JP5339050B2 - Electrophotographic photoreceptor, image forming method, image forming apparatus, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and device for suppressing reduction in electrostatic property, a scumming, an electrostatic charging failure for a long time without causing increase in exposure section potential, and also to provide a process cartridge for the image forming device. <P>SOLUTION: This image forming device has a conductive support, an intermediate layer, and a photosensitive layer. The intermediate layer contains amorphous oxide. The surface resistivity of the amorphous oxide is 1.0&times;10<SP>5</SP>&Omega;/cm<SP>2</SP>or less. The intermediate layer and the photosensitive layer are stacked on the conductive support in that order. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to an electrophotographic photosensitive member used in an electrophotographic image forming apparatus such as a copying machine, a laser printer, and a normal facsimile, a process cartridge for an image forming apparatus using the electrophotographic photosensitive member, an image forming apparatus, and The present invention relates to an image forming method.
In particular, the present invention provides an electrophotographic photosensitive member capable of suppressing a decrease in chargeability, background contamination, and poor charging without causing an increase in potential of an exposed portion even when the electrophotographic photosensitive member is used for a long time. And an image forming method, an image forming apparatus, and a process cartridge for the image forming apparatus using the same.

  In recent years, from the viewpoints of saving office space, expanding business opportunities, etc., electrophotographic image forming apparatuses are desired to be faster, smaller, more colored, and higher in image quality and easier to maintain. ing. Since these are related to improvement in characteristics and durability of an electrophotographic photosensitive member (hereinafter also simply referred to as a photosensitive member), they are positioned as problems to be solved by developing an electrophotographic photosensitive member. Yes. From the viewpoint of improving ease of maintenance, there is a reduction in the replacement frequency of the electrophotographic photosensitive member. This is to reduce the main image defects derived from the electrophotographic photosensitive member as much as possible over a long period of time, which is nothing but the extension of the life of the electrophotographic photosensitive member. In addition, in recent years, there have been many reports on development relating to extending the life of electrophotographic photosensitive members because they are related to the improvement of the image quality of output images over a long period of time.

  In order to achieve a long life of the electrophotographic photosensitive member, it is important to improve durability against various hazards that the electrophotographic photosensitive member receives from the image forming process. There are two types of hazards mentioned here: mechanical hazards and electrostatic hazards.

  An example of a mechanical hazard is one derived from blade cleaning, which is one of means for removing toner remaining on the electrophotographic photosensitive member after transfer of the image forming process (so-called toner cleaning process). Blade cleaning is a means for forcibly removing toner from the electrophotographic photosensitive member by contacting an elastic member (so-called cleaning blade) on the photosensitive member, and has a large toner removing ability in a small space. This is very effective for miniaturization of an electrophotographic apparatus. However, on the other hand, in the blade cleaning, the elastic member is brought into direct contact with the electrophotographic photosensitive member and rubbed, so that the mechanical stress on the electrophotographic photosensitive member is very large, and the layer disposed on the outermost surface of the photosensitive member. It has been pointed out that it is easy to wear. For this reason, in an electrophotographic apparatus to which a blade cleaning method is applied, wear of the electrophotographic photosensitive member often becomes a problem for extending the life, and a technique of laminating a high-hardness protective layer is proposed for this problem. (See Patent Documents 1 to 5).

  Next, the electrostatic hazard will be described. In a normal image forming process, an electric charge is applied to the surface of the electrophotographic photosensitive member, and after charging to a predetermined potential, the electric charge applied to the surface via the photosensitive member is removed by exposure to the electrophotographic photosensitive member. At this time, electrostatic stress is applied to the electrophotographic photosensitive member as charges pass through each layer (for example, a surface layer, a charge generation layer, a charge transport layer, and an intermediate layer) of the electrophotographic photosensitive member. Currently, the most widely used electrophotographic photoreceptors are composed of organic materials, and in the current electrophotographic processes in which repeated charging and discharging are repeated, the organics constituting the electrophotographic photoreceptor are included. The material gradually changes in quality due to the electrostatic hazard, and the electrophotographic characteristics are deteriorated as exemplified by generation of charge traps in the layer and change in chargeability. In particular, it is known that a decrease in chargeability has a great influence on the image quality of an output image, and causes serious problems such as a decrease in image density, background contamination, and image homogeneity during continuous output.

  Various reduction factors are cited for the reduction in chargeability of the photoreceptor. For example, it has been pointed out that the discharge product generated in the charging process in the image forming process affects the photoreceptor (see Patent Documents 6 to 8). This discharge product increases the bulk conductivity of the charge transport layer and the surface layer, thereby causing a decrease in chargeability of the electrophotographic photosensitive member. To solve the problem of such discharge products, a technique for suppressing a decrease in chargeability by adding an antioxidant to the charge transport layer or the surface layer has been disclosed (see Patent Document 8). In addition, a charging technique that generates less discharge products as a charging process has been disclosed (see Patent Documents 6 and 7). By applying this charging technique to a charging process in an image forming process, it is possible to suppress a decrease in charging property of the electrophotographic photosensitive member caused by a discharge product.

  Moreover, the deterioration of the intermediate layer can be considered as another factor of the decrease in chargeability. The intermediate layer widely used at present is in a form in which inorganic fine particles are dispersed in a binder made of an organic resin, and has a function of preventing charge injection from the conductive support to the photosensitive layer and occurs in the photosensitive layer. It is preferable to have a function of transporting charges to a conductive support.

When the function of preventing charge injection from the conductive support to the photosensitive layer is insufficient, for example, when charging an electrophotographic photosensitive member, a charge having a polarity opposite to the charged polarity of the photosensitive member is transferred from the conductive support to the photosensitive layer. However, it is easy to erase the charge on the surface of the photosensitive member, which causes a problem that it is difficult to obtain a desired charge.
In addition, when the charge transport function of the charge generated in the photosensitive layer to the conductive support is insufficient, for example, the exposed portion potential increases due to a decrease in charge generation efficiency, or charging failure occurs due to charge trapping in the intermediate layer. easy. Further, when the photoconductor is used for a very long time, a phenomenon that the photoconductor becomes difficult to be charged is observed. It is assumed that this phenomenon is caused by charge accumulation in the vicinity of the intermediate layer. be able to.

  For this reason, various techniques have been developed for the compatibility and maintenance of the two functions of the charge injection blocking function and the charge transport function, but these functions are easy to take a reciprocal relationship, It is very difficult to maintain. For example, a technique for improving the charge injection blocking function by applying a high insulating layer as a constituent layer of the intermediate layer has been disclosed (see Patent Documents 9 and 10). When this technology is used for electrophotographic photoreceptors, it is reported that image defects such as scumming due to a decrease in chargeability of the photoreceptor are extremely small, and extremely good output images are maintained even after repeated use. Has been. However, the charge transport function from the charge generation material to the conductive support, which is another function to be performed by the intermediate layer, becomes insufficient. It is easy to manifest.

  In addition, for example, in an image forming process in which the surface of an electrophotographic photosensitive member is negatively charged, a technique for blending an electron transport material into an intermediate layer of the electrophotographic photosensitive member has been disclosed (see Patent Document 11). According to such a technique, it is difficult for charges of the opposite polarity on the surface of the photoreceptor (in this case, positive charges) to be injected from the conductive support to the photosensitive layer and to transport negative charges generated in the charge generation layer to the conductive support. Thus, an intermediate layer satisfying both of the two functions required for the above-described intermediate layer can be obtained. When this intermediate layer is applied to an electrophotographic photosensitive member, it exhibits very good electrophotographic characteristics in the initial stage. However, in the technique according to Patent Document 11, the organic material constituting the intermediate layer is likely to be deteriorated by repeated electrostatic hazards, and the deep trap order is easily formed due to the influence of oxygen in the air on the electron transport material. For reasons such as being easy to form charge traps, it is a problem that electrophotographic characteristics are degraded by repeated electrostatic hazards. In addition, there is a problem that few electron transport materials exhibit excellent electron transfer characteristics.

JP-A-5-181299 JP 2002-6526 A JP 2002-82465 A JP 2000-284514 A JP 2001-194413 A JP-A-9-26685 JP 2002-229241 A JP 2006-99028 A Japanese Patent Laid-Open No. 3-45762 Japanese Patent Laid-Open No. 7-281463 JP 2006-259141 A

  Thus, in order to achieve a long life of the electrophotographic photosensitive member, it is important to impart durability to various hazards that the electrophotographic photosensitive member receives from each process in image formation. And this invention pays attention to the durability with respect to an electrostatic hazard among these various hazards.

  That is, the present invention has been made in view of the above problems in the prior art, and it is possible to suppress a decrease in chargeability, background contamination, and charging failure over a long period of time without causing an increase in the potential of the exposed portion. Another object of the present invention is to provide an electrophotographic photosensitive member, an image forming method using the same, an image forming apparatus, and a process cartridge for the image forming apparatus.

As a result of intensive studies, the present inventors have at least a conductive support, an intermediate layer, and a photosensitive layer, and the intermediate layer includes an amorphous oxide, and the amorphous oxide The surface resistivity is 1.0 × 10 ⁵ Ω / cm ² or less, and the above problem is solved by laminating the intermediate layer and the photosensitive layer in this order on the conductive support. The headline and the present invention were completed.

Specifically, in order to solve the above-described problems, the electrophotographic photosensitive member according to the present invention, the image forming method using the same, the image forming apparatus, and the process cartridge for the image forming apparatus are specifically described in the following (1) to ( 1). It has the technical features described in 9) .

(1): having a conductive support, an intermediate layer, and a photosensitive layer, the intermediate layer containing an amorphous oxide, and the surface resistivity of the amorphous oxide is 1.0 × 10 ⁵ Ω / cm ² or less, and the photosensitive layer contains a titanyl phthalocyanine pigment and is laminated on the conductive support in the order of the intermediate layer and the photosensitive layer. Is the body.

(2) The electrophotographic photosensitive member according to (1), wherein the amorphous oxide contains indium, zinc, and gallium.

(3) The electrophotographic photosensitive member according to (1) or (2), wherein the intermediate layer has a thickness of 0.1 μm or more and 0.9 μm or less.

(4) The electrophotographic photosensitive member according to any one of (1) to (3), wherein the conductive support has a surface roughness Rz of 0.6 μm or more.

(5) The electrophotographic photosensitive member according to any one of (1) to (4), wherein the photosensitive layer includes a charge generation layer and a charge transport layer.

(6) : A charging process for charging the electrophotographic photosensitive member, a latent image forming process for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging process, and the latent image forming process. An image obtained by repeatedly performing a development process for forming a visible image by attaching toner to the image portion of the electrostatic latent image and a transfer process for transferring the visible image formed by the development process to a transfer target In the forming method, the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of the above (1) to (5) .

(7) : an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, a latent image forming unit for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging unit, Developing means for forming a visible image by attaching toner to the image portion of the electrostatic latent image formed by the latent image forming means, and transfer for transferring the visible image formed by the developing means to a transfer target An electrophotographic photosensitive member according to any one of (1) to (5) above, wherein the electrophotographic photosensitive member is an image forming apparatus.

(8) : an electrophotographic photosensitive member, a charging unit that charges the electrophotographic photosensitive member, a latent image forming unit that forms an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging unit, and One or more means selected from a developing means for forming a visible image by attaching toner to the image portion of the electrostatic latent image formed by the latent image forming means, and is detachable from the image forming apparatus. A process cartridge for an image forming apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of (1) to (5). is there.

(9) An image forming apparatus comprising the process cartridge for an image forming apparatus according to (8) , which is detachable.

  According to the present invention, an image forming method, an image forming apparatus, and an image forming apparatus capable of suppressing chargeability deterioration, background contamination, and charging failure over a long period of time without causing an increase in exposure portion potential. A process cartridge can be provided.

[Electrophotographic photoconductor]
The electrophotographic photoreceptor according to the present invention includes a conductive support, an intermediate layer, and a photosensitive layer, and the intermediate layer includes an amorphous oxide, and the surface resistivity of the amorphous oxide is 1.0 × 10 ⁵ Ω / cm ² or less, and the intermediate layer and the photosensitive layer are laminated in this order on the conductive support.

First, the electrophotographic photoreceptor according to the present invention will be described in detail from the functional side.
In the electrophotographic photosensitive member according to the present invention, the intermediate layer has a function of suppressing injection of unnecessary charges (charges having a polarity opposite to the charged polarity of the photosensitive member) from the conductive support to the photosensitive layer (charge injection blocking function). And a function of transporting charges having the same polarity as the charged polarity of the photoreceptor among the charges formed in the photosensitive layer (charge transport function).
For example, when it is necessary to negatively charge the photoreceptor as an image forming process, the intermediate layer has a hole injection blocking function (hole blocking property) from the conductive support to the photosensitive layer, and the conductive support from the photosensitive layer. It is necessary to combine the function of transporting electrons to the body (electron transportability). In order to obtain a long-life electrophotographic photosensitive member, it is important that the two functions described above do not change due to repeated electrostatic hazards.

<Configuration of electrophotographic photosensitive member>
Next, the configuration of the electrophotographic photosensitive member according to the present invention will be described in more detail with specific examples.
Although the embodiments described below are preferred embodiments of the present invention, various technically preferable limitations are attached thereto, but the scope of the present invention is intended to limit the present invention in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

The electrophotographic photoreceptor according to the present invention includes at least a conductive support, an intermediate layer, and a photosensitive layer, and the intermediate layer and the photosensitive layer are stacked in this order on the conductive support. Being done. Here, the photosensitive layer may have a single layer structure or a multilayer structure including a charge generation layer and a charge transport layer as long as it has a charge generation function and a charge transport function.
Further, a wear-resistant surface layer may be further laminated on the photosensitive layer for the purpose of improving the above-mentioned mechanical hazard durability. Examples of the surface layer include a heat-crosslinking surface layer, an ionizing radiation-crosslinking surface layer, and a particle-dispersed surface layer.

FIG. 1 is a schematic view showing an example of a configuration in which a photosensitive layer 36 as an embodiment of the electrophotographic photosensitive member according to the present invention is a single layer type.
In this example, an intermediate layer 32 is provided on a conductive support 31, and a photosensitive layer 36 mainly composed of a charge generation material and a charge transport material is provided thereon.

FIG. 2 is a schematic view showing an example of a configuration in which the photosensitive layer 36, which is another embodiment of the electrophotographic photoreceptor according to the present invention, is a laminated type, and FIG. 3 is another diagram of the electrophotographic photoreceptor according to the present invention. It is the schematic which shows the other example of the structure by which the photosensitive layer 36 which is embodiment of this is a lamination type.
In these examples, the intermediate layer 32 is laminated on the conductive support 31, and the charge generation layer 33 responsible for the charge generation function and the charge transport layer 34 responsible for the charge transport function are separated on the intermediate layer 32. It is the thing of the laminated | stacked aspect. Note that the order of stacking the charge generation layer and the charge transport layer is not particularly limited as shown in FIGS. 2 and 3 and can be properly used depending on the application. However, many charge generation materials have poor chemical stability, and when exposed to an acidic gas such as a discharge product around a charger in an electrophotographic image forming process, the charge generation efficiency is reduced. For this reason, it is preferable to stack the charge transport layer 34 on the charge generation layer 33.
Further, each layer will be described in detail.

<Intermediate layer>
First, details of the intermediate layer, which is a feature of the electrophotographic photoreceptor according to the present invention, will be described.
In the electrophotographic photoreceptor according to the present invention, the intermediate layer contains an amorphous oxide, and the surface resistivity of the amorphous oxide is 1.0 × 10 ⁵ Ω / cm ² or less.

  In order for the intermediate layer to have the above-described hole blocking properties, the ionization potential of the intermediate layer or the work function in the electron full band is larger than the Fermi rank of the conductive support, and the hole transport property of the intermediate layer itself is extremely high. Small is needed. An example of a material having such a hole blocking property and suitable as a material for the intermediate layer is an n-type semiconductor material. In addition, from the viewpoint of work function, those having a relatively large band gap can also be mentioned.

On the other hand, in order for the intermediate layer to transport the electrons generated in the above-described photosensitive layer to the conductive support (having electron transport properties), the electron affinity of the photosensitive layer is smaller than the electron affinity of the intermediate layer. Is required to have an electron transporting property.
Suitable materials for the intermediate layer having such an electron transport property include an electron transport layer formed by dispersing an organic material having an electron transport structure in a binder, and an n-type inorganic semiconductor. Etc. are exemplified. Moreover, as a material in which the electron transportability is not easily changed by electrostatic hazard, an n-type inorganic semiconductor material as shown in the latter is preferable. Further, in consideration of in-plane variation of electrical characteristics in a device having a relatively large area as typified by an electrophotographic photoreceptor, an amorphous material is preferable.

Therefore, the intermediate layer in the present invention preferably comprises an amorphous oxide, and further comprises only an amorphous oxide. Here, the amorphous oxide means a solid state oxide having an irregular atomic arrangement.
This amorphous oxide is roughly divided into a glass oxide semiconductor obtained by quenching an oxide in a fluid state at a high temperature and an amorphous oxide formed at a relatively low temperature by a technique such as sputtering. can do. In consideration of the heat resistance of the conductive support, it is preferable to select an amorphous oxide as mentioned in the latter.

  In the present invention, the amorphous oxide applied to the intermediate layer is not particularly limited. For example, indium oxide, oxide containing at least two elements of indium, zinc, and tin, two elements of indium, zinc, and gallium are used. Alternatively, an oxide containing all three elements is exemplified. Among these, an amorphous oxide composed of three elements of indium, zinc, and gallium is preferable as being included in the intermediate layer of the electrophotographic photosensitive member.

<Method for forming amorphous oxide film>
The method for forming an amorphous oxide on a conductive support is not particularly limited as long as it is a generally used method for forming an inorganic material. General film forming methods are roughly classified into a vapor phase growth method, a liquid phase growth method, and a solid phase growth method. Vapor deposition is further classified into physical vapor deposition (PVD) and chemical vapor deposition (CVD). Examples of physical vapor deposition include vacuum deposition, electron beam deposition, and laser ablation. , Laser ablation MBE, MOMBE, reactive deposition, ion plating, cluster ion beam method, glow discharge sputtering, ion beam sputtering, reactive sputtering, and the like. Examples of the liquid phase growth method include thermal CVD, MOCVD, RF plasma CVD, ECR plasma CVD, photo CVD, and laser CVD. Examples of the liquid phase method include an LPE method, an electroplating method, an electroless plating method, and a coating method. Examples of the solid phase method include SPE, recrystallization method, graphoepitaxy, LB method, and sol-gel method.

  Of these film forming methods, physical vapor deposition is widely used to form a homogeneous film in a relatively large area such as an electrophotographic photosensitive member. Among these, the laser ablation method is preferable when fine composition control of the amorphous oxide is necessary, and various sputtering methods are preferable when mass productivity is required.

<< Filming conditions for amorphous oxide >>
Next, the film formation conditions for the amorphous oxide, particularly the film formation conditions for the sputtering method will be described in detail.

-Substrate cleaning-
In order to obtain an amorphous oxide exhibiting uniform electrical characteristics, it is very important to clean the substrate on which the amorphous oxide is formed, that is, the conductive support in the present invention. The surface of a clean conductive support is ideally free of contaminants other than at least a conductive support (eg, aluminum), but it is very difficult to achieve that condition. Therefore, it is preferable to obtain a desired conductive support surface by applying a generally proposed cleaning method in accordance with the amount of surface contaminants required and the performance of the apparatus used in the experiment. Examples of the cleaning method include a wet cleaning method, a sputter etching method, a high temperature thermal etching method, a low temperature thermal etching method, an electron beam irradiation etching method, a synchrotron radiation irradiation etching method, and a laser light irradiation etching method.

-Target-
In forming an amorphous oxide on a conductive support by a sputtering method, a polycrystalline sintered body containing a constituent element of the formed amorphous oxide is generally used. The element used for the polycrystalline sintered body may be appropriately selected depending on the constituent element of the amorphous oxide to be formed.
In order to obtain an amorphous oxide composed of indium, zinc and gallium, it is necessary to use a polycrystalline sintered body containing at least indium, zinc and gallium. This polycrystalline sintered body can be manufactured by a generally known target manufacturing method. As an example of the production method, each powder of indium oxide, zinc oxide and gallium oxide can be blended at a desired blending ratio, and it can be obtained by wet mixing using ethanol until homogeneous and then sintering. It is.
Further, for the purpose of controlling the conductivity of the amorphous oxide, a desired impurity may be blended in advance with the target. The metal to be doped is not particularly limited, and examples thereof include Li, Na, Mn, Ni, Pd, Cu, Cd, C, N, P, Ti, Zr, V, Ru, Ge, Sn, and F. .

−Film forming pressure−
In the sputtering method, plasma is generated by applying an electric field on a target during film formation. For this reason, when the sputtering method is used, it is necessary to form a reduced pressure atmosphere using a vacuum chamber or the like. If the pressure during film formation is insufficient, plasma cannot be formed or the plasma is unstable, so care must be taken because the formed film becomes non-uniform. The reduced pressure atmosphere may be appropriately selected from the film forming method, apparatus, conditions, desired film quality, and the like.

-Inflow gas type-
In the sputtering method, a plasma is formed while flowing a mixed gas of an inert gas and an oxygen gas into a reduced-pressure atmosphere, so that an amorphous material is formed on the substrate (conductive support in the present invention) disposed on the counter electrode. A quality oxide can be formed. The inert gas used here is not particularly limited as long as it is generally used, and examples thereof include helium, argon as represented by Group 18 elements, and other gases represented by nitrogen gas. . Moreover, in order to add the said impurity, you may use together 1 or more types of gas in addition to an inert gas and oxygen.

-Oxygen partial pressure-
A general oxide semiconductor has a characteristic that the conductivity can be controlled by the amount of oxygen (oxygen deficiency) in the oxide semiconductor without doping impurities. The same applies to the amorphous oxide in the present invention. It has the properties of This property indicates that the conductivity control of the amorphous oxide can be controlled only by the oxygen flow rate (oxygen partial pressure) at the time of film formation, and the resistivity control described later is also generally controlled by the oxygen partial pressure at the time of film formation. Since it can be performed by controlling the film thickness, it becomes an important film forming condition.
The proportion of oxygen gas flowing during film formation varies depending on the apparatus and other conditions described later, but is generally 0.05 vol% or more and 20 vol% or less, preferably 0.1 vol% or more and 15 vol% with respect to the total gas flow rate. The following is preferred. If it exceeds 20 vol%, the carrier concentration of the amorphous oxide formed becomes too low, which is not preferable because the electron conductivity becomes extremely low.

-Target / substrate distance-
It is known that the amount of oxygen (amount of oxygen vacancies) in the amorphous oxide changes by changing the target / substrate distance. In general, when the target / substrate distance is increased, the amount of oxygen deficiency decreases and the formed amorphous oxide becomes a high resistance body. On the other hand, when the distance between the target and the substrate is reduced, a homogeneous film is produced due to the influence on the film quality due to the substrate temperature rising by the plasma on the target surface, and the influence of the plasma itself on the amorphous oxide. Note that this may be difficult. Since the target / substrate distance differs depending on the film forming method, apparatus, and other film forming conditions, it is preferable to select a target / substrate distance that provides desired electrical characteristics.

-Substrate temperature-
In the sputtering method, the temperature of the substrate tends to rise due to the discharge of the target surface. The substrate temperature is controlled by methods such as cooling the substrate and increasing the distance between the target and the substrate because it is known that the increase in the substrate temperature affects the electrical properties, denseness, and structure of the film. It is preferable. Further, a cooling jacket or the like may be provided in order to prevent the substrate temperature from being overheated during sputtering.

<Film quality of amorphous oxide>
In the present invention, attention should be paid to the film quality of the amorphous oxide and the like, and by making this preferable, desirable characteristics as an intermediate film, and thus desirable characteristics as an electrophotographic photoreceptor can be obtained.
For example, in the present invention, it is important that the intermediate layer is a homogeneous amorphous film. A method for confirming that the film formed on the conductive support is amorphous is generally determined by crystal structure analysis by X-ray diffraction. In addition, a structure analysis method such as an electron diffraction method or a neutron diffraction method, or a method using a microstructure observation means such as a TEM may be used to determine the cross section of the formed film.
Further, as a feature of the amorphous oxide that affects electrophotographic characteristics, the composition and composition distribution of the film are important. As a composition analysis method of an amorphous oxide, a method generally used as an elemental analysis method can be applied. For example, fluorescent X-ray analysis, X-ray photoelectron spectroscopy, Auger electron spectroscopy, energy dispersive X-ray A constituent element analysis method of a substance such as spectroscopy is exemplified.

<< Electrical properties of amorphous oxide >>
In the present invention, by setting the surface resistivity of the amorphous oxide used for the intermediate layer to 1.0 × 10 ⁵ Ω / cm ² or less, an excellent electrophotographic photosensitive member having high durability against electrostatic hazard can be obtained. Can be obtained. There are many unclear points at present regarding this reason. However, when an amorphous oxide as in the present invention is used for an intermediate layer, the interaction between the photosensitive layer and the intermediate layer occurs when the surface resistivity of the intermediate layer is high. It is assumed that charge traps are likely to occur between both layers, and charge accumulation is likely to occur between the photosensitive layer / intermediate layer. For these reasons, it is considered that when a long-term electrostatic hazard is applied, unnecessary charges are accumulated in the photoconductor, resulting in a decrease in chargeability and image defects. On the other hand, when an amorphous oxide having a low surface resistance is applied to the intermediate layer, it is considered that unnecessary charge in the photosensitive layer is reduced, so that chargeability and image defects are less likely to occur. According to the verification by the inventors, when the surface resistivity of the amorphous oxide is 1.0 × 10 ⁵ Ω / cm ² or less, the change in chargeability before and after the electrostatic hazard load is small. When it is larger than 1.0 × 10 ⁵ Ω / cm ² , the change in charging property before and after the electrostatic hazard load is large, and particularly when it is larger than 1.0 × 10 ⁷ Ω / cm ^2, it remains with a decrease in charging property. An increase in potential was also confirmed.

The surface resistivity of the amorphous oxide is preferably 1.0 × 10 ⁵ Ω / cm ² or less, more preferably 1.0 × 10 ⁴ Ω / cm ² or less.
As a method for measuring the surface resistance of the amorphous oxide, a generally used surface resistivity measuring method can be used. Specifically, for a low resistance body having a surface resistivity of 10 ⁶ Ω / cm ² or less, a constant current application method described in JIS K 7194 is exemplified. As for a high resistance pair having a surface resistivity of 10 ⁶ Ω / cm ² or more, a constant voltage application / leakage current measurement method described in JIS K 6911 is exemplified. Further, the measurement may be performed by other generally known methods such as a four-probe method, a four-terminal method, and a two-terminal method.

  In addition, the electrical characteristics other than the surface resistivity of the amorphous oxide described above greatly affect the electrical characteristics of the electrophotographic photosensitive member. Therefore, in order to obtain the desired electrical characteristics of the electrophotographic photosensitive member, it is applied to the intermediate layer. It is necessary to appropriately select the electrical characteristics of the amorphous oxide. The following are typical examples of other electrical characteristics of the amorphous oxide.

-Carrier concentration-
As described above, the amount of oxygen deficiency (so-called carrier concentration) in the film can be controlled by doping the amorphous oxide without doping an impurity metal or the like according to the amount of oxygen flowing during film formation. In addition, the carrier concentration can be adjusted by appropriately doping impurities. As a method for quantifying the carrier concentration, a method using the Hall effect is generally used.

-Band gap-
In the present invention, the band gap of the amorphous oxide is also considered to be related to the characteristics of the electrophotographic photosensitive member, particularly the hole blocking property from the conductive support. It is preferable to appropriately select a work function in a full band of amorphous oxide.

  Examples of the band gap measurement method include an electrochemical measurement method and a photochemical measurement method. For example, a band gap energy measurement method using a Tauc plot, which is one of the photochemical measurement methods, can be exemplified. In general, in the region of relatively large absorption near the optical absorption edge on the long wavelength side of the semiconductor, the absorption coefficient α, the light energy hν (where h is the Planck constant, and ν is the wave number), and the band cap. It is considered that the following equation holds between the energy E0.

αhν = B (hν−E0) ² (B is a constant)

Therefore, the absorption spectrum is measured, hν is plotted against the (αhν) ^1/2 (so-called Tauc plot), and the value of hν at α = 0 obtained by extrapolating the straight section becomes the band gap energy.
The band gap may be measured by using the above-described method, and when a characteristic value that is synonymous electrochemically and photochemically can be obtained, it is not particularly limited, and various measurement methods may be used.

<Film thickness of amorphous oxide>
Further, it is considered that the film thickness of the amorphous oxide used for the intermediate layer also affects the electrical characteristics of the electrophotographic photoreceptor.
Currently, the light source widely used in the exposure process is a highly coherent laser beam, so moire is likely to occur due to the interference between the incident laser beam and the reflected light from the conductive support, and this is suppressed. For the purpose, the surface of the conductive support often has arbitrary irregularities. Also, the surface of the conductive support often has arbitrary irregularities for the purpose of compensating for the physical contact between the conductive support and the intermediate layer.
In such a case, when the film thickness of the intermediate layer is small, the film thickness deviation becomes large due to the surface unevenness of the conductive support, and there is a possibility that partial charging failure occurs. In addition, when an amorphous oxide is used for the intermediate layer, it is not preferable that the film thickness is too large because the composition variation in the film depth direction increases, resulting in variation depending on the position of the electrical characteristics. Furthermore, if the film thickness is too large, the time required for film formation becomes long, so the cost for film formation becomes very large, which is not realistic.

  Therefore, in the present invention, the thickness of the intermediate layer is preferably 0.05 μm or more and 1.5 μm or less, and more preferably 0.1 μm or more and 0.9 μm or less. When the intermediate layer is less than 0.05 μm, it is difficult to uniformly coat the surface of the conductive support, and the effect of providing the intermediate layer cannot be exhibited sufficiently. On the other hand, when the intermediate layer exceeds 1.5 μm, the film forming cost is excessively high, and there is a possibility that the electrical characteristics of the intermediate layer may be different between the vicinity of the conductive support and the vicinity of the photosensitive layer.

<Photosensitive layer (laminated photosensitive layer)>
Next, the photosensitive layer laminated on the intermediate layer will be described. Here, a multilayer photosensitive layer including a charge generation layer and a charge transport layer will be described first, and then a single layer type photosensitive layer having both a charge generation function and a charge transport function will be described.

<Charge generation layer>
The charge generation layer is a layer mainly composed of a charge generation material having a charge generation function, and a binder resin can be used in combination as necessary. As the charge generation material, inorganic materials and organic materials can be used.

  Inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, and amorphous silicon. In amorphous silicon, dangling bonds that are terminated with hydrogen atoms or halogen atoms, or those that are doped with boron atoms, phosphorus atoms, or the like are preferably used.

  On the other hand, a known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having a carbazole skeleton, azo pigments having a triarylamine skeleton, azo pigments having a diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. In the present invention, it is confirmed that excellent electrophotographic photoreceptor characteristics can be maintained over a long period of time by applying a phthalocyanine pigment among the charge generating materials listed above. The reason why the phthalocyanine pigment is preferable is not well understood, but it is considered that it is difficult to interact with the amorphous oxide.

  As described above, the phthalocyanine pigment used in the present invention includes metal-free phthalocyanine or metal phthalocyanine, and synthetic methods described in Moser and Thomas' “phthalocyanine compound” (Rheinhold, 1963), and others. Those obtained by an appropriate method are used.

  Examples of metal phthalocyanines include those having a central metal such as copper, silver, beryllium, magnesium, calcium, zinc, indium, sodium, lithium, titanium, tin, lead, vanadium, chromium, manganese, iron, cobalt, etc. . Further, a metal halide having a valence of 3 or more may be present in the central nucleus of phthalocyanine instead of the metal atom. Various crystal forms of phthalocyanine are known, but known forms such as crystal forms such as α-type, β-type, Y-type, ε-type, τ-type, and X-type, and amorphous forms can be used.

  Further, as the phthalocyanine pigment used in the present invention, as shown in the following general formula (A), titanyl phthalocyanine (hereinafter referred to as TiOPc) having titanium as a central metal is particularly desirable because it has particularly high sensitivity and excellent characteristics.

In the formula, X ₁ , X ₂ , X ₃ and X ₄ each independently represent various halogen atoms, and n, m, l and k each independently represent a number of 0 to 4.

  The titanyl phthalocyanine used here is an electrophotographic titanyl phthalocyanine having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.514 波長) of CuKα. Even when the sensitivity of the photoreceptor is increased and the combination with the intermediate layer made of an amorphous oxide, stable photoreceptor characteristics can be expressed over a long period of time, which is very effective.

  From the viewpoint of increasing the sensitivity of the photoreceptor, it is desirable to reduce the particle size of the phthalocyanine pigment used. The reason for this is that many of the photocarriers generated inside the charge generation material particles have a shorter moving distance to the particle surface, so the possibility of deactivation before reaching the carrier generation site on the particle surface is reduced. (Increased photocarrier generation efficiency) Further, as the particle size is reduced, the surface area is increased, and the photocarrier injection efficiency is increased based on the increased amount of contact with the charge transporting material surrounding the pigment particle surface. By these actions, it is considered that the light sensitivity can be increased by using the small particle size phthalocyanine pigment.

  Here, the average particle size of the phthalocyanine pigment is preferably 0.6 μm or less, more preferably 0.4 μm or less. Examples of the method for measuring the average particle diameter of the pigment include known methods such as a centrifugal separation method, a laser diffraction method, a dynamic light scattering method, and an electrical detector method. Unless otherwise specified, this is a volume average particle size measured by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba Seisakusho), and a particle size corresponding to 50% of the cumulative distribution (Median series) ).

  As a binder resin used as necessary for the charge generation layer, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, Examples include polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, and polyvinyl pyrrolidone. These binder resins can be used alone or as a mixture of two or more. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generating material. The binder resin may be added before or after dispersion.

  Methods for forming the charge generation layer include a vacuum thin film preparation method and a casting method from a solution dispersion system. As the former method, a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used, and the above-described inorganic materials and organic materials can be satisfactorily formed. In addition, in order to provide the charge generation layer by the latter casting method, the inorganic or organic charge generation material described above, together with a binder resin, if necessary, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclohexane. It can be formed by dispersing with a ball mill, attritor, sand mill, bead mill or the like using a solvent such as pentanone, anisole, xylene, methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, etc., and applying the solution after appropriately diluting the dispersion. Moreover, leveling agents, such as a dimethyl silicone oil and a methylphenyl silicone oil, can be added as needed. The coating can be performed using a dip coating method, spray coating, bead coating, ring coating method or the like.

  The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

<Charge transport layer>
The charge transport layer is a layer having a charge transport function, and is a layer mainly composed of a charge transport material and a binder resin.
Charge transport materials include hole transport structures such as triarylamine, hydrazone, pyrazoline, and carbazole, for example, electron transport structures such as condensed polycyclic quinone, diphenoquinone, electron-withdrawing aromatic rings having a cyano group and a nitro group. A compound to be used, that is, an electron transport material or a hole transport material.

  Examples of the electron transporting material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and diphenoquinone derivatives. These electron transport materials can be used alone or as a mixture of two or more.

  Examples of the hole transport material include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, etc. Other known materials may be used. These hole transport materials may be used alone or in combination of two or more.

  When these materials are used to form a charge transport layer, they are dispersed in a binder described later. The charge transport material is preferably 20 to 80% by weight, more preferably 30 to 70% by weight, based on the total weight of the charge transport layer.

  Further, a polymer charge transporting material having both a binder resin function and a charge transporting material function described later may be used. The charge transport layer containing the polymer charge transport material has durability against the above-mentioned mechanical hazard, and in combination with the intermediate layer having durability against electrostatic hazard, the life of the electrophotographic photosensitive member Can be extended dramatically.

  A known material can be used as the polymer charge transport material, but at least one polymer selected from polycarbonate, polyurethane, polyester, and polyether is preferable. In particular, a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferable. Among these, polymer charge transport materials represented by the following formulas (3) to (12) are preferably used.

In formula (3), R ₁ , R ₂ and R ₃ are each independently a substituted or unsubstituted alkyl group or a halogen atom, R ₄ is a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₅ and R ₆ are A substituted or unsubstituted aryl group, o, p, q are each independently an integer of 0-4, k, j represents a composition, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, n is It represents the number of repeating units and is an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula (I) or (II).

In general formula (I), R ₁₀₁ and R ₁₀₂ each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, —O—, —S—, —SO—, —SO ₂ —. , —CO—, or —CO—O—Z—O—CO— (wherein Z represents an aliphatic divalent group). Here, R ₁₀₁ and R ₁₀₂ may be the same or different.

In general formula (II), a represents an integer of 1 to 20, b represents an integer of 1 to 2000, and R ₁₀₃ and R ₁₀₄ represent a substituted or unsubstituted alkyl group or aryl group. Here, R ₁₀₃ and R ₁₀₄ may be the same or different.

In formula (4), R ₇ and R ₈ represent a substituted or unsubstituted aryl group, and Ar ₁ , Ar ₂ , and Ar ₃ represent the same or different arylene groups. X, k, j, and n are the same as in the case of Expression (3).

In formula (5), R ₉ and R ₁₀ represent a substituted or unsubstituted aryl group, and Ar ₄ , Ar ₅ and Ar ₆ represent the same or different arylene groups. X, k, j, and n are the same as in the case of Expression (3).

In the formula (6), R ₁₁ and R ₁₂ are substituted or unsubstituted aryl groups, Ar ₇ , Ar ₈ and Ar ₉ are the same or different arylene groups, and p is an integer of 1 to 5. X, k, j, and n are the same as in the case of Expression (3).

In formula (7), R ₁₃ and R ₁₄ are substituted or unsubstituted aryl groups, Ar ₁₀ , Ar ₁₁ and Ar ₁₂ are the same or different arylene groups, X ₁ and X ₂ are substituted or unsubstituted ethylene groups, or A substituted or unsubstituted vinylene group is represented. X, k, j, and n are the same as in the case of Expression (3).

In the formula (8), R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ are substituted or unsubstituted aryl groups, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ and Ar ₁₆ are the same or different arylene groups, Y ₁ , Y ₂ , Y ₃ represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group, which may be the same or different. Also good. X, k, j, and n are the same as in the case of Expression (3).

In the formula (9), R ₁₉ and R ₂₀ represent a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ and Ar ₁₉ represent the same or different arylene groups. X, k, j, and n are the same as in the case of Expression (3).

In formula (10), R ₂₁ represents a substituted or unsubstituted aryl group, and Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , and Ar ₂₃ represent the same or different arylene groups. X, k, j, and n are the same as in the case of Expression (3).

In the formula (11), R ₂₂ , R ₂₃ , R ₂₄ and R ₂₅ are substituted or unsubstituted aryl groups, and Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ and Ar ₂₈ represent the same or different arylene groups. X, k, j, and n are the same as in the case of Expression (3).

In formula (12), R ₂₆ and R ₂₇ represent a substituted or unsubstituted aryl group, and Ar ₂₉ , Ar ₃₀ and Ar ₃₁ represent the same or different arylene groups. X, k, j, and n are the same as in the case of Expression (3).

  These polymer charge transport materials may be used alone, or two or more kinds of polymer charge transport materials may be used in combination.

  Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, Examples thereof include thermoplastic or thermosetting resins such as phenol resins and alkyd resins. In addition, as a binder resin, a polymeric charge transport material having a charge transport function, for example, polycarbonate, polyester, polyurethane, polyether, and polyamine having an arylamine skeleton, a benzidine skeleton, a hydrazone skeleton, a carbazole skeleton, a stilbene skeleton, a pyrazoline skeleton, or the like. Polymer materials such as siloxane and acrylic resins, polymer materials having a polysilane skeleton, and the like can be used and are useful.

  The amount of the charge transport material is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. However, when a polymer charge transport material is used, it may be used alone or in combination with a binder resin.

<Film forming method>
Since most of the constituent components of the charge transport layer are solid at normal temperature and pressure, a solvent having a high affinity with each constituent component is used in preparing the coating liquid. The solvent used here is not particularly limited as long as it is usually used. For example, alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran, dioxane and propyl ether, dichloromethane And halogen series such as dichloroethane, trichloroethane and chlorobenzene, aromatic series such as benzene, toluene and xylene, and cellosolv series such as methyl cellosolve, ethyl cellosolve and cellosolve acetate. These solvents may be used alone or in combination of two or more.

  The coating method used for forming the charge transport layer is not particularly limited as long as it is a commonly used coating method, and is appropriately applied depending on the viscosity of the coating liquid, the desired thickness of the charge transport layer, and the like. Choose a method. Examples include dip coating, spray coating, bead coating, ring coating, and the like.

  If necessary, a plasticizer and a leveling agent can be added. As the plasticizer used for the charge transport layer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 0 to 100 parts by weight of the binder resin. About 30 parts by weight is appropriate. Examples of leveling agents that can be used in the charge transport layer include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. About 0 to 1 part by weight is appropriate for the part by weight.

  The thickness of the charge transport layer is preferably 40 μm or less, more preferably 30 μm or less, from the viewpoint of resolution and responsiveness. Regarding the lower limit, although it differs depending on the system to be used (particularly the charging potential), it is preferably 5 μm or more.

  The charge transport layer formed by the above-described method needs to be heated by some means from the viewpoint of electrophotographic characteristics and film viscosity to remove the solvent as described above from the film. As thermal energy, gas such as air and nitrogen, steam, various heat media, infrared rays, and electromagnetic waves can be used, and heating is performed from the coated surface side or the conductive support side. The heating temperature is preferably 100 ° C. or higher and 170 ° C. or lower. When the temperature is lower than 100 ° C., it is confirmed that the organic solvent in the film cannot be sufficiently removed, and the electrophotographic characteristics are deteriorated and the wear durability is reduced. On the other hand, when the treatment is performed at a temperature higher than 170 ° C., a skin-like defect or crack may occur on the surface, or peeling may occur at the interface with the adjacent layer. Further, when the volatile component in the photosensitive layer is sprayed to the outside, it is not preferable because desired electrical characteristics may not be obtained.

<Photosensitive layer (single-layer type photosensitive layer)>
A photosensitive layer having a single-layer structure is a layer having a charge generation function and a charge transport function at the same time. The single-layer type photosensitive layer can be formed by dissolving or dispersing a charge generating substance, a charge transporting substance, and a binder resin in an appropriate solvent, and applying and drying them. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.

  As the binder resin, in addition to the binder resin previously mentioned in the charge transport layer, the binder resin mentioned in the charge generation layer may be mixed and used. Of course, the polymer charge transport materials mentioned above can also be used favorably. The amount of the charge generating material with respect to 100 parts by weight of the binder resin is preferably 5 to 40 parts by weight, and the amount of the charge transporting material is preferably 0 to 190 parts by weight, and more preferably 50 to 150 parts by weight. The photosensitive layer is formed by dip coating, spray coating, bead coating, ring coating with a charge generating material, a binder resin and a charge transport material dispersed in a disperser using a solvent such as tetrahydrofuran, dioxane, dichloroethane, and cyclohexane. It can be formed by coating with a coat. The film thickness of the photosensitive layer is suitably about 5 to 25 μm.

<Other layers>
The electrophotographic photoreceptor according to the present invention may be provided with a layer other than the surface layer, photosensitive layer, charge generation layer, charge transport layer, and intermediate layer described above, for example, an undercoat layer, a light shielding layer, and the like. These may be provided.
<Additive materials>
Furthermore, in the present invention, for the purpose of improving the environmental resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, a surface layer, a photosensitive layer, a charge generation layer, a charge transport layer, an undercoat layer, an intermediate layer, An antioxidant can be added to each layer such as a light shielding layer.
The following are mentioned as antioxidant which can be used for this invention.

<Phenolic compound>
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 4, 4'-thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4 -Hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [meth -3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) butyl Rick acid] cricol ester, tocopherols and the like.

<Paraphenylenediamines>
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.

<Hydroquinones>
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone and the like.

<Organic sulfur compounds>
Dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate and the like.

<Organic phosphorus compounds>
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.

  These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained.

  In the present invention, the addition amount when using the antioxidant is preferably 0.01 to 10% by weight based on the total weight of the layer to be added.

<Conductive support>
Examples of the conductive support include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, and platinum, tin oxide, and indium oxide. After metal oxide is deposited or sputtered, film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. Pipes that have been subjected to surface treatment such as cutting, super-finishing, and polishing can be used. Further, endless nickel belts and endless stainless steel belts disclosed in JP-A-52-36016 can also be used as the conductive support.

  In addition, the conductive support dispersed in an appropriate binder resin on the support can be used as the conductive support in the present invention. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, silver, and metal oxide powder such as conductive tin oxide and ITO. Is mentioned. The binder resin used at the same time includes polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine Examples thereof include thermoplastic resins such as resins, urethane resins, phenol resins, and alkyd resins, thermally crosslinkable resins, and photocrosslinkable resins. Such a conductive layer can be provided by dispersing and applying these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  Further, a heat shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, polytetrafluoroethylene-based fluororesin on a suitable cylindrical substrate. Those provided with a conductive layer can be favorably used as the conductive support in the present invention.

  Incidentally, as will be described later, a laser having high coherence may be used for forming a latent image in an electrophotographic process. As described above, the conductive support is often made of a metal material, and many of them are considered to have high surface reflectance. When an electrophotographic photosensitive member is produced by applying the amorphous oxide on the conductive support, interference occurs between the writing light and the reflected light from the conductive support, resulting in image defects (moire). There are concerns about the occurrence. For this reason, when the reflectivity of the conductive support is high, it is preferable to make the surface of the conductive support uneven to reduce the reflectivity. Further, projections or the like that are potentially present on the raw tube may cause image defects when the photosensitive layer is laminated. By roughening this to an appropriate surface roughness, a smooth conductive support surface free from protrusions can be provided.

  As the surface irregularities, arithmetic ten-point average surface roughness (Rz) measured by the method described in JIS B0601-1982 was used as a representative characteristic value. As a measuring method, Surfcom 1400D (manufactured by Tokyo Seimitsu) was used, and the surface roughness Rz was measured with respect to an evaluation length of 2.5 mm and a reference length of 0.5 mm. The measurement points were 80 mm from both ends of the drum in the axial direction, three points in the center of the drum, and four ways of 90 degrees in the circumferential direction. The Rz value is preferably 0.6 μm or more. If Rz is smaller than this, moire due to writing light is likely to occur, which is not preferable. Further, even if Rz is large, there is no significant problem in use. However, if Rz is too large, it is difficult to form the intermediate layer uniformly, so care must be taken. From this viewpoint, the Rz of the conductive support is preferably 3.0 μm or less.

  Examples of the roughening method include honing and centerless polishing. Honing is preferably used because it is inexpensive and easy to adjust the surface roughness. There are dry and wet processing methods for honing, but either method may be used. Wet (liquid) honing is a method in which a powdery abrasive (abrasive grain) is suspended in a liquid such as water and then sprayed onto the surface of the conductive support at high speed to roughen the surface. Can be controlled by spraying pressure, speed, amount of abrasive, type, shape, size, hardness, specific gravity or suspension concentration. Similarly, the dry honing process is a method in which an abrasive is sprayed onto the surface of the conductive support at high speed with air, and the surface roughness can be controlled in the same manner as the wet honing process. Examples of the abrasive used in the wet or dry honing process include particles such as silicon carbide, alumina, zirconia, stainless steel, iron, glass beads, and plastic shots.

  However, in liquid honing using dry sand blasting or amorphous alumina abrasive grains, the abrasive grains may pierce the surface of the conductive support, and when producing an electrophotographic photosensitive member, black spots on a white image in a reversal development system, It may appear as a white spot on a black image in the forward developing system. In liquid honing using glass beads, there is a problem that the glass breaks immediately and pierces the surface of the conductive support, and that it is difficult to control the roughness. Therefore, after roughening the conductive support by liquid honing using spherical alumina abrasive grains or stainless abrasive grains as an abrasive, an undercoat layer and a photosensitive layer are formed, and an electrophotographic photoreceptor is obtained. It is common to produce. In addition, in the roughening treatment of the conductive support, from the viewpoint of the processing time, the amount of abrasive grains used, the amount of energy used, and the convenience of removing residual abrasive grains in the conductive support after roughening, It is desirable to make the processing conditions as mild as possible within a range satisfying the interference fringe prevention function and to keep Rz small.

[Image forming apparatus, process cartridge for image forming apparatus]
The image forming apparatus according to the present invention forms the electrostatic latent image on the surface of the electrophotographic photoreceptor charged by the charging means, the charging means for charging the electrophotographic photoreceptor, and the charging means. A latent image forming unit; a developing unit that forms a visible image by attaching toner to an image portion of the electrostatic latent image formed by the latent image forming unit; and the developed image formed by the developing unit. Transfer means for transferring to a transfer body.
Next, the image forming apparatus and the process cartridge for the image forming apparatus of the present invention will be described in detail with reference to the drawings.

The image forming apparatus of the present invention uses the electrophotographic photosensitive member. For example, the toner image on the image holding member (transfer paper) after at least charging, image exposure, and development of the photosensitive member. Transfer, fixing and cleaning of the photoreceptor surface.
In some cases, an image forming apparatus that directly transfers an electrostatic latent image to a transfer member and develops it does not necessarily have the above-described process arranged on a photosensitive member.

  FIG. 4 is a schematic diagram illustrating an example of an image forming apparatus. A charging charger (3) is used as means (charging means) for charging the electrophotographic photosensitive member (1) on average. As the charging means, a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, a conductive brush device, or the like is used, and a known system can be used.

  Next, in order to form an electrostatic latent image on the uniformly charged photoreceptor (1), an image exposure unit (5) which is a latent image forming unit is used. As the light source, all luminescent materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL) can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

  Next, in order to visualize the electrostatic latent image formed on the photoreceptor (1), a developing unit (6) which is a developing unit is used. Development methods include a one-component development method using a dry toner, a two-component development method, and a wet development method using a wet toner. When the photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.

  Next, a transfer charger (10) is used to transfer the toner image visualized on the photosensitive member onto a transfer member (9) as transfer means. In addition, a pre-transfer charger (7) may be used for better transfer. As these transfer means, a transfer charger, an electrostatic transfer method using a bias roller, a mechanical transfer method such as an adhesive transfer method and a pressure transfer method, and a magnetic transfer method can be used. As the electrostatic transfer method, the charging means can be used. The transfer body (9) is transported to the transfer section by a pair of transport rollers (8) which are part of the transport means.

  Next, a separation charger (11) and a separation claw (12) are used as means for separating the transfer body (9) from the photoreceptor (1). As other separation means, electrostatic adsorption induction separation, side end belt separation, tip grip conveyance, curvature separation, and the like are used. As the separation charger (11), the charging means can be used.

  Next, a fur brush (14) and a cleaning blade (15) are used to clean the toner remaining on the photoreceptor after transfer. Further, a pre-cleaning charger (13) may be used in order to perform cleaning more efficiently. Other cleaning means include a web method, a magnet brush method, and the like, but each may be used alone or in combination.

  Next, a neutralizing unit is used for the purpose of removing the latent image on the photoreceptor as required. As the charge removal means, a charge removal lamp (2) and a charge removal charger are used, and the exposure light source and the charging means can be used respectively.

  In addition, known processes can be used for reading, feeding, fixing, paper discharge and the like that are not close to the photoconductor.

  The present invention is an image forming method and an image forming apparatus using the electrophotographic photoreceptor according to the present invention for such image forming means.

The image forming means may be fixedly incorporated in a copying apparatus, facsimile, or printer, but may be incorporated in these apparatuses in the form of a process cartridge and detachable.
That is, the process cartridge for an image forming apparatus according to the present invention includes the electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, and an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging unit. One or more means selected from a latent image forming means for forming an image, and a developing means for forming a visible image by attaching toner to the image portion of the electrostatic latent image formed by the latent image forming means; And is detachable from the image forming apparatus.
In addition, the image forming apparatus according to the present invention may be configured such that the process cartridge for the image forming apparatus is detachable.

FIG. 5 is a schematic view showing an example of the configuration of a process cartridge for an image forming apparatus according to the present invention.
The process cartridge for an image forming apparatus includes an electrophotographic photosensitive member (101), and at least one of a charging unit (102), a developing unit (104), a transfer unit (106), and an exposure unit (103). In addition, the image forming apparatus main body may further include a cleaning unit (107) and a charge eliminating unit (not shown), and is an apparatus (part) that is detachable from the image forming apparatus main body.

  Referring to the image forming process by the apparatus illustrated in FIG. 5, the surface of the photoreceptor (101) is exposed by charging by the charging means (102) and exposure by the exposure means (103) while rotating in the direction of the arrow. An electrostatic latent image corresponding to the image is formed, and the electrostatic latent image is developed with toner by the developing means (104). The toner development is transferred to the transfer body (105) by the transfer means (106), and printed. Be out. Next, the surface of the photoconductor after the image transfer is cleaned by a cleaning unit (107), and further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

The following examples illustrate the present invention in more detail. However, of the following examples, Examples 4 to 6, 11, and 13 are test examples as reference examples that do not belong to the scope of the present invention.
<Example 1>
<Method for producing electrophotographic photosensitive member>
An aluminum cylinder with a surface roughness Rz of 0.9 μm, a diameter of 30 mm, and a length of 360 mm was prepared as a conductive support, and an intermediate layer was formed using an improved RF sputtering system so that film formation was possible while rotating the cylinder. did. As described above, a cooling jacket is provided inside the cylinder to prevent overheating of the substrate temperature during sputtering. In addition, using a 150 mm × 400 mm target made of a polycrystalline sintered body containing indium, zinc and gallium, an amorphous oxide film made of indium, zinc and gallium (hereinafter In-Ga-ZnOX) is used as an intermediate layer. Formed. The intermediate layer deposition conditions were as follows.

[Interlayer deposition conditions]
-Conductive support cooling temperature: 30 ° C
Output: 11.2 W / cm ²
・ Target-substrate distance: 50mm
・ Back pressure: 5.0 × 10 ⁻⁶ torr or less ・ Film forming pressure: 3.0 × 10 ⁻³ torr
・ Inert gas: Argon ・ Oxygen partial pressure: 2 vol% with respect to the total flow rate of inert gas and oxygen gas

According to the intermediate layer deposition conditions, 0.5 μm In—Ga—ZnO _X was formed as an intermediate layer. The film thickness was measured with an ellipsometer.

  Next, a 0.3 μm charge generation layer and a 20 μm charge transport layer are formed by sequentially applying and drying a charge generation layer coating solution and a charge transport layer coating solution having the following composition to provide a conductive support. An electrophotographic photosensitive member comprising a body / intermediate layer / charge generation layer / charge transport layer was obtained.

[Coating liquid composition for charge generation layer]
-8 parts of titanyl phthalocyanine having the X-ray diffraction pattern of FIG. 6 (average particle size 0.31 μm)
・ Polyvinyl butyral (XYHL, manufactured by UCC) 5 parts ・ Methyl ethyl ketone 80 parts

[Coating liquid composition for charge transport layer]
・ 10 parts of bisphenol Z polycarbonate (Panlite TS-2050, manufactured by Teijin Chemicals)
・ Low molecular charge transport material of the following structural formula (1) 7 parts ・ Tetrahydrofuran 100 parts ・ Tetrahydrofuran solution of 1% silicone oil 1 part (KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.)

<Example 2>
Among the film forming conditions of the intermediate layer of Example 1, except that the intermediate layer was formed by changing the oxygen partial pressure to 1 vol% with respect to the total flow rate of the inert gas and oxygen gas, Similarly, an electrophotographic photosensitive member was produced.

<Example 3>
Example 1 except that the intermediate layer was formed by changing the oxygen partial pressure to 0.5 vol% with respect to the total flow rate of the inert gas and oxygen gas among the film forming conditions of the intermediate layer of Example 1. In the same manner as above, an electrophotographic photosensitive member was produced.

<Examples 4 to 6>
An electrophotographic photosensitive member was produced in the same manner as in Examples 1 to 3, except that the charge generation layer coating solution composition used in Examples 1 to 3 was changed to the following composition.

[Coating liquid composition for charge generation layer]
・ Bisazo pigment of the following structural formula (2) 2.5 parts ・ Polyvinyl butyral (XYHL, manufactured by UCC) 0.5 part ・ Cyclohexanone 200 parts ・ Methyl ethyl ketone 80 parts

<Examples 7 to 9>
Electrophotographic photosensitive members were produced in the same manner as in Examples 1 to 3, except that the charge transport layer coating solution composition used in Examples 1 to 3 was changed to the following composition.

[Coating liquid composition for charge transport layer]
-10 parts of polymer charge transport material of the following structural formula (3) (Molecular weight Mw 130000)
Tetrahydrofuran 100 parts 1% silicone oil tetrahydrofuran solution 1 part
(KF50-100CS, manufactured by Shin-Etsu Chemical)

<Examples 10 to 11>
On the electrophotographic photosensitive member comprising the conductive support / intermediate layer / charge generation layer / charge transport layer obtained in Examples 2 and 5, a surface layer coating solution having the following composition was sprayed to 5 μm. Then, an electrophotographic photosensitive member comprising a conductive support / intermediate layer / charge generation layer / charge transport layer / surface layer was obtained by drying at 150 ° C. for 30 minutes.

[Coating liquid composition for surface layer]
-Bisphenol Z polycarbonate 4 parts (Panlite TS-2050, manufactured by Teijin Chemicals Ltd.)
・ 3 parts of low molecular charge transport material of the above structural formula (2) ・ 3 parts of alumina fine particles (AA03, manufactured by Sumitomo Chemical Co., Ltd.)
・ 170 parts of tetrahydrofuran ・ 50 parts of cyclohexanone

<Examples 12 to 13>
On the electrophotographic photosensitive member comprising the conductive support / intermediate layer / charge generation layer / charge transport layer obtained in Examples 2 and 5, a surface layer coating solution having the following composition was sprayed to 5 μm. Then, using a metal halide lamp, the surface layer is crosslinked by light irradiation under the conditions of illuminance: 900 mW / cm ² and irradiation time: 20 seconds, and drying at 130 ° C. for 30 minutes. As a result, an electrophotographic photosensitive member comprising a conductive support / intermediate layer / charge generation layer / charge transport layer / surface layer was obtained.

[Coating liquid composition for surface layer]
-95 parts by weight of radically polymerizable monomer of the following structural formula (4)
Trimethylolpropane triacrylate
(TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
・ 95 parts by weight of a radically polymerizable compound having a charge transporting structure represented by the following structural formula (5) • 10 parts by weight of a photopolymerization initiator
1-hydroxy-cyclohexyl-phenyl-ketone
(Irgacure I-184, Ciba Specialty Chemicals)
・ 1200 parts by weight of tetrahydrofuran

<Example 14>
Example 2 is the same as Example 2 except that the film thickness of the intermediate layer of Example 2 is 0.05 μm (the film is formed under the film forming conditions of Example 2 and the film forming time is set to 1/10 of Example 2). Similarly, an electrophotographic photosensitive member was produced.

<Example 15>
Example 2 is the same as Example 2 except that the film thickness of the intermediate layer of Example 2 is 0.15 μm (the film is formed under the film forming conditions of Example 2 and the film formation time is set to 3/10 of Example 2). Similarly, an electrophotographic photosensitive member was produced.

<Example 16>
Example 2 is the same as Example 2 except that the film thickness of the intermediate layer of Example 2 is 0.8 μm (produced under the film-forming conditions of Example 2 and made only the film-forming time 1.6 times that of Example 2). Similarly, an electrophotographic photosensitive member was produced.

<Example 17>
Example 2 was the same as Example 2 except that the film thickness of the intermediate layer in Example 2 was 1.0 μm (the film was formed under the conditions for film formation in Example 2 and only the film formation time was twice that of Example 2). Thus, an electrophotographic photosensitive member was produced.

<Example 18>
An electrophotographic photosensitive member was produced in the same manner as in Example 2 except that the surface roughness Rz of the conductive support of Example 2 was 0.2 μm.

<Example 19>
Of the intermediate layer preparation method of Example 1, an electrophotographic photosensitive member was prepared in the same manner as in Example 2 except that the composition ratio of the polycrystalline sintered body containing indium, zinc and gallium was as follows. .
In: Ga: Zn = 1: 1.5: 1

<Example 20>
Of the intermediate layer preparation method of Example 1, an electrophotographic photosensitive member was prepared in the same manner as in Example 2 except that the composition ratio of the polycrystalline sintered body containing indium, zinc and gallium was as follows. .
In: Ga: Zn = 1: 0.75: 1

<Example 21>
Of the intermediate layer manufacturing method of Example 1, a polycrystalline sintered body containing indium and gallium (composition ratio In: Ga = 1: 1) is used as a target, and the oxygen partial pressure is the sum of inert gas and oxygen gas. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the flow rate was changed to 1.5 vol%.

<Example 22>
Of the intermediate layer manufacturing method of Example 1, a polycrystalline sintered body (composition ratio In: Zn = 1: 1) containing indium and zinc is used as a target, and the oxygen partial pressure is the sum of inert gas and oxygen gas. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the flow rate was changed to 1.5 vol%.

<Comparative Examples 1-3>
The coating solution for charge generation layer used in Examples 1, 4 and 7 was applied to an aluminum cylinder having a surface roughness Rz of 0.9 μm, a diameter of 30 mm and a length of 360 mm used in Examples 1, 4 and 7. An electrophotographic photosensitive member comprising a conductive support / charge transport layer / charge generation layer formed by sequentially applying and drying a transport layer coating solution to form a 0.3 μm charge generation layer and a 20 μm charge transport layer. Got.

<Comparative Examples 4-6>
For an aluminum cylinder having a surface roughness Rz of 0.9 μm, a diameter of 30 mm, and a length of 360 mm used in Examples 1, 4 and 7, the intermediate layer coating liquid having the following composition and Examples 1, 4 and 7 were used. The coating solution for the charge generation layer and the coating solution for the charge transport layer were sequentially applied and dried to form a 3.5 μm intermediate layer, a 0.3 μm charge generation layer, and a 20 μm charge transport layer. An electrophotographic photosensitive member comprising a conductive support / intermediate layer / charge transport layer / charge generation layer was obtained.

[Coating liquid composition for intermediate layer]
・ Alkyd resin 6 parts (Beccosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink and Chemicals)
・ Titanium oxide 40 parts ・ Methyl ethyl ketone 50 parts

<Comparative Example 7>
Example 1 except that the intermediate layer was formed by changing the oxygen partial pressure to 2.5 vol% with respect to the total flow rate of the inert gas and oxygen gas among the film forming conditions of the intermediate layer of Example 1. In the same manner as above, an electrophotographic photosensitive member was produced.

<Comparative Example 8>
Example 1 except that the intermediate layer was formed by changing the oxygen partial pressure to 3.0 vol% with respect to the total flow rate of the inert gas and oxygen gas among the film forming conditions of the intermediate layer of Example 1. In the same manner as above, an electrophotographic photosensitive member was produced.

<Comparative Example 9>
Example 1 except that the intermediate layer was formed by changing the oxygen partial pressure to 5.0 vol% with respect to the total flow rate of the inert gas and the oxygen gas among the film forming conditions of the intermediate layer of Example 1. In the same manner as above, an electrophotographic photosensitive member was produced.

<Comparative Example 10>
Example 1 except that the intermediate layer was formed by changing the oxygen partial pressure to 7.0 vol% with respect to the total flow rate of the inert gas and oxygen gas among the film forming conditions of the intermediate layer of Example 1. In the same manner as above, an electrophotographic photosensitive member was produced.

<Comparative Examples 11-14>
Implementation was performed except that the intermediate layer was formed by changing the oxygen partial pressure to 3.0 vol% with respect to the total flow rate of the inert gas and oxygen gas among the film forming conditions of Examples 19 to 22 An electrophotographic photosensitive member was produced in the same manner as in Examples 19-22.

<Comparative Example 15>
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the intermediate layer of Example 1 was tin oxide prepared using the modified RF sputtering apparatus described in Example 1 under the following intermediate layer deposition conditions. Produced.

[Interlayer deposition conditions]
・ Target: Polycrystalline sintered body made of tin oxide ・ Conductive support cooling temperature: 30 ° C.
RF power: 11.2 W / cm ²
・ Target-substrate distance: 50mm
・ Back pressure: 5.0 × 10 ⁻⁶ torr or less ・ Film forming pressure: 3.0 × 10 ⁻³ torr
-Inert gas: Argon-Oxygen partial pressure: 5 vol% with respect to the total amount of inert gas and oxygen gas

<Comparative Example 16>
Comparative Example 15 except that the intermediate layer was formed by changing the oxygen partial pressure to 3.0 vol% with respect to the total flow rate of the inert gas and oxygen gas among the film forming conditions of the intermediate layer of Comparative Example 15 In the same manner as above, an electrophotographic photosensitive member was produced.

  Composition analysis, surface resistivity, and structural analysis were performed on the intermediate layers used in Examples 1-22 and Comparative Examples 1-16.

<< Structural analysis of amorphous oxide >>
It was evaluated by crystal structure analysis by X-ray diffraction that the intermediate layer produced in the example was an amorphous oxide.

[X-ray diffraction evaluation method]
Evaluation device: X-ray diffractometer X 'Part Pro (manufactured by Philips)
-X-ray generation source: Cu (encapsulated tube)
-Filter: None-Scan axis: 2θ / θ
-Measurement angle range: 10 ° -100 °

The measurement result of the intermediate layer produced in Example 1 is shown in FIG.
As is clear from this result, the intermediate layer produced by the method shown in Example 1 was an amorphous oxide. Similarly, other Examples 2 to 22 and Comparative Examples 1 to 14 were confirmed to be amorphous oxides. On the other hand, as a result of carrying out the same evaluation with respect to tin oxide known as a crystalline oxide, all of those produced in Comparative Examples 15 to 16 were crystalline oxides.

<Amorphous oxide composition>
Among the intermediate layers produced in the present examples and comparative examples, the composition ratios of the multi-component oxides (Examples 1 to 22 and Comparative Examples 1 to 14) were evaluated using fluorescent X-ray analysis. Moreover, regarding the amorphous oxides created by the film forming methods of Examples 1 to 18 and Comparative Examples 7 to 10, the composition profile in the depth direction of the amorphous oxide was evaluated using Auger electron spectroscopy.

[Fluorescence X-ray method evaluation method]
・ Measurement device: Wavelength dispersive X-ray fluorescence analyzer RIX3000 (manufactured by Rigaku Corporation)
・ X-ray tube: Rh
・ Output: 50kV
・ Current: 50 mA

  From the evaluation by the fluorescent X-ray method in the above evaluation method, the amorphous oxide obtained in this example was an amorphous oxide having the following composition ratio.

(Composition ratio)
Examples 1 to 18: In: Zn: Ga = 100: 112: 117
Example 19: In: Zn: Ga = 100: 108: 137
Example 20: In: Zn: Ga = 100: 110: 105
Example 21: In: Ga = 100: 125
Example 22: In: Zn = 100: 111

[Auger electron spectroscopy evaluation method]
・ Measuring device: FE-SAM680 (manufactured by Phi)
・ Acceleration voltage: 10 kV
-Amount of current: 10 nA
Sputter etching conditions: Ar ion / acceleration voltage 1 kV

The measurement result of the measurement by Auger electron spectroscopy in the above evaluation method is shown in FIG.
From these results, the constituent elements (indium, zinc, gallium, oxygen) had almost no variation in the depth direction, and were extremely homogeneous amorphous oxides.

<< Surface resistivity of amorphous oxide >>
The surface resistivity of the intermediate layer produced in Examples / Comparative Examples was measured by the method described below.
The substrate was replaced with a non-alkali glass (Corning # 1737) in place of the conductive support, and film formation was carried out under other conditions in accordance with the respective examples and comparative examples, and the obtained intermediate layer was subjected to measurement. When measuring the surface resistivity, a 25 μm gap, 10 mm long Au electrode was formed on an amorphous oxide formed on an alkali-free glass by vapor deposition, and the passing current of the intermediate layer when a bias was applied between the electrodes was measured. The measurement was performed. This surface resistivity measurement was carried out 10 times at different locations, and the average value was calculated. The surface resistivity of the intermediate layer used in each example and comparative example is shown in Table 1 below.

Next, the following tests were carried out using the electrophotographic photoreceptors of Examples 1 to 22 and Comparative Examples 1 to 16.
<< Evaluation of electrostatic characteristics and image after electrostatic fatigue >>
A unit in which a member (cleaning blade or the like) excluding the charging unit was removed from the Ricoh Imagio Neo 271 photoreceptor unit was used in the running test. The modified photoconductor unit to which the photoconductors produced in Examples and Comparative Examples were attached was set in an Imagio Neo 271 remodeling machine so that only charging and development could be repeatedly performed without passing paper. As charging conditions, a charging roller is used, an alternating voltage obtained by superimposing an AC voltage on a DC voltage is applied, a peak-to-peak voltage Vpp of the AC voltage is about 1.9 [kV], and a frequency f is about 900 [Hz]. The DC voltage was set to -800 [V], and the rotational speed of the electrophotographic photosensitive member was set to 125 mm / sec. As development conditions, for Examples 1 to 3, 7 to 10, 12, 14 to 22 and Comparative Examples 1, 3 to 4, 6 to 16 using a phthalocyanine pigment as a charge generation material, an LD of 780 nm was used, For other examples and comparative examples using disazo pigments as the generating material, LD of 655 nm was used. The writing pattern was 100% writing pattern (all solid). Under this condition, an electrostatic fatigue equivalent to 100,000 sheets of running (5% test pattern / charge-exposure potential difference 750 V / electrophotographic photoreceptor electrostatic capacity 110 pF / cm ² y) To charge, the passing charge calculation shows that it can be achieved by running for about 2 hours. In this evaluation, an electrostatic fatigue test equivalent to 100,000 runnings was performed using the above-described modified machine, and image evaluation was performed using the following evaluation machine.

  For image evaluation, as in the electrostatic fatigue test, Examples 1 to 3, 7 to 10, 12, 14 to 22 and Comparative Examples 1, 3 to 4, 6 to 16 using a phthalocyanine pigment as a charge generation material. For example, an IPSiO Color CX9000 remodeling machine manufactured by Ricoh with a 780 nm LD was used. For other examples and comparative examples using a disazo pigment as a charge generation material, an IPSiO Color CX9000 remodeling machine with a 655 nm LD was used. In any of the apparatuses, the setting was changed so as to eliminate the initial idling process during image output. Imagio toner type 27 was used as the toner, and MyPaper (A4 size) manufactured by NBS Ricoh was used as the paper. The photoreceptor surface potential at the start was −800 V, and the in-machine potential (dark part potential and exposed part potential) before and after the electrostatic fatigue was evaluated. As a method for determining the in-machine potential, five 100% written images are output continuously, the photosensitive member surface potential immediately before writing the fifth image is set as the dark portion potential, and the potential at the time of writing the fifth image is exposed. The partial potential was used. In order to confirm the effect of improving the chargeability of the electrophotographic photosensitive member after long-term use, which is also the object of the present invention, the photosensitive member surface potential immediately before writing the first image and the immediately preceding second image writing. The surface potential of the photoreceptor was measured, and the difference in charging potential was calculated. As an output image, 5 sheets of white background output and halftone output were continuously performed, and image evaluation was performed by confirming the occurrence of background contamination and density unevenness. The measurement results of the in-machine potential are shown in Tables 2 and 3, and the image evaluation results are also shown in Table 2.

From the results shown in Table 2, the electrophotographic photoreceptors obtained in the examples are significantly different in both the chargeability and light attenuation before and after the electrostatic fatigue test in the electrophotographic photoreceptors obtained in the comparative examples. Was not seen. In particular, it can be seen that the stability of the example using a phthalocyanine-based material as the charge generation material is relatively high. On the other hand, in Comparative Examples 1 to 3 having no intermediate layer, a large difference in the exposed portion potential is not observed, but a decrease in the dark portion potential is greatly observed, and it can be seen that the durability against electrostatic fatigue is poor. As for Comparative Examples 4 to 6 having a particle-dispersed intermediate layer, both the decrease in the dark portion potential and the increase in the exposure portion potential due to electrostatic fatigue were clearly observed. The electrophotographic photoreceptors of Examples 1 to 22 of the present invention. It was found that the electrostatic stability was poor compared to. Even when an amorphous oxide is used, when the surface resistance is larger than 1.0 × 10 5 W / cm ² (Comparative Examples 7 to 14), the examples and It can be seen that the electrostatic stability is poor. In particular, with respect to Comparative Example 10 in which the surface resistance of the amorphous oxide is 1.6 × 10 9 W / cm ² , the dark layer potential and the exposed portion potential after electrostatic fatigue are not provided with the intermediate layers of Comparative Examples 1 to 6 or This is a significant change compared to the case where a conventional intermediate layer is provided, and this proves that the surface resistance adjustment is important when an amorphous oxide is used as the intermediate layer. When tin oxide, which is a crystalline oxide, is used as the intermediate layer, the charging stability is poor from the initial stage of use, and the charging potential falls below 100 V after several sheets of output. Abandoned the implementation.

  Regarding the image, the electrophotographic photosensitive member obtained in the example may cause slight scumming after electrostatic fatigue when a disazo material is used as a charge generation material. However, a phthalocyanine material is used. If it was, good images were output before and after electrostatic fatigue. On the other hand, with respect to Comparative Examples 1 to 3, a large number of ground stains were generated after electrostatic fatigue with respect to Comparative Examples 4 to 6, and this result also revealed that the electrostatic stability was poor. On the other hand, even in an electrophotographic photoreceptor using an amorphous oxide, if the surface resistance of the amorphous oxide is large, the occurrence of scumming is confirmed in several output images after electrostatic fatigue. Although the electrostatic stability was higher than those of Comparative Examples 1 to 6, it was revealed that the stability as in Examples was not obtained.

  Next, from the results of the chargeability evaluation shown in Table 3, all the photoconductors obtained in the examples were able to acquire a sufficient charging potential from the first sheet after electrostatic fatigue. It can be seen that there is almost no difference between the dark part potential at the time of output and the dark part potential at the time of outputting the second sheet. On the other hand, it can be seen that all of the electrophotographic photoreceptors of Comparative Examples 1 to 14 have a large difference between the dark part potential when the first sheet is output and the dark part potential when the second sheet is output. In particular, when an amorphous oxide having a large surface resistance is used, it can be seen that the dark potential difference depends on the surface resistance.

Furthermore, the relationship between the intermediate layer surface resistivity of Examples 1-22 and Comparative Examples 7-14 and the dark part potential difference after electrostatic fatigue is shown in FIG. As is apparent from FIG. 9, the difference between the first sheet dark portion potential and the second sheet dark portion potential is small in the example using the low surface resistivity intermediate layer, whereas the comparative example is the intermediate layer. It is apparent that the potential difference increases as the surface resistivity increases. A linear approximation curve (illustrated) was obtained from the results of the comparative example, and the X-intercept of the straight line (that is, the surface resistivity of the intermediate layer for setting the potential difference to 0) was calculated to be 1.03 × 10 ⁵ Ω / cm. since there was a ^2, a case of using the amorphous oxide as an intermediate layer, in order to obtain an electrophotographic photoreceptor having a high electrostatic stability, surface resistivity of the intermediate layer is 1. It can be estimated that it is necessary to be 0 × 10 ⁵ Ω / cm ² or less.

  From the above results, the electrophotographic photosensitive member shown in the present example has a small characteristic variation even with respect to an electrostatic load, and the initial state of both charging property and light attenuation property is maintained for a long time. As a result, it was found that the electrophotographic photosensitive member has few defects relating to image quality.

1 is a schematic view illustrating an example of a configuration in which a photosensitive layer as an embodiment of an electrophotographic photoreceptor according to the present invention is a single layer type. FIG. 6 is a schematic view showing an example of a configuration in which a photosensitive layer which is another embodiment of the electrophotographic photosensitive member according to the present invention is a laminated type. It is the schematic which shows the other example of the structure by which the photosensitive layer which is other embodiment of the electrophotographic photoreceptor which concerns on this invention is a lamination type. 1 is a schematic diagram illustrating an example of a configuration of an image forming apparatus according to the present invention. FIG. 2 is a schematic diagram illustrating an example of a configuration of a process cartridge for an image forming apparatus according to the present invention. It is a graph which shows the X-ray-diffraction pattern of the titanyl phthalocyanine used for the Example. 4 is a graph showing measurement results of X-ray diffraction of the intermediate layer produced in Example 1. It is a graph which shows the measurement result of the measurement by the Auger electron spectroscopy of the intermediate layer created in the Example. It is a graph which shows the relationship between the intermediate layer surface resistivity of Examples 1-22 and Comparative Examples 7-14 and the dark part electric potential difference after electrostatic fatigue.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Static elimination lamp 3 Charger charger 5 Image exposure part 6 Developing unit 7 Charger before transfer 8 Conveyance roller 9 Transfer object (recording medium)
DESCRIPTION OF SYMBOLS 10 Transfer charger 11 Separation charger 12 Separation claw 13 Charger before cleaning 14 Fur brush 15 Cleaning blade 31 Conductive support 32 Intermediate layer 33 Charge generation layer 34 Charge transport layer 36 (Single layer type or multilayer type) Photosensitive layer 101 Electrophotographic photosensitive member Body 102 Charging means 103 Exposure means 104 Developing means 105 Transfer object (recording medium)
106 Transfer means 107 Cleaning means

Claims (9)

A conductive support, an intermediate layer, and a photosensitive layer;
The intermediate layer includes an amorphous oxide,
The surface resistivity of the amorphous oxide is 1.0 × 10 ⁵ Ω / cm ² or less,
The photosensitive layer comprises a titanyl phthalocyanine pigment;
An electrophotographic photoreceptor, wherein the intermediate layer and the photosensitive layer are laminated in this order on the conductive support.   The electrophotographic photoreceptor according to claim 1, wherein the amorphous oxide contains indium, zinc, and gallium.   The electrophotographic photosensitive member according to claim 1, wherein the intermediate layer has a thickness of 0.1 μm to 0.9 μm.   4. The electrophotographic photoreceptor according to claim 1, wherein the conductive support has a surface roughness Rz of 0.6 μm or more. 5.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer includes a charge generation layer and a charge transport layer. A charging process for charging the electrophotographic photosensitive member, a latent image forming process for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging process, and the static image formed by the latent image forming process. In an image forming method in which a developing process for forming a visible image by attaching toner to an image portion of an electrostatic latent image and a transfer process for transferring the visible image formed by the developing process to a transfer target are repeated.
The image forming method according to claim 1, wherein the electrophotographic photoreceptor is the electrophotographic photoreceptor according to claim 1 . An electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, a latent image forming unit for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging unit, and the latent image formation Developing means for attaching a toner to the image portion of the electrostatic latent image formed by the means to form a visible image; and transferring means for transferring the visible image formed by the developing means to a transfer target. In the image forming apparatus provided,
The image forming apparatus according to claim 1, wherein the electrophotographic photoreceptor is the electrophotographic photoreceptor according to claim 1 . An electrophotographic photoreceptor;
Charging means for charging the electrophotographic photosensitive member, latent image forming means for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging means, and the latent image forming means formed by the latent image forming means One or more means selected from developing means for forming a visible image by attaching toner to the image portion of the electrostatic latent image,
In a process cartridge for an image forming apparatus that is detachable from the image forming apparatus,
The process cartridge for an image forming apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 5 . An image forming apparatus comprising the process cartridge for an image forming apparatus according to claim 8 detachably.

Images