JPH0611866A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body usable in both of a positively charged state and a negatively charged state, having high sensitivity and excellent in repetitive characteristics and light resistance. CONSTITUTION:A photosensitive layer contg. an electron transferring agent represented by formula I and a positive hole transferring agent represented by formula II is formed on an electric conductive substrate. In the formulae I, II, each of R<1>-R<6> is H, 1-6C alkyl, etc., (n) is an integer of 0-3 and each of (p) and (q) is an integer of >=1.

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 containing an organic photosensitive layer, and more particularly to an electrophotographic photosensitive member having high sensitivity, excellent repeating characteristics and light resistance.

[0002]

2. Description of the Related Art Recently, electrophotographic photoreceptors made of various materials have been proposed and used in image forming apparatuses such as copying machines utilizing the so-called Carlson process. One is an inorganic photoreceptor using a photosensitive layer containing an inorganic material such as amorphous selenium, and the other is an organic photoreceptor using a photosensitive layer containing an organic material. Organic photoreceptors are cheaper and more productive than inorganic photoreceptors, have good insulating properties in the dark, and have a wide range of functional design because of their diverse molecular structures, and are non-polluting. Due to its advantages, extensive research is underway.

In such an organic photoreceptor, generally, a function-separated type photosensitive layer containing a charge generating agent for generating an electric charge by light irradiation and a charge transferring agent for transferring the generated electric charge is often used. .

In order to satisfy various conditions desired for such an organic photoreceptor, it is necessary to appropriately select materials to be combined such as a charge generating agent and a charge transporting agent.

Various substances have been studied as the charge transfer agent, and many substances such as polyvinylcarbazole, oxadiazole compounds, pyrarizone compounds, and hydrazone compounds have been proposed.

Since these charge-transporting agents are hole-transporting agents, they are one of the function-separated type photoreceptors which have become the mainstream of organic electrophotographic photoreceptors at present, and a charge-generating layer is formed on a conductive substrate. A negative charging process is inevitably required for a laminated photoreceptor having a system in which a charge transport layer and a charge electron transport layer are laminated in this order. But,
Negatively charged organic photoconductors may pollute the environment or deteriorate the photoconductor due to ozone generation.To prevent this, a system that does not generate ozone or a system that discards ozone in the device However, there is a drawback that the process and system become complicated.

In order to solve these drawbacks, the use of an electron transfer material as a charge transfer material has been studied, and an electrophotographic photosensitive material using a compound having a diphenoquinone skeleton as an electron transfer material, which can be used in positive charging. A body has been proposed (Japanese Patent Laid-Open No. 1-206349).

This is an electron acceptor having a non-localized π-electron system, and can transport electrons by an electron transfer reaction involving an anion radical state.

By the way, if a photoconductor having both positive charging property and negative charging property can be used, the application range of the photoconductor can be further expanded. As such a photoreceptor, by containing an electron transporting agent having a quinone structure as a charge transporting agent and a phenylenediamine-based hole transporting agent in the photosensitive layer, it can be used in both positive and negative charging and has high sensitivity and It is also being studied to obtain a photoreceptor having excellent repeating characteristics.

[0010]

However, a photoreceptor using the above diphenoquinone compound as an electron transfer agent is
Since the diphenoquinone compound has sublimability and low compatibility with the binder resin, the sensitivity is poor, and when it is repeatedly used, the surface potential is lowered and the residual potential becomes high, and further, the light resistance is further increased. The sex was insufficient.

The present invention is intended to solve the above problems, and an object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity, excellent repeating characteristics and light resistance.

[0012]

The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member in which an organic photosensitive layer containing an electron transferring material and a hole transferring material is provided on a conductive substrate. The electron transfer agent is a compound represented by the following general formula (I), and the hole transfer agent is a compound represented by the following general formula (II), thereby achieving the above object. can do.

[0013]

[Chemical 3]

(In the formula, R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a substituent. Represents an optionally substituted aryl group or an optionally substituted benzyl group)

[0015]

[Chemical 4]

(In the formula, R ⁵ and R ⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and n is 0 to 3 Represents an integer, and p and q each independently represent an integer of 1 or more)

[0017]

In the electrophotographic photosensitive member of the present invention, the compound represented by the general formula (I) used as the electron transfer agent has a wider conjugated system than the conventional diphenoquinone type compound, and therefore, the transfer of electrons is caused. The degree improves. Further, since the compound (I) has an increased molecular weight as compared with the conventional diphenoquinone compound, it has excellent compatibility with the binder resin and can be contained in a large amount in the photosensitive layer. Therefore, the sensitivity of the photoconductor is improved. In addition, the above compound (I)
Does not have a sublimation property unlike the diphenoquinone-based compound, the photoconductor has excellent light resistance and has excellent repetitive characteristics such as stable potential during repeated use.

Further, the compound represented by the general formula (I) as the specific electron transfer agent of the present invention and the compound represented by the general formula (II) as the specific hole transfer agent are used. Although the action of matching due to the selection is not clear, it is understood from the comparison between the example and the comparative example described later that the result is improvement in sensitivity, repeatability and light resistance.

That is, even if the output of the exposure lamp that is standardly installed in the copying machine is not increased, problems such as fog do not occur, which leads to extension of the life of the exposure lamp and reduction of power consumption. It is estimated that

Next, the present invention will be described in detail.

[0021]

[Preferable Embodiment] The photoreceptor of the present invention comprises a single layer type as a photosensitive layer,
It is applicable to any of the multi-layer type. However, the effect of the combination of the electron transfer agent and the hole transfer agent is more remarkable particularly in the single-layer type photoconductor in which both the transfer agent and the charge generating agent are contained in the same layer. It can be said that is more preferably applied to an electrophotographic photoreceptor having a single-layer type photosensitive layer.

In order to obtain a single-layer type photoreceptor, a charge generating agent, a compound represented by the general formula (I) which is an electron transfer agent, and a general formula (II) which is a hole transfer agent are used. A photosensitive layer containing the represented compound and a binder resin may be formed on the conductive substrate by means of coating or the like.

That is, the principle of charge image generation in the above-mentioned single layer system is that when charges (holes and electrons) are generated in the charge generating agent by exposure, electrons are injected into the electron transferring material and holes are hole transferring. The charges (electrons and holes) injected into the agent and then injected are transferred in each transport agent without being trapped in the middle, and finally transferred to the surface of the photosensitive layer or the surface of the conductive substrate. It is to be transported.

That is, in the single-layer type photoreceptor as described above,
Not only can the charge trap be controlled and the sensitivity can be improved, but it can also be used as a dual charging photoconductor and has a wide range of applications. Further, the single-layer type photoconductor is improved in productivity because it is not necessary to apply the photosensitive layer twice because of its constitution.

In order to obtain a laminated type photoreceptor, a charge generation layer containing a charge generation agent is formed on a conductive substrate by means such as vapor deposition or coating, and the electron transfer agent is formed on this charge generation layer. A compound represented by the above general formula (I),
A charge transport layer containing a compound represented by the general formula (II), which is a hole transport agent, and a binder resin may be formed. Alternatively, conversely to the above, the charge transport layer may be formed on the conductive substrate, and then the charge generation layer may be formed.

The laminated type photoreceptor of the above-mentioned type can be used as both charging photoreceptors and has a wide range of applications.

A hole transporting layer containing a compound represented by the general formula (II), which is a hole transporting agent, and a binder resin is formed on a conductive substrate, and the hole transporting layer is formed on the hole transporting layer. On the charge generation layer, a charge generation layer containing a charge generation agent is formed by means such as vapor deposition or coating, and a compound represented by the general formula (I), which is an electron transfer agent, and a binder resin are formed on the charge generation layer. You may form the charge transport layer containing.

The laminated type photoreceptor of the above type is a positive charging type.

Alternatively, contrary to the above, an electron transport layer may be formed on a conductive substrate, and then a charge generation layer and a hole transport layer may be sequentially laminated.

The laminated type photoreceptor of the above type is a negative charging type.

When the organic photosensitive layer is formed as a single layer, the thickness of the organic photosensitive layer is preferably 10 to 50 μm, more preferably 15 to 30 μm.

The content of the charge generating agent is preferably in the range of 1 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the binder resin of the organic photosensitive layer. is there. When the content of the charge generating agent is less than 1 part by weight,
The resulting photoconductor has a small charge generation capability. On the other hand, if the content of the charge generating agent exceeds 20 parts by weight, the abrasion resistance of the resulting photoreceptor may be reduced.

The content of the electron transfer agent represented by the above general formula (I) is 10 based on 100 parts by weight of the binder resin of the organic photosensitive layer.
It is preferably contained in the range of 100 to 100 parts by weight, more preferably 20 to 70 parts by weight. When the content of the electron transfer agent is less than 10 parts by weight, the resulting photoreceptor has poor repetitive properties. On the contrary, the content of the electron transfer agent is 100
If the amount is more than parts by weight, the abrasion resistance of the resulting photoreceptor may be reduced. Further, it is preferable to contain 200 to 7000 parts by weight with respect to 100 parts by weight of the charge generating agent.

The content of the hole transfer agent represented by the general formula (II) is 1 with respect to 100 parts by weight of the binder resin of the organic photosensitive layer.
It is preferably contained in the range of 0 to 100 parts by weight, more preferably 20 to 70 parts by weight. When the content of the hole transport material is less than 10 parts by weight, the sensitivity of the obtained photoreceptor is lowered. On the other hand, if the content of the hole transport material exceeds 100 parts by weight, the abrasion resistance of the resulting photoreceptor may be reduced. 200 to 700 relative to the weight part of the charge generating agent
It is preferably contained in an amount of 0 part by weight.

The content of the electron transfer agent represented by the above general formula (I) is preferably 20 to 80% by weight, more preferably 30 to 70% by weight, in the charge transfer agent. is there. When the content of the above-mentioned electron transfer agent in the charge transfer agent is less than 20% by weight, the repetitive characteristics of the obtained photoreceptor are deteriorated. On the other hand, when the content of the electron transfer agent exceeds 80% by weight, the sensitivity of the obtained photoreceptor is lowered.

The content of the hole transfer agent represented by the general formula (II) is preferably 20 to 80% by weight, more preferably 30 to 70% by weight in the charge transfer agent.
Is. When the content of the hole transporting agent in the charge transporting agent is less than 20% by weight, the repeating characteristics of the resulting photoreceptor will be poor. On the contrary, when the content of the hole transport material exceeds 80% by weight, the sensitivity of the obtained photoreceptor is lowered.

When the organic photosensitive layer is composed of a charge generation layer and a charge transport layer, the thickness of the charge generation layer is from 0.1 to
The thickness is preferably 5 μm, more preferably 0.5 to 2 μm. The thickness of the charge transport layer is preferably 10 to 50 μm,
More preferably, it is 15 to 30 μm.

The content of the above charge generating agent is preferably 50 to 500 parts by weight, more preferably 100 to 300 parts by weight, based on 100 parts by weight of the binder resin in the charge generating layer. is there. When the content of the charge generating agent is less than 50 parts by weight, the charge generating ability of the obtained photoreceptor is small, and when the content of the charge generating agent exceeds 500 parts by weight, the mechanical strength of the obtained photoreceptor is It may decrease.

The content of the electron transfer agent represented by the above general formula (I) is 10 based on 100 parts by weight of the binder resin in the charge transfer layer.
It is preferably contained in the range of 100 to 100 parts by weight, more preferably 20 to 70 parts by weight. When the content of the electron transfer agent is less than 10 parts by weight, the resulting photoreceptor has poor repetitive properties. On the contrary, if the content of the electron transfer agent is 10
If it exceeds 0 parts by weight, the abrasion resistance of the resulting photoreceptor may be reduced.

The content of the hole transfer agent represented by the general formula (II) is 1 with respect to 100 parts by weight of the binder resin in the charge transfer layer.
It is preferably contained in the range of 0 to 100 parts by weight, more preferably 20 to 70 parts by weight. When the content of the hole transport material is less than 10 parts by weight, the sensitivity of the obtained photoreceptor is lowered. On the other hand, if the content of the hole transport material exceeds 100 parts by weight, the abrasion resistance of the resulting photoreceptor may be reduced.

The content of the electron transfer agent represented by the general formula (I) is preferably 20 to 80% by weight, more preferably 30 to 70% by weight in the charge transfer agent. Preferably. When the content of the above-mentioned electron transfer agent in the charge transfer agent is less than 20% by weight, the repetitive characteristics of the obtained photoreceptor are deteriorated. On the other hand, when the content of the electron transfer agent exceeds 80% by weight, the sensitivity of the obtained photoreceptor is lowered.

The content of the hole transfer agent represented by the general formula (II) is preferably 20 to 80% by weight, more preferably 30 to 70% by weight, in the charge transfer agent.
It is preferably contained. When the content of the hole transporting agent in the charge transporting agent is less than 20% by weight, the repeating characteristics of the resulting photoreceptor will be poor. On the other hand, when the content of the hole transporting agent exceeds 80% by weight, the sensitivity of the resulting photoreceptor becomes poor.

Further, a protective layer may be provided on the organic photosensitive layer, and an intermediate layer may be provided between the organic photosensitive layer and the conductive substrate.

As the charge generating agent, conventionally known charge generating agents can be used. For example, selenium, selenium-tellurium, amorphous silicon, pyrylium salt, azo pigments, disazo pigments, anthanthrone pigments, phthalocyanine pigments, indico pigments, threnic pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments. And the like, preferably A-type metal-free phthalocyanine,
Copper phthalocyanine, oxotitanyl phthalmeanine, 1,
4-dithioketo-3,6-diphenyl-pyrrolo- (3,
4-c) pyrrolohilol, 2,7-bis (2-hydroxy-3- (2-chlorophenylcarbamoyl) -1-naphthylazo) fluorenone and the like can be mentioned.

As the charge transfer agent, the electron transfer agent represented by the general formula (I) and the hole transfer agent represented by the general formula (II) are used.

In the electron transfer agent represented by the above general formula (I), R ¹ , R ² , R ³ and R ⁴ are preferably each independently a hydrogen atom, a methyl group, a methoxy group or the like.
For example, [2.2.2.2] (3,3 ', 5,5')-
Examples include diphenoquinonophene, Chemistry Lett
ers, pp.1461-1464, (1991).

In the hole-transporting agent represented by the general formula (II), R ⁵ and R ⁶ are preferably each independently a hydrogen atom, a methyl group, a methoxy group, an ethyl group,
n is preferably 0 to 2, and p and q are each preferably 1 or 2 independently. For example, 1- (2-pyrene)-
4- (4-di (4-methylphenyl) aminophenyl)
-1,3-Butadiene and the like can be mentioned, for example, JP-A 1-252965.
It can be synthesized according to the publication.

Further, as the above charge transfer material, an electron transfer material and a hole transfer material other than the above may be used. For example, m-phenylenediamine compounds; tetracyanoethylene; fluorenone compounds such as 2,4,7, -trinitro-9-fluorenone; nitrated compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride. Acid; triphenylmethane compound;
2,5-di (4-dimethylaminophenyl) -1,3
Oxadiazole compounds such as 4, -oxadiazole; styryl compounds such as 9- (4-diethylaminostyryl) anthracene; carbazole compounds such as poly-N-vinylcarbazole; organic polysilane compounds; 1
-Pyrazoline compounds such as phenyl-3- (p-dimethylaminophenyl) pyrazoline; 4,4 ', 4'',-
Amine derivatives such as tris (N, N-diphenylamino) triphenylamine; conjugated unsaturated compounds such as 1,1-bis (4-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene; 4- ( Hydrazone compounds such as N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone; indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazolines Nitrogen-containing cyclic compounds such as compounds and triazole compounds; condensed polycyclic compounds and the like.

As the binder resin, any of those conventionally used in photoreceptor coating liquids can be used. For example, thermosetting silicone resin; epoxy resin; phenoxy resin; urethane resin; curable acrylic resin. Acrylic-modified urethane resin; Alkyd resin; Unsaturated polyester resin; Diallyl phthalate resin; Phenol resin; Urea resin; Benzoguanamine resin; Melamine resin; Styrene-based polymer; Acrylic polymer; Styrene-acrylic polymer; Polyethylene; Ethylene Vinyl acetate polymer; olefin such as chlorinated polyethylene, polypropylene, ionomer; polyvinyl chloride; vinyl chloride-vinyl acetate copolymer; polyvinyl acetate; saturated polyester;
Polyacrylamide; polyamide; thermoplastic urethane resin; polycarbonate; polyarylate; polysulfone; ketone resin; polyvinyl butyral resin; polyether resin and the like. When the organic photosensitive layer is formed of a plurality of layers, the binder resin can be used to form each layer.

As additives, antioxidants, radical scavengers, and
A quencher, a UV absorber, a softening agent, a surface modifier, a filler, a thickener, a dispersion stabilizer, a wax, an acceptor, a donor and the like may be contained.

The conductive substrate is formed in an appropriate shape such as a sheet shape or a drum shape according to the mechanism and structure of the image forming apparatus in which the electrophotographic photosensitive member is incorporated. As the conductive substrate, the whole may be formed of a conductive material such as metal,
Alternatively, the base material may be formed of a material having no conductivity, and the surface thereof may be provided with a material having conductivity. As the conductive material, for example, the surface is alumite-treated, or untreated aluminum, copper, tin, platinum,
Examples thereof include gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. Particularly, aluminum anodized by the sulfuric acid alumite method and sealed with nickel acetate is preferably used. To be In the case of a conductive substrate formed by providing a conductive material on the surface of a base material made of a material having no conductivity, on the surface of a synthetic resin base material or a glass base material, the above-mentioned metal or A thin film made of a conductive material such as aluminum iodide, tin oxide, indium oxide,
Those formed by a known film forming method such as a vacuum vapor deposition method and a wet plating method, those in which a film of the above metal material or the like is laminated on the surface of the above base material, and substances that impart conductivity to the surface of the above base material Injected ones can be used. The conductive substrate may be subjected to a surface treatment with a surface treatment agent such as a silane coupling agent or a titanium coupling agent, if necessary, to enhance the adhesion with the organic photosensitive layer.

In the electrophotographic photoreceptor of the present invention, when each of the above organic photosensitive layers is formed by a coating method such as a spray coating method, a dipping method or a flow coating method, the charge generating agent and the charge transporting agent described above are used. , A binder resin and the like are dispersed and mixed with an appropriate solvent to prepare a coating liquid,
This may be applied and dried.

It is preferable to perform heat treatment in order to reduce the residual amount of the solvent contained in each of the organic photosensitive layers.
When dichloromethane is used as the solvent, the conductive substrate coated with the coating solution is preferably heat-treated at a temperature of 50 ° C. or higher for 60 minutes or longer. When the heat treatment temperature is lower than the above conditions, the residual amount of dichloromethane may not be sufficiently reduced.

As the solvent or dispersion solvent used in the coating liquid, the following solvents or dispersion media can be used alone or in combination in addition to dichloromethane.
For example, aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane; aromatic hydrocarbons such as benzene, xylene, and toluene; halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene; methanol, ethanol, isopropanol, Butanol,
Alcohols such as allyl alcohol, cyclopentanol, benzyl alcohol, furfuryl alcohol, diacetone alcohol; ethers such as dimethyl ether, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetrahydrofuran; acetone, methyl ethyl ketone, methyl isobutyl ketone, Ketones such as cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethylformamide; dimethyl sulfoxide and the like.

The coating solution is prepared by a conventionally known method, for example, a mixer, a ball mill, a paint shaker, a sand mill,
It can be prepared using an attritor, an ultrasonic disperser or the like. When preparing the above-mentioned coating liquid, a surfactant, a leveling agent, or the like may be added to improve dispersibility, coatability, and the like.

[0056]

EXAMPLES The present invention will be described below with reference to examples and comparative examples.

Examples 1 to 9 and Comparative Examples 1 to 10 5 parts by weight of metal-free phthalocyanine as a charge generating agent, 40 parts by weight of a compound shown in Table 1 as an electron transfer agent, and 40 compounds of Table 1 as a hole transfer agent. By weight, 100 parts by weight of a polycarbonate resin as a binder resin and 800 parts by weight of dichloromethane as a solvent were mixed and dispersed in a paint shaker to prepare a coating liquid for a single-layer type photosensitive layer. The prepared liquid was applied onto an aluminum foil with a wire bar and then dried by heating at 60 ° C. for 120 minutes to obtain an electrophotographic photosensitive member having a single-layer type photosensitive layer having a film thickness of 15 to 20 μm.

The charging characteristics and photosensitive characteristics of the electrophotographic photosensitive members obtained in Examples 1 to 9 and Comparative Examples 1 to 10 were evaluated according to the following methods, and the results are shown in Table 1.

1) Measurement of initial surface potential V1sp A single layer type electrophotographic photosensitive member was applied with an applied voltage to the obtained photosensitive member by using an electrostatic copying tester (EPA-8100 manufactured by Kawaguchi Denki KK). The surface potential was charged positively or negatively, and the surface potential V1 (V) was measured.

2) Measurement of half-exposure amount E1 / 2 and residual potential V2 The surface potential V1 of the photoconductor in the charged state was reduced to 1/2 by using a halogen lamp as an exposure light source of an electrostatic copying tester.
Until the half-exposure amount E1 / 2 (lux.
sec) was calculated. Further, the surface potential after 5 seconds from the exposure was measured and defined as the residual potential V2 (V).

3) Measurement of repetitive characteristics ΔV1 and ΔV2 The obtained photoconductor was mounted on a copying machine, the surface potential V1 and the residual potential V2 after 1000 cycles of copying were measured, and V1 and V2 were measured. Was calculated as the surface potential change ΔV1 and the residual potential change ΔV2.

[0062]

[Table 1]

[0063]

[Chemical 5]

[0064]

[Chemical 6]

[0065]

[Chemical 7]

[0066]

[Chemical 8]

From Table 1, it can be seen that the electrophotographic photosensitive members of the examples have high sensitivity and excellent repeatability and light resistance.

[0068]

As is apparent from the above description, according to the present invention, it is possible to provide an electrophotographic photosensitive member which can be used with both positive and negative charging and has high sensitivity and excellent repeating characteristics and light resistance.

Claims (2)

[Claims] 1. A conductive substrate containing a compound represented by the following general formula (I) as an electron transfer agent and a compound represented by the following general formula (II) as a hole transfer agent. An electrophotographic photoreceptor comprising a photosensitive layer. [Chemical 1] (In the formula, R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a substituent. Represents a good aryl group or an optionally substituted benzyl group) (In the formula, R ⁵ and R ⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and n represents an integer of 0 to 3). , P and q each independently represent an integer of 1 or more). 2. The electrophotographic photosensitive member according to claim 1, wherein the organic photosensitive layer is a single-layer type organic photosensitive layer.