JPS6228742A - 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 incor porated 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 formu la 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 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, poly-N-vinylcarbazole, polyvinyl/
Organic photoconductive polymers such as thracene, 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 pariage range has been expanded, allowing selection of compounds that exhibit photoconductivity in an appropriate wavelength range.
A number of photoconductive organic pigments 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 No. 3628, No. 3628, No. 3628, 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 is known. There is.

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 photoreceptor, 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 photoreceptors due to its sensitivity and increased residual potential after durability tests. Although it is advantageous, it is still not at a sufficient level9.

[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 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 quinone pigment represented by formula (1). The charge transport layer has the general formula (II) (wherein R1 and R2 are an alkyl group that may have a substituent, an aryl group, or together with a nitrogen atom, form a 5- or 6-membered ring. May be R3 and R
4 may be an alkyl group or an aryl group which may have a substituent, or may be taken together with a nitrogen atom to form a 5-negative term or a 6-membered ring.

R5 and R6 may have a hydrogen atom, a halodane atom, a nitro group, or a substituent. Alkyl group, alkoxy group,
Indicates 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 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 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 (1).

The charge generation layer can be formed by coating the above-mentioned pigments and, if necessary, a charge transporting material together with a suitable binder (or without a binder) on the substrate, or by applying the deposited film using a vacuum deposition apparatus. It can be obtained by forming

There is a wide range of pine finishes that can be used when forming the charge generation layer by coating. ! It can be selected from resins and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bis-7enol A and heptatalic acid, etc.), polycarbonate, etc. Insulating resins such as ester, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, broken vinyl pyridine, cellulose LIIW, urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone can be mentioned. can. 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 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 tetrahydrofuran, nooxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, Aliphatic halodanized hydrocarbons such as dichloroethylene, carbon tetrachloride, trichlorethylene, etc., aromatics such as alyhabenzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating method, spray coach ink method, spinner coating method, bead coating method,
This can be carried out using a coating method such as Mayer T4-coating method, blade coating method, roller coating method, curtain coating method, or the like. 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 the charge generation layer or may be laminated below it.

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" used herein includes the broad definition of "light rays" including r-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 material used in the present invention is a hydrazone compound represented by general formula (II).

R3R4R, R4 (in the formula R1y R2* R3+ R4r Rs r R
6 and R are as described above).

Here, the alkyl group is preferably lower alkyl (a), and the aryl group includes, for example, phenyl, diphenyl, naphthyl, and the like. For example, as a 5-membered or 6-membered term,
Examples include pyrrolidino, pyridino, and morpholino.

In addition, the alkyl, aryl, aryl, cy, acyl, and amino groups may be further substituent groups, such as halodane, alkyl,
May be substituted with aryl, nitro, hydroxyl, etc.

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.

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 (weight ratio) or less, preferably 0.01 to 1 times (weight ratio) of the charge generation material to achieve high sensitivity, low residual potential, and repeated stability. It is appropriate from a gender perspective.

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 resin, polyacrylate, etc. Lyester, Polycar?
Insulating resin such as acrylonitrile-styrene copolymer, acrylonitrile-butazoene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated dem, or poly-N-
Organic photoconductive polymers such as vinylcarbazole, polyvinylanthracene, polyvinylpyrene and the like may be mentioned.

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 conductor 11, 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, a glass material (e.g., cardan black, silver particles, etc.) having a layer formed by vacuum evaporation of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. In addition to Ingu, a substrate coated on glass, a substrate made of glass or paper 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. Subbing layer, casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
Acrylic acid colimer, polyvinyl butyral, phenolic resin, polyamide)'(S(lon 6, nylon 66,
Nylon 61o.

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.

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, glass film, etc. and then developed and fixed.

Alternatively, a method may be used in which the S-electronic 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., dirt 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, 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 includes polyvinyl butyral, polyester, polycarnate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butazoene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer. The photosensitive layer can be formed by dissolving a resin such as the like in an appropriate organic solvent and coating 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 described according to Examples.0 Example 1 Aqueous ammonia solution of casein (casein 11.2j', 28 thiammonia water 1f1) was placed on an aluminum cylinder.
Water 222+d) was applied by a coating method and dried to form a subbing layer with a coating amount of 1.0 y-7 m''.

Next, 1 part by weight of a charge generating substance represented by formula (I), butyral resin (S-LEC BM-2: manufactured by Sekisui Chemical (C))
1 part by weight and 30 parts by weight of isozorobyl alcohol were dispersed for 4 hours using a Gehr 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, 1 part by weight of the hydrazone compound of Compound A (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 Vo)
. Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay VS).
ILIX-sac) was evaluated.

These results were as follows.

Vo: -590 & ruto v5 knee 580 volts E14: 5.11 ux-sec Examples 2 to 7 In place of the compound A(1) used in Example 1, the compounds shown in Table 1 were used, respectively. A photoreceptor was prepared in exactly the same manner as in Example 1, and the characteristics of this photoreceptor were measured. These results are shown in Table 2. 6.0 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.

Table 3 C2H5 Table 4 1 1 590 565 7.3 2 2 580 555 7.1 3 3 590 570 7.6 4 4 610 590 8.6 5 5 595 565 7.8 6 6 600 570 7.5 Examples and As is clear from the results of the comparative examples, it can be seen that the laminated 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-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 may have an alkyl group, an alkoxy group, an aryloxy group, an acyl group, or an amino group.R represents an arylene group which may have a substituent.) An electrophotographic photoreceptor characterized by being composed of layers. (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).