JP2752861B2 - 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 utilizing an electrophotographic method, such as an electrostatic copying machine or a laser beam printer.

[0002]

2. Description of the Related Art An electrophotographic method such as the Carlson process includes a step of uniformly charging the surface of an electrophotographic photosensitive member by corona discharge, and a step of exposing the charged surface of the electrophotographic photosensitive member to an electrostatic latent image. An exposure step of forming an image, a developing step of bringing a developer into contact with the formed electrostatic latent image, and developing the electrostatic latent image into a toner image with toner contained in the developer; And a fixing step of fixing the transferred toner image, and after the transfer step,
A cleaning step of removing toner remaining on the photoconductor.

In recent years, electrophotographic photoreceptors used in the above electrophotographic method have been replaced with inorganic photoconductors such as selenium and cadmium sulfide which are difficult to handle due to their toxicity. Various so-called organic photoreceptors using an organic photoconductive compound having low toxicity have been proposed. Such an organic photoreceptor is advantageous in that it has good workability, is easy to manufacture, and has a high degree of freedom in functional design.

In such organic photoreceptors, generally, a function-separated type photosensitive layer containing a charge generating material for generating charges by light irradiation and a charge transporting material for transporting the generated charges is often used. . As a charge generation material used in the electrophotographic photoreceptor, JP-A-1-202775 discloses a specific bisazo pigment. This bisazo pigment is represented by the following general formula (1).

[0005]

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Wherein A ¹ and A ² are the same or different and represent a coupler residue, and R ¹ represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group. The heterocyclic group may have a substituent, and n represents 0 or 1.) Such a bisazo pigment (1)
Has the advantages of being stable to heat and light, having high charge generation efficiency, high sensitivity, and excellent repetition characteristics.

[0007]

By the way, in order to produce a function-separated organic photoreceptor using a charge generation material and a charge transport material, sensitivity, potential holding property, potential stability,
It is necessary to select a good matching material that satisfies all the electrophotographic characteristics such as the residual potential. For example, no matter how much a charge generating material generates a sufficient charge, satisfactory electrophotographic characteristics cannot be obtained unless the charge is efficiently combined with a charge transporting material capable of transporting the charge. .

According to the above-mentioned Japanese Patent Application Laid-Open No. 1-220257, the bisazo pigment represented by the general formula (1) is used in combination with various charge transporting materials (carrier-transferring substances), thereby reducing heat and light. It is disclosed that a stable photosensitive member can be obtained. However, the bisazo pigments (1) disclosed in the above publications include phthalocyanine-based and perylene-based pigments, fluorenone-type bisazo pigments (JP-A-57-96345) which are commonly used charge generating materials, and a perinone skeleton. Oxadiazole-type azo pigments having a coupler having a characteristic (e.g., JP-A-59-229564) are more susceptible to oxidative deterioration due to ozone, nitrogen oxides NOx, light and the like generated in a copying machine. There is a drawback that characteristics tend to deteriorate. It is presumed that such oxidative deterioration of the bisazo pigment (1) occurs because ozone and the like are adsorbed to the azo group to decompose the azo group.

Such oxidative deterioration is caused by the above-mentioned bisazo pigment.
(1) is accelerated when used in combination with a charge transporting material that is an electron donating compound. This is because, when the electron donating compound has a strong basicity, the electron donating compound coordinates to the azo group and increases the electron density of the azo group, which makes the compound more susceptible to attack by ozone and nitrogen oxides. Can be

Therefore, a photoreceptor having high sensitivity and repetition characteristics could not be obtained without impairing the excellent characteristics of the bisazo pigment (1). The present invention has been made in view of the above circumstances, and the general formula
An object of the present invention is to provide a high-performance electrophotographic photoreceptor having high sensitivity and excellent durability by using the bisazo pigment represented by (1) as a charge generating material.

[0011]

The present inventors have conducted intensive studies on the charge transporting material used in combination with the above bisazo pigment, and as a result, the charge generating material is represented by the above general formula (1). Bisazo pigment and a charge transport material represented by general formula (2):

[0012]

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(Wherein R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are the same or different and each represents an alkyl group, an alkoxyl group, a halogen atom, an aryl group, a nitro group, a cyano group or an alkylamino group And p and q each represent an integer of 0 to 3. k, 1, m and o each represent an integer of 0 to 2.)
An electrophotographic photoreceptor provided with a photosensitive layer containing a diamine compound represented by the formula on a conductive substrate is stable against oxidative deterioration due to ozone, nitrogen oxides, and light,
The present inventors have found a new fact that the sensitivity and the repetition characteristics (durability) can be remarkably improved as compared with the conventional electrophotographic photosensitive member.

The effect of the combination of the above-described charge generating material and charge transport material in the present invention is not necessarily clear, but the effect of suppressing oxidative deterioration caused by ozone, nitrogen oxides and the like is considered as follows.
That is, in the diamine compound (2) used as the charge transporting material, electron delocalization is progressing, and steric hindrance in which a phenyl group surrounds a nitrogen atom causes the azo compound of the bisazo pigment (1). It is considered that the coordination to the group is inhibited, so that the electron density of the azo group does not increase, so that the azo group is hardly attacked by ozone or the like.

Further, the bisazo pigment (1) has high charge generation efficiency and high sensitivity, and the diamine-based compound (2) has a higher ionization potential than the bisazo pigment (1).
It has a good relationship with (1), and is excellent in light resistance and durability, and has little dependence on the electric field strength of mobility.Therefore, these characteristics are not reduced, and an optimal combination is obtained. It is considered that the performance was improved.

However, even with such a combination of the charge generation material and the charge transport material, the printing speed is 40 to 5 times.
When used in a high-speed copier of 0 sheets / min, a large amount of ozone and nitrogen oxides are generated in the machine, and the required light amount is also increased, and the photoconductor is exposed to a more severe use environment. It is desired to further improve the durability against nitrogen and nitrogen oxides.

Therefore, in the present invention, in addition to the combination of the specific charge generating material and the charge transporting material, a general formula (3):

[0018]

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Wherein R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R
¹⁵ is the same or different and represents a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, an aralkyl group or an alkoxy group, and the alkyl group, aralkyl group or alkoxy group may have a substituent. ), A dicarboxylic acid ester derivative represented by the following general formula (4), a diphosphorous acid derivative represented by the general formula (5), and a diphosphoric acid derivative represented by the following general formula (6). And at least one compound selected from the group consisting of a piperidine derivative and a spiro-type amine derivative represented by the general formula (7).

[0020]

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Wherein R ¹⁶ and R ¹⁷ are the same or different and each represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group which may have a substituent, Y ¹ is an alkylene group, and Y ² is an alkylene group or a ^{group: - (Y 3 -Y 3 -O} ) n -Y 3 - ( wherein, Y ³ is an alkylene radical, n is an is an integer of 1 to 3) show an alkylene glycol residue represented by . ]

[0022]

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(In the formula, R ¹⁸ and R ¹⁹ are the same or different and represent an alkyl group or an aryl group which may have a substituent.)

[0024]

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[0025] (wherein, R ⁵⁰ and R ⁵¹ represents an aryl group which may have the same or different and each represents a hydrogen atom, an alkyl group, a cycloalkyl group or a substituent, R ^52,
R ⁵³ , R ⁵⁴ and R ⁵⁵ are the same or different and represent a hydrogen atom or an alkyl group, and Y ⁷ , Y ⁸ and Y ⁹ are the same or different and represent an alkylene group. )

[0026]

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[0027] (wherein, Z ^1, Z ² and Z ³ are the same or different and represent a hydrogen atom or a monovalent organic group, R ^22,
R ²³ , R ²⁴ and R ²⁵ are the same or different and represent a hydrogen atom or an alkyl group, and R ²⁶ or R ²⁷ are the same or different and represent a hydrogen atom, an alkyl group, a halogen atom or a hydroxyl group. That is, these stabilizers are both intended to impart resistance to ozone, nitrogen oxides, and oxidation deterioration against light. At this time, the benzotriazole-based ultraviolet absorber (3) has an effect of converting ultraviolet light energy, which is a main factor of light (oxidation) deterioration, into heat energy to suppress the effect. This benzotriazole UV absorber
Among the other stabilizers (4) to (7) combined with (3), the stabilizer (5) is a peroxide generated by the reaction of radicals generated by heat, light, etc. with oxygen (also generated by ozone). Decomposes into an inactive compound to suppress the effect on the chain reaction. Other stabilizers (4), (6) and (7)
It captures radicals generated by oxidation and suppresses chain reactions.

The alkyl group in the general formula (1) is, for example, a group having 1 to 1 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group and a hexyl group. And 6 alkyl groups. Examples of the aryl group include a phenyl group,
Examples include an o-terphenyl group, a naphthyl group, an anthryl group, a phenanthryl group and the like. Examples of the heterocyclic group include a thienyl group, a pyrrolyl group, a pyrrolidinyl group, an oxazolyl group, an isoxazolyl group, a thiazolyl group, an isothiazolyl group, an imidazolyl group, a 2H-imidazolyl group,
Pyrazolyl group, triazolyl group, tetrazolyl group, pyranyl group, pyridyl group, piberidyl group, piperidino group, 3
-A morpholinyl group, a morpholino group and a thiazolyl group. Further, the heterocyclic group may be condensed with an aromatic ring.

The 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, and 2 to 2 carbon atoms which may have an aryl group And 6 alkenyl groups. Examples of the coupler residues represented by A ¹ and A ² include groups represented by general formulas (a) to (g).

[0030]

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In each formula, R ³⁰ 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, and a succinamoyl group. These groups include 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 ³¹ represents an atomic group necessary for forming an aromatic ring, a polycyclic hydrocarbon or a heterocyclic ring by condensing with R ³⁰ and the benzene ring having a hydroxyl group. It may have a similar substituent. R ³² represents an oxygen atom, a sulfur atom, or an imino group. R ³³ represents a divalent chain hydrocarbon or an aromatic hydrocarbon, and these groups may have the same substituent as described above.

R ³⁴ represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group, and these groups may have the same substituent as described above. R ³⁵ is a divalent chain hydrocarbon, an aromatic hydrocarbon, or the following formula (h) in the above general formulas (e) and (f):

[0034]

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Represents an atomic group necessary for forming a heterocyclic ring together with the moiety represented by the formula, and these rings may have the same substituents as described above. R ³⁶ represents a hydrogen atom, an alkyl group,
It represents an amino group, a carbamoyl group, a sulfamoyl group, an allophanoyl group, a carboxyl group, an ester of a carboxyl group, an aryl group, or a cyano group, and groups other than a hydrogen atom may have the same substituent as described above.

R ³⁷ represents an alkyl group or an aryl group, and these groups may have the same substituent as described above.
In R ³¹ , the atomic groups necessary for condensing with R ³⁰ and a benzene ring having a hydroxyl group to form an aromatic ring include, for example, a methylene group, an ethylene group, a propylene group,
Examples thereof include an alkylene group such as a tetramethylene group.

The aromatic ring formed by condensation of R ³¹ with R ³⁰ and a benzene ring having a hydroxyl group includes:
Examples include a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a chrysene ring, a naphthacene ring and the like. In R ³¹ , an atomic group necessary for condensing with R ³⁰ and a benzene ring having a hydroxyl group to form a polycyclic hydrocarbon includes, for example, carbon atoms such as a methylene group, an ethylene group, a propylene group, and a butylene group. Examples include alkylene groups of the formulas 1 to 4.

In R ³¹ , examples of the polycyclic hydrocarbon condensed with R ³⁰ and a benzene ring having a hydroxyl group include a carbazole ring, a benzocarbazole ring and a dibenzofuran ring. In R ³¹ , an atomic group necessary for condensing with R ³⁰ and a benzene ring having a hydroxyl group to form a heterocyclic ring includes, for example, a benzofuranyl group, a benzothiophenyl group, an indolyl group, a 1H-indolyl group, and a benzoyl group. Oxazolyl group, benzothiazolyl group, 1H-indolyl group, benzimidazolyl group, chromenyl group, chromanyl group, isochromanyl group, quinolinyl group, isoquinolinyl group, cinnolinyl group, phthalazinyl group, quinazonyril group, quinoxalinyl group, dibenzofuranyl group, carbazolyl group , A xanthenyl group, an acridinyl group, a phenanthridinyl group, a phenazinyl group, a phenoxazinyl group, a thianthrenyl group and the like.

Examples of the aromatic heterocyclic group formed by condensation of R ³¹ with R ³⁰ and a benzene ring having a hydroxyl group include, for example, thienyl group, furyl group, pyrrolyl group, oxazolyl group, isoxazolyl group, thiazolyl group , Isothiazolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, pyridyl and thiazolyl groups. 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 ³³ and R ³⁵ , examples of the divalent chain hydrocarbon include an ethylene group, a propylene group, and a butylene group. Examples of the divalent aromatic hydrocarbon include a phenylene group, a naphthylene group, and the like. A phenanthrylene group and the like. In the R ^34, examples of the heterocyclic group, a pyridyl group, pyrazinyl group, thienyl group, pyranyl group, indolyl group and the like.

In R ³⁵ , the atomic groups necessary for forming a heterocyclic ring together with the moiety represented by the formula (h) include, for example, phenylene, naphthylene, phenanthrylene, ethylene, propylene, and butylene. And the like. Examples of the aromatic heterocyclic group formed by R ³⁵ and the moiety represented by the formula (h) include a benzimidazole group, a benzo [f] benzimidazole group, and a dibenzo [e, g] benzimidazole. And benzopyrimidine groups. These groups may have the same substituents as described above.

In R ³⁶ , examples of the carboxyl group ester include methyl ester, ethyl ester, propyl ester and butyl ester. Specific examples of the coupler residues A ¹ and A ² represented by the general formulas (a) to (g) include the following groups.

[0043]

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[0044]

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[0045]

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[0046]

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Specific examples of the bisazo compound (1) include compounds represented by the following formulas (B1) to (B10).

[0048]

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[0049]

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[0050]

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In the diamine compound represented by the general formula (2), the alkyl group and the aryl group corresponding to the groups R ^{2 to} R ⁷ in the formula include, for example, the group represented by the general formula (1). Similar ones can be mentioned. Examples of the halogen atom include chlorine, iodine, bromine and fluorine. Examples of the alkoxyl group include a methoxy group, an ethoxy group, an isopropoxy group, a butoxy group, a t-butoxy group, and a hexyloxy group.

Examples of the alkylamino group include a methylamino group, a dimethylamino group, an ethylamino group, a diethylamino group, a propylamino group, an isopropylamino group, a butylamino group, an isobutylamino group, a t-butylamino group, a pentylamino group. And a hexylamino group. Specific examples of the diamine-based compound represented by the general formula (2) include, for example, No. A shown in Table 1.
1 to A15. In the table, for example, “3-CH ₃ ” indicates that a methyl group is bonded to the 3-position of the phenyl group, and “3,5-CH ₃ ” indicates that a 3- and 5-position of the phenyl group are bonded. This indicates that the methyl groups are bonded to each other (the same applies to Tables 2 to 4 described later).

[0053]

[Table 1]

The diamine compound (2) can be synthesized by various methods, for example, the following general formula (40)
And the compounds represented by the general formulas (41) to (44) are reacted simultaneously or sequentially.

[0055]

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(Wherein R ² , R ³ , R ⁴ , R ⁵ , R ⁶ ,
R ⁷ , k, l, m, o, p, and q are the same as described above. X
Represents a halogen atom. The reaction between the compound represented by the general formula (40) and the compounds represented by the general formulas (41) to (44) is usually performed in an organic solvent,
As the solvent, any solvent can be used as long as it does not adversely affect the reaction, for example, nitrobenzene,
Organic solvents such as dichlorobenzene, quinoline, N, N-dimethylformamide, N-methylpyrrolidone and dimethylsulfoxide are exemplified. The reaction is usually performed in the presence of a catalyst such as copper powder, copper oxide, or copper halide, or a basic substance such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, or potassium hydrogencarbonate. It is performed at a temperature of 250 ° C.

Further, the compound represented by the general formula (2) having a symmetrical structure has controlled substitution positions of the substituents R ² , R ³ , R ⁴ and R ^5. ) And a compound represented by the general formula (41), (43) to obtain a compound represented by the following general formula (46), and then a compound represented by the general formula (46) Is hydrolyzed and deacylated to obtain a compound represented by the following general formula (47), and further reacted with a compound represented by the general formulas (42) and (44). .

[0058]

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(Wherein R ⁸ and R ⁹ represent an alkyl group, and R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , k, l,
m, o, p, and q are the same as described above. The reaction between the compound represented by the general formula (45) and the compound represented by the general formulas (41) and (43) is performed by reacting the compound represented by the general formula (40) with the general formulas (41) and (42). ) The reaction can be carried out in the same manner as in the reaction with the compounds represented by (43) and (44). The deacylation reaction of the compound represented by the general formula (46) by hydrolysis can be performed by a conventional method in the presence of a basic catalyst. Further, the reaction between the compound represented by the general formula (47) and the compound represented by the general formulas (42) and (44) is performed by reacting the compound represented by the general formula (40) with the general formula (41) ( 42) The reaction can be carried out in the same manner as in the reaction with the compounds represented by (43) and (44).

After completion of the reaction, the reaction mixture is concentrated, and can be easily separated and purified by conventional means such as recrystallization, solvent extraction, column chromatography and the like. Next, the stabilizer added to the photosensitive layer will be described. General formula (4)
Examples of the alkylene group in the derivative represented by (6) include a methylene group, an ethylene group, a propylene group, an isopropylidene group, a 2,2-dimethylpropylene group, a butylidene group, a tetramethylene group, and a hexamethylene group. .

Specific examples of the alkyl group, alkoxyl group and aryl group in each of the derivatives of the general formulas (3) to (7) include the same groups as those in the general formula (1) or (2). However, as the alkyl group and the alkoxyl group, a branched or linear alkyl group and an alkoxyl group having 1 to 20 carbon atoms can be employed. Examples of the aralkyl group in the general formula (3) include a benzyl group, a benzhydryl group, a trityl group, and a phenethyl group. Also, the general formulas (4) and (6)
Examples of the cycloalkyl group include, for example, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like, and an aryl group which may have a substituent includes a phenyl group, a benzylphenyl group,
And a dimethylbenzylphenyl group.

The above-mentioned benzotriazole ultraviolet absorber
Examples of (3) include the compounds of (I1) to (I7) represented by the following formulas.

[0063]

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The amount of the benzotriazole-based ultraviolet absorber (3) may be generally about 0.5 to 20 parts by weight based on 100 parts by weight of the binder resin. The general formula (4)
Examples of the dicarboxylic acid ester derivative represented by are the compounds (G1) to (G8) shown in Table 2 below.

[0065]

[Table 2]

Examples of the diphosphorous acid derivative represented by the general formula (5) include compounds (K1) to (K7) shown in Table 3 below.

[0067]

[Table 3]

Examples of the piperidine derivative represented by the general formula (6) include compounds (J1) to (J8) shown in Table 4 below.

[0069]

[Table 4]

The spiro-type amine derivative represented by the general formula (7) includes, for example, compounds (H1) to (H6) represented by the following formulas.

[0071]

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These compounds (4) to (7) may be used alone or in combination of two or more in combination with the benzotriazole-based ultraviolet absorber (3). Good. That is, these compounds (4) to
(7) itself has ozone, nitrogen oxides, and oxidation resistance to light, but when combined with the benzotriazole-based ultraviolet absorber (3), light resistance and nitrogen oxide resistance are further improved. Improves and exhibits a high stabilizing effect.

The amount of the compounds (4) to (7) to be added is usually about 0.5 to 20 parts by weight based on 100 parts by weight of the binder resin. The photoreceptor of the present invention can be applied to a single layer type or a multilayer type as a photosensitive layer. However, the effect of the combination of the charge generation material and the charge transport material is as follows.
In particular, it can be said that the present invention is more preferably applied to an electrophotographic photoreceptor having a single-layer type photosensitive layer, since both materials appear more prominently in a single-layer type photosensitive layer contained in the same layer.

In order to obtain a single-layer type photoreceptor, a photosensitive material containing the bisazo pigment (1) as a charge generating material, the diamine compound (2) as a charge transporting material, a binder resin and the like is used. The layer may be formed on the conductive substrate by means such as coating. Further, in order to obtain a laminated photoreceptor, the bisazo pigment is formed on a conductive substrate by means such as vapor deposition or coating.
A charge generation layer containing (1) and a binder resin may be formed, and a charge transport layer containing the diamine compound (2) and the binder resin may be formed on the charge generation layer. Conversely, a charge transport layer may be formed on a conductive substrate, and then a charge generation layer may be formed.

As the charge generating material, in addition to the bisazo pigment (1), for the purpose of expanding the sensitivity region of the electrophotographic photosensitive member so as to have an absorption wavelength region in a desired region,
Further, other known charge generation materials can be used in combination. As other charge generating materials, other azo pigments having a different chemical structure from those represented by the general formula (1),
Selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salts, perylene pigments, anthanthrone pigments, phthalocyanine pigments, naphthalocyanine pigments, indigo pigments, triphenylmethane pigments, sulene pigments, toluidine pigments Pigments, pyrazoline pigments, quinacridone pigments, dithioketopyrrolopyrrole pigments, and the like.

The above-mentioned diamine compound which is a charge transport material
(2) can be used alone or in combination with other conventionally known charge transport materials. As a conventionally known charge transporting material, various electron withdrawing compounds and electron donating compounds can be used. As the electron-withdrawing compounds, such as ^{2,6-dimethyl-2,, 6,} - di te
diphenoquinone derivatives such as rt-dibutyl diphenoquinone, malononitrile, thiopyran-based compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone,
Examples include fluorenone compounds (such as 3,4,5,7-tetranitro-9-fluorenone), dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, and dibromomaleic anhydride. Is done.

Further, as the electron donating compound, 2,5
Oxadiazole compounds such as -di (4-methylaminophenyl) and 1,3,4-oxadiazole; 9- (4
Styryl compounds such as -diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds, triphenylamine compounds, indole Compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds,
Nitrogen-containing cyclic compounds such as imidazole compounds, pyrazole compounds and triazole compounds, and condensed polycyclic compounds are exemplified.

These charge transport materials are used alone or as a mixture of two or more. Note that when a charge transporting material having a film forming property such as polyvinyl carbazole is used,
A binder resin is not always necessary. Various resins can be used as the binder resin. For example, styrene polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic copolymers, styrene-acrylic acid copolymers, polyethylene, ethylene-vinyl acetate copolymer , Chlorinated polyethylene, polyvinyl chloride, polypropylene,
Thermoplastic resins such as vinyl chloride-vinyl acetate copolymer, polyester alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, polyester resin,
Examples include silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, and other cross-linkable thermosetting resins, as well as photo-curable resins such as epoxy acrylate and urethane-acrylate. These binder resins are 1
Species or a mixture of two or more can be used.

In each of the single-layer type and laminated type organic photosensitive layers,
A sensitizer, a fluorenone-based compound, an antioxidant, a deterioration inhibitor such as an ultraviolet absorber, and an additive such as a plasticizer can be contained. In order to improve the sensitivity of the charge generation layer, a known sensitizer such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generation material.

In the laminated photoreceptor, the charge generation material and the binder resin constituting the charge generation layer can be used in various ratios. It is preferable to use 1000 parts by weight, particularly 30 to 500 parts by weight. The charge transport material and the binder resin constituting the charge transport layer can be used in various ratios within a range that does not hinder charge transport and a range that does not crystallize, but are generated in the charge generation layer by light irradiation. Charge transporting material is 10 to 500 parts by weight, particularly 25 to
It is preferred to use 200 parts by weight.

The thickness of the laminated photosensitive layer is preferably such that the charge generation layer is formed to a thickness of about 0.01 to 5 μm, particularly about 0.1 to 3 μm, and the thickness of the charge transport layer is 2 to 100 μm.
m, particularly preferably about 5 to 50 μm.
In a single-layer type photoreceptor, the charge generation material is 0.1 to 50 parts by weight, especially 0.5 to 50 parts by weight, based on 100 parts by weight of the binder resin.
Suitably, the amount is 30 parts by weight and the charge transporting material is 20 to 500 parts by weight, particularly 30 to 200 parts by weight. The thickness of the single-layer type photosensitive layer is 5 to 100 μm, particularly 10 to 50 μm.
m.

In the case of a single-layer type photoreceptor, between the conductive substrate and the photosensitive layer, in the case of the laminated type photoreceptor, between the conductive substrate and the charge generating layer, or in the case of the conductive type A barrier layer may be formed between the photoconductor and the charge transport layer or between the charge generation layer and the charge transport layer as long as the properties of the photoconductor are not impaired. It may be formed.

Various conductive materials can be used as the conductive substrate on which the above layers are formed.
For example, simple metals such as aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, and plastic materials on which the above metals are deposited or laminated, iodide Glass coated with aluminum, tin oxide, indium oxide or the like is exemplified.

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. In addition, the conductive substrate preferably has sufficient mechanical strength when used. When each of the above layers is formed by a coating method, the above-described charge generation material, charge transport material, binder resin and the like, together with a suitable solvent, are mixed with a known method, for example, a roll mill, a ball mill, an attritor, a paint shaker. Alternatively, a coating solution may be prepared by dispersing and mixing using an ultrasonic disperser or the like, and this may be applied and dried by a known means.

As the solvent for preparing the coating solution, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol,
Aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, dimethyl ether, diethyl ether and tetrahydrofuran Ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethyl formaldehyde, dimethyl formamide, and dimethyl sulfoxide. These solvents can be used alone or in combination of two or more.

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

[0087]

The present invention will be described below in detail with reference to examples and comparative examples. Examples 1 to 20 (laminated photoreceptor) Paint shaker using glass beads (2 mm diameter) comprising 0.7 parts by weight of a bisazo pigment as a charge generating material, 1 part by weight of polyvinyl butyral resin and a predetermined amount of tetrahydrofuran For 2 hours. The resulting dispersion was applied to the surface of an aluminum tube by using a dip coating method, and dried at 100 ° C. for 1 hour to form a charge generation layer having a thickness of 0.5 μm.

On this charge generating layer, 1 part by weight of a diamine compound as a charge transporting material and 1 part by weight of a bisphenol A type polycarbonate resin were dissolved in a predetermined amount of dichloromethane, and further shown in Tables 5 to 8 as a stabilizer. A solution in which a stabilizer was added at a ratio shown in the same table was applied by using a dip coating method, and dried at 100 ° C. for 1 hour to form a charge transport layer having a thickness of 22 μm. Type electrophotographic photosensitive member was obtained. In addition, the charge generation material used in each example,
The charge transport materials and stabilizers are shown in Tables 5 to 8 using the compound numbers of the specific examples described above.

[0089]

[Table 5]

[0090]

[Table 6]

[0091]

[Table 7]

[0092]

[Table 8]

Comparative Example 1 (Laminated photoreceptor) A negative photoconductor was prepared in the same manner as in Examples 1 to 20, except that the bisazo pigment and the diamine compound indicated by the compound number in Table 4 were used without adding a stabilizer. A charging-type laminated electrophotographic photosensitive member was obtained. Comparative Examples 2 to 7 (Laminated Photoreceptor) Instead of the diamine compound used in Examples 1 to 20,
Except that the compounds represented by the following formulas (D1) to (D5) and (D11) were used, respectively, and that no stabilizer was added, the same procedure as in Examples 1 to 20 was carried out to obtain a negatively charged laminated electron. A photoreceptor was obtained. Table 9 shows the composition.

[0094]

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[0095]

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[0096]

[Table 9]

Examples 21 to 40 (Single-layer type photoreceptor) 3 parts by weight of a bisazo pigment as a charge generating material, 75 parts by weight of a diamine compound as a charge transporting material, and 100 parts by weight of a bisphenol A type polycarbonate resin , Table 1
0 to 13 in the proportions shown in the table,
The mixture was dispersed together with dichloromethane using an ultrasonic disperser for 2 minutes to prepare a coating solution for a single-layer photosensitive layer. And
This coating solution is applied to the surface of the aluminum tube by a dip coating method, dried at 80 ° C. for 120 minutes, and has a thickness of 30 μm.
m was formed to obtain a positively-charged single-layer type electrophotographic photoreceptor. The charge generation materials and charge transport material compounds used are shown in Tables 10 to 13 using the compound numbers of the specific examples described above.

[0098]

[Table 10]

[0099]

[Table 11]

[0100]

[Table 12]

[0101]

[Table 13]

Comparative Example 8 (Single-layer type photoreceptor) The same procedures as in Examples 21 to 40 were carried out except that the bisazo pigment and the diamine compound indicated by the compound number in Table 14 were used without adding the stabilizer. A positively charged single-layer electrophotographic photosensitive member was obtained. Comparative Examples 9 to 14 (Single-Layer Photoreceptor) Instead of the diamine-based compounds used in Examples 21 to 40, compounds represented by the following formulas (D6) to (D11) were used, and a stabilizer was used. Example 21 except that it was not added
In the same manner as in Examples 1 to 40, a positively charged single-layer type electrophotographic photoreceptor was obtained.

[0103]

Embedded image

[0104]

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[0105]

[Table 14]

The following tests were carried out on the electrophotographic photosensitive members of the above Examples and Comparative Examples, and the characteristics thereof were evaluated. Electrical Characteristics After measuring the surface potential (V) when the surface of the electrophotographic photosensitive member prepared in each of Examples and Comparative Examples was charged to around ± 800 V, light of 550 nm most necessary for the photosensitive member for PPC was measured. The half-exposure amount was measured using this method. That is, the wavelength extracted from the xenon lamp using a spectroscope is 550.
The light of nm was exposed at an intensity of 0.2 mW / cm ² and an exposure time of 1 second to obtain a half-reduction exposure amount (μJ / cm ² ). Also,
The surface potential at the time when 0.5 seconds passed immediately after the light irradiation was determined as the post-exposure potential (V). Repetition characteristics 1 with electrostatic copying machine DC-1670M (Mita Kogyo Co., Ltd.)
After repeating printing 000 times, the surface potential (V),
The half-exposure dose (μJ / cm ² ) and the post-exposure potential (V) were measured.

Tables 15 to 20 show the test results.

[0108]

[Table 15]

[0109]

[Table 16]

[0110]

[Table 17]

[0111]

[Table 18]

[0112]

[Table 19]

[0113]

[Table 20]

As is clear from Tables 15 to 20, all of the photoreceptors obtained in Comparative Examples 2 to 7 and 9 to 14 had poor sensitivity, and therefore fog occurred from the early stage of printing. Even when the exposure lamp mounted as a standard was set to the maximum output, the potential corresponding to the white background was high and fogging occurred.
In the image confirmation after repeated printing, the contrast potential decreased due to the decrease in the surface potential, and the image density also decreased. On the other hand, the photoconductors obtained in Comparative Examples 1 and 8 had almost no difference in initial sensitivity from the examples, but had a remarkable decrease in sensitivity after repeated printing.

On the other hand, the photoreceptors of each of the examples had high sensitivity, a clear image was obtained even at a normal exposure intensity, and a good image was obtained by repeated printing.

[0116]

According to the present invention, a bisazo pigment represented by the general formula (1), which is a charge generating material, and a diamine compound represented by the general formula (2), which is a charge transporting material, are used. Further, by using a specific derivative as a stabilizer, an organic photoreceptor having high sensitivity and excellent repetition characteristics can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 5/05 103-104 G03G 5/06 351 G03G 5/06 312

Claims (1)

(57) [Claims] 1. A charge-generating material of the general formula (1): (Where A ¹ and A ² are the same or different and represent a coupler residue, R ¹ represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group, and the alkyl group, the aryl group and the heterocyclic group are And n represents 0 or 1.) and a charge transporting material represented by the following general formula (2): (In the formula, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are the same or different and represent an alkyl group, an alkoxyl group, a halogen atom, an aryl group, a nitro group, a cyano group or an alkylamino group. p and q each represent an integer of 0 to 3. k,
l, m and o each represent an integer of 0 to 2. And a diamine compound represented by the general formula (3): (Wherein, R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁵ are the same or different and each represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, an aralkyl group or an alkoxy group; an alkyl group, an aralkyl group or an alkoxy group May have a substituent.) A benzotriazole-based ultraviolet absorber represented by the following general formula (4); a dicarboxylic acid ester derivative represented by the following general formula (4); Phosphoric acid derivative, general formula
A photosensitive layer containing at least one compound selected from the group consisting of a piperidine derivative represented by (6) and a spiro-type amine derivative represented by the general formula (7) is provided on a conductive substrate. An electrophotographic photosensitive member characterized by the following. Embedded image [Wherein, R ¹⁶ and R ¹⁷ are the same or different and each represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group which may have a substituent, and Y ¹ represents an alkylene group,
Y ² is an alkylene group or a group: alkylene represented by — (Y ³ —Y ³ —O) _n —Y ³ — (wherein, Y ³ represents an alkylene group and n is an integer of 1 to 3) Indicates a glycol residue. [Chemical formula 5] (In the formula, R ¹⁸ and R ¹⁹ are the same or different and represent an alkyl group or an aryl group which may have a substituent.) (Wherein, R ⁵⁰ and R ⁵¹ are the same or different and each represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group which may have a substituent, and R ⁵² , R ⁵³ , R ⁵⁴ and R ⁵⁵ are the same or different. Differently represent a hydrogen atom or an alkyl group, and Y ⁷ , Y ⁸ and Y ⁹ represent the same or different alkylene groups.) (Wherein, Z ¹ , Z ² and Z ³ are the same or different and each represent a hydrogen atom or a monovalent organic group, and R ²² , R ²³ , R ²⁴ ,
R ²⁵ is the same or different and represents a hydrogen atom or an alkyl group; R ²⁶ or R ²⁷ is the same or different and represents a hydrogen atom;
It represents an alkyl group, a halogen atom or a hydroxyl group. )