JPS6214656A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To form a laminate type electrophotographic sensitive body extremely high in sensitivity by using a specified polycyclic quinone type pigment as an electrostatic charge generating material for a charge generating layer and a specified hydrazone derivative for a charge transfer layer. CONSTITUTION:The charge generating layer contains by polycyclic quinone type pigment represented by formula I and the charge transfer layer contains the hydrazone derivative represented by formula II, typified by formula (2). When the charge transfer material is added to the charge generating layer, it is suitable to add the hydrazone derivative in an amount of 1-100pts.wt. per 100pts.wt. of the charge generating material from the viewpoint of high sensitivity, low residual potential, and repetition stability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an organic photoconductor, and particularly to an electrophotographic photoreceptor having a charge transport layer and a charge generation layer.

[Conventional technology]

Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been known so far.

On the other hand, since the discovery that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. For example, organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, carbazole,
Low-molecular organic photoconductors such as anthracene, pyrazolines, oxadiazoles, hydrazones, polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes Alternatively, organic pigments and dyes such as methine squaric acid dyes are known. In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded. Photoconductive organic pigments and dyes have been proposed.

For example, U.S. Patent Nos. 4,123,270 and 42
No. 47614, No. 4251613, No. f54251
No. 614, No. 4256821.

Same No. 4260672, Same No. 4268596, Same No. 4
As disclosed in No. 278,747 and No. 4,293,628, there are electrophotographic photoreceptors using a disazo pigment exhibiting photoconductivity as a charge generating substance in a photosensitive layer which is functionally separated into a charge generation layer and a charge transport layer. Are known.

Electrophotographic photoreceptors using such organic photoconductors can be produced by coating by appropriately selecting a binder, so it is possible to provide photoreceptors with extremely high productivity and at low cost. It has the advantage of being able to freely control the sensitive wavelength range.

A multilayer photoconductor obtained by laminating a charge transport layer and a charge generation layer mainly composed of a charge generation material has advantages over other single-layer photoconductors in terms of sensitivity and increased residual potential after durability tests. However, it was still not at a sufficient level.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks and provide a laminated electrophotographic photoreceptor with high sensitivity and extremely low residual potential even after a durability test.

The present invention aims to achieve the above object in a laminated electrophotographic photoreceptor having two layers, a charge generation layer containing a charge generation material as a main component and a charge transport layer containing a charge transport material as a main component, on a conductive support. This is achieved by using a specific polycyclic quinone pigment in the generation layer and a specific hydrazone compound in the charge transport layer.

[Means for solving problems]

The present invention provides a laminated type electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, in which the charge generation layer is comprised of a layer containing a polycyclic quinone pigment represented by the formula CI). , the charge transport layer has the general formula (II) (wherein R1 and R2 are a hydrogen atom, a halogen atom, a substituted or substituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted amine 7 represents a group, provided that at least one of R1 and R2 is a substituted amine group or an alkoxy group.R3 and R4 are
It represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted 7-aryl group, provided that at least one of R3 and R4 is a substituted or unsubstituted aryl group. Further, R3 and R4 may form a nitrogen-containing heterocycle.

R5, R6, R+, and R8 are hydrogen atoms, halogen atoms, substituted or unsubstituted alkyl groups, alkoxy groups,
The present invention is an electrophotographic photoreceptor characterized by comprising a layer containing a hydrazone compound represented by a substituted or unsubstituted 7-aryloxy group or a substituted amino group, where n is 0 or l.

The present invention will be explained in detail below.

In the laminated electrophotographic photoreceptor of the present invention, the charge generation layer contains as much charge generation material as possible in order to obtain sufficient absorbance, and in order to efficiently inject the generated charge carriers into the charge transport layer. It is desirable to use a 6M film layer, for example, a thin film layer with a thickness of 10 microns or less, preferably 0.01 micron to 1 micron.
Most of the incident light is absorbed by the charge generation layer to generate many charge carriers, and the generated charge carriers must be injected into the charge transport layer without being deactivated by recombination or trapping. It is caused by something.

The charge generating material used in the present invention is a polycyclic quinone pigment represented by formula (I).

The charge generation layer can be formed by coating the above-mentioned pigment and, if necessary, a charge transporting material together with a suitable binder (or without a binder) on the substrate, or by forming a vapor deposited film using a vacuum vapor deposition apparatus. can be obtained by

The binder that can be used when forming the charge generating layer by coating can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin,
polyamide, polyvinylpyridine, cellulose resin,
Examples include insulating resins such as urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone.・Resin contained in the charge generation layer is 80%
Weight % or less, preferably 40 weight % or less is suitable.

The solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the underlying charge generation layer or undercoat layer.

Specific organic solvents include methanol, ethanol,
Alcohols such as Impropatool, ketones such as acetone, methyl ethyl ketone, cyclohexanone, N, N
-dimethylformamide.

Amides such as N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol methyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, dichloroethylene , aliphatic halogenated hydrocarbons such as carbon tetrachloride and trichloroethylene, or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene and dichlorobenzene.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using a coating method such as a Mayer bar coating method, a blade coating method, a roller coating method, or a curtain coating method. Drying is
It is preferable to dry to the touch at room temperature and then heat dry. Heat drying can be carried out at 30° C. to 200° C. for a period of 5 minutes to 2 hours, either stationary or under ventilation.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and taking charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. have. At this time, this charge transport layer may be laminated on or under the charge generation layer.

The substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport substance) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The term "electromagnetic waves" as used herein includes the broad definition of "light rays" including γ-rays, X-rays, far-infrared rays, and the like. When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both layers trap each other, resulting in a decrease in sensitivity.

The charge transport material used in the present invention is a hydrazone compound represented by general formula (II).

R6N R8 (wherein R1 and R2 represent a hydrogen atom, a halogen atom, a substituted or substituted alkyl group, an alkoxy group, a substituted or unsubstituted 7-aryloxy group, or a substituted amine group, provided that at least one of R1 and R2 One is a substituted amine group or an alkoxy group. R3 and R4 are
It represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, provided that at least one of R3 and R4 is a substituted or unsubstituted aryl group. Furthermore, R3 and R4 may form a nitrogen-containing heterocycle,
R5, R6, R7, and R8 are hydrogen atoms, halogen atoms, substituted or unsubstituted alkyl groups, alkoxy groups,
(represents a substituted or unsubstituted 7-aryloxy group or a substituted amino group, n represents O or 1) This hydrazone compound satisfies the above-mentioned conditions as a charge transporting substance, particularly sensitivity.

It has excellent properties in terms of durability.

Typical hydrazone compounds represented by the general formula (n) used in the present invention are illustrated in Table 1.

Table 1a Table 1b Furthermore, in the present invention, the above-mentioned hydrazone compound used in the charge transport layer can be added to the charge generation layer, and the sensitizing effect thereof becomes even more remarkable.

When a heavy transport material is added to the charge generation layer, the hydrazone compound should be 10 times or less (weight ratio), preferably 0.01 to 1 times (weight ratio) of the charge generation material to achieve high sensitivity, low residual potential, and repeated stability. It is appropriate from a gender perspective.

To form a charge transport layer containing a hydrazone compound, a film can be formed by selecting an appropriate binder. Resins that can be used as binders include, for example, acrylic resins, polyacrylates, polyesters, polycarbonates, polystyrene, acrylonitrile-styrene copolymers, acrylonitrile-butadiene copolymers,
Examples include insulating resins such as polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, and chlorinated rubber, and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

The charge transport layer cannot be made thicker than necessary because there is a limit to its ability to transport charge carriers. Generally, the thickness is 5 to 30 microns, but the preferred range is 8 to 20 microns. be. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a substrate having a conductive layer, that is, a conductive support. The substrate having a conductive layer is one which itself has conductivity, such as aluminum, aluminum alloy, copper, and zinc.

Stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used, and in addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. can be coated by vacuum evaporation method. A substrate in which a plastic having a formed layer (e.g. carbon black, silver particles, etc.) is coated on a plastic together with a suitable binder, a substrate in which plastic or paper is impregnated with conductive particles, a plastic having a conductive polymer, etc. are used. be able to.

A subbing layer having a barrier function and an adhesive part can also be provided between the conductive layer and the photosensitive layer. The subbing layer is casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
Acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 61O1 copolymerized nylon, alkoxymethylated nylon, etc.).

It can be formed from polyurethane, gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is suitably 0.1 to 40 microns, preferably 0.1 to 3 microns. A photoreceptor is used in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order. In this case, when the charge transport material in the charge transport layer is made of an electron transport material, it is necessary to positively charge the surface of the charge transport layer, and when exposed to light after charging, the electrons generated in the charge generation layer are transferred to the charge transport layer in the exposed area. The material is injected and then reaches the surface to neutralize the positive charge, causing attenuation of the surface potential and creating an electrostatic contrast with the unexposed area. A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed.

Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, and then visually imaged and fixed. The type of developer, the developing method, and the fixing method may be any known ones or known methods, and are not limited to specific ones.

On the other hand, when the charge transport material consists of a hole transport material, the surface of the charge transport layer must be negatively charged, and when exposed to light after charging, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. , which then reaches the surface and neutralizes the negative charges, resulting in attenuation of the surface potential and an electrostatic contrast between the surface potential and the unexposed area.

During development, it is necessary to use a positively charged toner, contrary to the case where an electron transport material is used.

The electrophotographic photoreceptor according to the present invention is susceptible to deterioration due to ultraviolet rays, ozone, etc., dirt from oil, etc., scratches from metal chips, etc., damage to the photoreceptor due to photoreceptor contact members such as developing members, transfer members, cleaning members, etc. A protective layer may be further provided on the charge generation layer or the charge transport layer for the purpose of preventing abrasion. In order to form an electrostatic latent image on this protective layer,
It is desirable that the surface resistivity is 1011Ω or more.

The protective layer used in the present invention is made of resin such as polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer, etc. It can be formed by applying a solution dissolved in an appropriate organic solvent onto the photosensitive layer and drying it.

Moreover, additives such as ultraviolet absorbers can be added to the resin liquid. At this time, the thickness of the protective layer is generally 0.05~
20 microns, particularly preferably in the range 0.2 to 5 microns.

Hereinafter, the present invention will be explained according to examples.

Example 1 An ammonia aqueous solution of casein (1.2 g of casein I, 1 g of 28% ammonia water, 222 m of water) was coated on an aluminum cylinder using a coating method, and dried to form a subbing layer with a coating amount of 1.0 g/ba. was formed.

Next, 1 part by weight of a charge generating material represented by formula (I), 1 part by weight of butyral resin (S-LEC BM-2: manufactured by Sekisui Chemical Co., Ltd.)
Parts by weight and 30 parts by weight of isopropyl alcohol were dispersed for 4 hours using a ball mill disperser.

This dispersion was applied onto the previously formed subbing layer by a dip coating method and dried to form a charge generating layer. The film thickness at this time was 0.3 JL.
1 part by weight of the hydrazone compound (1), 1 part by weight of polysulfone resin (P1700, manufactured by Union Carbide), and 6 parts by weight of monochlorobenzene were mixed and dissolved by stirring with a stirrer.

This liquid was applied onto the charge generation layer by dip coating and dried to form a charge transport layer. The film thickness at this time is
It was for business.

A corona discharge of 15 KV was applied to the photoreceptor thus prepared. The surface potential at this time was measured (initial potential Vo),
Furthermore, the surface potential of this photoreceptor was measured after leaving it in the dark for 5 seconds (dark decay v5). /2
The evaluation was made by measuring 1 ux@sec).

These results were as follows.

Vo: -585 volts Vs: -575 volts El/2: 5.4 sentences ux*sec Examples 2 to 5 Compound No. (1) used in Example 1 was replaced with the compound shown in Table 1, respectively. Example 1 except that
A photoreceptor was prepared in exactly the same manner as described above, and the characteristics of this photoreceptor were measured. These results are shown in Table 2.

Table 2 Example Compound No VO(-V) V5(-V)
El/2 sentence uxasec 2 2 5805705.2 3 3 5905805.9 4 4 5855755.8 5 5 5955856.3 Comparative Examples 1 to 6 The charge transport substances shown in Table 3 were used in place of the hydrazone compound used in Example 1. A photoreceptor was produced in exactly the same manner except for the following. The charging characteristics are shown in Table 4.

Table 3 Comparative example Comparative charge Comparative charge transport material structural formula Comparative example
Comparative charge Comparative charge transport material structural formula transport object Kayo table 4 Comparative example Comparative charge Vo (-V) Vs (-V) E
l/2 transport substance 1”) 9.ux*
5ec1 1 5905657.4 2 2 5805507.0 3 3 5905657.6 4 4 6055808.1 5 5 5855607.2 6 6 5805557.6 As is clear from the results of the examples and comparative examples, The type photoreceptors are comparative example photoreceptors No. 1 to 3,
It can be seen that a photoreceptor with extremely high sensitivity was obtained compared to No. 6. Further, the photoreceptors of Examples 1 to 3 were used in a copying machine (NP-15
02: Image output using Canon Inc.)
Repeated 000 times. As a result, both photoreceptors had 200
Good quality images were obtained even after 00 repetitions. As a result, it can be seen that the photoreceptor of the present invention has extremely excellent durability.

〔Effect of the invention〕

As is clear from the above, the present invention uses a specific polycyclic quinone pigment as a charge generation material in the charge generation layer and a specific hydrazone compound in the charge transport layer, thereby achieving extremely high sensitivity compared to conventional ones. Our aim is to provide a highly refined layer type electrophotographic photoreceptor.

Claims (2)

[Claims] (1) In a laminated photographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, the charge generation layer has the formula (
I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼It consists of a layer containing a polycyclic quinone pigment represented by (I), and the charge transport layer is the general formula (II).▲There are mathematical formulas, chemical formulas, tables, etc.▼(II ) (In the formula, R_1 and R_2 represent a hydrogen atom, a halogen atom, a substituted or substituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted amino group. However, at least one of R_1 and R_2 is a substituted amino group or an alkoxy group. R_3 and R_4 represent a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. However, at least one of R_3 and R_4 is a substituted or unsubstituted aryl group. is an aryl group.R_3 and R4 may also form a nitrogen-containing heterocycle.R_5, R_6, R_7, and R_
8 represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted amino group. n is 0 or 1
shows. ) An electrophotographic photoreceptor comprising a layer containing a hydrazone compound represented by: (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).