JPS6228744A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain high sensitivity and superior durability by using a specified polycyclic quinone pigment as a charge generating material in a charge generating layer and incorporating a specified hydrazone compound into a charge transferring layer. CONSTITUTION:A polycyclic quinone pigment represented by formula I is incorporated into the charge generating layer of a laminate type electrophotographic sensitive body, and a hydrazone compound represented by formula II [where each of R1 and R2 is (un)substituted alkyl or aryl; R1 and R2 may bond to each other to form a 5- 6-membered ring together with N; R3 and R4 are R1 and R2; each of R5 and R6 is H, halogen, nitro, (un)substituted alkyl, alkoxy, aryloxy, acyl or amino; and R is (un)substituted arylene] is incorporated into the charge transferring layer. The resulting laminate type sensitive body has high sensitivity and satisfactory durability and can give a fine image even after it is used many times. The hydrazone compound represented by the formula II may also be incorporated into the charge generating layer so as to produce a further remarkable sensitizing effect.

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 are known.

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, oxazoazoles, hydrazones, polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and squares. Organic pigments and dyes such as methine lic 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. 429
As disclosed in Japanese Patent No. 3628, electrophotographic photoreceptors are known that use a disazo pigment exhibiting photoconductivity 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.

The laminated photoconductor, which is 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 photoconductors due to its sensitivity and increased residual potential after durability tests. Although it was advantageous, 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. n) (In the formula, R1 and R2 are an alkyl group which may have a substituent, and an aryl group may be taken together with a nitrogen atom to form a 5-membered ring or a 6-membered ring. R3 and R
4 may be an alkyl group which may have a substituent, an aryl group, or may be taken together with a nitrogen atom to form a 5-membered ring or a 6-membered ring.

R5 and R61j: represent a hydrogen atom, a halodane atom, a nitro group, an alkyl group that may have a substituent, an alkoxy group, an aryloxy group, an acyl group, or an amine group.

R represents an arylene group which may have a substituent. ) 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 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 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 transported without being deactivated by recombination or capture (track 7''). 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 (1).

The charge generation layer is 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. It can be obtained by forming

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, polyvinylbutysil, polyarylate (condensation polymer of bisphenol A and heptalic acid, etc.), polycargonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin,
Polyamide, polyvinyl resin, 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
Weight - below, preferably below 40% by weight @
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 isopropanol, ketones such as acetone, methyl ethyl ketone, cyclohexanone, N, N
-Amides such as dimethylformamide, N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydro7rane, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, chloroform, chloride Aliphatic halodanized hydrocarbons such as methylene, dichloroethylene, carbon tetrachloride, trichlorethylene, etc., or aromatics such as benzene, toluene, xylene, ligroin, monochloropenze/dichlorobenzene, etc. can be used.

Coating methods include dip coating method, spray coating method, spinner coating method, peed coating method,
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. have. At this time, this charge transport layer may be laminated on top of the charge generation layer, or may be laminated below it.

The substance that transports charge carriers (hereinafter simply referred to as charge transport substance) in the charge transport layer 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. 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 general formula (II).

(In the formula, R, tR2, R3?R4, 5.R6 and R are as described above)).

Here, the alkyl group is preferably lower alkyl, and examples of the aryl group include phenyl, diphenyl, and naphthyl. Examples of the 5-membered ring or 6-membered ring include:
Pyrrolidino, piperidino.

Morpholino etc. are shown. Also alkyl, aryl,
Aryloxy, acyl, and amine groups may further include other substituents,
For example, it may be substituted with halo, alkyl, aryl, nitro, hydroxyl, and the like.

This hydrazone compound satisfies the above-mentioned conditions as a charge transport material, 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.

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 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, polycargonates, polystyrene, acrylonitrile-styrene corimers, acrylonitrile-butadiene copolymers,
Examples include insulating resins such as polyvinylbutyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, and chlorinated rubber, and organic photoconductive remers such as poly-H-vinylcarbazole, privinyanthracene, and polyvinylpyrene. .

Since the charge transport layer has a limit to its ability to transport charge carriers, it cannot be made thicker than necessary. 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, the coating method 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 (such as Rikiichi Bomb 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. It is possible to use a base coated on glass, a base made of plastic or paper impregnated with conductive particles, a glass having conductive polymer, and the like.

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, phenol resin, polyamide (nylon 6, nylon 66, nylon 6101 copolymerized 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 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 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, 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 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 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. To form an electrostatic latent image on this protective layer,
It is desirable that the surface resistivity is 10 Ω 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 0.12 to 5 microns. .

Hereinafter, the present invention will be explained according to examples.

Example 1 Aqueous ammonia solution of casein (casein 11.2.F, 28% aqueous ammonia I11) was placed on an aluminum cylinder.
Water 222d) was applied by a coating method and dried to form a subbing layer with a coating amount of 1.0 g/ln.

Next, 1 part by weight of the charge generating substance represented by formula (I), butyral resin (S-LEC BM-2: manufactured by Sekisui Chemical ■) l!
part and 30 parts by weight of Improvil 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 generation layer.

The film thickness at this time was 0.3μ. Next, parts by weight of hydrazone compound 11i from Compound Shop (1) in Table 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 ■).

Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay v5). *s
It was evaluated by measuring ec).

These results were as follows.

Vo: -570yf Ruto V5: -560 Delt E172: 5. OLux, set example 2
~7 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 photoreceptor was Characteristics were measured. These results are shown in Table 2.

Table 2 Example compound A Vo(-V) Vs(V) E
l, 41 yu, se.

225755654.9 335655554.7 445605505.2 555805705°8 665955856.0 775905805.9 Comparative Examples 1 to 6 Exactly the same except that the charge transport substance shown in Table 3 was used in place of the hydrazone compound used in Example 1. A photoreceptor was created using the method. The charging characteristics are shown in Table 4.

Tatsumi size
Q Table 4 1 1 5755507.7 2 25705507.5 3 35805558.1 4 45905708.6 5 55805608.3 6 6 5855657.9 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 photoreceptor A1-6 of the comparative example. 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 quinone-based pigment as a charge-generating material in the charge-generating layer and a specific hydrazone-based compound in the charge transport layer. 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 may be an alkyl group which may have a substituent, an aryl group, or may be taken together with a nitrogen atom to form a 5-membered ring or a 6-membered ring. R_3 and R_4 are substituted An alkyl group, an aryl group, which may have a group, or together with a nitrogen atom, may form a 5- or 6-membered ring. R_5 and R_6 are a hydrogen atom, a halogen atom, a nitro group, a substituent R represents an alkyl group, an alkoxy group, an aryloxy group, an acyl group, or an amino group that may have a substituent. R represents an arylene group that may have a substituent. An electrophotographic photoreceptor comprising: (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).