JPS6214654A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To form a laminate type electrophotographic sensitive body extremely high in sensitivity by using a specified polycyclic quinone type pigment as an electrostatic charge generating material for a charge generating layer and a specified hydrazone derivative for a charge transfer layer. CONSTITUTION:The charge generating layer contains the polycyclic quinone type pigment represented by formula I and the charge transfer layer contains the hydrazone derivative represented by formula II, typified by formula (2). When the charge transfer material is added to the charge generating layer, it is suitable to add the hydrazone derivative in an amount of 1-100pts.wt. per 100pts.wt. of the charge generating material from the viewpoint of high sensitivity, low residual potential, and repetition stability.

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 developed9. carbazole,
Low-molecular organic photoconductors such as anthracene, pyrazolines, oxacyazoles, hydrazones, polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes Alternatively, organic pigments and dyes such as 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, U.S. Pat. No. 4,123,270;
No. 7614, No. 4251613, No. 425161
No. 4, No. 4256821, No. 4260672,
Same No. 4268596, Same No. 4278747, Same No. 4
As disclosed in Japanese Patent No. 293,628, an electrophotographic photoreceptor is known in which a disazo pigment exhibiting photoconductivity is used 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 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 higher sensitivity and a higher residual potential after a 1° durability test than other single layer photoconductors. Although it is advantageous in such things, it is 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 non-based pigment in the generation layer and having 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). The charge transport layer is formed by the general formula (II) (wherein R and R2 are substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups, or atoms forming a 5-membered ring or 6-membered ring together with the nitrogen atom). indicate the group,
R3 and R4 are a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a nitrogen atom and 5
R5 and R6 are hydrogen atoms, halogen atoms, nitro groups, substituted or unsubstituted alkyl groups, alkoxy groups, substituted or unsubstituted aryloxy groups, and substituted or unsubstituted aryloxy groups. An electrophotographic photoreceptor comprising a layer containing a hydrazone compound represented by (representing a substituted acyl group or a substituted or unsubstituted 7-mino group, R representing a divalent organic residue) .

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 microns or less, preferably o, oi microns 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 (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 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 polyvinylpyrene. 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 include insulating resins such as urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is 80
A weight percent or less, preferably a 40' weight i% 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 methyl ether, esters such as methyl acetate and ethyl acetate, chloroform, and methylene chloride. , aliphatic halogenated hydrocarbons such as dichloroethylene, carbon tetrachloride, and trichlorethylene, or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, and dichlorobenzene.

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 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 material that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport material) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer described in h. "Electromagnetic waves" includes the broad definition of "light rays" including gamma 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 general formula (II).

(In the formula, R1 and R2 represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or an atomic group forming a 5-membered ring or a 6-membered ring together with a nitrogen atom,
R3 and R4 are a substituted or unsubstituted alkyl group, a substituted or unsubstituted 7-aryl group, or a nitrogen atom and 5
Represents an atomic group forming a membered ring or a 6-membered ring, R5 and R6 are 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 represents an unsubstituted acyl group or a substituted or unsubstituted amine group, and R represents a divalent organic residue) This hydrazone compound is
It meets the above conditions as a charge transport material, and has excellent properties particularly in terms of sensitivity and durability.

Typical hydrazone compounds represented by the general formula CH) used in the present invention are illustrated in Table 1.

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 transporting material to the charge generation layer, the hydrazone compound should be 10 times or less (weight ratio), preferably 0.01-1 times (weight ratio) of the charge generation material to achieve high sensitivity, low residual potential,
This is appropriate from the point of view of regression 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, polyacrylates, polyesters, polycarbonates, and polystyrene.

Acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, 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, polyvinylanthra7ane, and 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 a substrate, 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, nitrocellulose, ethylene-
It can be formed from acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon BIG, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc.

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 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, ozone, etc., dirt from oil, etc., scratches from metal chips, etc., damage to the photoreceptor due to photoreceptor contact members such as developing members, transfer members, cleaning members, etc. A protective layer may be further provided on the charge generation layer or the charge transport layer for the purpose of preventing abrasion. In order to form an electrostatic latent image on this protective layer,
It is desirable that the surface resistivity is 19110 or more.

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 mJD of water) was coated on an aluminum cylinder using a coating method, and dried to form a subbing layer with a coating amount of x and an og 7 g. did.

Next, 1 part by weight of a charge-generating material represented by formula (I), 1 part by weight of butyral tree (S-LEC BM-2: manufactured by A Suikagaku ■)
lffi and 1 part of 30 g 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) 1 part by weight of the hydrazone compound, 1 part by weight of polysulfone resin (P1700: manufactured by Unio 7 Carbide Co., Ltd.) and 6 parts by weight of monochlorobenzene were mixed,
The mixture was stirred and dissolved using an 82 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 3IL.

The thus prepared photoreceptor was subjected to a 15 KV co-discharge. The surface potential at this time was measured (initial potential VO),
Furthermore, the surface potential of this photoreceptor was measured after leaving it in a dark place for 5 seconds (dark decay 5). El/2
The evaluation was made by measuring the visual ux*5ec).

These results were as follows.

Vo: -600 volts 5: ~590 ports El/2: 4.71 uxasec Example 2~
5 Compound No. (1) used in Example 1 except that the compounds shown in Table 1 were used, respectively.

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 in Table 2.

Table 2 Example compound No. Vo(-V) V5(-V) E
l/21ux*5ec 2 2 5955855.0 3 3 5905805.2 4 4 6106006.0 5 5 6005905.5 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
Comparison'-[Cargo Comparison Charge Transport Material Structural Formula Transport Object If!
i Table 4 Comparative example Ratio 411 load Vo (-V) Vs (-V)
El/2 Transport substance No lux*5
ec1 1 5905657.4 2 2 5805507.0 3 3 5905657.6 4 4 6055808.1 5 5 5855607.2 6 6 5805557.6 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 the comparative examples of photoreceptor movement 1 to positive and 6. Furthermore, using the photoconductors of Examples 1 to 3 using a copying machine (NP-150Z: manufactured by Canon Inc.), image production 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-generating material in the charge-generating layer and a specific hydrazone-based compound in the charge transport layer, thereby achieving extremely high sensitivity compared to conventional ones. Our aim is to provide a laminated type electrophotographic photoreceptor with high viscosity.

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 substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or an atomic group forming a 5-membered ring or a 6-membered ring together with a nitrogen atom, and R_3 and R_4 are substituted or unsubstituted aryl groups. Indicates a substituted alkyl group, a substituted or unsubstituted aryl group, or an atomic group that forms a 5- or 6-membered ring with a nitrogen atom,
R_5 and R_6 are hydrogen atoms, halogen atoms, nitro groups, substituted or unsubstituted alkyl groups, alkoxy groups,
It represents a substituted or unsubstituted aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted amino group, and R represents a divalent organic residue. ) 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).