JP4676921B2 - Image forming apparatus and image forming method - Google Patents

Description

  In the present invention, an electrostatic latent image carrier (hereinafter sometimes referred to as “electrophotographic photosensitive member”, “photosensitive member”, or “photoconductive insulator”) used in an image forming apparatus is at least a charge generation layer. The present invention relates to an image forming apparatus and an image forming method having a photosensitive layer comprising a charge transport layer and an organic charge generating material in the charge generating layer.

  In recent years, there has been a remarkable development of information processing system machines using electrophotography. In particular, an optical printer that converts information into a digital signal and records information by light is markedly improved in print quality and reliability. This digital recording technique is applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. In addition, since a variety of information processing functions are added to a conventional copying machine equipped with this digital recording technology for analog copying, the demand is expected to increase further in the future. In addition, with the spread of personal computers and the improvement in performance, the progress of digital color printers for performing color output of images and documents is rapidly progressing.

Most of such digital image forming apparatuses employ negative / positive development. This is because most of the images (originals) output by the conventional image forming apparatus are centered on characters, and the writing rate is lower than the output image (paper) (about 5 to 10%). Due to that.
It can be said that the conversion from analog to digital has shifted from positive-positive development to negative / positive development. There is a change in writing only information such as characters on the photosensitive member. Since the writing rate is low as described above, the output time of the light source is reduced to 1/10 if only the document information portion (about 10% or less of the whole) is used in consideration of the life of the writing light source. Is making use of.

  In an image forming apparatus using negative / positive development, the surface charge of the electrostatic latent image carrier remains in a portion (non-image portion, background portion) that is not written by a writing light source even after development and transfer. Since it may affect the next charging, a charge removal process is performed. For static elimination, light is used to generate photocarriers to cancel surface charges (photo static elimination), a method in which a conductive brush or the like is brought into contact with the photoconductor to leak charges, or a reverse bias is applied. A method of canceling the surface charge is used.

  In recent years, image forming apparatuses have been improved in image quality and color, and relatively high-definition writing and development have become possible, and information (originals) input to the image forming apparatus has changed somewhat. As described above, characters have mainly been used in past manuscripts, but photographic images, colored pictures, graphs, and the like have been input. When such various patterns of input signals exist, the next image formation may be affected unless the history of the previous cycle in image formation is erased. In many cases, an abnormal image called an afterimage is generated. The afterimage has already been formed in a non-uniform state when the photosensitive member is charged during the image forming process, and the entire area of the photosensitive member is written on the entire surface. (Especially halftone) The charging potential after writing is essentially uniform, whereas the history of the charged state of the photosensitive member before charging remains, so that the charging distribution becomes uneven. In this state, an electrostatic latent image is formed, and if this is developed by the developing unit, non-uniform development is performed, and the latent image formed in the previous image forming cycle remains as it is. It is what produces.

There are two reasons for this. One is that image formation has become very fast, so the capacity (charging ability) of the charger tends to be insufficient, and if the surface charge of the photoconductor before charging is not uniform, the history is picked up at the next charging. This is because it is impossible to ensure uniform charge. The other is that the use of the charging roller has increased due to the compactness of the image forming apparatus or tandemization by colorization. The charging roller causes a discharge phenomenon between the photosensitive member and charges the surface of the photosensitive member due to a bias potential difference between them. Will leave.
Therefore, the key is how to uniformize the surface potential (surface charge) of the photoreceptor before charging, and the charge removal process has played a very important role in improving image quality.

  Among the static elimination methods described above, methods other than the optical static elimination have the following problems. The method of charge leakage using a conductive brush or the like requires a member that makes contact with the surface of the photoconductor, and wear of the photoconductor and the contact member occurs, and high durability cannot be desired. In addition, the effect of the charge leakage method may be reduced due to contamination of the surface of the photoreceptor or the contact member. Further, when the speed is increased, a sufficient effect cannot be expected in consideration of the charge transfer time.

  In the method of applying the reverse bias, uniformization is not sufficiently performed when the bias application condition is too weak, and when the bias application condition is too strong, the surface of the photoreceptor is reversely charged. Since a normal photoconductor can move only a positive charge, it cannot be canceled when the surface is charged with a positive charge. Accordingly, when negative charging is performed at the next charging, the positive charge is first canceled and then negative charging is performed. This further creates a shortage of charger capacity. Further, when positively charged, it becomes easy to form carrier traps in the photosensitive layer, and it becomes easy to generate a residual potential of the photosensitive member, and as a result, the life of the photosensitive member is shortened.

From the above, it can be said that the use of optical static elimination is the best choice at the present time for the static elimination process in the image forming apparatus. As described above, in recent years, digital image forming apparatuses have become mainstream, and for the reasons described above, negative / positive development is used as the developing method used at that time. Compared with the case of positive / positive development in the analog method used conventionally, the meaning in static elimination is very different.
That is, in the positive / positive development, in the photostatic discharge after transfer, although the entire surface of the photoreceptor is usually irradiated with light, only the area corresponding to the writing portion of characters and the like is substantially discharged. For this reason, the area is at most about 10% with respect to the entire area of the photosensitive member.

On the other hand, in the negative / positive development, the non-exposed portion of the photoconductor (the portion where writing is not performed) is substantially neutralized, so that the same original as described above is close to 90% with respect to the entire area of the photoconductor. The area will be substantially neutralized. As used herein, “substantially charge removal” means that the photoconductor has a surface charge at the place where photostatic discharge is performed, and light irradiation of the charge removal member generates photocarriers inside the photoconductor, thereby This means that the surface charge of the photoreceptor is canceled out.
In other words, the positive / positive development and the negative / positive development that have been used in the past mean that the surface charge canceling rate of the photoconductor is completely different (resulting in a reverse history). Compared to the above, the effect of static elimination differs by at least about 10 times. However, studies on the influence (especially the neutralization light wavelength, etc.) in the static elimination process on the photosensitive member have not been conducted so much, and the actual situation is that it has been used as it is.

  Patent Document 1 (Japanese Patent Laid-Open No. 60-88981) or Patent Document 2 (Japanese Patent Laid-Open No. 62-87981) discloses a technique relating to a charge removal member, which includes an inorganic photoconductor (Se-based, a-Si). There is a description that the image forming apparatus used can prevent light fatigue and charging fatigue by irradiating with appropriate charge-removing light including light having a short wavelength. However, the photoconductor used in Patent Document 1 or Patent Document 2 is an inorganic photoconductor, and the photocarrier generation mechanism is essentially different from a photoconductor using an organic charge generating material as described later. For this reason, inorganic technology (photo static elimination) cannot be applied to an organic photoreceptor as it is. Further, the development method used is the age of positive / positive development, and the degree of influence of light neutralization is completely different from that of negative / positive development. Further, the wavelength of the static elimination light includes wavelength light in a region of 500 nm or more. As a result of performing an experiment by applying the technique of Patent Document 1 or Patent Document 2, the effect of suppressing the increase in the residual potential was not sufficient.

  In Patent Document 3 (Japanese Patent Laid-Open No. 61-36784), exposure is performed at a wavelength that approximately matches the intrinsic photosensitive wavelength of the dye-sensitized photoconductor, in other words, the wavelength of the region where no absorption of the sensitizing dye is performed. There is a description that the residual potential can be removed by performing static elimination using the same. However, the original material (for example, polyvinyl carbazole) or the like of a photosensitized photoreceptor subjected to dye sensitization has no absorption in the visible range, and is sensitized with a dye having absorption in the visible range. Therefore, in the above technique, the dye is not absorbed and the charge is removed in a wavelength region having absorption in polyvinyl carbazole. In this case, there is a case where the optical carrier generation efficiency in this wavelength band is low, and not only the charge removal cannot be performed efficiently, but also the photodegradation of polyvinyl carbazole occurs, so that it cannot always be an effective means. Further, the development method used is the age of positive / positive development, and the degree of influence of light neutralization is completely different from that of negative / positive development. For this reason, when it is used for negative / positive development which is the subject of the present invention, the effect is not sufficient.

  Patent Document 4 (Japanese Patent Application Laid-Open No. 62-38491) discloses that a photoconductor having a photosensitivity at a long wavelength and having a low sensitivity or a low photosensitivity on the short wavelength side is discharged with a short wavelength light. There is a description of suppressing sensitivity reduction due to light fatigue. However, in a relatively high-speed image forming apparatus, when neutralization is performed with light in a region with low sensitivity or substantially no photosensitivity, the neutralization function is insufficient and abnormal images cannot be suppressed. Occurs. It is important to have sufficient photosensitivity for the static elimination light, and the technique of Patent Document 4 cannot cope with current image forming measures. In Patent Document 4, the neutralization wavelength is not specified.

  In Patent Document 5 (JP-A-1-217490) and Patent Document 6 (JP-A-1-274186), a positively charged photoconductor having a charge generation layer laminated on a charge transport layer has a wavelength of 620 nm or less. There is a description that neutralization is performed by irradiating light to reduce the residual potential. The wavelength of the static elimination light includes wavelength light in the region of 500 nm or more. As a result of conducting an experiment by applying the technique of Patent Document 5 or 6, the effect of suppressing the increase in residual potential was not sufficient.

  Patent Document 7 (Japanese Patent Application Laid-Open No. 4-17489) describes that neutralization is performed by simultaneously irradiating two types of light emitting diodes to prevent an increase in residual potential under high temperature and high humidity. The wavelength of the static elimination light includes wavelength light in the region of 500 nm or more. As a result of performing an experiment by applying the technique of Patent Document 7, the effect of suppressing the increase in residual potential was not sufficient.

  In Patent Document 8 (Japanese Patent No. 3460285), in the charge removal of a single-layer photoreceptor containing an organic pigment, the charge removal is performed by irradiating light in a range including a wavelength region that is equal to or greater than the half-value width of the maximum absorbance of the photosensitive layer. There is a statement that it is efficient. Usually, a practical organic pigment has an absorption peak in the visible region, and therefore, the technique of Patent Document 8 cannot obtain a sufficient effect of suppressing the increase in residual potential.

  In Patent Document 9 (Japanese Patent Laid-Open No. 2002-287382), by selecting a wavelength at which the sensitivity of the photosensitive member at the charge eliminating wavelength is higher than the sensitivity of the photosensitive member at the writing light and using it for the charge removing light, There is a description that potential reduction and ghost generation can be suppressed. In this technique, the charge eliminating wavelength varies depending on the photosensitive material used, and the charge eliminating wavelength cannot be specified. In addition, organic pigments usually have an absorption peak in the visible region, and a spectral sensitivity peak is also present in the visible region. For this reason, in the technique of patent document 9, the static elimination technique by the wavelength of less than 500 nm is not produced.

  In Patent Document 10 (Japanese Patent Laid-Open No. 2005-311110), in the charge removal of an image forming apparatus using a charge generation material dispersion type (single layer photoreceptor) photoreceptor, the spectral absorption rate of the photoreceptor is relatively low. There is a description of irradiating light of a wavelength. This technique is performed in order to remove residual charges generated in the bulk of the photosensitive layer in repeated use of the single-layer photosensitive member. That is, in the case of a single-layer photoconductor, the charge generating material is uniformly dispersed in the bulk, and the irradiation light is absorbed near the surface of the photosensitive layer at a wavelength having a high absorption rate. The high resolution of single-layer photoconductors uses this phenomenon, and writing light is used to reduce the irradiation energy by using a wavelength with a high absorption rate of the photosensitive layer, and photocarriers are generated only near the surface of the photosensitive layer. Let For this reason, the movement distance of the charge having the opposite polarity to the polarity charged on the surface of the photosensitive member is small, and the diffusion due to the Coulomb repulsion is prevented by reducing the movement distance of the charge. On the other hand, since the irradiation light hardly reaches the inside of the bulk, when the charge having the same polarity as that charged on the surface of the photosensitive member is trapped in the photosensitive layer bulk and becomes a residual potential, it can be canceled. Can not. For this reason, in the static elimination light, light with a wavelength that penetrates deep into the bulk is used to cancel the light by generating optical carriers in the deep part of the bulk (near the electrode, near the center of the photosensitive layer, etc.). To do.

  On the other hand, the charge generation layer of the laminated photoreceptor is very thin, unlike the single-layer photosensitive layer. Further, the absorptance with respect to the writing light is 90% or less even at the maximum absorption wavelength (in other words, the writing light is transmitted through the charge generation layer by 10% or more). For this reason, even if the wavelength of the writing light is different, there is no change in the essence that charge generation occurs in the entire charge generation layer bulk. Therefore, in the case of a laminated photoreceptor, the effect described in Patent Document 10 does not occur.

Patent Document 11 (Japanese Patent Application Laid-Open No. 2004-45996) describes that the phthalocyanine compound is subjected to light irradiation with respect to the Soret band to perform static elimination. In the same document, it is described that a fluorescent lamp is used as a static elimination light source in order to realize this.
Further, Patent Document 12 (Japanese Patent Application Laid-Open No. 2004-45997) describes that a photoreceptor containing a phthalocyanine compound is subjected to charge removal with a fluorescent lamp.

  In FIG. 1, the example of the spectral emission spectrum of the light of a fluorescent lamp is shown. Fluorescent lamps contain several bright lines, but in addition to this, there is a large light emission from 500 to 650 nm. Since the light irradiation amount (light emission amount) depends on the area surrounded by the spectrum curve of FIG. 1, the light of the fluorescent lamp irradiated on the photoconductor is substantially in the above wavelength range (500 to 650 nm). ) Is irradiated on the main.

  In Patent Documents 11 and 12, charge removal by 680 nm red LED light and charge removal by fluorescent lamp irradiation are compared. From the spectrum of FIG. 1, the comparison between the two shows that the charge removal by the red LED light of 680 nm is compared with the charge removal by light emission in the wavelength range of 500 to 650 nm. Since the light corresponding to the phthalocyanine Sore band (λmax ≈ 350 nm) is not zero, it is true that the Sore band is irradiated with light, but the other light components are larger. Absorption of the non-banded area is large.

  In Patent Document 13 (Japanese Patent Laid-Open No. 2005-181991), the writing wavelength (λa), the static elimination wavelength (λb), and the maximum spectral sensitivity wavelength (λc) of the photosensitive member are all in the range of 380 to 520 nm. An image forming apparatus that satisfies the relationship of <λc <λb is disclosed. The present invention is similar to the present invention in terms of light neutralization by the wavelength in the blue region. However, the photoreceptor (intermediate layer) of Patent Document 13 cannot absorb static elimination light, and the effect of the present invention cannot be expected.

  Under such circumstances, the printer and copying machine are required to have higher image quality and higher durability, including colorization. There are two problems in improving the image quality in a digital machine. One is how to uniformly form an electrostatic latent image with minute dots, and the other is how to reduce various abnormal images. In terms of increasing durability, extending the life of the photoreceptor is the most effective method.

  There are various approaches for solving these problems, but what can be said in common to both is how to reduce the deterioration due to electrostatic fatigue of the photoreceptor used in these image forming apparatuses. Specifically, it is how to suppress the increase in the residual potential (exposure portion potential) during repeated use, among the suppression of the exposure portion potential residual potential increase and the suppression of the initial potential decrease during dark place charging. .

As a countermeasure for increasing the residual potential, the development so far has been performed by devising the design (prescription, configuration, etc.) of the photoreceptor. However, the electrostatic fatigue of the photoconductor varies greatly depending on the photoconductor formulation or process conditions. From the viewpoint of development of the photoconductor, it is necessary to cope with each process condition. Under such circumstances, little study has been made on the electrostatic fatigue of the photoreceptor from the process conditions.
JP 60-88981 A JP-A-62-87981 JP-A 61-36784 JP-A-62-38491 JP-A-1-217490 JP-A-1-274186 JP-A-4-17489 Japanese Patent No. 3460285 JP 2002-287382 A Japanese Patent Laying-Open No. 2005-31110 JP 2004-45996 A JP 2004-45997 A JP 2005-181991 A

  An object of the present invention is to solve the above-mentioned problems in the prior art and achieve the following objects. That is, the present invention provides an image forming apparatus and an image forming method capable of forming a highly durable and high-definition image by suppressing an increase in residual potential due to repeated use of the photoreceptor in order to form a highly durable and high-definition image. The purpose is to provide.

The present inventors have examined how the process conditions affect the electrostatic fatigue of the photoreceptor, particularly the increase in residual potential. The examination method is as follows.
A state in which only charging, writing, and static elimination are applied with development, transfer, and cleaning members removed so as not to affect the shape and physical properties other than the electrostatic characteristics of the photoreceptor as much as possible in repeated use in an image forming apparatus. Then, an electrostatic fatigue test of the photoreceptor was performed.
(1) The writing rate by the writing light was changed, and the amount of charge passing through the photoreceptor was measured.
(2) The surface charge was erased only by static elimination light without writing, and the passing charge amount of the photoreceptor was measured.

At this time, the following knowledge was obtained by evaluating the residual potential of the photosensitive member under various conditions (1) and (2).
(3) The increase in the residual potential of the photoconductor depends on the amount of charge passing through the photoconductor. Even when the writing rate is changed, the amount of increase in residual potential is evenly arranged by arranging the amount of passing charges.
(4) The passing charge amount of the photoreceptor depends on the light irradiation amount in one image forming cycle. Regardless of writing and static elimination, it depends on the light irradiation amount (more precisely, the light absorption amount of the photosensitive member).
(5) In the case of negative / positive development, most of the light irradiation amount is given by light neutralization.

Further, an experiment similar to the above was performed with a transfer member attached so that a reverse bias could be applied to the photoreceptor before the charge removal step. By making it possible to measure the surface potential of the photoconductor before static elimination and changing the reverse bias, the surface potential of the photoconductor before static elimination becomes almost the same as the surface potential after static elimination in the above experiments (3) to (5). The reverse bias can be applied under such conditions.
When the electrostatic fatigue test was performed in this state, the amount of increase in the residual potential of the photoconductor became very small and became a magnitude depending on the writing rate, and the effect of static elimination did not appear at all.

From the above, the following can be said.
(6) If the photoreceptor surface potential is lowered before static elimination, the residual potential is unlikely to increase. In other words, if the surface potential of the photosensitive member is low at the time of charge removal, irradiation with charge removal light does not contribute to an increase in residual potential.
(7) Even when a reverse bias is applied and the surface potential of the photoconductor is lowered before static elimination, the amount of increase in residual potential can be organized by the amount of charge passing through the photoconductor, as in (3) above.
From (3) to (7), the increase in residual potential depends on the amount of charge passing through the photoconductor, but most of it is generated in the static elimination process, and how to control the static elimination process depends on the increase in residual potential. One key to control.

  The passing charge amount shown in (3) is the passing charge amount per unit surface area of the photoreceptor in one cycle of image formation, and depends on the amount of photocarrier generated. Therefore, the image forming conditions depend on the charging potential (applied electric field strength to the photosensitive member), the exposure amount, the exposure area, the electrostatic capacitance (film thickness) of the photosensitive member, the carrier generation efficiency, and the like. However, in the target image forming apparatus, these items cannot be changed so much.

For example, greatly changing the charging potential brings about the following changes. When the charging potential is greatly increased, the hazard to the photoreceptor increases. In the case of a large decrease, the background potential (photosensitive member charging potential-developing bias) becomes small, or the developing potential (developing bias-photosensitive member exposed portion potential) becomes small, and image forming conditions (especially developing conditions). Becomes very narrow and the margin of the system becomes small.
Changing the exposure amount greatly brings about the following changes. When the exposure amount is reduced, there are cases where the image density is insufficient or the contrast cannot be obtained. On the other hand, when the exposure amount is increased, a phenomenon that the dots are crushed occurs.

The electrostatic capacity (film thickness) and carrier generation efficiency of the photoconductor do not change significantly unless the photoconductor material itself is changed significantly. There are limits to the main materials (charge generation materials and charge transport materials) that can be used for photoconductors, and it is extremely difficult to change them to completely different materials.
Accordingly, the passing charge amount of the photoconductor mounted on the target image forming apparatus does not change significantly, and greatly depends on the light irradiation amount.

  However, the light irradiation amount referred to here is the light irradiation amount to the photosensitive member in one cycle of image formation (charging, writing, developing, transferring, discharging). The image formation includes a fixing step, but is not directly in contact with the photoconductor, and therefore is omitted from the description here. In other words, it can be seen that light irradiation to the photosensitive member consists of two types of writing light and static elimination light.

  In general, an image forming apparatus that performs current digital writing uses negative / positive development. This is due to the fact that most of the writing rate of an actual document is 10% or less, and the purpose is to reduce stress on the writing light source. However, from the viewpoint of the photoconductor side, if the surface potential of the photoconductor is not canceled (smoothed) before the next image forming cycle, it will be affected at the next charging. The surface potential of the photoreceptor is reduced as much as possible before charging in the next step.

  As described above, since the writing rate is about 10%, 90% or more of the surface of the photoconductor enters the charge removal process with surface charge on it. Here, the residual charge is erased by irradiating the surface potential of the photoreceptor remaining after the transfer with a charge-removing light and generating a photocarrier. That is, 90% or more of the charge passing through the photoreceptor generated in one cycle of the image forming process is generated in the static eliminating process.

  Up to this point, this is the normal state of an image forming apparatus using negative / positive development. Basically, all negative / positive images are basically output except when only originals that are continuously written on the entire surface are output. This is common to image forming apparatuses using development. However, as described above, the actual situation is that analysis from the process side regarding the electrostatic fatigue of the photosensitive member has not been carried out so much.

  The present inventor examined the control by process conditions for the increase of the residual potential (exposure portion potential) in the repeated use of the photoreceptor. As described above, the static elimination process in image formation has a great influence. Was revealed.

  Next, an analysis was performed on how the residual potential (exposure portion potential) increased due to repeated use of the photoreceptor. As a result, in a high-speed process in which writing is performed with a strong light such as a laser beam on a laminated photoreceptor composed of a conductive support / intermediate layer / charge generation layer / charge transport layer, the carrier movement or charge of the intermediate layer It has been clarified that the carrier injection from the generation layer becomes the rate-determining factor and the residual potential (exposed portion potential) rises.

  That is, in the electrophotographic photoreceptor having the above-described configuration, since a hole transport material is generally used for the charge transport layer, a negative charge is charged on the surface of the photoreceptor. Therefore, of the photocarriers generated in the charge generation layer, holes are injected into the charge transport layer, cross the charge transport layer, and cancel the surface charge. On the other hand, electrons are injected into the intermediate layer, traverse the intermediate layer, arrive at the conductive support, and cancel charges (holes) of opposite polarity induced during charging. At this time, a hole transport material is used for the charge transport layer, and the current technology has a response speed of about several tens of μs as a transit time. For image output of about several tens of sheets per minute We can cope enough.

  On the other hand, the intermediate layer is made of a material exhibiting N-type conduction characteristics and has an electron transport property. However, currently used intermediate layers include (1) support surface concealment (surface roughness reduction), (2) moire prevention, (3) electron transport, and (4) hole injection from the support. It is a situation where many functions such as prevention are carried. In particular, in negative / positive development in which the present invention is used, it is not an exaggeration to say that the background stain as the abnormal image determines the rate of life, and the function (4) is regarded as important.

  In order to strengthen this hole injection prevention function, the intermediate layer is given rectification (only electrons flow), the resistance is increased, the film thickness is increased and the time constant is increased. . However, it is difficult to impart complete rectification, and as a result, a balanced design is aimed at, and the electron transportability is slightly reduced. Alternatively, the electron injection property from the charge generation layer to the intermediate layer is deteriorated. For this reason, it has been found that when the photoreceptor is used repeatedly, a residual potential (exposure portion potential) rises in the direction in which electrons accumulate in the intermediate layer (charge generation layer).

Furthermore, examination was repeated regarding the conditions (mainly light wavelength) of static elimination light. As described above, in an image forming apparatus in which negative / positive development is used, most (90% or more) of the photocarrier of the photoconductor is generated in the photostatic process. The neutralizing light exhibits its function as long as the photoconductor (charge generation layer) has a wavelength with absorption. In general, a light source such as an LED array or a fluorescent lamp is used to irradiate substantially uniform light in the longitudinal direction of the photoreceptor. In the past, fluorescent lamps have been mainly used, but have the following problems because they include light in an area where the charge transport layer has absorption.
(1) Since a part of light is absorbed by the charge transport layer, there is a case where sufficient light does not reach the charge generation layer, and there is a case where the amount of light needs to be very large.
(2) As a result of the charge transporting material absorbing the static elimination light, the charge transporting material may deteriorate and affect the electrostatic characteristics of the photoreceptor.

  In order to overcome such a problem, a red LED (having a wavelength on the order of 600 nm) has generally been used. At the wavelength of this red LED, normally used charge transport materials have no absorption, the above-mentioned two problems can be cleared, and many charge generation materials have a large absorption, so that the charge removal is carried out efficiently. In addition, the fact that the cost of the LED is relatively low is also a great advantage of using this member. Conventionally, this has been considered.

The present inventor questioned from the analysis result of the increase in the residual potential (exposure portion potential) whether the neutralization by irradiating light of a relatively long wavelength such as the red LED is optimal for repeated use of the photoreceptor. We investigated the wavelength dependence of static elimination light. Specifically, light of various wavelengths was created by combining a monochromatic laser beam or an appropriate light source and a filter, and studies were made on the residual potential increase in repeated use of the photoreceptor.
As a result, it has been found that red charge removal, which has been considered to be good in the past, raises the residual potential rather than irradiating light with a shorter wavelength. As a result, specifically, the intermediate layer is made to contain a specific material to give a specific photoelectric attribute, and the neutralization is performed with light having such a wavelength that the intermediate layer can absorb the static elimination light. Thus, it was found that the increase in the residual potential can be significantly suppressed. More specifically, the intermediate layer contains nitrogen-doped titanium oxide, the nitrogen-doped titanium oxide can absorb light, and the charge is removed by light having a wavelength shorter than 500 nm.
Obtaining the above knowledge, the present inventors have completed the present invention.

This invention is based on the said knowledge of this inventor, and as a means for solving the said subject, it is as follows (1)-(23).
(1) “An electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and developing the electrostatic latent image with toner. Development means for forming a visual image; transfer means for transferring the visible image to a recording medium; fixing means for fixing the transferred image transferred to the recording medium; An electrostatic latent image carrier having a support and a photosensitive layer comprising at least an intermediate layer, a charge generation layer and a charge transport layer on the support. The intermediate layer contains at least nitrogen-doped titanium oxide, and the charge generation layer contains an organic charge generation material, and the charge removal means is a charge removal means that irradiates light having a wavelength shorter than 500 nm. Image forming apparatus characterized by
(2) “Image forming apparatus according to item (1), wherein the nitrogen-doped titanium oxide is not subjected to surface treatment”
(3) “The image forming apparatus according to item (1) or (2), wherein the organic charge generating substance is an azo pigment represented by the following formula (I):

（式中、Ｃｐ_１，Ｃｐ_２はカップラー残基を表わす。Ｒ_２０１，Ｒ_２０２はそれぞれ、水素原子、ハロゲン原子、アルキル基、アルコキシ基、シアノ基のいずれかを表わし、同一でも異なっていても良い。またＣｐ_１，Ｃｐ_２は下記（II）式で表わされ、

(In the formula, Cp ₁ and Cp ₂ represent a coupler residue. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, which may be the same or different. Cp ₁ and Cp ₂ are represented by the following formula (II):

式中、Ｒ_２０３は、水素原子、アルキル基、アリール基を表わす。Ｒ_２０４，Ｒ_２０５，Ｒ_２０６，Ｒ_２０７，Ｒ_２０８はそれぞれ、水素原子、ニトロ基、シアノ基、ハロゲン原子、ハロゲン化アルキル基、アルキル基、アルコキシ基、ジアルキルアミノ基、水酸基を表わし、Ｚは置換もしくは無置換の芳香族炭素環または置換もしくは無置換の芳香族複素環を構成するのに必要な原子群を表わす。）」
（４）「前記アゾ顔料のＣｐ_１とＣｐ_２が互いに異なるものであることを特徴とする前記第（３）項に記載の画像形成装置」
（５）「前記有機電荷発生物質がＣｕＫαの特性Ｘ線（波長１．５４２Å）に対するブラッグ角２θの回折ピーク（±０．２゜）として少なくとも２７．２゜に最大回折ピークを有し、更に９．４゜、９．６゜、２４．０゜に主要なピークを有し、最も低角側の回折ピークとして７．３゜にピークを有し、該７．３°のピークと９．４゜のピークの間にピークを有さず、更に２６．３°にピークを有さないチタニルフタロシアニン結晶であることを特徴とする前記第（１）項又は第（２）項に記載の画像形成装置」
（６）「前記電荷輸送層が、下記（III）式で表わされる電荷輸送物質を含有することを特徴とする前記第（１）項乃至第（５）項の何れかに記載の画像形成装置；

In the formula, R ₂₀₃ represents a hydrogen atom, an alkyl group, or an aryl group. R ₂₀₄ , R ₂₀₅ , R ₂₀₆ , R ₂₀₇ , and R ₂₀₈ each represent a hydrogen atom, a nitro group, a cyano group, a halogen atom, a halogenated alkyl group, an alkyl group, an alkoxy group, a dialkylamino group, or a hydroxyl group, and Z is A group of atoms necessary for constituting a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring. ) "
(4) “Image forming apparatus according to item (3), wherein Cp ₁ and Cp ₂ of the azo pigment are different from each other”
(5) “The organic charge generating material has 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 1.542 mm) of CuKα, It has major peaks at 9.4 °, 9.6 °, and 24.0 °, and has a peak at 7.3 ° as a diffraction peak at the lowest angle side. The image as described in (1) or (2) above, which is a titanyl phthalocyanine crystal having no peak between 4 ° peaks and further having no peak at 26.3 °. Forming device "
(6) "The image forming apparatus according to any one of (1) to (5), wherein the charge transport layer contains a charge transport material represented by the following formula (III): ;

（式中、Ｒ_３０１、Ｒ_３０３及びＲ_３０４は水素原子、アミノ基、アルコキシ基、チオアルコキシ基、アリールオキシ基、メチレンジオキシ基、無置換のアルキル基、ハロゲン原子又は置換もしくは無置換のアリール基を、Ｒ_３０２は水素原子、アルコキシ基、置換もしくは無置換のアルキル基又はハロゲンを表わす。またｋ、ｌ、ｍ及びｎは１、２、３又は４の整数であり、各々が２、３又は４の整数のときは前記Ｒ_３０１、Ｒ_３０２、Ｒ_３０３及びＲ_３０４は同一でも異なっていてもよい。）」
（７）「前記感光層上に保護層を有することを特徴とする前記第（１）項乃至第（６）項の何れかに記載の画像形成装置」
（８）「前記保護層が除電光を３０％以上透過することを特徴とする前記第（７）項に記載の画像形成装置」
（９）「前記保護層が、比抵抗１０^１０Ω・ｃｍ以上の無機顔料及び金属酸化物から選択される少なくともいずれかを含むことを特徴とする前記第（７）項又は第（８）項に記載の画像形成装置」
（１０）「前記保護層が、少なくとも電荷輸送性構造を有しない３官能以上のラジカル重合性モノマーと１官能の電荷輸送性構造を有するラジカル重合性化合物とを硬化することにより形成されることを特徴とする前記第（７）項又は第（８）項に記載の画像形成装置」
（１１）「前記保護層に用いられる１官能の電荷輸送性構造を有するラジカル重合性化合物が、下記一般式（１）及び（２）の化合物からなる群から選択された少なくとも一種以上であることを特徴とする前記第（１０）項に記載の画像形成装置；

Wherein R ₃₀₁ , R ₃₀₃ and R ₃₀₄ are a hydrogen atom, amino group, alkoxy group, thioalkoxy group, aryloxy group, methylenedioxy group, unsubstituted alkyl group, halogen atom or substituted or unsubstituted aryl. R ₃₀₂ represents a hydrogen atom, an alkoxy group, a substituted or unsubstituted alkyl group or a halogen, and k, l, m and n are integers of 1, 2, 3 or 4, each of which is 2, 3 Or when R is an integer of 4, R ₃₀₁ , R ₃₀₂ , R ₃₀₃ and R ₃₀₄ may be the same or different.
(7) “Image forming apparatus according to any one of items (1) to (6), wherein a protective layer is provided on the photosensitive layer”
(8) “Image forming apparatus according to item (7), wherein the protective layer transmits at least 30% of the static elimination light”
(9) The item (7) or the item (8), wherein the protective layer contains at least one selected from inorganic pigments and metal oxides having a specific resistance of 10 ¹⁰ Ω · cm or more. Image forming apparatus described in "
(10) “The protective layer is formed by curing at least a trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. The image forming apparatus according to item (7) or (8), characterized in that
(11) “The radically polymerizable compound having a monofunctional charge transporting structure used in the protective layer is at least one selected from the group consisting of compounds of the following general formulas (1) and (2). An image forming apparatus according to item (10), characterized by:

｛式中、Ｒ_１は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ_７（Ｒ_７は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基）、ハロゲン化カルボニル基若しくはＣＯＮＲ_８Ｒ_９（Ｒ_８及びＲ_９は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい）を表わし、Ａｒ_１、Ａｒ_２は置換もしくは無置換のアリーレン基を表わし、同一であっても異なってもよい。Ａｒ_３、Ａｒ_４は置換もしくは無置換のアリール基を表わし、同一であっても異なってもよい。Ｘは単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わす。Ｚは置換もしくは無置換のアルキレン基、置換もしくは無置換のアルキレンエーテル２価基、アルキレンオキシカルボニル２価基を表わす。ｍ、ｎは０〜３の整数を表わす。｝」
（１２）「前記保護層に用いられる１官能の電荷輸送性構造を有するラジカル重合性化合物が、下記一般式（３）の少なくとも一種以上であることを特徴とする前記第（１０）項又は第（１１）項に記載の画像形成装置；

{In the formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), halogen Carbonyl group or CONR ₈ R ₉ (R ₈ and R ₉ may have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Represents a good aryl group, which may be the same or different from each other, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group, which may be the same or different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group. m and n represent an integer of 0 to 3. }
(12) The item (10) or the item wherein the radical polymerizable compound having a monofunctional charge transporting structure used in the protective layer is at least one of the following general formula (3): (11) The image forming apparatus according to item

（式中、ｏ、ｐ、ｑはそれぞれ０又は１の整数、Ｒａは水素原子、メチル基を表わし、Ｒｂ、Ｒｃは水素原子以外の置換基で炭素数１〜６のアルキル基を表わし、複数の場合は異なっても良い。ｓ、ｔは０〜３の整数を表わす。Ｚａは単結合、メチレン基、エチレン基、

(Wherein, o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, Rb and Rc represent a substituent other than a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, And s and t each represents an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,

を表わす。）」
（１３）「前記保護層の硬化手段が加熱又は光エネルギー照射手段であることを特徴とする前記第（１０）項乃至第（１２）項の何れかに記載の画像形成装置」
（１４）「前記中間層が電荷ブロッキング層とモアレ防止層から構成され、窒素ドープ酸化チタンがモアレ防止層に含有されることを特徴とする前記第（１）項乃至第（１３）項の何れかに記載の画像形成装置」
（１５）「前記電荷ブロッキング層が絶縁性材料からなり、その膜厚が２．０μｍ未満、０．３μｍ以上であることを特徴とする前記第（１４）項に記載の画像形成装置」
（１６）「前記絶縁性材料が、Ｎ−メトキシメチル化ナイロンであることを特徴とする前記第（１５）項に記載の画像形成装置」
（１７）「前記モアレ防止層が窒素ドープ酸化チタンとバインダー樹脂を含有し、両者の容積比が１／１乃至３／１の範囲であることを特徴とする前記第（１４）項乃至第（１６）項の何れかに記載の画像形成装置」
（１８）「前記静電潜像形成手段に用いられる画像書き込み光の光源波長が、４５０ｎｍよりも短波長の光源であることを特徴とする前記第（１）項乃至第（１７）項の何れかに記載の画像形成装置」
（１９）「少なくとも静電潜像担持体、静電潜像形成手段、現像手段、転写手段、及び除電手段を有する画像形成要素を複数備えたことを特徴とする前記第（１）項乃至第（１８）項の何れかに記載の画像形成装置」
（２０）「静電潜像担持体と、静電潜像形成手段、現像手段、除電手段及びクリーニング手段から選択される１つ以上の手段とが一体となり、装置本体と着脱自在なプロセスカートリッジを搭載していることを特徴とする前記第（１）項乃至第（１９）項の何れかに記載の画像形成装置」
（２１）「静電潜像担持体上に静電潜像を形成する静電潜像形成工程と、該静電潜像をトナーを用いて現像して可視像を形成する現像工程と、該可視像を記録媒体に転写する転写工程と、記録媒体に転写された転写像を定着させる定着工程と、静電潜像担持体の残留電荷を光除電する除電工程とを少なくとも有する画像形成方法であって、前記静電潜像担持体が、支持体と、該支持体上に少なくとも中間層、電荷発生層と電荷輸送層とからなる感光層を有し、該中間層に少なくとも窒素ドープ酸化チタンを含有し、かつ該電荷発生層中に有機電荷発生物質を含有すると共に、前記除電工程が５００ｎｍよりも短波長の光を照射する除電工程であることを特徴とする画像形成方法」
（２２）「前記静電潜像形成工程に用いられる画像書き込み光の光源波長が、４５０ｎｍよりも短波長の光源であることを特徴とする前記第（２１）項に記載の画像形成方法」
（２３）「少なくとも静電潜像形成工程、現像工程、転写工程、及び除電工程を有する画像形成工程を複数備えたことを特徴とする前記第（２１）項又は第（２２）項に記載の画像形成方法」

Represents. ) "
(13) “The image forming apparatus according to any one of (10) to (12), wherein the curing unit of the protective layer is a heating or light energy irradiation unit”
(14) Any one of the above items (1) to (13), wherein the intermediate layer includes a charge blocking layer and a moire preventing layer, and nitrogen-doped titanium oxide is contained in the moire preventing layer. Image forming apparatus according to
(15) “The image forming apparatus according to (14), wherein the charge blocking layer is made of an insulating material, and the film thickness is less than 2.0 μm and 0.3 μm or more”.
(16) “Image forming apparatus according to item (15), wherein the insulating material is N-methoxymethylated nylon”
(17) The above (14) to ((1), wherein the moire prevention layer contains nitrogen-doped titanium oxide and a binder resin, and the volume ratio of the two is in the range of 1/1 to 3/1. The image forming apparatus according to any one of Items 16) "
(18) Any of the above-mentioned items (1) to (17), wherein the light source wavelength of the image writing light used for the electrostatic latent image forming unit is a light source having a wavelength shorter than 450 nm. Image forming apparatus according to
(19) The items (1) to (1), wherein a plurality of image forming elements each having at least an electrostatic latent image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, and a charge eliminating unit are provided. The image forming apparatus according to any one of items (18) "
(20) “An electrostatic latent image carrier and at least one means selected from an electrostatic latent image forming means, a developing means, a charge eliminating means, and a cleaning means are integrated to form a process cartridge that is detachable from the apparatus main body. The image forming apparatus according to any one of (1) to (19), wherein the image forming apparatus is mounted.
(21) “An electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier, and a developing step of developing the electrostatic latent image with toner to form a visible image; Image formation having at least a transfer step for transferring the visible image to a recording medium, a fixing step for fixing the transferred image transferred to the recording medium, and a static elimination step for photostatic elimination of residual charges on the electrostatic latent image carrier The electrostatic latent image carrier has a support and a photosensitive layer comprising at least an intermediate layer, a charge generation layer and a charge transport layer on the support, and the intermediate layer has at least nitrogen doping. An image forming method characterized in that it contains titanium oxide and contains an organic charge generation material in the charge generation layer, and the charge removal step is a charge removal step of irradiating light having a wavelength shorter than 500 nm.
(22) “Image forming method according to item (21), wherein the light source wavelength of the image writing light used in the electrostatic latent image forming step is a light source having a wavelength shorter than 450 nm”
(23) In the above (21) or (22), the apparatus includes a plurality of image forming processes including at least an electrostatic latent image forming process, a developing process, a transferring process, and a charge eliminating process. Image Forming Method "

  According to the inventor's study, when the irradiation light at the time of static elimination is finely decomposed, the increase in the residual potential can be suppressed as the intermediate layer (nitrogen-doped titanium oxide) is irradiated with light of a wavelength that can be absorbed. I understood. Furthermore, when long-wavelength light (light of 500 nm or more) that cannot be absorbed by the intermediate layer (nitrogen-doped titanium oxide) was mixed, an increase in residual potential was observed according to the amount of long-wavelength light mixed. Therefore, the methods described in Patent Documents 1 to 14 are still inadequate as a technique for suppressing the increase in residual potential in consideration of high durability and high image quality.

In the present invention, as the charge eliminating light, the wavelength that can be absorbed by nitrogen-doped titanium oxide corresponds to the width of the forbidden band of nitrogen-doped titanium oxide (also referred to as an energy gap or a band gap between the conduction band and the valence band). It is defined as a wavelength (short wavelength) having energy larger than energy. That is, in the case of nitrogen-doped titanium oxide, the energy gap is approximately 2.4 eV, which is approximately 520 nm when converted into a wavelength. This is the wavelength on the longest wavelength side that can be absorbed by nitrogen-doped titanium oxide, and light with a wavelength shorter than 520 nm can be absorbed by nitrogen-doped titanium oxide.
In addition, the neutralization light having a wavelength shorter than 500 nm as the neutralization light in the present invention indicates that the light does not include light on the long wavelength side of 500 nm or longer (hereinafter referred to as the neutralization light of less than 500 nm). There is).
As described above, the wavelength at which nitrogen-doped titanium oxide can be absorbed is defined as a wavelength larger than the energy gap. A method for measuring this energy gap will be described. In general, there are three methods.
One is a method of obtaining the absorption edge on the long wavelength side by measuring the spectral reflection spectrum of the intermediate layer. This can be easily measured with a commercially available spectral absorption spectrum apparatus. This measurement is used in the embodiments of the present invention. The wavelength that can be absorbed by the intermediate layer is obtained as light having a shorter wavelength than the absorption edge obtained by this method.
Second, the spectral absorption spectrum and the emission spectrum of the intermediate layer are obtained and described in the same graph, and the intersection of the two (the long wavelength side tail of the spectral absorption spectrum curve and the short wavelength side tail of the emission spectrum curve). This is a method for obtaining the wavelength at the point of intersection. These can be measured with a commercially available spectrophotometer and fluorometer. The wavelength that can be absorbed by the intermediate layer is determined as light having a shorter wavelength than the wavelength (intersection) determined by this method.
Third, the energy level of the conduction band and the valence band is measured, and the difference between the two is obtained as the energy gap. These require dedicated measurement equipment and are not very common. The wavelength that can be absorbed by the intermediate layer is obtained as light on the shorter wavelength side than the wavelength by converting the energy gap (unit is energy) into a wavelength unit.

It has not been clarified in detail how the residual potential increase in the repeated use of the photosensitive member can be suppressed by using the neutralizing light having a wavelength that can be absorbed by the nitrogen-doped titanium oxide. At present, the mechanism is considered as follows.
In the repeated use of the photoconductor, if the charge is removed by light having a wavelength longer than the wavelength that can be absorbed by the nitrogen-doped titanium oxide, all the photocarriers generated by the photoconductor are generated in the charge generation layer. At this time, holes are injected into the charge transport layer and electrons are injected into the intermediate layer and transported to the surface of the photoreceptor or the conductive support, respectively, and surface charge or induced charge (charge induced on the support side during main charging). Cancel. In a high-speed process as the object of the present invention, electron transport in the intermediate layer is inferior to hole transport in the charge transport layer (for example, the number of generated electron capture centers (electron trap sites) is large and Because the annihilation rate is slow or the pn junction for the rectification at the interface is thermally disturbed, etc., electrons are accumulated in the intermediate layer with repeated use.

  On the other hand, when charge removal is performed with light having a wavelength that can be absorbed by nitrogen-doped titanium oxide, photocarriers are also generated in the charge generation layer, but the charge generation layer does not absorb 100% of the charge removal light. The static elimination light also reaches the layer. When this static elimination light is light having a wavelength shorter than the wavelength that can be absorbed by nitrogen-doped titanium oxide, the nitrogen-doped titanium oxide contained in the intermediate layer absorbs light and passes through a photoexcited state to generate a photocarrier. Is generated. In this case, since it is formed by the intermediate layer, there is no injection process from the charge generation layer, so that the efficiency is high. In this way, the photocarrier generated in the intermediate layer can suppress the residual potential increase by canceling the residual charges (electrons) accumulated until the previous image formation.

The nitrogen-doped titanium oxide used in the present invention is present in the form of TiO _{2 -X} N _X by adding nitrogen to titanium oxide. x is preferably 0.001 or more and 0.1 or less. The feature of this material is that the absorption wavelength is increased while maintaining the photocatalytic performance of titanium oxide. In general titanium oxide, for example, rutile type titanium oxide, the absorption edge (absorption on the longest wavelength side that can be absorbed) is approximately 410 nm, and in anatase type titanium oxide, it is 380 nm. In contrast, the absorption of nitrogen-doped titanium oxide extends to approximately 520 nm.
In the present invention, light is absorbed in the nitrogen-doped titanium oxide contained in the intermediate layer to generate carriers. Therefore, as the absorption is on the longer wavelength side, the selectivity of the light source becomes very advantageous. .

  In addition, organic charge generation materials generally used in the charge generation layer have absorption in the visible range, so that the neutralization light of less than 500 nm is transmitted at a certain rate, and the intermediate layer reaches the amount of light necessary for carrier generation. To do. However, organic charge generating materials cannot be said to have no absorption at less than 500 nm due to their structure, and photocarriers can be sufficiently generated even with static elimination light of less than 500 nm. For this reason, in the charge generation layer, it is possible to secure the same amount of photocarrier generation as that of charge removal by ordinary charge removal light (exposure of 500 nm or more), and it does not adversely affect the light charge removal itself.

In order to sufficiently exhibit such an effect, it is necessary that the static elimination light sufficiently reaches at least the intermediate layer of the photoreceptor. For this purpose, the charge generation layer and the charge transport layer installed on the upper layer of the intermediate layer need to sufficiently transmit static elimination light of less than 500 nm.
Among the materials that have been usefully used as charge transport materials for electrophotographic photoreceptors so far, materials that absorb light of less than 500 nm are also included. For this reason, when such a material is used, the effect of the present invention may not be sufficiently obtained. Even if the material sufficiently transmits light of less than 500 nm, the stability of the electrostatic characteristics of the photoreceptor in repeated use cannot be ensured unless the ability as a charge transport material is sufficient.

For this reason, the characteristics required for the charge transport material used in the present invention are as follows: (1) The charge transport layer is sufficiently formed to transmit a static elimination light of less than 500 nm. It is desirable to transmit at least 30% of lightning. (2) Good matching with organic charge generation materials, specifically, good energy matching and smooth injection of photocarriers generated in the charge generation layer. (3) exhibiting stability as a material in repeated use of a photoreceptor, specifically, having resistance to an oxidizing gas generated by a charging means, and being stable against long-term energization There are some things.
By adopting a configuration that satisfies the above-described conditions, the effect of the present invention becomes more remarkable.

  According to the present invention, there is provided an image forming apparatus capable of solving various problems in the prior art and capable of forming a high-durability and high-quality image, an intermediate layer containing at least nitrogen-doped titanium oxide, a charge generation layer, and charge transport Nitrogen-doped titanium oxide containing an organic charge generating substance in a charge generation layer in an electrostatic latent image carrier having a laminated photosensitive layer composed of layers, and having a wavelength shorter than 500 nm in a static elimination light source and contained in an intermediate layer Is an image forming apparatus using a light source having a wavelength that can be absorbed. Accordingly, it is possible to provide an image forming apparatus and an image forming method capable of outputting a stable image with high durability and few abnormal images.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention has an electrostatic latent image having a laminated photosensitive layer comprising an intermediate layer containing nitrogen-doped titanium oxide, a charge generation layer containing an organic charge generation material, and a charge transport layer on at least a conductive support. It comprises at least an image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, a fixing unit, and a charge eliminating unit having a light source having a wavelength shorter than 500 nm, and further selected as necessary. Other means such as cleaning means, recycling means, control means, and the like.

The image forming method of the present invention comprises at least an electrostatic latent image forming step, a developing step, a transfer step, a static elimination step having a light source having a wavelength shorter than 500 nm, and a fixing step, and further if necessary. Other processes appropriately selected, for example, a cleaning process, a recycling process, a control process, and the like are included.
The image forming method of the present invention can be preferably carried out by the image forming apparatus of the present invention, the electrostatic latent image forming step can be performed by the electrostatic latent image forming means, and the developing step is the developing. The transfer step can be performed by the transfer unit, the neutralization step can be performed by the neutralization unit, the fixing step can be performed by the fixing unit, and the other steps. Can be performed by the other means.

  An image forming apparatus according to the present invention includes an electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and the electrostatic latent image using toner. Developing means for developing a visible image by development, transfer means for transferring the visible image to a recording medium, charge eliminating means for removing charges remaining on the electrostatic latent image carrier, and transfer to the recording medium At least a fixing unit for fixing the transferred image, and the static eliminator irradiates the electrostatic latent image carrier with static elimination light by a light source having a light source having a wavelength shorter than 500 nm.

-Electrostatic latent image carrier-
The latent electrostatic image bearing member has a material, shape, structure, and size, except that the intermediate layer contains nitrogen-doped titanium oxide and the charge generation layer contains an organic charge generation material. , Etc. are not particularly limited, and can be appropriately selected from known ones. As the support, a conductive support having conductivity is preferable.

Next, the electrophotographic photosensitive member used in the present invention will be described in detail with reference to the drawings.
FIG. 2 is a cross-sectional view showing a structural example of the electrophotographic photosensitive member used in the present invention. On the support (31), an intermediate layer (39) containing nitrogen-doped titanium oxide and at least as a charge generating substance are used. A charge generation layer (35) mainly composed of an organic charge generation material and a charge transport layer (37) mainly composed of a charge transport material are laminated.

  FIG. 3 is a cross-sectional view showing another structural example of the electrophotographic photosensitive member used in the present invention, in which the intermediate layer (39) includes a charge blocking layer (43) and a moire prevention layer (45 containing nitrogen-doped titanium oxide). And a charge generation layer (35) mainly composed of at least an organic charge generation material as a charge generation material and a charge transport layer (37) mainly composed of a charge transport material are laminated on the intermediate layer. The structure is taken.

  FIG. 4 is a sectional view showing still another structural example of the electrophotographic photosensitive member used in the present invention. On the support (31), the intermediate layer (39) containing nitrogen-doped titanium oxide and the charge are shown. A charge generation layer (35) having at least an organic charge generation material as a main component as a generation material and a charge transport layer (37) having a charge transport material as a main component are laminated, and further on the charge transport layer (photosensitive layer). The structure which provided the protective layer (41) is taken.

As the conductive support (31), a material having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, oxidation Metal oxide such as indium by vapor deposition or sputtering, film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel plates, etc. and methods such as extrusion and drawing After forming the tube, it is possible to use a tube subjected to surface treatment such as cutting, superfinishing or polishing. Endless nickel belts and endless stainless steel belts can also be used as the conductive support.

  In addition, the conductive support dispersed in a suitable binder resin on the support can be used as the conductive support of 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. It is done. 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 resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  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 conductive support of the present invention.

  Of these, a cylindrical support made of aluminum, which can be easily subjected to the anodic oxide film treatment, can be most preferably used. As used herein, aluminum includes both pure aluminum and aluminum alloys. Specifically, JIS 1000 series, 3000 series, and 6000 series aluminum or aluminum alloy is most suitable. Anodized films are obtained by anodizing various metals and various alloys in an electrolyte solution. Among them, a film called anodized aluminum or an aluminum alloy that has been anodized in an electrolyte solution is used in the present invention. Is the most suitable. In particular, it is excellent in preventing point defects (black spots, background stains) that occur when used in reversal development (negative and positive development).

The anodizing treatment is performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid. Of these, treatment with a sulfuric acid bath is most suitable. For example, sulfuric acid concentration: 10 to 20%, bath temperature: 5 to 25 ° C., current density: 1 to 4 A / dm ² , electrolytic voltage: 5 to 30 V, treatment time: treatment in the range of about 5 to 60 minutes However, the present invention is not limited to this. Since the anodic oxide film produced in this way is porous and has high insulation, the surface is very unstable. For this reason, there is a change with time after fabrication, and the physical property value of the anodized film is likely to change. In order to avoid this, it is preferable to further seal the anodized film. Examples of the sealing treatment include a method of immersing the anodized film in an aqueous solution containing nickel fluoride and nickel acetate, a method of immersing the anodized film in boiling water, and a method of treating with pressurized steam. Among these, the method of immersing in the aqueous solution containing nickel acetate is the most preferable. Subsequent to the sealing treatment, the anodic oxide film is washed. The main purpose of this is to remove excess metal salts and the like attached by the sealing treatment. If this remains excessively on the surface of the support (anodized film), it not only adversely affects the quality of the coating film formed on this surface, but also generally low resistance components remain, resulting in the occurrence of soiling. It can also be a cause. Cleaning may be performed with pure water only once, but usually, multistage cleaning is performed. At this time, it is preferable that the final cleaning liquid is as clean as possible (deionized). Moreover, it is preferable to perform physical rubbing cleaning with a contact member in one of the multi-stage cleaning processes. The thickness of the anodized film formed as described above is preferably about 5 to 15 μm. If it is too thin, the barrier effect as an anodic oxide film is not sufficient, and if it is too thick, the time constant as an electrode becomes too large, resulting in the generation of residual potential and the response of the photoreceptor. There is a case.

  Next, the intermediate layer (39) will be described. It is essential that the intermediate layer used in the present invention contains nitrogen-doped titanium oxide. The intermediate layer generally contains a resin as a main component, but these resins are preferably resins having a high solvent resistance with respect to a general organic solvent in consideration of applying a photosensitive layer thereon with a solvent. . Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin.

Further, the intermediate layer contains nitrogen-doped titanium oxide for the purpose of reducing the residual potential, etc., but this also has the effect of preventing moire. The absorption wavelength range of nitrogen-doped titanium oxide varies depending on the impurities contained, crystal type, and the like. Therefore, the energy gap of the material to be used or the intermediate layer using the same is actually measured by the method described above.
The absorption edge wavelength obtained from the energy gap of the nitrogen-doped titanium oxide effectively used in the present invention (the long wavelength edge that can be absorbed if the light is shorter than this) is about 520 nm. As described above, these values are only reference values, and these values vary depending on the amount of impurities and crystal type of the material used.

  Further, the nitrogen-doped titanium oxide to be used is advantageously not subjected to surface treatment. This is because the surface treatment reduces the surface area of the unmodified nitrogen-doped titanium oxide, which acts in a disadvantageous direction when transporting carriers generated from the nitrogen-doped titanium oxide. Thereby, the effect of this invention may be reduced. If surface treatment is desired for reasons such as dispersion stability, the minimum amount should be used.

These intermediate layers can be formed by using an appropriate solvent and coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the intermediate layer of the present invention. The thickness of the intermediate layer is suitably from 0.1 to 5 μm.
In addition to the generation of photocarriers during static elimination, the intermediate layer has a function to prevent injection of reverse polarity charges induced on the electrode side when the photosensitive member is charged into the photosensitive layer, and during writing with coherent light such as laser light. It has at least two functions of preventing the generated moire. A function separation type intermediate layer in which this function is separated into two or more layers is an effective means for the photoreceptor used in the present invention. The function-separated intermediate layer of the charge blocking layer (43) and the moire prevention layer (45) will be described below.

  The charge blocking layer (43) is a layer having a function of preventing the reverse polarity charge induced in the electrode (conductive support (31)) during charging of the photosensitive member from being injected into the photosensitive layer from the support. . In the case of negative charging, it has a function of preventing hole injection, and in the case of positive charging, it has a function of preventing electron injection. The charge blocking layer includes an anodized film typified by an aluminum oxide layer, an inorganic insulating layer typified by SiO, a layer formed from a glassy network of metal oxide, a layer made of polyphosphazene, an aminosilane reaction A layer made of a product, a layer made of an insulating binder resin, a layer made of a curable binder resin, and the like can be given. Among them, a layer composed of an insulating binder resin or a curable binder resin that can be formed by a wet coating method can be used favorably. Since the charge blocking layer is formed by laminating a moiré preventing layer and a photosensitive layer thereon, when these are provided by a wet coating method, the charge blocking layer must be composed of a material or a structure that does not attack the coating film by these coating solvents. Is essential.

Examples of the binder resin that can be used include thermoplastic resins such as polyamide, polyester, vinyl chloride-vinyl acetate copolymer, and thermosetting resins such as active hydrogen (-OH group, -NH ₂ group, -NH group, etc. ) And a compound containing a plurality of isocyanate groups and / or a compound containing a plurality of epoxy groups can be used. In this case, examples of the compound containing a plurality of active hydrogens include acrylic resins containing active hydrogen such as polyvinyl butyral, phenoxy resin, phenol resin, polyamide, polyester, polyethylene glycol, polypropylene glycol, polybutylene glycol, and hydroxyethyl methacrylate groups. Based resins and the like. Examples of the compound containing a plurality of isocyanate groups include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and their prepolymers. Examples of the compound having a plurality of epoxy groups include bisphenol A type epoxy resins. Can be mentioned. Among these, polyamide is most preferably used from the viewpoint of film formability, environmental stability, solvent resistance, and the like. Among polyamides, N-methoxymethylated nylon is most suitable. N-methoxymethylated nylon can be obtained by modifying a polyamide containing polyamide 6 as a constituent component, for example, by a method proposed by TLCairns (J. Am. Chem. Soc. 71. P651 (1949)). . N-methoxymethylated nylon is obtained by replacing the amide bond hydrogen of the original polyamide with a methoxymethyl group. This substitution rate can be selected in a wide range depending on the modification conditions, but it is preferably 15 mol% or more from the viewpoint of environmental stability because it suppresses the hygroscopicity of the intermediate layer to some extent, has excellent alcohol affinity. More preferably, the substitution rate is 35 mol% or more. Also, as the degree of amide substitution (N-N-methoxymethylation) increases, the alcoholic solvent affinity increases, but the influence of the bulk side chain groups around the main chain becomes stronger, and the main chain is in a relaxed state or main chain. Because the coordination state between the chain and the main chain changes, the hygroscopicity also increases, the crystallinity decreases, the melting point decreases, and the mechanical strength and elastic modulus decrease. Therefore, the substitution rate is 85 mol. % Or less is preferable. More preferably, the substitution rate is 70 mol% or less. Further, according to the examination results, nylon 6 is most preferable as nylon, then nylon 66 is preferable, and conversely, a copolymer nylon such as nylon 6/66/610 is disclosed in JP-A-9-265202. Contrary to the contents, it was not very preferable.

In addition, a thermosetting resin obtained by thermally polymerizing an oil-free alkyd resin and an amino resin such as a butylated melamine resin, a polyurethane having an unsaturated bond, a resin having an unsaturated bond such as an unsaturated polyester, and thioxanthone A photocurable resin such as a combination with a photopolymerization initiator such as a methyl compound or methylbenzyl formate can also be used as the binder resin.
Further, a function such as suppression of charge injection from the substrate may be provided by adding a conductive polymer having a rectifying property or an acceptor (donor) resin or compound in accordance with the charging polarity.
The film thickness of the charge blocking layer is 0.1 μm or more and less than 2.0 μm, preferably about 0.3 μm or more and less than 2.0 μm. When the charge blocking layer becomes thick, the residual potential increases remarkably at low temperature and low humidity due to repeated charging and exposure, and when the film thickness is too thin, the blocking effect is reduced. Add chemicals, solvents, additives, curing accelerators, etc. necessary for curing (crosslinking), and apply to the substrate by conventional methods such as blade coating, dip coating, spray coating, beat coating, and nozzle coating. It is formed. After the coating, it is dried or cured by a curing process such as drying, heating, or light.

  The moire prevention layer (45) is a layer having a function of preventing the generation of a moire image due to light interference inside the photosensitive layer when writing with coherent light such as laser light. When the intermediate layer has a function separation type structure, nitrogen-doped titanium oxide is included in the moire prevention layer, and the moire prevention layer has a function of generating a photocarrier during static elimination. Basically, it has a function of causing light scattering of the writing light. In order to exhibit such a function, it is effective that the anti-moire layer has a material having a large refractive index.

In the case where the intermediate layer is composed of a charge blocking layer and a moiré preventing layer, the effect is further enhanced by making the moiré preventing layer in contact with the charge generation layer, and the most effective photosensitive layer. Body composition.
In addition, in the photoreceptor having the function separation type intermediate layer, the charge blocking layer prevents the charge injection from the support (31). Therefore, in the moire preventing layer, at least the charge charged on the photoreceptor surface is From the viewpoint of preventing residual potential, it is preferable to have a function of moving charges of the same polarity. For this reason, for example, in the case of a negatively charged type photoreceptor, it is desirable to impart electronic conductivity to the moire prevention layer, and the nitrogen-doped titanium oxide to be used may be one having electron conductivity or a conductive one. It is desirable to use it. Alternatively, the use of an electron conductive material (for example, an acceptor) or the like for the moire preventing layer makes the effect of the present invention more remarkable.

  As the binder resin, the same resin as the charge blocking layer can be used. However, in consideration of laminating a photosensitive layer (a charge generation layer (35), a charge transport layer (37)) on the moire prevention layer, the photosensitive layer ( It is important that the coating solvent for the charge generation layer and the charge transport layer is not affected by the coating solvent.

  A thermosetting resin is preferably used as the binder resin. In particular, alkyd / melamine resin mixtures are best used. At this time, the mixing ratio of the alkyd / melamine resin is an important factor that determines the structure and characteristics of the moire prevention layer. A range in which the ratio (weight ratio) between the two is 5/5 to 8/2 can be cited as a good mixing ratio range. When the melamine resin is richer than 5/5, volume shrinkage is increased during thermosetting, and coating film defects are likely to occur, or the residual potential of the photoreceptor is increased. If the alkyd resin is richer than 8/2, it is effective in reducing the residual potential of the photoconductor, but it is not desirable because the bulk resistance becomes too low and the soiling becomes worse.

  In the anti-moire layer, the volume ratio of nitrogen-doped titanium oxide and binder resin determines an important characteristic. For this reason, it is important that the volume ratio of the nitrogen-doped titanium oxide and the binder resin is in the range of 1/1 to 3/1. When the volume ratio of the two is less than 1/1, not only the moire prevention ability is lowered, but there is a case where the increase of the residual potential in repeated use becomes large. On the other hand, in the region where the volume ratio exceeds 3/1, not only the binding ability of the binder resin is inferior, but also the surface property of the coating film is deteriorated, which may adversely affect the film forming property of the upper photosensitive layer. This effect can be a serious problem when the photosensitive layer is a laminated type and a thin layer such as a charge generation layer is formed. When the volume ratio exceeds 3/1, there may be a case where the binder resin cannot completely cover the surface of the nitrogen-doped titanium oxide. The direct contact with the charge generation material increases the probability of heat carrier generation, May have an adverse effect on dirt. Here, the volume ratio is calculated by setting the true specific gravity of nitrogen-doped titanium oxide to 4.0, and the volume ratio of the binder resin is calculated using the density of the catalog value. From the weight ratio of the two, the volume ratio was converted using the above specific gravity to obtain the ratio of the two.

  Furthermore, by using two types of nitrogen-doped titanium oxide having different average particle diameters for the moire prevention layer, it is possible to improve the concealing power on the conductive substrate and suppress moire and to cause abnormal images. Can be eliminated. For this purpose, it is important that the ratio of the average particle diameters of the two types of nitrogen-doped titanium oxide used is within a certain range (0.2 <D2 / D1 ≦ 0.5). In the case of the particle size ratio outside the range specified in the present invention, that is, the average particle size (D2) of the other nitrogen-doped titanium oxide (T2) with respect to the average particle size (D1) of the nitrogen-doped titanium oxide (T1) having a large average particle size. ) Ratio is too small (0.2 ≧ D2 / D1), the activity on the surface of the nitrogen-doped titanium oxide is increased and the electrostatic stability of the electrophotographic photosensitive member is significantly impaired. When the ratio of the average particle diameter of the other nitrogen-doped titanium oxide (T2) to the average particle diameter of one nitrogen-doped titanium oxide (T1) is too large (D2 / D1> 0.5), The concealing power is reduced, and the suppression of moiré and abnormal images is reduced. The average particle size mentioned here is obtained from a particle size distribution measurement obtained when strong dispersion is performed in an aqueous system.

  The average particle size (D2) of the nitrogen-doped titanium oxide (T2) having a smaller particle size is an important factor, and it is important that 0.05 μm <D2 <0.20 μm. When the thickness is 0.05 μm or less, the hiding power is reduced, and moire may be generated. On the other hand, in the case of 0.20 μm or more, the filling rate of the nitrogen-doped titanium oxide in the moire preventing layer is lowered, and the effect of suppressing soiling cannot be sufficiently exhibited.

  The mixing ratio (weight ratio) of the two types of nitrogen-doped titanium oxide is also an important factor. When T2 / (T1 + T2) is smaller than 0.2, the filling rate of nitrogen-doped titanium oxide is not so large, and the effect of suppressing soiling cannot be sufficiently exhibited. On the other hand, when it is larger than 0.8, the concealing power is reduced, and moire may be generated. Therefore, it is important that 0.2 ≦ T2 / (T1 + T2) ≦ 0.8.

  The thickness of the moire preventing layer is 1 to 10 μm, preferably 2 to 5 μm. If the film thickness is less than 1 μm, the effect is small and if it exceeds 10 μm, residual potential is accumulated, which is not desirable.

  Nitrogen-doped titanium oxide is dispersed together with a solvent and a binder resin by a conventional method, for example, a ball mill, a sand mill, an attrier, etc. In addition, it is formed on the substrate by a blade coating method, a dip coating method, a spray coating method, a beat coating method, a nozzle coating method, or the like by a conventional method. After the coating, it is dried or cured by a curing process such as drying, heating, or light.

Next, the photosensitive layer will be described. The photosensitive layer has a laminated structure of a charge generation layer (35) containing an organic charge generation material as a charge generation material and a charge transport layer (37) containing a charge transport material as a main component.
The charge generation layer (35) is a layer mainly composed of an organic charge generation material as a charge generation material. The organic charge generating material is formed by dispersing the organic charge generating material in a suitable solvent together with a binder resin, if necessary, using a ball mill, attritor, sand mill, ultrasonic wave, etc., applying this onto the intermediate layer, and drying.

  The binder resin used in the charge generation layer as necessary includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, and poly-N-vinyl. Examples include carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, and the like. . 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.

  Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. As a coating method for the coating solution, a dip coating method, spray coating, beat coating, nozzle coating, spinner coating, ring coating, or the like can be used. The film thickness of the charge generation layer is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.

An organic charge generation material can be used as the charge generation material.
A known material can be used as the organic charge generating substance. 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 triphenylamine skeleton, azo pigments having a diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.

Among these, azo pigments represented by the following formula (I) are effectively used. In particular, an asymmetric azo pigment in which Cp ₁ and Cp ₂ of the azo pigment are different from each other has high carrier generation efficiency and can be effectively used as the charge generation material of the present invention.

（式中、Ｃｐ_１，Ｃｐ_２はカップラー残基を表わす。Ｒ_２０１，Ｒ_２０２はそれぞれ、水素原子、ハロゲン原子、アルキル基、アルコキシ基、シアノ基のいずれかを表わし、同一でも異なっていても良い。またＣｐ_１，Ｃｐ_２は下記（II）式で表わされ、

(In the formula, Cp ₁ and Cp ₂ represent a coupler residue. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, which may be the same or different. Cp ₁ and Cp ₂ are represented by the following formula (II):

式中、Ｒ_２０３は、水素原子、メチル基、エチル基などのアルキル基、フェニル基などのアリール基を表わす。Ｒ_２０４，Ｒ_２０５，Ｒ_２０６，Ｒ_２０７，Ｒ_２０８はそれぞれ、水素原子、ニトロ基、シアノ基、フッ素、塩素、臭素、ヨウ素などのハロゲン原子、トリフルオロメチル基等のハロゲン化アルキル基、メチル基、エチル基などのアルキル基、メトキシ基、エトキシ基などのアルコキシ基、ジアルキルアミノ基、水酸基を表わし、Ｚは置換もしくは無置換の芳香族炭素環または置換もしくは無置換の芳香族複素環を構成するのに必要な原子群を表わす。

In the formula, R ₂₀₃ represents a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, or an aryl group such as a phenyl group. R ₂₀₄ , R ₂₀₅ , R ₂₀₆ , R ₂₀₇ and R ₂₀₈ are each a hydrogen atom, a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, bromine or iodine, a halogenated alkyl group such as a trifluoromethyl group, methyl Represents an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, a dialkylamino group or a hydroxyl group, and Z constitutes a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring It represents the atomic group necessary to do.

  In addition, titanyl phthalocyanine can be effectively used as the charge generating material of the present invention. Among them, a titanyl phthalocyanine crystal 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 1.542 mm) of CuKα, among them, 27.2 ° It has a maximum diffraction peak, further has main peaks at 9.4 °, 9.6 °, and 24.0 °, and has a peak at 7.3 ° as the lowest diffraction peak, The titanyl phthalocyanine crystal having no peak between the peak at 3 ° and the peak at 9.4 ° and further having no peak at 26.3 ° has a large carrier generation efficiency, and is used as the charge generation material of the present invention. Can be used effectively.

  In the organic charge generating material contained in the electrophotographic photosensitive member of the present invention, the effect is expressed by making the particle size of the charge generating material finer, and the average particle size is 0.25 μm or less. Preferably, 0.2 μm or less is more preferable. The manufacturing method is shown below. A method for controlling the particle size of the charge generating material contained in the photosensitive layer is a method of removing coarse particles larger than 0.25 μm after dispersing the charge generating material.

  The average particle size referred to here is a volume average particle size, and is determined by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba, Ltd.). At this time, the particle diameter (Median diameter) corresponding to 50% of the cumulative distribution was calculated. However, this method may not be able to detect a very small amount of coarse particles. Therefore, in order to obtain more details, it is important to observe the charge generation material powder or dispersion directly with an electron microscope and determine the size. It is.

  As a result of further observation of the dispersion and examination of micro defects, the above phenomenon was understood as follows. Usually, in the method of measuring the average particle size, when an extremely large particle is present in several% or more, the presence can be detected, but it is about 1% or less of the whole. When the amount is too small, the measurement is below the detection limit. As a result, the presence of coarse particles is not detected only by measuring the average particle size, making it difficult to interpret the above minute defects.

FIG. 5 and FIG. 6 show photographs observing the state of two types of dispersions in which the dispersion conditions are fixed and only the dispersion time is changed. A photograph of a dispersion having a short dispersion time under the same conditions is shown in FIG. 5. Compared with FIG. 6 having a long dispersion time, coarse particles remain. The black particles in FIG. 5 are coarse particles.
The average particle size and particle size distribution of these two types of dispersions were measured by a commercially available particle size distribution measuring device (manufactured by Horiba: ultracentrifugal automatic particle size distribution measuring device, CAPA 700). The result is shown in FIG. “A” in FIG. 7 corresponds to the dispersion shown in FIG. 5, and “B” corresponds to the dispersion shown in FIG. When both are compared, there is almost no difference in the particle size distribution. In addition, the average particle diameter values of the two are “A” of 0.29 μm and “B” of 0.28 μm, and taking into account measurement errors, no difference is recognized between the two.
Therefore, it is understood that the remaining of a minute amount of coarse particles cannot be detected only by the definition of the known average particle diameter (particle size), and it is not possible to cope with the recent high-resolution negative / positive development. The presence of such a minute amount of coarse particles can be recognized for the first time by observing the coating solution at the microscope level.

Next, a method of removing coarse particles after dispersing the organic charge generating material will be described.
That is, it is a method in which a dispersion liquid with as fine a particle as possible is prepared and then filtered through an appropriate filter. For the preparation of the dispersion, a general method is used, and the organic charge generating substance is dispersed in a suitable solvent together with a binder resin as necessary by using a ball mill, an attritor, a sand mill, a bead mill, an ultrasonic wave, or the like. It is obtained. At this time, the binder resin may be selected depending on the electrostatic characteristics of the photoreceptor, and the solvent may be selected depending on the wettability to the pigment and the dispersibility of the pigment.

  This method is a very effective means in that it can remove a minute amount of coarse particles that cannot be visually observed (or cannot be detected by particle size measurement), and that the particle size distribution is uniform. Specifically, the dispersion prepared as described above is filtered through a filter having an effective pore size of 5 μm or less, more preferably 3 μm or less, thereby completing the dispersion. Also by this method, a dispersion liquid containing only an organic charge generating substance having a small particle size (0.25 μm or less, preferably 0.2 μm or less) can be produced, and a photoconductor using the dispersion is mounted on an image forming apparatus. By using it, the effect of the present invention becomes more remarkable.

  At this time, when the particle size of the dispersion to be filtered is too large or the particle size distribution is too wide, the loss due to filtration becomes large or the filtration becomes clogged and filtration becomes impossible. There is a case. For this reason, in the dispersion before filtration, it is desirable to perform dispersion until the average particle size reaches 0.3 μm or less and the standard deviation reaches 0.2 μm or less. When the average particle size is 0.3 μm or more, the loss due to filtration increases, and when the standard deviation is 0.2 μm or more, there may be a problem that the filtration time becomes very long.

  The charge generation material used in the present invention has an extremely strong intermolecular hydrogen bonding force, which is a feature of the charge generation material exhibiting highly sensitive characteristics. For this reason, the interaction between the dispersed pigment particles is very strong. As a result, the charge generation material particles dispersed by a disperser or the like are very likely to be re-aggregated due to dilution or the like. Such agglomerates can be removed. At this time, since the dispersion is in a thixotropic state, particles having a size smaller than the effective pore size of the filter to be used are removed. Or the liquid which shows structural viscosity can also be changed into the state close | similar to Newton property by a filter process. In this way, the effect of the present invention is remarkably improved by removing the coarse particles of the charge generation material.

  The filter for filtering the dispersion varies depending on the size of coarse particles to be removed, but according to the study by the present inventors, as a photoreceptor used in an electrophotographic apparatus that requires a resolution of about 600 dpi. The presence of coarse particles of at least 3 μm affects the image. Therefore, a filter with an effective pore size of 5 μm or less should be used. More preferably, a filter having an effective pore size of 3 μm or less is used. As for the effective pore size, the finer the particle, the more effective the removal of coarse particles. However, if the particle size is too fine, the necessary pigment particles themselves are also filtered, and therefore there is an appropriate size. In addition, if it is too fine, it takes time for filtration, clogging of the filter, and excessive load is applied when liquid is sent using a pump or the like. As a matter of course, a material having resistance to the solvent used in the dispersion to be filtered is used as the material of the filter used here.

  The charge transport layer (37) is a layer mainly composed of a charge transport material, and is formed by dissolving or dispersing the charge transport material and a binder resin in an appropriate solvent, and applying and drying the solution on the charge generation layer. it can. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.

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

  Examples of the electron transporting material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.

The binder resin is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polychlorinated. Vinylidene, polyarate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, Examples thereof include thermoplastic or thermosetting resins such as alkyd resins.
The amount of the charge transport material is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably about 5 to 100 μm.

  As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used. Among them, the use of a non-halogen solvent is desirable for the purpose of reducing the environmental load. Specifically, cyclic ethers such as tetrahydrofuran, dioxolane and dioxane, aromatic hydrocarbons such as toluene and xylene, and derivatives thereof are preferably used.

  In the present invention, a charge generation layer and a charge transport layer are formed on the intermediate layer. For this reason, unless an appropriate charge transport material is selected, there are cases where the static elimination light does not sufficiently reach the intermediate layer and the static elimination action (photocarrier generation in the intermediate layer) does not work clearly. In addition, there is a case where the charge transport material is easily deteriorated by absorbing the static elimination light, and conversely, a residual potential rise is generated. Therefore, in the case of the above configuration, it is desirable that the transmittance of the charge transport layer with respect to the charge removal light is 30% or more, preferably 50% or more, and more desirably 85% or more.

  In order to make the charge transport layer in such a condition, it is important to select a charge transport material appropriate for the static elimination light and form the charge transport layer. Among the charge transport materials described above, a charge transport material having a triarylamine skeleton is suitable as a charge transport material for use in the photoreceptor of the present invention because it easily transmits static elimination light of less than 500 nm and has high mobility. It is.

  Among charge transport materials having a triarylamine skeleton, charge transport materials represented by the following formula (III) are particularly effectively used.

（式中、Ｒ_３０１、Ｒ_３０３及びＲ_３０４は水素原子、アミノ基、アルコキシ基、チオアルコキシ基、アリールオキシ基、メチレンジオキシ基、無置換のアルキル基、ハロゲン原子又は置換もしくは無置換のアリール基を、Ｒ_３０２は水素原子、アルコキシ基、置換もしくは無置換のアルキル基又はハロゲンを表わす。またｋ、ｌ、ｍ及びｎは１、２、３又は４の整数であり、各々が２、３又は４の整数のときは前記Ｒ_３０１、Ｒ_３０２、Ｒ_３０３及びＲ_３０４は同一でも異なっていてもよい。）

Wherein R ₃₀₁ , R ₃₀₃ and R ₃₀₄ are a hydrogen atom, amino group, alkoxy group, thioalkoxy group, aryloxy group, methylenedioxy group, unsubstituted alkyl group, halogen atom or substituted or unsubstituted aryl. R ₃₀₂ represents a hydrogen atom, an alkoxy group, a substituted or unsubstituted alkyl group or a halogen, and k, l, m and n are integers of 1, 2, 3 or 4, each of which is 2, 3 Or when R is an integer of 4, R ₃₀₁ , R ₃₀₂ , R ₃₀₃ and R ₃₀₄ may be the same or different.)

  In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer. As the plasticizer, those used as general plasticizers such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is suitably about 0 to 30% by weight based on the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 to 0 with respect to the binder resin. 1% by weight is suitable.

  In the electrophotographic photoreceptor of the present invention, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. In recent years, computers have been used on a daily basis, and there is a demand for miniaturization of devices as well as high-speed output by printers. Therefore, by providing a protective layer and improving the durability, it is possible to use the photosensitive member of the present invention with high sensitivity and no abnormal defects.

The effective protective layer used in the present invention is roughly classified into two types. One is a configuration in which a filler is added to the binder resin. The other one uses a cross-linking binder.
First, a configuration in which a filler is added to the protective layer will be described.

  Materials used for the protective layer include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, Polybutylene terephthalate, polycarbonate, polyarylate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polychlorinated Examples thereof include resins such as vinyl, polyvinylidene chloride, and epoxy resin. Of these, polycarbonate or polyarylate can be most preferably used.

Other protective layers include fluorine resins such as polytetrafluoroethylene, silicone resins, and inorganic fillers such as titanium oxide, tin oxide, potassium titanate, and silica for the purpose of improving wear resistance. What disperse | distributed the filler etc. can be added.
Among the filler materials used for the protective layer of the photoreceptor, examples of the organic filler material include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, a-carbon powder, and the like. Metals such as copper, tin, aluminum and indium, silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony, tin doped indium oxide and other metals Inorganic materials such as oxide and potassium titanate can be mentioned. In particular, it is advantageous to use an inorganic material from the viewpoint of the hardness of the filler. In particular, inorganic pigments and metal oxides are preferable, and silica, titanium oxide, and alumina can be used effectively.

  The filler concentration in the protective layer varies depending on the type of filler used and also on the electrophotographic process conditions using the photoconductor, but the ratio of filler to the total solid content on the outermost layer side of the protective layer is preferably 5% by weight or more, preferably It is 10% by weight or more and 50% by weight or less, preferably about 30% by weight or less. Moreover, the volume average particle diameter of the filler to be used is preferably in the range of 0.1 μm to 2 μm, and preferably in the range of 0.3 μm to 1 μm. In this case, if the average particle size is too small, the wear resistance is not sufficiently exhibited, and if it is too large, the surface property of the coating film is deteriorated or the coating film itself cannot be formed.

  In addition, unless otherwise indicated, the average particle diameter of the filler in this invention is a volume average particle diameter, and is calculated | required with the ultracentrifugal automatic particle size distribution measuring apparatus: CAPA-700 (made by Horiba Seisakusho). At this time, the particle diameter (Median diameter) corresponding to 50% of the cumulative distribution was calculated. In addition, it is important that the standard deviation of each particle measured simultaneously is 1 μm or less. If the standard deviation is larger than this, the particle size distribution may be too wide, and the effects of the present invention may not be obtained remarkably.

Further, the pH of the filler used in the present invention greatly affects the resolution and the dispersibility of the filler. One possible reason is that hydrochloric acid or the like remains in the filler, particularly the metal oxide, during production. When the remaining amount is large, the occurrence of image blur is unavoidable, and depending on the remaining amount, the dispersibility of the filler may be affected.
Another reason is due to the difference in chargeability on the surface of the filler, particularly the metal oxide. Usually, particles dispersed in a liquid are charged positively or negatively, and ions having opposite charges gather to try to keep it electrically neutral, and an electric double layer is formed there. The dispersed state of the particles is stabilized. The potential (zeta potential) gradually decreases with increasing distance from the particle, and the potential in a region that is sufficiently away from the particle and electrically neutral is zero. Therefore, the stability increases as the repulsive force of the particles increases due to an increase in the absolute value of the zeta potential, and the particles tend to aggregate and become unstable as they approach zero. On the other hand, the zeta potential varies greatly depending on the pH value of the system, and at a certain pH value, the potential becomes zero and has an isoelectric point. Therefore, the dispersion system is stabilized by increasing the absolute value of the zeta potential as far as possible from the isoelectric point of the system.

In the configuration of the present invention, the filler having a pH at the isoelectric point of at least 5 is preferably from the viewpoint of image blur suppression, and the more basic the filler, the higher the effect. It was confirmed that there was. A filler exhibiting basicity having a high pH at the isoelectric point has a higher zeta potential when the system is acidic, thereby improving dispersibility and its stability.
Here, the pH of the filler in the present invention is the pH value at the isoelectric point from the zeta potential. At this time, the zeta potential was measured with a laser zeta potentiometer manufactured by Otsuka Electronics Co., Ltd.

Furthermore, as the filler that is less likely to cause image blurring, a filler having high electrical insulation (specific resistance is 10 ¹⁰ Ω · cm or more) is preferable, and a filler having a pH of 5 or more or a filler having a dielectric constant of 5 or more. The ones shown can be used particularly effectively. In addition, a filler having a pH of 5 or more or a filler having a dielectric constant of 5 or more can be used alone, or two or more fillers having a pH of 5 or less and a filler having a pH of 5 or more can be mixed. However, it is also possible to use a mixture of two or more fillers having a dielectric constant of 5 or less and fillers having a dielectric constant of 5 or more. Among these fillers, α-type alumina, which has high insulation properties, high thermal stability, and high wear resistance, is a hexagonal close-packed structure, from the viewpoint of suppressing image blur and improving wear resistance. It is particularly useful.

The specific resistance of the filler used in the present invention is defined as follows. Since the specific resistance value of the powder such as the filler varies depending on the filling rate, it is necessary to measure under a certain condition. In the present invention, the specific resistance value of the filler was measured using an apparatus having the same configuration as that of the measuring apparatus disclosed in JP-A-5-113688 (FIG. 1), and this value was used. In the measuring device, the electrode area is 4.0 cm ² . Prior to measurement, a load of 4 kg is applied to one electrode for 1 minute, and the sample amount is adjusted so that the distance between the electrodes is 4 mm. At the time of measurement, the measurement is performed with the weight of the upper electrode (1 kg) loaded, and the applied voltage is measured at 100V. The area above 10 ⁶ Ω · cm was measured with a HIGH RESISTANCE METER (Yokogawa Hewlett Packard), and the area below it was measured with a digital multimeter (Fluk). The specific resistance value thus obtained is defined as the specific resistance value in the present invention.

  The dielectric constant of the filler was measured as follows. Using a cell similar to the measurement of the specific resistance as described above, after applying a load, the capacitance was measured, and the dielectric constant was determined from this. For the measurement of the capacitance, a dielectric loss measuring device (Ando Electric) was used.

Furthermore, these fillers can be surface-treated with at least one surface treatment agent, and it is preferable from the viewpoint of filler dispersibility. Lowering the dispersibility of the filler not only increases the residual potential, but also lowers the transparency of the coating, causes defects in the coating, and lowers the wear resistance. It can develop into a big problem. As the surface treatment agent, a conventionally used surface treatment agent can be used, but a surface treatment agent capable of maintaining the insulating properties of the filler is preferable. For example, titanate coupling agents, aluminum coupling agent, and mixing treatment in the zircoaluminate coupling agent, a higher fatty acid, etc., or these with silane coupling _{agent, Al 2 O 3, TiO 2} , ZrO 2, Silicone, aluminum stearate, or the like, or a mixture thereof is more preferable from the viewpoint of filler dispersibility and image blur. The treatment with the silane coupling agent is strongly influenced by image blur, but the influence may be suppressed by performing a mixing treatment of the surface treatment agent and the silane coupling agent. The surface treatment amount varies depending on the average primary particle size of the filler used, but is preferably 3 to 30 wt%, more preferably 5 to 20 wt%. If the surface treatment amount is less than this, the filler dispersing effect cannot be obtained, and if the surface treatment amount is too much, the residual potential is significantly increased. These filler materials may be used alone or in combination of two or more. The surface treatment amount of the filler is defined by the weight ratio of the surface treatment agent to be used with respect to the filler amount as described above.
These filler materials can be dispersed by using an appropriate disperser. Further, from the viewpoint of the transmittance of the protective layer, it is preferable that the filler used is dispersed to the primary particle level and has less aggregates.

  Further, the protective layer may contain a charge transport material for reducing residual potential and improving responsiveness. As the charge transport material, the materials described in the description of the charge transport layer and known charge transport materials can be used. When a low molecular charge transport material is used as the charge transport material, a concentration gradient in the protective layer may be provided. In order to improve wear resistance, it is an effective means to reduce the concentration of the surface side. The concentration here refers to the ratio of the weight of the low molecular charge transporting material to the total weight of all the materials constituting the protective layer, and the concentration gradient is a gradient that lowers the concentration on the surface side in the above weight ratio. It shows that. The use of a polymer charge transport material is very advantageous in terms of enhancing the durability of the photoreceptor.

In addition, a known polymer charge transport material can also be used as the binder resin for the protective layer. As an effect when this is used, an improvement in wear resistance and an effect of high-speed charge transport can be obtained.
As a method for forming such a protective layer, a normal coating method is employed. In addition, about 0.1-10 micrometers is suitable for the thickness of the protective layer mentioned above.

Next, a protective layer having a crosslinked structure will be described as a binder structure of the protective layer (hereinafter referred to as a crosslinked protective layer).
Regarding the formation of a cross-linked structure, a reactive monomer having a plurality of cross-linkable functional groups in one molecule is used to cause a cross-linking reaction using light or heat energy to form a three-dimensional network structure. is there. This network structure functions as a binder resin and exhibits high wear resistance.

Moreover, it is a very effective means to use a monomer having a charge transporting ability in whole or in part as the reactive monomer. By using such a monomer, a charge transporting site is formed in the network structure, and the function as a protective layer can be sufficiently expressed. A reactive monomer having a triarylamine structure is effectively used as the monomer having charge transporting ability.
The protective layer having such a network structure has high wear resistance, but has a large volume shrinkage during the crosslinking reaction, and if it is too thick, cracks may occur. In such a case, the protective layer may be a laminated structure, and a protective layer of a low molecular dispersion polymer may be used for the lower layer (photosensitive layer side), and a protective layer having a crosslinked structure may be formed on the upper layer (surface side). good.

Among the crosslinked protective layers, a protective layer having the following specific structure is particularly effectively used.
The specific crosslinkable protective layer is a protective layer formed by curing at least a trifunctional or higher functional radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure. It is. Since it has a cross-linked structure obtained by curing a tri- or higher-functional radically polymerizable monomer, a three-dimensional network structure is developed, and a highly hard and highly elastic surface layer with a very high cross-linking density is obtained, and it is uniform and highly smooth. High wear resistance and scratch resistance are achieved. In this way, it is important to increase the crosslink density on the surface of the photoreceptor, that is, the number of crosslink bonds per unit volume. This internal stress increases as the thickness of the crosslinkable protective layer increases. Therefore, when the entire protective layer is cured, cracks and film peeling tend to occur. Even if this phenomenon does not appear initially, it may be likely to occur over time due to repeated use in the electrophotographic process and the influence of charging, development, transfer, cleaning hazards and thermal fluctuations.

  As a method for solving this problem, (1) a polymer component is introduced into the crosslinked layer and the crosslinked structure, (2) a large amount of monofunctional and bifunctional radically polymerizable monomers are used, and (3) a flexible group is introduced. Although the directionality which makes a cured resin layer soft, such as using the polyfunctional monomer which has, is mentioned, the crosslink density of a bridge | crosslinking layer becomes thin in any case, and remarkable wear resistance is not achieved. On the other hand, the photoreceptor of the present invention is preferably provided with a cross-linking protective layer having a high cross-linking density and having a three-dimensional network structure developed on the charge transport layer, preferably with a film thickness of 1 μm or more and 10 μm or less. Cracks and film peeling do not occur, and very high wear resistance is achieved. By making the film thickness of the crosslinkable protective layer 2 μm or more and 8 μm or less, in addition to further improving the margin for the above problem, it is possible to select a material for increasing the crosslink density that leads to further improvement in wear resistance. It becomes possible.

  The reason why the photoconductor of the present invention can suppress cracks and film peeling is that the crosslinkable protective layer can be made thin, so that the internal stress does not increase, and the lower layer has a photosensitive layer or charge transport layer, so that the surface is a crosslinkable protective layer. This is because the internal stress can be relaxed. For this reason, it is not necessary to contain a large amount of polymer material in the crosslinkable protective layer, and the polymer material and radical polymerizable composition (radically polymerizable monomer or radical polymerizable compound having a charge transporting structure) generated at this time are generated. Scratches and toner filming due to incompatibility with the cured product resulting from the reaction are less likely to occur. Further, when the thick film over the entire protective layer is cured by irradiation with light energy, the light transmission from the absorption by the charge transporting structure is limited, and the curing reaction may not sufficiently proceed. In the crosslinkable protective layer of the present invention, preferably a thin film having a thickness of 10 μm or less causes a uniform curing reaction to proceed to the inside, and high wear resistance is maintained inside as well as the surface. In addition, in the formation of the crosslinkable protective layer of the present invention, in addition to the trifunctional radical polymerizable monomer, a radical polymerizable compound having a monofunctional charge transporting structure is contained, which is the trifunctional or higher functional group. These radically polymerizable monomers are incorporated into the cross-linking during curing. On the other hand, when a low molecular charge transport material having no functional group is contained in the cross-linked surface layer, precipitation of the low molecular charge transport material and white turbidity occur due to its low compatibility, and the cross-linked surface layer The mechanical strength also decreases. On the other hand, when a bifunctional or higher-functional charge transporting compound is used as the main component, the crosslink structure is fixed by a plurality of bonds and the crosslink density is further increased. However, the charge transporting structure is very bulky, so that the cured resin structure is distorted. Becomes very large, which increases the internal stress of the crosslinked protective layer.

  Furthermore, the photoreceptor of the present invention has good electrical characteristics, and therefore has excellent repeated stability, realizing high durability and high stability. This is because a radical polymerizable compound having a monofunctional charge transporting structure is used as a constituent material of the crosslinkable protective layer and is immobilized in a pendant shape between the crosslinks. As described above, the charge transport material having no functional group causes precipitation and clouding phenomenon, and the electrical characteristics are remarkably deteriorated in repeated use such as reduction in sensitivity and increase in residual potential. When a bifunctional or higher-functional charge transporting compound is used as the main component, it is fixed in the crosslinked structure with a plurality of bonds, so the intermediate structure (cation radical) during charge transport cannot be kept stable, Sensitivity decreases due to traps and residual potential increases. Such deterioration of the electric characteristics appears as an image such as a decrease in image density and thinning of characters. Furthermore, in the photoconductor of the present invention, the high charge mobility design with less charge trapping of the conventional photoconductor can be applied as the lower charge transport layer, and the electrical side effects of the crosslinked protective layer can be minimized. .

  Furthermore, in the formation of the above-mentioned crosslinkable protective layer of the present invention, the drastic wear resistance is exhibited particularly by making the crosslinkable protective layer insoluble in the organic solvent. The crosslinked protective layer of the present invention is formed by curing a tri- or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Dimensional network structure develops and has a high crosslinking density, but contains other than the above components (for example, mono- or bifunctional monomers, polymer binders, antioxidants, leveling agents, plasticizers and other additives and lower layers) Depending on the dissolved components) and curing conditions, the cross-linking density may be locally dilute or may be formed as an aggregate of minute cured products cross-linked at high density. Such a crosslinkable protective layer has a low bonding strength between cured products and is soluble in organic solvents, and is repeatedly used in the electrophotographic process. Detachment easily occurs. By making the cross-linkable protective layer insoluble in an organic solvent as in the present invention, the original three-dimensional network structure is developed and has a high degree of cross-linking, and the chain reaction proceeds in a wide range so that a cured product is obtained. Due to the high molecular weight, a dramatic improvement in wear resistance is achieved.

Next, the constituent material of the crosslinking type protective layer coating solution of the present invention will be described.
The trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the present invention is a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano. A monomer having no electron transport structure such as an electron-withdrawing aromatic ring having a group or a nitro group and having three or more radically polymerizable functional groups. The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and can be radically polymerized. Examples of these radical polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.

(1) Examples of the 1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = CH—X ₁ −... Formula 10
(In the formula 10, X ₁ represents an arylene group such as a phenylene group and a naphthylene group which may have a substituent, an alkenylene group which may have a substituent, a —CO— group, a —COO— group, -CON _{(R 10)} - group _{(R 10} is hydrogen, alkyl group such as a methyl group, an ethyl group, a benzyl group, naphthylmethyl group, an aralkyl group such as a phenethyl group, a phenyl group, an aryl group such as phenyl or naphthyl Or represents an —S— group.)
Specific examples of these functional groups include vinyl group, styryl group, 2-methyl-1,3-butadienyl group, vinylcarbonyl group, acryloyloxy group, acryloylamide group, vinylthioether group and the like.

(2) Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
_{CH 2 = C (Y) -X} 2 - ···· formula 11
(However, in Formula 11, Y is an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, a naphthyl group, etc. An aryl group, a halogen atom, a cyano group, a nitro group, an alkoxy group such as a methoxy group or an ethoxy group, a -COOR ₁₁ group (R ₁₁ is a hydrogen atom, an optionally substituted methyl group, an ethyl group, etc. An alkyl group, an aralkyl group such as an optionally substituted benzyl or phenethyl group, an aryl group such as an optionally substituted phenyl group or naphthyl group, or -CONR ₁₂ R ₁₃ (R ₁₂ and R ₁₃ is a hydrogen atom, which may have a substituent an alkyl group such as methyl group and ethyl group, which may have a substituent group benzyl group, naphthylmethyl group or a phenethyl group, Aralkyl group or substituent a phenyl group which may have a, an aryl group such as a naphthyl group, which may be the same or different from each other.) Further, X ₂ is the same as X ₁ in the formula 10 A substituent, a single bond, or an alkylene group, provided that at least one of Y and X ₂ is an oxycarbonyl group, a cyano group, an alkenylene group, and an aromatic ring.
Specific examples of these functional groups include an α-acryloyloxy group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.

In addition, examples of the substituent further substituted with the substituent for X ₁ , X ₂ , and Y include, for example, a halogen atom, a nitro group, a cyano group, a methyl group, an alkyl group such as an ethyl group, a methoxy group, an ethoxy group, and the like And an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group and a naphthyl group, and an aralkyl group such as a benzyl group and a phenethyl group.
Among these radical polymerizable functional groups, acryloyloxy group and methacryloyloxy group are particularly useful. For example, a compound having three or more acryloyloxy groups may be an acrylic compound or a compound having three or more hydroxyl groups in the molecule. It can be obtained by using an acid (salt), an acrylic acid halide, or an acrylic ester to cause ester reaction or transesterification. A compound having three or more methacryloyloxy groups can be obtained in the same manner. Further, the radical polymerizable functional groups in the monomer having three or more radical polymerizable functional groups may be the same or different.

Specific examples of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure include the following, but are not limited to these compounds.
That is, examples of the radical polymerizable monomer used in the present invention include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, trimethylolpropane alkylene-modified triacrylate, trimethylolpropane ethyleneoxy-modified (hereinafter referred to as EO modification). ) Triacrylate, trimethylolpropane propyleneoxy modified (hereinafter PO modified) triacrylate, trimethylolpropane caprolactone modified triacrylate, trimethylolpropane alkylene modified trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate Glycerol epichlorohydrin modified (hereinafter ECH modified) Acrylate, glycerol EO modified triacrylate, glycerol PO modified triacrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), dipentaerythritol caprolactone modified hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkylated di Pentaerythritol pentaacrylate, alkylated dipentaerythritol tetraacrylate, alkylated dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, phosphoric acid EO-modified triacrylate, 2, 2, 5, 5 , -Tetrahydroxymethylcyclopentanone tetraacrylate And the like, which can be used in combination either alone or in combination.

  Further, the trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the present invention has a molecular weight relative to the number of functional groups in the monomer in order to form a dense crosslink in the crosslinkable protective layer. The ratio (molecular weight / functional group number) is preferably 250 or less. On the other hand, if this ratio is larger than 250, the crosslinked protective layer tends to be soft and wear resistance tends to decrease somewhat. Therefore, among the monomers exemplified above, monomers having modifying groups such as EO, PO, caprolactone, etc. In the method, it is not preferable to use a compound having an extremely long modifying group alone. In addition, the proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the crosslinkable protective layer is 20 to 80% by weight, preferably 30 to 70% by weight, based on the total amount of the crosslinkable protective layer. is there. When the monomer component is less than 20% by weight, the three-dimensional crosslink density of the crosslinkable protective layer is small, and it is difficult to achieve a dramatic improvement in wear resistance as compared with the case of using a conventional thermoplastic binder resin. On the other hand, when it exceeds 80% by weight, the content of the charge transporting compound is lowered, and the electrical characteristics tend to be deteriorated. The electrical characteristics and abrasion resistance required vary depending on the process used, and the thickness of the cross-linked protective layer of the photoconductor also varies accordingly. A weight percent range is most preferred.

  The radical polymerizable compound having a monofunctional charge transporting structure used in the crosslinked protective layer of the present invention is a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, It refers to a compound having an electron transport structure such as diphenoquinone, an electron-withdrawing aromatic ring having a cyano group or a nitro group, and having one radical polymerizable functional group. Examples of the radical polymerizable functional group include those shown in the above radical polymerizable monomer, and acryloyloxy group and methacryloyloxy group are particularly useful. In addition, a triarylamine structure has a high effect as a charge transporting structure, and in particular, when a compound represented by the structure of the following general formula (1) or (2) is used, electrical characteristics such as sensitivity and residual potential Is well maintained.

｛式中、Ｒ_１は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ_７（Ｒ_７は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基）、ハロゲン化カルボニル基若しくはＣＯＮＲ_８Ｒ_９（Ｒ_８及びＲ_９は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい）を表わし、Ａｒ_１、Ａｒ_２は置換もしくは無置換のアリーレン基を表わし、同一であっても異なってもよい。Ａｒ_３、Ａｒ_４は置換もしくは無置換のアリール基を表わし、同一であっても異なってもよい。Ｘは単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わす。Ｚは置換もしくは無置換のアルキレン基、置換もしくは無置換のアルキレンエーテル２価基、アルキレンオキシカルボニル２価基を表わす。ｍ、ｎは０〜３の整数を表わす。｝

{In the formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), halogen Carbonyl group or CONR ₈ R ₉ (R ₈ and R ₉ may have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Represents a good aryl group, which may be the same or different from each other, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group, which may be the same or different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group. m and n represent an integer of 0 to 3. }

Specific examples of general formulas (1) and (2) are shown below.
In the general formulas (1) and (2), in the substituent of R ₁ , examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. The aralkyl group includes a benzyl group, a phenethyl group, and a naphthylmethyl group, and the alkoxy group includes a methoxy group, an ethoxy group, a propoxy group, and the like. These include a halogen atom, a nitro group, a cyano group, and a methyl group. Substituted with an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group or a naphthyl group, an aralkyl group such as a benzyl group or a phenethyl group, etc. May be.
Of the substituents for R ₁ , particularly preferred are a hydrogen atom and a methyl group.

Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group. In the present invention, the aryl group includes a condensed polycyclic hydrocarbon group, a non-condensed cyclic hydrocarbon group, and a heterocyclic group, and includes the following groups.
The condensed polycyclic hydrocarbon group preferably has 18 or less carbon atoms forming a ring, for example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group. , S-indacenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group , A chrycenyl group, a naphthacenyl group, and the like.

Examples of the non-condensed cyclic hydrocarbon group include monovalent groups of monocyclic hydrocarbon compounds such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether and diphenyl sulfone, or biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne, Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane, and polyphenylalkene, or ring assemblies such as 9,9-diphenylfluorene And monovalent groups of hydrocarbon compounds.
Examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.

Further, the aryl group represented by Ar ₃ or Ar ₄ may have a substituent as shown below, for example.
(1) Halogen atom, cyano group, nitro group and the like.
(2) Alkyl groups, preferably C ₁ -C _12, especially C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkyl groups, further including fluorine atoms , a hydroxyl group, a cyano _group, an alkoxy group of C 1 -C _4, a phenyl group or a halogen _atom, which may have a phenyl group substituted by an alkoxy group C 1 -C ₄ alkyl or _C 1 -C ₄ Good. Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-ethoxyethyl Group, 2-cyanoethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl group and the like.

(3) An alkoxy group (—OR ₂ ), and R ₂ represents the alkyl group defined in (2). Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, benzyloxy group And a trifluoromethoxy group.
(4) An aryloxy group, and examples of the aryl group include a phenyl group and a naphthyl group. It _may contain an alkoxy group having C 1 -C _4, alkyl group, or a halogen atom C 1 -C ₄ as a substituent. Specific examples include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methoxyphenoxy group, and a 4-methylphenoxy group.
(5) Alkyl mercapto group or aryl mercapto group, and specific examples include methylthio group, ethylthio group, phenylthio group, p-methylphenylthio group and the like.
(6)

（式中、Ｒ_３及びＲ_４は各々独立に水素原子、前記（２）で定義したアルキル基、またはアリール基を表わす。アリール基としては、例えばフェニル基、ビフェニル基又はナフチル基が挙げられ、これらはＣ_１〜Ｃ_４のアルコキシ基、Ｃ_１〜Ｃ_４のアルキル基またはハロゲン原子を置換基として含有してもよい。Ｒ_３及びＲ_４は共同で環を形成してもよい。）
具体的には、アミノ基、ジエチルアミノ基、Ｎ−メチル−Ｎ−フェニルアミノ基、Ｎ，Ｎ−ジフェニルアミノ基、Ｎ，Ｎ−ジ（トリール）アミノ基、ジベンジルアミノ基、ピペリジノ基、モルホリノ基、ピロリジノ基等が挙げられる。

(Wherein R ₃ and R ₄ each independently represent a hydrogen atom, an alkyl group defined in (2) above, or an aryl group. Examples of the aryl group include a phenyl group, a biphenyl group, and a naphthyl group, these _C 1 -C ₄ alkoxy _groups, C 1 -C good .R ₃ and _{R 4} may contain as alkyl group or a halogen atom substituents ₄ may be linked to form a ring.)
Specifically, amino group, diethylamino group, N-methyl-N-phenylamino group, N, N-diphenylamino group, N, N-di (tolyl) amino group, dibenzylamino group, piperidino group, morpholino group And pyrrolidino group.

(7) An alkylenedioxy group or an alkylenedithio group such as a methylenedioxy group or a methylenedithio group.
(8) A substituted or unsubstituted styryl group, a substituted or unsubstituted β-phenylstyryl group, a diphenylaminophenyl group, a ditolylaminophenyl group, and the like.

The arylene group represented by Ar ₁ and Ar ₂ is a divalent group derived from the aryl group represented by Ar ₃ and Ar ₄ .
X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group.
The substituted or unsubstituted alkylene group is a C ₁ -C ₁₂ , preferably C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkylene group, and these alkylene groups include a fluorine atom, a hydroxyl group, a cyano _group, an alkoxy group of C 1 -C _4, a phenyl group or a halogen _atom, a phenyl group substituted with an alkyl group or a _C 1 -C ₄ alkoxy group C 1 -C ₄ It may be. Specifically, methylene group, ethylene group, n-butylene group, i-propylene group, t-butylene group, s-butylene group, n-propylene group, trifluoromethylene group, 2-hydroxyethylene group, 2-ethoxyethylene. Group, 2-cyanoethylene group, 2-methoxyethylene group, benzylidene group, phenylethylene group, 4-chlorophenylethylene group, 4-methylphenylethylene group, 4-biphenylethylene group and the like.

The substituted or unsubstituted cycloalkylene _group, a cyclic alkylene group of C 5 -C _7, these are the cyclic alkylene group fluorine atom, a hydroxyl _group, an alkyl group of C 1 -C _4, a C 1 -C ₄ It may have an alkoxy group. Specific examples include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.
The substituted or unsubstituted alkylene ether group represents ethyleneoxy, propyleneoxy, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, tripropylene glycol, alkylene ether group alkylene group is hydroxyl group, methyl group, ethyl group, etc. You may have the substituent of.
The vinylene group is

で表わされ、Ｒ_５は水素、アルキル基（前記（２）で定義されるアルキル基と同じ）、アリール基（前記Ａｒ_３、Ａｒ_４で表わされるアリール基と同じ）、ａは１または２、ｂは１〜３を表わす。

R ₅ is hydrogen, an alkyl group (same as the alkyl group defined in (2) above), an aryl group (same as the aryl group represented by Ar ₃ or Ar ₄ above), a is 1 or 2 , B represents 1-3.

Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group.
Examples of the substituted or unsubstituted alkylene group include the same alkylene groups as those described above for X.
Examples of the substituted or unsubstituted alkylene ether divalent group include the above-mentioned alkylene ether divalent group of X.
Examples of the alkyleneoxycarbonyl divalent group include a caprolactone divalent modifying group.

  Further, the radically polymerizable compound having a monofunctional charge transporting structure of the present invention is more preferably a compound having the structure of the following general formula (3).

（式中、ｏ、ｐ、ｑはそれぞれ０又は１の整数、Ｒａは水素原子、メチル基を表わし、Ｒｂ、Ｒｃは水素原子以外の置換基で炭素数１〜６のアルキル基を表わし、複数の場合は異なっても良い。ｓ、ｔは０〜３の整数を表わす。Ｚａは単結合、メチレン基、エチレン基、

(Wherein, o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, Rb and Rc represent a substituent other than a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, And s and t each represents an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,

を表わす。）
上記一般式で表わされる化合物としては、Ｒｂ、Ｒｃの置換基として、特にメチル基、エチル基である化合物が好ましい。

Represents. )
As the compound represented by the above general formula, compounds having a methyl group or an ethyl group as substituents for Rb and Rc are particularly preferable.

  The radical polymerizable compound having a monofunctional charge transporting structure represented by the above general formulas (1) and (2), particularly (3) used in the present invention is polymerized by releasing the carbon-carbon double bond on both sides. Therefore, in the polymer that does not become a terminal structure, is incorporated in the chain polymer, and is crosslinked by polymerization with a tri- or higher functional radical polymerizable monomer, it exists in the main chain of the polymer, and Present in the main chain-cross-linked chain (this cross-linked chain has an intermolecular cross-linked chain between one polymer and another polymer, and a main chain folded in one polymer. There is an intramolecular cross-linked chain that crosslinks the site and another site derived from the polymerized monomer at a position away from this in the main chain), but even if it exists in the main chain, Even if present in the triarylamine structure suspended from the chain moiety, It has at least three aryl groups arranged in the radial direction from and is bulky, but it is not directly bonded to the chain part and is suspended from the chain part via a carbonyl group etc. Since these triarylamine structures can be arranged adjacent to each other in the polymer, there is little structural distortion in the molecule, and the surface of the electrophotographic photosensitive member is also fixed. In the case of a layer, it is presumed that an intramolecular structure that is relatively free from interruption of the charge transport pathway can be adopted.

  Specific examples of the radically polymerizable compound having a monofunctional charge transporting structure of the present invention are shown below, but are not limited to the compounds having these structures.

  Further, the radical polymerizable compound having a monofunctional charge transporting structure used in the present invention is important for imparting the charge transporting performance of the crosslinkable protective layer, and this component is 20 to 80 with respect to the crosslinkable protective layer. % By weight, preferably 30 to 70% by weight. If this component is less than 20% by weight, the charge transport performance of the cross-linked protective layer cannot be sufficiently maintained, and repeated use tends to cause deterioration of electrical characteristics such as a decrease in sensitivity and an increase in residual potential. On the other hand, if it exceeds 80% by weight, the content of the trifunctional monomer having no charge transporting structure is lowered, and the crosslink density is lowered, so that high wear resistance tends to be hardly exhibited. The electrical characteristics and abrasion resistance required differ depending on the process used, and the thickness of the crosslinked protective layer of the photoreceptor of the present invention varies accordingly. A range of ˜70% by weight is most preferred.

  The crosslinkable protective layer constituting the electrophotographic photosensitive member of the present invention is obtained by curing at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. However, in addition to this, monofunctional and bifunctional radically polymerizable monomers and functionalities for the purpose of imparting functions such as viscosity adjustment during coating, stress relaxation of the cross-linked protective layer, low surface energy, and reduction of friction coefficient, etc. A monomer and a radically polymerizable oligomer can be used in combination. Known radical polymerizable monomers and oligomers can be used.

  Examples of the monofunctional radically polymerizable monomer include 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl carbitol acrylate, 3-methoxybutyl acrylate, benzyl acrylate, Examples include cyclohexyl acrylate, isoamyl acrylate, isobutyl acrylate, methoxytriethylene glycol acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, and styrene monomer.

  Examples of the bifunctional radical polymerizable monomer include 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1, Examples include 6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A-EO modified diacrylate, bisphenol F-EO modified diacrylate, neopentyl glycol diacrylate, and the like.

  Examples of the functional monomer include those substituted with a fluorine atom such as octafluoropentyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl methacrylate, 2-perfluoroisononylethyl acrylate, No. 60503, JP-B-6-45770, siloxane repeating units: 20-70 acryloyl polydimethylsiloxane ethyl, methacryloyl polydimethylsiloxane ethyl, acryloyl polydimethylsiloxane propyl, acryloyl polydimethylsiloxane butyl, diacryloyl polydimethylsiloxane Examples include vinyl monomers having a polysiloxane group such as diethyl, acrylates and methacrylates.

Examples of the radical polymerizable oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate oligomers.
However, when a large amount of monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers are contained, the three-dimensional crosslink density of the crosslinkable protective layer is substantially lowered, resulting in a decrease in wear resistance. Therefore, the content of these monomers and oligomers is more preferably 50 parts by weight or less, preferably 30 parts by weight or less with respect to 100 parts by weight of the tri- or higher functional radical polymerizable monomer.

  The crosslinked protective layer of the present invention is obtained by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Accordingly, a polymerization initiator may be contained in the crosslinkable protective layer coating solution in order to allow the curing reaction to proceed efficiently.

  Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di ( Peroxybenzoyl) hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) B) Peroxide-based initiators such as propane, azo-based compounds such as azobisisobutylnitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 4,4′-azobis-4-cyanovaleric acid Initiators are mentioned.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2- Acetophenone-based or ketal-based photopolymerization initiators such as methyl-2-morpholino (4-methylthiophenyl) propan-1-one and 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, benzoin , Benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether Benzoin ether photopolymerization initiators such as benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, 1, Benzophenone photopolymerization initiators such as 4-benzoylbenzene, thioxanthone photopolymerization initiation such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone And other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 2,4,6-trimethylbenzoylpheny Ethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10- Examples include phenanthrene, acridine compounds, triazine compounds, and imidazole compounds. Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4'-dimethylaminobenzophenone, and the like.

  These polymerization initiators may be used alone or in combination of two or more. The content of the polymerization initiator is 0.5 to 40 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the total content having radical polymerizability.

  Furthermore, the coating liquid for forming a crosslinked protective layer of the present invention may contain various plasticizers (for the purpose of stress relaxation and adhesion improvement), leveling agents, and low molecular charge transport materials that do not have radical reactivity as necessary. An agent can be contained. As these additives, known additives can be used, and as plasticizers, those used in general resins such as dibutyl phthalate and dioctyl phthalate can be used, and the amount used is the total solid content of the coating liquid. To 20 wt% or less, preferably 10 wt% or less. As leveling agents, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain can be used, and the amount used is based on the total solid content of the coating liquid. 3% by weight or less is appropriate.

  The crosslinkable protective layer of the present invention comprises a coating solution containing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure as described above. It is formed by coating and curing on the charge transport layer. When the radically polymerizable monomer is a liquid, the coating liquid can be applied by dissolving other components in the liquid, but if necessary, it is diluted with a solvent and applied. Solvents used at this time include alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, tetrahydrofuran, dioxane and propyl ether. And ethers such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene, aromatics such as benzene, toluene and xylene, cellosolves such as methyl cellosolve, ethyl cellosolve and cellosolve acetate. These solvents may be used alone or in combination of two or more. The dilution ratio with the solvent varies depending on the solubility of the composition, the coating method, and the target film thickness, and is arbitrary. The coating can be performed using a dip coating method, spray coating, bead coating, ring coating method or the like.

In the present invention, after applying such a crosslinkable protective layer coating solution, the external energy is applied and cured to form a crosslinkable protective layer. The external energy used at this time is heat, light, radiation, etc. Etc. The heat energy is applied by heating from the coating surface side or the support side using a gas such as air or nitrogen, steam, various heat media, infrared rays, or electromagnetic waves. The heating temperature is preferably 100 ° C. or higher and 170 ° C. or lower. If the heating temperature is lower than 100 ° C., the reaction rate is slow and the curing reaction tends not to be completed completely. At a high temperature exceeding 170 ° C., the curing reaction proceeds non-uniformly, and large strains, a large number of unreacted residues, and reaction termination terminals are generated in the crosslinked protective layer. In order to proceed the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 100 ° C. and then heating to 100 ° C. or more. As light energy, UV irradiation light sources such as high-pressure mercury lamps and metal halide lamps that have an emission wavelength mainly in the ultraviolet region can be used, but a visible light source can be selected according to the absorption wavelength of radically polymerizable substances and photopolymerization initiators. Is also possible. Irradiation light amount is 50 mW / cm ² or more, preferably 1000 mW / cm ² or less, it takes time for the curing reaction is less than 50 mW / cm ^2. If it is higher than 1000 mW / cm ^2, the progress of the reaction becomes non-uniform, and local wrinkles are generated on the surface of the cross-linked protective layer, and many unreacted residues and reaction termination ends are generated. In addition, internal stress increases due to rapid crosslinking, which causes cracks and film peeling. Examples of radiation energy include those using electron beams. Among these energies, those using heat and light energy are useful because of the ease of reaction rate control and the simplicity of the apparatus.

  The film thickness of the crosslinked protective layer of the present invention is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 8 μm or less. If it is thicker than 10 μm, cracks and film peeling are likely to occur as described above, and if it is 8 μm or less, the margin is further improved, so that the crosslink density can be increased, and material selection and curing that further increases wear resistance. Conditions can be set. On the other hand, the radical polymerization reaction is prone to oxygen inhibition, that is, the surface in contact with the air is not easily cross-linked or non-uniform due to the influence of radical trapping by oxygen. This effect appears remarkably when the surface layer is less than 1 μm, and a crosslinked protective layer having a thickness less than this thickness is likely to have a reduced wear resistance or uneven wear. In addition, when the crosslinkable protective layer is applied, the lower charge transport layer component is mixed.In particular, if the coating thickness of the crosslinkable protective layer is thin, the contaminants spread throughout the layer, inhibiting the curing reaction and reducing the crosslinking density. Bring about a decline. For these reasons, the crosslinkable protective layer of the present invention has good wear resistance and scratch resistance at a film thickness of 1 μm or more. However, when repeatedly used, a part that is locally scraped to the lower charge transport layer is formed. The wear of the portion increases, and the density unevenness of the halftone image tends to occur due to the chargeability and sensitivity fluctuation. Therefore, it is desirable that the thickness of the cross-linking protective layer is 2 μm or more for a longer life and higher image quality.

  When the outermost crosslinkable protective layer is insoluble in an organic solvent in the structure in which the intermediate layer, the photosensitive layer (charge generation layer, charge transport layer), and the crosslinkable protective layer of the electrophotographic photosensitive member of the present invention are sequentially laminated. It is characterized by achieving dramatic wear resistance and scratch resistance. As a method for testing the solubility in an organic solvent, a drop of an organic solvent having high solubility in a polymer substance, for example, tetrahydrofuran, dichloromethane, or the like, is dropped on the surface layer of the photoconductor, and the surface shape of the photoconductor is dried after natural drying. It can be determined by observing the change with a stereomicroscope. Highly soluble photoconductors have a phenomenon that the central part of the droplet becomes concave and the surroundings swell up, the charge transport material precipitates and becomes cloudy or cloudy due to crystallization, and the surface swells and then shrinks, causing wrinkles Changes such as the phenomenon to be seen. In contrast, an insoluble photoconductor does not exhibit the above-described phenomenon, and does not change at all as before dropping.

  In the constitution of the present invention, in order to make the crosslinkable protective layer insoluble in the organic solvent, (1) composition of the crosslinkable protective layer coating solution, adjustment of the content ratio thereof, (2) coating of the crosslinkable protective layer Dilution solvent of working solution, adjustment of solid content concentration, (3) Selection of coating method of crosslinkable protective layer, (4) Control of curing conditions of crosslinkable protective layer, (5) Difficult dissolution of lower charge transport layer It is important to control these factors such as sexualization, but it is not achieved by a single factor.

  The composition of the crosslinkable protective layer coating solution may be a radical polymerizable compound in addition to the above-described trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. When a large amount of additives such as a binder resin having no functional group, an antioxidant, and a plasticizer is contained, the crosslinking density is reduced, and the cured product resulting from the reaction and phase separation between the additive and the organic solvent are caused. It tends to be soluble. Specifically, it is important to suppress the total content to 20% by weight or less with respect to the total solid content of the coating liquid. Further, in order not to dilute the crosslinking density, the total content of monofunctional or bifunctional radical polymerizable monomers, reactive oligomers, and reactive polymers is 20% by weight or less based on the trifunctional radical polymerizable monomers. It is desirable. Further, when a large amount of a radical polymerizable compound having a bifunctional or higher functional charge transporting structure is contained, a bulky structure is fixed in the crosslinked structure by a plurality of bonds, so that distortion is likely to occur. It is easy to become an aggregate. This can cause solubility in organic solvents. Although different depending on the compound structure, the content of the radical polymerizable compound having a bifunctional or higher functional charge transporting structure is preferably 10% by weight or less based on the radical polymerizable compound having a monofunctional charge transporting structure.

  As for the diluting solvent of the crosslinkable protective layer coating solution, if a solvent with a slow evaporation rate is used, the remaining solvent may hinder the curing, or increase the amount of the lower layer component mixed. Reduces the cured density. For this reason, it tends to be soluble in organic solvents. Specifically, tetrahydrofuran, a mixed solvent of tetrahydrofuran and methanol, ethyl acetate, methyl ethyl ketone, ethyl cellosolve and the like are useful, but are selected according to the coating method. Further, regarding the solid content concentration, if it is too low for the same reason, it tends to be soluble in an organic solvent. Conversely, the upper limit concentration is constrained by the limitations of film thickness and coating solution viscosity. Specifically, it is desirable to use in the range of 10 to 50% by weight. As a coating method for the cross-linked protective layer, for the same reason, the solvent content at the time of forming the coating film, a method of reducing the contact time with the solvent is preferable, specifically, the spray coating method, the amount of coating liquid A regulated ring coat method is preferred. Also, in order to suppress the amount of the lower layer component mixed in, a polymer charge transport material is used as the charge transport layer, and a crosslinkable protective layer is applied between the photosensitive layer (or charge transport layer) and the crosslinkable protective layer. It is also effective to provide an intermediate layer insoluble in the solvent.

As the curing conditions for the cross-linkable protective layer, if the energy of heating or light irradiation is low, the curing is not completely completed and the solubility in the organic solvent is increased. On the other hand, when cured with very high energy, the curing reaction becomes non-uniform, and it tends to increase the number of uncrosslinked parts and radical stopping parts and to form an aggregate of minute cured products. For this reason, it may become soluble in an organic solvent. In order to insolubilize in an organic solvent, the heat curing conditions are preferably 100 to 170 ° C. and 10 minutes to 3 hours, and the curing conditions by UV light irradiation are 50 to 1000 mW / cm ² and 5 seconds to 5 minutes. In addition, it is desirable to control the temperature rise to 50 ° C. or less to suppress non-uniform curing reaction.

  An example of a method for making the crosslinkable protective layer constituting the electrophotographic photoreceptor of the present invention insoluble in an organic solvent is, for example, an acrylate monomer having three acryloyloxy groups and one acryloyloxy group as a coating liquid. When using a triarylamine compound having a ratio of 7: 3 to 3: 7, a polymerization initiator is added in an amount of 3 to 20% by weight based on the total amount of these acrylate compounds, and a solvent is added. Prepare the coating solution. For example, in the case where the charge transport layer which is the lower layer of the crosslinkable protective layer uses a triarylamine donor as the charge transport material and polycarbonate as the binder resin and the surface layer is formed by spray coating, the above coating liquid As the solvent, tetrahydrofuran, 2-butanone, ethyl acetate and the like are preferable, and the use ratio thereof is 3 to 10 times the total amount of the acrylate compound.

Next, for example, the prepared coating solution is applied by spraying or the like on a photoreceptor in which an intermediate layer, a charge generation layer, and the charge transport layer are sequentially laminated on a support such as an aluminum cylinder. Thereafter, it is naturally dried or dried at a relatively low temperature for a short time (25 to 80 ° C., 1 to 10 minutes), and cured by UV irradiation or heating.
For UV irradiation, uses a metal halide lamp, illuminance 50 mW / cm ² or more, 1000 mW / cm ² or less, preferably about 5 minutes 5 seconds as the time, the drum temperature is controlled so as not to exceed 50 ° C. .
In the case of thermosetting, the heating temperature is preferably 100 to 170 ° C. For example, when a blowing oven is used as a heating means and the heating temperature is set to 150 ° C, the heating time is 20 minutes to 3 hours.
After completion of curing, the photosensitive member of the present invention is obtained by further heating at 100 to 150 ° C. for 10 to 30 minutes to reduce the residual solvent.
In addition to the protective layer containing the filler and the crosslinked protective layer described above, a known material such as a-C or a-SiC formed by a vacuum thin film forming method can be used as the protective layer. .

As described above, when a protective layer is formed on the photosensitive layer, there is a case where the neutralizing light does not sufficiently reach the photosensitive layer unless the appropriate protective layer is selected, and the neutralizing action does not work clearly. In addition, the protective layer absorbs the static elimination light, so that it tends to deteriorate, and conversely, there is a case where a residual potential rise is generated. Therefore, in any of the protective layers described above, it is desirable that the transmittance for static elimination light is 30% or more, preferably 50% or more, and more desirably 85% or more.
The transmittance of the protective layer is measured by the same method as that for the charge transport layer. That is, the protective layer used for the photoconductor is formed alone, and the spectral absorption spectrum is measured with a commercially available spectrophotometer. It is obtained by obtaining the transmittance at the wavelength of the static elimination light used in the image forming apparatus from the spectrum.

In addition, when a protective layer is provided on the photosensitive layer configured in the order of the charge generation layer and the charge transport layer, and the discharge light is irradiated from the surface side of the photoreceptor, the discharge light passes through the protection layer and the charge transport layer. The charge generation layer is irradiated. Accordingly, the transmittance in a form in which the charge transport layer and the protective layer are laminated is important. In this case, in the state where the charge transport layer and the protective layer are laminated, it is desirable that the transmittance with respect to the static elimination light is 30% or more, preferably 50% or more, and more desirably 85% or more.
In such a case, the transmittance can be obtained by measuring the spectral absorption spectrum of the coating film in a state where the charge transport layer and the protective layer are laminated as described above.

  As described above, providing a protective layer on the surface of the photoconductor not only enhances the durability (wear resistance) of each photoconductor, but is also used in a tandem type full-color image forming apparatus as described below. In such a case, a new effect that does not exist in the monochrome image forming apparatus is also produced.

  In the present invention, in order to improve environmental resistance, in order to prevent a decrease in sensitivity and an increase in residual potential, in particular, in each layer such as a protective layer, a charge transport layer, a charge generation layer, a charge blocking layer, and a moire prevention layer. Antioxidants can be added.

(Phenolic compounds)
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 4, 4'-thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4 -Hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene- -(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) butyric acid] Crycol esters, tocopherols, etc.

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

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

(Organic sulfur compounds)
Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.

(Organic phosphorus compounds)
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.
These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained. The addition amount of the antioxidant in the present invention is 0.01 to 10% by weight based on the total weight of the layer to be added.

  In the case of a full-color image, various types of images are input, but on the contrary, a typical image may also be input. For example, the presence of a seal in a Japanese document or the like. Something like indicia is usually located towards the edge of the image area, and the colors used are also limited. In a state in which a random image is always written, image writing, development, and transfer are performed on the photoconductor in the image forming element on average. When many image formations are repeated or only a specific image forming element is used, the durability balance is lost. When a photoconductor having a low surface durability (physical / chemical / mechanical) is used in such a state, this difference becomes prominent and easily causes an image problem. On the other hand, when the photoconductor is made highly durable, the amount of such local change is small, and as a result, it becomes difficult to appear as a defect on the image, so that high durability is achieved and the stability of the output image is improved. This is very effective.

-Electrostatic latent image forming means-
The formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the electrostatic latent image carrier and then performing imagewise exposure, and is performed by the electrostatic latent image forming unit. be able to.
The electrostatic latent image forming means includes, for example, at least a charger that uniformly charges the surface of the electrostatic latent image carrier and an exposure device that exposes the surface of the electrostatic latent image carrier imagewise. Prepare.

The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charging device including a conductive or semiconductive roll, brush, film, rubber blade, etc. And non-contact chargers using corona discharge such as corotron and scorotron (including proximity-type non-contact chargers having a gap of 100 μm or less between the surface of the photoreceptor and the charger).
The electric field strength applied to the electrostatic latent image carrier by the charger is preferably 20 to 60 V / μm, and more preferably 30 to 50 V / μm. The higher the electric field strength applied to the photoconductor, the better the dot reproducibility. However, if the electric field strength is too high, problems such as dielectric breakdown of the photoconductor and carrier adhesion during development may occur.

The electric field strength is expressed by the following mathematical formula (1).
<Formula (1)>
Electric field strength (V / μm) = SV / G
In Equation (1), SV represents the absolute value (V) of the surface potential at the unexposed portion of the electrostatic latent image carrier at the development position. G represents the film thickness (μm) of the photosensitive layer including at least the photosensitive layer (charge generation layer and charge transport layer).

  The exposure can be performed, for example, by exposing the surface of the latent electrostatic image bearing member imagewise using the exposure device. The type of the exposure device is not particularly limited and may be appropriately selected according to the purpose. For example, various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system. Is mentioned. In the present invention, a back light system in which imagewise exposure is performed from the back surface side of the electrostatic latent image carrier may be employed.

As the light source of the exposure device, a light source capable of ensuring high luminance such as a light emitting diode (LED), a semiconductor laser (LD), or electroluminescence (EL) is used.
Depending on the resolution of the light source (write light) to be used, the resolution of the electrostatic latent image and thus the toner image to be formed is determined, and the higher the resolution, the clearer the image. However, if writing is performed with a higher resolution, the time required for writing becomes longer. Therefore, if there is one writing light source, writing is limited by the drum linear speed (process speed). Therefore, when there is one writing light source, a resolution of about 2400 dpi is the upper limit. If there are a plurality of writing light sources, each of them only has to bear the writing area, and the upper limit is substantially “2400 dpi × number of writing light sources”. Among these light sources, light emitting diodes and semiconductor lasers have high irradiation energy and are used favorably.

  Further, since a finer electrostatic latent image is formed by using a light source having a wavelength shorter than 450 nm as the light source wavelength of the exposure device, it is effectively used in the present invention. Examples of a technique for causing laser oscillation in such a wavelength range include a method in which the wavelength of laser light is halved using second harmonic generation (SHG), and a technique using a wide gap semiconductor. In recent years, an LD that oscillates in a wavelength region of 400 to 410 nm has been developed, and an optical system using the LD has been developed and can be used beneficially in the present invention. The lower limit of the wavelength that can be used for the current writing light is approximately 350 nm, although it varies depending on the materials constituting the charge transport layer and the protective layer. With the development of new materials and lasers, this lower limit will be shortened.

-Development means-
The development can be performed by developing the electrostatic latent image with toner to form a visible image. As the toner, a toner having the same polarity as the charged polarity of the photoreceptor is used, and the electrostatic latent image is developed by reversal development (negative / positive development). In addition, there are two methods, a one-component method in which development is performed only with toner and a two-component method in which a two-component developer composed of toner and carrier is used.

-Transfer means-
The transfer means is a means for transferring the visible image to a recording medium. The transfer means can transfer the visible image directly from the surface of the photosensitive member to the recording medium, and an intermediate transfer body. There is a method in which a visual image is first transferred and then the visible image is secondarily transferred onto the recording medium. Either aspect can be used satisfactorily, but the former method (direct transfer) with a small number of transfers is preferred when the adverse effect of the transfer is great when the image quality is improved.

  The transfer can be performed, for example, by charging the latent electrostatic image bearing member (photosensitive member) with the transfer charger using the visible image, and can be performed by the transfer unit. The transfer unit is not particularly limited, and can be appropriately selected from known transfer units according to the purpose. For example, a transfer conveyance belt that can simultaneously convey the recording medium can be preferably used. It is done.

  The transfer means (the primary transfer means and the secondary transfer means) is a transfer for peeling and charging the visible image formed on the electrostatic latent image carrier (photoconductor) to the recording medium side. It is preferable to have at least a charger. There may be one transfer means or two or more transfer means. Examples of the transfer charger 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 not particularly limited and can be appropriately selected from known recording media (recording paper).

  The transfer charger may be a transfer belt or a transfer roller, but it is desirable to use a contact type such as a transfer belt or transfer roller that generates less ozone. As a voltage / current application method at the time of transfer, either a constant voltage method or a constant current method can be used, but the transfer charge amount can be kept constant, and a constant voltage with excellent stability can be used. The current method is more desirable. As such a transfer member, a known member can be used as long as the structure of the present invention can be satisfied.

  As described above, the amount of charge passing through the photoconductor per cycle of image formation varies greatly depending on the surface potential of the photoconductor after transfer (the surface potential of the difference entering the charge eliminating portion). The larger this is, the greater the influence on the electrostatic fatigue of the photoreceptor in repeated use.

  This passing charge amount corresponds to the amount of charge flowing in the film thickness direction of the photoreceptor. As an operation of the photoconductor in the image forming apparatus, the main charger is charged to a desired charging potential (in most cases, negatively charged), and optical writing is performed based on an input signal corresponding to the document. At this time, photocarriers are generated in the portion where writing has been performed, and the surface charge is neutralized (potential decay). At this time, the amount of charge depending on the amount of generated photocarriers flows in the direction of the photoreceptor film thickness. On the other hand, the region where the optical writing is not performed (non-writing portion) proceeds to the charge removal process through the development process and the transfer process (a cleaning process is performed before that if necessary). Here, when the surface potential of the photoconductor is close to the potential applied by the main charging (excluding dark decay), the amount of charge is almost the same as that in the area where optical writing is performed. Will flow into. In general, since the current document has a low writing rate, this method means that the current passing through the photoconductor in repeated use is mostly current flowing in the static elimination process (the writing rate is 10%). Then, the current flowing in the static elimination process occupies 90% of the total).

  This passing charge greatly affects the electrostatic characteristics of the photoconductor, for example, causing deterioration of the material constituting the photoconductor. As a result, the residual potential of the photosensitive member is raised, depending on the amount of passing charge. When the residual potential of the photosensitive member is increased, the image density is lowered in the negative and positive development used in the present invention, which is a serious problem. Therefore, there is a problem of how to reduce the passing charge amount of the photoconductor in order to increase the lifetime (high durability) of the photoconductor in the image forming apparatus.

  On the other hand, there is a way of thinking that the photostatic discharge is not performed, but if the main charger is not sufficiently charged, the charging cannot be stabilized and a problem such as an afterimage may occur. The passing charge of the photosensitive member is generated by the movement of the generated optical carrier by light irradiation by the electric potential (the electric field generated thereby) charged on the surface of the photosensitive member. Therefore, if the photoreceptor surface potential can be attenuated by means other than light, the amount of passing charge per rotation of the photoreceptor (one cycle of image formation) can be reduced.

  For this purpose, it is effective to adjust the charge passing through the photosensitive member by adjusting the transfer bias in the transfer process. That is, the non-writing portion that is charged by the main charger and does not perform writing enters the transfer process in a state close to the charged potential except for the dark attenuation amount. At this time, by reducing the absolute value of the polarity charged by the main charger to 100 V or less, even when entering the subsequent static elimination process, almost no photocarrier is generated and no passing charge is generated. This value is preferably closer to 0V.

Furthermore, by adjusting the transfer bias, by applying a transfer bias so that the surface potential of the photosensitive member is charged to a polarity opposite to the charging polarity applied by the main charging, it is more preferable because no optical carrier is generated. . However, under transfer conditions that charge to the opposite polarity, there are cases where a large amount of transfer dust occurs or the main charge of the next image forming process (cycle) cannot catch up. In that case, since a problem such as an afterimage may occur, the absolute value of the reverse polarity is preferably 100 V or less.
Adding the control as described above can effectively use the effect of the present invention as a remarkable effect.

-Fixing means-
The fixing may be performed each time the visible image transferred to the recording medium is fixed using a fixing device and transferred to the recording medium for each color toner, or the toner is stacked on each color toner. May be performed simultaneously at the same time.

  There is no restriction | limiting in particular as said fixing device, Although it can select suitably according to the objective, A well-known heating-pressing means is suitable. Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt. The heating in the heating and pressing means is usually preferably 80 ° C to 200 ° C. In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing step and the fixing unit depending on the purpose.

-Static elimination means-
The static elimination means has a wavelength of less than 500 nm (however, a wavelength that can be absorbed by nitrogen-doped titanium oxide contained in the intermediate layer of the photoreceptor), and performs static elimination on the electrostatic latent image carrier. Can be selected as appropriate from known static eliminators. For example, a semiconductor laser (LD), electroluminescence (EL), and the like are preferable.

  For light sources such as semiconductor lasers (LD) and electroluminescence (EL), semiconductor lasers (LD) and electroluminescence (EL) having an oscillation wavelength of less than 500 nm, or fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium A combination of a lamp, a xenon lamp, or the like with an appropriate optical filter that can limit light emission to less than 500 nm can be used. The optical filter includes various types 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 in order to irradiate only light in a desired wavelength range (less than 500 nm). A filter can also be used.

There are several techniques for causing laser oscillation in such a wavelength range. One is to use a non-linear optical material and to halve the wavelength of the laser beam using second harmonic generation (SHG) (for example, Japanese Patent Laid-Open Nos. 9-275242 and 9). No. 189930, JP-A-5-313033, etc.). Since this system can use a GaAs LD or YAG laser that has already established technology and can output high power as a primary light source, it is possible to extend the life and output. The other uses a wide gap semiconductor, and the size of the apparatus can be reduced as compared with a device using SHG. LD using a ZnSe-based semiconductor (see JP-A-7-321409, JP-A-6-334272, etc.) or a GaN-based semiconductor (see JP-A-8-88441, JP-A-7-335975, etc.) However, because of its high luminous efficiency, it has been the subject of many studies. As a relatively recent technology, Nichia Corporation has put into practical use LD (405 nm oscillation) using a GaN-based semiconductor, and has developed a writing system far more advanced than the above-mentioned technology. It can be used beneficially.
In addition, LED lamps using the above materials are also on the market, and these can also be used effectively.

  On the other hand, at the present time, the lower limit is determined by the following problem. That is, as a material constituting the photoconductor (charge transport layer or protective layer existing on the writing light incident side), a charge transport material can be mentioned. Among charge transport materials that have high mobility and can be used at a practical level. In other words, there is no material that is sufficiently transparent to light having a component shorter than about 350 nm. This is because most of the charge transport materials currently developed have a triarylamine structure, and the absorption edge on the long wavelength side of this material is approximately 300 to 350 nm. Therefore, if further shortening of the light source for static elimination and further transparency of the charge transport material (shortening of absorption) are realized, the oscillation wavelength of the light source that can be used in the present invention is further reduced. Will extend.

-Others-
The cleaning means is not particularly limited as long as it can remove the electrophotographic toner remaining on the electrostatic latent image carrier, and can be appropriately selected from known cleaners. Suitable examples include brush cleaners, electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

The recycling unit is a step of recycling the electrophotographic color toner removed by the cleaning unit to the developing unit, and examples thereof include a known conveyance unit.
The control means is a process for controlling the steps, and can be suitably performed by the control means.
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.

Here, an aspect of the image forming apparatus of the present invention will be described with reference to FIG.
FIG. 8 is a schematic diagram for explaining the image forming apparatus of the present invention, and modifications as described later also belong to the category of the present invention.
In FIG. 8, a photosensitive member (1) as an electrostatic latent image carrier has an intermediate layer containing at least nitrogen-doped titanium oxide, a charge generation layer containing an organic charge generation material, and a charge transport material on a support. A laminated photosensitive layer comprising a charge transport layer is provided. The photoconductor (1) has a drum shape, but may be a sheet or an endless belt.

  As the charger (3), a wire type charger or a roller-type charger is used. When high-speed charging is required, a scorotron charger is preferably used. In a compact or tandem image forming apparatus that uses a plurality of photoconductors described later, acid gas (NOx, SOx, etc.) A roller-shaped charger that generates less ozone is effectively used. Although the photosensitive member is charged by this charger, the higher the electric field strength applied to the photosensitive member, the better the dot reproducibility. Therefore, it is desirable to apply an electric field strength of 20 V / μm or more. . However, there is a possibility that problems such as dielectric breakdown of the photosensitive member and carrier adhesion during development occur, and the upper limit is approximately 60 V / μm or less, more preferably 50 V / μm or less.

In addition, the image exposure unit (5) can ensure high luminance such as a light emitting diode (LED), a semiconductor laser (LD), and electroluminescence (EL), and can be written with a high resolution (600 dpi or higher resolution). Is used. Depending on the resolution of the light source (writing light), the resolution of the formed electrostatic latent image, and thus the toner image, is determined. The higher the resolution, the clearer the image. However, if writing is performed with a higher resolution, the time required for writing becomes longer. Therefore, if there is one writing light source, writing is limited by the drum linear speed (process speed). Therefore, when there is one writing light source, a resolution of about 1200 dpi is the upper limit. When there are a plurality of writing light sources, each of them only needs to bear a writing area, and “1200 dpi × number of writing light sources” is practically the upper limit. Among these light sources, light emitting diodes and semiconductor lasers have high irradiation energy and are used favorably.
Further, as described above, it is an effective means to use laser light having an oscillation wavelength shorter than 450 nm.

The developing unit (6) which is a developing means has at least one developing sleeve.
In the developing unit (6), toner having the same polarity as the charged polarity of the photoreceptor is used, and the electrostatic latent image is developed by reversal development (negative / positive development). Depending on the light source used in the previous image exposure unit, in the case of a digital light source used in recent years, there is generally a reversal development method in which toner development is performed on the writing portion in response to a low image area ratio. This is advantageous in view of the lifetime of the light source. In addition, there are two methods, a one-component method in which development is performed only with toner and a two-component method in which a two-component developer composed of toner and carrier is used.

  The transfer charger (10) may be a transfer belt or a transfer roller, but it is desirable to use a contact type such as a transfer belt or transfer roller that generates less ozone. As a voltage / current application method at the time of transfer, either a constant voltage method or a constant current method can be used, but the transfer charge amount can be kept constant, and a constant voltage with excellent stability can be used. The current method is more desirable. In particular, by subtracting the current that flows from the power supply member (high-voltage power supply) that supplies electric charge to the transfer member and does not flow into the photosensitive member, the current to the photosensitive member is subtracted. A method of controlling the value is preferred.

  The transfer current is a current based on the amount of charge required to peel off the toner electrostatically attached to the photosensitive member and transfer it to a transfer target (transfer paper or intermediate transfer member). In order to avoid transfer defects such as transfer residue, it is only necessary to increase the transfer current. However, in the case of using negative and positive development, charging with a polarity opposite to the charging polarity of the photosensitive member is given. As a result, the electrostatic fatigue of the photoconductor becomes remarkable. The larger the transfer current, the more advantageous it is because a charge amount exceeding the electrostatic adhesion force between the photoconductor and the toner can be given. However, if a certain threshold value is exceeded, a discharge phenomenon occurs between the transfer member and the photoconductor, and it becomes fine. As a result, the developed toner image is scattered. For this reason, the upper limit is a range in which this discharge phenomenon does not occur. This threshold varies depending on the gap (distance) between the transfer member and the photoconductor, the material constituting the both, and the like, but the discharge phenomenon can be avoided by using it at about 200 μA or less. Therefore, the upper limit value of the transfer current is about 200 μA.

Further, the toner image formed on the photoconductor is transferred onto the transfer paper to become an image on the transfer paper. At this time, there are two methods. One is a method of directly transferring a toner image developed on the surface of the photoreceptor as shown in FIG. 8 to the transfer paper, and the other is that the toner image is once transferred from the photoreceptor to the intermediate transfer body, and this is transferred to the transfer paper. It is the method of transferring to. Either case can be used in the present invention.
As such a transfer member, a known member can be used as long as the structure of the present invention can be satisfied.
In addition, by controlling the transfer current as described above, reducing the photoreceptor surface potential after transfer (the unexposed portion of the writing light) reduces the amount of charge passed through the photoreceptor per one cycle of image formation. Can be used effectively in the present invention.

  The light source such as the static elimination lamp (2) has a wavelength of less than 500 nm (however, a wavelength that can be absorbed by the nitrogen-doped titanium oxide contained in the intermediate layer of the photoreceptor), and the electrostatic latent image carrier As long as it can perform static elimination, it can be appropriately selected from known static eliminators. For example, a semiconductor laser (LD), electroluminescence (EL), and the like are preferable.

For light sources such as semiconductor lasers (LD) and electroluminescence (EL), semiconductor lasers (LD) and electroluminescence (EL) having an oscillation wavelength of less than 500 nm, or fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium A combination of a lamp, a xenon lamp, or the like with an appropriate optical filter that can limit light emission to less than 500 nm can be used. The optical filter includes various types 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 in order to irradiate only light in a desired wavelength range (less than 500 nm). A filter can also be used.
The lower limit of the wavelength to be used varies depending on the transmittance of the charge transport layer and the protective layer used in the photosensitive member, but the lower limit is approximately 300 to 350 nm.
In FIG. 8, (8) is a registration roller, (11) is a separation charger, and (12) is a separation claw.

  In addition, the toner developed on the photoreceptor (1) by the developing unit (6) is transferred to the transfer paper (9), but when toner remaining on the photoreceptor (1) is generated, a fur brush ( 14) and the cleaning blade (15). Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.

Next, FIG. 9 is a schematic view for explaining the tandem type full-color image forming apparatus of the present invention, and the following modifications also belong to the category of the present invention.
In FIG. 9, reference numerals (16Y), (16M), (16C), and (16K) are drum-shaped photoconductors, and the photoconductors are intermediate layers containing at least nitrogen-doped titanium oxide on the support, organic charges. A laminated photosensitive layer comprising a charge generation layer containing a generation material and a charge transport layer containing a charge transport material is provided.

  The photoconductors (16Y), (16M), (16C), and (16K) can be rotated in the direction of the arrow in FIG. 9, and the chargers (17Y), (17M), and (17C) are arranged at least in the order of rotation therearound. , (17K), developing means (19Y), (19M), (19C), (19K) having at least one developing sleeve, cleaning means (20Y), (20M), (20C), (20K), from 410 nm Also, neutralizing means (27Y), (27M), (27C), and (27K) for irradiating short wavelength light are arranged. The chargers (17Y), (17M), (17C), and (17K) are chargers that constitute a charging device for uniformly charging the surface of the photoreceptor. From the surface of the photoreceptor between the chargers (17Y), (17M), (17C), (17K) and the developing means (19Y), (19M), (19C), (19K), an exposure unit (18Y) , (18M), (18C), and (18K) are irradiated with laser light, and electrostatic latent images are formed on the photoreceptors (16Y), (16M), (16C), and (16K). Yes. Then, the four image forming elements (25Y), (25M), (25C), and (25K) centering on such photoconductors (16Y), (16M), (16C), and (16K) serve as transfer materials. They are juxtaposed along the transfer conveyance belt (22) which is a conveyance means. The transfer / conveying belt (22) includes developing means (19Y), (19M), (19C), and (19K) for each image forming element (25Y), (25M), (25C), and (25K) and a cleaning means (20Y). , (20M), (20C), and (20K) are in contact with the photoconductors (16Y), (16M), (16C), and (16K) and hit the back side of the transfer conveyance belt (22) on the photoconductor side. Transfer brushes (21Y), (21M), (21C), and (21K) for applying a transfer bias are arranged on the surface (back surface). Each of the image forming elements (25Y), (25M), (25C), and (25K) is different in the color of the toner inside the developing device, and the others are the same in configuration.

  In the full-color image forming apparatus having the configuration shown in FIG. 9, the image forming operation is performed as follows. First, in each of the image forming elements (25Y), (25M), (25C), and (25K), an electrostatic latent image is formed on the photoconductors (16Y), (16M), (16C), and (16K). It has become. Then, the photoreceptors (16Y), (16M), (16C), and (16K) rotate, and the photoreceptors are charged by the chargers (17Y), (17M), (17C), and (17K). The At this time, in order to form a high-definition latent image, charging is performed so that the electric field strength of the photosensitive member is 20 V / μm or more (60 V μm or less, preferably 50 V / μm or less).

  Next, writing is performed at a resolution of 1200 dpi or more (preferably 2400 dpi or more) with a laser beam by the exposure devices (18Y), (18M), (18C), and (18K) arranged outside the photoconductor, and created. An electrostatic latent image corresponding to each color image is formed. As the writing light source, as described above, a light source suitable for an arbitrary photoconductor is used. In this case as well, 2400 dpi writing is generally the upper limit for one writing light source. Also in this case, it is an effective means to use laser light having an oscillation wavelength shorter than 450 nm as described above.

  Next, the latent image is developed by the developing means (19Y), (19M), (19C), and (19K) to form a toner image. Developing means (19Y), (19M), (19C) and (19K) are developing means for developing with toners of Y (yellow), M (magenta), C (cyan) and K (black), respectively. The toner images of the respective colors formed on the two photoconductors (16Y), (16M), (16C), and (16K) are superimposed on the transfer paper. The transfer paper (26) is fed out from the tray by a paper feeding roller (not shown), temporarily stopped by a pair of registration rollers (23), and transferred and conveyed (22) in synchronization with the image formation on the photosensitive member. ). The transfer paper (26) held on the transfer conveyance belt (22) is conveyed, and each color is in contact with each photoconductor (16Y), (16M), (16C), (16K) (transfer section). The toner image is transferred.

  The toner image on the photoconductor includes transfer bias applied to the transfer brushes (21Y), (21M), (21C), and (21K) and the photoconductors (16Y), (16M), (16C), and (16K). The image is transferred onto the transfer paper (26) by an electric field formed from the potential difference. Then, the transfer paper (26) on which the toner images of four colors are superimposed through the four transfer portions is conveyed to the fixing device (24), where the toner is fixed, and is discharged to a paper discharge portion (not shown).

Further, the residual toner remaining on each of the photoconductors (16Y), (16M), (16C), and (16K) without being transferred at the transfer portion is cleaned by the cleaning means (20Y), (20M), (20C), ( 20K).
Subsequently, excess residual charges on the photosensitive member are removed by the charge eliminating units (27Y), (27M), (27C), and (27K) having a light source having a wavelength shorter than 410 nm. Thereafter, the charging is performed uniformly again by the charger, and the next image formation is performed.

In the example of FIG. 9, the image forming elements are arranged in the order of Y (yellow), M (magenta), C (cyan), and K (black) from the upstream side to the downstream side in the transfer paper conveyance direction. However, the order is not limited to this order, and the color order is arbitrarily set. Further, when creating a black-only document, it is particularly effective to use the present invention to provide a mechanism for stopping image forming elements other than black ((25Y), (25M), (25C)). .
Further, as described above, the surface of the photoreceptor after transfer is preferably charged to 100 V or less on the polarity side charged by the main charger, more preferably charged to the reverse polarity side, and to the reverse polarity side. It is particularly preferable to charge to 100 V or less. Thereby, an increase in the residual potential due to repeated use of the photoreceptor can be reduced.

  The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. The process cartridge is a single device (part) that contains a photosensitive member, and further includes an electrostatic latent image forming unit, a developing unit, a transfer unit, a cleaning unit, a charge eliminating unit, and the like. There are many shapes and the like of the process cartridge, but a general example is shown in FIG. The photoreceptor (101) is provided with a laminated photosensitive layer comprising an intermediate layer containing at least a metal oxide, a charge generation layer containing an organic charge generation material, and a charge transport layer containing a charge transport material on a support. Become.

  As described above, a light source capable of writing with a resolution of 600 dpi or higher is preferably used for the image exposure unit (103), and an arbitrary charger is used for the charger (102). In FIG. 10, (104) is a developing means having at least one developing sleeve, (105) is a transfer member, (106) is a transferring means, (107) is a cleaning means, and (108) is a light source having a wavelength shorter than 500 nm. It is the static elimination means which has.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the following Example at all. All parts are parts by mass.
First, a method for synthesizing the azo pigment and titanyl phthalocyanine crystal used in the present invention will be described. The azo pigments used in the following examples were prepared according to the methods described in Japanese Patent Publication No. 60-29109 and Japanese Patent No. 3026645. Moreover, the titanyl phthalocyanine crystal | crystallization was produced according to Unexamined-Japanese-Patent No. 2001-19871 and Unexamined-Japanese-Patent No. 2004-83859 as shown below.

-Synthesis of titanyl phthalocyanine crystals-
(Synthesis Example 1)
A pigment was prepared in accordance with JP 2001-19871, Synthesis Example 1. That is, 29.2 g of 1,3-diiminoisoindoline and 200 ml of sulfolane are mixed, and 20.4 g of titanium tetrabutoxide is added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C. and 180 ° C. After the reaction is complete, the mixture is allowed to cool, and then the precipitate is filtered, washed with chloroform until the powder turns blue, then washed several times with methanol, then washed several times with hot water at 80 ° C. and dried. Crude titanyl phthalocyanine was obtained. Crude titanyl phthalocyanine is dissolved in 20 times the amount of concentrated sulfuric acid, added dropwise to 100 times the amount of ice water with stirring, the precipitated crystals are filtered, and then ion-exchanged water (pH: 7.) until the washing solution becomes neutral. 0, specific conductivity: 1.0 μS / cm) Repeated washing with water (pH value of ion-exchanged water after washing was 6.8, specific conductivity was 2.6 μS / cm), wet of titanyl phthalocyanine pigment A cake (water paste) was obtained. 40 g of the obtained wet cake (water paste) was put into 200 g of tetrahydrofuran, stirred for 4 hours, filtered and dried to obtain titanyl phthalocyanine powder. This is designated as Pigment 1.
The solid content concentration of the wet cake was 15% by mass. The crystal conversion solvent was used in a mass ratio of 33 times that of the wet cake. In addition, the halogen-containing compound is not used for the raw material of the synthesis example 1.

  The obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions. As a result, the Bragg angle 2θ with respect to Cu-Kα ray (wavelength 1.542Å) was 27.2 ± 0.2 °, and the maximum peak and minimum angle 7 Has a peak at .3 ± 0.2 °, and further has major peaks at 9.4 ± 0.2 °, 9.6 ± 0.2 °, 24.0 ± 0.2 °, and 7 A titanyl phthalocyanine powder having no peak between the peak at 3 ° and the peak at 9.4 ° and further having no peak at 26.3 ° was obtained. The result is shown in FIG.

  A part of the water paste obtained in Synthesis Example 1 was dried at 80 ° C. under reduced pressure (5 mmHg) for 2 days to obtain a low crystalline titanyl phthalocyanine powder. The X-ray diffraction spectrum of the dry powder of water paste is shown in FIG.

<X-ray diffraction spectrum measurement conditions>
X-ray tube: Cu
Voltage: 50kV
Current: 30mA
Scanning speed: 2 ° / min Scanning range: 3 ° -40 °
Time constant: 2 seconds

(Synthesis Example 2)
-Synthesis of titanyl phthalocyanine crystals-
According to the method of JP 2004-83859 A, Example 1, a water paste of titanyl phthalocyanine pigment was synthesized, and crystal conversion was performed as follows to obtain a phthalocyanine crystal having smaller primary particles than the previous synthesis example 1. .
400 parts by mass of tetrahydrofuran was added to 60 parts by mass of the water paste before crystal conversion obtained in Synthesis Example 1 above, and the mixture was vigorously stirred (2000 rpm) with a homomixer (Kennis, MARKIIf model) at room temperature, and the paste was dark blue When the color changed to light blue (20 minutes after the start of stirring), stirring was stopped and filtration under reduced pressure was immediately performed. The crystals obtained on the filter were washed with tetrahydrofuran to obtain a pigment wet cake. This was dried under reduced pressure (5 mmHg) at 70 ° C. for 2 days to obtain 8.5 parts by mass of titanyl phthalocyanine crystals. This is designated as Pigment 2. The raw material of Synthesis Example 2 does not use a halogen-containing compound. The solid content concentration of the wet cake was 15% by mass. The crystal conversion solvent was used in an amount of 44 times by mass ratio to the wet cake.

  Part of the pre-crystallized titanyl phthalocyanine (water paste) prepared in Synthesis Example 1 was diluted with ion-exchanged water to approximately 1% by mass, and the surface was scooped with a copper net that was subjected to conductive treatment, and titanyl phthalocyanine was obtained. Were observed with a transmission electron microscope (TEM, Hitachi: H-9000NAR) at a magnification of 75000 times. The average particle size was determined as follows.

  The TEM image observed as described above is taken as a TEM photograph, and 30 titanyl phthalocyanine particles (a shape close to a needle shape) projected are arbitrarily selected, and the size of each major axis is measured. An arithmetic average of the major diameters of the measured 30 individuals was determined and used as the average particle diameter. The average particle diameter in the water paste (wet cake) in Synthesis Example 1 determined by the above method was 0.06 μm.

  In addition, the titanyl phthalocyanine crystal after crystal conversion just before filtration in Synthesis Example 1 and Synthesis Example 2 was diluted with tetrahydrofuran so as to be about 1% by mass, and observed in the same manner as the above method. The average particle diameter determined as described above is shown in Table 1. In addition, the titanyl phthalocyanine crystal produced in Synthesis Example 1 and Synthesis Example 2 did not necessarily have the same shape of all crystals (a shape close to a triangle, a shape close to a square, etc.). For this reason, the calculation was performed with the length of the largest diagonal line of the crystal as the major axis.

合成例２で作製した顔料２は、先程と同様の方法でＸ線回折スペクトルを測定した。その結果、合成例２で作製した顔料２のＸ線回折スペクトルは、合成例１で作製した顔料１のスペクトルと一致した。

The pigment 2 produced in Synthesis Example 2 was measured for the X-ray diffraction spectrum by the same method as described above. As a result, the X-ray diffraction spectrum of Pigment 2 prepared in Synthesis Example 2 matched the spectrum of Pigment 1 prepared in Synthesis Example 1.

(Dispersion Preparation Example 1)
The pigment 1 prepared in Synthesis Example 1 was dispersed under the following composition under the following conditions to prepare a dispersion as a charge generation layer coating solution.
Titanyl phthalocyanine pigment (Pigment 1) 15 parts Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 10 parts 2-butanone 280 parts All butanone and pigment were added, and the rotor rotation speed was 1200 r. p. m. For 30 minutes to prepare a dispersion. This was designated as Dispersion Liquid 1.

(Dispersion preparation example 2)
A dispersion was prepared under the same conditions as in Dispersion Preparation Example 1, using Pigment 2 prepared in Synthesis Example 2 instead of Pigment 1 used in Dispersion Preparation Example 1. This was designated as Dispersion Liquid 2.

(Dispersion preparation example 3)
The dispersion 1 prepared in Dispersion Preparation Example 1 was filtered using a cotton wind cartridge filter, TCW-1-CS (effective pore size 1 μm) manufactured by Advantech. During filtration, a pump was used and filtration was performed in a pressurized state. This was designated as Dispersion Liquid 3.

(Dispersion preparation example 4)
Dispersion was performed by pressure filtration in the same manner as in Dispersion Preparation Example 3, except that the filter used in Dispersion Preparation Example 3 was changed to Advantech's Cotton Wind Cartridge Filter and TCW-3-CS (effective pore size 3 μm). A liquid was prepared. This was designated as Dispersion Liquid 4.

(Dispersion preparation example 5)
Dispersion was carried out under the conditions shown below with the following composition, to prepare a dispersion as a charge generation layer coating liquid.
5 parts of azo pigment with the following structure

ポリビニルブチラール（積水化学製：ＢＸ−１） ２部
シクロヘキサノン ２５０部
２−ブタノン １００部
ボールミル分散機に直径１０ｍｍのＰＳＺボールを用い、ポリビニルブチラールを溶解した溶媒およびアゾ顔料を全て投入し、回転数８５ｒ．ｐ．ｍ．にて７日間分散を行ない、分散液を作製した（分散液５とする）。

Polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd .: BX-1) 2 parts Cyclohexanone 250 parts 2-butanone 100 parts Using a PSZ ball having a diameter of 10 mm in a ball mill disperser, all of the solvent in which polyvinyl butyral is dissolved and an azo pigment are added, and the rotational speed is 85 r. . p. m. For 7 days to prepare a dispersion (referred to as dispersion 5).

(Dispersion Preparation Example 6)
A dispersion was prepared in the same manner as in Dispersion Preparation Example 5 except that the azo pigment used in Dispersion Preparation Example 5 was changed to one having the following structure (referred to as Dispersion 6).

  The particle size distribution of the pigment particles in the dispersion prepared as described above was measured by HORIBA, Ltd .: CAPA-700. The results are shown in Table 2.

(Photoreceptor Preparation Example 1)
On an aluminum drum (JIS 1050) with a diameter of 30 mm, an intermediate layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition were sequentially applied and dried to obtain a 3.5 μm intermediate layer, 0 A 0.5 μm charge generation layer and a 25 μm charge transport layer were formed to produce a laminated photoreceptor (hereinafter referred to as “electrophotographic photoreceptor 1”).
◎ Intermediate layer coating solution Nitrogen doped titanium oxide (surface untreated; Toyota Tsusho) 112 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 260 parts

Charge generation layer coating solution Dispersion 1 prepared earlier was used.
◎ Charge transport layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula: 7 parts

塩化メチレン ８０部
上記中間層塗工液を用いて、厚さ１ｍｍのアルミ板上に、感光体１と同様に中間層を形成した。市販の分光光度計（島津：ＵＶ−３１００）を用いて、中間層の分光反射スペクトルを測定した。分光反射スペクトルから、中間層の吸収端（吸収可能な長波長側の上限波長）を求め、窒素ドープ酸化チタンの吸収端はおよそ５２０ｎｍと求められた。
窒素ドープ酸化チタン粉体とバインダー樹脂の容積比の算出には、前記のように、窒素ドープ酸化チタンの真比重を４．０とし、また、使用バインダー樹脂のカタログ値の密度を用いた（以下同様）。

80 parts of methylene chloride An intermediate layer was formed in the same manner as the photoreceptor 1 on an aluminum plate having a thickness of 1 mm using the intermediate layer coating solution. The spectral reflection spectrum of the intermediate layer was measured using a commercially available spectrophotometer (Shimadzu: UV-3100). From the spectral reflection spectrum, the absorption edge of the intermediate layer (the upper limit wavelength on the long wavelength side that can be absorbed) was determined, and the absorption edge of nitrogen-doped titanium oxide was determined to be approximately 520 nm.
In calculating the volume ratio of the nitrogen-doped titanium oxide powder and the binder resin, as described above, the true specific gravity of the nitrogen-doped titanium oxide was set to 4.0, and the density of the catalog value of the binder resin used was used (hereinafter referred to as the following). The same).

Example 1
The electrophotographic photosensitive member 1 produced as described above is mounted on an image forming apparatus as shown in FIG. 8, an image exposure light source is a semiconductor laser of 780 nm (image writing by a polygon mirror), a scorotron charger as a charging member, a transfer member A transfer belt was used as a member, and a 470 nm LED (manufactured by Nichia Chemical) was used as a static elimination light source. Process conditions before the test are set as follows, and a chart with a writing rate of 6% (characters equivalent to 6% as an image area are written on the entire A4 surface) is continuously 50,000. Sheet printing was performed.
Photoconductor charging potential (unexposed portion potential): -900V
Development bias: -650V (negative / positive development)
Surface potential after neutralization (unexposed portion of writing light): -100V

The evaluation was performed by measuring the photosensitive member exposed portion potential before and after printing 50,000 images.
As a measuring method, a surface potential meter is mounted at the position of the developing portion shown in FIG. 8, the photosensitive member is charged to −900 V, solid writing is performed with the semiconductor laser, and the surface potential of the unexposed portion at the development site and the exposure The partial potential was measured. The results are shown in Table 3.

(Comparative Example 1)
Evaluation was performed in the same manner as in Example 1 except that the static elimination light source in Example 1 was changed to a 523 nm LED (Rohm: full width at half maximum: 36 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.

(Comparative Example 2)
Evaluation was performed in the same manner as in Example 1 except that the static elimination light source in Example 1 was changed to 591 nm LED (Rohm: full width at half maximum: 15 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.

(Comparative Example 3)
Evaluation was performed in the same manner as in Example 1 except that the static elimination light source in Example 1 was changed to a 630 nm LED (Rohm: half width 20 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.

(Comparative Example 4)
Evaluation was performed in the same manner as in Example 1 except that the static elimination light source in Example 1 was changed to a fluorescent lamp (having the emission spectrum shown in FIG. 1). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.

(Comparative Example 5)
Example 1 and Example 1 except that the static elimination light source in Example 1 was changed to irradiate substantially the same amount of light simultaneously using two of 470 nm LED (manufactured by Nichia) and 630 nm LED (manufactured by ROHM: half-width 20 nm). Evaluation was performed in the same manner. The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.

From Table 3, when the wavelength of the static elimination light is set to 470 nm and light is absorbed by the nitrogen-doped titanium oxide contained in the intermediate layer (Example 1), the longer wavelength (the nitrogen-doped titanium oxide does not absorb light) ) Is used (Comparative Examples 1 to 3), the increase in the potential of the exposed area after repeated use is small.
Further, in the case where the light emission distribution is wide and a component of long wavelength light of 500 nm or more is included (Comparative Example 4), the clear effect as in the example is not obtained. In addition, when two types of light sources having different exposure wavelengths are used (Comparative Example 5), it can be seen that the effect of charge removal by the short wavelength light source is reduced.

(Photosensitive member preparation example 2)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that Dispersion 2 prepared above was used as the charge generation layer coating solution (referred to as electrophotographic photoconductor 2). .

(Example 2)
In Example 1, evaluation was performed in the same manner as in Example 1 except that the electrophotographic photosensitive member 2 was used instead of the electrophotographic photosensitive member 1 used. The results are shown in Table 4.

(Comparative Example 6)
In Comparative Example 1, evaluation was performed in the same manner as in Comparative Example 1 except that the electrophotographic photosensitive member 2 was used instead of the used electrophotographic photosensitive member 1. The results are shown in Table 4.

(Comparative Example 7)
In Comparative Example 2, evaluation was performed in the same manner as in Comparative Example 2 except that the electrophotographic photosensitive member 2 was used instead of the electrophotographic photosensitive member 1 used. The results are shown in Table 4.

(Comparative Example 8)
In Comparative Example 3, evaluation was performed in the same manner as Comparative Example 3 except that the electrophotographic photosensitive member 2 was used instead of the used electrophotographic photosensitive member 1. The results are shown in Table 4.

(Comparative Example 9)
In Comparative Example 4, evaluation was performed in the same manner as in Comparative Example 4 except that the electrophotographic photoreceptor 2 was used instead of the used electrophotographic photoreceptor 1. The results are shown in Table 4.

(Comparative Example 10)
In Comparative Example 5, evaluation was performed in the same manner as in Comparative Example 5 except that the electrophotographic photosensitive member 2 was used instead of the electrophotographic photosensitive member 1 used. The results are shown in Table 4.

  From Table 4, when the wavelength of the static elimination light is set to 470 nm and light is absorbed in titanium oxide (Example 2), a longer wavelength (not absorbed in nitrogen-doped titanium oxide) is used (Comparative Example 6). It can be seen that the increase in the potential of the exposed part after repeated use is small as compared with ˜8). Further, when the emission distribution is wide and a component of long wavelength light of 500 nm or more is included (Comparative Example 9), a clear effect as in the example is not obtained. In addition, when two types of light sources having different exposure wavelengths are used (Comparative Example 10), it can be seen that the effect of charge removal by the short wavelength light source is reduced.

(Photoreceptor Preparation Example 3)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge generation layer coating solution (Dispersion 1) in Photoconductor Preparation Example 1 was changed to Dispersion 3 (referred to as electrophotographic photoconductor 3). .

(Photosensitive member production example 4)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge generation layer coating solution (Dispersion 1) in Photoconductor Preparation Example 1 was changed to Dispersion 4 (referred to as electrophotographic photoconductor 4). .

(Example 3)
Evaluation was performed using the electrophotographic photosensitive member 3 instead of the electrophotographic photosensitive member 1 under the same conditions as in Example 1. Also, after outputting 50,000 images, a solid white image was output to evaluate the background stain. The results are shown in Table 5 together with the results of Examples 1 and 2.

Example 4
Evaluation was performed using the electrophotographic photosensitive member 4 instead of the electrophotographic photosensitive member 1 under the same conditions as in Example 1. Also, after outputting 50,000 images, a solid white image was output to evaluate the background stain. The results are shown in Table 5.

  For the background dirt evaluation, a rank evaluation was performed from the number and size of sunspots generated on the background. The ranking was performed in 4 stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.

  From Table 5, when the average particle diameter of the coating solution used for the charge generation layer is 0.25 μm or less (Examples 2 to 4), the surface potential of the exposed portion in the initial state of the photoreceptor can be lowered and repeatedly used. Later, it can be seen that the occurrence of background contamination can be suppressed without affecting the increase in potential of the exposed portion.

(Photoreceptor Preparation Example 5)
Similar to Photoconductor Preparation Example 1 except that the thickness of the charge transport layer in Photoconductor Preparation Example 1 was 22 μm, a protective layer coating solution having the following composition was applied and dried on the charge transport layer, and a protective layer of 3 μm was provided. A photoreceptor was prepared (referred to as electrophotographic photoreceptor 5).
◎ Protective layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula: 7 parts

アルミナ微粒子 ４部
（比抵抗：２．５×１０^１２Ω・ｃｍ、平均一次粒径：０．４μｍ）
シクロヘキサノン ５００部
テトラヒドロフラン １５０部

4 parts of alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
Cyclohexanone 500 parts Tetrahydrofuran 150 parts

(Photosensitive member preparation example 6)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 5 except that the alumina fine particles in the protective layer coating solution in Photoconductor Preparation Example 5 were changed to the following (referred to as electrophotographic photoconductor 6).
4 parts of titanium oxide fine particles (specific resistance: 1.5 × 10 ¹⁰ Ω · cm, average primary particle size: 0.5 μm)

(Photoreceptor Preparation Example 7)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 5 except that the alumina fine particles in the protective layer coating solution in Photoconductor Preparation Example 5 were changed to the following (referred to as electrophotographic photoconductor 7).
4 parts of tin oxide-antimony oxide powder (specific resistance: 10 ⁶ Ω · cm, average primary particle size 0.4 μm)

(Photoreceptor Preparation Example 8)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member preparation example 5 except that the protective layer coating solution in the photosensitive member preparation example 5 was changed to one having the following composition (referred to as an electrophotographic photosensitive member 8).
◎ Protective layer coating solution 17 parts of polymer charge transport material of the following structural formula (weight average molecular weight: about 140000)

アルミナ微粒子 ４部
（比抵抗：２．５×１０^１２Ω・ｃｍ、平均一次粒径：０．４μｍ）
シクロヘキサノン ５００部
テトラヒドロフラン １５０部

4 parts of alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
Cyclohexanone 500 parts Tetrahydrofuran 150 parts

(Photoreceptor Preparation Example 9)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member preparation example 5 except that the protective layer coating solution in the photosensitive member preparation example 5 was changed to the one having the following composition (referred to as an electrophotographic photosensitive member 9).
◎ Protective layer coating solution Methyltrimethoxysilane 100 parts 3% acetic acid 20 parts Charge transporting compound with the following structure 35 parts

酸化防止剤（サノール ＬＳ２６２６：三共化学社製） １部
硬化剤（ジブチル錫アセテート） １部
２−プロパノール ２００部

Antioxidant (Sanol LS2626: Sankyo Chemical Co., Ltd.) 1 part Curing agent (dibutyltin acetate) 1 part 2-propanol 200 parts

(Photoreceptor Preparation Example 10)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member manufacturing example 5 except that the protective layer coating solution in the photosensitive member manufacturing example 5 was changed to the one having the following composition (referred to as an electrophotographic photosensitive member 10).
◎ Protective layer coating solution Methyltrimethoxysilane 100 parts 3% acetic acid 20 parts Charge transporting compound with the following structure 35 parts

アルミナ微粒子 １５部
（比抵抗：２．５×１０^１２Ω・ｃｍ、平均一次粒径：０．４μｍ）
酸化防止剤（サノール ＬＳ２６２６：三共化学社製） １部
ポリカルボン酸化合物 ＢＹＫ Ｐ１０４：ビックケミー社製 ０．４部
硬化剤（ジブチル錫アセテート） １部
２−プロパノール ２００部

15 parts of alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
Antioxidant (Sanol LS2626: Sankyo Chemical Co., Ltd.) 1 part Polycarboxylic acid compound BYK P104: BYK Chemie 0.4 part Curing agent (dibutyltin acetate) 1 part 2-propanol 200 parts

(Photoreceptor Preparation Example 11)
An electrophotographic photosensitive member was prepared in the same manner as the photosensitive member preparation example 5 except that the protective layer coating solution in the photosensitive member preparation example 5 was changed to the one having the following composition (referred to as an electrophotographic photosensitive member 11).
◎ Protective layer coating solution Trifunctional or more radical polymerizable monomer having no charge transport structure 10 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
10 parts of radically polymerizable compound having a monofunctional charge transporting structure having the following structure (Exemplary Compound No. 54)

光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部
保護層は、スプレー塗工してから２０分間自然乾燥した後、メタルハライドランプ：１６０Ｗ／ｃｍ、照射強度：５００ｍＷ／ｃｍ^２、照射時間：６０秒の条件で光照射を行なうことによって塗布膜を硬化させた。

Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts The protective layer was spray-coated and air-dried for 20 minutes, followed by light irradiation under conditions of a metal halide lamp: 160 W / cm, irradiation intensity: 500 mW / cm ² , irradiation time: 60 seconds. The film was cured.

(Photoconductor Preparation Example 12)
In Photoreceptor Preparation Example 11, all the examples except for changing the trifunctional or higher radical polymerizable monomer having no charge transporting structure contained in the protective layer coating solution to the following radical polymerizable monomer In the same manner as in Example 11, an electrophotographic photosensitive member was produced (referred to as an electrophotographic photosensitive member 12).
10 parts of tri- or higher functional radical polymerizable monomer having no charge transport structure (pentaerythritol tetraacrylate (SR-295, manufactured by Kayaku Sartomer)
(Molecular weight: 352, number of functional groups: 4 functions, molecular weight / number of functional groups = 88)

(Photoreceptor Preparation Example 13)
The trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the protective layer coating solution of Photoreceptor Preparation Example 11 is converted into the following bifunctional radical polymerizable monomer 10 having no charge transporting structure: An electrophotographic photoreceptor was produced in the same manner as in Photoreceptor Preparation Example 11 (except for the parts) (referred to as electrophotographic photoreceptor 13).
10 parts of bifunctional radically polymerizable monomer having no charge transporting structure (1,6-hexanediol diacrylate (manufactured by Wako Pure Chemical Industries))
Molecular weight: 226, number of functional groups: bifunctional, molecular weight / number of functional groups = 113)

(Photoreceptor Preparation Example 14)
In Photoreceptor Preparation Example 11, all the examples except for changing the tri- or higher functional radical polymerizable monomer having no charge transporting structure contained in the protective layer coating solution to the following radical polymerizable monomer In the same manner as in Example 11, an electrophotographic photosensitive member was produced (referred to as an electrophotographic photosensitive member 14).
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 10 parts (Caprolactone-modified dipentaerythritol hexaacrylate (KAYARAD DPCA-120, manufactured by Nippon Kayaku)
(Molecular weight: 1947, number of functional groups: 6 functions, molecular weight / number of functional groups = 325)

(Photoreceptor Preparation Example 15)
10 parts of a radically polymerizable compound having a bifunctional charge transporting structure represented by the following structural formula is included in the protective layer coating solution of Photoreceptor Preparation Example 11 An electrophotographic photoconductor was produced in the same manner as in Photoconductor Production Example 11 except that the electrophotographic photoconductor 15 was used.

(Photoreceptor Production Example 16)
In Photoconductor Preparation Example 11, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 11 except that the protective layer coating solution was changed to the following composition (referred to as electrophotographic photoconductor 16).
◎ Protective layer coating liquid Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 6 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
14 parts of radically polymerizable compound having a monofunctional charge transporting structure having the following structure (Exemplary Compound No. 54)

光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部

Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Photoreceptor Preparation Example 17)
In Photoconductor Preparation Example 11, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 11 except that the protective layer coating solution was changed to the following composition (referred to as electrophotographic photoconductor 17).
◎ Protective layer coating solution Trifunctional or more radical polymerizable monomer having no charge transporting structure 14 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
6 parts of a radical polymerizable compound having a monofunctional charge transport structure having the following structure (Exemplary Compound No. 54)

光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部

Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Photoreceptor Preparation Example 18)
In Photoconductor Preparation Example 11, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 11 except that the protective layer coating solution was changed to the following composition (referred to as electrophotographic photoconductor 18).
◎ Protective layer coating solution Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 2 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
18 parts of a radically polymerizable compound having a monofunctional charge transporting structure having the following structure (Exemplary Compound No. 54)

光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部

Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Photoreceptor Preparation Example 19)
In Photoconductor Preparation Example 11, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 11 except that the protective layer coating solution was changed to the following composition (referred to as electrophotographic photoconductor 19).
◎ Protective layer coating solution Trifunctional or higher functional radical polymerizable monomer having no charge transporting structure 18 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
2 parts of radically polymerizable compound having a monofunctional charge transporting structure having the following structure (Exemplary Compound No. 54)

光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部

Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Example 5)
The electrophotographic photosensitive member 1 produced as described above is mounted on an image forming apparatus as shown in FIG. 8, an image exposure light source is a semiconductor laser of 780 nm (image writing by a polygon mirror), a scorotron charger as a charging member, a transfer member A transfer belt was used as a member, and the following was used as a static elimination light source. Process conditions before the test were set to be as follows, and continuous 70,000 sheets were printed using a chart with a writing rate of 6%.
Photoconductor charging potential (unexposed portion potential): -900V
Development bias: -650V (negative / positive development)
Surface potential after neutralization (unexposed portion of writing light): -100V
Neutralizing light source: A monochromatic light of 450 nm was made by combining a xenon lamp with a spectroscope, which was guided to an image forming apparatus by an optical fiber, and slit-shaped light was irradiated on the surface of the photoreceptor at the static eliminating portion.

<Evaluation items>
(1) Measurement of surface potential Evaluation was made by measuring the potential of the photosensitive member exposed area before and after printing 70,000 images.
As a measuring method, a surface potential meter is mounted at the position of the developing portion shown in FIG. 8, the photosensitive member is charged to −900 V, solid writing is performed with the semiconductor laser, and the surface potential of the unexposed portion at the development site and the exposure The partial potential was measured. The results are shown in Table 6.

(2) Soil evaluation Further, after outputting 70,000 images (after completion of the surface potential measurement), a solid white image was output to evaluate the soil (22 ° C.-50% RH). The background dirt evaluation was performed by the above-described four-level rank evaluation. The results are shown in Table 6.

(3) Evaluation of cleaning property Further, after evaluation of soiling, a black solid portion was obtained under the same conditions as in Example 1 using a test chart as shown in FIG. 13 in a low-temperature and low-humidity environment (10 ° C., 15% RH). The image was output in the direction from solid to white, 50 sheets were continuously printed, and the cleaning property was evaluated. At this time, the image of the 50th white solid portion was visually evaluated. Evaluation is performed in 4 stages, ◎ for very good (no cleaning failure at all), ◯ for good (level with slight black streaks, 1 to 2 in the longitudinal direction), slightly inferior (slightly) The level at which black streaks enter, 3 to 4 places in the longitudinal direction, is indicated by Δ, and the very bad one (level at which black streaks clearly enter) is indicated by ×. The results are shown in Table 6.

(4) Evaluation of dot reproducibility Subsequent to the previous cleaning test, a further sheet passing test (used with the previous 6% char) was conducted in a high temperature and high humidity environment (30 ° C.-90% RH). A one-dot image evaluation (outputting an image in which independent dots were written) was performed after passing the sheet. A one-dot image was observed with an optical microscope, and the clarity of the dot outline was ranked. The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x. The results are shown in Table 6.

(5) Wear amount evaluation The initial film thickness of the photoconductor was measured, and the film thickness was measured again after completing the above tests (1) to (4). The difference in film thickness (amount of wear) before and after all tests was evaluated. The film thickness was measured at intervals of 1 cm, excluding 5 cm at both ends in the longitudinal direction of the photoreceptor, and the average value was taken as the film thickness.

(Examples 6 to 20)
Under the same conditions as in Example 5, the electrophotographic photoreceptors 5 to 19 produced as described above were evaluated. The results are shown in Table 6. Table 6 also shows the used electrophotographic photoreceptor number corresponding to the example number.

Table 6 shows the following.
Even when the protective layer is provided, the effect of preventing the residual potential from rising can be recognized by setting the wavelength of the static elimination light to 450 nm and absorbing the light into the nitrogen-doped titanium oxide contained in the intermediate layer.
By providing the protective layer (Examples 6 to 20), the wear resistance is improved as compared with the case where the protective layer is not provided (Example 5).
Among the cases where a protective layer containing an inorganic pigment (metal oxide) is provided (Examples 6 to 8), the inorganic pigment (metal oxide) having a specific resistance of 10 ¹⁰ Ω · cm or more contains a high temperature. The dot reproducibility does not decrease so much even under high humidity (Examples 6 and 7).
By having the crosslinked structure in the protective layer, the wear resistance is improved as compared with the case where it is not present. Furthermore, in the case of using a protective layer formed by curing a radically polymerizable monomer having three or more functional groups having no charge transporting structure and a radically polymerizable compound having a monofunctional charge transporting structure, High wear resistance is obtained (Examples 12, 13, 15, 17-20).
In addition, when using a protective layer formed by curing a radical polymerizable monomer having a trifunctional or higher functionality not having a charge transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure, The cleaning property is also good.

(Comparative Example 11)
The exposed portion potential was measured and evaluated in the same manner as in Example 15 except that the static elimination light source in Example 15 was changed to 523 nm LED (Rohm: full width at half maximum: 36 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 15. The results are shown in Table 7.

(Comparative Example 12)
The exposed portion potential was measured and evaluated in the same manner as in Example 15 except that the static elimination light source in Example 15 was changed to 591 nm LED (Rohm: half width: 15 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 15. The results are shown in Table 7.

(Comparative Example 13)
Exposed portion potential was measured and evaluated in the same manner as in Example 15 except that the static elimination light source in Example 15 was changed to 630 nm LED (Rohm: half width 20 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 15. The results are shown in Table 7.

(Comparative Example 14)
Exposed portion potential was measured and evaluated in the same manner as in Example 15 except that the static elimination light source in Example 15 was changed to a fluorescent lamp (having the emission spectrum shown in FIG. 1). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 15. The results are shown in Table 7.

From Table 7, when the wavelength of the static elimination light is 450 nm and the light is absorbed in the nitrogen-doped titanium oxide contained in the intermediate layer (Example 15), a longer wavelength is used, and the nitrogen-doped titanium oxide is used. It can be seen that the increase in the potential of the exposed area after repeated use is small as compared with the case of not absorbing (Comparative Examples 11 to 13).
Further, in the case where the emission distribution is wide and a component of long wavelength light of 500 nm or more is included (Comparative Example 14), the clear effect as in the example is not obtained.

(Example 21)
The electrophotographic photosensitive member 14 manufactured as described above is mounted on an image forming apparatus as shown in FIG. 8, and an image exposure light source is a 780 nm semiconductor laser (image writing by a polygon mirror), a scorotron charger as a charging member, a transfer member A transfer belt was used as a member, and the following was used as a static elimination light source. Process conditions before the test were set to be as follows, and continuous 70,000 sheets were printed using a chart with a writing rate of 6%.
Photoconductor charging potential (unexposed portion potential): -900V
Development bias: -650V (negative / positive development)
Surface potential after neutralization (unexposed portion of writing light): -100V
Neutralizing light source: A monochromatic light of 409 nm was made by combining a xenon lamp with a spectroscope, which was guided to an image forming apparatus by an optical fiber, and slit-like light was irradiated on the surface of the photoreceptor at the static eliminating portion.

Evaluation was made by measuring the potential of the photosensitive member exposed area before and after printing 70,000 images.
As a measuring method, a surface potential meter is mounted at the position of the developing portion shown in FIG. 8, the photosensitive member is charged to −900 V, solid writing is performed with the semiconductor laser, and the surface potential of the unexposed portion at the development site and the exposure The partial potential was measured. The results are shown in Table 8.
Further, after the potential measurement was performed after 70,000 sheets were output, a chart as shown in FIG. 14 (the front half was a stripe and the rear half was a halftone) was output, and image unevenness in the halftone portion was observed.

  In order to measure the transmittance of the protective layer, only the protective layer in the electrophotographic photoreceptor 14 was formed on a φ30 mm aluminum drum wrapped with a polyethylene terephthalate film under the same conditions as in the electrophotographic photoreceptor 16. Using a commercially available spectrophotometer (Shimadzu: UV-3100) with a polyethylene terephthalate film without a protective layer cut out to an appropriate size, a spectral transmittance in the range of 500 to 300 nm is obtained. It was measured.

(Example 22)
Evaluation was performed in the same manner as in Example 21 except that the static elimination light wavelength in Example 21 was changed to 393 nm by a spectroscope. The results are shown in Table 8.

(Example 23)
Evaluation was performed in the same manner as in Example 21 except that the static elimination light wavelength in Example 21 was changed to 390 nm by a spectrometer. The results are shown in Table 8.

(Example 24)
Evaluation was performed in the same manner as in Example 21 except that the static elimination light wavelength in Example 21 was changed to 385 nm by a spectrometer. The results are shown in Table 8.

As can be seen from Table 8, when the transmittance of the protective layer against static elimination light is less than 30%, the effect is slightly reduced.
In the chart output of FIG. 14, the halftone portions of Examples 21 to 22 formed a completely normal image. However, in Examples 23 and 24, the level was not a problem, but the halftone portion was striped. A slight afterimage corresponding to was observed. This degree was worse in Example 24 than in Example 23.
From the above results, it is possible to suppress the exposure portion potential increase after repeated use by irradiating the neutralization light of less than 500 nm and causing the nitrogen-doped titanium oxide contained in the intermediate layer to absorb light. It can be seen that if the transmittance with respect to the static elimination light is less than 30%, there may be slight side effects.

(Photoreceptor Preparation Example 20)
The intermediate layer in the photoreceptor preparation example 1 was a laminated structure of a charge blocking layer and a moire preventing layer. Photoconductor Preparation Example 1 except that the charge blocking layer coating solution and the moire prevention layer coating solution having the following composition were applied and dried to obtain a 1.0 μm charge blocking layer and a 3.5 μm moire prevention layer. Similarly, a photoconductor was prepared (referred to as electrophotographic photoconductor 20).
◎ Charge blocking layer coating solution N-methoxymethylated nylon (Lead City: Fine Resin FR-101) 4 parts Methanol 70 parts n-Butanol 30 parts ◎ Moire prevention layer coating solution Nitrogen doped titanium oxide (surface untreated; Toyota) Commerce) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment and the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is 6/4 weight ratio.

(Photoconductor Preparation Example 21)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 20 except that the charge blocking layer thickness was 0.3 μm in Photoconductor Preparation Example 20 (referred to as electrophotographic photoconductor 21).

(Photoconductor Preparation Example 22)
In Photoconductor Preparation Example 20, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 20 except that the thickness of the charge blocking layer was 1.8 μm (referred to as electrophotographic photoconductor 22).

(Photoconductor Preparation Example 23)
In Photoconductor Preparation Example 20, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 20 except that the charge blocking layer coating solution was changed to one having the following composition (referred to as electrophotographic photoconductor 23).
◎ Charge blocking layer coating solution Alcohol-soluble nylon (Toray: Amilan CM8000) 4 parts Methanol 70 parts n-Butanol 30 parts

(Photoconductor Preparation Example 24)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 20 except that the moire-preventing layer coating solution was changed to one having the following composition in Photoconductor Preparation Example 20 (referred to as electrophotographic photoconductor 24).
◎ Moire prevention layer coating solution Nitrogen-doped titanium oxide (surface untreated; Toyota Tsusho) 252 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 3/1.
The ratio of alkyd resin to melamine resin is 6/4 weight ratio.

(Photoconductor Preparation Example 25)
In Photoconductor Preparation Example 20, a photoconductor was prepared in the same manner as Photoconductor Preparation Example 20 except that the moire preventing layer coating solution was changed to one having the following composition (referred to as electrophotographic photoconductor 25).
◎ Moire prevention layer coating solution Nitrogen-doped titanium oxide (surface untreated; Toyota Tsusho) 84 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1/1.
The ratio of alkyd resin to melamine resin is 6/4 weight ratio.

(Examples 25-30)
The electrophotographic photoreceptors 20 to 25 produced as described above were subjected to a running test of 70,000 sheets under the same conditions as in Example 5 (the evaluation method and items were the same). The results are shown in Table 9 in comparison with the case of Example 5.

  From the results of Table 9, it can be seen that the durability against soiling is improved by configuring the intermediate layer as a charge blocking layer and a moire prevention layer.

(Example 31)
In Example 1, evaluation was performed in the same manner as in Example 1 except that the image exposure light source was changed to a 407 nm semiconductor laser (manufactured by Nichia). The results are shown in Table 10 together with the case of Example 1.
A 1-dot image having a diameter of 60 μm was formed and compared with the case of Example 1 (observation of the dot formation state with a 150 × microscope).

  From Table 10, it can be seen that when writing is performed using a short wavelength LD (407 nm) (Example 31), the increase in the potential of the exposed portion is further suppressed as compared with Example 1. Furthermore, in dot evaluation, the outline of the one-dot image of Example 31 was clearer.

(Photoconductor Preparation Example 26)
Similar to Photoreceptor Preparation Example 1 except that the charge generation layer coating solution (Dispersion 1) in Photoreceptor Preparation Example 1 was changed to Dispersion 5 and the charge transport layer coating solution was changed to the following composition. An electrophotographic photoreceptor was prepared (referred to as electrophotographic photoreceptor 26).
◎ Charge transport layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula: 7 parts

塩化メチレン ８０部

80 parts of methylene chloride

(Example 32)
The previously prepared electrophotographic photosensitive member 26 is mounted on a process cartridge as shown in FIG. 10, mounted in an image forming apparatus as shown in FIG. 9, and an image exposure light source is a 655 nm semiconductor laser (image writing by a polygon mirror). ), A contact roller charger as the charging member, a transfer belt as the transfer member, and a 470 nm LED (manufactured by Nichia Chemical) as the charge eliminating light source. Process conditions before the test are set as follows, and a chart with a writing rate of 6% (characters equivalent to 6% as an image area are written on the entire A4 surface) is continuously 50,000. Sheet printing was performed.
Photoconductor charging potential (unexposed portion potential): -900V
Development bias: -650V (negative / positive development)
Surface potential after neutralization (unexposed portion of writing light): -100V

In the evaluation, the photosensitive member exposed portion potential was measured before and after printing 50,000 images (black station).
As a measuring method, a surface potential meter is mounted at the developing portion position shown in FIG. 9, and after charging the photosensitive member to −900 V, solid writing is performed with the semiconductor laser, and the surface potential of the unexposed portion and the exposure at the developing portion are measured. The partial potential was measured. The results are shown in Table 11.
Further, before and after printing 50,000 sheets, an ISO / JIS-SCID image N1 (portrait) was output to evaluate the color color reproducibility.

(Comparative Example 15)
Evaluation was performed in the same manner as in Example 32 except that the static elimination light source in Example 32 was changed to 523 nm LED (manufactured by Seiwa Denki: full width at half maximum: 36 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 32. The results are shown in Table 11.

(Comparative Example 16)
Evaluation was performed in the same manner as in Example 32 except that the static elimination light source in Example 32 was changed to a 591 nm LED (Rohm: half width: 15 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 32. The results are shown in Table 11.

(Comparative Example 17)
Evaluation was performed in the same manner as in Example 32 except that the static elimination light source in Example 32 was changed to 630 nm LED (Rohm: half width 20 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 32. The results are shown in Table 11.

(Comparative Example 18)
Evaluation was performed in the same manner as in Example 32 except that the static elimination light source in Example 32 was changed to a fluorescent lamp (having the emission spectrum shown in FIG. 1). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 32. The results are shown in Table 11.

(Comparative Example 19)
Example 32 and Example 32 except that the static elimination light source in Example 32 was changed to irradiate substantially the same amount of light simultaneously using two of 470 nm LED (manufactured by Nichia) and 630 nm LED (manufactured by ROHM: half-value width 20 nm). Evaluation was performed in the same manner. The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 32. The results are shown in Table 11.

From Table 11, when the wavelength of the static elimination light is set to 470 nm and light is absorbed by the nitrogen-doped titanium oxide contained in the intermediate layer (Example 32), a longer wavelength is used, and the nitrogen-doped titanium oxide is used. It can be seen that the increase in the potential of the exposed area after repeated use is small compared to the case where no light is absorbed (Comparative Examples 15 to 17).
Further, when the emission distribution is wide and a component of long wavelength light of 500 nm or more is included (Comparative Example 18), a clear effect as in the example is not obtained. In addition, when two types of light sources having different exposure wavelengths are used (Comparative Example 19), it can be seen that the effect of charge removal by the short wavelength light source is reduced.
From the results of the test chart, in Example 32, an image almost the same as the initial image was output even after printing 50,000 sheets. In Comparative Examples 15 to 19, the color was printed after printing 50,000 sheets. The image was slightly out of balance.

(Photoconductor Preparation Example 27)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member preparation example 26 except that the charge generation layer coating solution (dispersion liquid 5) in the photosensitive member preparation example 26 was changed to the dispersion liquid 6 (referred to as an electrophotographic photosensitive member 27). ).

(Example 33)
In Example 32, evaluation was performed in the same manner as in Example 34 except that the electrophotographic photosensitive member 27 was used instead of the used electrophotographic photosensitive member 26. The results are shown in Table 12.

(Comparative Example 20)
In Comparative Example 15, evaluation was performed in the same manner as in Comparative Example 15 except that the electrophotographic photosensitive member 27 was used instead of the used electrophotographic photosensitive member 26. The results are shown in Table 12.

(Comparative Example 21)
In Comparative Example 16, evaluation was performed in the same manner as in Comparative Example 16 except that the electrophotographic photosensitive member 27 was used instead of the used electrophotographic photosensitive member 26. The results are shown in Table 12.

(Comparative Example 22)
In Comparative Example 17, evaluation was performed in the same manner as Comparative Example 17 except that the electrophotographic photosensitive member 27 was used instead of the electrophotographic photosensitive member 26 used. The results are shown in Table 12.

(Comparative Example 23)
In Comparative Example 18, the evaluation was performed in the same manner as Comparative Example 18 except that the electrophotographic photosensitive member 27 was used instead of the used electrophotographic photosensitive member 26. The results are shown in Table 12.

(Comparative Example 24)
In Comparative Example 19, evaluation was performed in the same manner as Comparative Example 19 except that the electrophotographic photosensitive member 27 was used instead of the electrophotographic photosensitive member 26 used. The results are shown in Table 12.

From Table 12, when the wavelength of static elimination light is 470 nm and light is absorbed by nitrogen-doped titanium oxide contained in the intermediate layer (Example 33), a longer wavelength is used (Comparative Examples 20 to 20). It can be seen that the increase in the potential of the exposed area after repeated use is small compared to 22).
Further, in the case where the emission distribution is wide and a component of long wavelength light of 500 nm or more is included (Comparative Example 23), a clear effect as in the example is not obtained. In addition, when two types of light sources having different exposure wavelengths are used (Comparative Example 24), it can be seen that the effect of charge removal by the short wavelength light source is reduced.
From the results of the test chart, in Example 33, an image almost the same as the initial image was output even after printing 50,000 sheets. In Comparative Examples 20 to 24, the color was printed after printing 50,000 sheets. The image was slightly out of balance.
Moreover, when the exposed part surface potential of Example 32 described in Table 11 and the exposed part surface potential of Example 33 described in Table 12 are compared, the exposed part surface potential of Example 32 is lower. It can be seen that the asymmetry of the coupler component of the azo pigment used in Example 32 contributes to higher sensitivity.

(Example 34)
In Example 32, evaluation was performed in the same manner as in Example 32 except that the image exposure light source was changed to a 407 nm semiconductor laser (manufactured by Nichia Corporation). The results are shown in Table 13 together with the case of Example 34.
Further, a one-dot image having a diameter of 60 μm was formed and compared with the case of Example 32 (the dot formation state was observed with a 150 × microscope).

  From Table 13, it can be seen that when writing is performed using a short wavelength LD (407 nm) (Example 34), the exposure portion potential rise is further suppressed as compared to Example 32. Furthermore, in dot evaluation, the outline of the one-dot image of Example 34 was clearer.

It is a figure which shows the spectral emission spectrum of a fluorescent lamp. It is a figure showing the layer structure of the electrophotographic photosensitive member used for this invention. It is a figure showing another layer structure of the electrophotographic photosensitive member used for this invention. It is a figure showing another layer structure of the electrophotographic photosensitive member used for this invention. It is a figure which shows the state of the dispersion liquid when dispersion time is short. It is a figure which shows the state of the dispersion liquid when dispersion time is long. It is a figure which shows an average particle diameter and a particle size distribution about the dispersion liquid of FIG. 1 is a schematic view for explaining an electrophotographic process and an image forming apparatus of the present invention. 1 is a schematic view for explaining a tandem-type full-color image forming apparatus of the present invention. FIG. FIG. 4 is a diagram for explaining a process cartridge for an image forming apparatus according to the present invention. 4 is a diagram illustrating an XD spectrum of titanyl phthalocyanine synthesized in Synthesis Example 1. FIG. It is a figure showing the XD spectrum of the dry powder of the water paste (wet cake). 10 is a test chart used in Example 5. FIG. 22 is a test chart used in Example 21. FIG.

Explanation of symbols

(About Figures 2-4)
31 Conductive Support 35 Charge Generation Layer 37 Charge Transport Layer 39 Intermediate Layer 41 Protective Layer 43 Charge Blocking Layer 45 Moire Prevention Layer (Regarding FIG. 8)
DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charger 5 Image exposure part 6 Developing unit 8 Registration roller 9 Transfer paper 10 Transfer charger 11 Separation charger 12 Separation claw 14 Fur brush 15 Cleaning blade (about FIG. 9)
16Y, 16M, 16C, 16K Photoconductors 17Y, 17M, 17C, 17K Chargers 18Y, 18M, 18C, 18K Exposure units 19Y, 19M, 19C, 19K Developing means 20Y, 20M, 20C, 20K Cleaning means 21Y, 21M, 21C , 21K Transfer brush 22 Transfer conveyance belt 23 Registration roller 24 Fixing devices 25Y, 25M, 25C, 25K Image forming element 26 Transfer paper 27Y, 27M, 27C, 27K
DESCRIPTION OF SYMBOLS 101 Photoconductor 102 Charger 103 Image exposure part 104 Developing means 105 Transfer body 106 Transfer means 107 Cleaning means 108 Static elimination means

Claims (23)

An electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and developing the electrostatic latent image with toner to form a visible image Developing means, transfer means for transferring the visible image to the recording medium, fixing means for fixing the transferred image transferred to the recording medium, and static elimination means for photo-staticizing the residual charge of the electrostatic latent image carrier The latent electrostatic image bearing member has a support and a photosensitive layer comprising at least an intermediate layer, a charge generation layer and a charge transport layer on the support, and the intermediate The layer contains at least nitrogen-doped titanium oxide, the charge generation layer contains an organic charge generation material, and the charge removal means is a charge removal means that irradiates light having a wavelength shorter than 500 nm. Image forming apparatus. The image forming apparatus according to claim 1, wherein the nitrogen-doped titanium oxide is not subjected to a surface treatment. The image forming apparatus according to claim 1, wherein the organic charge generating substance is an azo pigment represented by the following formula (I).

(In the formula, Cp ₁ and Cp ₂ represent a coupler residue. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, which may be the same or different. Cp ₁ and Cp ₂ are represented by the following formula (II):

In the formula, R ₂₀₃ represents a hydrogen atom, an alkyl group, or an aryl group. R ₂₀₄ , R ₂₀₅ , R ₂₀₆ , R ₂₀₇ , and R ₂₀₈ each represent a hydrogen atom, a nitro group, a cyano group, a halogen atom, a halogenated alkyl group, an alkyl group, an alkoxy group, a dialkylamino group, or a hydroxyl group, and Z is A group of atoms necessary for constituting a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring. ) The image forming apparatus according to claim 3, wherein Cp ₁ and Cp ₂ of the azo pigment are different from each other. The organic charge generating material has 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 1.542 mm) of CuKα, and further 9.4 °. , 9.6 °, 24.0 °, and the lowest angle diffraction peak at 7.3 °, the 7.3 ° peak and the 9.4 ° peak 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is a titanyl phthalocyanine crystal that does not have a peak between and a peak at 26.3 °. 6. The image forming apparatus according to claim 1, wherein the charge transport layer contains a charge transport material represented by the following formula (III).

Wherein R ₃₀₁ , R ₃₀₃ and R ₃₀₄ are a hydrogen atom, amino group, alkoxy group, thioalkoxy group, aryloxy group, methylenedioxy group, unsubstituted alkyl group, halogen atom or substituted or unsubstituted aryl. R ₃₀₂ represents a hydrogen atom, an alkoxy group, a substituted or unsubstituted alkyl group or a halogen, and k, l, m and n are integers of 1, 2, 3 or 4, each of which is 2, 3 Or when R is an integer of 4, R ₃₀₁ , R ₃₀₂ , R ₃₀₃ and R ₃₀₄ may be the same or different.) The image forming apparatus according to claim 1, further comprising a protective layer on the photosensitive layer. The image forming apparatus according to claim 7, wherein the protective layer transmits at least 30% of the static elimination light. The image forming apparatus according to claim 7, wherein the protective layer includes at least one selected from inorganic pigments and metal oxides having a specific resistance of 10 ¹⁰ Ω · cm or more. The protective layer is formed by curing at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Item 9. The image forming apparatus according to Item 7 or 8. The radical polymerizable compound having a monofunctional charge transporting structure used in the protective layer is at least one selected from the group consisting of compounds of the following general formulas (1) and (2). The image forming apparatus according to claim 10.

{In the formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), halogen Carbonyl group or CONR ₈ R ₉ (R ₈ and R ₉ may have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Represents a good aryl group, which may be the same or different from each other, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group, which may be the same or different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group. m and n represent an integer of 0 to 3. } The image forming apparatus according to claim 10 or 11, wherein the radical polymerizable compound having a monofunctional charge transporting structure used in the protective layer is at least one of the following general formula (3).

(Wherein, o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, Rb and Rc represent a substituent other than a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, And s and t each represents an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,

Represents. ) 13. The image forming apparatus according to claim 10, wherein the protective layer curing means is heating or light energy irradiation means. The image forming apparatus according to claim 1, wherein the intermediate layer includes a charge blocking layer and a moire preventing layer, and nitrogen-doped titanium oxide is contained in the moire preventing layer. The image forming apparatus according to claim 14, wherein the charge blocking layer is made of an insulating material and has a thickness of less than 2.0 μm and 0.3 μm or more. The image forming apparatus according to claim 15, wherein the insulating material is N-methoxymethylated nylon. The image formation according to any one of claims 14 to 16, wherein the moire preventing layer contains nitrogen-doped titanium oxide and a binder resin, and a volume ratio of the two is in a range of 1/1 to 3/1. apparatus. 18. The image forming apparatus according to claim 1, wherein a light source wavelength of image writing light used for the electrostatic latent image forming unit is a light source having a wavelength shorter than 450 nm. 19. The image according to claim 1, comprising a plurality of image forming elements each having at least an electrostatic latent image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, and a charge eliminating unit. Forming equipment. The electrostatic latent image carrier and one or more means selected from an electrostatic latent image forming means, a developing means, a charge eliminating means, and a cleaning means are integrated, and a process cartridge that is detachable from the apparatus main body is mounted. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. An electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier, a developing step of developing the electrostatic latent image with toner to form a visible image, and the visible image An image forming method comprising at least a transfer step for transferring the image to a recording medium, a fixing step for fixing the transferred image transferred to the recording medium, and a static elimination step for photostatic elimination of residual charges on the electrostatic latent image carrier. The electrostatic latent image carrier has a support and a photosensitive layer comprising at least an intermediate layer, a charge generation layer and a charge transport layer on the support, and the intermediate layer contains at least nitrogen-doped titanium oxide. In addition, an image forming method characterized in that the charge generation layer contains an organic charge generation material, and the charge removal step is a charge removal step of irradiating light having a wavelength shorter than 500 nm. The image forming method according to claim 21, wherein a light source wavelength of image writing light used in the electrostatic latent image forming step is a light source having a wavelength shorter than 450 nm. 23. The image forming method according to claim 21, further comprising a plurality of image forming steps including at least an electrostatic latent image forming step, a developing step, a transfer step, and a charge eliminating step.

Images