aminopropyltriethoxysilane.

The metal oxide particles are particularly preferably treated with a silane treating agent represented by the structure of the following formula (i). This silane treatment agent is a good treatment agent with good reactivity with metal oxide particles.

In the formula (i), R ^a1 and R ^a2 each independently represents an alkyl group. The carbon number of R ^a1 and R ^a2 is not limited, but is usually 1 or more, and usually 18 or less, preferably 10 or less, more preferably 6 or less. Examples of suitable ones among R ^a1 and R ^a2 include a methyl group and an ethyl group.
In the formula (i), R ^a3 represents an alkyl group or an alkoxy group. The carbon number of R ^a3 is not limited, but is usually 1 or more and usually 18 or less, preferably 10 or less, more preferably 6 or less. Examples of suitable R ^a3 include a methyl group, an ethyl group, a methoxy group, and an ethoxy group.
When the number of carbon atoms of R ^{a1 to} R ^a3 is too large, the reactivity with the metal oxide particles is lowered, or the dispersion stability in the coating solution for forming the undercoat layer of the metal oxide particles after the treatment is lowered. there is a possibility.

  In addition, the outermost surface of these surface-treated metal oxide particles is usually treated with the treatment agent as described above. At this time, the surface treatment described above may be performed only by one surface treatment, or two or more surface treatments may be performed in any combination. For example, before the surface treatment with the silane treating agent represented by the above formula (i), it may be treated with a treating agent such as aluminum oxide, silicon oxide or zirconium oxide. Moreover, you may use together the metal oxide particle which performed different surface treatment in arbitrary combinations and a ratio.

Among the metal oxide particles according to the present invention, examples of those that have been commercialized will be given. However, the metal oxide particles according to the present invention are not limited to the products exemplified below.
Examples of specific products of titanium oxide particles include ultrafine titanium oxide “TTO-55 (N)” that has not been surface-treated; ultrafine titanium oxide “TTO-55 (A) coated with Al ₂ O _3. ) ”,“ TTO-55 (B) ”; ultrafine titanium oxide surface treated with stearic acid“ TTO-55 (C) ”; ultrafine titanium oxide surface treated with Al ₂ O ₃ and organosiloxane “TTO-55 (S)”; high purity titanium oxide “CR-EL”; sulfuric acid method titanium oxide “R-550”, “R-580”, “R-630”, “R-670”, “R-” 680 "," R-780 "," A-100 "," A-220 "," W-10 "; chlorinated titanium oxides" CR-50 "," CR-58 "," CR-60 "," CR-60-2 "," CR-67 "; conductive titanium oxide" SN " -100P "," SN-100D "," ET-300W "; (above, manufactured by Ishihara Sangyo Co., Ltd.). In addition, titanium oxides such as “R-60”, “A-110”, and “A-150”; and “SR-1”, “R-GL”, “R—” coated with Al ₂ O ₃ 5N "," R-5N-2 "," R-52N "," RK-1 "," a-SP "; subjected to SiO _2, Al ₂ O ₃ coating" R-GX "," R-7E _{"; ZnO, SiO 2, Al 2} O 3 coating was subjected to a" R-650 "; subjected to ZrO _2, Al ₂ O ₃ coating" R-61N "; (or, manufactured by Sakai Chemical Industry Co., Ltd.) also like Can be mentioned. Furthermore, surface-treated with SiO _2, Al ₂ O ₃ "TR-700"; ZnO, surface-treated with SiO _2, Al ₂ O ₃ "TR-840", another "TA-500", "TA Surface-untreated titanium oxide such as “-100”, “TA-200”, “TA-300”; “TA-400” (manufactured by Fuji Titanium Industry Co., Ltd.); surface-treated with Al ₂ O ₃ ; surface not subjected to treatment, "MT-150 W", "MT-500B"; surface-treated with SiO _2, Al ₂ O ₃ "MT-100SA", "MT-500SA"; SiO _2, Al ₂ O ₃ and organosiloxane Examples thereof include “MT-100SAS” and “MT-500SAS” (manufactured by Teika Co., Ltd.) surface-treated with siloxane.

Examples of specific products of aluminum oxide particles include “Aluminium Oxide C” (manufactured by Nippon Aerosil Co., Ltd.).
Furthermore, examples of specific products of silicon oxide particles include “200CF”, “R972” (manufactured by Nippon Aerosil Co., Ltd.), “KEP-30” (manufactured by Nippon Shokubai Co., Ltd.), and the like.
Moreover, "SN-100P" (made by Ishihara Sangyo Co., Ltd.) etc. are mentioned as an example of the specific goods of a tin oxide particle.
Furthermore, “MZ-305S” (manufactured by Teika Co., Ltd.) and the like are listed as examples of specific products of zinc oxide particles.

[II-1-2. Physical properties of metal oxide particles]
About the metal oxide particle which concerns on this invention, the following requirements are materialized regarding the particle size distribution. That is, the metal oxidation in a liquid (hereinafter referred to as “dispersion for measuring the undercoat layer” as appropriate) in which the undercoat layer according to the present invention is dispersed in a solvent in which methanol and 1-propanol are mixed at a weight ratio of 7: 3. The volume average particle diameter measured by the dynamic light scattering method of physical particles is 0.1 μm or less, and the cumulative 90% particle diameter is 0.3 μm or less.
Hereinafter, this point will be described in detail.

[Volume average particle diameter of metal oxide particles]
The metal oxide particles according to the present invention have a volume average particle size of 0.1 μm or less, preferably 95 nm or less, more preferably 90 nm or less, measured by a dynamic light scattering method in the undercoat layer measurement dispersion. is there. Moreover, although there is no restriction | limiting in the minimum of the said volume average particle diameter, Usually, it is 20 nm or more. By satisfying the above range, the electrophotographic photosensitive member of the present invention has stable exposure-charging repetition characteristics under low temperature and low humidity, and suppresses occurrence of image defects such as black spots and color spots in the obtained image. it can.

[About cumulative 90% particle size of metal oxide particles]
The metal oxide particles according to the present invention have a cumulative 90% particle diameter measured by a dynamic light scattering method in a dispersion for measuring an undercoat layer of 0.3 μm or less, preferably 0.25 μm or less, more preferably 0.2 μm or less. The lower limit of the cumulative 90% particle size is not limited, but is usually 10 nm or more, preferably 20 nm or more, more preferably 50 nm or more. In a conventional electrophotographic photoreceptor, a metal oxide particle aggregate that is large enough to penetrate the front and back of the undercoat layer is formed by aggregation of metal oxide particles in the undercoat layer, and the large metal oxide particles The agglomerates could cause defects during image formation. Further, when a contact type is used as the charging means, when the photosensitive layer is charged, the charge moves from the photosensitive layer to the conductive support through the metal oxide particles, and the charging is appropriately performed. There was also a possibility that it could not be done. However, in the electrophotographic photosensitive member of the present invention, since the cumulative 90% particle diameter is very small, there are very few large metal oxide particles that cause defects as described above. As a result, in the electrophotographic photosensitive member of the present invention, it is possible to suppress the occurrence of defects and the inability to appropriately charge, and high-quality image formation is possible.

[Measurement method of volume average particle size and cumulative 90% particle size]
The volume average particle size and the cumulative 90% particle size of the metal oxide particles according to the present invention are a mixed solvent in which an undercoat layer is mixed with methanol and 1-propanol at a weight ratio of 7: 3 (this is a particle size). Prepare a dispersion for measuring the undercoat layer by dispersing in a dispersion medium for measurement), and measure the particle size distribution of the metal oxide particles in the dispersion for measuring the undercoat layer by the dynamic light scattering method. Is a value obtained by

  In the dynamic light scattering method, the speed of Brownian motion of finely dispersed particles is detected, and the particle size distribution is detected by irradiating the particles with laser light and detecting light scattering (Doppler shift) with different phases according to the speed. Is what you want. The values of the volume average particle diameter and the cumulative 90% particle diameter of the metal oxide particles in the undercoat layer measurement dispersion are obtained when the metal oxide particles are stably dispersed in the undercoat layer measurement dispersion. It is a value and does not mean the particle size in the undercoat layer after the undercoat layer is formed. In the actual measurement, the volume average particle size and the cumulative 90% particle size are specifically expressed by a dynamic light scattering particle size analyzer (MICROTRAC UPA model: 9340-UPA, manufactured by Nikkiso Co., Ltd., hereinafter referred to as UPA). ) And the following settings. A specific measurement operation is performed based on the instruction manual of the particle size analyzer (manufactured by Nikkiso Co., Ltd., Document No. T15-490A00, revised No. E).

・ Setting of dynamic light scattering system particle size analyzer Upper limit of measurement: 5.9978 μm
Measurement lower limit: 0.0035 μm
Number of channels: 44
Measurement time: 300 sec.
Particle permeability: Absorption Particle refractive index: N / A (not applicable)
Particle shape: non-spherical density: 4.20 g / cm ³ (*)
Dispersion medium type: Methanol / 1-propanol = 7/3
Dispersion medium refractive index: 1.35
(*) The value of density is for titanium dioxide particles, and for other particles, the values described in the instruction manual are used.

The amount of the mixed solvent of methanol and 1-propanol (weight ratio: methanol / 1-propanol = 7/3; refractive index = 1.35) used as the dispersion medium is the dispersion for measuring the undercoat layer as the sample. The amount of the sample concentration index (SIGNAL LEVEL) of the liquid is 0.6 to 0.8.
The measurement of particle size by dynamic light scattering is performed at 25 ° C.

  The volume average particle diameter and cumulative 90% particle diameter of the metal oxide particles according to the present invention are 100% of the total volume of the metal oxide particles when the particle size distribution is measured by the dynamic light scattering method as described above. When the cumulative curve of the volume particle size distribution is obtained from the small particle size side by the dynamic light scattering method described above, the particle diameter at the point where the cumulative curve becomes 50% is the volume average particle diameter (center diameter: median diameter). And the particle diameter at the point where the cumulative curve is 90% is defined as the cumulative 90% particle diameter.

[Other physical properties]
There is no restriction | limiting in the average primary particle diameter of the metal oxide particle concerning this invention, and it is arbitrary unless the effect of this invention is impaired remarkably. However, the average primary particle diameter of the metal oxide particles according to the present invention is usually 1 nm or more, preferably 5 nm or more, and usually 100 nm or less, preferably 70 nm or less, more preferably 50 nm or less.
The average primary particle diameter can be obtained by an arithmetic average value of particle diameters directly observed by a transmission electron microscope (hereinafter referred to as “TEM” as appropriate).

Moreover, there is no restriction | limiting in the refractive index of the metal oxide particle which concerns on this invention, What kind of thing can be used if it can be used for an electrophotographic photoreceptor. The refractive index of the metal oxide particles according to the present invention is usually 1.3 or more, preferably 1.4 or more, and usually 3.0 or less, preferably 2.9 or less, more preferably 2.8 or less. .
In addition, the literature value described in various publications can be used for the refractive index of a metal oxide particle. For example, according to the filler utilization dictionary (Filler Study Group, Taiseisha, 1994), it is as shown in Table 1 below.

  In the undercoat layer of the present invention, the use ratio of the metal oxide particles and the binder resin is arbitrary as long as the effects of the present invention are not significantly impaired. However, in the undercoat layer of the present invention, the metal oxide particles are usually 0.5 parts by weight or more, preferably 0.7 parts by weight or more, more preferably 1.0 parts by weight with respect to 1 part by weight of the binder resin. More than 4 parts by weight, preferably less than 3.8 parts by weight, more preferably less than 3.5 parts by weight. If the amount of the metal oxide particles is too small relative to the binder resin, the electrical characteristics of the obtained electrophotographic photoreceptor may deteriorate, particularly the residual potential may increase, and if too large, the electrophotographic photoreceptor is formed using the electrophotographic photoreceptor. There is a possibility that image defects such as black spots and color spots increase in the image.

[II-2. Binder resin]
Any binder resin can be used as the binder resin used in the undercoat layer of the present invention as long as the effects of the present invention are not significantly impaired. Usually, it is soluble in a solvent such as an organic solvent, and the undercoat layer is insoluble or low in solubility in a solvent such as an organic solvent used in a coating solution for forming a photosensitive layer. Use one that does not mix.

  As such a binder resin, for example, a resin such as phenoxy, epoxy, polyvinyl pyrrolidone, polyvinyl alcohol, casein, polyacrylic acid, cellulose, gelatin, starch, polyurethane, polyimide, polyamide or the like is cured alone or with a curing agent. Can be used in Of these, polyamide resins such as alcohol-soluble copolymerized polyamides and modified polyamides are preferable because they exhibit good dispersibility and coating properties.

  As the polyamide resin, for example, so-called copolymer nylon obtained by copolymerizing 6-nylon, 66-nylon, 610-nylon, 11-nylon, 12-nylon, etc .; N-alkoxymethyl-modified nylon, N-alkoxyethyl-modified Examples thereof include alcohol-soluble nylon resins such as a type in which nylon is chemically modified, such as nylon. Specific products include, for example, “CM4000”, “CM8000” (manufactured by Toray), “F-30K”, “MF-30”, “EF-30T” (manufactured by Nagase Chemtech Co., Ltd.), and the like. .

Among these polyamide resins, a copolymerized polyamide resin containing a diamine component corresponding to a diamine represented by the following formula (ii) (hereinafter, appropriately referred to as “diamine component corresponding to formula (ii)”) as a constituent component is particularly preferable. Used.

In the formula (ii), R ^{a4 to} R ^a7 represent a hydrogen atom or an organic substituent. m and n each independently represents an integer of 0 to 4. In addition, when there are a plurality of substituents, these substituents may be the same as or different from each other.

When the example of a suitable thing as an organic substituent represented by R ^{< a4>} -R ^<a7> is given, the hydrocarbon group which may contain the hetero atom is mentioned. Among these, preferred are, for example, alkyl groups such as methyl group, ethyl group, n-propyl group and isopropyl group; alkoxy groups such as methoxy group, ethoxy group, n-propoxy group and isopropoxy group; phenyl group and naphthyl group And aryl groups such as an anthryl group and a pyrenyl group, more preferably an alkyl group or an alkoxy group. Particularly preferred are a methyl group and an ethyl group.
The number of carbon atoms of the organic substituent represented by R ^{a4 to} R ^a7 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 20 or less, preferably 18 or less, more preferably 12 or less, 1 or more. If the number of carbon atoms is too large, the solubility in the solvent deteriorates when preparing the coating solution for forming the undercoat layer, and even if it can be dissolved, the storage stability as the coating solution for forming the undercoat layer deteriorates. Show a tendency to

  The copolymerized polyamide resin containing a diamine component corresponding to the formula (ii) as a constituent component constitutes a constituent component other than the diamine component corresponding to the formula (ii) (hereinafter, simply referred to as “other polyamide constituent component”). It may be included as a unit. Examples of other polyamide constituents include lactams such as γ-butyrolactam, ε-caprolactam, lauryllactam; 1,4-butanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,20-eicosanedicarboxylic acid, and the like. Dicarboxylic acids; diamines such as 1,4-butanediamine, 1,6-hexamethylenediamine, 1,8-octamethylenediamine, 1,12-dodecanediamine; piperazine and the like. At this time, examples of the copolymerized polyamide resin include those obtained by copolymerizing the constituent components into, for example, binary, ternary, and quaternary.

  When the copolymerized polyamide resin containing a diamine component corresponding to the formula (ii) as a constituent component contains other polyamide constituent components as constituent units, the proportion of the diamine component corresponding to the formula (ii) in all the constituent components Although there is no limitation, it is usually 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more, and usually 40 mol% or less, preferably 30 mol% or less. If the amount of the diamine component corresponding to the formula (ii) is too large, the stability of the coating solution for forming the undercoat layer may be deteriorated. May be less stable against environmental changes.

  Specific examples of the copolymerized polyamide resin are shown below. However, in specific examples, the copolymerization ratio represents the charge ratio (molar ratio) of the monomer.

There is no restriction | limiting in particular in the manufacturing method of said copolyamide, The normal polycondensation method of polyamide is applied suitably. For example, a polycondensation method such as a melt polymerization method, a solution polymerization method, and an interfacial polymerization method can be appropriately applied. In the polymerization, for example, a monobasic acid such as acetic acid or benzoic acid; a monoacid base such as hexylamine or aniline may be contained in the polymerization system as a molecular weight regulator.
In addition, binder resin may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Moreover, there is no restriction | limiting also in the number average molecular weight of binder resin which concerns on this invention. For example, when a copolymerized polyamide is used as the binder resin, the number average molecular weight of the copolymerized polyamide is usually 10,000 or more, preferably 15000 or more, and usually 50000 or less, preferably 35000 or less. If the number average molecular weight is too small or too large, it is difficult to maintain the uniformity of the undercoat layer.

[II-3. Other ingredients]
The undercoat layer of the present invention may contain components other than the metal oxide particles and the binder resin described above as long as the effects of the present invention are not significantly impaired. For example, the undercoat layer may contain additives as other components.

  Examples of additives include sodium phosphite, sodium hypophosphite, phosphorous acid, heat stabilizers typified by hypophosphorous acid and hindered phenol, other polymerization additives, and antioxidants. It is done. In addition, an additive may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

[II-4. Physical properties of undercoat layer]
[Film thickness]
The thickness of the undercoat layer is arbitrary, but is usually 0.1 μm or more, preferably 0.3 μm or more, more preferably 0 from the viewpoint of improving the photoreceptor characteristics and coating properties of the electrophotographic photoreceptor of the present invention. It is preferably in the range of 5 μm or more, usually 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less.

〔Surface roughness〕
The surface layer of the undercoat layer according to the present invention is not limited in its surface shape, but is usually in-plane root mean square roughness (RMS), in-plane arithmetic average roughness (Ra), in-plane maximum roughness (P− V). These numerical values are numerical values obtained by extending the reference length of the root mean square height, arithmetic average height, and maximum height in the standard of JIS B 0601: 2001 to the reference plane, and the height on the reference plane. Using Z (x) which is the value of the direction, the in-plane root mean square roughness (RMS) is the root mean square of Z (x), and the in-plane arithmetic mean roughness (Ra) is Z (x) The average of the absolute values, the in-plane maximum roughness (P-V) represents the sum of the maximum value of the peak height of Z (x) and the maximum value of the valley depth, respectively.

The in-plane root mean square roughness (RMS) of the undercoat layer according to the present invention is usually in the range of 10 nm or more, preferably 20 nm or more, and usually 100 nm or less, preferably 50 nm or less. If the in-plane root mean square roughness (RMS) is too small, the adhesiveness with the upper layer may be deteriorated, and if it is too large, the uniformity of the coating film thickness of the upper layer may be deteriorated.
The in-plane arithmetic average roughness (Ra) of the undercoat layer according to the present invention is usually in the range of 10 nm or more and usually 50 nm or less. If the in-plane arithmetic average roughness (Ra) is too small, the adhesion with the upper layer may be deteriorated, and if it is too large, the uniformity of the coating thickness of the upper layer may be deteriorated.
The in-plane maximum roughness (P-V) of the undercoat layer according to the present invention is usually in the range of 100 nm or more, preferably 300 nm or more, and usually 1000 nm or less, preferably 800 nm or less. If the in-plane maximum roughness (PV) is too small, the adhesion with the upper layer may be deteriorated, and if it is too large, the uniformity of the coating thickness of the upper layer may be deteriorated.

  In addition, the numerical value of the index (RMS, Ra, PV) relating to the surface shape can be any surface as long as it is measured by a surface shape analyzer capable of measuring irregularities in the reference plane with high accuracy. Although it may be measured by a shape analyzer, it is preferably measured by a method of detecting irregularities on the sample surface by combining a high-accuracy phase shift detection method and interference fringe order counting using an optical interference microscope. More specifically, it is preferable to measure in the wave mode by the interference fringe addressing method using Micromap of Ryoka System Co., Ltd.

[Absorbance when used as dispersion]
The undercoat layer according to the present invention is dispersed in a solvent capable of dissolving the binder resin binding the undercoat layer to form a dispersion (hereinafter referred to as “absorbance measurement dispersion” as appropriate). Usually, the absorbance of the dispersion exhibits specific physical properties.

  The absorbance of the dispersion for absorbance measurement can be measured by a generally known spectrophotometer. Conditions such as cell size and sample concentration when measuring absorbance vary depending on physical properties such as the particle diameter and refractive index of the metal oxide particles to be used. Therefore, in general, in the wavelength region to be measured (in the present invention, (400 nm to 1000 nm), the sample concentration is appropriately adjusted so as not to exceed the measurement limit of the detector.

  A cell size (optical path length) for measurement is 10 mm. Any cell may be used as long as it is substantially transparent in the range of 400 nm to 1000 nm, but it is preferable to use a quartz cell, and in particular, a sample cell and a standard cell. It is preferable to use a matched cell that has a difference in transmittance characteristics within a specific range.

  When the undercoat layer according to the present invention is dispersed to obtain a dispersion for measuring absorbance, the binder resin that binds the undercoat layer is not substantially dissolved, and is formed on the undercoat layer. After dissolving and removing the layer on the undercoat layer with a solvent capable of dissolving the layer and the like, the binder resin for binding the undercoat layer is dissolved in the solvent to obtain a dispersion for absorbance measurement. At this time, as a solvent that can dissolve the undercoat layer, a solvent that does not have large light absorption in a wavelength region of 400 nm to 1000 nm may be used.

  Specific examples of the solvent that can dissolve the undercoat layer include alcohols such as methanol, ethanol, 1-propanol, and 2-propanol, and particularly methanol, ethanol, and 1-propanol. Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

In particular, an absorbance measurement dispersion in which the undercoat layer according to the present invention is dispersed in a solvent in which methanol and 1-propanol are mixed at a weight ratio of 7: 3, with respect to the light with a wavelength of 400 nm and the light with a wavelength of 1000 nm. The difference from the absorbance (absorbance difference) is as follows. That is, the absorbance difference is usually 0.3 (Abs) or less, preferably 0.2 (Abs) or less, when the refractive index of the metal oxide particles is 2.0 or more. Moreover, when the refractive index of a metal oxide particle is less than 2.0, it is 0.02 (Abs) or less normally, Preferably it is 0.01 (Abs) or less.
The absorbance value depends on the solid content concentration of the liquid to be measured. For this reason, when measuring the absorbance, it is preferable to disperse so that the concentration of the metal oxide particles in the dispersion is in the range of 0.003% to 0.0075% by weight.

[Regular reflectance of undercoat layer]
The regular reflectance of the undercoat layer according to the present invention usually shows a specific value in the present invention. The regular reflectance of the undercoat layer according to the present invention indicates the regular reflectance of the undercoat layer on the conductive support relative to the conductive support. Since the regular reflectance of the undercoat layer varies depending on the thickness of the undercoat layer, it is defined here as the reflectance when the thickness of the undercoat layer is 2 μm.

In the undercoat layer according to the present invention, when the refractive index of the metal oxide particles contained in the undercoat layer is 2.0 or more, the conductive support is converted when the undercoat layer is 2 μm. The ratio of the regular reflection for light with a wavelength of 480 nm of the undercoat layer to the regular reflection for light with a wavelength of 480 nm is usually 50% or more.
On the other hand, when the refractive index of the metal oxide particles contained in the undercoat layer is less than 2.0, it is converted to the case where the undercoat layer is 2 μm. The ratio of regular reflection to light with a wavelength of 400 nm of the undercoat layer relative to reflection is usually 50% or more.

  Here, even when the undercoat layer contains a plurality of types of metal oxide particles having a refractive index of 2.0 or more, or when the undercoat layer contains a plurality of types of metal oxide particles having a refractive index of less than 2.0, Those having regular reflection similar to the above are preferred. In the case where the undercoat layer simultaneously contains metal oxide particles having a refractive index of 2.0 or more and metal oxide particles having a refractive index of less than 2.0, the metal oxide having a refractive index of 2.0 or more As in the case of containing particles, the regular reflection of light of the undercoat layer with respect to light at a wavelength of 480 nm with respect to the light of the conductive support with respect to light of a wavelength of 480 nm as converted when the undercoat layer is 2 μm. The ratio is preferably in the above range (50% or more).

  As described above, the case where the film thickness of the undercoat layer is 2 μm has been described in detail. However, in the electrophotographic photoreceptor according to the present invention, the film thickness of the undercoat layer is not limited to 2 μm, and any film thickness can be obtained. It doesn't matter. When the thickness of the undercoat layer is other than 2 μm, it is equivalent to the electrophotographic photosensitive member using the undercoat layer forming coating solution (described later) used for forming the undercoat layer. An undercoat layer having a thickness of 2 μm can be applied and formed on the conductive support, and the regular reflectance can be measured for the undercoat layer. As another method, there is a method in which the regular reflectance of the undercoat layer of the electrophotographic photosensitive member is measured and converted when the film thickness is 2 μm.

Hereinafter, the conversion method will be described.
Assuming a thin layer of thickness dL perpendicular to the light when specific monochromatic light passes through the subbing layer, is specularly reflected on the conductive support and is again detected through the subbing layer To do.
The amount of decrease in light intensity −dI after passing through a thin layer having a thickness dL is considered to be proportional to the light intensity I before passing through the layer and the thickness dL of the layer. It can be written as follows (k is a constant):

-DI = kIdL (A)
The equation (A) is transformed as follows.
-DI / I = kdL (B)
When both sides of the formula (B) are integrated in the interval from I ₀ to I and from 0 to L, the following formula is obtained. Note that I ₀ represents the intensity of incident light.
log (I ₀ / I) = kL (C)

Equation (C) is the same as what is called Lambert's law in the solution system, and can also be applied to the measurement of reflectance in the present invention.
When formula (C) is transformed,
I = I ₀ exp (−kL) (D)
Thus, the behavior until the incident light reaches the surface of the conductive support is represented by the formula (D).

On the other hand, since the regular reflectance is a denominator of the reflected light of the incident light with respect to the conductive support, the reflectance R = I ₁ / I ₀ on the surface of the raw tube is considered. Here, I ₁ represents the intensity of the reflected light.
Then, the light that has reached the surface of the conductive support according to the formula (D) is regularly reflected after being multiplied by the reflectance R, and again passes through the optical path length L and exits to the surface of the undercoat layer. That is,
I = I ₀ exp (−kL) · R · exp (−kL) (E)
By substituting R = I ₁ / I ₀ and further transforming,
I / I ₁ = exp (−2 kL) (F)
Can be obtained. This is the value of the reflectivity for the undercoat layer relative to the reflectivity for the conductive support, which is defined as the regular reflectivity.

As described above, in the undercoat layer of 2 μm, the optical path length is 4 μm in a reciprocating manner, but the reflectivity T of the undercoat layer on any conductive support depends on the thickness L of the undercoat layer (this (Which sometimes becomes an optical path length 2L) and is expressed as T (L). From equation (F)
T (L) = I / I ₁ = exp (−2 kL) (G)
Is established.
On the other hand, since the value we want to know is T (2), substituting L = 2 into equation (G),
T (2) = I / I ₁ = exp (−4k) (H)
Then, when k is deleted by simultaneous equations (G) and (H),
T (2) = T (L) ^{2 / L} (I)
It becomes.

  That is, when the thickness of the undercoat layer is L (μm), the reflectance T (2) when the undercoat layer is 2 μm is obtained by measuring the reflectivity T (L) of the undercoat layer. Can be estimated with considerable accuracy. The value of the film thickness L of the undercoat layer can be measured by an arbitrary film thickness measuring device such as a roughness meter.

[III. Method for forming undercoat layer]
There is no restriction | limiting in the formation method of the undercoat layer based on this invention. However, usually, an undercoat layer-forming coating solution containing metal oxide particles and a binder resin is applied to the surface of the conductive support and dried to obtain an undercoat layer.

[III-1. Undercoat layer forming coating solution]
The undercoat layer forming coating solution according to the present invention is used to form an undercoat layer, and contains metal oxide particles and a binder resin. In general, the coating solution for forming the undercoat layer according to the present invention contains a solvent. Furthermore, the coating liquid for undercoat layer formation concerning this invention may contain the other component in the range which does not impair the effect of this invention remarkably.

[III-1-1. Metal oxide particles]
The metal oxide particles are the same as those described as the metal oxide particles contained in the undercoat layer.
However, regarding the particle size distribution of the metal oxide particles in the undercoat layer forming coating solution according to the present invention, the following requirements are usually satisfied. That is, the volume average particle size and the cumulative 90% particle size measured by the dynamic light scattering method of the metal oxide particles in the coating solution for forming the undercoat layer according to the present invention are respectively for the above-described undercoat layer measurement. This is the same as the volume average particle size and cumulative 90% particle size measured by the dynamic light scattering method of the metal oxide particles in the dispersion.

Therefore, in the coating liquid for forming the undercoat layer according to the present invention, the volume average particle diameter of the metal oxide particles is usually 0.1 μm or less (refer to [volume average particle diameter of metal oxide particles]). .
In the undercoat layer forming coating liquid according to the present invention, the metal oxide particles are preferably present as primary particles. However, there are few such cases, and in most cases, they are aggregated and exist as aggregate secondary particles, or both are mixed. Therefore, how the particle size distribution should be in that state is very important.

  Therefore, in the undercoat layer forming coating solution according to the present invention, by setting the volume average particle diameter of the metal oxide particles in the undercoat layer forming coating solution within the above range (0.1 μm or less). Then, precipitation and viscosity change in the coating solution for forming the undercoat layer were reduced. Thereby, as a result, the film thickness and surface property after forming the undercoat layer can be made uniform. On the other hand, when the volume average particle size of the metal oxide particles is too large (over 0.1 μm), conversely, precipitation and viscosity change in the coating solution for forming the undercoat layer increase, resulting in Since the film thickness and surface properties after the formation of the pulling layer become non-uniform, the quality of the upper layer (such as a charge generation layer) may be adversely affected.

In the undercoat layer forming coating solution according to the present invention, the cumulative 90% particle diameter of the metal oxide particles is usually 0.3 μm or less (refer to [Regarding the cumulative 90% particle diameter of metal oxide particles]). ).
This is desirable if the metal oxide particles according to the present invention are present as spherical primary particles in the undercoat layer forming coating solution. However, such metal oxide particles are not practically obtained. Even if the metal oxide particles are agglomerated, the inventors of the present invention should have a 90% cumulative particle diameter that is sufficiently small, that is, if the cumulative 90% particle diameter is specifically 0.3 μm or less. For example, it has been found that the coating solution for forming the undercoat layer has little gelation and viscosity change and can be stored for a long period of time, and as a result, the film thickness and surface properties after forming the undercoat layer are uniform. On the other hand, if the metal oxide particles in the coating solution for forming the undercoat layer are too large, gelation and viscosity change in the solution are large, resulting in non-uniform film thickness and surface properties after forming the undercoat layer. Therefore, the quality of the upper layer (such as a charge generation layer) may be adversely affected.

  The method for measuring the volume average particle size and the cumulative 90% particle size of the metal oxide particles in the undercoat layer forming coating solution is to measure the metal oxide particles in the undercoat layer measurement dispersion. Instead, the coating liquid for forming the undercoat layer is directly measured. The volume average particle diameter and cumulative 90% particle diameter of the metal oxide particles in the above-described undercoat layer measurement dispersion liquid are as follows. It is different from the measurement method. Except for the following points, the measurement method of the volume average particle diameter and cumulative 90% particle diameter of the metal oxide particles in the undercoat layer forming coating solution is the same as the metal oxidation in the undercoat layer measurement dispersion liquid. This is the same as the method for measuring the volume average particle size and cumulative 90% particle size of the product particles.

  That is, when measuring the volume average particle size and cumulative 90% particle size of the metal oxide particles in the coating solution for forming the undercoat layer, the type of dispersion medium is the solvent used in the coating solution for forming the undercoat layer. The dispersion medium refractive index is the refractive index of the solvent used in the coating solution for forming the undercoat layer. In addition, when the coating solution for forming the undercoat layer is too thick and the concentration is outside the measurable range of the measuring device, the coating solution for forming the undercoat layer is mixed with a mixed solvent of methanol and 1-propanol ( (Weight ratio: methanol / 1-propanol = 7/3; refractive index = 1.35) so that the concentration of the coating solution for forming the undercoat layer falls within a measurable range. For example, in the case of the above UPA, the coating solution for forming the undercoat layer is mixed with a mixed solvent of methanol and 1-propanol so that the sample concentration index (SIGNAL LEVEL) suitable for measurement is 0.6 to 0.8. Dilute. Since the volume particle diameter of the metal oxide particles in the coating solution for forming the undercoat layer is considered not to change even when diluted in this way, the volume average particle diameter measured as a result of the dilution described above Further, the cumulative 90% particle size is treated as the volume average particle size and cumulative 90% particle size of the metal oxide particles in the coating solution for forming the undercoat layer.

In addition, the absorbance of the coating solution for forming the undercoat layer according to the present invention can be measured with a generally known spectrophotometer (absorption spectrophotometer). Conditions such as cell size and sample concentration when measuring absorbance vary depending on physical properties such as the particle diameter and refractive index of the metal oxide particles to be used. Therefore, in general, in the wavelength region to be measured (in the present invention, (400 nm to 1000 nm), the sample concentration is appropriately adjusted so as not to exceed the measurement limit of the detector. In the present invention, the sample concentration is adjusted so that the amount of the metal oxide particles in the coating solution for forming the undercoat layer is 0.0075 wt% to 0.012 wt%. The solvent used to prepare the sample concentration is usually the solvent used as the solvent for the coating solution for forming the undercoat layer, but is compatible with the solvent for the coating solution for forming the undercoat layer and the binder resin. Any mixture can be used as long as it does not cause turbidity when mixed and does not have large light absorption in the wavelength region of 400 nm to 1000 nm. Specific examples include alcohols such as methanol, ethanol, 1-propanol and 2-propanol; hydrocarbons such as toluene and xylene; ethers such as tetrahydrofuran; ketones such as methyl ethyl ketone and methyl isobutyl ketone. .
The cell size (optical path length) for measurement is 10 mm. Any cell may be used as long as it is substantially transparent in the range of 400 nm to 1000 nm, but it is preferable to use a quartz cell, and in particular, a sample cell and a standard cell. It is preferable to use a matched cell that has a difference in transmittance characteristics within a specific range.

  The absorbance of the coating solution for forming the undercoat layer of the present invention in a solvent prepared by mixing methanol and 1-propanol at a weight ratio of 7: 3 with respect to light with a wavelength of 400 nm and with respect to light with a wavelength of 1000 nm. The difference is preferably 1.0 (Abs) or less when the refractive index of the metal oxide particles is 2.0 or more, and is 0.00 when the refractive index of the metal oxide particles is 2.0 or less. 02 (Abs) or less is preferable.

[III-1-2. Binder resin]
The binder resin contained in the undercoat layer forming coating solution is the same as that described as the binder resin contained in the undercoat layer.
However, the content of the binder resin in the coating solution for forming the undercoat layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.5% by weight or more, preferably 1% by weight or more, and usually 20%. It is used in the range of not more than wt%, preferably not more than 10 wt%.

[III-1-3. solvent]
As the solvent (undercoat layer solvent) used in the coating solution for forming the undercoat layer according to the present invention, any solvent can be used as long as it can dissolve the binder resin according to the present invention. As this solvent, an organic solvent is usually used. Examples of the solvent include alcohols having 5 or less carbon atoms such as methanol, ethanol, isopropyl alcohol or normal propyl alcohol; chloroform, 1,2-dichloroethane, dichloromethane, trichrene, carbon tetrachloride, 1,2-dichloropropane, etc. Halogenated hydrocarbons; nitrogen-containing organic solvents such as dimethylformamide; aromatic hydrocarbons such as toluene and xylene.

  Moreover, the said solvent may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Furthermore, even if the solvent alone does not dissolve the binder resin according to the present invention, it can be used as long as the binder resin can be dissolved by using a mixed solvent with other solvents (for example, the organic solvents exemplified above). can do. In general, coating unevenness can be reduced by using a mixed solvent.

  In the coating solution for forming the undercoat layer according to the present invention, the amount ratio of the solvent and the solid content such as metal oxide particles and binder resin varies depending on the coating method of the coating solution for forming the undercoat layer, and the coating method to be applied In order to form a uniform coating film, it may be appropriately changed and used. Specifically, the concentration of the solid content in the coating solution for forming the undercoat layer is usually 1% by weight or more, preferably 2% by weight or more, and usually 30% by weight or less, preferably 25% by weight or less. It is preferable from the viewpoints of stability and coatability of the coating solution for forming the undercoat layer.

[III-1-4. Other ingredients]
The other components contained in the undercoat layer forming coating solution are the same as those described as the other components contained in the undercoat layer.

[III-1-5. Advantages of coating solution for undercoat layer formation]
The coating solution for forming the undercoat layer according to the present invention has high storage stability. There are various storage stability indexes. For example, the coating solution for forming the undercoat layer according to the present invention has a viscosity change rate at the time of preparation and after storage at room temperature for 120 days (that is, viscosity after storage for 120 days). The value obtained by dividing the difference between the viscosity at the time of production and the viscosity at the time of production) is usually 20% or less, preferably 15% or less, more preferably 10% or less. The viscosity can be measured by a method according to JIS Z 8803 using an E-type viscometer (manufactured by Tokimec, product name ED).
Further, by using the undercoat layer forming coating solution according to the present invention, it is possible to produce an electrophotographic photoreceptor with high quality and high efficiency.

[III-2. Manufacturing method of coating liquid for forming undercoat layer]
There is no restriction | limiting in the manufacturing method of the coating liquid for undercoat layer formation concerning this invention. However, the coating solution for forming the undercoat layer according to the present invention contains the metal oxide particles as described above, and the metal oxide particles are dispersed in the coating solution for forming the undercoat layer. Therefore, the manufacturing method of the undercoat layer forming coating liquid according to the present invention usually has a dispersion step of dispersing the metal oxide particles.

  In order to disperse the metal oxide particles, for example, a known mechanical grinding device (dispersing device) such as a ball mill, a sand grind mill, a planetary mill, or a roll mill is used. What is necessary is just to carry out wet dispersion in a solvent. By this dispersion step, it is considered that the metal oxide particles according to the present invention are dispersed and have the predetermined particle size distribution described above. Moreover, the dispersion solvent may use the solvent used for the coating liquid for undercoat layer formation, and may use the other solvent. However, when a solvent other than the solvent used for the coating solution for forming the undercoat layer is used as the dispersion solvent, the metal oxide particles and the solvent used for the coating solution for forming the undercoat layer are mixed or solvent-exchanged after dispersion. However, in this case, it is preferable to carry out the above mixing or solvent exchange while preventing the metal oxide particles from aggregating to have a predetermined particle size distribution.

Among the wet dispersion methods, those using a dispersion medium are particularly preferable.
Any known dispersion device may be used as a dispersion device for dispersion using a dispersion medium. Examples of a dispersing device that disperses using a dispersion medium include a pebble mill, a ball mill, a sand mill, a screen mill, a gap mill, a vibration mill, a paint shaker, and an attritor. Among these, those that can circulate and disperse the metal oxide particles are preferable. In addition, wet stirring ball mills such as a sand mill, a screen mill, and a gap mill are particularly preferable from the viewpoints of dispersion efficiency, fineness of reached particle diameter, ease of continuous operation, and the like. These mills may be either vertical or horizontal. The disc shape of the mill can be any plate type, vertical pin type, horizontal pin type or the like. Preferably, a liquid circulation type sand mill is used.
In addition, these dispersion apparatuses may be implemented by only 1 type, and may be implemented in arbitrary combinations of 2 or more types.

  Further, when dispersing using a dispersion medium, by using a dispersion medium having a predetermined average particle diameter, the volume average particle diameter of the metal oxide particles in the coating liquid for forming the undercoat layer and the above accumulation The 90% particle size can be within the above-mentioned range.

  That is, in the method for producing a coating liquid for forming an undercoat layer according to the present invention, when metal oxide particles are dispersed in a wet stirring ball mill, the average particle size is usually used as a dispersion medium of the wet stirring ball mill. A dispersion medium of 5 μm or more, preferably 10 μm or more, and usually 200 μm or less, preferably 100 μm or less is used. A dispersion medium having a small particle size tends to give a uniform dispersion in a short time. However, if the particle size is excessively small, there is a possibility that the mass of the dispersion medium becomes too small to perform efficient dispersion.

  In addition, the use of a dispersion medium having an average particle size as described above allows the volume average particle size and cumulative 90% particle size of the metal oxide particles in the coating solution for forming the undercoat layer to be obtained by the manufacturing method described above. It is considered that this is one of the factors that can fall within the desired range. Therefore, the coating solution for forming the undercoat layer produced using the metal oxide particles dispersed using the dispersion medium having the above average particle size in the wet stirring ball mill is the undercoat layer forming coating solution according to the present invention. It satisfies the liquid requirements well.

  Since the dispersion medium usually has a shape close to a true sphere, for example, the average particle diameter can be obtained by measuring by sieving using a sieve described in JIS Z 8801: 2000 or by image analysis, The density can be measured by the Archimedes method. Specifically, for example, the average particle diameter and sphericity of the dispersion medium can be measured by an image analyzer represented by LUZEX50 manufactured by Nireco Corporation.

Although there is no restriction | limiting in the density of a dispersion medium, A thing of 5.5 g / cm < ³ > or more is used normally, Preferably it is 5.9 g / cm < ³ > or more, More preferably, a thing of 6.0 g / cm < ³ > or more is used. Generally, dispersion using a higher density dispersion medium tends to give a uniform dispersion in a shorter time. The sphericity of the dispersion medium is preferably 1.08 or less, more preferably a dispersion medium having a sphericity of 1.07 or less.

As the material of the dispersion medium, any known material can be used as long as it is insoluble in the dispersion solvent contained in the slurry and has a specific gravity greater than that of the slurry and does not react with the slurry or alter the slurry. Any distributed media can be used. Examples include steel balls such as chrome balls (ball balls for ball bearings) and carbon balls (carbon steel balls); stainless steel balls; ceramic balls such as silicon nitride balls, silicon carbide, zirconia, and alumina; titanium nitride, carbonitride Examples thereof include a sphere coated with a film of titanium or the like. Among these, ceramic spheres are preferable, and zirconia fired balls are particularly preferable. More specifically, it is particularly preferable to use zirconia fired beads described in Japanese Patent No. 3400836.
Note that only one type of dispersion medium may be used, or two or more types may be used in any combination and ratio.

Further, among the wet stirring ball mills, in particular, a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, and a dispersion medium filled in the stator And a rotor that stirs and mixes the slurry supplied from the supply port and a discharge port, and is rotatably provided to separate the dispersion medium and the slurry by the action of centrifugal force, and discharge the slurry from the discharge port. It is preferable to use what is provided with the separator for doing.
Here, the slurry contains at least metal oxide particles and a dispersion solvent.

Hereinafter, the configuration of this wet stirring ball mill will be described in detail.
The stator is a cylindrical (usually cylindrical) container having a hollow portion therein, and a slurry supply port is formed at one end and a slurry discharge port is formed at the other end. Furthermore, the inside hollow portion is filled with a dispersion medium, and the metal oxide particles in the slurry are dispersed by the dispersion medium. The slurry is supplied from the supply port into the stator, and the slurry in the stator is discharged from the discharge port to the outside of the stator.

  The rotor is provided inside the stator, and stirs and mixes the dispersion medium and the slurry. Note that the rotor type includes, for example, a pin, a disk, an annular type, and any type of rotor may be used.

  Furthermore, the separator separates the dispersion medium and the slurry. This separator is provided so as to be connected to the discharge port of the stator. And it is comprised so that the slurry and dispersion medium in a stator may be isolate | separated and a slurry may be sent out of the stator from the discharge port of a stator.

In addition, the separator used here is rotatably provided, preferably an impeller type, so that the dispersion medium and the slurry are separated by the action of centrifugal force generated by the rotation of the separator. It has become.
Note that the separator may be rotated integrally with the rotor, or may be rotated independently of the rotor.

  Moreover, it is preferable that the wet stirring ball mill is provided with a shaft that serves as a rotating shaft of the separator. Furthermore, it is preferable that a hollow discharge path communicating with the discharge port is formed at the shaft center of the shaft. That is, the wet stirring ball mill includes at least a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, a dispersion medium filled in the stator, and A rotor that stirs and mixes the slurry supplied from the supply port, and an impeller that is connected to the discharge port and is rotatably provided to separate the dispersion medium and the slurry by the action of centrifugal force and discharge the slurry from the discharge port. Preferably, the separator is configured to include a type separator and a shaft that serves as a rotation axis of the separator, and a hollow discharge path that communicates with the discharge port is formed in the shaft center.

  The discharge passage formed in the shaft communicates the rotation center of the separator and the discharge port of the stator. For this reason, the slurry separated from the dispersion medium by the separator is sent to the discharge port through the discharge path, and discharged from the discharge port to the outside of the stator. At this time, although the discharge passage passes through the shaft center, the centrifugal force does not act on the shaft, so that the slurry is discharged without kinetic energy. For this reason, kinetic energy is not wasted and useless power is not consumed.

  Such a wet stirring ball mill may be horizontally oriented, but is preferably oriented vertically in order to increase the filling rate of the dispersion medium. At this time, the discharge port is preferably provided at the upper end of the mill. Further, in this case, it is desirable to provide a separator above the level of the dispersion medium filled.

  When the discharge port is provided at the upper end of the mill, the supply port is provided at the bottom of the mill. In this case, as a more preferable aspect, the supply port is configured by a valve seat, and a V-shaped, trapezoidal, or cone-shaped valve body that is fitted to the valve seat so as to be movable up and down and can be in line contact with the edge of the valve seat. To do. This makes it possible to form an annular slit between the edge of the valve seat and the valve body so that the dispersion medium cannot pass through. Therefore, the slurry is supplied at the supply port, but the dispersion medium can be prevented from falling. Further, it is possible to widen the slit to raise the valve body to discharge the dispersion medium, or to lower the valve body to close the slit and seal the mill. Further, since the slit is formed by the edge of the valve body and the valve seat, coarse particles (metal oxide particles) in the slurry are difficult to bite, and even if they are bitten, they are easily pulled up and down and are not easily clogged.

  Further, if the valve body is caused to vibrate up and down by the vibration means, the coarse particles caught in the slit can be pulled out from the slit, and the biting itself is difficult to occur. In addition, the shearing force is applied to the slurry by the vibration of the valve body, the viscosity is lowered, and the amount of slurry passing through the slit (that is, the supply amount) can be increased. There is no limitation on the vibration means for vibrating the valve body. For example, in addition to mechanical means such as a vibrator, means for changing the pressure of compressed air acting on a piston integrated with the valve body, for example, a reciprocating compressor In addition, an electromagnetic switching valve for switching intake / exhaust of compressed air can be used.

  In such a wet stirring ball mill, it is desirable that a screen for separating the dispersion medium and a slurry outlet are provided at the bottom so that the slurry remaining in the wet stirring ball mill can be taken out after the dispersion is completed.

  In addition, the wet stirring ball mill is installed vertically, and the shaft is pivotally supported on the upper end of the stator, and an O-ring and a mechanical seal having a mating ring are provided on the bearing portion for supporting the shaft at the upper end of the stator. When an O-ring is fitted into the bearing and an O-ring is fitted to the annular groove, a tapered shape that expands downward is formed on the lower side of the annular groove. It is preferable to form a notch. That is, a wet stirring ball mill is supported by a cylindrical vertical stator, a slurry supply port provided at the bottom of the stator, a slurry discharge port provided at the upper end of the stator, and an upper end of the stator. A shaft that is rotationally driven by the driving means, a pin, a disk or an annulus type rotor that is fixed to the shaft and that stirs and mixes the dispersion medium filled in the stator and the slurry supplied from the supply port, and near the discharge port The separator that separates the dispersion media from the slurry and the mechanical seal that is provided on the bearing that supports the shaft at the upper end of the stator, and the O-ring that contacts the mating ring of the mechanical seal are fitted. Forming a tapered incision that expands downward in the lower part of the annular groove Preferred.

According to the above-described wet stirring ball mill, the mechanical seal is provided at the shaft center where the dispersion medium or slurry has little kinetic energy and at the upper end of the stator above the liquid surface level. And dispersion medium and slurry can be greatly reduced between the lower portion of the O-ring fitting groove.
In addition, the lower portion of the annular groove into which the O-ring is fitted is expanded downward by cutting, and the clearance is widened. Therefore, the slurry and the dispersion medium are jammed and solidified due to clogging or solidification. This prevents the mating ring from following the seal ring smoothly and maintains the function of the mechanical seal. In addition, since the lower part of the fitting groove into which the O-ring is fitted has a V-shaped cross section and the whole is not thin, the strength is not impaired, and the holding function of the O-ring is also impaired. Absent.

  In particular, the separator has two disks each provided with a fitting groove for a blade on the opposite inner surface, a blade that is fitted in the fitting groove and is interposed between the disks, and a blade. It is preferable to include a supporting means for sandwiching the disk from both sides. That is, as the wet stirring ball mill, a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, and the stator filled A dispersion medium, a rotor for stirring and mixing the slurry supplied from the supply port, and connected to the discharge port and rotatably provided in the stator, and the dispersion medium and the slurry are rotated by the action of centrifugal force. And a separator for discharging the slurry from the discharge port, and the separator is provided with two disks provided with a fitting groove of a blade on the opposing inner surface, and the fitting The blade fitted in a groove and interposed between the disks, and support means for clamping the disk with the blades interposed from both sides; It is preferable to equip. In this case, in a preferred embodiment, the support means is composed of a shaft step that forms a stepped shaft and a cylindrical presser unit that fits into the shaft and presses the disk, and the shaft step and the presser unit are used to hold the blade. The intervening disc is sandwiched and supported from both sides. By such a wet stirring ball mill, the metal oxide particles in the undercoat layer can easily be within the range of the volume average particle size and the cumulative 90% particle size. Here, the separator preferably has an impeller type configuration.

Hereinafter, in order to more specifically describe the configuration of the above-described vertical wet stirring ball mill, an embodiment of the wet stirring ball mill will be described. However, the stirrer used for producing the undercoat layer coating solution of the present invention is not limited to those exemplified here.
FIG. 1 is a longitudinal sectional view schematically showing the configuration of the wet stirring ball mill of this embodiment. In FIG. 1, slurry (not shown) is supplied to a vertical wet stirring ball mill, pulverized by being stirred with the dispersion medium (not shown) in the mill, and then the dispersion medium is separated by a separator 14 and shaft The material is discharged through a discharge passage 19 formed at the center of 15 shafts, followed by a return route (not shown), and circulated and crushed.

  As shown in detail in FIG. 1, the vertical wet stirring ball mill includes a stator 17 having a longitudinally cylindrical shape and a jacket 16 through which cooling water for cooling the mill is passed, and an axis of the stator 17. And a shaft 15 provided with a mechanical seal as shown in FIG. 2 (described later) at the upper portion of the stator 17 and having an upper shaft center as a hollow discharge passage 19. A pin or disk-shaped rotor 21 projecting in the radial direction at the lower end of the shaft 15, a pulley 24 fixed to the upper part of the shaft 15 and transmitting a driving force, and an open end at the upper end of the shaft 15. A rotary joint 25, a separator 14 for separating media fixed to the shaft 15 near the top in the stator 17, and a shaft 15 at the bottom of the stator 17. It is mounted on a grid-like screen support 27 installed at a slurry supply port 26 provided opposite to the shaft end and a slurry take-out port 29 provided at an eccentric position at the bottom of the stator 17 to separate the dispersion media. And a screen 28.

  The separator 14 is composed of a pair of disks 31 fixed to the shaft 15 at a predetermined interval and a blade 32 connecting the disks 31 to form an impeller. Centrifugal force is applied to the dispersion medium and the slurry that have entered, and the dispersion medium is blown outward in the radial direction due to the difference in specific gravity, while the slurry is discharged through the discharge passage 19 at the shaft center of the shaft 15. .

  The slurry supply port 26 is composed of an inverted trapezoidal valve body 35 that fits up and down on a valve seat formed at the bottom of the stator 17, and a bottomed cylindrical body 36 that projects downward from the bottom of the stator 17. When the valve body 35 is pushed up by the supply of slurry, an annular slit (not shown) is formed between the valve seat 35 and the slurry, so that the slurry is supplied into the stator 17.

The valve body 35 at the time of supplying the raw material rises against the pressure in the mill due to the supply pressure of the slurry fed into the cylindrical body 36, and forms a slit between the valve seat 35 and the valve seat.
In order to eliminate clogging at the slit, the valve body 35 can be lifted up and down to the upper limit position in a short cycle to eliminate biting. The valve body 35 may be vibrated at all times or when the slurry contains a large amount of coarse particles. When the slurry supply pressure rises due to clogging, the valve body 35 is interlocked with this. May be performed.

  As shown in detail in FIG. 2, the mechanical seal is formed by pressing a mating ring 101 on the stator side to a seal ring 100 fixed to the shaft 15 by the action of a spring 102, thereby sealing the stator 17 and the mating ring 101. Is performed by an O-ring 104 that fits into the stator-side fitting groove 103. In FIG. 2, the lower portion of the O-ring fitting groove 103 has a tapered shape that expands downward. The notch (not shown) is inserted, the length a of the minimum clearance portion between the lower portion of the fitting groove 103 and the mating ring 101 is narrow, the medium and slurry enter and solidify, and the mating ring The movement of 101 is not hindered so that the seal with the seal ring 100 is not impaired.

  In the above embodiment, the rotor 21 and the separator 14 are fixed to the same shaft 15, but in another embodiment, the rotor 21 and the separator 14 are fixed to separate shafts arranged on the same axis and are driven to rotate separately. In the above-described embodiment in which the rotor and the separator are attached to the same shaft, the structure is simplified because only one drive device is required. On the other hand, the rotor and the shaft are attached to separate shafts, and the drive is separated. In the latter embodiment, which is driven to rotate by the apparatus, the rotor and the separator can be driven at optimum rotational speeds, respectively.

The ball mill shown in FIG. 3 has a shaft 105 as a stepped shaft, a separator 106 is inserted from the lower end of the shaft, a spacer 107 and a disk or pin-like rotor 108 are alternately inserted, and a stopper 109 is inserted at the lower end of the shaft. The separator 106 is fastened by a screw 110, and the separator 106, the spacer 107 and the rotor 108 are sandwiched and fixed by a step 105a of the shaft 105 and a stopper 109. The separator 106 is a surface facing the inside as shown in FIG. A pair of discs 115 each having a blade fitting groove 114 formed thereon, a blade 116 interposed between the two discs and fitted in the blade fitting groove 114, and the two discs 115 are maintained at a constant interval, and the discharge path An annular spacer 113 formed with a hole 112 communicating with 111; Constitute a.
In addition, specifically as a wet stirring ball mill which has a structure which was illustrated by this embodiment, the ultra apex mill made from a Kotobuki industry is mentioned, for example.

  Since the wet stirring ball mill of the present embodiment is configured as described above, the slurry is dispersed by the following procedure. That is, a dispersion medium (not shown) is filled in the stator 17 of the wet stirring ball mill of this embodiment, and the rotor 21 and the separator 14 are driven to rotate by external power, while a certain amount of slurry is supplied. 26. Thus, slurry is supplied into the stator 7 through a slit (not shown) formed between the edge of the valve seat and the valve body 35.

  The slurry in the stator 7 and the dispersion medium are agitated and mixed by the rotation of the rotor 21 and the slurry is pulverized. Further, the dispersion medium and the slurry that have entered the separator 14 are separated by the difference in specific gravity due to the rotation of the separator 14, and the dispersion medium having a high specific gravity is blown outward in the radial direction, whereas the slurry having a low specific gravity is transferred to the shaft 15. Is discharged through a discharge passage 19 formed at the axis of the material and returned to the raw material tank. When the pulverization has progressed to some extent, the particle size of the slurry is appropriately measured. When the desired particle size is reached, the raw material pump is stopped, the mill operation is stopped, and the pulverization is terminated.

  In addition, when the metal oxide particles are dispersed using a wet stirring ball mill, there is no limitation on the filling rate of the dispersion medium filled in the wet stirring ball mill, and the metal oxide particles are dispersed until a desired particle size distribution is obtained. If it can be performed, it is arbitrary. However, when the metal oxide particles are dispersed using the vertical wet stirring ball mill as described above, the filling rate of the dispersion medium filled in the wet stirring ball mill is usually 50% or more, preferably 70% or more. , More preferably 80% or more, and usually 100% or less, preferably 95% or less, more preferably 90% or less.

  In the wet stirring ball mill applied to disperse the metal oxide particles, the separator may be a screen or a slit mechanism, but as described above, an impeller type is desirable, and a vertical type is preferable. It is desirable that the wet stirring ball mill be oriented vertically and the separator be provided at the top of the mill. Particularly when the filling rate of the dispersion medium is set within the above range, the grinding is most efficiently performed, and the separator is more than the media filling level. It becomes possible to position it above, and there is an effect that it is possible to prevent the dispersion medium from being discharged on the separator.

  The operating conditions of the wet stirring ball mill applied to disperse the metal oxide particles include the volume average particle diameter and cumulative 90% particle diameter of the metal oxide particles in the coating solution for forming the undercoat layer, subbing Stability of the layer forming coating solution, surface shape of the undercoat layer formed by applying and forming the undercoat layer forming coating solution, and electron having an undercoat layer formed by applying and forming the undercoat layer forming coating solution Affects the characteristics of photographic photoreceptors. In particular, the slurry supply speed and the rotational speed of the rotor are considered to have a great influence.

  The slurry supply speed is related to the time during which the slurry stays in the wet stirring ball mill, and is therefore affected by the volume of the mill and its shape. In the case of a commonly used stator, the volume of the wet stirring ball mill is 1 liter (hereinafter referred to as L Is usually 20 kg / hour or more, preferably 30 kg / hour or more, and usually 80 kg / hour or less, preferably 70 kg / hour or less.

  The rotational speed of the rotor is affected by parameters such as the rotor shape and the gap with the stator. In the case of a commonly used stator and rotor, the peripheral speed of the rotor tip is usually 5 m / second or more, preferably The range is 8 m / second or more, more preferably 10 m / second or more, and usually 20 m / second or less, preferably 15 m / second or less, more preferably 12 m / second or less.

  Furthermore, there is no limit on the amount of distributed media used. However, the dispersion medium is usually used in a volume ratio of 1 to 5 times that of the slurry. In addition to the dispersion medium, a dispersion aid that can be easily removed after dispersion can be used in combination. Examples of the dispersion aid include sodium chloride and sodium nitrate.

The metal oxide particles are preferably dispersed in the presence of a dispersion solvent in a wet manner. Moreover, as long as the metal oxide particles can be appropriately dispersed, components other than the dispersion solvent may coexist. Examples of such components that may coexist include binder resins and various additives.
The dispersion solvent is not particularly limited, but if the solvent used in the coating solution for forming the undercoat layer is used, it is preferable that a step such as solvent exchange is not required after dispersion. Any one of these dispersion solvents may be used alone, or two or more of these dispersion solvents may be used in any combination and ratio, and may be used as a mixed solvent.

From the viewpoint of productivity, the amount of the dispersion solvent used is usually 0.1 parts by weight or more, preferably 1 part by weight or more, and usually 500 parts by weight or less with respect to 1 part by weight of the metal oxide to be dispersed. The range is preferably 100 parts by weight or less.
The temperature at the time of mechanical dispersion can be from the freezing point of the solvent (or mixed solvent) to the boiling point or less, but from the viewpoint of safety during production, it is usually 10 ° C. or more and 200 ° C. or less. It is performed in the range.

After the dispersion treatment using the dispersion medium, it is preferable to separate and remove the dispersion medium from the slurry and to perform ultrasonic treatment. The ultrasonic treatment applies ultrasonic vibration to the metal oxide particles.
There are no particular restrictions on the conditions for ultrasonic treatment such as the vibration frequency, but ultrasonic vibration is applied by an oscillator having a frequency of usually 10 kHz or more, preferably 15 kHz or more, and usually 40 kHz or less, preferably 35 kHz or less.
Moreover, although there is no restriction | limiting in particular in the output of an ultrasonic oscillator, Usually 100W-5kW thing is used.

  Furthermore, it is usually better to disperse a small amount of slurry with ultrasonic waves from a small output ultrasonic oscillator than to process a large amount of slurry with ultrasonic waves from a high output ultrasonic oscillator. Therefore, the amount of slurry to be treated at one time is usually 1 L or more, preferably 5 L or more, more preferably 10 L or more, and usually 50 L or less, preferably 30 L or less, more preferably 20 L or less. In this case, the output of the ultrasonic oscillator is preferably 200 W or more, more preferably 300 W or more, still more preferably 500 W or more, and preferably 3 kW or less, more preferably 2 kW or less, and even more preferably 1.5 kW or less. It is.

  There is no particular limitation on the method of applying ultrasonic vibration to the metal oxide particles. For example, the method of directly immersing the ultrasonic oscillator in the container containing the slurry, or contacting the ultrasonic oscillator on the outer wall of the container containing the slurry. And a method of immersing a container containing a slurry in a liquid that has been vibrated by an ultrasonic oscillator. Among these methods, a method of immersing a container containing slurry in a liquid that has been vibrated by an ultrasonic oscillator is preferably used.

  In the above case, the liquid to be vibrated by the ultrasonic oscillator is not limited, but examples thereof include water; alcohols such as methanol; aromatic hydrocarbons such as toluene; and fats and oils such as silicone oil. Among them, it is preferable to use water in consideration of safety in production, cost, cleanability and the like.

  In the method of immersing a container containing slurry in a liquid that has been vibrated by an ultrasonic oscillator, it is preferable to keep the temperature of the liquid constant because the efficiency of ultrasonic treatment changes depending on the temperature of the liquid. . The temperature of the liquid to which vibration is applied may increase due to the applied ultrasonic vibration. The temperature of the liquid is usually 5 ° C. or higher, preferably 10 ° C. or higher, more preferably 15 ° C. or higher, and usually 60 ° C. or lower, preferably 50 ° C. or lower, more preferably 40 ° C. or lower. It is preferable to do.

  There is no limitation on the container in which the slurry is placed when ultrasonic treatment is performed. For example, any container can be used as long as it is a container that is normally used to contain a coating solution for forming an undercoat layer used for forming a photosensitive layer for an electrophotographic photoreceptor. Specific examples include a resin container such as polyethylene and polypropylene, a glass container, and a metal can. Among these, metal cans are preferable, and in particular, 18 liter metal cans as defined in JIS Z 1602 are preferably used. This is because it is hardly affected by organic solvents and is strong against impact.

  Moreover, the slurry after dispersion and the slurry after ultrasonic treatment are used after being filtered as necessary in order to remove coarse particles. As filtration media in this case, any filtration media such as cellulose fiber, resin fiber, and glass fiber, which are usually used for filtration, may be used. As a form of the filtration media, a so-called wind filter in which various fibers are wound around a core material is preferable because of a large filtration area and high efficiency. As the core material, any conventionally known core material can be used. Examples of the core material include stainless steel core materials and polypropylene-made resin core materials that do not dissolve in the slurry and the solvent contained in the slurry.

  The slurry thus obtained further contains a solvent, a binder resin (binder), other components (auxiliaries, etc.) as necessary to form a coating liquid for forming an undercoat layer. In addition, the metal oxide particles are used as needed for the solvent and binder resin for the coating solution for forming the undercoat layer, before, during or after the dispersion or sonication step. What is necessary is just to mix with the other component made. Therefore, the mixing of the metal oxide particles with the solvent, binder resin, other components, etc. is not necessarily performed after the dispersion or ultrasonic treatment.

  As described above, according to the method for producing an undercoat layer forming coating solution according to the present invention, the undercoat layer forming coating solution according to the present invention can be efficiently produced, and the undercoat layer has higher storage stability. A forming coating solution can be obtained. Therefore, a higher quality electrophotographic photosensitive member can be obtained efficiently.

[III-3. Formation of undercoat layer]
The undercoat layer according to the present invention can be formed by applying the coating liquid for forming the undercoat layer according to the present invention on a conductive support and drying it. There is no limitation on the method for applying the coating solution for forming the undercoat layer according to the present invention, but examples include dip coating, spray coating, nozzle coating, spiral coating, ring coating, bar coating coating, roll coating coating, blade coating, and the like. Can be mentioned. In addition, these coating methods may be implemented only by 1 type, and may be implemented in arbitrary combinations of 2 or more types.

  Examples of the spray coating method include air spray, airless spray, electrostatic air spray, electrostatic airless spray, rotary atomizing electrostatic spray, hot spray, and hot airless spray. Further, considering the atomization degree for obtaining a uniform film thickness, the adhesion efficiency, etc., in the rotary atomizing electrostatic spray, the conveying method disclosed in the republished publication No. 1-805198, that is, cylindrical It is preferable that the workpiece is continuously conveyed without being spaced apart in the axial direction while rotating the workpiece. Thereby, an electrophotographic photoreceptor excellent in uniformity of the thickness of the undercoat layer can be obtained with a comprehensively high adhesion efficiency.

Examples of the spiral coating method include a method using a liquid injection coating machine or a curtain coating machine disclosed in Japanese Patent Laid-Open No. 52-119651, and paint from a minute opening disclosed in Japanese Patent Laid-Open No. 1-2231966. There are a method of continuously flying in a streak shape, a method using a multi-nozzle body disclosed in JP-A-3-193161, and the like.
In the case of the dip coating method, the total solid concentration of the coating solution for forming the undercoat layer is usually 1% by weight or more, preferably 10% by weight or more, and usually 50% by weight or less, preferably 35% by weight or less. The viscosity is preferably 0.1 cps or more, and preferably 100 cps or less. Note that 1 cps = 1 × 10 ⁻³ Pa · s.

  After coating, the coating film is dried, but it is preferable to adjust the drying temperature and time so that necessary and sufficient drying is performed. The drying temperature is usually 100 ° C. or higher, preferably 110 ° C. or higher, more preferably 115 ° C. or higher, and usually 250 ° C. or lower, preferably 170 ° C. or lower, more preferably 140 ° C. or lower. There is no restriction | limiting in the drying method, For example, a hot air dryer, a steam dryer, an infrared dryer, a far-infrared dryer, etc. can be used.

[IV. Photosensitive layer]
As the structure of the photosensitive layer, any structure applicable to a known electrophotographic photoreceptor can be adopted. As a specific example, a so-called single-layer type photoreceptor having a single-layer photosensitive layer (that is, a single-layer type photosensitive layer) in which a photoconductive material is dissolved or dispersed in a binder resin; containing a charge generating substance. Examples include a so-called multilayer photoreceptor having a photosensitive layer (that is, a multilayer photosensitive layer) composed of a plurality of layers formed by laminating a charge generation layer and a charge transport layer containing a charge transport material. In general, it is known that the photoconductive material exhibits the same performance as a function regardless of whether it is a single layer type or a laminated type.

The photosensitive layer of the electrophotographic photosensitive member of the present invention may be in any known form. However, in consideration of the mechanical properties, electrical characteristics, manufacturing stability, etc. of the photosensitive member, A photoreceptor is preferred. In particular, a sequential lamination type photoreceptor in which an undercoat layer, a charge generation layer, and a charge transport layer are laminated in this order on a conductive support is more preferable.
The photosensitive layer according to the present invention contains a specific arylamine compound.

[IV-1. Arylamine Compound According to the Present Invention]
The photosensitive layer according to the present invention contains a compound represented by the following formula (I) (appropriately referred to as “arylamine compound according to the present invention”). The arylamine compound according to the present invention functions as a charge transport material in the photosensitive layer.

（式（Ｉ）において、Ａｒ¹〜Ａｒ⁶はそれぞれ独立に置換基を有しても良い芳香族残基を表し、Ｘは置換基を有していてもよい有機残基を表し、Ｒ¹〜Ｒ⁴はそれぞれ独立に置換基を有しても良い不飽和基を表し、ｎ₁は１又は２を表し、ｎ₀及びｎ₂〜ｎ₆は０〜２の整数を表す。）

(In the formula (I), Ar ^{1 to} Ar ⁶ each independently represents an aromatic residue which may have a substituent, X represents an organic residue which may have a substituent, R ¹ to R ⁴ also have independently substituent represents an unsaturated group, n ₁ is 1 or 2, n ₀ and n ₂ ~n ₆ represents an integer of 0 to 2.)

In the formula (I), Ar ^{1 to} Ar ⁶ each independently represents an aromatic residue that may have a substituent. Here, the valences of Ar ^{1 to} Ar ⁶ are valences at which the structure represented by formula (I) can be established. Specifically, Ar ^{2 to} Ar ⁵ are monovalent or divalent groups, and Ar ¹ and Ar ⁶ are divalent groups.

Examples of aromatic residues that become Ar ^{1 to} Ar ⁶ include aromatic hydrocarbon residues such as benzene, naphthalene, anthracene, pyrene, perylene, phenanthrene, and fluorene; aromatics such as thiophene, pyrrole, carbazole, and imidazole. And heterocyclic residues.
Moreover, the carbon number of the aromatic residue which becomes Ar ^{1 to} Ar ⁶ is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 20 or less, preferably 16 or less, more preferably 10 or less. If the number of carbon atoms is too large, the stability of the arylamine compound represented by the formula (I) is lowered and may be decomposed by an oxidizing gas, so that ozone resistance may be lowered. In addition, a ghost phenomenon due to memory may easily occur during image formation. Moreover, a minimum is 5 or more normally from a viewpoint of an electrical property, Preferably it is 6 or more.
From the above viewpoint, among the above-described aromatic residues, Ar ^{1 to} Ar ⁶ are preferably aromatic hydrocarbon residues, and more preferably benzene residues. In particular, Ar ^{1 to} Ar ⁶ are particularly preferably all benzene residues.

Moreover, the substituent which Ar < ¹ > -Ar < ⁶ > has is arbitrary unless the effect of this invention is impaired remarkably. Examples of this substituent include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group and allyl group; alkoxy groups such as methoxy group, ethoxy group and propoxy group; phenyl group, indenyl group, naphthyl group, Examples thereof include aryl groups such as acenaphthyl group, phenanthryl group and pyrenyl group; and heterocyclic groups such as indolyl group, quinolyl group and carbazolyl group. These substituents may form a ring by a linking group or a direct bond.

  The introduction of the above-described substituent has the effect of adjusting the intramolecular charge of the arylamine compound according to the present invention and increasing the charge mobility. On the other hand, if the bulk becomes too large, In some cases, the charge mobility may be lowered due to the distortion of the molecule and the intermolecular steric repulsion. For this reason, the number of carbon atoms of the substituent is usually 1 or more, and usually 6 or less, preferably 4 or less, more preferably 2 or less.

Furthermore, the said substituent may be substituted by 1 piece and may be substituted by 2 or more pieces. Moreover, only 1 type may be substituted for the said substituent and 2 or more types may be substituted by arbitrary combinations and ratios. However, it is preferable to have a plurality of substituents because it has an effect of suppressing crystal precipitation of the arylamine compound according to the present invention. However, if there are too many substituents, the charge is changed due to distortion of the conjugate plane in the molecule and intermolecular steric repulsion. May reduce mobility. For this reason, Preferably, the number of the substituent which Ar < ¹ > -Ar < ⁶ > has is normally 2 or less per ring.

Furthermore, the substituent which Ar ^{1 to} Ar ⁶ has is preferably one that is not sterically bulky in order to improve the stability of the arylamine compound according to the present invention in the photosensitive layer and improve the electrical characteristics. From these viewpoints, examples of suitable substituents of Ar ^{1 to} Ar ⁶ include a methyl group, an ethyl group, a butyl group, an isopropyl group, and a methoxy group.

In particular, when Ar ^{1 to} Ar ⁴ are benzene residues, it is preferable to have a substituent. In this case, an example of a preferable substituent is an alkyl group, and a particularly preferable example is a methyl group.
When Ar ⁵ or Ar ⁶ is a benzene residue, examples of preferred substituents include a methyl group and a methoxy group.

Furthermore, in Formula (I), it is preferable that at least one of Ar ^{1 to} Ar ⁴ has a fluorene structure. At this time, as the fluorene structure, it is sufficient that at least a part of the skeleton has a fluorene structure. As a result, an electrophotographic photosensitive member having high charge mobility, excellent high-speed response, and low residual potential can be obtained.

In the formula (I), X represents an organic residue which may have a substituent. Here, the valence of X is a valence with which the structure represented by the formula (I) can be established, and specifically, it is divalent or trivalent. In the formula (I), when n ₅ is 2 (that is, when two Xs are present), Xs may be the same or different.
Examples of X include an aromatic residue that may have a substituent; a saturated aliphatic residue; a heterocyclic residue; an organic group having an ether structure; an organic residue having a divinyl structure, etc. Can be mentioned.

  The number of carbon atoms of the organic residue to be X is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 or more and 15 or less. Among them, X is preferably an aromatic residue or a saturated aliphatic residue. When X is an aromatic residue, the carbon number of the aromatic residue is preferably 6 or more, preferably 14 or less, more preferably 10 or less. More specifically, arylene groups such as a phenylene group and a naphthylene group are preferred. On the other hand, when X is a saturated aliphatic residue, the carbon number of the saturated aliphatic residue is preferably 10 or less, more preferably 8 or less.

  X may have a substituent. The substituent which X has is arbitrary, unless the effect of this invention is impaired remarkably. Examples of this substituent include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group and allyl group; alkoxy groups such as methoxy group, ethoxy group and propoxy group; phenyl group, indenyl group, naphthyl group, Examples thereof include aryl groups such as acenaphthyl group, phenanthryl group and pyrenyl group; and heterocyclic groups such as indolyl group, quinolyl group and carbazolyl group. Among them, an aryl group is preferable, and a phenyl group is particularly preferable. This is because the electrical characteristics of the photoreceptor are improved by using these. In order to increase charge mobility, an alkyl group is preferable, and a methyl group or an ethyl group is particularly preferable. These substituents may form a ring by a linking group or a direct bond.

  Further, the carbon number of the substituent of X is arbitrary as long as the effects of the present invention are not significantly impaired, but it is usually 1 or more, usually 10 or less, preferably 6 or less, more preferably 3 or less. From this point of view, examples of suitable substituents of X include a methyl group, an ethyl group, a butyl group, an isopropyl group, and a methoxy group.

  Furthermore, the substituent which X has may be substituted with one or may be substituted with two or more. Moreover, only 1 type may be substituted for the said substituent and 2 or more types may be substituted by arbitrary combinations and ratios. However, it is preferable to have a plurality of substituents because it has an effect of suppressing crystal precipitation of the arylamine compound according to the present invention. However, if there are too many substituents, the charge is changed due to distortion of the conjugate plane in the molecule and intermolecular steric repulsion. May reduce mobility. For this reason, preferably, the number of substituents X has is usually 2 or less per ring.

In the formula (I), R ^{1 to} R ⁴ each independently represents an unsaturated group which may have a substituent. An unsaturated group refers to a group constituting an unsaturated compound. Specifically, the unsaturated compound refers to a compound containing a double bond between carbon atoms or a triple bond among organic compounds. However, an aromatic double bond is not regarded as an unsaturated double bond.

（式（ＩＩ）において、Ｒ⁵〜Ｒ⁹は、それぞれ独立に、水素原子、又は、置換基を有しても良いアルキル基もしくはアリール基を表し、ｎ₇は０〜５の整数を表す。） The unsaturated group to be R ^{1 to} R ⁴ is arbitrary as long as the effects of the present invention are not significantly impaired, but a group represented by the following formula (II) is preferable.

(In the formula (II), R ^{5 to} R ⁹ each independently represents a hydrogen atom or an alkyl group or an aryl group which may have a substituent, and n ₇ represents an integer of 0 to 5. )

In the formula (II), R ^{5 to} R ⁹ each independently represents a hydrogen atom or an alkyl group or an aryl group which may have a substituent.
The carbon number of the alkyl group to be R ^{5 to} R ⁹ is arbitrary as long as the effects of the present invention are not significantly impaired, but is usually 10 or less, preferably 6 or less, more preferably 3 or less. Examples of the alkyl group that becomes R ^{5 to} R ⁹ include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and a stearyl group. Among them, a methyl group is preferable.

The number of carbon atoms of the aryl group to be R ^{5 to} R ⁹ is arbitrary as long as the effects of the present invention are not significantly impaired, but is usually 16 or less, preferably 10 or less, more preferably 6 or less. Examples of the aryl group as the R ⁵ to R ^9, a phenyl group, an indenyl group, a naphthyl group, an acenaphthyl group, a phenanthryl group, pyrenyl group.

Moreover, the said alkyl group and aryl group may be substituted with a substituent. The substituent which R < ⁵ > -R < ⁹ > has is arbitrary unless the effect of this invention is impaired remarkably. Examples of this substituent include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group and allyl group; alkoxy groups such as methoxy group, ethoxy group and propoxy group; phenyl group, indenyl group, naphthyl group, Examples thereof include aryl groups such as acenaphthyl group, phenanthryl group and pyrenyl group; and heterocyclic groups such as indolyl group, quinolyl group and carbazolyl group.

These substituents may form a ring by a linking group or a direct bond. Furthermore, the carbon number of the substituent which R ^{5 to} R ⁹ have is arbitrary as long as the effects of the present invention are not significantly impaired, but is usually 10 or less.
Further, in the formula (II), n ₇ represents an integer of 0 or more and 5 or less, preferably 2 or less.

In the formula (I), n ₁ represents 1 or 2, preferably 1.
In the formula (I), n ₀ and n ₂ each independently represents an integer of 0 to 2, preferably 0 or 1. However, when n ₀ is 0, n ₁ is 1.
Further, in the above formula (I), n ₃ and n ₄ each independently represent an integer of 0 to 2.
Further, in the formula (I), n ₅ and n ₆ represents an integer of 0 to 2. When n ₅ is 0, X represents a direct bond (direct bond) (that is, Ar ⁵ and Ar ⁶ are directly bonded). When n ₆ is 0, n ₅ is preferably 0.

When both n ₅ and n ₆ are 1, X is preferably an alkylidene group, an arylene group, or a group having an ether structure.
Preferred examples of the alkylidene group include a phenylmethylidene group, a 2-methylpropylidene group, a 2-methylbutylidene group, and a cyclohexylidene group. Moreover, as an example of an arylene group, a phenylene group, a naphthylene group, etc. are mentioned as a preferable thing. Furthermore, as an example of the group having an ether structure, —O—CH ₂ —O— and the like are preferable.

In the formula (I), when both n ₅ and n ₆ are 0, Ar ⁵ is preferably a benzene residue or a fluorene residue. In particular, when Ar ⁵ is a benzene residue, the benzene residue is preferably substituted with an organic group such as an alkyl group or an alkoxy group, and among them, a methyl group or a methoxy group is preferably substituted. In particular, the organic group is preferably substituted at the p-position of the nitrogen atom.
Further, in the formula (I), when n ₆ is 2, X is preferably a benzene residue.

Table 2 shows examples of specific combinations of n _{0 to} n ₆ in the formula (I).

  Specific examples of suitable structures of the arylamine compound according to the present invention are shown below. In the structural formulas of the arylamine compounds exemplified below, R represents a hydrogen atom or an arbitrary substituent. However, R may be the same or different. Moreover, as said substituent used as R, organic groups, such as an alkyl group, an alkoxy group, an aryl group, are preferable, for example, and especially a methyl group and a phenyl group are more preferable. N represents an integer of 0-2.

[IV-2. Charge generation layer]
The charge generation layer is a layer containing a charge generation material. As the charge generation material, known materials can be arbitrarily used as long as the effects of the present invention are not significantly impaired.
Examples of charge generating materials include selenium and its alloys, inorganic photoconductive materials such as cadmium sulfide; phthalocyanine pigments, azo pigments, dithioketopyrrolopyrrole pigments, squalene (squarylium) pigments, quinacridone pigments, indigo pigments, perylene pigments And various photoconductive materials such as organic pigments such as polycyclic quinone pigments, anthanthrone pigments, and benzimidazole pigments. Among these, organic pigments, phthalocyanine pigments, and azo pigments are particularly preferable.

  Among these, specific examples of phthalocyanine pigments include metals such as metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, and germanium, or oxides, halides, hydroxides, and alkoxides thereof. And various crystal forms of coordinated phthalocyanines. In particular, titanyl phthalocyanines 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 (also known as oxy) Titanium phthalocyanine), vanadyl phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and I, μ− such as type II Oxo-aluminum phthalocyanine dimer is preferred. Among these phthalocyanine pigments, A type (β type), B type (α type), D type (Y type) oxytitanium phthalocyanine, II type chlorogallium phthalocyanine, V type hydroxygallium phthalocyanine, G type μ-oxo. -Gallium phthalocyanine dimer is particularly preferred.

In particular, it is preferable that oxytitanium phthalocyanine has a clear diffraction peak mainly at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-ray.
In addition, the powder X-ray diffraction spectrum by CuKα characteristic X-ray can be usually measured according to a method used for solid powder X-ray diffraction measurement.

Oxytitanium phthalocyanine preferably has a clear diffraction peak at a Bragg angle (2θ ± 0.2 °) of 9.0 ° to 9.8 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-ray.
In particular, those having a peak at a Bragg angle (2θ ± 0.2 °) of 9.0 °, 9.6 °, or 9.5 and 9.7 ° are preferable. That is, the oxytitanium phthalocyanine has a clear diffraction peak mainly at a Bragg angle (2θ ± 0.2 °) of 9.0 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-ray, or a Bragg angle (2θ ± 0.2 °) preferably has a clear diffraction peak at 9.6 °, or has a clear diffraction peak at Bragg angles (2θ ± 0.2 °) of 9.5 ° and 9.7 °, respectively. .
However, the oxytitanium phthalocyanine preferably does not have a clear diffraction peak at a Bragg angle (2θ ± 0.2 °) of 26.3 °.

In the oxytitanium phthalocyanine, the chlorine content in the crystal is preferably 1.5% by weight or less. The chlorine content is obtained from elemental analysis.
Furthermore, in the oxytitanium phthalocyanine crystal, the ratio of the chlorinated oxytitanium phthalocyanine represented by the following formula (1) is higher than the unsubstituted oxytitanium phthalocyanine represented by the following formula (2). The ratio is usually 0.070 or less, preferably 0.060 or less, more preferably 0.055 or less. Further, in the production, when the dry grinding method is used for amorphization, the ratio is preferably 0.02 or more, and when the acid paste method is used for amorphization, the ratio is 0.03. The following is preferred. The chloro substitution amount can be measured based on the method described in JP-A No. 2001-115054.

The particle size of the oxytitanium phthalocyanine varies greatly depending on the production method, crystal conversion method, etc., but the primary particle size is preferably 500 nm or less in consideration of dispersibility, and is 300 nm or less from the viewpoint of coating film formability. Is preferred.
The oxytitanium phthalocyanine may be substituted with a substituent such as a fluorine atom, a nitro group, or a cyano group in addition to the chlorine atom. Alternatively, various oxytitanium phthalocyanine derivatives substituted with a substituent such as a sulfone group may be contained.

The method for producing the oxytitanium phthalocyanine is not limited. For example, the composition of oxytitanium phthalocyanine is obtained by synthesizing dichlorotitanium phthalocyanine using phthalonitrile and titanium halide as raw materials, and then hydrolyzing and purifying the dichlorotitanium phthalocyanine. This product is manufactured by crystallizing (crystal conversion) an amorphized oxytitanium phthalocyanine composition obtained by making a product intermediate and amorphizing the resulting oxytitanium phthalocyanine composition intermediate can do.
Hereinafter, this manufacturing method will be described.

The titanium halide is optional as long as oxytitanium phthalocyanine can be obtained. Among these, titanium chloride is preferable. Examples of the titanium chloride include titanium tetrachloride and titanium trichloride, and titanium tetrachloride is particularly preferable. When titanium tetrachloride is used, the content of chlorinated oxytitanium phthalocyanine contained in the obtained oxytitanium phthalocyanine composition can be easily controlled.
In addition, a titanium halide may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  When synthesizing dichlorotitanium phthalocyanine using phthalonitrile and titanium halide as raw materials, the reaction temperature is arbitrary as long as the reaction proceeds, but is usually 150 ° C. or higher, preferably 180 ° C. or higher. Furthermore, when using titanium chloride as the titanium halide, in order to control the content of chlorinated oxytitanium phthalocyanine, it is more preferably 190 ° C or higher, usually 300 ° C or lower, preferably 250 ° C or lower, More preferably, it is performed at 230 ° C. or lower.

  Usually, the titanium chloride is mixed with a mixture of phthalonitrile and the reaction solvent. In this case, the titanium chloride may be directly mixed as long as it has a boiling point or lower, or may be mixed with a high boiling point solvent having a boiling point of 150 ° C. or higher.

  For example, when diarylalkane is used as a reaction solvent and oxytitanium phthalocyanine is produced using phthalonitrile and titanium tetrachloride, titanium tetrachloride is divided at a low temperature of 100 ° C. or lower and a high temperature of 180 ° C. or higher. By mixing with phthalonitrile, oxytitanium phthalocyanine can be produced appropriately.

  The obtained dichlorotitanium phthalocyanine is hydrolyzed and purified, and then the resulting oxytitanium phthalocyanine composition intermediate is amorphized. There is no limitation on the method of amorphization, but for example, a so-called acid paste method obtained by pulverization with a known mechanical pulverizer such as a paint shaker, ball mill, sand grind mill, etc., or obtained as a solid in cold water after being dissolved in concentrated sulfuric acid It becomes amorphous by such as. Among these, in view of dark decay, mechanical pulverization is preferable, and the acid paste method is preferable from the viewpoint of sensitivity and environment dependence.

The obtained amorphous oxytitanium phthalocyanine composition is crystallized using a known solvent to obtain a composition containing oxytitanium phthalocyanine (oxytitanium phthalocyanine composition). Examples of the solvent used in this case include halogenated aromatic hydrocarbon solvents such as orthodichlorobenzene, chlorobenzene and chloronaphthalene; halogenated hydrocarbon solvents such as chloroform and dichloroethane; aromatics such as methylnaphthalene, toluene and xylene. Hydrocarbon solvents; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as methyl ethyl ketone and acetone; alcohols such as methanol, ethanol, butanol and propanol; ether solvents such as ethyl ether, propyl ether and butyl ether; terpinolene and pinene A monoterpene hydrocarbon solvent such as liquid paraffin is preferably used. Of these, orthodichlorobenzene, toluene, methylnaphthalene, ethyl acetate, butyl ether, pinene, and the like are preferable.
In addition, the solvent used for crystallization may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The phthalocyanine pigment may be in a mixed crystal state. As the mixed state in the phthalocyanine pigment or crystal state here, the respective constituent elements may be mixed and used later, or a mixed state is generated in the production / treatment process of phthalocyanine pigment such as synthesis, pigmentation, crystallization, etc. It can be stuffed. As examples of 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.

Examples of suitable azo pigments include various known bisazo pigments and trisazo pigments.
Examples of preferable azo pigments are shown below. In the following structural formula, Cp ¹ , Cp ² and Cp ³ each independently represent a coupler.

The couplers Cp ¹ , Cp ² and Cp ³ preferably have the following structures.

  In addition, the charge generation material may be used alone or in combination of two or more in any combination and ratio.

In the charge generation layer, the charge generation material is formed in a state where the charge generation material is bound by the binder resin. Here, any binder resin for the charge generation layer can be used as long as the effects of the present invention are not significantly impaired.
Examples of binder resins that can be used in the charge generation layer include polyvinyl butyral resins, polyvinyl formal resins, polyvinyl acetal resins such as partially acetalized polyvinyl butyral resins in which a part of butyral is modified with formal or acetal, Polyarylate resin, polycarbonate resin, polyester resin, modified ether-based polyester resin, phenoxy resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polystyrene resin, acrylic resin, methacrylic resin, polyacrylamide resin, polyamide resin, Polyvinyl pyridine resin, cellulose resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, casein, vinyl chloride-vinyl acetate Vinyl chloride-vinyl acetate copolymers such as copolymers, hydroxy-modified vinyl chloride-vinyl acetate copolymers, carboxyl-modified vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, Styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, styrene-alkyd resin, silicon-alkyd resin, insulating resin such as phenol-formaldehyde resin, poly-N-vinylcarbazole, polyvinylanthracene, polyvinylperylene, etc. Examples include organic photoconductive polymers.
In the charge generation layer, one binder resin may be used alone, or two or more binder resins may be used in any combination and ratio.

  The amount of the charge generating material used is arbitrary as long as the effects of the present invention are not significantly impaired. However, the amount of the charge generation material is usually 10 parts by weight or more, preferably 30 parts by weight or more, and usually 1000 parts by weight or less, preferably 500 parts by weight or less, with respect to 100 parts by weight of the binder resin in the charge generation layer. Is desirable. If the amount of the charge generating material is too small, sufficient sensitivity may not be obtained. If the amount is too large, the charge generating material may aggregate to reduce the stability of the coating solution used when forming the charge generating layer.

Further, the thickness of the charge generation layer is not limited, but is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 4 μm or less, preferably 0.6 μm or less.
In addition, the charge generating material is dispersed in the photosensitive layer forming coating solution at the time of formation, but there is no limitation on the dispersion method. For example, ultrasonic dispersion method, ball mill dispersion method, attritor dispersion method, sand mill dispersion Law. At this time, it is effective to reduce the particle size of the charge generating material to a particle size of usually 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

Further, the charge generation layer may contain any component as long as the effects of the present invention are not significantly impaired. For example, the charge generation layer may contain an additive. These additives are used for improving film-forming properties, flexibility, coating properties, stain resistance, gas resistance, light resistance, and the like. Examples thereof include antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, visible light shading agents, sensitizers, dyes, pigments, surfactants, and the like. Examples of the antioxidant include hindered phenol compounds and hindered amine compounds. Examples of dyes and pigments include various pigment compounds and azo compounds. Examples of surfactants include silicone oil and fluorine-based oil.
In addition, an additive may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

[IV-3. Charge transport layer]
The charge transport layer is a layer containing a charge transport material. In the electrophotographic photoreceptor of the present invention, the arylamine compound according to the present invention is used as a charge transport material.
In addition, unless the effect of the present invention is significantly impaired, a charge generating substance other than the arylamine compound according to the present invention (hereinafter, referred to as “charge transporting substance that can be used together”) may be used in combination with the arylamine compound according to the present invention. Is possible.

  Examples of charge transport materials that can be used in combination include aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, electron withdrawing materials such as quinone compounds such as diphenoquinone, carbazole Derivatives, indole derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, heterocyclic compounds such as benzofuran derivatives, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives and a plurality of these compounds Examples thereof include an electron-donating substance such as a polymer in which a species is bonded or a polymer having a group composed of these compounds in the main chain or side chain. Among these, carbazole derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and those obtained by bonding a plurality of these compounds are preferable.

  Specific examples of suitable structures of charge transport materials that can be used in combination are shown below. However, these specific examples are shown for illustrative purposes, and charge transport materials that can be used in combination are not limited to those exemplified here, and any known charge transport materials can be used without departing from the gist of the present invention. May be.

  In the structural formulas of the charge transport materials that can be used in combination as exemplified above, R represents a hydrogen atom or a substituent. As the substituent, an organic group such as an alkyl group, an alkoxy group, and an aryl group is preferable. Particularly preferred are a methyl group and a phenyl group. N is an integer of 0-2. Note that R may be the same or different.

  In addition, any one kind of charge transport materials may be used alone, or two or more kinds may be used in any combination and ratio. Therefore, the arylamine compound according to the present invention may be used alone or in combination of two or more in any combination and ratio. Further, the charge transport materials that can be used in combination may be used alone or in combination of two or more in any combination and ratio.

  When a charge generating material that can be used in combination is used, the ratio of the arylamine compound according to the present invention in the entire charge generating material is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 60% by weight or more, preferably 80%. % By weight or more, more preferably 90% by weight or more. If the amount of the arylamine compound according to the present invention is too small, the memory resistance of the photoreceptor is lowered, and the ghost phenomenon is likely to occur. The upper limit is 100% by weight.

Further, in the charge transport layer, the charge transport material is formed in a state where the charge transport material is bound by the binder resin. The binder resin is used for securing the film strength.
Here, as the binder resin of the charge generation layer, for example, butadiene resin, styrene resin, vinyl acetate resin, vinyl chloride resin, acrylate ester resin, methacrylate ester resin, vinyl alcohol resin, ethyl vinyl ether, and other vinyl compound heavy compounds can be used. Copolymers and copolymers, polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal, polycarbonate resin, polyester resin, polyarylate resin, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicon resin, silicon-alkyd resin, Examples thereof include poly-N-vinylcarbazole resin. The binder resin may be modified with a silicon reagent or the like.

  Of the binder resins, polycarbonate resins and polyarylate resins are particularly preferable. Furthermore, among polycarbonate resins and polyarylate resins, polycarbonate resins and polyarylate resins containing a bisphenol component or biphenol component having the following structure are preferred from the viewpoint of sensitivity and residual potential. Among these, polycarbonate resin is more preferable from the viewpoint of mobility.

Hereinafter, the structure of the monomer corresponding to the bisphenol component and biphenol component which can be used suitably for polycarbonate resin is illustrated. However, this illustration is performed for the purpose of clarification, and the present invention is not limited to the structure exemplified below unless departing from the gist of the present invention.

In particular, in order to further exhibit the effects of the present invention, a polycarbonate resin containing a bisphenol component corresponding to a bisphenol derivative having the following structure is preferable.

In order to improve mechanical properties, it is preferable to use a polyarylate resin. In this case, it is preferable to use a bisphenol component corresponding to the monomer represented by the following structural formula.

Furthermore, it is preferable to use an acid component corresponding to the monomer represented by the following structural formula.

In the charge transport layer, one type of binder resin may be used alone, or two or more types may be used in any combination and ratio.
The ratio of the binder resin and the charge transport material used in the charge transport layer is arbitrary as long as the effects of the present invention are not significantly impaired. However, the charge transport material is usually 20 parts by weight or more with respect to 100 parts by weight of the binder resin, and preferably 30 parts by weight or more from the viewpoint of reducing the residual potential, and further stability and charge mobility during repeated use. In view of the above, 40 parts by weight or more is more preferable. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, it is usually 150 parts by weight or less, and preferably 120 parts by weight or less from the viewpoint of compatibility between the charge transport material and the binder resin. 100 parts by weight or less is more preferable from the viewpoint of property, and 80 parts by weight or less is particularly preferable from the viewpoint of scratch resistance.

The thickness of the charge transport layer is not limited, but is usually 5 μm or more, preferably 10 μm or more from the viewpoint of long life and image stability, and is usually 50 μm or less, 45 μm from the viewpoint of long life and image stability. The following is preferable, and 30 μm or less is more preferable from the viewpoint of high resolution.
Furthermore, the charge generation layer may contain any component as long as the effect of the present invention is not significantly impaired, similarly to the charge transport layer. For example, an additive may be contained.

[IV-4. Single-layer type photosensitive layer]
The single-layer type photosensitive layer is configured by dispersing the above-described charge generating material in the charge transport layer having the above-described mixing ratio.

In the single-layer type photosensitive layer, the types of the charge transport material and the binder resin, and the usage ratio thereof are the same as those described for the charge transport layer. Therefore, the arylamine compound according to the present invention is contained in the single-layer type photosensitive layer.
The kind of the charge generation material is also as described above. However, in this case, it is desirable that the particle size of the charge generation material is sufficiently small. Specifically, it is usually 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

  Furthermore, if the amount of the charge generating material dispersed in the photosensitive layer is too small, there is a possibility that sufficient sensitivity cannot be obtained, and if it is too large, there are problems such as a decrease in chargeability and a decrease in sensitivity. Therefore, the amount of the charge generating substance in the single-layer type photosensitive layer is usually 0.1% by weight or more, preferably 1% by weight or more, and usually 50% by weight or less, preferably 20% by weight or less.

The thickness of the single-layer type photosensitive layer is arbitrary, but is usually 5 μm or more, preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less.
Further, the single layer type photosensitive layer may contain any component as long as the effects of the present invention are not significantly impaired. For example, an additive may be included as in the charge generation layer.

[IV-5. Method for forming photosensitive layer]
There is no limitation on the method of forming each layer constituting the photosensitive layer (charge generation layer, charge transport layer, single layer type photosensitive layer), but usually a coating solution containing the material constituting each layer (coating solution for charge generation layer) , A charge transport layer coating solution, and a single-layer photosensitive layer coating solution) by applying a coating and drying process for each layer in succession using a known coating method on the undercoat layer. Is done.

For example, in the charge generation layer, a charge generation material, a binder resin, and other components are dissolved or dispersed in a solvent to prepare a coating solution. In the case of a reverse lamination type photosensitive layer, it can be obtained by coating on a charge transport layer and drying.
In addition, for example, the charge transport layer is prepared by dissolving or dispersing a charge transport material, a binder resin, and other components in a solvent to prepare a coating solution. Further, in the case of a reverse lamination type photosensitive layer, it can be obtained by coating on an undercoat layer and drying.
Further, the single-layer type photosensitive layer is prepared by dissolving or dispersing a charge generating substance, a charge transporting substance, a binder resin, and other components in a solvent to prepare a coating solution, which is coated on the undercoat layer and dried. Obtainable.

In this case, any solvent (or dispersion medium) used for dissolving the binder resin and preparing the coating solution can be used as long as the effects of the present invention are not significantly impaired. For example, saturated aliphatic solvents such as pentane, hexane, octane and nonane; aromatic solvents such as toluene, xylene and anisole; halogenated aromatic solvents such as chlorobenzene, dichlorobenzene and chloronaphthalene; dimethyl Amide solvents such as formamide and N-methyl-2-pyrrolidone; Alcohol solvents such as methanol, ethanol, isopropanol, n-butanol and benzyl alcohol; Aliphatic polyhydric alcohols such as glycerin and ethylene glycol; Acetone, cyclohexanone, Chain, branched and cyclic ketone solvents such as methyl ethyl ketone and 4-methoxy-4-methyl-2-pentanone; ester solvents such as methyl formate, ethyl acetate and n-butyl acetate; methylene chloride, chloroform, 1, 2 ―Halo such as dichloroethane Hydrocarbonated solvents: linear ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve; acetonitrile, dimethyl sulfoxide, sulfolane, hexamethylphosphoric acid Examples include aprotic polar solvents such as triamide; nitrogen-containing compounds such as n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, and triethylamine; mineral oil such as ligroin; water and the like. Among these, those that do not dissolve the undercoat layer are preferably used.
In addition, these solvents may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  In the case of a coating solution for a single layer type photoreceptor and a charge transport layer, the coating solution for forming a layer has a solid content concentration of usually 5% by weight or more, preferably 10% by weight or more, and usually 40% by weight. Hereinafter, it is preferably used in the range of 35% by weight or less. Further, the viscosity of the coating solution is usually 10 mPa · s or more, preferably 50 mPa · s or more, and usually 500 mPa · s or less, preferably 400 mPa · s or less.

  On the other hand, in the case of the coating solution for the charge generation layer, the solid content concentration is usually 0.1% by weight or more, preferably 1% by weight or more, and usually 15% by weight or less, preferably 10% by weight or less. Is preferably used. Furthermore, the viscosity of the coating solution is preferably 0.01 mPa · s or more, preferably 0.1 mPa · s or more, and usually 20 mPa · s or less, preferably 10 mPa · s or less.

  There are no restrictions on the application method of the coating liquid, but for example, dip coating method, spray coating method, spinner coating method, bead coating method, wire bar coating method, blade coating method, roller coating method, air knife coating method, curtain coating method Other known coating methods can also be used.

  Although there is no restriction | limiting in the drying method of a coating liquid, It is preferable to heat-dry in the temperature range of 30-200 degreeC for 1 minute to 2 hours, without a wind or ventilation, after the touch drying at room temperature. The heating temperature may be constant or may be changed while drying.

[V. Other layers]
A layer other than the undercoat layer and the photosensitive layer may be formed on the electrophotographic photoreceptor of the present invention.
For example, a protective layer may be provided on the outermost surface layer of the photosensitive member for the purpose of preventing the photosensitive layer from being worn out or preventing or reducing the deterioration of the photosensitive layer due to a discharge substance generated from a charger or the like. The protective layer is formed, for example, by containing a conductive material in an appropriate binder resin, or a charge such as a triphenylamine skeleton as described in JP-A-9-190004 and JP-A-10-252377. A copolymer using a compound having a transport ability can be used.

As the conductive material, TPD (N, N′-diphenyl-N, N′-bis- (m-
It is possible to use aromatic amino compounds such as (tolyl) benzidine), metal oxides such as antimony oxide, indium oxide, tin oxide, titanium oxide, tin oxide-antimony oxide, aluminum oxide, and zinc oxide. It is not limited to. In addition, a conductive material may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Examples of the binder resin used for the protective layer include 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 copolymer of the above resin with a skeleton having a charge transporting ability such as a triphenylamine skeleton as described in JP-A-9-190004 and JP-A-10-252377 can be used. In addition, this binder resin may also be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Furthermore, it is preferable that the protective layer is configured to have an electric resistance of 10 ⁹ to 10 ¹⁴ Ω · cm. If the electric resistance is higher than 10 ¹⁴ Ω · cm, the residual potential may increase and an image with much fog may be formed. On the other hand, if the electric resistance is lower than 10 ⁹ Ω · cm, the image may be blurred or the resolution may be reduced.
Also, the protective layer must be configured so as not to substantially impede transmission of light irradiated for image exposure.

  In addition, fluorine resin, silicone resin, polyethylene resin, polystyrene resin, etc. are used for the surface layer for the purpose of reducing frictional resistance and abrasion on the surface of the photoconductor and increasing the transfer efficiency of the toner from the photoconductor to the transfer belt and paper. May be included. Moreover, the particle | grains which consist of these resin, and the particle | grains of an inorganic compound may be included.

  In addition, although there is no restriction | limiting in the formation method of layers other than these undercoat layers and a photosensitive layer, Usually, similarly to the photosensitive layer mentioned above, the coating liquid containing the material which comprises each layer is used for a well-known coating method. It is formed by repeating the coating and drying process for each layer and coating sequentially.

[VI. Advantages of electrophotographic photosensitive member of the present invention]
The electrophotographic photoreceptor of the present invention has good electrical characteristics such as sensitivity and residual potential even when the environment such as temperature and humidity changes. Therefore, favorable image formation can be realized in various environments.

[VII. Image forming apparatus]
Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention (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. 5, the image forming apparatus includes an electrophotographic photosensitive member 1, a charging device (charging means) 2, an exposure device (exposure means; image exposure means) 3, a developing device (developing means) 4, and a transfer device (transfer). Means) 5, and a cleaning device (cleaning means) 6 and a fixing device (fixing means) 7 are provided as necessary.

  In the image forming apparatus of the present invention, the electrophotographic photosensitive member of the present invention described above is provided as the photosensitive member 1. That is, the image forming apparatus of the present invention comprises an electrophotographic photosensitive member, a charging means for charging the electrophotographic photosensitive member, and image exposure for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image. In an image forming apparatus comprising: a developing unit that develops the electrostatic latent image with a toner; and a transfer unit that transfers the toner to a transfer target, the electrophotographic photosensitive member is formed on a conductive support. An electrophotographic photosensitive member having an undercoat layer containing metal oxide particles and a binder resin, and a photosensitive layer formed on the undercoat layer, wherein the undercoat layer comprises 7 methanol and 1-propanol. : The volume average particle diameter of the metal oxide particles in a liquid dispersed in a solvent mixed at a weight ratio of 3 is measured by a dynamic light scattering method, and the cumulative average is 90%. The diameter is 0.3 μm or less in the photosensitive layer Further, a compound containing the compound represented by the above formula (I) (arylamine compound according to the present invention) is provided.

  The electrophotographic photosensitive member 1 is not particularly limited as long as it is the above-described electrophotographic photosensitive member of the present invention, but in FIG. 5, 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. In order to effectively utilize the effects of the present invention, the charging device is preferably disposed in contact with the electrophotographic photoreceptor 1. In FIG. 5, a roller-type charging device (charging roller) is shown as an example of the charging device 2, but a corona charging device such as a corotron or a scorotron, a contact charging device such as a charging brush, etc. are often used.

  In many cases, the electrophotographic photoreceptor 1 and the charging device 2 are designed to be removable from the main body of the image forming apparatus as a cartridge including both of them (hereinafter, referred to as a photoreceptor cartridge as appropriate). For example, when the electrophotographic photoreceptor 1 or the charging device 2 deteriorates, the photoreceptor cartridge can be removed from the image forming apparatus main body, and another new photosensitive cartridge can be mounted on the image forming apparatus main body. ing. Also, the toner described later is often stored in the toner cartridge and designed to be removable from the main body of the image forming apparatus. When the toner in the used toner cartridge runs out, this toner cartridge is removed. It can be removed from the main body of the image forming apparatus and another new toner cartridge can be mounted. Further, a cartridge equipped with all of the electrophotographic photosensitive member 1, the charging device 2, and the toner may be used.

  The type of exposure apparatus 3 is not particularly limited as long as it can form an electrostatic latent image on the photosensitive surface of the electrophotographic photosensitive member 1 by performing exposure (image exposure) on the electrophotographic photosensitive member 1. Absent. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, and LEDs (light emitting diodes). Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, if the exposure is performed with monochromatic light having a wavelength of 780 nm, monochromatic light having a wavelength of 600 nm to 700 nm, slightly short wavelength, or monochromatic light having a wavelength of 380 nm to 600 nm. Good. Among these, it is preferable to expose with monochromatic light having a short wavelength of 350 nm to 600 nm, and more preferably to expose with monochromatic light having a wavelength of 380 nm to 500 nm.

  The developing device 4 develops the electrostatic latent image. The type is not particularly limited, and any apparatus such as a dry development system such as cascade development, one-component conductive toner development, two-component magnetic brush development, or a wet development system can be used. In FIG. 5, 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. The 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 silicone resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.

  The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

  The regulating member 45 is formed of a resin blade such as silicone 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 a variety of shapes ranging from a nearly spherical shape to a potato-like spherical shape. 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 a toner image formed on the electrophotographic photosensitive member 1 to a transfer material (transferred material, paper, medium). Transfer to P. In the present invention, it is effective when the transfer device 5 is placed in contact with the photoreceptor via a transfer material.

  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. 5 shows an example in which a heating device 73 is provided inside the upper fixing member 71. As the upper and lower fixing members 71 and 72, a known heat fixing member 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 coated with a fluororesin, or a fixing sheet is used. be able to. Further, each of the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

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

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 have a configuration capable of performing, 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.

  When the photosensitive member 1 is configured as a cartridge in combination with the charging device 2 as described above, it is preferable that the photosensitive member 1 further includes a developing device 4. Further, in addition to the photosensitive member 1, if necessary, 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. In this case, the cartridge may be configured as an integrated cartridge (electrophotographic cartridge), and the electrophotographic cartridge may be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. That is, the electrophotographic cartridge of the present invention includes an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, and an image exposing unit for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image. At least one of developing means for developing the electrostatic latent image with toner, transfer means for transferring the toner to a transfer target, and cleaning means for collecting the toner adhering to the electrophotographic photosensitive member. An electrophotographic cartridge having an undercoat layer containing metal oxide particles and a binder resin on a conductive support, and a photosensitive layer formed on the undercoat layer, as the electrophotographic photoreceptor. An electrophotographic photoreceptor, wherein the undercoat layer is measured by a dynamic light scattering method of the metal oxide particles in a liquid in which methanol and 1-propanol are mixed in a solvent mixed at a weight ratio of 7: 3. The The product average particle diameter is 0.1 μm or less and the cumulative 90% particle diameter is 0.3 μm or less. In the photosensitive layer, the compound represented by the above formula (I) (the arylamine according to the present invention) It is preferable to include a compound containing a compound).

  In this case, similarly to the cartridge described in the above embodiment, for example, when the electrophotographic photosensitive member 1 or other members deteriorates, the electrophotographic cartridge is removed from the image forming apparatus main body, and another new electrophotographic cartridge is imaged. By attaching to the forming apparatus main body, maintenance and management of the image forming apparatus is facilitated.

According to the image forming apparatus and the electrophotographic cartridge of the present invention, high quality images can be formed in various environments. That is, since the electrophotographic photosensitive member according to the present invention exhibits excellent electrical characteristics such as high sensitivity and low residual potential without depending on the environment such as temperature and humidity, the image forming apparatus and the electrophotographic cartridge of the present invention are provided. If used, it is possible to perform high-quality image formation in which image defects are suppressed regardless of environmental conditions.
Conventionally, when the transfer device 5 is placed in contact with the photosensitive member via a transfer material, the image quality is likely to deteriorate. However, the image forming apparatus and the electrophotographic cartridge according to the present invention have such a quality deterioration. This is effective because there is little possibility of occurrence.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these, unless it deviates from the summary. In the description of Examples, “part” means “part by weight” unless otherwise specified.

[Example 1]
[Coating liquid for undercoat layer]
A rutile type titanium oxide having an average primary particle diameter of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by weight of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide were added to a Henschel mixer. 1 kg of a raw slurry obtained by mixing 50 parts of surface-treated titanium oxide obtained by mixing with 120 parts of methanol, and using a zirconia bead having a diameter of about 100 μm (YTZ manufactured by Nikkato Co., Ltd.) as a dispersion medium, a mill volume of about 0 Using a 15-liter Ultra Apex Mill (UAM-015 type) manufactured by Kotobuki Kogyo Co., Ltd., a titanium oxide dispersion was prepared by dispersing for 1 hour in a liquid circulation state with a rotor peripheral speed of 10 m / second and a liquid flow rate of 10 kg / hour. .

The titanium oxide dispersion, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula Compound represented by (B)] / Hexamethylenediamine [Compound represented by the following formula (C)] / Decamethylene dicarboxylic acid [Compound represented by the following formula (D)] / Octadecamethylene dicarboxylic acid [Formula (E After the polyamide pellets are dissolved by stirring and mixing the pellets of the copolymerized polyamide having a composition molar ratio of 60% / 15% / 5% / 15% / 5%] , Ultrasonic dispersion with an ultrasonic generator with an output of 1200 W is performed for 1 hour, and a PTFE membrane filter (a) with a pore diameter of 5 μm The weight ratio of the surface-treated titanium oxide / copolymerized polyamide was 3/1, and the weight ratio of the mixed solvent of methanol / 1-propanol / toluene was 7/1/2. Thus, an undercoat layer forming coating solution A having a solid content concentration of 18.0% by weight was obtained.
Table 3 shows the particle size distribution of the undercoat layer forming coating solution A measured using the UPA.

  This undercoat layer forming coating solution A is dip coated on an anodized aluminum cylinder (outer diameter 30 mm, length 260.5 mm, thickness 1.0 mm), and the film thickness after drying is 1.5 μm. An undercoat layer was provided so as to be.

94.2 cm ^{2 of} this undercoat layer was immersed in a mixed solution of 70 g of methanol and 30 g of 1-propanol, and subjected to ultrasonic treatment for 5 minutes by an ultrasonic oscillator with an output of 600 W to obtain an undercoat layer dispersion. When the particle size distribution of the metal oxide particles therein was measured by UPA, the volume average particle size was 0.09 μm, and the cumulative 90% particle size was 0.12 μm.

Next, as a charge generation material, 20 parts of D-type oxytitanium phthalocyanine and 280 parts of 1,2-dimethoxyethane were mixed and pulverized with a sand grind mill for 2 hours for atomization dispersion treatment.
Subsequently, polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denkabutyral” # 6000C), 253 parts of 1,2-dimethoxyethane and 4-methoxy-4-methyl-2 were added to this refined treatment solution. -A binder liquid obtained by dissolving in a mixed solution with 85 parts of pentanone and 230 parts of 1,2-dimethoxyethane were mixed to prepare a dispersion (charge generating material).

The aluminum cylinder provided with the undercoat layer is dip coated on this dispersion (charge generation material), and a charge generation layer is prepared so that the film thickness after drying is 0.3 μm (0.3 g / m ² ). did.
Next, 50 parts of the following compound (CT-1) as a charge transport material,

100 parts of polycarbonate (PC1: viscosity average molecular weight of about 30,000; m: n = 1: 1) having the following structure as a repeating unit as a binder resin;

8 parts of an antioxidant having the following structure:

A liquid obtained by dissolving 0.05 part of silicone oil (trade name: KF96 Shin-Etsu Chemical Co., Ltd.) as a leveling agent in 640 parts of a mixed solvent of tetrahydrofuran / toluene (weight ratio 8/2) is added to the charge generation layer described above. The photosensitive drum E1 having a laminated photosensitive layer was obtained by dip coating so that the film thickness after drying was 20 μm.

The photosensitive layer 94.2 cm ² of the obtained photoreceptor E1 was immersed in 100 cm ³ of tetrahydrofuran, dissolved and removed by ultrasonic treatment for 5 minutes with an ultrasonic oscillator with an output of 600 W, and the same part was treated with 70 g of methanol and 1-propanol. It was immersed in 30 g of a mixed solution, and subjected to ultrasonic treatment for 5 minutes with an ultrasonic oscillator with an output of 600 W to obtain an undercoat layer dispersion, and the particle size distribution of the metal oxide particles in the dispersion was measured with the UPA. However, the volume average particle size was 0.08 μm, and the cumulative 90% particle size was 0.11 μm.

[Example 2]
A photoconductor E2 was obtained in the same manner as in Example 1 except that the following compound (CT-2) was used instead of the compound (CT-1) as a charge transport material.

[Example 3]
A photoconductor E3 was obtained in the same manner as in Example 1 except that the following compound (CT-3) was used instead of the compound (CT-1) as a charge transport material.

[Example 4]
Instead of using the compound (CT-1) as the charge transporting material, a composition (CT-4) of an arylamine compound represented by the following structural formula described in Example 1 of JP-A-2002-080432 A photoconductor E4 was obtained in the same manner as in Example 1 except that was used.

[Example 5]
A coating liquid B for forming an undercoat layer was prepared in the same manner as in Example 1 except that zirconia beads having a diameter of about 50 μm (YTZ manufactured by Nikkato Co., Ltd.) were used as a dispersion medium when dispersed by an ultra apex mill. The physical properties were measured in the same manner as in Example 1. The results are shown in Table 3.

The undercoat layer forming coating solution B is dip coated on an anodized aluminum cylinder (outer diameter 30 mm, length 260.5 mm, thickness 1.0 mm), and the film thickness after drying becomes 1.5 μm. Thus, an undercoat layer was provided.
94.2 cm ^{2 of} this undercoat layer was immersed in a mixed solution of 70 g of methanol and 30 g of 1-propanol, and subjected to ultrasonic treatment for 5 minutes by an ultrasonic oscillator with an output of 600 W to obtain an undercoat layer dispersion. When the particle size distribution of the metal oxide particles therein was measured by UPA as in Example 1, the volume average particle size was 0.08 μm, and the cumulative 90% particle size was 0.12 μm.

On the resulting undercoat layer, a charge generation layer and a charge transport layer were formed in the same manner as in Example 1 to obtain a photoreceptor E5.
The photosensitive layer 94.2 cm ² of the obtained photoreceptor E5 was immersed in 100 cm ³ of tetrahydrofuran, dissolved and removed by ultrasonic treatment for 5 minutes with an ultrasonic oscillator with an output of 600 W, and the same part was treated with 70 g of methanol and 1-propanol. It is immersed in 30 g of a mixed solution, and subjected to ultrasonic treatment for 5 minutes by an ultrasonic oscillator with an output of 600 W to obtain a subbing layer dispersion, and the particle size distribution of metal oxide particles in the dispersion is the same as in Example 1. When measured by UPA, the volume average particle size was 0.08 μm, and the cumulative 90% particle size was 0.12 μm.

[Example 6]
Undercoat layer forming coating solution C was prepared in the same manner as in Example 5 except that the rotor peripheral speed at the time of dispersion by the ultra apex mill was set to 12 m / second, and the physical properties were measured in the same manner as in Example 1. did. The results are shown in Table 3.

Using this undercoat layer forming coating solution C, an undercoat layer was provided by dip coating on an aluminum cylinder in the same manner as in Example 1.
94.2 cm ^{2 of} this undercoat layer was immersed in a mixed solution of 70 g of methanol and 30 g of 1-propanol, and subjected to ultrasonic treatment for 5 minutes by an ultrasonic oscillator with an output of 600 W to obtain an undercoat layer dispersion. When the particle size distribution of the metal oxide particles therein was measured by UPA similar to that of Example 1, the volume average particle size was 0.08 μm, and the cumulative 90% particle size was 0.11 μm.

Next, a photoreceptor E6 was obtained in the same manner as in Example 1 except that the undercoat layer forming coating solution C was used.
The photosensitive layer 94.2 cm ² of the obtained photoreceptor E6 was immersed in 100 cm ³ of tetrahydrofuran, dissolved and removed by ultrasonic treatment for 5 minutes with an ultrasonic oscillator with an output of 600 W, and the same part was treated with 70 g of methanol and 1-propanol. It is immersed in 30 g of a mixed solution, and subjected to ultrasonic treatment for 5 minutes by an ultrasonic oscillator with an output of 600 W to obtain a subbing layer dispersion, and the particle size distribution of metal oxide particles in the dispersion is the same as in Example 1. When measured by UPA, the volume average particle size was 0.08 μm, and the cumulative 90% particle size was 0.11 μm.

[Comparative Example 1]
A photoreceptor P1 was obtained in the same manner as in Example 1 except that the following compound (CT-5) was used instead of the compound (CT-1) as the charge transport material.

[Comparative Example 2]
A photoconductor P2 was obtained in the same manner as in Example 1 except that the following compound (CT-6) was used instead of the compound (CT-1) as a charge transport material.

[Comparative Example 3]
A slurry obtained by mixing a rutile type titanium oxide having an average primary particle diameter of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by weight of methyldimethoxysilane with respect to the titanium oxide in a ball mill is dried, and further methanol is added. The hydrophobically treated titanium oxide obtained by washing and drying in (1) was dispersed in a methanol / 1-propanol mixed solvent by a ball mill to form a hydrophobized titanium oxide dispersion slurry, and the dispersed slurry, methanol / 1-propanol / toluene (weight ratio 7/1/2) mixed solvent and ε-caprolactam / bis (4-amino-3-methylcyclohexyl) methane / hexamethylenediamine / decamethylenedicarboxylic acid / octadecamethylene Copolymer poly consisting of dicarboxylic acid (composition mol%: 60/15/5/15/5) The solid content containing the hydrophobically treated titanium oxide / copolymerized polyamide in a weight ratio of 3/1 is obtained by stirring and mixing with the imide pellets while heating to dissolve the polyamide pellets, followed by ultrasonic dispersion treatment. A coating liquid D for forming an undercoat layer having a concentration of 18.0% was prepared.

Using this undercoat layer forming coating solution D, an undercoat layer was provided by dip coating on an aluminum cylinder in the same manner as in Example 1.
94.2 cm ^{2 of} this undercoat layer was immersed in a mixed solution of 70 g of methanol and 30 g of 1-propanol, and subjected to ultrasonic treatment for 5 minutes by an ultrasonic oscillator with an output of 600 W to obtain an undercoat layer dispersion. When the particle size distribution of the metal oxide particles therein was measured by UPA as in Example 1, the volume average particle size was 0.11 μm and the cumulative 90% particle size was 0.20 μm.

Next, a photoreceptor P3 was obtained in the same manner as in Example 1 except that the undercoat layer forming coating solution D was used.
The photosensitive layer 94.2 cm ² of the obtained photoreceptor P3 was immersed in 100 cm ³ of tetrahydrofuran, dissolved and removed by ultrasonic treatment for 5 minutes with an ultrasonic oscillator with an output of 600 W, and the same part was treated with 70 g of methanol and 1-propanol. It is immersed in 30 g of a mixed solution, and subjected to ultrasonic treatment for 5 minutes by an ultrasonic oscillator with an output of 600 W to obtain a subbing layer dispersion, and the particle size distribution of metal oxide particles in the dispersion is the same as in Example 1. When measured by UPA, the volume average particle size was 0.11 μm, and the cumulative 90% particle size was 0.18 μm.

[Comparative Example 4]
A photoconductor P4 was obtained in the same manner as in Comparative Example 3, except that the compound (CT-3) was used instead of the compound (CT-1) as the charge transport material.

[Evaluation of electrical characteristics]
The electrophotographic photosensitive member produced in the Examples and Comparative Examples was prepared by electrophotographic characteristic evaluation apparatus produced according to the standard of the Electrophotographic Society (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404-405). In accordance with the following procedure, the electrical characteristics were evaluated by a cycle of charging (negative polarity), exposure, potential measurement, and static elimination.

In an environment of a temperature of 25 ° C. and a humidity of 50%, and in an environment of a temperature of 5 ° C. and a humidity of 10%, the photosensitive member is charged so that the initial surface potential is −700 V, and the light of the halogen lamp is 780 nm with an interference filter. A monochromatic light was irradiated, and the irradiation energy (half exposure energy) when the surface potential was −350 V was measured as sensitivity (E1 / 2) (μJ / cm ² ). Further, the post-exposure surface potential (VL1) after 100 ms when the exposure light was irradiated at an intensity of 1.0 μJ / cm ² was measured (−V). Further, after setting the initial surface potential to −700 V, the surface potential after being left in a dark place for 5 seconds was measured, and the difference was defined as dark decay (DD).
The results are shown in Table 4A (temperature 25 ° C., humidity 50%) and Table 4B (temperature 5 ° C., humidity 10%). In the columns of the undercoat layer in Tables 4A and 4B, “α” represents the undercoat layer forming dispersion A, B, or C, and “β” represents the undercoat dispersion D.

  As is apparent from the results of Tables 3, 4A, and 4B, it can be seen that the photoconductor of the present invention has a relatively small change in electrical characteristics in order to maintain high responsiveness even at low temperatures.

[Image Evaluation]
A drum cartridge (contact charging roller member as an integrated cartridge) of a monochrome page printer (“LaserJet 4200” manufactured by Hewlett-Packard) with a gear attached to the electrophotographic photosensitive member produced in the examples and comparative examples, and A4 output at 33 sheets per minute , Blade cleaning member, and developing member), purchase and install recycled toner from the market, print the image, and visually check the image density of the black solid part and the image defect in the black solid image and white solid image evaluated.
The results are shown in Table 5.

  As is apparent from the results in Table 5, when image formation is performed using the photoreceptor of the present invention, high-quality image formation without fogging or black spots is possible in both ambient and low temperature environments. I understand.

  The present invention can be used in any industrial field, and in particular, can be suitably used for electrophotographic printers, facsimiles, copying machines, and the like.

It is a longitudinal cross-sectional view which represents typically the structure of the wet stirring ball mill which concerns on one Embodiment of this invention. It is an expanded longitudinal cross-sectional view which represents typically the mechanical seal used with the wet stirring ball mill which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view which represents typically another example of the wet stirring ball mill which concerns on one Embodiment of this invention. FIG. 4 is a transverse sectional view schematically showing a separator of the wet stirring ball mill shown in FIG. 3. 1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus including an electrophotographic photosensitive member of the present invention.

Explanation of symbols

1 Photoconductor 2 Charging device (charging roller)
DESCRIPTION OF SYMBOLS 3 Exposure apparatus 4 Developing apparatus 5 Transfer apparatus 6 Cleaning apparatus 7 Fixing apparatus 14 Separator 15 Shaft 16 Jacket 17 Stator 19 Discharge path 21 Rotor 24 Pulley 25 Rotary joint 26 Raw material slurry supply port 27 Screen support 28 Screen 29 Product slurry extraction port 31 Disk 32 Blade 35 Valve element 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 45 Restricting member 71 Upper fixing member (fixing roller)
72 Lower fixing member (fixing roller)
73 Heating device 100 Sealing 101 Mating ring 102 Spring 103 Fitting groove 104 O-ring 105 Shaft 106 Separator 107 Spacer 108 Rotor 109 Stopper 110 Screw 111 Discharge path 112 Hole 113 Spacer 114 Blade fitting groove 115 Disc 116 Blade T Toner P Transfer Material (paper, medium)

Claims (5)

In an electrophotographic photoreceptor having an undercoat layer containing metal oxide particles and a binder resin on a conductive support, and a photosensitive layer formed on the undercoat layer,
The volume average particle size of the undercoat layer measured by the dynamic light scattering method of the metal oxide particles in a liquid in which methanol and 1-propanol are mixed in a solvent mixed at a weight ratio of 7: 3 is 0. .1 μm or less and a 90% cumulative particle size is 0.3 μm or less,
An electrophotographic photosensitive member comprising a compound represented by the following formula (I) in the photosensitive layer.

(In the formula (I), Ar ^{1 to} Ar ⁶ each independently represents an aromatic residue which may have a substituent, X represents an organic residue which may have a substituent, R ¹ to R ⁴ also have independently substituent represents an unsaturated group, n ₁ is 1 or 2, n ₀ and n ₂ ~n ₆ represents an integer of 0 to 2.) 2. The electrophotographic photoreceptor according to claim 1, wherein in the formula (I), Ar ^{1 to} Ar ⁶ are all benzene residues. The electrophotographic photosensitive member according to claim 1, wherein R ^{1 to} R ⁴ are represented by the following formula (II) in the formula (I).

(In the formula (II), R ^{5 to} R ⁹ each independently represents a hydrogen atom or an alkyl group or an aryl group which may have a substituent, and n ₇ represents an integer of 0 to 5. ) The electrophotographic photosensitive member according to any one of claims 1 to 3,
Charging means for charging the electrophotographic photosensitive member;
Image exposure means for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image;
Developing means for developing the electrostatic latent image with toner;
An image forming apparatus comprising: a transfer unit that transfers the toner to a transfer target. The electrophotographic photosensitive member according to any one of claims 1 to 3,
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, developing means for developing the electrostatic latent image with toner, the toner An electrophotographic cartridge comprising: transfer means for transferring the toner to a transfer member; and at least one of cleaning means for collecting the toner adhering to the electrophotographic photosensitive member.

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