JP2018004747A - Electrophotographic photoreceptor, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that reduces the occurrence of transfer memory.SOLUTION: An electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transport agent, an electron transport agent, and a binder resin. The photosensitive layer is a single-layer photosensitive layer. The hole transport agent contains two or more compounds. One of the two or more compounds is a diamine derivative represented by the general formula (1). The maximum value of the absolute value of a difference in ionization potential of the hole transport agent is 0.20 eV or more.SELECTED DRAWING: None

Description

  The present invention relates to an electrophotographic photoreceptor, an image forming apparatus, and a process cartridge.

  The electrophotographic photosensitive member is used in an electrophotographic image forming apparatus. As the electrophotographic photosensitive member, for example, a single layer type electrophotographic photosensitive member is used. The electrophotographic photoreceptor includes a photosensitive layer. The single layer type electrophotographic photosensitive member includes a single layer type photosensitive layer having a charge generation function and a charge transport function as a photosensitive layer.

  The photosensitive layer provided in the electrophotographic photoreceptor described in Patent Document 1 contains, for example, a compound represented by the following chemical formula (HTM-2).

JP 2006-008670 A

  However, the electrophotographic photoreceptor described in Patent Document 1 cannot sufficiently suppress the generation of transfer memory.

  The present invention has been made in view of the above problems, and an object thereof is to provide an electrophotographic photosensitive member that suppresses the generation of a transfer memory. Another object of the present invention is to provide an image forming apparatus and a process cartridge that suppress the occurrence of an image defect due to the occurrence of a transfer memory.

  The electrophotographic photosensitive member of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transport agent, an electron transport agent, and a binder resin. The photosensitive layer is a single-layer type photosensitive layer. The hole transport agent includes two or more kinds of compounds. One of the two or more types of the compounds is a diamine derivative represented by the general formula (1). The maximum absolute value of the difference in ionization potential of the hole transport agent is 0.20 eV or more.

In the general formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ are each independently a hydrogen atom, a halogen atom, An alkyl group having 1 to 6 carbon atoms which may have a substituent, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, or the number of carbon atoms which may have a substituent Represents an aryl group of 6 or more and 14 or less. m represents an integer of 1 to 3. n represents an integer of 0 or more and 2 or less.

  The image forming apparatus of the present invention includes an image carrier, a charging unit, an exposure unit, a developing unit, and a transfer unit. The charging unit charges the surface of the image carrier. The exposure unit exposes the charged surface of the image carrier to form an electrostatic latent image. The developing unit develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the surface of the image carrier to the transfer body. The image carrier is the above-described electrophotographic photosensitive member. A charging polarity of the charging unit is positive. The charging unit applies a DC voltage while contacting the surface of the image carrier to charge the surface of the image carrier.

  The process cartridge of the present invention includes the above-described electrophotographic photosensitive member.

  According to the electrophotographic photosensitive member of the present invention, generation of a transfer memory can be suppressed. Further, according to the image forming apparatus and the process cartridge of the present invention, it is possible to suppress image defects caused by the generation of the transfer memory.

(A), (b) and (c) are schematic sectional views showing an example of the electrophotographic photosensitive member according to the first embodiment of the present invention. It is a figure which shows the structure of the image forming apparatus which concerns on 2nd embodiment of this invention. It is a figure which shows the image which the image ghost generate | occur | produced. It is a figure which shows the image for evaluation.

  Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, about the location where description overlaps, although description may be abbreviate | omitted suitably, the summary of invention is not limited.

  Hereinafter, a compound and its derivatives may be generically named by adding “system” after the compound name. In addition, when “polymer” is added after the compound name to indicate the polymer name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

  Hereinafter, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, and An aryl group having 6 to 14 carbon atoms has the following meaning unless otherwise specified.

  As a halogen atom, a fluorine atom, a chlorine atom, or a bromine atom is mentioned, for example.

  The alkyl group having 1 to 6 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, A neopentyl group or a hexyl group is mentioned.

  The alkyl group having 1 to 3 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

  The alkoxy group having 1 to 6 carbon atoms is linear or branched and unsubstituted. Examples of the alkoxy group having 1 to 6 carbon atoms include: Methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, s-butoxy group, t-butoxy group, pentyloxy group, isopentyloxy group, neopentyloxy group, or hexyloxy group It is done.

  The alkoxy group having 1 to 3 carbon atoms is linear or branched and unsubstituted. Examples of the alkoxy group having 1 to 3 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, and an isopropoxy group.

  Examples of the aryl group having 6 to 14 carbon atoms include an unsubstituted aromatic monocyclic hydrocarbon group having 6 to 14 carbon atoms and an unsubstituted aromatic condensed bicyclic carbon group having 6 to 14 carbon atoms. A hydrogen group or an unsubstituted aromatic condensed tricyclic hydrocarbon group having 6 to 14 carbon atoms. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group.

<First embodiment: electrophotographic photoreceptor>
The first embodiment relates to an electrophotographic photoreceptor (hereinafter sometimes referred to as a photoreceptor). Hereinafter, the structure of the photoreceptor will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an example of a photoreceptor 1 according to this embodiment.

  As shown in FIG. 1A, the photoreceptor 1 includes a conductive substrate 2 and a single-layer type photosensitive layer 3 c as the photosensitive layer 3. The single-layer type photosensitive layer 3c is a single layer. As shown in FIG. 1B, the photoreceptor 1 may include a conductive substrate 2, a single-layer type photosensitive layer 3 c, and an intermediate layer (undercoat layer) 4. The intermediate layer 4 is provided between the conductive substrate 2 and the single-layer type photosensitive layer 3c. Moreover, as shown in FIG.1 (c), the protective layer 5 may be provided on the single layer type photosensitive layer 3c.

  The thickness of the single-layer type photosensitive layer 3c is not particularly limited as long as the function as a single-layer type photosensitive layer can be sufficiently expressed. The thickness of the single-layer type photosensitive layer 3c is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

  The photoreceptor 1 according to the first embodiment includes two or more compounds as a hole transport agent. One of the two or more compounds is a diamine derivative represented by the general formula (1) (hereinafter sometimes referred to as diamine derivative (1)). The maximum absolute value of the difference in ionization potential of the hole transport agent is 0.20 eV or more. Since the photoreceptor 1 according to the first embodiment has such a configuration, generation of a transfer memory is suppressed. The reason is presumed as follows.

For convenience, the transfer memory will be described first. In electrophotographic image formation, for example, an image forming process including the following steps 1) to 5) is performed. Here, an image forming apparatus having a reversal development method and a positive charging polarity will be described as an example.
1) a charging step for charging the surface of the photoreceptor;
2) an exposure process for forming an electrostatic latent image on the surface of the photoreceptor;
3) a developing step of developing the electrostatic latent image as a toner image;
4) a transfer step of transferring the formed toner image from the photoreceptor to the recording medium; and 5) a step of fixing the toner image transferred to the recording medium.

  However, in such an image forming process, since the photosensitive member is rotated and used, a transfer memory due to the transfer process may occur. Specifically, it is as follows. In the charging step, the surface of the photoreceptor is uniformly charged to a constant positive potential. Subsequently, through an exposure process and a development process, in the transfer process, a transfer bias having a polarity opposite to that of charging (negative polarity) is applied to the photoconductor via the recording medium. Due to the influence of the applied transfer bias, the potential of the non-exposed area (non-image area) on the surface of the photoconductor may be greatly lowered, and the lowered state may be maintained. Under the influence of this potential drop, the non-exposed area is not easily charged to a desired positive potential in the next charging step. On the other hand, even when the transfer bias is applied, the potential of the exposure region (image region) is difficult to be applied directly to the surface of the photoreceptor and is not easily lowered because the toner adheres to the exposure region. For this reason, the exposure area is easily charged to a desired positive potential in the charging process of the next circumference. As a result, the charged potential differs between the exposed area and the non-exposed area, and it may be difficult to uniformly charge the surface of the image carrier to a constant positive potential. A phenomenon in which the charging ability in the non-exposed area is lowered and the potential difference is generated by dragging the influence of the transfer in the image forming process on the front periphery of the photoreceptor is called a transfer memory.

  As already described, the photoreceptor 1 according to the first embodiment includes two or more compounds as a hole transport agent. One of the two or more compounds is the diamine derivative (1). The maximum absolute value of the difference in ionization potential of the hole transport agent is 0.20 eV or more. Since the photoreceptor 1 according to the first embodiment has such a configuration, the residual charge in the non-exposed area and the residual charge in the exposed area in the photosensitive layer tend to be uniform. Therefore, it is considered that the photoreceptor 1 according to the first embodiment suppresses the generation of the transfer memory. In the above description, an image forming apparatus that employs the direct transfer method is taken as an example. Similarly, in the image forming apparatus that employs the intermediate transfer method, the photoreceptor 1 according to the first embodiment can suppress the generation of the transfer memory.

  The structure of the photoreceptor 1 has been described above with reference to FIG.

  The photosensitive layer contains a charge generating agent, a hole transporting agent, a binder resin, and an electron transporting agent. The photosensitive layer may further contain an additive. Hereinafter, a conductive substrate, an electron transport agent, a hole transport agent, a charge generating agent, a binder resin, an additive, and an intermediate layer will be described as elements of the photoreceptor. In addition, a method for manufacturing the photoreceptor will be described.

[1. Conductive substrate]
The conductive substrate is not particularly limited as long as it can be used as the conductive substrate of the photoreceptor. The conductive substrate may be formed of a material having at least a surface portion having conductivity. Examples of the conductive substrate include a conductive substrate formed of a conductive material. Another example of the conductive substrate is a conductive substrate coated with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, and indium. These materials having conductivity may be used alone or in combination of two or more. Examples of the combination of two or more include alloys (more specifically, aluminum alloy, stainless steel, brass, etc.). Among these materials having conductivity, aluminum or an aluminum alloy is preferable because charge transfer from the photosensitive layer to the conductive substrate is good.

  The shape of the conductive substrate is appropriately selected according to the structure of the image forming apparatus. Examples of the shape of the conductive substrate include a sheet shape or a drum shape. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

[2. Electron transport agent]
Examples of the electron transfer agent include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, Examples include dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, or dibromomaleic anhydride. Examples of quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds. These electron transfer agents may be used alone or in combination of two or more.

  Of these electron transfer agents, compounds represented by general formula (HTM1), general formula (HTM2), or general formula (HTM5) are preferable.

In General Formula (ETM1), R ¹ and R ² each independently represents an alkyl group having 1 to 6 carbon atoms, and preferably represents a 2-methyl-2-butyl group.

In General Formula (ETM2), R ³ represents an alkoxy group having 1 to 3 carbon atoms which may have an aryl group having 6 to 14 carbon atoms, and preferably represents a phenylmethoxy group.

In General Formula (ETM5), R ⁴ and R ⁵ each independently represents an aryl group having 6 to 14 carbon atoms, which may have one or more alkyl groups having 1 to 3 carbon atoms. Represents an ethylmethylphenyl group.

  Examples of the compound represented by the general formula (ETM1) include a compound represented by the chemical formula (ETM-1) (hereinafter sometimes referred to as an electron transport agent (ETM-1)).

  Examples of the compound represented by the general formula (ETM2) include a compound represented by the chemical formula (ETM-2) (hereinafter sometimes referred to as an electron transport agent (ETM-2)).

  Examples of the compound represented by the general formula (ETM5) include a compound represented by the chemical formula (ETM-5) (hereinafter sometimes referred to as an electron transport agent (ETM-5)).

  The content of the electron transfer agent is preferably 10 parts by mass or more and 200 parts by mass or less, and more preferably 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the photosensitive layer. Preferably, it is 10 parts by mass or more and 75 parts by mass or less.

[3. Hole transport agent]
The hole transport agent contains two or more compounds. One of the two or more compounds is the diamine derivative (1). The diamine derivative (1) is represented by the general formula (1).

In general formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, a halogen atom, or a substituent. An alkyl group having 1 to 6 carbon atoms which may have a group, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, or 6 carbon atoms which may have a substituent Represents an aryl group of 14 or less. m represents an integer of 1 to 3. n represents an integer of 0 or more and 2 or less.

In general formula (1), the alkyl group having 1 to 6 carbon atoms represented by R ^{1 to} R ¹⁰ is preferably an alkyl group having 1 to 3 carbon atoms, and is a methyl group or an ethyl group. Is more preferable. Examples of the substitution position of the alkyl group having 1 to 6 carbon atoms include the ortho position (o position), meta position (m position), and para position (p position) of the benzene ring with respect to the bond with the nitrogen atom. The ortho position or the para position is preferred. The alkyl group having 1 to 6 carbon atoms may have a substituent. Examples of such a substituent include a halogen atom, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms. The number of substituents is not particularly limited, but is preferably 3 or less.

In general formula (1), the alkoxy group having 1 to 6 carbon atoms represented by R ^{1 to} R ¹⁰ may have a substituent. Examples of such a substituent include a halogen atom, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms. The number of substituents is not particularly limited, but is preferably 3 or less.

In General Formula (1), the aryl group having 6 to 14 carbon atoms represented by R ^{1 to} R ¹⁰ may have a substituent. Examples of such a substituent include a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms. The number of substituents is not particularly limited, but is preferably 3 or less.

  Specific examples of the diamine derivative include compounds represented by chemical formula (HTM1-1), chemical formula (HTM1-2), or chemical formula (HTM1-3) (hereinafter referred to as hole transporting agent (HTM1-1) and hole, respectively). And a transport agent (HTM1-2) and a hole transport agent (HTM1-3)).

<Method for producing diamine derivative (1)>
The diamine derivative (1) is produced, for example, by a reaction represented by the following reaction formulas (R-1) to (R-10) or a method analogous thereto. In addition to these reactions, appropriate steps may be included as necessary. Hereinafter, the reactions represented by the reaction formulas (R-1) to (R-10) may be referred to as reactions (R-1) to (R-10), respectively.

<Synthesis of Compound 7>
First, compound 7 is synthesized as a raw material used for the synthesis of diamine derivative (1). Compound 7 is synthesized according to reactions (R-1) to (R-4).

In the reaction formulas (R-1) to (R-4), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and n are R ¹ , R ² , R ³ , Synonymous with R ⁴ , R ⁵ , and n. X represents a halogen atom.

[Reaction (R-1)]
In reaction (R-1), compound 2-1 (1 equivalent) is reacted with triethyl phosphite (1 equivalent) to give compound 3-1 (1 equivalent).

  In reaction (R-1), it is preferable to add 1 to 2.5 mol of triethyl phosphite to 1 mol of compound 2-1. When the number of moles of triethyl phosphite is 1 mol or more and 2.5 mol or less with respect to 1 mol of compound 2-1, the yield of compound 3-1 is unlikely to decrease and compound 3-1 is easily purified. .

  The reaction temperature of reaction (R-1) is preferably 160 ° C. or higher and 200 ° C. or lower, and the reaction time is preferably 2 hours or longer and 10 hours or shorter.

[Reaction (R-2)]
Compound 3-1 (1 equivalent) and compound 4 (1 equivalent) are reacted to obtain compound 5 (1 equivalent). Reaction (R-2) is a Wittig reaction.

  In the reaction (R-2), it is preferable to add 1 mol or more and 10 mol or less of compound 4 with respect to 1 mol of compound 3-1. When the amount is 1 mol or more and 10 mol or less with respect to 1 mol of the compound 3-1, the yield of the compound 5 is hardly lowered and the compound 5 is easily purified.

  Reaction (R-2) may be performed in the presence of a base. Examples of the base include sodium alkoxide (more specifically, sodium methoxide or sodium ethoxide), metal hydride (more specifically, sodium hydride or potassium hydride), or metal salt (more Specific examples thereof include n-butyl lithium. These bases may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the base added is preferably 1 mol or more and 2 mol or less with respect to 1 mol of the compound 3-1. When the addition amount of the base is 1 mol or more and 2 mol or less with respect to 1 mol of the compound 3-1, the reactivity is hardly lowered and the reaction is easily controlled.

  Reaction (R-2) may be performed in a solvent. Examples of the solvent include ethers (more specifically, tetrahydrofuran, diethyl ether, dioxane, etc.), halogenated hydrocarbons (more specifically, methylene chloride, chloroform, dichloroethane, etc.), or aromatic carbonization. Hydrogen (more specifically, benzene, toluene, etc.) is mentioned.

  The reaction temperature of the reaction (R-2) is preferably 0 ° C. or more and 50 ° C. or less, and the reaction time is preferably 2 hours or more and 24 hours or less.

[Reaction (R-3)]
In reaction (R-3), compound 2-2 (1 equivalent) is reacted with triethyl phosphite (1 equivalent) to give compound 3-2 (1 equivalent).

  In the reaction (R-3), it is preferable to add 1 mol to 2.5 mol of triethyl phosphite with respect to 1 mol of the compound 2-2. When the number of moles of triethyl phosphite is 1 mole or more and 2.5 moles or less with respect to 1 mole of compound 2-2, the yield of compound 3-2 is difficult to decrease, and the number of moles of compound 2-2 is reduced. On the other hand, when the number of moles of triethyl phosphite is too large, the compound 3-2 is easily purified.

  The reaction temperature of the reaction (R-3) is preferably from 160 ° C. to 200 ° C., and the reaction time is preferably from 2 hours to 10 hours.

[Reaction (R-4)]
In reaction (R-4), compound 3-2 (1 equivalent) is reacted with compound 5 (1 equivalent) to give compound 7 (1 equivalent). Reaction (R-4) is a Wittig reaction.

  In reaction (R-4), it is preferable to add 1 mol to 2.5 mol of compound 5 with respect to 1 mol of compound 3-2. When the number of moles of compound 5 is 1 mole or more and 2.5 moles or less with respect to 1 mole of compound 3-2, the yield of compound 7 is unlikely to decrease and compound 7 is easily purified.

  Reaction (R-4) may be performed in the presence of a base. The base is the same as, for example, the base used in the reaction (R-2). These bases may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the base added is preferably 1 mol or more and 2 mol or less with respect to 1 mol of the compound 3-2. When the addition amount of the base is 1 mol or more and 2 mol or less with respect to 1 mol of the compound 3-2, the reactivity is hardly lowered and the reaction is easily controlled.

  Reaction (R-4) may be performed in a solvent. The solvent is the same as the solvent used in reaction (R-2), for example. The reaction temperature of reaction (R-4) is preferably 0 ° C. or higher and 50 ° C. or lower, and the reaction time is preferably 2 hours or longer and 24 hours or shorter.

<Synthesis of Compound 6>
Next, compound 6 is synthesized as a raw material used for the synthesis of diamine derivative (1). Compound 6 is represented by the following general formula (6). Compound 6 is synthesized according to any of reaction (R-5), reaction (R-6), or reaction (R-7) and reaction (R-8).

  In general formula (6), m is synonymous with m in general formula (1). X represents a halogen atom. Compound 6-1 in which m in general formula (6) is 1 is synthesized according to reaction (R-5). Compound 6-2 in which m in general formula (6) is 2 is synthesized according to reaction (R-6). Compound 6-3 in which m in general formula (6) is 3 is synthesized according to reactions (R-7) and (R-8).

  In the reaction formulas (R-5) to (R-8), X represents a halogen atom.

[Reaction (R-5)]
In reaction (R-5), compound 3-1 (1 equivalent) is reacted with compound 8 (1 equivalent) to give compound 6-1 (1 equivalent). Reaction (R-5) is a Wittig reaction.

  In reaction (R-5), compound 8 is preferably added in an amount of 1 mol to 2.5 mol with respect to 1 mol of compound 3-1. When the number of moles of compound 8 is 1 mole or more and 2.5 moles or less with respect to 1 mole of compound 3-1, the yield of compound 6-1 is unlikely to decrease and compound 6-1 is easily purified.

  Reaction (R-5) may be performed in the presence of a base. The base is the same as, for example, the base used in the reaction (R-2). These bases may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the base added is preferably 1 mol or more and 2 mol or less with respect to 1 mol of the compound 3-1. When the addition amount of the base is 1 mol or more and 2 mol or less with respect to 1 mol of the compound 3-1, the reactivity is hardly lowered and the reaction is easily controlled.

  Reaction (R-5) may be carried out in a solvent. The solvent is the same as the solvent used in reaction (R-2), for example. The reaction temperature of reaction (R-5) is preferably 0 ° C. or higher and 50 ° C. or lower, and the reaction time is preferably 2 hours or longer and 24 hours or shorter.

[Reaction (R-6)]
In reaction (R-6), compound 3-1 (1 equivalent) is reacted with compound 9 (1 equivalent) to give compound 6-2 (1 equivalent). Reaction (R-6) is a Wittig reaction. Reaction (R-6) is carried out in the same manner as in reaction (R-5), for example, except that compound 8 in reaction (R-5) is changed to compound 9.

[Reaction (R-7)]
In the reaction (R-7), compound 2-3 (1 equivalent) is reacted with triethyl phosphite (2 equivalent) to give compound 3-3 (1 equivalent).

  In reaction (R-7), it is preferable to add 2 to 5 mol of triethyl phosphite with respect to 1 mol of compound 2-3. When the number of moles of triethyl phosphite is 2 mol or more and 5 mol or less with respect to 1 mol of compound 2-3, the yield of compound 3-3 is unlikely to decrease and compound 3-3 is easily purified.

  The reaction temperature for the reaction (R-7) is preferably from 160 ° C. to 200 ° C., and the reaction time is preferably from 2 hours to 10 hours.

[Reaction (R-8)]
In reaction (R-8), compound 3-3 (1 equivalent) is reacted with compound 8 (2 equivalents) to give compound 6-3 (1 equivalent). Reaction (R-8) is a Wittig reaction.

  In reaction (R-8), it is preferable to add 2 mol or more and 5 mol or less of compound 8 with respect to 1 mol of compound 3-3. When the number of moles of compound 8 is 2 moles or more and 5 moles or less with respect to 1 mole of compound 3-3, the yield of compound 6-3 is unlikely to decrease and compound 6-3 is easily purified.

  Reaction (R-8) may be performed in the presence of a base. The base is the same as, for example, the base used in the reaction (R-2). These bases may be used individually by 1 type, and may be used in combination of 2 or more type. The addition amount of the base is preferably 1 mol or more and 2 mol or less with respect to 1 mol of the compound 8. When the addition amount of the base is 1 mol or more and 2 mol or less with respect to 1 mol of the compound 8, the reactivity is hardly lowered and the reaction is easily controlled.

  Reaction (R-8) may be carried out in a solvent. The solvent is the same as the solvent used in reaction (R-2), for example. The reaction temperature of reaction (R-8) is preferably 0 ° C. or higher and 50 ° C. or lower, and the reaction time is preferably 2 hours or longer and 24 hours or shorter.

<Synthesis of diamine derivative (1)>
Next, the diamine derivative (1) is synthesized using the synthesized compound 7 and compound 6. The diamine derivative (1) is synthesized according to reactions (R-9) and (R-10).

[Reaction (R-9)]
In reaction (R-9), compound 10 (1 equivalent) is reacted with compound 7 (1 equivalent) to give compound 11 (1 equivalent). Reaction (R-9) is a coupling reaction.

  In reaction (R-9), it is preferable to add 1 mol or more and 5 mol or less of compound 7 with respect to 1 mol of compound 10. If the number of moles of compound 7 is too small relative to the number of moles of compound 10, the yield of compound 11 may decrease. On the other hand, when the number of moles of compound 7 is too large relative to the number of moles of compound 10, unreacted compound 7 remains after the reaction, and purification of compound 11 may be difficult.

  The reaction temperature for reaction (R-9) is preferably from 80 ° C to 140 ° C, and the reaction time is preferably from 2 hours to 10 hours.

  In the reaction (R-9), it is preferable to use a palladium compound as a catalyst. By using a palladium compound, the activation energy in the reaction (R-9) tends to decrease. As a result, it is considered that the yield of compound 11 can be improved. Examples of the palladium compound include a tetravalent palladium compound, a divalent palladium compound, and other palladium compounds. Examples of the tetravalent palladium compound include sodium hexachloropalladium (IV) tetrahydrate or potassium hexachloropalladium (IV) tetrahydrate. Examples of the divalent palladium compound include palladium chloride (II), palladium bromide (II), palladium acetate (II), palladium acetyl acetate (II), dichlorobis (benzonitrile) palladium (II), dichlorobis (triphenylphosphine). ) Palladium (II), dichlorotetramine palladium (II), or dichloro (cycloocta-1,5-diene) palladium (II). Examples of other palladium compounds include tris (dibenzylideneacetone) dipalladium (0), tris (dibenzylideneacetone) dipalladium chloroform complex (0), and tetrakis (triphenylphosphine) palladium (0). A palladium compound may be used individually by 1 type, and may be used in combination of 2 or more type. The addition amount of the palladium compound is preferably 0.0005 mol or more and 20 mol or less, and more preferably 0.001 mol or more and 1 mol or less with respect to 1 mol of the compound 10.

  The palladium compound may have a structure including a ligand. Thereby, it is easy to improve the reactivity of reaction (R-5). Examples of the ligand include tricyclohexylphosphine, triphenylphosphine, methyldiphenylphosphine, trifurylphosphine, tri (o-tolyl) phosphine, dicyclohexylphenylphosphine, tri (t-butyl) phosphine, and 2,2′-bis. (Diphenylphosphino) -1,1′-binaphthyl, or 2,2′-bis [(diphenylphosphino) diphenyl] ether. A ligand may be used individually by 1 type and may be used in combination of 2 or more type. The addition amount of the ligand is preferably 0.0005 mol or more and 20 mol or less, and more preferably 0.001 mol or more and 1 mol or less with respect to 1 mol of the compound 10.

  The reaction (R-9) is preferably performed in the presence of a base. Thereby, it is considered that the hydrogen halide (for example, hydrogen chloride) generated in the reaction system can be neutralized promptly and the catalytic activity can be improved. As a result, it is considered that the yield of compound 11 can be improved. The base may be an inorganic base or an organic base. Examples of the organic base include alkali metal alkoxides (more specifically, sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, lithium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide and the like). Is preferred, and sodium tert-butoxide is more preferred. Examples of the inorganic base include tripotassium phosphate and cesium fluoride. When the palladium compound is added in an amount of 0.0005 mol to 20 mol with respect to 1 mol of the compound 10, the addition amount of the base is preferably 1 mol to 50 mol, and preferably 1 mol to 30 mol. It is more preferable.

  Reaction (R-9) may be carried out in a solvent. Examples of the solvent include xylene (more specifically, o-xylene or the like), toluene, tetrahydrofuran, or dimethylformamide.

[Reaction (R-10)]
In reaction (R-10), compound 11 (2 equivalents) and compound 6 (1 equivalent) are reacted to obtain diamine derivative (1) (1 equivalent). Reaction (R-10) is a coupling reaction.

  In reaction (R-10), compound 6 is preferably added in an amount of 0.5 mol to 2.5 mol with respect to 1 mol of compound 11. When the number of moles of compound 6 is 0.5 mol or more and 2.5 mol or less with respect to 1 mol of compound 11, the yield of diamine derivative (1) is unlikely to decrease and the diamine derivative (1) is easily purified.

  The reaction temperature for reaction (R-10) is preferably from 80 ° C to 140 ° C, and the reaction time is preferably from 2 hours to 10 hours.

  In the reaction (R-10), it is preferable to use a palladium compound as a catalyst. By using a palladium compound, the activation energy in the reaction (R-10) tends to decrease. As a result, it is considered that the yield of the diamine derivative (1) can be improved. The palladium compound is the same as, for example, the palladium compound used in the reaction (R-9). A palladium compound may be used individually by 1 type, and may be used in combination of 2 or more type. The addition amount of the palladium compound is preferably 0.0005 mol or more and 20 mol or less, and more preferably 0.001 mol or more and 1 mol or less with respect to 1 mol of the compound 11.

  The palladium compound may have a structure including a ligand. Thereby, it is thought that the reactivity of reaction (R-10) can be improved. A ligand is the same as the ligand used by reaction (R-9), for example. A ligand may be used individually by 1 type and may be used in combination of 2 or more type. The addition amount of the ligand is preferably 0.0005 mol or more and 20 mol or less, and more preferably 0.001 mol or more and 1 mol or less with respect to 1 mol of the compound 11.

  The reaction (R-10) is preferably performed in the presence of a base. Thereby, it is considered that the hydrogen halide (for example, hydrogen chloride) generated in the reaction system can be neutralized promptly and the catalytic activity can be improved. As a result, it is considered that the yield of the diamine derivative (1) can be improved. The base is the same as, for example, the base used in the reaction (R-9). When adding 0.0005 mol or more and 20 mol or less of palladium compound to 1 mol of compound 11, the amount of base added is preferably 1 mol or more and 10 mol or less, and preferably 1 mol or more and 5 mol or less. It is more preferable.

  Reaction (R-10) can be performed in a solvent. The solvent is the same as the solvent used in reaction (R-9), for example.

  The hole transport agent contains two or more compounds. The other of the two or more compounds is another hole transporting agent other than the diamine derivative (1). As another compound, for example, a nitrogen-containing cyclic compound or a condensed polycyclic compound can be used. Examples of the nitrogen-containing cyclic compound and the condensed polycyclic compound include diamine derivatives (more specifically, N, N, N ′, N′-tetraphenylphenylenediamine derivatives, N, N, N ′, N ′). -Tetraphenylnaphthylenediamine derivative, or N, N, N ', N'-tetraphenylphenanthrylenediamine derivative, etc.), oxadiazole compounds (more specifically, 2,5-di (4-methyl) Aminophenyl) -1,3,4-oxadiazole, etc.), styryl compounds (more specifically, 9- (4-diethylaminostyryl) anthracene, etc.), carbazole compounds (more specifically, polyvinylcarbazole, etc.) , Organic polysilane compounds, pyrazoline compounds (more specifically, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, etc.), Dorazon compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, or triazole compound. These hole transport agents may be used alone or in combination of two or more as two or more compounds. Among these hole transporting agents, a hole transporting agent represented by the general formula (HTM2), general formula (HTM3), general formula (HTM5), or general formula (HTM-6) (hereinafter referred to as hole transporting respectively). Agent (HTM2), hole transport agent (HTM3), hole transport agent (HTM5), and general formula (HTM6)) may be preferable.

In General Formula (HTM2), Q ⁸ , Q ¹⁰ , Q ¹¹ , Q ¹² , Q ¹³ , and Q ¹⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or 1 or more carbon atoms. 6 or less alkoxy group or a phenyl group is represented. Q ⁹ and Q ¹⁵ each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. b represents an integer of 0 or more and 5 or less. When b represents an integer of 2 or more and 5 or less, a plurality of Q ⁹ bonded to the same phenyl group may be the same as or different from each other. c represents an integer of 0 or more and 4 or less. When c represents an integer of 2 or more and 4 or less, the plurality of Q ¹⁵ bonded to the same phenyl group may be the same as or different from each other. k represents 0 or 1.

In the general formula (HTM2), Q ⁸ , Q ¹⁰ , Q ¹¹ , Q ¹² , Q ¹³ , and Q ¹⁴ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms (more preferably methyl Group or ethyl group), b and c are preferably 0, and k is preferably 0.

  The hole transport agent (HTM2) is preferably a compound represented by the chemical formula (HTM-2) (hereinafter sometimes referred to as a hole transport agent (HTM-2)).

In General Formula (HTM3), R ^a , R ^b, and R ^c each independently represents an alkyl group having 1 to 6 carbon atoms, a phenyl group, or an alkoxy group having 1 to 6 carbon atoms. q represents an integer of 0 or more and 4 or less. When q represents an integer of 2 or more and 4 or less, a plurality of R ^c bonded to the same phenyl group may be the same or different from each other, and m and n each independently represents an integer of 0 or more and 5 or less. Represent. When m represents an integer of 2 or more and 5 or less, a plurality of R ^b bonded to the same phenyl group may be the same or different from each other. When n represents an integer of 2 or more and 5 or less, a plurality of R ^a bonded to the same phenyl group may be the same or different from each other.

In general formula (HTM3), R ^a and R ^b each independently represents an alkyl group having 1 to 3 carbon atoms, and q represents 0. It is preferable that m and n each independently represent 0 or 2.

  The hole transporting agent (HTM3) is preferably a compound represented by the chemical formula (HTM-3) (hereinafter sometimes referred to as a hole transporting agent (HTM-3)).

In General Formula (HTM5), each Q ² independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. Q ³ , Q ⁴ , Q ⁵ , Q ⁶ , and Q ⁷ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. Represent. Two adjacent ones of Q ³ , Q ⁴ , Q ⁵ , Q ⁶ , and Q ⁷ may be bonded to each other to form a ring. a represents an integer of 0 or more and 5 or less. When a represents an integer of 2 or more and 5 or less, a plurality of Q ² bonded to the same phenyl group may be the same or different from each other. s represents an integer of 1 to 3.

In general formula (HTM5), Q ³ , Q ⁴ , Q ⁵ , Q ⁶ , and Q ⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, a represents 0, s preferably represents 1 or 3.

  The hole transport agent (HTM5) is a compound represented by the chemical formula (HTM-5-1) or the chemical formula (HTM-5-2) (hereinafter referred to as a hole transport agent (HTM-5-1) and a hole transport agent). (It may be described as (HTM-5-2)).

In the general formula (HTM6), Q ¹⁶ , Q ¹⁷ , Q ¹⁸ , and Q ¹⁹ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, Alternatively, it represents an aryl group having 6 to 14 carbon atoms.

In General Formula (HTM6), Q ¹⁶ , Q ¹⁷ , Q ¹⁸ , and Q ¹⁹ each independently preferably represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group.

  The hole transporting agent (HTM6) is preferably a compound represented by the chemical formula (HTM-6) (hereinafter sometimes referred to as a hole transporting agent (HTM-6)).

  The content of the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less, and preferably 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the photosensitive layer. More preferably, it is 10 parts by mass or more and 75 parts by mass or less.

  The ionization potential of the hole transport agent can be measured using, for example, an atmospheric-type ultraviolet photoelectron analyzer (“AC-1” manufactured by Riken Keiki Co., Ltd.). The method for measuring the ionization potential of the hole transport agent will be described in detail in Examples.

  It is considered that the ionization potential of the hole transport agent can be controlled by, for example, the size of the spatial spread of the π-conjugated system or the density of the π-conjugated system charge. More specifically, the ion transport potential of the hole transport agent is increased by increasing the spatial spread of the π-electron system of the hole transport agent or by the presence or absence of an electron-donating substituent such as an alkyl group or an alkoxy group. It is thought that it can be reduced.

  The maximum absolute value of the difference in ionization potential when the hole transport agent contains three or more compounds will be described. Here, a case where the hole transport agent includes three kinds of compounds will be described as an example. Three types of compounds are referred to as a hole transport agent A, a hole transport agent B, and a hole transport agent C. First, the ionization potential of the hole transport agent A, the hole transport agent B, and the hole transport agent C is obtained by measurement. A plurality of ionization potential differences are obtained from the obtained three ionization potentials. Specifically, the difference in ionization potential includes difference in ionization potential (hole transport agent A and hole transport agent B), difference in ionization potential (hole transport agent B and hole transport agent C), and ionization potential. (Hole transport agent C and hole transport agent A). Thereafter, the maximum value is selected from the obtained ionization potential differences, and is set as the maximum absolute value of the ionization potential difference.

  The maximum absolute value of the difference in ionization potential of the hole transport agent is greater than 0.20 eV. This maximum value is preferably larger than 0.20 eV and not larger than 0.50 eV, and more preferably not smaller than 0.26 eV and not larger than 0.50 eV. When it is 0.20 eV or more and 0.50 eV or less, the residual potential of the exposed region of the photosensitive layer and the residual potential of the non-exposed region are more likely to be more uniform, and the electron transport ability is unlikely to decrease.

[4. Charge generator]
The charge generator is not particularly limited as long as it is a charge generator for a photoreceptor. Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azurenium pigments, cyanine Pigments, inorganic photoconductive materials (more specifically, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon, etc.) powders, pyrylium pigments, ansanthrone pigments, triphenylmethane pigments, selenium Examples thereof include pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the phthalocyanine pigment include a metal-free phthalocyanine represented by the chemical formula (CGM-1) (hereinafter sometimes referred to as a charge generator (CGM-1)) or metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine represented by the chemical formula (CGM-2) (hereinafter sometimes referred to as a charge generating agent (CGM-2)), hydroxygallium phthalocyanine, or chlorogallium phthalocyanine. The phthalocyanine pigment may be crystalline or non-crystalline. The crystal shape of the phthalocyanine pigment (for example, X type, α type, β type, Y type, V type, or II type) is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

  Examples of the crystal of metal-free phthalocyanine include an X-type crystal of metal-free phthalocyanine (hereinafter sometimes referred to as X-type metal-free phthalocyanine). Examples of the crystals of titanyl phthalocyanine include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter sometimes referred to as α-type titanyl phthalocyanine, β-type titanyl phthalocyanine, and Y-type titanyl phthalocyanine, respectively). It is done. Examples of the crystal of hydroxygallium phthalocyanine include a V-type crystal of hydroxygallium phthalocyanine. Examples of chlorogallium phthalocyanine crystals include chlorogallium phthalocyanine type II crystals.

  For example, in a digital optical image forming apparatus, it is preferable to use a photoconductor having sensitivity in a wavelength region of 700 nm or more. Examples of the digital optical image forming apparatus include a laser beam printer or a facsimile using a light source such as a semiconductor laser. Since it has a high quantum yield in a wavelength region of 700 nm or more, the charge generator is preferably a phthalocyanine pigment, more preferably a metal-free phthalocyanine or titanyl phthalocyanine. In order to further suppress the generation of the transfer memory when the photosensitive layer contains the diamine derivative (1), as the charge generating agent, X-type metal-free phthalocyanine or Y-type titanyl phthalocyanine is more preferable.

  Y-type titanyl phthalocyanine has a main peak at 27.2 ° of the Bragg angle (2θ ± 0.2 °) in the CuKα characteristic X-ray diffraction spectrum, for example. The main peak in the CuKα characteristic X-ray diffraction spectrum is a peak having the first or second highest intensity in a range where the Bragg angle (2θ ± 0.2 °) is 3 ° or more and 40 ° or less.

(Measuring method of CuKα characteristic X-ray diffraction spectrum)
An example of a method for measuring the CuKα characteristic X-ray diffraction spectrum will be described. A sample (titanyl phthalocyanine) is filled in a sample holder of an X-ray diffractometer (for example, “RINT (registered trademark) 1100” manufactured by Rigaku Corporation), an X-ray tube Cu, a tube voltage 40 kV, a tube current 30 mA, and CuKα. An X-ray diffraction spectrum is measured under the condition of a characteristic X-ray wavelength of 1.542 mm. The measurement range (2θ) is, for example, 3 ° to 40 ° (start angle 3 °, stop angle 40 °), and the scanning speed is, for example, 10 ° / min.

  For the photoreceptor applied to the image forming apparatus using the short wavelength laser light source, Ansanthrone pigment is preferably used as the charge generating agent. The wavelength of the short wavelength laser light is, for example, not less than 350 nm and not more than 550 nm.

  The content of the charge generating agent is preferably 0.1 parts by weight or more and 50 parts by weight or less, and 0.5 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the binder resin contained in the photosensitive layer. More preferably, it is more preferably 0.5 parts by mass or more and 4.5 parts by mass or less.

[5. Binder resin]
Examples of the binder resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include polycarbonate resin, polyarylate resin, styrene-butadiene resin, styrene-acrylonitrile resin, styrene-maleic acid resin, acrylic acid resin, styrene-acrylic acid resin, polyethylene resin, and ethylene-vinyl acetate resin. , Chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate resin, alkyd resin, polyamide resin, urethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyester resin or A polyether resin is mentioned. As a thermosetting resin, a silicone resin, an epoxy resin, a phenol resin, a urea resin, or a melamine resin is mentioned, for example. Examples of the photocurable resin include an epoxy-acrylic acid resin (more specifically, an acrylic acid derivative adduct of an epoxy compound) or a urethane-acrylic resin (acrylic acid derivative adduct of a urethane compound). Can be mentioned. These binder resins may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these resins, a polycarbonate resin is preferable because a photosensitive layer having an excellent balance of processability, mechanical properties, optical properties, and abrasion resistance can be obtained. Examples of the polycarbonate resin include bisphenol Z-type polycarbonate resin, bisphenol ZC-type polycarbonate resin, bisphenol C-type polycarbonate resin, and bisphenol A-type polycarbonate resin. From the viewpoint of good compatibility with the diamine derivative (1) and improving the dispersibility of the diamine derivative (1) in the photosensitive layer, the chemical formula (Resin-1), the chemical formula (Resin-2), or the chemical formula ( A resin having a repeating unit represented by (Resin-3) (hereinafter sometimes referred to as a polycarbonate resin (Resin-1), a polycarbonate resin (Resin-2), and a polycarbonate resin (Resin-3), respectively). preferable.

  The viscosity average molecular weight of the binder resin is preferably 40,000 or more, and more preferably 40,000 or more and 52,500 or less. When the viscosity average molecular weight of the binder resin is 40,000 or more, it is easy to improve the wear resistance of the photoreceptor. When the viscosity average molecular weight of the binder resin is 52,500 or less, the binder resin is easily dissolved in a solvent during formation of the photosensitive layer, and the viscosity of the coating solution for the photosensitive layer does not become too high. As a result, it becomes easy to form a photosensitive layer.

[6. Additive]
The photosensitive layer of the photoreceptor may contain various additives as necessary. Examples of the additive include a deterioration inhibitor (more specifically, an antioxidant, a radical scavenger, a quencher, or an ultraviolet absorber), a softener, a surface modifier, a bulking agent, a thickener, A dispersion stabilizer, wax, donor, surfactant, plasticizer, sensitizer, or leveling agent may be mentioned.

[7. Middle layer]
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (intermediate layer resin). The presence of the intermediate layer is considered to suppress the increase in resistance by smoothing the flow of current generated when the photosensitive member is exposed while maintaining an insulating state capable of suppressing the occurrence of leakage.

  Examples of the inorganic particles include metal (more specifically, aluminum, iron, copper, etc.) particles, metal oxide (more specifically, titanium oxide, alumina, zirconium oxide, tin oxide, or zinc oxide). Etc.) or non-metal oxide particles (more specifically, silica etc.). These inorganic particles may be used individually by 1 type, and may use 2 or more types together.

  The resin for the intermediate layer is not particularly limited as long as it can be used as a resin for forming the intermediate layer. The intermediate layer may contain various additives. The additive is the same as the additive for the photosensitive layer.

[8. Photoconductor manufacturing method]
The photoreceptor is manufactured, for example, as follows. The photoreceptor is manufactured by applying a coating solution for the photosensitive layer onto a conductive substrate and drying. The photosensitive layer coating solution is produced by dissolving or dispersing an electron transport agent, a hole transport agent, a charge generating agent, a binder resin, and various additives added as necessary in a solvent. The

  The solvent contained in the photosensitive layer coating solution (hereinafter sometimes referred to as coating solution) is not particularly limited as long as each component contained in the coating solution can be dissolved or dispersed. Examples of the solvent include alcohols (more specifically, methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbons (more specifically, n-hexane, octane, cyclohexane, etc.), aromatics, and the like. Hydrocarbons (more specifically, benzene, toluene, xylene, etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, etc.), ethers (more specifically, , Dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or propylene glycol monomethyl ether), ketones (more specifically, acetone, methyl ethyl ketone, cyclohexanone, etc.), esters More specifically, ethyl acetate or methyl acetate, etc.), dimethylformamide, dimethyl formamide, or dimethyl sulfoxide and the like. These solvents are used alone or in combination of two or more. In order to improve the workability during the production of the photoreceptor, it is preferable to use a non-halogen solvent (a solvent other than the halogenated hydrocarbon) as the solvent.

  The coating solution is prepared by mixing each component and dispersing in a solvent. For mixing or dispersing, for example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser can be used.

  The coating liquid may contain, for example, a surfactant in order to improve the dispersibility of each component.

  The method for applying the coating solution is not particularly limited as long as the coating solution can be uniformly applied onto the conductive substrate. Examples of the coating method include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

  The method for drying the coating solution is not particularly limited as long as the solvent in the coating solution can be evaporated. For example, the method of heat-processing (hot-air drying) is mentioned using a high-temperature dryer or a vacuum dryer. The heat treatment conditions are, for example, a temperature of 40 ° C. or higher and 150 ° C. or lower and a time of 3 minutes or longer and 120 minutes or shorter.

  In addition, the manufacturing method of a photoreceptor may further include one or both of a step of forming an intermediate layer and a step of forming a protective layer as necessary. A known method is appropriately selected in the step of forming the intermediate layer and the step of forming the protective layer.

  The photoreceptor according to the first embodiment can be provided as an image carrier in a contact charging type DC application type image forming apparatus. A contact charging direct application type image forming apparatus includes a charging unit. The charging unit applies a DC voltage while contacting the surface of the image carrier to charge the surface of the image carrier.

  The photoreceptor according to the first embodiment has been described above. According to the photoconductor of the first embodiment, generation of a transfer memory can be suppressed.

<Second Embodiment: Image Forming Apparatus>
The second embodiment relates to an image forming apparatus. Hereinafter, an aspect of the image forming apparatus according to the second embodiment will be described with reference to FIG. FIG. 2 is a diagram illustrating a configuration of the image forming apparatus according to the second embodiment. The image forming apparatus 100 according to the second embodiment includes an image carrier, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. The image carrier is the photoreceptor 1 according to the first embodiment. The charging unit 42 applies a DC voltage while contacting the surface of the image carrier to charge the surface of the image carrier. The charging polarity of the charging unit 42 is positive. The exposure unit 44 exposes the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier. The developing unit 46 develops the electrostatic latent image as a toner image. The transfer unit 48 transfers the toner image from the image carrier to the transfer member. The outline of the image forming apparatus according to the second embodiment has been described above.

  The image forming apparatus 100 according to the second embodiment can suppress image defects caused by the generation of the transfer memory. The reason is presumed as follows. The image forming apparatus 100 according to the second embodiment includes the photoreceptor 1 according to the first embodiment as an image carrier. The photoreceptor 1 according to the first embodiment can suppress the generation of a transfer memory. Therefore, the image forming apparatus 100 according to the second embodiment can suppress image defects caused by the generation of the transfer memory.

  First, for the sake of convenience, image defects caused by the transfer memory will be described. As described above, when a transfer memory is generated in the image forming process, when the circumference of the photoconductor in image formation is used as a reference (hereinafter sometimes referred to as a reference circumference), the surface of the image carrier has the next circumference. In a region where a desired potential cannot be obtained in the charging process, the potential tends to be lower than a region where a desired potential can be obtained in the charging process of the next circumference. Specifically, the potential of the non-exposure area in the previous round on the surface of the image carrier tends to decrease during the next round of charging as compared to the exposure area in the previous round. For this reason, the non-exposure area in the previous round is more likely to attract the positively charged toner during development because the potential at the time of charging tends to be lower than the exposure area in the previous round. As a result, an image reflecting a non-image portion (non-exposed area) on the reference circumference is easily formed. An image defect in which an image reflecting the image portion of the reference circumference is formed is an image defect caused by the transfer memory (hereinafter sometimes referred to as an image ghost).

  With reference to FIG. 3, an image in which an image defect has occurred will be described. FIG. 3 is a diagram illustrating an image 51 in which an image ghost has occurred. The image 51 includes a region 53 and a region 54. The region 53 is a region corresponding to one rotation of the image carrier, and the region 54 is a region corresponding to one rotation of the image carrier. Region 53 includes an image 56. The image 56 is composed of a donut-shaped solid image. Region 54 includes image 60 and image 58. The image 60 is a donut-shaped halftone image. The image 58 is a donut-shaped white halftone image in the region 54. The image 58 has a higher image density than the image 60. The image 58 is an image defect (image ghost) that reflects the non-exposed area of the area 53 and becomes darker than the design image density. Note that the image in the region 54 is composed of a half-tone image on the entire design image.

  The photoreceptor 1 according to the first embodiment tends to suppress the occurrence of image defects due to the transfer memory as described above. Therefore, since the image forming apparatus 100 according to the second embodiment includes the photoconductor 1 according to the first embodiment as an image carrier, it is considered that image defects due to the transfer memory can be suppressed.

  Hereinafter, each part will be described in detail. An image forming apparatus 100 according to the second embodiment will be described with reference to FIG. The image forming apparatus 100 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 100 may be, for example, a monochrome image forming apparatus or a color image forming apparatus. When the image forming apparatus 100 is a color image forming apparatus, the image forming apparatus 100 employs, for example, a tandem method. Hereinafter, the tandem image forming apparatus 100 will be described as an example.

  The image forming apparatus 100 employs a direct transfer method. Usually, in an image forming apparatus that employs a direct transfer method, an image carrier is likely to be affected by a transfer bias, and thus a transfer memory is usually easily generated. However, the image forming apparatus 100 according to the second embodiment includes the photoreceptor 1 according to the first embodiment as an image carrier. The photoconductor according to the first embodiment can suppress the generation of a transfer memory. Therefore, when the photoreceptor 1 according to the first embodiment is provided as an image carrier, it is considered that the occurrence of image defects caused by the transfer memory can be suppressed even when the image forming apparatus 100 adopts the direct transfer method. It is done.

  The image forming apparatus 100 includes image forming units 40a, 40b, 40c, and 40d, a transfer belt 50, and a fixing unit 52. Hereinafter, when it is not necessary to distinguish, each of the image forming units 40a, 40b, 40c, and 40d is referred to as an image forming unit 40.

  The image forming unit 40 includes an image carrier, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. An image carrier is provided at the center position of the image forming unit 40. The image carrier is provided to be rotatable in the arrow direction (counterclockwise). Around the image carrier, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48 are provided in this order from the upstream side in the rotation direction of the image carrier with reference to the charging unit 42. The image forming unit 40 may further include one or both of a cleaning unit (not shown) and a charge removal unit (not shown).

  Each of the image forming units 40a to 40d sequentially superimposes toner images of a plurality of colors (for example, four colors of black, cyan, magenta, and yellow) on the recording medium P on the transfer belt 50. When the image forming apparatus 100 is a monochrome image forming apparatus, the image forming apparatus 100 includes an image forming unit 40a, and the image forming units 40b to 40d are omitted.

  The charging unit 42 charges the surface of the image carrier. The charging polarity of the charging unit is positive. The charging unit 42 applies a DC voltage while contacting the surface of the image carrier to charge the surface of the image carrier. The charging unit 42 is a contact type charging unit. Examples of the contact-type charging unit 42 include a charging roller or a charging brush.

  A charging roller as the charging unit 42 is provided in the image forming apparatus 100. When charging the surface of the image carrier, the charging roller comes into contact with the surface of the image carrier. Usually, in an image forming apparatus including a charging roller, a transfer memory is likely to occur. However, the photoreceptor 1 according to the first embodiment is provided in the image forming apparatus 100 as an image carrier. The photoreceptor 1 according to the first embodiment can suppress the generation of a transfer memory. Therefore, even when the charging roller is provided in the image forming apparatus 100 as the charging unit 42, the occurrence of image defects due to the generation of the transfer memory is suppressed.

  The voltage applied by the charging unit 42 is only a DC voltage. The charging unit 42 has the following advantages compared to the case where the charging unit applies an AC voltage or the charging unit applies a superimposed voltage obtained by superimposing the AC voltage on the DC voltage. When the charging unit 42 applies only a DC voltage, the voltage value applied to the image carrier is constant, so that the surface of the image carrier is easily charged uniformly to a constant potential. Further, when the charging unit 42 applies only a DC voltage, the wear amount of the photosensitive layer 3 tends to decrease. As a result, a suitable image can be formed.

  Usually, a direct-current voltage tends to generate a transfer memory as compared with an alternating-current voltage. However, the image forming apparatus 100 according to the second embodiment includes the photoreceptor 1 according to the first embodiment as an image carrier. The photoreceptor 1 according to the first embodiment can suppress the generation of a transfer memory. Therefore, the image forming apparatus 100 according to the second embodiment can suppress the occurrence of image defects due to the transfer memory even if the charging unit that applies a DC voltage in contact with the image carrier is provided.

  The exposure unit 44 exposes the surface of the charged image carrier. As a result, an electrostatic latent image is formed on the surface of the image carrier. The electrostatic latent image is formed based on image data input to the image forming apparatus 100.

  The developing unit 46 supplies toner to the surface of the image carrier and develops the electrostatic latent image as a toner image.

  The transfer belt 50 conveys the recording medium P between the image carrier and the transfer unit 48. The transfer belt 50 is an endless belt. The transfer belt 50 is provided to be rotatable in the arrow direction (clockwise).

  The transfer unit 48 transfers the toner image developed by the developing unit 46 from the surface of the image carrier to the recording medium P. When the toner image is transferred from the image carrier to the recording medium P, the image carrier is in contact with the recording medium P. That is, the image forming apparatus 100 employs a so-called direct transfer method. An example of the transfer unit 48 is a transfer roller. As shown in FIG. 2, when the image forming apparatus 100 adopts the direct transfer method, the transfer body corresponds to the recording medium P.

  The fixing unit 52 heats and / or pressurizes the unfixed toner image transferred to the recording medium P by the transfer unit 48. The fixing unit 52 is, for example, a heating roller and / or a pressure roller. The toner image is fixed on the recording medium P by heating and / or pressurizing the toner image. As a result, an image is formed on the recording medium P.

  The image forming apparatus according to the second embodiment has been described above. The image forming apparatus according to the second embodiment can suppress the occurrence of image defects by including the photoconductor according to the first embodiment as an image carrier.

<Third embodiment: Process cartridge>
The third embodiment relates to a process cartridge. The process cartridge according to the third embodiment includes the photoreceptor 1 according to the first embodiment. Next, the process cartridge according to the third embodiment will be described with reference to FIG.

  The process cartridge includes a unitized image carrier. The process cartridge employs a configuration in which at least one selected from the group consisting of a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48 is unitized in addition to the image carrier. The process cartridge corresponds to each of the image forming units 40a to 40d, for example. The process cartridge may further include one or both of a cleaning device (not shown) and a static eliminator (not shown). The process cartridge is designed to be detachable from the image forming apparatus 100. Therefore, the process cartridge is easy to handle, and when the sensitivity characteristics and the like of the image carrier are deteriorated, the process cartridge including the image carrier can be easily and quickly replaced.

  The process cartridge according to the third embodiment has been described above. Since the process cartridge according to the third embodiment includes the photoconductor 1 according to the first embodiment as an image carrier, it is possible to suppress the occurrence of image defects due to the occurrence of a transfer memory.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the scope of the examples.

<1. Photosensitive Material>
The following electron transport agent, hole transport agent, charge generator, and binder resin were prepared as materials for forming the photosensitive layer of the photoreceptor.

[1-1. Electron transport agent]
The electron transport agent (ETM-2), the electron transport agent (ETM-3), and the electron transport agent (ETM-5) described in the first embodiment were prepared.

[1-2. Hole transport agent]
The hole transport agents (HTM1-1) to (HTM1-3) described in the first embodiment were prepared. The hole transport agents (HTM1-1) to (HTM1-3) were each synthesized by the following method.

<1-2-1. Synthesis of Compounds 3a, 3b, 3c, and 3d>
First, compounds 3a, 3b, 3c, and 3d were synthesized as raw materials used in the synthesis of compounds 6b, 6c, 7a, and 7b described later. Compounds 3a, 3b, 3c, and 3d were synthesized according to the reactions represented by the following reaction formulas (R-11), (R-12), (R-13), and (R-14), respectively. . Hereinafter, the reactions represented by the reaction formulas (R-11) to (R-14) may be referred to as reactions (R-11) to (R-14), respectively.

  In reaction (R-11), compound 2a was reacted with triethyl phosphite to give compound 3a. Specifically, Compound 2a (16.1 g, 0.10 mol) and triethyl phosphite (25.0 g, 0.15 mol) were charged into a 200 mL flask. The flask contents were stirred at 180 ° C. for 8 hours and then cooled to room temperature. Subsequently, unreacted triethyl phosphite contained in the flask contents was distilled off under reduced pressure. This obtained compound 3a which is a white liquid (yield 24.1 g, yield 92 mol%).

  In reaction (R-12), compound 2b was reacted with triethyl phosphite to give compound 3b. Reaction (R-12) was carried out in the same manner as in reaction (R-11) except that the following points were changed. Compound 2a (16.1 g, 0.10 mol) in reaction (R-11) was changed to compound 2b (15.2 g, 0.10 mol). As a result, compound 3b was obtained (yield 23.5 g, yield 92 mol%).

  In reaction (R-13), compound 2c was reacted with triethyl phosphite to give compound 3c. Reaction (R-13) was carried out in the same manner as in reaction (R-11), except that the following points were changed. Compound 2a (16.1 g, 0.10 mol) in reaction (R-11) was changed to compound 2c (12.7 g, 0.10 mol). As a result, compound 3c was obtained (yield 21.3 g, yield 93 mol%).

  In reaction (R-14), compound 2d was reacted with triethyl phosphite to give compound 3d. Reaction (R-14) was performed in the same manner as in reaction (R-11), except for the following changes. Compound 2a (16.1 g, 0.10 mol) in reaction (R-11) was changed to compound 2d (10.7 g, 0.05 mol). As a result, compound 3d was obtained (yield 14.5 g, yield 88 mol%).

<1-2-2. Synthesis of Compounds 6b and 6c>
Next, compounds 6b and 6c were synthesized as raw materials used in the synthesis of the hole transport agents (HTM1-1), (HTM1-2), and (HTM1-3) described later. Compounds 6b and 6c were synthesized according to the reactions represented by the following reaction formulas (R-16) and (R-17), respectively. Hereinafter, the reactions represented by the reaction formulas (R-16) to (R-17) may be referred to as reactions (R-16) to (R-17), respectively.

  In reaction (R-16), compound 3d was reacted with compound 8a to give compound 6b. Reaction (R-16) is a Wittig reaction. Specifically, compound 3d (8.2 g, 0.025 mol) was added to a 500 mL two-necked flask at 0 ° C. The air in the flask was replaced with argon gas. Subsequently, dry tetrahydrofuran (100 mL) and 28% sodium methoxide (9.3 g, 0.05 mol) were added into the flask. The flask contents were stirred for 30 minutes. Subsequently, a solution of compound 8a (7.03 g, 0.05 mol) in dry tetrahydrofuran (300 mL) was added to the flask. The flask contents were stirred at room temperature for 12 hours. The contents of the flask were poured into ion exchange water and extracted with toluene. The obtained organic layer was washed 5 times with ion-exchanged water and dried using anhydrous sodium sulfate. Subsequently, the solvent contained in the organic layer was distilled off to obtain a residue. The resulting residue was purified using toluene / methanol (20 mL / 100 mL). This obtained the compound 6b which is a white crystal (yield 3.8 g, yield 25 mol%).

  In reaction (R-17), compound 3a was reacted with compound 8a to give compound 6c. Reaction (R-17) is a Wittig reaction. Reaction (R-17) was performed in the same manner as in reaction (R-16), except that the following points were changed. Compound 3d (8.2 g, 0.025 mol) in the reaction (R-16) was changed to compound 3a (13.1 g, 0.025 mol). As a result, compound 6c was obtained (yield 9.4 g, yield 75 mol%).

<1-2-3. Synthesis of Compounds 7a and 7b>
Next, compounds 7a and 7b were synthesized as raw materials used in the synthesis of hole transporting agents (HTM1-1) to (HTM1-3) described later. Compound 7a was synthesized according to the reaction represented by the following reaction formulas (R-18) and (R-19). Compound 7b was synthesized according to the reaction represented by the following reaction formulas (R-18) and (R-20). Hereinafter, reactions represented by reaction formulas (R-18) to (R-20) may be referred to as reactions (R-18) to (R-20), respectively.

  In reaction (R-18), compound 3a was reacted with compound 4 to give compound 5a. Reaction (R-18) is a Wittig reaction. Specifically, compound 3a (13.0 g, 0.05 mol) obtained in the reaction (R-11) was added to a two-necked flask with a volume of 500 mL at 0 ° C. The air in the flask was replaced with argon gas. Subsequently, a solution of dry tetrahydrofuran (100 mL) and compound 4 (35.0 g, 0.26 mol) in dry tetrahydrofuran (300 mL) was added to the flask. The flask contents were stirred for 30 minutes. Subsequently, 28% sodium methoxide (9.3 g, 0.05 mol) was added into the flask. The flask contents were stirred at room temperature for 12 hours. The contents of the flask were poured into ion exchange water and extracted with toluene. The obtained organic layer was washed 5 times with ion-exchanged water and dried using anhydrous sodium sulfate. Subsequently, the solvent contained in the organic layer was distilled off to obtain a residue. The resulting residue was purified using toluene / methanol (20 mL / 100 mL). This obtained the compound 5a which is a white crystal (yield 3.6 g, yield 30 mol%).

  In reaction (R-19), compound 3c was reacted with compound 5a to give compound 7a. Reaction (R-19) is a Wittig reaction. Specifically, the compound 3c (11.4 g, 0.05 mol) obtained in the reaction (R-13) was added to a 500 mL two-necked flask at 0 ° C. The air in the flask was replaced with argon gas. Subsequently, dry tetrahydrofuran (100 mL) and 28% sodium methoxide (9.3 g, 0.05 mol) were added into the flask. The flask contents were stirred for 30 minutes. Subsequently, a solution of compound 5a obtained in the reaction (R-18) (12.2 g, 0.05 mol) in dry tetrahydrofuran (300 mL) was added to the flask. The flask contents were stirred at room temperature for 12 hours. The contents of the flask were poured into ion exchange water and extracted with toluene. The obtained organic layer was washed 5 times with ion-exchanged water and dried using anhydrous sodium sulfate. Subsequently, the solvent contained in the organic layer was distilled off to obtain a residue. The resulting residue was purified using toluene / methanol (20 mL / 100 mL). This obtained the compound 7a which is a white crystal (yield 14.0 g, yield 88 mol%).

  In reaction (R-20), compound 3b was reacted with compound 5a to give compound 7b. Reaction (R-20) is a Wittig reaction. Reaction (R-20) was carried out in the same manner as in reaction (R-19), except for the following points. Compound 3c (11.4 g, 0.050 mol) in reaction (R-19) was changed to compound 3b (12.8 g, 0.050 mol). As a result, compound 7b was obtained (yield 15.3 g, yield 89 mol%).

<1-2-4. Synthesis of Hole Transfer Agent (HTM1-1)>
Next, a hole transporting agent (HTM1-1) was synthesized according to the reactions represented by the following reaction formulas (R-21) and (R-22). Hereinafter, the reactions represented by the reaction formulas (R-21) and (R-22) may be referred to as reactions (R-21) and (R-22), respectively.

In the reaction (R-21), compound 10a and compound 7a were reacted to obtain compound 11a. Reaction (R-21) is a coupling reaction. Specifically, in a three-necked flask, compound 7a (6.2 g, 0.020 mol, second raw material in Table 1), tricyclohexylphosphine (0.068 g, 0.000196 mol), tris (dibenzylideneacetone) dipalladium (0) (0.045 g, 4.89 × 10 ⁻⁵ mol), sodium tert-butoxide (2.0 g, 0.021 mol), compound 10a (2.7 g, 0.020 mol) One raw material) and distilled о-xylene (100 mL). The air in the flask was replaced with argon gas. Subsequently, the flask contents were stirred at 120 ° C. for 5 hours and then cooled to room temperature. The flask contents were washed three times with ion exchange water to obtain an organic layer. Anhydrous sodium sulfate and activated clay were added to the organic layer, followed by drying treatment and adsorption treatment. Subsequently, the organic layer after the drying treatment and the adsorption treatment was distilled off under reduced pressure to remove о-xylene. This gave a residue. The obtained residue was crystallized using chloroform / hexane (volume ratio 1: 1). This gave compound 11a (yield 5.7 g, yield 70 mol%).

Next, in the reaction (R-22), the compound 11a and the compound 6b were reacted to obtain a hole transport agent (HTM1-1). Reaction (R-22) is a coupling reaction. Specifically, in a three-necked flask, compound 6b (1.5 g, 0.005 mol, second raw material in Table 2) obtained in the reaction (R-16), tricyclohexylphosphine (0.035 g, 9.97 × 10 ⁻⁵ mol), tris (dibenzylideneacetone) dipalladium (0) (0.046 g, 4.98 × 10 ⁻⁵ mol), sodium tert-butoxide (1.0 g, 0.010 mol), reaction (R The compound 11a (4.0 g, 0.010 mol, the first raw material in Table 2) obtained in -21) and distilled о-xylene (200 mL) were added. The air in the flask was replaced with argon gas. Subsequently, the flask contents were stirred at 120 ° C. for 5 hours and then cooled to room temperature. The flask contents were washed three times with ion exchange water to obtain an organic layer. Anhydrous sodium sulfate and activated clay were added to the organic layer, followed by drying treatment and adsorption treatment. Subsequently, the organic layer after the drying treatment and the adsorption treatment was distilled off under reduced pressure to remove о-xylene. This gave a residue. The obtained residue was purified by silica gel column chromatography using chloroform / hexane (volume ratio 1: 1) as a developing solvent. Thereby, a hole transport agent (HTM1-1) was obtained (yield 2.8 g, yield 53 mol%).

<1-2-5. Synthesis of Hole Transfer Agents (HTM1-2) and (HTM1-3)>
A hole transport agent (HTM1-2) and (HTM1-3) were respectively synthesized by the same method as the synthesis of the hole transport agent (HTM1-1) except that the following points were changed. In addition, each raw material used in the synthesis | combination of a hole transport agent (HTM1-2)-(HTM1-3) is the same mole number as the mole number of a corresponding raw material in the synthesis | combination of a hole transport agent (HTM1-1). Added.

  Table 1 shows the first raw material, the second raw material, and the reaction product in the reaction (R-21). In reaction (R-21), the first raw material was changed from compound 10a to compound 10b or 10f (first raw material shown in Table 1). In the reaction (R-21), the second raw material was changed from compound 7a to compound 7a or 7b (second raw material shown in Table 1). As a result, in the reaction (R-21), the reaction product (compound 11b or 11f) shown in Table 1 was obtained instead of the compound 11a. Table 1 shows the yield and yield of each reaction product obtained in the reaction (R-21).

  Table 2 shows the first raw material, the second raw material, and the reaction product in the reaction (R-22). In the reaction (R-22), the first raw material was changed from the compound 11a to the compound 11b or 11f (first raw material shown in Table 2). Further, the second raw material in the reaction (R-22) was changed from compound 6b to compound 6b or 6c (second raw material shown in Table 2). As a result, in the reaction (R-22), hole transfer agents (HTM1-2) and (HTM1-3) were obtained instead of the hole transfer agent (HTM1-1). Table 2 shows the yield and yield of the hole transport agents (HTM1-2) and (HTM1-3) obtained in the reaction (R-22).

  In Tables 1 and 2, the compounds 10a, 10b, and 10f, and 11a, 11b, and 11f are represented by the following chemical formulas (10a) to (10b) and (10f), and chemical formulas (11a) to (11b) And the chemical formula (11f). In Tables 1 and 2, compounds 7a to 7b and 6b to 6c are compounds obtained by the above reaction.

Next, the hole transport agent (HTM1-3) synthesized using ¹ H-NMR (proton nuclear magnetic resonance spectrometer) was analyzed. The magnetic field strength was set to 300 MHz. Deuterated chloroform (CDCl ₃ ) was used as the solvent. Tetramethylsilane (TMS) was used as an internal standard substance. The chemical shift value of the measured hole transport agent (HTM1-3) is shown below. ^{From the 1} H-NMR spectrum and the chemical shift value, it was confirmed that the hole transporting agent (HTM1-3) had a structure represented by the chemical formula (HTM1-3).
Hole transport agent (HTM1-3): ¹ H-NMR (300 MHz, CDCl ₃ ) δ 2.0 (s, 6H), 6.6-6.7 (m, 6H), 6.8-7.1 (M, 16H), 7.2-7.5 (m, 30H)

The ionization potential of the hole transport agent (HTM1-3) was 5.18 eV. The ionization potential of the hole transport agent was measured using an atmospheric-type ultraviolet photoelectron analyzer (“AC-1” manufactured by Riken Keiki Co., Ltd.). The measurement conditions were as shown below. The ionization potential of the diamine derivative (1) other than the hole transport agent (HTM1-3) was measured by the same method.
(Ionization potential measurement conditions)
Measurement start energy: 4.50 eV
Measurement end energy: 6.20 eV
Energy interval (step): 0.10 eV

<1-2-6. Hole transport agents (HTM-11) and (HTM-12)>
As a hole transport agent, a compound represented by the chemical formula (HTM-11) or (HTM-12) (hereinafter, sometimes referred to as a hole transport agent (HTM-11) and (HTM-12)) was prepared. .

[1-3. Charge generator]
The charge generating agent (CGM-1) and charge generating agent (CGM-2) described in the first embodiment were prepared. The charge generator (CGM-1) was a metal-free phthalocyanine (X-type metal-free phthalocyanine) represented by the chemical formula (CGM-1). The crystal structure of the charge generating agent (CGM-1) was X type.

  The charge generating agent (CGM-2) was titanyl phthalocyanine (Y-type titanyl phthalocyanine) represented by the chemical formula (CGM-2). The crystal structure of the charge generating agent (CGM-2) was Y-type.

[1-4. Binder resin]
Polycarbonate resin (Resin-1) (Teijin Limited “Panlite (registered trademark) TS-2050”, viscosity average molecular weight 50,000), polycarbonate resin (Resin-2) (viscosity average molecular weight 50,000) as binder resin And polycarbonate resin (Resin-3) (viscosity average molecular weight 50,000) was prepared.

<2. Manufacture of photoconductor>
Photoconductors (A-1) to (A-13) and photoconductors (B-1) to (B-5) were produced using materials for forming the photosensitive layer.

[2-1. Production of photoconductor (A-1)]
In the container, 5 parts by mass of a compound (CGM-1) as a charge generating agent, 30 parts by mass of a hole transporting agent (HTM1-1) and 30 parts by mass of a hole transporting agent (HTM-2), and an electron transporting agent 30 parts by mass of (ETM-1), 100 parts by mass of a polycarbonate resin (Resin-1) as a binder resin, and 800 parts by mass of tetrahydrofuran as a solvent were added. The contents of the container were mixed for 24 hours using a ball mill to disperse the material in the solvent. This obtained the coating liquid for photosensitive layers. The photosensitive layer coating solution was coated on an aluminum drum-shaped support as a conductive substrate using a dip coating method. The coated photosensitive layer coating solution was dried with hot air at 120 ° C. for 40 minutes. This formed the photosensitive layer (film thickness of 30 micrometers) on the electroconductive base | substrate. As a result, a photoreceptor (A-1) was obtained.

[2-2. Production of photoconductors (A-2) to (A-13) and photoconductors (B-1) to (B-5)]
Except for the following changes, the photoconductors (A-2) to (A-13) and the photoconductors (B-1) to (B-5) were produced in the same manner as in the production of the photoconductor (A-1). ) Were produced respectively. The compound (CGM-1) as the charge generating agent used in the production of the photoreceptor (A-1) was changed to the type of charge generating agent shown in Table 3. 30 parts by mass of the hole transport agent (HTM1-1) and 30 parts by mass of the hole transport agent (HTM-2) used for the production of the photoreceptor (A-1) are the types and contents of holes shown in Table 3. Changed to transport agent. The electron transport agent (ETM-1) used for the production of the photoreceptor (A-1) was changed to the type of electron transport agent shown in Table 3. The polycarbonate resin (Resin-1) as the binder resin used in the production of the photoreceptor (A-1) was changed to the type of binder resin shown in Table 3.

  Table 3 shows configurations of the photoconductors (A-1) to (A-13) and the photoconductors (B-1) to (B-5). In Table 3, CGM, HTM, and ETM represent a charge generator, a hole transport agent, and an electron transport agent, respectively. In Table 3, CGM-1 and CGM-2 in the CGM column indicate charge generating agents (CGM-1) and (CGM-2), respectively. HTM1-1, HTM1-2, HTM1-3, HTM-2, HTM-3, HTM-5-1, HTM-5-2, and HTM-6 in the HTM column are respectively a hole transport agent (HTM1-1). ), Hole transport agent (HTM1-2), hole transport agent (HTM1-3), hole transport agent (HTM-2), hole transport agent (HTM-3), hole transport agent (HTM-5). -1), a hole transport agent (HTM-5-2), and a hole transport agent (HTM-6). ETM-1, ETM-2, and ETM-5 in the ETM column indicate an electron transport agent (ETM-1), an electron transport agent (ETM-2), and an electron transport agent (ETM-5), respectively. Resin-1, Resin-2, and Resin-3 in the binder resin column indicate polycarbonate resin (Resin-1), polycarbonate resin (Resin-2), and polycarbonate resin (Resin-3).

<3. Evaluation of photoconductor>
(Evaluation of defective images)
Any one of the photoconductors (A-1) to (A-13) of Examples 1 to 13 and the photoconductors (B-1) to (B-5) of Comparative Examples 1 to 5 is used as an image forming apparatus (Kyocera Document). It was mounted on “FS-C5250DN” manufactured by Solutions Corporation. This image forming apparatus includes a contact-type charging roller that applies a DC voltage as a charging unit. The charging roller charges the surface of the photosensitive member by bringing the charging sleeve into contact with the photosensitive member. The charging sleeve is composed of a charging rubber in which conductive carbon is dispersed in epichlorohydrin resin. Further, this image forming apparatus employs an intermediate transfer system. In order to stabilize the operation of the photoreceptor of the image forming apparatus, alphabet images were printed for 1 hour. Subsequently, an image for evaluation was created by the following operation.

  The evaluation image will be described with reference to FIG. FIG. 4 is a diagram showing the evaluation image 70. The evaluation image 70 includes a region 72 and a region 74. The region 72 is a region corresponding to one rotation of the image carrier. Region 72 includes an image 76. The image 76 is composed of a donut-shaped solid image (image density 100%). This solid image is composed of a set of two concentric circles. The region 74 is a region corresponding to one rotation of the image carrier. Region 74 includes an image 78. The image 78 is composed of an entire halftone image (image density 12.5%). First, an image 76 of the region 72 was formed, and then an image 78 of the region 74 was formed. The image 76 is an image corresponding to one rotation of the photoconductor, and the image 78 is an image corresponding to one rotation of the next turn on the basis of the rotation in which the image 76 is formed. This image formation was repeated 10 times.

Next, the last image (tenth image) was used as an evaluation image. The image for evaluation was visually observed, and the presence or absence of an image corresponding to the image 76 in the region 74 was confirmed. Here, visual observation is observation with the naked eye (visual observation) or observation through a loupe (magnification 10 times, manufactured by TRUSCO, TL-SL10K) (loupe observation). The presence or absence of image defects (image ghosts) due to the transfer memory was confirmed. The presence or absence of image ghost was evaluated based on the following criteria. In addition, evaluation A and evaluation B were set as the pass.
Evaluation A: An image ghost corresponding to the image 76 was not observed.
Evaluation B: A slight image ghost corresponding to the image 76 was observed.
Evaluation C: An image ghost corresponding to the image 76 was observed. The contrast between the image ghost observed in the evaluation sample and the non-image part where no image ghost was observed was low.

  As shown in Table 3, in the photoreceptors (A-1) to (A-13), the photosensitive layer contained a charge generator, a hole transport agent, an electron transport agent, and a binder resin. The hole transport agent contained two or more compounds. One of the two or more compounds was any one of the diamine derivatives (1) represented by the chemical formulas (HTM1-1) to (HTM1-3). The hole transport agents (HTM1-1) to (HTM1-3) were diamine derivatives represented by the general formula (1). The other of the two or more compounds is one of a hole transport agent (HTM-2), (HTM-3), (HTM-5-1), (HTM-5-2), and (HTM-6). One or more. The maximum absolute value of the difference in ionization potential of the hole transport agent was 0.20 eV or more. As shown in Table 5, in the photoreceptors (A-1) to (A-13), the evaluation of the image ghost was A (very good) or B (good).

  As shown in Table 4, in the photoreceptors (B-1) to (B-5), the photosensitive layer contained a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin. . Specifically, in the photoconductors (B-1) to (B-2), the maximum absolute value of the difference in ionization potential of the hole transport agent was less than 0.20 eV. In the photoreceptor (B-3), the photosensitive layer contained only the hole transport agent (HTM1-1). Photoconductors (B-4) to (B-5) contained two hole transporting agents, but did not have the diamine derivative (1). As shown in Table 6, in the photoconductors (B-1) to (B-5), the evaluation of the image ghost was C (bad).

  It is clear that the photoconductors (A-1) to (A-13) suppress the generation of the transfer memory as compared with the photoconductors (B-1) to (B-5). The image forming apparatus including the photoconductors (A-1) to (A-13) has an image defect due to the generation of the transfer memory, as compared with the image forming apparatus including the photoconductors (B-1) to (B-5). It is clear to suppress the occurrence of.

  The photoreceptor according to the present invention can be used in an image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Conductive base | substrate 3 Photosensitive layer 3c Single layer type photosensitive layer

Claims (10)

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer,
The photosensitive layer contains a charge generator, a hole transport agent, an electron transport agent, and a binder resin.
The photosensitive layer is a single-layer type photosensitive layer,
The hole transport agent includes two or more compounds,
One of the two or more compounds is a diamine derivative represented by the general formula (1),
An electrophotographic photoreceptor, wherein the absolute value of the difference in ionization potential of the hole transport agent is 0.20 eV or more.

In the general formula (1),
R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ may each independently have a hydrogen atom, a halogen atom, or a substituent. An alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, or an aryl group having 6 to 14 carbon atoms which may have a substituent. Represent,
m represents an integer of 1 to 3,
n represents an integer of 0 or more and 2 or less. In the general formula (1),
R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Represent,
m represents 1 or 3,
The electrophotographic photosensitive member according to claim 1, wherein n represents 0 or 1. One or more selected from the group consisting of compounds represented by the general formula (HTM2), the general formula (HTM3), the general formula (HTM5), and the general formula (HTM6), The electrophotographic photosensitive member according to claim 1, which is the compound.

In the general formula (HTM2),
Q ⁸ , Q ¹⁰ , Q ¹¹ , Q ¹² , Q ¹³ , and Q ¹⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or Represents a phenyl group,
Q ⁹ and Q ¹⁵ each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group,
b represents an integer of 0 to 5,
when b represents an integer of 2 or more and 5 or less, a plurality of Q ⁹ bonded to the same phenyl group may be the same or different from each other;
c represents an integer of 0 or more and 4 or less,
when c represents an integer of 2 or more and 4 or less, a plurality of Q ¹⁵ bonded to the same phenyl group may be the same or different from each other;
k represents 0 or 1,
In the general formula (HTM3),
R ^a , R ^b and R ^c each independently represents an alkyl group having 1 to 6 carbon atoms, a phenyl group, or an alkoxy group having 1 to 6 carbon atoms,
q represents an integer of 0 or more and 4 or less,
when q represents an integer of 2 or more and 4 or less, a plurality of R ^c bonded to the same phenyl group may be the same or different from each other;
m and n each independently represent an integer of 0 to 5,
when m represents an integer of 2 or more and 5 or less, a plurality of R ^b bonded to the same phenyl group may be the same or different from each other;
when n represents an integer of 2 or more and 5 or less, a plurality of R ^a bonded to the same phenyl group may be the same or different from each other;
In the general formula (HTM5),
Q ² each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group,
Q ³ , Q ⁴ , Q ⁵ , Q ⁶ , and Q ⁷ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. Represent,
Two adjacent ones of Q ³ , Q ⁴ , Q ⁵ , Q ⁶ , and Q ⁷ may be bonded to each other to form a ring;
a represents an integer of 0 to 5,
when a represents an integer of 2 or more and 5 or less, a plurality of Q ² bonded to the same phenyl group may be the same or different from each other;
s represents an integer of 1 to 3,
In the general formula (HTM6),
Q ¹⁶ , Q ¹⁷ , Q ¹⁸ , and Q ¹⁹ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or 6 to 14 carbon atoms. The following aryl groups are represented. In the general formula (HTM2),
Q ⁸ , Q ¹⁰ , Q ¹¹ , Q ¹² , Q ¹³ , and Q ¹⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms,
b represents 0;
c represents 0;
k represents 0,
In the general formula (HTM3),
R ^a and R ^b each independently represents an alkyl group having 1 to 3 carbon atoms,
q represents 0;
m and n each independently represent 0 or 2,
In the general formula (HTM5),
Q ³ , Q ⁴ , Q ⁵ , Q ⁶ , and Q ⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms,
a represents 0;
s represents 1 or 3,
In the general formula (HTM6),
The electrophotographic photosensitive member according to claim 3, wherein Q ¹⁶ , Q ¹⁷ , Q ¹⁸ , and Q ¹⁹ each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group. The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the electron transfer agent includes a compound represented by General Formula (ETM1), General Formula (ETM2), or General Formula (ETM5).

In the general formula (ETM1),
R ²¹ and R ²² each independently represents an alkyl group having 1 to 6 carbon atoms,
In the general formula (ETM2),
R ²³ represents an alkoxy group having 1 to 3 carbon atoms having an aryl group having 6 to 14 carbon atoms,
In the general formula (ETM5),
R ²⁴ and R ²⁵ each independently represents an aryl group having 6 to 14 carbon atoms having one or more alkyl groups having 1 to 3 carbon atoms.   The electrophotographic photosensitive member according to claim 1, wherein the charge generating agent includes X-type metal-free phthalocyanine or Y-type titanyl phthalocyanine. Provided as an image carrier in an image forming apparatus,
The image carrier includes a charging unit,
The electrophotographic photosensitive member according to claim 1, wherein the charging unit applies a DC voltage while being in contact with the surface of the image carrier to charge the surface of the image carrier. An image carrier;
A charging unit that charges the surface of the image carrier;
An exposure unit for exposing the surface of the charged image carrier to form an electrostatic latent image;
A developing unit for developing the electrostatic latent image as a toner image;
A transfer unit that transfers the toner image from the surface of the image carrier to a transfer member;
The image carrier is the electrophotographic photosensitive member according to any one of claims 1 to 7,
The charging polarity of the charging unit is positive.
The charging unit is an image forming apparatus in which a DC voltage is applied while being in contact with the surface of the image carrier to charge the surface of the image carrier.   The image forming apparatus according to claim 8, wherein the transfer body is a recording medium.   A process cartridge comprising the electrophotographic photosensitive member according to claim 1.

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