JPS61196249A - 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 laminating an electrostatic charge generating layer contg. a specified polycyclic quinone type pigment and a charge transfer layer contg. a specified hydrazone deriv. CONSTITUTION:The charge generating layer contains the polycyclic quinone type pigment represented by formula (I) and the charge transfer layer contains the hydrazone deriv. represented by formula (II) in which each of R1, R2 is H, or optionally substd. aryl or heterocyclic, and each of R3, R4 is optionally substd. alkyl, aralkyl, aryl, or heterocyclic, and R6 is a divalent org. residue. It is preferred for the charge generating layer to contain the charge generating material as much as possible in order to optain sufficient light absorbance, and to have film thickness as thin as 0.01-1mum in order to inject generated charge carriers efficiently to the charge transfer layer.

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, polyvinylanthra7ane, 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 range of options for selecting compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded. , a large number of photoconductive 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. 42936J8, etc., in a photosensitive layer functionally separated into a charge generation layer and a charge transport layer. Electrophotographic photoreceptors using photoconductive resazo pigments 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 amount of laminated photoreceptors 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 type photoreceptors due to the sensitivity and increase in residual potential after durability tests. 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 to provide an 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 in an 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 attempted to be achieved by using a certain percentage of polycyclic kino/type pigment in the generation layer and having a specific hydrazone compound in the charge transport layer.

[Means for solving problems]

The present invention provides an electrophotographic photoreceptor comprising a laminate 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 quinone pigment represented by formula (1). The charge transport layer has the general formula (II) (wherein R1 and R2 represent a hydrogen atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. R3 and R4 are substituted or unsubstituted heterocyclic groups). A hydrazone compound represented by a substituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group.R5 represents a divalent organic residue. An electrophotographic photoreceptor characterized by comprising a layer containing:

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 one thin film layer, for example, a thin film layer having a thickness of less than 10 microns, or from 0.01 microns to 1 micron. This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are transported by recombination or trapping without being deactivated. This is due to the need to inject into the layer.

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

The charge generation layer can be formed by coating the above-mentioned pigment and, if necessary, a charge transporting material on the substrate together with a suitable pine binder (it is possible without a binder). can be obtained by forming .

The binder that can be used to form 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, 4-rivinylanthracene, and polyvinylpyrene. . Preferably,? Livinyl buttyl, I realylate (condensation polymer of hisphenol and 7-talic acid, etc.), I
Recarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin,
Priamide, polyvinylpyridine, cellulose resin,
Examples include insulating resins such as urethane resin, polyurethane resin, casein, polyvinyl alcohol, and yl'l pyrrolidone. The resin contained in the charge generation layer is
A weight of less than 80 weight, preferably less than 40 weight, 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 isoproanol, acetone, methyl ethyl ketone, ketones such as 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 halodanized hydrocarbons such as dichloroethylene, carbon tetrachloride, trichlorethylene, etc., or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichloroenzene, etc. can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using a coating method such as a Mayer coating method, a blade 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. In this case, the 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 furthermore, when the binder in the charge transport layer is selected, K. This is desirable in that a good photoreceptor surface can be formed.

It is preferable that the substance that transports Yaria in the charge in the charge transport layer (hereinafter simply referred to as charge transport substance) is 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 of the charge transport layer matches or overlaps that of the charge generation layer, charge carriers generated in both 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 hydrogen atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. R3 and R4 represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group) group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. R5 represents a divalent organic residue.) This hydrazone compound satisfies the above conditions as a charge transport substance. It has excellent properties, especially in terms of sensitivity and durability.

Representative compounds of the hydra-zozone compound represented by the general formula (II) used in the present invention are illustrated in Table 1.

/-1\ In addition, 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 binder. Resins that can be used as binders include, for example, acrylic resins, polyacrylates, polyesters, polycarnates, polystyrene, acrylonitrile-styrene copolymers, acrylonitrile-butadiene codelimers,
Polyvinyl butyral, /I7 vinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated f
Examples include insulating resins such as aluminum oxide, and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyhinylpyrene.

The charge transport layer cannot be made thicker than necessary because there is a limit to its ability to transport Yaria in the charge. 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 may be one in which the substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel%/l-/cum, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. In addition, it can be used as a glass material having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. (e.g., carbon black, silver particles, etc.) A substrate obtained by coating a glass material with a suitable binder on a glass material, a substrate obtained by impregnating a glass material or paper with conductive particles, a plastic material containing a conductive polymer, etc. can be used.

4ii! A subbing layer having barrier and adhesive functions can also be provided between the layer and the photosensitive layer. The subbing layer contains casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid co-tymer, polyvinyl butyral,
Phenolic resin, polyamide (nylon 6, nylon 6
6. Nylon 610.

It can be formed from 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.

Is the conductive layer, charge generation layer, and charge transport layer stacked in this order? When using a photoreceptor, if 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, and when exposed after charging, a charge is generated in the exposed area. Electrons generated in the layer are injected into the charge transport layer, which then reaches the surface and neutralizes the positive charge, resulting in a decay of the surface potential and an electrostatic contrast with the unexposed areas.

A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. Either fix this directly, or transfer the toner image to paper or plastic film, etc.
It can be established and established.

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 subject to deterioration due to ultraviolet rays, ozone, etc., stains due to oil, etc., scratches due to cutting powder of metal, etc., and damage to the photoreceptor due to members in contact with the photoreceptor 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 e. 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 - ribinyl petyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-7 It can be formed by applying a solution prepared by dissolving a resin such as acrylonitrile cotelimer 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 Aqueous ammonia solution of casein (casein 11.2.9, 28% ammonia water 11.
Water (222d) was applied by a coating method and dried to form a subbing layer with a coating amount of 1.01/m2.

Next, 1 part by weight of a charge generating material represented by the formula CI), 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 Goal 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 0.3μ. Next, compound A (1
), 1 part by weight of P-diethylaminobenzaldehyde-N-phenyl-α-naphthylhydrazone, polysulfone resin (P1700: Union Carbide #11
6 parts by weight of monochlorobenzene were mixed and dissolved by stirring with a stirrer. This i was applied onto the charge generation layer by dip coating and dried to form the entire charge transport layer.

The film thickness at this time was 12μ.

The photoreceptor K thus prepared was subjected to corona discharge at -5 kV. 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 was evaluated by measuring the exposure amount (E% Lux-ale) f required to attenuate the potential V after dark decay to W.

These results were as follows.

vo: -600 Delt v5: -5ss*Ruto Ey2: 5. OLaxa s@e Example 2~
10 A photoreceptor was prepared in exactly the same manner as in Example 1, except that the compounds shown in Table 1 were used in place of the compound A(1) used in Example 1, and the characteristics of this photoreceptor were determined. was measured. These results are shown in Table 2.

Table 2 M・ale 2 2 6005905.3 3 3 6106006.2 4 4 6106006.0 5 5 5955805.4 6 6 6005855.3 7 7 6055905.1 8 8 5905755.8 9 9 6106005.5 10 10 5855705. 7 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.

; Cao-Kyo no Hon-Zheng's table 4 1 1 6005807.7 2 2 5905657.1 3 3 5955707.5 4 4 6155908.3 5 5 6005707.4 6 6 5905607.9 From the results of Examples and Comparative Examples As is clear, the lamination amount photoreceptor of the present invention has a lower lamination amount than the comparative example photoreceptors I61 to A6.
It can be seen that a photoreceptor with extremely high sensitivity was obtained. Furthermore, using the photoconductors of Examples 1 to 3, images were produced 120,000 times 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 generating material in the charge generating layer and a specific hydrazone compound in the charge transporting layer, thereby making it significantly more effective than the conventional ones. This makes it possible to provide an electrophotographic photoreceptor with high sensitivity and a high lamination amount.

Claims (2)

[Claims] (1) In a photographic photoreceptor with a laminated amount 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) It consists 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 and R_2 are hydrogen atoms, substituted or unsubstituted. represents an aryl group or a substituted or unsubstituted heterocyclic group. R_3 and R_4 are a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group,
Indicates a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group. R_5 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).