JP2019189555A - Quinone derivative and electrophotographic photoreceptor - Google Patents

Abstract

To provide a compound that improves sensitivity properties of an electrophotographic photoreceptor and inhibits crystallization.SOLUTION: A compound is represented by general formula (1). In general formula (1), Rand Rindependently represent a hydrogen atom, an alkyl group having carbon atoms of 1 or more and 8 or less, an aryl group having carbon atoms of 6 or more and 22 or less which is optionally substituted with an alkyl group having carbon atoms of 1 or more and 10 or less, an aralkyl group having carbon atoms of 7 or more and 20 or less, a cycloalkyl group having carbon atoms of 3 or more and 20 or less, or an alkoxy group having carbon atoms of 1 or more and 6 or less. Ris a single bond or an alkanediyl group having carbon atoms of 1 or more and 4 or less. Two Rare mutually the same. Two Rare mutually the same.SELECTED DRAWING: None

Description

  The present invention relates to a compound (particularly a quinone derivative) and an electrophotographic photoreceptor.

  The electrophotographic photosensitive member is used in an electrophotographic image forming apparatus. 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 electrophotographic photosensitive member includes a single-layer 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. This photosensitive layer contains, for example, a quinone derivative represented by the chemical formula (E-1) as an electron transport agent.

JP 2000-226354 A

  However, the quinone derivative described in Patent Document 1 can improve the sensitivity characteristics of the electrophotographic photosensitive member, but on the other hand, the inventors have found that there is room for improvement in suppressing crystallization. .

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a compound capable of achieving both improvement in sensitivity characteristics of an electrophotographic photosensitive member and suppression of crystallization. Another object of the present invention is to provide an electrophotographic photoreceptor capable of achieving both excellent sensitivity characteristics and suppression of crystallization.

  The compound of the present invention is represented by the general formula (1).

In the general formula (1), R ¹ and R ² may each independently be substituted with a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkyl group having 1 to 10 carbon atoms. An aryl group having 6 to 22 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms is represented. R ³ represents a single bond or an alkanediyl group having 1 to 4 carbon atoms. Two R ¹ are the same as each other. Two R ² are the same as each other.

  The electrophotographic photosensitive member of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single layer. The photosensitive layer contains at least a charge generating agent and the above-described compound.

  The compound of the present invention can achieve both improvement in sensitivity characteristics of an electrophotographic photoreceptor and suppression of crystallization. The electrophotographic photosensitive member of the present invention can achieve both excellent sensitivity characteristics and suppression of crystallization.

It is sectional drawing which shows an example of the electrophotographic photoreceptor which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows an example of the electrophotographic photoreceptor which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows an example of the electrophotographic photoreceptor which concerns on 2nd 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.

  Hereinafter, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 or 4 carbon atoms, a carbon atom 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, an aryl group having 6 to 22 carbon atoms, an alkyl group having 6 to 14 carbon atoms An aryl group, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms, Unless otherwise specified, each has the following meaning.

  Examples of the halogen atom (halogen group) include a fluorine atom (fluoro group), a chlorine atom (chloro group), a bromine atom (bromo group), and an iodine atom (iodo group).

  An alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 or 4 carbon atoms, and 1 to 3 carbon atoms The following alkyl groups are each linear or branched and 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, sec-butyl group, tert-butyl group, n-pentyl group, and isopentyl. Group, neopentyl group, 1,2-dimethylpropyl group, linear or branched hexyl group, linear or branched heptyl group, linear or branched octyl group, direct Examples thereof include a linear or branched nonyl group, and a linear or branched decyl group. Examples of the alkyl group having 1 to 8 carbon atoms are groups having 1 to 8 carbon atoms among the groups described as examples of alkyl groups having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms are groups having 1 to 6 carbon atoms among the groups described as examples of alkyl groups having 1 to 10 carbon atoms. Examples of the alkyl group having 1 or 4 carbon atoms are groups having 1 or 4 carbon atoms among the groups described as examples of alkyl groups having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms are groups having 1 to 3 carbon atoms among the groups described as examples of alkyl groups having 1 to 10 carbon atoms.

  The alkoxy group having 1 to 6 carbon atoms and the alkoxy group having 1 to 3 carbon atoms are each 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, sec-butoxy group, tert-butoxy group, n-pentoxy group, An isopentoxy group, a neopentoxy group and a hexyl group can be mentioned. Examples of the alkoxy group having 1 to 3 carbon atoms are groups having 1 to 3 carbon atoms among the groups described as examples of alkoxy groups having 1 to 6 carbon atoms.

  The aryl group having 6 to 22 carbon atoms, the aryl group having 6 to 14 carbon atoms, and the aryl group having 6 to 10 carbon atoms are each unsubstituted. Examples of the aryl group having 6 to 22 carbon atoms include, for example, phenyl group, naphthyl group, indacenyl group, biphenylenyl group, acenaphthylenyl group, anthryl group, phenanthryl group, triphenylenyl group, pyrenyl group, chrysenyl group, naphthacenyl group, preadenenyl Group, picenyl group, perylenyl group, pentaphenyl group and pentacenyl group. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an indacenyl group, a biphenylenyl group, an acenaphthylenyl group, an anthryl group, and a phenanthryl group. Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group and a naphthyl group.

  The cycloalkyl group having 3 to 20 carbon atoms and the cycloalkyl group having 5 to 10 carbon atoms are each unsubstituted. Examples of the cycloalkyl group having 3 to 20 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cycloundecyl group, and a cyclododecyl group. Group, cyclotridecyl group, cyclotetradecyl group, cyclopentadecyl group, cyclohexadecyl group, cyclooctadecyl group, cyclononadecyl group and cycloicosyl group. Examples of the cycloalkyl group having 5 to 10 carbon atoms are groups having 5 to 10 carbon atoms among the groups described as examples of cycloalkyl groups having 3 to 20 carbon atoms.

  An aralkyl group having 7 to 20 carbon atoms is unsubstituted. Examples of the aralkyl group having 7 to 20 carbon atoms include an alkyl group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 14 carbon atoms.

<First embodiment: quinone derivative>
1st Embodiment of this invention is related with the compound (henceforth a quinone derivative (1) may be described) represented by General formula (1).

In general formula (1), R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a carbon optionally substituted with an alkyl group having 1 to 10 carbon atoms. It represents an aryl group having 6 to 22 atoms, an aralkyl group having 7 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. R ³ represents a single bond or an alkanediyl group having 1 to 4 carbon atoms. Two R ¹ are the same as each other. Two R ² are the same as each other.

  The quinone derivative (1) can be used for forming a photosensitive layer of an electrophotographic photoreceptor (hereinafter sometimes referred to as a photoreceptor), and can achieve both improvement in sensitivity characteristics of the photoreceptor and suppression of crystallization. The reason is presumed as follows.

The quinone derivative (1) has a structure in which two molecules of a compound having one indane ring and one benzene ring are linked via R ³ . The compound having one indane ring and one benzene ring can function alone as a charge transport agent. On the other hand, in the quinone derivative (1), two molecules of a compound having one indane ring and one benzene ring are not connected to each other because two indane rings are in close proximity via R ^3. Compared to the case, the charge transport efficiency between the indane rings is excellent. That is, the quinone derivative (1) can efficiently transport charges. Therefore, the quinone derivative (1) can improve the sensitivity characteristics of the photoreceptor. The quinone derivative (1) has a structure in which two indane rings are twisted. That is, the plane formed by the other indan ring is not parallel to the plane formed by the one indan ring. Thus, since the quinone derivative (1) has a structure in which two indandione rings are twisted, a space is easily formed between molecules. Therefore, in the quinone derivative (1), a hydrogen bond is not easily formed between molecules, and a solvent easily enters between molecules. Therefore, the quinone derivative (1) can exhibit excellent solubility in the solvent for forming the photosensitive layer, and can suppress crystallization of the photoreceptor.

The alkyl group having 1 to 8 carbon atoms represented by R ¹ and R ² is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 or 4 carbon atoms, a methyl group or a tert group. More preferred is a butyl group.

The aryl group having 6 to 22 carbon atoms represented by R ¹ and R ² is preferably an aryl group having 6 to 14 carbon atoms, and more preferably an aryl group having 6 to 10 carbon atoms. The aryl group having 6 to 22 carbon atoms represented by R ¹ and R ² may be substituted with an alkyl group having 1 to 10 carbon atoms.

The aralkyl group having 7 to 20 carbon atoms represented by R ¹ and R ² is preferably an alkyl group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 14 carbon atoms.

The cycloalkyl group having 3 to 20 carbon atoms represented by R ¹ and R ² is preferably a cycloalkyl group having 5 to 10 carbon atoms.

The alkoxy group having 1 to 6 carbon atoms represented by R ¹ and R ² is preferably an alkoxy group having 1 to 3 carbon atoms.

R ¹ and R ² each independently preferably represents an alkyl group having 1 to 8 carbon atoms. R ¹ and R ² preferably represent the same group, and each preferably represents a methyl group, or more preferably represents a tert-butyl group. R ¹ and R ² may represent different groups. When R ¹ and R ² represent different groups, it is preferable that R ¹ represents a methyl group and R ² represents a tert-butyl group.

Examples of the alkanediyl group having 1 to 4 carbon atoms represented by R ³ include a methanediyl group, an ethanediyl group, a propanediyl group, and a butanediyl group.

R ³ preferably represents a single bond or a methanediyl group, and more preferably represents a methanediyl group. When R ³ represents a methanediyl group, the quinone derivative (1) can easily form a structure in which two indane rings are appropriately twisted, and the solubility in a solvent for forming a photosensitive layer is further improved.

  In order to further improve the sensitivity characteristics of the photoreceptor and more effectively suppress crystallization, the quinone derivative (1) is a compound represented by the general formula (1-a) or (1-b). It is preferable that the compound represented by the general formula (1-a) is more preferable.

In general formulas (1-a) and (1-b), R ¹ , R ^2, and R ³ have the same meaning as in general formula (1).

  In order to further suppress the crystallization while further improving the sensitivity characteristics of the photoreceptor, the quinone derivative (1) is more preferably a chemical formula (1-1), (1-2), (1-3), ( 1-4) or (1-5) (hereinafter referred to as quinone derivatives (1-1), (1-2), (1-3), (1-4) and (1-5), respectively. ) May be described. In chemical formulas (1-1) to (1-5), t-Bu represents a tert-butyl group.

  As the quinone derivative (1), a quinone derivative (1-1), (1-3) or (1-5) is particularly preferable.

(Synthesis of quinone derivative (1))
The quinone derivative (1) is, for example, according to the reactions represented by the reaction formulas (R-1) and (R-2) (hereinafter sometimes referred to as reactions (R-1) and (R-2)). Or synthesized by a method equivalent thereto. In addition, the compounds represented by the general formulas (A), (B), (C) and (D) represented by the reaction formulas (R-1) and (R-2) are respectively represented by the compounds (A), ( B), (C) and (D) may be described. Y in the general formulas (A) and (B) each independently represents a halogen atom. Formula ^{(B), R 1, R} 2 in (C) and (D), and R ³ are each the same meaning as in formula (1) R ¹ in, R ^2, and R ^3. As the halogen atom represented by Y, a chlorine atom is preferable.

  In the reaction (R-1), 2 molar equivalents of the compound (A) and 1 molar equivalent of the compound (B) are reacted to obtain 1 molar equivalent of the compound (C). Specifically, the compound (A) and the compound (B) are reacted in the presence of an acid catalyst. Thereby, -COY is eliminated from compound (A) to obtain compound (C). Examples of the acid catalyst include aluminum chloride and titanium tetrachloride, and aluminum chloride is preferable. Reaction (R-1) may be carried out in the presence of a solvent. Examples of the solvent include nitrobenzene. The reaction (R-1) may be performed under an inert gas atmosphere (for example, under a nitrogen gas atmosphere). The reaction temperature for reaction (R-1) is preferably 50 ° C. or higher and 100 ° C. or lower. The reaction time for reaction (R-1) is preferably from 1 hour to 10 hours. After completion of the reaction (R-1), an acid may be added to remove a ligand such as aluminum chloride. Examples of the acid include hydrochloric acid and oxalic acid, and oxalic acid is preferred.

  In the reaction (R-2), 1 molar equivalent of the compound (C) and 2 molar equivalents of the compound (D) are reacted to obtain 1 molar equivalent of the quinone derivative (1). Specifically, the compound (C) and the compound (D) are reacted in the presence of a base catalyst. Examples of the base catalyst include pyridine and picoline, and pyridine is preferable. Note that the base catalyst mentioned here also functions as a solvent. The reaction temperature for reaction (R-2) is preferably 15 ° C or higher and 30 ° C or lower. The reaction time for reaction (R-2) is preferably from 1 hour to 5 hours.

  After performing the reaction (R-1), the obtained compound (C) may be purified. Moreover, after performing reaction (R-2), you may refine | purify the obtained quinone derivative (1). Examples of the purification method include known methods (for example, filtration, silica gel chromatography, or crystallization).

<Second Embodiment: Electrophotographic Photosensitive Member>
The second embodiment of the present invention relates to a photoreceptor. Hereinafter, the structure of the photoreceptor 1 will be described with reference to FIGS. 1 to 3 are cross-sectional views showing examples of the photoreceptor 1 according to the second embodiment.

  As shown in FIG. 1, the photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is a single layer (single layer). The photoreceptor 1 is a single layer type electrophotographic photoreceptor having a single photosensitive layer 3.

  As shown in FIG. 2, the photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and an intermediate layer 4 (undercoat layer). The intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3. As shown in FIG. 1, the photosensitive layer 3 may be provided directly on the conductive substrate 2. Alternatively, as shown in FIG. 2, the photosensitive layer 3 may be provided on the conductive substrate 2 via the intermediate layer 4. The intermediate layer 4 may be a single layer or a plurality of layers.

  As shown in FIG. 3, the photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and a protective layer 5. The protective layer 5 is provided on the photosensitive layer 3. The protective layer 5 may be a single layer or a plurality of layers.

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

  The structure of the photoreceptor 1 has been described above with reference to FIGS. Hereinafter, the photoreceptor will be described in more detail.

<Photosensitive layer>
The photosensitive layer contains at least a charge generator and a quinone derivative (1). The photosensitive layer may further contain a hole transport agent. The photosensitive layer may further contain a binder resin. The photosensitive layer may contain an additive as necessary.

(Quinone derivative (1))
The photosensitive layer contains a quinone derivative (1). The quinone derivative (1) functions as, for example, an electron transport agent in the photosensitive layer. When the photosensitive layer contains the quinone derivative (1), the photoreceptor according to the second embodiment can achieve both excellent sensitivity characteristics and suppression of crystallization.

  The photosensitive layer may contain only the quinone derivative (1) as an electron transport agent. In addition to the quinone derivative (1), the photosensitive layer may further contain an electron transport agent other than the quinone derivative (1) (hereinafter sometimes referred to as other electron transport agent). Examples of other electron transfer agents include quinone compounds (excluding quinone derivatives (1)), diimide compounds, hydrazone compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro- Examples include 9-fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride and dibromomaleic anhydride. It is done. Examples of quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds.

  The photosensitive layer may contain only one kind of quinone derivative (1) or may contain two or more kinds. In addition to the quinone derivative (1), the photosensitive layer may contain only one kind of other electron transporting agent, or may contain two or more kinds of other electron transporting agents. The content of the quinone derivative (1) is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass with respect to the total mass of the electron transport agent. .

  The content of the quinone derivative (1) is preferably 5 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin, and 33 parts by mass. More preferably, it is at least 40 parts by mass. When the content of the quinone derivative (1) is 5 parts by mass or more with respect to 100 parts by mass of the binder resin, it is easy to improve the sensitivity characteristics of the photoreceptor. When the content of the quinone derivative (1) is 100 parts by mass or less with respect to 100 parts by mass of the binder resin, the quinone derivative (1) is easily dissolved in the solvent for forming the photosensitive layer, thereby forming a uniform photosensitive layer. It becomes easy.

  Here, the general electron transport agent can improve the sensitivity characteristic of the photoreceptor as the content thereof increases. However, when the content of the general electron transfer agent is 33 parts by mass or more with respect to 100 parts by mass of the binder resin, the photoconductor may be crystallized. There is a certain limit to the improvement of sensitivity characteristics. On the other hand, since the quinone derivative (1) is excellent in solubility in a solvent for forming a photosensitive layer and compatibility with a binder resin as described above, its content is 33 parts by mass with respect to 100 parts by mass of the binder resin. Even with the above, sensitivity characteristics can be further improved while suppressing crystallization of the photoreceptor. In other words, by improving the content of the quinone derivative (1) to 33 parts by mass or more with respect to 100 parts by mass of the binder resin, improvement in sensitivity characteristics of the photoreceptor and suppression of crystallization can be achieved at a higher level. Can do.

(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 (eg, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide or amorphous silicon) powders, pyrylium pigments, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, Examples thereof 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 and metal phthalocyanine. Metal-free phthalocyanine is represented, for example, by the chemical formula (CGM2). Examples of the metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. Titanyl phthalocyanine is represented by the chemical formula (CGM1). 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, and Y-type titanyl phthalocyanine).

  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, and even more preferably an X-type metal-free phthalocyanine or Y-type titanyl phthalocyanine. Y-type titanyl phthalocyanine is particularly preferred.

  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.

  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.

  In a photoreceptor applied to an image forming apparatus using a short wavelength laser light source (for example, a laser light source having a wavelength of 350 nm or more and 550 nm or less), an sanslon pigment is preferably used as a charge generating agent.

  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.

(Hole transport agent)
Examples of the hole transport agent include triphenylamine derivatives and diamine derivatives (for example, N, N, N ′, N′-tetraphenylbenzidine derivatives, N, N, N ′, N′-tetraphenylphenylenediamine derivatives, N, N, N ′, N′-tetraphenylnaphthylenediamine derivative, N, N, N ′, N′-tetraphenylphenanthrylenediamine derivative or di (aminophenylethenyl) benzene derivative), oxadiazole series A compound (eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole), a styryl compound (eg, 9- (4-diethylaminostyryl) anthracene), a carbazole compound (eg, , Polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (for example, 1-phenyl-3- (p- Methylamino phenyl) pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds and triazole compounds. A hole transport agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The photosensitive layer preferably contains a compound represented by the general formula (10) (hereinafter sometimes referred to as the compound (10)). Compound (10) functions as, for example, a hole transport agent in the photosensitive layer.

In the general formula (10), R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ and R ¹⁰⁶ are each independently an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. Represents a group or an aryl group having 6 to 14 carbon atoms. a, b, c and d each independently represent an integer of 0 or more and 5 or less. e and f each independently represents an integer of 0 or more and 4 or less.

When a represents an integer of 2 or more and 5 or less, the plurality of R ¹⁰¹ may be the same as or different from each other. When b represents an integer of 2 or more and 5 or less, the plurality of R ¹⁰² may be the same as or different from each other. When c represents an integer of 2 or more and 5 or less, the plurality of R ¹⁰³ may be the same as or different from each other. When d represents an integer of 2 or more and 5 or less, the plurality of R ¹⁰⁴ may be the same as or different from each other. When e represents an integer of 2 or more and 4 or less, the plurality of R ¹⁰⁵ may be the same as or different from each other. When f represents an integer of 2 or more and 4 or less, the plurality of R ¹⁰⁶ may be the same as or different from each other.

In general formula (10), R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ , R ^105, and R ¹⁰⁶ each independently preferably represents an alkyl group having 1 to 6 carbon atoms. More preferably, it represents an alkyl group of 3 or less, and more preferably a methyl group. a, b, c and d each independently preferably represent 0 or 1, and more preferably represent 1. e and f each independently preferably represent 0 or 1, and more preferably represent 0.

  Preferable examples of compound (10) include a compound represented by the following chemical formula (10-1) (hereinafter sometimes referred to as compound (10-1)).

  The photosensitive layer may contain only the compound (10) as a hole transport agent. The content of the compound (10) is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass with respect to the total mass of the hole transport agent. .

  The content of the hole transport agent contained in the photosensitive layer 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. More preferred.

(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 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, and a melamine resin are mentioned, for example. As photocurable resin, the acrylic acid adduct of an epoxy compound and the acrylic acid adduct of a urethane compound are mentioned, for example. The photosensitive layer may contain only one kind of these binder resins or may contain two or more kinds.

  As the binder resin, 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 ZC type polycarbonate resin, bisphenol C type polycarbonate resin, bisphenol A type polycarbonate resin and bisphenol Z type polycarbonate resin. The bisphenol Z-type polycarbonate resin is a polycarbonate resin having a repeating unit represented by the following chemical formula (20). Hereinafter, the polycarbonate resin having a repeating unit represented by the chemical formula (20) may be referred to as a polycarbonate resin (20).

(Additive)
Examples of additives include deterioration inhibitors (for example, antioxidants, radical scavengers, singlet quenchers or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, dispersion stabilizers. , Waxes, acceptors, 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, and An organic phosphorus compound is mentioned.

(combination)
As a combination of the hole transport agent and the electron transport agent in the photosensitive layer, the compound (10-1) and the quinone derivative (1-1), (1-2), (1-3), (1-4) or A combination with (1-5) is preferred. Combinations (j-1) to (j-10) shown in Table 1 are preferred as the combination of the charge generating agent, hole transporting agent and electron transporting agent in the photosensitive layer. In Table 1, X-H ₂ Pc, and Y-TiOPc, respectively, showing an X-type metal-free phthalocyanine and Y type titanyl phthalocyanine.

<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 and a drum shape. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

<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 and 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 an additive. Examples of the additive contained in the intermediate layer are the same as those of the additive contained in the photosensitive layer.

<Method for producing photoconductor>
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 coating solution for the photosensitive layer is produced by dissolving or dispersing a charge generating agent, an electron transporting agent and components added as necessary (for example, a hole transporting agent, a binder resin and an additive) in a solvent. .

  The solvent contained in the photosensitive layer coating solution is not particularly limited as long as each component contained in the coating solution can be dissolved or dispersed. 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 And dimethyl sulfoxide. One of these solvents may be used alone, or two or more may be used in combination. 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 photosensitive layer 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 photosensitive layer coating solution may contain, for example, a surfactant in order to improve the dispersibility of each component.

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

  The method for drying the photosensitive layer coating solution is not particularly limited as long as the solvent in the coating solution can be evaporated. As a specific method for drying the coating solution for the photosensitive layer, for example, a method of performing a heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer may be mentioned. 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.

  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.

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

(Charge generator)
Y-type titanyl phthalocyanine and X-type metal-free phthalocyanine were prepared as charge generating agents. As the Y-type titanyl phthalocyanine, a titanyl phthalocyanine represented by the chemical formula (CGM1) described in the second embodiment and having a Y-type crystal structure was prepared. As the X-type metal-free phthalocyanine, a metal-free phthalocyanine represented by the chemical formula (CGM2) described in the second embodiment and having an X-type crystal structure was prepared.

(Hole transport agent)
As the hole transport agent, the compound (10-1) described in the second embodiment (hereinafter may be referred to as a hole transport agent (10-1)) was prepared.

(Binder resin)
The polycarbonate resin (20) described in the second embodiment was prepared as a binder resin. The viscosity average molecular weight of the polycarbonate resin (20) was 50000.

(Electron transfer agent)
The quinone derivatives (1-1) to (1-5) described in the first embodiment were prepared as electron transport agents. Each of the quinone derivatives (1-1) to (1-5) was synthesized by the following method. In addition, the compounds represented by the chemical formulas (A-1), (B-1), (C-1) and (D-1) described below are respectively represented by the compounds (A-1) and (B-1). , (C-1) and (D-1). Moreover, the yield of each compound was calculated | required by molar ratio conversion.

(Synthesis of quinone derivative (1-1))
According to the reaction represented by the reaction formula (r-1) and the reaction formula (r-2) (hereinafter sometimes referred to as the reaction (r-1) and (r-2)), the quinone derivative (1-1 ) Was synthesized.

  In reaction (r-1), compound (A-1) and compound (B-1) were reacted to obtain compound (C-1). Specifically, 2.82 g (20 mmol) of compound (A-1), 2.79 g (10 mmol) of compound (B-1) and 7.92 g (60 mmol) of aluminum chloride were dissolved in nitrobenzene (50 mL). The resulting nitrobenzene solution was stirred at 80 ° C. for 5 hours under a nitrogen gas atmosphere. Then, 10% oxalic acid aqueous solution (100 mL) was added to the nitrobenzene solution, extracted with chloroform, and the solvent was distilled off to obtain a residue. The residue was purified by silica gel column chromatography using chloroform as a developing solvent. Thereby, a compound (C-1) was obtained. The yield of compound (C-1) was 1.60 g. The yield of compound (C-1) from compound (A-1) was 55%.

  In the reaction (r-2), the compound (C-1) and the compound (D-1) were reacted to obtain a quinone derivative (1-1). Specifically, 2.9 g (10 mmol) of compound (C-1) and 4.4 g (20 mmol) of compound (D-1) were dissolved in pyridine (50 mL). The resulting pyridine solution was stirred at room temperature (25 ° C.) for 3 hours. Thereafter, 100 mL of water was added to the pyridine solution, and the resulting solid was collected by filtration. The filtered solid was purified by silica gel column chromatography using chloroform as a developing solvent to obtain 3.47 g of a quinone derivative (1-1). The yield of the quinone derivative (1-1) from the compound (C-1) was 50%.

(Synthesis of quinone derivatives (1-2) to (1-5))
The quinone derivatives (1-2) to (1-5) were respectively synthesized by the same method as the synthesis of the quinone derivative (1-1) except that the following points were changed. In addition, each raw material used in the synthesis | combination of a quinone derivative (1-2)-(1-5) is added by the same mole number as the mole number of the corresponding raw material used in the synthesis | combination of a quinone derivative (1-1). did.

  The quinone derivative (1-1) is obtained by reacting the compounds (A-1) and (B-1) to obtain the compound (C-1), and then converting the compound (C-1) into the compound (D-1). It was synthesized by reacting with. On the other hand, quinone derivatives (1-2) to (1-5) were synthesized by reacting the compounds shown in Table 2 and Table 3. Tables 2 and 3 show the yield and yield of each reaction.

Next, with reference to ¹ H-NMR (proton nuclear magnetic resonance spectroscopy), it was analyzed by ¹ H-NMR spectrum of the quinone derivative (1-1) to (1-5). 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. As typical examples of the quinone derivatives (1-1) to (1-5), chemical shift values of ¹ H-NMR spectrum of the quinone derivative (1-1) are shown below. From the chemical shift value of the measured ¹ H-NMR spectrum, it was confirmed that the quinone derivative (1-1) was obtained. Each of the quinone derivatives (1-2) to (1-5) is obtained from the chemical shift value of the measured ¹ H-NMR spectrum for the quinone derivatives (1-2) to (1-5). It was confirmed.

Quinone derivative (1-1): ¹ H-NMR (300 MHz, CDCl ₃ ) δ = 8.82-8.87 (m, 4H), 8.21-8.28 (m, 2H), 8.09- 8.17 (m, 4H), 1.38 (s, 36H)

  As an electron transport agent used in Comparative Examples, a compound represented by the chemical formula (E-1) (hereinafter sometimes referred to as compound (E-1)) was also prepared.

<Manufacture of photoconductor>
Each of the photoreceptors (A-1) to (A-10) and (B-1) to (B-4) was manufactured using a material for forming the photosensitive layer.

(Manufacture of photoconductor (A-1))
In the container, 2 parts by mass of X-type metal-free phthalocyanine as a charge generating agent, 50 parts by mass of a hole transporting agent (10-1), 35 parts by mass of a quinone derivative (1-1) as an electron transporting agent, as a binder resin 100 parts by mass of the polycarbonate resin (20) and 600 parts by mass of tetrahydrofuran as a solvent were added. The contents of the container were mixed for 12 hours using a ball mill to disperse the material in the solvent. This obtained the coating liquid for photosensitive layers. The coating solution for the photosensitive layer was coated on a conductive substrate (aluminum drum-shaped support, diameter 30 mm, total length 238.5 mm) using a blade coating method. The applied photosensitive layer coating solution was dried with hot air at 120 ° C. for 80 minutes. Thus, a single photosensitive layer (thickness 30 μm) was formed on the conductive substrate. As a result, a photoreceptor (A-1) was obtained.

(Production of photoconductors (A-2) to (A-10) and (B-1) to (B-4))
Each of the photoreceptors (A-2) to (A-10) and (B-1) to (B-4) is the same as the production of the photoreceptor (A-1) except that the following points are changed. Manufactured. In the production of the photoreceptor (A-1), X-type metal-free phthalocyanine was used as a charge generator, but the photoreceptors (A-2) to (A-10) and (B-1) to (B-4) In each production, charge generators of the types shown in Table 4 were used. In the production of the photoreceptor (A-1), 35 parts by mass of the quinone derivative (1-1) was used as the electron transport agent. However, the photoreceptors (A-2) to (A-10) and (B-1) In each production of (B-4), the amounts and types of electron transport agents shown in Table 4 were used.

<Evaluation of sensitivity characteristics>
The sensitivity characteristics of each of the photoreceptors (A-1) to (A-10) and (B-1) to (B-4) were evaluated. The sensitivity characteristics were evaluated in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH. First, the surface of the photosensitive member was charged to +600 V using a drum sensitivity tester (manufactured by Gentec Corporation). 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 photoreceptor was irradiated with the extracted monochromatic light. The surface potential of the photoconductor was measured after 50 milliseconds had elapsed from the end of irradiation. The measured surface potential was defined as a post-exposure potential (V _L , unit: + V). Table 3 shows the measured post-exposure potential (V _L ) of the photoreceptor. In addition, it shows that the sensitivity characteristic (especially the sensitivity characteristic with respect to exposure light) of a photoreceptor is excellent, so that a post-exposure potential ( _VL ) is a small positive value. A photoconductor having a post-exposure potential (V _L ) of +155 V or higher was evaluated as having poor sensitivity characteristics.

<Evaluation of presence or absence of crystallization>
The entire surface (photosensitive layer) of each of the photoreceptors (A-1) to (A-10) and (B-1) to (B-4) was observed with the naked eye. And the presence or absence of the crystallized part in a photosensitive layer was confirmed. The confirmation results are shown in Table 4.

In Table 4, CGM, HTM, ETM, V _L , X-H ₂ Pc, and Y-TiOPc are respectively a charge generator, a hole transport agent, an electron transport agent, a post-exposure potential, an X-type metal-free phthalocyanine, And Y-type titanyl phthalocyanine. In Table 4, “None” indicates that a portion crystallized in the photosensitive layer was not confirmed, and “Slightly crystallized” indicates that a portion crystallized in the photosensitive layer was slightly confirmed.

  The photoreceptors (A-1) to (A-10) were provided with a conductive substrate and a single photosensitive layer. The photosensitive layer contained at least a charge generator and a quinone derivative (1). Specifically, the photosensitive layer contained any of the quinone derivatives (1-1) to (1-5) included in the general formula (1). Therefore, as is apparent from Table 4, in the photoreceptors (A-1) to (A-10), the post-exposure potential was a small positive value, and the sensitivity characteristics of the photoreceptor were excellent. Further, in the photoconductors (A-1) to (A-10), the crystallized portion in the photosensitive layer was not confirmed, and the crystallization of the photosensitive layer was suppressed. Thus, the photoreceptors (A-1) to (A-10) have both excellent sensitivity characteristics and suppression of crystallization.

  On the other hand, the quinone derivative (1) was not contained in the photosensitive layers of the photoreceptors (B-1) to (B-4). Specifically, compound (E-1) was contained in the photosensitive layers of photoconductors (B-1) to (B-4), but compound (E-1) is included in formula (1). It was not a compound. Therefore, as apparent from Table 4, in the photoreceptors (B-1) to (B-3), the post-exposure potential was a large positive value, and the sensitivity characteristics were unacceptable. Further, in the photoreceptors (B-3) and (B-4), a portion crystallized in the photosensitive layer was slightly confirmed, and crystallization was not suppressed. Thus, the photoreceptors (B-1) to (B-4) did not achieve both excellent sensitivity characteristics and suppression of crystallization.

  From the above, the quinone derivative according to the present invention was able to achieve both improvement in sensitivity characteristics of the photoreceptor and suppression of crystallization. Further, the photoreceptor according to the present invention has both excellent sensitivity characteristics and suppression of crystallization.

  The quinone derivative and 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 4 Intermediate | middle layer 5 Protective layer

Claims (10)

The compound represented by General formula (1).

(In the general formula (1),
R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkyl group having 1 to 10 carbon atoms and optionally having 6 to 22 carbon atoms. An aryl group, an aralkyl group having 7 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms,
R ³ represents a single bond or an alkanediyl group having 1 to 4 carbon atoms,
Two R ¹ 's are identical to each other;
Two R ² are the same as each other. ) ^2. The compound according to claim 1, wherein in the general formula (1), R ¹ and R ² each independently represents an alkyl group having 1 to 8 carbon atoms. The compound according to claim 1 or 2, wherein R ³ in the general formula (1) represents a single bond or a methanediyl group. The compound represented by the said General formula (1) is a compound as described in any one of Claims 1-3 which is a compound represented by general formula (1-a) or (1-b).

(The general formula (1-a) and in (1-b), R ^1, R ² and R ³ have the same meaning as R ^1, R ² and R ³ in the general formula (1).) The compound represented by the general formula (1) is a compound represented by the chemical formula (1-1), (1-2), (1-3), (1-4) or (1-5). The compound as described in any one of Claims 1-4.

  The compound represented by the said General formula (1) is a compound of Claim 5 which is a compound represented by the said Chemical formula (1-1), (1-3) or (1-5). Comprising a conductive substrate and a photosensitive layer;
The photosensitive layer is a single layer,
The photosensitive layer is an electrophotographic photosensitive member containing at least a charge generating agent and the compound according to any one of claims 1 to 6. The electrophotographic photosensitive member according to claim 7, wherein the photosensitive layer further contains a compound represented by the general formula (10).

(In the general formula (10), R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ and R ¹⁰⁶ are each independently an alkyl group having 1 to 6 carbon atoms, and having 1 to 6 carbon atoms. Represents an alkoxy group or an aryl group having 6 to 14 carbon atoms,
a, b, c and d each independently represents an integer of 0 to 5,
e and f each independently represents an integer of 0 or more and 4 or less. ) The electrophotographic photoreceptor according to claim 8, wherein the compound represented by the general formula (10) is a compound represented by the chemical formula (10-1).

The electrophotographic photosensitive member according to any one of claims 7 to 9, wherein the photosensitive layer further contains a polycarbonate resin having a repeating unit represented by the chemical formula (20).

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