JPS6225765A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the titled body having a high sensitivity and a less residual potential by incorporating a specific polycyclic quinone pigment to an electric charge generating layer, and a specific hydrazone compd. to an electric charge transfer layer respectively, and then, by laminating the prescribed layers with each other to form the titled body. CONSTITUTION:The electric charge generating layer contains the polycyclic quinone pigment shown by formula I. The electric charge transfer layer contains the hydrazone compd. shown by formula II. In formula II, R1-R4 are each an alkyl or an aryl group, R1 and R2 or R3 and R4 together with a nitrogen atom may be formed each 5 or 6 membered cyclic ring. R5 and R6 are each a hydrogen or a halogen atom, a nitro, an alkyl, an alkoxy, an aryloxy, an acyl or an amino group. Thus, the electric charge generating layer and the electric charge transfer layer contg. the prescribed compds. respectively are laminated on an aluminum substrate to form the photosensitive body, thereby improving the sensitivity of the photosensitive body.

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.

(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. , carbazole,
Low-molecular organic photoconductors such as anthracene, pyratulins, oxadiazoles, hydrazones, polyaryl alkanes, -ytalonanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, Organic pigments and dyes such as 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
No. 47614, No. 4251613, No. 42516
No. 14, No. 4256821, No. 4260672, No. 4268596, No. 4278747, No. 4293628, etc., the photosensitive layer is mechanically separated into a charge generation layer and a charge transport layer. Electrophotographic photoreceptors using disazo pigments exhibiting photoconductivity as charge-generating substances 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 y1 layer type 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 multilayer 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 composed of a layer containing a polycyclic non-based pigment represented by formula (I). and the charge transport layer is represented by the general formula (II) (wherein R1 and R2 represent a hydrogen atom, /\rogen atom, a nitro group, an a-substituted or unsubstituted aryloxy group, or a substituted or unsubstituted amine group) , provided that at least one of R1 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 7-aryl group, provided that at least one of R3 and R4 One is a substituted or unsubstituted 7-aryl group. R3 and R4 may form a nitrogen-containing heterocycle, and R5, R6, R+ and R8 are hydrogen atoms, halogen atoms, nitro groups, substituted or An unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted 7-aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted amino group). This is an electrophotographic photoreceptor characterized by 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 to use a thin film layer, for example, a thin film layer having a thickness of 10 microns or less, preferably 0.01 micron to 1 micron. This means that most of the incident light is absorbed by the charge generation layer, 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 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 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, polyvinylanthracene, and polydonylpyrene. 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 of resins contained in the mML charge generation layer include insulating resins such as urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone.
0% by weight or less, preferably 40% by 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
- Amides such as dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, chloroform, methylene chloride, Dichloroethylene, carbon tetrachloride.

Aliphatic halogenated hydrocarbons such as trichloroethylene, 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 coach ink method, a roller coach ink 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" includes a broad definition of "light rays" that includes gamma rays, X-rays, far-infrared rays, and the like. 71! 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 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

Ha1 R4 (wherein R1 and R2 are a hydrogen atom, a halogen atom,
Represents a nitro group, a substituted or non-converted 7-aryloxy group, or a substituted or non-converted 7-mino group, provided that R1 and R
At least one of 2 is a substituted amine group or an alkoxy group. R3 and Rat-1 represent 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. Further, R3 and R4 may form a nitrogen-containing heterocycle, R11, R6, R1 and R
8 is a hydrogen atom, a halogen atom, a nitro group, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted 7-aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted 7-mino group. This hydrazone compound satisfies the above-mentioned conditions as a charge transport material, and has particularly excellent properties in terms of sensitivity and durability.

Table 1 shows typical hydrazone compounds represented by the general formula (II) used in the present invention.

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 adding a charge transport material to the charge generation layer, the hydrazone compound should be 10 times or less (ffi amount ratio), preferably 0.01 to 1 times (weight ratio), 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. Examples of resins that can be used as binders include acrylic resin and polyacrylate.

Insulating resins such as polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N-vinylcarbazole, polyvinylanthracene, Mention may be made of organic photoconductive polymers such as 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. As the substrate having the conductive layer, materials that are conductive themselves such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum can be used. In addition, plastics (e.g., carbon black, silver particles, etc.) having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc., are used together with a suitable binder. A substrate coated on top, 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 is casein,
Polyvinyl alcohol, cellulose, ethylene-
It can be formed from acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 61O1 copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, and the like.

The thickness of the undercoat layer is suitably 0.1 micron to 40 micron, preferably 0.1 micron to 3 micron.

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 charging, electrons 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 positive charge, causing a decrease in surface potential and static electricity between the exposed area and the unexposed area. Electrocontrast occurs. 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, oran, 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 or the charge transport layer for the purpose of preventing scratches and abrasion.In order to form an electrostatic latent image on this protective layer, the surface resistivity must be IQIIΩ or higher. It is desirable that there be.

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 (11.2 g of casein, 1 g of 28% ammonia water, 222 m5 L of water) was coated on an aluminum cylinder by a coating method, dried, and coated i1. A subbing layer of Og/rn' was formed.

Next, 1 gl part of a charge generating material represented by formula (I),
Butyral resin (S-LEC BM-2: [manufactured by Suikagaku ■)]
Parts of lji 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-.
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 1
It was 2μ.

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 it was left in a dark place for 5 seconds (dark decay V5). Quantity (E
The evaluation was made by measuring 1/7 sentence ux@5ec).

These results were as follows.

Vo: -590 volts V5: -580 volts El12: 5.8 JILux*sec Example 2
~5 A photoreceptor was prepared in exactly the same manner as in Example 1, except that the compounds shown in Table 1 were used in place of the compound M (1) used in Example 1, and the photoreceptor was prepared in the same manner as in Example 1. Characteristics were measured. These results are shown in Table 2.

Table 2 Example Compound No Vo(-V) V5(-V)
El/21ux*5ec 2 2 5805655.7 3 3 5855706.3 4 4 5905806.0 5 5 6106006.6 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 material questionnaire 4 Comparative example Comparative charge Vo (-V) Vs (-V) E
l/2 transport substance collapse U!・5ec1
1 5755507.6 2 2 5705407.2 3 3 5805558.0 4 4 585560 B, 3 5 5 5805507.4 6 6 5755457.7 As is clear from the results of Examples and Comparative Examples, the laminated photoreceptor of the present invention It can be seen that a photoreceptor with extremely high sensitivity was obtained compared to Comparative Examples 1 to 6. Furthermore, using the photoconductors of Examples 1 to 3 using a copying machine (MP-150Z: manufactured by Canon Inc.), image formation was repeated 20,000 times. As a result, good quality images were obtained for all photoreceptors even after repeating 20,000 times. 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 non-based 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. This makes it possible to provide a laminated electrophotographic photoreceptor with high

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 nitro group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted amino group. However, R_
At least one of 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
One is a substituted or unsubstituted aryl group. Also R_
3 and R_4 may form a nitrogen-containing heterocycle. R_5,
R_6, R_7 and R_8 are 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 amino Indicates the group. ) 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).