JPS6221155A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a laminate type electrophotographic sensitive body high in sensitivity by using a specified polycyclic quinone type pigment in an electrostatic charge generating layer as a charge generating material and a specified hydrazone type compound for a charge transfer layer. CONSTITUTION:The charge generating layer is formed by coating a substrate with the polycyclic quinone type pigment represented by formula (I) as the charge generating material, when needed, together with the charge transfer material and a proper binder, or depositing said pigment film with a vacuum vapor deposition device. The charge transfer layer is electrically connected with the charge generating layer and has a function of receiving charge carriers injected from the charge generating layer in the presence of an electric field and transferring them to the surface. The material for transferring the charge carriers in the charge transfer layer is substantially insensitive to the electromagnetic waves of the wavelength region to which the charge generating by formula (II) are used for it, and that can be added to the charge generating layer, permitting that sensitization effect to be more distiguished.

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 polymers such as poly-N-vinylcarbazole, polyvinylanthracene, carbazole,
Anthracene, pyrazolines, oxadiazoles, hydrazones.

Organic pigments and dyes such as low-molecular organic photoconductors such as polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and squaric acid methine dyes are used. 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.

An electrophotographic photoreceptor using such an organic photoconductor can be produced by coating by appropriately selecting a binder, so it is possible to provide a photoreceptor with extremely high productivity and low cost.
Moreover, it has the advantage that the sensitive wavelength range can be freely controlled by selecting the organic pigment.

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 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). and the charge transport layer has the general formula (n) (wherein R1 and R2 are 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) shows,
R3 and R4 are a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a nitrogen atom and 5
Represents an atomic group forming a negative 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 aryloxy group, a substituted or unsubstituted aryloxy group, The present invention is an electrophotographic photoreceptor characterized by comprising a layer containing a hydrazone compound represented by (representing a substituted acyl group or a substituted or unsubstituted amino 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 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 with a thickness of less than IO micron or 0.01 micron to 1 micron.
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 by recombination or trapping. It is caused by something.

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

The charge generation layer consists of the above-mentioned pigments and, if necessary, a charge transporting material together with a suitable binder (it is also possible without a binder)!
It can be formed by coating on the S body, or it can be obtained by forming a vapor deposited film using a vacuum evaporation device.

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 vinylanthracene and polyvinylpyrene.
Preferably, polyvinyl butyral, polyarylate (
f of bisphenol A and 7-talic acid! Insulating properties of polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, etc. One example is resin. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 4Oi% or less.

The solvent that dissolves these resins varies depending on the type S of the 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 methanol, ethanol,
Alcohols such as isopropanol, 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, ligroin, 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 most preferably carried out by drying to the touch at room temperature and then heating. Heat drying at 30℃~2
It can be carried out at 00° 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, 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. I have it. 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 material) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The "electromagnetic waves" mentioned here include gamma rays, X-rays,
Includes a broad definition of "ray" that includes far-infrared rays, etc. 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 It represents an unsubstituted acyl group or a substituted or unsubstituted amino group, and R represents a divalent organic residue. ) This hydrazone compound satisfies the above-mentioned conditions as a charge transport substance, and has excellent properties particularly 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 is used at 1r1. It can be added to the load-generating layer, and its sensitizing effect 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 to 1 times (weight ratio) of the charge generation material to achieve high sensitivity, low residual potential,
This is appropriate from the viewpoint of cyclic 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, polyvinylanthracene, 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 a conductive layer, materials whose substrate itself is conductive (for example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molyftene, chromium, titanium, nickel, indium, gold, platinum, etc.) 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 lurol, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 810, copolymerized nylon,
Alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is. O. 1 micron to 40 micron, preferably 0.1 micron to 3 micron is suitable.

When using a photoreceptor having a conductive layer, a charge generation layer, and a charge transport layer in this order, and the charge transport material in the charge transport layer is 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 and neutralize the positive charge, causing the surface potential to attenuate and creating static between the unexposed area and the exposed area. Electrical contrast occurs. A visible image can be obtained by developing the electrostatic latent image created in this way with 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 can be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, and then visualized 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, 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 subject to deterioration due to ultraviolet rays, ozone, etc., stains due to oil, etc., scratches due to 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 scratching. In order to form an electrostatic latent image on this protective layer, the surface resistivity must be 1011Ω or more. 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 mJl of water) was coated on an aluminum cylinder by a coating method and dried to form a subbing layer with a coating amount of 1.0 g/ba. was formed.

Next, 1 part by weight of a charge generating material represented by formula (I), 1 part by weight of butyral resin (S-LEC BM-2: manufactured by Sekisui Chemical ■)
Parts by weight 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 JL. Next, compound N0 in Table 1
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 3 ru.

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 5). Quantity (El
/2 uxasec) was evaluated.

These results were as follows.

VO: -eoo Porto vs: -590 volts El/2: 5. 'NLux*sec Example 2
~5 Instead of the compound Nb(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 No Vo(-V) Vs(-V)
El/2 cross ux@5ec 2 2 5955856.3 3 3 5905806.7 4 4 6005907.2 5 5 6005906.8 Comparative Examples 1 to 6 Charge transporting substances shown in Table 3 in place of the hydrazone compound used in Example 1 A photoreceptor was produced in exactly the same manner except that . The charging characteristics are shown in Table 4.

Table 3 Comparative example Comparative charge Comparative charge transport material structural formula % formula % Comparative example Comparative charge Comparative charge transport material structural formula Transport substance I
fINO Table 4 Comparative example Comparative charge Vo(-V) Vs(-V) E
l/2 transport substance fall uXmSec1
1 6005758.3 2 2 5905B58.1 3 3 5955708.6 4 4 6156009.4 5 5 6005808.7 6 6 6055758.9 As is clear from the results of Examples and Comparative Examples.

The laminated photoreceptor of the present invention is a comparative example photoreceptor No.
It can be seen that a photoreceptor with extremely high sensitivity was obtained compared to No. 6. Furthermore, the photoreceptors of Examples 1 to 3 were copied l&(NP-1
502: manufactured by Canon Inc.) to output the image 2
Repeated 0000 times. As a result, both photoreceptors were 20
Good quality images were obtained even after 000 repetitions. 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 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).