JPS628157A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a laminate type electrophotographic sensitive body high in sensitiv ity and extremely low in residual potential even after a durability test by forming a layer containing a specified quinone type pigment as an electrostatic charge generat ing layer and a layer containing a hydrazone type compound as a charge transfer layer. CONSTITUTION:The charge generating layer contains the polycyclic quinone type pigment represented by structural formula (I) and the charge transfer layer contains the hydrazone type compound represented by general formula (II). The charge generat ing layer can be formed by coating a substrate with said pigment, and when needed, the charge transfer material together with a proper binder. The charge transfer layer is electrically connected with the charge generating layer, and has a function of receiv ing charge carriers injected from the charge generating layer in the presence of an electric field and transferring them to the surface. The hydrazone type compound to be used as the charge transfer material is typified by formulae (1)-(3), and when the charge transfer material is added to the charge generating layer, it is proper to add it in amount of 1-100pts.wt. per 100pts.wt. of the charge generating material from the view points of high sensitivity, low residual potential, and stability against repeated uses. In the formula II, R is substd or unsubstd arylene group.

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, and polyaryl alkanes, phthalocyanine pigments, azo pigments, anine pigments, polycyclic quinone pigments, perylene pigments, and indigo dyes. Organic pigments and dyes such as , thioindigo dyes and square methine 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. Pat. Nos. 4,123,270 and 4,247.
No. 614, No. 4251613, No. 4251614
No. 4256821, No. 4260672, No. 4268596, No. 4278747, No. 42
As disclosed in Japanese Patent No. 93628, electrophotographic photoreceptors are known that use a disazo pigment exhibiting photoconductivity as a charge generation container in a photosensitive layer that is 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 photosensitive wavelength range through selection.

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] The purpose of the present invention is to improve the above-mentioned drawbacks and to provide a product with high sensitivity and extremely low residual potential even after durability tests! An object of the present invention is to provide an fjI type electrophotographic photoreceptor.

[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 pigment in the charge generation layer and a specific hydrazone compound in the charge transport 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 arranged on a conductive support, in which the charge generation layer is a layer containing a polycyclic quinone pigment of structural formula (I). The charge transport layer consists of a hydrazone compound represented by the general formula (n) (wherein R1 and R are a substituted or unsubstituted alkyl group, a substituted or unsubstituted 7-aryl group, or a 5-membered ring together with a nitrogen atom). or indicates the atomic group necessary to complete a 6-membered ring, and together with R3 and R4 substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups, or nitrogen atoms complete the 5- or 6-membered ring. R5 and Rt are hydrogen atoms, halogen atoms,
Represents 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 amino group, and R is a substituted or unsubstituted arylene group. The electrophotographic photoreceptor is composed of a layer containing the following:

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. In addition, it is desirable that the thin film layer 1 has a thickness of, for example, 10 μl or less, preferably 0.01 to 1 p. This means that most of the incident light is absorbed by the charge generation layer and a large amount of This is due to the need to generate charge carriers and to inject the generated charge carriers into the charge transport layer without being deactivated by recombination or trapping.

The charge generating material included in the present invention is a polycyclic bovine non-based 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 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 butyral, and polyvinylpyrene. Preferably polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, acrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin , epoxy resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, and other insulating resins. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less. Solvents that dissolve these resins vary depending on the type of resin, and are preferably selected from those that do not dissolve the charge transport layer or undercoat layer described below.Specific organic solvents include methanol, ethanol, and inorganic solvents. Alcohols such as propatool, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, N,N-dimethylformamide,
Amides such as N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, dichloroethylene,
Aliphatic halogenated hydrocarbons such as tetranomized carbon and trichloroethylene, aromatics such as mabenzel, toluene, xylene, ligroin, monochlorobenzene, and dichlorobenzene 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 coach ink method, a roller coating 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 is performed at a temperature of 30 to 200°C for 5 minutes to 2 minutes.
It can be carried out stationary or under a draft for a time range of 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, the charge transport layer 4 may be laminated on the charge generation layer, or may be laminated under it, and may be a material that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport layer). Preferably, the material (hereinafter referred to as "substance") is substantially insensitive to the wavelength range of electromagnetic waves to which the above-mentioned 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 matches or overlaps that of the charge generation layer, charge carriers generated in both trap each other.

As a result, this causes 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, R1 and R represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted 7-aryl group, or an atomic group necessary to complete a 5-membered ring or a 6-membered ring together with a nitrogen atom, and R3 and R4 Indicates the atomic group necessary to complete a 5-membered ring or 6-membered ring together with a substituted or unsubstituted alkyl group, an okimon or unsubstituted 7-aryl group, or a nitrogen atom, and RS- and Rt are hydrogen atoms, It represents 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 7-mino group, and R is a substituted or unsubstituted 7-mino group. Indicates a substituted arylene group.

This hydrazone compound satisfies the above-mentioned conditions as a charge transport material, especially sensitivity.

It has excellent properties in terms of durability.

Typical hydrazone compounds used in the present invention are illustrated 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 a charge transporting material is added to the charge generation layer, the hydrazone compound is 10 times or less (weight ratio) of the charge generation material, preferably 0.01
~1 times (weight ratio) is suitable from the viewpoint of high sensitivity, low residual potential, and repetition stability. To form a charge transport layer containing a hydrazone compound, a film can be formed by selecting an appropriate binder. Examples of resins that can be used as binders include acrylic resins, polyarylates,
Insulating resins such as polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, boriado, chlorinated rubber, or poly-N-vinylcarbazole, polyvinyl Mention may be made of organic photoconductive polymers such as anthracene and polyvinylpyrene.

Since the charge transport layer has a limit in which it can transport charge, it cannot be made thicker than necessary. Generally, the thickness is 5 to 30 IL, but the preferable range is 8 to 20 IL.
It is. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photosensitive layer having a tiIM structure including such 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,
Plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluorinated ethylene, etc.) having a layer formed by vacuum evaporation of indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. Use a substrate made of conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic with a suitable binder, a substrate made of plastic or paper impregnated with conductive particles, a plastic with conductive particles, etc. Can be done.

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 6, nylon 66, nylon 610° copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, It can be formed from aluminum oxide or the like. The thickness of the undercoat layer is suitably 0.1 to 40 ml, preferably 0.1 to 3 colors.

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 base 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, the surface of the charge transport layer must be negatively charged.

After charging, when exposed to light, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, causing a decrease in surface potential and creating a gap between the exposed area and the unexposed area. Electrostatic contrast occurs. 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 free from stains due to deterioration due to ultraviolet rays, ozone, 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 one layer, the surface resistivity must be 1.
The F11 resistance used in the present invention is preferably polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, It can be formed by applying a solution prepared by dissolving a resin such as styrene-acrylonitrile copolymer in a suitable organic solvent onto the photosensitive layer and drying it. Moreover, additives such as ultraviolet absorbers can be added to the resin liquid. On this occasion,
The thickness of the protective layer generally ranges from 0.05 to 20 l, preferably from 0.2 to 5 l.

The present invention will be explained below according to examples.

Example 1 Casein ammonium was placed on an aluminum worm ring.
□Nia aqueous solution (casein 11.2g, 28% ammonia Ig, water 222ml) was applied by dip coating method,
It was dried to form a subbing layer with a coating weight of 1.0 g/w.

Next, 1 part by weight of the charge generating material of structural formula (I), 1 part by weight of butyral resin (manufactured by S-LEC BM-2.fi Suikagaku ■) 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 0.3p.

Next, compound 11i 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 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.

This film thickness was 12JL.

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 V,).

Sensitivity was evaluated by measuring the exposure amount (E 1/21ux, 5ec) required to attenuate the potential η to 172 after dark decay.

These results were as follows.

V6: -580V, V: -570V.

E l/2:3, Olux, see Examples 2 to 5 The following examples were carried out 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 in exactly the same manner as in Example 1, and the characteristics of this photoreceptor were measured.

These results are shown below.

'! JjJJ m Vo -V V? -V E
1/2 lux 5ec2 (2) 59
0 580 3.23 (3) 580
570 2.94 (4) 570
580 3.15 (bow) ss'557
5 3.8 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 (6) were used in place of the hydrazone compound used in Example 1. A photoreceptor was created and its charging characteristics were measured.

C YuH Riki Charging Characteristics (1) 5110 585 4.3 (2)
580 5θo4.6(3) 5
85 550 5.0 (4) 810 8
00 8.2 (5) 585 555
5.7(6) 815 805 4.4 The laminated photoreceptor of the present invention has the following characteristics compared to the photoreceptors of Comparative Examples 1 to 6:
It can be seen that a photoreceptor with extremely high sensitivity was obtained. Furthermore, the photoreceptors of Examples 1 to 5 were used in a copying machine (manufactured by Canon Corporation, N
Image generation was repeated 20,000 times using P-1502). 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
By using a specific hydrazone compound in the cargo transport layer, it has become possible to provide a laminated electrophotographic photoreceptor with extremely high sensitivity compared to conventional ones.

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 substituted or R_3 and R_4 represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or an atomic group necessary to complete a 5- or 6-membered ring together with a nitrogen atom. Indicates the atomic group necessary to complete a 5-membered ring or 6-membered ring together with a substituted aryl group or nitrogen atom, R_5 and R_6 are hydrogen atoms, halogen atoms, nitro groups, substituted or unsubstituted alkyl groups,
represents an alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted amino group, and R represents a substituted or unsubstituted arylene group. Characteristic electrophotographic photoreceptor. (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).