JP4657153B2 - Image forming apparatus and image forming method - Google Patents

Description

  In the present invention, an electrostatic latent image carrier (having a photosensitive layer composed of an intermediate layer, a charge generation layer and a charge transport layer on a support, and containing an organic charge generation substance in the charge generation layer ( Hereinafter, the present invention relates to an image forming apparatus and an image forming method using an “electrophotographic photoreceptor”, “photoreceptor”, and “photoconductive insulator”.

  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 has a remarkable improvement 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. Furthermore, 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. The big difference is that the entire surface of the document was irradiated with light and this was irradiated onto the photoconductor. 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 original 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, a portion not written by a writing light source (non-image portion, background portion) is an electrostatic latent image carrier (hereinafter referred to as “electrophotographic photosensitive member”) after development and transfer. The surface charge of the “body”, “photosensitive body”, and “photoconductive insulator” may remain, which may affect the next charging, and the charge removal 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 writing is performed uniformly over the entire area of the photosensitive member. (Especially halftone) The original charged potential after writing is almost uniform, but the history of the charged state of the photosensitive member before charging is left, so that the charge distribution becomes uneven. In this state, an electrostatic latent image is formed, and when 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 with the photoconductor and charges the surface of the photoconductor due to a bias difference between the two, but if the surface charge on the photoconductor before charging is non-uniform, the history will be recorded at the next charging. 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, so that 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 photosensitive member 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 a trap 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 negative / positive development, the non-exposed portion of the photoconductor (the portion where writing is not performed) is substantially neutralized, so if the document is the same as above, it is close to 90% of the total 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 cancellation ratio 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) on the photosensitive member in the static elimination process have not been made so much, and the actual situation is that it has been used as it is.

  As a prior art relating to a charge eliminating member, an inorganic photoreceptor (Se, a-Si) is used in Patent Document 1 (Japanese Patent Laid-Open No. 60-88981) or 2 (Japanese Patent Laid-Open No. 62-87981). In the image forming apparatus described above, there is a description that light fatigue and charging fatigue can be prevented by irradiating with appropriate neutralizing light including light having a short wavelength. However, the photoconductor used in Patent Document 1 or 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. Inorganic technology (photo static elimination) cannot be applied horizontally to organic photoreceptors. 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 conducting an experiment by applying the technique of Patent Document 1 or 2, the effect of suppressing the increase in residual potential was not sufficient.

  In Patent Document 3 (Japanese Patent Laid-Open No. 61-36784), exposure is performed at a wavelength that substantially matches the intrinsic photosensitive wavelength of a dye-sensitized photoconductor, in other words, the wavelength of a region where no sensitizing dye is absorbed. 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, the photocarrier generation efficiency in this wavelength band is low, and not only charge removal cannot be performed efficiently, but also photodegradation of polyvinyl carbazole, etc., which may not necessarily 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 used for negative / positive development, 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 the decrease in sensitivity due to light fatigue by performing. 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. Cases arise. It is important to have sufficient photosensitivity for the static elimination light, and the technique of Patent Document 4 cannot be applied to the current image forming apparatus. In Patent Document 4, the neutralization wavelength is not specified.

  In Patent Documents 5 (Japanese Unexamined Patent Publication No. 1-2217490) and 6 (Japanese Unexamined Patent Publication No. 1-274186), light having a wavelength of 620 nm or less is applied to a positively charged photoreceptor in which a charge generation layer is laminated on a charge transport layer. There is a statement that neutralization is performed by irradiation 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 conducting 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 this is done efficiently. In general, a practical organic pigment has an absorption peak in the visible range, and therefore, the technique of Patent Document 8 cannot obtain a sufficient effect for increasing the 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 removal wavelength differs depending on the photosensitive material used, and the charge removal 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 500 nm or less 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 when the single-layer photosensitive member is repeatedly used. 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. I can't. 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 the laminated photoconductor, 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 addition, this publication describes that a fluorescent lamp is used as a static elimination light source in order to realize this.
Furthermore, Patent Document 12 (Japanese Patent Application Laid-Open No. 2004-45997) describes performing static elimination with a fluorescent lamp on a photoreceptor containing a phthalocyanine compound.
FIG. 1 shows a spectral emission spectrum of light from a fluorescent lamp. 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 of FIG. 1, the light of the fluorescent lamp irradiated on the photosensitive member is mainly light in the above wavelength range (500 to 650 nm). It will be irradiated.

  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 means that the charge removal by the red LED light of 680 nm and the charge removal by the light emission from 500 to 650 nm are compared. Since the light corresponding to the phthalocyanine Sore band is not zero, it is true that the Sore band is irradiated with light. It will be big.

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. Further, with regard to high durability, extending the life of the photoreceptor is the most effective method.
There are various approaches to solve 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 an increase in residual potential (exposure portion potential) during repeated use.

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

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide an image forming apparatus and an image forming method capable of suppressing an increase in residual potential in repeated use of a photoreceptor and forming a highly durable and high-definition image.

The inventors of the present invention have studied how the process condition affects the electrostatic fatigue of the photoreceptor, particularly the increase in the 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 by attaching a transfer member so that a reverse bias could be applied to the photoconductor before the charge eliminating 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 substantially 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 the light irradiation to the photoconductor consists of two types of writing light and static elimination light.

Generally, an image forming apparatus that performs digital writing currently uses negative / positive development. This is due to the fact that most of the writing rate of the actual document is 10% or less, and the purpose is to reduce the 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 time of 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 remaining 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, and basically all negative / positive images are output except when only originals that are continuously written on the entire surface are output. This is true for image forming apparatuses that use development. However, as described above, the actual situation is that the analysis from the process side regarding the electrostatic fatigue of the photoreceptor has not been performed so much.
The present inventor examined the control by process conditions for the increase in residual potential (exposure portion potential) in the repeated use of the photosensitive member. As described above, the static elimination process in image formation has a great influence. 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, carrier movement or charge in 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 out 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 microseconds as a transit time. 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.
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.

  The present inventor questioned whether the neutralization by irradiating light of a relatively long wavelength such as the red LED is optimal for repeated use of the photoreceptor, and examined the wavelength dependence of the neutralization light. Specifically, various wavelengths were produced by combining a monochromatic laser beam or an appropriate light source and a filter, and studies were made on the increase in residual potential in repeated use of the photoreceptor.

  As a result, it has been found that red static elimination, which has been considered to be good in the past, raises the residual potential rather than irradiating light with a shorter wavelength. Specifically, it has been found that an increase in the residual potential can be significantly suppressed by performing neutralization with light having such a wavelength that the intermediate layer can absorb the neutralization light. More specifically, the neutralization is performed by light having a wavelength shorter than 500 nm and light having a wavelength that allows the metal oxide contained in the intermediate layer to absorb light. In this experiment, the amount of charge passing through the photoconductor per unit time at the time of static elimination is adjusted, so the amount of static elimination light applied to the photoconductor is determined by the spectral absorption spectrum profile of the photoconductor (charge generation material). Although it changes, the light absorption amount of the photosensitive layer does not change. Therefore, it was understood that the above result was due to the influence of the wavelength dependency of the static elimination light.

  On the other hand, the charge transport materials that have been developed so far are intended to be used for photoconductors that use fluorescent light sources even at the shortest wavelength, and light close to the ultraviolet region as described above is cut off by a suitable filter. Have been used. This is because most of the charge transport materials have absorption on the shorter wavelength side than 500 nm, and when irradiated with high energy light such as ultraviolet rays, it causes deterioration of the material (decomposition, conversion to other substances, etc.) This is because it adversely affects the electrostatic characteristics of the photoreceptor.

However, when a light source having a wavelength shorter than 500 nm is used as in the present invention to perform photostatic discharge from the surface of the photoreceptor, most of the charge is absorbed by the charge transport layer, which is the essence of photostatic discharge. As a result, the light neutralization efficiency is remarkably lowered. In order to cover this, it is conceivable to increase the amount of light elimination, but this will increase the amount of light absorption in the charge transport layer, which not only causes a large energy loss, but also promotes the deterioration of the charge transport layer. become.
Therefore, the material used for the charge transport layer is selected by taking into consideration the level of absorption of the charge transport material with respect to the static elimination light, the strength of the charge transport material itself with respect to light, and the like. This clearly limits the degree of freedom in photoreceptor design. Even if a material having a lower absorption is used, the charge transporting substance concentration in the charge transporting layer is generally about 40% by weight, so that the writing light is absorbed almost in the shallowest part of the outermost surface. For this reason, in a photoreceptor having a layered structure of a charge generation layer / charge transport layer, when the charge transport layer side is neutralized with a short wavelength light source as in a known technique, the charge transport material is not deteriorated completely. It is not avoidable.

  As a result of examination on this point, by using a photoconductor using a support transparent to static elimination light, by irradiating static elimination light from the inside of the photoconductor, by reducing the light irradiation to the charge transport material as much as possible It has been found that it is possible to suppress the deterioration of the charge transport material as much as possible. Further, according to this method, even if a charge transport material having a large absorption with respect to the static elimination light is used, the side effect of reducing the photosensitivity does not occur, and rather, the selection of a material independent of the absorption wavelength of the charge transport material is possible. It becomes possible.

  By further applying this point, the following developments became possible. That is, the use of a polymer charge transport material is effective for improving the abrasion resistance of the photoreceptor, but when a short wavelength light source is used as the charge eliminating light and the charge removal exposure is performed from the photoreceptor surface side, the polymer charge transport material is used. There may be a case where the photosensitivity is lowered due to light absorption of the substance (decrease in static elimination efficiency) and the polymer charge transporting substance is degraded (for example, main chain cleavage of polysilane by ultraviolet rays). On the other hand, by performing static elimination exposure from the back surface side, the above disadvantages can be prevented and the original advantages of the polymer charge transport material can be utilized. In addition, when a surface protective layer is used, when a short wavelength light source is used and exposure is performed from the surface side of the photoreceptor, there may occur a decrease in sensitivity due to light scattering due to a filler added for wear resistance. . Again, by performing exposure from the back side, it is possible to prevent the above disadvantages. Further, in any case, it is not necessary to consider the shielding of static elimination light, etc., and the range of material selection is widened, so that the original wear resistance of the material / configuration can be sufficiently functioned, so that the photosensitive layer or protective layer Can also be made thinner.

Obtaining the above knowledge, the present inventors have completed the present invention.
That is, a metal oxide is contained in an intermediate layer in an electrostatic latent image carrier having an intermediate layer, a laminated photosensitive layer composed of a charge generation layer and a charge transport layer on a translucent support that transmits at least static elimination light, When the charge generation layer contains an organic charge generation material, and the neutralization light source uses a light source having a wavelength shorter than 500 nm and capable of absorbing a metal oxide, the photoreceptor can be used repeatedly in an image forming apparatus. The present inventors have found that the residual potential rise in the substrate can be suppressed, found that image formation with few abnormal images can be stably performed, and found that the above problems can be solved.

The present invention is based on the above knowledge of the present inventor, and means for solving the above problems are as follows. That is,
(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 to make it visible Development means for forming an image, transfer means for transferring the visible image to a recording medium, fixing means for fixing the transferred image transferred to the recording medium, and residual charge of the electrostatic latent image carrier are photo-discharged An image forming apparatus having at least a charge eliminating unit, wherein the electrostatic latent image carrier includes a translucent support that transmits charge removal light, and at least an intermediate layer, a charge generation layer, and a charge transport layer on the support. The intermediate layer contains at least a metal oxide, and the charge generation layer contains an organic charge generation material, and the charge eliminating means has a wavelength shorter than 500 nm and an intermediate layer. Light with a wavelength that can be absorbed by the metal oxide contained in the Image forming apparatus which is a discharging means for morphism.

(2) The image forming apparatus as described in (1) above, wherein a light source used for the charge eliminating unit is an LD or an LED.
(3) The image forming apparatus according to (1) or (2), wherein the metal oxide is not subjected to surface treatment.

(4) In the latent image carrier, the intermediate layer is composed of a charge blocking layer and a moire preventing layer, and the metal oxide is contained in the moire preventing layer. (1) to (3) The image forming apparatus according to any one of the above items.
(5) The image forming apparatus according to (4), 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.
(6) The image forming apparatus as described in (5) above, wherein the insulating material is N-methoxymethylated nylon.
(7) The items (4) to (6), wherein the moire preventing layer contains a metal 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 the items.

(8) The image forming apparatus according to any one of (1) to (7), wherein a protective layer is provided on the charge transport layer.
(9) The image forming apparatus according to (8), 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.
(10) 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. The image forming apparatus according to item (8).

(11) The above-mentioned (10), 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 (1) or (2). The image forming apparatus described in the item.
{Wherein 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 each 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 above-mentioned item (10) or (), wherein the radically polymerizable compound having a monofunctional charge transporting structure used in the protective layer is at least one of the following general formula (3). The image forming apparatus according to item 11).
(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 any one of (10) to (12), wherein the protective layer curing means is heating or light energy irradiation means.
(14) The image forming apparatus according to any one of (1) to (1), wherein the image forming apparatus includes a second charge eliminating unit that irradiates light having a wavelength longer than 500 nm from the surface layer side of the electrostatic latent image carrier. The image forming apparatus according to any one of 13).
(15) Any one of (1) to (14) above, wherein the light source wavelength of the image writing light used for the electrostatic latent image forming means is a light source having a wavelength shorter than 450 nm. The image forming apparatus described in 1.

(16) Item (1) to Item (15), 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, and a charge eliminating unit. The image forming apparatus according to any one of the above.
(17) The 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, and a process cartridge that is detachable from the apparatus main body is mounted. The image forming apparatus according to any one of (1) to (16), characterized in that:

(18) An electrostatic latent image carrier, an electrostatic latent image forming step for forming an electrostatic latent image on the electrostatic latent image carrier, and developing the electrostatic latent image with toner to make it visible A developing step for forming an image, a transferring 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 residual charge on the electrostatic latent image carrier is photostatically removed. An image forming method comprising at least a charge eliminating step, wherein the latent electrostatic image bearing member has a translucent support that transmits charge eliminating light, and at least an intermediate layer, a charge generation layer, and a charge transport layer on the support. The intermediate layer contains at least a metal oxide, and the charge generation layer contains an organic charge generation material, and the charge eliminating means has a wavelength shorter than 500 nm and an intermediate layer. Light having a wavelength that can be absorbed by the metal oxide contained in the inside of the electrostatic latent image carrier Image forming method which is a charge eliminating step of irradiating.

(19) The image forming method according to (18), wherein the image forming method includes a second charge eliminating step of irradiating light having a wavelength longer than 500 nm from the surface layer side of the electrostatic latent image carrier. Image forming method.
(20) The image as described in (18) or (19) above, 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. Forming method.
(21) Item (18) to Item (20), comprising a plurality of image forming elements having at least an electrostatic latent image carrier, an electrostatic latent image forming step, a developing step, and a charge eliminating step. The image forming method according to any one of the above.

  According to the study of the present inventor, 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 (metal oxide) is irradiated with light having 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 (metal 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, the wavelength that can be absorbed by the metal oxide as the static elimination light is the energy corresponding to the width of the forbidden band of the metal oxide (also referred to as the energy gap between the conduction band and the valence band). Is also defined as a wavelength having a large energy (short wavelength). That is, in the case of titanium oxide (rutile type), the energy gap is 3.0 eV, which is about 410 nm in terms of wavelength. This is the wavelength on the longest wavelength side where titanium oxide (rutile type) can be absorbed, and light having a wavelength shorter than 410 nm can be absorbed by 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 the metal 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, three methods are conceivable.
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.

The second is a method of obtaining the spectral absorption spectrum and emission spectrum of the intermediate layer, describing them in the same graph, and obtaining the wavelength at the intersection of the two. 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.

A detailed mechanism that can suppress an increase in residual potential in repeated use of the photoreceptor by using a neutralizing light with a wavelength that can be absorbed by the metal oxide has not been clarified. At present, the mechanism is considered as follows.
In repeated use of the photoconductor, if the charge is removed by light having a wavelength longer than the wavelength that the metal oxide can absorb, 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 that is the subject of the present invention, electron transport in the intermediate layer is slower than hole transport in the charge transport layer, so that electrons accumulate in the intermediate layer with repeated use.

On the other hand, when static elimination is performed with light having a wavelength that can be absorbed by the metal oxide, the metal oxide contained in the intermediate layer absorbs light and generates a photocarrier via a photoexcited state. In this case, it is efficient because it is formed of an intermediate layer and there is no injection process from the charge generation layer. 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.
In general, the organic charge generation material used in the charge generation layer has absorption in the visible region, but it cannot be said that there is no absorption below 500 nm due to its structure. Can sufficiently generate photocarriers. 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 support on which the intermediate layer is formed needs to sufficiently transmit light having a wavelength that can be absorbed by the metal oxide contained in the intermediate layer.

  According to the present invention, it is an image forming apparatus that can solve various problems in the prior art and can perform high-durability and high-quality image formation. On the translucent support that transmits at least static elimination light, the intermediate layer, the charge The intermediate layer in the electrostatic latent image bearing member having a multilayer photosensitive layer comprising a generation layer and a charge transport layer contains a metal oxide, the charge generation layer contains an organic charge generation material, and the charge removal light source has a thickness of more than 500 nm. The image forming apparatus uses a light source having a short wavelength and a wavelength that can be absorbed by the metal oxide contained in the intermediate layer. 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 comprises a laminated photosensitive layer comprising an intermediate layer containing a metal oxide, a charge generation layer containing an organic charge generation material, and a charge transport layer on a translucent support that transmits at least static elimination light. An electrostatic latent image bearing member, an electrostatic latent image forming unit, a developing unit, a transfer unit, a fixing unit, and a metal oxide contained in the intermediate layer at a wavelength shorter than 500 nm can be absorbed. At least a static elimination unit having a light source of a wavelength, and further, other units appropriately selected as necessary, for example, a cleaning unit, a recycling unit, a control unit, and the like.
The image forming method of the present invention comprises an electrostatic latent image forming step, a developing step, a transfer step, a static elimination light source having a wavelength shorter than 500 nm and capable of absorbing the metal oxide contained in the intermediate layer. The process includes at least a process and a fixing process, and further includes other processes appropriately selected as necessary, for example, a cleaning process, a recycling process, a control process, and the like.

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.
The 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 forming 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 A fixing unit for fixing the transferred image, and the neutralizing unit has a light source having a wavelength shorter than at least 500 nm and capable of absorbing the metal oxide contained in the intermediate layer. The electrostatic latent image carrier is irradiated with static elimination light.

-Electrostatic latent image carrier-
As the electrostatic latent image carrier, it is essential to use a translucent support capable of transmitting static elimination light and to provide at least a charge generation layer containing an organic charge generation material on the support. Other than the above, the material, shape, structure, size, etc. are not particularly limited, and can be appropriately selected from known ones.

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 translucent support (31), an intermediate layer (39) containing a metal oxide and a charge generating substance. The charge generation layer (35) containing at least an organic charge generation material as a main component and the charge transport layer (37) including a charge transfer material as a main component are stacked.
FIG. 3 is a cross-sectional view showing another structural example of the electrophotographic photosensitive member used in the present invention. On the translucent support (31), the intermediate layer (39) has a charge blocking layer (43) and a metal. A charge generation layer (35) composed of an oxide-containing moire prevention layer (45) and having an organic charge generation material as a main component at least as a charge generation material on the intermediate layer, and a charge having a charge transport material as a main component The transport layer (37) has a laminated structure.

  FIG. 4 is a sectional view showing still another structural example of the electrophotographic photosensitive member used in the present invention. On the translucent support (31), an intermediate layer (39) containing a metal 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, and a charge transport layer (photosensitive layer). The protective layer (41) is provided on the top.

  The translucent support 31 is not particularly limited as long as it transmits static elimination light. For example, glass (pyrex (registered trademark) glass, borosilicate glass, soda glass, etc.), transparent such as quartz, sapphire, etc. It is made of a transparent resin such as inorganic material, fluororesin, polyester, polycarbonate, polyethylene, polyethylene terephthalate, vinylon, epoxy. Moreover, the support body described in Unexamined-Japanese-Patent No. 2000-29234, Unexamined-Japanese-Patent No. 2000-39732, Unexamined-Japanese-Patent No. 2000-75532, etc. can also be used. In such a support, conductivity is essential. Therefore, when the support itself is an insulator, it is necessary to provide a conductive layer on the surface of the support or to conduct a conductive treatment. As the conductive layer, a transparent conductive material such as ITO (indium tin oxide), lead oxide, indium oxide, copper iodide or the like is formed directly or dispersed on a resin, or formed on the surface, or aluminum, nickel, gold, hastelloy, etc. The metal may be formed thin enough to be translucent. When the conductive layer is provided, it can be provided by a method such as sputtering or a wet method. When a metal is provided on the surface, a vapor deposition method or sputtering is used.

There is no restriction | limiting in particular as a shape of a translucent support body, A cylindrical thing and the thing on a film are used. However, in order to perform static elimination from the inner surface side, the inside of the support is preferably smooth.
Note that the transmission of charge removal light is defined as that the transmittance of charge removal light is 95% or more when the support is irradiated with charge removal light. At this time, it is ideally 100% to transmit.

  Next, the intermediate layer 39 will be described. It is essential that the intermediate layer used in the present invention contains a metal 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 a metal oxide for the purpose of reducing the residual potential, etc., but this also has the effect of preventing moire. Examples of the metal oxide include titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide, and zinc oxide. Among these, titanium oxide, tin oxide, and zinc oxide are effectively used. Among the titanium oxides, rutile type titanium oxide and nitrogen-doped titanium oxide are preferable. Anatase-type titanium oxide can also be used, but considering the generation of photocarriers (light absorption), the anatase type has an absorption wavelength region on the shorter wavelength side than the rutile type, and it is necessary to make the neutralizing light the shorter wavelength side. Comes out. In this case, when the spectral transmittance of the charge transport layer is taken into consideration, when the anatase type is used, restrictions on the charge transport material that can be used may occur as compared with the case where the rutile type is used. For this reason, the rutile type is more advantageous. Nitrogen-doped titanium oxide is present in the form of TiO _2−X N _X by adding nitrogen to titanium oxide. The feature of this material is that the absorption wavelength is increased while maintaining the photocatalytic performance of titanium oxide. The absorption edge (absorption on the longest wavelength side that can be absorbed) extends to approximately 520 nm, which is most advantageous in terms of selectivity of the light source.

Moreover, the metal oxide to be used is advantageously one that has not been subjected to surface treatment. This is because the surface treatment reduces the surface area of the unmodified metal oxide, which acts in a disadvantageous direction in transporting carriers generated from the metal oxide. Thereby, the effect of this invention may be reduced. If a surface treatment is desired for reasons such as dispersion stability, it should be the minimum amount necessary.
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.

  The intermediate layer 39 has the function of preventing injection of reverse polarity charges induced on the electrode side during charging of the photoconductor into the photosensitive layer in addition to the generation of photocarriers during static elimination, and writing with coherent light such as laser light. It has at least two functions of preventing moiré that sometimes occurs. 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. Hereinafter, the function separation type intermediate layer of the charge blocking layer 43 and the moire preventing layer 45 will be described.

  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.

Usable binder resins 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.). A thermosetting resin obtained by thermally polymerizing a compound containing a plurality of (hydrogen) and a compound containing a plurality of isocyanate groups and / or a compound containing a plurality of epoxy groups can also 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. System resin and the like. Examples of the compound containing a plurality of isocyanate groups include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and prepolymers thereof. Examples of the compound having a plurality of epoxy groups include bisphenol A type epoxy resin. can give. 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 is a polyamide containing polyamide 6 as a constituent, for example, T.I. L. It can be obtained by modification by the method proposed by Cairns (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, for example, copolymer nylon such as nylon 6/66/610 is disclosed in JP-A-9-265202. Contrary to the contents, it was not very preferable.

Further, 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 temperatures 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, nozzle coating, etc. It is formed. After the coating, it is dried or cured by a curing process such as drying, heating, or light.

  The moiré prevention layer 45 is a layer having a function of preventing the generation of a moiré 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-separated configuration, a metal 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.
Further, in the photoconductor having the function separation type intermediate layer, the charge blocking layer prevents the charge injection from the support 31, and therefore, in the moire prevention layer, at least the charge charged on the surface of the photoconductor has the same polarity. From the viewpoint of preventing residual potential, it is preferable to have a function of transferring the electric charge. 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 metal oxide to be used should be one that has electron conductivity or a conductive one. It is desirable to do. 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 (charge generation layer 35, charge transport layer 37) on the moire prevention layer, the photosensitive layer (charge generation layer, It is important not to be affected by the coating solvent for the charge transport layer.
As the binder resin, a thermosetting resin is preferably used. In particular, alkyd / melamine resin mixtures are best used. At this time, the mixing ratio of alkyd / melamine resin is an important factor for determining the structure and characteristics of the moire prevention layer. A range in which the ratio (weight ratio) of both is 5/5 to 8/2 can be cited as a good range of the mixing ratio. If 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. Further, if the alkyd resin is richer than 8/2, it is effective in reducing the residual potential of the photoreceptor, but it is not desirable because the bulk resistance becomes too low and the soiling becomes worse.

  In the moiré prevention layer, the volume ratio between the metal oxide and the binder resin determines an important characteristic. For this reason, it is important that the volume ratio of the metal 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 are cases where the binder resin cannot cover the metal oxide surface, and the direct contact with the charge generating material increases the probability of heat carrier generation, resulting in soil contamination. May be adversely affected.

  Furthermore, by using two kinds of metal oxides having different average particle diameters for the moire prevention layer, it is possible to improve the hiding power on the conductive substrate and suppress moire and cause abnormal images. Pinholes can be eliminated. For this purpose, it is important that the ratio of the average particle diameters of the two types of metal oxides 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 metal oxide (T2) with respect to the average particle size (D1) of the metal oxide (T1) having a large average particle size. When the ratio is too small (0.2 ≧ D2 / D1), the activity on the surface of the metal oxide is increased, and the electrostatic stability of the electrophotographic photosensitive member is significantly impaired. Further, when the ratio of the average particle diameter of the other metal oxide (T2) to the average particle diameter of one metal oxide (T1) is too large (D2 / D1> 0.5), the hiding power to the conductive substrate Decreases, and the suppression of moiré and abnormal images decreases. The average particle size mentioned here is obtained from a particle size distribution measurement obtained when strong dispersion is performed in an aqueous system.

In addition, the average particle size (D2) of the metal 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 metal oxide filling rate of the moire prevention layer is lowered, and the background stain suppressing effect cannot be sufficiently exhibited.
The mixing ratio (weight ratio) of the two metal oxides is also an important factor. When T2 / (T1 + T2) is smaller than 0.2, the filling rate of the metal 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.

  The metal 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., and a chemical, a solvent, an additive, a curing accelerator, etc. necessary for curing (crosslinking) are added as necessary. In general, it is formed on the substrate by blade coating, dip coating, spray coating, beat coating, nozzle coating, or the like. 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 includes a charge generation layer 35 containing an organic charge generation material as a charge generation material and a charge transport layer 37 stacked structure.
The charge generation layer 35 is a layer mainly composed of an organic charge generation material. 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 a translucent support and drying Is done.

An organic material can be used as the charge generation material.
A known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having a carbazole skeleton, azo pigments having a 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 (XVII) 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.
(XVII) In the formula, Cp ₁ and Cp ₂ represent coupler residues. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, and may be the same or different. Cp ₁ and Cp ₂ are represented by the following formula (XVIII):
In the formula (XVIII), 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. _R204 , _R205 , _R206 , _R207 , and _R208 are each a hydrogen atom, a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, bromine, or iodine, a trifluoromethyl group, a methyl group, or an ethyl group. Represents an alkoxy group such as an alkyl group, a methoxy group or an ethoxy group, a dialkylamino group, or a hydroxyl group, and Z is an atom necessary for constituting a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring Represents a group.

  In addition, titanyl phthalocyanine can be effectively used as the charge generating material of the present invention. In particular, 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 of CuKα, and has a maximum diffraction peak at 27.2 °. Further, it has major peaks at 9.4 °, 9.6 °, and 24.0 °, and has a peak at 7.3 ° as the lowest diffraction peak, and the peak at 7.3 ° A titanyl phthalocyanine crystal that does not have a peak between 9.4 ° and further has no peak at 26.3 ° has a large carrier generation efficiency and can be used effectively as a charge generating material of the present invention.

  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 thickness of the charge generation layer is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.

  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 production method thereof will be described 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 only the dispersion time is changed while fixing the dispersion conditions. 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, it is observed that 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.
For the preparation of the dispersion, a general method is used, and it is obtained by dispersing the charge generating substance in a suitable solvent together with a binder resin as necessary using a ball mill, an attritor, a sand mill, a bead mill, an ultrasonic wave, or the like. It is what 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.

  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. 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, it is possible to produce a dispersion containing only charge generation material particles having a small particle size (0.25 μm or less, preferably 0.2 μm or less), 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 carry out dispersion until the average particle size is 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.

  Many of the charge generating materials used in the present invention have extremely strong intermolecular hydrogen bonding force, which is a characteristic of charge generating materials exhibiting highly sensitive characteristics. For this reason, the interaction between the dispersed pigment particles is very strong. As a result, there is a great possibility that the charge generation material particles dispersed by a disperser etc. are re-aggregated by 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 can be formed by dissolving or dispersing a charge transport material and a binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. 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.

Among these, substances represented by the following general formulas (I) to (VI) are particularly effectively used.
(In the formula (I), R ₈ , R ₉ and R ₁₀ are each a hydrogen atom, an amino group, an alkoxy group, a thioalkoxy group, an aryloxy group, a methylenedioxy group, a substituted or unsubstituted alkyl group, a halogen atom, Or a substituted or unsubstituted aryl group, m represents an integer of 1 to 3)

(In the formula (II), R ₅ represents a lower alkyl group, a lower alkoxy group or a halogen atom, l represents an integer of 0 to 4, R ₆ and R ₇ may be the same or different, and may be a hydrogen atom, Represents a lower alkyl group, a lower alkoxy group or a halogen atom.)

(In the formula (III), R ₁ , R ₂ , R ₃ and R ₄ represent a hydrogen atom, a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted aryl group, and Ar ₁ represents a substituted or unsubstituted aryl. Represents a group, Ar ₂ represents a substituted or unsubstituted arylene group, R ₁ and Ar ₁ may form a ring together, and k is an integer of 0 or 1.)

(In formula (IV), A ₁ and A ₂ each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, which may be the same or different. Ar ₃ represents a substituted or unsubstituted condensed poly group. Represents a cyclic hydrocarbon group.)

(In the formula (V), Ar ₄ represents an aromatic group, R ₁₁ represents a hydrogen atom, a substituted or unsubstituted alkyl group or an aryl group, p is 0 or 1, q is 1 or 2, and p = When 0 and q = 1, Ar ₄ and R ₁₁ may jointly form a ring.)

(In the formula (VI), R ₁₂ and R ₁₃ are hydrogen atoms, halogen atoms, nitro groups, cyano groups, substituted or unsubstituted alkyl groups, etc., R ₁₄ and R ₁₅ are hydrogen atoms, cyano groups, alkoxycarbonyl groups, R ₁₆ represents a hydrogen atom, a lower alkyl group or an alkoxy group, such as a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, etc. W represents a hydrogen atom, a substituted or unsubstituted alkyl group or an alkylene group, substituted or An unsubstituted aryl group or arylene group, such as r is an integer of 1 to 5, s is an integer of 1 to 4, t is an integer of 0 to 2, u is an integer of 1 to 3, and v is an integer of 1 to 2. To express.)

  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, poly Vinylidene chloride, polyarate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin And thermoplastic or thermosetting resins such as alkyd resins.

The amount of the charge transport material is appropriately 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 these, 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 addition, a polymer charge transport material having a function as a charge transport material and a function of a binder resin is also preferably used for the charge transport layer. The charge transport layer composed of these polymer charge transport materials is excellent in wear resistance. As the polymer charge transport material, known materials can be used, and in particular, a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used. Among these, polymer charge transport materials represented by the formulas (VII) to (XVI) are favorably used, and these are exemplified below and specific examples are shown.

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

In the formula, R ₁₀₁ and R ₁₀₂ each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, —O—, —S—, —SO—, —SO ₂ —. , -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or
(Wherein, a represents an integer of 1 to 20, b represents an integer of 1 to 2000, R ₁₀₃ and R ₁₀₄ represent a substituted or unsubstituted alkyl group or an aryl group). Here, R ₁₀₁ and R ₁₀₂ , and R ₁₀₃ and R ₁₀₄ may be the same or different.

(VIII) wherein, R _7, R ₈ represents a substituted or unsubstituted aryl _{group, Ar 1, Ar 2, Ar} 3 independently represent an arylene group. X, k, j and n are the same as those in the formula (VII).

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

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

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

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

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

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

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

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

  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 has been 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.
In addition to the protective layer, 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 (inorganic pigments) ), Or an organic filler (organic pigment) dispersed therein 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 among them from the viewpoint of the hardness of the filler. In particular, 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 of 10 ¹⁰ Ω · cm or more) is preferable, and the filler having a pH of 5 or more or the 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 of 10 ⁶ Ω · cm or more was measured with a HIGH RESISTER 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, all conventionally used surface treatment agents can be used, but a surface treatment agent capable of maintaining the insulating properties of the filler is preferable. For example, a titanate coupling agent, an aluminum coupling agent, a zircoaluminate coupling agent, a higher fatty acid, etc., or a mixed treatment of these with a 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 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, as the binder resin for the protective layer, the polymer charge transport material described in the section of the charge transport layer can also be used. As the effect when this is used, the effect of improving the wear resistance and the high-speed charge transport can be obtained as described in the section of the charge transport layer.
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.

There are several ways to solve this problem:
(1) introducing a polymer component into the crosslinked layer and the crosslinked structure;
(2) A large amount of monofunctional and bifunctional radically polymerizable monomers are used.
(3) A polyfunctional monomer having a flexible group is used.
However, in any case, the crosslink density of the cross-linked layer becomes dilute, and the dramatic wear resistance is not achieved. On the other hand, in the photoreceptor of the present invention, a cross-linking protective layer having a high cross-linking density in which a three-dimensional network structure is developed on the charge transport layer is preferably provided with a 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 thickness of the crosslinkable protective layer 2 μm or more and 8 μm or less, in addition to improving the margin for the above problem, it is possible to select a material with a high crosslink density that leads to further improvement in wear resistance. It becomes possible.

  The reason why the photoreceptor of the present invention can suppress cracks and film peeling is that the internal stress does not increase because the cross-linked protective layer can be thinned, and the internal stress of the cross-linked protective layer on the surface because the charge transport layer is provided in the lower layer. It is because it can relax. 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
(However, in Formula 10, X ₁ represents an arylene group such as a phenylene group or 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 Represents a -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, an 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 optionally substituted benzyl, an aralkyl group such as a phenethyl group, an optionally substituted phenyl group, an aryl group such as a naphthyl group, or -CONR ₁₂ R ₁₃ (R ₁₂ and R ₁₃ represents a hydrogen atom, an optionally substituted alkyl group such as a methyl group or an ethyl group, an optionally substituted benzyl group, a naphthylmethyl group, or an aralkyl group such as a phenethyl group; Ma Is a phenyl group which may have a substituent, an aryl group such as phenyl or naphthyl, which may be the same or different from each other.) Further, X ₂ is and the same substituents as X ₁ in the formula 10 Represents 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 phenyl group and a naphthyl group, an aralkyl group such as a benzyl group and a phenethyl group, and the like.

  Among these radical polymerizable functional groups, acryloyloxy group and methacryloyloxy group are particularly useful, and a compound having three or more acryloyloxy groups is, for example, a compound having three or more hydroxyl groups in the molecule and an acrylic group. It can be obtained by using an acid (salt), an acrylic acid halide, or an acrylic ester to cause an ester reaction or a transesterification reaction. 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.

{Wherein 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 each 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.
Among 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.

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 to} C _12, especially C _{1 to} C ₈ , more preferably C _{1 to} C ₄ linear or branched alkyl groups, and these alkyl groups further 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, 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)
(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 or Ar ₂ is a divalent group derived from the aryl group represented by Ar ₃ or 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.

Examples of the substituted or unsubstituted alkylene group include C _{1 to} C ₁₂ , preferably C _{1 to} C ₈ , and more preferably C _{1 to} C ₄ linear or branched alkylene groups. 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 is a C _{5 to} C ₇ cyclic alkylene group, and these cyclic alkylene groups include a fluorine atom, a hydroxyl group, a C _{1 to} C ₄ alkyl group, and a C _{1 to} C ₄ alkyl group. 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
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).
(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. )
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 azobisisobutyronitrile, 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, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether Benzoin ether-based photopolymerization initiators such as Benzophenone photopolymerization initiators such as 1,4-benzoylbenzene, thioxanthones such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Examples of photopolymerization initiators and other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoic acid. Phenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10 -Phenanthrene, an acridine type compound, a triazine type compound, an imidazole type compound is mentioned. 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 application can be performed by dip coating, spray coating, bead coating, ring coating, 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 reaction progresses unevenly, local flaws occur on the surface of the crosslinked protective layer, and a large number of unreacted residues and reaction termination ends occur. 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.

  In the configuration in which the charge blocking layer, the moire preventing layer, the photosensitive layer (charge generation layer, charge transport layer) and the crosslinkable protective layer of the electrophotographic photoreceptor of the present invention are sequentially laminated, the outermost crosslinkable protective layer is an organic solvent. On the other hand, when it is insoluble, it is characterized in that dramatic wear resistance and scratch resistance are achieved. 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. 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 onto a photoreceptor in which a charge generation layer and the charge transport layer are sequentially laminated on a translucent support. 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, the use of a polymer charge transport material for the photosensitive layer (charge transport layer) or the provision of a protective layer on the surface of the photoreceptor increases the durability (wear resistance) of each photoreceptor. In addition, when used in a tandem type full-color image forming apparatus as described later, a new effect not found in the monochrome image forming apparatus is also produced.

In the present invention, in order to improve environmental resistance, the following antioxidant is added to each layer such as a protective layer, a charge transport layer, and a charge generation layer, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential. be able to.
(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 electrostatic latent image can be formed, for example, by uniformly charging the surface of the electrostatic latent image carrier and then exposing (writing) imagewise. It can be done by means.
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. Non-contact charger using corona discharge such as a charger, corotron, scorotron, etc. Examples include a proximity non-contact charger (see FIG. 16) having a gap.
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 of the surface potential (V) 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 charge generation layer and the charge transport layer.

  The exposure (optical writing) 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 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 at a higher resolution, writing takes longer, so writing with one writing light source 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, toner having the same polarity as the charged polarity of the photosensitive member 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 using only 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 (photoconductor) of the visible image using a transfer charger, 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 a recording medium can be preferably cited. 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 vessel. There may be one transfer means or two or more transfer means. Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device. The recording medium is 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 a 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, the greater the effect on the electrostatic fatigue of the photoreceptor during repeated use.
This passing charge amount corresponds to the amount of charge flowing in the film thickness direction of the photoreceptor. As an operation in the image forming apparatus of the photoconductor, 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 is 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 area 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. Generally, since current writing is low in writing, if this method is used, the amount of charge passing through the photoreceptor in repeated use is almost the current that flows 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 photoconductor 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 photoconductor. Accordingly, if the surface potential of the photosensitive member can be attenuated by means other than light, the amount of passing charge per one rotation of the photosensitive member (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, a non-writing portion that is charged by main charging 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, the absolute value on the polarity side charged by the main charger is reduced to 100 V or less, so that almost no photocarrier is generated even if the subsequent charge removal process is entered, 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 photoconductor is charged to a polarity opposite to the charge polarity applied by the main charger, no optical carrier is generated. desirable. 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 by 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 pressurizing 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 neutralizing means has a wavelength of less than 500 nm (however, the wavelength that can be absorbed by the metal oxide contained in the intermediate layer of the photoreceptor), and neutralizes the electrostatic latent image carrier. As long as it is possible, 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.

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 on the market, and these can also be used effectively.

On the other hand, the lower limit value of the static elimination light wavelength is basically determined by the material constituting the support. Even in the case of a material such as glass, the transmittance decreases in the region of about 200 nm, and in the case of a plastic having an aromatic group, the transmittance decreases on the shorter wavelength side than about 300 nm. Thus, the lower limit is determined by the rate of absorption of the material constituting the support.
Further, the lower limit may be determined by the absorption spectrum of the charge transport material contained in the charge transport layer. That is, when neutralizing light is irradiated from the support side, no problem occurs when light is absorbed in the charge generation layer by nearly 100%. Depending on the concentration and the film thickness of the charge generation layer, the static elimination light reaches the charge transport layer. The majority of charge transport materials that have high mobility and can be used at a practical level are that 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. In such a case, the charge transport material absorbs the static elimination light, which may lead to deterioration of the charge transport material, and light in a region where the charge transport material is not absorbed is used. Therefore, if further shortening of the wavelength 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.

  As a second charge eliminating means, light having a wavelength longer than 500 nm may be irradiated from the photosensitive member surface side. Even if light having a wavelength longer than 500 nm is irradiated from the inside of the photoreceptor, the light is blocked (generally scattered) by the intermediate layer, and sufficient light does not reach the photosensitive layer. In addition, when light having a wavelength shorter than 500 nm is irradiated from the surface, the light is absorbed by the charge transport layer and not only does not exhibit the effect as the static elimination light but also has an adverse effect.

-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 respective 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 a metal oxide and a charge generation layer containing an organic charge generation material on a translucent support that transmits static elimination light. And a laminated photosensitive layer comprising a charge transport layer. The photoconductor (1) has a drum shape, but may be a sheet or an endless belt.

  As the charging member (3), a wire-type charger or a roller-shaped 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 (4) 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 at a higher resolution, writing takes longer, so writing with one writing light source 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, as described above, it is an effective means to use laser light having an oscillation wavelength shorter than 450 nm.

The developing unit (5) as developing means has at least one developing sleeve.
In the developing unit (5), 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 life of the light source. In addition, there are two methods, a one-component method in which development is performed using only toner and a two-component method in which a two-component developer composed of toner and carrier is used.

  The transfer member (8) may be a transfer belt or a transfer roller, but it is desirable to use a contact type such as a transfer belt or a 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 photosensitive member is transferred to the transfer paper and becomes 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. Further, 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 passing through the photoreceptor per one cycle of image formation. Can be used effectively in the present invention.

The light source such as the neutralizing member (2) has a wavelength of less than 500 nm (however, a wavelength that can be absorbed by the metal oxide contained in the intermediate layer of the photoconductor), and the electrostatic latent image carrier What is necessary is just to be able to perform static elimination, and it can select suitably from well-known static elimination devices, for example, a semiconductor laser (LD), electroluminescence (EL) etc. are mentioned suitably.
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 500 nm or less 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 support used for the photoreceptor and the transmittance of the charge transport material, but the lower limit is about 300 to 350 nm.
In FIG. 8, 6 is a registration roller, 7 is a transfer paper, and 9 is a separation claw.
In addition, the toner developed on the photoreceptor (1) by the developing unit (5) is transferred to the transfer paper (7). If toner remaining on the photoreceptor (1) is generated, a fur brush ( 10) and the cleaning blade (11) to remove from the photoreceptor. 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) denote photoconductors, and the photoconductors are intermediate layers containing at least a metal oxide on a translucent support that transmits static elimination light. A laminated photosensitive layer comprising a charge generation layer containing an organic charge generation material and a charge transport layer is provided.

  The photoreceptors (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) having at least one developing sleeve (19M), (19C), (19K), cleaning member (20Y), (20M), (20C), (20K), from 500 nm Also, there are arranged neutralizing means (15Y), (15M), (15C), and (15K) for irradiating light with a short wavelength (however, the wavelength that can be absorbed by the metal oxide contained in the intermediate layer of the photoreceptor). ing. 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 member (18Y) , (18M), (18C), and (18K) are irradiated with laser light (writing light), and electrostatic latent images are formed on the photoconductors (16Y), (16M), (16C), and (16K). It is like that. 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), (19K) and a cleaning member (20Y) of the image forming units (25Y), (25M), (25C), (25K). , (20M), (20C), and (20K) are in contact with the photosensitive member (16Y), (16M), (16C), and (16K), and contact the back side of the photosensitive member side of the transfer conveyance belt (22). 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 absolute value of 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 600 dpi or more (preferably 2400 dpi or more) with a laser beam by the exposure members (18Y), (18M), (18C), and (18K) arranged outside the photosensitive member. 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 members (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, residual toner remaining on each of the photoconductors (16Y), (16M), (16C), and (16K) without being transferred by the transfer unit is removed from the cleaning devices (20Y), (20M), (20C), ( 20K).
Subsequently, excess residual charges on the photosensitive member are removed by the charge eliminating members (15Y), (15M), (15C), and (15K) having a light source having a wavelength shorter than 500 nm. After that, the charger is uniformly charged again, 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. A process cartridge is a single device (part) that contains a photoconductor and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a neutralizing 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 on a translucent support that transmits the static elimination light. It will be.

  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 body, 106 is a transfer means, 107 is a cleaning means, and 108 is a wavelength shorter than 500 nm (however, in the intermediate layer of the photoreceptor). It is a static elimination member having a light source having a wavelength that can be absorbed by the contained metal oxide.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the following Example at all. In addition, all the parts used in an Example represent a weight part.
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.

-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.

When the obtained titanyl phthalocyanine powder was measured for X-ray diffraction spectrum under the following conditions using a commercially available X-ray diffractometer (Rigaku Denki: RINT1100), the Bragg angle 2θ with respect to Cu-Kα ray (wavelength 1.542Å) was It has a maximum peak at 27.2 ± 0.2 ° and a peak at a minimum angle of 7.3 ± 0.2 °, and further 9.4 ± 0.2 °, 9.6 ± 0.2 °, 24.0 Titanyl phthalocyanine powder having a main peak at ± 0.2 ° and no peak between the 7.3 ° peak and the 9.4 ° peak, and 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)
According to the method of JP-A-2004-83859, Example 1, an aqueous paste of titanyl phthalocyanine pigment was synthesized, and crystal transformation 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 stirred vigorously (2000 rpm) with a homomixer (Kennis, MARKIIf model) at room temperature. 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.

A portion of titanyl phthalocyanine (water paste) before crystal conversion 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 having a 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. The arithmetic average of the major axis of the measured 30 individuals was determined and used as the average particle size. 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 carried out with the length of the largest diagonal line of the crystal as the major axis.

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)
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 carried out under the conditions shown below with a formulation having the following composition to prepare a dispersion as a charge generation layer coating solution.
5 parts of azo pigment with the following structure
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. Was dispersed for 10 days to prepare a dispersion (referred to as dispersion 4).

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

(Photoreceptor Preparation Example 1)
According to the method described in JP-A-11-288115, Example 1-2, a translucent support was prepared by manufacturing a cylindrical substrate (diameter 100 mm) and further applying a conductive layer in the same manner. Got ready.
That is, azobisisobutyronitrile (AIBN) was used as a polymerization initiator so that the blending ratio of benzyl methacrylate (BzMA) monomer and methyl methacrylate (MMA) monomer was 20:80 (weight ratio). The resultant was added and heated at 50 ° C. for 3 hours for prepolymerization to obtain a syrupy polymerizable liquid material having a viscosity of about 100 cp. This polymerizable liquid material is poured into a cylindrical mold having an inner diameter of 100 mm and a length of 800 mm, and the entire mold is subjected to a heat treatment at 60 ° C. for 9 hours while being closely adhered to the inner wall of the mold by centrifugal force. And polymerized. The obtained substrate was annealed to room temperature at a rate of 0.2 ° C./min and then removed from the mold. The obtained substrate was subjected to end cutting processing to obtain a cylindrical substrate having an outer diameter of 100 mm and a length of 360 mm as shown in Table 1, and was used for production of a photoreceptor. Next, each of the following conductive layer coating solution compositions was applied onto the cylindrical substrate so as to have a dry film thickness of 0.5 μm, and heat-treated at 80 ° C. for 30 minutes to obtain a support for a photoreceptor.
◎ Conductive layer coating composition
1000 g of conductive paint X-101H manufactured by Sumitomo Metal Mining Co., Ltd.
1000g of toluene

On this support, 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 and a 0.3 μm charge generation layer. An electrophotographic photosensitive member having a charge transport layer of 25 μm was prepared (referred to as photosensitive member 1).
◎ Intermediate layer coating liquid Untreated surface rutile type titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 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%),
Manufactured by Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 260 parts ◎ charge generation layer coating solution Dispersion 2 prepared above was used.

◎ Charge transport layer coating solution Z type polycarbonate 10 parts Charge transport material of the following structural formula 7 parts
Tetrahydrofuran 100 parts 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 (upper limit wavelength on the long wavelength side that can be absorbed) was determined, and the absorption edge of titanium oxide was determined to be about 410 nm.

(Photosensitive member preparation example 2)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the intermediate layer coating solution used in Photoconductor Preparation Example 1 was changed to one having the following composition (referred to as electrophotographic photoconductor 2).
◎ Intermediate layer coating liquid Surface Si-treated rutile type titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 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 The above-mentioned surface Si-treated rutile type titanium oxide is 2% by weight based on the weight of the surface untreated rutile type titanium oxide used in Photoconductor Preparation Example 1. The surface treatment was performed using this siloxane.
An intermediate layer was formed in the same manner as the photoreceptor 2 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 (upper limit wavelength on the long wavelength side that can be absorbed) was determined, and the absorption edge of titanium oxide was determined to be about 410 nm.

(Photoreceptor Preparation Example 3)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the intermediate layer coating solution used in Photoconductor Preparation Example 1 was changed to one having the following composition (referred to as electrophotographic photoconductor 3).
◎ Intermediate layer coating solution Surface untreated zinc oxide:
(SAZEX # 2000: manufactured by Sakai Chemical Industry Co., Ltd., average particle size: 0.60 μm) 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 Using the above intermediate layer coating solution, an intermediate layer was formed on the 1 mm thick aluminum plate in the same manner as the photoreceptor 3. As in the case of the photoreceptor 1, 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 (upper limit wavelength on the long wavelength side that can be absorbed) was determined, and the absorption edge of titanium oxide was determined to be approximately 388 nm.

(Photosensitive member production example 4)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the intermediate layer coating solution used in Photoconductor Preparation Example 1 was changed to one having the following composition (referred to as electrophotographic photoconductor 4).
◎ 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 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.

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 Using a transfer belt as a member and using a 380 nm LED (manufactured by Nichia Corporation) as a static elimination light source, static elimination was performed from the inside of the photoreceptor. Process conditions before the test were set as follows, and a chart with a writing rate of 6% (characters equivalent to 6% as the image area are written on the entire A4 surface) was continuously 100,000 Sheet printing was performed.
Photoconductor charging potential (unexposed portion potential): −900 V
Development bias: -650V (negative / positive development)
Surface potential after static elimination (unexposed area of writing light): −100V
Evaluation was made by measuring the potential of the photosensitive member exposed area before and after printing 100,000 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 light source in Example 1 was changed to a 472 nm LED (manufactured by Seiwa Denki: full width at half maximum of 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 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)
Except for changing to irradiate substantially the same amount of light simultaneously using two of 380 nm LED (manufactured by Nichia Chemical) and 630 nm LED (manufactured by ROHM: half-width 20 nm) as the static elimination light source in Example 1, and 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.

(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 3.

  In Examples and Comparative Examples, the transmittance for neutralizing light was measured with a commercially available spectrophotometer in the same configuration as the photoconductor used before the intermediate layer was applied. The results are shown in the table as the support transmittance.

From Table 3, when the wavelength of the static elimination light was set to 380 nm and light was absorbed by titanium oxide contained in the intermediate layer (Example 1), a longer wavelength (not absorbed by titanium oxide) was used. Compared to the cases (Comparative Examples 1 to 3), it can be seen that the increase in the exposed portion potential after repeated use is small.
Further, in the case where the emission distribution is wide and a component of long wavelength light of 410 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.
It can be seen that when the titanium oxide used in the intermediate layer is subjected to surface treatment (Example 2), the effect of reducing the residual potential is small as compared with the case where it is not treated (Example 1).

(Example 3)
In Example 1, evaluation was performed in the same manner as in Example 1 except that the electrophotographic photosensitive member 3 was used instead of the electrophotographic photosensitive member 1 used. The results are shown in Table 4.
(Comparative Example 6)
Evaluation was performed in the same manner as in Example 3 except that the static elimination light source in Example 3 was changed to 472 nm LED (manufactured by Seiwa Denki: full width at half maximum of 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 3. The results are shown in Table 4.

(Comparative Example 7)
Evaluation was performed in the same manner as in Example 3 except that the neutralization light source in Example 3 was changed to a 502 nm LED (manufactured by Seiwa Denki: full width at half maximum of 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 3. The results are shown in Table 4.
(Comparative Example 8)
Evaluation was performed in the same manner as in Example 3 except that the static elimination light source in Example 3 was changed to 630 nm LED (Rohm: full width at half maximum: 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 3. The results are shown in Table 4.

(Comparative Example 9)
Evaluation was performed in the same manner as in Example 3 except that the static elimination light source in Example 3 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 3. The results are shown in Table 4.
(Comparative Example 10)
Example 3 and Example 3 except that the static elimination light source in Example 3 was changed to irradiate substantially the same amount of light simultaneously using two of 380 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 3. The results are shown in Table 4.

From Table 4, when the wavelength of the static elimination light was set to 380 nm and light was absorbed by the zinc oxide contained in the intermediate layer (Example 3), a longer wavelength (not absorbed by zinc oxide) was used. Compared to the cases (Comparative Examples 6 to 8), it can be seen that the increase in the potential of the exposed area after repeated use is small.
In addition, in the case where the emission distribution is wide and a component of light having a long wavelength of 388 nm or more is included (Comparative Example 7), 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.

Example 4
In Example 1, evaluation was performed in the same manner as in Example 1 except that the electrophotographic photosensitive member 4 was used instead of the used electrophotographic photosensitive member 1. The results are shown in Table 5.
(Example 5)
Evaluation was performed in the same manner as in Example 4 except that the charge removal light source in Example 4 was changed to a 470 nm LED (manufactured by Nichia Corporation) as the charge removal light source. 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 4. The results are shown in Table 5.

(Comparative Example 11)
Evaluation was performed in the same manner as in Example 4 except that the static elimination light source in Example 4 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 4. The results are shown in Table 5.
(Comparative Example 12)
Evaluation was performed in the same manner as in Example 4 except that the static elimination light source in Example 4 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 4. The results are shown in Table 5.

(Comparative Example 13)
Evaluation was performed in the same manner as in Example 4 except that the static elimination light source in Example 4 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 4. The results are shown in Table 5.
(Comparative Example 14)
Evaluation was performed in the same manner as in Example 4 except that the static elimination light source in Example 4 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 4. The results are shown in Table 5.

(Comparative Example 15)
Example 4 and Example 4 except that the static elimination light source in Example 4 was changed to irradiate substantially the same amount of light simultaneously using two of 380 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 4. The results are shown in Table 5.

From Table 5, when the wavelength of the static elimination light is 380 or 470 nm and light is absorbed by the nitrogen-doped titanium oxide contained in the intermediate layer (Examples 4 and 5), a longer wavelength (nitrogen-doped titanium oxide) It can be seen that the increase in the potential of the exposed portion after repeated use is small as compared with the case where the light is not absorbed in (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. In addition, when two types of light sources having different exposure wavelengths are used (Comparative Example 15), it can be seen that the effect of charge removal by the short wavelength light source is reduced.

(Photoreceptor Preparation Example 5)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge generation layer coating solution in Photoconductor Preparation Example 1 was changed to Dispersion Liquid 1 (referred to as Photoconductor 5).
(Photosensitive member preparation example 6)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge generation layer coating solution in Photoconductor Preparation Example 1 was changed to Dispersion Liquid 3 (referred to as Photoconductor 6).

(Example 6)
Evaluation was performed in the same manner as in Example 1 except that the electrophotographic photoreceptor used in Example 1 was changed from the photoreceptor 1 to the photoreceptor 5. Further, after outputting 100,000 images, a solid white image was output to evaluate the background stain. The results are shown in Table 6 together with the results of Examples 1 and 6.
(Example 7)
Evaluation was performed in the same manner as in Example 6 except that the electrophotographic photoreceptor used in Example 6 was changed from the photoreceptor 5 to the photoreceptor 6. The results are shown in Table 6.
For the background dirt evaluation, the rank evaluation was carried out from the number and size of black spots generated on the background. The ranking was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.

  From Table 6, when the average particle diameter of the coating solution used for the charge generation layer is 0.25 μm or less (Examples 1 and 7), 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 7)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge transport layer coating solution in Photoconductor Preparation Example 1 was changed to one having the following composition (referred to as Photoconductor 7).
◎ Charge transport layer coating solution Z type polycarbonate 10 parts Charge transport material of the following structural formula 7 parts
Tetrahydrofuran 100 parts

(Photoreceptor Preparation Example 8)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge transport layer coating solution in Photoconductor Preparation Example 1 was changed to one having the following composition (referred to as Photoconductor 8).
◎ Charge transport layer coating solution Z type polycarbonate 10 parts Charge transport material of the following structural formula 7 parts
Tetrahydrofuran 100 parts

(Example 8)
Evaluation was performed in the same manner as in Example 1 except that the electrophotographic photoreceptor used in Example 1 was changed from the photoreceptor 1 to the photoreceptor 7. The results are shown in Table 7.
(Comparative Example 16)
Evaluation was performed in the same manner as in Comparative Example 3 except that the electrophotographic photoreceptor used in Comparative Example 3 was changed from Photoreceptor 1 to Photoreceptor 7. The results are shown in Table 7.

Example 9
Evaluation was performed in the same manner as in Example 1 except that the electrophotographic photoreceptor used in Example 1 was changed from the photoreceptor 1 to the photoreceptor 8. The results are shown in Table 7.
(Comparative Example 17)
Evaluation was performed in the same manner as in Comparative Example 3 except that the electrophotographic photoreceptor used in Comparative Example 3 was changed from Photoreceptor 1 to Photoreceptor 8. The results are shown in Table 7.

(Comparative Example 18)
The apparatus shown in FIG. 8 was modified so that static elimination light was irradiated from the surface side of the photoreceptor. A 100,000 sheet passing test was performed under the same conditions as in Example 9 except that the irradiation direction of the static elimination light was changed. The results are shown in Table 8.

From the results shown in Table 8, when the charge removal light is irradiated from the surface of the photoreceptor (Comparative Example 18), the charge removal light does not reach the intermediate layer and the charge generation layer, and the exposed portion potential increases after repeated use. I understand.

(Example 10)
The apparatus shown in FIG. 8 was modified so that the second charge eliminating light could be irradiated from the surface side of the photoreceptor. A 100,000 sheet passing test was performed under the same conditions as Example 1 except that a 630 nm LED (Rohm: half width 20 nm) was used in combination as the second charge eliminating light. At this time, the amount of charge removed from the inside of the photosensitive member was set to be the same as in the case of Example 1.
Further, after outputting 100,000 sheets, a chart as shown in FIG. 13 (the front half was a stripe and the rear half was a halftone) was output, and the image unevenness in the halftone portion was observed. The results are shown in Table 9.

  When the second charge removal light is irradiated from the surface of the photoreceptor (Example 10), the exposure portion potential increase after repeated use is suppressed, although only slightly. In the chart output of FIG. 13, the halftone part of Example 10 formed a completely normal image. However, in Example 1, the level was not a problem, but the halftone part was slightly corresponding to the stripe. An afterimage was observed.

(Example 11)
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.
Further, a one-dot image having a diameter of 60 μm was formed and compared with the case of Example 1 (the dot formation state was observed with a 150 × microscope).

From Table 10, it can be seen that when writing is performed using a short wavelength LD (407 nm) (Example 11), compared to the case of Example 1, the exposure portion potential rise is further suppressed. Furthermore, in dot evaluation, the outline of the one-dot image of Example 11 was clearer.

(Photoreceptor Preparation Example 9)
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 9).
◎ 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 Titanium oxide (CR-EL: Ishihara Sangyo Co., Ltd.) Manufactured, average particle size: 0.25 μm) 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.

(Photoreceptor Preparation Example 10)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 9 except that the charge blocking layer thickness was 0.3 μm in Photoconductor Preparation Example 9 (hereinafter referred to as “electrophotographic photoconductor 10”).
(Photoreceptor Preparation Example 11)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 9 except that the thickness of the charge blocking layer was 1.8 μm in Photoconductor Preparation Example 9 (referred to as electrophotographic photoconductor 11).

(Photoconductor Preparation Example 12)
In Photoconductor Preparation Example 9, a photoconductor was prepared in the same manner as in Photoconductor Preparation Example 9 except that the charge blocking layer coating solution was changed to the following composition (referred to as electrophotographic photoconductor 12).
◎ Charge blocking layer coating solution Alcohol-soluble nylon (Toray: Amilan CM8000) 4 parts Methanol 70 parts n-Butanol 30 parts

(Photoreceptor Preparation Example 13)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 9 except that the moire-preventing layer coating solution was changed to one having the following composition in Photoconductor Preparation Example 9 (referred to as electrophotographic photoconductor 13).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 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.

(Photoreceptor Preparation Example 14)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 9 except that the moire-preventing layer coating solution was changed to one having the following composition in Photoconductor Preparation Example 9 (referred to as electrophotographic photoconductor 14).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 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.

(Example 12)
The electrophotographic photosensitive member 1 is mounted on an image forming apparatus as shown in FIG. 8, an image exposure light source is a 780 nm semiconductor laser (image writing by a polygon mirror), a scorotron charger is used as a charging member, and a transfer belt is used as a transfer member. Then, using a 380 nm LED (manufactured by Nichia) as a static elimination light source, static elimination was performed from the inside of the photoreceptor. Process conditions before the test were set as follows, and using a chart with a writing rate of 6% (characters equivalent to 6% as the image area are written on the entire A4 surface), continuous 200,000 Sheet printing was performed.
Photoconductor charging potential (unexposed portion potential): −900 V
Development bias: -650V (negative / positive development)
Surface potential after static elimination (unexposed area of writing light): −100V

Evaluation was made by measuring the potential of the photosensitive member exposed area before and after printing 200,000 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. Further, after outputting 200,000 images, a solid white image was output to evaluate the background stain.
For the background dirt evaluation, the rank evaluation was carried out from the number and size of black spots generated on the background. The ranking 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 11.

(Examples 13 to 18)
The electrophotographic photoreceptors 9 to 14 were subjected to a running test of 200,000 sheets under the same conditions as in Example 12 (the evaluation method and items were the same). The results are shown in Table 11 in comparison with the case of Example 12.
From the results of Table 11, it can be seen that the durability against soiling is improved by configuring the intermediate layer as a charge blocking layer and a moire preventing layer.

(Photoreceptor Preparation Example 15)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge transport layer coating solution in Photoconductor Preparation Example 1 was changed to one having the following composition (referred to as Photoconductor 15).
◎ Charge transport layer coating solution 10 parts of polymer charge transport material of the following structural formula
4 parts of low molecular charge transport material with the following structure
100 parts methylene chloride

(Photoreceptor Production Example 16)
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 photoconductor was prepared (referred to as electrophotographic photoconductor 16).
◎ Protective layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula: 7 parts
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 17)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 16 except that the alumina fine particles in the protective layer coating solution in Photoconductor Preparation Example 16 were changed to the following (referred to as electrophotographic photoconductor 17).
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 18)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 16 except that the alumina fine particles in the protective layer coating solution in Photoconductor Preparation Example 16 were changed to the following (referred to as electrophotographic photoconductor 18).
4 parts of tin oxide-antimony oxide powder (specific resistance: 10 ⁶ Ω · cm, average primary particle size 0.4 μm)

(Photoreceptor Preparation Example 19)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member manufacturing example 16 except that the protective layer coating solution in the photosensitive member manufacturing example 16 was changed to one having the following composition (referred to as an electrophotographic photosensitive member 19).
◎ Protective layer coating solution 17 parts of polymer charge transport material of the following structural formula (weight average molecular weight: about 140000)
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 20)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member manufacturing example 16 except that the protective layer coating solution in the photosensitive member manufacturing example 16 was changed to one having the following composition (referred to as an electrophotographic photosensitive member 20).
◎ Protective layer coating solution Methyltrimethoxysilane 100 parts 3% acetic acid 20 parts Charge transporting compound with the following structure 35 parts
Antioxidant (Sanol LS2626: Sankyo Chemical Co., Ltd.) 1 part Curing agent (dibutyltin acetate) 1 part 2-propanol 200 parts

(Photoconductor Preparation Example 21)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member manufacturing example 16 except that the protective layer coating solution in the photosensitive member manufacturing example 16 was changed to one having the following composition (referred to as an electrophotographic photosensitive member 21).
◎ Protective layer coating solution Methyltrimethoxysilane 100 parts 3% acetic acid 20 parts Charge transporting compound with the following structure 35 parts
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

(Photoconductor Preparation Example 22)
An electrophotographic photosensitive member was prepared in the same manner as the photosensitive member preparation example 16 except that the protective layer coating solution in the photosensitive member preparation example 16 was changed to the one having the following composition (referred to as an electrophotographic photosensitive member 22).
◎ 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)
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 , and irradiation time: 60 seconds. The film was cured.

(Photoconductor Preparation Example 23)
In Photoconductor Preparation Example 22, all the examples except for changing the trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure contained in the protective layer coating solution to the following radical polymerizable monomer An electrophotographic photosensitive member was produced in the same manner as in Example 22 (referred to as an electrophotographic photosensitive member 22).
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)

(Photoconductor Preparation Example 24)
A trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure contained in the protective layer coating solution of Photosensitive Member Preparation Example 22 is converted into a bifunctional radical polymerizable monomer having no following charge transporting structure. Except for changing to 10 parts, an electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member manufacturing example 22 (referred to as an electrophotographic photosensitive member 24).
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)

(Photoconductor Preparation Example 25)
In Photoconductor Preparation Example 22, all of the photoconductors were prepared except that the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the protective layer coating solution was replaced with the following radical polymerizable monomer. An electrophotographic photoreceptor was produced in the same manner as in Example 22 (referred to as electrophotographic photoreceptor 25).
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)

(Photoconductor Preparation Example 26)
The radical polymerizable compound 10 having a bifunctional charge transporting structure represented by the following structural formula is used as the radical polymerizable compound having a monofunctional charge transporting structure contained in the protective layer coating solution of Photosensitive Member Preparation Example 22. An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member manufacturing example 22 except that the part was changed to an electrophotographic photosensitive member (referred to as electrophotographic photosensitive member 26).

(Photoconductor Preparation Example 27)
In Photoconductor Preparation Example 22, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 22 except that the protective layer coating solution was changed to the following composition (referred to as electrophotographic photoconductor 27).
◎ 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)
Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Photoreceptor Preparation Example 28)
In Photoconductor Preparation Example 22, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 22 except that the protective layer coating solution was changed to the following composition (referred to as electrophotographic photoconductor 28).
◎ 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)
Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Photoconductor Preparation Example 29)
In Photoconductor Preparation Example 22, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 22 except that the protective layer coating solution was changed to the following composition (referred to as electrophotographic photoconductor 29).
◎ 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)
Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Photoreceptor Preparation Example 30)
In Photoconductor Preparation Example 22, an electrophotographic photoconductor was prepared in the same manner as Photoconductor Preparation Example 22 except that the protective layer coating solution was changed to the following composition (referred to as electrophotographic photoconductor 30).
◎ 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)
Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Example 19)
The electrophotographic photosensitive member 1 is mounted on an image forming apparatus as shown in FIG. 8, an image exposure light source is a 780 nm semiconductor laser (image writing by a polygon mirror), a scorotron charger is used as a charging member, and a transfer belt is used as a transfer member. A 380 nm LED (manufactured by Nichia Corporation) was used as a static elimination light source. The process conditions before the test were set as follows, and 300,000 sheets were continuously printed using a chart with a writing rate of 6%.
Photoconductor charging potential (unexposed portion potential): −900 V
Development bias: -650V (negative / positive development)
Surface potential after static elimination (unexposed area of writing light): −100V

<Evaluation items>
(1) Measurement of surface potential Evaluation was made by measuring the potential of the photosensitive member exposed area before and after printing 300,000 images.
As a measuring method, a surface potential meter is mounted at the position of the developing portion shown in FIG. 8, 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. The partial potential was measured. The results are shown in Table 12.
(2) Soil Evaluation Further, after outputting 300,000 images (after the surface potential measurement was completed), 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 12.

(3) Evaluation of cleaning property Further, after evaluation of soiling, under a low temperature and low humidity environment (10 ° C., 15% RH), using a test chart as shown in FIG. 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 12.

(4) Dot reproducibility evaluation 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 the sheet was passed. 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 12.
(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 20 to 35)
Under the same conditions as in Example 19, the electrophotographic photoreceptors 15 to 30 produced as described above were evaluated. The results are shown in Table 12. Table 12 also shows the used electrophotographic photoreceptor number corresponding to the example number.

Table 12 shows the following.
When a polymer charge transport material is used for the charge transport layer, even when a protective layer is provided, the effect of preventing the residual potential from rising can be recognized by performing static elimination with a light source having a wavelength shorter than 500 nm.
Wear resistance is improved by using a polymer charge transport material for the charge transport layer (Example 20), by providing a protective layer (Examples 21-35), and when not provided (Example 19). To do.
In the case where a protective layer containing an inorganic pigment (metal oxide) is provided (Examples 21 to 23), a specific resistance is 10 ¹⁰ Ω · cm or more, and an inorganic pigment (metal oxide) having a specific resistance is high. The dot reproducibility does not decrease so much even under high humidity (Examples 21 and 22).
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 abrasion resistance is obtained (Examples 27, 28, 30, 32 to 35).
In addition, when 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 is used, cleaning is performed. The property is also good.

(Comparative Example 19)
Evaluation was performed in the same manner as in Example 30 except that the static elimination light source in Example 30 was changed to 502 nm LED (manufactured by Seiwa Denki: full width at half maximum of 15 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal was the same as in Example 30. The results are shown in Table 13.
(Comparative Example 20)
Evaluation was performed in the same manner as in Example 30 except that the static elimination light source in Example 30 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 was the same as in Example 30. The results are shown in Table 13.

(Comparative Example 21)
Evaluation was performed in the same manner as in Example 30 except that the static elimination light source in Example 30 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 was the same as in Example 30. The results are shown in Table 13.
(Comparative Example 22)
Evaluation was performed in the same manner as in Example 30 except that the static elimination light source in Example 30 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 was the same as in Example 30. The results are shown in Table 13.

From Table 13, when the wavelength of the static elimination light is less than 500 nm and the intermediate layer can absorb the light (Example 30), it is compared with the case where a longer wavelength is used (Comparative Examples 19 to 21). Thus, it can be seen that the increase in the exposed portion potential 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 22), the clear effect as in the example is not obtained.

(Photoreceptor Preparation Example 31)
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 4 and the charge transport layer coating solution was changed to the following composition. An electrophotographic photoreceptor was prepared (referred to as electrophotographic photoreceptor 31).
◎ Charge transport layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula: 7 parts
80 parts of methylene chloride

(Example 31)
The previously prepared electrophotographic photoreceptor 31 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 380 nm LED (manufactured by Nichia Chemical) as the charge eliminating light source. Process conditions before the test were set as follows, and a chart with a writing rate of 6% (characters equivalent to 6% as the image area are written on the entire A4 surface) was continuously 100,000 Sheet printing was performed.
Photoconductor charging potential (unexposed portion potential): −900 V
Development bias: -650V (negative / positive development)
Surface potential after static elimination (unexposed area of writing light): −100V

The evaluation was performed by measuring the photosensitive member exposed portion potential before and after printing 100,000 sheets of 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 14.
Further, before and after printing 100,000 sheets, an ISO / JIS-SCID image N1 (portrait) was output to evaluate the color color reproducibility.

(Comparative Example 23)
Evaluation was performed in the same manner as in Example 31 except that the static elimination light source in Example 31 was changed to a 472 nm LED (manufactured by Seiwa Denki: full width at half maximum of 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 31. The results are shown in Table 14.
(Comparative Example 24)
Evaluation was performed in the same manner as in Example 31 except that the static elimination light source in Example 31 was changed to 502 nm LED (manufactured by Seiwa Denki: full width at half maximum of 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 31. The results are shown in Table 14.

(Comparative Example 25)
Evaluation was performed in the same manner as in Example 31 except that the static elimination light source in Example 31 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 31. The results are shown in Table 14.
(Comparative Example 26)
Evaluation was performed in the same manner as in Example 31 except that the static elimination light source in Example 31 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 31. The results are shown in Table 14.

(Comparative Example 27)
Evaluation was performed in the same manner as in Example 31 except that the static elimination light source in Example 31 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 31. The results are shown in Table 14.
(Comparative Example 28)
Except that the static elimination light source in Example 31 was changed to irradiate substantially the same amount of light at the same time using two of 380 nm LED (manufactured by Nichia) and 630 nm LED (manufactured by ROHM: full width at half maximum of 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 31. The results are shown in Table 14.

From Table 14, when the wavelength of the static elimination light is set to less than 500 nm and the intermediate layer is capable of absorbing light (Example 31), the wavelength is longer than that (Comparative Examples 23 to 26). Thus, it can be seen that the increase in the potential of the exposed portion after repeated use is small.
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 27), 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 28), 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 the case of Example 31, an image almost the same as the initial image was output even after printing 100,000 sheets. In the case of Comparative Examples 23 to 28, the color was printed after printing 100,000 sheets. The image was slightly out of balance.

(Photoconductor Preparation Example 32)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member preparation example 31 except that the charge transport layer coating solution in the photosensitive member preparation example 31 was changed to one having the following composition (referred to as an electrophotographic photosensitive member 32).
◎ Charge transport layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula: 7 parts
80 parts of methylene chloride

(Example 32)
In Example 31, evaluation was performed in the same manner as in Example 31 except that the electrophotographic photosensitive member 32 was used instead of the electrophotographic photosensitive member 31 used. The results are shown in Table 15.
(Comparative Example 29)
In Comparative Example 23, evaluation was performed in the same manner as Comparative Example 23 except that the electrophotographic photosensitive member 32 was used instead of the used electrophotographic photosensitive member 31. The results are shown in Table 15.

(Comparative Example 30)
In Comparative Example 24, evaluation was performed in the same manner as Comparative Example 24 except that the electrophotographic photosensitive member 32 was used instead of the used electrophotographic photosensitive member 31. The results are shown in Table 15.
(Comparative Example 31)
In Comparative Example 25, evaluation was performed in the same manner as in Comparative Example 25 except that the electrophotographic photosensitive member 32 was used instead of the used electrophotographic photosensitive member 31. The results are shown in Table 15.

(Comparative Example 32)
In Comparative Example 26, evaluation was performed in the same manner as Comparative Example 26 except that the electrophotographic photosensitive member 32 was used instead of the used electrophotographic photosensitive member 31. The results are shown in Table 15.
(Comparative Example 33)
In Comparative Example 27, evaluation was performed in the same manner as in Comparative Example 27 except that the electrophotographic photosensitive member 32 was used instead of the used electrophotographic photosensitive member 31. The results are shown in Table 15.
(Comparative Example 34)
In Comparative Example 28, evaluation was performed in the same manner as in Comparative Example 28 except that the electrophotographic photosensitive member 32 was used instead of the electrophotographic photosensitive member 31 used. The results are shown in Table 15.

From Table 15, when the wavelength of the static elimination light is set to less than 500 nm and the intermediate layer can absorb the light (Example 32), the wavelength is longer than that (Comparative Examples 29 to 32). Thus, it can be seen that the increase in the potential of the exposed portion after repeated use is small.
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 33), the clear effect as in the example is not obtained. Further, it can be seen that when two types of light sources having different exposure wavelengths are used (Comparative Example 34), the effect of static elimination 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 100,000 sheets. In Comparative Examples 29 to 34, the color was printed after printing 100,000 sheets. The image was slightly out of balance.

(Comparative Example 35)
The apparatus shown in FIG. 9 was modified so as to irradiate the surface of the photoreceptor with static elimination light. A 100,000 sheet passing test was carried out under the same conditions as in Example 32 except that the direction of the neutralizing light irradiation was changed. The results are shown in Table 16.

From the results shown in Table 16, when the charge removal light is irradiated from the surface of the photoreceptor (Comparative Example 35), the charge removal light does not reach the intermediate layer and the charge generation layer, and the potential of the exposed area is increased after repeated use. I understand.

(Example 33)
The apparatus shown in FIG. 9 was modified so that the second charge eliminating light can be irradiated from the surface side of the photoreceptor. 100,000 sheet passing tests were performed under the same conditions as in Example 31 except that a 630 nm LED (manufactured by ROHM: full width at half maximum) was used in combination as the second charge eliminating light. At this time, the amount of charge removed from the inside of the photosensitive member was set to be the same as that in Example 31.
Further, after outputting 100,000 sheets, a chart as shown in FIG. 13 (the front half was a stripe and the rear half was a halftone) was output, and the image unevenness in the halftone portion was observed. The results are shown in Table 17.

When the second charge-removing light is irradiated from the photosensitive member surface side (Example 33), the exposure portion potential increase after repeated use is suppressed, although slightly. In the chart output of FIG. 13, the halftone portion of Example 33 formed a completely normal image. However, in Example 31, the level was not a problem, but the halftone portion was slightly corresponding to the stripe. An afterimage was observed.

(Example 34)
In Example 31, evaluation was performed in the same manner as in Example 31 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 18 together with the case of Example 31.
Further, a one-dot image having a diameter of 60 μm was formed and compared with the case of Example 31 (the dot formation state was observed with a 150 × microscope).

From Table 18, it can be seen that when writing is performed using the short wavelength LD (407 nm) (Example 34), the exposure portion potential rise is further suppressed as compared to Example 31. Furthermore, in dot evaluation, the outline of the one-dot image of Example 34 was clearer.

It is a 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. FIG. 6 is a diagram showing still another layer configuration of the electrophotographic photosensitive member used in the present 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 10 (output in the A3 vertical feed direction). 20 is a test chart used in Example 19. FIG. It is a perspective view showing the charging means of the non-contact proximity arrangement mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination member 3 Charging member 4 Image exposure part 5 Developing unit 6 Registration roller 7 Transfer paper 8 Transfer member 9 Separation claw 10 Fur brush 11 Cleaning blade 15Y, 15M, 15C, 15K Static elimination member 16Y, 16M, 16C, 16K Photoconductor 17Y, 17M, 17C, 17K Charger 18Y, 18M, 18C, 18K Exposure member 19Y, 19M, 19C, 19K Development member 20Y, 20M, 20C, 20K Cleaning member 21Y, 21M, 21C, 21K Transfer brush 22 Transfer conveyance Belt 23 Registration roller 24 Fixing device 25Y, 25M, 25C, 25K Image forming element 26 Transfer paper 31 Conductive support 35 Charge generation layer 37 Charge transport layer 41 Protective layer 101 Photoconductor 102 Charging means 103 Image exposure section 104 Developing means 105 Transcription Body 106 transfer means 107 cleaning means 108 static elimination means 111 photoconductor 112 charging roller 113 gap forming member 114 metal shaft 115 image forming area 116 non-image forming area

Claims (21)

  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 electrostatic latent image carrier comprises at least an intermediate layer, a charge generation layer, and a charge transport layer on the support. A photosensitive layer, the intermediate layer contains at least a metal oxide, and the charge generation layer contains an organic charge generation material, and the charge eliminating means has a wavelength shorter than 500 nm and is contained in the intermediate layer. Irradiate from the inside of the electrostatic latent image carrier with light of a wavelength that can be absorbed by the metal oxide. Image forming apparatus which is a charge-eliminating unit.   The image forming apparatus according to claim 1, wherein a light source used for the charge eliminating unit is an LD or an LED.   The image forming apparatus according to claim 1, wherein the metal oxide is not subjected to a surface treatment.   4. The image formation according to claim 1, wherein in the latent image carrier, the intermediate layer includes a charge blocking layer and a moire preventing layer, and the metal oxide is contained in the moire preventing layer. apparatus.   The image forming apparatus according to claim 4, wherein the charge blocking layer is made of an insulating material and has a film thickness of less than 2.0 μm and 0.3 μm or more.   The image forming apparatus according to claim 5, wherein the insulating material is N-methoxymethylated nylon.   7. The image forming apparatus according to claim 4, wherein the moire preventing layer contains a metal oxide and a binder resin, and a volume ratio of the two is in a range of 1/1 to 3/1. .   The image forming apparatus according to claim 1, further comprising a protective layer on the charge transport layer. The image forming apparatus according to claim 8, 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 8. 11. The image formation according to claim 10, wherein the radically polymerizable compound having a monofunctional charge transporting structure used in the protective layer is at least one of the following general formula (1) or (2). apparatus.
{Wherein 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 each 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. )   The image forming apparatus according to claim 10, wherein the protective layer curing means is heating or light energy irradiation means.   14. The image according to claim 1, wherein the image forming apparatus further includes a second charge eliminating unit that irradiates light having a wavelength longer than 500 nm from the surface layer side of the electrostatic latent image carrier. Forming equipment.   15. 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.   16. The image forming apparatus 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, and a charge eliminating unit.   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 carrier, an electrostatic latent image forming step 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 A developing step, a transferring 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 eliminating step for photo-staticizing residual charges on the electrostatic latent image carrier. The latent electrostatic image bearing member comprises a translucent support that transmits static elimination light, and at least an intermediate layer, a charge generation layer, and a charge transport layer on the support. A photosensitive layer, the intermediate layer contains at least a metal oxide, and the charge generation layer contains an organic charge generation material, and the charge eliminating means has a wavelength shorter than 500 nm and is contained in the intermediate layer. Irradiate from the inside of the electrostatic latent image carrier with light of a wavelength that can be absorbed by the metal oxide. Image forming method which is a discharging process.   The image forming method according to claim 18, further comprising a second charge eliminating step of irradiating light having a wavelength longer than 500 nm from the surface layer side of the electrostatic latent image carrier.   20. The image forming method according to claim 18, 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.   21. The image forming method according to claim 18, comprising a plurality of image forming elements each having at least an electrostatic latent image carrier, an electrostatic latent image forming step, a developing step, and a charge eliminating step.