JPS61182047A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a laminate type electrophotographic sensitive body high in sensitivity and extremely low in residual potential after durability test by using a specified polycyclic quinone type pigment for an electrostatic charge generating layer and a specified hydrazone deriv. for a charge transfer layer. CONSTITUTION:The charge generating layer contains a polycyclic quinone type pigment represented by formula (I), and the charge transfer layer contains a hydrazone deriv. represented by formula (II) in which R1-R4 are each H or halogen; R5 is H, alkyl, or alkoxy; and R6 and R7 are each optionally substd. alkyl, aralkyl, phenyl, or a residue for forming a 5- or 6-membered ring together with an N atom. The charge generating layer is formed into a thin layer, preferably, in a thickness of <=10mum, especially, 0.01-1mum, and when the charge transfer material is added to the charge generating layer, it is preferred to add the hydrazone compd. in a charge transfer material to charge generating material ratio of (<=10):1, especially, (0.01-1):1 by weight, from the view points of ensuring high sensitivity, low residual potential, and high stability against repeated uses.

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, a number of organic photoconductors have been developed. carbazole,
Low-molecular organic photoconductors such as anthracene, pyrazolines, oxadiazoles, hydrazones, polyarylalkanes, 7-thalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, 4-rylene pigments, indigo dyes, Organic pigments and dyes such as thioindigo dyes and methine squaric acid dyes are known. In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded.
Many photoconductive organic pigments and dyes have been proposed.

For example, US Pat. No. 4,123,270, US Pat. No. 42,476
No. 14, No. 4251613, No. 4251614, No. 4256821, No. 4260672, No. 4268596, No. 4278747, No. 429
As disclosed in Japanese Patent No. 3628, electrophotographic photoreceptors are known that use a disazo pigment exhibiting photoconductivity as a charge generation substance 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 pine paste, making it possible to provide photoreceptors with extremely high productivity and low cost. It has the advantage that the sensitive wavelength range can be freely controlled by selection.

A multilayer photoreceptor obtained by laminating a charge transport layer and a charge generation layer mainly composed of a charge generation material has higher sensitivity and increased residual potential after durability tests than other single layer photoreceptors. Although it was advantageous, it was still not at a sufficient level.

[Problem that the invention seeks to solve]

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-mentioned object by providing 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 comprised of a layer containing a polycyclic quinone pigment represented by formula (1). , the charge transport layer has the general formula 01) (wherein, R1e R2+ Rs 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 have a substituent. Alkyl group, aralkyl group, phenyl group or N
This is an electrophotographic photoreceptor characterized by comprising a layer containing a hydrazone compound represented by ), which represents a residue that forms 1c5- to 6-membered II with atoms.

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 to generate many charge carriers, and the generated charge carriers must be injected into the charge transport layer without being deactivated due to recombination or trapping. This is due to the fact that

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, 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 generation layer by coating can be selected from a wide range of insulating resins, including poly-N-vinylcarbazole, polyvinylanthracene, etc. It can be selected from organic photoconductive polymers such as ribinyl biry. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and heptalic acid, etc.), polycargonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin,
polyamide, polyvinylpyridine, cellulose resin,
Urethane resin, epoxy resin 1. Examples include insulating resins such as casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is 8
Less than 0 weight, preferably less than 40 weight, are 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 alcohols such as methanol, ethanol, and ingrod-nol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide, N,N-tumethylacetamide, and dimethyl 2 Sulfoxides such as sulfoxide, tetrahydro7
Ethers such as orchid, ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halodanized hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichlorethylene, etc. Aromatic compounds such as be/zene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating method, spray coating method, spinner coating method, bead coating method,
Coating methods such as Mayer coating method, blade coating method, roller coating method, and curtain coating method can be used. 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 top of the charge generation layer, or may be laminated below it. 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 furthermore, by selecting a binder in the charge transport layer, a better This is desirable in that it can form the surface of a photoreceptor.

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 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 material used in the present invention is a hydrazone compound represented by the general formula (〇).

8゜(In the formula, R1e R2e R5 and R4 represent a hydrogen atom or a halogen atom, R5 represents a hydrogen atom, an alkyl group, or an alkoxy group, and R6 and R7 represent an alkyl group or an aralkyl group that may have a substituent. , a phenyl group or a residual group that forms a 5- to 6-membered ring with an N atom.) This hydrazone compound satisfies the above conditions as a charge transport material, and has excellent sensitivity and durability. It has properties.

Table 1 shows typical hydrazicine compounds represented by the general formula (II) used in the present invention.゛Table 11 Table 1b Furthermore, in the present invention, the above-mentioned human dicine 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 human 2 sine compound, a film can be formed by selecting an appropriate binder. Resins that can be used as binders include, for example, acrylic resins, polyacrylates, polyesters, polycargenates, polystyrenes, acrylonitrile-styrene copolymers, acrylonitrile-butadiene copolymers,
Examples include insulating resins such as polyvinyl butyral, 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. As the substrate having a conductive layer, materials that are themselves conductive can be used, such as aluminum, aluminum alloy, steel, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum. In addition, plastics having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. (for example, Riki-Den Black, silver particles, etc.) are used in an appropriate manner. In addition to Ingu, a substrate coated on plastic, 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-
It can be formed from acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 6101 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 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 to neutralize the positive charge, causing a decrease in surface potential and creating static electricity between the exposed area and the unexposed area. Contrast 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, then developed and fixed. The ingredients for the developer, the developing method, and the fixing method may be any known method or method, and are not limited to any particular method.

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, ozone, etc., dirt due to oil, etc., scratches due to metal chips, etc., and exposure 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 of the body. In order to form an electrostatic latent image on this protective layer, it is desirable that the surface resistivity is 100 or more.

The protective layer used in the present invention includes I-lipinyl petyl 2-yl, preester, polycarbanate, acrylic resin, methacrylic resin, nylon, I-liimide, prearylate, I-riurethane, styrene-butadiene cotelimer, styrene-acrylic fit near $ It can be formed by applying a solution prepared by dissolving a resin such as IJ mamer-styrene-acrynitrile co-mer 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. 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 d of water) was coated on an aluminum cylinder by a coating method, and dried to form a subbing layer with a coating weight of 1 and Og/m2. Formed.

Next, 1 part by weight of a charge generating material represented by the formula (D), 1 part by weight of butyral resin (S-LEC BM-2: manufactured by Sekisui Chemical Co., Ltd.)
parts by weight and 30 parts by weight of inzorobil alcohol? -Dispersed for 4 hours using a Lumil disperser. This dispersion was first formed and coated on top of the nine sublayers by dip coating, and dried to form a charge generation layer. The film thickness at this time was 0.3μ. Next, 1 part by weight of P-diethylaminobenzaldehyde-N-phenyl-α-naphthylhydrazone, which is compound A(1) in Table 1, 1 part by weight of polysulfone resin (P1700: manufactured by Union Carbide) and 6 parts by weight of monochlorobenzene.
Parts by weight 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.

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

Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay v5). Sensitivity is determined by the exposure amount (E,, l
Evaluation was made by measuring ux e s@c).

These results were as follows.

Vo: -600 Gelt V5: -590 Gelt E'/z: 2.7 lux °sea Examples 2 to 10 In place of the compound from Compound Shop (1) used in Example 1, the compounds shown in Table 1 were used, respectively. A photoreceptor was prepared in exactly the same manner as in Example 1, except that the photoreceptor was used, and the characteristics of this photoreceptor were measured. These results are shown in Table 2. Table 2 Example Compound A Vo(-V) V (-V)
E, /21ux11sec 2 2 600 5852.6 3 3 610 6003.1 4 4 590 5803.0 5 5 605 5852.9 6 6 620 6103.5 7 7 615 6053.2 8 8 610 6053.0 9 9 605 5902 .8 10 10 600 5852.9 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 Examples of Transport Material Points Comparative Charge Comparative Charge Transport Material Structural Formula % Formula % As is clear from the results of the Examples and Comparative Examples, the laminated photoreceptor of the present invention has a It can be seen that a photoreceptor with extremely high sensitivity was obtained. Furthermore, images were produced 20,000 times using the photoconductors of Examples 1 to 3 using a copying machine (NP-1502: 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 specific hydrazone compound in the charge transport layer, thereby achieving extremely high sensitivity compared to conventional ones. This made it possible to provide a high-quality laminated electrophotographic photoreceptor.

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, R_2, R_3 and R_4 represent a hydrogen atom or a halogen atom, R_5 represents a hydrogen atom, an alkyl group or an alkoxy group, and R_6 and R_7 are an alkyl group which may have a substituent, 1. An electrophotographic photoreceptor comprising a layer containing a hydrazone compound represented by the following formula: an aralkyl group, a phenyl group, or a residue that forms a 5- to 6-membered ring together with an N atom. (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).