JP2005070749A - Electrophotographic photoreceptor, and process cartridge and image forming apparatus using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy-saving charging method and an image forming apparatus having high durability and high reliability and causing no abnormal image even for repeated use. <P>SOLUTION: The electrophotographic photoreceptor is to be used for an image forming method, and includes: the steps of: exposing a photoreceptor for charging; applying voltage to the photoreceptor via a conductive voltage application member being in contact with the photoreceptor during or after exposure for charging so as to charge the surface of the photoreceptor by the voltage application member into the same polarity as the applied voltage; forming an electrostatic latent image on the photoreceptor by carrying out imagewise exposure after charging; developing the electrostatic latent image with toner; and transferring the developed image onto a transfer body. The electrophotographic photoreceptor has, on a light transmitting conductive supporting body, a photosensitive layer having sensitivity at least to imagewise exposure and a photo-charge charging layer containing a charge generating substance which generates charges at least by exposure for charging. The photo-charge charging layer is present on the surface of the photoreceptor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photosensitive member, an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile machine, and a process cartridge for the image forming apparatus.

  An electrophotographic image forming apparatus charges a surface of a photoconductor to a predetermined potential, and selectively removes the charged potential by an exposure unit or a neutralization unit to form an electrostatic latent image. Is formed into a toner image by a developing means and visualized by transferring it to a transfer material.

  In recent years, a contact charging method has been used as a means for charging the surface of a photoreceptor. The contact charging method is a charging method in which charging is performed by bringing a charging member such as a roller, a magnetic brush, or a fur brush into direct contact with the photosensitive member. Such a contact charging method is attracting attention because it has advantages of low ozone and low power compared to a corona charging method represented by corotron and scorotron. The charging mechanism of the photoreceptor in the contact charging method includes discharge charging and injection charging, and the charging characteristics are determined depending on which is dominant.

  “Discharge electrification” is a mechanism in which a photoconductor is charged by a discharge phenomenon generated in a minute gap formed between a contact charging member and the photoconductor. In discharge charging, ozone, which is a discharge product, is inevitably generated. Therefore, side effects such as image flow may occur.

  On the other hand, “injection charging” is a mechanism in which a charge is directly injected from a contact portion between a contact charging member and the photoreceptor to charge the photoreceptor. A typical configuration for achieving such injection charging is a configuration in which charge is injected by bringing a charging member into contact with a photosensitive member whose resistance value is adjusted by dispersing conductive fine particles in the surface layer (hereinafter referred to as “charging”). A layer whose resistance value is adjusted so that charges can be injected into the photoreceptor is expressed as a “charge injection layer”). Such a system is disclosed in Patent Document 1, for example. Injecting charging does not generate ozone in principle, so there is little hazard to the photoconductor, and unlike discharge charging, the discharge threshold voltage (the voltage at which the photoconductor starts to discharge when voltage is applied to the charging member, This is known as an energy-saving charging method because there is no “discharge start voltage”.

Whether charging or injection charging is dominant when performing contact charging can be determined by examining the relationship between the voltage applied to the charging member and the charging potential on the surface of the photoreceptor. FIG. 1 shows the difference between injection charging and discharge charging from the relationship between the voltage applied to the charging member and the photosensitive member charging potential.
In pure discharge charging (broken line in the figure), the charging potential does not change until the voltage applied to the charging member reaches the predetermined discharge start voltage (V _th ), and after the discharge start voltage is exceeded, the charge potential is Start to change. For this reason, in order to charge the surface of the photoreceptor, it is necessary to apply a voltage equal to or higher than the discharge start voltage (V _th ) to the charging member.

  On the other hand, in pure injection charging (straight line in the figure), the charging potential of the photoreceptor changes in proportion to the voltage applied to the charging member. At this time, a characteristic of this injection charging is that a straight line passes through the origin and no discharge start voltage exists. In order to realize such injection charging, the conventional charge injection layer controls the resistance of the injection layer by dispersing conductive fine particles such as tin oxide and indium oxide in an insulating binder.

  For example, Patent Document 1 discloses tin oxide (described in [0024]) and titanium oxide (described in [0027]) that have been made conductive by doping antimony or indium as conductive particles. Patent Document 2 states that “conducting particles include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, indium oxide doped with tin, tin oxide doped with antimony and tantalum, oxide. Ultrafine particles such as zirconium can be used.These metal oxides are used alone or in combination of two or more ”(described in [0043]).

  These conductive fine particles existing on the surface of the photosensitive member come into contact with the charging member, and when a voltage is applied, a microelectrode (hereinafter referred to as “injection site”) for injecting charge from the charging member to the photosensitive member. It is thought to serve the role of In order to uniformly inject and charge the surface of the photoconductor, it is necessary to form as many injection sites as possible to inject charges. For this purpose, the charge injection layer needs to contain a large amount of conductive fine particles which are injection sites. On the other hand, when a large amount of conductive fine particles are contained in the charge injection layer, the distance between the fine particles is close and the resistance of the surface of the photoconductor is lowered, and the latent image charge formed on the surface of the photoconductor leaks toward the surface of the photoconductor. As a result, the electrostatic latent image tends to collapse. Therefore, since the toner image is blurred or flows, there is a drawback that it is difficult to form a sharp image.

  Therefore, it is necessary to design the conductive fine particles so that they are present in an appropriate distance in the charge injection layer. Due to these constraints, it is difficult to charge uniformly and densely in an injection charging photoreceptor using conductive particles as injection sites in a conventional charge injection layer. There is a drawback that the image quality becomes rough and rough. Furthermore, if there are many hard particles such as metal oxides on the surface, the cleaning blade and the soft image forming member such as the charging member are damaged, resulting in charging irregularities on the streaks and poor cleaning. ing.

  In Patent Document 3, a charge injection layer on a photosensitive layer contains a conductive material whose resistance value reversibly changes by light or heat, and exposure is performed before or after charging, and charging unevenness in injection charging is disclosed. As a conductive material whose resistance value reversibly changes by light or heat, zinc oxide and polyvinyl carbazole are disclosed. However, these photoresponsive conductive substances are substances that absorb in the ultraviolet light region, have a small charging effect, and it is necessary to use ultraviolet light having a wavelength shorter than 400 nm as the light applied to the surface of the photoreceptor. A component (material) of a general photoconductor, particularly an OPC photoconductor composition mainly composed of an organic material, is easily deteriorated by ultraviolet rays. For this reason, for example, image deterioration may occur due to deterioration of the material (structural change) to reduce the electrical resistance of the surface of the photoconductor, or the surface of the photoconductor is likely to be worn due to a decrease in molecular weight, thereby reducing the life of the photoconductor. I will let you. In addition, there is a disadvantage that a memory phenomenon occurs due to high-energy ultraviolet exposure, and an afterimage is generated on the image.

  Patent Document 4 discloses a method in which the photoconductive portion of a latent electrostatic image bearing member having photoconductivity is reduced in resistance by visible light exposure and a voltage is applied to charge the photoconductor. There is no description suggesting the constitution and materials of the photoreceptor of the present invention.

Japanese Patent Laid-Open No. 6-3921 Japanese Patent Laid-Open No. 11-265086 JP 10-31321 A JP 2001-147576 A (Applicant Ricoh)

The object of the present invention is to overcome the above-mentioned drawbacks of conventional charging methods (deterioration of the photoconductor constituent material due to generation of oxidizing gas in the discharge type charging method, generation of abnormal images such as image blur in the charge injection charging method, and It is to solve the deterioration of the imaging member). Specifically, the occurrence of abnormal images can be suppressed by suppressing the generation of ozone, nitrogen oxides, etc. during charging, and the deterioration of image forming members around the photoreceptor can be suppressed, so that repeated use can be performed. An object of the present invention is to provide an electrophotographic photosensitive member capable of forming a good image and enabling a compact charging device.
Another object of the present invention is to provide an image forming apparatus using the photoconductor, and to provide an energy-saving charging system and an image forming apparatus having high durability and high reliability that do not generate an abnormal image even in repeated use. An object of the present invention is to provide an image forming apparatus capable of making the entire apparatus compact, and to provide an image forming apparatus capable of preventing a moire image generated in writing with substantially monochromatic light. It is another object of the present invention to provide a writable image forming apparatus that does not depend on the optical characteristics of the surface of the photoreceptor.
It is another object of the present invention to provide a process cartridge that is easy to handle and can be compactly designed using the photoconductor.

  As a result of intensive investigations on charging methods for electrophotographic photosensitive members that eliminate the conventional drawbacks, the present inventors have found that a photosensitive layer having a photosensitivity for at least image exposure on a conductive support, and at least charging by exposure for charging. It can be charged by applying a voltage by bringing a conductive member into contact with a photoconductor provided with a layer containing a substance that can be generated (hereinafter referred to as “photocharged charge layer”), and further charging the photoconductor It has been found that by applying a voltage simultaneously with or after the exposure, the surface of the photoreceptor is charged and the photoreceptor can be charged to a higher level (hereinafter referred to as “photocharge charging”). In addition, since the charging method using photocharge charging generates almost no ozone or NOx gas, it is possible to provide a compact image forming apparatus with less environmental pollution because the deterioration of the photoreceptor due to the conventional discharge type charging is suppressed. I found out. And the present inventors completed this invention based on said knowledge.

That is, the said subject of this invention can be solved by the electrophotographic photoreceptor of this invention which has the following structures.
(1) Step of performing exposure for charging on the photoconductor, simultaneously with or after exposure for charging, a voltage is applied to the photoconductor through a conductive voltage applying member in contact with the photoconductor, and the voltage An electrophotographic photosensitive member for use in an image forming method comprising a step of charging a photosensitive member surface with the same polarity as an applied voltage from an applying member, wherein the electrophotographic photosensitive member is at least subjected to image exposure on a translucent conductive support. A photosensitive layer having a sensitivity to the photosensitive layer; and a photocharged charge layer containing at least a charge generating substance that generates a charge upon exposure for charging; and the photocharged charge layer is on the surface of the photoreceptor. Electrophotographic photoreceptor.
(2) The electrophotographic photoreceptor as described in (1) above, wherein the charge generating material contained in the photocharged charge layer is an organic pigment.
(3) The electrophotographic photosensitive member as described in (2) above, wherein the organic pigment is an azo pigment.
(4) The electrophotographic photoreceptor as described in (3) above, wherein the azo pigment is an azo pigment represented by the following general formula (I).

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 (II):

In the formula, R ₂₀₃ represents a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, or an aryl group such as a phenyl group. R ₂₀₄ , R ₂₀₅ , R ₂₀₆ , R ₂₀₇ and R ₂₀₈ are each a hydrogen atom, a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, bromine or iodine, a 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.

(5) The electrophotographic photosensitive member as described in (4) above, wherein Cp ₁ and Cp ₂ of the azo pigment are different from each other.
(6) The electrophotographic photosensitive member as described in (2) above, wherein the organic pigment is titanyl phthalocyanine.
(7) The titanyl phthalocyanine is a titanyl phthalocyanine having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 波長) of CuKα. The electrophotographic photosensitive member as described in (6) above, wherein
(8) The titanyl phthalocyanine has a diffraction peak (± 0.2 °) with a Bragg angle of 2θ with respect to CuKα characteristic X-rays (wavelength of 1.542 mm), and further 9.4 °, 9.6 °, and 24.0 °. And has a peak at 7.3 ° as the lowest angled diffraction peak, and has a peak between the 7.3 ° peak and the 9.4 ° peak. The electrophotographic photosensitive member according to (7) above, which has no peak at 26.3 °.
(9) The electrophotographic photosensitive member according to any one of (1) to (8) above, wherein the photocharged charge layer contains a charge transport material.
(10) The electrophotographic photoreceptor as described in (9) above, wherein the charge transport material is a hole transport material.
(11) The electrophotographic photoreceptor as described in (10) above, wherein the hole transport material is a compound having at least a triarylamine structure.
(12) The electrophotographic photosensitive member as described in (9) above, wherein the photocharge charging layer contains a polymer charge transporting substance.
(13) The electrophotographic photosensitive member as described in (12) above, wherein the polymer charge transporting substance is a hole transporting substance.
(14) The electrophotographic photosensitive member as described in (12) above, wherein the polymer charge transporting substance has a crosslinked structure.
(15) The difference between the maximum absorption wavelength of the organic pigment used in the photocharge charging layer and the maximum absorption wavelength of the organic pigment used in the photosensitive layer is in the range of ± 10 nm. The electrophotographic photosensitive member according to any one of (14).
(16) The electrophotographic photosensitive member as described in (15) above, wherein the organic pigment used in the photocharge charging layer and the organic pigment used in the photosensitive layer are the same.
(17) The organic pigment used in the photocharge charging layer is different from the organic pigment used in the photosensitive layer, and the maximum absorption wavelength of the organic pigment used in the photocharge charging layer and the organic used in the photosensitive layer are different. The electrophotographic photosensitive member according to any one of (1) to (16) above, wherein the maximum absorption wavelength of the pigment is 200 nm or more.
(18) The electrophotographic photosensitive member according to any one of (1) to (17) above, wherein a filler is contained in the photocharged charge layer.
(19) The electrophotographic photosensitive member according to any one of (1) to (18) above, wherein the photosensitive layer comprises at least a charge generation layer and a charge transport layer.
(20) The electrophotographic photosensitive member according to any one of (1) to (19), wherein the conductive support has an endless belt shape.

The problems of the present invention can be solved by the image forming apparatus of the present invention having the following configuration.
(21) At least the photosensitive member and a means for exposing the photosensitive member for exposure, and a conductive voltage applying member in contact with the photosensitive member at the same time as or after the exposure for charging. A voltage applying means for applying a voltage to the surface of the photoconductor from the voltage applying member to charge the same polarity as the applied voltage. After charging, image exposure is performed from the inner surface of the photoconductor to charge the electrostatic latent image on the photoconductor. In an image forming apparatus having an image exposure means for forming an image, a developing means for developing the electrostatic latent image with toner, and a means for transferring the developed image to a transfer body, the photoreceptor is the above ( An image forming apparatus comprising the electrophotographic photosensitive member according to any one of 1) to (20).
(22) The image forming apparatus as described in (21) above, wherein a light source having a length of 400 nm or longer is used as the charging exposure means.
(23) The image forming apparatus as described in (22) above, wherein the photocharged layer absorbs 80% or more of the light used for the charging exposure means.
(24) The wavelength of the light used for the exposure means for charging is light in a region where there is no absorption of the charge generating material used for the photosensitive layer, as described in any one of (21) to (23) above Image forming apparatus.
(25) Any of the above (21) to (24), wherein the photocharged charge layer of the photoreceptor has a positive charge transport function, and a negative voltage is applied to the voltage application means. An image forming apparatus according to claim 1.

Furthermore, the problems of the present invention can be solved by the process cartridge of the present invention having the following configuration.
(26) A process cartridge in which a photosensitive member and at least one selected from an exposing unit for charging, a voltage applying unit, a developing unit, a cleaning unit, a neutralizing unit, and a transfer unit are integrated and detachably provided. A process cartridge, wherein the photoconductor is the photoconductor according to any one of (1) to (20).
Hereinafter, the inventions (1) to (26) are referred to as the present inventions (1) to (26).

The effects of the present invention are as follows.
The present invention (1): a photosensitive layer that is at least sensitive to image exposure on a conductive support, and a charge generation material that generates a charge in exposure for charging or a charge generation layer that includes a charge generation material and a charge transport material. And having a photocharged charge layer on the surface of the photoconductor, the voltage is applied to the photoconductor via a conductive voltage applying member that is in contact with the photoconductor at the same time as or after the exposure for charging. Is applied to charge the photocharge charging layer with the same polarity as the applied voltage, and charging without corona discharge, which is a cause of deterioration of the photoconductor, can be provided. In addition, since a translucent support is used, compact writing can be performed by housing the optical system in the photosensitive body.
Furthermore, an environmentally friendly charging method and an image forming apparatus are provided.
Invention (2): Since the charge generating material contained in the photocharge charging layer is an organic pigment, visible light can be used as an exposure light source for charging, and therefore the photoreceptor is deteriorated by ultraviolet light. Therefore, it is possible to provide a long-life photoconductor. In addition, the absorption spectrum has a wide variety compared to inorganic pigments, and the design of the photoreceptor becomes easy.
Invention (3): Since the organic pigment contained in the photocharge charging layer is an azo pigment, it is possible to provide a photoconductor with high photocharge charge efficiency.
Present invention (4): In particular, the azo pigment represented by the formula (I) has a high charge generation ability, is resistant to light fatigue in repeated use, and can provide a photoreceptor having high photocharge charging efficiency.
The present invention (5): Among the formulas (I), the two asymmetric pigments having different coupler components have a very high photocarrier generation ability, and can provide a photoconductor having high photocharge charging efficiency.
Invention (6): Since the organic pigment contained in the photocharge charging layer is titanyl phthalocyanine, a photoconductor with high photocharge charge efficiency can be provided.
Present invention (7): By using titanyl phthalocyanine having a specific crystal (having a maximum diffraction peak at 27.2 degrees), a photoconductor with higher photocharge charging efficiency can be provided.
Invention (8): In particular, a specific crystal titanyl phthalocyanine of a specific crystal makes it possible to provide a photoconductor with higher photocharge charging efficiency.
Invention (9): By containing a charge transport material in the photocharge charging layer, it is possible to provide a photoconductor with higher photocharge charge efficiency.
Present invention (10): Since the charge transport material contained in the photocharge charging layer is a hole transport material, it is possible to provide a photoreceptor having high negative charge charge efficiency.
Present invention (11): The hole transport material contained in the photocharge charging layer is at least one compound having a triarylamine structure, whereby high-speed charging becomes possible.
Invention (12): Use of a polymer charge transporting material as a charge transporting material in the photocharge charging layer reduces wear and scratches on the surface of the photoconductor, and durability capable of stably obtaining uniform photocharge charging. High photoconductor can be provided.
Invention (13): Since the polymer charge transporting material contained in the photocharge charging layer is a hole transporting material, the photocharge charging efficiency of the negative charge is high, and the surface of the photoreceptor is worn and scratched. Thus, it is possible to provide a highly durable photoconductor that can stably obtain uniform photocharge charging.
Present invention (14): The photocharge charging layer contains a polymer charge transporting substance having a crosslinked structure, so that the hardness of the photocharge charge layer is increased, the wear and scratches on the surface of the photoreceptor are less, and uniform. Therefore, it is possible to provide a highly durable photoconductor that can stably obtain a stable photocharge charge.
Present invention (15): Since the absorption spectra of the charge generating material contained in the photocharged charge layer and the photosensitive layer substantially coincide with each other, it becomes possible to make the photosensitive layer hardly absorb the exposure for charging, and efficient charging is achieved. It becomes possible. This can be done by performing image writing from the inside of the photoreceptor.
Present invention (16): This is the same effect as the present invention (15), but the effect is ensured by the fact that both charge generating substances are the same. In addition, the charge injection property is made smooth. Furthermore, cost merit arises.
Invention (17): The maximum absorption peak of the charge generation material contained in the photocharge charge layer and the photosensitive layer (charge generation layer) is 200 nm or more, so that the absorption regions do not overlap with each other and the light is efficient. Charge charging becomes possible.
Present invention (18): Since the photocharged charge layer contains a filler, wear on the surface of the photoreceptor is reduced, and a photoreceptor having a long life can be provided.
Invention (19): The photosensitive layer comprises at least a charge generation layer and a charge transport layer, whereby it is possible to provide a highly sensitive photoconductor for photocharge charging.
Present invention (20): Since the photosensitive member has a flexible endless belt shape, it enables wide contact between the voltage applying means and the photosensitive member, and enables uniform and stable charging by photocharge charging. Highly reliable image forming apparatus that ensures stable development nip between toner and developing member, transfer nip between photoconductor and transfer member, etc., and does not cause abnormal images such as image flow, image blurring, roughness, streaks It is possible to provide a photoconductor that can be designed.

Present invention (21): An energy-saving image forming apparatus capable of forming a highly reliable image without generating an abnormal image such as image flow, image blurring, roughness, and streak-like soil and generating no discharge products. Can be provided.
Invention (22): By using a light source having a length of 400 nm or longer without using ultraviolet rays as the exposure means for charging, it is possible to provide a highly reliable image forming apparatus with little deterioration of the photoreceptor.
Inventions (23) and (24): By preventing charging exposure from being absorbed by the charge generation layer, an apparatus capable of efficient photocharge charging can be provided.
Invention (25): The photocharge charging layer of the photoconductor has a positive charge transport function, and a negative voltage is applied to the voltage applying means, whereby the photocharge charging efficiency is high and the reliability is high speed. An image forming apparatus can be provided.
Invention (26): It is possible to provide a highly reliable process cartridge that does not generate abnormal images such as image flow, image blur, roughness, and streak-like background stains.

  As shown in FIG. 2, the basic structure of the photoconductor of the present invention comprises a photosensitive layer 12 containing at least a charge generating material and a charge transport material on a conductive support 11, and at least a charge generating material laminated thereon. It consists of the photocharge charge layer 13 contained.

  Although the detailed mechanism of the charging mechanism for the photoconductor provided with the photocharged charge layer of the present invention is not clear at present, the present inventors have shown the mechanism of charging and latent image formation as shown below. This will be described with reference to FIG.

(1) When the photoconductor is provided with a photocharged charge layer containing a charge generating material that generates charge upon exposure to the surface of the photoconductor, the surface of the photoconductor layer is both positive and negative when irradiated with light absorbed by the photocharge charge layer. Is generated (FIG. 3A).
(2) When a voltage is applied to a voltage application member (hereinafter sometimes referred to as “charging member”) that contacts the surface of the photoconductor before the charge recombines and disappears, a charge having a polarity opposite to the applied voltage is applied. Moves to the voltage application member, and the photocharge charge layer is charged with the same polarity as the voltage application member (FIG. 3B).
(3) Charges having the opposite polarity to the applied voltage are induced on the conductive support side of the photoreceptor, and the voltage is uniformly applied to the photosensitive layer (FIG. 3 (c)).
(4) As described above, the charge in the present invention is formed only by the internal charges formed in the photocharge charge layer, and for that purpose, the photocharge charge layer absorbs light and generates a charge. It must contain a charge generating material.
(5) In addition, by incorporating a charge transport material simultaneously with the charge generation material in the photocharge charge layer, the separation efficiency of positive and negative charge pairs in the photocharge charge layer, the charge transfer speed can be increased, and the photocharge charge layer Charge transfer between the voltage application member and the voltage application member becomes smooth, and charge charge efficiency can be increased (as a result, a high photoreceptor surface potential can be obtained).
(6) Thereafter, when image exposure for forming an electrostatic latent image according to the original (input signal) (hereinafter, simply referred to as image exposure) is performed, the exposed portion of the photosensitive layer is irradiated with image light. The charge in the photocharge charging layer is neutralized by the photocharge generated by the above, and an electrostatic latent image is formed on the photoconductor (FIG. 3D).

Next, the layer structure of the photoreceptor used in the present invention will be described.
<Photocharge charge layer>
As the charge generation material used for the photocharge charging layer 13 of the present invention, conventionally known materials can be used as charge generation materials for electrophotography. Among these, organic materials can be used effectively. This is because the organic material can arbitrarily control the absorption wavelength depending on the chemical structure. When both the exposure for charging and the exposure for image formation are performed from the surface of the photoreceptor as described later, the photocharge charging layer is formed. Advantages such as efficient generation of photocarriers by differentiating the absorption wavelength region of the charge generation material used from the charge generation material of the photosensitive layer (charge generation layer) which is the lower layer of the photocharge charge layer Can be produced. For this reason, compared with an inorganic material, an organic material can be effectively used for this invention.

  Examples of such organic materials include phthalocyanine pigments such as various metal phthalocyanines and metal-free phthalocyanines, azulenium salt pigments, squaric acid methine pigments, azo pigments having a carbazole skeleton, and azo pigments having a triphenylamine skeleton. Azo pigments having a diphenylamine skeleton, azo pigments having a dibenzothiophene skeleton, azo pigments having a fluorenone skeleton, azo pigments having an oxadiazol skeleton, azo pigments having a bisstilbene skeleton, azo having a distyryl oxadiazol skeleton Pigments, azo pigments having a distyrylcarbazole skeleton, perylene pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, shear Emissions and azomethine pigments, indigoid pigments, bisbenzimidazo - such as Le based pigments.

These charge generation materials can be used alone or as a mixture of two or more. In particular, the azo pigment represented by the formula (I) or a specific crystal form (as a diffraction peak (± 0.2 °) at a Bragg angle 2θ with respect to a characteristic X-ray of CuKα (wavelength 1.542 mm) is at least 27. Since titanyl phthalocyanine (having a maximum diffraction peak at 2 °) has high sensitivity and high durability and is particularly resistant to light fatigue, it can be used effectively as a charge generating material of the present invention. Among them, in the formula (I), those in which Cp ₁ and Cp ₂ are different show particularly high sensitivity among the materials represented by the formula (I), and are very good as the charge generating material of the photoreceptor of the present invention. used. Among the titanyl phthalocyanines having the maximum diffraction peak at 27.2 °, there are further main peaks at 9.4 °, 9.6 °, and 24.0 °, and the diffraction peak at the lowest angle is 7%. A titanyl phthalocyanine crystal having a peak at .3 °, no peak between the peak at 7.3 ° and the peak at 9.4 °, and no peak at 26.3 ° is particularly sensitive. Moreover, the decrease in chargeability in repeated use of the photoconductor is small, and it can be used very well as a charge generating material of the photoconductor of the present invention.

The charge generation material used in the photocharge charge layer is the same as that used in the photosensitive layer (charge generation layer) described later, or has the same absorption spectrum profile (the difference in the maximum absorption wavelength between the two). Those within ± 10 nm can be used satisfactorily. This is because when the exposure in photocharge charging is absorbed by the photosensitive layer, photocarrier generation also occurs in the photosensitive layer in the state of FIG. This is because the charge moves to the position and the charge stored in the photocharge charge layer is partially canceled.
As a method for avoiding this, there are roughly two methods described below.

  One is that the charge generation material used for the photocharge charge layer and the charge generation material used for the photosensitive layer are the same (or the absorption spectrum profile is substantially the same), and the absorption amount of the photocharge charge layer is Is to increase. This prevents the exposure light for charging from reaching the photosensitive layer. In this case, it is desirable that the photocharge charging layer absorb 80% or more of the light for charging exposure, and it is necessary to sufficiently increase the concentration of the charge generating substance in the photocharge charging layer or to increase the film thickness.

  In another method, the charge generation material used for the photocharge charge layer is different from the charge generation material used for the photosensitive layer (charge generation layer) described later, and the absorption wavelength region is made different (the maximum of both). It is preferable that the difference in absorption wavelength is 200 nm or more. In general, organic pigments preferably used as charge generating materials for photoreceptors are often highly molecular aggregates. Therefore, in general, the absorption spectrum is broad. Therefore, in order to make the absorption wavelength region of the charge generation material used in the photocharge charge layer different from the charge generation material used in the photosensitive layer (charge generation layer) described later, the absorption peak position is increased. Need to shift. Specifically, in the range of 400 nm to 1200 nm, if the maximum absorption peak wavelength is 200 nm or more, both absorption regions rarely overlap, and even if they overlap, the wavelength region is slight.

  Such an evaluation method of the absorption wavelength region of the charge generation substance (organic pigment) can be performed as follows. A sample is prepared by coating and drying an optical charge charging layer coating solution and a photosensitive layer (charge generation layer) coating solution, which are used for the photoreceptor, on an optically transparent support. Subsequently, each absorption spectrum is measured with a commercially available spectrophotometer, whereby the absorption profile and the maximum absorption wavelength of the charge generating material are determined. An example of such a measurement result is shown in FIG.

  The absorption spectra of charge generation materials (denoted as CGM A, B, and C in the figure) are respectively shown. For example, it is assumed that charge generation material C is used as the charge generation material of the photosensitive layer. Here, when the charge generating substance A is used for the photocharged charge layer, the overlap of the absorption spectra of both is small, and if the image exposure of approximately 700 nm or more is performed, the photocharge charge layer is hardly absorbed. On the other hand, when the charge generating substance B is used in the photocharge charging layer, the overlap of the absorption spectra of both is very large, not only the image exposure wavelength is very limited, but also the absorption in the photocharge charging layer. In some cases, the photosensitivity of the photoconductor may be reduced. Thus, the distribution of the absorption spectrum of the charge generating material used in the photocharged charge layer and the photosensitive layer is important, and a good combination is obtained when the maximum absorption peak wavelengths of both are separated by 200 nm or more as shown in FIG. It becomes.

  In order to provide a photocharged charge layer on the photosensitive layer, if necessary, the above-described charge generating material is used together with a binder resin and an organic solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, methylethylketone, ball mill, attritor. It can be formed by dispersing in fine particles with a sand mill or the like and applying the solution after diluting the dispersion appropriately. The coating can be performed using a dip coating method, a spray coat, a bead coat method or the like.

  Binder resins used as necessary for the photocharged charge layer include polyamide, polyurethane, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polystyrene, poly- N-vinyl carbazole, polyacrylamide, vinyl chloride resin, vinyl acetate resin, vinyl acetate-vinyl chloride copolymer resin and the like are used. These binder resins can be used alone or as a mixture of two or more.

  Further, the present inventors have found that by adding a charge transport material together with the charge generation material to the photocharge charge layer, the efficiency of photocharge charge is increased, and a higher charge potential can be expressed. . This is because a charge transport material is contained at the same time as the charge generation material, and a positive and negative charge pair that is relatively easily separated by an electric field in the vicinity of the contact interface between the charge generation material and the charge transport material is generated. It is considered that the charge having the opposite polarity to the applied voltage is transported to the charging member via the charge transport material or the charge generating material and charged to the charging member, and charging having the same polarity as the applied voltage occurs.

Examples of charge transport materials that can be added to the photocharge charge layer 13 include a hole transport material and an electron transport material. As described above, the photocharged charge layer of the present invention needs to cause the charge generated by the charging exposure to reach the surface of the photoreceptor (FIG. 3). At this time, the reverse polarity applied to the charging member Need to carry charge. For this reason, a hole transport material is effectively used when negative polarity is applied to the charging member, and an electron transport material is effectively used when positive polarity is applied.

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

  Examples of the hole transport material include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl). ) Propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like. Among them, a compound having a triarylamine structure in a molecule has a high charge transporting ability and can cope with a high-speed process and can be used very effectively in the present invention. These hole transport materials can be used alone or as a mixture of two or more.

In addition, you may contain these electron transport materials and hole transport materials simultaneously. The polarity to be charged on the photocharged charge layer (photoreceptor surface) should be determined to be negative or positive depending on the system design concept of the image forming apparatus to be used. However, most of the image forming apparatuses so far use an organic photoreceptor, and most of them employ a negatively charged photoreceptor. Also, in recent image forming apparatuses, digital writing / development is the mainstream, and the developing system used is combined with this. Further, hole transport materials occupy most of the charge transport materials used for the photoreceptor as materials capable of high-speed charge transfer. Under such circumstances, also in the present invention, the photosensitive layer, which is the lower layer of the photocharge charging layer, should make the best use of the known technology and should be applied to the image forming apparatus. Accordingly, the electrophotographic photosensitive member of the present invention is extremely advantageous in the negatively charged type, and therefore, a hole transport material is effectively used in the photocharged charge layer.
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 photocharge charge layer 13.
The photocharged charge layer 13 composed of these polymer charge transport materials is excellent in scratch resistance and wear resistance.
As the polymer charge transport material, basically, any polymer charge transport material of either hole transport property or electron transport property can be used. However, for the reason described above, the charge transport layer has a hole transport property. Polymer charge transport materials are more effectively used.
A known material can be used as the hole-transporting polymer charge transporting material, 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 (III) to (XII) are preferably used, and these are exemplified below and specific examples are shown.

(III) Formula

In the formula, R ₁ , R ₂ and R ₃ are each independently a substituted or unsubstituted alkyl group or a halogen atom, R ₄ is a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₅ and R ₆ are substituted or unsubstituted. Substituted aryl group, o, p and q are each independently an integer of 0 to 4, k and j are compositions, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, and n is the number of repeating units Represents 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 (III), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

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

(A represents an integer of 1 to 20, b represents an integer of 1 to 2000, and R ₁₀₃ and R ₁₀₄ represent a substituted or unsubstituted alkyl group or aryl group). Here, R ₁₀₁ and R ₁₀₂ , and R ₁₀₃ and R ₁₀₄ may be the same or different. )

(IV) Formula

In the formula, R ₇ and R ₈ represent a substituted or unsubstituted aryl group, and Ar ₁ , Ar ₂ , and Ar ₃ represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (III). In the formula (IV), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

(V) Formula

In the formula, R ₉ and R ₁₀ represent a substituted or unsubstituted aryl group, and Ar ₄ , Ar ₅ , and Ar ₆ represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (III). In the formula (V), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

(VI) formula

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 in the case of the formula (III). In the formula (VI), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

(VII) Formula

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 substituted or unsubstituted Represents a substituted vinylene group. X, k, j and n are the same as in the case of the formula (III). In the formula (VII), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

(VIII) Formula

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, and Y ₁ , Y ₂ and Y ₃ are 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 may be the same or different. X, k, j and n are the same as in the case of the formula (III). In the formula (VIII), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

(IX) Formula

In the formula, R ₁₉ and R _{20 each} represent a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ and Ar ₁₉ represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (III). In the formula (IX), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

(X) Formula

In the formula, R ₂₁ represents a substituted or unsubstituted aryl group, and Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , and Ar ₂₃ represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (III). In the formula (X), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

(XI) Formula

In the formula, R ₂₂ , R ₂₃ , R ₂₄ and R ₂₅ represent a substituted or unsubstituted aryl group, and Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ and Ar ₂₈ represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (III). In the formula (XI), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

(XII) formula

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 in the case of formula (I). In the formula (X), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.
As other hole transporting polymer charge transport materials used in the photocharge charge layer, copolymers of known monomers, block polymers, graft polymers, and star polymers can also be used. Further, for example, as disclosed in JP-A-3-109406, JP-A-5-216249, JP-A-2000-206723, JP-A-2001-34001, etc. A polymer having a two-dimensional or three-dimensional crosslinked structure can be finally used by performing a curing reaction or a crosslinking reaction after film formation in the state of a monomer or oligomer having a group.

In general, the electrophotographic photoreceptor is rubbed with a developer, transfer paper, a cleaning member, and the like in an image forming process, and the photocharged charge layer 13 on the surface of the photoreceptor is worn. Further, the photocharged charge layer 13 on the surface of the photosensitive member is locally damaged by contact with various members when mounted on the image forming apparatus, when detached from the image forming apparatus, or the like. The local flaws and wear parts of the photocharge charge layer 13 have less charge generation material, or if the flaws and wear are severe, the charge generation material disappears and the photocharge charge function, which is a feature of the present invention, is reduced. . For this reason, the scratch potential and the wear portion of the photocharged charge layer have a lower charging potential than the portion where there is no scratch or wear, and the uniformity of charging is lost. It tends to occur.
In general, the mechanical strength of the organic photoconductive film can be reinforced by a binder resin. However, if the amount of the insulating polymer resin is increased, the charge transport property is lowered and the generation efficiency of the photocarrier is lowered. By using a polymer charge transport material that combines the charge transport function and the binder resin function as in the present invention, the photo charge charge layer with higher scratch resistance and wear resistance can be obtained without reducing the photo charge efficiency. Allows formation. Further, by using a cross-linked polymeric charge transport material, the film charge layer has a higher film hardness, and the scratch resistance and abrasion resistance of the photoreceptor can be further enhanced. As described above, the use of the polymer charge transport material for the photocharge charging layer is very effective in providing a photoconductor for charging and charging with higher durability.

Further, the photocharged charge layer 13 may contain a filler in order to enhance the film strength of the layer. Fillers that can be used include organic fillers and inorganic fillers.
Examples of the organic filler material include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, a-carbon powder, and the like, and inorganic filler materials include silica, tin oxide, zinc oxide, Metal oxides such as titanium oxide, alumina, zirconium oxide, indium oxide, antimony oxide, bismuth oxide, calcium oxide, tin oxide doped with antimony, indium oxide doped with tin, tin fluoride, calcium fluoride Inorganic materials such as metal fluorides such as aluminum fluoride, potassium titanate, and boron nitride. Among these fillers, the use of inorganic fillers is advantageous for improving the wear resistance from the viewpoint of the hardness of the fillers. Further, as a filler effective for improving the image quality, a filler having high electrical insulation is preferable, and silica, titanium oxide, alumina, zinc oxide, zirconium oxide, and the like can be used particularly effectively. These fillers having high electrical insulation can be mixed with two or more fillers having high electrical insulation or other fillers.

  In the electrophotographic photosensitive member of the present invention, image exposure is performed subsequent to charging. Image exposure is performed from the inside of the photosensitive member. For this reason, the light transmittance of the conductive support described later is an important item, but conversely, the optical characteristics of the surface layer of the photoreceptor are not involved. Therefore, the material constituting the photoreceptor surface can be used freely. As an extreme example, it is sufficient that the photocharged charge layer can absorb only the exposure for charging, and the layer constituting the surface of the photoreceptor may be a layer that completely blocks light such as black.

<Conductive support>

The conductive support 11 has a volume resistance of 10 ¹⁰ Ω · cm or less and is not particularly limited as long as it is transparent to image light. For example, glass (Pyrex (registered trademark) glass) , Borosilicate glass, soda glass, etc.), transparent inorganic materials such as quartz and sapphire, and transparent resins such as fluororesin, polyester, polycarbonate, polyethylene, polyethylene terephthalate, vinylon, and 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 on the surface directly or dispersed in resin, 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 image writing from the inner surface side, the inner side of the support is preferably smooth.

<Photosensitive layer>
The photosensitive layer 12 in the present invention may be a single layer type or a laminated type, but here, for convenience of explanation, a laminated type will be described first. FIG. 4 shows an example of the photoreceptor of the present invention using a laminated photosensitive layer. In this case, the photoconductor structure is provided with a charge generation layer 12a and a charge transport layer 12b as a photosensitive layer on a conductive support 11, and a photocharge charge layer 13 is laminated on the surface. Further, an undercoat layer 14 is provided between the conductive support and the photosensitive layer.

  First, the charge generation layer 12a will be described. The charge generation layer has a function of absorbing image exposure and generating positive and negative photocharges. Therefore, the charge generation layer is a layer mainly composed of a charge generation material, and a binder-resin may be used as necessary. As the charge generation material, inorganic materials and organic materials can be used.

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

  On the other hand, a known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having a carbazole skeleton, azo pigments having a 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 having a distyrylcarbazole skeleton Pigments, perylene pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, a Jigoido pigments, bisbenzimidazo - such as Le based pigments. These charge generation materials can be used alone or as a mixture of two or more.

  Binder resins used as necessary for the charge generation layer include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, and poly-N-vinylcarbazole. Polyacrylamide is used. These binder resins can be used alone or as a mixture of two or more. Furthermore, you may add a charge transport material as needed.

  Examples of the hole transporting material include the electron donating materials shown below and are used favorably. For example, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styryl Examples include pyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, and thiophene derivatives. These hole transport materials can be used alone or as a mixture of two or more.

Methods for forming the charge generation layer are roughly classified into a vacuum thin film preparation method and a casting method from a solution dispersion system. As the former method, a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used, and the above-described inorganic materials and organic materials can be satisfactorily formed. Further, in order to provide a charge generation layer by the casting method described later, a ball mill using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone together with a binder resin if necessary, the inorganic or organic charge generation material described above, It can be formed by dispersing with an attritor, sand mill or the like, and applying the solution after diluting the dispersion appropriately. The coating can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

Next, the charge transport layer 12b will be described.
The charge transport layer receives the charge generated in the charge generation layer, transports the charge to the interface with the photocharge charge layer (and thus the surface of the photoreceptor), and neutralizes the charged charge on the surface, thereby supporting image exposure. It has a function of forming an electrostatic charge latent image. For this purpose, the charge transport layer is a layer mainly composed of a charge transport material, and is formed by dissolving and coating the charge transport material together with a binder resin as necessary. Binder resins that can be used as needed include polycarbonate with good film properties (bisphenol A type, bisphenol Z type, bisphenol C type, etc., or copolymers thereof), polyarylate, polysulfone, polyester, methacrylic resin, polystyrene, acetic acid Vinyl, epoxy resin, phenoxy resin, etc. are used. These binders can be used alone or as a mixture of two or more.

  The charge transport materials used in the charge transport layer include oxazole derivatives, oxadiazole derivatives (described in JP-A Nos. 52-139065 and 52-139066), imidazole derivatives, triphenylamine derivatives, and benzidine derivatives (Japanese Patent Publication No. Sho). 58-32372), α-phenylstilbene derivatives (described in JP-A-58-190953), hydrazone derivatives (JP-A 55-154955, 55-156594, 55-52063) 56-81850), triphenylmethane derivatives (described in Japanese Patent Publication No. 51-10983), anthracene derivatives (described in Japanese Patent Application Laid-Open No. 51-94829), styryl derivatives (Japanese Patent Application Laid-Open No. 56-29245 and 58-198043), cal Tetrazole derivative (described in JP-A-58-58552), or the like can be used pyrene derivatives.

  Next, the case where the photosensitive layer has a single layer structure will be described. A photoreceptor in which the above-described charge generating material is dispersed in a binder resin can be used. The single-layer photosensitive layer can be formed by dissolving or dispersing a charge generating substance, a charge transporting substance, and a binder resin in an appropriate solvent, and applying and drying them. Further, the photosensitive layer may be a function separation type to which the above-described charge transport material is added, and can be used satisfactorily. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.

  As the binder resin, in addition to the binder resin previously mentioned in the section of the charge transport layer 12b, the binder resin mentioned in the section of the charge generation layer 12a may be mixed and used. The amount of the charge generating material with respect to 100 parts by weight of the binder resin is preferably 5 to 40 parts by weight. The amount of the charge transport material is preferably 0 to 190 parts by weight, and more preferably 50 to 150 parts by weight. The single-layer photosensitive layer is formed by dip coating or spray coating with a coating solution dispersed with a disperser or the like using a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexane together with a charge transport material and a charge transport material if necessary. It can be formed by coating with a bead coat or the like. The thickness of the single photosensitive layer is suitably about 5 to 50 μm. More preferably, it is 10-25 micrometers.

<Underlayer>
Next, the undercoat layer 14 will be described.
In the electrophotographic photosensitive member of the present invention, an undercoat is optionally provided between the conductive support and the photosensitive layer (between the conductive support and the charge generation layer when the photosensitive layer is a laminated type). A layer can be provided. The undercoat layer is provided for the purpose of improving adhesiveness, charge blocking, improving the coatability of the upper layer, and reducing the residual potential. The undercoat layer generally contains a resin as a main component. However, considering that the photosensitive layer is applied with a solvent on these resins, the resin may be a resin having a high solvent resistance with respect to a general organic solvent. desirable.

  Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and polyacrylic acid, alcohol-soluble resins such as copolymerizable nylon and methoxymethylated nylon, polyurethane, melamine resins, alkyd-melamine resins, and epoxy resins. And a curable resin that forms a three-dimensional network structure. Further, fine powders such as metal oxides exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like, or metal sulfides and metal nitrides may be added.

Furthermore, a metal oxide layer formed by using, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like as the undercoat layer of the present invention is also useful. In addition to this, the undercoat layer of the present invention is formed by anodizing aluminum oxide, organic matter such as polyparaxylylene (parylene), SiO, SnO ₂ , TiO ₂ , ITO, CeO _2, etc. What provided the inorganic substance with the vacuum thin film preparation method can also be used favorably.

  These undercoat layers need to sufficiently transmit writing light for image formation. When the undercoat layer absorbs the exposure for image formation, the amount of light reaching the photosensitive layer (charge generation layer) decreases accordingly. As a result, the photosensitivity of the photoconductor is lowered, the potential difference between the bright part potential and the dark part potential is reduced, and it becomes difficult to obtain the contrast of the image. For this reason, the material and structure used for the undercoat layer are preferably those that do not absorb in the wavelength region of image forming exposure.

  Further, in the photoreceptor of the present invention, an antioxidant can be added for the purpose of preventing the decrease in sensitivity and the increase in residual potential, in order to improve the environmental properties. The antioxidant may be added to any layer containing an organic substance, but good results are obtained when it is added to a layer containing a charge transport material.

Examples of the antioxidant that can be used in the present invention include the following.
(Monophenol compound)
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate and the like.

(Bisphenol compound)
2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4′-thiobis- ( 3-methyl-6-t-butylphenol), 4,4′-butylidenebis- (3-methyl-6-t-butylphenol) and the like.

(High molecular phenolic compounds)
1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t- Butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis ( 4'-hydroxy-3'-t-butylphenyl) butyric acid] cricol ester, tocopherols and the like.

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

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

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

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

  These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained. The addition amount of the antioxidant in the present invention is 0.1 to 100 parts by weight, preferably 2 to 30 parts by weight with respect to 100 parts by weight of the charge transport material.

Next, an electrophotographic image forming method and an image forming apparatus according to the present invention will be described in detail with reference to the drawings.
FIG. 5 is a schematic diagram for explaining an electrophotographic apparatus, which is used for image formation in an embodiment of the present invention. In FIG. 5, a photosensitive member 1 includes a light-transmitting conductive support, a photosensitive layer having photosensitivity at least for image exposure for image formation, and a charge generating material that generates charges by at least charging exposure. It is a photoreceptor having a photocharged charging layer.

  The charging exposure means 2 can be used as long as it is a light source containing light having a wavelength that is absorbed by the photocharged charging layer of the photoreceptor. For example, a halogen lamp, a fluorescent lamp, a mercury lamp, a xenon lamp, a laser light source, and an LED can be used. In general, a photoconductor is easily deteriorated by ultraviolet rays. Therefore, it is preferable to use light of 400 nm or more as charging light. Therefore, as the exposure means for charging, those incorporating a means for cutting off ultraviolet light such as a filter, an optical diffraction grating, or an apparatus can be used. The charging exposure means can be integrated with other members such as a voltage applying member and a photosensitive member. For example, it is possible to incorporate an exposure means for charging inside the transparent voltage application member in which the surface of a cylindrical hollow body made of glass or plastic is processed to be translucent and conductive as the voltage application means. By installing the charging exposure means in this way, not only can the image forming apparatus be designed in a compact manner, but also the charging exposure and voltage application can be performed at the same time, thereby enhancing the light charging effect. Can do.

  In charging exposure, it is important that the photocharge charging layer sufficiently absorbs light, but it is also important not to allow light to reach the photosensitive layer (charge generation layer). In the state of FIG. 3C, when the exposure for charging reaches the photosensitive layer (charge generation layer) sufficiently, photocarriers are generated in the same manner as when image light is written on the photoreceptor. For this reason, one of the positive and negative charges stored in the photocharge charge layer (which is determined by the charge polarity) may be canceled, and the photoreceptor may be insufficiently charged.

  For this reason, in the image forming apparatus of the present invention, it is important that the photocharged charge layer absorbs 80% or more of the light used for charging exposure, and preferably 100% is absorbed. In addition, the use of light in a wavelength region in which the photosensitive layer (charge generation layer) does not absorb as the charging exposure is effectively used in the present invention. That is, it is sufficient that the exposure for charging is sufficiently absorbed in the photocharge charging layer as described above. However, if the charge generating material used in the photosensitive layer (charge generation layer) does not absorb the exposure for charging even in such a case, Carriers are not generated, and the above-described problems do not occur.

  Such an example will be described with reference to the drawings. Assume that the charge generation material (CGM A) shown in FIG. 10 is used as the charge generation material of the photosensitive layer and the charge generation material (CGM C) is used as the charge generation material of the photocharge charge layer. At this time, by setting the exposure wavelength for charging to light near 800 nm, the absorption of CGM C is very large (absorption efficiency is high), and the charge generation substance concentration in the photocharge charge layer is increased, or the photocharge By increasing the thickness of the charge layer, the exposure for charging can be absorbed by 80% or more (preferably 100%). In consideration of the influence on the other characteristics of the photoreceptor, etc., even if the charge generation material concentration and film thickness cannot be set to the above levels, the charge generation material (CGM A) used for the photosensitive layer (charge generation layer) There is no absorption in the vicinity of 800 nm, and even if the exposure for charging partially passes through the photocharged charge layer, photocarrier generation does not occur in the photosensitive layer (charge generation layer), and the photosensitive member is sufficiently charged. It is.

The voltage applying unit 3 is a unit that comes into contact with the photoconductor 1 and charges the photocharge charging layer by applying a voltage to the photoconductor 1 by a power source (not shown) to charge the photoconductor 1 to a desired potential. . For this reason, the voltage application member that comes into contact with the surface of the photoreceptor needs to have sufficient conductivity. The conductivity can be described by the resistance value of the voltage application member, and is 10 ¹¹ Ω · cm or less, preferably 10 ⁹ Ω · cm or less, more preferably 10 ⁷ Ω · cm or less.

As the voltage application member, a material obtained by processing a conductive material such as metal, conductive rubber, or conductive plastic into a roller shape, a plate shape, or a brush shape can be used. An elastic conductive roller in which conductive rubber in which conductive fine particles such as carbon are dispersed in silicone rubber or urethane rubber is coated on a conductive core roll such as metal can be used. The resistance of the conductive roller is preferably 10 ¹⁰ Ω · cm or less. In the embodiment of the present invention, a conductive roller was used in which a conductive urethane elastic layer having a volume resistivity of about 10 ⁴ Ω · cm was provided on a stainless steel shaft having a diameter of 8 mm.

  A magnet roll fixedly supported; a non-magnetic sleeve rotatably provided on the outside of the magnet roll; and magnetic particles adsorbed on the non-magnetic sleeve by the magnetic force of the magnet roll. It is also possible to use a so-called magnetic brush voltage application member which is designed so that a magnetic brush is formed by raising a magnetic force and this magnetic brush and the photosensitive member come into contact with each other.

  Furthermore, a conductive fiber obtained by processing a conductive plastic can also be used. Furthermore, it is also possible to use a so-called conductive brush in which they are densely planted on a conductive metal roll or a plate-like support. It is also possible to use a conductive woven fabric in which a conductive carbon fiber cloth is attached to a roll or a plate-like support. A DC voltage having a desired polarity is applied to these voltage application members, but an AC voltage may be superimposed on the DC voltage in order to improve charging uniformity.

  The image exposure means 4 is an image exposure means generally used in electrophotography, and can be used as long as it can be disposed inside the photoconductor used. For example, an LD, LED, phosphor dot array, or the like is used as a digital light source.

Arranging the image exposure means inside the photoreceptor in this way produces the following effects.
One is that the device is compact. This is because when the image exposure is performed from the photosensitive member surface side, the apparatus becomes large due to the arrangement of the optical system. In the case of the present invention, an exposure means for charging is necessary, which has the effect of not making the apparatus unnecessarily large.

  Second, it does not depend on the optical characteristics of the surface layer of the photoconductor for the exposure of the writing light. In general, the material constituting the surface of the photoreceptor needs to be transparent to image exposure, and this reduces the degree of freedom in designing the photoreceptor. For example, when a filler or the like is added to the surface layer in order to improve mechanical durability, its dispersibility, addition amount, refractive index, etc. are very limited, making design difficult. In addition, attempts are made to add a lubricant or wax to reduce the friction coefficient of the surface. However, if the surface of the photoreceptor becomes cloudy, use is limited. Further, even when scratches or the like occur on the surface of the photoconductor due to repeated use of the photoconductor, the writing light is scattered and the image quality is deteriorated. All of these problems can be solved by irradiating image light from the inside of the photoconductor.

  Third, there is no moiré. Recently, the use of coherent light such as a laser is increasing for precision writing. However, if there is a reflecting surface in the structure of the photoreceptor, the writing light and the reflected light interfere with each other, so-called moire occurs. However, when a translucent support is used and writing is performed from the inside of the photoconductor, there is no reflective surface and no moiré occurs.

  After an electrostatic charge latent image is formed on the surface of the photoreceptor, a toner image is formed by the developing means 5. The toner image formed on the surface of the photoreceptor is transferred to a transfer body such as transfer paper 9 by the transfer unit 6. In addition to the direct transfer to the transfer member as shown in FIG. 5, the toner image may be transferred to the transfer member by using a so-called intermediate transfer method in which the toner image is transferred to the intermediate transfer member and then transferred to the final transfer member. Thereafter, the toner image is fixed on the transfer paper by fixing means (not shown). Residual toner on the photoreceptor 1 is removed by a cleaning means 7 such as a cleaning fur brush or a cleaning blade, and the next electrophotographic cycle is started. If necessary, the charge on the surface of the photosensitive member may be discharged before charging by using a discharging means 8 such as a discharging lamp.

  FIG. 6 shows another example of the electrophotographic process and apparatus according to the present invention. The photoreceptor 1 is an endless belt-like photoreceptor having at least a photosensitive layer and a photocharged charging layer containing a charge generating substance on a conductive support. This endless belt-like photoreceptor is driven and supported by drive rollers 9a and 9b and moves in the direction of the arrow. The photoreceptor 1 is charged and charged by the voltage application unit 3 and forms an electrostatic latent image by image exposure by the image exposure unit 4.

The electrostatic latent image is developed with toner by the developing unit 5 and transferred onto a transfer member such as paper by the transfer unit 6. The image on the transfer body is fixed by fixing means (not shown).
Residual toner on the photoreceptor 1 is removed by a cleaning means 7 such as a cleaning fur brush or a cleaning blade, and the next electrophotographic cycle is started. If necessary, the charge on the surface of the photosensitive member may be discharged before charging by using a discharging means 8 such as a discharging lamp.

Since the support of the photosensitive member 1 is light transmissive, an image exposure means, a static elimination light source, and the like can be installed inside the belt, and light irradiation can be performed from the support side, which has an advantage that the apparatus is compact.
The belt-shaped photosensitive member and the driving / supporting roller can be integrated into a unit so that it can be freely attached to and detached from the apparatus.

  The image forming method and the image forming apparatus of the present invention are not limited to the above examples. At least, the photosensitive member having a photocharged charge layer containing a charge generating substance is charged and charged, and an electrostatic latent image is obtained by exposure. Any image forming apparatus including a step of forming an image may be used.

  The image forming method and apparatus as described above may be fixedly incorporated in a copying apparatus, a facsimile machine, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is a single device (incorporating a photosensitive member having exposure means on the inside, and including charging exposure means, voltage application means, development means, cleaning means, static elimination means, transfer means, etc.) Parts).

FIG. 7 shows an example of the process cartridge of the present invention. Around the periphery of the photoreceptor 1 are a voltage application roller 2 as a charging member, a developing means 5 for supplying an appropriate amount of developer to the surface of the photoreceptor 1 and a cleaning means 7 having a blade for cleaning the surface of the photoreceptor after image transfer. Built in. This cartridge is formed so that it can be detachably handled by an image forming apparatus having means necessary for image formation, such as image exposure means, transfer means, static elimination means, fixing means, and recording paper transport means.
The photoreceptor 1 mounted on the cartridge is a photoreceptor having at least a photosensitive layer and a photocharged charge layer containing a charge generating substance on a translucent conductive support.

<Production of cylindrical support>
As a translucent support, a cylindrical support having an outer diameter of 100 mm was produced as follows in accordance with the method described in Example 1 of JP-A-11-288115.
Azobisisobutyronitrile (AIBN) is added as a polymerization initiator to a mixture in which the blending ratio of benzyl methacrylate (BzMA) monomer and methyl methacrylate (MMA) monomer is 20/80, and 50 ° C., 3 hr. Preliminary polymerization was carried out by heating 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 600 mm, and the mold is rotated and adhered along the inner wall of the mold by centrifugal force, and the entire mold is heated at 60 ° C. for 9 hours. 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 an end cutting process to obtain a cylindrical support having an outer diameter of 100 mm and a length of 360 mm.

<Coating of conductive layer>
On the cylindrical support obtained as described above, the following conductive layer coating solution composition was applied to a dry film thickness of 0.5 μm, heat-treated at 80 ° C. for 30 minutes to form a conductive layer, A transparent support for an electrophotographic photosensitive member was obtained.

(Conductive layer coating solution composition)
1000 g of conductive paint X-101H manufactured by Sumitomo Metal Mining Co., Ltd.
1000g of toluene

<Formation of undercoat layer>
An undercoat layer coating solution having the following composition was applied on a cylindrical support having an outer diameter of 100 mm by a dipping method so that the film thickness after drying was 0.2 μm to form an undercoat layer.

(Coating liquid for undercoat layer)
Zirconium tetraacetylacetonate (ZC150: manufactured by Matsumoto Kosho) 3 parts γ-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) 5 parts Isopropyl alcohol 400 parts

<Formation of charge generation layer>
On the undercoat layer, the following charge generation layer coating solution was dip coated and dried by heating to form a charge generation layer.

(Coating solution for charge generation layer)
Bisazo pigment of the following structural formula (1) 5 parts by weight Butyral resin (ESREC BMS: Sekisui Chemical) 2 parts by weight Cyclohexanone 60 parts by weight
20 parts by weight of methyl ethyl ketone

<Formation of charge transport layer>
Next, the charge generation layer is dip-coated using a charge transport layer coating solution containing the following structural formula (2) charge transport material, heated and dried at 130 ° C. for 20 minutes, and a charge having a thickness of 20 μm. A transport layer was formed.

(Coating liquid for charge transport layer)
Bisphenol Z-type polycarbonate (viscosity average molecular weight 50,000) 1 part by weight Charge transport material of the following structural formula (2) 1 part by weight Tetrahydrofuran 10 parts by weight

<Formation of photocharged charge layer>
On the charge transport layer thus prepared, the following photocharge charge layer coating solution was applied by spray coating, dried at room temperature, and then heat dried at 160 ° C. for 20 minutes to form a 1 μm thick photocharge charge layer. Then, a photoconductor for charge charging was prepared.

(Photocharged charge layer coating solution)
3 parts by weight of the bisazo pigment of the structural formula (1) 3 parts by weight of a charge transporting material of the following structural formula (3) 1 part by weight of THF 100 parts by weight of cyclohexanone 40 parts by weight of bisphenol Z type polycarbonate (viscosity average molecular weight 50,000)

<Evaluation>
The charge generation layer coating solution and the photocharge charge layer coating solution prepared as described above were each applied and dried on a quartz glass substrate under the same conditions as the photoconductor, and the respective absorption spectra were then commercially available. The absorption spectrum was measured with a spectrophotometer (Hitachi: UV-3100). As a result, the absorption spectra of the charge generation layer and the photocharge charging layer almost coincided with the absorption spectrum of CGM A shown in FIG. 11, and the maximum absorption peak wavelength was 583 nm. Further, the transmittance at 645 nm of the photocharged charge layer was 10%.

The photocharge charging characteristics of the photoconductor thus prepared were measured as follows using a charging characteristic measuring apparatus shown in FIG.
A photosensitive member rotating at a speed of 200 mm / s was brought into contact with a silicon rubber roller having a diameter of 16 mm and an electric resistance of 10 ⁴ Ω · cm, and the charged potential was measured when a voltage of −400 V was applied in the accompanying state. An LED having a wavelength region of 645 nm was used as exposure light for charging. The charging potential (V _OFF ) when not exposed was −150 V, and the charging potential (V _ON ) when the LED was turned on was −270 V.
When 655 ± 10 nm light was exposed to the photosensitive member charged by turning on the LED using an optical system set inside the photosensitive member and exposed to 0.5 μJ / cm ² , the charged potential was attenuated, and The potential (VL) was -20V.

FIG. 9 shows the charging characteristics when the applied voltage is changed from −400 V to +400 V when the LED is exposed and when it is not exposed. Compared with the case where the LED is not exposed, the charging of the photosensitive member is increased by the LED exposure. In addition, the charging potential increases in proportion to the applied voltage, and the discharge start voltage _Vth peculiar to the discharge charging is not observed, suggesting that the photoreceptor of the present invention is charged by photocharge charging. .

Next, using this photoreceptor, an image was formed by the image forming apparatus shown in FIG. The image forming method will be described below.
Immediately after irradiating the photosensitive member 1 with LED light (1 μJ / cm ² ) in the wavelength region of 645 nm by the charging exposure means 2, volume resistance is formed on a stainless steel shaft having a diameter of 8 mm as a voltage application member of the voltage application means 3. Using a conductive roller provided with a conductive urethane elastic layer having a rate of about 10 ⁴ Ω · cm, this was brought into contact with the surface of the photoreceptor, and a voltage of −500 V was applied. The initial charging potential of the photoreceptor 1 was −320V. The image exposure means 4 is a device for writing a latent image on the charged photoreceptor 1 in accordance with image information, and it exposes a 600 dpi dot image with an optical scanning device using a laser beam having an oscillation wavelength of 655 nm and a polygon mirror mirror. did. The potential of the exposed portion at the time of exposing the entire surface of the photoreceptor was -20V. As developing means, reversal development was performed using a two-component developer composed of a negatively charged toner and a magnetic carrier. In the transfer, a positive voltage was applied to a conductive charging roller and transferred onto paper. For cleaning, fur brush cleaning was used. When an image was formed under the above conditions, a clear image with no image blur, a uniform halftone portion, and no roughness was obtained.

Next, the following forced fatigue test was conducted in order to investigate the deterioration of the photoreceptor when the charging method of the present invention was repeated.
10000 nm LED light irradiation, −500 V voltage application, and 655 nm laser entire surface exposure test were repeated 10,000 times on the photoreceptor, then in a temperature and humidity environment of 25 ° C., 50% RH, 30 ° C., 85% RH. Thus, when an image was created by the same method as the initial image formation, a clear dot image similar to the initial one with no image blur and image flow was obtained.

A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the film thickness of the photocharged charge layer in Example 1 was changed and the transmittance at 645 nm was changed to 20%.
As in the case of Example 1, the charging potential when a voltage of −400 V was applied was measured. The charging potential (V _OFF ) when not exposed was −150 V, and the charging potential (V _ON ) when the LED was turned on was −240 V. Further, when 655 ± 10 nm light was exposed to 0.5 μJ / cm ^{2 on} the photosensitive member charged by turning on the LED, the charged potential was attenuated and the potential (VL) of the exposed portion became −20V.
Further, when image formation was performed with the image forming apparatus shown in FIG. 5, the initial charging potential of the photosensitive member was −300 V with an applied voltage of −500 V. When image formation was performed in the same manner as in Example 1, a clear image with no image blur, a uniform halftone portion, and no roughness was obtained.

A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the film thickness of the photocharged charge layer in Example 1 was changed and the transmittance at 645 nm was changed to 30%.
As in the case of Example 1, the charging potential when a voltage of −400 V was applied was measured. The charging potential (V _OFF ) when not exposed was −150 V, and the charging potential (V _ON ) when the LED was turned on was −170 V. Further, when 780 ± 10 nm light was exposed to 0.5 μJ / cm ^{2 on} the photosensitive member charged by turning on the LED, the charged potential was attenuated and the potential (VL) of the exposed portion became −30V.
Further, when image formation was performed with the image forming apparatus shown in FIG. 5, the initial charging potential of the photosensitive member was −210 V with an applied voltage of −500 V. When image formation was performed in the same manner as in Example 1, no image blur occurred, but an image having a slightly lower image density than that in Example 1 was obtained.

  The photocharged charge layer in Example 1 was changed to a photocharged charge layer coating solution having the following composition to prepare a photoreceptor, and evaluation was performed in the same manner as in Example 1.

(Photocharged charge layer coating solution)
3 parts by weight of a bisazo pigment of the following structural formula (4) 3 parts by weight of a charge transporting substance of the structural formula (3) 1 part by weight of THF 100 parts by weight of cyclohexanone 40 parts by weight of bisphenol Z type polycarbonate (viscosity average molecular weight 50,000)

In the same manner as in Example 1, the absorption spectrum of the photocharged charge layer was measured. As a result, the absorption spectrum of the photocharged charge layer almost coincided with the absorption spectrum of CGM A shown in FIG. 11, and the maximum absorption peak wavelength was 583 nm.
As in the case of Example 1, the charging potential when a voltage of −400 V was applied was measured. The charging potential (V _OFF ) when not exposed was −140 V, and the charging potential (V _ON ) when the LED was turned on was −320 V. Further, when 655 ± 10 nm light was exposed to 0.5 μJ / cm ^{2 on} the photosensitive member charged by turning on the LED, the charged potential was attenuated and the potential (VL) of the exposed portion became −20V.

  Further, when image formation was performed with the image forming apparatus shown in FIG. 5, the initial charging potential of the photosensitive member was −360 V with an applied voltage of −500 V. When image formation was performed in the same manner as in Example 1, a clear image with no image blur, a uniform halftone portion, and no roughness was obtained. The contrast of this image was higher than that of the image of Example 1.

A photoconductor was prepared in the same manner as in Example 1 except that a bisazo pigment having the following structure was used as the charge generating material of the photocharge charging layer of Example 1.
Using this photoconductor, the charge characteristic was measured using the charge characteristic measuring apparatus in the same manner as in Example 1. As a result, the charge potential showed charge charge charge characteristics that increased in proportion to the applied voltage, and V _{OFF was} applied at the applied voltage of −400V. = −140V, V _ON = −190V, and VL = −10V.

  Using this photoreceptor, an image was formed under the same conditions using the same image forming apparatus as in Example 1. As a result, there was no image blur and an image having a slightly lower density than that in Example 1 was obtained.

  The photocharged charge layer in Example 1 was changed to a photocharged charge layer coating solution having the following composition to prepare a photoreceptor, and evaluation was performed in the same manner as in Example 1.

(Photocharged charge layer coating solution)
3 parts by weight of titanyl phthalocyanine pigment (XD spectrum is shown in FIG. 12)
Charge transport material of the above structural formula (3) 3 parts by weight Bisphenol N type polycarbonate (viscosity average molecular weight 50,000) 1 part by weight THF 100 parts by weight cyclohexanone 40 parts by weight

The titanyl phthalocyanine pigment used in the coating solution further has a Bragg angle 2θ diffraction peak (± 0.2 °) with respect to CuKα characteristic X-rays (wavelength 1.542 mm), and further 9.4 ° and 9.6 °. The main peak at 24.0 ° and the lowest diffraction peak at 7.3 ° and between the 7.3 ° peak and the 9.4 ° peak. Is a titanyl phthalocyanine having no peak and no peak at 26.3 °.
The titanyl phthalocyanine pigment was synthesized according to Synthesis Example 1 described in paragraph No. [0140] of JP-A No. 2001-19871.

  In the same manner as in Example 1, the absorption spectrum of the photocharged charge layer was measured. As a result, the absorption spectrum of the photocharged charge layer almost coincided with the absorption spectrum of CGM C shown in FIG. 11, and the maximum absorption peak wavelength was 800 nm.

As in the case of Example 1, the charging potential when a voltage of −400 V was applied was measured. However, the charging exposure member was changed to a 740 nm LED. The charging potential (V _OFF ) when not exposed was −150 V, and the charging potential (V _ON ) when the LED was turned on was −310 V. Further, when 655 ± 10 nm light was exposed to 0.5 μJ / cm ^{2 on} the photosensitive member charged by turning on the LED, the charged potential was attenuated and the potential (VL) of the exposed portion became −20V.

  Further, when an image was formed with the image forming apparatus shown in FIG. 5, the initial charging potential of the photosensitive member was −350 V with an applied voltage of −500 V. When image formation was performed in the same manner as in Example 1, a clear image with no image blur, a uniform halftone portion, and no roughness was obtained. The contrast of this image was higher than that of the image of Example 1.

  A photoconductor was prepared in the same manner as in Example 1 except that the compound of the following structural formula (6) was contained instead of the compound of the structural formula (3) of the charge transport material of the photocharged charge layer of Example 1.

As a result of measuring the charging characteristics and the light attenuation characteristics in the same manner as in Example 1, the charging potential shows charge charging characteristics proportional to the applied voltage. When a voltage of −400 V is applied, V _OFF = −100 V and V _ON = −290 V. A charging potential was indicated, and VL = −10V.

  Using this photoreceptor, an image was formed under the same conditions using the same image forming apparatus as in Example 1. As a result, there was no image blur, and the halftone portion was uniform and a clear image without a feeling of roughness was obtained. . Further, in the same manner as in Example 1, only 740 nm LED light irradiation, −500 V voltage application, and 655 nm laser entire surface exposure were repeated 10,000 times to perform a forced fatigue test, followed by 25 ° C., 50% RH. When an image was formed by the same method as the initial image formation in a temperature and humidity environment of 30 ° C. and 85% RH, a clear dot image similar to the initial image without image blur and image flow was obtained. It was.

  A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the charge transport material of the photocharge charging layer in Example 1 was changed to the charge transport material of the following structural formula (7).

As a result of measuring the charging characteristics and the light attenuation characteristics in the same manner as in Example 1, the charging potential shows charge charging characteristics proportional to the applied voltage. When a voltage of −400 V is applied, V _OFF = −100 V and V _ON = −190 V. A charging potential was indicated, and VL = −10V. Using this photoconductor, an image was formed under the same conditions using the same image forming apparatus as in Example 1. As a result, there was no image blur and an image having a slightly lower image density than that of Example 1 was obtained. It was.

[Comparative Example 1]
A photoconductor was prepared in the same manner as in Example 1 except that the photocharged charge layer was not provided in Example 1.
The charging characteristics were measured by applying a voltage of −400 V in the same manner as in Example 1, but V _OFF = 0V and V _ON = + 5V.
Next, in place of the voltage application roller of the image forming apparatus used in Example 1, a non-contact charging roller for discharge charging is mounted, and the surface of the photoreceptor is charged by −350 V by discharging, and Example 1 is performed. When an image was formed in the same manner as in Example 1, a clear initial image was obtained as in Example 1.

Then, after repeating only −340V charging and exposure by corona discharge 10,000 times, an image was formed in an environment of 25 ° C., 50% RH, 30 ° C., and 85% RH. The image was blurred. In addition, image flow occurred in an environment of 30 ° C. and 85% RH.
As described above, if charging is performed by photocharge charging using a photoconductor composed of at least a photoconductive layer and a photocharged charge layer on the conductive support of the present invention, the conventional discharge charge can be used. In addition, it is possible to provide an image forming apparatus in which the photoreceptor is not deteriorated and image blur and image flow are less likely to occur.

  Using an endless belt-shaped translucent support composed of a polyethylene terephthalate film (thickness 30 μm, circumference length 180 mm, belt width 340 mm) having a Hastelloy conductive layer on the surface, the same composition and film thickness as in Example 1 are formed thereon. The endless belt-shaped photoconductor was prepared by providing a charge generation layer, a charge transport layer, and a photocharge charge layer (no undercoat layer was formed).

This photoreceptor was subjected to image formation with the image forming apparatus shown in FIG. At that time, the endless belt photoreceptor was driven by two rollers having a diameter of 25 mm and rotated at a speed of 100 mm / s.
The exposure light source for charging is 645 nm LED light (1 μJ / cm2), a silicon rubber roller with a diameter of 16 mm and an electric resistance of 10 ⁴ Ω · cm is brought into contact as a voltage application member, and a charging potential when a voltage of −500 V is applied in the accompanying state. As a result, -400 V was charged.

The image exposing means 4 exposed a 600 dpi dot image with an optical scanning device using a laser beam having an oscillation wavelength of 655 nm and a polygon mirror mirror. For development, reversal development was performed using a two-component developer composed of a negatively charged toner and a carrier. The transfer means applied a positive voltage to the conductive roller to transfer the toner image onto paper. As the cleaning means, a fur brush was used to reduce wear on the surface of the photoreceptor. In addition, the photoconductor, the two driving rollers, and the voltage application roller were integrated and unitized so as to be detachable from the electrophotographic apparatus.
When an image was formed using such an apparatus, a uniform and clear image having no image blur and a feeling of roughness was obtained even in the halftone image portion.

  A photoconductor for charging and charging was prepared in the same manner as in Example 1 except that a photocharged charge layer having a dry film thickness of 1 μm was provided on the surface of the photosensitive layer using the following photocharged charge layer coating solution.

(Photocharged charge layer coating solution)
3 parts by weight of the bisazo pigment of the structural formula (1) 3 parts by weight of the charge transporting material of the structural formula (3) 1 part by weight of bisphenol Z type polycarbonate (viscosity average molecular weight 50,000) 1 part by weight of alumina (average primary particle size: 0) .3 μm, “AA03” manufactured by Sumitomo Chemical)
Tetrahydrofuran 100 parts by weight Cyclohexanone 40 parts by weight

The photoconductor was measured for charging characteristics and photosensitivity in the same manner as in Example 1, and was charged with V _OFF = −150 V and V _ON = −250 v with an applied voltage of −400V.
When this photoreceptor was used to form an image in the same manner as in Example 1, a clear image was obtained. The photoreceptor was subjected to repeated forced fatigue tests only for charging and exposure in the same manner as in Example 1, and then the same as in the initial image formation in a temperature and humidity environment of 25 ° C., 50% RH, 30 ° C., and 85% RH. When an image was formed by this method, a clear dot image similar to that in the initial stage without image blur and image flow was obtained in any environment.

  Further, 10,000 continuous images were formed on the photoconductor of Example 1 and the photoconductor of Example 10 using the image forming apparatus shown in FIG. In the photoconductor of Example 1, slight streak-like scratches occurred on the surface of the photoconductor after forming 10,000 images, and slight streak-like image defects occurred in the output image. On the other hand, in the photoreceptor of Example 10, no scratches or the like were observed on the surface of the photoreceptor, and no defect was observed in the image after 10,000 sheets.

<Formation of undercoat layer>
On the same light-transmitting cylindrical support as in Example 1, an undercoat layer coating solution having the following composition was applied by an immersion method so that the film thickness after drying was 0.3 μm to form an undercoat layer. did.

(Coating liquid for undercoat layer)
Alcohol-soluble nylon 3 parts Methanol 70 parts Butanol 30 parts

<Formation of charge generation layer>
On this undercoat layer, the following charge generation layer coating solution was dip-coated and dried by heating at 110 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.3 μm.

(Coating solution for charge generation layer)
5 parts by weight of titanyl phthalocyanine pigment (XD spectrum is shown in FIG. 12)
Butyral resin (ESREC BX-1: Sekisui Chemical) 2 parts by weight Methyl ethyl ketone 80 parts by weight

<Formation of charge transport layer>
Next, dip coating was performed on the charge generation layer using a charge transport layer coating liquid having the following composition, followed by heating and drying at 130 ° C. for 20 minutes to form a charge transport layer having a thickness of 20 μm.

(Coating liquid for charge transport layer)
1 part by weight of bisphenol Z-type polycarbonate (viscosity average molecular weight 50,000) 1 part by weight of charge transport material of structural formula (2) 10 parts by weight of tetrahydrofuran

<Formation of photocharged charge layer>
On the charge transport layer thus prepared, a photocharged charge layer coating solution having the following composition was applied by spray coating, dried at room temperature, and then heated and dried at 160 ° C. for 20 minutes to charge the photocharge with a film thickness of 1 μm. A layer was formed to prepare a photoreceptor for charge charging.

(Photocharged charge layer coating solution)
3 parts by weight of titanyl phthalocyanine pigment (XD spectrum is shown in FIG. 12)
Charge transport material of the above structural formula (3) 3 parts by weight Bisphenol Z type polycarbonate 1 part by weight THF 100 parts by weight Cyclohexanone 40 parts by weight

<Evaluation>
The charge generation layer application solution and the photocharge charge layer coating solution prepared as described above were each applied and dried on a quartz glass substrate under the same conditions as the photoconductor, and the respective absorption spectra were then commercially available. The absorption spectrum was measured with a meter (Hitachi: UV-3100). As a result, the absorption spectra of the charge generation layer and the photocharge charge layer almost coincided with the absorption spectrum of CGMC shown in FIG. 11, and the maximum absorption peak wavelength was 800 nm. Further, the transmittance at 780 nm of the photocharged charge layer was 10%.

The photocharging and charging characteristics of the photoreceptor thus prepared were measured as follows using a charging characteristics measuring apparatus shown in FIG.
Immediately after irradiating a photoconductor rotating at a speed of 200 mm / s with LED light (1 μJ / cm ² ) in a wavelength region of 740 nm, a silicon rubber roller having a diameter of 16 mm and an electric resistance of 10 ⁴ Ω · cm is brought into contact with the photoconductor. The charging potential when a voltage of -400 V was applied was measured. The charging potential (V _OFF ) when not exposed was −150 V, and the charging potential (V _ON ) when the LED was turned on was −280 V. When the 780 ± 10 nm LED light was exposed to 0.5 μJ / cm ^{2 on} the photosensitive member charged by turning on the LD, the charged potential was attenuated and the potential (VL) of the exposed portion became −20V.

Next, using this photoreceptor, an image was formed by an image forming apparatus using the process cartridge shown in FIG. The image forming method will be described below.
As a charging member, a conductive voltage application roller 3 in which a conductive urethane elastic layer having a volume resistivity of about 10 ⁴ Ω · cm is provided on a stainless steel shaft having a diameter of 8 mm is used. A voltage was applied. The initial charging potential of the photoreceptor was -380V. An LED having a wavelength region of 740 nm was used as the charging exposure light. An exposure device (not shown) is a device for writing a latent image on a charged photoreceptor in accordance with image information, and is an optical scanning device using a laser beam having an oscillation wavelength of 780 nm and a polygon mirror mirror, and a dot image of 600 dpi. Was exposed. The potential of the exposed portion at the time of exposing the entire surface of the photoreceptor was -30V. As developing means, reversal development was performed using a two-component developer composed of a negatively charged toner and a magnetic carrier. In the transfer, a positive voltage was applied to a conductive charging roller and transferred onto paper. For cleaning, fur brush cleaning was used. When an image was formed under the above conditions, a clear image with no image blur, a uniform halftone portion, and no roughness was obtained.

  Next, the following forced fatigue test was conducted in order to investigate the deterioration of the photoreceptor when the charging method of the present invention was repeated. After 10000-times repeated tests of 740 nm LED light irradiation, -500 V voltage application, and 780 nm laser overall exposure to the photoreceptor, under a temperature and humidity environment of 25 ° C., 50% RH, 30 ° C., 85% RH Then, when an image was created by the same method as the initial image formation, a clear dot image similar to the initial one with no image blur and image flow was obtained.

  The titanyl phthalocyanine used in the photocharged charge layer of Example 11 was changed to titanyl phthalocyanine (a titanyl phthalocyanine having a peak at a minimum angle of 7.5 degrees and a maximum peak at 27.2 degrees) having an XD spectrum in FIG. A photoconductor was prepared and evaluated in the same manner as in Example 11 except for the change.

  The photocharged charge layer coating solution prepared as described above was applied and dried on a quartz glass substrate under the same conditions as the photoreceptor, and the absorption spectrum was measured with a commercially available spectrophotometer (Hitachi: UV-3100). Absorption spectrum was measured. As a result, the absorption spectrum of the photocharged charge layer almost coincided with the absorption spectrum of CGM C shown in FIG. 11, and the maximum absorption peak wavelength was 793 nm. Further, the transmittance at 780 nm of the photocharged charge layer was 10%.

As in the case of Example 11, the charging potential when a voltage of −400 V was applied was measured. The charging potential (V _OFF ) when not exposed was −160 V, and the charging potential (V _ON ) when the LED was turned on was −240 V. Further, when 780 ± 10 nm light was exposed to 0.5 μJ / cm ^{2 on} the photosensitive member charged by turning on the LED, the charged potential was attenuated and the potential (VL) of the exposed portion became −10V.

  Further, when an image was formed by the image forming apparatus using the process cartridge shown in FIG. 7, the initial charging potential of the photosensitive member was −340V with an applied voltage of −500V. When image formation was performed in the same manner as in Example 11, a clear image with no image blur and a uniform halftone portion and no rough feeling was obtained. The image contrast is slightly inferior to the image of Example 11.

  A photoconductor was prepared and evaluated in the same manner as in Example 11 except that the titanyl phthalocyanine used in Example 11 was changed to titanyl phthalocyanine having an XD spectrum in FIG. 14 (titanyl phthalocyanine having a maximum peak at 26.3 degrees). Went.

  The photocharged charge layer coating solution prepared as described above was applied and dried on a quartz glass substrate under the same conditions as the photoreceptor, and the absorption spectrum was measured with a commercially available spectrophotometer (Hitachi: UV-3100). Absorption spectrum was measured. As a result, the absorption spectrum of the photocharged charge layer almost coincided with the absorption spectrum of CGM C shown in FIG. 11, and the maximum absorption peak wavelength was 785 nm. Further, the transmittance at 780 nm of the photocharged charge layer was 10%.

As in the case of Example 11, the charging potential when a voltage of −400 V was applied was measured. The charging potential (V _OFF ) when not exposed was −150 V, and the charging potential (V _ON ) when the LED was turned on was −180 V. Further, when 780 ± 10 nm light was exposed to 0.5 μJ / cm ^{2 on} the photosensitive member charged by turning on the LED, the charged potential was attenuated and the potential (VL) of the exposed portion became −10V.

  Further, when an image was formed by the image forming apparatus using the process cartridge shown in FIG. 7, the initial charging potential of the photosensitive member was −230 V with an applied voltage of −500 V. When image formation was performed in the same manner as in Example 1, there was no image blur and an image having a slightly lower image density than that of the image of Example 11 was obtained.

  In Example 11, the photocharged charge layer coating solution was changed to the following to produce a photoconductor and evaluated in the same manner.

(Photocharged charge layer coating solution)
3 parts by weight of a trisazo pigment of the following structural formula (8) 3 parts by weight of a charge transport material of the structural formula (3) 1 part by weight of THF 100 parts by weight of cyclohexanone 40 parts by weight of bisphenol Z type polycarbonate (viscosity average molecular weight 50,000)

  The photocharged charge layer coating solution prepared as described above was applied and dried on a quartz glass substrate under the same conditions as the photoreceptor, and the absorption spectrum was measured with a commercially available spectrophotometer (Hitachi: UV-3100). Absorption spectrum was measured. As a result, the absorption spectrum of the photocharged charge layer almost coincided with the absorption spectrum of CGM B shown in FIG. 11, and the maximum absorption peak wavelength was 780 nm. Further, the transmittance at 780 nm of the photocharged charge layer was 10%.

As in the case of Example 11, the charging potential when a voltage of −400 V was applied was measured. The charging potential (V _OFF ) when not exposed was −120 V, and the charging potential (V _ON ) when the LED was turned on was −140 V. Further, when 780 ± 10 nm light was exposed to 0.5 μJ / cm ^{2 on} the photosensitive member charged by turning on the LED, the charged potential was attenuated and the potential (VL) of the exposed portion became −10V.

  Further, when an image was formed by the image forming apparatus using the process cartridge shown in FIG. 7, the initial charging potential of the photosensitive member was −200 V with an applied voltage of −500 V. When image formation was performed in the same manner as in Example 1, there was no image blur and an image having a slightly lower image density than that of the image of Example 11 was obtained.

In Example 11, the exposure for charging was changed to a xenon lamp, and an exposure light source of 370 ± 15 nm was used using a 350 nm short wavelength cut filter and a 400 nm long wavelength cut filter.
As in the case of Example 11, the charging potential when a voltage of −400 V was applied was measured. The charging potential (V _OFF ) when not exposed was −140 V, and the charging potential (V _ON ) when the LED was turned on was −270 V. Further, when 780 ± 10 nm light was exposed to 0.5 μJ / cm ^{2 on} the photosensitive member charged by turning on the LED, the charged potential was attenuated and the potential (VL) of the exposed portion became −10V.

  When the forced fatigue test was carried out in the same manner as in Example 11, it was observed that the color of the surface of the photoreceptor was slightly changed and the surface was deteriorated. Along with this, a slight image blur was observed after the forced deterioration test.

The same undercoat layer, charge generation layer, and charge transport layer as in Example 1 were produced on an aluminum cylindrical tube having an outer diameter of 100 mmΦ. Next, a photocharged charge layer having a dry film thickness of 1 μm was formed in the same manner as in Example 1 except that the following composition liquid was used on the charge transport layer to prepare a photoreceptor.
(Photocharged charge layer coating solution)
3 parts by weight of a bisazo pigment of the structural formula (2) 3 parts by weight of a polymeric charge transport material of the following structural formula (9) (n was determined to be about 240 as a result of measurement by GPC)
THF 100 parts by weight Cyclohexanone 40 parts by weight

When this photoreceptor was used to form an image under the same conditions using the same image forming apparatus as in Example 1, a clear image was obtained with no image blur.
Further, when 10,000 continuous images were formed in the same manner as in Example 10, no scratches or the like were observed on the surface of the photoreceptor, and no defects were observed in the image after 10,000 images.

Example 18 is the same as Example 18 except that the polymer charge transport material of the following structural formula (10) (n was determined to be about 230 as a result of measurement by GPC) was used instead of the polymer charge transport material of Example 16. Similarly, a photoreceptor was produced.
When this photoreceptor was used to form an image under the same conditions using the same image forming apparatus as in Example 1, a clear image was obtained with no image blur.
Further, when 10,000 continuous images were formed in the same manner as in Example 10, no scratches or the like were observed on the surface of the photoreceptor, and no defects were observed in the image after 10,000 images.

A photoconductor was prepared and evaluated in the same manner as in Example 19 except that the photocharge charging layer of Example 17 was formed as follows.
The photocharged charge layer was formed as a cured film having a dry film thickness of about 1 μm by applying a photocharge charge layer coating solution having the following composition onto the surface of the charge transport layer by spraying and heating and drying at 150 ° C. for 30 minutes. .
(Photocharged charge layer coating solution)
Bisazo pigment of structural formula (2) 1.5 parts by weight Methyl methacrylate-styrene-n-butyl methacrylate copolymer resin
(Average molecular weight: 15000, composition ratio: 20/30/30 (weight ratio)) 0.06 part by weight 1,4-butanediol dimethacrylate 0.5 part by weight Charge transporting compound of the following structural formula (11) 1 part by weight Parts benzoyl peroxide 0.01 parts by weight THF 50 parts by weight cyclohexanone 15 parts by weight

When this photoreceptor was used to form an image under the same conditions using the same image forming apparatus as in Example 1, a clear image was obtained with no image blur.
Further, when 10,000 continuous images were formed in the same manner as in Example 10, no scratches or the like were observed on the surface of the photoreceptor, and no defects were observed in the image after 10,000 images.

  Since the electrophotographic photosensitive member of the present invention does not generate abnormal images even after repeated use and has high durability and high reliability, it can be used as an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile machine. Is expensive.

FIG. 5 is a diagram showing the difference between injection charging and discharge charging from the relationship between the voltage applied to the charging member and the photosensitive member charging potential. FIG. 2 is a view showing a basic structure of an electrophotographic photosensitive member of the present invention. It is a figure which shows the principle of charging and latent image formation in the electrophotographic photosensitive member of the present invention. It is an example of the electrophotographic photosensitive member of the present invention using a laminated photosensitive layer. 1 is a diagram illustrating an example of a configuration of an image forming apparatus of the present invention. 1 is a diagram illustrating an example of an image forming apparatus of the present invention when an endless belt-like photoconductor is used. It is a figure which shows the example of the process cartridge of this invention. It is a figure which shows the measuring apparatus for measuring the charging characteristic of a photoconductor. FIG. 3 is a diagram illustrating charging characteristics of the photoconductor of Example 1. It is the figure which contrasted the absorption spectrum of three types of electrification substances. It is the figure which showed the relationship between the light source wavelength for image exposure, and the absorption spectrum of a charge generation material. 6 is a diagram showing an XD spectrum of titanyl phthalocyanine used in Example 6. FIG. 6 is a diagram showing an XD spectrum of titanyl phthalocyanine used in Example 12. FIG. 14 is a diagram showing an XD spectrum of titanyl phthalocyanine used in Example 13. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging exposure means 3 Voltage application means, voltage application roller 4 Image exposure means 5 Development means 6 Transfer means 7 Cleaning means 8 Static elimination means, static elimination roller 9 Transfer paper 11 Conductive support 12 Photosensitive layer 12a Charge generation layer 12b Charge transport layer 13 Photo charge charge layer 14 Cleaning blade 15 Toner transport coil 16 Developer set case 17 Doctor blade 18 Transport screw 19 Development sleeve 20 LED light source 21 Static elimination roller 22 Surface potential meter 23 Light source for image exposure

Claims (26)

  Step of performing exposure for charging on the photoconductor, simultaneously with or after exposure for charging, a voltage is applied to the photoconductor through a conductive voltage application member in contact with the photoconductor, and the voltage application member An electrophotographic photosensitive member for use in an image forming method having a step of charging the surface of the photosensitive member with the same polarity as an applied voltage, wherein the electrophotographic photosensitive member is at least sensitive to image exposure on a translucent conductive support. And a photocharged charge layer containing at least a charge generating substance that generates a charge upon charging exposure, and the photocharged charge layer is on the surface of the photoreceptor. body.   The electrophotographic photosensitive member according to claim 1, wherein the charge generating material contained in the photocharged charge layer is an organic pigment.   The electrophotographic photosensitive member according to claim 2, wherein the organic pigment is an azo pigment. 4. The electrophotographic photosensitive member according to claim 3, wherein the azo pigment is an azo pigment represented by the following general formula (I).

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 (II):

In the formula, R ₂₀₃ represents a hydrogen atom, an alkyl group, or an aryl group. R ₂₀₄ , R ₂₀₅ , R ₂₀₆ , R ₂₀₇ and R ₂₀₈ each represent a hydrogen atom, a nitro group, a cyano group, a halogen atom, a trifluoromethyl group, an alkyl group, an alkoxy group, a dialkylamino group or a hydroxyl group, and Z is A group of atoms necessary for constituting a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring. The electrophotographic photosensitive member according to claim 4, wherein Cp ₁ and Cp ₂ of the azo pigment are different from each other.   The electrophotographic photosensitive member according to claim 2, wherein the organic pigment is titanyl phthalocyanine.   The titanyl phthalocyanine is a titanyl phthalocyanine having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 mm) of CuKα. The electrophotographic photosensitive member according to claim 6.   The titanyl phthalocyanine has a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to CuKα characteristic X-rays (wavelength 1.542 mm), and is further dominant at 9.4 °, 9.6 °, and 24.0 °. Has a peak at 7.3 ° as the lowest angle diffraction peak, and has no peak between the 7.3 ° peak and the 9.4 ° peak, and The electrophotographic photosensitive member according to claim 7, wherein the electrophotographic photosensitive member has no peak at 26.3 °.   The electrophotographic photosensitive member according to claim 1, wherein the photocharged charge layer contains a charge transport material.   The electrophotographic photosensitive member according to claim 9, wherein the charge transport material is a hole transport material.   The electrophotographic photosensitive member according to claim 10, wherein the hole transport material is a compound having at least a triarylamine structure. The electrophotographic photosensitive member according to claim 9, wherein the charge transporting substance is a polymer charge transporting substance. The electrophotographic photosensitive member according to claim 12, wherein the polymer charge transporting material is a hole transporting material. The electrophotographic photosensitive member according to claim 12, wherein the polymer charge transporting material has a crosslinked structure. The difference between the maximum absorption wavelength of the organic pigment used in the photocharge charging layer and the maximum absorption wavelength of the organic pigment used in the photosensitive layer is in the range of ± 10 nm. The electrophotographic photoreceptor described in 1. The electrophotographic photosensitive member according to claim 15, wherein the organic pigment used in the photocharge charging layer and the organic pigment used in the photosensitive layer are the same. The organic pigment used in the photocharge charging layer is different from the organic pigment used in the photosensitive layer, the maximum absorption wavelength of the organic pigment used in the photocharge charging layer and the maximum of the organic pigment used in the photosensitive layer The absorption wavelength is separated by 200 nm or more.
The electrophotographic photosensitive member according to any one of the above. The electrophotographic photosensitive member according to claim 1, wherein a filler is contained in the photocharged charge layer. The photosensitive layer comprises at least a charge generation layer and a charge transport layer.
The electrophotographic photosensitive member according to any one of 18. The electrophotographic photosensitive member according to claim 1, wherein the conductive support has an endless belt shape. At least a voltage is applied to the photosensitive member through a conductive voltage applying member that is in contact with the photosensitive member and a means for performing exposure for charging the photosensitive member at the same time as or after the exposure for charging. A voltage applying means for charging the surface of the photoreceptor with the same polarity as the applied voltage from the voltage application member, and after charging, image exposure is performed from the inner surface of the photoreceptor to form an electrostatic charge latent image on the photoreceptor. An image forming apparatus comprising: an image exposure unit that performs development, a development unit that develops the electrostatic latent image with toner, and a unit that transfers the developed image to a transfer body. An image forming apparatus comprising the electrophotographic photosensitive member according to any one of the above. 3. A light source having a length of 400 nm or longer is used as the charging exposure means.
The image forming apparatus according to 1. The image forming apparatus according to claim 22, wherein the photocharged charge layer absorbs 80% or more of light used for the charging exposure means. The image forming apparatus according to any one of claims 21 to 23, wherein the wavelength of light used for the charging exposure means is light in a region where the charge generating material used for the photosensitive layer is not absorbed. 25. The image formation according to claim 21, wherein the photocharge charging layer of the photoconductor has a positive charge transport function, and a negative voltage is applied to the voltage application unit. apparatus. A process cartridge in which a photosensitive member is integrated with at least one selected from an exposing unit for charging, a voltage applying unit, a developing unit, a cleaning unit, a neutralizing unit and a transfer unit, and is detachably provided. 21. A process cartridge which is the photosensitive member according to claim 1.

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