JP2006058573A - Manufacturing method of coating liquid for under coat layer, electrophotographic photoreceptor and electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of an under coat layer coating liquid which can secure sufficient electric properties on the under coat layer, by stabilizing the coating liquid for forming the under coat layer of an electrophotographic photoreceptor. <P>SOLUTION: This is the manufacturing method of a coating liquid for forming an under coat layer between the conductive base and the photosensitive layer of an electrophotographic photoreceptor. It has a dispersion step of obtaining a dispersed liquid by dispersing the mixture containing fine metal oxide particles, binder resin, and a solvent, and an ion content removing step of removing the ion contents in the dispersed liquid to obtain a coating liquid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a coating liquid for forming an undercoat layer, an electrophotographic photoreceptor, and an electrophotographic apparatus.

  The electrophotographic system uses an electrophotographic photosensitive member to perform image forming processes such as charging, exposure, development, and transfer, and because high-speed and high-quality printing is possible, copying machines, laser beam printers, etc. It is widely applied to the electrophotographic apparatus.

  In recent years, as an electrophotographic photoreceptor used in such an electrophotographic apparatus, an organic photoreceptor in which a photosensitive layer is formed using a photoconductive organic material on a conductive substrate has become the mainstream. In the case of an organic photoreceptor, an undercoat layer is often provided between the conductive substrate and the photosensitive layer.

  The undercoat layer described above plays an important role in improving the electrophotographic characteristics of the electrophotographic photosensitive member as well as preventing the inflow of charges from the conductive substrate to the photosensitive layer. For example, if the charge accumulation property of the undercoat layer is high, the residual potential of the electrophotographic photosensitive member increases when the image forming process is repeatedly performed in the electrophotographic apparatus.

  In addition, the electrical characteristics of the electrophotographic photosensitive member are easily affected by temperature, humidity, and the like, and the charging potential may vary depending on the usage environment. Further, in recent years, a contact charging type charging device has been used as a charging device for an electrophotographic apparatus in place of corotron or the like, but in the case of the contact charging type, the charging potential of the electrophotographic photosensitive member is made non-uniform. Resulting image defects may occur. Such fluctuations and non-uniformization of the charging potential often depend on the properties of the undercoat layer.

Therefore, various studies have been made to improve the electrical characteristics of the undercoat layer. For example, the use of an electrophotographic photoreceptor in which acicular titanium oxide fine particles having a predetermined volume resistance value are contained in the undercoat layer is used. It has been proposed (see, for example, Patent Document 1).
JP 7-84393 A

However, even with the above conventional electrophotographic photosensitive member, it is difficult to sufficiently suppress the increase of the residual potential and the fluctuation and non-uniformization of the charged potential, and there is still room for improvement as it can be put to practical use. There is. That is, when fine particles such as titanium oxide fine particles are used as the constituent material of the undercoat layer, the fine particles are likely to aggregate or settle in the undercoat layer forming coating solution, and the fine particles are dispersed in the formed undercoat layer. Tends to be non-uniform. Therefore, even when specific titanium oxide fine particles as described in Patent Document 1 are used, the effect of the use cannot be sufficiently exhibited. Therefore, in order to improve the electrical characteristics of the undercoat layer, it is important not only to change the constituent material of the undercoat layer but also to establish a method for improving the stability of the coating solution. Such a method is not necessarily considered enough.

  The present invention has been made in view of such circumstances, and its purpose is to improve the stability of a coating solution used for forming an undercoat layer of an electrophotographic photosensitive member, and to form an undercoat layer to be formed. It is an object of the present invention to provide a method for producing a coating liquid for forming an undercoat layer capable of imparting sufficient electrical characteristics. Another object of the present invention is to provide an electrophotographic photosensitive member and an electrophotographic apparatus capable of suppressing a rise in residual potential and fluctuation or nonuniformity of a charged potential.

  As a result of intensive studies to achieve the above object, the present inventors have found that destabilization of the coating liquid for forming the undercoat layer is caused by ionic components present in the coating liquid. As a result of further research based on such knowledge, when preparing a coating liquid for forming an undercoat layer, a coating liquid obtained by dispersing a mixture of specific components and removing ionic components from the dispersion liquid It has been found that the stability of the undercoat layer can be sufficiently improved, and that sufficient electrical properties can be imparted to the undercoat layer formed using the coating solution, and the present invention has been completed.

  That is, the method for producing a coating solution for forming an undercoat layer of the present invention is a method for producing a coating solution for forming an undercoat layer between a conductive substrate and a photosensitive layer of an electrophotographic photoreceptor, A first step of obtaining a dispersion by dispersing a mixture containing oxide fine particles, a binder resin, and a solvent; and a second step of obtaining an application liquid by removing ionic components in the dispersion. It is characterized by that.

  According to the present invention, by dispersing the mixture of the metal oxide fine particles, the binder resin, and the solvent, and removing the ionic components from the dispersion, the ionic components derived from the components themselves such as the metal oxide fine particles, Furthermore, since ionic components generated by the dispersion treatment are removed, aggregation and sedimentation of metal oxide fine particles derived from these ionic components can be suppressed, and the stability of the resulting coating liquid can be sufficiently improved. Therefore, by forming the undercoat layer using the coating solution thus obtained, the dispersion state of the metal oxide fine particles in the undercoat layer is sufficiently uniformed, and the undercoat layer has a high level of electrical characteristics. It becomes possible to grant.

  Further, in the second step described above, based on the correlation between the concentration of the ionic component of the coating solution obtained in advance and the conductivity, the conductivity of the obtained coating solution is set to a predetermined value or less. It is preferable to remove the ionic component. Thus, by adopting the electrical conductivity of the coating liquid as an index when removing the ionic component, the content of the ionic component in the coating liquid can be reliably reduced. Therefore, since it becomes possible to improve the stability of the coating liquid at a high level, desired electrical characteristics can be imparted to the formed undercoat layer.

  Furthermore, in the present invention, the coating solution obtained on the basis of the correlation between the concentration of the ionic component of the coating solution obtained in advance and the conductivity of the coating solution after a predetermined time has passed since the second step. There may be further provided a third step of removing the ion component so that the electrical conductivity of the liquid crystal becomes a predetermined value or less. As described above, by further including the third step of removing the ionic component generated by the change with time of the coating solution after the second step, it is possible to suppress a decrease in the stability of the coating solution due to the pot life. Thereby, the stability of the coating solution is improved, so that the coating solution can be used for a long time.

  In the second and / or third steps described above, the ion component removing means is not particularly limited, and for example, an ion exchange resin can be used. When using an ion exchange resin, it is preferable to select the kind and combination of ion exchange resins according to the ion component to be removed. In particular, when a metal ion is contained in the ionic component, it is preferable to remove the ionic component using a chelate resin. Thereby, since the removal efficiency of an ionic component is raised more, the stability of a coating liquid is further improved.

  In the present invention, it is preferable to use at least one selected from tin oxide, titanium oxide and zinc oxide as metal oxide fine particles, and use metal oxide fine particles having an average primary particle size of 0.5 μm or less. Is preferred. When the average primary particle size of the metal oxide fine particles is 0.5 μm or less, the dispersibility of the metal oxide fine particles can be further improved, so that excellent electrical characteristics can be imparted to the undercoat layer.

  Moreover, in this invention, it is preferable to use the metal oxide fine particle surface-treated with the surface treating agent as the metal oxide fine particle. In addition, when metal oxide fine particles surface-treated with a surface treatment agent are used in a conventional coating solution for forming an undercoat layer, an unreacted surface treatment agent that was not chemically adsorbed on the surface of the metal oxide fine particles, The stability of the coating solution is impaired by ionic components derived from the surface treatment agent such as a decomposition product of the generated surface treatment agent. On the other hand, in the present invention, the ionic component derived from the surface treatment agent is removed after the dispersion treatment, so that the dispersion of the metal oxide fine particles by the surface treatment is not inhibited by the ionic component without inhibiting the stability of the coating solution. The effect of improving the properties can be effectively obtained, and a higher level of electrical characteristics can be imparted to the undercoat layer.

  Furthermore, in this invention, it is preferable to use at least 1 sort (s) chosen from a silane coupling agent, a zirconia coupling agent, a titanate coupling agent, and an aluminate coupling agent as a surface treating agent. By using the metal oxide fine particles surface-treated with such a coupling agent, the dispersibility of the metal oxide fine particles can be further improved, so that a high level of electrical characteristics can be imparted to the undercoat layer.

  The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor comprising a conductive substrate and an undercoat layer formed on the conductive substrate, wherein the undercoat layer is the production of the present invention described above. It is formed using the coating liquid for undercoat layer formation obtained by the method, It is characterized by the above-mentioned. The undercoat layer of the electrophotographic photoreceptor of the present invention is formed using the coating solution whose stability has been improved by the above-described production method of the present invention, and therefore has sufficient electrical characteristics. Therefore, the electrophotographic photosensitive member of the present invention can suppress the increase of the residual potential and the fluctuation or nonuniformity of the charging potential.

  Further, the electrophotographic apparatus of the present invention includes the above-described electrophotographic photosensitive member of the present invention, a charging device that charges the surface of the electrophotographic photosensitive member, and an exposure device that exposes the electrophotographic photosensitive member to form an electrostatic latent image. And a developing device that develops the electrostatic latent image with toner, and a transfer device that transfers the developed toner image to a transfer medium. In the electrophotographic apparatus of the present invention, by including the electrophotographic photosensitive member of the present invention in which the increase of the residual potential and the fluctuation or nonuniformity of the charged potential are suppressed, image defects such as black spots are not generated for a long period of time. Good image quality can be obtained.

  According to the present invention, it is possible to improve the stability of a coating solution used for forming an undercoat layer of an electrophotographic photosensitive member, and to form an undercoat layer capable of imparting sufficient electrical characteristics to the formed undercoat layer. The manufacturing method of the coating liquid can be provided. In addition, it is possible to provide an electrophotographic photosensitive member and an electrophotographic apparatus that can suppress an increase in residual potential and fluctuation or nonuniformity in charging potential.

Preferred embodiments of the present invention will be described in detail. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.
(Manufacturing method of undercoat layer forming coating solution)
The manufacturing method of the undercoat layer forming coating solution according to the present embodiment includes a first step and a second step. In the first step, a dispersion is obtained by dispersing a mixture of metal oxide fine particles, a binder resin, and a solvent. In the second step, the ionic component in the dispersion is removed to obtain a coating solution.

First, the first step will be described. Examples of the metal oxide fine particles used in the first step include tin oxide, titanium oxide, and zinc oxide. These can be used alone or in admixture of two or more. In this case, two or more kinds having different particle diameters may be mixed and used. As the metal oxide fine particles, those having an average primary particle size of 0.5 μm or less are preferably used. When the average primary particle diameter exceeds 0.5 μm, poor dispersion tends to occur, and the liquid tends to separate or the metal oxide fine particles precipitate. Further, even if metal oxide fine particles having an average primary particle diameter exceeding 0.5 μm are dispersed to some extent in the liquid, the film formability is insufficient, and cracks tend to be generated during drying. Further, from the viewpoint of imparting leak resistance to the undercoat layer, the metal oxide fine particles preferably have a resistance value of about 10 ² to 10 ¹¹ Ω · cm. If the resistance value is lower than the lower limit, sufficient leakage resistance cannot be obtained. On the other hand, if the resistance value is higher than the upper limit, the residual potential may be increased.

  As the metal oxide fine particles, metal oxide fine particles that have been surface-treated with a surface treatment agent are preferably used. Any surface treating agent can be used as long as the desired photoreceptor characteristics can be obtained. As the surface treatment agent, it is preferable to use at least one selected from a silane coupling agent, a zirconia coupling agent, a titanate coupling agent, and an aluminate coupling agent. Specifically, vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, Vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-amino Examples include, but are not limited to, silane coupling agents such as propylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and γ-chloropropyltrimethoxysilane. Absent. Moreover, these coupling agents can also be used individually or in mixture of 2 or more types.

  Any method can be used as the surface treatment method of the metal oxide fine particles as long as it is a known method, but a dry method or a wet method can be used. When surface treatment is performed on the metal oxide fine particles by a dry method, a coupling agent dissolved directly or in an organic solvent or water is added dropwise to dry air or nitrogen while stirring the metal oxide fine particles with a mixer having a large shearing force. By spraying with the gas, the surface of the metal oxide fine particles can be uniformly treated. The dropping or spraying of the coupling agent is preferably performed at a temperature of 50 ° C. or higher. After dropping or spraying the coupling agent, baking may be performed at 100 ° C. or higher. Baking can be carried out in an arbitrary range as long as the temperature and time allow the desired electrophotographic characteristics to be obtained. In the dry method, the surface adsorbed water can be removed by heating and drying before the surface treatment of the metal oxide fine particles with the coupling agent. By removing the surface adsorbed water before the surface treatment of the metal oxide fine particles, the coupling agent can be uniformly adsorbed on the surface of the metal oxide fine particles. The metal oxide fine particles can be heat-dried while stirring with a mixer having a large shearing force.

  When surface treatment is performed on metal oxide fine particles by a wet method, the metal oxide fine particles are dispersed in a solvent using stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and a coupling agent solution is added and stirred or dispersed. Then, the surface of the metal oxide fine particles can be uniformly treated by removing the solvent. After removing the solvent, baking can be performed at 100 ° C. or higher. Such printing can be carried out in an arbitrary range as long as the temperature and the time at which desired electrophotographic characteristics are obtained. In the wet method, the surface adsorbed water can be removed before the surface treatment of the metal oxide fine particles with the coupling agent. As a method for removing this surface adsorbed water, in addition to removal by heating and drying as in the dry method, there are a method of removing with stirring and heating in a solvent used for surface treatment, a method of removing by azeotropy with the solvent, and the like. It is done.

It is essential that the amount of the surface treatment agent used for the metal oxide fine particles is an amount that can provide desired electrophotographic characteristics. The electrophotographic characteristics of the photoreceptor are affected by the amount of the surface treatment agent attached to the metal oxide fine particles. This adhesion amount can be measured by fluorescent X-ray analysis. For example, when the surface treatment agent is a silane coupling agent, it can be determined from the Si strength and the main metal element strength of the metal oxide fine particles. A suitable Si intensity in the fluorescent X-ray analysis is in the range of 1.0 × 10 ^{−6 to} 1.0 × 10 ⁻³ of the main metal element strength of the metal oxide fine particles. When the Si intensity is less than the above lower limit, image quality defects such as fog are likely to occur, and when it exceeds the above upper limit, defects such as an increase in residual potential tend to occur.

  Binder resins include acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride. -Known polymer resins such as vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, and the like. In addition, a charge transporting resin having a charge transporting group, a conductive resin such as polyaniline, or the like can be used. Among these, resins that are insoluble in the upper coating solvent are preferably used, and phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, epoxy resins, and the like are particularly preferably used.

  The mass ratio between the metal oxide fine particles and the binder resin in the coating solution can be arbitrarily set within a range where desired electrophotographic photoreceptor characteristics can be obtained. The mass ratio (the former: the latter) is preferably 8.5: 1 to 20: 1, more preferably 10: 1 to 16: 1. When the mass of the metal oxide fine particles is less than 8.5 times the mass of the binder resin, the exposed area potential of the electrophotographic photosensitive member tends to increase and the potential characteristics tend to deteriorate. On the other hand, when the mass of the metal oxide fine particles exceeds 20 times the mass of the binder resin, the film forming property and the coating stability tend to deteriorate.

  As the solvent, any known organic solvent that can dissolve the binder resin can be used. The organic solvent can be arbitrarily selected from, for example, alcohol solvents, aromatic solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents, and ester solvents. Specifically, methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane Ordinary organic solvents such as tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene can be used. These solvents can be used alone or in admixture of two or more.

  Moreover, various additives can be mix | blended with the coating liquid concerning this embodiment for an electrical property improvement, environmental stability improvement, and image quality improvement. Examples of additives include quinone compounds such as chloranil, bromoanil, anthraquinone, alizarin, tetracyanoquinodimethane compounds, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, and the like. Fluorenone compounds such as 2- (4-biphenyl) -5- (4-t-butylphenyl) -1.3.4-oxadiazole and 2,5-bis (4-naphthyl) -1,3,4- Oxadiazole, oxadiazole compounds such as 2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, 5,5′- Electron transporting materials such as diphenoquinone compounds such as tetra-t-butyldiphenoquinone, electron transporting pigments such as polycyclic condensation systems and azo systems, zirconium chelation Things, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, there can be used a known material such as a silane coupling agent. The silane coupling agent is used as a surface treatment for the metal oxide fine particles, but it can also be added to the dispersant as an additive.

  Such silane coupling agents include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltri Methoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl)- Examples include γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, and the like.

  Zirconium chelate compounds include: zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, naphthenic acid Zirconium, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Titanium chelate compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium Examples include lactate, titanium lactate ethyl ester, titanium triethanolamate, and polyhydroxytitanium stearate.

  Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, and aluminum tris (ethyl acetoacetate). These compounds can be used alone or as a mixture or polycondensate of two or more.

  As a dispersion treatment method in the first step, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used.

  Next, the second step will be described. In the second step, the ionic component in the dispersion is removed to obtain a coating solution. It is preferable to use an ion exchange resin for removing the ionic component. Examples of the ion exchange resin include a strong acid cation exchange resin, a weak acid cation exchange resin, a strong basic anion exchange resin, a weak basic anion exchange resin, and a chelate resin. Examples of the structure of the ion exchange resin include a gel type, a porous type, and a high porous type. Here, the gel type means that the inside of the particle is composed of a uniform crosslinked polymer. The porous type means a fine and dense structure inside the particle, and there are pores that promote the diffusion of ions and molecules in addition to the polymer network. The high porous type means a resin having a structure in which pores are further developed, and is a resin having an improved reaction rate.

  The ion exchange resin used for removing the ion component is selected depending on the type of solvent for performing ion exchange, the type of binder, and the type of metal oxide fine particles. Specifically, strong acid sulfonic acid group type, weak acid methacrylic acid type, acrylic type, carboxylic acid group type; strong basic ammonium group type; weak basic acrylic tertiary amine type, 1-2 There are secondary polyamine type, tertiary amine type; iminodiacetic acid type using a chelate resin, polyamine type, N-methylglucamine group type, and the like. In some cases, a synthetic adsorbent may be used. When using a synthetic adsorbent, aromatic or methacrylic may be used. Moreover, an ion exchange resin can be used individually or in combination of 2 or more types.

  Among these ion exchange resins, a chelate resin is preferable in that an ion component generated due to metal oxide fine particles or a surface treatment agent can be efficiently removed. The present inventors presume that the metal ion, which is an ionic component, binds to a functional group such as iminodiacetic acid or polyamine that the chelate resin has, thereby removing the ionic component in the dispersion. Accordingly, the chelate resin is preferably one having an exchange group such as a functional group such as iminodiacetic acid or polyamine. Here, the chelate resin refers to a resin that strongly and selectively binds to a specific ionic component by a chelate bond.

Moreover, the electrical conductivity of a coating liquid can be used as an index | index at the time of removing an ionic component. An example of a procedure for removing ionic components using the conductivity of the coating solution as an index will be described with reference to FIG. FIG. 1 is a graph showing an example of the correlation between the concentration of the ionic component of the coating solution and the conductivity. The graph shown in FIG. 1 plots the conductivity σ _A , σ _B , σ _C , σ _D of the dispersion or coating liquid against the concentrations C _A , C _B , C _C , C _D of the ionic components. It is an example of the correlation curve of the density | concentration of an ionic component and conductivity obtained.

Based on the correlation between the concentration of the ionic component thus obtained and the electrical conductivity, the ionic component is extracted from the dispersion obtained in the first step so that the electrical conductivity of the obtained coating liquid is not more than a predetermined value. Remove. For example, when the conductivity of the dispersion liquid is σ _D , the ionic component is removed so that the conductivity of the resulting coating liquid is σ _B or less. In addition, although the reference value of the electrical conductivity after removing the ionic component can be appropriately selected according to the type and content of the material contained in the dispersion, it is preferably 300 nS / cm or less, more preferably 200 nS / cm. cm or less.

Moreover, in this invention, you may remove an ion component by making into a parameter | index the variation | change_quantity of the electrical conductivity before and behind ion component removal. The amount of change may be a difference (for example, σ _D −σ) obtained by subtracting the conductivity before removal of the ion component from the conductivity after removal of the ion component, or a ratio of both (eg, σ / σ _D ). There may be. For example, when the conductivity σ / σ _D before and after removal of the ionic component is used as an index, it is preferable to remove the ionic component so that σ / σ _D is 1/2 or less (more preferably 1/5 or less). .

In addition, a third step of removing an ionic component so that the conductivity of the obtained coating solution is a predetermined value or less may be further provided for the coating solution that has passed for a predetermined time after the second step. The conductivity of the coating liquid is determined based on the correlation between the concentration of the ionic component of the coating liquid and the conductivity, but can be determined based on the correlation obtained in the second step described above, for example, σ _B It can be. In this case, a correlation between the concentration of the ionic component of the coating solution and the conductivity may be newly obtained. Then, the ionic component can be removed by allowing the coating solution to pass through the above-described chelate resin so that the conductivity of the coating solution is σ _B or less.

  In addition, as a measuring method of the electrical conductivity of a coating liquid, the alternating current bipolar method which immerses the electrode of a conductivity meter in a coating liquid is mentioned. The circuit of the conductivity meter may be either a bridge method or an AC voltage current method.

  The stability of the coating solution is due to the removal of ionic components due to many factors such as the dispersion state of the metal oxide fine particles, the stability of the surface treatment agent that surface-treated the metal oxide fine particles, and the amount of moisture contained in the coating solution. It will change over time later. For this reason, when the coating solution is circulated, an ionic component removing device may be installed in the coating solution circulation device to remove the ionic component of the coating solution. Thereby, since it becomes possible to remove an ionic component continuously, the coating liquid excellent in stability can be manufactured.

Moreover, the removal of the ion component can be performed before the first step and when the mixture is prepared. For example, first, a solution of metal oxide fine particles dispersed in an organic solvent is passed through an ion exchange resin to remove ionic components. Thereby, the ionic component in the metal oxide fine particles and the ionic component attached to the fine particles can be removed in advance. Further, the ion component may be removed from the binder resin and the solvent by the same method. Next, after preparing and dispersing a mixture of metal oxide fine particles, binder resin and solvent from which ion components have been removed in advance, the ion components are further removed with an ion exchange resin. This makes it possible to more reliably remove ionic components contained in metal oxide fine particles, etc., so that the coating for forming the undercoat layer can impart sufficient electrical characteristics to the formed undercoat layer. A liquid can be produced. In addition, the ionic component adsorbed on the ion exchange resin can be dissolved with an acid, for example. In this case, the ion exchange resin can be used repeatedly by regenerating with an alkali, for example. Therefore, by using such an ion exchange resin, it becomes excellent in environmental performance.
(Electrophotographic photoreceptor)
FIG. 2 is a cross-sectional view showing an example of a preferred basic configuration of an electrophotographic photosensitive member mounted on an electrophotographic apparatus. As shown in FIG. 2, in the electrophotographic photoreceptor 1, the conductive substrate 2, the undercoat layer 4 formed on the conductive substrate 2, the photosensitive layer 3 formed on the undercoat layer 4, And a protective layer 7 formed on the photosensitive layer 3. The photosensitive layer 3 has a laminated structure (two-layer structure) of a charge generation layer 5 formed on the undercoat layer 4 and a charge transport layer 6 formed on the charge generation layer 5. And the undercoat layer 4 in this embodiment is formed using the coating liquid for undercoat layer formation obtained by the manufacturing method mentioned above.

  Hereinafter, each component of the electrophotographic photoreceptor 1 will be described in detail.

  First, the conductive substrate 2 will be described. As the conductive substrate 2, for example, a metal drum made of a metal material such as aluminum, copper, iron, stainless steel, zinc, or nickel can be used. In addition, a metal such as aluminum, copper, gold, silver, platinum, palladium, titanium, nickel-chromium, stainless steel, or indium is deposited on a sheet, paper, plastic, or glass, or a conductive material such as indium oxide or tin oxide. Conductive metal compounds are vapor-deposited, metal foil is laminated, or carbon black, indium oxide, tin oxide, antimony oxide powder, metal powder, copper iodide, etc. are dispersed in a binder resin and applied to conduct electrical treatment. A thing etc. can be used.

  The shape of the conductive substrate 2 is not limited to a drum shape, and may be a sheet shape or a plate shape. In the case where a metal pipe is used as the conductive substrate 2, the metal pipe may be used as it is, or previously subjected to processing such as mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing and the like. May be.

  Next, the undercoat layer 4 will be described. The undercoat layer 4 has functions such as an improvement in electrical characteristics, an improvement in image quality, an improvement in image quality maintenance, an improvement in adhesion of the photosensitive layer 3 and an improvement in leak resistance. The undercoat layer 4 is formed of an undercoat layer forming coating liquid from which an ionic component has been removed by the above-described manufacturing method, and includes metal oxide fine particles and a binder resin. The structures of the inorganic pigment and the binder resin are as described in the above-described method for producing the undercoat layer forming coating solution.

  As a coating method of the coating liquid used when forming the undercoat layer 4, a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, etc. are usually used. This method can be used.

  The undercoat layer 4 preferably has a Vickers strength of 35 or more. Furthermore, the film thickness of the undercoat layer 4 can be set to an arbitrary film thickness within a range where desired characteristics are obtained, but is preferably 15 μm or more, more preferably 20 to 50 μm.

  The surface roughness of the undercoat layer 4 is adjusted to ¼ n (where n is the refractive index of the upper layer) to λ of the exposure laser wavelength λ used in order to prevent moire images. In order to adjust the surface roughness, resin particles may be added to the undercoat layer 4. Examples of the resin particles include silicone resin particles and cross-linked PMMA resin particles. Further, the undercoat layer 4 may be polished in order to adjust the surface roughness. Examples of the polishing method include buffing, sandblasting, wet honing, and grinding.

  Further, an intermediate layer may be provided between the undercoat layer 4 and the photosensitive layer 3 in order to improve electrical characteristics, improve image quality, improve image quality maintenance, improve adhesion of the photosensitive layer, and the like. This intermediate layer is composed of acetal resin such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride In addition to polymer compounds such as vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, organometallic compounds having elements such as zirconium, titanium, aluminum, manganese, silicon, etc. Containing. These compounds can be used alone or as a mixture or polycondensate of two or more. Among these, when an organometallic compound containing zirconium or silicon is used, the residual potential is low, the potential change due to the environment is small, and the potential change due to repeated use is small. You can get a body.

  Examples of the organosilicon compound include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltri Methoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl)- Examples thereof include γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and γ-chloropropyltrimethoxysilane. Among these, particularly preferable organosilicon compounds are vinyltriethoxysilane, vinyltris (2-methoxyethoxysilane), 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-amino Examples of the silane coupling agent include propyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

  Examples of the organic zirconium compound include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, Zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide.

  Examples of the organic titanium compound include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, and titanium lactate ammonium salt. , Titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, and polyhydroxytitanium stearate.

  Examples of the organoaluminum compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, and aluminum tris (ethyl acetoacetate).

  In addition to improving the coatability of the upper layer, the intermediate layer also serves as an electrical blocking layer, so if the film thickness is excessively thick, the electrical barrier becomes too strong, causing desensitization and potential increase due to repetition. There is a case. Therefore, the film thickness of the intermediate layer is set in the range of 0.1 to 3 μm.

  Next, the charge generation layer 5 will be described. The charge generation layer 5 has a function of generating charge carriers. The charge generation layer 5 includes a charge generation material and a binder resin.

  As the charge generation material, known charge generation materials can be used. Examples of infrared light include phthalocyanine pigments, squarylium, bisazo, trisazo, perylene, dithioketopyrrolopyrrole and the like. Examples of visible light include condensed polycyclic pigments, bisazo, perylene, trigonal selenium, and dye-sensitized metal oxide fine particles. Among these, a particularly excellent performance is obtained, and a charge generating material that is preferably used includes a phthalocyanine pigment. By using this phthalocyanine pigment, an electrophotographic photosensitive member having particularly high sensitivity and excellent repeat stability can be obtained. Particularly preferably used phthalocyanine pigments include chlorogallium phthalocyanine, dichlorosus phthalocyanine, hydroxygallium phthalocyanine, metal-free phthalocyanine, oxytitanyl phthalocyanine, chloroindium phthalocyanine and the like.

  In addition, phthalocyanine pigments generally have several types of crystal types, and any of these crystal types can be used as long as it is a crystal type capable of obtaining a sensitivity suitable for the purpose. Crystals of phthalocyanine pigments can be obtained by mechanically dry-grinding phthalocyanine pigments produced by a known method with an automatic mortar, planetary mill, vibration mill, CF mill, roller mill, sand mill, kneader, etc. In addition, it can be produced by wet pulverization using a ball mill, mortar, sand mill, kneader or the like. Solvents used in this wet grinding treatment include aromatics (toluene, chlorobenzene, etc.), amides (dimethylformamide, N-methylpyrrolidone, etc.), aliphatic alcohols (methanol, ethanol, butanol, etc.), aliphatic Polyhydric alcohols (ethylene glycol, glycerin, polyethylene glycol, etc.), aromatic alcohols (benzyl alcohol, phenethyl alcohol, etc.), esters (acetic ester, butyl acetate, etc.), ketones (acetone, methyl ethyl ketone, etc.), dimethyl sulfoxide , Ethers (diethyl ether, tetrahydrofuran, etc.), a mixed system of several solvents, and a mixed system of these organic solvents and water.

  The solvent to be used is used in the range of 1 to 200 parts by mass, preferably 10 to 100 parts by mass, based on the total mass of the pigment crystals. The treatment temperature is in the range of -20 ° C to the boiling point of the solvent, preferably -10 to 60 ° C. Further, at the time of pulverization, grinding aids such as salt and sodium nitrate can be used. The grinding aid may be used 0.5 to 20 times, preferably 1 to 10 times the total mass of the pigment. Moreover, the phthalocyanine pigment crystal produced by a known method can be controlled by combining acid pasting or acid pasting with dry grinding or wet grinding as described above. As an acid used for acid pasting, sulfuric acid is preferable, and one having a concentration of 70 to 100%, preferably 95 to 100% is used, and a dissolution temperature is in a range of -20 to 100 ° C, preferably -10 to 60 ° C. It is. The usage-amount of concentrated sulfuric acid is 1-100 times with respect to the mass of a phthalocyanine pigment crystal, Preferably it is 3-50 times. As the solvent to be precipitated, water or a mixed solvent of water and an organic solvent is used in an arbitrary amount. The temperature for precipitation is not particularly limited, but it is preferably cooled with ice or the like in order to prevent heat generation.

  In addition, the charge generation material may be surface-treated with a surface treatment agent from the viewpoint of improving the stability of electric characteristics and preventing image quality defects. A coupling agent or the like can be used as the surface treatment agent, but is not limited thereto. As coupling agents used for the surface treatment, vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxy Propyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) ) -Γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, and other silane coupling agents. Among these, silane coupling agents that are particularly preferably used include vinyltriethoxysilane, vinyltris (2-methoxyethoxysilane), 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-amino Examples thereof include propyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

  Zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, zirconium naphthenate, lauric acid Organic zirconium compounds such as zirconium, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like can also be used. Tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate Organic titanium compounds such as ethyl ester, titanium triethanolamate, polyhydroxytitanium stearate, aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) Organic aluminum compounds such as these can also be used.

  The binder resin used for forming the charge generation layer 5 can be selected from a wide range of insulating resins. It can also be selected from organic photoconductive polymers such as poly-N-vinyl carbazole, polyvinyl anthracene, polyvinyl pyrene and polysilane. Preferred binder resins include polyvinyl acetal resin, polyarylate resin (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin Insulating resins such as polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin can be mentioned, but are not limited thereto. These binder resins can be used alone or in admixture of two or more. Of these, polyvinyl acetal resin is particularly preferably used. The content ratio (mass ratio) of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10.

  Furthermore, the charge generation layer 5 may contain various additives for improving electrical characteristics, improving image quality, and the like. Additives include quinone compounds such as chloranil, bromoanil and anthraquinone, tetracyanoquinodimethane compounds, fluorenones such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone Compounds, 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole and 2,5-bis (4-naphthyl) -1,3,4-oxadi Azole, oxadiazole compounds such as 2,5-bis (4-diethylaminophenyl) -1,3.4-oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, 5,5′-tetra- Electron transport materials such as diphenoquinone compounds such as t-butyldiphenoquinone, electron transport pigments such as polycyclic condensation systems and azo systems, zirconium chelate compounds, titani Mukireto compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, there can be used a known material such as a silane coupling agent.

  As silane coupling agents, vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxy Silane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ -Aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane and the like.

  Zirconium chelate compounds include: zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, naphthenic acid Zirconium, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Titanium chelate compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium Examples include lactate, titanium lactate ethyl ester, titanium triethanolamate, and polyhydroxytitanium stearate.

  Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, and aluminum tris (ethyl acetoacetate). These compounds can be used alone or as a mixture or polycondensate of two or more.

  Solvents for adjusting the coating solution for forming the charge generation layer 5 are known organic solvents such as alcohols, aromatics, halogenated hydrocarbons, ketones, ketone alcohols, ethers, esters. It can be arbitrarily selected from the above. For example, methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, Usual organic solvents such as methylene chloride, chloroform, chlorobenzene, and toluene can be used. These solvents can be used alone or in admixture of two or more. When mixing, any solvent can be used as long as it can dissolve the binder resin as the mixed solvent.

  As a dispersion treatment method for the coating liquid, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used. Further, as a coating method of the coating liquid when forming the charge generation layer 5, blade coating method, wire bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain coating method, etc. Conventional methods can be used.

  Further, in this dispersion treatment, if the particle size of the charge transport material is 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less, it is effective for high sensitivity and high stability. is there.

  Next, the charge transport layer 6 will be described. The charge transport layer 6 has a function of moving carriers generated in the charge generation layer 5. The charge transport layer 6 includes a charge transport material and a binder resin.

Any known material can be used as the charge transport material, but the following materials can be exemplified. Oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [pyridyl- (2)]-3 Pyrazoline derivatives such as-(p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, tri (p-methyl) phenylamine, N, N'-bis (3,4-dimethylphenyl) biphenyl Aromatic tertiary amino compounds such as -4-amine, dibenzylaniline, 9,9-dimethyl-N, N′-di (p-tolyl) fluoren-2-amine, N, N′-diphenyl-N, Aromatic tertiary diamino compounds such as N′-bis (3-methylphenyl)-[1,1-biphenyl] -4,4′-diamine, 3- (4′-dimethylaminophenyl)- 1,2,4-triazine derivatives such as 1,6-di- (4′-methoxyphenyl) -1,2,4-triazine, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 4-diphenylaminobenzaldehyde-1 , 1-diphenylhydrazone, hydrazone derivatives such as [p- (diethylamino) phenyl] (1-naphthyl) phenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, 6-hydroxy-2,3-di ( benzofuran derivatives such as p-methoxyphenyl) -benzofuran, α-stilbene derivatives such as p- (2,2-diphenylvinyl) -N, N′-diphenylaniline, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, poly Positive such as -N-vinylcarbazole and its derivatives Transport material;
Quinone compounds such as chloranil, bromoanil, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2- ( 4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (4-naphthyl) -1,3,4-oxadiazole, 2,5 -Oxadiazole compounds such as bis (4-diethylaminophenyl) -1,3,4-oxadiazole, xanthone compounds, thiophene compounds, 3,3 ', 5,5'-tetra-t-butyldiphenoxy Electron transport materials such as non-diphenoquinone compounds;
Or the polymer etc. which have the residue remove | excluding the hydrogen atom from the above-mentioned compound in a principal chain or a side chain are mentioned. These charge transport materials can be used alone or in admixture of two or more.

  The binder resin for the charge transport layer 6 is not particularly limited, but a resin capable of forming an electrically insulating film is preferable. Examples of the binder resin include polycarbonate resins (for example, bisphenol A and bisphenol Z), polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, and styrene-butadiene resins. Polymer, acrylonitrile-styrene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol- Formaldehyde resin, styrene-alkyd resin, poly-N-carbazole, polyvinyl butyral, polyvinyl formal, polysulfone, casein, gelatin, polyvinyl alcohol, ethyl cellulose, fluoro Insulative resins such as diol resin, polyacrylamide, polyamide, carboxymethyl cellulose, chlorine rubber, vinylidene chloride polymer wax, polyurethane, and organic photoconductive polymers such as polyvinyl carbazole, polyvinyl anthracene, polyvinyl pyrene, etc. It is not limited to. Among these, polycarbonate resin, polyester resin, methacrylic resin, and acrylic resin are particularly preferably used because they are excellent in compatibility with the charge transport material, solubility in a solvent, and strength. These binder resins can be used alone or in admixture of two or more.

  The charge transport layer 6 can contain fine particles such as silica and polytetrafluoroethylene (PTFE).

  The blending ratio (mass ratio) of the binder resin and the charge transport material can be arbitrarily set within a range not accompanied by a decrease in electrical characteristics and film strength. The film thickness of the charge transport layer 6 is preferably 5 to 50 μm, more preferably 10 to 40 μm. Further, as a coating method of the coating liquid for forming the charge transport layer 6, the blade coating method, the wire bar coating method, the spray coating method, the dip coating method, the bead coating method, the air knife coating method, the curtain coating method and the like are usually used. This method can be used. As a solvent used for the coating solution, a common organic solvent such as dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like can be used alone or in admixture of two or more.

Further, for the purpose of preventing deterioration of the electrophotographic photoreceptor 1 due to ozone, acid gas (for example, NO _x ), light or heat generated in the electrophotographic apparatus, an antioxidant, a light stabilizer, You may contain additives, such as a heat stabilizer.

  Examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. Examples of phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol, styrenated phenol, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxy Phenyl) -propionate, 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2-t-butyl-6- (3′-tert-butyl-5′-methyl-2′-) Hydroxybenzyl) -4-methylphenyl acrylate, 4,4′-butylidene-bis- (3-methyl-6-tert-butylphenol), 4,4′-thio-bis (3-methyl-6-tert-butylphenol) 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4 '-Hydroxyfe L) propionate] methane, 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,4,8 , 10-tetraoxaspiro [5,5] undecane and the like. Examples of hindered amine compounds include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy]- 2,2,6,6-tetramethylpiperidine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine succinate Polycondensate, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diimyl} {(2,2,6,6-tetra Methyl-4-piperidyl) imino} hexamethylene {(2,3,6,6-tetramethyl-4-piperidyl) imino}], 2- (3,5-di-t-butyl-4-hydroxybenzyl)- 2-n-Butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl- N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,5-triazine condensate and the like.

  Examples of the organic sulfur compound include dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, pentaerythritol-tetrakis (β- Lauryl-thiopropionate), ditridecyl-3,3′-thiodipropionate, 2-mercaptobenzimidazole, and the like. Examples of the organophosphorus compound include trisnonylphenyl phosfete, triphenyl phosfeto, and tris (2,4-di-t-butylphenyl) phosfeto. The antioxidants of the organic sulfur compound and the organic phosphorus compound are referred to as secondary antioxidants, and a synergistic effect can be obtained by using them together with primary antioxidants such as phenols or amines.

  Examples of the light stabilizer include benzophenone-based, benzoazole-based, dithiocarbamate-based, and tetramethylpipen-based derivatives. Examples of the benzophenone light stabilizer include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 2,2′-dihydroxy-4-methoxybenzophenone. Examples of the benzotriazole light stabilizer include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- [2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″). , 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- ( 2'-hydroxy-3'-t-butyl-5'-methyphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-t-butylphenyl) benzotriazole, 2- (2 '-Hydroxy-5'-t-octylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-t-amylphenyl-) benzotriazole and the like. Examples of other compounds include 2,4-di-t-butylphenyl-3 ′, 5′-di-t-butyl-4′-hydroxybenzoate and nickel dibutyl-dithiocarbamate.

In addition, at least one kind of electron-accepting substance can be contained for the purpose of improving sensitivity, reducing residual potential, and reducing fatigue during repeated use. Examples of the electron-accepting substance that can be used in the electrophotographic photoreceptor 1 according to this embodiment include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetra Examples thereof include cyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, and phthalic acid. Among these, benzene derivatives having an electron-withdrawing substituent such as fluorenone-based, quinone-based, Cl, CN, and NO ₂ are particularly preferable. A small amount of silicone oil can be added to the coating solution as a leveling agent for improving the smoothness of the coating film.

  Next, the protective layer 7 will be described. The protective layer 7 is an outermost layer, and has a function of preventing chemical change of the charge transport layer 6 during charging and increasing the mechanical strength of the photosensitive layer 3.

  The protective layer 7 is composed of a curable resin, a siloxane resin cured film containing a charge transporting compound, a film formed by containing a conductive material or the like in a binder resin, and the like. The curable resin is not particularly limited, and a known resin can be used. Specifically, a phenol resin, a polyurethane resin, a melamine resin, a diallyl phthalate resin, a siloxane resin, and the like can be given. In the case of a siloxane resin cured film containing a charge transporting compound, any known material can be used as the charge transporting compound. For example, JP-A-10-95787 and JP-A-10-251277. Examples thereof include, but are not limited to, compounds described in JP-A-11-32716, JP-A-11-38656, and JP-A-11-236391. When the protective layer 7 is a film formed by containing a conductive material in a suitable binder resin, examples of the conductive material include metallocene compounds such as N, N′-dimethylferrocene, N, N ′. -Aromatic amine compounds such as diphenyl-N, N'-bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine, molybdenum oxide, tungsten oxide, antimony oxide, tin oxide, Examples include titanium oxide, indium oxide, a solid solution carrier of tin oxide and antimony or antimony oxide, a mixture thereof, or a mixture of these metal oxide fine particles in a single particle or a coating thereof. It is not limited. The binder resin used for the protective layer 7 is polyamide resin, polyvinyl acetal resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, polyimide resin, polyamideimide. Known resins such as resins are used, and these can also be used after being crosslinked.

  Further, the protective layer 7 can contain an antioxidant. Antioxidants include, for example, known antioxidants such as phenol-based antioxidants, hindered amine-based antioxidants, organic sulfur-based antioxidants, organic phosphorus-based antioxidants, and hydroxyl groups capable of binding to siloxane resins. , Antioxidants having functional groups such as amino groups and alkoxysilyl groups.

  Examples of phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol, styrenated phenol, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxy Phenyl) -propionate, 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2-t-butyl-6- (3′-tert-butyl-5′-methyl-2′-) Hydroxybenzyl) -4-methylphenyl acrylate, 4,4′-butylidene-bis- (3-methyl-6-tert-butylphenol), 4,4′-thio-bis (3-methyl-6-tert-butylphenol) 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4 '-Hydroxyfe L) propionate] methane, 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,4,8 , 10-tetraoxaspiro [5,5] undecane and the like.

  Examples of hindered amine compounds include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy]- 2,2,6,6-tetramethylpiperidine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine succinate Polycondensate, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diimyl} {(2,2,6,6-tetra Methyl-4-piperidyl) imino} hexamethylene {(2,3,6,6-tetramethyl-4-piperidyl) imino}], 2- (3,5-di-t-butyl-4-hydroxybenzyl)- 2-n-Butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl- N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,5-triazine condensate and the like.

  Examples of organic sulfur antioxidants include dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, pentaerythritol-tetrakis. (Β-lauryl-thiopropionate), ditridecyl-3,3′-thiodipropionate, 2-mercaptobenzimidazole and the like. Examples of the organic phosphorus-based antioxidant include trisnonylphenyl phosphite, triphenyl phosfeft, and tris (2,4-di-t-butylphenyl) phosphite.

  Further, the protective layer 7 may contain fine particles such as silica and polytetrafluoroethylene (PTFE). The thickness of the protective layer 7 is preferably 1 to 20 μm, more preferably 1 to 10 μm.

  In addition, as a coating method of the coating solution for forming the protective layer 7, the blade coating method, the wire bar coating method, the spray coating method, the dip coating method, the bead coating method, the air knife coating method, the curtain coating method, etc. The method can be used. As the solvent used in the coating solution, ordinary organic solvents such as dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene and toluene can be used alone or in admixture of two or more. It is preferable to use a solvent that hardly dissolves the layer formed in the lower layer.

  The electrophotographic photosensitive member of the present invention is not limited to the above embodiment. For example, the electrophotographic photoreceptor 1 shown in FIG. 2 includes the protective layer 7, but the protective layer 7 is not provided when the charge transport layer 6 and the like have sufficiently high mechanical strength. Also good.

  In the electrophotographic photoreceptor 1 shown in FIG. 2, the charge generation layer 5 and the charge transport layer 6 are sequentially laminated on the conductive substrate 2, but the order of laminating these layers may be reversed. Good. Further, the electrophotographic photoreceptor 1 shown in FIG. 2 includes the function-separated type photosensitive layer 3, but may include a single-layer type photosensitive layer.

The electrophotographic photosensitive member 1 according to the present embodiment can be used in electrophotographic apparatuses such as laser beam printers, digital copying machines, LED printers, and laser facsimiles that emit near-infrared light or visible light. The electrophotographic photoreceptor 1 preferably has a residual potential fluctuation of 250 V or less when only charging exposure is repeated 100 kcycles or more. The laser beam is preferably a laser that oscillates light of 350 to 800 nm in order to obtain a high-definition image. Furthermore, in order to obtain a high-definition image, the spot diameter of the laser beam is preferably 10 ⁴ μm ² or less, more preferably 3 × 10 ³ μm ² or less.
(Electrophotographic equipment)
FIG. 3 is a schematic diagram showing a preferred embodiment of the electrophotographic apparatus of the present invention. The apparatus shown in FIG. 1 is a so-called tandem type color image forming apparatus, and four electrophotographic photoreceptors 1 a to 1 d are arranged in parallel with each other along an intermediate transfer belt 9 in a housing 200. Here, the electrophotographic photoreceptors 1a to 1d are the electrophotographic photoreceptors of the present invention.

  Each of the photoreceptors 1a to 1d can be rotated in a predetermined direction (counterclockwise on the paper surface), and the charging rolls 202a to 202d, the developing devices 204a to 204d, and the primary transfer rolls 210a to 210d along the rotation direction. Cleaning blades 215a to 215d are arranged. Each of the developing devices 204a to 204d can be supplied with toners (color toners) of four colors of black, yellow, magenta, and cyan accommodated in the toner cartridges 205a to 205d, and the primary transfer rolls 210a to 210d Each is in contact with the photoreceptors 1a to 1d via the intermediate transfer member 209. Further, a laser light source 203 is disposed at a predetermined position in the housing 200, and the surfaces of the charged photoreceptors 1a to 1d can be irradiated with laser light emitted from the laser light source 203. . Thus, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the photoreceptors 1a to 1d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 209 in an overlapping manner.

  The intermediate transfer belt 209 is supported with a predetermined tension by a drive roll 206, a backup roll 207, and a tension roll 208, and can be rotated without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 213 is disposed so as to contact the backup roll 207 via the intermediate transfer body 209. The intermediate transfer belt 209 passing between the backup roll 207 and the secondary transfer roll 213 is cleaned by the cleaning blade 214 and then repeatedly used in the next image forming process.

  In addition, a tray 211 is provided at a predetermined position in the housing 200, and a transfer medium (paper or the like) in the tray 211 is transferred between the intermediate transfer belt 209 and the secondary transfer roll 213 by the transfer roll 212. Are sequentially transferred between two fixing rollers 214 that are in contact with each other, and then discharged to the outside of the housing 200.

  FIG. 3 shows an electrophotographic apparatus provided with charging rolls 202a to 202d. However, the charging means provided in the electrophotographic apparatus of the present invention is not particularly limited, and examples thereof include conductive or semiconductive rollers, brushes, and films. In addition, there are known chargers such as a contact charger using a charging member such as a rubber blade, a scorotron charger using a corona discharge, and a corotron charger. Among these, a contact-type charger is preferable in terms of excellent charge compensation capability. The charging unit normally applies a direct current to the electrophotographic photosensitive member, but an alternating current may be applied in a superimposed manner.

Examples of the material for the charging member include metals such as aluminum, iron, and copper, conductive polymer materials such as polyacetylene, polypyrrole, and polythiophene, polyurethane rubber, silicone rubber, epichlorohydrin rubber, ethylene propylene rubber, acrylic rubber, fluorine rubber, A material in which metal oxide fine particles such as carbon black, copper iodide, silver iodide, zinc sulfide, silicon carbide, and metal oxide are dispersed in an elastomer material such as styrene-butadiene rubber and butadiene rubber can be used. Examples of the metal oxide include ZnO, SnO ₂ , TiO ₂ , In ₂ O ₃ , MoO ₃ , and composite oxides thereof. Moreover, perchlorate may be included in the elastomer material to impart conductivity.

  A coating layer can also be provided on the surface of the charging member. Examples of the material for forming this coating layer include N-alkoxymethylated nylon, cellulose resin, vinyl pyridine resin, phenol resin, polyurethane, polyvinyl butyral, melamine and the like, and these may be used alone. Two or more kinds may be used in combination. Also, emulsion resin-based materials such as acrylic resin emulsion, polyester resin emulsion, polyurethane, particularly emulsion resin synthesized by soap-free emulsion polymerization can be used. In these resins, conductive agent particles may be dispersed in order to further adjust the resistivity, and an antioxidant may be contained in order to prevent deterioration. Further, in order to improve the film formability when forming the coating layer, the emulsion resin may contain a leveling agent or a surfactant.

The charging member has an elastic layer, a conductive layer, and a resistance layer, and preferably has a volume resistivity of 10 ² to 10 ¹⁰ Ω · cm, and more preferably 10 ⁴ to 10 ¹⁰ Ω · cm. Further, when a voltage is applied to the charging member, either a direct current or an alternating current can be used as the applied voltage, and further, a superposed DC voltage and an alternating voltage can be used.

  The exposure means is not particularly limited. For example, a light source such as a semiconductor laser light, an LED light, or a liquid crystal shutter light on the surface of the electrophotographic photosensitive member 1 or a desired image from these light sources via a polygon mirror. And optical system equipment that can be exposed in this manner.

  Further, in the electrophotographic apparatus, the developing means (developing apparatuses 204a to 204d) can be appropriately selected according to the purpose. For example, a one-component developer or a two-component developer is used as a brush, a roller, or the like. Examples include known developing devices that are used in contact or non-contact for development.

  As a material of the intermediate transfer belt 209, a conventionally known conductive thermoplastic resin can be used. Examples of such a resin include polyimide resin containing a conductive agent, polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene terephthalate (PAT), ethylenetetrafluoroethylene copolymer (ETFE) / PC, ETFE / PAT. And PC / PAT blend materials. Among these, a polyimide resin in which a conductive agent is dispersed is preferably used in terms of excellent mechanical strength. As the conductive agent, a conductive polymer such as carbon black, metal oxide, or polyaniline can be used.

  An intermediate transfer belt made of a polyimide resin in which a conductive agent is dispersed is, for example, 5 to 20 as a conductive agent in a polyamic acid solution, which is a polyimide precursor, as described in JP-A-63-311263. After mass% carbon black is dispersed and the dispersion is cast on a metal drum and dried, the film peeled off from the drum is stretched at a high temperature to form a polyimide film, which is further cut into a suitable size. Manufactured by making an endless belt. The film molding is generally performed by injecting a polyamic acid solution film-forming stock solution in which a conductive agent is dispersed into a cylindrical mold and, for example, heating at 100 to 200 ° C. at a rotational speed of 500 to 2000 rpm. The film is formed into a film by a centrifugal molding method while rotating. Next, the obtained film is demolded in a semi-cured state, covered with an iron core, and is subjected to a main curing by advancing a polyimide reaction (polyamic acid ring-closing reaction) at a high temperature of 300 ° C. or higher. Also, the stock solution is cast on a metal sheet to a uniform thickness and heated to 100-200 ° C. to remove most of the solvent in the same manner as above, and then gradually raised to a high temperature of 300 ° C. or higher. There is also a method of forming a polyimide film. The thickness of the intermediate transfer belt is preferably 50 to 500 [mu] m, more preferably 60 to 150 [mu] m, and can be appropriately selected depending on the hardness of the material. The intermediate transfer member may have a surface layer.

  In the electrophotographic apparatus according to the present embodiment, electrophotographic image formation is performed using the electrophotographic photosensitive member 1 including the undercoat layer 4 in which fluctuations in the residual potential and the charging potential are suppressed as compared with the conventional case. Therefore, it is possible to achieve excellent image quality characteristics with high contrast and suppressed occurrence of fogging, black spots, and the like.

  The electrophotographic apparatus of the present invention is not limited to the above embodiment. For example, the electrophotographic apparatus of the present invention may include a light neutralizing unit as necessary. Examples of such light neutralizing means include tungsten lamps and LEDs, and examples of the light quality used in the light neutralizing process include white light such as tungsten lamps and red light such as LED light. The irradiation light intensity in the photostatic process is usually set to output several times to about 30 times the amount of light indicating the half exposure sensitivity of the electrophotographic photosensitive member.

  Further, the electrophotographic apparatus of the present invention may include a fixing unit as necessary. Such fixing means is not particularly limited, and examples thereof include a fixing device known per se, such as a heat roller fixing device and an oven fixing device. The cleaning means is not particularly limited, and a known cleaning device or the like may be used.

  The electrophotographic apparatus of the present invention may further include a static eliminator such as an erase light irradiation device. As a result, when the electrophotographic photosensitive member is repeatedly used, the phenomenon that the residual potential of the electrophotographic photosensitive member is brought into the next cycle is prevented, so that the image quality can be further improved.

  Further, the electrophotographic photoreceptor 1 according to the present embodiment can be used for a process cartridge. Such a process cartridge combines, together with the electrophotographic photoreceptor 1, a charging device, a developing device, a cleaning device (cleaning means), an opening for exposure, and an opening for static elimination exposure using a mounting rail, and It is an integrated one. This process cartridge is detachable from the transfer device, the fixing device, and the electrophotographic apparatus main body, and can constitute an electrophotographic apparatus together with the electrophotographic apparatus main body.

  Further, FIG. 3 shows an electrophotographic apparatus that performs tandem color image formation. The electrophotographic apparatus of the present invention is, for example, a normal monochromatic electrophotographic apparatus in which only a single color toner is accommodated in a developing device. Alternatively, it may be a color electrophotographic apparatus provided with a developing device capable of supplying a plurality of colors of toner to one photoconductor.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.
(Example 1)
(Manufacture of coating solution for undercoat layer formation)
After 100 parts by mass of tin oxide (S1, manufactured by Mitsubishi Materials) was mixed with 500 parts by mass of toluene, 2 parts by mass of a silane coupling agent (A1100, manufactured by Nihon Unicar) was added and stirred for 5 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 100 ° C. for 2 hours.

  After mixing 35 parts by mass of the obtained surface-treated tin oxide and 44 parts by mass of methyl ethyl ketone, this solution was passed through a chelate resin (Diaion® CR20, manufactured by Mitsubishi Chemical Corporation) attached to the cartridge. It was. It was 100 nS / cm when the electric conductivity of the liquid mixture considered to be the amount of ions before and after being passed through the chelate resin was measured. The mixed solution is mixed with 15 parts by mass of a curing agent (blocked isocyanate, Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.) and 6 parts by mass of butyral resin (BM-1, manufactured by Sekisui Chemical Co., Ltd.). Was dispersed for 2 hours in a sand mill to obtain a dispersion.

After passing this dispersion through a chelate resin (Diaion® CR20) attached to the cartridge, 0.005 parts by mass of dioctyltin dilaurate as a catalyst, silicone oil (SH29PA, Toray Dow Corning) was used as a catalyst in the obtained filtrate. 0.01 parts by mass) (manufactured by Silicone) was added to obtain a coating solution for forming an undercoat layer. The conductivity of the coating solution after removing the ionic component was 120 nS / cm.
(Preparation of electrophotographic photoreceptor)
This coating solution was applied on an aluminum substrate having a diameter of 30 mm, a length of 340 mm, and a thickness of 1 mm by a dip coating method, followed by drying and curing at 160 ° C. for 100 minutes to form an undercoat layer having a thickness of 20 μm. Next, a photosensitive layer was formed on the undercoat layer. First, the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using Cukα as a charge generation material is diffracted to at least 7.4 °, 16.6 °, 25.5 °, and 28.3 °. A mixture of 15 parts by mass of gallium chloride phthalocyanine having a peak, 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nihon Unicar Co., Ltd.) as a binder resin, and 300 parts by mass of n-butyl alcohol was obtained. The glass beads were dispersed in a sand mill for 4 hours. The obtained dispersion was applied as a charge generation layer forming coating solution by dip coating on the undercoat layer and dried to form a charge generation layer having a thickness of 0.2 μm.

Furthermore, 4 parts by mass of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1.1 ′] biphenyl-4,4′-diamine and bisphenol Z polycarbonate resin (molecular weight 40,000) 6 A coating solution obtained by adding and dissolving 80 parts by mass of chlorobenzene to a part by mass was applied on the charge generation layer and dried at 130 ° C. for 40 minutes to form a charge transport layer having a thickness of 25 μm. Thus, an electrophotographic photosensitive member was produced.
(Example 2)
The coating solution for forming the undercoat layer prepared in Example 1 was stirred at room temperature for 21 days, and the coating solution was mixed with a chelate resin (diaion (3) so that the conductivity of the coating solution was 150 nS / cm or less. R) After passing through CR20), the conductivity of the coating solution after removing the ionic component was measured. The measurement result is shown as A in FIG. After removing the ionic component of the coating solution for forming the undercoat layer stirred for 21 days and measuring the conductivity, an electrophotographic photosensitive member was produced in the same manner as in Example 1 using this coating solution for forming the undercoat layer. did.
(Comparative Example 1)
The electrophotographic photoreceptor was measured after measuring the conductivity after preparing the coating solution by the same method as in Example 1 except that the chelate resin was not used to remove the ionic component in the production of the coating solution for forming the undercoat layer. Was made.
(Comparative Example 2)
The coating solution for forming the undercoat layer prepared in Comparative Example 1 was stirred for 21 days at room temperature without passing through the chelate resin, and the conductivity of the coating solution was measured every 3 days. The measurement result is shown as B in FIG. After measuring the electrical conductivity of the coating solution for forming the undercoat layer after 21 days, an electrophotographic photosensitive member was produced in the same manner as in Example 1 using this coating solution.
(Residual potential and charging potential evaluation test)
The residual potential and the charging potential were evaluated by the following method. Using the electrophotographic photoreceptors of Examples 1-2 and Comparative Examples 1-2, the following steps (A) to (C) under the conditions of 20 ° C. and 40% RH:
(A) a charging step of charging the electrophotographic photosensitive member with a scorotron charger having a grid applied voltage of −700 V,
(B) An exposure process in which discharge is performed by irradiating light of 10.0 erg / cm ² using a semiconductor laser having a wavelength of 780 nm after 1 second of (A),
(C) After 3 seconds of (A), a neutralization step was carried out sequentially by neutralizing by irradiating 50.0 erg / cm ² of red LED light. At this time, using a laser printer remodeling scanner (modified from Fuji Xerox XP-15), the potential V _H after the charging process in (A) and the potential V _L after the exposure process in (B) Measurement was performed, and potential fluctuation amounts ΔV _H and ΔV _L were determined from V _H and V _L at the initial stage (at the time of 1 cycle) and V _H and V _L after 100 kcycles were repeated. The test results are shown in Table 1. In Table 1, the higher V _H means that the higher the acceptance potential of the electrophotographic photosensitive member, the higher the contrast. A lower _VL means higher sensitivity, and a lower ΔV potential means less residual potential and less image memory and fogging.
(Production of electrophotographic apparatus and print test)
Using each of the electrophotographic photoreceptors of Examples 1 to 7 and Comparative Examples 1 to 3, an electrophotographic apparatus including a contact charging device and an intermediate transfer belt was produced. The configuration other than the electrophotographic photosensitive member was the same as that of the full color printer (copying machine) Docu Center Color 400 manufactured by Fuji Xerox Co., Ltd. Each electrophotographic apparatus thus obtained was subjected to a continuous print test, and the image quality after printing 10,000 sheets was evaluated. The obtained evaluation results are shown in Table 1.

It is a figure which shows an example of the correlation of the density | concentration of the ionic component of the coating liquid concerning this invention, and electrical conductivity. 1 is a schematic cross-sectional view showing an embodiment of an electrophotographic photoreceptor according to the present invention. 1 is a schematic diagram showing an embodiment of an electrophotographic apparatus according to the present invention. It is a figure which shows an example of the correlation with the electrical conductivity of the coating liquid concerning this invention, and elapsed days.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electrophotographic photoreceptor, 2 ... Electroconductive base | substrate, 3 ... Photosensitive layer, 4 ... Undercoat layer, 5 ... Charge generation layer, 6 ... Charge transport layer, 7 ... Protective layer.

Claims (5)

A method for producing a coating solution for forming an undercoat layer between a conductive substrate and a photosensitive layer of an electrophotographic photoreceptor,
A first step of obtaining a dispersion by dispersing a mixture containing metal oxide fine particles, a binder resin and a solvent;
A second step of obtaining a coating liquid by removing ionic components in the dispersion;
The manufacturing method of the coating liquid for undercoat layer formation characterized by the above-mentioned.   In the second step, the ionic component is removed so that the conductivity of the obtained coating liquid is not more than a predetermined value based on the correlation between the concentration of the ionic component of the coating liquid obtained in advance and the conductivity. The manufacturing method of the coating liquid for undercoat layer formation of Claim 1 characterized by performing.   For the coating liquid that has passed a predetermined time after the second step, the conductivity of the coating liquid obtained is less than a predetermined value based on the correlation between the concentration of the ionic component of the coating liquid and the electrical conductivity obtained in advance. The method for producing a coating liquid for forming an undercoat layer according to claim 1, further comprising a third step of removing an ionic component so that An electrophotographic photoreceptor comprising a conductive substrate and an undercoat layer formed on the conductive substrate,
An electrophotographic photosensitive film characterized in that the undercoat layer is formed using a coating solution for forming an undercoat layer obtained by the production method according to any one of claims 1 to 3. body. An electrophotographic photosensitive member according to claim 4,
A charging device for charging the surface of the electrophotographic photosensitive member;
An exposure apparatus that exposes the electrophotographic photoreceptor to form an electrostatic latent image;
A developing device for developing the electrostatic latent image with toner;
A transfer device for transferring the developed toner image to a transfer medium;
An electrophotographic apparatus comprising:

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