JP2010181608A - Electrophotographic photoreceptor, image forming method using the same, image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having stable charging properties and durability to mechanical and electrostatic hazards, to provide an image forming method, an apparatus therefor and a process cartridge using the same. <P>SOLUTION: The electrophotographic photoreceptor includes: an intermediate layer composed of amorphous oxide including a plurality of metallic elements (e.g., the amorphous oxide including the following three elements: indium, zinc and gallium shown in Fig.4); an electron injecting layer; and a charge generating layer (e.g., a layer containing titanyl phthalocyanine as a charge generating material); and a hole transport layer, which are sequentially provided on a conductive support. The electrophotographic photoreceptor is used for constituting an image forming apparatus and a process cartridge, to form an image. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used for a copying machine, a laser printer, a normal facsimile, and the like, an image forming method using the same, an image forming apparatus, and a process cartridge for the image forming apparatus. Even if it is a case, an electrophotographic photosensitive member capable of suppressing a decrease in chargeability, background contamination, and charging failure without causing an increase in potential of an exposed portion, and an image forming method, an image forming apparatus, and an image using the same. The present invention relates to a process cartridge for a forming apparatus.

In recent years, from the viewpoints of saving office space, expanding business opportunities, etc., high speed, downsizing, colorization, high image quality, and easy maintenance are desired for electrophotographic apparatuses. These are regarded as problems to be solved by developing an electrophotographic photosensitive member because they are related to improvement in characteristics and durability of the electrophotographic photosensitive member. 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 an important issue to improve durability against various hazards that the electrophotographic photosensitive member receives from the image forming process. The hazards mentioned here can be broadly classified into two types: mechanical hazards and electrical hazards (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, 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 is worn. The demerit that it is easy is pointed out. For this reason, in an electrophotographic apparatus to which the present cleaning method is applied, wear of the electrophotographic photosensitive member is often a problem for extending the life, and a technique for 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, the intermediate layer, the charge generation layer, the charge transport layer, and the surface layer) of the electrophotographic photosensitive member. At present, the most widely used electrophotographic photoreceptors are composed of organic materials. In the current electrophotographic processes in which charging and discharging are repeated repeatedly, the electrophotographic photoreceptor is constituted. The organic material to be gradually deteriorated due to electrostatic hazards, resulting in the deterioration of electrophotographic characteristics such as the generation of charge traps in the layer and the 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 a discharge product generated in a charging process in an image forming process has an influence on a photoreceptor (see Patent Documents 6, 7, and 8). As a result, the chargeability of the electrophotographic photoreceptor is reduced. On the other hand, 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 method 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 cause of the decrease in chargeability. The intermediate layer that is widely used at present is in a form in which inorganic fine particles are dispersed in a binder made of an organic resin, and includes a “charge injection blocking function” from the conductive support to the photosensitive layer, and a photosensitive layer. It is preferable to have a “charge transport function” of the generated charges to the conductive support. For example, if the function of preventing charge injection from the conductive support to the photosensitive layer is insufficient, when the electrophotographic photosensitive member is charged, a charge having a polarity opposite to the charged polarity of the photosensitive member is transferred from the conductive support to the photosensitive layer. As a result, the charge on the surface of the photosensitive member is easily erased, so that a phenomenon that it is difficult to obtain a desired charge occurs. In addition, when the function of transporting the charge generated in the photosensitive layer to the conductive support is insufficient, the potential of the exposed portion is increased due to a decrease in charge generation efficiency, and charging failure due to charge trapping in the intermediate layer is likely to occur. Furthermore, when the photoconductor is used for a very long time, a phenomenon that the photoconductor becomes difficult to be charged is observed. This phenomenon is presumed to be caused by charge accumulation in the vicinity of the intermediate layer. be able to.

Various techniques for coexistence and maintenance of the two functions described above have been developed, but these functions are likely to have a reciprocal relationship, and it is very difficult to achieve both functions. For example, a technique for achieving an improvement in the function of preventing charge injection by applying a high insulating layer as a constituent layer of the intermediate layer is 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 function of charge transport from the charge generation material to the conductive support, which is another function to be performed by the intermediate layer, becomes insufficient, and charging failure due to an increase in the potential of the exposed area or charge accumulation in the vicinity of the intermediate layer, image Defects etc. are easily manifested.
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 this disclosed technology, the charge of the opposite polarity on the surface of the photoreceptor (in this case, positive charge) is difficult to be injected from the conductive support to the photosensitive layer, and the negative charge generated in the charge generation layer is transferred to the conductive support. An intermediate layer that satisfies the two functions of the intermediate layer described above has been proposed. When this intermediate layer is applied to an electrophotographic photosensitive member, it exhibits very good electrophotographic characteristics in the initial stage. However, there are few electron transport materials that exhibit excellent electron transfer characteristics, the organic material constituting the intermediate layer is likely to deteriorate due to repeated electrostatic hazards, and the electron transport material is affected by oxygen in the atmosphere. Due to the fact that it is easy to form a deep trap order, there is a problem that electrophotographic characteristics are deteriorated by repeated electrostatic hazards.
Alternatively, in order to prevent the occurrence of fog and image density unevenness, there is a method of forming an image using an organic photoreceptor in which a photosensitive layer is provided on a conductive support through an intermediate layer containing inorganic particles in a binder resin. It has been proposed (see Patent Document 12). However, in the case of such an organic photoreceptor, as described above, when the function of transporting the charge generated in the photosensitive layer to the conductive support is insufficient, the potential of the exposed portion is increased due to a decrease in charge generation efficiency, A problem that charging failure due to charge trapping in the intermediate layer is likely to occur is assumed.
Furthermore, an electrophotographic photosensitive member (see Patent Document 13) in which an intermediate layer is provided between the conductive support and the charge generation layer as a charge injection blocking layer in order to prevent fog-like image defects. In order to suppress deterioration of characteristics over time, an electrophotographic photoreceptor provided with an intermediate layer formed by applying a solution containing an organometallic compound between an aluminum substrate and a photosensitive layer (see Patent Document 14), against environmental changes In order to reduce the fluctuation of the electric resistance and to reduce the increase in the residual potential, an electrophotographic photosensitive member in which an intermediate layer made of single crystal silicon is provided between the support and the organic photoconductive layer has been proposed (patent) Reference 15). However, none of them is still sufficient for the long life required for the electrophotographic apparatus in recent years, that is, the compatibility between the mechanical hazard and the electrostatic hazard.

  The present invention has been made in view of the above prior art, and is compatible with mechanical hazards in cleaning processes and the like and in electrical hazards (electrostatic hazards) in charging processes, transfer processes, etc., and can be used repeatedly. Long life (environmentally friendly and easy to maintain) that can cope with high image quality and high speed without the occurrence of abnormal images such as image density unevenness and background smudges due to suppressed exposure area potential and poor charging. An object of the present invention is to provide an electrophotographic photosensitive member and an image forming method, an image forming apparatus, and a process cartridge for the image forming apparatus using the electrophotographic photosensitive member.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by the inventions described in the following [1] to [9], and have reached the present invention. Hereinafter, the present invention will be specifically described.

  [1]: The above-described problem is an electrophotographic photoreceptor having, in order, at least an intermediate layer, an electron injection layer, a charge generation layer, and a hole transport layer on a conductive support, and the intermediate layer includes a plurality of metal elements. This is solved by an electrophotographic photosensitive member characterized by being a layer made of an amorphous oxide containing.

  [2]: In the electrophotographic photosensitive member according to [1], the amorphous oxide containing the plurality of metal elements is an amorphous oxide containing at least two elements of indium, zinc, and gallium. It is characterized by that.

  [3]: The electrophotographic photosensitive member according to the above [1] or [2], wherein a film thickness of the intermediate layer made of the amorphous oxide is 0.1 μm or more and 0.9 μm or less. To do.

  [4]: The electrophotographic photosensitive member according to any one of the above [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 charge generation layer contains a phthalocyanine pigment as a charge generation material.

  [6]: In the electrophotographic photosensitive member according to the above [5], the phthalocyanine pigment has a maximum peak at 27.2 ± 0.2 ° with a Bragg angle 2θ with respect to Cu—Kα rays (wavelength 1.542 mm). It is a titanyl phthalocyanine having a peak at a minimum angle of 7.3 ± 0.2 °.

  [7]: The above-described problem is at least charged by using the electrophotographic photosensitive member according to any one of [1] to [6] and charging the electrophotographic photosensitive member by the charging process. A latent image forming process for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member, a developing process for attaching toner to an image portion of the electrostatic latent image formed by the latent image forming process, and a visible image formed by the developing process. This is solved by an image forming method characterized by repeatedly performing a transfer process of transferring an image onto a transfer target.

  [8]: The above-described problems are solved by the electrophotographic photosensitive member according to any one of [1] to [6], at least a charging unit for charging the electrophotographic photosensitive member, and an electrophotographic photosensitive member charged by the charging unit. Image forming unit comprising one unit selected from a latent image forming unit for forming an electrostatic latent image on the body surface and a developing unit for attaching toner to an image portion of the electrostatic latent image formed by the latent image forming unit The present invention is solved by an image forming apparatus having an apparatus process cartridge mounted thereon, wherein the image forming apparatus process cartridge is detachable.

  [9]: The above-described problems are solved by the electrophotographic photosensitive member according to any one of [1] to [6], at least a charging unit for charging the electrophotographic photosensitive member, and an electrophotographic photosensitive member charged by the charging unit. Image forming apparatus integrally comprising one means selected from a latent image forming means for forming an electrostatic latent image on the surface of the body and a developing means for attaching toner to the image portion of the electrostatic latent image formed by the latent image forming means This is solved by a process cartridge for an image forming apparatus, which is detachable from the main body.

The electrophotographic photoreceptor of the present invention comprises a structure having at least an intermediate layer, an electron injection layer, a charge generation layer, and a hole transport layer in this order on a conductive support, and the intermediate layer is an amorphous oxide, By using an inorganic semiconductor material that is durable against passing charges and electrochemically prevents unwanted charges from being injected into the photosensitive layer, and efficiently injects and transports the charges generated in the charge generation layer to the conductive support. Improves durability against electrical hazards (electrostatic hazards) in charging processes and transfer processes (improves durability related to charging properties such as dirt and image density unevenness), and mechanical hazards in cleaning processes, etc. (In addition, when the charge generated in the charge generation layer is efficiently injected and transported to the conductive support, the electron injection layer is generated in the charge generation layer.) Loading plays an important role to perform injection into the transport and the intermediate layer (electron)). As a result, it is possible to cope with high image quality and high speed with a long life, and even in repeated use, an increase in potential of the exposed portion and charging failure are suppressed, and abnormal images such as image density unevenness and background contamination are not generated. In addition, since it has a long life, it is excellent in environmental friendliness and easy maintenance.
According to the image forming method of the present invention, the electrophotographic photosensitive member having both durability against the mechanical hazard in the cleaning process and the like and the electrical hazard (electrostatic hazard) in the charging process and the transfer process is used. Even in image formation, a reduction in charging property does not occur, and a high-quality image with few defects such as image density unevenness and background stains can be formed continuously and stably.
According to the image forming apparatus and the process cartridge of the present invention, the electrophotographic photosensitive member having both durability against the mechanical hazard in the cleaning process and the like and the electrical hazard (electrostatic hazard) in the charging process and the transfer process is used. Even when the process linear velocity is high, the stable high-quality image can be continuously output without generating an abnormal image. Here, if a process cartridge is used, it is easy to store, transport, etc., and exchanging in a short time is excellent in handling.

1 is a schematic diagram illustrating an example of an image forming apparatus according to the present invention. It is the schematic which shows the structural example of the process cartridge which concerns on this invention. 3 is a diagram showing an X-ray diffraction pattern of titanyl phthalocyanine used in the charge generation layer coating solution of Example 2. FIG. It is a figure which shows the representative example (Examples 1-14) of the X-ray-diffraction pattern which measured the intermediate | middle layer formed in the Example by the X-ray-diffraction method. It is a figure which shows the typical example (Examples 1-9 and Example 14) of the composition profile of the depth direction which measured the intermediate | middle layer formed in the Example by Auger electron spectroscopy.

As described above, the electrophotographic photoreceptor in the present invention (hereinafter sometimes abbreviated as “photoreceptor”) has at least an intermediate layer, an electron injection layer, a charge generation layer, and a hole transport layer on a conductive support. An electrophotographic photoreceptor having layers in order, wherein the intermediate layer is a layer made of an amorphous oxide containing a plurality of metal elements.
The electrophotographic photoreceptor of the present invention has excellent durability against electrical hazards (electrostatic hazards) in charging processes and transfer processes, and also has good durability against mechanical hazards in cleaning processes. It can be compatible. Accordingly, it is possible to cope with higher image quality and higher speed, and even when used repeatedly, the rise in the potential of the exposed portion and charging failure are suppressed, and abnormal images such as image density unevenness and background contamination are not generated. In addition, since it has a long life, it is excellent in environmental friendliness and easy maintenance.

[Requirements for long-life electrophotographic photoreceptors]
In order to achieve the long life of the electrophotographic photosensitive member, it is important to impart durability to various hazards received from each process in image formation as described above. In particular, the mechanical hazards imposed by the cleaning process to remove the toner remaining on the surface of the electrophotographic photosensitive member and the electrostatic hazards received from the charging process and the transfer process give great stress to the photosensitive member. It is considered that this causes a change in the characteristics of the photoconductor and is an impediment to the long life of the photoconductor. In the present invention, while maintaining durability against mechanical hazards, in particular, it is intended to improve durability against electrostatic hazards, and more specifically, durability related to charging properties such as background contamination and image density unevenness. It is related to the technology that improves. That is, the electrophotographic photosensitive member of the present invention has the requirements required for a long-life electrophotographic photosensitive member.

[Estimated cause of deterioration of charging characteristics]
The charging process in the electrophotographic image forming process is to charge the surface of the photoconductor to a constant potential, and the uniformity is related to image density unevenness, background contamination, etc. It is regarded as an important technology for conversion.
In the electrophotographic photosensitive member, as characteristics necessary for uniformly charging the surface, there is no unnecessary charge injection from the conductive support, and there is little residual charge in the electrophotographic photosensitive member. Can be mentioned. If the electrophotographic photosensitive member does not have these characteristics, charge injection with the opposite polarity to the charged polarity occurs from the conductive support during charging of the electrophotographic photosensitive member in the charging process, and the charge applied to the surface. Canceling the charge or canceling the charge applied to the surface by the accumulated charge in the electrophotographic photosensitive member causes a phenomenon that a desired chargeability cannot be obtained.
In addition, as described above, the recent development trend of electrophotographic photosensitive members has been promoted to extend the service life for environmental compatibility, easy maintenance, etc., and unnecessary charge injection from the conductive support and charge trapping have been promoted. There is a need to maintain that there is no absence. In other words, even if the characteristics related to the charging property are very excellent in the initial stage, the material used by use deteriorates, and an injection site of unnecessary charges is generated, or residual charges are generated. In order to cause a decrease in chargeability due to an increase in the thickness of the material, the electrical durability of the material used has been demanded.

The present invention has been made to remedy this problem. In other words, an inorganic semiconductor material having durability against the passing charge is applied to the intermediate layer, and the inorganic semiconductor material that is electrochemically resistant to injecting unnecessary charges into the photosensitive layer is used, and is generated in the charge generation layer. It has been found that by efficiently injecting and transporting electric charges to and from a conductive support, the chargeability is not easily lowered over a long period of time, and an excellent electrophotographic photosensitive member can be obtained, resulting in the present invention. The electron injection layer constituting the electrophotographic photoreceptor of the present invention plays an important role in transporting charges (electrons) generated in the charge generation layer and injecting them into the intermediate layer. This function can effectively improve the charging characteristics.
Details of the present invention will be described below.

[Description of characteristics required for intermediate layer]
The intermediate layer of the electrophotographic photosensitive member described in the present invention includes a function for 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, Of the charges formed by the layers, it is preferable to have a function of transporting charges having the same polarity as the charged polarity of the photoreceptor. 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). Further, in order to obtain a long-life electrophotographic photosensitive member, it is important that the characteristics do not change due to repeated electrostatic hazards.
In addition, the said photosensitive layer in this invention points out the laminated body which consists of a charge generation layer / hole transport layer at least.

  Since the intermediate layer has hole blocking properties, the characteristics that the intermediate layer should have are that the ionization potential of the intermediate layer or the work function in the electron full band is higher than the Fermi rank of the conductive support, and that the intermediate layer itself has a hole function. It is mentioned that transportability is very small. As a material having these characteristics, a semiconductor material exhibiting n-type is preferable. In addition, from the viewpoint of work function, it can be mentioned that the band gap is relatively large.

The characteristics that the intermediate layer should have in order to transport electrons generated in the photosensitive layer to the conductive support (electron transportability) are that the electron affinity of the photosensitive layer is smaller than the electron affinity of the intermediate layer, and the intermediate layer transports electrons. It has the property.
Examples of the intermediate layer satisfying these characteristics include an electron transport layer formed by dispersing an organic material having an electron transport structure in a binder, an inorganic semiconductor exhibiting n-type, and the like. As the material in which the characteristics of the material are less likely to change due to electrostatic hazard, the 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.

[Examples of amorphous oxide]
The intermediate layer in the present invention is made of an amorphous oxide (inorganic semiconductor material).
Here, the amorphous oxide means a solid state oxide having an irregular atomic arrangement. This oxide can be broadly classified into a glass oxide semiconductor obtained by quenching an oxide in a fluid state at high temperature and an amorphous oxide formed at a relatively low temperature by a technique such as sputtering. . In consideration of the heat resistance of the conductive support, it is preferable to select an amorphous oxide as mentioned in the latter.
The amorphous oxide applied to the intermediate layer in the present invention is not particularly limited. For example, at least two of indium oxide, oxide containing at least two elements of indium, zinc, and tin, indium, zinc, and gallium are used. Examples include oxides containing elements. Among these, an amorphous oxide composed of three elements of indium, zinc and gallium is suitable as an intermediate layer of the electrophotographic photosensitive member.

[Method for forming intermediate layer made of amorphous oxide]
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. Examples thereof include laser ablation MBE, MOMBE, reactive vapor deposition, ion plating, cluster ion beam method, glow discharge sputtering, ion beam sputtering, and reactive sputtering.
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 applied to form a homogeneous film in a relatively large area such as an electrophotographic photosensitive member. The laser ablation method is suitable when fine composition control of the crystalline oxide is necessary, and various sputtering methods are suitable when mass productivity is necessary.

[Filming conditions for intermediate layer made of amorphous oxide]
Next, the film forming conditions of the amorphous oxide, particularly the film forming conditions by the sputtering method will be described in detail.
<Washing of substrate (conductive support)>
First, 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. Ideally, the surface of a clean conductive support is at least free of contaminants other than the 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 the amorphous oxide of the present invention 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.
Further, an oxide containing at least two elements of indium, zinc, and gallium exemplified as the amorphous oxide, in particular, an amorphous oxide composed of three elements of indium, zinc, and gallium, which are preferable, is an electron. When the intermediate layer of the photographic photoreceptor is used, it is necessary to use a polycrystalline sintered body containing at least indium, zinc and gallium. This polycrystalline sintered body can be produced by a generally known target production 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.
In addition, for the purpose of controlling the conductivity of the amorphous oxide, a desired impurity may be added to the target in advance. 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, the 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 sputtering, a plasma is formed while flowing a mixed gas of an inert gas and an oxygen gas into a reduced-pressure atmosphere, whereby an amorphous material is formed on a substrate (conductive support in the present invention) disposed on the counter electrode. An 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 represented by Group 18 elements, and other gases represented by nitrogen gas. Moreover, in order to add the said impurity, in addition to inert gas and oxygen, you may use together 1 or more types of gas.

<Oxygen partial pressure>
A general oxide semiconductor is characterized in that the conductivity can be controlled by the amount of oxygen (oxygen deficiency) in the oxide semiconductor without doping impurities, and the amorphous oxide described in the present invention is used. Have similar properties. This property indicates that the conductivity control of amorphous oxide can be controlled only by the oxygen flow rate (oxygen partial pressure) during film formation, which is important from the viewpoint of electron transport control in the intermediate layer. It becomes a 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. When it exceeds 20 vol%, the carrier concentration of the formed amorphous oxide becomes too low, which is not preferable because the electron conductivity becomes extremely low.

<Distance between target and substrate>
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 vacancies 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.

[Film quality of amorphous oxide]
In the present invention, attention must be paid to the film quality of the amorphous oxide in order to show good electrophotographic characteristics.
For example, in the present invention, it is important that the intermediate layer is a homogeneous amorphous film. The method for confirming that the film formed on the conductive support by the above-described method 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>
The electrical characteristics of the amorphous oxide used as the intermediate layer greatly influences the electrical characteristics of the electrophotographic photosensitive member. Therefore, in order to obtain the desired electrical characteristics of the electrophotographic photosensitive member, the amorphous oxide applied to the intermediate layer is used. It is necessary to appropriately select the electrical characteristics of the object. The following are typical examples of electrical characteristics of amorphous oxides.

<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.

<Surface resistance>
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. In addition to the present method, the measurement may be performed by a generally known method such as a four-probe method, a four-terminal method, or a two-terminal method.

《Bandgap》
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. (To be precise, the work function in the full band of the amorphous oxide) may be appropriately selected.
The band gap measurement method is measured by an electrochemical measurement method, a photochemical measurement method, or the like. For example, a band gap energy measurement method using a Tauc plot, which is one of the photochemical measurement methods, can be exemplified. In this method, in general, an absorption coefficient α and light energy hν (where h is a Planck constant and ν is a wave number) in a region of relatively large absorption near the optical absorption edge on the long wavelength side of a semiconductor. And the band cap energy E ₀ ,
αhν = B (hν−E ₀ ) ² (B is a constant)
Is based on what is believed to hold.
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 is obtained, it is not particularly limited, and various measurement methods may be used.

<Amorphous oxide film thickness>
It is considered that the 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 highly coherent laser light, so that moire tends to occur due to interference between incident laser light and reflected light from a conductive support, etc. For the purpose of compensating for physical contact between the body and the intermediate layer, the surface of the conductive support often has arbitrary irregularities. In such a case, when the film thickness of the intermediate layer is small, the film thickness deviation becomes large due to the unevenness of the surface of the conductive support, which may cause partial charging failure. In addition, when an amorphous oxide semiconductor as described in the present invention is used for the intermediate layer, if the film thickness is too large, the variation in composition in the depth direction of the film increases, resulting in variations in electrical characteristics depending on the location. Since it occurs or the time required for film formation becomes long, the cost for film formation becomes very large, which is not realistic. The film thickness of the amorphous oxide is 0.05 μm or more and 1.5 μm or less, preferably 0.1 μm or more and 0.9 μm or less. When the intermediate layer made of an amorphous oxide is less than 0.05 μm, it is difficult to uniformly coat the surface of the conductive support, and the effects described in the present invention cannot be sufficiently exhibited. 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.

[Explanation on the structure of the electrophotographic photosensitive member]
The photoreceptor of this embodiment is a laminate having at least an intermediate layer, an electron injection layer, a charge generation layer, and a hole transport layer in this order on a conductive support. In this configuration, the charge generation function and charge transport function required for the electrophotographic photosensitive member are handled by independent layers, so the device characteristics can be improved relatively easily by enhancing the function of each layer. It is.
In this layer structure, the charge generation layer is responsible for charge generation during the exposure process in the image formation process, and the holes generated here are injected into the hole transport layer and transported through the bulk of the hole transport layer. As a result, it reaches the surface of the electrophotographic photosensitive member, and as a result, the charge applied by the charging process in the image forming process is erased. Here, when the hole transport layer is not provided, the charge generation layer is disposed on the outermost surface of the electrophotographic photosensitive member, but most of the charge generation materials contained in the layer have poor chemical stability, When exposed to an acidic gas such as a discharge product around a charger in a photographic image forming process, the charge generation efficiency is reduced. Therefore, the electrostatic durability of the electrophotographic photoreceptor described in the object of the present invention is reduced. It is difficult to achieve.
On the other hand, electrons generated in the charge generation layer are injected into the electron injection layer and transported through the bulk of the electron injection layer, thereby releasing the electrons to the conductive support. Here, even when the electron injection layer is not provided, an electrophotographic photosensitive member having sufficient characteristics can be initially obtained. However, as it is repeatedly used, electrons remain between the intermediate layer and the charge generation layer. As a result, it is difficult to maintain the uniform charge described in the object of the present invention, and there is a concern that an afterimage or the like is generated.

<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 fluorenone skeleton, azo pigments having oxadiazole skeleton, azo pigments having bis-stilbene skeleton, azo pigments having distyryl oxadiazole skeleton, azo pigments having 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 photosensitive member characteristics can be maintained for a long time by applying a phthalocyanine pigment among the charge generating materials. Although the reason for this is not well understood, it is considered that one of the reasons is that it does not easily interact with the amorphous oxide described in the present invention.

As described above, the phthalocyanine pigment used in the present invention includes metal-free phthalocyanine or metal phthalocyanine, and a synthesis method described in Moser and Thomas “phthalocyanine compound” (Rheinhold, 1963), and the like, and Those obtained by other suitable methods can be 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. In particular, R-type titanyl phthalocyanine is preferably used.
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.

  According to 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 (a), 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 a 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. Stable photoconductor characteristics can be expressed over a long period of time by combining high sensitivity of a photographic photoconductor and an intermediate layer made of an amorphous oxide, which is very effective. In particular, titanyl phthalocyanine having a maximum peak at a Bragg angle 2θ of 27.2 ± 0.2 ° and a peak at a minimum angle of 7.3 ± 0.2 ° with respect to a Cu—Kα ray (wavelength 1.542Å) is preferable.

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 photosensitivity can be increased by using a small particle size phthalocyanine pigment.
Here, the average particle diameter 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.

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.

<About hole transport layer>
The hole transport layer is a layer having a hole transport function, and is a layer mainly composed of a hole transport material and a binder resin.
The hole transporting substance refers to a compound having a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, etc., and generally used compounds can be used.

  Specifically, poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, oxadi Azole derivative, imidazole derivative, monoarylamine derivative, diarylamine derivative, triarylamine derivative, stilbene derivative, α-phenylstilbene derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9-styrylanthracene derivative, pyrazoline derivative, Other known materials such as divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, etc. Is mentioned. These hole transport materials may be used alone or in combination of two or more. When forming a hole transport layer using these materials, it is used by being dispersed in a binder resin described later. The hole transport material is preferably 20 to 80% by weight, more preferably 30 to 70% by weight, based on the total weight of the hole transport layer.

The binder resin is not particularly limited and may be appropriately selected from known materials according to the purpose. For example, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Polymer, 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 , Thermoplastic or thermosetting resins such as poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin.
Further, as the binder resin, a polymer charge transport material having a hole transport function exemplified in Japanese Patent No. 3852812, Japanese Patent No. 3990499, or the like may be used. For example, a polymer material such as a polycarbonate, polyester, polyurethane, polyether, polysiloxane, acrylic resin, or the like having an arylamine skeleton, benzidine skeleton, hydrazone skeleton, carbazole skeleton, stilbene skeleton, or pyrazoline skeleton, or a polymer material having a polysilane skeleton Etc. can also be used, which is useful.
The hole transport layer can be formed by dissolving or dispersing the hole transport material and the binder resin or the polymer charge transport material in a suitable solvent, applying the solution, and drying.

Since most of the constituent components of the hole transport layer are solid at normal temperature and pressure, a solvent having a high affinity with the constituent components is used in preparing the coating liquid. The solvent used here is not particularly limited as long as it is a known solvent that is generally used for coating and coating. For example, a solvent used in the formation of the charge generation layer can also be used, and the solvent used is independent. It may be used in a mixture of two or more.
The coating method used for forming the hole transport layer is not particularly limited, and a commonly used coating method can be used. The viscosity of the coating liquid, the desired thickness of the hole transport layer, etc. It is advisable to select a coating method as appropriate. Examples include dip coating, spray coating, bead coating, ring coating, and the like.
Moreover, the plasticizer and leveling agent which are mentioned later can also be added to a positive hole transport layer if needed.
The thickness of the hole transport layer is preferably 50 μm or less, more preferably 45 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 hole transport layer formed by the above means 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 the thermal energy, air, nitrogen or other gas, steam, various heat media, infrared rays, or electromagnetic waves can be used, and heating is performed from the coating surface side or the 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 surface-like defect or crack may occur on the surface, or peeling may occur at the interface with the adjacent layer. In addition, when the organic solvent remains in the photosensitive layer, this volatile component may be scattered outside, resulting in failure to obtain desired electrical characteristics.

<Electron injection layer>
The electron injection layer is a layer responsible for transport of electrons generated in the charge generation layer and injection into the intermediate layer, and is a layer mainly composed of an electron transport material and a binder resin.
Examples of the electron transport material include chloroanil, bromanyl, 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- Examples thereof include electron-accepting substances such as trinitrodibenzothiophene-5,5-dioxide and diphenoquinone derivatives. From the viewpoint of electron injection, it is preferable to select an electron transport material in consideration of the relationship between the electron affinity of the charge generation layer, the electron injection layer, and the intermediate layer. From the viewpoint of electron transport, the formation of electron traps is small, and the electron mobility is low. A high electron transport material may be selected. In particular, from the viewpoint of electron transport, electron transport materials exemplified in JP-A-2007-79307, JP-A-2007-233116, and the like are preferable. These electron transport materials can be used alone or as a mixture of two or more.

When an electron injection layer is formed using these materials, the electron injection layer is dispersed in the binder resin described in the section of the hole transport layer. The electron transport material is preferably 10 to 80% by weight, more preferably 30 to 70% by weight, based on the total weight of the electron injection layer.
As with the hole transport layer, the electron injection layer can be formed by dissolving or dispersing the electron transport material and the binder resin in a suitable solvent, applying the solution, and drying.
The thickness of the electron injection layer is not particularly limited as long as electrons generated in the charge generation layer can be effectively transported to the intermediate layer. However, in consideration of an electron trap formed in the electron injection layer, etc. 10 micrometers or less are preferable and 7 micrometers or less are more preferable.

<Surface layer>
The electrophotographic photoreceptor of the present invention may be provided with a surface layer on the hole transport layer for the purpose of improving the wear durability. By providing the surface layer and increasing the wear durability, it is possible to obtain an electrophotographic photosensitive member with few image defects over a long period of time, combined with the high electrostatic durability described in the present invention.
Examples of the surface layer that can be used in the present invention include a surface layer in which a filler described in JP-A No. 2002-278120 is dispersed, a photocrosslinking type surface layer described in JP-A No. 2005-115353, and JP-A No. 2002-2002. The charge injection layer described in Japanese Patent No. 31911 can be used.

"Additive"
In the electrophotographic photosensitive member of the present invention, in order to improve environmental resistance, the layers constituting the photosensitive layer, such as the charge generation layer and the hole transport layer, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential. Alternatively, commercially available antioxidants, plasticizers, lubricants, ultraviolet absorbers and leveling agents may be added to each surface layer. The addition amount of these additives may be appropriately selected according to the purpose, and is preferably 0.01% by mass to 10% by mass with respect to the total mass of the layer to be added.

<Conductive support>
The conductive support (hereinafter sometimes abbreviated as “support”) is not particularly limited as long as it has a volume resistance of 10 ¹⁰ Ω · cm or less, and is appropriately selected depending on the purpose. For example, a metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, or platinum; a metal oxide such as tin oxide or indium oxide is deposited or sputtered to form a film or cylindrical plastic , Paper-coated or aluminum, aluminum alloy, nickel, stainless steel plates, etc., and extruding them, making them into raw pipes by methods such as drawing, then cutting, superfinishing, polishing, etc. Can be used. Further, an endless nickel belt and an endless stainless steel belt disclosed in JP-A-52-36016 can also be used as a support.
In addition, those in which conductive powder is dispersed in an appropriate binder resin and coated on the support can also be used as the 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 and silver, or metal oxide powder such as conductive tin oxide and ITO. Etc.
The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate, 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 Thermoplastic, thermosetting resin or photo-curing resin such as resin, urethane resin, phenol resin, alkyd resin and the like can be mentioned.
The 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, toluene and the like.
Furthermore, it is electrically conductive by 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, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as the support of the present invention.

  As will be described later, a highly coherent laser may be used to form a latent image in the electrophotographic process. As described above, the support is often made of a metal material, many of which have a high surface reflectance. When an electrophotographic photosensitive member is produced by applying the inorganic semiconductor material of the present invention on a support having such characteristics, interference occurs between writing light and reflected light from the support, resulting in image defects. Cheap. For this reason, when the reflectance of a support body is high, it is preferable to give an unevenness | corrugation to the surface of a support body and to reduce a reflectance. Further, protrusions and the like that are potentially present on the support may cause image defects when the photosensitive layer is laminated. By roughening this to an appropriate surface roughness, it is possible to provide a support surface with few protruding protrusions. 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.

The surface roughness (Rz) is measured using, for example, Surfcom 1400D (manufactured by Tokyo Seimitsu Co., Ltd.), and the surface roughness (Rz) is measured with respect to an evaluation length of 2.5 mm and a reference length of 0.5 mm. Is. The measurement location is 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. A total of 12 points are measured, and the average value is defined as the surface roughness (Rz) of the drum.
The surface roughness (Rz) 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. In this respect, the surface roughness (Rz) of the support is more preferably 3.0 μm or less.

Examples of the roughening method include honing and centerless polishing. The honing process is preferably used because it is inexpensive and the surface roughness can be easily adjusted. There are dry and wet processing methods for the honing process, and any of them 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 sprayed onto the surface of the support at high speed to roughen the surface. The pressure, speed, amount, type, shape, size, hardness, specific gravity or suspension concentration of the abrasive can be controlled. Similarly, the dry honing process is a method in which an abrasive is sprayed onto the support surface with air at a high speed to roughen the surface, and the surface roughness can be controlled in the same manner as the wet honing process. Examples of the abrasive used in these wet or dry honing processes include particles such as silicon carbide, alumina, zirconia, stainless steel, iron, glass beads, and plastic shots.

  However, in dry honing and liquid honing using amorphous alumina abrasive grains, the abrasive grains may pierce the surface of the support, and when an electrophotographic photosensitive member is produced, black spots on white images in the reversal development system, normal rotation It appears as white spots on a black image in the development system. In liquid honing using glass beads, it is difficult to control the roughness because the glass breaks immediately and pierces the support surface. Therefore, after roughening the support by liquid honing using spherical alumina abrasive grains or stainless abrasive grains as an abrasive, an intermediate layer and a photosensitive layer are formed to produce an electrophotographic photoreceptor. Is common. Further, in the roughening treatment of the support, an interference fringe prevention function from the viewpoint of processing time, amount of abrasive grains used, amount of energy consumption, and ease of removing residual abrasive grains from the roughened substrate. It is preferable to make the treatment conditions as mild as possible within the range satisfying the above and to keep the surface roughness (Rz) small.

[Image Forming Method and Image Forming Apparatus]
The image forming apparatus of the present invention includes at least 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 a latent image forming unit. A process cartridge for an image forming apparatus, which is integrally provided with one means selected from developing means for attaching toner to an image portion of an electrostatic latent image formed by (exposure means: latent image forming device), is mounted. The process cartridge for the forming apparatus is detachable. That is, the entire image forming apparatus includes an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit, and other units appropriately selected as necessary, for example, a fixing unit, It has cleaning means, static elimination means, recycling means, control means and the like. Here, the electrophotographic photosensitive member is the electrophotographic photosensitive member of the present invention.
The image forming method of the present invention includes at least a charging process (charging process) for charging the electrophotographic photosensitive member and a latent image for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging process. The formation process (exposure process), the development process (development process) for attaching toner to the image portion of the electrostatic latent image formed by the latent image formation process, and the developed image formed by the development process are transferred to the transfer target The transfer process (transfer process) is repeatedly performed. That is, the image forming method used in the present invention includes at least a charging step, an exposure step, a development step, and a transfer step, and further other steps appropriately selected as necessary, for example, a fixing step and a cleaning step. , A static elimination process, a recycling process, a control process, and the like.

  The image forming method used in the present invention can be preferably implemented by the image forming apparatus of the present invention, the charging step can be performed by the charging unit, and the exposure step can be performed by the exposing unit. The developing step can be performed by the developing unit, the transferring step can be performed by the transferring unit, the fixing step can be performed by the fixing unit, and the cleaning step can be performed by the cleaning unit. The other steps can be performed by the other means.

<Charging process and charging means>
The charging step is a step of charging the surface of the electrophotographic photosensitive member, and is performed by the charging unit.
The charging means is not particularly limited as long as it can uniformly apply a voltage to the surface of the electrophotographic photosensitive member, and can be appropriately selected depending on the purpose. A non-contact charging means for charging in a non-contact manner with the photoreceptor is preferably used. As the non-contact charging means, for example, a non-contact charger using a corona discharge, a needle electrode device, a solid discharge element; conductive or semiconductive disposed with a minute gap with respect to the electrophotographic photosensitive member And a charging roller. Among these, corona discharge is particularly preferable.
The corona discharge is a non-contact charging method that gives positive or negative ions generated by corona discharge in the air to the surface of the electrophotographic photosensitive member, and has a characteristic of giving a certain amount of charge to the electrophotographic photosensitive member. There are a charger and a scorotron charger having a characteristic of giving a constant potential.
The coroton charger is composed of a casing electrode that occupies a half space around the discharge wire, and a discharge wire placed almost at the center thereof.
The scorotron charger is obtained by adding a grid electrode to the corotron charger, and the grid electrode is provided at a position 1.0 mm to 2.0 mm away from the surface of the electrophotographic photosensitive member.

<Exposure process and exposure means>
The exposure step can be performed, for example, by exposing the surface of the electrophotographic photosensitive member imagewise using the exposure unit.
The optical system in the exposure is roughly classified into an analog optical system and a digital optical system. The analog optical system is an optical system that directly projects an original onto an electrophotographic photosensitive member by an optical system, and the digital optical system receives image information as an electrical signal, converts this into an optical signal, and converts it into an electrophotographic image. It is an optical system that exposes a photoreceptor to form an image.
The exposure unit is not particularly limited as long as the surface of the electrophotographic photosensitive member charged by the charging unit can be exposed like an image to be formed, and can be appropriately selected according to the purpose. However, various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, a liquid crystal shutter optical system, and an LED optical system can be used.
In the present invention, an optical backside system that performs imagewise exposure from the backside of the electrophotographic photosensitive member may be employed.

<Development process and development means>
The developing step is a step of developing the electrostatic latent image using a toner or a developer to form a visible image.
The visible image can be formed, for example, by developing the electrostatic latent image using the toner or the developer, and can be performed by the developing unit.
The developing unit is not particularly limited as long as it can be developed using, for example, the toner or the developer, and can be appropriately selected from known ones. For example, the toner or developer is accommodated. Preferred examples include those having at least a developing unit capable of bringing the toner or developer into contact or non-contact with the electrostatic latent image.
The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multi-color developing unit. For example, a toner having a stirrer for charging the toner or the developer by frictional stirring and a rotatable magnet roller is preferable.

In the developing device, for example, the toner and the carrier are mixed and agitated, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. . Since the magnet roller is disposed in the vicinity of the electrophotographic photosensitive member, a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is electrically attracted to the electrophotographic photosensitive member. Move to the surface of the body. As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the electrophotographic photosensitive member.
The developer accommodated in the developing device is a developer containing the toner, but the developer may be a one-component developer or a two-component developer.

<Transfer process and transfer means>
The transfer step is a step of transferring the visible image onto a recording medium. After the primary transfer of the visible image onto the intermediate transfer member using an intermediate transfer member, the visible image is transferred onto the recording medium. A primary transfer step of forming a composite transfer image by transferring a visible image onto an intermediate transfer body using two or more colors, preferably a full color toner, as the toner, and a composite transfer image; A mode including a secondary transfer step of transferring the transfer image onto the recording medium is more preferable.
The transfer can be performed, for example, by charging the electrophotographic photosensitive member using a transfer charger and transferring the visible image onto a recording medium by the transfer unit. The transfer means includes a primary transfer means for transferring a visible image onto an intermediate transfer member to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium. Embodiments are preferred. The intermediate transfer member is not particularly limited and may be appropriately selected from known transfer members according to the purpose. For example, a transfer belt and the like are preferable.

The transfer means (the primary transfer means and the secondary transfer means) includes at least a transfer unit that peels and charges the visible image formed on the electrophotographic photosensitive member toward the recording medium. preferable. There may be one transfer means or two or more transfer means. Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is typically plain paper, but is not particularly limited as long as it can transfer an unfixed image after development, and can be appropriately selected according to the purpose. PET for OHP A base or the like can also be used.

<Fixing process and fixing means>
The fixing step is a step of fixing the visible image transferred to the recording medium using a fixing device, and may be performed each time the toner of each color is transferred to the recording medium, or may be applied to the toner of each color. On the other hand, it may be carried out simultaneously at the same time in a state of being laminated.
The fixing unit is not particularly limited and may be appropriately selected depending on the intended purpose. A fixing unit and a heat source for heating the fixing member are used.
Examples of the fixing member include a combination of an endless belt and a roller, a combination of a roller and a roller, etc., but the warm-up time can be shortened, and in terms of realizing energy saving, A combination of an endless belt and a roller having a small heat capacity is preferable in terms of expansion of the fixable width.

<Cleaning process and cleaning means>
The cleaning step is a step of removing the toner remaining on the electrophotographic photosensitive member, and can be suitably performed by a cleaning unit. It is also possible to employ a method in which the residual toner charges are made uniform by the rubbing member and collected by the developing roller without using the cleaning means.
The cleaning means is not particularly limited, and may be selected from known cleaners as long as the electrophotographic toner remaining on the electrophotographic photosensitive member can be removed. For example, a magnetic brush cleaner Suitable examples include electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

<Static elimination process and static elimination means>
The neutralization step is a step of performing neutralization by applying a neutralization bias to the electrophotographic photosensitive member, and can be suitably performed by a neutralization unit.
The neutralization means is not particularly limited, and may be appropriately selected from known neutralizers as long as it can apply a neutralization bias to the electrophotographic photosensitive member. For example, a neutralization lamp is preferably used. Can be mentioned.

<Recycling process and recycling method>
The recycling step is a step of recycling the toner removed by the cleaning step to the developing unit, and can be suitably performed by the recycling unit. There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.

<Control process and control means>
The control step is a step of controlling each of the steps, and can be suitably performed by a control unit.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

[Description of Image Forming Apparatus and Process Cartridge Based on Drawing]
Next, the image forming apparatus and the process cartridge 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 of the present invention. For example, at least after the photosensitive member is charged, exposed to an image, and developed, the recording medium (image holding member: transfer paper) is used. It consists of a process of transferring a toner image, fixing, and cleaning the surface of the photoreceptor.
In some cases, an image forming apparatus that directly transfers an electrostatic latent image to a recording medium and develops it does not necessarily have the above-described process disposed on a photoconductor.

FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus. As a means for charging the electrophotographic photosensitive member (photosensitive member) on average, a charging charger 3 is used. 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, the image exposure unit 5 is used to form an electrostatic latent image on the uniformly charged photoreceptor 1. 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, the developing unit 6 is used to visualize the electrostatic latent image formed on the photoreceptor 1. 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. If this is developed with toner of negative (positive) polarity (detection fine particles), a positive image can be obtained, and if developed with toner of positive (negative) polarity, a negative image can be obtained.
Next, a transfer charger 10 is used to transfer the toner image visualized on the photoreceptor onto the recording medium 9. 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.
Next, a separation charger 11 and a separation claw 12 are used as means for separating the recording medium 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 photoconductor 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.
Further, a charge eliminating unit is used for the purpose of removing the latent image on the photosensitive member as necessary. As the charge removal means, the charge removal lamp 2 and the charge removal charger are used, and the exposure light source and the charging means can be used respectively. In FIG. 1, reference numeral 8 denotes a paper feed roller.
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. An example of the process cartridge is shown in FIG.
The process cartridge includes an electrophotographic photosensitive member (photosensitive member) 101, and further includes at least one of a charging unit 102, a developing unit 104, a transfer unit 106, a cleaning unit 107, and a charge eliminating unit (not shown). An apparatus (part) that can be attached to and detached from the image forming apparatus main body.

  The image forming process using the process cartridge of FIG. 2 will be described. The photosensitive member 101 is charged in the direction of the arrow while being charged by the charging unit 102 and exposed by the exposure unit 103, and the electrostatic latent image corresponding to the exposed image on the surface thereof. The electrostatic latent image is developed with toner by the developing unit 104, and the toner development is transferred to the recording medium 105 by the transfer unit 106 and printed out. Next, the surface of the photoconductor after the image transfer is cleaned by the cleaning unit 107 and further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

  The image forming method, the image forming apparatus, and the process cartridge of the present invention use the electrophotographic photosensitive member of the present invention having an intermediate layer made of an amorphous oxide semiconductor. Thus, it is possible to continuously obtain high-quality images with few defects and extremely low electrophotographic characteristics.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these Examples at all. “Parts” are all parts by weight.

<Example 1>
[Method for producing photoconductor]
An RF sputtering apparatus improved by preparing an aluminum cylinder (conductive support) having a surface roughness Rz of 0.9 μm, a diameter of 30 mm, and a length of 360 mm as a conductive support, and forming a film while rotating the cylinder. An intermediate layer was formed. As described above, a cooling jacket was provided inside the cylinder to prevent the substrate temperature from being overheated during sputtering. Also, using a 150 mm × 400 mm target made of a polycrystalline sintered body (composition ratio, In: Ga: Zn = 1: 1: 1) containing indium, zinc and gallium, an amorphous made of indium, zinc and gallium. quality oxide film (hereinafter In-Ga-ZnO _X) was formed as an intermediate layer. The film forming conditions were as follows.

[Film forming conditions]
-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: 3 vol% with respect to the total amount of inert gas and oxygen gas

Under the above conditions, 0.5 μm In—Ga—ZnO _X was formed as an intermediate layer. The film thickness was measured with an ellipsometer.
Moreover, the result of measuring the composition ratio of the amorphous oxide forming the intermediate layer by a fluorescent X-ray method described later was In: Zn: Ga = 100: 112: 117 as described later. Moreover, the surface resistivity measured by the measuring method mentioned later was 5.0 * 10 < ⁶ > (ohm / cm < ² >).

  Next, an electron injection layer coating solution, a charge generation layer coating solution, and a hole transport layer coating solution having the following composition were sequentially applied onto the intermediate layer and dried to dry the 4 μm electron injection layer, 0 A 3 μm charge generation layer and a 20 μm charge transport layer were formed.

[Coating solution for electron injection layer]
-Low molecular charge transport material of the following structural formula (1): 4 parts-Polyvinyl butyral (XYHL, manufactured by UCC): 5 parts-Methyl ethyl ketone: 80 parts

[Coating liquid for charge generation layer]
・ Τ-type metal-free phthalocyanine (average particle size 0.34 μm): 8 parts ・ Polyvinyl butyral (XYHL, manufactured by UCC): 5 parts ・ Methyl ethyl ketone: 80 parts

[Coating fluid for hole transport layer]
Bisphenol Z polycarbonate (Panlite TS-2050, manufactured by Teijin Chemicals): 10 parts Low molecular hole transport material of the following structural formula (2): 7 parts Tetrahydrofuran: 100 parts Tetrahydrofuran solution of 1% silicone oil (KF50) -100CS, manufactured by Shin-Etsu Chemical Co., Ltd.): 1 part

<Example 2>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge generation layer coating solution in Example 1 was changed to the following charge generation layer coating solution.

[Coating liquid for charge generation layer]
・ Titanyl phthalocyanine having the X-ray diffraction pattern shown in FIG. 3 (average particle size; 0.31 μm): 8 parts ・ Polyvinyl butyral (XYHL, manufactured by UCC): 5 parts ・ Methyl ethyl ketone: 80 parts

<Example 3>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge generation layer coating solution in Example 1 was changed to the following charge generation layer coating solution.

[Coating liquid for charge generation layer]
-Bisazo pigment of the following structural formula (3): 2.5 parts-Polyvinyl butyral (XYHL, manufactured by UCC): 0.5 part-Cyclohexanone: 200 parts-Methyl ethyl ketone: 80 parts

<Example 4>
An electrophotographic photosensitive member was produced in the same manner as in Example 2 except that the coating liquid for hole transport layer in Example 2 was changed to the following.

[Coating fluid for hole transport layer]
-Polymeric hole transport material of the following structural formula (4) (molecular weight / Mw; 130000): 10 parts-Tetrahydrofuran: 100 parts-Tetrahydrofuran solution of 1% silicone oil (KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.): 1 part

<Example 5>
To the electrophotographic photosensitive member comprising the conductive support / intermediate layer / electron injection layer / charge generation layer / hole transport layer obtained in Example 2, the following surface layer coating solution is applied to the surface using a spray coating method. After coating, the surface layer was cross-linked by irradiating with a metal halide lamp under the conditions of illuminance: 900 mW / cm ² and irradiation time: 20 seconds to obtain a cured surface film of 5.0 μm. Thereafter, drying was performed at 130 ° C. for 30 minutes to prepare an electrophotographic photosensitive member comprising a conductive support / intermediate layer / electron injection layer / charge generation layer / hole transport layer / surface layer.

[Coating liquid for surface layer]
-Radical polymerizable monomer [trimethylolpropane triacrylate (TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)]: 95 parts-Radical polymerizable compound having a hole transporting structure of the following structural formula (5): 95 parts-Photopolymerization initiator [1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure I-184, manufactured by Ciba Specialty Chemicals)]: 10 parts ・ Tetrahydrofuran: 1200 parts

<Example 6>
An electrophotographic photosensitive member was produced in the same manner as in Example 2 except that the electron transport material of the coating liquid for electron injection layer of Example 2 was changed to that described in the following structural formula (6).

<Example 7>
An electrophotographic photosensitive member was produced in the same manner as in Example 2 except that the electron transport material of the coating liquid for electron injection layer in Example 2 was changed to that described in the following structural formula (7).

<Example 8>
An electrophotographic photosensitive member was produced in the same manner as in Example 2 except that the film thickness of the electron injection layer in Example 2 was changed to 10 μm.

<Example 9>
An electrophotographic photosensitive member was produced in the same manner as in Example 2 except that the film thickness of the electron injection layer in Example 2 was changed to 2 μm.

<Example 10>
Except that the film thickness of the intermediate layer of Example 2 was formed at 0.05 μm (film formation under the film forming conditions described in Example 1; only film forming time was set to 1/10 of Example 2). An electrophotographic photosensitive member was produced in the same manner as in Example 2.

<Example 11>
Except that the film thickness of the intermediate layer of Example 2 was formed to 0.15 μm (film formation under the film formation conditions described in Example 1; only film formation time was made to be one third of that of Example 2). An electrophotographic photosensitive member was produced in the same manner as in Example 2.

<Example 12>
Except that the film thickness of the intermediate layer of Example 2 was 0.8 μm (except for film formation under the film formation conditions described in Example 1; only the film formation time was 1.6 times that of Example 2). An electrophotographic photosensitive member was produced in the same manner as in Example 2.

<Example 13>
Example 2 except that the film thickness of the intermediate layer in Example 2 was 1.0 μm (film formation was performed under the film formation conditions described in Example 1; only the film formation time was twice that of Example 2). In the same manner as in Example 2, an electrophotographic photosensitive member was produced.

<Example 14>
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 15>
The intermediate layer was formed using In: Ga: Zn = 1: 1.5: 1 as the composition ratio of the polycrystalline sintered body containing indium, zinc, and gallium used in the intermediate layer manufacturing method of Example 2. An electrophotographic photosensitive member was produced in the same manner as in Example 2 except that was formed.
The result of measuring the composition ratio of the amorphous oxide forming the intermediate layer by the fluorescent X-ray method described later was In: Zn: Ga = 100: 108: 137 as described later. Moreover, the surface resistivity measured by the measuring method described later was 4.9 × 10 ⁷ (Ω / cm ² ).

<Example 16>
An intermediate layer using a composition ratio of In: Ga: Zn = 1: 0.75: 1 of the polycrystalline sintered body containing indium, zinc, and gallium used in the intermediate layer manufacturing method of Example 2 An electrophotographic photosensitive member was produced in the same manner as in Example 2 except that was formed.
The result of measuring the composition ratio of the amorphous oxide forming the intermediate layer by a fluorescent X-ray method described later was In: Zn: Ga = 100: 110: 105 as described later. Moreover, the surface resistivity measured by the measuring method mentioned later was 6.2 * 10 < ⁵ > (ohm / cm < ² >).

<Example 17>
Example 2 except that the intermediate layer was formed by using In: Ga = 1: 1 as the composition ratio of the polycrystalline sintered body containing indium and gallium used in the intermediate layer manufacturing method of Example 2. An electrophotographic photosensitive member was produced in the same manner as described above.
The result of measuring the composition ratio of the amorphous oxide forming the intermediate layer by a fluorescent X-ray method described later was In: Ga = 100: 125 as described later. Further, the surface resistivity measured by the measurement method described later was 6.7 × 10 ⁷ (Ω / cm ² ).

<Example 18>
Implementation was performed except that the intermediate layer was formed using a composition ratio of In: Zn = 1: 1 of the polycrystalline sintered body containing indium, zinc, and gallium used in the intermediate layer manufacturing method of Example 2. An electrophotographic photosensitive member was produced in the same manner as in Example 2.
The result of measuring the composition ratio of the amorphous oxide forming the intermediate layer by a fluorescent X-ray method described later was In: Zn = 100: 111 as described later. Moreover, the surface resistivity measured by the measuring method mentioned later was 7.5 * 10 < ⁶ > (ohm / cm < ² >).

<Comparative Examples 1-3>
Coating for the charge generation layer used in Examples 1 to 3 was applied to an aluminum cylinder (conductive support) having a surface roughness Rz of 0.9 μm, a diameter of 30 mm, and a length of 360 mm used in Examples 1 to 3, respectively. The liquid and the charge transport layer coating liquid are sequentially applied and dried to form a 0.3 μm charge generation layer and a 20 μm charge transport layer, and a conductive support / charge generation layer / hole transport layer (intermediate) An electrophotographic photosensitive member (Comparative Examples 1 to 3) having a structure in which no layer and an electron injection layer are provided) was produced.

<Comparative Examples 4-6>
The aluminum cylinder (conductive support) having a surface roughness Rz of 0.9 μm, a diameter of 30 mm, and a length of 360 mm used in Examples 1 to 3 was used for the polycrystalline sintered bodies used in Examples 1 to 3, respectively. An intermediate layer is formed, and a charge generation layer coating solution and a hole transport layer coating solution used in each of Examples 1 to 3 are sequentially applied to the intermediate layer and dried to obtain a charge of 0.3 μm. An electrophotographic photoreceptor (Comparative Examples 4 to 6) comprising a generation layer, a 20 μm hole transport layer, and comprising a conductive support / intermediate layer / charge generation layer / hole transport layer (a structure in which no electron injection layer is provided). ) Was produced.

<Comparative Examples 7-9>
The electron injection layer coating solution used in Examples 1 to 3 was applied to an aluminum cylinder (conductive support) having a surface roughness Rz of 0.9 μm, a diameter of 30 mm, and a length of 360 mm used in Examples 1 to 3, respectively. Then, a 4.0 μm electron injection layer, a 0.3 μm charge generation layer, and a 20 μm hole transport layer are formed by sequentially applying and drying a charge generation layer coating solution and a hole transport layer coating solution. Then, electrophotographic photosensitive members (Comparative Examples 7 to 9) composed of a conductive support / electron injection layer / charge generation layer / hole transport layer (a configuration in which no intermediate layer was provided) were produced.

<Comparative Example 10>
The following intermediate layer coating solution and the electron injection layer used in Example 2 were applied to an aluminum cylinder (conductive support) having a surface roughness Rz of 0.9 μm, a diameter of 30 mm, and a length of 360 mm used in Example 2. Coating solution for coating, coating solution for charge generation layer, coating solution for hole transport layer, and drying sequentially, 3.5μm intermediate layer, 4μm electron injection layer, 0.3μm charge generation layer A 20 μm hole transport layer was formed, and an electrophotographic photosensitive member comprising a conductive support / intermediate layer / electron injection layer / charge transport layer / hole generation layer was produced.

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

<Comparative Example 11>
An electrophotographic photoreceptor in the same manner as in Example 2 except that the intermediate layer of Example 2 was tin oxide formed under the conditions of the following intermediate layer formation method using the modified RF sputtering apparatus described in Example 1. Was made.

(Intermediate layer forming method)
-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

  The following tests were carried out on the electrophotographic photoreceptors of Examples 1 to 18 and Comparative Examples 4 to 6 produced as described above. Representative examples of measurement results (Examples 1 to 14) are shown in FIG.

<< Structural analysis of amorphous oxide >>
It was evaluated by crystal structure analysis by an X-ray diffraction method that the intermediate layer made of an oxide containing at least two elements of indium, zinc, and gallium produced in the example was amorphous.
[Evaluation conditions for crystal structure analysis by X-ray diffraction]
Evaluation device: X-ray diffractometer X 'Part Pro (manufactured by Philips)
・ X-ray source: Cu (encapsulated tube)
-Filter: None-Scan axis: 2θ / θ
-Measurement angle range: 10 ° -100 °

  As is apparent from FIG. 4, the intermediate layer produced by the method shown in this example was an amorphous oxide.

<Amorphous oxide composition>
The composition ratios of the constituent components of the amorphous oxide produced in Examples 1 to 18 were evaluated using fluorescent X-ray analysis. The composition profile in the depth direction of the amorphous oxide was evaluated using Auger electron spectroscopy. Typical examples (Examples 1 to 9 and Example 14) of the depth direction composition profile of the amorphous oxide are shown in FIG.

[Conditions for evaluating composition ratio of amorphous oxide by fluorescent X-ray method]
・ Measurement equipment: Wavelength dispersive X-ray fluorescence analyzer RIX3000 (manufactured by Rigaku Corporation)
・ X-ray tube: Rh
・ Output: 50kV
・ Current: 50 mA

From the evaluation under the above conditions, the amorphous oxides obtained in Examples 1 to 18 were amorphous oxides having the following composition ratio.
Examples 1 to 14; In: Zn: Ga = 100: 112: 117
Example 15; In: Zn: Ga = 100: 108: 137
Example 16; In: Zn: Ga = 100: 110: 105
Example 17; In: Ga = 100: 125
Example 18; In: Zn = 100: 111

[Conditions for evaluating the composition profile of amorphous oxides by Auger electron spectroscopy]
・ 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

  From the result of FIG. 5, there was almost no variation in the depth direction of each constituent element (indium, zinc, gallium, oxygen), and it was a very homogeneous amorphous oxide.

<< Surface resistivity of amorphous oxide >>
As an electrical resistance evaluation of the amorphous oxides produced in Examples 1 to 18, surface resistivity was measured by the method described below.
As the substrate for forming the amorphous oxide, alkali-free glass (Corning # 1737) is used instead of the above-mentioned conductive support, and the amorphous oxide is formed under other conditions as described in Example 1. And subjected to surface resistivity measurement. In measuring the surface resistivity, a 25 μm gap, 10 mm long Au electrode was produced by vapor deposition on an amorphous oxide formed on an alkali-free glass, and a bias was applied between the electrodes. The measurement was carried out by measuring the passing current.
This surface resistivity measurement was carried out 10 times at different locations, and the average value was calculated. As a result, the surface resistivity of the amorphous oxides of Examples 1 to 14 was 5.0 × 10 ⁶ Ω / cm. ^2. The surface resistivity of the amorphous oxide of Example 15 was 4.9 × 10 ⁷ Ω / cm ² , and the surface resistivity of the amorphous oxide of Example 16 was 6.2 × 10 ⁵ Ω / cm 2. ^2. The surface resistivity of the amorphous oxide of Example 17 was 6.7 × 10 ⁷ Ω / cm ² , and the surface resistivity of the amorphous oxide of Example 18 was 7.5 × 10 ⁶ Ω / cm 2. ² .

Next, electrostatic property evaluation and image evaluation after electrostatic fatigue were performed using Examples 1 to 18 and Comparative Examples 1 to 11.
<< 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 photoreceptor unit to which the photoreceptor prepared in Examples and Comparative Examples was attached was set in an Imagio Neo 271 modified 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, Examples 1-2, 4-18, and Comparative Examples 1-2, 4-5, 7-8, and 10-11 using a phthalocyanine pigment as a charge generation material (with respect to 11, a running test was performed). In Example 3, using a 780 nm LD for the charge generation material, and 655 nm LD for Comparative Examples 3, 6, and 9, the write pattern was 100% write pattern (all solid). did. In order to load the electrophotographic photoreceptor with electrostatic fatigue equivalent to 100,000 running (5% test pattern / charge-exposure potential difference 750 V / electrophotographic photoreceptor electrostatic capacitance 110 pF / cm ² ) under these conditions, The passage 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 1-2, 4-18 and Comparative Examples 1-2, 4-5, 7-8, 10-11 using a phthalocyanine pigment as a charge generation material. For Example 11 and Comparative Examples 3, 6 and 9 using a Ricoh IPSiO Color CX9000 remodeling machine assembled with a 780 nm LD and using a bisazo pigment as a charge generating material. Used a modified IPSiO Color CX9000 with a 655 nm LD. Each device was modified 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 (post-charge potential and exposed portion potential) before and after the electrostatic fatigue was evaluated. As an output image, 5 sheets of white background were continuously output, and the background contamination was evaluated. Evaluation of afterimages was performed by outputting three images having a 3 cm × 3 cm × shape pattern continuously and then outputting halftone images continuously, and visually confirming the presence or absence of afterimages. The in-machine potential measurement results and image evaluation results are shown in Table 1 below.

The results of Table 1 show that the electrophotographic photoreceptors obtained in the examples all have higher electrostatic stability than the electrophotographic photoreceptors obtained in the comparative examples, and the occurrence of image defects is extremely small. ing. In addition, the electrophotographic photosensitive member obtained in Comparative Example 11 was poor in charging stability from the beginning, and a phenomenon such that defective charging occurred promptly during image evaluation was observed, so the electrostatic fatigue test was not performed.
The electrophotographic photosensitive member produced in Comparative Examples 1 to 3 to which an intermediate layer made of an amorphous oxide and an electron injection layer were not applied had a low dark portion potential from the beginning, and a large number of background stains were generated. When an electrophotographic photosensitive member provided with an intermediate layer made of an amorphous oxide and an electron injection layer prepared in Examples 1 to 3 was used, the dark portion potential was sufficiently high, the exposed portion potential was low, and the static potential was low. It is shown that the fluctuation of the value is small even by the electric fatigue, and the occurrence of the image defect is extremely small. In addition, in the electrophotographic photoreceptors of Comparative Examples 4 to 6 in which an intermediate layer made of an amorphous oxide is provided but the electron injection layer is not applied, the dark portion potential, the exposed portion potential, and the background stain are good. However, afterimage fatigue was confirmed after electrostatic fatigue. Further, in the electrophotographic photoreceptors of Comparative Examples 7 to 9 in which the intermediate layer made of an amorphous oxide is not provided and the electron injection layer is applied, as in Comparative Examples 1 to 3, the dark portion potential is reduced due to electrostatic fatigue. The stability and image defects were insufficient, such as remarkable and background smearing. In addition, although the intermediate layer / electron injection layer is applied as in Examples 1 to 3, the potential of the exposed area is slightly higher than that of Comparative Example 10 in which a particle-dispersed intermediate layer is applied as the intermediate layer. After electrostatic fatigue, image defects such as scumming and afterimages occurred, and the electrophotographic photosensitive member was not satisfactory.

The electrophotographic photoreceptor produced in the examples will be described in more detail. In Examples 1 to 3, the exposed portion potential was low from the beginning and the electrostatic stability was good, but metal-free phthalocyanine and bisazo were used as charge generation materials. In Examples 1 and 3 using the pigment, a slight background stain was confirmed in the image evaluation after the electrostatic fatigue test. On the other hand, Example 4 using a polymer charge transport material (polymer hole transport material) as a charge transport material (hole transport material) showed no image defects. Although the cause of the difference between Examples 1 to 3 is not clearly understood at the present time, it may be derived from the semiconductor characteristics of the charge generation material. Among them, the electrophotographic photosensitive member using the titanyl phthalocyanine pigment shown in Examples 2 and 4 as the charge generation material has a relatively low exposed area potential from the beginning, and no significant increase is caused by electrostatic fatigue. No image defects were observed before and after electrostatic fatigue, indicating that excellent electrophotographic characteristics were maintained over a long period of time.
Further, Example 5 in which a crosslinkable surface layer was laminated on the surface of the electrophotographic photoreceptor of the present invention for the purpose of improving wear durability was shown in Example 5. As a result, it was confirmed that the exposed portion potential was increased by laminating the surface layer, but the electrostatic stability effect expected from the present invention can be enjoyed without change, and the electrostatic stability is high, and the wear is high. It is possible to obtain an extremely long-life electrophotographic photosensitive member excellent in durability.
The case where the electron transport material used for the electron injection layer is changed is shown in Examples 6 to 7, and the case where the layer thickness of the electron injection layer is changed is shown in Examples 8 to 9. An electrophotographic photosensitive member exhibiting characteristics comparable to the results obtained in Example 2 was obtained, indicating that the electrophotographic photosensitive member is an excellent electrophotographic photosensitive member with little fluctuation due to electrostatic fatigue.
Results of using examples in which the film thickness of the amorphous oxide was changed to Examples 10 to 13 and using an intermediate layer in which the constituent elements of the amorphous oxide were changed and the element ratio was changed to Examples 15 to 18 However, the electrophotographic photoconductor is excellent in electrostatic stability with a sufficiently low initial exposure portion potential, little fluctuation in the electrostatic fatigue test, and few image defects. It has been shown.
The electrophotographic photosensitive member produced in Example 14 was not inferior to the result obtained in Example 2, but a phenomenon that a slight moire was generated in the output image was confirmed.
From the above results, it has been found that the electrophotographic photosensitive member shown in the present example has little variation in characteristics even with an electrostatic load and has few defects related to image quality over a long period of time.

  That is, the electrophotographic photosensitive member of the present invention has both long-life and durability against electrical hazards (electrostatic hazards) in the charging process and transfer process, and mechanical hazards in the cleaning process. Repeated use of the method can hardly cause an increase in the potential of the exposed area and charging failure, suppress the occurrence of abnormal images such as image density unevenness and background stains, and can stably form a high quality image. If such an electrophotographic photosensitive member is used, high speed, miniaturization, colorization, high image quality, and easy maintenance are strongly demanded in image forming apparatuses and image forming methods such as copying machines, laser printers, or ordinary facsimiles. It can correspond to.

(Reference in FIG. 1)
1 Electrophotographic photoreceptor (photoreceptor)
DESCRIPTION OF SYMBOLS 2 Static elimination lamp 3 Charger charger 5 Image exposure part 6 Developing unit 7 Charger before transfer 8 Feed roller 9 Recording medium 10 Transfer charger 11 Separation charger 12 Separation claw 13 Charger before cleaning 14 Fur brush 15 Cleaning blade (reference numeral in FIG. 2)
101 Electrophotographic photoreceptor (photoreceptor)
102 Charging means 103 Exposure means 104 Developing means 105 Recording medium 106 Transfer means 107 Cleaning means

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 JP 2006-154753 A JP 2003-35965 A JP 2004-198819 A JP 2006-235513 A

Claims (9)

  An electrophotographic photosensitive member having at least an intermediate layer, an electron injection layer, a charge generation layer, and a hole transport layer in this order on a conductive support, wherein the intermediate layer is made of an amorphous oxide containing a plurality of metal elements. An electrophotographic photosensitive member characterized by comprising:   2. The electrophotographic photosensitive member according to claim 1, wherein the amorphous oxide containing a plurality of metal elements is an amorphous oxide containing at least two elements of indium, zinc, and gallium.   3. The electrophotographic photosensitive member according to claim 1, wherein a film thickness of the intermediate layer made of the amorphous oxide is 0.1 μm or more and 0.9 μm or less.   The electrophotographic photosensitive member according to claim 1, wherein the conductive support has a surface roughness Rz of 0.6 μm or more.   The electrophotographic photosensitive member according to claim 1, wherein the charge generation layer contains a phthalocyanine pigment as a charge generation material.   The phthalocyanine pigment is titanyl phthalocyanine having a maximum peak at 27.2 ± 0.2 ° and a peak at a minimum angle of 7.3 ± 0.2 ° of the Bragg angle 2θ with respect to Cu—Kα ray (wavelength 1.542Å). The electrophotographic photosensitive member according to claim 5, wherein the electrophotographic photosensitive member is provided.   A charging process for charging at least the electrophotographic photosensitive member using the electrophotographic photosensitive member according to any one of claims 1 to 6, and an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging process. A latent image forming process, a developing process for attaching toner to the image portion of the electrostatic latent image formed by the latent image forming process, and a transfer process for transferring the developed image formed by the developing process to the transfer target An image forming method characterized by repeating the above.   The electrophotographic photosensitive member according to claim 1, at least a charging unit for charging the electrophotographic photosensitive member, and an electrostatic latent image is formed on the surface of the electrophotographic photosensitive member charged by the charging unit. A process cartridge for an image forming apparatus, which is integrally provided with one means selected from a latent image forming means and a developing means for attaching toner to an image portion of an electrostatic latent image formed by the latent image forming means, An image forming apparatus, wherein the process cartridge for the forming apparatus is detachable.   The electrophotographic photosensitive member according to claim 1, at least a charging unit for charging the electrophotographic photosensitive member, and an electrostatic latent image is formed on the surface of the electrophotographic photosensitive member charged by the charging unit. The image forming apparatus main body is integrally provided with one means selected from a latent image forming means and a developing means for attaching toner to an image portion of an electrostatic latent image formed by the latent image forming means. A process cartridge for an image forming apparatus.

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