JPS61174555A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body high in sensitivity and kept in extremely low in residual potential even in long period repeated uses by incorporating a specified polycyclic quinone type pigment in an electrostatic charge generating layer and a specified hydrazone type compd. in a charge transfer layer. CONSTITUTION:The charge generating layer is formed by coating a conductive substrate with a coating soln. prepared by dispersing one of the polycyclic quinone type pigments represented by formula I into the org. solvent soln. of a binder resin, and drying it, or by vapor depositing this pigment in a vacuum system. The electrophotographic sensitive body high in sensitivity and superior in durability can be obtained by coating the charge generating layer with the coating soln. contg. the hydrazone compd. together with the binder resin dissolved in an org. solvent, and drying it to form the charge transfer layer on the charge generating layer. The charge transfer layer may be further coated with a protective layer. The charge generating layer can be further more enhanced in sensitivity by adding said hydrazone type compd. to it as well. This hydrazone type charge transfer material is represented by formula II in which each of R1-R4 is H or halogen, R5 is H, alkyl, or alkoxy, and each of R6, R7 is a residue capable of forming a 5- or 6-membered ring together with an optionally substd. alkyl, aralkyl, phenyl, or N atom.

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 I-rimers such as poly-IJ-N-vinylcarbazole and privinylanthracene, low-molecular organic photoconductors such as carbazole, anthracene, pyrazolines, osadiazoles, hydrazones, and polyarylalkanes. Organic pigments and dyes such as phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and squaric acid 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. 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., in a photosensitive layer functionally separated into a charge generation layer and a charge transport layer. Electrophotographic photoreceptors using disazo pigments that exhibit 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.

The laminated photoreceptor, which is obtained by laminating a charge transport layer and a charge generation layer mainly composed of a charge generation material, is different from other single layer photoreceptors due to its sensitivity and increased residual potential after durability tests. Although it was advantageous, 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 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 consists of a layer containing a polycyclic chino/type pigment represented by formula (I). The charge transport layer has the general formula Q[) (wherein R,, R2, R, and R4 represent a hydrogen atom or a halodane atom, R5 represents a hydrogen atom, an alkyl group, or an alkoxy group, and R6 and R7 represents an alkyl group, an aralkyl group, a phenyl group, which may have a substituent, or a residue that forms a 5- to 6-membered ring together with an atom. It is an electrophotographic 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 efficiently injects generated charge carriers into the charge transport layer. Therefore, 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 a large number of charge carriers and to inject the generated charge carriers into the charge transport layer without recombining, trapping, or deactivating them.

The charge generating material used in the present invention is a polycyclic quinone pigment represented by formula (1).

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, and forming a vapor-deposited film using a vacuum vapor deposition apparatus. You can get it by doing

The binder 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 I-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. . Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol and heptalic acid, etc.), polycarcanate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin,
Polyamide, I-lipinylpyridine, cellulose resin,
Examples include insulating resins such as urethane/resin, polyurethane resin, casein, polyvinyl alcohol, and f-rivinylpyrrolidone. The resin contained in the charge generation layer is 80
A weight below 40 weight is suitable.

The solvent that dissolves these resins varies depending on the type of resin, and it is preferable to select a solvent that does not dissolve the underlying charge generation layer or undercoat layer. Specific organic solvents include alcohols such as methanol, ethanol, isoglono 4-nol, acetone, methyl ethyl keto/1. Ketones such as cyclohexa and non, N,N-dimethylformamide, N.

Amino-Ps such as N-dimethylacetamide, sulfoxides such as dimethylsulfoxide, tetrahydrofuran,
Ethers such as dioxane, ethylene, glycol methyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halodanized hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichlorethylene, or benzene , toluene, xylene,
Aromatics such as refloin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating method, spray coating method, spinner coating method, peed coach ink method,
This can be carried out using a coating method such as a Mayer-Per coating method, a Fleid coating 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 can be carried out at 30° C. to 200° C. for a period of 5 minutes to 2 hours, either stationary or with air blowing.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and receiving 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. However, since the charge transport layer is laminated on the charge generation layer, there is less deterioration of the surface of the photoreceptor during repeated durability tests, and further, by selecting the binder in the charge transport layer, This is desirable in that a good photoreceptor surface can be formed.

The material for transporting charge carriers in the charge transport layer (hereinafter simply referred to as charge transport material) is preferably insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The term "electromagnetic waves" used herein includes the broad definition of "light rays" including 7-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 capture 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 ([).

(In the formula, R1+ "2," S and R4 represent a hydrogen atom or a halodane atom, R5 represents a hydrogen atom, an alkyl group, or an alkoxy group, and R6 and R7 represent an alkyl group that may have a substituent, an aralkyl group, (Represents a residue that forms a 5- to 6-membered ring with a phenyl group, a phenyl group, or an N atom.) This hydrazone compound satisfies the above-mentioned conditions as a charge transport material, especially in terms of sensitivity and durability. It has excellent properties.

Representative compounds of the hydrazicine compound represented by the general formula (n) used in the present invention are illustrated in Table IK.

Table 1 (1) 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 (weight ratio), preferably 0.01 to 1 times (weight ratio) of the charge generation material, to achieve high sensitivity, low residual potential, and repeatability. This is appropriate from the viewpoint of return stability.

To form a charge transport layer containing a hydrazone compound, a film can be formed by selecting an appropriate material. Resins that can be used as binders include, for example, acrylic resins, polyacrylates, polyesters, polycargenates, and polystyrenes.

Acrylonitrile-styrene copolymer, acrylonitrile-butadiene corimer, polyvinyl butyral,
Examples include insulating resins such as polyvinyl formal, polysulfone, polyacrylamide, polyamide, and chlorinated rubber, 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. Typically it is 5 microns to 30 microns, with a preferred range of 8 microns to 20 microns. 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 and platinum can be used, as well as aluminum, aluminum alloys,
A base made of a plastic coated with a layer of indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. by vacuum evaporation (e.g., Chikdenblack, silver particles, etc.) together with a suitable binder, A substrate made of plastic or paper impregnated with conductive particles, a plastic containing 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, nitrocellulose, ethylene-
Acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610° copolymerized nylon, alkoxymethylated nylon, etc.).

Can be formed from polyurethane, gelatin, and aluminum oxide.

The thickness of the undercoat layer is 0.1 micron to 40 micron.

Preferably, 0.1 micron to 3 micron 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 an electron transport material, it is necessary to positively charge the surface of the charge transport layer. 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, causing the surface potential to attenuate and creating static between the unexposed area and the exposed area. Electrocontrast occurs. A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. Should I fix this directly?

Alternatively, the toner particles 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, then developed 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, it is necessary to charge the surface of the charge transport layer negatively. 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 that, it reaches the surface and neutralizes the negative charges, resulting in attenuation of the surface potential and an electrostatic contrast between it and the unexposed area.

When printing, 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 subject to deterioration due to ultraviolet rays, ozone, etc., dirt due to oil, etc., scratches due to metal chips, etc., and damage to the photoreceptor due to photoreceptor contact members such as printing 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 scratching. K is 1 to form an electrostatic latent image on this protective layer.
It is desirable that the surface resistivity is 10 Ω or more.

The protective layer used in the present invention includes polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, I-limide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer, etc. The photosensitive layer can be formed by dissolving a resin in an appropriate organic solvent and coating the photosensitive layer with a solution 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 On the aluminum cylinder was an ammonia aqueous solution of casein (casein 11.21!, 28% 7 ammonia water II,
Apply 222d) of water using a coating method, dry and coat amount 1. A subbing layer of OI/m'' was formed.

Next, 1 part by weight of the charge generating material represented by Formula 1 (I), 1 part by weight of butyral resin (S-LEC BM-2, manufactured by Sekisui Chemical Co., Ltd.) and 30 parts by weight of Improvil alcohol were dispersed for 4 hours using a Solmill 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 0.3μ. Next, P-diethylaminobenzaldehyde, which is the compound (1) in Table 1,
1 part by weight of N-7 enyl-α-naphthylhydrazone, polysulfone resin (P1700: manufactured by Union Carbide)
1 part by weight 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 was 12μ.

Corona discharge of -5 kV was applied to the photoreceptor thus prepared. The surface potential at this time was measured (initial potential V0).

Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay v5). The sensitivity is determined by the exposure amount (E%l) required to attenuate the potential v5 after dark decay by 1/2 K.
The evaluation was made by measuring ux −5ee ).

These results were as follows.

■. : -615 volts V5 knee 600 delt E3A: 40 Lux-Crown Examples 2-10 In place of the compound from Compound Shop (1) used in Example 1.

A photoreceptor was prepared in exactly the same manner as in Example 1, except that the compounds shown in Table 1 were used, and the characteristics of this photoreceptor were measured. These results are shown in Table 2.

Table 2 Example Compound shop vo(-v)v5(-v) E
3ALux 0 Formula % Formula % Comparative Examples 1 to 6 Photoreceptors were prepared in exactly the same manner except that the charge transport materials shown in Table 3 were used in place of the hydrazone compound used in Example 1. The charging characteristics are shown in Table 4.

Table 3 Comparative example Comparative charge Comparative charge transporting material structural formula ■ Comparative charge Comparative charge transporting material structural formula 4 1 1 600575 6.2 2 2 590 565 6.0 3 3 595 570 6.8 4 4 610 580 7. 4 5 5 585 555 7.1 6 6 580 555 6.6 As is clear from the results of Examples and Comparative Examples, the laminated photoreceptor of the present invention has an extremely high It can be seen that a photoreceptor with high sensitivity was obtained. Further, images were produced 20,000 times using the photoconductors of Examples 1 to 3 using a copying machine (NP-150z, manufactured by Canon Inc.). 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 quinone pigment as a charge generation material in the charge generation layer and a hydrazone compound of 49% 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 is expressed by the formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) The charge transport layer is composed of a layer containing a polycyclic quinone pigment, and the charge transport layer has the general formula (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) (In the formula, R_1, R_2, R_3 and R_4 are hydrogen atoms or halogens. R_5 represents a hydrogen atom, an alkyl group, or an alkoxy group, and R_6 and R_7 represent an alkyl group, an aralkyl group, a phenyl group that may have a substituent, or a residue that forms a 5- to 6-membered ring together with the N atom. An electrophotographic photoreceptor comprising a layer containing a hydrazone compound represented by the following. (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).