JP2006317557A - Electrophotographic photoreceptor, image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor capable of giving a good output image free of a ghost while preventing occurrence of a black spot due to pinhole leak, an image forming apparatus and a process cartridge. <P>SOLUTION: The electrophotographic photoreceptor 207 has an undercoat layer and a photosensitive layer on a conductive support, wherein the undercoat layer contains metal oxide fine particles and a binder resin, and when a surface of the electrophotographic photoreceptor 207 is repeatedly subjected to charge with a charging device 208, exposure with an exposure device 210 and photo-charge elimination with a photo-charge eliminator 214, the electrophotographic photoreceptor 207 satisfies expression (1): -3.0≤(RP-ΔVL)/L≤-1.0 wherein ΔVL denotes a difference given by subtracting a surface potential of the electrophotographic photoreceptor 207 after first-cycle exposure with the exposure device 210 from a surface potential of the electrophotographic photoreceptor 207 after second-cycle exposure; RP denotes a surface potential of the electrophotographic photoreceptor 207 after first-cycle photo-charge elimination with the photo-charge eliminator 214; and L denotes a thickness of the photosensitive layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photoreceptor, an image forming apparatus using the electrophotographic photoreceptor, and a process cartridge.

  A so-called electrophotographic image forming apparatus is an apparatus that forms an image by performing an image forming cycle including processes such as charging, exposure, development, and transfer using an electrophotographic photosensitive member. Is widely used in the fields of copiers, laser beam printers, and the like. As electrophotographic photoreceptors used in these electrophotographic image forming apparatuses, organic electrophotographic photoreceptors using organic photoconductive materials, which are inexpensive and have excellent advantages in terms of manufacturability and disposal, are widely used. Yes.

  Many organic electrophotographic photoreceptors have a structure in which an undercoat layer is formed on a conductive substrate such as aluminum and a photosensitive layer is formed thereon. The undercoat layer plays a major role in electrophotographic photoreceptors. It not only serves as a binder layer for ensuring sufficient adhesion between the conductive substrate and the photosensitive layer, but also conceals defects and stains on the conductive substrate. It also serves to prevent excessive charge injection from the photosensitive substrate into the photosensitive layer.

  In recent years, instead of corotron, which is a non-contact charging method, in an electrophotographic image forming apparatus, a contact charging type charging device that generates a small amount of ozone has been used. On the other hand, a local high electric field applied at the time of contact charging may cause an electrical pinhole leak, which may occur as an image quality defect (black spot). This pinhole leak may occur due to a coating film defect of the above-described electrophotographic photosensitive member itself. In addition, the pinhole leak may occur in the apparatus of the electrophotographic image forming apparatus or may enter the apparatus from the outside. There are cases where conductive foreign matter or the like has come into contact with or penetrate into the electrophotographic photosensitive member.

  In order to deal with such problems, a method has been devised to conceal defects in the conductive base material by increasing the thickness of the undercoat layer and to prevent the penetration of conductive foreign substances from the outside of the electrophotographic photosensitive member. Yes. When the undercoat layer is thickened, metal oxide fine particles are often contained in the undercoat layer in order to stabilize the electrical characteristics of the electrophotographic photoreceptor. For example, Patent Document 1 proposes a technique for preventing the generation of black spots by using an undercoat layer in which titanium oxide fine particles are contained in a thermosetting resin at a predetermined volume content. Patent Document 2 discloses a technique for preventing the generation of black spots by using an undercoat layer in which titanium oxide fine particles are contained in a specific block copolymer. Further, Patent Document 3 discloses a technique that contains titanium oxide fine particles. There has been proposed a technique for preventing the generation of black spots by including a polyethylene glycol ester in the drawing layer.

  From the viewpoint of preventing pinhole leakage, the thicker the undercoat layer, the greater the effect. However, when the thickness of the undercoat layer is increased, the influence of the undercoat layer on the electrical characteristics increases. For this reason, it is important that electric charges flow smoothly in the interface between the undercoat layer and the photosensitive layer and in the undercoat layer bulk. That is, when the electrophotographic photosensitive member is used with a negative charge, the hole injection property from the undercoat layer to the photosensitive layer is low (hole blocking property is high), and the undercoat is subtracted from the photosensitive layer. It is desired that the electron (electron) injection property into the layer is high. When the hole injection property from the undercoat layer to the photosensitive layer is high, image quality defects such as fog and black spots occur. In addition, when the electron injection property from the photosensitive layer to the undercoat layer is low, it is a cause of so-called ghost phenomenon in which the image in the previous cycle emerges in the next cycle, or causes deterioration in image quality due to changes in electrical characteristics in long-term use. It becomes.

Various studies have been made so far in order to improve the charge transfer in the interface between the undercoat layer and the photosensitive layer and in the undercoat layer bulk. For example, Patent Document 4 and Patent Document 5 disclose a technique for improving hole blocking property by using a silane coupling agent having an amino group as means for improving the hole injection preventing property from the undercoat layer to the photosensitive layer. Proposed.
Japanese Patent Application Laid-Open No. 08-044096 JP 11-338176 A JP 11-338178 A Japanese Patent Application Laid-Open No. 08-166679 JP 11-133649 A

  However, when these conventional techniques are used, the charge transfer in the interface between the undercoat layer and the photosensitive layer and in the undercoat layer bulk cannot be sufficiently controlled, and ghosting can be effectively prevented. It was difficult. In particular, when the undercoat layer is made thick in order to prevent the occurrence of black spots caused by pinhole leakage, a means for effectively preventing the occurrence of ghosts cannot be obtained by a conventionally known technique.

  The present invention has been made in view of the above-described problems of the prior art, and is capable of obtaining a good output image that is free from ghosting while preventing the occurrence of black spots due to pinhole leakage. An object is to provide a body, an image forming apparatus, and a process cartridge.

  As a result of intensive studies to achieve the above object, the present inventors have repeatedly included the metal oxide fine particles and the binder resin in the undercoat layer, and repeatedly charged, exposed, and removed the light from the electrophotographic photosensitive member surface. In the course of performing, the following formula (1): −3.0 ≦ (RP−ΔVL) /L≦−1.0 (where ΔVL in the formula (1) is the surface of the electrophotographic photoreceptor after the second cycle exposure) A difference obtained by subtracting the surface potential (V) of the electrophotographic photosensitive member after the first cycle exposure from the potential (V) is shown, and RP represents the surface potential (V) of the electrophotographic photosensitive member after the first cycle of photostatic elimination. L represents the film thickness (μm) of the photosensitive layer), and it was found that good characteristics without ghosting can be obtained, and the present invention has been completed.

That is, the present invention
<1> In an electrophotographic photosensitive member having an undercoat layer and a photosensitive layer on a conductive support,
The undercoat layer includes fine metal oxide particles and a binder resin;
The electrophotographic photosensitive member satisfies the following formula (1) in the process of repeatedly charging, exposing, and photostaticizing the surface of the electrophotographic photosensitive member.
−3.0 ≦ (RP−ΔVL) /L≦−1.0 Formula (1)
(In the formula (1), ΔVL represents a difference obtained by subtracting the surface potential of the electrophotographic photosensitive member after the first cycle exposure from the surface potential of the electrophotographic photosensitive member after the second cycle exposure, and RP is: (The surface potential of the electrophotographic photosensitive member after the first cycle static elimination exposure is indicated, and L indicates the film thickness of the photosensitive layer.)

  <2> The electrophotographic photosensitive member according to <1>, wherein the thickness of the undercoat layer is 15 μm or more and 30 μm or less.

  <3> The electrophotographic photosensitive member according to any one of <1> to <2>, wherein the photosensitive layer includes a charge generation layer and a charge transport layer.

  <4> The electrophotographic photosensitive member according to any one of <1> to <3>, wherein the photosensitive layer is formed in contact with the undercoat layer.

  <5> The metal oxide fine particles according to any one of <1> to <4>, wherein the metal oxide fine particles are at least one selected from the group consisting of titanium oxide, zinc oxide, and tin oxide. An electrophotographic photoreceptor.

  <6> The electrophotographic photosensitive member according to any one of <1> to <5>, wherein the metal oxide fine particles are surface-treated with a coupling agent.

  <7> The electrophotographic photosensitive member according to <6>, wherein the coupling agent is a silane coupling agent having an amino group.

  <8> The electrophotographic photosensitive member according to <3>, wherein the charge generation layer contains a phthalocyanine pigment.

  <9> The electron according to <8>, wherein the phthalocyanine pigment is at least one selected from hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, oxotitanyl phthalocyanine, and metal-free phthalocyanine. It is a photographic photoreceptor.

<10> The electrophotographic photosensitive member according to any one of <1> to <9>,
A charging device for charging the electrophotographic photoreceptor;
An exposure device that exposes the electrophotographic photosensitive member charged by the charging device to form an electrostatic latent image; and
A developing device for developing the electrostatic latent image to form a toner image;
A transfer device for transferring the developed toner image to a transfer medium;
An image forming apparatus comprising:

<11> In the transfer device, a transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the surface of the electrophotographic photosensitive member, and an electric field strength applied to the photosensitive layer of the electrophotographic photosensitive member by the transfer voltage is 1.0 × 10 ⁵ V / cm or more and 4.0 × 10 ⁵ V / cm or less, the image forming apparatus according to <10>.

<12> The electrophotographic photosensitive member according to any one of <1> to <9> and at least one selected from the group consisting of a charging device, an image exposure device, and a cleaning device are integrally supported to form an image. A process cartridge is detachable from a forming apparatus main body.

  <13> The process cartridge according to <12>, wherein the charging unit includes a contact-type charging device that contacts the photoconductor to charge the photoconductor.

  The main factors that cause ghosts are 1) the amount of continuous variation in electrical characteristics of the electrophotographic photosensitive member itself (hereinafter referred to as “cycle variation”), and 2) the electrophotographic photosensitive member in the transfer process. There are two points: the influence of the transfer voltage received. Regarding the cycle variation of the electrophotographic photosensitive member, when the increase in the surface potential in the next cycle of the area that was the image portion (printing portion) in the previous cycle is large, the image in the previous cycle is lightly exposed. A phenomenon called ghost occurs. On the other hand, when the decrease in the surface potential in the next cycle is large, a phenomenon called so-called positive ghost occurs in which the image in the previous cycle appears deeply.

  In the case of a reversal development type electrophotographic process in which the print portion is image-exposed, a transfer voltage having a polarity opposite to the charging potential is applied to the electrophotographic photosensitive member in the transfer process. In the image part (printing part) on the surface of the electrophotographic photosensitive member, the toner layer developed in the developing process exists, and in the non-image part (non-printing part), there is no toner layer. Therefore, in the transfer process, the non-image portion is more susceptible to the transfer voltage than the image portion. The greater the influence of the transfer voltage, the greater the decrease in surface potential in the next cycle. Therefore, in the case of an electrophotographic photosensitive member that is easily affected by the transfer voltage, the decrease in surface potential in the next cycle of the non-image part (non-printing part) is larger than the image part (printing part) in the previous cycle. Negative ghost is likely to occur. On the other hand, positive ghost is likely to occur in an electrophotographic photosensitive member that is not easily affected by the transfer voltage. That is, the degree of occurrence of the ghost is determined by the combination of the cycle variation of the electrophotographic photosensitive member and the potential variation due to the influence of the transfer voltage.

  The present inventors have found that the cycle fluctuation of the electrophotographic photoreceptor is caused by the charge behavior in the photosensitive layer, the potential fluctuation due to the influence of the transfer voltage is caused by the charge behavior in the undercoat layer, and both It was found that it fluctuates depending on the state of the undercoat layer. Furthermore, it has been found that the occurrence of ghosts can be effectively prevented by controlling the difference between the two to the electric field intensity per unit photosensitive layer thickness within the predetermined range.

  That is, in the formula (1) of the present invention, when (RP−ΔVL) / L is smaller than −3.0, the influence of the transfer electric field tends to be small and positive ghost tends to be generated. In (1), when (RP−ΔVL) / L is larger than −1.0, the film is easily affected by the transfer electric field, and negative ghost tends to occur.

  Here, the potential fluctuation due to the charge behavior in the photosensitive layer and the potential fluctuation due to the charge behavior in the undercoat layer are the same as those after charging in an apparatus that can repeatedly perform charging, exposure, and photostatic elimination. It can be calculated by measuring the electric potential after photostatic elimination.

  In other words, the potential fluctuation due to the charge behavior in the photosensitive layer is calculated as the potential fluctuation (ΔVL) after the second cycle exposure with respect to the first cycle when charging, exposure, and photostatic discharge are repeated. Can do. On the other hand, the potential fluctuation due to the charge behavior in the undercoat layer can be calculated as the potential (RP) after the photostatic elimination in the first cycle. As described above, ΔVL and RP can be measured and calculated because ΔVL is caused by the charge behavior in the photosensitive layer, and thus appears as potential fluctuations after the charge is generated and moved in the photosensitive layer by exposure, and RP is This is considered to be due to the electric charge behavior in the undercoat layer and appearing as a potential fluctuation in a relatively slow time region that has been subjected to photostatic discharge with a sufficient amount of light.

  As described above, according to the present invention, it is possible to provide an electrophotographic photosensitive member, an image forming apparatus, and a process cartridge that can obtain a good output image free from ghosting.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  1 to 3 are schematic sectional views showing a preferred embodiment of the electrophotographic photosensitive member of the present invention. The electrophotographic photosensitive member 1 is cut along a plane perpendicular to the stacking direction of the substrate 2 and the photosensitive layer 3. It is a thing. The electrophotographic photosensitive member shown in FIGS. 1 and 2 is a function-separated type photosensitive member, and a charge generation layer 5 and a charge transport layer 6 are individually provided as the photosensitive layer 3 provided in each photosensitive member. On the other hand, the electrophotographic photosensitive member shown in FIG. 3 is a single layer type electrophotographic photosensitive member in which the photosensitive layer is composed of a single layer containing both a charge generating substance and a charge transporting substance.

  More specifically, in the electrophotographic photoreceptor 1 shown in FIG. 1, the undercoat layer 4, the charge generation layer 5 and the charge transport layer 6 are laminated in this order on the conductive substrate 2 to form the photoreceptor 3. In the electrophotographic photoreceptor 1 shown in FIG. 2, the undercoat layer 4, the charge generation layer 5, the charge transport layer 6, and the protective layer 7 are laminated on the conductive substrate 2 in this order to form the photosensitive layer 3. Is configured. In the electrophotographic photoreceptor 1 shown in FIG. 3, the undercoat layer 4 and the photosensitive layer 3 are laminated in this order on the conductive substrate 2. Although the protective layer is not described in the configuration of FIG. 3, it may be provided as necessary.

  Hereinafter, each element will be described based on the electrophotographic photosensitive member 1 shown in FIG.

  The conductive substrate 2 is made of a metal such as aluminum, copper, iron, zinc or nickel; on a substrate such as a sheet, paper, plastic or glass, aluminum, copper, gold, silver, platinum, palladium, titanium, nickel-chromium , Stainless steel, copper-indium or other metal deposited; conductive metal compound such as indium oxide or tin oxide deposited on the substrate; metal foil laminated on the substrate; carbon black, indium oxide, Examples include tin oxide-antimony oxide powder, metal powder, copper iodide and the like dispersed in a binder resin and applied to the substrate to conduct a conductive treatment. The shape of the conductive substrate 2 may be any of a drum shape, a sheet shape, and a plate shape.

The undercoat layer 4 is formed by containing metal oxide fine particles in a binder resin. In order for the undercoat layer 4 to exhibit sufficient leakage resistance, the metal oxide fine particles preferably have a powder resistance of about 1 × 10 ² to 1 × 10 ¹¹ Ω · cm. Among them, it is preferable to use fine metal oxide particles such as tin oxide, titanium oxide, zinc oxide and zirconium oxide having the above resistance values, and zinc oxide is particularly preferably used. If the resistance value of the metal oxide fine particles is lower than the lower limit of the above range, sufficient leakage resistance cannot be obtained. If the resistance value is higher than the upper limit of the range, there is a concern that the residual potential is increased. Further, two or more kinds of metal oxide fine particles having different surface treatments or different particle diameters can be used in combination. The metal oxide fine particles preferably have a primary particle diameter of 50 to 200 nm, more preferably 60 to 150 nm. When the primary particle diameter is smaller than 50 nm, the thixotropy of the dispersed coating liquid for forming the undercoat layer becomes high, and it becomes difficult to handle the coating liquid or to form a uniform coating film. Further, when the primary particle diameter is larger than 200 nm, the dispersibility of the zinc oxide particles is deteriorated, and it becomes difficult to obtain a coating liquid in which the zinc oxide particles are uniformly dispersed.

A metal oxide fine particle having a BET specific surface area value of 10 m ² / g or more is preferably used. Those having a BET specific surface area value of less than 10 m ² / g tend to cause a decrease in chargeability and tend to make it difficult to obtain good electrophotographic characteristics.

  Furthermore, the metal oxide fine particles can be subjected to a surface treatment as necessary. The surface treatment agent can be selected from known materials as long as desired characteristics such as a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a surfactant can be obtained. In particular, silane coupling agents are preferably used because they give good electrophotographic characteristics. Further, a silane coupling agent having an amino group is preferably used because it gives a good blocking property to the undercoat layer 4.

  Any silane coupling agent having an amino group can be used as long as it can obtain desired photoreceptor characteristics. Specific examples include γ-aminopropyltriethoxysilane, N-β- (amino Ethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and the like. However, it is not limited to these. Moreover, 2 or more types of silane coupling agents can also be mixed and used. Examples of silane coupling agents that can be used in combination with the silane coupling agent having an amino group include 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-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltri Examples include methoxysilane. The present invention is not limited to, et al.

  As the surface treatment method, any known method can be used, but a dry method or a wet method can be used.

  When surface treatment is performed by a dry method, a silane coupling agent dissolved directly or in an organic solvent is added dropwise and sprayed with dry air or nitrogen gas while stirring the metal oxide fine particles with a mixer having a large shearing force. Is uniformly processed. The addition or spraying is preferably performed at a temperature below the boiling point of the solvent. Spraying at a temperature equal to or higher than the boiling point of the solvent is not preferred because it causes the solvent to evaporate before being stirred uniformly, causing the silane coupling agent to locally accumulate and making uniform processing difficult. After addition or spraying, baking can 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.

  As a wet method, the metal oxide fine particles are stirred in a solvent, dispersed using ultrasonic waves, a sand mill, an attritor, a ball mill, etc., added with a silane coupling agent solution and stirred or dispersed, and then the solvent is removed. Uniformly processed. The solvent removal method is distilled off by filtration or distillation. After removing the solvent, baking can 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 wet method, the water containing metal oxide fine particles can be removed before adding the surface treatment agent. For example, a method of removing with stirring and heating in the solvent used for the surface treatment, removing by azeotroping with the solvent. It is also possible to use a method of

  The amount of the silane coupling agent with respect to the metal oxide fine particles in the undercoat layer 4 can be arbitrarily set as long as desired electrophotographic characteristics can be obtained.

  As the binder resin contained in the undercoat layer 4, any known resin can be used as long as it can form a good film and can obtain desired characteristics.

  Examples of the binder resin 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, chloride Known polymer resin compounds such as vinyl-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, and charge transport property having a charge transporting group Resin, conductive resin such as polyaniline, and the like can be used. Of these, resins 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 ratio between the metal oxide fine particles and the binder resin in the coating solution for forming the undercoat layer can be arbitrarily set within a range where desired electrophotographic photoreceptor characteristics can be obtained.

  Various additives can be used in the coating liquid for forming the undercoat layer in order to improve electrical characteristics, environmental stability, and image quality.

As additives, quinone compounds such as chloranil and bromoanil, 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, Oxadiazole compounds such as 2,5-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 such as non-electron transport pigments such as polycyclic condensation systems and azo systems, zirconium chelate compounds, titanium chelate compounds, Rumi hexafluorophosphate chelate compounds, titanium alkoxide compounds, organic titanium compounds, there can be used a known material such as a silane coupling agent. Although the silane coupling agent is used for the surface treatment of the metal oxide, it can also be used as an additive added to the coating solution. Specific examples of the silane coupling agent used here include 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-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane and the like. Examples of zirconium chelate compounds include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl zirconium acetoacetate, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, naphthene. Zirconate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Examples of 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, Examples thereof include titanium 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, aluminum tris (ethyl acetoacetate) and the like.

  These compounds can be used alone or as a mixture or polycondensate of a plurality of compounds.

  As a solvent for adjusting the coating solution for forming the undercoat layer, any known organic solvent such as alcohol, aromatic, halogenated hydrocarbon, ketone, ketone alcohol, ether, ester, etc. You can choose. 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.

  Moreover, the solvent used for these dispersion | distribution can be used individually or in mixture of 2 or more types. When mixing, any solvent can be used as long as it can dissolve the binder resin as the mixed solvent.

  As a method for dispersing the metal oxide fine particles in the binder resin, known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used. Furthermore, as an application method used when providing this undercoat layer, a normal method such as 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, or a curtain coating method is used. Can be used.

  Furthermore, the thickness of the undercoat layer is preferably 15 μm or more and 30 μm or less, and more preferably 18 μm or more and 28 μm or less. When the thickness of the undercoat layer is less than 15 μm, it becomes difficult to effectively prevent black spots generated due to pinhole leakage. On the other hand, when the thickness of the undercoat layer is greater than 30 μm, the amount of charge accumulated in the undercoat layer increases, and the electrical characteristics as an electrophotographic photosensitive member deteriorate.

  Here, as described above, ΔVL indicating the potential fluctuation due to the charge behavior in the photosensitive layer, RP indicating the potential fluctuation due to the charge behavior in the undercoat layer, and the photosensitive layer thickness L are in a predetermined relationship. Therefore, the dispersion state of the metal oxide fine particles in the undercoat layer 4 is important. That is, when the metal oxide fine particles are excessively finely dispersed (overdispersed), the amount of charge that can be held in the undercoat layer is reduced, and the relationship between ΔVL and RP and L is set to a desired state. It becomes difficult. Therefore, in order to obtain the characteristics of the present invention, it is important to control the degree of dispersion of the metal oxide fine particles in the undercoat layer and adjust ΔVL, RP and L to a predetermined relationship.

  The degree of dispersion of the metal oxide fine particles can be controlled by the dispersion force (dispersion share) applied during dispersion and the dispersion time. For example, when the dispersion is performed by the paint shaker, if the amount of dispersed beads enclosed in the dispersion container together with the liquid to be dispersed is increased or the dispersed beads having a large specific gravity are used, the dispersion proceeds further, and the metal oxide fine particles are dispersed. More finely dispersed. Even if the dispersion time is set longer, the dispersion proceeds in the same manner. Conversely, when the amount of dispersed beads is reduced, dispersed beads having a small specific gravity are used, or the dispersion time is set short, the metal oxide fine particles are not so dispersed. When the degree of dispersion proceeds (when the metal oxide fine particles are finely dispersed), the potential fluctuation RP caused by the charge behavior in the undercoat layer tends to decrease, and conversely, the degree of dispersion progresses too much. In the state where it is not, the potential variation RP tends to increase. This has the same tendency depending on the degree of dispersion even if the dispersion method is changed.

  The value of RP can be adjusted by the diameter and amount of the metal oxide, the material and amount of the dispersion medium, the dispersion time, etc. For example, when zinc oxide particles are used as the metal oxide to be contained in the undercoat layer, the particle diameter When the dispersion time is set to 50 nm to 200 nm (μm) and the dispersion time is 1.5 hours or more, the RP tends to be −20 (V) or more, and the dispersion time is 0.3 to less than 1.5 hours. By doing so, RP can be adjusted to be less than −20 (V) to −45 (V) or less, and RP can be adjusted to be less than −45 V by setting the dispersion time to less than 0.3 hours.

  On the other hand, ΔVL indicating the potential fluctuation due to the charge behavior in the photosensitive layer is determined by the configuration of the photosensitive layer and its constituent materials. For example, ΔVL tends to increase when a highly sensitive charge generating material is used, and conversely, ΔVL tends to decrease when a charge generating material with low sensitivity is used.

  Therefore, in order to obtain the characteristics of the present invention, the constitution of the photosensitive layer, the degree of dispersion of the undercoat layer, and the film thickness of the photosensitive layer are controlled, and (RP−ΔVL) / L in the formula (1) is set by the combination thereof. Can be controlled. For example, when RP increases, the sensitivity is decreased to decrease ΔVL, and when RP decreases, a highly sensitive charge generation material is used, and RP and ΔVL and L are adjusted to a predetermined relationship. In addition, (RP−ΔVL) / L can be set to a specific range.

  Here, examples of the charge generation material that tends to increase ΔVL include hydroxygallium phthalocyanine and oxotitanyl phthalocyanine, and examples of the charge generation material that tends to decrease ΔVL include chlorogallium phthalocyanine and bisazo pigments. Can be mentioned.

  Further, the surface roughness of the undercoat layer 4 is adjusted to ¼ n (n is the refractive index of the upper layer) to ½λ of the exposure laser wavelength λ used in order to prevent moire images. In order to adjust the surface roughness, particles such as a resin can be added to the undercoat layer. As the resin particles, silicone resin particles, cross-linked PMMA resin particles, and the like can be used.

In addition, the undercoat layer can be polished to adjust the surface roughness. As a polishing method, buffing, sand blasting, wet honing, grinding, or the like can be used.

  The charge generation layer 5 constituting the photosensitive layer 3 contains a binder resin (binder resin) and a charge generation material. As the charge generation material, any conventionally known charge generation material can be used, but among these, phthalocyanine pigments are preferably used in view of the sensitivity of the electrophotographic photoreceptor. Furthermore, among the phthalocyanine pigments, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, oxotitanyl phthalocyanine, and metal-free phthalocyanine are more preferably used.

  The charge generation material is dispersed and held in a predetermined binder resin to form the charge generation layer 5. Such a binder resin can be selected from a wide range of insulating resins. Preferred binder resins include polyvinyl acetal resin, polyarylate resin, polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, Examples thereof include insulating resins such as urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinylpyrrolidone resin, and organic photoconductive polymers such as poly-N-vinyl carbazole, polyvinyl anthracene, polyvinyl pyrene, and polysilane. Among these, polyvinyl acetal resin and vinyl chloride-vinyl acetate copolymer are preferably used. These binder resins can be used alone or in combination of two or more. The blending ratio (mass ratio) of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10, and more preferably in the range of 8: 2 to 3: 7.

  When the charge generation layer 5 is formed, a coating solution in which a charge generation material is dispersed in a solution in which a binder resin is dissolved in a predetermined organic solvent is used. As an organic solvent for the coating solution for the charge generation layer, a solvent capable of dissolving the binder resin, for example, alcohol, aromatic, halogenated hydrocarbon, ketone, ketone alcohol, ether, ester, etc. Can be used. More 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, Examples include dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like. These solvents can be used alone or in combination of two or more. Examples of a method for dispersing the charge generating substance in the binder resin liquid include a ball mill, a roll mill, a sand mill, an attritor, and an ultrasonic wave.

  The charge generation material can be subjected to a surface treatment in order to improve dispersibility. A coupling agent or the like can be used as the surface treatment agent, but is not limited thereto. As coupling agents, 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- Examples include silane coupling agents such as aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and γ-chloropropyltrimethoxysilane. Among these, vinyltriethoxysilane, vinyltris (2-methoxyethoxysilane), 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxy Silane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3- Aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane are preferred.

  In addition to coupling agents, zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate An organic zirconium compound such as zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, or isostearate zirconium butoxide may be blended. 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, polyhydroxy titanium stearate, aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) An organoaluminum compound such as can also be used.

  The charge transport layer 6 includes a charge transport material and a binder resin. Specific examples of such charge transport materials include oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenylpyrazoline. 1- [pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline and other pyrazoline derivatives, triphenylamine, tri (p-methyl) phenylamine, N, N Aromatic tertiary such as' -bis (3,4-dimethylphenyl) biphenyl-4-amine, dibenzylaniline, 9,9-dimethyl-N, N'-di (p-tolyl) fluoren-2-amine Aromatic tertiary dia such as amino compounds, N, N′-diphenyl N, N′-bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine Compounds, 1,2,4-triazine derivatives such as 3- (4′-dimethylaminophenyl) -5,6-di- (4′-methoxyphenyl) -1,2,4-triazine, 4-diethylaminobenzaldehyde Hydrazone derivatives such as -1,1-diphenylhydrazone, 4-diphenylaminobenzaldehyde-1,1-diphenylhydrazone, [p- (diethylamino) phenyl]-(1-naphthyl) -phenylhydrazone, 2-phenyl-4-styryl Quinazoline derivatives such as quinazoline, benzofuran derivatives such as 6-hydroxy-2,3-di (p-methoxyphenyl) benzofuran, and α-stilbene such as p- (2,2-diphenylvinyl) -N, N′-diphenylaniline Derivatives, enamine derivatives, carbazole derivatives such as N-ethylcarbazole And hole transport materials such as poly-N-vinylcarbazole and derivatives thereof. Also, 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 Oxadiazole compounds such as 1,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, 5,5′-tetra-t-butyl Electron transport materials such as diphenoquinone compounds such as diphenoquinone can also be used. Furthermore, a polymer having a group composed of the above compound in the main chain or side chain can also be used. These charge transport materials can be used alone or in combination of two or more.

  The binder resin for the charge transport layer 6 is preferably a resin capable of forming an electrical insulating film. Examples of such resins include polycarbonate resin, polyarylate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, chloride Vinylidene-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, phenol resin, polyamide, carboxy-methyl cellulose, salt Vinylidene polymer waxes, polyurethanes, and the like. These binder resins can be used individually by 1 type or in mixture of 2 or more types. The mixing ratio (mass ratio) between the binder resin and the charge transport material can be arbitrarily set in any case, but attention must be paid to a decrease in electrical characteristics and a decrease in film strength.

  The charge transport layer 6 is formed by applying a charge transport layer coating liquid containing the above material onto the charge generation layer 5 and drying it. The solvent used in the coating solution can be arbitrarily selected from known organic solvents as long as the desired electrophotographic photoreceptor characteristics can be obtained, but dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like are preferable. Used for. Moreover, these can be used individually by 1 type or in mixture of 2 or more types. The thickness of the charge transport layer 6 is preferably 5 to 50 μm, more preferably 10 to 40 μm.

  To the charge transport layer 6, additives such as an antioxidant and a light stabilizer are added for the purpose of preventing deterioration of the photoreceptor due to ozone, oxidizing gas, or light / heat generated in the image forming apparatus. Can do.

  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′-hydroxyphenyl) 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-1,3,5-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-laurylthiopropionate), ditridecyl-3,3′-thiodipropionate, 2-mercaptobenzimidazole and the like.

  Examples of the organophosphorus antioxidant include trisnonylphenyl phosfte, triphenyl phosfte, tris (2,4-di-t-butylphenyl) -phosfte, and the like.

  The organic sulfur-based and organic phosphorus-based antioxidants are called secondary antioxidants, and a synergistic effect can be obtained by using them together with a primary antioxidant such as a phenol-based or amine-based antioxidant.

  Examples of the light stabilizer include benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine derivatives.

  Examples of the benzophenone light stabilizer include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and the like.

  Examples of the benzotriazole light stabilizer include 2- (2′-hydroxy-5′-methylphenyl) -benzotriazole, 2- [2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ′, 6 ″). -Tetrahydrophthalimido-methyl) -5'-methylphenyl] benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'- Hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5 ′,-di-t-butylphenyl) benzotriazole, 2- ( 2'-hydroxy-5'-t-octylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5',-di-t-amylphenyl) benzotriazole And the like.

  Other compounds include 2,4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4'-hydroxybenzoate and nickel dibutyl-dithiocarbamate.

  Further, at least one kind of electron accepting substance can be included for the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, and the like. Examples of the electron acceptor include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, Examples include chloranilquinone, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, and phthalic acid. Among these, a benzene derivative having an electron-withdrawing substituent such as fluorenone-based, quinone-based, Cl-, CN-, or NO2- is particularly preferable.

  In addition, a solid lubricant or a metal oxide can be dispersed in the charge transport layer 6 for the purpose of reducing wear. Solid lubricants include fluorine-containing resin particles (ethylene tetrafluoride, ethylene trifluoride chloride, ethylene tetrafluoride hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride, and those And the like, and silicon-containing resin particles. Examples of the metal oxide include silica, alumina, titanium oxide, tin oxide and the like. When the solid lubricant is dispersed, the friction coefficient on the surface of the charge transport layer decreases, so that wear can be suppressed. Further, when the metal oxide is dispersed, the mechanical hardness of the charge transport layer is increased, so that wear can be suppressed. Further, since the fluorine-containing resin particles are hardly dispersed particles, dispersibility is improved by using a fluorine-containing polymer-based dispersion aid. As a method for dispersing the solid lubricant and metal oxide, methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, a paint shaker, a homogenizer, and a high-pressure treatment type homogenizer can be used. In this dispersion, it is effective to make the dispersed particles 1.0 μm or less, preferably 0.5 μm or less.

  Further, a trace amount of silicone oil can be added as a leveling agent for improving the smoothness of the coating film.

As the surface protective layer 7, a cured film formed by including a compound represented by the following general formula (I) is preferable.
F- [DA] _b (I)
In general formula (I), F represents an organic group derived from a photofunctional compound, D represents a divalent group, and A represents a hydrolysis represented by —SiR ¹ _3-a (OR ² ) _a. The substituted silicon group which has a sex group is represented, and b represents the integer of 1-4. Here, R ¹ represents hydrogen, an alkyl group, or a substituted or unsubstituted aryl group, and R ² represents hydrogen, an alkyl group, or a trialkylsilyl group. a represents an integer of 1 to 3.

A substituted silicon group having a hydrolyzable group represented by A in the general formula (I), that is, —SiR ¹ _3-a (OR ² ) _a , has a three-dimensional Si—O—Si bond ( It plays a role in forming an inorganic glassy network.

  In general formula (I), F is an organic group having photoelectric characteristics, more specifically, photocarrier transport characteristics, and the structure of a photofunctional compound conventionally known as a charge transport material is used as it is. be able to. Specific examples of the organic group represented by F include triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, and the like. Examples include a compound skeleton having a hole transporting property, and a compound skeleton having an electron transporting property such as a quinone compound, a fluorenone compound, a xanthone compound, a benzophenone compound, a cyanovinyl compound, and an ethylene compound.

  Preferable examples of the organic group represented by F include groups represented by the following general formula (II). When F is a group represented by the general formula (II), particularly excellent photoelectric characteristics and mechanical characteristics are exhibited.

In general formula (II), Ar ^{1 to} Ar ⁴ each independently represents a substituted or unsubstituted aryl group. Ar ⁵ represents a substituted or unsubstituted aryl group or an arylene group. B (b = 1 to 4) of Ar ^{1 to} Ar ⁵ are bonded to a group represented by —D—SiR ¹ _(3-a) (OR ² ) _a . Here is the same as R ^1, R ^2, a is R ¹ in the general formula ^{(I), R 2, a} . k represents 0 or 1;

Ar ^{1 to} Ar ⁴ in the general formula (II) are preferably any of the following formulas (II-1) to (I-7).

_{-Ar-Z 's -Ar-X} m (II-7)

[In the formulas (II-1) to (I-7), R ⁶ is substituted with a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Represents one selected from the group consisting of a phenyl group, an unsubstituted phenyl group, and an aralkyl group having 7 to 10 carbon atoms, wherein R ^{7 to} R ⁹ are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, carbon One type selected from the group consisting of an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, or an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom Ar represents a substituted or unsubstituted arylene group, X represents —D—SiR ¹ _(3-a) (OR ² ) _a in general formula (I), and m and s are each 0 or 1 And t represents an integer of 1 to 3, respectively. ]

  Here, as Ar in Formula (II-7), what is represented by following formula (II-8) or (II-9) is preferable.

[In Formula (II-8) or (II-9), R ¹⁰ and R ¹¹ are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms. It represents one selected from the group consisting of a phenyl group substituted with an alkoxy group or an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, and t represents an integer of 1 to 3. ]

  Moreover, as Z 'in Formula (II-7), what is represented by either of following formula (II-10)-(II-17) is preferable.

_{- (CH 2) q - (} II-10)
_{- (CH 2 CH 2 O)} r - (II-11)

[In the formulas (II-10) to (II-17), R ¹² and R ¹³ are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms. It represents one selected from the group consisting of a phenyl group substituted by an alkoxy group or an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, W represents a divalent group, q and r Represents an integer of 1 to 10, respectively, and t represents an integer of 1 to 3, respectively. ]

  W in the above formulas (II-16) and (II-17) is preferably any one of divalent groups represented by the following (II-18) to (II-26).

—CH ₂ — (II-18)
—C (CH ₃ ) ₂ — (II-19)
-O- (II-20)
-S- (II-21)
—C (CF ₃ ) ₂ — (II-22)
—Si (CH ₃ ) ₂ — (II-23)

[In the formulas (II-18) to (II-26), u represents an integer of 0 to 3]

In general formula (II), Ar ⁵ is an aryl group exemplified in the description of Ar ^{1 to} Ar ⁴ when k is 0, and when k is 1, a predetermined hydrogen atom is taken from the aryl group. Excluded arylene group.

In the general formula (I), the divalent group represented by D plays a role of linking F that imparts photoelectric characteristics and A that is directly bonded to a three-dimensional inorganic glassy network, On the other hand, it imparts moderate flexibility to an inorganic glassy network that is brittle and plays a role of improving the toughness of the film. Examples of the divalent group represented by D, and _{specifically, -C n H 2n -, -} C n H 2n-2 -, - C n H 2n-4 - 2 divalent hydrocarbon group represented by (n represents an integer of 1~15), - COO -, - S -, - O -, - CH 2 -C 6 H 4 -, - n = CH -, - C 6 H 4 -C 6 H 4 -, A combination of these, or a substituent introduced.

  In general formula (I), b is preferably 2 or more. When b is 2 or more, the photofunctional organosilicon compound represented by the general formula (I) has two or more Si atoms, which facilitates formation of an inorganic glassy network and improves mechanical strength. Tend to.

  The compound represented by general formula (I) may be used individually by 1 type, and may be used together 2 or more types.

A compound represented by the following general formula (III) may be used in combination with the compound represented by the general formula (I) for the purpose of further improving the mechanical strength of the cured film.
B-A _n (III)

In general formula (III), A represents a substituted silicon group having a hydrolyzable group represented by —SiR ¹ _(3-a) (OR ² ) _a . Here is the same as R ^1, R ^2, a is R ¹ in the general formula ^{(I), R 2, a} . B is composed of at least one group selected from a divalent or higher valent hydrocarbon group, a divalent or higher valent phenyl group, and —NH—, which may contain a branch, or a combination thereof. n represents an integer of 2 or more.

The compound represented by the general formula (III) is a compound having a substituted silicon group having a hydrolyzable group represented by A, that is, —SiR ¹ _3-a (OR ² ) _a . The compound represented by the general formula (III) is a reaction with the compound represented by the general formula (I) or the general formula (III).
By the reaction between the compounds represented by the formula, a Si—O—Si bond is formed to give a three-dimensional crosslinked cured film. When the compound represented by the general formula (III) and the compound represented by the general formula (I) are used in combination, the crosslinked structure of the cured film tends to be three-dimensional, and the cured film has an appropriate flexibility. Therefore, stronger mechanical strength can be obtained. Preferred examples of the compound represented by the general formula (III) are shown in Table 1.

In addition to the compound represented by the general formula (I), another compound capable of crosslinking reaction may be used in combination. As such a compound, various silane coupling agents and commercially available silicone hard coat agents can be used.

  As silane coupling agents, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxy Silane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, tetramethoxysilane, methyltrimethoxysilane, Examples include dimethyldimethoxysilane.

  As a commercially available hard coat agent, KP-85, CR-39, X-12-2208, X-40-9740, X-4101007, KNS-5300, X-40-2239 (manufactured by Shin-Etsu Silicone), AY42-440, AY42-441, AY49-208 (manufactured by Toray Dow Corning) and the like.

  A fluorine-containing compound can be added to the protective layer 7 for the purpose of imparting surface lubricity. By improving the surface lubricity, the coefficient of friction with the cleaning member decreases, and the wear resistance can be improved. It also has the effect of preventing the adhesion of discharge products, developer, paper dust, etc. to the surface of the photoreceptor, which helps to improve the life of the photoreceptor.

As the fluorine-containing compound, a fluorine atom-containing polymer such as polytetrafluoroethylene can be added as it is, or fine particles of these polymers can be added. In the case of a cured film formed of the compound represented by the general formula (I), it is desirable to add a fluorine-containing compound that can react with an alkoxysilane and configure it as a part of the crosslinked film. Examples of such fluorine-containing compounds include (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, 3- (heptafluoro). Isopropoxy) propyltriethoxysilane, 1H, 1H, 2H, 2H-perfluoroalkyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorooctyltri An ethoxysilane etc. are mentioned.

  The content of the fluorine-containing compound is preferably 20% by mass or less based on the total amount of the protective layer 7. When the content of the fluorine-containing compound exceeds 20% by mass, a problem may occur in the film formability of the crosslinked cured film.

  Although the protective layer 7 containing the above compound has sufficient oxidation resistance, an antioxidant may be added for the purpose of imparting stronger oxidation resistance. Antioxidants are preferably hindered phenols or hindered amines, organic sulfur antioxidants, phosphite antioxidants, dithiocarbamate antioxidants, thiourea antioxidants, benzimidazole antioxidants. , Etc., may be used. As content of antioxidant, 15 mass% or less is preferable on the basis of the protective layer 7 whole quantity, and 10 mass% or less is more preferable.

  Examples of the hindered phenol antioxidant include 2,6-di-t-butyl-4-methylphenol, 2,5-di-t-butylhydroquinone, N, N′-hexamethylene bis (3,5-di). -T-butyl-4-hydroxyhydrocinnamide, 3,5-di-t-butyl-4-hydroxybenzylphosphonate-diethyl ester, 2,4-bis [(octylthio) methyl] -o-cresol, 2 , 6-di-t-butyl-4-ethylphenol, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 2,5-di-tert-amylhydroquinone, 2-tert-butyl-6- (3-butyl-2-hydroxy) Proxy-5-methylbenzyl) -4-methylphenyl acrylate, 4,4'-butylidene bis (3-methyl -6-t-butylphenol) and the like.

  In addition, other additives used for forming a known coating film can be added to the protective layer 7, and known materials such as a leveling agent, an ultraviolet absorber, a light stabilizer, and a surfactant are used. be able to.

  The protective layer 7 is formed by applying a coating solution containing the above compound onto the charge transport layer 6 and subjecting it to a heat treatment. Thereby, the compound etc. which are represented by general formula (I) raise | generate a crosslinking hardening reaction three-dimensionally, and a firm cured film is formed. The temperature of the heat treatment is not particularly limited as long as it does not affect the lower layer, but is preferably room temperature to 200 ° C, more preferably 100 to 160 ° C.

  The crosslinking curing reaction may be performed without a catalyst, or an appropriate catalyst may be used. Catalysts include acid catalysts such as hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, trifluoroacetic acid, bases such as ammonia and triethylamine, organotin compounds such as dibutyltin diacetate, dibutyltin dioctoate, stannous oxalate, Examples thereof include organic titanium compounds such as tetra-n-butyl titanate and tetraisopropyl titanate, iron salts of organic carboxylic acids, manganese salts, cobalt salts, zinc salts, zirconium salts, and aluminum chelate compounds.

  Moreover, in order to make easy application | coating of the coating liquid for protective layers, it can add and use a solvent as needed. Specifically, water, methanol, ethanol, n-propanol, i-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, Examples include methylene chloride, chloroform, dimethyl ether, and dibutyl ether. These solvents may be used alone or in a combination of two or more.

  Examples of the coating method include 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, and a curtain coating method.

  The thickness of the protective layer 7 thus formed is preferably 0.5 to 20 μm, more preferably 2 to 10 μm.

  In the case of constituting a single layer type photosensitive layer, the single layer type photosensitive layer is formed containing a charge generating material and a binder resin. The charge generation material is the same as that used for the charge generation layer in the function separation type photosensitive layer, and the binder resin is a binder resin used for the charge generation layer and the charge transport layer in the function separation type photosensitive layer. Similar ones can be used. The content of the charge generating material in the single-layer type photosensitive layer is preferably 10 to 85% by mass, more preferably 20 to 50% by mass, based on the total solid content in the single-layer type photosensitive layer. A charge transport material or a polymer charge transport material may be added to the single-layer type photosensitive layer for the purpose of improving photoelectric characteristics. The addition amount is preferably 5 to 50% by mass based on the total solid content in the single-layer type photosensitive layer. Moreover, the solvent and coating method used for coating can be the same as those for the above layers. The thickness of the single-layer type photosensitive layer is preferably about 5 to 50 μm, more preferably 10 to 40 μm. In the electrophotographic photosensitive member 1 shown in FIG. 3, the single-layer type photosensitive layer 3 may further include a protective layer 7 of the electrophotographic photosensitive member 1 shown in FIG.

Next, a preferred embodiment of the image forming apparatus of the present invention will be described.
FIG. 4 is a cross-sectional view schematically showing a basic configuration of an image forming apparatus according to another preferred embodiment of the present invention. An image forming apparatus 200 illustrated in FIG. 4 includes an electrophotographic photosensitive member 207, a charging device 208 that charges the electrophotographic photosensitive member 207, a power source 209 connected to the charging device 208, and an electrophotographic image that is charged by the charging device 208. An exposure device 210 that exposes the photosensitive member 207 to form an electrostatic latent image, a developing device 211 that develops the electrostatic latent image formed by the exposure device 210 with toner, and forms a toner image, and a developing device 211 The image forming apparatus includes a transfer device 212 that transfers the formed toner image to a transfer target medium (image output medium) 500, a cleaning device 213, a light static eliminator 214, and a fixing device 215.

  FIG. 5 is a cross-sectional view schematically showing a basic configuration of an image forming apparatus according to another preferred embodiment of the present invention. 5 transfers the toner image formed on the electrophotographic photosensitive member 207 to the primary transfer member 212a, and then is supplied between the primary transfer member 212a and the secondary transfer member 212b. A transfer device of an intermediate transfer system for transferring to a transfer target medium (image output medium) 500, and at the time of such transfer, a current having a predetermined current density is directed from the primary transfer member 212a to the electrophotographic photosensitive member. Supply is possible. The rest of the configuration is the same as in FIG.

  A charging device 208 in FIG. 4 is of a system (contact charging system) in which a conductive member (charging roll) is brought into contact with the surface of the electrophotographic photoreceptor 207 to charge the surface of the photoreceptor 207. In the present invention, a contactless charging device such as corotron or scorotron may be used instead of the contact charging device.

  As the contact-type charging member, a member in which an elastic layer, a resistance layer, a protective layer and the like are provided on the outer peripheral surface of the core material is preferably used. The shape of the conductive member may be any of a brush shape, a blade shape, a pin electrode shape, a roller shape, and the like.

  As the material of the core material, a conductive material such as iron, copper, brass, stainless steel, aluminum, nickel, or the like is used. Also, a resin molded product in which conductive particles or the like are dispersed can be used.

As the material of the elastic layer, a material having conductivity or semiconductivity, for example, a material in which conductive particles or semiconducting particles are dispersed in a rubber material can be used. EPDM, polybutadiene, natural rubber, polyisobutylene, SBR, CR, NBR, silicone rubber, urethane rubber, epichlorohydrin rubber, SBS, thermoplastic elastomer, norbornene rubber, fluorosilicone rubber, ethylene oxide rubber, chloroprene rubber, isoprene Rubber, epoxy rubber or the like is used. Examples of the conductive particles or semiconductive particles include carbon black, zinc, aluminum, copper, iron, nickel, chromium, titanium and other metals, ZnO—Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , In ₂ O ₃ — Metal oxides such as SnO ₂ , ZnO—TiO ₂ , MgO—Al ₂ O ₃ , FeO—TiO ₂ , TiO ₂ , SnO ₂ , Sb ₂ O ₃ , In ₂ O ₃ , ZnO, and MgO can be used. These materials can be used individually by 1 type or in mixture of 2 or more types.

  As the material of the resistance layer and the protective layer, conductive particles or semiconductive particles are dispersed in a binder resin, and the resistance is controlled. As binder resin, acrylic resin, cellulose resin, polyamide resin, methoxymethylated nylon, ethoxymethylated nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, polythiophene resin, PFA, FEP, A polyolefin resin such as PET, a styrene butadiene resin, or the like is used. As the conductive particles or semiconductive particles, the same carbon black, metal, and metal oxide as the elastic layer are used. If necessary, an antioxidant such as hindered phenol and hindered amine, a filler such as clay and kaolin, and a lubricant such as silicone oil can be added. As a means for forming these layers, blade coating method, Mayer bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain coating method, melt molding method, injection molding method, etc. should be used. Can do.

  When the photosensitive member is charged using these conductive members, a voltage is applied to the conductive member. The applied voltage may be a DC voltage or a DC voltage superimposed with an AC voltage. The shape of the contact-type charging member may be any shape such as a roller, a blade, or a belt, and can be arbitrarily selected according to the specifications and form of the image forming apparatus.

  There is no particular limitation on the charging method used in the electrophotographic photosensitive member of the present invention. However, in recent years, a contact charging method that generates less ozone and has a low environmental load tends to be used preferably. In general, the contact charging method has a weak charging ability as compared with non-contact charging methods such as scorotron and corotron, and is likely to be a problem particularly in an image forming apparatus that requires a high-speed response. When the charging capability is weak, the charge remaining in the photosensitive layer of the electrophotographic photosensitive member causes image quality defects such as ghost. However, according to the electrophotographic photosensitive member of the present invention, since the relationship between the cycle variation of the electrophotographic photosensitive member and the potential variation due to the influence of the transfer voltage is set to a predetermined state, the image quality defect as described above Is less likely to occur, and can be suitably used in combination with a contact charging system.

  As the exposure apparatus 210, an optical system apparatus that can expose a light source such as a semiconductor laser, an LED (light emitting diode), and a liquid crystal shutter on the surface of the electrophotographic photosensitive member in a desired image-like manner can be used.

  The toner used in the developing device 211 includes, for example, a binder resin and a colorant. Examples of the binder resin include homopolymers and copolymers such as styrenes, monoolefins, vinyl esters, α-methylene aliphatic monocarboxylic acid esters, vinyl ethers, and vinyl ketones. Typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescence, polyethylene, and polypropylene. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax, and the like can also be mentioned.

  Coloring agents include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, and lamp black. Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be cited as a representative example.

  The toner may be internally added or externally added with a known additive such as a charge control agent, a release agent, or other inorganic fine particles.

Typical examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.
Known charge control agents can be used, but charge control agents such as azo-based metal complex compounds, metal complex compounds of salicylic acid, and resin types containing polar groups can be used.

  As other inorganic fine particles, small-diameter inorganic fine particles having an average primary particle size of 40 nm or less are used for the purpose of powder flowability, charge control, etc., and if necessary, larger diameters are used to reduce adhesion. Inorganic or organic fine particles may be used in combination. As these other inorganic fine particles, known ones can be used.

  In addition, the surface treatment of the small-diameter inorganic fine particles is effective because the dispersibility becomes high and the effect of increasing the powder fluidity increases.

  As a method for producing the toner used in the present invention, a polymerization method such as an emulsion polymerization aggregation method or a dissolution suspension method is preferably used because high shape controllability can be obtained. In addition, a manufacturing method may be performed in which the toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to give a core-shell structure. When an external additive is added, it can be produced by mixing the toner and the external additive with a Henschel mixer or a V blender. Further, when the toner is manufactured by a wet method, it can be externally added by a wet method.

  The cleaning device 213 is for removing residual toner adhering to the surface of the electrophotographic photosensitive member after the transfer process. The cleaned electrophotographic photosensitive member is repeatedly used for the image forming process described above. . As the cleaning device, brush cleaning, roll cleaning, and the like can be used in addition to the cleaning blade. Among these, it is preferable to use the cleaning blade. Examples of the material for the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber.

  FIG. It is sectional drawing which shows typically the basic composition of the image forming apparatus which concerns on other suitable embodiment of this invention. The image forming apparatus shown in FIG. 6 is an intermediate transfer type image forming apparatus. In the housing 400, four electrophotographic photosensitive members 401a to 401d (for example, the electrophotographic photosensitive member 401a is yellow, the electrophotographic photosensitive member 401b is magenta, An image in which the electrophotographic photosensitive member 401c is cyan and the electrophotographic photosensitive member 401d is black can be formed in parallel with each other along the intermediate transfer belt 409.

  Each of the electrophotographic photosensitive members 401a to 401d can be rotated in a predetermined direction (counterclockwise on the paper surface), and the charging rolls 402a to 402d, the developing devices 404a to 404d, and the primary transfer roll 410a along the rotation direction. To 410d and cleaning blades 415a to 415d are arranged. Each of the developing devices 404a to 404d can supply toners of four colors of black, yellow, magenta, and cyan accommodated in toner cartridges 405a to 405d. These toners satisfy the condition that the average shape factor is 100 to 140. Further, the primary transfer rolls 410a to 410d are in contact with the electrophotographic photosensitive members 401a to 401d via the intermediate transfer belt 409, respectively.

  Further, a laser light source (exposure device) 403 is disposed at a predetermined position in the housing 400, and the surface of the electrophotographic photoreceptors 401a to 401d after charging is irradiated with laser light emitted from the laser light source 403. Is possible. Accordingly, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the electrophotographic photosensitive members 401a to 401d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 409 in an overlapping manner.

  The intermediate transfer belt 409 is supported with a predetermined tension by a drive roll 406, a backup roll 408, and a tension roll 407, and can rotate without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 413 is disposed so as to contact the backup roll 408 via the intermediate transfer belt 409. The intermediate transfer belt 409 passing between the backup roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed in the vicinity of the drive roll 406 and then repeatedly used for the next image forming process. Is done.

  A tray (transfer medium tray) 411 is provided at a predetermined position in the housing 400, and the transfer medium 500 such as paper in the tray 411 is transferred to the intermediate transfer belt 409 and the secondary transfer roll by the transfer roll 412. Then, the paper is sequentially transferred between the two fixing rolls 414 that are in contact with each other and the two fixing rolls 414, and then discharged to the outside of the housing 400.

  In the above description, the case where the intermediate transfer belt 409 is used as the intermediate transfer member has been described. However, the intermediate transfer member may have a belt shape like the intermediate transfer belt 409 or a drum shape. There may be. Conventionally known resins can be used as the resin material used as the base material of the intermediate transfer member in the belt shape. For example, polyimide resin, polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene terephthalate (PAT), ethylenetetrafluoroethylene copolymer (ETFE) / PC, ETFE / PAT, PC / PAT blend material, polyester Resin materials such as polyether ether ketone and polyamide, and resin materials using these as main raw materials. Furthermore, a resin material and an elastic material can be blended and used.

  As an elastic material, polyurethane, chlorinated polyisoprene, NBR, chloropyrene rubber, EPDM, hydrogenated polybutadiene, butyl rubber, silicone rubber, or the like can be used, or a material obtained by blending two or more kinds can be used. If necessary, a conductive agent imparting electronic conductivity or a conductive agent having ionic conductivity is added to the resin material and elastic material used for these base materials in combination of one kind or two or more kinds. Among these, it is preferable to use a polyimide resin in which a conductive agent is dispersed from the viewpoint of excellent mechanical strength. As the conductive agent, a conductive polymer such as carbon black, metal oxide, or polyaniline can be used.

  When a belt-shaped configuration such as the intermediate transfer belt 409 is employed as the intermediate transfer member, the thickness of the belt is generally preferably 50 to 500 μm and more preferably 60 to 150 μm, but is appropriately selected according to the hardness of the material. be able to.

  For example, a belt made of a polyimide resin in which a conductive agent is dispersed is 5 to 20% by mass as a conductive agent in a polyamic acid solution, which is a polyimide precursor, as described in JP-A-63-311263. After the carbon black is dispersed, the dispersion is cast on a metal drum and dried, and then the film peeled off from the drum is stretched at a high temperature to form a polyimide film. Can be produced.

  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 was formed into a film by a centrifugal molding method while being rotated, and then the obtained film was demolded in a semi-cured state and covered with an iron core, and subjected to a polyimide reaction (polyamide acid) at a high temperature of 300 ° C. or higher. It can be carried out by proceeding a ring-closing reaction) and carrying out main curing. 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 intermediate transfer member may have a surface layer.

  When a drum-shaped configuration is adopted as the intermediate transfer member, it is preferable to use a cylindrical substrate formed of aluminum, stainless steel (SUS), copper, or the like as the substrate. If necessary, an elastic layer can be coated on the cylindrical substrate, and a surface layer can be formed on the elastic layer.

In the transfer device of the present invention, the electric field strength applied to the photosensitive layer of the electrophotographic photosensitive member by the transfer voltage is in the range of 1.0 × 10 ⁵ V / cm or more and 4.0 × 10 ⁵ V / cm or less. Is preferable, and the range of 1.5 × 10 ⁵ V / cm to 3.0 × 10 ⁵ V / cm is more preferable. When the electric field strength applied by the transfer voltage is lower than 1.0 × 10 ⁵ V / cm, the influence of the potential fluctuation due to the charge behavior in the photosensitive layer becomes large, and positive ghost is likely to occur. On the other hand, when the electric field strength is larger than 4.0 × 10 ⁵ V / cm, the potential fluctuation due to the charge behavior in the undercoat layer becomes large and negative ghost is likely to occur.

  FIG. 7 is a sectional view schematically showing a preferred embodiment of the process cartridge of the present invention. In addition to the electrophotographic photosensitive member 207, the process cartridge 300 is provided with a charging device 208, a developing device 211, a cleaning device (cleaning means) 213, an opening 218 for exposure, and an opening 217 for static elimination exposure. Are combined and integrated with each other. The developing device 211 supplies toner to the electrophotographic photosensitive member 207.

  The process cartridge 300 is detachably attached to an image forming apparatus main body including a transfer device 212, a fixing device 215, and other components (not shown), and the image forming apparatus together with the image forming apparatus main body. It constitutes.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
Zinc oxide: (average particle diameter 70 nm: manufactured by Teica: BET specific surface area value 15 m ² / g) 100 parts by mass is stirred and mixed with 500 parts by mass of toluene, and a silane coupling agent (KBM603: manufactured by Shin-Etsu Chemical Co., Ltd.) 1.25 Part by mass was added and stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain a silane coupling agent surface-treated zinc oxide pigment.

  60 parts by mass of the surface-treated zinc oxide pigment, hardener blocked isocyanate Sumijour 3175 (manufactured by Sumitomo Bayern Urethane Co., Ltd.): 12 parts by mass, and 8 parts by mass of butyral resin BM-1 (manufactured by Sekisui Chemical Co., Ltd.) 60 parts by mass of a solution dissolved in 92 parts by mass of methyl ethyl ketone was dispersed for 0.3 hours with a paint shaker using 1 mmφ glass beads to obtain a dispersion.

  Here, the dispersion in the paint shaker is performed by using a glass bottle with a capacity of 200 mL, 100 g of glass beads, 100 g of a liquid obtained by mixing the zinc oxide pigment, blocked isocyanate smudge 3175, butyral resin BM-1 and methyl ethyl ketone in the above ratio. Was dispersed.

  Dioctyltin dilaurate: 0.005 parts by mass and silicone resin particle Tospearl 145 (manufactured by GE Toshiba Silicone): 3 parts by mass were added as catalysts to 120 parts by mass of the resulting dispersion to obtain an undercoat layer coating solution. . The obtained coating solution was applied on an aluminum substrate having a diameter of 24 mm, a length of 257 mm, and a thickness of 1 mm by a dip coating method, followed by drying and curing at 180 ° C. for 40 minutes to obtain an undercoat layer having a thickness of 24 μm. .

  Next, the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using Cukα rays is at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 15 parts by mass of hydroxygallium phthalocyanine having diffraction peaks at 25.1 ° and 28.3 °, 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH: manufactured by Nihon Unicar) as a binder resin, n -A mixture composed of 300 parts by mass of butyl acetate was subjected to a dispersion treatment for 100 minutes in a horizontal sand mill using glass beads of 1 mmφ to obtain a coating solution for a charge generation layer. The obtained coating solution was dip-coated on the undercoat layer and dried to form a charge generation layer having a thickness of 0.2 μm.

Next, 1 part by mass of tetrafluoroethylene resin particles, 0.02 part by mass of the fluorine-based graft polymer, 5 parts by mass of tetrahydrofuran, and 2 parts by mass of toluene were sufficiently stirred and mixed to obtain a tetrafluoroethylene resin particle suspension. . Next, 4 parts by mass of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine, a bisphenol Z-type polycarbonate resin ( Viscosity average molecular weight 40,000) 6 parts by mass, 23 parts by mass of tetrahydrofuran and 10 parts by mass of toluene are mixed and dissolved, and the tetrafluoroethylene resin particle suspension is added and mixed by stirring. Using a high-pressure homogenizer (trade name LA-33S, manufactured by Nanomizer Co., Ltd.) equipped with a pressure chamber, the dispersion treatment was repeated 6 times by increasing the pressure to 3.92 Pa (400 kgf / cm ² ). A dispersion was obtained. Further, 0.2 parts by mass of 2,6-di-t-butyl-4-methylphenol was mixed to obtain a coating solution for forming a charge transport layer. This coating solution was applied onto the charge generation layer and dried at 135 ° C. for 40 minutes to form a charge transport layer having a thickness of 17 μm to obtain an electrophotographic photoreceptor.

  The electrical characteristics of the obtained electrophotographic photosensitive member were measured with a continuous rotation type surface potential measuring device that can repeatedly perform charging, exposure, and photostatic discharge, and can measure the surface potential after photostatic discharge after exposure. . The measurement conditions of the continuous rotation type surface potential measuring device are as follows.

Charging to exposure: 172 ms
Exposure to surface potential meter 1: 74 ms
Surface potentiometer 1 to light neutralization: 388 ms
Photostatic to surface potential meter 2: 137 ms
Surface potential meter 2-Charging: 128 ms
Exposure light quantity: 1.6 mJ / m ²
Exposure wavelength: 780nm
Charging potential: -400V
Light neutralizing light quantity: 480 mJ / m ²
Light static elimination light source: Halogen lamp (select light with a wavelength of 600-800 nm with a filter)
Measurement temperature: 20 ° C
Measurement humidity: 40% RH

The potential fluctuation ΔVL (V) due to the charge behavior in the photosensitive layer and the potential fluctuation RP (V) due to the charge behavior in the undercoat layer were calculated by the following methods. The results are shown in Table 2.
ΔVL = (value of surface potential meter 1 in the second cycle) − (value of surface potential meter 1 in the first cycle)
RP = value of surface electrometer 2 at the first cycle

Further, the obtained electrophotographic photosensitive member was mounted on an image quality test apparatus obtained by modifying a full color printer (DELL: 5100cn) having a contact charging device and an intermediate transfer device, and the image quality of the output image was evaluated. The transfer voltage (VIDT) applied to the primary transfer member in contact with the photosensitive member was set to 400 V, and the ghost grade of the output image was evaluated. In addition, the transfer electric field strength applied to the photosensitive layer of the photosensitive member was as shown in Table 2. For the ghost evaluation image, an arbitrary number of 15 mm square patterns are printed for one round of the electrophotographic photosensitive member, and then the entire halftone image is printed in the next cycle, and the ghost image that appears on the halftone image is displayed. evaluated. Magenta was used for printing. The halftone image was created with a pattern of 1 dot ON-3 dots OFF. The image was printed at a temperature of 20 ° C. and a humidity of 40% RH. The ghost was visually graded and measured as follows.
Grade 0: Ghost cannot be seen at all Grade 1: Ghost appears to be very thin Grade 2: Ghost appears to be thin Grade 3: Ghost appears clearly Grade 4: Ghost appears dark Grade 5: Ghost appears extremely dark Of these, Grade If it is 1 or less, there is no problem in image quality. The results are shown in Table 2. In Table 2, “+” indicates a positive ghost and “−” indicates a negative ghost in the ghost grade column.

(Example 2)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the dispersion time of the undercoat layer coating solution was 0.5 hour. The results are shown in Table 2.

(Example 3)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the dispersion time of the undercoat layer coating solution was 1.0 hour. The results are shown in Table 2.

Example 4
In Example 2, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 2 except that the transfer voltage (VIDT) applied to the primary transfer member was 200V. The results are shown in Table 2.

(Examples 5-7)
In Example 2, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 2 except that the transfer voltage (VIDT) applied to the primary transfer member was set to the values shown in Table 2, respectively. The results are shown in Table 2.

(Example 8)
In Example 2, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 2 except that the thickness of the undercoat layer was 17 μm. The results are shown in Table 2.

(Examples 9 to 10)
In Example 2, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 2 except that the thickness of the undercoat layer was changed to the values shown in Table 2, respectively. The results are shown in Table 2.

(Comparative Example 1)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the dispersion time of the undercoat layer coating solution was changed to 0.2 hours. The results are shown in Table 2.

(Comparative Examples 2-3)

  In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the dispersion time of the undercoat layer coating solution was changed to the times shown in Table 2, respectively. The results are shown in Table 2.

(Examples 11 to 12)
In Example 2, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 2 except that the thickness of the undercoat layer was changed to the values shown in Table 2, respectively. The results are shown in Table 2.

  From the results of Table 2, in Examples 2-3, Examples 5-6, and Examples 8-10, no ghost was generated and a good output image was obtained. In Example 1, Example 4, and Example 7, a slight ghost was generated, but it was not at a level causing a particular problem in terms of image quality. Further, in Example 11, a slight minute black spot was observed, and in Example 7, the image density was slightly lowered, but this was not a problem level in terms of image quality.

  On the other hand, in Comparative Example 1, a strong positive ghost appeared, and in Comparative Examples 2 to 3, a strong negative ghost appeared.

1 is a schematic cross-sectional view showing a preferred embodiment of an electrophotographic photoreceptor of the present invention. FIG. 6 is a schematic cross-sectional view showing another preferred embodiment of the electrophotographic photosensitive member of the present invention. FIG. 6 is a schematic cross-sectional view showing another preferred embodiment of the electrophotographic photosensitive member of the present invention. 1 is a cross-sectional view schematically showing a basic configuration of an image forming apparatus according to a preferred embodiment of the present invention. It is sectional drawing which shows typically the basic composition of the image forming apparatus which concerns on other suitable embodiment of this invention. It is sectional drawing which shows typically the basic composition of the image forming apparatus which concerns on other suitable embodiment of this invention. 1 is a cross-sectional view schematically showing a preferred embodiment of a process cartridge of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electrophotographic photoreceptor, 2 ... Conductive substrate, 3 ... Photosensitive layer, 4 ... Undercoat layer, 5 ... Charge generation layer, 6 ... Charge transport layer, 7 ... Protective layer, 200, 220, 230 ... Image forming apparatus 207: Electrophotographic photosensitive member, 208: Charging device, 209 ... Power source, 210 ... Exposure device, 211 ... Development device, 212 ... Transfer device, 213 ... Cleaning device, 214 ... Photostatic device, 215 ... Fixing device, 216 ... Mounting rail, 217 ... opening for static elimination exposure, 218 ... opening for exposure, 300 ... process cartridge, 400 ... housing, 401a to 401d ... electrophotographic photosensitive member, 402a to 402d ... charging roll, 403 ... laser Light source (exposure device), 404a to 404d, developing device, 405a to 405d, toner cartridge, 406, driving roll, 407, tension roller 408 ... backup roll, 409 ... intermediate transfer belt, 410a to 410d ... primary transfer roll, 411 ... tray (transfer target tray), 412 ... transfer roll, 413 ... secondary transfer roll, 414 ... fixing roll, 415a ˜415d... Cleaning blade, 416... Cleaning blade, 500.

Claims (5)

In an electrophotographic photosensitive member having an undercoat layer and a photosensitive layer on a conductive support,
The undercoat layer includes fine metal oxide particles and a binder resin;
In addition, the electrophotographic photosensitive member satisfies the following formula (1) in the process of repeatedly charging, exposing, and photostaticizing the surface of the electrophotographic photosensitive member.
−3.0 ≦ (RP−ΔVL) /L≦−1.0 Formula (1)
(In the formula (1), ΔVL represents a difference obtained by subtracting the surface potential of the electrophotographic photosensitive member after the first cycle exposure from the surface potential of the electrophotographic photosensitive member after the second cycle exposure, and RP is: The surface potential of the electrophotographic photosensitive member after the first-stage photostatic charge is shown, and L is the thickness of the photosensitive layer.)   The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer has a thickness of 15 μm or more and 30 μm or less. The electrophotographic photosensitive member according to any one of claims 1 to 2,
A charging device for charging the electrophotographic photoreceptor;
An exposure device that exposes the electrophotographic photosensitive member charged by the charging device to form an electrostatic latent image; and
A developing device for developing the electrostatic latent image to form a toner image;
A transfer device for transferring the developed toner image to a transfer medium;
An image forming apparatus comprising: In the transfer device, a transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the surface of the electrophotographic photosensitive member, and an electric field strength applied to the photosensitive layer of the electrophotographic photosensitive member by the transfer voltage is 1. The image forming apparatus according to claim 3, wherein the image forming apparatus has a range of 0 × 10 ⁵ V / cm to 4.0 × 10 ⁵ V / cm.   3. The electrophotographic photosensitive member according to claim 1 and at least one selected from the group consisting of a charging device, an exposure device, and a cleaning device are integrally supported and detachably attached to the image forming apparatus main body. Process cartridge characterized by being.

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