JPS61294449A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To increase the sensitivity by forming a charge generating layer contg. a specified polycyclic quinone pigment and a charge transferring layer contg. a specified hydrazone compound. CONSTITUTION:When a charge generating layer and a charge transferring layer are formed on an electrically conductive support to obtain a laminate type electrophotographic sensitive body, the charge generating layer is made of a layer contg. a polycyclic quinone pigment represented by formula I and the charge transferring layer is made of a layer contg. a hydrazone compound represented by formula II. The charge generating layer contains the charge generating material to the utmost limit and has a small thickness of <=10mum, preferably 0.01-1mum. The charge transferring layer is electrically connected to the charge generating layer and has functions to receive charge carriers implanted from the charge generating layer in the presence of an electric field and to transfer the charge carriers to the surface. Thus, a sensitive body having very high sensitivity can be obtd.

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, cadmium sulfide, 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. Low-molecular organic photoconductors such as carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine pigments, polycyclic bovine pigments, perylene pigments, indigo dyes Organic pigments and dyes such as , thioindigo dyes and methine squarate 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, US Pat. Nos. 4,123,270 and 42,476.
No. 14, No. 42516, No. 3, No. 4251614, No. 4256821, No. 4260672, No. 4268596, No. 4278747, No. 429
As disclosed in Japanese Patent Application No. 3628, etc., electrophotographic photoreceptors are known in which a disazo pigment exhibiting photoconductivity is used as a charge generation substance in a photosensitive layer functionally separated into a charge generation layer and a charge transport layer. 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 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.

[Problems to be Solved by the Invention] An object of the present invention is to improve the above-mentioned drawbacks and to provide a laminated electrophotographic photoreceptor with high sensitivity and extremely low residual potential even after a durability test.

[Means for Solving the Problems 1 Effect] The present invention achieves the above-mentioned object 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 non-containing pigment in the charge generation layer and a specific hydrazone compound in the charge transporting 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 (1), The charge transport layer is a hydrazone compound represented by the general formula (n) (wherein R1 and R2 are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted 7-aryloxy group, or Indicates a substituted amino group, provided that at least one of R7 and R is a substituted amino group.
or an alkoxy group, and R1 and ~ represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted 7-aryl group, provided that at least one of R1 and ~ is a substituted or unsubstituted 7-aryl group. , and R1 and R4
The nitrogen-containing heterocycle may be completed with Rs, R,, R? BiR? 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, and n represents O or 1). It consists of an electrophotographic photoreceptor characterized by:

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. , a thin film layer, e.g. 1 OjL
Below, preferably 0°01-1. It is desirable to have a thin film layer with a film thickness of This is due to the need to inject into the charge transport layer without being deactivated by traps.

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 pigment and, if necessary, a charge transporting 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 device. can be obtained by The binder that can be used in 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, polyvinyl 7-thracene, and polyvinylpyrene. Preferably polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.)
, polycarbonate, polyester, phenoxy resin,
Examples include insulating resins such as polyvinyl acetate, acryl resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is 8
A content of 0% by weight or less, preferably 40% by weight or less is suitable. Solvents that dissolve these resins vary depending on the type of resin, and are preferably selected from those that do not dissolve the underlying charge transport layer or subbing layer.Specific organic solvents include methanol, ethanol, and in-propyl alcohol. Alcohols such as tools, ketones such as 7setone, methyl ethyl ketone, cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, tetrahydrofuran, dioxane, ethylene glycol monomethyl ether ethers such as methyl acetate, ethyl acetate, etc., aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, or benzene, toluene, xylene, ligroin, monochlorobenzene , aromatics such as 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 coating method, or a curtain coating method.

Drying is preferably carried out by drying to the touch at room temperature and then heating. Drying by heating is performed at a temperature of 30 to 200°C for 5 minutes to
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, and may be a substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as a charge transport material). 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 substance used in the present invention is a hydrazone compound represented by the general formula (n), where R1 and R are hydrogen atoms, halogen atoms, substituted or unsubstituted alkyl groups, alkoxy groups, substituted or unsubstituted 7-aryloxy group or substituted amine group, provided that at least one of R1 and R1 is a substituted amine group or alkoxy group, and R3 and R4a gl substituted or unsubstituted alkyl group or substituted or unsubstituted 7-aryloxy group or substituted amine group; Represents a lyl group, provided that at least one of the R groups is a substituted or unsubstituted 7-aryl group, and R3 and R÷ may complete a nitrogen-containing heterocycle, R,, R,, R2 and R9 are hydrogen atoms, halogen atoms, substituted or unsubstituted alkyl groups, alkoxy groups, substituted or unsubstituted 7-aryloxy groups,
or substituted #7 represents a mino group, and n represents O or l.

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

Typical hydrazone compounds used in the present invention are illustrated below.

CD'0 Furthermore, 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 to 1 times (weight ratio) is appropriate 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. and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary; generally, the thickness is 5 to 30. However, the preferred range is 8 to 20. 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. As the substrate having a conductive layer, it is possible to use materials whose substrate itself is conductive, such as aluminum, aluminum alloy, copper, summer lead, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. I can do it,
In addition, plastics (for example, polyethylene) have a layer formed by vacuum deposition of aluminum, aluminum alloy indium oxide, tin oxide, indium oxide-tin oxide alloy, etc.

polypropylene, polyvinyl chloride, polyethylene, lenterephthalate, acrylic resin, polyethylene fluoride, etc.),
A substrate in which conductive particles (e.g., carbon black, silver particles, etc.) are 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. can be used. .

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The undercoat layer is casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 8. + iron 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, It can be formed from gelatin, aluminum oxide, etc. The thickness of the undercoat layer is 0.1 to 40J.
L, preferably 0.1 to 3, is suitable.

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. , after which it reaches the surface and neutralizes the negative charges, resulting in attenuation of one surface type, creating 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 10 is required.
The protective layer used in the present invention is preferably made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon,
It can be formed by dissolving a resin such as polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer, etc. in a suitable organic solvent 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 μl, preferably 0.2
~5IL.

The present invention will be explained below according to examples.

Example 1 An ammonia aqueous solution of casein (11.2 g of casein, 28% Ig of ammonia, 2 g of water) was placed on an aluminum cylinder.
22 ml) was applied by a dip coating method and dried to form a subbing layer with a coating amount of 1 and 0 gem.

Next, 1 part by weight of a charge generating material of structural formula (I).

Butyral resin (Eslec BM-2, manufactured by Sekisui Chemical Co., Ltd.)
1 part by weight and 3011 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 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 12 mm.

A corona discharge of 15 KV was applied to the photoreceptor thus prepared. The surface potential (initial potential Va) 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 Vy).

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

These results were as follows.

V, knee 585V, η: -575V, E l/2:4
, 6 lux, sec Examples 2 to 5 Completely the same as Example 1 except that hydrazone compound examples (2) to (5) were used in place of hydrazone compound example (1) used in Example 1. A photoreceptor was prepared using the method described above, and the characteristics of this photoreceptor were measured.

These results are shown below.

IJLll Audit lV -V V -V E
1/21u! 5ec2 (2) 580
570 4.43 (3) 590 58
0 5.24 (4) 585 575
5.0 Comparative Examples 1 to 6 The photosensitive materials of Comparative Examples 1 to 6 were prepared in exactly the same manner except that the following comparative charge transport substances (1) to (6) were used in place of the hydrazone compound used in Example 1. They created a body and measured its charging characteristics.

CλHr Charging characteristics 1 (1) 5! a5 575 B
, 02 (2) 585 580 5
．． 93 (3) 5i90 585
8.84 (4) 805 585
7.85 (5) 800 580
8.46 (6) 815 800
7.0 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,
Image formation on the photoreceptors of Examples 1 to 5 was repeated 20,000 times using a copying machine 4m (manufactured by Canon Inc., NP-150Z).

As a result, good quality images were obtained even after repeating 20,000 times with each photoreceptor.1 The electrophotographic photoreceptor of the present invention
It can be seen that the durability is also extremely excellent.

[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,
Represents a substituted or unsubstituted alkyl group, alkoxy group, substituted or unsubstituted aryloxy group, or substituted amino group, provided that at least one of R_1 and R_2 is a substituted amino group or alkoxy group, and R_3 and R_
4 represents a substituted or 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, and R_3 and R_4 represent a nitrogen-containing heterocycle. It may be completed, R_5, R_6, R_7 and R_8 are hydrogen atoms,
a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted amino group, and n represents 0 or 1. Photographic photoreceptor. (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).