JPS6219872A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain high sensitivity and excellent durability by using a specific polycyclic quinone pigment as an electric charge generating material for an electric charge generating layer and incorporating a specific hydrazone compd. into an electric charge transfer layer. CONSTITUTION:The polycyclic quinone pigment expressed by the formula I is incorporated into the charge generating layer of a lamination type photosensitive layer provided on a conductive base and the hydrazone compd., expressed by the formula II [R1, R2 are an (un)substd. alkyl, aryl or may together form a 5- or 6-membered ring with an N atom. R3, R4 are synonymous with R1, R2. R5, R6 are H, halogen atom, nitro (un)substd. alkyl, alkoxy, aryloxy, acyl, or amino. R is a bivalent residual org. group] is incorporated into the charge transfer layer. The hydrazone compd. expressed by the formula II is preferably added to the charge generating layer, by which the much better sensitization effect is obtd. Such laminated type photosensitive body has the high sensitivity and provides the excellent image even after many times of uses. The photosensitive body has the good durability as well.

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,
Low-molecular organic photoconductors such as anthracene, pyrazolines, oxadiazoles, hydrazones, and polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, polyurethane pigments, indigo dyes, and thioindigo Organic pigments and dyes such as dyes or 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. 42
As disclosed in Japanese Patent No. 93628, electrophotographic photoreceptors are known that use a disazo pigment exhibiting photoconductivity as a charge generation material in a photosensitive layer 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, making it possible to provide photoreceptors with extremely high productivity and 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 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 composed 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 are a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or together with a nitrogen atom, a 5-membered ring or a 6-membered ring. R3 and R4 may form a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or together with the nitrogen atom, a 5- or 6-membered ring.

R5 and R6 represent a hydrogen atom, a halodane atom, a nitro group, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted amine group. show. R represents a divalent organic residue. ) 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 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, generating many charge carriers, and that the generated charge carriers are not deactivated by recombination or trapping, but are transferred to the charge transport layer. This is due to the need for injection.

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 a substrate, or by forming a vapor deposited film using a vacuum vapor deposition apparatus. You can get it by doing this.

The binder that can be used when forming the charge generation layer by coating can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polyamides such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. . Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and heptalic acid, etc.), polycarnate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin,
polyamide, polyvinylpyridine, cellulose resin,
Insulating resins such as urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone can be mentioned.Resin contained in the charge generation layer is 80%
A weight below -, preferably below 40% by weight is suitable.

The solvent that dissolves these resins varies depending on the type of 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 alcohols such as methanol, ethanol, and imprononol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide. Various sulfoxides, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halodanization and carbonization such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichlorethylene. Hydrogens 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,
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 picking up 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 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 a broad definition of "light rays" that includes gamma green, 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 (9).

(In the formula, R1, R2, R3, R4, R5, R6 and R are as defined above).

Here, the alkyl group is preferably lower alkyl, and examples of the aryl group include phenyl, diphenyl, and naphthyl. Examples of the 5- to 6-membered ring include morpholino, piperidino, and pyrrolidino. Furthermore, the alkyl group, aryl group, aryloxy group, acyl group, and amine group may be further substituted with other substituents such as halodane, alkyl, aryl, and the like.

The divalent organic residue for R is preferably a divalent hydrocarbon group, such as -CH-Cll-.

-fCH2-f (n is an integer of 1 or more), etc. are shown.

The above hydrazone compound satisfies 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 (9) used in the present invention are illustrated in Table 1.

Table 11 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 a charge transport substance is added 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 substance to provide high sensitivity, low residual potential,
This is suitable 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. Resins that can be used as binders include, for example, acrylic resins, polyacrylates, polyesters, polycarbanates, polystyrene, acrylonitrile-styrene copolymers, acrylonitrile-citadiene copolymers,
Insulating resins such as polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or organic photoconductive materials such as polyvinyl butyral, polyvinyl anthracene, polyvinyl pyrene, etc. IJ Mama - I can mention it.

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 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 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.) together with a suitable binder. A substrate coated on plastic, a substrate made of glass or paper impregnated with conductive particles, a plastic snack 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. Subbing layer, casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
It can be formed from acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610, combined 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 an electron transport material, it is necessary to positively charge the surface of the charge transport layer. 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. Electrocontrast 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, 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, it is necessary to charge the surface of the charge transport layer negatively. When exposed to light after charging, holes 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 negative charges, resulting in attenuation of the surface potential and an electrostatic contrast between it 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., stains due to oil, etc., scratches due to metal chips, etc., damage to the photoreceptor due to photoreceptor drawing 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. To form an electrostatic latent image on this protective layer,
It is desirable that the surface resistivity is 1011Ω or more.

The protective layer used in the present invention is made of polyvinyl butyral, polyester, polycarbanate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile 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 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 (casein 11.2 F, 28% ammonia water 1 t, water 222 ml) was coated on an aluminum 7 linder using a coating method, and dried to form a subbing layer with a coating amount of 1° Of/m2. was formed.

Next, 1 part by weight of the charge-generating substance represented by formula (1), butyral resin (Esle, Ri BM-2: Tsukusui Kagaku Co., Ltd. g)
1 part by weight and 30 parts by weight of isopropyl alcohol were dispersed for 4 hours using a Solmill 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, the compounds 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 was 12.5μ.

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

Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay Vs). The sensitivity is determined by the amount of exposure (El/2) required to attenuate the potential v5 after dark decay by half.
1uX'1N1e).

These results were as follows.

Vo: -570yW Volt v5: -555V El/2: 5.51ux°sec Example 2~
6 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 from Compound Shop (1) used in Example 1, and the characteristics of this photoreceptor were determined. was measured. These results are shown in Table 2.

Table 2 2 2 565 550 5.7 3 3 570 55.5 6.0 4 4 580 570 6.6 5 5 580 565 6.3 6 6 585 575 6.8 Comparative Examples 1 to 6 Used in Example 1 A photoreceptor was prepared in exactly the same manner except that the charge transport material shown in Table 3 was used in place of the hydrazone compound. The charging characteristics are shown in Table 4.

Table 3 Table 4 1 1 550 530 7.9 2 2 550 525 7.7 3 3 560 530 8.2 4 4 570 550 8.8 5 5 555 530 8.3 6 6 545 520 8.6 Examples and comparisons As is clear from the results of the examples, it can be seen that the laminated thermal photoreceptor of the present invention has extremely high sensitivity compared to the photoreceptors A1 to A6 of the comparative examples. Furthermore, using the photoconductors of Examples 1 to 3 using a copying machine (NP-1502: 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 quinone pigment as a charge generation material in the charge generation layer and a specific hydrazone compound in the charge transport layer, thereby making the present invention extremely superior to the 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.▼(I) The charge transport layer consists of a layer containing a polycyclic quinone pigment represented by the general formula (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R_1 and R_2 may be an alkyl group, an aryl group, which may have a substituent, or may be taken together with a nitrogen atom to form a 5- or 6-membered ring. R_3 and R_4 are substituents. may have an alkyl group, an aryl group, or may be taken together with a nitrogen atom to form a 5- or 6-membered ring. R_5 and R_6 represent a hydrogen atom, a halogen atom, a nitro group, or a substituent. (represents an optional alkyl group, alkoxy group, aryloxy group, acyl group, or amino group; R represents a divalent organic residue). An electrophotographic photoreceptor. (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).