JP3530649B2 - Electrophotographic photoreceptor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in an image forming apparatus such as an electrostatic copying machine, a laser printer, a plain paper facsimile machine.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors made of various materials are used in image forming apparatuses such as copiers, facsimiles and laser printers using the Carlson process. One is an inorganic photoreceptor using an inorganic material such as selenium in the photosensitive layer, and the other is an organic photoreceptor (OPC) using an organic material in the photosensitive layer. Among them, the organic photoconductor has many advantages such as being cheaper than the inorganic photoconductor, having high productivity, and being non-polluting. Therefore, extensive research has been conducted.

As the organic photoconductor, there are many laminated photoconductors in which a charge generation layer and a charge transport layer are laminated, that is, so-called function-separated photoconductors. The charge generation agent and the charge transport agent are contained in the photoconductive layer. Dispersed single-layer type photoreceptors are also known. The charge transport agents used in these photoconductors are required to have high carrier mobility, but most of the charge transport agents having high carrier mobility have hole transporting properties, and therefore are not put to practical use. From the viewpoint of mechanical strength, the existing organic photoreceptor is limited to a negative charging type laminated organic photoreceptor having a charge transport layer as the outermost layer. However, since the negative charging type organic photoconductor uses negative corona discharge, a large amount of ozone is generated, which causes problems such as pollution of the environment and deterioration of the photoconductor.

Therefore, in order to eliminate such drawbacks, the use of an electron transfer agent as a charge transfer agent has been studied. For example, JP-A-1-206349 discloses a compound having a diphenoquinone structure as an electron transfer agent. It has been proposed to use it as an electron transfer material for photographic photoreceptors.

[0005]

However, in general, conventional electron transfer agents such as diphenoquinone derivatives are difficult to match with the charge generating agent, resulting in insufficient electron injection from the charge generating agent to the electron transferring agent. . Further, since such an electron transfer material has a poor compatibility with the binder resin and a hopping distance becomes long, electron transfer is unlikely to occur in a low electric field.
Therefore, the conventional photoconductor containing an electron transfer material has a problem that the residual potential is high and the sensitivity is low.

An object of the present invention is to solve the above-mentioned technical problems and to provide an electrophotographic photosensitive member having improved sensitivity as compared with the conventional one.

[0007]

The inventors of the present invention have conducted extensive studies in order to solve the above problems, and as a result, an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, The layer has the general formula (1):

[0008]

[Chemical 2]

(Wherein R ¹ , R ² , R ³ and R ⁴ are
The same or different, a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, an alkoxy group which may have a substituent, an acyl which may have a substituent Indicates a group or a halogen atom. When a dibenzofuranquinone derivative represented by the formula (1) is contained, a new fact has been found that an electrophotographic photoreceptor having improved sensitivity as compared with the conventional one can be obtained, and the present invention has been completed.

The dibenzofuranquinone derivative represented by the general formula (1) has good solubility in a solvent and compatibility with a binder resin, and is excellent in matching with a charge generating agent. By using the derivative (1) as an electron transfer agent, a highly sensitive organic photoreceptor can be obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the dibenzofuranquinone derivative (1) used in the electrophotographic photoreceptor of the present invention, examples of the alkyl group corresponding to the substituents R ^{1 to} R ⁴ include methyl, ethyl, n-propyl and isopropyl. , N-butyl, isobutyl, s-butyl, t-butyl, pentyl,
Examples thereof include groups having 1 to 6 carbon atoms such as hexyl. Examples of the aryl group include groups such as phenyl, tolyl, xylyl, biphenylyl, o-terphenyl, naphthyl, anthryl, phenanthryl and the like. Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, t-butoxy, pentyloxy,
Examples include groups such as hexyloxy. Examples of the acyl group include groups such as acetyl, propionyl, butyryl, isobutyryl, valeryl, isovaleryl, pivaloyl, benzoyl, 2-naphthoyl and o-toluoyl. Examples of the halogen atom include fluorine, chlorine, bromine, iodine and the like.

Examples of the substituent which may be substituted on the alkyl group include the halogen atom, the aryl group, the alkoxy group and the acyl group exemplified above, and the substituent which may be substituted on the aryl group, the alkoxy group and the acyl group. As a basis,
Examples thereof include the alkyl group, aryl group, alkoxy group, acyl group and halogen atom. Further, the substitution position of such a substituent is not particularly limited.

Specific examples of the dibenzofuranquinone derivative represented by the above general formula (1) include, for example, the following formulas (1-1) to
Examples thereof include compounds represented by (1-2).

[0014]

[Chemical 3]

Among the dibenzofuranquinone derivatives (1),
For example, a method of synthesizing the dibenzofuranquinone represented by the above formula (1-1) is described by FR Hewgill et al. (J. Chem. Soc.,
1964 , 408). That is, the above-mentioned dibenzofuranquinone (1-1) is the 4-hydroxydibenzofuran potassium nitrosodisulfonate (Flemie salt).
It is obtained by oxidizing with.

The electrophotographic photosensitive member of the present invention may be either a single layer type or a laminated type, but the effect of the use of the above-mentioned electron transfer agent is remarkably exhibited in the single layer type photosensitive member. The single-layer type electrophotographic photoreceptor is one in which a photosensitive layer is provided on a conductive substrate, and this photosensitive layer contains at least a charge-generating agent and a hole-transporting agent together with a dibenzofuranquinone derivative (1 ) Is contained in the binder resin.

This single-layer type photoconductor is applicable to both positive charging and negative charging, but it is particularly preferable to use the positive charging type. The single-layer type electrophotographic photoreceptor of the present invention has a significantly lower residual potential of the photoreceptor and improved sensitivity as compared with the conventional single-layer type electrophotographic photoreceptor. Further, -0.8 to -1.4 V is applied to the photosensitive layer of the single-layer type electrophotographic photosensitive member.
When the electron-accepting compound having the redox potential is contained, the electrons can be efficiently extracted from the charge generating agent, and the sensitivity of the photoconductor is further improved.

On the other hand, the laminated electrophotographic photosensitive member comprises a conductive substrate, on which at least a charge generation layer and a charge transport layer are provided in this order, and the dibenzofuranquinone derivative (1) is used as an electron transport agent in the charge transport layer. ) Is included. This laminated electrophotographic photosensitive member has a significantly lower residual potential and improved sensitivity than conventional laminated electrophotographic photosensitive members. Further, in order to transfer electrons from the charge generation layer to the charge transport layer more smoothly, it is preferable that the charge generation layer also contains the dibenzofuranquinone derivative (1).

In the laminated electrophotographic photosensitive member having at least a charge generation layer and a charge transport layer provided in this order on the conductive substrate, the charge generation layer has an oxidation-reduction potential of -0.8 to -1.4V. When containing an electron-accepting compound,
The sensitivity of the photoconductor is further improved. As described above, the dibenzofuranquinone derivative (1) has good solubility in a solvent and compatibility with a binder resin, and also has an excellent matching with a charge generating agent, which facilitates electron injection. In particular, it has an excellent electron transporting property in a low electric field.

Therefore, for example, in a positively charged single-layer type photoreceptor, the electrons released from the charge generating agent in the exposure step are smoothly injected into the electron transporting agent represented by the general formula (1). Then, by the transfer of electrons between the electron transfer agents,
The electrons move to the surface of the photosensitive layer and cancel the positive charge (+) charged on the surface of the photosensitive layer in advance. On the other hand, holes (+)
Is injected into the hole transport material, moves to the surface of the conductive substrate without being trapped, and cancels the negative charge (−) on the surface of the conductive substrate. In this way, it is considered that the sensitivity of the positively charged single-layer type photoreceptor is improved. The negatively charged single-layer type photoconductor only has the opposite direction of charge transfer from the above, and the sensitivity is similarly improved.

Further, in the positively charged layered photoreceptor, the electrons released from the charge generating agent in the charge generating layer in the exposure step become the electron transferring agent represented by the general formula (1) in the charge transferring layer. It is injected smoothly. Then, by the transfer of electrons between the electron transfer agents, the electrons move in the charge transport layer, reach the surface of the photosensitive layer, and cancel the positive charge (+) charged in advance on the surface of the photosensitive layer. On the other hand, holes (+) move directly from the charge generation layer to the surface of the conductive substrate, and cancel the negative charge (-) on the surface of the conductive substrate. In this way, it is considered that the sensitivity of the positively charged layered type photoreceptor is improved.

The charge generating agent, which absorbs light upon exposure to the photoreceptor, produces ion pairs [holes (+) and electrons (-)]. In order for the generated ion pairs to become free carriers and effectively cancel the surface charge, it is preferable that the ion pair recombine and disappear. Here, in the presence of an electron-accepting compound having a redox potential of −0.8 to −1.4 V, LUMO (an orbital having the lowest energy level among molecular orbitals having no electrons) Since the generated electrons usually move to this orbital), the energy level is lower than that of the charge generator, so that the electrons move to the electron-accepting compound during the formation of ion pairs, and the ion pairs are easily separated into carriers. Become. That is, the electron-accepting compound acts on the charge generation to improve the generation efficiency.

On the other hand, in order to have high sensitivity, it is also necessary that carrier traps due to impurities do not occur when free carriers move. Usually, a trap due to a small amount of impurities exists in the moving process of the free carrier, and the free carrier moves while repeating trap-detrap. Therefore, when the free carriers fall to a level where they cannot be untrapped, they become carrier traps and their movement is stopped.

When an electron-accepting compound having an oxidation-reduction potential of higher than -0.8 V is used, the separated free carriers are dropped to a level that cannot be detrapped, resulting in carrier traps. On the contrary, the redox potential is −
When an electron-accepting compound smaller than 1.4 V is used, the LUMO energy level becomes higher than that of the charge generating agent, and the electrons do not move to the electron-accepting compound during the generation of an ion pair, resulting in a charge generation efficiency. It is thought that this does not lead to the improvement of

As shown in FIG. 1, the above-mentioned oxidation-reduction potential was calculated using the following equation by obtaining E ₁ and E ₂ shown in the figure from the relationship between index voltage (V) and current (μA). . Redox potential (V) = (E ₁ + E ₂ ) / 2 The above index voltage (V) and current (μA) were measured by a three-electrode cyclic voltammetry using a measurement solution prepared by mixing the following materials. Measured.

Electrode: working electrode (glassy carbon electrode), counter electrode (platinum electrode) Reference electrode: silver nitrate electrode (0.1 mol / liter AgNO)
₃ - acetonitrile) Measurement solution electrolyte: perchlorate tetra -n- butylammonium 0.1 mol analyte: electron transporting agent 0.001 mol solvent: CH ₂ Cl ₂ 1 liters following the electrophotographic photosensitive member of the present invention Various materials used in the above will be described. <Hole Transfer Agent> Examples of the hole transfer agent include compounds represented by the following general formulas (HT1) to (HT13).

[0027]

[Chemical 4]

(In the formula, R⁸, R⁹, R^Ten, R¹¹, R¹²Oh
And R¹³Are the same or different and are hydrogen atom,
Child, an alkyl group which may have a substituent, and a substituent
An optionally substituted alkoxy group or an aryl group which may have a substituent
Represents a radical. a and b are the same or different and are 1 to 4
Represents an integer, and c, d, e and f are the same or different
Indicates an integer of 1 to 5. In addition, a, b, c, d, e or
When f is 2 or more, each R ⁸, R⁹, R^Ten, R¹¹, R¹²Oh
And R¹³May be different. )

[0029]

[Chemical 5]

(Wherein R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ and R
¹⁸ is the same or different and represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aryl group which may have a substituent. g, h, i and j are the same or different and are 1 to 5
Is shown, k shows the integer of 1-4. Note that g,
When h, i, j or k is 2 or more, each R ¹⁴ , R ¹⁵ , R
¹⁶ , R ¹⁷ and R ¹⁸ may be different. )

[0031]

[Chemical 6]

(In the formula, R ¹⁹ , R ²⁰ , R ²¹ and R ²² are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent or an alkoxy which may have a substituent. A group or an aryl group which may have a substituent is shown.
R ²³ is a hydrogen atom, a halogen atom, a cyano group, a nitro group,
The alkyl group which may have a substituent, the alkoxy group which may have a substituent, or the aryl group which may have a substituent are shown. m, n, o and p are the same or different and are 1
Indicates an integer of ˜5. q represents an integer of 1 to 6. In addition,
When m, n, o, p or q is 2 or more, each R ¹⁹ ,
R ²⁰ , R ²¹ , R ²² and R ²³ may be different. )

[0033]

[Chemical 7]

(In the formula, R ²⁴ , R ²⁵ , R ²⁶ and R ²⁷ are the same or different and each is a hydrogen atom, a halogen atom, an alkyl group which may have a substituent or an alkoxy which may have a substituent. A group or an aryl group which may have a substituent is shown.
r, s, t and u are the same or different and each represents an integer of 1 to 5. When r, s, t or u is 2 or more,
Each R ²⁴ , R ²⁵ , R ²⁶ and R ²⁷ may be different. )

[0035]

[Chemical 8]

(In the formula, R ²⁸ and R ²⁹ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. R ³⁰ , R ³¹ , R ³² and R ³³ are the same or different and are hydrogen. Indicates an atom, an alkyl group or an aryl group.)

[0037]

[Chemical 9]

(In the formula, R ³⁴ , R ³⁵ and R ³⁶ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group.)

[0039]

[Chemical 10]

(In the formula, R ³⁷ , R ³⁸ , R ³⁹ and R ⁴⁰ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group.)

[0041]

[Chemical 11]

(Wherein R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ and R
⁴⁵ is the same or different and represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. )

[0043]

[Chemical 12]

(In the formula, R ⁴⁶ represents a hydrogen atom or an alkyl group, R ⁴⁷ , R ⁴⁸ and R ⁴⁹ are the same or different,
A hydrogen atom, a halogen atom, an alkyl group or an alkoxy group is shown. )

[0045]

[Chemical 13]

(In the formula, R ⁵⁰ , R ⁵¹ and R ⁵² are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group.)

[0047]

[Chemical 14]

(In the formula, R ⁵³ and R ⁵⁴ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent or an alkoxy group which may have a substituent ^. And R ⁵⁶ is the same or different and represents a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent.)

[0049]

[Chemical 15]

(In the formula, R ⁵⁷ , R ⁵⁸ , R ⁵⁹ , R ⁶⁰ , R ⁶¹ and R ⁶² are the same or different and each have a hydrogen atom, an alkyl group which may have a substituent, or a substituent. Is an alkoxy group or an aryl group which may have a substituent.
Represents an integer of 1 to 10, and v, w, x, y, z and β
Are the same or different and are 1 or 2. Note that v,
When w, x, y, z or β is 2, each R ⁵⁷ , R ⁵⁸ , R
⁵⁹ , R ⁶⁰ , R ⁶¹ and R ⁶² may be different. )

[0051]

[Chemical 16]

(In the formula, R ⁶³ , R ⁶⁴ , R ⁶⁵ and R ⁶⁶ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, and Ar is

[0053]

[Chemical 17]

A group (Ar1), (Ar2) or (Ar3) represented by is shown. ) In the above-described hole transfer material, the alkyl group, aryl group, alkoxy group and halogen atom are the same as those described above. The substituent that may be substituted on the above groups,
For example, halogen atom, amino group, hydroxyl group, optionally esterified carboxyl group, cyano group, carbon number 1 to
Examples thereof include an alkyl group having 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and an alkenyl group having 2 to 6 carbon atoms which may have an aryl group. Further, the substitution position of the substituent is not particularly limited.

In the present invention, in addition to the above examples, conventionally known hole transporting substances, that is, for example, 2,5-
Oxadiazole compounds such as di (4-methylaminophenyl) -1,3,4-oxadiazole, 9- (4-
Styryl compounds such as diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, organic polysilane compounds, 1-phenyl-3- (p
-Pyrazoline compounds such as dimethylaminophenyl) pyrazolin, hydrazone compounds, triphenylamine compounds, indole compounds, oxazole compounds,
Nitrogen-containing cyclic compounds such as isoxazole-based compounds, thiazole-based compounds, thiadiazole-based compounds, imidazole-based compounds, pyrazole-based compounds and triazole-based compounds, condensed polycyclic compounds and the like can be used.

In the present invention, the charge transport agent is used alone or in combination of two or more. Further, when using a charge transport material having film-forming properties such as polyvinylcarbazole, the binder resin is not always necessary. In the present invention, among the hole transport materials, the ionization potential (Ip) is 4.8 to.
It is preferable to use the one of 5.6 eV and the electric field strength of 3
It is more preferable that the mobility is 1 × 10 ⁻⁶ cm ² / V · sec or more at × 10 ⁵ V / cm.

By using a hole transfer material having an ionization potential within the above range, the residual potential is further lowered,
The sensitivity is improved. The reason is not clear, but it is considered as follows. That is, the easiness of injecting charges from the charge generating agent into the hole transporting agent is closely related to the ionization potential of the hole transporting agent, and when the ionization potential of the hole transporting agent is larger than the above range. Is considered to cause a decrease in sensitivity due to a lower degree of charge injection from the charge generating agent to the hole transfer agent or a lower degree of hole transfer between the hole transfer agents. . On the other hand, in a system in which a hole transfer material and an electron transfer material coexist, it is necessary to pay attention to the interaction between them and more specifically to the formation of a charge transfer complex. When such a complex is formed between the two, recombination occurs between the holes and the electrons, and the mobility of the charge is lowered as a whole. When the ionization potential of the hole transfer material is smaller than the above range, the tendency to form a complex with the electron transfer material increases, and electron-hole recombination occurs, resulting in an apparent quantum yield. Is likely to decrease, resulting in a decrease in sensitivity.

When a bulky group is present in the electron transfer agent, the formation of the charge transfer complex can be suppressed by its steric hindrance. Therefore, it is preferable to introduce a bulky substituent into the dibenzofuranquinone derivative (1) used as the electron transfer agent in the present invention. <Electron-Accepting Compound> The electron-accepting compound is not particularly limited, except that it is a compound having an electron-accepting property and an oxidation-reduction potential of −0.8 to −1.4 V, and examples thereof include benzoquinone compounds. , Naphthoquinone type, anthraquinone type, diphenoquinone type, malononitrile, thiopyran type compound, 2,4,8-trinitrothioxanthone, 3,
Fluorenone compounds such as 4,5,7-tetranitro-9-fluorenone, dinitroanthracene, dinitroacridine, nitroanthraquinone and dinitroanthraquinone can be used. Of these, the diphenoquinone system, in particular, has a quinone system oxygen atom with excellent electron acceptability bound to the end of the molecular chain and also has a conjugated double bond over the entire long molecular chain. It is particularly preferable because it has the advantage that it is easy and the transfer of electrons is easy. Further, each electron-accepting compound described above contributes to the generation of charges.

Examples of the benzoquinone compounds include p-benzoquinone, 2,6-dimethyl-p-benzoquinone and 2,6-di-t-butyl-p-benzoquinone. Examples of the diphenoquinone compound include those represented by the general formula (10):

[0060]

[Chemical 18]

(Wherein R ¹⁷⁰ , R ¹⁷¹ , R ¹⁷² and R
¹⁷³ are the same or different and each represents a hydrogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, or a substituent. A good aralkyl group, a cycloalkyl group which may have a substituent or an amino group which may have a substituent is shown. However, two of R ¹⁷⁰ , R ¹⁷¹ , R ^172, and R ¹⁷³ are the same group. Among the compounds represented by the formula (4), those having an oxidation-reduction potential within the above range can be mentioned.

In the above general formula (10), the substituents R ¹⁷⁰ to
^Examples of the alkyl group, alkoxy group and aryl group corresponding to R ¹⁷³ include the same groups as described above. As the aralkyl group, for example, benzyl, benzhydryl, trityl, phenethyl and the like have 1 to 1 carbon atoms in the alkyl group moiety.
There are six groups. Examples of the cycloalkyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and other cycloalkyl groups having 3 to 6 carbon atoms. Examples of the amino group which may have a substituent include, in addition to the amino group, monomethylamino, dimethylamino, monoethylamino, diethylamino groups and the like.

The diphenoquinone compound (10) usable in the present invention is, for example, 3,5-dimethyl-3 ', 5'.
-Di-t-butyl-4,4'-diphenoquinone, 3,3 '
-Dimethyl-5,5'-dit-butyl-4,4'-diphenoquinone, 3,5'-dimethyl-3 ', 5-dit-butyl-4,4'-diphenoquinone, 3,3', 5 , 5 '
-Tetra-t-butyl-4,4'-diphenoquinone and the like. These diphenoquinone compounds are used alone or in combination of two or more. <Charge Generating Agent> Examples of the charge generating agent include compounds represented by the following general formulas (CG1) to (CG12). (CG1) Metal-free phthalocyanine (PcH ₂ )

[0064]

[Chemical 19]

(CG2) Titanyl phthalocyanine (PcTi
O)

[0066]

[Chemical 20]

(CG3) Perylene pigment

[0068]

[Chemical 21]

(In the formula, R ⁷⁰ and R ⁷¹ are the same or different and each represents a substituted or unsubstituted alkyl group, cycloalkyl group, aryl group, alkanoyl group or aralkyl group having 18 or less carbon atoms.) (CG4 ) Bisazo pigment

[0070]

[Chemical formula 22]

[Wherein A ¹ and A ² are the same or different and each represents a coupler residue, and X is

[0072]

[Chemical formula 23]

(In the formula, R ⁷² represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group, and the alkyl group, the aryl group or the heterocyclic group may have a substituent n.
Represents 0 or 1. )

[0074]

[Chemical formula 24]

[0075]

[Chemical 25]

(In the formula, R ⁷³ and R ⁷⁴ are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogen atom, an alkoxy group, an aryl group or an aralkyl group.)

[0077]

[Chemical formula 26]

[0078]

[Chemical 27]

[0079]

[Chemical 28]

(In the formula, R ⁷⁵ represents a hydrogen atom, an ethyl group, a chloroethyl group or a hydroxyethyl group.)

[0081]

[Chemical 29]

Or

[0083]

[Chemical 30]

(Wherein R ⁷⁶ , R ⁷⁷ and R ⁷⁸ are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogen atom, an alkoxy group, an aryl group or an aralkyl group). . ] (CG5) Dithioketopyrrolopyrrole pigment

[0085]

[Chemical 31]

(In the formula, R ⁷⁹ and R ⁸⁰ are the same or different and represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and R ⁸¹ and R ⁸² are the same or different and are a hydrogen atom, an alkyl group or an aryl group. (CG6) Metal-free naphthalocyanine pigment

[0087]

[Chemical 32]

(In the formula, R ⁸³ , R ⁸⁴ , R ⁸⁵ and R ⁸⁶ are the same or different and each represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom.) (CG7) Metal naphthalocyanine pigment

[0089]

[Chemical 33]

(In the formula, R ⁸⁷ , R ⁸⁸ , R ⁸⁹ and R ⁹⁰ are the same or different and each represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and M represents Ti or V.) (CG8) Squaraine pigment

[0091]

[Chemical 34]

(In the formula, R ⁹¹ and R ⁹² are the same or different and each represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom.) (CG9) Trisazo pigment

[0093]

[Chemical 35]

(In the formula, Cp ₁ , Cp ₂ and Cp ₃ are the same or different and represent a coupler residue.) (CG10) Indigo pigment

[0095]

[Chemical 36]

(In the formula, R ⁹³ and R ⁹⁴ are the same or different and each represents a hydrogen atom, an alkyl group or an aryl group,
Z represents an oxygen atom or a sulfur atom. ) (CG11) Azurenium pigment

[0097]

[Chemical 37]

(In the formula, R ⁹⁵ and R ⁹⁶ are the same or different and each represents a hydrogen atom, an alkyl group or an aryl group.) (CG12) Cyanine pigment

[0099]

[Chemical 38]

(Wherein R ⁹⁷ and R ⁹⁸ are the same or different and represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and R ⁹⁹ and R ¹⁰⁰ are the same or different and are a hydrogen atom, an alkyl group or an aryl group. In the above-mentioned charge generating agent, the alkyl group is
The same groups as mentioned above can be mentioned. The alkyl group having 1 to 5 carbon atoms is the above-mentioned alkyl group having 1 to 6 carbon atoms with hexyl removed. The substituted or unsubstituted alkyl group having 18 or less carbon atoms is a group containing octyl, nonyl, decyl, dodecyl, tridecyl, pentadecyl, octadecyl and the like in addition to the above-mentioned alkyl group having 1 to 6 carbon atoms. Examples of the cycloalkyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,
Examples thereof include groups having 3 to 8 carbon atoms such as cycloheptyl and cyclooctyl. Examples of the alkoxy group, aryl group and aralkyl group include the same groups as described above. Examples of the alkanoyl group include a formyl group, an acetyl group, a propionyl group, a butyryl group, a pentanoyl group and a hexanoyl group.

Examples of the heterocyclic group include thienyl, pyrrolyl, pyrrolidinyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, 2H.
-Imidazolyl, pyrazolyl, triazolyl, tetrazolyl, pyranyl group, pyridyl, piperidyl, piperidino, 3-morpholinyl, morpholino, thiazolyl and the like. It may also be a heterocyclic group condensed with an aromatic ring.

Substituents which may be substituted on the above groups include
For example, a halogen atom, an amino group, a hydroxyl group, a carboxyl group which may be esterified, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 2 to 2 carbon atoms. And the alkenyl group of 6 and the like. Examples of the coupler residue represented by A ¹ , A ² and Cp ₁ , Cp ₂ , Cp ₃ include those represented by the following general formula (2
The groups shown in 1) to (29) are mentioned.

[0103]

[Chemical Formula 39]

[0104]

[Chemical 40]

In each formula, R ¹²⁰ represents a carbamoyl group, a sulfamoyl group, an allofanoyl group, an oxamoyl group, an anthraniloyl group, a carbazoyl group, a glycyl group, a hydantoyl group, a phthalamoyl group or a succinamoyl group. These groups, a halogen atom, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a nitro group, a cyano group, an alkyl group, an alkenyl group,
It may have a substituent such as a carbonyl group or a carboxyl group.

R ¹²¹ represents an atomic group necessary for being condensed with a benzene ring to form an aromatic ring, a polycyclic hydrocarbon or a heterocycle, and these rings have a substituent similar to the above. May be. R ¹²² represents an oxygen atom, a sulfur atom or an imino group. R ¹²³ represents a divalent chain hydrocarbon group or an aromatic hydrocarbon group, and these groups may have the same substituents as described above.

R ¹²⁴ represents an alkyl group, an aralkyl group, an aryl group or a heterocyclic group, and these groups may have the same substituents as described above. R ¹²⁵ is a divalent chain hydrocarbon group, an aromatic hydrocarbon group or the above general formulas (25) to (28)
In the following formula:

[0108]

[Chemical 41]

It represents an atomic group necessary for forming a heterocycle with the moiety represented by, and these rings may have the same substituents as described above. R ¹²⁶ represents a hydrogen atom, an alkyl group, an amino group, a carbamoyl group, a sulfamoyl group, an allofanoyl group, a carboxyl group, an alkoxycarbonyl group, an aryl group or a cyano group, and groups other than the hydrogen atom have the same substituents as described above. You may have.

R ¹²⁷ represents an alkyl group or an aryl group, and these groups may have the same substituents as described above. Examples of the alkenyl group include vinyl, allyl, 2-butenyl, 3-butenyl, 1-methylallyl, 2-pentenyl and 2-hexenyl alkenyl groups having 2 to 6 carbon atoms. .

Examples of the atomic group necessary for forming an aromatic ring by condensing with the benzene ring in the above R ¹²¹ include alkylene groups such as methylene group, ethylene group, propylene group and butylene group. Examples of the aromatic ring formed by the condensation of R ¹²¹ and the benzene ring include naphthalene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, and naphthacene ring.

In the above R ¹²¹ , the atomic group necessary for condensation with a benzene ring to form a polycyclic hydrocarbon is, for example, a methylene group, an ethylene group, a propylene group or a butylene group having 1 to 4 carbon atoms. The alkylene group of Examples of the atomic group necessary for forming a polycyclic hydrocarbon by condensing with the benzene ring in R ¹²¹ include a carbazole ring, a benzocarbazole ring, a dibenzofuran ring, and the like.

Further, in R ¹²¹ , the atomic group necessary for condensing with the benzene ring to form a heterocycle is, for example, a benzofuranyl group, a benzothiophenyl group, an indolyl group, a 1H-indolyl group, a benzoxazolyl group. Group, benzothiazolyl group, 1H-indaryl group, benzimidazolyl group, chromenyl group, chromanyl group, isochromanyl group, quinolinyl group, isoquinolinyl group, cinnolinyl group, phthalazinyl group, quinazonilyl group, quinoxalinyl group, dibenzofuranyl group, carbazolyl group, xanthenyl group , Acridinyl group, phenanthridinyl group, phenazinyl group, phenoxazinyl group, thianthrenyl group and the like.

Examples of the aromatic heterocyclic group formed by the condensation of R ¹²¹ and the benzene ring include, for example, thienyl group, furyl group, pyrrolyl group, oxazolyl group, isoxazolyl group, thiazolyl group, isothiazolyl group, imidazolyl group, Examples thereof include a pyrazolyl group, a triazolyl group, a tetrazolyl group, a pyridyl group and a thiazolyl group. Also,
Further, it may be a heterocyclic group condensed with another aromatic ring (for example, a benzofuranyl group, a benzimidazolyl group, a benzoxazolyl group, a benzothiazolyl group, a quinolyl group, etc.).

In R ¹²³ and R ¹²⁵ , examples of the divalent chain hydrocarbon include ethylene group, propylene group and butylene group, and examples of the divalent aromatic hydrocarbon include phenylene group, naphthylene group, Examples thereof include a phenanthrylene group. ^Examples of the heterocyclic group for R ¹²⁴ include a pyridyl group, a pyrazyl group, a thienyl group, a pyranyl group and an indolyl group.

In R ¹²⁵ , the atomic groups necessary to form a heterocycle with the moieties represented by the formulas (30) and (31) are, for example, phenylene group, naphthylene group, phenanthrylene group, ethylene group, Examples thereof include a propylene group and a butylene group. Examples of the aromatic heterocyclic group formed by R ¹²⁵ and the moieties represented by the formulas (30) and (31) include a benzimidazole group, a benzo [f] benzimidazole group, a dibenzo [e, g] Benzimidazole group, benzopyrimidine group and the like. These groups may have the same substituents as described above.

Examples of the alkoxycarbonyl group for R ¹²⁶ include methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group and the like. In the present invention, in addition to the charge generating agents exemplified above, for example, selenium, selenium-tellurium, amorphous silicon, pyrylium salts, ansanthuron pigments, triphenylmethane pigments, slene pigments, toluidine pigments, pyrazoline pigments. Conventionally known charge generating agents such as quinacridone pigments can be used.

The charge generating agents exemplified above may be used alone or in combination of two or more so as to have an absorption wavelength in a desired region. At that time, in connection with the use of a hole transfer agent having an ionization potential of 4.8 to 5.6 eV, a charge generating agent having a balance with this hole transfer agent, specifically, an ionization potential of 4.8-6.0e
It is preferable to use a charge generating agent having V, particularly 5.0 to 5.8 eV, from the viewpoint of reducing the residual potential and improving the sensitivity.

Particularly suitable charge generating agents are phthalocyanine pigments such as X-type metal-free phthalocyanine and oxotitanyl phthalocyanine, perylene pigments and bisazo pigments. Among the charge generating agents exemplified above, the phthalocyanine pigment is suitable as a charge generating material for a photoreceptor having sensitivity in a wavelength region of 700 nm or more. That is, since the phthalocyanine-based pigment is excellent in matching with the compound (electron transfer agent) represented by the general formula (1), the electrophotographic photoreceptor using both of them has high sensitivity in the above wavelength range. Therefore, it can be suitably used for an image forming apparatus of a digital optical system using a light source having a wavelength of 700 nm or more.

Among the above-mentioned perylene pigments represented by the general formula (CG3), among the perylene pigments represented by the general formula (1)
1):

[0121]

[Chemical 42]

(Wherein R ¹³⁰ , R ¹³¹ , R ¹³² and R
¹³³ is the same or different and represents a hydrogen atom, an alkyl group, an alkoxyl group or an aryl group. The compound represented by) is preferably used. In the general formula (11), examples of the alkyl group, alkoxy group and aryl group corresponding to the substituents R ^{130 to} R ¹³³ include the same groups as described above.

This perylene pigment is suitable as a charge generating material for a photosensitive member having a sensitivity in the visible region. That is, the perylene-based pigment (11) is excellent in matching with the compound (electron transfer agent) represented by the general formula (1), and the electrophotographic photoreceptor using both of them has high sensitivity in the visible region. Therefore, it can be suitably used for an image forming apparatus of an analog optical system using a light source having a wavelength in the visible region. <Binder Resin> As the binder resin for dispersing the above components, various resins conventionally used in the photosensitive layer can be used. For example, a styrene polymer and a styrene-butadiene copolymer Coal, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, Ionomer, vinyl chloride-vinyl acetate copolymer, polyester,
Alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin,
Thermoplastic resin such as polyether resin, polyester resin, silicone resin, epoxy resin, phenol resin,
Examples thereof include urea resins, melamine resins, other crosslinkable thermosetting resins, and photocurable resins such as epoxy acrylate and urethane-acrylate. These binder resins can be used alone or in combination of two or more. Suitable resins are styrene polymers, acrylic polymers, styrene-acrylic copolymers, polyesters, alkyd resins, polycarbonates, polyarylates and the like.

Next, a method for manufacturing the electrophotographic photosensitive member of the present invention will be described. In order to obtain a single-layer type electrophotographic photosensitive member, a predetermined electron transfer agent is dissolved or dispersed in a suitable solvent together with a charge generating agent, a hole transfer agent, a binder resin, etc. It may be applied on a conductive substrate and dried. In the case of a single-layer type photoreceptor, the binder resin 1
0.1 to 50 parts by weight of the charge generating agent with respect to 00 parts by weight,
The amount is preferably 0.5 to 30 parts by weight, and the electron transfer agent is 5 to 100 parts by weight, preferably 10 to 80 parts by weight. Further, the hole transport material is 5 to 500
It is blended in a proportion of parts by weight, preferably 25 to 200 parts by weight. Further, it is suitable that the total amount of the hole transfer agent and the electron transfer agent is 20 to 500 parts by weight, preferably 30 to 200 parts by weight, based on 100 parts by weight of the binder resin. When the single-layer type photosensitive layer contains an electron-accepting compound, the electron-accepting compound is added in an amount of 0.1 to 100 parts by weight of the binder resin.
It is suitable to add 40 parts by weight, preferably 0.5 to 20 parts by weight.

The thickness of the single-layer type photosensitive layer is 5 to 100.
μm, preferably 10 to 50 μm. In order to obtain a laminated type electrophotographic photoreceptor, first, a charge generation layer containing a charge generation agent is formed on a conductive substrate by means such as vapor deposition or coating, and then an electron transfer agent is formed on this charge generation layer. A coating liquid containing a binder resin and a binder resin may be applied by means such as coating and dried to form the charge transport layer.

In the multi-layer type photoreceptor, the charge generating agent and the binder resin constituting the charge generating layer may be used in various proportions, but the charge generating agent may be added to 100 parts by weight of the binder resin. 5 to 1000 parts by weight, preferably 30 to 500
It is suitable to mix in a ratio of parts by weight. When the charge-generating layer contains an electron-accepting compound, the electron-accepting compound is added in an amount of 0.1-40 parts by weight, preferably 0.5-20 parts by weight, based on 100 parts by weight of the binder resin. Appropriate. When the charge generation layer contains an electron transfer agent, the electron transfer agent is added to the binder resin in an amount of 0.
It is suitable to add 5 to 50 parts by weight, preferably 1 to 40 parts by weight.

The electron-transporting agent and the binder resin constituting the charge-transporting layer can be used in various proportions within a range that does not hinder the transport of charge and a range that does not crystallize. In order to easily transport the generated charge, 10 to 10 parts by weight of the electron transfer agent may be added to 100 parts by weight of the binder resin.
It is suitable to mix it in an amount of 500 parts by weight, preferably 25 to 100 resin. When the charge transport layer contains an electron-accepting compound, the electron-accepting compound is added to the binder resin 10
0.1 to 40 parts by weight, preferably 0.
It is suitable to add 5 to 20 parts by weight.

The thickness of the laminated type photosensitive layer is about 0.01 to 5 μm, preferably 0.1 to 3 μm for the charge generation layer.
The charge transport layer has a thickness of 2 to 100 μm, preferably 5 to 50 μm. In the case of a single-layer type photoreceptor, between the conductive base and the photosensitive layer, and in the case of the multilayer type photoreceptor, between the conductive base and the charge generation layer, the conductive base and the charge transport layer. Between or between the charge generation layer and the charge transport layer,
A barrier layer may be formed in a range that does not impair the characteristics of the photoreceptor. Further, a protective layer may be formed on the surface of the photoconductor.

Each of the single-layer type and multi-layer type photosensitive layers has various additives known per se, such as an antioxidant, a radical scavenger, a singlet quencher, within a range that does not adversely affect electrophotographic properties. A deterioration inhibitor such as an ultraviolet absorber, a softener, a plasticizer, a surface modifier, a bulking agent, a thickener, a dispersion stabilizer, a wax, an acceptor, a donor and the like can be added. Further, in order to improve the sensitivity of the photosensitive layer,
For example, known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generating agent.

Further, together with the compound represented by the general formula (1), various electron transfer agents having a high electron transfer ability may be contained in the photosensitive layer. Examples of such an electron transfer agent include, in addition to the diphenoquinone compounds and benzoquinone compounds represented by the general formula (10), the following general formula:
Examples thereof include compounds represented by (ET1) to (ET13).

[0131]

[Chemical 43]

(In the formula, R ¹⁴² , R ¹⁴³ , R ¹⁴⁴ , R ¹⁴⁵
And R ¹⁴⁶ are the same or different and each have a hydrogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, and a substituent. Represents an optionally substituted aralkyl group, an optionally substituted phenoxy group or a halogen atom. )

[0133]

[Chemical 44]

(Wherein R ¹⁴⁷ is an alkyl group, R ¹⁴⁸ is an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, a substituent Represents an aralkyl group which may have a group, a halogen atom or a halogenated alkyl group, and γ represents an integer of 0 to 5.
When γ is 2 or more, each R ¹⁴⁸ may be different from each other. )

[0135]

[Chemical formula 45]

(In the formula, R ¹⁴⁹ and R ¹⁵⁰ are the same or different and each represents an alkyl group. Δ represents an integer of 1 to 4 and ε represents an integer of 0 to 4. Note that δ and ε are 2 In the above case, each R ¹⁴⁹ and R ¹⁵⁰ may be different.)

[0137]

[Chemical formula 46]

(In the formula, R ¹⁵¹ represents an alkyl group, an aryl group, an aralkyl group, an alkoxy group, a halogenated alkyl group or a halogen atom. Ζ is 0 to 4 and η is 0 to 5).
Is an integer. When η is 2 or more, each R ¹⁵¹ may be different. )

[0139]

[Chemical 47]

(In the formula, θ is an integer of 1 to 2.)

[0141]

[Chemical 48]

(In the formula, R ¹⁵² represents an alkyl group, and σ is an integer of 1 to 4. When σ is 2 or more, each R
¹⁵² may be different. )

[0143]

[Chemical 49]

(In the formula, R ¹⁵³ and R ¹⁵⁴ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an aralkyloxycarbonyl group, an alkoxy group, a hydroxyl group, a nitro group or a cyano group. Basis:
Indicates O, N-CN or C (CN) ₂ . )

[0145]

[Chemical 50]

(In the formula, R ¹⁵⁵ represents a hydrogen atom, a halogen atom, an alkyl group or a phenyl group which may have a substituent, and R ¹⁵⁶ represents a hydrogen atom, a halogen atom or an alkyl group which may have a substituent, A phenyl group, an alkoxycarbonyl group, an N-alkylcarbamoyl group, a cyano group or a nitro group which may have a substituent is shown.
Is an integer of 1 to 3. When λ is 2 or more, each R
¹⁵⁶ may be different from each other. )

[0147]

[Chemical 51]

(In the formula, R ¹⁵⁷ is a hydrogen atom, an alkyl group which may have a substituent, a phenyl group which may have a substituent, a halogen atom, an alkoxycarbonyl group, N
-Indicates an alkylcarbamoyl group, a cyano group or a nitro group. μ is an integer of 1 to 3. When μ is 2 or more, each R ¹⁵⁷ may be different from each other. )

[0149]

[Chemical 52]

(In the formula, R ¹⁵⁸ and R ¹⁵⁹ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, a cyano group, a nitro group or an alkoxycarbonyl group. Ν and ξ are It is an integer of 1 to 3. When ν or ξ is 2 or more, each R ¹⁵⁸ and R ¹⁵⁹ may be different from each other.)

[0151]

[Chemical 53]

(In the formula, R ¹⁶⁰ and R ¹⁶¹ are the same or different and each represents a phenyl group, a polycyclic aromatic group or a heterocyclic group, and these groups may have a substituent.)

[0153]

[Chemical 54]

(In the formula, R ¹⁶² represents an amino group, a dialkylamino group, an alkoxy group, an alkyl group or a phenyl group, and π is an integer of 1 to 2. When π is 2,
Each R ^{16 2} may be different from each other. )

[0155]

[Chemical 55]

(In the formula, R ¹⁶³ is a hydrogen atom, an alkyl group,
An aryl group, an alkoxy group or an aralkyl group is shown. ) And the like, and further malononitrile, thiopyran-based compound, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, Examples include dibromomaleic anhydride.

In the electron transfer agent exemplified above, the alkyl group, alkoxy group, aryl group, aralkyl group, halogenated alkyl group, halogen atom and heterocyclic group are the same as described above. Examples of the polycyclic aromatic group include a naphthyl group, a phenanthryl group and an anthryl group.

Substituents which may be substituted on the above groups include
For example, a halogen atom, an amino group, a hydroxyl group, a carboxyl group which may be esterified, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 2 to 2 carbon atoms. And the alkenyl group of 6 and the like. As the conductive substrate used in the photoreceptor of the present invention, various materials having conductivity can be used, for example, aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, Titanium,
Examples include simple metals such as nickel, palladium, indium, stainless steel, and brass, plastic materials obtained by vapor deposition or laminating of the above metals, and glass coated with aluminum iodide, tin oxide, indium oxide, or the like.

The conductive substrate may be in the form of a sheet, a drum or the like, as long as the substrate itself has conductivity or the surface of the substrate has conductivity. Further, it is preferable that the conductive substrate has sufficient mechanical strength when used. The photosensitive layer according to the present invention is manufactured by coating a coating solution prepared by dissolving or dispersing a resin composition containing each of the above components in a solvent on a conductive substrate and drying the coating solution.

That is, the charge generating agent, charge transporting agent, binder resin and the like exemplified above are used together with a suitable solvent by a known method such as roll mill, ball mill, attritor, paint shaker or ultrasonic disperser. The coating liquid may be prepared by dispersing and mixing, and the coating liquid may be coated and dried by a known means. As the solvent for forming the coating liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol, aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, benzene, Aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, cyclohexanone, etc. Examples thereof include ketones, esters such as ethyl acetate and methyl acetate, dimethylformaldehyde, dimethylformamide, dimethylsulfoxide and the like. These solvents can be used alone or in combination of two or more.

Further, in order to improve the dispersibility of the charge transport material or the charge generating material and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent, etc. may be used.

[0162]

EXAMPLES The electrophotographic photoreceptor of the present invention will be described below with reference to examples. The components used in the electrophotographic photoreceptor of the present invention are as follows. (i) Charge generating agent PcH ₂ : X-type metal-free phthalocyanine [ionization potential (Ip) = 5.38 eV] PcTiO: oxotitanyl phthalocyanine (Ip =
5.32 eV) Perylene: Perylene pigment in which all of the substituents R ^{130 to} R ¹³³ of the general formula (11) are methyl groups (Ip = 5.50e).
V) (ii) Hole transport material 7-1: Benzidine derivative (Ip) represented by the following formula (7-1):
= 5.56 eV)

[0163]

[Chemical 56]

(Iii) Electron Transfer Agent 1-1: Dibenzofuranquinone derivative represented by the above formula (1-1) C: 3,5-dimethyl-3 ′, 5′-dit-butyl-
4,4'-Diphenoquinone (iv) electron-accepting compound A: p-benzoquinone (oxidation-reduction potential = -0.81 V) B: 2,6-di-t-butyl-p-benzoquinone (oxidation-reduction potential = -1. 30V) C: 3,5-dimethyl-3 ', 5'-di-t-butyl-
4,4'-diphenoquinone (redox potential = -0.86
V) D: 3,3 ′, 5,5′-tetra-t-butyl-4,4 ′
-Diphenoquinone (oxidation-reduction potential = -0.94V) The ionization potential was measured using an atmospheric photoelectron analyzer (AC-1 manufactured by Riken Keiki Co., Ltd.). [Production of Single-Layer Electrophotographic Photoreceptor for Digital Light Source] Examples 1 and 2 and Comparative Examples 1 to 3 Were mixed in the proportions shown below and mixed and dispersed for 50 hours with a ball mill to prepare a single-layer type photosensitive layer coating solution.

(Component) (Parts by Weight) Charge Generating Agent 5 Hole Transporting Agent 50 Electron Transporting Agent 30 Binder Resin (Polycarbonate) 100 Solvent (Tetrahydrofuran) 800 Next, the above coating liquid is applied to aluminum as a conductive base material. A single layer type electrophotographic photoreceptor for a digital light source having a film thickness of 15 to 20 μm was prepared by applying the dip coating method on the surface of the blank tube and drying with hot air at 100 ° C. for 60 minutes. Examples 3 to 6 5 parts by weight of charge generating agent, 50 parts by weight of hole transferring material, 30 parts by weight of electron transferring material, 100 parts by weight of binder resin and 800 parts of solvent.
In addition to 10 parts by weight of an electron-accepting compound in addition to 1 part by weight, a single-layer type photosensitive layer coating solution was prepared, and Example 5 was used.
A single-layer type electrophotographic photosensitive member for digital light source was prepared in the same manner as in. [Production of Laminated Electrophotographic Photoreceptor for Digital Light Source] Example 7 and Comparative Example 4 100 parts by weight of a charge generating agent (PcH ₂ ), 100 parts by weight of a binder resin (polyvinyl butyral) and 2000 parts by weight of a solvent (tetrahydrofuran). A ball mill was mixed and dispersed for 50 hours to prepare a coating solution for the charge generation layer. And
This coating solution was applied to the surface of an aluminum base tube, which is a conductive base material, by a dip coating method, and dried with hot air at 100 ° C. for 60 minutes to form a charge generation layer having a film thickness of 1 μm.

Next, 100 parts by weight of the electron transport material and the binding tree
100 parts by weight of fat (polycarbonate) and solvent (torr)
EN) 800 parts by weight are mixed and dispersed in a ball mill for 50 hours.
Then, a coating liquid for the charge transport layer was prepared. And this paint
Apply the cloth liquid on the charge generation layer by dip coating method.
And dried with hot air at 100 ° C. for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer is formed to provide a laminated electrophotographic feel for digital light sources.
An optical body was produced. [Preparation of single-layer electrophotographic photoreceptor for analog light source] Example 8 and Comparative Examples 5-6 Example except that a perylene pigment was used as the charge generating agent
5-6 or the same as Comparative Examples 1-3, single-layer electrophotography
A photoconductor was prepared. [Preparation of laminated electrophotographic photoreceptor for analog light source] Example 9 and Comparative Example 7 Example except that a perylene pigment was used as the charge generating agent
12 or a laminated electrophotographic photoreceptor in the same manner as in Comparative Example 7.
Was produced. (Evaluation of Photoreceptor Characteristics) Obtained in Examples and Comparative Examples above.
Conducted the following photosensitivity test on the electrophotographic photoreceptor and
The sensitivity characteristics of were evaluated. In addition, the photoconductor for digital light source
Photosensitivity test I for
Test II was conducted. Photosensitivity test I Drum sensitivity tester made by GENTEC
By applying an applied voltage to the surface of the photoconductor,
It was charged to 700V. Next, the exposure light source (halogen
Wave) extracted using a bandpass filter from
Long 780 nm (half-width 20 nm), light intensity 16 μW / c
m²Irradiate (780 nm) monochromatic light onto the surface of the photoconductor (illumination
The exposure time is 80 milliseconds), and 330 milliseconds have elapsed from the start of exposure.
The surface potential at the time of_LMeasured as (V)
Decided Photosensitivity test II White light from a halogen lamp for exposure (light intensity 147 μW / c
m²), Except that the irradiation time is 50 milliseconds
As in the photosensitivity test I, the post-exposure potential V _L(V)
Was measured.

Table 1 shows the measurement results of the components used in the above Examples and Comparative Examples and the post-exposure potential V _L.

[0168]

[Table 1]

As is clear from Table 1, the photoconductors of Examples 1 to 9 using the dibenzofuranquinone derivative (1) of the present invention as the electron transfer agent, use the diphenoquinone derivative as the electron transfer agent or the electron transfer agent. It can be seen that the post-exposure potential is lower than that of the photoconductor of the comparative example in which no agent is used, and the photoconductor has high sensitivity. Example 3 containing an electron-accepting compound having a predetermined redox potential
The photoconductors # 6 to # 6 have even higher sensitivity than the other examples.

[0170]

Since the dibenzofuranquinone derivative (1) has a high electron transporting ability, the residual potential of the electrophotographic photosensitive member of the present invention containing the dibenzofuranquinone derivative (1) as an electron transferring agent is remarkably lowered. And has high sensitivity. Further, by adding an electron-accepting compound having a specific redox potential, the residual potential is further lowered, and a photoreceptor having improved sensitivity can be obtained.

Therefore, when the photoconductor of the present invention is used, the speed of copying machines, printers and the like can be increased.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a traction voltage (V) and a current (A) for obtaining a redox potential in the present invention.

FIG. 2 is an infrared absorption spectrum of a dibenzofuranquinone derivative represented by the formula (1-1).

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-1-138561 (JP, A) JP-A-4-300971 (JP, A) JP-A-6-123983 (JP, A) JP-A-4- 360885 (JP, A) JP 5-45908 (JP, A) JP 5-45915 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 5/06 315

Claims (2)

(57) [Claims] 1. An electrophotographic photoreceptor having a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer has the general formula (1): (In the formula, R ¹ , R ² , R ³ and R ⁴ are the same or different and each is a hydrogen atom or an alkyl group which may have a substituent,
The aryl group which may have a substituent, the alkoxy group which may have a substituent, the acyl group which may have a substituent, or a halogen atom is shown. ) The electrophotographic photoreceptor containing a dibenzofuranquinone derivative represented by 2. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains an electron-accepting compound having an oxidation-reduction potential of -0.8 to -1.4V.