JP2018010236A - Electrophotographic photoreceptor, image forming apparatus including the same, and coating liquid for forming charge transport material-containing layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a coating liquid including a charge transport material in which a deterioration in coating liquid is suppressed and to provide an electrophotographic photoreceptor that can increase wear resistance, suppress a reduction in photoresponsivity, suppress an increase in residual potential, prevent deterioration due to ozone and/or nitrogen oxide and extend its life, and maintain the quality of an image during printing.SOLUTION: An electrophotographic photoreceptor contains an enamine compound represented by the following general formula as a charge transport material; a layer containing the charge transport material contains free chlorine within a concentration range of 10 to 4000 ppm; the electrophotographic photoreceptor contains at least one or more types of antioxidant.SELECTED DRAWING: None

Description

  The present invention relates to an electrophotographic photosensitive member, an image forming apparatus including the same, and a coating liquid for forming a charge transport material-containing layer.

  An electrophotographic image forming apparatus (hereinafter also referred to as an electrophotographic apparatus) used as a copying machine, a printer, a facsimile machine, or the like forms an image through the following electrophotographic process.

First, a photosensitive layer of an electrophotographic photoreceptor (hereinafter also simply referred to as a photoreceptor) provided in the apparatus is uniformly charged to a predetermined potential by a charger.
Next, exposure is performed by light such as laser light emitted from the exposure unit in accordance with image information to form an electrostatic latent image.

The developer is supplied from the developing means to the formed electrostatic latent image, and the electrostatic latent image is developed by attaching colored fine particles called toner, which is a component of the developer, to the surface of the photoreceptor. It is visualized as a toner image.
The formed toner image is transferred from the surface of the photoreceptor to a transfer material such as recording paper by a transfer unit, and fixed by a fixing unit.

However, not all the toner on the surface of the photoconductor is transferred to the recording paper and transferred during the transfer operation by the transfer means, but a part of the toner remains on the surface of the photoconductor. Further, the paper dust of the recording paper that comes into contact with the photoconductor during transfer may remain attached to the surface of the photoconductor. Such foreign matters such as residual toner and adhering paper dust on the surface of the photosensitive member adversely affect the quality of the formed image and are removed by the cleaning device.
In recent years, cleaner-less technology has progressed, and there is also a method of removing the foreign matter by a so-called developing and cleaning system that collects residual toner by a cleaning function added to the developing unit without having an independent cleaning unit.
In this method, after the surface of the photosensitive member is cleaned, the surface of the photosensitive layer is neutralized by a static eliminator or the like so that the electrostatic latent image disappears.

An electrophotographic photoreceptor used in such an electrophotographic process is configured by laminating a photosensitive layer containing a photoconductive material on a conductive substrate made of a conductive material.
Examples of electrophotographic photoreceptors include inorganic photoconductive materials and organic photoconductive materials (hereinafter referred to as organic photoconductors; abbreviated as OPC). Since the sensitivity and durability of the body have been improved, organic photoreceptors are often used at present.

  In recent years, the electrophotographic photosensitive member has been mainly composed of a multilayer type photosensitive member in which a photosensitive layer is functionally separated into a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. ing. In many cases, a charge transport layer in which a charge transport material having charge transport ability is dispersed in a molecular form in a binder resin is laminated on a charge generation layer in which a charge generation material is deposited or dispersed in a binder resin. It is a negatively charged photoreceptor. In addition, a single-layer type photoreceptor in which a charge generation material and a charge transport material are uniformly dispersed and dissolved in the same binder resin has been proposed.

Charge transport materials include
(1) being stable to light and heat;
(2) being stable against ozone, nitrogen oxides (NO _x ), nitric acid, etc. generated by corona discharge when charging the surface of the photoreceptor;
(3) having a high charge transport capability;
(4) High compatibility with organic solvents and binders,
(5) It must be easy and inexpensive to manufacture. However, although the aforementioned charge transport materials meet some of these requirements, they have not yet met all at a high level.

  In recent years, electrophotographic apparatuses such as digital copying machines and printers have been miniaturized and speeded up, and there is a demand for higher sensitivity corresponding to higher speeds as photoconductor characteristics. Ability is required. In a high-speed process, since the time from exposure to development is short, a photoconductor with good photoresponsiveness is required.

  In any of the configurations of the photoreceptors proposed so far, sufficient performance has not yet been obtained. That is, by increasing the content of the charge transport material in the charge transport layer, the speed can be increased to some extent. However, since the binder resin is reduced, the wear resistance is deteriorated and the life of the photoreceptor is shortened. On the contrary, if the amount of the binder resin is increased, the wear resistance is improved, but the photoresponsiveness is lowered. If the photosensitive member is used in such a state, it is repeatedly used in a state where the surface potential is not sufficiently attenuated, and the potential change accompanying the increase in the residual potential increases, resulting in an early deterioration of image quality. Inconveniences such as inviting occur.

  It has also been found that oxidizing gases such as ozone and nitrogen oxides emitted from corona discharge chargers cause significant damage to the photosensitive layer. These oxidizing gases chemically change the material in the photosensitive layer and cause various characteristic changes. For example, a decrease in charging potential, an increase in residual potential, and a decrease in resolving power due to a decrease in surface resistance. As a result, image blurring such as white spots and black bands occurs on the output image, and the image quality is remarkably lowered. It shortens the life of the body. For such a phenomenon, proposals to incorporate measures to efficiently exhaust and replace the gas around the corona charger to avoid direct gas influence on the photoreceptor, and antioxidants and stabilizers in the photosensitive layer Proposals have also been made to add and prevent deterioration.

  For example, JP-A-62-105151 (Patent Document 1) discloses that an antioxidant having a triazine ring and a hindered phenol skeleton in the molecule is added to the photosensitive layer, and JP-A-63-18355 ( Patent Document 2) discloses that a specific hindered amine is added to the photosensitive layer. JP-A 63-4238 (Patent Document 3), JP-A 63-216055 (Patent Document 4) and JP-A-3-172852 (Patent Document 5) disclose trialkylamines, aromatics. Japanese Patent Laid-Open No. 5-158258 (Patent Document 6) discloses that an amine amine is added to a photosensitive layer, but an antioxidant for the photosensitive layer is disclosed in JP-A-5-158258. It has been found that the residual potential rises due to repeated energization fatigue due to the introduction of, and is not sufficient to satisfy both.

JP 62-105151 A JP-A-63-18355 Japanese Unexamined Patent Publication No. 63-4238 Japanese Patent Laid-Open No. 63-216055 JP-A-3-172852 JP-A-5-158258

  Accordingly, the present invention develops a coating liquid containing a charge transport material that suppresses deterioration of the coating liquid, and forms a laminated type photoreceptor or a single layer type photoreceptor containing a charge transport material prepared using the coating liquid. Increases the wear resistance of the photosensitive member, suppresses the decrease in photoresponsiveness, suppresses the increase in residual potential, prevents the deterioration of the photosensitive member by ozone and / or nitrogen oxides, prolongs the life of the photosensitive member, and extends over a long period of time. An object is to maintain image quality during printing in a low-temperature, low-humidity environment or a high-temperature, high-humidity environment.

In selecting a coating liquid binder resin and an antioxidant containing a charge transport material, the present inventors have been subjected to repeated energization fatigue due to the difference in the binder resin used, even if the binder resin has the same structure. On the other hand, it was found that the increase in the residual potential was remarkably improved.
However, it has been found that the adverse effects of the binder resins used may cause decomposition of the charge transport material or application defects due to bubbles in the coating liquid, and the coating liquid deterioration rate increases due to the difference in the binder resin used.

As a result of investigating the causes of coating solution deterioration, it was found that the free chlorine concentration in the photosensitive layer is commonly detected in the photosensitive layer having these specific characteristics.
This free chlorine originates from the fact that the polycarbonate resin used as the binder resin remains in the binder resin due to insufficient purification of the HCl component produced as a by-product when synthesized by the phosgene method. I understood that.

Since the solvent used for the coating liquid containing the charge transport material is THF which dissolves water infinitely, the remaining HCl component is dissociated into hydrogen ions and chlorine ions, and the electric field transport material is formed by the hydrogen ions. It is inferred that it was decomposed and led to deterioration of the coating liquid.
On the other hand, the reason for the chlorine ions in the pair is not clear, but the presence of free chlorine ions (hereinafter also referred to as free chlorine) reduces the resistance of the entire photosensitive layer and promotes the movement of carriers in the photosensitive layer. I guess it was because

  The present inventors have intensively studied to suppress the deterioration of the coating liquid while taking advantage of the specific characteristics as described above, and found that the concentration of free chlorine within a specific range and the antioxidant are charge transport materials. The present inventors have found that the deterioration of the coating liquid can be suppressed by containing it in the coating liquid containing the toner, and the increase in the residual potential due to repeated energization fatigue of the photoreceptor prepared using the coating liquid can be suppressed.

In addition, it has been found that by having a phosphorus-based antioxidant specifically defined in the present invention, a strong suppression effect against white spots due to deterioration of the photosensitive layer by an oxidizing gas such as NO _x is exhibited.
These phosphorus-based antioxidants have been known to have a strong oxidation-resistant gas effect, but as an adverse effect, the increase in residual potential due to repeated electrical fatigue is large, and the combined use with the enamine compound in the present invention is considered to be severe. It was done.
However, by adjusting the free chlorine concentration in the layer containing the charge transport material within a specific range, it is possible to suppress an increase in residual potential and to be used in combination with a phosphorus-based antioxidant, thereby completing the present invention. It came to.

Thus, according to the present invention, at least a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated in this order, or a single layer type containing a charge generation material and a charge transport material. The photosensitive layer is an electrophotographic photosensitive member laminated on a conductive substrate,
In the electrophotographic photoreceptor, the following general formula (1) is used as a charge transport material:

(1)
(Where
a represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, alkoxy group, dialkylamino group or aryl group;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a's may be the same or different from each other. When a is an alkyl group, adjacent a's are bonded to each other to form a ring structure. May form;

Ar ¹ and Ar ² each represent an aryl group which may have a substituent or a heterocyclic group which may have a substituent;
Ar ³ represents an aryl group that may have a substituent, a heterocyclic group that may have a substituent, an aralkyl group that may have a substituent, or an alkyl group that may have a substituent. ;
Ar ⁴ and Ar ⁵ are the same as or different from each other, and each represents a hydrogen atom or an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group, provided that Ar ⁴ and Ar ⁵ are Cannot simultaneously be hydrogen atoms, and Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or atomic group to form a ring structure;

R ¹ represents a hydrogen atom, a halogen atom or an alkyl group which may have a substituent;
R ² , R ³ and R ⁴ are each a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, a heterocyclic group which may have a substituent or a substituent. An aralkyl group which may have
n represents an integer of 0 to 3, and when n is 2 or 3, a plurality of R ² and R ³ may be the same or different, provided that when n is 0, Ar ³ has a substituent. A heterocyclic group which may be
An electron containing the enamine compound represented by the above, wherein the layer containing the charge transport material contains free chlorine at a concentration in the range of 10 to 4000 ppm and contains at least one antioxidant. A photographic photoreceptor is provided.

Further, according to the present invention, the Ar ¹ in the general formula (1) is substituted with b _i is also a phenyl group, Ar ² is a phenyl group optionally substituted by c _k, Ar ³ is a phenyl group which may be substituted with d _j , R ¹ , R ² , R ³ and R ⁴ are hydrogen, and the enamine compound represented by the general formula (1) is represented by the following general formula ( 2):

(2)
(Where
a represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, alkoxy group, dialkylamino group or aryl group;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a's may be the same or different from each other. When a is an alkyl group, adjacent a's are bonded to each other to form a ring structure. May form;

b, c and d are the same or different from each other and each represents a hydrogen atom, a halogen atom, or an alkyl group, alkoxy group, dialkylamino group, aryl group, aryloxy group or arylthio group which may have a substituent. ;
i, k and j are the same or different from each other, and are integers of 1 to 5, and when i, j or k is 2 or more, each of a plurality of b, c or d may be the same or different from each other. Or each of b, c or d bonded to adjacent carbon atoms of the benzene ring may be bonded together to form a ring structure;

Ar ⁴ and Ar ⁵ are the same as or different from each other, and each represents a hydrogen atom or an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group, provided that Ar ⁴ and Ar ⁵ are At the same time, it cannot be a hydrogen atom, and Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or an atomic group to form a ring structure)
The electrophotographic photosensitive member represented by the formula is provided.

According to the invention, in the general formula (2), the following partial structure:
But the following substituents:

Means the following substructure:

Are the same or different from each other and have the following substituents:

Means the following substructure:

But the following substituents:

Wherein Ar ⁴ or Ar ⁵ are the same or different from each other, and the following substituents:

Wherein Ar ⁵ or Ar ⁴ are the same or different from each other, and the following substituents:

Or said Ar ⁴ and Ar ⁵ together are the following substituents:

An electrophotographic photoreceptor as described above is provided.

Moreover, according to the present invention, the antioxidant is
The following general formula (3):

(3)
(Wherein R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are the same as or different from each other, and represent a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group or an aralkyl group; R ²⁰ represents a hydrogen atom or a monovalent group) W represents an organic residue; W represents an atomic group necessary to form a ring structure containing an amino nitrogen atom, provided that R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are not hydrogen atoms with each other. )
A hindered amine antioxidant represented by:
The following general formula (4):

(In the formula, R ²¹ , R ²² and R ²³ are the same or different from each other, and are a hydroxy group, an alkoxy group, an alkylsulfanyl group, an optionally substituted phenyl group or phenoxy group, or R ²¹ , R ^22. And any two of R ²³ are bonded to each other to form a ring structure containing one phosphorus atom, or any one of R ²¹ , R ²² and R ^{23 in} the two compounds of the general formula (4) Can be bonded to each other to form a ring structure containing two phosphorus atoms, provided that R ²¹ , R ²² and R ²³ are not mutually hydroxy groups)
A phosphorus-based antioxidant represented by the following general formula (5):

(Wherein R ²⁵ and R ²⁶ are the same or different from each other, and may be an alkyl group or a phenyl group which may have a substituent, or the following partial structure:

Or (wherein R ²⁸ is a hydrogen atom, an optionally substituted alkyl group, or a 4-hydroxy 3,5-di-t-butylphenethyl group)
Have)
The electrophotographic photosensitive member is selected from the sulfide-based antioxidants represented by the formula:

  According to the present invention, the layer containing the charge transport material contains 0.1 to 25% by weight of an antioxidant with respect to the total amount of the layer components containing the charge transport material. A photoreceptor is provided.

  Further, according to the present invention, the layer containing the charge transport material contains 0.1 to 20% by weight of an antioxidant with respect to the total amount of the layer components containing the charge transport material. A photoreceptor is provided.

Furthermore, according to the present invention, the electrophotographic photoreceptor described above,
Charging means for charging the electrophotographic photoreceptor;
Exposure means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image; and
Developing means for developing the electrostatic latent image with toner to form a toner image;
Transfer means for transferring the toner image onto a recording material;
An image forming apparatus is provided that includes a fixing unit that fixes the transferred toner image on the recording material.

Moreover, according to the present invention, there is provided a charge transport material-containing layer forming coating solution that contains at least a charge transport material and may optionally contain a charge generation material,
The following general formula (1) as a charge transport material:

(1)
(Where
a represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, alkoxy group, dialkylamino group or aryl group;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a's may be the same or different from each other. When a is an alkyl group, adjacent a's are bonded to each other to form a ring structure. May form;

Ar ¹ and Ar ² each represent an aryl group which may have a substituent or a heterocyclic group which may have a substituent;
Ar ³ represents an aryl group that may have a substituent, a heterocyclic group that may have a substituent, an aralkyl group that may have a substituent, or an alkyl group that may have a substituent. ;
Ar ⁴ and Ar ⁵ are the same as or different from each other, and each represents a hydrogen atom or an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group, provided that Ar ⁴ and Ar ⁵ are Cannot simultaneously be hydrogen atoms, and Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or atomic group to form a ring structure;

R ¹ represents a hydrogen atom, a halogen atom or an alkyl group which may have a substituent;
R ² , R ³ and R ⁴ are each a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, a heterocyclic group which may have a substituent or a substituent. An aralkyl group which may have
n represents an integer of 0 to 3, and when n is 2 or 3, a plurality of R ² and R ³ may be the same or different, provided that when n is 0, Ar ³ has a substituent. A heterocyclic group which may be
A charge containing the enamine compound represented by the above, wherein the layer containing the charge transport material contains free chlorine at a concentration in the range of 10 to 4000 ppm and contains at least one antioxidant. A coating liquid for forming a transport material-containing layer is provided.

Further, according to the present invention, the Ar ¹ in the general formula (1) is substituted with b _i is also a phenyl group, Ar ² is a phenyl group optionally substituted by c _k, Ar ³ is a phenyl group which may be substituted with d _j , R ¹ , R ² , R ³ and R ⁴ are hydrogen, and the enamine compound represented by the general formula (1) is represented by the following general formula ( 2):

(2)
(Where
a represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, alkoxy group, dialkylamino group or aryl group;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a's may be the same or different from each other. When a is an alkyl group, adjacent a's are bonded to each other to form a ring structure. May form;

b, c and d are the same or different from each other and each represents a hydrogen atom, a halogen atom, or an alkyl group, alkoxy group, dialkylamino group, aryl group, aryloxy group or arylthio group which may have a substituent. ;
i, k and j are the same or different from each other, and are integers of 1 to 5, and when i, j or k is 2 or more, each of a plurality of b, c or d may be the same or different from each other. Or each of b, c or d bonded to adjacent carbon atoms of the benzene ring may be bonded together to form a ring structure;

Ar ⁴ and Ar ⁵ are the same as or different from each other, and each represents a hydrogen atom or an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group, provided that Ar ⁴ and Ar ⁵ are At the same time, it cannot be a hydrogen atom, and Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or an atomic group to form a ring structure)
The charge transport material-containing layer forming coating solution represented by

According to the invention, in the general formula (2), the following partial structure:
But the following substituents:
Means the following substructure:

Are the same or different from each other and have the following substituents:

Means the following substructure:

But the following substituents:

Wherein Ar ⁴ or Ar ⁵ is the following substituent:

Wherein Ar ⁵ or Ar ⁴ is the following substituent:

Or said Ar ⁴ and Ar ⁵ together are the following substituents:

The above-mentioned coating liquid for forming a charge transport material-containing layer is provided.

According to the present invention, the antioxidant is
The following general formula (3):

(3)
(Wherein R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are the same as or different from each other, and represent a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group or an aralkyl group; R ²⁰ represents a hydrogen atom or a monovalent group) W represents an organic residue; W represents an atomic group necessary to form a ring structure containing an amino nitrogen atom, provided that R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are not hydrogen atoms with each other. )
A hindered amine antioxidant represented by:
The following general formula (4):

(In the formula, R ²¹ , R ²² and R ²³ are the same or different from each other, and are a hydroxy group, an alkoxy group, an alkylsulfanyl group, an optionally substituted phenyl group or phenoxy group, or R ²¹ , R ^22. And any two of R ²³ are bonded to each other to form a ring structure containing one phosphorus atom, or any one of R ²¹ , R ²² and R ^{23 in} the two compounds of the general formula (4) Can be bonded to each other to form a ring structure containing two phosphorus atoms, provided that R ²¹ , R ²² and R ²³ are not mutually hydroxy groups)
A phosphorus-based antioxidant represented by the following general formula (5):
(Wherein R ²⁵ and R ²⁶ are the same or different from each other, and may be an alkyl group or a phenyl group which may have a substituent, or the following partial structure:

Or (wherein R ²⁸ is a hydrogen atom, an optionally substituted alkyl group, or a 4-hydroxy 3,5-di-t-butylphenethyl group)
Have)
The charge transport material-containing layer forming coating solution selected from the sulfide-based antioxidants represented by the formula:

  Further, according to the present invention, the charge transport layer forming coating solution contains 0.1 to 25% by weight of an antioxidant with respect to the total amount of the layer component containing the charge transport material. A substance-containing layer forming coating solution is provided.

  Further, according to the present invention, the charge transport layer forming coating solution contains 0.1 to 20% by weight of an antioxidant with respect to the total amount of the layer components including the charge transport material. A substance-containing layer forming coating solution is provided.

According to the present invention, since the organic photoconductive material represented by the general formula (1) is an enamine compound represented by the general formula (2), an organic photoconductive material having a particularly high charge mobility is used. It can be easily obtained at low cost.
As described above, by using the organic photoconductive material of the present invention having a particularly high charge mobility as a charge transport material, the charged potential is high, the sensitivity is high, and sufficient photoresponsiveness is exhibited. It is possible to provide an electrophotographic photosensitive member whose characteristics do not deteriorate even when used in a process.

Furthermore, by controlling the free chlorine concentration in the photoreceptor coating liquid while containing an antioxidant, the stability of the oxidizing gas such as ozone in the photosensitive layer is improved and the electrophotographic photoreceptor characteristics are degraded. A highly reliable electrophotographic photosensitive member can be realized.
As the antioxidant, a compound having a hindered amine structural unit or a phosphorus antioxidant in the molecule is most effective.

According to the invention, preference antioxidants of the present invention described above is, ozone generated during charging by corona discharge, or an active gas such as NO _x, exposure, and free radicals generated by ultraviolet light and heat contained in the lamp light Reaction to prevent degradation of the enamine compound of the present invention, thus improving the potential characteristics, increasing the stability as a coating solution, and reducing fatigue deterioration when the photoreceptor is used repeatedly. And durability can be improved.

The present invention is also an image forming apparatus comprising the electrophotographic photosensitive member.
According to the present invention, as described above, it is possible to suppress the decomposition of the charge transfer agent due to external stimuli such as light and heat during the production of the photoreceptor, and there is no increase in residual potential due to repeated energization fatigue. Since a highly reliable electrophotographic photosensitive member is provided, it is possible to obtain a highly reliable image forming apparatus capable of providing high quality images under various environments.

Further, it has been found that the stability of the coating liquid is remarkably increased by using the hindered amine antioxidant defined in the present invention among the antioxidants.
On the other hand, a polycarbonate binder resin generally used for forming a layer containing a charge transport material is a large component contained in more than half of the coating liquid containing the charge transport material. Conventionally, a material having extremely high purity as a binder resin has been demanded, so that cost reduction is severe.

However, according to the present invention, in the case of an underpurified polycarbonate binder resin, the resistance of the photosensitive layer as a whole is lowered by the presence of HCl and / or free chlorine (hereinafter also referred to as free chlorine ions) derived from the production process, Since the movement of the carrier in the photosensitive layer can be promoted, the cost of the polycarbonate binder resin can be reduced.
Furthermore, according to the present invention, HCl is added for the purpose of adjusting the free chlorine concentration as necessary, by adding a free chlorine concentration and an antioxidant within a specific range to the coating liquid containing the charge transport material. By adding to the coating liquid, deterioration of the coating liquid can be suppressed, and an increase in residual potential due to repeated energization fatigue of a photoreceptor prepared using the coating liquid can be suppressed.

1 is a schematic cross-sectional view illustrating a configuration of a multilayer electrophotographic photosensitive member having no intermediate layer, which is an example of an electrophotographic photosensitive member according to the present invention. 1 is a schematic cross-sectional view showing a configuration of a multilayer electrophotographic photoreceptor having an intermediate layer which is an example of an electrophotographic photoreceptor according to the present invention. 1 is a schematic cross-sectional view illustrating a configuration of a single layer type electrophotographic photosensitive member having an intermediate layer which is an example of an electrophotographic photosensitive member according to the present invention. 1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus including an electrophotographic photoreceptor 10 according to the present invention.

The electrophotographic photoreceptor of the present invention has the following general formula (1):
(1)
(Where
a represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, alkoxy group, dialkylamino group or aryl group;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a's may be the same or different from each other. When a is an alkyl group, adjacent a's are bonded to each other to form a ring structure. May form;

Ar ¹ and Ar ² each represent an aryl group which may have a substituent or a heterocyclic group which may have a substituent;
Ar ³ represents an aryl group that may have a substituent, a heterocyclic group that may have a substituent, an aralkyl group that may have a substituent, or an alkyl group that may have a substituent. ;
Ar ⁴ and Ar ⁵ are the same as or different from each other, and each represents a hydrogen atom or an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group, provided that Ar ⁴ and Ar ⁵ are Cannot simultaneously be hydrogen atoms, and Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or atomic group to form a ring structure;

R ¹ represents a hydrogen atom, a halogen atom or an alkyl group which may have a substituent;
R ² , R ³ and R ⁴ are each a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, a heterocyclic group which may have a substituent or a substituent. An aralkyl group which may have
n represents an integer of 0 to 3, and when n is 2 or 3, a plurality of R ² and R ³ may be the same or different, provided that when n is 0, Ar ³ has a substituent. A heterocyclic group which may be
At least one enamine compound represented by the formula:

The enamine compound of the above general formula (1) has the following general formula (2):
(2)
The enamine compound shown by these is more preferable.

In the enamine compound of the general formula (2),
a represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, alkoxy group, dialkylamino group or aryl group;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a's may be the same or different from each other. When a is an alkyl group, adjacent a's are bonded to each other to form a ring structure. May form;

b, c and d are the same or different from each other and each represents a hydrogen atom, a halogen atom, or an alkyl group, alkoxy group, dialkylamino group, aryl group, aryloxy group or arylthio group which may have a substituent. ;
i, k and j are the same or different from each other, and are integers of 1 to 5, and when i, j or k is 2 or more, each of a plurality of b, c or d may be the same or different from each other. Or each of b, c or d bonded to adjacent carbon atoms of the benzene ring may be bonded together to form a ring structure;

Ar ⁴ and Ar ⁵ are the same as or different from each other, and each represents a hydrogen atom or an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group, provided that Ar ⁴ and Ar ⁵ are At the same time, it cannot be a hydrogen atom, and Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or an atomic group to form a ring structure.

Hereinafter, the above general formula (2)
The substituents in are specifically described.
In the general formula (2), examples of the halogen atom represented by a include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and among these, a fluorine atom is particularly preferable.

Moreover, as an alkyl group which may have a substituent which a represents, a C1-C4 alkyl group or a C1-C4 alkoxy group is mentioned.
Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a methoxyethyl group, a fluoromethyl group, and a trifluoromethyl group. Among these, a methyl group Particularly preferred are isopropyl group and trifluoromethyl group.

Examples of the alkoxy group which may have a substituent represented by a include an alkoxy group having 1 to 4 carbon atoms.
Specific examples include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, and an isobutoxy group, and among these, a methoxy group is particularly preferable.

Examples of the alkyl group of the dialkylamino group which may have a substituent represented by a include an alkyl group having 1 to 4 carbon atoms.
Specific examples include a dimethylamino group, a diethylamino group, and a diisopropylamino group.

Examples of the aryl group which may have a substituent represented by a include an aryl group which may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group.
Specific examples include phenyl, tolyl, xylyl, methoxyphenyl, methylmethoxyphenyl, 4-chlorophenyl, 4-fluorophenyl, naphthyl, and methoxynaphthyl groups.

Examples of the alkyl group, alkoxy group and dialkylamino group which may have a halogen atom or a substituent represented by b, c and d include those represented by a above. Examples of the aryl group which may have a substituent represented by b, c and d include an aryl group having 6 to 12 carbon atoms which may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group.
Specific examples include phenyl group, tolyl group, xylyl group, methoxyphenyl group, methylmethoxyphenyl group, 4-chlorophenyl group, 4-fluorophenyl group, biphenylyl group, naphthyl group, methoxynaphthyl group, etc. Among these, a phenyl group and a biphenylyl group are particularly preferable.

  Examples of the aryloxy group and arylthio group which may have a substituent represented by b, c and d include a 4-methylphenoxy group and a phenylthio group, respectively.

Examples of the alkyl group that may have a substituent represented by Ar ⁴ and Ar ⁵ include those represented by a above, and a methyl group is particularly preferable.
The aryl group which may have a substituent represented by Ar ⁴ and Ar ⁵ is, for example, substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group, or a dialkylamino group having 2 to 6 carbon atoms. An aryl group which may be used is mentioned.

  Specific examples of the halogen atom include those represented by a, and examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, an isopropylphenyl group, a methoxyphenyl group, a methylmethoxyphenyl group, t- Examples include butylphenyl group, 4-diethylaminophenyl group, 4-chlorophenyl group, 2-fluorophenyl group, 4-fluoroethylphenyl group, naphthyl group, methoxynaphthyl group and the like. Among these, a phenyl group, a tolyl group, a methoxyphenyl group, and a naphthyl group are particularly preferable.

The aralkyl group which may have a substituent Ar ⁴ and Ar ⁵ mean, and the like benzyl group.
Examples of the heterocyclic group that may have a substituent represented by Ar ⁴ and Ar ⁵ include a chromanyl group, a thienyl group, a 5-methylthienyl group, and a furyl group.
More specifically, in the general formula (2), the partial structure:

Are the following substituents:

Means.

In the general formula (1), the partial structure:
Are the same or different from each other and have the following substituents:

Means.

In the general formula (1), the partial structure:
Are the following substituents:

Means.

In the general formula (1), Ar ⁴ or Ar ⁵ is the following substituent:
Means.

In the general formula (1), Ar ⁵ or Ar ⁴ is the following substituent:
Means.

Alternatively, in the general formula (1), Ar ⁴ and Ar ⁵ are bonded to each other through an atom or an atomic group to form the following ring structure:
Means.

Specific examples of the enamine compound represented by the general formula (2) are shown in the following table, but the organic photoconductive material of the present invention is not limited thereby.

Among these compounds, Exemplified Compounds 1-1, 1-43 and 1-111 are particularly preferable from the viewpoints of electrical characteristics and film strength.
These compounds can be synthesized by the method described in JP-A No. 2004-151666.

  Among the antioxidants, the above-mentioned hindered amine antioxidants are preferably used. By using these antioxidants, fatigue degradation is further reduced when the enamine compound represented by the general formula (1) contained in the photosensitive layer as a charge transport material is used with repeated suppression with particular suppression of degradation and degradation. In addition, the durability of the electrophotographic photosensitive member 1 can be further improved. Further, the stability of the coating solution when forming the photosensitive layer by coating can be further enhanced, and the quality stability and productivity of the electrophotographic photoreceptor can be further improved.

In the present specification, the hindered amine antioxidant is a compound having a hindered amine structural unit and having an antioxidant action.
The hindered amine structural unit is a structural unit derived from an amine compound having a bulky atomic group near the amino nitrogen atom. Examples of the bulky atomic group include a branched alkyl group, an alicyclic hydrocarbon group, an aryl group, and a heterocyclic group. The hindered amine structural unit may be either an aromatic amine type or an aliphatic amine type, but is preferably an aliphatic amine type.
The hindered amine structural unit has the following general formula (3):

(3)
The compound shown by these is preferable.

In the general formula (3), R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ each represent a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group or an aralkyl group. R ²⁰ represents a hydrogen atom or a monovalent organic residue. W represents an atomic group necessary for forming a ring structure containing an amino nitrogen atom. However, R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are not all hydrogen atoms.
In the general formula (3), the alkyl group represented by R ¹⁶ , R ¹⁷ , R ¹⁸ or R ¹⁹ is preferably one having 1 to 18 carbon atoms.

The alkyl group represented by R ¹⁶ , R ¹⁷ , R ¹⁸ or R ¹⁹ may have a substituent. Examples of the substituent include an aryl group, an alkoxy group, a carboxylic acid group, an amide group, a halogen group and a thioether group. And so on.
Specific examples of the aryl group represented by R ¹⁶ , R ¹⁷ , R ¹⁸ or R ¹⁹ include phenyl, naphthyl, anthryl and p-tolyl.
Specific examples of the heterocyclic group represented by R ¹⁶ , R ¹⁷ , R ¹⁸ or R ¹⁹ include thienyl, furyl, benzofuryl and benzothiophenyl.
Specific examples of the aralkyl group represented by R ¹⁶ , R ¹⁷ , R ¹⁸ or R ¹⁹ include benzyl, phenethyl, 1-naphthylmethyl and 1-methylbenzyl.

Examples of the monovalent organic residue represented by R ²⁰ include alkyl groups such as methyl, ethyl, t-pentyl, hexyl and octyl, aryl groups such as phenyl and naphthyl, and aralkyl groups such as benzyl, phenethyl and 1-naphthylmethyl. And heterocyclic groups such as pyridyl, thienyl, furyl, benzofuryl and benzothiophenyl. The alkyl group represented by R ²⁰ preferably has 1 to 18 carbon atoms.

In the general formula (3), the ring structure containing an amino nitrogen atom formed by W is preferably a 5-membered ring or a 6-membered ring. Specific examples thereof include piperidine, piperazine, morpholine, pyrrolidine, imidazo. Examples include lysine, oxazolidine, thiazolidine, selenazolidine, pyrroline, imidazoline, isoindoline, tetrahydroisoquinoline, tetrahydropyridine, dihydropyridine, dihydroisoquinoline, oxazoline, thiazoline, selenazoline and pyrrole. Among these, piperidine, piperazine and pyrrolidine rings are particularly preferable.
In addition, although W has one bond chain in the general formula (3), it is not limited thereto, and W may have two or more bond chains.

  The ring containing an amino nitrogen atom formed thereby may have a substituent, such as an alkyl group such as methyl, ethyl and octyl, an aryl group such as phenyl and naphthyl, a benzyl and phenethyl, etc. Aralkyl groups, heterocyclic groups such as pyridyl, thienyl, furyl, benzofuryl and benzothiophenyl, and amino groups such as methylamino, dimethylamino and diphenylamino. Moreover, an ester group, a hydroxyl group, a silyl group, etc. can also be mentioned.

The hindered amine compound may have two or more hindered amine structural units represented by the general formula (3) or the like. In this case, the plurality of hindered amine structural units may be the same or different.
When a plurality of hindered amine structural units are thus included in the hindered amine compound, the plurality of hindered amine structural units may be directly bonded or may be bonded via an atom or an atomic group.

Specific examples of the atom that bonds a plurality of hindered amine structural units include an oxygen atom, a sulfur atom, and a carbon atom.
Specific examples of the atomic group for linking a plurality of hindered amine structural units include polyvalent groups such as divalent and trivalent groups derived from saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, aromatic hydrocarbons or heterocyclic compounds. The group can be mentioned.

  Specific examples of polyvalent groups derived from saturated aliphatic hydrocarbons include divalent groups such as alkylene groups such as methylene, ethylene and propylene and alkylidene groups such as ethylidene, propylidene and butylidene, and 1-propanyl-3-ylidene. And trivalent groups such as alkanetriyl groups such as 1,3,6-hexanetriyl and the like.

  Specific examples of the polyvalent group generated from the unsaturated aliphatic hydrocarbon include alkenylene groups such as vinylene and propenylene, alkadienylene groups such as 1,3-butadienylene and 1,4-hexadienylene, and 3-pentynylene and 2-hexynylene. Examples thereof include a divalent group such as an alkynylene group and a trivalent group such as an alkenylidene group such as 2-pentenyl-5-ylidene.

Specific examples of polyvalent groups derived from aromatic hydrocarbons include arylene groups such as phenylene, naphthylene, biphenylylene and 2,7-phenanthrylene, trivalent groups such as 1,3,5-benzenetriyl, and 1,4 And tetravalent groups such as 5,8-anthracenetetrayl.
Specific examples of the polyvalent group generated from the heterocyclic compound include divalent groups such as 3,5-pyridinediyl and 2,6-quinolinediyl, and 3 such as 1,3,5-triazine-2,4,6-triyl. Mention may be made of valent groups and tetravalent groups such as 1,4,5,8-acridinetetrayl.

  Further, the hindered amine compound may have the above-mentioned hindered phenol structural unit in addition to the hindered amine structural unit. Specific examples of the hindered amine compound are shown, for example, in Tables 2-1 to 2-3 below. Although an exemplary compound can be mentioned, a hindered amine compound is not limited to these.

  As the antioxidant, those known as phosphorus antioxidants can be used. Specifically, for example, exemplified compounds P-1 to P- shown in the following Tables 3-1 to 3-5 47, but the phosphorus-based antioxidant is not limited to these.

  As other antioxidants, there are sulfide-based antioxidants and the like, and publicly known ones can be used, and specific examples include, for example, exemplified compounds S- shown in Tables 4-1 to 4-2 below. Although 1-S-14 can be mentioned, sulfide type antioxidant is not limited to these.

  The electrophotographic photoreceptor according to the present invention (hereinafter also simply referred to as “photoreceptor”) has at least a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material laminated in this order on a conductive support. The laminated photosensitive layer or the single-layered photosensitive layer containing a charge generating substance and a charge transporting substance is an electrophotographic photosensitive member laminated on a conductive substrate, the general formula (1) described above, In particular, the enamine compound represented by the general formula (2) is used as a charge transport material, and there are various embodiments.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

Embodiment 1
FIG. 1 is a schematic cross-sectional view showing a simplified configuration of an electrophotographic photosensitive member 1 which is an example of an electrophotographic photosensitive member according to the present invention.
The electrophotographic photoreceptor 1 includes a charge generation layer 12 having a charge generation material 13 on a sheet-like conductive support 11 made of a conductive material, a charge transport layer 16 containing a charge transport material 14 and a binder resin. Is a multilayer photoreceptor having the multilayer photosensitive layer 17 laminated in this order.

<Conductive support>
As the conductive material constituting the conductive support 11, for example, a metal material such as aluminum, aluminum alloy, copper, zinc, stainless steel, and titanium can be used. Without being limited to these metal materials, polymer materials such as polyethylene terephthalate, nylon and polystyrene, those obtained by laminating metal foil on the surface of hard paper or glass, those obtained by vapor deposition of metal materials, or conductivity A material obtained by depositing or coating a layer of a conductive compound such as a polymer, tin oxide, or indium oxide can also be used. The shape of the conductive support 11 is a sheet shape in the electrophotographic photosensitive member 1, but is not limited thereto, and may be a cylindrical shape, a columnar shape, an endless belt shape, or the like.

  If necessary, the surface of the conductive support 11 may be anodized film treatment, surface treatment with chemicals or hot water, coloring treatment, or roughening the surface within a range not affecting the image quality. You may perform an irregular reflection process. In an electrophotographic process using a laser as an exposure light source, the wavelength of the laser beam is uniform, so that the incident laser beam and the light reflected in the electrophotographic photosensitive member cause interference, and interference fringes due to this interference appear on the image. May appear and cause image defects. By performing the above-described treatment on the surface of the conductive support 11, image defects due to interference of laser light having the same wavelength can be prevented.

<Charge generation layer>
The charge generation layer 12 contains a charge generation material 13 that generates charges by absorbing light as a main component. Substances effective as the charge generating substance 13 include azo pigments such as monoazo pigments, bisazo pigments and trisazo pigments, indigo pigments such as indigo and thioindigo, perylene pigments such as peryleneimide and perylene anhydride, anthraquinone And polycyclic quinone pigments such as pyrenequinone, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, squarylium dyes, pyrylium salts and thiopyrylium salts, triphenylmethane dyes, and inorganic materials such as selenium and amorphous silicon Can be mentioned. These charge generation materials 13 are used alone or in combination of two or more.

Of these charge generation materials 13, oxotitanium phthalocyanine is preferably used. Since oxotitanium phthalocyanine is a charge generation material 13 having high charge generation efficiency and charge injection efficiency, a large amount of charge is generated by absorbing light, and the generated charge is not accumulated therein. It can be efficiently injected into the charge transport material 14.
As described above, the charge transport material 14 is an enamine compound having a high charge mobility represented by the general formula (1), particularly the general formula (2). Therefore, the charges generated in the charge generation material 13 by light absorption are efficiently injected into the charge transport material 14 and smoothly transported, so that an electrophotographic photosensitive member with high sensitivity and high resolution can be obtained.

  The charge generation material 13 includes triphenylmethane dyes typified by methyl violet, crystal violet, knight blue and victoria blue, erythrosine, rhodamine B, rhodamine 3R, acridine dyes typified by acridine orange and frapeosin, methylene blue and Can be used in combination with sensitizing dyes such as thiazine dyes typified by methylene green, oxazine dyes typified by capri blue and meldra blue, cyanine dyes, styryl dyes, pyrylium salt dyes or thiopyrylium salt dyes Good.

  As a method for forming the charge generation layer 12, the charge generation material 13 is vacuum-deposited on the conductive support 11, or the charge generation layer coating liquid obtained by dispersing the charge generation material 13 in a solvent is made conductive. There is a method of coating on the support 11. Among these, the charge generating material 13 is dispersed by a conventionally known method in a binder resin solution obtained by mixing a binder resin as a binder in a solvent, and the obtained coating solution is dispersed in the conductive support 11. The method of applying on top is preferred. Hereinafter, this method will be described.

  Examples of the binder resin include polyester resin, polystyrene resin, polyurethane resin, phenol resin, alkyd resin, melamine resin, epoxy resin, silicone resin, acrylic resin, methacrylic resin, polycarbonate resin, polyarylate resin, phenoxy resin, polyvinyl butyral resin and One type selected from the group consisting of resins such as polyvinyl formal resins and copolymer resins containing two or more of the repeating units constituting these resins is used alone or in combination of two or more types. The Specific examples of the copolymer resin include insulating resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and acrylonitrile-styrene copolymer resin. be able to. The binder resin is not limited to these, and a commonly used resin can be used as the binder resin.

  Solvents include, for example, halogenated hydrocarbons such as dichloromethane and dichloroethane, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran (THF) and dioxane, 1,2- Alkyl ethers of ethylene glycol such as dimethoxyethane, aromatic hydrocarbons such as benzene, toluene and xylene, or aprotic polar solvents such as N, N-dimethylformamide and N, N-dimethylacetamide are used. Moreover, the mixed solvent which mixed 2 or more types of these solvents can also be used.

  The blending ratio of the charge generation material 13 and the binder resin is preferably such that the ratio of the charge generation material 13 is in the range of 10 wt% to 99 wt%. When the ratio of the charge generation material 13 is less than 10% by weight, the sensitivity is lowered. When the ratio of the charge generation material 13 exceeds 99% by weight, not only the film strength of the charge generation layer 12 is decreased, but also the dispersibility of the charge generation material 13 is decreased to increase coarse particles, which are erased by exposure. Since the surface charge other than the power portion is reduced, image fogging, in particular, the fogging of an image called a black spot where toner adheres to a white background and minute black spots are formed increases. Therefore, it was set to 10% to 99% by weight.

Prior to dispersing the charge generation material 13 in the binder resin solution, the charge generation material 13 may be pulverized by a pulverizer in advance. Examples of the pulverizer used for the pulverization treatment include a ball mill, a sand mill, an attritor, a vibration mill, and an ultrasonic disperser.
Examples of the disperser used when the charge generating material 13 is dispersed in the binder resin solution include a paint shaker, a ball mill, and a sand mill. As a dispersion condition at this time, an appropriate condition is selected so that impurities are not mixed due to wear of a container and a member constituting the disperser.

Examples of the coating method for the coating solution for the charge generation layer obtained by dispersing the charge generation material 13 in the binder resin solution include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method. be able to. Among these application methods, an optimum method can be selected in consideration of the physical properties and productivity of the application.
In particular, the dip coating method is a method in which a layer is formed on the conductive support 11 by immersing the conductive support 11 in a coating tank filled with a coating solution and then pulling it up at a constant speed or a sequentially changing speed. Since it is relatively simple and excellent in terms of productivity and cost, it is widely used in the production of electrophotographic photosensitive members. In addition, in order to stabilize the dispersibility of a coating liquid, the apparatus used for the dip coating method may be provided with a coating liquid dispersing apparatus represented by an ultrasonic generator.

  The film thickness of the charge generation layer 12 is preferably 0.05 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 1 μm or less. If the thickness of the charge generation layer 12 is less than 0.05 μm, the light absorption efficiency is lowered and the sensitivity is lowered. If the film thickness of the charge generation layer 12 exceeds 5 μm, the charge transfer inside the charge generation layer becomes a rate-limiting step in the process of erasing the charge on the surface of the photoreceptor, and the sensitivity decreases. Therefore, the thickness is set to 0.05 μm or more and 5 μm or less.

<Charge transport layer>
In the charge transport layer 16, an enamine compound having a high charge mobility represented by the general formula (1), particularly, the general formula (2) is used as the charge transport material 14 in the present invention.
Therefore, an electrophotographic photosensitive member having a high charging potential, high sensitivity, sufficient photoresponsiveness, excellent durability, and a property that does not deteriorate even when used in a low temperature environment or a high-speed process is obtained. Can do.

  In addition, since a high charge transport capability can be realized without containing polysilane in the photosensitive layer 17, it is possible to obtain a highly reliable electrophotographic photosensitive member whose characteristics are not deteriorated by light exposure.

  Further, as described above, the photosensitive layer 17 has a laminated structure of the charge generation layer 12 containing the charge generation material 13 and the charge transport layer 16 containing the charge transport material 14. In this way, by assigning the charge generation function and the charge transport function to separate layers, it becomes possible to select the most suitable material for each of the charge generation function and the charge transport function. It is possible to obtain an electrophotographic photosensitive member having high durability with increased stability during repeated use.

  The charge transport layer 16 includes, as a charge transport material 14 having a function of accepting and transporting the charge generated by the charge generation material 13 with the enamine compound represented by the general formula (1), particularly the general formula (2), in a binder resin. It is obtained by forming it on the charge generation layer 12 using the charge transport material-containing layer forming coating solution contained in. The organic photoconductive material represented by the general formula (1), particularly the general formula (2), is selected from the compounds described in Table 1-1 to Table 1-14. 1-43 and 1-111 are preferred from the viewpoint of their electrical properties. One or more of these compounds may be used in combination.

  As the binder resin for the charge transport layer 16, a resin having excellent compatibility with the charge transport material 14 is selected. Specific examples include vinyl polymer resins such as polymethylmethacrylate polystyrene resin and polyvinyl chloride resin and copolymer resins thereof, and polycarbonate resin, polyester resin, polyester carbonate resin, polysulfone resin, phenoxy resin, and epoxy resin. And resins such as silicone resin, polyarylate resin, polyamide resin, polyether resin, polyurethane resin, polyacrylamide resin, and phenol resin.

Moreover, you may use the thermosetting resin which bridge | crosslinked these resin partially. These resins may be used alone or in combination of two or more. Among the resins described above, polystyrene resin, polycarbonate resin, polyarylate resin or polyphenylene oxide has a volume resistance value of 10 ¹³ Ω or more and excellent electrical insulation, and also has excellent film properties and potential characteristics. Therefore, it is particularly preferable to use these as binder resins.

The ratio A / B between the charge transport material 14 (A) and the binder resin (B) is generally about 10/12 by weight. However, in the electrophotographic photoreceptor 1 according to the present invention, the ratio A / B is 10 by weight. / 30 to 10/12. As described above, since the charge transport material 14 includes the organic photoconductive material of the present invention having high charge mobility represented by the general formula (1) or (2), the ratio A / B is 10/30 to Even if a binder resin is added at a ratio of 10/12, which is higher than when a conventionally known charge transport material is used, the photoresponsiveness can be maintained.
Therefore, the printing durability of the charge transport layer 16 can be improved and the durability of the electrophotographic photosensitive member can be improved without reducing the photoresponsiveness.

  When the ratio A / B is less than 10/30 and the ratio of the binder resin is high, the viscosity of the coating liquid increases when the charge transport layer 16 is formed by the dip coating method. Sexually worsen. Further, if the amount of the solvent in the coating solution is increased in order to suppress an increase in the viscosity of the coating solution, a brushing phenomenon occurs and white turbidity is generated in the formed charge transport layer 16. When the ratio A / B exceeds 10/12 and the binder resin ratio is low, the printing durability is lowered and the wear amount of the photosensitive layer is increased as compared with the case where the binder resin ratio is high. Therefore, it was set to 10/30 or more and 10/12 or less.

In order to improve the film formability, flexibility and surface smoothness, an additive such as a plasticizer or a leveling agent may be added to the charge transport layer 16 as necessary. Examples of the plasticizer include dibasic acid esters, fatty acid esters, phosphate esters, phthalate esters, chlorinated paraffins, and epoxy type plasticizers. Examples of the leveling agent include a silicone leveling agent.
The charge transport layer 16 may be added with fine particles of an inorganic compound or an organic compound in order to enhance mechanical strength and improve electrical characteristics.

Furthermore, in the present invention, an antioxidant is added to the charge transport layer 16. By adding this antioxidant, the stability as a coating solution for forming a charge transport material-containing layer is improved, and the potential characteristics of a photoconductor prepared using the coating solution is improved, and when the photoconductor is used repeatedly. It is possible to reduce fatigue deterioration and improve durability.
This antioxidant, ozone generated during charging by corona discharge, the active gas or exposure, such as NO _x, by reacting preferentially with the free radicals generated by the ultraviolet light and heat contained in the discharging light, the present invention This is because it prevents the deterioration of enamine compounds.

In addition to the hindered amine antioxidants and phosphorus antioxidants described above, sulfide antioxidants, hindered phenol antioxidants, benzotriazole derivatives, and benzophenone derivatives are preferably used as the antioxidant.
Furthermore, these antioxidants may be used by mixing not only one type but also two or more types. In this case, the total amount of these compounds used is preferably in the range of 0.1 wt% to 25 wt% with respect to the total amount of the layer components including the charge transport material 14. Further, it is more preferably in the range of 0.1 wt% or more and 20 wt% or less. When the total amount of the antioxidant used is less than 0.1% by weight, it is not possible to obtain a sufficient effect for improving the stability of the coating solution and improving the durability of the photoreceptor. On the other hand, if it exceeds 25% by weight, the photoreceptor characteristics are adversely affected in actual use such as an increase in residual potential. Further, when the content is 20% by weight or less, stable electrophotographic characteristics can be ensured over a long period of time.

  When two or more kinds are mixed and used, it is preferable that each antioxidant is in the range of 0.1 wt% or more and 15 wt% or less. Further, it is more preferably in the range of 0.1 wt% or more and 10 wt% or less. If it is less than 0.1% by weight, sufficient effects cannot be obtained for improving the stability of the coating solution and improving the durability of the photoreceptor. If it is 15% by weight or less, stable electrophotographic characteristics can be obtained, and if it is 10% or less, the stability of the coating solution can be secured.

  The charge transport layer 16 is prepared by, for example, dissolving or dispersing the charge transport material 14 and the binder resin and, if necessary, the aforementioned additives in a suitable solvent, as in the case of forming the aforementioned charge generation layer 12. It is formed by preparing a coating solution for a charge transport layer and coating the coating solution on the charge generation layer 12 by a spray method, a bar coating method, a roll coating method, a blade method, a ring method or a dip coating method. . Among these coating methods, the dip coating method is particularly excellent in various respects as described above, and is often used when the charge transport layer 16 is formed.

  Solvents used in the coating solution include aromatic hydrocarbons such as benzene, toluene, xylene and monochlorobenzene, halogenated hydrocarbons such as dichloromethane and dichloroethane, ethers such as THF, dioxane and dimethoxymethyl ether, and N, N -1 type chosen from the group which consists of aprotic polar solvents, such as a dimethylformamide, is used individually or in mixture of 2 or more types. Further, a solvent such as alcohols, acetonitrile or methyl ethyl ketone can be further added to the above-described solvent as necessary.

  The film thickness of the charge transport layer 16 is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 40 μm or less. When the film thickness of the charge transport layer 16 is less than 5 μm, the charge holding ability on the surface of the photoreceptor is lowered. When the film thickness of the charge transport layer 16 exceeds 50 μm, the resolution of the photoreceptor decreases. Accordingly, the thickness is set to 5 μm or more and 50 μm or less.

  In the present invention, it is specified that the free chlorine concentration in the photosensitive layer is in the range of 10 to 4000 ppm. It has been found that these free chlorine concentrations can be within the charge transport layer or within the charge generation layer. The concentration of free chlorine can be adjusted by intentionally leaving an antioxidant or a by-product generated during the synthesis of the binder resin, but it can also be adjusted by adding it to the coating liquid.

Embodiment 2
FIG. 2 is a schematic cross-sectional view showing a simplified configuration of an electrophotographic photosensitive member 2 which is another example of the electrophotographic photosensitive member according to the present invention. The electrophotographic photosensitive member 2 is similar to the electrophotographic photosensitive member 1 shown in FIG. 1, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. It should be noted that an intermediate layer 18 is provided between the conductive support 11 and the photosensitive layer 17.

When the intermediate layer 18 is not present between the conductive support 11 and the photosensitive layer 17, charges are injected from the conductive support 11 into the photosensitive layer 17, the chargeability of the photosensitive layer 17 is lowered, and it is erased by exposure. Surface charges other than those that should be reduced may cause defects such as fogging in the image.
In particular, when an image is formed using a reversal development process, a toner image is formed in a portion where the surface charge has decreased due to exposure. Therefore, if the surface charge decreases due to factors other than exposure, the toner adheres to a white background. An image fogging called a black spot where minute black spots are formed occurs, and the image quality is significantly deteriorated. That is, due to defects in the conductive support 11 or the photosensitive layer 17, the chargeability in a minute region is reduced, and image fogging such as black spots occurs, resulting in a significant image defect.

By providing the intermediate layer 18 as described above, injection of charges from the conductive support 11 to the photosensitive layer 17 can be prevented, so that a decrease in chargeability of the photosensitive layer 17 can be prevented, and exposure can be performed by exposure. It is possible to suppress the reduction of the surface charge other than the portion to be erased and to prevent the occurrence of defects such as fogging on the image.
Further, by providing the intermediate layer 18, it is possible to cover the defects on the surface of the conductive support 11 and obtain a uniform surface, so that the film formability of the photosensitive layer 17 can be improved. Further, peeling of the photosensitive layer 17 from the conductive support 11 can be suppressed, and the adhesion between the conductive support 11 and the photosensitive layer 17 can be improved.

For the intermediate layer 18, a resin layer or an alumite layer made of various resin materials is used.
The resin material for forming the resin layer includes polyethylene resin, polypropylene resin, polystyrene resin, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, silicone resin, polyvinyl butyral resin, and polyamide. Examples thereof include resins such as resins, copolymer resins containing two or more of repeating units constituting these resins, casein, gelatin, polyvinyl alcohol, and ethyl cellulose. Among these, it is preferable to use a polyamide resin, and it is particularly preferable to use an alcohol-soluble nylon resin. Preferred alcohol-soluble nylon resins include, for example, so-called copolymer nylon obtained by copolymerizing 6-nylon, 6,6-nylon, 6,10-nylon, 11-nylon, 2-nylon, and the like, and N-alkoxymethyl-modified. Examples thereof include resins obtained by chemically modifying nylon, such as nylon and N-alkoxyethyl-modified nylon.

The intermediate layer 18 may contain particles such as a metal oxide. By containing these particles, the volume resistance value of the intermediate layer 18 can be adjusted to further prevent the injection of charges from the conductive support 11 to the photosensitive layer 17, and the photosensitive member can be used in various environments. Electrical characteristics can be maintained.
Examples of metal oxide particles include particles of titanium oxide, aluminum oxide, aluminum hydroxide, tin oxide, and the like.

When the intermediate layer 18 contains particles such as metal oxide, for example, these particles are dispersed in a resin solution in which the above-described resin is dissolved to prepare an intermediate layer coating solution. The intermediate layer 18 can be formed by coating on the support 11.
Water or various organic solvents are used as the solvent for the resin solution. In particular, a single solvent such as water, methanol, ethanol or butanol, or water and alcohols, two or more alcohols, acetone or dioxolane and alcohols, chlorinated solvents such as dichloroethane, chloroform and trichloroethane and alcohols, etc. A mixed solvent is preferably used.

As a method for dispersing the aforementioned particles in the resin solution, a general method using a ball mill, a sand mill, an attritor, a vibration mill, an ultrasonic disperser, or the like can be used.
The total content C of the resin and metal oxide in the coating solution for intermediate layer is such that C / D is 1/99 to 40 / weight ratio by weight with respect to the content D of the solvent used in the coating solution for intermediate layer. 60 is preferable, and 2/98 to 30/70 is more preferable.
The ratio of resin to metal oxide (resin / metal oxide) is preferably 1/99 to 90/10, more preferably 5/95 to 70/30, by weight.

  Examples of the coating method of the intermediate layer coating liquid include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method. In particular, as described above, the dip coating method is relatively simple and excellent in terms of productivity and cost. Therefore, the dip coating method is often used for forming the intermediate layer 18.

  The film thickness of the intermediate layer 18 is preferably 0.01 μm or more and 20 μm or less, and more preferably 0.05 μm or more and 10 μm or less. If the thickness of the intermediate layer 18 is less than 0.01 μm, the intermediate layer 18 substantially does not function, and the surface of the conductive support 11 cannot be covered to obtain a uniform surface property. It becomes impossible to prevent the injection of charges from the body 11 to the photosensitive layer 17 and the chargeability of the photosensitive layer 17 is lowered. Making the thickness of the intermediate layer 18 greater than 20 μm makes it difficult to form the intermediate layer 18 when the intermediate layer 18 is formed by dip coating, and makes the photosensitive layer 17 uniformly on the intermediate layer 18. Since it cannot be formed and the sensitivity of the photoreceptor is lowered, it is not preferable.

Embodiment 3
FIG. 3 is a schematic cross-sectional view showing a simplified configuration of an electrophotographic photoreceptor 3 which is still another example of the electrophotographic photoreceptor according to the present invention. The electrophotographic photosensitive member 3 is similar to the electrophotographic photosensitive member 2 shown in FIG. 2, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.
It should be noted that the electrophotographic photosensitive member 3 is a single layer type photosensitive member having a photosensitive layer 140 having a single layer structure in which a charge generating material 13 and a charge transporting material 14 are contained in a binder resin. is there.

  The photosensitive layer 140 is formed by the same method as that for forming the charge transport layer 12 described above. For example, the above-described charge generating material 13, the charge transport material 14 containing the organic photoconductive material of the present invention represented by the general formula (1), particularly the general formula (2), the binder resin, and the antioxidant of the present invention. The photosensitive layer coating solution is prepared by dissolving or dispersing in the above-mentioned appropriate solvent, and this photosensitive layer coating solution is applied onto the intermediate layer 18 by a dip coating method or the like.

The ratio of the charge transport material 14 and the binder resin in the photosensitive layer 140 is 10/30 to 10 by weight ratio, similar to the ratio A / B of the charge transport material 14 and the binder resin in the charge transport layer 16 described above. / 12.
The film thickness of the photosensitive layer 140 is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less. If the film thickness of the photosensitive layer 140 is less than 5 μm, the charge holding ability on the surface of the photoreceptor is lowered. When the film thickness of the photosensitive layer 140 exceeds 100 μm, the productivity is lowered. Accordingly, the thickness is set to 5 μm or more and 100 μm or less.
The electrophotographic photosensitive member according to the present invention is not limited to the configuration shown in FIGS. 1 to 3 described above, and can adopt various layer configurations.

Embodiment 4
Next, an image forming apparatus including the electrophotographic photosensitive member according to the present invention will be described. The image forming apparatus according to the present invention is not limited to the following description.

FIG. 4 is a configuration diagram showing a simplified configuration of the image forming apparatus 100 including the electrophotographic photosensitive member 10 according to the present invention.
The image forming apparatus 100 includes an electrophotographic photoreceptor 10 according to the present invention (hereinafter also simply referred to as “photoreceptor 10”). The photosensitive member 10 has a cylindrical shape and is rotationally driven at a predetermined peripheral speed in the direction of reference numeral 41 by a driving unit (not shown). A charger 32, a semiconductor laser (not shown), a developing device 33, a transfer charger 34, and a cleaner 36 are provided in this order around the photoconductor 10 along the rotation direction of the photoconductor 10. A fixing device 35 is provided in the traveling direction of the transfer paper 51.

  An image forming process by the image forming apparatus 100 will be described. First, the photoreceptor 10 is uniformly charged with a predetermined positive or negative potential on a surface 43 facing the charger 32 by a contact-type or non-contact-type charger 32. Next, a laser beam 31 is irradiated from a semiconductor laser (not shown), and the surface 43 of the photoreceptor 10 is exposed. The laser beam 31 is repeatedly scanned in the longitudinal direction of the photoconductor 10 which is the main scanning direction, and accordingly, electrostatic latent images are sequentially formed on the surface 43 of the photoconductor 10. The formed electrostatic latent image is developed as a toner image by a developing device 33 provided on the downstream side in the rotation direction from the image forming point of the laser beam 31.

In synchronism with the exposure of the photosensitive member 10, the transfer paper 51 is fed from the direction of reference numeral 42 to the transfer charger 34 provided on the downstream side in the rotation direction of the developing device 33.
The toner image formed on the surface 43 of the photoconductor 10 in the developing device 33 is transferred onto the surface of the transfer paper 51 by the transfer charger 34. The transfer paper 51 onto which the toner image has been transferred is transported to the fixing device 35 by a transport belt (not shown), and the toner image 0 is fixed to the transfer paper 51 by the fixing device 35 to form part of the image.

  The toner remaining on the surface 43 of the photoconductor 10 is removed by a cleaner 36 provided with a charge eliminating lamp (not shown) further downstream in the rotation direction of the transfer charger 34 and upstream in the rotation direction of the charger 32. By further rotating the photoreceptor 10, the above process is repeated and an image is formed on the transfer paper 51. The transfer paper 51 on which the image is formed in this way is discharged outside the image forming apparatus 100.

  As described above, the electrophotographic photoreceptor 10 according to the present invention provided in the image forming apparatus 100 contains the organic photoconductive material of the present invention represented by the general formula (1) or (2) as the charge transport material 14. Therefore, the charging potential is high, the sensitivity is high, the photoresponsiveness is sufficient, the durability is excellent, and the characteristics are not deteriorated even when used in a low temperature environment or in a high-speed process. Therefore, it is possible to obtain a highly reliable image forming apparatus capable of providing high quality images under various environments. Further, since the characteristics of the electrophotographic photoreceptor 10 are not deteriorated by exposure to light, it is possible to prevent deterioration of image quality due to exposure of the photoreceptor to light during maintenance or the like, and to improve the reliability of the image forming apparatus. Can do.

  EXAMPLES Next, although this invention is demonstrated further in detail using an Example, this invention is not limited to this.

<Measurement of free chlorine concentration>
Sample Sampling Samples were partially peeled off and weighed as finely as possible for analysis.

Preparation of Standard Solution Chloride ion standard solution (1005 μg / mL, manufactured by Wako Pure Chemical Industries, Ltd., Lot. DCF1125) was sequentially diluted with a separately prepared phosphoric acid internal standard to prepare a standard solution. Of these, a calibration curve was prepared using analysis data of a standard solution suitable for analyzing the concentration in the sample.

Combustion ion chromatography of sample The sample was weighed and burned in the combustion tube of the analyzer described below, and the generated gas was absorbed into the solution, and then a part of the absorption liquid was analyzed by ion chromatography.

Combustion and absorption conditions System: AQF-2100H, GA-210 (Mitsubishi Chemical)
Electric furnace temperature: Inlet 900 ° C, Outlet 1000 ° C
Gas: Ar / O ₂ 200 mL / min.
O ₂ 400 mL / min.
Absorbent: H ₂ O ₂ 90 μg / mL, internal standard phosphoric acid 2 μg / mL
Absorption liquid volume: 5mL

Ion chromatography and anion analysis conditions System: ICS1600 (manufactured by DIONEX)
Mobile phase: 2.7 mmol / L Na ₂ CO ₃ /0.3 mmol / L NaHCO ₃
Flow rate: 1.50 mL / min.
Detector: Electrical conductivity detector Injection volume: 100 μL

<Production method of polycarbonate resin>
In general, the production of a polycarbonate binder resin is synthesized by a phosgene method.
This polycarbonate resin synthesis method is represented by the following reaction scheme:

Shown in

According to the above reaction scheme, the produced polycarbonate binder resin contains phosgene-derived HCl, which is produced as a by-product in which phosgene added for the polymerization is consumed during the polymerization.
In general, commercially available polycarbonate resins are shipped after sufficiently washed with water to suppress the mixing of HCl as much as possible in order to suppress the mixing of HCl.

As one of the control of the free chlorine concentration of the photosensitive layer of the present invention, in the binder resin polycarbonate resin in the charge transport layer, a method of controlling the free chlorine concentration of the entire photosensitive layer by leaving free chlorine in the process of synthesis. There is.
The concentration of free chlorine in the charge transport layer can be controlled by leaving HCl as a by-product during purification of the polymer. Further, HCl can be added in advance to the charge transport layer forming coating solution in order to obtain a suitable concentration of free chlorine in the charge transport layer.

Manufacture of polycarbonate binder resin (1) A polycarbonate polymer obtained by the phosgene method is repeatedly washed with water until the dielectric constant of the aqueous layer becomes 8.05 μs / cm in the water washing step, filtered and dried to obtain the desired binder. Resin (1) could be obtained. It was confirmed that the free chlorine concentration of the binder resin (1) was 16.3 ppm.

Manufacture of polycarbonate binder resin (2) The polymer is synthesized in the same manner as polycarbonate binder resin (1), and water washing is repeated until the dielectric constant of the water layer in the water washing step is 5.2 μs / cm. The target binder resin (2) could be obtained by filtering and drying. It was confirmed that the free chlorine concentration of the binder resin (2) was 1.9 ppm.

Example 1
A mixed solvent of 21 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd .: TTO55A) and 39 parts by weight of a copolymer nylon resin (Toray Industries, Inc .: CM8000), 329 parts by weight of methanol and 611 parts by weight of 1,2-dichloroethane In addition to the above, it was dispersed for 8 hours using a paint shaker to prepare a coating solution for an intermediate layer. The prepared coating solution for intermediate layer was applied to a 0.2 mm thick aluminum substrate as the conductive support 11 with a bakery applicator and then dried to form an intermediate layer 18 having a thickness of 1 μm. (Total amount 18g, yield 92.3%)

  Next, a resin obtained by dissolving 2 parts by weight of Y-type oxotitanium phthalocyanine as the charge generating material 13 and 1 part by weight of polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd .: BX-1) in 97 parts by weight of methyl ethylken After adding to the solution, it was dispersed with a paint shaker for 10 hours to prepare a coating solution for charge generation layer. This charge generation layer coating solution was applied onto the previously formed intermediate layer 18 with a baker applicator and then dried to form a charge generation layer 12 having a thickness of 0.4 μm. (Total amount: 18 g, yield: 95%)

Next, 10 parts by weight of the enamine compound of Exemplified Compound 1-43 which is the charge transport material 14, 18 parts by weight of the binder resin (1) prepared by the above synthesis route, and hindered amine of Exemplified Compound HA-10 which is an antioxidant Compound (BASF Sanol LS-2626) 1.5 parts by weight (about 5% based on the total amount of the layer components including the charge transport material) and Illustrative Compound P14 (irgafos 168 manufactured by BASF) which is a phosphorus-based antioxidant 1. 5 parts by weight (about 5% with respect to the total amount of the layer components including the charge transport material) was dissolved in 100 parts by weight of THF to prepare a charge transport layer coating solution. This coating solution for charge transport layer was applied on the charge generation layer 12 formed previously with a baker applicator and then dried to form a charge transport layer 16 having a thickness of 23 μm.
What is the free chlorine concentration in the photosensitive layer prepared as described above? It was 10 ppm. (Total amount: 49.5 g)

Example 2
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that Exemplified Compound 1-1 was used in place of Exemplified Compound 1-43.

Example 3
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that Exemplified Compound 1-111 was used in place of Exemplified Compound 1-43.
Examples 4 and 5
In investigating the appropriate value of the free chlorine concentration in the photosensitive layer according to Example 1, the objective is to determine the free chlorine concentration in the photosensitive layer by simply dropping HCl into the charge transport layer coating solution. A photosensitive layer was prepared. In Example 4, adjustment was made so that the free chlorine concentration was 500 ppm, and in Example 5, it was 3850 ppm.

Example 6
Example Example P-36 (HP-10 manufactured by ADEKA) shown in Table 3-3 was added to the charge transport layer of Example 1 instead of P-14, which is a phosphorus-based antioxidant. In the same manner as in Example 1, an electrophotographic photosensitive member was produced.

Example 7
Electrons were obtained in the same manner as in Example 4 except that Example Compound S14 (IRGANOX 1035 manufactured by BASF) was added to the charge transport layer of Example 4 in place of hindered amine compound HA-10 and phosphorus antioxidant P14. A photographic photoreceptor was prepared.

Example 8
An electrophotographic photosensitive member was produced in the same manner as in Example 4 except that P-14, which is a phosphorus antioxidant, was not added to the charge transport layer of Example 4.

Example 9
Example 4 except that the amount of hindered amine compound HA-10 added to the charge transport layer of Example 4 is 0.028 part by weight (about 0.1% with respect to the total amount of layer components including the charge transport material). Thus, an electrophotographic photosensitive member was produced.

Example 10
In the charge transport layer of Example 4, the amount of hindered amine compound HA-10 added was 3 parts by weight (about 10% with respect to the total amount of the layer components including the charge transport material), and P-14, which is a phosphorus antioxidant, was added. An electrophotographic photosensitive member was produced in the same manner as in Example 4 except that the addition amount was 3 parts by weight (about 10% with respect to the total amount of the layer components including the charge transport material).

Example 11
An electrophotographic photosensitive member was produced in the same manner as in Example 4 except that the hindered amine compound HA-10 was not added to the charge transport layer of Example 4.

Example 12
Example 4 except that the amount of the phosphorus-based antioxidant P-14 added to the charge transport layer of Example 4 is 0.028 part by weight (about 0.1% with respect to the total amount of the layer components including the charge transport material). In the same manner as above, an electrophotographic photosensitive member was produced.

Example 13
Same as Example 4 except that the addition amount of the phosphorus-based antioxidant P-14 to the charge transport layer of Example 4 is 4.2 parts by weight (about 15% with respect to the total amount of the layer components including the charge transport material). Thus, an electrophotographic photosensitive member was produced.

Comparative Example 1
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the binder resin (1) in the coating solution for charge transport layer in Example 1 was changed to the binder resin (2).

Comparative Example 2
An electrophotographic photosensitive member was produced in the same manner as in Example 6 except that the binder resin (1) in the coating solution for charge transport layer in Example 6 was changed to the binder resin (2).

Comparative Example 3
An electrophotographic photosensitive member was produced in the same manner as in Example 4 except that the free chlorine concentration in the photosensitive layer of Example 4 was 4350 ppm.

Comparative Example 4
Example 1 An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that the additives HA-14 and P-14 were not added to the charge transport layer coating solution.

The electric characteristics (sensitivity) of the photoreceptors of Examples 1 to 13 and Comparative Examples 1 to 4 were evaluated as follows.

<Evaluation 1>
Each electrophotographic photosensitive member is a commercially available small digital copying machine (manufactured by Sharp Corporation: AR) modified so that the surface potential of the photosensitive member in the image forming process can be measured with a surface potential meter (Gentec Corporation: CATE 751). -C260). Under an environment of a temperature of 22 ° C. and a humidity of 5% (low humidity), the power was turned off immediately after 180,000 live-action aging for copying a test image of a predetermined pattern onto plain paper, and left for 1 hour. Thereafter, a halftone image was formed on plain paper of Japanese Industrial Standard (JIS) A3 size. Here, the halftone image is an image in which gradation of the image is expressed by gradation using black and white dots. The obtained image was visually observed, and the image quality was evaluated by the degree of image defects such as white spots, black belts, and image blur.
The image quality was evaluated according to the following criteria.
G (good): Good. No image defects.
NB (not bad): Somewhat bad. There are image defects that can be ignored.
B (bad): Bad. There is an obvious image defect.

<Evaluation 2>
Each electrophotographic photosensitive member using a test copying machine modified from the above-mentioned digital copying machine (trade name: MX-2600, manufactured by Sharp Corporation) is constant at 35 ° C. (high temperature) / 85% (high humidity). Under the environment, the surface potential VL of the photoreceptor at the initial stage (before printing) and the surface potential VL of the photoreceptor after continuous printing of 100,000 sheets were measured. The surface potential VL indicates the surface potential of the photosensitive member at the black background at the time of exposure, that is, the surface potential of the photosensitive member at the developing portion.
A value ΔVL obtained by subtracting the initial surface potential from the surface potential after 180,000 continuous printing was calculated. Then, the electrical characteristics of the photoconductor were evaluated as follows.
G: Good (0 ≦ ΔVL <100).
NB: No problem in practical use (100 ≦ ΔVL <130).
B: Actual use is not possible (130 ≦ ΔVL).

<Evaluation 3>
For each charge transport layer coating solution, store the coating solution for 3 months in a 20 ° C storage room, and compare the difference in surface potential before and after storage in a constant environment of 25 ° C and 5% for the MX2600 remodeling test copy machine. went.
G: No problem ΔVL <15V
B: Coating solution deteriorates greatly and cannot be used in actual use> 15V

<Comprehensive judgment>
VG (very good): very good, when evaluations 1 to 3 were all G determinations G: evaluations 1 to 3 were all without any B determinations, and there was no problem in actual use B: In evaluations 1 to 3, when there is a B judgment for one item and it cannot be used

As a result of the above, by introducing the additive defined in the present invention into the photoconductor containing the enamine compound of the present invention, as can be seen from Evaluation 1, an image caused by oxidizing gas in a low humidity environment It can be seen that the defects are improved. (Comparison between Example and Comparative Example 4)
However, as can be seen from the evaluation 2, it can be seen that by adding the additive, the increase in VL due to electrical fatigue in a high-humidity environment is large, and an adverse effect due to the additive appears.
Thus, it can be seen that by controlling the free chlorine concentration to 10 to 4000 ppm as defined in the invention, it is possible to suppress an increase in residual potential due to long-term conduction fatigue. (Examples and Comparative Examples 1 and 2) In order to increase the free chlorine, a method using a binder resin having a high free chlorine concentration as in Example 1 can be mentioned. As a result, the cost of the binder resin is reduced.

  Further, there is a concern that increasing the free chlorine concentration in the photosensitive layer may lead to deterioration of the coating liquid as a harmful effect. As can be seen from Evaluation 3, storing the coating solution for 3 months resulted in a deterioration in sensitivity characteristics (Comparative Examples 3 and 4). It is presumed that the enamine compound has deteriorated and the movement of holes in the photosensitive layer is affected. However, it has been found that the combined use of antioxidants, particularly the antioxidants defined in this patent, are extremely effective in increasing the stability of the coating solution. (Comparison between Example and Comparative Example 4) If the free chlorine concentration is also increased to 4000 ppm or more, the coating solution is too deteriorated to be practically used. In view of productivity, it has been found that it is necessary to suppress it to 4000 ppm or less.

The electrophotographic photoreceptor according to the present invention is an under-purified polycarbonate binder resin that has been conventionally avoided, that is, HCl and / or free chlorine (hereinafter referred to as free chlorine) present as a by-product derived from the production process. When a resin containing an ion) is used in combination with an antioxidant, the resistance of the entire photosensitive layer is lowered, and the movement of carriers in the photosensitive layer can be promoted, so that the cost of the polycarbonate binder resin can be reduced.
Furthermore, according to the present invention, HCl is added for the purpose of adjusting the free chlorine concentration as necessary, by adding a free chlorine concentration and an antioxidant within a specific range to the coating liquid containing the charge transport material. By adding to the coating liquid, deterioration of the coating liquid can be suppressed, and an increase in residual potential due to repeated energization fatigue of a photoreceptor prepared using the coating liquid can be suppressed.

1, 2, 3, 10 Electrophotographic photoreceptor 11 Conductive support 12 Charge generation layer 13 Charge generation material 14 Charge transport material 17, 140 Photosensitive layer 16 Charge transport layer 18 Intermediate layer 31 Laser beam 32 Charger 33 Developer 34 Transfer charging device 35 Fixing device 36 Cleaner 51 Transfer paper 100 Image forming apparatus

Claims (13)

A laminated photosensitive layer in which a charge generating layer containing at least a charge generating material and a charge transporting layer containing a charge transporting material are laminated in this order, or a single-layered photosensitive layer containing a charge generating material and a charge transporting material is a conductive substrate. An electrophotographic photoreceptor laminated on the top,
In the electrophotographic photoreceptor, the following general formula (1) is used as a charge transport material:
(1)
(Where
a represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, alkoxy group, dialkylamino group or aryl group;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a's may be the same or different from each other. When a is an alkyl group, adjacent a's are bonded to each other to form a ring structure. May form;
Ar ¹ and Ar ² each represent an aryl group which may have a substituent or a heterocyclic group which may have a substituent;
Ar ³ represents an aryl group that may have a substituent, a heterocyclic group that may have a substituent, an aralkyl group that may have a substituent, or an alkyl group that may have a substituent. ;
Ar ⁴ and Ar ⁵ are the same as or different from each other, and each represents a hydrogen atom or an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group, provided that Ar ⁴ and Ar ⁵ are Cannot simultaneously be hydrogen atoms, and Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or atomic group to form a ring structure;
R ¹ represents a hydrogen atom, a halogen atom or an alkyl group which may have a substituent;
R ² , R ³ and R ⁴ are each a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, a heterocyclic group which may have a substituent or a substituent. An aralkyl group which may have
n represents an integer of 0 to 3, and when n is 2 or 3, a plurality of R ² and R ³ may be the same or different, provided that when n is 0, Ar ³ has a substituent. A heterocyclic group which may be
And the layer containing the charge transport material contains free chlorine,
An electrophotographic photoreceptor comprising a concentration of 10 to 4000 ppm and containing at least one antioxidant. In the general formula (1), Ar ¹ is a phenyl group which may be substituted with b _i , Ar ² is a phenyl group which may be substituted with _ck , and Ar ³ is substituted with d _j. And R ¹ , R ² , R ³ and R ⁴ are hydrogen, and the enamine compound represented by the general formula (1) is represented by the following general formula (2):
(2)
(Where
a represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, alkoxy group, dialkylamino group or aryl group;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a's may be the same or different from each other. When a is an alkyl group, adjacent a's are bonded to each other to form a ring structure. May form;
b, c and d are the same or different from each other and each represents a hydrogen atom, a halogen atom, or an alkyl group, alkoxy group, dialkylamino group, aryl group, aryloxy group or arylthio group which may have a substituent. ;
i, k and j are the same or different from each other, and are integers of 1 to 5, and when i, j or k is 2 or more, each of a plurality of b, c or d may be the same or different from each other. Or each of b, c or d bonded to adjacent carbon atoms of the benzene ring may be bonded together to form a ring structure;
Ar ⁴ and Ar ⁵ are the same as or different from each other, and each represents a hydrogen atom or an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group, provided that Ar ⁴ and Ar ⁵ are At the same time, it cannot be a hydrogen atom, and Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or an atomic group to form a ring structure)
The electrophotographic photoreceptor according to claim 1, represented by: In the general formula (2), the following partial structure:
But the following substituents:
Means the following substructure:
Are the same or different from each other and have the following substituents:
Means the following substructure:
But the following substituents:
Wherein Ar ⁴ or Ar ⁵ is the following substituent:
Wherein Ar ⁵ or Ar ⁴ is the following substituent:
Or said Ar ⁴ and Ar ⁵ together are the following substituents:
The electrophotographic photosensitive member according to claim 1, which means The antioxidant is
The following general formula (3):
(3)
(Wherein R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are the same as or different from each other, and represent a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group or an aralkyl group; R ²⁰ represents a hydrogen atom or a monovalent group) W represents an organic residue; W represents an atomic group necessary to form a ring structure containing an amino nitrogen atom, provided that R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are not hydrogen atoms with each other. )
A hindered amine antioxidant represented by:
The following general formula (4):
(In the formula, R ²¹ , R ²² and R ²³ are the same or different from each other, and are a hydroxy group, an alkoxy group, an alkylsulfanyl group, an optionally substituted phenyl group or phenoxy group, or R ²¹ , R ^22. And any two of R ²³ are bonded to each other to form a ring structure containing one phosphorus atom, or any one of R ²¹ , R ²² and R ^{23 in} the two compounds of the general formula (4) Can be bonded to each other to form a ring structure containing two phosphorus atoms, provided that R ²¹ , R ²² and R ²³ are not mutually hydroxy groups)
A phosphorus-based antioxidant represented by the following general formula (5):
(Wherein R ²⁵ and R ²⁶ are the same or different from each other, and may be an alkyl group or a phenyl group which may have a substituent, or the following partial structure:
Or (wherein R ²⁸ is a hydrogen atom, an optionally substituted alkyl group, or a 4-hydroxy 3,5-di-t-butylphenethyl group)
Have)
The electrophotographic photosensitive member according to claim 1, which is selected from sulfide-based antioxidants represented by the formula:   5. The layer according to claim 1, wherein the layer containing the charge transport material contains 0.1 to 25% by weight of an antioxidant based on the total amount of the layer components containing the charge transport material. Electrophotographic photoreceptor.   6. The layer according to claim 1, wherein the layer containing the charge transport material contains 0.1 to 20% by weight of an antioxidant with respect to the total amount of the layer components containing the charge transport material. Electrophotographic photoreceptor. The electrophotographic photosensitive member according to any one of claims 1 to 6,
Charging means for charging the electrophotographic photoreceptor;
Exposure means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image; and
Developing means for developing the electrostatic latent image with toner to form a toner image;
Transfer means for transferring the toner image onto a recording material;
An image forming apparatus comprising fixing means for fixing the transferred toner image on the recording material. A charge transport material-containing coating solution for forming a layer containing at least a charge transport material and optionally containing a charge generation material,
The following general formula (1) as a charge transport material:
(1)
(Where
a represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, alkoxy group, dialkylamino group or aryl group;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a's may be the same or different from each other. When a is an alkyl group, adjacent a's are bonded to each other to form a ring structure. May form;
Ar ¹ and Ar ² each represent an aryl group which may have a substituent or a heterocyclic group which may have a substituent;
Ar ³ represents an aryl group that may have a substituent, a heterocyclic group that may have a substituent, an aralkyl group that may have a substituent, or an alkyl group that may have a substituent. ;
Ar ⁴ and Ar ⁵ are the same as or different from each other, and each represents a hydrogen atom or an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group, provided that Ar ⁴ and Ar ⁵ are Cannot simultaneously be hydrogen atoms, and Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or atomic group to form a ring structure;
R ¹ represents a hydrogen atom, a halogen atom or an alkyl group which may have a substituent;
R ² , R ³ and R ⁴ are each a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, a heterocyclic group which may have a substituent or a substituent. An aralkyl group which may have
n represents an integer of 0 to 3, and when n is 2 or 3, a plurality of R ² and R ³ may be the same or different, provided that when n is 0, Ar ³ has a substituent. A heterocyclic group which may be
The charge transport characterized in that the enamine compound represented by the above formula, the layer containing the charge transport material contains free chlorine at a concentration in the range of 10 to 4000 ppm and contains at least one antioxidant. A coating solution for forming a substance-containing layer. In the general formula (1), Ar ¹ is a phenyl group which may be substituted with b _i , Ar ² is a phenyl group which may be substituted with _ck , and Ar ³ is substituted with d _j. And R ¹ , R ² , R ³ and R ⁴ are hydrogen, and the enamine compound represented by the general formula (1) is represented by the following general formula (2):
(2)
(Where
a represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, alkoxy group, dialkylamino group or aryl group;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a's may be the same or different from each other. When a is an alkyl group, adjacent a's are bonded to each other to form a ring structure. May form;
b, c and d are the same or different from each other and each represents a hydrogen atom, a halogen atom, or an alkyl group, alkoxy group, dialkylamino group, aryl group, aryloxy group or arylthio group which may have a substituent. ;
i, k and j are the same or different from each other, and are integers of 1 to 5, and when i, j or k is 2 or more, each of a plurality of b, c or d may be the same or different from each other. Or each of b, c or d bonded to adjacent carbon atoms of the benzene ring may be bonded together to form a ring structure;
Ar ⁴ and Ar ⁵ are the same as or different from each other, and each represents a hydrogen atom or an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group, provided that Ar ⁴ and Ar ⁵ are At the same time, it cannot be a hydrogen atom, and Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or an atomic group to form a ring structure)
The coating liquid for charge transport substance containing layer formation of Claim 8 represented by these. In the general formula (2), the following partial structure:
But the following substituents:
Means the following substructure:
Are the same or different from each other and have the following substituents:
Means the following substructure:
But the following substituents:
Wherein Ar ⁴ or Ar ⁵ is the following substituent:
Wherein Ar ⁵ or Ar ⁴ is the following substituent:
Or said Ar ⁴ and Ar ⁵ together are the following substituents:
The coating liquid for charge transport substance containing layer formation of Claim 8 or 9 which means. The antioxidant is
The following general formula (3):
(3)
(Wherein R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are the same as or different from each other, and represent a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group or an aralkyl group; R ²⁰ represents a hydrogen atom or a monovalent group) W represents an organic residue; W represents an atomic group necessary to form a ring structure containing an amino nitrogen atom, provided that R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are not hydrogen atoms with each other. )
A hindered amine antioxidant represented by:
The following general formula (4):
(In the formula, R ²¹ , R ²² and R ²³ are the same or different from each other, and are a hydroxy group, an alkoxy group, an alkylsulfanyl group, an optionally substituted phenyl group or phenoxy group, or R ²¹ , R ^22. And any two of R ²³ are bonded to each other to form a ring structure containing one phosphorus atom, or any one of R ²¹ , R ²² and R ^{23 in} the two compounds of the general formula (4) Can be bonded to each other to form a ring structure containing two phosphorus atoms, provided that R ²¹ , R ²² and R ²³ are not mutually hydroxy groups)
A phosphorus-based antioxidant represented by the following general formula (5):
(Wherein R ²⁵ and R ²⁶ are the same or different from each other, and may be an alkyl group or a phenyl group which may have a substituent, or the following partial structure:
Or (wherein R ²⁸ is a hydrogen atom, an optionally substituted alkyl group, or a 4-hydroxy 3,5-di-t-butylphenethyl group)
Have)
The charge transport material-containing layer forming coating solution according to claim 8, which is selected from sulfide-based antioxidants represented by the formula:   12. The charge transport layer forming coating solution according to claim 8, comprising 0.1 to 25% by weight of an antioxidant with respect to the total amount of layer components including a charge transport material. Coating liquid for forming a layer containing a charge transport material.   13. The charge transport layer forming coating solution according to claim 8, comprising 0.1 to 20% by weight of an antioxidant with respect to the total amount of the layer components including the charge transport material. Coating liquid for forming a layer containing a charge transport material.