JP2828812B2 - 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 having an organic photosensitive layer provided on a conductive substrate, and more particularly, to an electrophotographic photosensitive member having high sensitivity and excellent repetition characteristics, ozone resistance and light resistance. It relates to a photoreceptor.

[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 photosensitive member using an inorganic material such as selenium as a photosensitive layer, and the other is an organic photosensitive member using an organic material as a photosensitive layer. Organic photoreceptors are inexpensive and have higher productivity than inorganic photoreceptors, and have many advantages such as being pollution-free.

By the way, an electrophotographic photoreceptor which can be used in both positive and negative charging using a diphenoquinone compound as an electron transport material and a polysilane or benzidine compound as a hole transport material has been proposed as a charge transport material. Have been.

[0004]

However, the above-mentioned electrophotographic photoreceptor has a drawback that the sensitivity is poor and the surface potential decreases when used repeatedly. More ozone resistance,
Light resistance was insufficient.

An object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity and excellent repetition characteristics.

[0006]

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

[0007]

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(Wherein, R ^{1 to} R ⁴ are each independently
Represents a hydrogen atom, an alkyl group, an aryl group, an alkoxy group or a benzyl group).

[0009]

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(Wherein, R ^{5 to} R ⁸ are each independently
Represents a hydrogen atom, a lower alkyl group or an alkoxy group,
Each may be substituted plurally).

Next, the present invention will be described in detail.

The electrophotographic photoreceptor of the present invention is constituted by providing an organic photosensitive layer containing a binder resin, a charge generation material and a charge transport material on a conductive substrate. The organic photosensitive layer may be a single layer, or may be formed from a plurality of layers (for example, a charge generation layer and a charge transport layer). When the organic photosensitive layer has a plurality of layers, the electron transporting material represented by the general formula (I) and the hole transporting material represented by the general formula (II) are preferably contained in the same layer. 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 used in the present invention, 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) pyrrolohydrol, 2,
7-bis (2-hydroxy-3- (2-chlorophenylcarbamoyl) -1-naphthylazo) fluorenone and the like.

The charge transporting material used in the present invention is an electron transporting material represented by the above general formula (I) and a hole transporting material represented by the above general formula (II).

Further, in addition to the above charge transport materials, the following charge transport materials may be contained. For example, m-phenylenediamine compound; tetracyanoethylene;
Fluorenone compounds such as 7, -trinitro-9-fluorenone; nitrated 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; carbazole compounds such as poly-N-vinylcarbazole; pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline; ',
Amine derivatives such as 4 ″,-tris (N, N-diphenylamino) triphenylamine; 1,1-bis (4-diethylaminophenyl) -4,4-diphenyl-1,3-
Conjugated unsaturated compounds such as butadiene; hydrazone compounds such as 4- (N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone; indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds Compounds, nitrogen-containing cyclic compounds such as imidazole compounds, pyrazole compounds, pyrazoline compounds and triazole compounds; condensed polycyclic compounds and the like.

As the binder resin used in the present invention, all of those conventionally used in photoreceptor coating solutions can be used. For example, thermosetting silicone resins, epoxy resins, urethane resins, cured resins 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 polymer, Olefin polymers such as polyethylene, ethylene-vinyl acetate polymer, chlorinated polyethylene, polypropylene, and ionomer; polyvinyl chloride; vinyl chloride-vinyl acetate copolymer; polyvinyl acetate; saturated polyester; polyamide; thermoplastic urethane resin; ; Polyant Over preparative; polysulfone; ketone resins, polyvinyl butyral resins; polyether resins. When the organic photosensitive layer is formed of a plurality of layers, the binder resin can be used for forming each layer.

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

When the organic photosensitive layer is formed as a single layer,
The content of the charge generation material is determined by the binder resin 1 of the organic photosensitive layer.
It is preferably contained in the range of 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight, per 100 parts by weight. When the content of the charge generating material is less than 0.5 part by weight, the sensitivity of the obtained photoreceptor decreases. Conversely, if the content of the charge generating material exceeds 15 parts by weight, the abrasion resistance of the obtained photoconductor may be reduced.

The content of the electron transporting material represented by the general formula (I) is preferably in the range of 5 to 100 parts by weight based on 100 parts by weight of the binder resin of the organic photosensitive layer.
More preferably, it is 20 to 50 parts by weight. When the content of the electron transporting material is less than 5 parts by weight, the obtained photoreceptor has poor repetition characteristics. Conversely, if the content of the electron transport material exceeds 100 parts by weight, the abrasion resistance of the obtained photoconductor may be reduced. It is preferable that the content is 50 to 100 parts by weight based on 100 parts by weight of the charge generation material.

The content of the hole transporting material represented by the general formula (II) is preferably in the range of 10 to 200 parts by weight based on 100 parts by weight of the binder resin of the organic photosensitive layer. More preferably, it is 50 to 200 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 deteriorated. Conversely, when the content of the hole transport material exceeds 200 parts by weight, the abrasion resistance of the obtained photoconductor may be reduced. It is preferable that the content be 5 to 50 parts by weight based on 100 parts by weight of the charge generation material.

The content of the electron transporting material represented by the general formula (I) is 20 to 70% by weight in the charge transporting material.
And particularly preferably 20 to 50% by weight. When the content of the electron transporting material in the charge transporting material is less than 20% by weight, the obtained photoconductor has poor repetition characteristics. Conversely, when the content of the electron transport material exceeds 70% by weight, the sensitivity of the obtained photoreceptor deteriorates.

The content of the hole transporting material represented by the above general formula (II) is 20 to 70% by weight, particularly 20 to 50% 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 obtained photoreceptor has poor repetition characteristics. Conversely, if the content of the hole transport material exceeds 70% by weight, the sensitivity of the obtained photoreceptor deteriorates.

When the organic photosensitive layer is formed of a charge generation layer and a charge transport layer, the thickness of the charge generation layer is from 0.01 to
It is preferably 3 μm, more preferably 0.1 to 2 μm. The thickness of the charge transport layer is preferably 2 to 100 μm,
More preferably, it is 5 to 30 μm.

The content of the charge generating material is preferably in the range of 20 to 300 parts by weight, more preferably 50 to 100 parts by weight, based on 100 parts by weight of the binder resin of the organic photosensitive layer.
２００200 parts by weight. When the content of the charge generating material is less than 20 parts by weight, the charge generation density of the obtained photoreceptor is low, and when the content of the charge generating material exceeds 300 parts by weight, the mechanical strength of the obtained photoreceptor is low. It may decrease.

The content of the electron transporting material represented by the general formula (I) is preferably in the range of 5 to 100 parts by weight based on 100 parts by weight of the binder resin of the organic photosensitive layer.
More preferably, it is 20 to 50 parts by weight. When the content of the electron transporting material is less than 5 parts by weight, the obtained photoreceptor has poor repetition characteristics. Conversely, if the content of the electron transport material exceeds 100 parts by weight, the abrasion resistance of the obtained photoconductor may be reduced. It is preferable that the content is 50 to 100 parts by weight based on 100 parts by weight of the charge generation material.

The content of the hole transporting material represented by the general formula (II) is preferably in the range of 10 to 200 parts by weight based on 100 parts by weight of the binder resin of the organic photosensitive layer. More preferably, it is 50 to 200 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 deteriorated. Conversely, when the content of the hole transport material exceeds 200 parts by weight, the abrasion resistance of the obtained photoconductor may be reduced. It is preferable that the content be 5 to 50 parts by weight based on 100 parts by weight of the charge generation material.

The content of the electron transporting material represented by the above general formula (I) is 20 to 70% by weight in the charge transporting material.
And particularly preferably 20 to 50% by weight. When the content of the electron transporting material in the charge transporting material is less than 20% by weight, the obtained photoconductor has poor repetition characteristics. Conversely, when the content of the electron transport material exceeds 70% by weight, the sensitivity of the obtained photoreceptor deteriorates.

The content of the hole transporting material represented by the general formula (II) is 20 to 70% by weight, particularly 20 to 50% 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 obtained photoreceptor has poor repetition characteristics. Conversely, if the content of the hole transport material exceeds 70% by weight, the sensitivity of the obtained photoreceptor deteriorates.

The organic photosensitive layer may contain various additives such as an antioxidant and a quencher.

The conductive substrate used in the present invention is formed in an appropriate shape such as a sheet or a drum corresponding 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 a metal, or the base may be formed of a material having no conductivity, and a material having conductivity may be provided on the surface thereof. Good. As the conductive material, for example, alumite-treated or untreated aluminum,
Copper, tin, platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, brass, etc.Especially anodized by the alumite sulfate method and sealed with nickel acetate Treated aluminum is preferably used. In the case of a conductive substrate formed by providing a conductive material on the surface of a substrate made of a material having no conductivity, in the case of a synthetic resin substrate or a glass substrate, the above-described metal or the like is used. A thin film made of a conductive material such as aluminum iodide, tin oxide, or indium oxide is formed by a known film forming method such as a vacuum evaporation method or a wet plating method, and a film of the metal material or the like is formed on the surface of the base material. May be employed, or a substrate in which a substance imparting conductivity is injected into the surface of the substrate may be employed. 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 as needed to enhance the adhesion to the organic photosensitive layer.

In the electrophotographic photoreceptor of the present invention, when the organic photosensitive layer is a single layer, at least a binder resin, a charge generating material,
A coating solution obtained by dispersing the electron transport material represented by the general formula (I) and the hole transport material represented by the general formula (II) in dichloromethane or the like as a solvent or a dispersion medium,
It can be prepared by applying an ordinary photosensitive coating method such as a spray coating method, a dipping method or a flow coating method on a conductive substrate to form an organic photosensitive layer. When the organic photosensitive layer is a plurality of layers, at least a binder resin and a charge generating material are formed by applying a coating liquid obtained by dispersing at least a binder resin and a charge generating material in a solvent onto a conductive substrate, An electrophotographic photosensitive material is formed by further applying a coating solution in which the electron transport material represented by the general formula (I) and the hole transport material represented by the general formula (II) are dispersed in a solvent to form a charge transport layer. Body can be formed. After the charge transport layer is formed first, charge generation cleaning may be performed.

It is preferable to perform a heat treatment to reduce the residual amount of dichloromethane contained in the organic photosensitive layer. For example, the conductive substrate coated with the above coating solution is heated at a temperature of 50 ° C. or more for 60 minutes or more. Is preferred. If the heat treatment temperature is lower than the above conditions, the remaining amount of dichloromethane may not be able to be sufficiently reduced.

As the solvent or dispersion medium used in the coating solution, other solvents or dispersion mediums besides dichloromethane can be used alone or in combination with dichloromethane.

[0034] Examples of such a solvent or a dispersion medium include the following. 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; dimethyl ether, diethyl ether,
Ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethyl formamide; dimethyl sulfoxide and the like.

The coating solution can be 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. In preparing the coating solution, a surfactant, a leveling agent, and the like may be added in order to improve dispersibility, coatability, and the like.

[0036]

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

Examples 1 to 9 and Comparative Examples 1 to 3 5 parts by weight of metal-free phthalocyanine as a charge generating material, 40 parts by weight of a compound shown in Table 1 as a hole transporting agent,
Diphenoquinone compound 40 shown in Table 1 as an electron transport agent
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 with a paint shaker to prepare a coating solution for a single-layer type photosensitive layer. The prepared solution was applied on an aluminum foil with a wire bar, and dried by heating at 60 ° C. for 120 minutes to obtain an electrophotographic photoreceptor having a single-layer type photosensitive layer having a 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 3 were evaluated according to the following methods. The results are shown in Table 1.

1) Measurement of Initial Surface Potential V1sp A single-layer type electrophotographic photoreceptor was applied to an obtained photoreceptor by applying an applied voltage to the obtained photoreceptor using an electrostatic copying tester (EPA-8100 manufactured by Kawaguchi Electric Co., Ltd.) The surface potential was charged positively or negatively, and the surface potential V1 (V) was measured.

2) Measurement of half-life exposure amount E1 / 2 and residual potential V2 The charged photoreceptor was charged to a surface potential V1 of 1/2 using a halogen lamp as an exposure light source of an electrostatic copying tester.
The half-exposure amount E1 / 2 (lux ·
sec) was calculated. The surface potential 5 seconds after the exposure was measured and defined as a residual potential V2 (V).

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

4) Evaluation of light fastness The surface of the obtained photoreceptor is irradiated with light for 60 minutes by adjusting the amount of light to 1000 lux using a white fluorescent lamp.
Difference between surface potential and residual potential before and after {V1 and △
V2 was measured.

[0043]

[Table 1]

[0044]

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[0045]

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[0046]

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Table 1 shows that the electrophotographic photosensitive members of the examples have excellent repetition characteristics.

[0048]

As is apparent from the above description, according to the present invention, it is possible to provide an electrophotographic photosensitive member having high sensitivity and excellent repetition characteristics, light fastness and ozone fastness.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-127407 (JP, A) JP-A-3-256050 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 5/00-5/16

Claims (1)

(57) [Claims] 1. An electrophotographic photosensitive member having an organic photosensitive layer containing a charge generating material, an electron transporting material and a hole transporting material on a conductive substrate, wherein the electron transporting material has the following general formula (I) Wherein the hole transporting material is a compound represented by the following general formula (II): Embedded image (Wherein, R ^{1 to} R ⁴ each independently represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a benzyl group.) (In the formula, R ^{5 to} R ⁸ each independently represent a hydrogen atom, a lower alkyl group or an alkoxy group, and each may have a plurality of substituents.)