JPS61289352A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To form a laminate type electrophotographic sensitive body high in sensitivity and extremely small in residual potential even after durability test by incorporating a polycyclic quinone type pigment in an electrostatic charge generating layer, and a hydrazone derivative in 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 II-1. It is preferred for the charge generating layer to contain a charge generating material as much as possible in order to obtain sufficient light absorbance, and to have a very small thickness of 0.01-1Xm in order to efficiently inject generated charge carriers to the charge transfer layer, thus permitting the obtained laminate type electrophotographic sensitive body to be extremely high in sensitivity as compared with the conventional ones.

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, 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, US Patent No. 4,123,270.

Same No. 4247614, Same No. 4251613.

Same No. 4251614, Same No. 4256821, Same No. 4
No. 260672, gg4268596.

An electrophotographic photoreceptor using a disazo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer functionally separated into a charge generation layer and a charge transport layer, as disclosed in 4278747 and 4293628. etc. 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 photosensitive liquid wall.

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 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 is comprised of a layer containing a polycyclic quinone pigment represented by formula (I). , the charge transport layer has the general formula (II) (wherein 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 6Q 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
Indicates 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, 22! l
j! or unsubstituted alkyl group, alkoxy group, Wi
Represents a substituted or unsubstituted 7-aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted 7-mino group, R represents a substituted or unsubstituted 7-arylene group,
) This is an electrophotographic photoreceptor characterized by comprising a layer containing a hydrazone compound represented by:

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 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 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, poly7-rylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy Examples include insulating resins such as resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

The solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the above-mentioned charge generation layer and 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, Aliphatic halogenated hydrocarbons such as dichloroethylene, carbon tetrachloride, trichlorethylene, etc. or aromatics such as benzene, toluene, xylene, refloin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
Meyer bar coating method, blade coating method, roller coating method.

This can be carried out using a coating method such as a curtain coating method. Drying is preferably carried out by drying to the touch at room temperature and then heating.
It can be carried out at 0° C. for a period of time ranging from 5 minutes to 2 hours, either stationary or under ventilation.

The charge transport layer is electrically connected to the charge generation layer described above, receives and takes charge carriers injected from the charge generation layer in the presence of an electric field, and has a Jl ability that can transport these charge carriers to the surface. have. At this time, this charge transport layer may be formed on the charge generation layer,
Moreover, it may be laminated thereunder.

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. 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 substance used in the present invention is a hydrazone compound represented by the general formula CI+).

(In the formula, R1 and R2 represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted 7-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 non-substituted 7-aryloxy group, 22 Exchange or non-2i! !
! ! represents an acyl group or a substituted or unsubstituted 7-mino group, R represents a substituted or unsubstituted 7-arylene group,
) This hydrazone compound satisfies the above-mentioned conditions as a charge transport substance, and has excellent properties particularly in terms of sensitivity and durability.

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

Table 1a Table 1b Furthermore, in the present invention, the above-mentioned doracin compounds used in the charge transport layer and the like 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 is 10 times (weight ratio or less, preferably 0.01 to 1 times (weight ratio)) as high sensitivity, low residual potential, and
This is appropriate from the viewpoint of repeat stability.

To form a charge transport layer containing a hydrazone compound, a film can be formed by selecting an appropriate binder. Resins that can be used as binders include acrylic resins, polyacrylates, polyesters, polycarbonates, polystyrene, 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, 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.

aIf of such a charge generation layer and charge transport layer! ! A photosensitive layer consisting of a structure is provided on a substrate or electrically conductive support having an electrically conductive layer. 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, platinum, etc. can be used, and in addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. can be coated by vacuum evaporation method. A substrate in which a plastic (e.g., carbon black, silver particles, etc.) that softens the formed layer is coated on a plastic together with an appropriate binder, a substrate in which plastic or paper is 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 610, co-In 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 the conductor layer, charge generation layer, and charge transport layer are made of aN 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 are injected into the charge transport layer in the exposed area.
After that, it reaches the surface and neutralizes the positive charge, resulting in attenuation of about one surface type, creating an electrostatic contrast with the unexposed area. 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, 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 scratching.In order to form an electrostatic latent image on this retaining WIN, the surface resistivity must be 10Ω or more. This is desirable.

The protective layer used in the present invention is made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-7crylonitrile copolymer, etc. The photosensitive layer can be formed by dissolving a resin in a suitable organic solvent and applying the solution onto the photosensitive layer and drying it.

Moreover, additives such as ultraviolet absorbers can be added to the resin liquid. At this time, the film thickness of the insulation 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 mJL of water) was coated on an aluminum cylinder by a coating method, dried, and coated 11. A subbing layer of og/rn' was formed.

Next, 147 parts of a charge generating material represented by formula (I),
Butyral resin (S-LEC BM-2: manufactured by a water chemical company)
1 part by weight and 30 parts by weight of inpropyl alcohol were dispersed for 4 hours in a ball mill dispersion system.

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 0.31L.

1 part by weight of a hydrazone compound of compound Nb(1) in Table 1, 1 part by weight of polysulfone resin (P1700: manufactured by Union Carbide), and monochlorobenzene 6! i parts were mixed and stirred and dissolved using 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 3μ.

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 11 V s). (
Evaluation was made by measuring El/2 (see 5ec).

These results were as follows.

Vo: -585 volts Vs: -575 volts El/2: 4.3JLuxesec Example 2
~5 In place of the compound ND(1) used in Example 1, 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 No We(-V) V5(-V)
E172 traffic U! φ5ec 2 2 590580 4.43 3
580570 3.84 4 5705
60 4.05 5 600590 5.
2 Comparative Examples 1 to 6 Photoreceptors were prepared in exactly the same manner except that the charge transporting substances shown in Table 3 were added to the hydrazone compound used in Example 1. It is 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 substance table 4 Comparative example Comparative charge VO (-V) V5 (-V) E
l/2 Transport Monoga No lux fist 5ec
As is clear from the results of the 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. Further, the photoreceptors of Examples 1 to 3 were printed at 20,000 yen using a copying machine (NP-150Z: Canon Inc.!2).
Repeated several 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 compound in the charge transporting layer, which makes it much more effective than conventional ones. This makes it possible to provide a laminated electrophotographic photoreceptor with high sensitivity.

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 substituted or unsubstituted arylene 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).