JPH0677156B2 - Electrophotographic photoconductor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photoconductor for electrophotography, and more specifically,
The present invention relates to an electrophotographic photoreceptor provided with a photosensitive layer containing a disazo pigment as a substance that generates a charge carrier when irradiated with light (hereinafter referred to as "charge generating substance").

2. Description of the Related Art As an electrophotographic photoconductor, an inorganic photoconductor using selenium and its alloy, a photoconductor in which dye-sensitized zinc oxide is dispersed in a binder resin, or an organic photoconductor is used. Typical examples include those using a charge transfer complex of 2,4,7-trinitro-9-fluorenone (hereinafter referred to as “TNF”) and poly-N-vinylcarbazole (hereinafter referred to as “PVK”). ing.

However, these photoreceptors have many advantages and, at the same time, have various drawbacks. For example, selenium photoconductors that are widely used at present have difficult manufacturing conditions, are expensive to manufacture, are difficult to process into a belt because they are not flexible, and are sensitive to heat and mechanical shock. Therefore, handle with care. Zinc oxide photoconductor can be manufactured by coating a support with inexpensive zinc oxide, so the cost is low, but in general, sensitivity is low, surface smoothness, hardness, tensile strength, abrasion resistance, etc. It has mechanical defects, and there are many problems such as durability as a photoreceptor for a plain paper copying machine which is usually used repeatedly. Further, a photoconductor using a charge transfer complex of TNF and PVK has low sensitivity and is not suitable as a photoconductor for a high speed copying machine.

In recent years, extensive research has been conducted in order to eliminate the drawbacks of these photoconductors, and in particular, various organic photoconductors have been proposed. Above all, a laminated type photoreceptor in which a thin film of an organic pigment is formed on a conductive support (charge generation layer) and a layer (charge transfer layer) mainly containing a charge transfer substance is formed on the conductive support is a conventional organic material type. Compared with the photoconductor of No. 1), it is attracting attention as a photoconductor for a plain paper copying machine because of its high general sensitivity and stable charging property, and some of them have been put to practical use.

This type of conventional laminated-type photoreceptor (1) a thin layer obtained by vacuum-depositing a perylene derivative as a charge generation layer and an oxadiazole derivative as a charge transport layer (see USP 3871882) (2) It is known that a thin layer formed by applying an organic amine solution of chlordian blue is used as the charge generation layer and a hydrazone compound is used as the charge transport layer (see Japanese Patent Publication No. 55-42380).

However, it is a fact that even the laminated type photoreceptor of this type has many advantages and various drawbacks at the same time. That is, it has the following drawbacks.

The photoreceptor using the perylene derivative and the oxadiazole derivative shown in (1) has a high manufacturing cost because the charge generation layer is formed by vacuum deposition.

The photoreceptor using the chlordyan blue and the hydrazone compound shown in (2) needs to use an organic amine (for example, ethylenediamine), which is generally difficult to handle, as a coating solvent for forming the charge generation layer. There are many downsides.

Object The present invention aims to provide a photoconductor that overcomes the above-mentioned conventional drawbacks.

Structure The electrophotographic photoreceptor of the present invention is characterized in that a photosensitive layer containing a disazo pigment represented by the following general formula (I) as a charge generating substance is provided on a conductive support.

(In the formula, A is Or R ₁ represents a hydrogen atom, a lower alkyl group or a phenyl group.) Incidentally, in view of the above-mentioned conventional drawbacks, the present inventor aims to develop a highly sensitive electrophotographic photoreceptor that can be easily produced. As a result of intensive studies, it has been found that the above object can be achieved by using a specific disazo compound represented by the general formula (I) as a charge generating substance, and the present invention has been completed based on it. It is a thing.

Specific examples of the disazo pigment represented by the general formula (I) used in the present invention are shown by the structural formulas as follows.

By using the disazo pigment of the present invention as described above, a highly sensitive electrophotographic photoreceptor can be easily manufactured.

The disazo pigment of the present invention is commercially available (for example, commercially available from Wako Pure Chemical Industries, Ltd.) 3,3 ′, 5,
Diazotization of 5'-tetramethylbenzidine by a conventional method to give a tetrazonium salt, and a coupling reaction is carried out by reacting the tetrazonium salt with a corresponding coupler in a suitable organic solvent such as N, N-dimethylformamide with a base. Can be easily manufactured by.

In the electrophotographic photosensitive member of the present invention, the disazo pigment is used as a charge generating substance in the photosensitive layer, and a typical constitution of this photosensitive member is shown in FIGS. 1 and 2.

The photoreceptor shown in FIG. 1 has a disazo pigment on a conductive support 11.
A laminate type photosensitive layer 191 including a charge generation layer 15 mainly composed of 13 and a charge transport layer 17 mainly composed of a charge carrier substance is provided.

In the photoreceptor of FIG. 1, the imagewise exposed light passes through the charge transport layer and reaches the charge generation layer 15, where the disazo pigment is present.
On the other hand, the charge is generated at 13, while the charge transfer layer 17 receives and injects the charge, and the disazo pigment 13 generates the charge necessary for light attenuation, and the charge transfer is performed by the charge transfer. It is a mechanism called in layer 17.

The optical member shown in FIG. 2 has a photosensitive layer 192 mainly composed of a disazo pigment 13, a charge carrier substance and an insulating binder on a conductive support 11. Here again, the disazo pigment 13 is a charge generating substance.

As another photoreceptor, the charge generation layer and the charge transport layer in FIG. 1 may be reversed.

The thickness of the photosensitive layer is as shown in FIG. 1, and the thickness of the charge generation layer 15 is preferably 0.01 to 5 μ, more preferably 0.05 to 2 μ. If this thickness is 0.01 μm or less, the generation of electric charges is not sufficient, and if it is 5 μm or more, the residual potential is high and it cannot be put to practical use. The thickness of the charge transport layer 17 is preferably 3 to 50 μ, more preferably 5 to 20 μ. If this thickness is 3 μm or less, the charge amount is insufficient, and if it is 50 μm or more, the residual potential is high and it is not practical.

The charge generation layer 15 is mainly composed of the disazo pigment represented by the above general formula, and may further contain a binder, a plasticizer and the like. The proportion of the disazo pigment in the charge generation layer is preferably 30% by weight or more, more preferably 50% by weight or more.

The charge transport layer 17 is mainly composed of a charge transport material and a binder, and may further contain a plasticizer and the like. The proportion of the charge carrier material in the charge carrier layer is 10 to 95% by weight, preferably 30 to 90%.
% By weight. If the proportion of the charge carrier material is less than 10% by weight, the charge carrier is hardly transferred, and
If it is more than 5% by weight, the mechanical strength of the photoreceptor film is extremely poor and it cannot be put to practical use.

In the case of the photoreceptor shown in FIG. 2, the thickness of the photosensitive layer 192 is preferably 3 to 50 μ, more preferably 5 to 20 μ.
The proportion of the disazo pigment in the photoconductor 192 is preferably 5
0 wt% or less, more preferably 20 wt% or less,
The proportion of the charge carrier substance is preferably 10 to 95% by weight, more preferably 30 to 90% by weight.

The present invention is based on the use of the specific disazo pigment represented by the general formula (I) as a charge generating substance in an electrophotographic photoreceptor, and a conductive support,
As the other components such as the charge carrier substance, any of those conventionally known can be used, which will be specifically described below.

As the conductive support used in the photoreceptor of the present invention, aluminum, copper, a metal plate such as zinc, a plastic sheet such as polyester or a plastic film aluminum, a conductive material such as SnO ₂ is deposited, or Electrically treated paper or the like is used.

Examples of the binder include condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone, and polycarbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide. Any adhesive and adhesive resin can be used.

Examples of the plasticizer include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl phthalate and the like. In addition, silicone oil or the like may be added to improve the surface property of the photoreceptor.

The charge carrier material includes a hole carrier material and an electron carrier material.
As the hole-transporting substance, for example, the following general formula (1) to
Examples thereof include the compounds shown in (11).

[In the formula, R ₁₁₅ represents a methyl group, an ethyl group, a 2-hydroxyethyl group or a 2-chloroethyl group, and a R ₁₂₅ represents a methyl group, an ethyl group, a vedizyl group or a phenyl group, and R
₁₃₅ is hydrogen, chlorine, bromine, an alkyl group having 1 to 4 carbon atoms,
It represents an alkoxyl group having 1 to 4 carbon atoms, a dialkylamino group or a nitro group. ] [In the formula, Ar ₃ represents a naphthalene ring, an anthracene ring, a styryl group and a substitution product thereof, a pyridine ring, a furan ring or a thiophene ring, and R ₁₄₅ represents an alkyl group or a benzyl group. ] [In the formula, R ₁₅₅ is an alkyl group, a benzyl group, a phenyl group,
Represents a naphthyl group, R ₁₆₅ represents hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group, a diaralkylamino group or a diarylamino group, and n is an integer of 1 to 4. When n is 2 or more, R ₁₆₅ may be the same or different. R ₁₇₅ represents hydrogen or a methoxy group. ] [In the formula, R ₁₈₅ represents an alkyl group having 1 to 11 carbon atoms, a substituted or unsubstituted phenyl group or a heterocyclic group, and R ₁₉₅ , R
₂₀₅ may be the same or different and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a chloroalkyl group, a substituted or unsubstituted aralkyl group,
R ₁₉₅ and R ₂₀₅ may be bonded to each other to form a nitrogen-containing heterocycle. R ₂₁₅ may be the same or different and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group or halogen. ] [In the formula, R ₂₂₅ represents hydrogen or a halogen atom, and Ar ₄
Represents a substituted or unsubstituted phenyl group, naphthyl group, anthryl group or carbazolyl group. ] [In the formula, R ₂₃₅ is hydrogen, halogen, a cyano group, or a carbon number of 1 to 1.
4 represents an alkoxy group having 4 or an alkyl group having 1 to 4 carbon atoms, and Ar ₅ is R ₂₄₅ represents an alkyl group having 1 to 4 carbon atoms,
R ₂₅₅ represents hydrogen, halogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a dialkylamino group, n is 1 or 2, and when n is 2, R ₂₅₅
May be the same or different, and R ₂₆₅ and R ₂₇₅ represent hydrogen, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted benzyl group. ] [In the formula, R ₂₈₅ and R ₂₉₅ are a carbazolyl group, a pyridyl group,
Cenyl group, indolyl group, furyl group or substituted or unsubstituted phenyl group, styryl group, naphthyl group or anthryl group, wherein these substituents are dialkylamino group, alkyl group, alkoxy group, carboxy group or ester thereof Represents a group selected from the group consisting of a halogen atom, a cyano group, an aralkylamino group, an N-alkyl-Naralkylamino group, an amino group, a nitro group and an acetylamino group. ] [In the formula, R ₃₀₅ represents a lower alkyl group or a benzyl group, and R ₃₁₅ represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a halogen atom, a nitro group, an amino group, or an amino substituted with a lower alkyl group or a benzyl group. Represents a group, and n represents an integer of 1 or 2. ] (In the formula, R ₃₂₅ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, R ₃₃₅ and R ₃₄₅ represent an alkyl group, a substituted or unsubstituted aralkyl group or a substituted or unsubstituted aryl group, R ₃₅₅ Represents a hydrogen atom or a substituted or unsubstituted phenyl group, and Ar ₆
Represents a phenyl group or a naphthyl group. ] [In the formula, n is an integer of 0 or 1, R ₃₆₅ is a hydrogen atom, an alkyl group or a substituted or unsubstituted phenyl group,
A ₁ is Represents a 9-anthryl group or a substituted or unsubstituted N-alkylcarbazolyl group, wherein R ₃₇₅ is a hydrogen atom,
Alkyl group, alkoxy group, halogen atom or (Wherein R ₃₈₅ and R ₃₉₅ represent an alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, and R ₃₈₅ and R ₃₉₅ may form a ring),
m is an integer of 0, 1, 2 or 3, and when m is 2 or more, R ₃₇₅ may be the same or different. ] [In the formula, R ₄₀₅ , R ₄₁₅ and R ₄₂₅ represent hydrogen, a lower alkyl group, a lower alkoxy group, a dialkylamino group or a halogen atom, and n represents 0 or 1. Examples of the compound represented by the general formula (1) include 9-ethylcarbazole-3-aldehyde, 1-methyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde 1-benzyl-1-phenylhydrazone, 9- Examples include ethylcarbazole-3-aldehyde 1,1-diphenylhydrazone.

Examples of the compound represented by the general formula (2) include 4-diethylaminostyrene-β-aldehyde 1-methyl-1.
-Phenylhydrazone, 4-methoxynaphthalene-1-
Aldehyde 1-benzyl-1-phenylhydrazone and the like.

Examples of the compound represented by the general formula (3) include 4-methoxybenzaldehyde 1-methyl-1-phenylhydrazone, 2,4-dimethoxybenzaldehyde 1-benzyl-1-phenylhydrazone, 4-diethylaminobenzaldehyde 1,1-diphenyl. Hydrazone, 4-methoxybenzaldehyde 1-benzyl-1- (4-methoxy) phenylhydrazone, 4-diphenylaminobenzaldehyde 1-benzyl-1-phenylhydrazone, 4
-Dibenzylaminobenzaldehyde-1,1-diphenylhydrazone and the like.

Examples of the compound represented by the general formula (4) include 1,1-
Bis (4-dibenzylaminophenyl) propane, tris (4-diethylaminophenyl) methane, 1,1-bis (4-dibenzylaminophenyl) propane, 2,2'dimethyl-4,4'-bis (diethylamino) -Such as triphenylmethane.

Examples of the compound represented by the general formula (5) include 9-
Examples include (4-diethylaminostyryl) anthracene and 9-bromo-10- (4-diethylaminostyryl) anthracene.

Examples of the compound represented by the general formula (6) include 9-
(4-Dimethylaminobenzylidene) fluorene, 3-
(9-fluorenylidene) -9-ethylcarbazole and the like.

Examples of the compound represented by the general formula (7) include 1,2-
Bis (4-diethylaminostyryl) benzene, 1,2-
There is bis (2,4-dimethoxystyryl) benzene.

Examples of the compound represented by the general formula (8) include 3-styryl-9-ethylcarbazole and 3- (4-methoxystyryl) -9-ethylcarbazole.

Examples of the compound represented by the general formula (9) include 4-diphenylaminostilbene, 4-dibenzylaminostilbene, 4-ditolylaminostilbene, 1- (4-diphenylaminostyryl) naphthalene, 1- (4-diethylamino). Styryl) There is naphthylene.

The compound represented by the general formula (10) includes, for example, 4'-
Examples include diphenylamino-α-phenylstilbene and 4′-methylphenylamino-α-phenylstilbene.

Examples of the compound represented by the general formula (11) include 1-phenyl-3- (4-diethylaminostyryl) -5-
(4-Diethylaminophenyl) pyrazoline, 1-phenyl-3- (4-dimethylaminostyryl) -5- (4
-Dimethylaminophenyl) pyrazoline and the like.

Other hole-transporting substances include, for example, 2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole and 2,5-bis [4- (4-diethylaminostyryl) phenyl]- 1,3,4-oxadiazole, 2- (9
Oxadiazole compounds such as -ethylcarbazolyl-3-)-5- (4-diethylaminophenyl) -1,3,4-oxadiazole, 2-vinyl-4- (2-chlorophenyl) -5- There are low molecular compounds such as oxazole compounds such as (4-diethylaminophenyl) oxazole and 2- (4-diethylaminophenyl) -4-phenyloxazole. Further, polymer compounds such as poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, pyreneformaldehyde resin and ethylcarbazoleformaldehyde resin can also be used.

Examples of the electron carrier include chloranil, bromanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4,7-trinitro-9-fluorenone, 2,
4,5,7-Tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2- b] Thiofen-4-one, 1,3,7-trinitrodibenzothiophen-5,5-dioxide and the like.

These charge carrier substances may be used alone or in combination of two or more.

In each of the photoreceptors obtained as described above, an adhesive layer or a barrier layer can be provided between the photoreceptors of the conductive support, if necessary. Polyamide, nitrocellulose, aluminum oxide and the like are suitable as materials used for these layers, and the film thickness is preferably 1 μm or less.

In order to prepare the photoreceptor of FIG. 1, the disazo pigment on the conductive support is vacuum-deposited by the vacuum deposition method described in USP3,973,959, USP3,996,049, or fine particles of the disazo pigment are used. Is dispersed in a suitable solvent in which a binder is dissolved, and this is coated and dried on a conductive support, and if necessary, it is disclosed in, for example, JP-A-51-90827. It can be obtained by finishing the surface by a method such as buffing or adjusting the film thickness, and then coating and drying a solution containing a charge carrier substance and a binder.

To prepare the photoreceptor of FIG. 2, fine powder of disazo pigment may be dispersed in a solution in which a charge carrier substance and a binder are dissolved, and this may be coated and dried on a conductive support.

In any case, the disazo pigment used in the present invention is pulverized with a ball mill or the like to have a particle size of 5 μm or less, preferably 2 μm or less. The coating method is carried out by a conventional means such as doctor blade, dipping, wire bar or the like.

In order to perform copying using the photoreceptor of the present invention, the surface of the photosensitive layer is charged and exposed, and then developed, and if necessary,
This is achieved by transferring to paper or the like.

As is clear from the above description and the examples described below,
The electrophotographic photoreceptor of the present invention uses the disazo pigment represented by the general formula (I) as a charge generating substance.
It has excellent properties such as easy manufacture as compared with conventional photoconductors, high sensitivity, and stable properties even after repeated use of the photoconductor.

Next, the present invention will be specifically described with reference to examples, but the embodiments of the present invention are not limited thereby.

Example 1 76 parts by weight of disazo pigment No. 1, 1260 parts by weight of a polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.) in tetrahydrofuran (solid concentration 2%), and tetrahydrofuran
3700 parts by weight are crushed and mixed in a ball mill, and the resulting dispersion is applied on the aluminum surface of an aluminum vapor-deposited polyester base (conductive support) using a doctor blade, and naturally dried to a thickness of about 1 μm. The charge generation layer of was formed.

On this charge generation layer, 2 parts by weight of 9-ethylcarbazole-3-aldehyde 1-methyl-1-phenylhydrazone as a charge carrier substance, 2 parts by weight of a polycarbonate resin (Panlite K-1300 manufactured by Teijin Ltd.) and tetrahydrofuran.
A solution prepared by mixing and dissolving 16 parts by weight was applied using a doctor blade and dried at 80 ° C. for 2 minutes and then at 105 ° C. for 5 minutes to form a charge transport layer having a thickness of about 20 μm, which is shown in FIG. A laminated type photoconductor No. 1 was prepared.

Examples 2 to 5 Photosensitive member No. 2-5 was prepared in the same manner as in Example 1 except that the disazo pigment and the charge carrier substance used in Example 1 were those shown in Table 1.

These photoconductors Nos. 1 to 5 were set to −6 KV using an electrostatic copying paper tester (SP428 type manufactured by Kawaguchi Electric Co., Ltd.).
After 20 seconds of corona discharge to make it negatively charged,
Let stand for 2 seconds in the dark, measure the surface potential Vpo (V) at that time, then irradiate light with a tungsten lamp so that the surface has an illuminance of 4.5 lux, and the surface potential becomes half of Vpo Exposure time E1
/ 2 (lux seconds) was calculated. The results are shown in Table-1.

Effects From the results shown in Table 1 above, it can be seen that the photoconductor of the present invention has high sensitivity.

Further, the photoconductors No. 2 and No. 3 of the present invention were mounted on a copying machine Recopy P-500 type manufactured by Ricoh Co., Ltd. and image output was repeated 10,000 times. A clear image was obtained without any change. From this, it can be understood that the photoreceptor of the present invention is also excellent in durability.

[Brief description of drawings]

1 and 2 are enlarged cross-sectional views showing a constitutional example of the photoconductor of the present invention. 11 ... Conductive support, 13 ... Disazo pigment 15 ... Charge generation layer, 17 ... Charge transport layer 191,192 ... Photosensitive layer

Claims (1)

[Claims] 1. A compound of general formula (I) on a conductive support. (In the formula, A is Or Wherein R ₁ represents a hydrogen atom, a lower alkyl group or a phenyl group), and a layer containing a disazo pigment represented by the formula) is formed as an active ingredient.