JP2007304435A - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor excellent in electrical properties and capable of effectively suppressing fogging even in a high temperature and high humidity environment, and an image forming apparatus equipped with the same. <P>SOLUTION: The electrophotographic photoreceptor has a photosensitive layer formed on a substrate directly or by way of an intermediate layer. The image forming apparatus provided with the same is also provided. The photosensitive layer contains a charge generating agent, a hole transport agent and a binder resin, wherein hydrazone compound having an enamine group represented by formula (1) is used as the hole transport agent. In the formula (1), R<SP>1</SP>is a ≥2C alkyl group; a plurality of symbols Ra-Rf are each independently a 1-12C substituted or unsubstituted alkyl group or the like; numbers of repetitions m and n are each an integer of 0-4; and numbers of repetitions o-r are each an integer of 0-5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic photoreceptor and an image forming apparatus. In particular, by using a hole transporting agent having a specific structure, an electrophotographic photosensitive member that has excellent electrical characteristics and can effectively suppress the occurrence of fog even in a high-temperature and high-humidity environment, and an image forming apparatus including the same About.

Conventionally, as an electrophotographic photosensitive member used in an image forming apparatus, a charge generating agent for generating a charge by light irradiation, a charge transporting agent for transporting the generated charge, and these substances are dispersed. An organic photoreceptor containing a binder resin for forming a layer is widely used.
The charge transport agent used in such an organic photoreceptor includes an electron transport agent for transporting electrons and a hole transport agent for transporting holes. Of these, hydrazone compounds and stilbene compounds are used as hole transporting agents, but it has not yet been achieved to obtain sufficient hole transporting ability, and therefore, an electrophotographic photoreceptor having sufficient electrical characteristics. It has not been obtained.

Therefore, in order to solve the problem of the hole transport ability, an electrophotographic photoreceptor using a specific enamine group-containing hydrazone compound as a hole transport agent having excellent mobility is disclosed (for example, Patent Document 1). reference).
JP-A-10-133401 (Claims)

However, even when the enamine group-containing hydrazone compound represented by the general formula (29) in Patent Document 1 is used, the above-described problem cannot be sufficiently solved.
That is, if the substituents R ^{1 to} R ² and R ^{4 to} R ⁶ in the enamine group-containing hydrazone compound represented by the general formula (29) are all substituted or unsubstituted aryl groups, sufficient holes Although it was possible to exhibit the transport ability, otherwise, there was a problem that the hole transport ability was not sufficient.

(In the general formula (29), R ¹ and R ² each represents an alkyl group, an aryl group or a heterocyclic ring which may have a substituent, and R ³ may have a hydrogen atom, a halogen atom or a substituent. A good alkyl group or an alkoxy group, m represents an integer of 0 to 1. R ⁶ represents an alkyl group, an aralkyl group, an aryl group or a heterocyclic ring which may have a substituent, and R ⁴ and R ⁵ represent Each represents an optionally substituted alkyl group, alkenyl group, aralkyl group, aryl group, or heterocyclic ring.)

When the substituents R ^{1 to} R ² and R ^{4 to} R ⁶ in the enamine group-containing hydrazone compound represented by the general formula (29) are all substituted or unsubstituted aryl groups, sufficient holes While exhibiting the transport ability, there was a problem that the solubility of the compound in the coating solution for the photosensitive layer was very low.
As a result, since the hole transporting agent crystallizes in the photosensitive layer, there has been a problem that fog is likely to occur when an image is formed in a high temperature and high humidity environment.

Therefore, as a result of intensive studies, the present inventors have sufficiently dissolved the hole transport agent in the photosensitive layer coating solution by including a hole transport agent having a specific structure in the photosensitive layer. The present inventors have found that crystallization can be effectively prevented and the excellent hole transport ability can be sufficiently exhibited.
That is, an object of the present invention is to provide an electrophotographic photosensitive member that has excellent electrical characteristics and can effectively suppress the occurrence of fog even in a high-temperature and high-humidity environment, and an image forming apparatus including the electrophotographic photosensitive member.

  According to the electrophotographic photosensitive member of the present invention, an electrophotographic photosensitive member having a photosensitive layer formed directly or via an intermediate layer on a substrate, the photosensitive layer comprising a charge generating agent, a hole transporting agent, And an electrophotographic photosensitive member, wherein the hole transporting agent is an enamine group-containing hydrazone compound represented by the following general formula (1). Can be solved.

(In General Formula (1), R ¹ is an alkyl group having 2 or more carbon atoms, and a plurality of Ra to Rf are each independently a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or 6 to 30 carbon atoms. Substituted or unsubstituted aryl group, substituted or unsubstituted alkenyl group having 6 to 30 carbon atoms, or —OR ² (R ² is an alkyl group having 1 to 10 carbon atoms, a perfluoroalkyl group, or 6 to 6 carbon atoms). 30 is an aryl group), and the repeating numbers m and n are integers of 0 to 4, and the repeating numbers o to r are integers of 0 to 5.)

That is, the enazone group-containing hydrazone compound having the specific structure represented by the general formula (1) can be sufficiently dissolved in the coating solution for the photosensitive layer, so that crystallization in the photosensitive layer is effective. Can be prevented.
Therefore, the occurrence of fog can be effectively suppressed even in a high temperature and high humidity environment, for example, at a temperature of 35 ° C. and a relative humidity of 85%.
Furthermore, since the enamine group-containing hydrazone compound having a specific structure represented by the general formula (1) has an excellent hole transport ability, the electrical characteristics of the electrophotographic photoreceptor can be improved. More specifically, effects such as suppression of exposure memory and improvement of sensitivity can be obtained.

  In constituting the electrophotographic photoreceptor of the present invention, the binder resin is preferably at least one selected from the group consisting of polycarbonate resins represented by the following general formulas (2) to (4).

(In General Formula (2), a plurality of substituents Rg are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. The number s is an integer from 0 to 4.)

(In General Formula (3), the plurality of substituents Rh are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. The number t is an integer from 0 to 4.)

(In the general formula (4), the plurality of substituents Ri are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. The number u is an integer from 0 to 4.)

  By comprising in this way, the dispersibility and stability of the positive hole transport agent which has a specific structure can be improved. In addition, the stain resistance and wear resistance of the electrophotographic photosensitive member can be improved.

In constituting the electrophotographic photoreceptor of the present invention, the photosensitive layer is preferably a single-layer type photosensitive layer containing a charge generating agent, a hole transporting agent, and a binder resin in the same layer. .
With this configuration, the present invention can be applied to both positive and negative charge types, and a simple layer configuration can improve productivity.

Further, in constituting the electrophotographic photoreceptor of the present invention, the photosensitive layer comprises a charge generating layer containing a charge generating agent and a charge transporting layer containing a hole transporting agent and a binder resin. It is preferable that
With such a configuration, it is possible to maintain excellent electrical characteristics in a multilayer electrophotographic photoreceptor that is generally said to have a large deterioration in electrical characteristics.

Another aspect of the present invention includes any one of the above-described electrophotographic photosensitive members, a charging unit, an exposing unit, a developing unit, and a transfer unit arranged around the electrophotographic photosensitive member, An image forming apparatus characterized by being a static elimination-less type having no means.
That is, as an electrophotographic photoreceptor using an enamine group-containing hydrazone compound having a specific structure represented by the general formula (1) as a hole transport agent, it is effective in generating fog even in a high temperature and high humidity environment. Can be suppressed.
Furthermore, since such an electrophotographic photosensitive member has excellent electrical characteristics, it is possible to effectively suppress the occurrence of exposure memory even when a static elimination-less type having no static elimination means is employed.
Therefore, it is possible to stably form a high-quality image in which the generation of fog and exposure memory images is suppressed, and the configuration of the image forming apparatus can be simplified.

In constituting the image forming apparatus of the present invention, the charging means is preferably a charging roller.
With this configuration, the overall configuration is simpler than that of the non-contact charging method, and no harmful substances such as ozone are generated, so that an image forming apparatus having excellent environmental characteristics can be obtained.
In addition, the electrophotographic photosensitive member can be stably charged with little dependency on temperature and relative humidity.

[First Embodiment]
The first embodiment of the present invention is an electrophotographic photosensitive member having a photosensitive layer formed directly or via an intermediate layer on a substrate, the photosensitive layer comprising a charge generating agent, a hole transporting agent, And an electron encapsulating resin, wherein the hole transporting agent is an enamine group-containing hydrazone compound represented by the general formula (1).

Hereinafter, as a first embodiment of the present invention, a single layer type electrophotographic photosensitive member will be described as an example.
1. Basic Configuration As shown in FIG. 1A, the basic configuration of the electrophotographic photosensitive member according to the present invention includes a single-layer type electrophotographic photosensitive member 10 on a substrate 12, a charge generating agent, an electron transporting agent. A single photosensitive layer 14 made of an agent, a hole transport agent having a specific structure, and a binder resin is preferably provided.
The reason for this is that the single-layer electrophotographic photoreceptor 10 can be applied to both positive and negative charge types and has a simple layer structure, thereby suppressing film defects when forming the photosensitive layer. This is because productivity can be improved.
Moreover, since there are few interfaces between layers, optical characteristics can be improved.
Further, as illustrated in FIG. 1B, a single-layer type photoreceptor 10 ′ in which an intermediate layer 16 is formed between the photosensitive layer 14 and the substrate 12 can be used.

2. Base As the base 12 illustrated in FIG. 1, various materials having conductivity can be used. For example, metals such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, brass, and plastic materials on which the above-mentioned metals are deposited or laminated , Glass coated with alumite, aluminum iodide, tin oxide, indium oxide and the like.
Further, the shape of the substrate may be any of a sheet shape, a drum shape, or the like according to the structure of the image forming apparatus to be used. The substrate itself has conductivity, or the surface of the substrate has conductivity. If you do. Further, the substrate preferably has a sufficient mechanical strength when used. In the case of a drum shape, the diameter of the substrate is preferably 10 to 60 mm, more preferably 10 to 35 mm from the viewpoint of miniaturization of the apparatus.

In addition, in order to prevent the occurrence of interference fringes, the surface of the support substrate is roughened using methods such as etching, anodizing, wet blasting, sand blasting, rough cutting, and centerless cutting. May be.
Note that when anodization or the like is performed on the substrate, non-conductivity or semiconductor characteristics may be obtained. Even in such a case, the substrate can be used as long as a predetermined effect is obtained.

3. Intermediate Layer Further, as shown in FIG. 1B, an intermediate layer 16 containing a predetermined binder resin may be provided on the substrate 12.
This is because the adhesion between the substrate and the photosensitive layer is improved, and by adding a predetermined fine powder in this intermediate layer, the incident light is scattered to suppress the generation of interference fringes, This is because charge injection from the substrate to the photosensitive layer during non-exposure that causes black spots can be suppressed. The fine powder is not particularly limited as long as it has light scattering properties and dispersibility, and examples thereof include white pigments such as titanium oxide, zinc oxide, zinc white, zinc sulfide, lead white, and lithopone. Inorganic pigments such as alumina, calcium carbonate, barium sulfate and the like, fluorine resin particles, benzoguanamine resin particles, styrene resin particles, and the like can be used.

Moreover, it is preferable to make the film thickness of this intermediate | middle layer into the value within the range of 0.1-50 micrometers. This is because if the intermediate layer is too thick, a residual potential is likely to be generated on the surface of the photoreceptor, which may cause a decrease in electrical characteristics. On the other hand, if the intermediate layer thickness is too thin, the unevenness of the substrate surface cannot be sufficiently relaxed, and the adhesion between the substrate and the photosensitive layer cannot be obtained.
Therefore, the thickness of the intermediate layer is preferably set to a value in the range of 0.1 to 50 μm, and more preferably set to a value in the range of 0.5 to 30 μm.

4). Photosensitive layer (1) Binder resin (1) -1 type The type of binder resin used in the electrophotographic photosensitive member of the present invention is not particularly limited, and examples thereof include polycarbonate resins, polyester resins, and polyresins. Arylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer, chlorinated Polyethylene, polyvinyl chloride, polypropylene, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide, polyurethane, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, etc., silicone resin , Epoxy resin, phenol Fat, urea resins, melamine resins, and other crosslinkable thermosetting resin, epoxy acrylate, urethane - resin such as photocurable resin such as acrylate can be used.

Among the binder resins described above, it is more preferable to use a polycarbonate resin, and it is particularly preferable to use at least one member selected from the group consisting of the polycarbonate resins represented by the general formulas (2) to (4). .
The reason for this is that by using these polycarbonate resins as the binder resin, the dispersibility and stability of the hole transport agent having a specific structure can be improved.
That is, these polycarbonate resins are excellent in compatibility with a hole transporting agent having a specific structure, and thus the hole transporting agent can be more uniformly dispersed in the photosensitive layer. As a result, the excellent hole transport ability can be exhibited more efficiently, and crystallization in the photosensitive layer can be more effectively prevented.

(1) -2 Specific Example Moreover, as polycarbonate resin represented by general formula (2)-(4), polycarbonate resin (Resin-1) represented by following formula (5)-(7), respectively. Is mentioned.

  Moreover, as polycarbonate resin used suitably other than the polycarbonate resin represented by General formula (2)-(4), polycarbonate resin (Resin-4 ~) represented by following formula (8)-(10) is used. 6).

(2) Charge generator (2) -1 type In addition, examples of the charge generator in the present invention include phthalocyanine pigments such as metal-free phthalocyanine and oxotitanyl phthalocyanine, perylene pigments, bisazo pigments, and diketopyrrolopyrrole pigments. , Metal-free naphthalocyanine pigment, metal naphthalocyanine pigment, squaraine pigment, trisazo pigment, indigo pigment, azulenium pigment, cyanine pigment, pyrylium pigment, ansanthrone pigment, triphenylmethane pigment, selenium pigment, toluidine pigment, pyrazoline pigment Conventionally known charge generating agents such as organic photoconductors such as pigments and quinacridone pigments and inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon can be used.

(2) -2 Specific Example More specifically, it is more preferable to use phthalocyanine pigments (CGM-1 to CGM-4) represented by the following formulas (11) to (14).
This is because a photoreceptor having sensitivity in a wavelength region of 600 to 800 nm or more is required when used in a digital optical image forming apparatus such as a laser beam printer or a facsimile provided with a semiconductor laser as a light source. It is.
On the other hand, when used in an analog optical image forming apparatus such as an electrostatic copying machine having a white light source such as a halogen lamp, a photosensitive member having sensitivity in the visible region is required. Perylene pigments and bisazo pigments can be preferably used.

(2) -3 Addition Amount of addition of the charge generator is preferably set to a value in the range of 0.1 to 50 parts by weight with respect to 100 parts by weight of the binder resin described later.
This is because the charge generating agent can efficiently generate charges when the photosensitive member is exposed by setting the amount of the charge generating agent within the above range. That is, when the amount of the charge generating agent added is less than 0.1 parts by weight with respect to 100 parts by weight of the binder resin, the amount of charge generated is insufficient to form an electrostatic latent image on the photoreceptor. This is because there is a case of becoming. On the other hand, when the added amount of the charge generating agent exceeds 50 parts by weight with respect to 100 parts by weight of the binder resin, it may be difficult to uniformly disperse in the coating solution for the photosensitive layer. It is.
Therefore, it is more preferable that the amount of the charge generator added relative to 100 parts by weight of the binder resin is a value within the range of 0.5 to 30 parts by weight.

(3) Hole Transfer Agent (3) -1 Type As the hole transfer agent used in the electrophotographic photoreceptor according to the present invention, the enamine group-containing hydrazone compound represented by the general formula (1) described above is used. It is characterized by that.
The reason for this is that the enamine group-containing hydrazone compound represented by the general formula (1) can be sufficiently dissolved in the coating solution for the photosensitive layer, thus effectively preventing crystallization in the photosensitive layer. be able to. Therefore, the occurrence of fog can be effectively suppressed even in a high temperature and high humidity environment.
Furthermore, the enamine group-containing hydrazone compound represented by the general formula (1) has an excellent hole transporting ability, and thus can improve the electrical characteristics of the electrophotographic photosensitive member. More specifically, it is possible to obtain effects such as suppression of exposure memory and improvement of sensitivity.
That is, since such a hole transport agent has a large number of aryl groups at specific locations, it has a strong tendency not only to have abundant π electrons but also to maintain the molecular structure in a planar shape. Therefore, the movement of charges in the molecule is efficiently performed, and as a result, the electrical characteristics of the electrophotographic photosensitive member can be improved. Furthermore, since R ¹ in the general formula (1) is an alkyl group having 2 or more carbon atoms, it is easy to adjust the polarity of the molecule within a suitable range, which is sufficient for the coating solution for the photosensitive layer. This is because crystallization in the photosensitive layer can be effectively prevented.

(3) -2 Specific Example As specific examples of the enamine group-containing hydrazone compound represented by the general formula (1), compounds represented by the following formulas (15) to (19) (HTM-1 to 5) Is mentioned.

(3) -3 Addition Amount The addition amount of the hole transport agent is preferably set to a value within the range of 1 to 120 parts by weight with respect to 100 parts by weight of the binder resin.
This is because when the amount of the hole transport agent added is less than 1 part by weight, the hole transport ability of the photosensitive layer is extremely lowered, which may adversely affect image characteristics.
Further, when the added amount exceeds 120 parts by weight, there is a problem that dispersibility is lowered and crystallization is easily caused.
Therefore, the amount of the hole transporting agent added is preferably 5 to 100 parts by weight, preferably 10 to 90 parts by weight with respect to 100 parts by weight of the binder resin. Is more preferable.

(4) Electron Transfer Agent (4) -1 Types The electron transfer agent used in the present invention is not particularly limited, and examples thereof include benzoquinone compounds, naphthoquinone compounds, anthraquinone compounds, diphenoquinone compounds, Dinaphthoquinone compounds, naphthalenetetracarboxylic acid diimide compounds, fluorenone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, dinitroanthracene compounds, dinitroacridine compounds, nitroantharaquinone compounds, dinitroanthraquinone compounds A single type of compound or a combination of two or more types may be mentioned.

(4) -2 Specific Example Specific examples of the electron transfer agent include compounds (ETM-1 to 5) represented by the following formulas (20) to (24).

(4) -3 Addition The addition amount of the electron transport agent is preferably set to a value within the range of 1 to 120 parts by weight with respect to 100 parts by weight of the binder resin.
This is because when the amount of the electron transport agent added is less than 1 part by weight, the electron transport ability of the photosensitive layer is extremely lowered, which may adversely affect image characteristics.
Further, when the added amount exceeds 120 parts by weight, there is a problem that dispersibility is lowered and crystallization is easily caused.
Therefore, the addition amount of the electron transfer agent is preferably set to a value within the range of 5 to 100 parts by weight, and preferably within a range of 10 to 90 parts by weight with respect to 100 parts by weight of the binder resin. More preferred.

(5) Additive It is also preferable to add a biphenyl derivative as an additive to the photosensitive layer.
This is because the occurrence of cracks in the contaminated component adhering portion of the electrophotographic photosensitive member can be suppressed by the action of the additive and the like.
That is, when contaminant components adhere to the surface of the electrophotographic photosensitive member and the monomer component elutes to form pores in the photosensitive layer, the additive acts on the pores to cause local stress. This is because the generation of cracks can be suppressed and the occurrence of cracks can be suppressed.

Here, the mechanism of crack generation when contaminants adhere to the surface of the electrophotographic photosensitive member will be described in detail.
First, when a contaminant adheres to the surface of the electrophotographic photosensitive member, a monomer component in the photosensitive layer, in particular, a charge transport agent composed of a hole transport agent and an electron transport agent starts to elute.
Next, it is considered that a hole is formed in the binder resin of the photosensitive layer at the trace of the elution of the charge transfer agent, and a local stress is generated in the vicinity of the hole to generate a crack. In other words, the occurrence of cracks can be regarded as a combination of two phenomena: a phenomenon of monomer component elution and a phenomenon of stress generation near the vacancies.

(5) -1 Specific Example Specific examples of the biphenyl derivative as the additive include compounds (BP-1 to 20) represented by the following formula (25).

(5) -2 Content The content of the above-described additive is preferably set to a value in the range of 2 to 14% by weight with respect to the solid content (100% by weight) of the photosensitive layer.
This is because the occurrence of cracks can be more effectively suppressed by setting the content of the additive to a value within such a range.
That is, when the content of the additive is less than 2% by weight, the stress relaxation action as described above cannot be sufficiently exhibited, and it is difficult to sufficiently prevent the occurrence of cracks. On the other hand, when the content of the additive exceeds 14% by weight, the glass transition point of the photosensitive layer is lowered, and the wear resistance may be lowered. Further, this is because dispersibility in the photosensitive layer is lowered and crystallization is observed.
Therefore, the content of the additive is more preferably set to a value within the range of 3 to 12% by weight, and further preferably set to a value within the range of 4 to 10% by weight.
The solid content of the photosensitive layer means the constituent components of the photosensitive layer excluding the solvent. In the present invention, the total of the charge generating agent, the charge transporting agent, the binder resin, and the additive. It means the amount added.

(6) Thickness Further, it is preferable to set the film thickness of the photosensitive layer to a value in the range of 5.0 to 100 μm.
This is because, when the thickness of the photosensitive layer is less than 5.0 μm, the mechanical strength as an electrophotographic photosensitive member may be insufficient. On the other hand, when the thickness of the photosensitive layer exceeds 100 μm, it may be easy to peel from the substrate or it may be difficult to form it uniformly. Accordingly, the thickness of the photosensitive layer is more preferably set to a value within the range of 10 to 80 μm, and further preferably set to a value within the range of 20 to 40 μm.

5). Production Method The production method of the single-layer electrophotographic photosensitive member is not particularly limited, but can be carried out by the following procedure.
First, a coating solution is prepared by adding a charge generating agent, a charge transporting agent, a binder resin, an additive and the like to a solvent. The coating solution thus obtained is applied onto a conductive substrate (aluminum tube) using a coating method such as a dip coating method, a spray coating method, a bead coating method, a blade coating method, or a roller coating method. Apply.
Then, for example, it is dried with hot air at 100 ° C. for 30 minutes to obtain a single layer type electrophotographic photosensitive member having a photosensitive layer having a predetermined thickness.
In addition, as a solvent for making a dispersion liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; Aromatic hydrocarbons such as benzene, toluene, xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, chlorobenzene; dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane Ethers such as 1,4-dioxane, ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethylformaldehyde, dimethyl Examples include tilformamide and dimethyl sulfoxide. These solvents are used alone or in admixture of two or more. At this time, in order to improve the dispersibility of the charge generating agent and the smoothness of the surface of the photoreceptor layer, a surfactant, a leveling agent and the like may be added.

It is also preferable to form an intermediate layer on the substrate before forming this photosensitive layer.
In forming this intermediate layer, a binder resin and, if necessary, an additive (organic fine powder or inorganic fine powder) together with an appropriate dispersion medium, a known method such as a roll mill, ball mill, attritor, paint shaker, ultrasonic wave A coating solution is prepared by dispersing and mixing using a disperser or the like, and this is applied by a known means such as a blade method, a dipping method, or a spray method, and subjected to heat treatment to form an intermediate layer.
In addition, the additive is in a range where precipitation during production does not become a problem, and various additives (organic fine powder or inorganic fine powder are used for the purpose of preventing the occurrence of interference fringes by causing light scattering. ) Can be added in small amounts.
Next, the obtained coating solution is applied to a support substrate (aluminum base tube) according to a known production method, such as dip coating, spray coating, bead coating, blade coating, roller coating, etc. It can apply | coat using the apply | coating method.
Then, it is preferable to perform the process of drying the coating liquid on a base | substrate at the temperature of 20-200 degreeC for 5 minutes-2 hours.

  In addition, as a solvent for making such a coating liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane. Aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and chlorobenzene; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate Dimethylformaldehyde, dimethylformamide, dimethyl sulfoxide and the like. These solvents are used alone or in admixture of two or more.

6). Multilayer Electrophotographic Photoreceptor In constituting the electrophotographic photoreceptor of the present invention, the photosensitive layer comprises a charge generating layer 24 containing a charge generating agent and a hole transport having a specific structure as shown in FIG. It is also preferable that the layered photosensitive layer 20 comprises a charge transport layer 22 containing an agent and a binder resin.
This is because, by using a hole transport agent having a specific structure as a hole transport agent, it is possible to maintain excellent electrical characteristics even in a multilayer electrophotographic photoreceptor that is generally said to have a large deterioration in electrical characteristics. It is because it can do.
In the laminated electrophotographic photoreceptor 20, a charge generation layer 24 containing a charge generation agent is formed on the substrate 12 by means of vapor deposition or coating, and then a specific structure is formed on the charge generation layer 24. The charge transporting layer 22 can be formed by applying a coating liquid containing a hole transporting agent and a binder resin, and drying the coating liquid.
In contrast to the above-described structure, as shown in FIG. 2B, the charge transport layer 22 may be formed on the substrate 12, and the charge generation layer 24 may be formed thereon. However, since the charge generation layer 24 is much thinner than the charge transport layer 22, for protection, the charge transport layer 22 is formed on the charge generation layer 24 as shown in FIG. It is more preferable to form
It is also preferable to form the intermediate layer 25 on the substrate as in the case of the single layer type photoreceptor.

The charge generation layer forming coating solution and the charge transport layer forming coating solution are, for example, a predetermined component such as a charge generating agent, a charge transporting agent, a binder resin, a dispersion medium, a roll mill, a ball mill, an attritor, a paint. It can be prepared by dispersing and mixing using a shaker, an ultrasonic disperser or the like.
In the laminated photosensitive layer 20, the thickness of the photosensitive layer (charge generation layer and charge transport layer) is not particularly limited, but the charge generation layer is preferably 0.01 to 5 μm, more preferably 0.1 to 0.1 μm. The thickness is 3 μm, and the charge transport layer is preferably 2 to 100 μm, more preferably 5 to 50 μm.

[Second Embodiment]
The second embodiment includes the electrophotographic photosensitive member according to the first embodiment, and a charging unit, an exposing unit, a developing unit, and a transfer unit are arranged around the electrophotographic photosensitive member, and a discharging unit. An image forming apparatus characterized by being a static elimination-less type that does not include
Hereinafter, the contents already described in the first embodiment will be omitted, and the second embodiment will be described focusing on differences from the first embodiment.
The case where a single layer type electrophotographic photosensitive member is used as the electrophotographic photosensitive member will be described as an example.

The basic configuration and operation of the image forming apparatus according to the present invention will be described with reference to FIG.
First, the electrophotographic photosensitive member 111 of the image forming apparatus 100 is rotated at a predetermined process speed (circumferential speed) in the direction indicated by the arrow A, and then the surface is charged to a predetermined potential by the charging unit 112. As the charging means 112, a charging roller is used.
Next, the exposure unit 113 exposes the surface of the electrophotographic photosensitive member 111 through a reflection mirror or the like while being light-modulated according to image information. By this exposure, an electrostatic latent image is formed on the surface of the electrophotographic photosensitive member 111.
Next, based on the electrostatic latent image, latent image development is performed by the developing unit 114. The developing means 114 stores toner, and the toner adheres corresponding to the electrostatic latent image on the surface of the electrophotographic photosensitive member 111 to form a toner image.
Further, the recording paper 120 is conveyed to the lower part of the photoconductor along a predetermined transfer conveyance path. At this time, the toner image can be transferred onto the recording material 120 by applying a predetermined transfer bias between the electrophotographic photoreceptor 111 and the transfer means 115.

Next, the recording paper 120 to which the toner image has been transferred is separated from the surface of the electrophotographic photosensitive member 111 by a separating means (not shown) and conveyed to a fixing device by a conveying belt. Next, the toner image is fixed on the surface by being heated and pressed by the fixing device, and then discharged to the outside of the image forming apparatus 100 by a discharge roller.
On the other hand, the electrophotographic photosensitive member 111 after the toner image is transferred continues to rotate, and residual toner (adhered matter) that has not been transferred to the recording paper 120 at the time of transfer is removed from the surface of the electrophotographic photosensitive member 111 by the cleaning device 117. The

That is, when the electrophotographic photoreceptor of the present invention is used as the electrophotographic photoreceptor 111, an enamine group-containing hydrazone compound having a specific structure represented by the general formula (1) is used as the hole transport agent. Since it is an electrophotographic photoreceptor, the occurrence of fog can be effectively suppressed even in a high temperature and high humidity environment.
Furthermore, since such an electrophotographic photosensitive member has excellent electrical characteristics, it is possible to effectively suppress the occurrence of exposure memory even when a static elimination-less type having no static elimination means is employed.
Therefore, it is possible to stably form a high-quality image in which the generation of fog and exposure memory images is suppressed, and the configuration of the image forming apparatus can be simplified.

In constituting the image forming apparatus of the present invention, the charging means is preferably a charging roller.
This is because the overall configuration is simpler than that of the non-contact charging method, and no harmful substances such as ozone are generated, so that an image forming apparatus having excellent environmental characteristics can be obtained.
Further, it is less dependent on temperature and relative humidity, and can stably charge the electrophotographic photosensitive member.
That is, in the non-contact type charging means, since the photosensitive member is charged through air by discharging, charging may become unstable due to the influence of the temperature and humidity of the air. On the other hand, a contact-type charging means does not cause such a problem and can stably charge the photosensitive member.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these description content.

[Example 1]
1. Preparation of multilayer electrophotographic photoreceptor (1) Preparation of intermediate layer Using bead mill, after surface treatment with titanium oxide (SMT-02, alumina and silica), the number average of surface treatment with methylhydrogenpolysiloxane while wet dispersion 200 parts by weight with a primary particle size of 10 nm (manufactured by Teika), 100 parts by weight of quaternary copolymerized polyamide resin CM8000 (manufactured by Toray Industries, Inc.), 1000 parts by weight of methanol, and 200 parts by weight of butanol, The mixture was dispersed and dispersed for 5 hours, and further filtered through a 5 micron filter to prepare an intermediate layer coating solution.
Next, one end of an aluminum substrate (supporting substrate) having a diameter of 30 mm and a length of 238.5 mm was placed on the upper side, and the resultant was applied by being immersed in the obtained intermediate layer coating solution at a rate of 5 mm / sec. Then, the hardening process was performed on 130 degreeC and the conditions for 30 minutes, and the intermediate | middle layer with a film thickness of 2 micrometers was formed.

(2) Formation of charge generation layer Next, using a bead mill, 100 parts by weight of a crystal of titanyl phthalocyanine (CGM-2) represented by the formula (12) as a charge generation agent and polyvinyl butyral resin (electrical as a binder resin) Chemical Co., Ltd. Denkabutyral 6000EP) 100 parts by weight, propylene glycol monomethyl ether 4000 parts by weight and tetrahydrofuran 4000 parts by weight were mixed and dispersed for 2 hours to obtain a coating solution for the charge generation layer. Next, the obtained coating solution is filtered through a 3 micron filter, and then applied onto the above-described intermediate layer by a dip coating method and dried at 50 ° C. for 5 minutes to form a charge generation layer having a thickness of 0.3 μm. Formed.

Moreover, the manufacturing method of the titanyl phthalocyanine crystal | crystallization used as a charge generation agent is as follows.
First, 22 g of o-phthalonitrile, 25 g of titanium tetrabutoxide, 2.28 g of urea, and 300 g of quinoline were added to a flask purged with argon, and the temperature was raised to 150 ° C. while stirring.
Next, the temperature of the system was raised to 215 ° C. while distilling off the vapor generated from the reaction system, and the mixture was further stirred for 2 hours while maintaining this temperature.
Then, after the reaction is completed, when the reaction mixture is cooled to 150 ° C., the reaction mixture is taken out of the flask, filtered through a glass filter, and the resulting solid is washed successively with N, N-dimethylformamide and methanol and then vacuum-dried. 24 g of a blue-violet solid was obtained.

(Pigmentation pretreatment)
10 g of the blue-purple solid obtained in the production of the above-mentioned titanyl phthalocyanine compound was added to 100 ml of N, N-dimethylformamide and heated to 130 ° C. with stirring for 2 hours.
Next, the heating was stopped when 2 hours passed, and further the stirring was stopped when the temperature was cooled to 23 ± 1 ° C. In this state, the liquid was allowed to stand for 12 hours for stabilization treatment. The stabilized supernatant was filtered off with a glass filter, and the resulting solid was washed with methanol and then vacuum dried to obtain 9.83 g of a crude crystal of a titanyl phthalocyanine compound.

(Pigmentation treatment)
5 g of crude crystals of titanyl phthalocyanine obtained by the above-mentioned pigmentation pretreatment were added to 100 ml of concentrated sulfuric acid and dissolved.
Next, this solution was dropped into water under ice cooling, stirred at room temperature for 15 minutes, and further allowed to stand at 23 ± 1 ° C. for 30 minutes to recrystallize and separate from the supernatant.
Next, the supernatant is filtered off with a glass filter, and the resulting solid is washed with water until the washing solution becomes neutral. Then, without drying, it is dispersed in 200 ml of chlorobenzene and heated to 50 ° C. And stirred for 10 hours. After filtering the supernatant with a glass filter, the obtained crystals were vacuum-dried at 50 ° C. for 5 hours to obtain crystals of unsubstituted titanyl phthalocyanine (CGM-2) represented by the formula (12) (blue powder) ) 4.1 g was obtained.
Further, using the obtained titanyl phthalocyanine crystal, CuKα characteristic X-ray diffraction spectrum measurement and differential scanning calorimetry were performed immediately after production and after immersion in 1,3-dioxolane or tetrahydrofuran for 7 days, respectively. As a result, in the CuKα characteristic X-ray diffraction spectrum, it was confirmed that no peaks were generated at Bragg angles 2θ ± 0.2 ° = 7.4 ° and 26.2 ° in any case. In the differential scanning calorimetry, in any case, when the temperature was raised to 400 ° C., one peak was observed at 296 ° C. in addition to the peak near 90 ° C. accompanying the vaporization of the adsorbed water.

(3) Formation of charge transport layer Next, in the ultrasonic disperser, 70 parts by weight of an enamine group-containing hydrazone compound (HTM-1) represented by the formula (15) as a hole transport agent and the formula ( 25) 5 parts by weight of a biphenyl derivative represented as BP-20 in the binder resin, 100 parts by weight of a polycarbonate resin (Resin-1) represented by the formula (5) having a viscosity average molecular weight of 30,500 as a binder resin, After containing 600 parts by weight of tetrahydrofuran, it was mixed and dissolved for 10 minutes to obtain a coating solution for a charge transport layer.
Next, the obtained charge transport layer coating solution is applied onto the charge generation layer in the same manner as the charge generation layer coating solution and dried at 130 ° C. for 30 minutes to form a 20 μm-thick charge transport layer. Type electrophotographic photosensitive member was produced.

2. Evaluation (1) Evaluation of sensitivity In addition, the sensitivity of the obtained multilayer electrophotographic photosensitive member was evaluated.
That is, the developing means is removed from the imaging unit in the printer (Okidata MicroLine-22 manufactured by Oki Data Co., Ltd.) that employs the negatively charged reversal development process, and a potential measuring device is attached thereto to create an imaging unit for measuring potential. did. Such a potential measuring device has a configuration in which a potential measuring probe is arranged with respect to the developing position of the imaging unit. Further, such a potential measuring probe was disposed with respect to the center in the axial direction of the electrophotographic photosensitive member, and the distance between the potential measuring probe and the surface of the electrophotographic photosensitive member was 5 mm.
Next, the obtained multilayer electrophotographic photosensitive member is mounted on the above-described potential measurement imaging unit, is negatively charged, and becomes a solid black image in a room temperature environment (temperature 20 ° C., relative humidity 50%). Corresponding exposure was performed, and the potential of the exposed portion was measured to obtain sensitivity (V). The obtained results are shown in Table 1. In addition, although the measured value of the obtained charging potential (V) and sensitivity (V) was a negative value, in Table 1, the absolute value (positive value) is described.

(2) Evaluation of exposure memory potential Moreover, the exposure memory potential in the obtained multilayer electrophotographic photosensitive member was evaluated.
That is, the obtained multilayer electrophotographic photosensitive member is mounted on the above-described potential measurement imaging unit, and a solid black image is obtained with respect to the first round (95 mm long) electrophotographic photosensitive member in the same environment. The exposure corresponding to 65 mm was performed (exposure portion), and the remaining 30 mm was not exposed (non-exposure portion). Next, the entire electrophotographic photoreceptor on the second round was not exposed. Next, the surface potential V ₀ b (V) in the second turn of the portion corresponding to the exposed portion of the first turn and the surface potential V ₀ (V) in the second turn of the portion corresponding to the non-exposed portion of the first turn. If the measured absolute value │V ₀ -V ₀ b│ the potential difference (V) was calculated, and the exposure memory potential (V). The obtained results are shown in Table 1.

(3) Evaluation of image fog Moreover, FD value was evaluated using the obtained multilayer electrophotographic photosensitive member.
That is, the obtained multilayer electrophotographic photosensitive member was mounted on a printer (MicroLine-22 manufactured by Oki Data Co., Ltd.), and a blank paper image was formed under a high temperature and high humidity environment (temperature 35 ° C., relative humidity 85%). Then, density FD ₁ value in the obtained blank image - from the density FD ₀ value in the blank image not yet output () (-) draw, was evaluated as FD value. The obtained results are shown in Table 1.

[Examples 2 to 14]
In Examples 2 to 14, the charge generating agent, the hole transporting agent, and the binder resin in the charge transporting layer used were laminated in the same manner as in Example 1 except that they were changed as shown in Table 1. Type electrophotographic photoreceptors were prepared and evaluated. The obtained results are shown in Table 1.

[Comparative Example 1]
Further, in Comparative Example 1, the laminated electrophotographic photosensitive member was the same as in Example 1 except that the hole transporting agent used was an enamine group-containing hydrazone compound (HTM-6) represented by the following formula (26). A body was created and evaluated. The obtained results are shown in Table 1.

[Comparative Example 2]
In Comparative Example 2, the laminated electrophotographic photosensitive member was the same as in Example 1 except that the hole transporting agent used was an enamine group-containing hydrazone compound (HTM-7) represented by the following formula (27). A body was created and evaluated. The obtained results are shown in Table 1.

[Comparative Example 3]
In Comparative Example 3, a multilayer electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the hole transporting agent used was a hydrazone compound (HTM-8) represented by the following formula (28). And evaluated. The obtained results are shown in Table 1.

[Example 15]
1. Production of Single Layer Type Electrophotographic Photoreceptor (1) Formation of Intermediate Layer An intermediate layer was formed on the substrate in the same manner as in Example 1.

(2) Formation of photosensitive layer Next, 3 parts by weight of x-type metal-free phthalocyanine (CGM-1) represented by the formula (11) as a charge generator and formula (15) as a hole transport agent in an ultrasonic dispersing machine In the formula (25), 50 parts by weight of the enamine group-containing hydrazone compound (HTM-1) represented by the formula (40), 40 parts by weight of the compound (ETM-1) represented by the formula (20) as the electron transporting agent, and additives. 3 parts by weight of a biphenyl derivative represented as BP-3, 100 parts by weight of a polycarbonate resin (Resin-1) represented by the formula (5) having a viscosity average molecular weight of 30,500 as a binder resin, and 600 parts by weight of tetrahydrofuran as a solvent After accommodating the part, it was mixed and dissolved for 10 minutes to obtain a photosensitive layer coating solution.
Next, the obtained photosensitive layer coating solution is applied on the intermediate layer by dip coating and dried with hot air at 130 ° C. for 40 minutes to form a photosensitive layer having a film thickness of 25 μm to produce a single-layer electrophotographic photosensitive member. did.

2. Evaluation (1) Evaluation of sensitivity In addition, the sensitivity of the obtained single-layer type electrophotographic photosensitive member was evaluated.
That is, instead of the printer used in Example 1 (MicroLine-22 manufactured by Oki Data Co., Ltd.), DP-560 manufactured by Kyocera Mita Co., Ltd. was used to create an imaging unit for measuring the potential. A single layer type electrophotographic photosensitive member was mounted. In addition, the static elimination lamp was removed, the rotational speed of the photosensitive drum was set to 60 mm / sec, and the amount of light during exposure was set to 1.0 μJ / cm ² . Other than that, it evaluated similarly to evaluation of the sensitivity in Example 1. FIG. The obtained results are shown in Table 2.

(2) Evaluation of exposure memory potential Moreover, the exposure memory potential in the obtained single layer type electrophotographic photosensitive member was evaluated.
That is, evaluation was performed in the same manner as the evaluation of the exposure memory potential in Example 1 except that the obtained single-layer electrophotographic photosensitive member was mounted on the above-described potential measurement imaging unit. The obtained results are shown in Table 2.

(3) Evaluation of image fog Moreover, FD value was evaluated using the obtained single layer type electrophotographic photosensitive member.
That is, the evaluation was the same as the image fogging evaluation in Example 1 except that the obtained single-layer electrophotographic photosensitive member was mounted on a printer (DP-560 manufactured by Kyocera Mita Co., Ltd.). The obtained results are shown in Table 2.

[Examples 16 to 28]
Further, in Examples 16 to 28, the charge generating agent, hole transporting agent, electron transporting agent, and binder resin used were changed as shown in Table 2, respectively. A layered electrophotographic photoreceptor was prepared and evaluated. The obtained results are shown in Table 2.

According to the electrophotographic photoreceptor of the present invention and the image forming apparatus using the same, the hole transport agent having a specific structure is contained in the photosensitive layer of the electrophotographic photoreceptor so that the hole transport agent can be converted into the photosensitive layer. It can be sufficiently dissolved in the coating liquid for use to effectively prevent crystallization, and can fully exhibit its excellent hole transport ability.
As a result, the electrical characteristics of the electrophotographic photosensitive member are improved, and the generation of fog can be effectively suppressed even in a high temperature and high humidity environment.
Therefore, the electrophotographic photosensitive member of the present invention and the image forming apparatus using the same are expected to contribute to high image quality and high speed of the image forming apparatus.

It is a figure provided in order to demonstrate the structure of the single layer type electrophotographic photosensitive member concerning this invention. It is a figure provided in order to demonstrate the structure of the laminated electrophotographic photosensitive member concerning this invention. 1 is a diagram for explaining an image forming apparatus according to the present invention.

Explanation of symbols

10: Single layer type photoreceptor, 12: Substrate, 14: Photosensitive layer, 16: Intermediate layer, 20: Multilayer type photoreceptor, 22: Charge transport layer, 24: Charge generation layer, 25: Intermediate layer, 100: Image formation Apparatus: 111: electrophotographic photosensitive member, 112: charging means, 113: exposure means, 114: developing means, 115: transfer means, 117: cleaning device, 120: recording paper

Claims (6)

An electrophotographic photosensitive member having a photosensitive layer formed directly or via an intermediate layer on a substrate,
The photosensitive layer contains a charge generator, a hole transport agent, and a binder resin, and the hole transport agent is an enamine group-containing hydrazone compound represented by the following general formula (1). An electrophotographic photoreceptor characterized by the above.

(In General Formula (1), R ¹ is an alkyl group having 2 or more carbon atoms, and a plurality of Ra to Rf are each independently a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or 6 to 30 carbon atoms. Substituted or unsubstituted aryl group, substituted or unsubstituted alkenyl group having 6 to 30 carbon atoms, or —OR ² (R ² is an alkyl group having 1 to 10 carbon atoms, a perfluoroalkyl group, or 6 to 6 carbon atoms). 30 is an aryl group), and the repeating numbers m and n are integers of 0 to 4, and the repeating numbers o to r are integers of 0 to 5.) The electrophotographic photosensitive member according to claim 1, wherein the binder resin is at least one selected from the group consisting of polycarbonate resins represented by the following general formulas (2) to (4).

(In General Formula (2), a plurality of substituents Rg are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. The number s is an integer from 0 to 4.)

(In General Formula (3), the plurality of substituents Rh are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. The number t is an integer from 0 to 4.)

(In the general formula (4), the plurality of substituents Ri are a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. The number u is an integer from 0 to 4.)   3. The electron according to claim 1, wherein the photosensitive layer is a single-layer type photosensitive layer including the charge generating agent, the hole transport agent, and a binder resin in the same layer. Photoconductor.   The photosensitive layer is a multilayer photosensitive layer comprising a charge generation layer containing the charge generation agent and a charge transport layer containing the hole transport agent and the binder resin. Or the electrophotographic photosensitive member according to 2.   The electrophotographic photosensitive member according to any one of claims 1 to 4 is provided, a charging unit, an exposing unit, a developing unit, a transfer unit are arranged around the electrophotographic photosensitive member, and a static eliminating unit is provided. An image forming apparatus characterized by being a static elimination-less type that does not have.   The image forming apparatus according to claim 5, wherein the charging unit is a charging roller.

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