JP6428583B2 - Naphthoquinone derivatives and electrophotographic photoreceptors - Google Patents

Description

  The present invention relates to a naphthoquinone derivative and an electrophotographic photoreceptor.

  The electrophotographic photosensitive member is used in an electrophotographic image forming apparatus. The electrophotographic photoreceptor includes a photosensitive layer. As the electrophotographic photosensitive member, for example, a multilayer electrophotographic photosensitive member or a single layer type electrophotographic photosensitive member is used. The multilayer electrophotographic photoreceptor includes, as a photosensitive layer, a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. 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 electrophotographic photosensitive member described in Patent Document 1 includes a photosensitive layer. The photosensitive layer contains, for example, a compound represented by the chemical formula (E-1).

International Publication No. 2002/081452

  However, the electrophotographic photosensitive member described in Patent Document 1 has insufficient electrical characteristics.

  The present invention has been made in view of the above problems, and an object thereof is to provide a naphthoquinone derivative that improves the electrical characteristics of an electrophotographic photoreceptor. Another object of the present invention is to provide an electrophotographic photoreceptor excellent in electric characteristics by containing such a naphthoquinone derivative.

  The naphthoquinone derivative of the present invention is represented by the following general formula (1), (2) or (3).

In the general formulas (1), (2) and (3), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ and R ₁₂ each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 14 carbon atoms. The aryl group may have a substituent. X, Y, and Z each independently represent an oxygen atom or a sulfur atom. The three Ys may be the same as or different from each other.

  The electrophotographic photoreceptor of the present invention includes a photosensitive layer. The photosensitive layer contains the naphthoquinone derivative described above.

  According to the naphthoquinone derivative of the present invention, the electrical characteristics of the electrophotographic photoreceptor can be improved. Moreover, according to the electrophotographic photosensitive member of the present invention, the electrical characteristics can be improved by containing such a naphthoquinone derivative.

(A), (b) and (c) are schematic sectional views showing examples of the electrophotographic photosensitive member according to the second embodiment of the present invention, respectively. (A), (b) and (c) is a schematic sectional drawing which shows another example of the electrophotographic photoreceptor which concerns on 2nd embodiment of this invention, respectively. It is an infrared absorption spectrum of the naphthoquinone derivative represented by Chemical formula (1-1) which concerns on 1st embodiment of this invention. It is an infrared absorption spectrum of the naphthoquinone derivative represented by Chemical formula (2-1) which concerns on 1st embodiment of this invention. It is an infrared absorption spectrum of the naphthoquinone derivative represented by Chemical formula (3-1) which concerns on 1st embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. However, 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.

  A halogen atom, an alkyl group having 1 to 10 carbon atoms, 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, 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.

  An alkyl group having 1 to 10 carbon atoms is a linear or branched alkyl group having 1 to 10 carbon atoms that is unsubstituted. Examples of the alkyl group having 1 to 10 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, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, or n-decyl group may be mentioned.

  The alkyl group having 1 to 6 carbon atoms is a linear or branched alkyl group having 1 to 6 carbon atoms that is 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 a linear or branched alkyl group having 1 to 3 carbon atoms that is unsubstituted. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, and a t-butyl group.

  The alkoxy group having 1 to 6 carbon atoms is a linear or branched alkoxy group having 1 to 6 carbon atoms which is unsubstituted. Examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an s-butoxy group, a t-butoxy group, a pentyloxy group, an iso group. A pentyloxy group, a neopentyloxy group, or a hexyloxy group may be mentioned.

  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: Naphthoquinone Derivative>
The first embodiment of the present invention is a naphthoquinone derivative. The naphthoquinone derivative of the first embodiment is represented by the following general formula (1), (2), or (3).

In the general formulas (1), (2) and (3), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ and R ₁₂ Each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 14 carbon atoms. The aryl group may have a substituent. X, Y, and Z each independently represent an oxygen atom or a sulfur atom. Three Y may be the same or different.

  A naphthoquinone derivative represented by the general formula (1), (2), or (3) (hereinafter sometimes referred to as naphthoquinone derivatives (1) to (3)) is an electrophotographic photoreceptor (hereinafter referred to as photosensitive). The electrical characteristics of the body may be improved. The reason is presumed as follows.

  Naphthoquinone derivatives (1) to (3) have a structure in which a naphthoquinone moiety and a heterocyclic moiety are bonded. Thus, the naphthoquinone derivatives (1) to (3) have an asymmetric structure. Therefore, the naphthoquinone derivatives (1) to (3) are easily dissolved in the solvent for forming the photosensitive layer, and a photosensitive layer in which the naphthoquinone derivatives (1), (2), or (3) are uniformly dispersed is obtained. It becomes easy to be done. As a result, it is considered that the carrier mobility in the photosensitive layer is improved and the electrical characteristics (for example, sensitivity characteristics) of the photoreceptor are improved.

  In the naphthoquinone derivatives (1) to (3), the naphthoquinone part and the heterocyclic part are bonded with a double bond, and the double bond and the heterocyclic part form a conjugated double bond. For this reason, the naphthoquinone derivatives (1) to (3) have a relatively large π-conjugated system. For this reason, the naphthoquinone derivatives (1) to (3) tend to be excellent in electron acceptability or electron mobility. Therefore, it is considered that the carrier mobility in the photosensitive layer is improved, and the electrical characteristics of the photoreceptor are improved.

In general formula (1), the alkyl group having 1 to 10 carbon atoms represented by R _{1 to} R ₁₂ is preferably an alkyl group having 1 to 6 carbon atoms, and 1 or more carbon atoms. It is more preferably an alkyl group of 3 or less, and a methyl group or an n-propyl group is still more preferable. The alkyl group having 1 to 10 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 aryl group having 6 to 14 carbon atoms represented by R _{1 to} R ₁₂ is preferably an aromatic monocyclic hydrocarbon group having 6 to 14 carbon atoms, and a phenyl group is More preferred. The aryl group having 6 to 14 carbon atoms 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.

In order to improve the electrical characteristics of the photoreceptor, in general formula (1), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ and R ₁₂ preferably each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group. The phenyl group may have a halogen atom as a substituent. In general formula (1), X, Y and Z preferably represent an oxygen atom.

In order to further improve the electrical characteristics of the photoreceptor, in formula (1), R ₁ and R ₃ each independently represents an alkyl group having 1 to 3 carbon atoms, and R ₂ represents a hydrogen atom. And R ₄ more preferably represents a phenyl group which may have a chlorine atom. In the general formula (2), R ₅ , R ₇ and R ₈ each independently represents an alkyl group having 1 to 3 carbon atoms, and R ₆ more preferably represents a hydrogen atom. In general formula (3), R ₉ represents an alkyl group having 1 to 3 carbon atoms, R ₁₀ and R ₁₁ represent a hydrogen atom, and R ₁₂ represents a phenyl group.

  Specific examples of the naphthoquinone derivative (1) include naphthoquinone derivatives represented by chemical formulas (1-1) to (1-3) (hereinafter referred to as naphthoquinone derivatives (1-1) to (1-3). There is).

  Specific examples of the naphthoquinone derivative (2) include a naphthoquinone derivative represented by the chemical formula (2-1) (hereinafter sometimes referred to as a naphthoquinone derivative (2-1)).

  Specific examples of the naphthoquinone derivative (3) include a naphthoquinone derivative represented by the chemical formula (3-1) (hereinafter sometimes referred to as a naphthoquinone derivative (3-1)).

  The naphthoquinone derivative (1) is produced, for example, according to the reaction formula represented by the reaction formula (R-1) (hereinafter sometimes referred to as reaction (R-1)) or by a method analogous thereto. In addition to these reactions, appropriate steps may be included as necessary.

In reaction _{(R-1), R 1} , R 2, R 3, R 4, and X is a R ₁ each in the general formula _{(1), R 2, R} 3, R 4, and the X synonymous .

  In the reaction (R-1), 1 equivalent of a compound represented by the general formula (1A) (hereinafter sometimes referred to as the compound (1A)) and 1 equivalent of a pyrazolone compound represented by the general formula (1B) (Hereinafter may be referred to as compound (1B)) in the presence of a base catalyst to give 1 equivalent of naphthoquinone derivative (1). Compound (1B) has a methylene group. In reaction (R-1), it is preferable to add 1 mol or more and 2.5 mol or less of compound (1B) with respect to 1 mol of compound (1A). When 1 mol or more of compound (1B) is added to 1 mol of compound (1A), the yield of naphthoquinone derivative (1) can be easily improved. On the other hand, when 2.5 mol or less of compound (1B) is added to 1 mol of compound (1A), unreacted compound (1B) hardly remains after the reaction, and naphthoquinone derivative (1) can be easily purified. Become. The reaction temperature for reaction (R-1) is preferably room temperature (eg, 25 ° C.). The reaction time for reaction (R-1) is preferably 2 hours or longer and 8 hours or shorter. Examples of the base catalyst include pyridine and piperidine. Reaction (R-1) may be carried out in a solvent. The base catalyst may function as a solvent.

  The naphthoquinone derivative (2) is produced, for example, according to the reaction formula represented by the reaction formula (R-2) (hereinafter sometimes referred to as reaction (R-2)) or by a method analogous thereto. In addition to these reactions, appropriate steps may be included as necessary.

In reaction _{(R-2), R 5} , R 6, R 7, R 8, and Y is a _{R 5, R 6, R 7} , R 8, and Y as defined for each in the general formula (2) .

  In the reaction (R-2), 1 equivalent of a compound represented by the general formula (2A) (hereinafter sometimes referred to as the compound (2A)) and 1 equivalent of a compound represented by the general formula (2B) ( Hereinafter, compound (2B) may be reacted in the presence of a base catalyst to obtain 1 equivalent of naphthoquinone derivative (2). Compound (2B) has a methylene group. In reaction (R-2), it is preferable to add 1 mol or more and 2.5 mol or less of compound (2-B) with respect to 1 mol of compound (2A). When 1 mol or more of compound (2B) is added to 1 mol of compound (2A), the yield of naphthoquinone derivative (2) is easily improved. On the other hand, when 2.5 mol or less of compound (2B) is added to 1 mol of compound (2A), unreacted compound (2B) hardly remains after the reaction, and naphthoquinone derivative (2) can be easily purified. Become. The reaction temperature for reaction (R-2) is preferably room temperature (eg, 25 ° C.). The reaction time for reaction (R-2) is preferably 2 hours or longer and 8 hours or shorter. Examples of the base catalyst include pyridine and piperidine. Reaction (R-2) may be performed in a solvent. The base catalyst may function as a solvent.

  The naphthoquinone derivative (3) is produced, for example, according to the reaction formula represented by the reaction formula (R-3) (hereinafter sometimes referred to as reaction (R-3)) or by a method analogous thereto. In addition to these reactions, appropriate steps may be included as necessary.

In reaction _{(R-3), R 9} , R 10, R 11, R 12, and Z are each is _{R 9, R 10, R 11} , R 12, and Z as defined in the general formula (3) .

  In the reaction (R-3), 1 equivalent of a compound represented by the general formula (3A) (hereinafter sometimes referred to as the compound (3A)) and 1 equivalent of a compound represented by the general formula (3B) ( Hereinafter, compound (3B) may be reacted in the presence of a base catalyst to obtain 1 equivalent of naphthoquinone derivative (3). Compound (3B) has a methylene group. In reaction (R-3), it is preferable to add 1 mol or more and 2.5 mol or less of compound (3B) with respect to 1 mol of compound (3A). When 1 mol or more of the compound (3B) is added to 1 mol of the compound (3A), the yield of the naphthoquinone derivative (3) is easily improved. On the other hand, when 2.5 mol or less of compound (3B) is added to 1 mol of compound (3A), unreacted compound (3B) hardly remains after the reaction, and naphthoquinone derivative (3) can be easily purified. Become. The reaction temperature for reaction (R-3) is preferably room temperature (eg, 25 ° C.). The reaction time for reaction (R-3) is preferably 2 hours or longer and 8 hours or shorter. Examples of the base catalyst include pyridine and piperidine. Reaction (R-3) may be carried out in a solvent. The base catalyst may function as a solvent.

  The naphthoquinone derivative according to the first embodiment has been described above. According to the naphthoquinone derivative according to the first embodiment, the electrical characteristics of the photoreceptor can be improved.

<Second Embodiment: Photoconductor>
The second embodiment relates to a photoreceptor. The photoreceptor may be a multilayer photoreceptor or a single layer photoreceptor. The photoreceptor includes a photosensitive layer. The photosensitive layer contains a naphthoquinone derivative (1), (2), or (3).

<1. Single-layer type photoreceptor>
Hereinafter, the structure of the photoconductor 1 when the photoconductor 1 is a stacked type photoconductor will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing a stacked type photoreceptor that is an example of a photoreceptor 1 according to the second embodiment.

  As shown in FIG. 1A, the multilayer photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 includes a charge generation layer 3a and a charge transport layer 3b.

  As shown in FIG. 1B, in the laminated type photoreceptor as the photoreceptor 1, the charge transport layer 3b is provided on the conductive substrate 2, and the charge generation layer 3a is provided on the charge transport layer 3b. Good. However, in order to improve the abrasion resistance of the multilayer photoreceptor, as shown in FIG. 1A, a charge generation layer 3a is provided on the conductive substrate 2, and the charge transport layer is formed on the charge generation layer 3a. 3b is preferably provided.

  As shown in FIG. 1C, the multilayer photoreceptor as the photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and an intermediate layer (undercoat layer) 4. The intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3. Further, a protective layer 5 (see FIG. 2) may be provided on the photosensitive layer 3.

  The thicknesses of the charge generation layer 3a and the charge transport layer 3b are not particularly limited as long as the functions as the respective layers can be sufficiently expressed. The thickness of the charge generation layer 3a is preferably 0.01 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 3 μm or less. The thickness of the charge transport layer 3b is preferably 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less.

  The charge generation layer 3a in the photosensitive layer 3 contains a charge generation agent. The charge generation layer 3a may contain a charge generation layer binder resin (hereinafter sometimes referred to as a base resin). The charge generation layer 3a may contain various additives as necessary.

  The charge transport layer 3b contains a naphthoquinone derivative (1), (2), or (3) as an electron accepting compound. The charge transport layer 3b may contain a hole transport agent or a binder resin. The charge transport layer 3b may contain various additives as necessary. The structure of the photoconductor 1 when the photoconductor 1 is a multilayer photoconductor has been described above with reference to FIG.

<2. Single-layer type photoreceptor>
Hereinafter, the structure of the photoreceptor 1 when the photoreceptor 1 is a single-layer photoreceptor will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view showing a single-layer type photoreceptor that is another example of the photoreceptor 1 according to the present embodiment.

  As shown in FIG. 2A, the single layer type photoreceptor as the photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The single layer type photoreceptor as the photoreceptor 1 includes a single layer type photosensitive layer 3 c as the photosensitive layer 3. The single-layer type photosensitive layer 3 c is a single photosensitive layer 3.

  As shown in FIG. 2B, the single layer type photoreceptor as 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. Further, as shown in FIG. 2C, a 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 single-layer type photosensitive layer 3c as the photosensitive layer 3 contains the naphthoquinone derivative (1), (2), or (3) as an electron transport agent. The single-layer type photosensitive layer 3c may further contain one or more of a charge generator, a hole transport agent, and a binder resin. The single-layer type photosensitive layer 3c may contain various additives as necessary. That is, when the photoreceptor 1 is a single-layer photoreceptor, the electron transport agent and components added as necessary (for example, a charge generator, a hole transport agent, a binder resin, or an additive) In the photosensitive layer 3 (single-layer type photosensitive layer 3c). The structure of the photoreceptor 1 when the photoreceptor 1 is a single-layer photoreceptor has been described above with reference to FIG.

The single-layer photosensitive layer of the single-layer photoreceptor may contain Y-type titanyl phthalocyanine (Y-TiOPc) as a charge generator and naphthoquinone derivative (1) as an electron transport agent. Here, in order to further improve the electrical characteristics of the photoreceptor, in general formula (1), R ₁ and R ₃ each independently represents an alkyl group having 1 to 3 carbon atoms, and R ₂ is Represents a hydrogen atom, and R ₄ more preferably represents a phenyl group which may have a chlorine atom. The single-layer type photosensitive layer of the single-layer type photoreceptor may contain X-type metal-free phthalocyanine (x-H ₂ Pc) and naphthoquinone derivative (1) or (3) as a charge generator. Here, in order to further improve the electrical characteristics of the photoreceptor, in general formula (1), R ₁ and R ₃ each independently represents an alkyl group having 1 to 3 carbon atoms, and R ₂ is , R ₄ represents a phenyl group which may have a chlorine atom, and in general formula (3), R ₉ represents an alkyl group having 1 to 3 carbon atoms, R ₁₀ and More preferably, R ₁₁ represents a hydrogen atom, and R ₁₂ represents a phenyl group. The charge generating agent will be described later.

  Next, elements of the multilayer photoreceptor and the single layer photoreceptor will be described.

<3. 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. An example of the conductive substrate is 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, indium, stainless steel, and brass. These conductive materials may be used alone or in combination of two or more (for example, as an alloy). 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.

<4. Naphthoquinone derivatives>
The photosensitive layer contains the naphthoquinone derivative (1), (2), or (3) according to the first embodiment. When the photoreceptor is a multilayer photoreceptor, the charge transport layer contains a naphthoquinone derivative (1), (2), or (3) as an electron acceptor compound. When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer contains a naphthoquinone derivative (1), (2), or (3) as an electron transport agent. By containing the naphthoquinone derivative (1), (2), or (3) in the photosensitive layer, the electrical characteristics of the photoreceptor can be improved as described in the first embodiment.

  When the photoreceptor is a multilayer photoreceptor, the content of the naphthoquinone derivative (1), (2), or (3) is 10 parts by mass or more with respect to 100 parts by mass of the binder resin contained in the charge transport layer. It is preferably 200 parts by mass or less, and more preferably 20 parts by mass or more and 100 parts by mass or less.

  When the photoreceptor is a single layer type photoreceptor, the content of the naphthoquinone derivative (1), (2), or (3) is 10 parts per 100 parts by mass of the binder resin contained in the single layer type photosensitive layer. It is preferably no less than 200 parts by mass and more preferably no greater than 10 parts by mass and no greater than 100 parts by mass, and particularly preferably no less than 10 parts by mass and no greater than 75 parts by mass.

The charge transport layer may further contain another electron acceptor compound in addition to the naphthoquinone derivative (1), (2), or (3). The single layer type photosensitive layer may further contain another electron transport agent in addition to the naphthoquinone derivative (1), (2) or (3). Other electron acceptor compounds and electron transport agents include, for example, quinone compounds (quinone compounds other than naphthoquinone derivatives (1), (2) or (3)), diimide compounds, hydrazone compounds, malononitrile compounds, Thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, Examples include 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.
<5. Hole transport agent>

  When the photoreceptor is a multilayer photoreceptor, the charge generation layer may contain a hole transport agent. When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer may contain a hole transport agent. As the hole transport agent, 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 (for example, N, N, N ′, N′-tetraphenylphenylenediamine derivatives, N, N, N ′, N′-tetraphenylnaphthyl). Range amine derivatives or N, N, N ′, N′-tetraphenylphenanthrylenediamine derivatives), oxadiazole compounds (for example, 2,5-di (4-methylaminophenyl) -1,3,4- Oxadiazole), styryl compounds (for example, 9- (4-diethylaminostyryl) anthracene), carbazole compounds (for example, polyvinylcarbazole), organic polysilane compounds, pyrazoline-based compounds (for example, 1-phenyl-3- (p-dimethyl) Aminophenyl) pyrazoline), hydrazone compounds, indole compounds, oxazole Compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compound, or triazole-based compounds. These hole transport agents may be used alone or in combination of two or more. Of these hole transporting agents, a compound represented by the chemical formula (H-1) (hereinafter sometimes referred to as the compound (H-1)) is preferable.

  When the photoreceptor is a multilayer photoreceptor, the content of the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the charge transport layer. More preferably, it is 20 parts by mass or more and 100 parts by mass or less.

  When the photoreceptor is a single layer type photoreceptor, the content of the hole transport agent is 10 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the single layer type photosensitive layer. Is more preferably 10 parts by mass or more and 100 parts by mass or less, and particularly preferably 10 parts by mass or more and 75 parts by mass or less.

<6. Charge generator>
When the photoreceptor is a multilayer photoreceptor, the charge generation layer may contain a charge generation agent. When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer may contain a charge generating agent.

  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 (for example, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide or amorphous silicon), pyrylium pigments, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, Examples include 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 metal-free phthalocyanine represented by the chemical formula (C-1) (hereinafter sometimes referred to as compound (C-1)) or metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine represented by the chemical formula (C-2) (hereinafter sometimes referred to as compound (C-2)), hydroxygallium phthalocyanine, or chlorogallium phthalocyanine. The phthalocyanine pigment may be crystalline or non-crystalline. The crystal shape of the phthalocyanine pigment (for example, 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 crystal of titanyl phthalocyanine include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter sometimes referred to as α-type, β-type, or Y-type titanyl phthalocyanine). 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 (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser), it is preferable to use a photoreceptor having sensitivity in a wavelength region of 700 nm or more. 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 particularly improve the electrical characteristics of the photoreceptor when the naphthoquinone derivative is contained in the photosensitive layer, X-type metal-free phthalocyanine or Y-type titanyl phthalocyanine is more preferable as the charge generating agent.

  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.

  When the photoreceptor is a multilayer photoreceptor, the content of the charge generating agent is preferably 5 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the base resin contained in the charge generation layer. More preferably, it is at least 500 parts by mass.

  When the photoreceptor is a single layer type photoreceptor, the content of the charge generating agent is 0.1 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the single layer type photosensitive layer. It is preferably 0.5 parts by mass or more and 30 parts by mass or less, and more preferably 0.5 parts by mass or more and 4.5 parts by mass or less.

<7. Binder resin>
When the photoreceptor is a multilayer photoreceptor, the charge transport layer may contain a binder resin. When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer may contain a 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 copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic acid polymer, styrene-acrylic acid copolymer, Polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polysulfone resin, diallyl phthalate Examples thereof include resins, ketone resins, polyvinyl butyral resins, polyester resins, and polyether resins. 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 (epoxy compound acrylic acid derivative adduct) or a urethane-acrylic acid resin (urethane compound acrylic acid derivative adduct). 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 single-layer type photosensitive layer and a charge transport layer excellent in balance of workability, mechanical properties, optical properties, and abrasion resistance can be obtained. Examples of the polycarbonate resin include a bisphenol Z-type polycarbonate resin represented by the following chemical formula (Resin-1) (hereinafter sometimes referred to as Z-type polycarbonate resin (Resin-1)), a bisphenol ZC-type polycarbonate resin, and bisphenol. C-type polycarbonate resin or bisphenol A-type polycarbonate resin may be mentioned.

  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 charge transport layer coating solution or single layer type photosensitive layer coating solution is increased. Not too much. As a result, it becomes easy to form a charge transport layer or a single-layer type photosensitive layer.

<8. Base resin>
When the photoreceptor is a multilayer photoreceptor, the charge generation layer contains a base resin. The base resin is not particularly limited as long as it is a base resin applicable to the photoreceptor. Examples of the base resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, styrene-acrylic acid copolymer, acrylic acid polymer, polyethylene resin, ethylene-vinyl acetate. Copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polycarbonate resin, polyarylate resin, polysulfone resin, diallyl phthalate resin , Ketone resin, polyvinyl butyral resin, polyether resin or polyester resin. Examples of the thermosetting resin include silicone resin, epoxy resin, phenol resin, urea resin, melamine resin, and other crosslinkable thermosetting resins. Examples of the photocurable resin include an epoxy-acrylic acid resin (epoxy compound acrylic acid addition product or acrylic acid derivative addition product) or a urethane-acrylic acid resin (urethane compound acrylic acid addition product or acrylic acid derivative addition). Product). A base resin may be used individually by 1 type, and may be used in combination of 2 or more type.

  The base resin contained in the charge generation layer is preferably different from the binder resin contained in the charge transport layer. This is because the charge generation layer is not dissolved in the solvent of the charge transport layer coating solution. Here, in the production of a laminated photoreceptor, it is common to form a charge generation layer on a conductive substrate and form a charge transport layer on the charge generation layer. This is because when forming the charge transport layer, a charge transport layer coating solution is applied onto the charge generation layer.

<9. Additives>
The photosensitive layer (charge generation layer, charge transport layer or single layer type photosensitive layer) of the photoreceptor may contain various additives as required. Additives include, for example, deterioration inhibitors (for example, antioxidants, radical scavengers, quenchers or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, Examples include donors, surfactants, plasticizers, sensitizers, and leveling agents. Antioxidants include, for example, hindered phenols (eg, di (tert-butyl) p-cresol), hindered amines, paraphenylenediamine, arylalkanes, hydroquinones, spirochromans, spirodanone or derivatives thereof, organic sulfur compounds or An organic phosphorus compound is mentioned.

<10. Intermediate layer>
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (intermediate layer resin) used for the intermediate layer. 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 (for example, aluminum, iron or copper), metal oxide (for example, titanium oxide, alumina, zirconium oxide, tin oxide or zinc oxide) particles or non-metal oxide (for example, silica). Particles. 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.

<11. Photoconductor manufacturing method>
When the photoreceptor is a multilayer photoreceptor, the multilayer photoreceptor is manufactured, for example, as follows. First, a charge generation layer coating solution and a charge transport layer coating solution are prepared. A charge generation layer is formed by applying a coating solution for charge generation layer onto a conductive substrate and drying. Subsequently, the charge transport layer coating liquid is applied on the charge generation layer and dried to form the charge transport layer. Thereby, a laminated photoreceptor is manufactured.

  The charge generation layer coating solution is prepared by dissolving or dispersing the charge generation agent and components added as necessary (for example, base resin and various additives) in a solvent. The coating solution for the charge transport layer is prepared by dissolving or dispersing the electron acceptor compound and components added as necessary (for example, a binder resin, a hole transport agent, and various additives) in a solvent.

  Next, when the photoconductor is a single layer type photoconductor, the single layer type photoconductor is manufactured, for example, as follows. A single layer type photoreceptor is manufactured by applying a coating solution for a single layer type photosensitive layer onto a conductive substrate and drying. A coating solution for a single-layer type photosensitive layer by dissolving or dispersing an electron transport agent and components added as necessary (for example, a charge generator, a hole transport agent, a binder resin and various additives) in a solvent. Is manufactured.

  The solvent contained in the coating solution for charge generation layer, the coating solution for charge transport layer or the coating solution for single layer type photosensitive layer (hereinafter sometimes referred to as coating solution) dissolves each component contained in the coating solution. Or as long as it can be dispersed, it is not particularly limited. Examples of solvents include alcohols (eg, methanol, ethanol, isopropanol or butanol), aliphatic hydrocarbons (eg, n-hexane, octane or cyclohexane), aromatic hydrocarbons (eg, benzene, toluene or xylene), Halogenated hydrocarbons (eg dichloromethane, dichloroethane, carbon tetrachloride or chlorobenzene), ethers (eg dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or propylene glycol monomethyl ether), ketones (eg acetone, Methyl ethyl ketone or cyclohexanone), esters (eg ethyl acetate or methyl acetate), dimethylformaldehyde, dimethylform Amide or dimethyl sulfoxide. 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 this embodiment has been described above. According to the photoreceptor of this embodiment, the electrical characteristics of the photoreceptor can be improved.

  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 hole transporting agent and charge generating agent were prepared as materials for forming the charge generating layer and charge transporting layer of the multilayer photoreceptor. The following hole transporting agent, charge generating agent and electron transporting agent were prepared as materials for forming the single layer type photosensitive layer of the single layer type photoreceptor.

<1-1. Electron transport agent>
As the electron transfer agent, compounds (1-1) to (1-3), a compound (2-1), and a compound (3-1) were prepared. Compounds (1-1) to (1-3), compound (2-1) and compound (3-1) were produced by the following methods, respectively.

<1-1-1. Production of Compound (1-1)>
A naphthoquinone derivative (1-1) was produced according to the reaction represented by the reaction formula (R-4) (hereinafter sometimes referred to as reaction (R-4)).

  In the reaction (R-4), the compound (1A-1) (2-methyl-1,4-naphthoquinone) and the compound (1B-1) were reacted to obtain a naphthoquinone derivative (1-1). Specifically, 2.0 g (0.011 mol) of the compound (1A-1) and 2.0 g (0.011 mol) of the compound (1B-1) were added to the flask, and 15 mL of pyridine was further added. The flask contents were stirred at room temperature for 3 hours. Subsequently, pyridine was removed by distillation under reduced pressure. The pyridine contained in the flask contents was distilled off under reduced pressure. This gave a residue. The obtained residue was purified by silica gel column chromatography using hexane / ethyl acetate (volume ratio V / V = 10/1) as a developing solvent. The yield of the naphthoquinone derivative (1-1) was 1.87 g, and the yield of the naphthoquinone derivative was 49 mol%.

<1-1-2. Production of Naphthoquinone Derivatives (1-2) to (1-3), (2-1) and (3-1)>
The naphthoquinone derivatives (1-2) to (1-3), (2-1) and (3-1) were changed in the same manner as in the production of the naphthoquinone derivative (1-1) except that the following points were changed. Each was manufactured. In addition, each raw material used in manufacture of a naphthoquinone derivative (1-2)-(1-3), (2-1) and (3-1) is a raw material corresponding in manufacture of a naphthoquinone derivative (1-1). The number of moles was the same as the number of moles.

  Table 1 shows the first raw material, the second raw material and the product in the reaction (R-4). Here, the first raw material and the second raw material are reactants (Reactant) in the reaction (R-4). The compound (1B-1) used in the reaction (R-4) was changed to any one of the compounds (1B-2) to (1B-3), (2B-1) and (3B-1). As a result, in the reaction (R-4), naphthoquinone derivatives (1-2) to (1-3), (2-1) and (3-1) were obtained instead of the naphthoquinone derivative (1-1). . Table 1 shows the yield and yield of the naphthoquinone derivative.

  In Table 1, compounds (1B-2) to (1B-3), (2B-1) and (3B-1) are represented by the following chemical formulas (1B-2) to (1B-3) and (2B-1), respectively. ) And (3B-1).

Next, the naphthoquinone derivatives (1-1) to (1-3), (2-1), and (3-1) manufactured using a Fourier transform infrared spectrophotometer ("SPECTRUM ONE" manufactured by PerkinElmer). ) Was measured. Samples were prepared by the KBr (potassium bromide) tablet method. From the measured infrared absorption spectrum, it was confirmed that naphthoquinone derivatives (1-1) to (1-3), (2-1), and (3-1) were obtained. Among these, naphthoquinone derivatives (1-1), (2-1) and (3-1) are given as representative examples. 3 to 5 show infrared absorption spectra of naphthoquinone derivatives (1-1), (2-1), and (3-1), respectively. 3 to 5, the vertical axis represents the transmittance (%), and the horizontal axis represents the wave number. The unit% of the vertical axis (transmittance) in FIGS. 3 to 5 is an arbitrary unit. The wave number (ν _MAX ) of the absorption peak of the infrared absorption spectrum is shown below.
Naphthoquinone derivative (1-1): IR cm ⁻¹ : 2968, 1689, 1598, 1498, 1154, 804.
Naphthoquinone derivative (2-1): IR cm ⁻¹ : 2968, 1666, 1595, 1460, 1152, 764.
Naphthoquinone derivative (3-1): IRcm ⁻¹ : 1711, 1666, 1594, 1501, 1171, 751.

<1-1-3. Preparation of Compound (E-1)>
As an electron transport agent, a compound represented by the chemical formula (E-1) (hereinafter sometimes referred to as compound (E-1)) was prepared.

<1-2. Hole transport agent>
The compound (H-1) described in the second embodiment was prepared as a hole transport agent.

<1-3. Charge generator>
Compounds (C-1) and (C-2) were prepared as charge generating agents. The compound (C-1) was a metal-free phthalocyanine (X-type metal-free phthalocyanine) represented by the chemical formula (C-1) described in the second embodiment. The crystal structure of the compound (C-1) was X type.

  The compound (C-2) was titanyl phthalocyanine (Y-type titanyl phthalocyanine) represented by the chemical formula (C-2) described in the second embodiment. Moreover, the crystal structure of the compound (C-2) was Y type.

<1-4. Binder resin>
The Z-type polycarbonate resin (Resin-1) described in the second embodiment (“Panlite (registered trademark) TS-2050” manufactured by Teijin Limited, viscosity average molecular weight 50,000) was prepared as the binder resin.

<2. Manufacture of single layer type photoreceptor>
Using the material for forming the photosensitive layer, single layer type photoreceptors (A-1) to (A-10) and single layer type photoreceptors (B-1) to (B-2) were produced.

<2-1. Production of Single Layer Type Photosensitive Member (A-1)>
In the container, 5 parts by mass of the compound (C-1) as a charge generating agent, 80 parts by mass of the compound (H-1) as a hole transporting agent, 40 parts by mass of the compound (1-1) as an electron transporting agent, 100 parts by mass of Z-type 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 50 hours using a ball mill to disperse the material in the solvent. This obtained the coating liquid for single layer type photosensitive layers. The single layer type photosensitive layer coating solution was coated on an aluminum drum-shaped support (diameter: 30 mm, total length: 238.5 mm) as a conductive substrate using a dip coating method. The applied coating liquid for single layer type photosensitive layer was dried with hot air at 100 ° C. for 30 minutes. As a result, a single-layer type photosensitive layer (thickness 30 μm) was formed on the conductive substrate. As a result, a single layer type photoreceptor (A-1) was obtained.

<2-2. Production of Single Layer Type Photoconductors (A-2) to (A-10) and Single Layer Type Photoconductors (B-1) to (B-2)>
A single-layer photoconductor (A-2) to (A-10) and a single-layer photoconductor (A-10) and a single-layer photoconductor (A-10) are produced in the same manner as the production of the single-layer photoconductor (A-1). B-1) to (B-2) were produced. The compound (C-1) as the charge generating agent used in the production of the single layer type photoreceptor (A-1) was changed to the type of charge generating agent shown in Table 1. The naphthoquinone derivative (1-1) as the electron transport agent used for the production of the single layer type photoreceptor (A-1) was changed to the type of electron transport agent shown in Table 1. Table 2 shows configurations of the photoconductors (A-1) to (A-10) and the photoconductors (B-1) to (B-2). In Table 2, CGM, HTM, and ETM represent a charge generating agent, a hole transport agent, and an electron transport agent, respectively. In Table 2, x-H ₂ Pc and Y-TiOPc in the CGM column represent X-type metal-free phthalocyanine and Y-type titanyl phthalocyanine, respectively. H-1 in the HTM column represents the compound (H-1). ETM column 1-1 to 1-3, 2-1, 3-1, and E-1 are naphthoquinone derivatives (1-1) to (1-3), (2-1), (3- 1) and a compound (E-1) are shown.

<3. Evaluation of electrical characteristics of single-layer type photoreceptor>
The electrical characteristics of each of the produced single layer type photoreceptors (A-1) to (A-10) and single layer type photoreceptors (B-1) to (B-2) were evaluated. The electrical characteristics were evaluated in an environment at a temperature of 23 ° C. and a humidity of 60% RH. First, using a drum sensitivity tester (manufactured by Gentec Co., Ltd.), the surface of the single layer type photoreceptor was charged to positive polarity. The charging conditions were set to a rotation speed of 31 rpm of the single layer type photoreceptor and a current flowing into the single layer type photoreceptor +8 μA. The surface potential of the single-layer type photoreceptor immediately after charging was set to + 700V. Next, monochromatic light (wavelength 780 nm, half-value width 20 nm, light energy 1.5 μJ / cm ² ) was extracted from the white light of the halogen lamp using a bandpass filter. The surface of the monolayer type photoreceptor was irradiated with the extracted monochromatic light. The surface potential of the single-layer photoreceptor was measured after 0.5 seconds had elapsed from the end of irradiation. The measured surface potential was defined as a sensitivity potential (V _L , unit V). Table 2 shows the measured sensitivity potential (V _L ) of the single-layer type photoreceptor. Note that the smaller the absolute value of the sensitivity potential (V _L ), the better the electrical characteristics of the single layer type photoreceptor.

  As shown in Table 1, in the photoreceptors (A-1) to (A-10), the photosensitive layer contains any one of naphthoquinone derivatives (1-1) to (1-5) as an electron transport agent. It was. Naphthoquinone derivatives (1-1) to (1-5) were naphthoquinone derivatives represented by the general formula (1). In the photoconductors (A-1) to (A-10), the sensitivity potential was + 122V or more and + 145V or less.

  As shown in Table 1, in the photoreceptors (B-1) to (B-2), the photosensitive layer contained the compound (E-1) as an electron transport agent. Compound (E-1) was not any of naphthoquinone derivatives (1) to (3). In the photoconductors (B-1) to (B-2), the sensitivity potential was + 155V or more and + 165V or less.

  It is clear that the photoconductors (A-1) to (A-10) are excellent in electrical characteristics as compared with the photoconductors (B-1) to (B-2).

  From the above, it was shown that the naphthoquinone derivative represented by the general formula (1), (2) or (3) improves the electrical characteristics of the photoreceptor when contained in the photosensitive layer. Moreover, it was shown that the photoreceptor provided with the photosensitive layer containing the naphthoquinone derivative represented by the general formula (1), (2) or (3) is excellent in electrical characteristics.

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

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 3 Photosensitive layer 3a Charge generation layer 3b Charge transport layer 3c Single layer type photosensitive layer

Claims (5)

A naphthoquinone derivative represented by the following general formula (1), (2) or (3).

In the general formulas (1), (2) and (3),
R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ and R ₁₂ are each independently a hydrogen atom, a carbon atom number of 1 or more and 10 Represents the following alkyl group or an aryl group having 6 to 14 carbon atoms,
The aryl group may have a substituent,
The substituent is 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,
X, Y, and Z each independently represent an oxygen atom or a sulfur atom, and three Ys may be the same as or different from each other. In the general formulas (1), (2) and (3),
R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ and R ₁₂ are each independently phenyl having a halogen atom. A group, a hydrogen atom, or an alkyl group having 1 to 3 carbon atoms,
The naphthoquinone derivative according to claim 1, wherein X, Y and Z each represents an oxygen atom. In the general formula (1),
R ₁ and R ₃ each independently represents an alkyl group having 1 to 3 carbon atoms,
R ₂ represents a hydrogen atom,
R ₄ represents a phenyl group which may have a chlorine atom,
In the general formula (2),
R ₅ , R ₇ and R ₈ each independently represents an alkyl group having 1 to 3 carbon atoms,
R ₆ represents a hydrogen atom,
In the general formula (3),
R ₉ represents an alkyl group having 1 to 3 carbon atoms,
R ₁₀ and R ₁₁ represent a hydrogen atom,
The naphthoquinone derivative according to claim 2, wherein R ₁₂ represents a phenyl group. An electrophotographic photoreceptor having a photosensitive layer,
The said photosensitive layer is an electrophotographic photoreceptor containing the naphthoquinone derivative as described in any one of Claims 1-3. The photosensitive layer is a single-layer type photosensitive layer,
The single-layer type photosensitive layer further contains a charge generating agent,
The electrophotographic photosensitive member according to claim 4, wherein the charge generating agent contains X-type metal-free phthalocyanine or Y-type titanyl phthalocyanine.

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