JPS61292155A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity of a photosensitive body by forming an electrostatic charge generating layer and a charge transfer layer each having a specified composition on a conductive substrate. CONSTITUTION:A laminate type electrophotographic sensitive body high in sensitivity can be obtained by forming on the conductive substrate the charge generating layer containing the polycyclic quinone type pigment represented by formula (I), and the charge transfer layer containing the hydrazone derivative represented by formula (II) in which each of R1, R2 is H, halogen, nitro, alkoxy, optionally substituted aryloxy, such amino; each of R3, R4 is optionally substituted alkyl or such aryl; and each of R5, R6, R7, R8 is H, halogen, nitro, optionally substituted alkyl or alkoxy, such aryloxy, such acyl, or such amino.

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 generation layer and a charge transport layer.

[Prior art] Electrophotographic photoreceptors using inorganic photoconductors such as selenium, sulfide repellent aluminum, and zinc oxide as photosensitive components have been known. 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 and polyvinylanthracene, low-molecular organic photoconductors such as carbazole, anthracene, pyrazolines, oxadiazoles, 1-hydrazones, and polyarylalkane, and phthalocyanine. Organic pigments and dyes such as pigments, azo pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and methine squaric acid dyes are known. In particular, photoconductive organic pigments and dyes are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has expanded, making it possible to use a large number of photoconductive compounds. Conductive organic pigments and dyes have been proposed. For example, U.S. Patent Nos. 4,123,270 and 42
47614, 4251613, 7 4251
No. 614, No. 4256821, No. 4260672
A disazo pigment that exhibits photoconductivity as a charge-generating substance in a photosensitive layer that is functionally separated into a charge-generating layer and a charge-transporting layer as disclosed in the specifications of No., No. 4268596, No. 4278747, No. 4293628, etc. Electrophotographic photoreceptors using the same are known. Electrophotographic photoreceptors using such organic photoconductors can be produced by coating by appropriately selecting a binder, making it possible to provide photoreceptors with extremely high productivity and low cost. It has the advantage of being able to freely control the sensitive wavelength range.

A multilayer photoreceptor obtained by laminating a charge-generating layer mainly composed of charge transport i and a charge-generating material has advantages over other single-layer photoreceptors in terms of sensitivity and increased residual potential after durability tests. However, it was still viable, albeit at a sufficient level.

[Problems to be Solved by 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.

[Means and actions for solving the problem of illumination] The present invention aims to achieve the above-mentioned purpose by forming 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 charge generation layer and a specific hydrazone compound in the charge ring layer in a laminated electrophotographic photoreceptor having two layers. .

The present invention provides a laminated 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 of structural formula (I), The charge transport layer is a hydrazone compound represented by the general formula (II) (wherein R and R2 are a hydrogen atom, a halogen atom, a nitro group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted aryloxy group). represents an amine group, provided that at least one of R1 and R2 is a substituted amino group or an alkoxy group, R1 and R1 represent a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, provided that R3 and R .

At least one of them is a substituted or unsubstituted aryl group, and RX and Machi may complete a nitrogen-containing heterocycle, and R5, R6, R2 and R# are hydrogen atoms, halogen atoms, nitro groups, A layer containing a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted 7-mino group It consists of a photographic photoreceptor.

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. and a thin film layer, for example less than 10 IL, preferably 0.
It is desirable that the thin film layer has a thickness of 01 to 1JL. This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are injected into the charge transport layer without being deactivated by recombination or trapping. This is due to the need to do so.

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

The charge generation layer can be formed by coating the above-mentioned pigment and, if necessary, a charge transport material together with a suitable binder (or without a binder) on a 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, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, Examples include insulating resins such as casein, polyvinyl alcohol, and polyvinylpyrrolidone.

The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

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 transport layer or subbing layer.

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

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

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 coach ink method, or a curtain coating method.

For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying at a temperature of 30 to 200°C for 5 minutes or more
It can be carried out stationary or under draft for a period of time in the range of 2 hours.

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 liquid wall of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both trap each other, resulting in a decrease in sensitivity.

The charge transport substance used in the present invention has the general formula (II)
It is a hydrazone compound represented by

(In the formula, R5 and R2 represent a hydrogen atom, a halogen atom, a nitro group, an alkoxy group, a substituted or unsubstituted arylene group, or a substituted or unsubstituted amino group, provided that R
At least one of 5 and R2 is a substituted amino group or an alkoxy group, R3 and R4 represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, provided that RJ,! at least one of l-R,1,
one is a substituted or unsubstituted aryl group, and R3
and R4 may complete the nitrogen-containing heterocycle, R5, R4,
R7 and R6 represent a hydrogen atom, a halogen atom, a nitro group, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted amine group. ).

This hydrazone compound satisfies the above-mentioned conditions as a charge transport material, and has excellent properties particularly in terms of sensitivity and durability.

Representative examples of the hydrazone compounds used in the present invention are shown below.

Further, in the present invention, the above-mentioned hydrazone compound used in the charge transport layer can be added to the charge generation layer.
The sensitizing effect becomes even more remarkable. When adding a charge transporting material to the charge generation layer, the hydrazone compound should be added in an amount not more than 10 times (weight ratio) as much as the charge generation material, preferably 0.0
A ratio of 1-1 times (weight ratio) is suitable from the viewpoints of high sensitivity, low residual potential, and repeated stability. 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 resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, etc. Insulating resin or poly-N-vinylcarbazole,
Organic photoconductive polymers such as polyvinylanthracene and polyvinylpyrene may be mentioned.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally, it is 5 to 30 IL, but the preferred range is 8 to 20 g,
It is. 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. Examples of the substrate having a conductive layer include those whose substrate itself is conductive, such as aluminum, aluminum alloy, copper, 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 layer of plastic (e.g. polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoroethylene, etc.) with a formed layer, conductive particles (e.g. carbon black, silver particles, etc.) on top of the plastic with a suitable binder. A substrate coated with a conductive material, a substrate obtained by impregnating a plastic or paper with conductive particles, a plastic having a conductive polymer, etc. can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer.

The subbing layer consists of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6).
, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The appropriate thickness of the undercoat layer is 0.1 to 40 mm, preferably 0.1 to 3 mm.

When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material in the charge transport layer is composed of an electron transport material, the surface of the charge transport layer must be positively charged; When exposed to light after being charged, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the surface and neutralize the positive charge, resulting in attenuation of the surface potential and an electrostatic contrast between it and the unexposed area. occurs.

A visible image is 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 methods, and are not limited to specific ones or methods.

On the other hand, when the charge transport material is a hole transport material, it is necessary to charge the surface of the charge transport layer negatively, 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 charge, resulting in an attenuation of the surface potential and an electrostatic contrast with 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., and damage to the photoreceptor due to photoreceptor contact members such as developing members, transfer members, and cleaning members. A protective layer may be further provided on the charge generation layer for the purpose of preventing scratching.In order to form an electrostatic latent image on this protective layer, a surface resistivity of 101 is required.
It is desirable that the resistance is 3Ω or more. The protective layer used in the present invention is made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene.
It can be formed by dissolving a resin such as butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer or the like in a suitable organic solvent and coating the photosensitive layer on 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 to 20 IL, preferably 0.2
~5IL.

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

Example 1 An ammonia aqueous solution of casein (casein 11, 2 g, 28% ammonia Ig, water 222 ml) was coated on an aluminum cylinder by dip coating and dried to a coating weight of 1. A subbing layer of Og/m was formed.

Next, 1 part by weight of the charge generating material of structural formula (I), 1 part by weight of butyral resin (Eslec BM-2, manufactured by Sekisui Chemical Co., Ltd.) 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 generation layer. The film thickness was 0.3.

Next, 1 part by weight of the above-mentioned hydrazone compound example (1), 1 part by weight of polysulfone (P1700, manufactured by Union Carbide), and 6 parts by weight of monochlorobenzene were mixed,
The mixture was stirred and dissolved using a stirrer.

This liquid was applied onto the charge generation layer by dip coating and dried to form a charge transport layer.

This film thickness was 13IL.

A corona discharge of 15 KV was applied to the photoreceptor thus prepared.

The surface potential (initial potential VO) at this time was measured.

Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay η).

Sensitivity was evaluated by measuring the amount of exposure (E 1/21ux, 5ec) required to attenuate the potential vr after dark decay to 1/2.

These results were as follows.

V: -600V, Vy: -590V, E 1/2:5, 31ux, seC Example 2
~5 A photoreceptor was prepared in exactly the same manner as in Example 1, except that hydrazone compound examples (2) to (5) were used in place of hydrazone compound example (1) used in Example 1. The characteristics of this photoreceptor were measured.

These results are shown below.

Actual example Vo -V V -V E 1
/2 lux 5ec2 (2) flt
oo 5B5 5.03 (3) 59
0 580 5.54 (4) 810
595 5.25 (5) 810 f
loo 8.0 Comparative Examples 1 to 6 Comparative Examples 1 to 6 were carried out in exactly the same manner except that the following comparative charge transport substances (1) to (8) were used in place of the hydrazone compound used in Example 1. A photoreceptor was created and its charging characteristics were measured.

C Yu ■ Yo charging characteristics 1 (1) 5115 570 7
．． 42 (2) 590 570
B, 93 (3) 800 575
7.14 (4) 815 585 8.
05 (5) 5110 5130
7.76 (6) 585 585
7.5 As is clear from the results of Examples and Comparative Examples, the laminated photoreceptor of the present invention has
It can be seen that a photoreceptor with extremely high sensitivity was obtained. moreover,
Images were printed on the electrophotographic photoreceptors of Examples 1 to 3 using a copying machine (manufactured by Canon Inc., NP-1502) for 2000 minutes.
Repeated 0 times.

As a result, good quality images were obtained even after repeating the test 20,000 times with each photoreceptor, indicating that the photoreceptor of the present invention has extremely excellent durability.

[Effects 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 improving the conventional method. This made it possible to provide a laminated electrophotographic photoreceptor with extremely high sensitivity compared to conventional products.

Claims (2)

[Claims] (1) In a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, the charge generation layer consists of a layer containing a polycyclic quinone pigment of structural formula (I), and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) Hydrazone compounds whose charge transport layer is represented by the general formula (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) (In the formula, R_1 and R_2 are hydrogen atoms , halogen atom,
It represents a nitro group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted amino group, provided that at least one of R_1 and R_2 is a substituted amino group or an alkoxy group, and R_3 and R_4 are substituted or represents an unsubstituted alkyl group or a substituted or unsubstituted aryl group, provided that at least one of R_3 and R_4 is a substituted or unsubstituted aryl group,
Also, R_3 and R_4 may complete a nitrogen-containing heterocycle,
R_5, R_6, R_7 and R_8 are hydrogen atoms, halogen atoms, nitro groups, substituted or unsubstituted alkyl groups,
1. An electrophotographic photoreceptor comprising a layer containing an alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted amino group. (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).