JPH0611859A - 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:This electrophotographic sensitive body has a photosensitive layer contg. an electron transferring material represented by formula I and a positive hole transferring material represented by formula II on the conductor substrate. In the formulae I, II, R<5> is 1-6C alkyl, etc., each of R<1>-R<4> and R<6> is H, 1-6C alkyl, etc., and each of (m)-(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 photoreceptor provided with an organic photosensitive layer on a conductive substrate, and more particularly to an electrophotographic photoreceptor having high sensitivity and excellent repeatability 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 an inorganic material such as selenium as a photosensitive layer, and the other is an organic photoreceptor using an organic material as a photosensitive layer. Organic photoconductors are cheaper than inorganic photoconductors, have high productivity, have a large degree of freedom in functional design, and have many advantages such as no pollution, so extensive research is being conducted. .

In general, such organic photoreceptors often use a function-separated type photosensitive layer containing a charge generating material that generates charges by light irradiation and a charge generating material that transports the generated charges. .

In order to satisfy various conditions desired for such an organic photoreceptor, a charge generating material, a charge transporting material, etc.
It is necessary to properly select the materials to be combined.

As the charge transport material, various substances have been studied so far, and many substances such as polyvinylcarbazole, oxadiazole compounds, pyrazoline compounds and hydrazone compounds have been proposed.

Since these charge-transporting materials are hole-transporting materials, a charge-generating layer and a charge-generating layer are formed on a conductive substrate, which is one of the function-separated type photoreceptors that are currently the mainstream of organic electrophotographic photoreceptors. A negative charging process is inevitably required for a laminated photoreceptor in which a charge transport layer and a charge transport layer are laminated in this order.

However, the negatively charged type organic photoconductor may pollute the environment or deteriorate the photoconductor due to the generation of ozone, and in order to prevent this, a system or apparatus in which ozone is not generated is used. It has a drawback that it requires a system for discarding ozone and complicates the process and system.

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

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

With respect to the charging polarity of the photosensitive member, it has been conventionally known that a photosensitive member usable with both positive and negative charging suppresses the residual potential to a low level, and such a photosensitive member has a wider range. Is expected to be applied. Focusing on this point, the present inventors, for example, as a charge transport material,
An electrophotographic photoreceptor using a diphenoquinone compound as an electron transport material and a phenylenediamine compound as a hole transport material has been proposed.

[0011]

However, a photoreceptor using the above diphenoquinone compound as an electron transport material has a problem that the diphenoquinone compound has sublimability and has low compatibility with the binder resin. The sensitivity was poor, the surface potential decreased with repeated use, and the residual potential increased, and the light resistance was insufficient.

The present invention is intended to solve the above problems. The object of the present invention is that it can be used with both positive and negative charging, has high sensitivity and excellent repeatability, and is also excellent in light resistance. To provide an electrophotographic photoreceptor.

[0013]

The electrophotographic photosensitive member of the present invention comprises a compound represented by the following general formula (I) as an electron transporting material and a general formula as a hole transporting material on a conductive substrate. A photosensitive layer containing a compound represented by (II) is provided, and the above object can be achieved by that.

[0014]

[Chemical 3]

(Wherein 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, a substituent) Represents an optionally substituted aryl group or an optionally substituted benzyl group).

[0016]

[Chemical 4]

(In the formula, R ⁵ represents an alkyl group having 1 to 6 carbon atoms or an aryl group which may be substituted,
R ⁶ and R ⁷ 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 R ⁸ and R ⁹ 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 m, n, p and q each independently represent an integer of 1 or more).

[0018]

In the electrophotographic photosensitive member of the present invention, the compound represented by the above general formula (I) used as an electron transport material has a wider conjugated system than the conventional diphenoquinone type compound, so that electron transfer 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. Further, 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.

The compound represented by the general formula (I) as the specific electron transporting material of the present invention and the compound represented by the general formula (II) as the specific hole transporting material are The effect of matching by selection is not clear, but 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 a longer life of the exposure lamp and a reduction in power consumption. Presumed to be.

Next, the present invention will be described in detail.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The photoconductor of the present invention can be applied to either a single layer type or a laminated type as a photosensitive layer. However, the effect of the combination of the electron transporting material and the hole transporting material is more remarkable especially in the single-layer type photoconductor in which both the transporting material and the charge generating material are contained in the same layer. It can be said that the invention 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 generation material, a compound represented by the general formula (I) which is an electron transport material, and a general formula (II) which is a hole transport material are used. The photosensitive layer containing the compound represented by the formula and the 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 single layer system is that when a charge (hole / electron) is generated in the charge generating material by exposure, the electron is injected into the electron transporting material and the hole transports the hole. The charges (holes / electrons) injected into the material and then injected are transferred in each transport material 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 trapping of charges be suppressed 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 coat the photosensitive layer twice due to its constitution.

To obtain a laminated type photoreceptor, a charge generation layer containing a charge generation material is formed on a conductive substrate by means such as vapor deposition or coating, and the electron transport material is formed on this charge generation layer. A charge transport layer containing a compound represented by the general formula (I), which is a compound represented by the general formula (I), a compound represented by the general formula (II), which is a hole transport material, 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 above-mentioned laminated type photoconductor can be used as a dual charging photoconductor and has a wide range of applications.

A hole transport layer containing a compound represented by the general formula (II), which is a hole transport material, and a binder resin is formed on a conductive substrate, and the hole transport layer is formed. To form a charge generation layer containing a charge generation material by means such as vapor deposition or coating, on the charge generation layer, a compound represented by the general formula (I) is an electron transport material and a binder resin. You may form the electron carrying 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 of a single layer,
The thickness of the organic photosensitive layer is preferably 10 to 50 μm, more preferably 15 to 30 μm.

When the organic photosensitive layer is formed of a single layer,
The content of the charge generation material is the binder resin 10 of the organic photosensitive layer.
The amount is preferably 1 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 0 parts by weight. When the content of the charge generating material is less than 1 part by weight, the sensitivity of the obtained photoreceptor is lowered. On the other hand, if the content of the charge generation material exceeds 20 parts by weight, the abrasion resistance of the obtained photoreceptor may be reduced.

The content of the electron transport material represented by the general formula (I) is 1 with respect to 100 parts by weight of the binder resin of the organic photosensitive layer.
The amount is preferably in the range of 0 to 100 parts by weight, more preferably 20 to 70 parts by weight. When the content of the electron transporting material is less than 10 parts by weight, the resulting photoreceptor has poor repetitive properties. On the other hand, if the content of the electron transport material exceeds 100 parts by weight, the abrasion resistance of the obtained photoreceptor may be reduced. Further, the electron transport material is preferably contained in an amount of 200 to 7000 parts by weight with respect to 100 parts by weight of the charge generation material.

The content of the hole transport material represented by the general formula (II) is 1 with respect to 100 parts by weight of the binder resin of the organic photosensitive layer.
The amount is preferably in the range of 0 to 100 parts by weight, more preferably 20 to 70 parts by weight. If the content of the hole transport material is less than 10 parts by weight, the sensitivity of the resulting photoreceptor will be poor. On the other hand, when the content of the hole transport material exceeds 100 parts by weight, the abrasion resistance of the obtained photoreceptor may be reduced. Further, the hole transport material is the charge generation material 10
It is preferable that the content is 200 to 7,000 parts by weight with respect to 0 parts by weight.

The content of the electron transporting material represented by the general formula (I) is 20 to 80% by weight, and particularly 30 to 70% by weight in the charge transporting material. preferable. The content of the electron transport material in the charge transport material is 20
If it is less than 10% by weight, the resulting photoreceptor will have poor repeatability. On the other hand, when the content of the electron transporting material exceeds 80% by weight, the sensitivity of the obtained photoreceptor becomes poor.

The content of the hole transporting material represented by the above general formula (II) is preferably 20 to 80% by weight, more preferably 30 to 70% by weight in the charge transporting material. preferable. If the content of the hole transporting material in the charge transporting material 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 transport material exceeds 80% by weight, the sensitivity of the resulting photoreceptor becomes poor.

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 0.1-5 μm.
Is preferable, and more preferably 0.5 to 2 μm. The thickness of the charge transport layer is preferably 10 to 50 μm, more preferably 15 to 30 μm.

The content of the charge generating material 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. When the content of the charge generation material is less than 50 parts by weight, the charge generation concentration of the obtained photoreceptor is low, while when the content of the charge generation material exceeds 500 parts by weight, the mechanical strength of the obtained photoreceptor is It may decrease.

The content of the electron transport material represented by the general formula (I) is 1 with respect to 100 parts by weight of the binder resin in the charge transport layer.
The amount is preferably in the range of 0 to 100 parts by weight, more preferably 20 to 70 parts by weight. When the content of the electron transporting material is less than 10 parts by weight, the resulting photoreceptor has poor repetitive properties. On the other hand, if the content of the electron transport material exceeds 100 parts by weight, the abrasion resistance of the obtained photoreceptor may be reduced.

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

The content of the electron transporting material represented by the above general formula (I) is preferably 20 to 80% by weight, and particularly preferably 30 to 70% by weight in the charge transporting material. . If the content of the electron transporting material in the charge transporting material is less than 20% by weight, the repeating characteristics of the obtained photoreceptor will be poor. On the contrary, when the content of the electron transporting material exceeds 80% by weight, the sensitivity of the resulting photoreceptor becomes poor.

The content of the hole transport material represented by the general formula (II) is preferably 20 to 80% by weight, more preferably 30 to 70% by weight in the charge transport material. preferable. If the content of the hole transporting material in the charge transporting material 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 transport material 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 material contained in the above resin composition, conventionally known materials can be used, for example, 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.

The charge transport material contained in the photoconductor of the present invention is the electron transport material represented by the general formula (I) and the hole transport material represented by the general formula (II).

The above-mentioned electron transporting material is based on Chemistry Letters,
It can be synthesized by the method described in p.1461-1464, 1991, and in the above general formula (I), R ¹ , R ² , R ³ and R ⁴ can be synthesized.
Preferred examples of the hydrogen atom include a hydrogen atom, a methyl group, a methoxy group and a phenyl group. Suitable compounds include, for example, [2.2] (3,5) -diphenoquinonophene.

Further, the above hole transport material is disclosed in JP-A-58-14006.
It can be obtained by the method described in JP-A-8. In the general formula (II), R ⁵ is a methyl group, an ethyl group,
Preferable examples are a toluyl group and an isopropyl group, R ⁶ and R ⁷ are preferably a hydrogen atom, a methyl group and an ethyl group, and R ⁸ and R ⁹ are preferably a hydrogen atom and a methyl group. Further, in the general formula (II), m, n, p and q are preferably 0 to 2.

Further, the resin composition may contain the following charge transport material in addition to the charge transport material. For example, m-phenylenediamine compounds; tetracyanoethylene; fluorenone compounds such as 2,4,7-trinitro-9-fluorenone; nitro compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; Triphenylmethane compounds; Oxadiazole compounds such as 2,5-di (4-dimethylaminophenyl) -1,3,4-oxadiazole; Styryl compounds such as 9- (4-diethylaminostyryl) anthracene ; Poly
-Carbazole compounds such as N-vinylcarbazole; 1-
Pyrazoline compounds such as phenyl-3- (p-dimethylaminophenyl) pyrazoline; amine derivatives such as 4,4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine;
Conjugated unsaturated compounds such as 1,1-bis (4-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene; Hydrazones such as 4- (N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone Compounds; indole compounds,
Nitrogen-containing cyclic compounds such as oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds and triazole compounds; condensed polycyclic compounds and the like.

As the binder resin contained in the above-mentioned resin composition, all resins which have been conventionally used in photoreceptor coating liquids can be used. For example, thermosetting silicone resin, epoxy 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 polymer, acrylic polymer, styrene-acrylic resin Coalesce, polyethylene, ethylene-vinyl acetate polymer, chlorinated polyethylene, polypropylene,
Olefin polymers such as ionomers; polyvinyl chloride; vinyl chloride-vinyl acetate copolymers; polyvinyl acetate; saturated polyesters; polyamides; thermoplastic urethane resins; polycarbonates; polyarylates; polysulfones; ketone resins; polyvinyl butyral resins; polyethers. Examples include resins. When the organic photosensitive layer is formed of a plurality of layers, the binder resin can be used to form each layer.

As the additive, various additives such as an antioxidant and a quencher may be contained.

The above-mentioned 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. The conductive substrate may be entirely formed of a conductive material such as metal, or the base material may be formed of a material having no conductivity and the surface thereof may be provided with a material having conductivity. Good. Examples of the conductive material include aluminum, copper, tin, platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, and stainless steel whose surface is alumite-treated or untreated. , Brass, etc., and particularly aluminum which is anodized by the sulfuric acid alumite method and sealed with nickel acetate is preferably used. When a conductive material is provided 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 metal or aluminum iodide described above, tin oxide, A thin film made of a conductive material such as indium oxide is formed by a known film forming method such as a vacuum deposition method or a wet plating method,
It is possible to employ one in which a film of the metal material or the like is laminated on the surface of the base material, or one in which a substance that imparts conductivity is injected into the surface of the base material.
The conductive base material 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 to the organic photosensitive layer.

In the electrophotographic photoreceptor of the present invention, when each of the above-mentioned 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 material, charge transporting material, A binder resin or the like is dispersed and mixed with an appropriate solvent to prepare a coating liquid,
This may be applied and dried.

In order to reduce the residual amount of the solvent contained in the organic photosensitive layer, it is preferable to heat-treat the above-mentioned photosensitive member,
For example, when dichloromethane is used as the solvent, it is preferable that the conductive substrate coated with the coating liquid is 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.

Dichloromethane is preferably used as the solvent or dispersion medium used in the above coating liquid, but it is also possible to use another solvent or dispersion medium alone or in combination with dichloromethane.

The above-mentioned solvent or dispersion medium is, for example,
The following solvents are listed. Aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane; aromatic hydrocarbons such as benzene, xylene, and toluene; halogenated hydrocarbons such as carbon tetrachloride and chlorobenzene; methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, Alcohols such as 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, mixer, ball mill, paint shaker, sand mill,
It can be prepared by a method 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.

[0057]

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 As a charge generating material, 5 parts by weight of metal-free phthalocyanine, 40 parts by weight of the compound shown in Table 1 as a hole transfer agent, and 40 of compounds shown in Table 1 as an electron transfer agent. By weight, 100 parts by weight of polycarbonate 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. After coating this preparation solution on aluminum foil with a wire bar, at 60 ℃
By drying with hot air for 120 minutes, an electrophotographic photosensitive member having a single-layer type photosensitive layer with a film thickness of 15 to 20 μm was obtained.

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 V ₁ sp Using an electrostatic copying tester (Kawaguchi Electric Co., EPA-8100),
An applied voltage was applied to the obtained photoconductor to charge its surface potential positively or negatively, and the surface potential V ₁ (V) was measured.

[0061] 2) with respect to the electrophotographic photosensitive member of the measuring the charging condition of the half decay exposure E1 / 2 and the residual potential V2, using a halogen lamp as an exposure light source of the electrostatic copying test apparatus, the surface potential V ₁ is 1
Obtain the half-exposure amount E1 / 2 (1μJ / cm
² ) was calculated. In addition, the surface potential after 5 seconds from the exposure was measured and defined as the residual potential V ₂ (V).

3) Measurement of repeating characteristics ΔV ₁ and ΔV ₂ The obtained photoreceptor was mounted on a copying machine and the surface potential V ₁ and the residual potential V ₂ after 1000 cycles of copying process were measured. , V ₁ and V ₂ were calculated as the surface potential change ΔV ₁ and the residual potential change ΔV ₂ .

[0063]

[Table 1]

[0064]

[Chemical 5]

[0065]

[Chemical 6]

[0066]

[Chemical 7]

[0067]

[Chemical 8]

From Table 1, it can be seen that the electrophotographic photosensitive members of the examples are excellent in photosensitivity and repeatability.

[0069]

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 photosensitive material containing, on a conductor substrate, a compound represented by the following general formula (I) as an electron transporting material and a compound represented by the following general formula (II) as a hole transporting material. An electrophotographic photoreceptor comprising a 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 substituted. Represents an optionally substituted aryl group or an optionally substituted benzyl group). [Chemical 2] (In the formula, R ⁵ represents an alkyl group having 1 to 6 carbon atoms or an aryl group which may be substituted, and R ⁶ and R ⁷
Are each independently a hydrogen atom or a carbon atom number of 1 to 6.
Represents an alkyl group or an alkoxy group having 1 to 6 carbon atoms, R ⁸ and R ⁹ are each independently a hydrogen atom,
An alkyl group having 1 to 6 carbon atoms or 1 to 6 carbon atoms
6 represents an alkoxy group, and m, n, 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.