JPS62962A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To increase the sensitivity of a sensitive body by incorporating a specified polycyclic quinone pigment into the charge generating layer and a hydrazone compound into the charge transferring layer. CONSTITUTION:A charge generating layer contg. a polycyclic quinone pigment represented by formula I and a charge transferring layer contg. a hydrazone compound represented by formula II are laminated on an electrically conductive support. When the compounds represented by formulae I, II are used, the sensitiv ity of the resulting sensitive body is increased and the durability is improved. In formula II, each of R1 and R2 is H, halogen, nitro, (un)substituted aryloxy or amino; each of R3 and R4 is (un)substituted alkyl or aryl; and each of R5-R8 is H, halogen, nitro, (un)substituted alkyl, alkoxy, (un)substituted aryloxy, (un) substituted acyl or amino.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] 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, a number of organic photoconductors have been developed. carbazole,
Low-molecular organic photoconductors such as anthracene, pyrazolines, oxadiazoles, hydrazones, polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic bovine pigments, perylene pigments, indigo dyes, Organic pigments and dyes such as thioindigo dyes and methine squaric acid dyes 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. Pat. No. 4,123,270;
No. 247614, No. 4251613, No. 4251
No. 614, No. 4256821, No. 4260672
No. 4288596.

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, as disclosed in 4278747 and 4293628. etc. 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.

A multilayer photoconductor obtained by laminating a charge transport layer and a charge generation layer mainly composed of a charge generation material is more stable than other single layer photoconductors in terms of sensitivity and increase in 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 laminated 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 comprised of a layer containing a polycyclic bovine non-based pigment represented by the formula CI). .

The charge transport layer has the general formula (n) (wherein R1 and R2 are hydrogen atoms, halogen atoms,
Represents a nitro group, a substituted or unsubstituted 7-aryloxy group, or a substituted or unsubstituted 7-mino group, provided that R1 and R
At least one of 2 is a substituted amino group or an alkoxy group eR3 and R4 represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, provided that at least one of R3 and R4 is a substituted or unsubstituted alkyl group. It is a substituted 7-aryl group. Further, R3 and R4 may form a nitrogen-containing heterocycle, and R5R6R7 and R8 are hydrogen atoms, halogen atoms, nitro groups, substituted or unsubstituted alkyl groups, alkoxy group-substituted or unsubstituted aryloxy groups, The present invention is an electrophotographic photoreceptor characterized by comprising a layer containing a hydrazone compound represented by the following formula, which represents a substituted or unsubstituted acyl group or a substituted or unsubstituted 7-mino group.

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 that the thin film layer 1 has a thickness of, for example, 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, This is due to the need to generate charge carriers and to inject the generated charge carriers into the charge transport layer without being deactivated by recombination or trapping.

The charge generating material used in the present invention is a polycyclic 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 together with a suitable binder (or without a binder) on the substrate, or by forming a vapor deposited film using a vacuum vapor deposition apparatus. can be obtained by

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, polyvinylanthra7ane, and polyvinylpyrene. . Preferably polyvinyl butyral, polyarylate (bispheno-JL; condensation polymer of A and phthalic acid, etc.)
, polycarbonate, polyester, phenoxy resin,
Examples include insulating resins such as polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is
A content of 80% by weight or less, preferably 40% by weight or less 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 charge generation layer and undercoat layer described below.

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,
This can be carried out using a coating method such as a Mayer bar coating method, a blade coating method, a roller coating method, or a curtain coating method. Drying is
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 under ventilation.

The charge transport layer is electrically connected to the charge generation layer described above and is capable 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. It has a function. At this time, this charge transport layer may be laminated on the charge generation layer,
Moreover, it may be laminated thereunder.

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" includes a broad definition of "light rays" that includes gamma 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 capture 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 (11).

(In the formula, R1 and R2 are hydrogen atoms, halogen atoms,
Represents a nitro group, a substituted or unsubstituted 7-aryloxy group, or a substituted or unsubstituted 7-mino group, provided that R1 and R
At least one of 2 is a substituted amino group or alkoxy group. aR3 and R4 represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted 7-aryl group, provided that at least one of R3 and R4 is a substituted or It is an unsubstituted 7-aryl group. In addition, R3 and R4 may form a nitrogen-containing heterocycle.6 R5R6R7 and R8 are
Hydrogen atoms, halogen atoms, nitro groups.

Substituted or unsubstituted alkyl group, alkoxy group, substituted or unsubstituted 7-aryloxy group, substituted or unsubstituted acyl group, or substituted or unsubstituted 7-mino group) This hydrazone compound can be used as a charge transport substance. It meets the above conditions, especially sensitivity.

It has excellent properties in terms of durability.

Typical hydrazone compounds represented by the general formula (I) used in the present invention are illustrated in Table 1.

Table 1a 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 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 repeat 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 resin and polyacrylate.

polyester, polycarbonate, 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 coaching 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 (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.

It is also possible to provide a subbing layer having barrier and adhesive functions between the conductive layer and the photosensitive layer. The subbing layer is casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
It can be formed from acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 81O1 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 composed of 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 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. Should I fix this directly?

Alternatively, 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, 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 susceptible to deterioration due to ultraviolet rays, ozone, etc., dirt from oil, etc., scratches from metal chips, etc., 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 charge transport layer for the purpose of preventing abrasion.In order to form an electrostatic latent image on this protective layer, the surface resistivity must be 1011Ω or more. is desirable.

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.

Additionally, 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 from 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 ml of water) was coated on an aluminum cylinder using a coating method, and dried to form a coating amount of 1.0 g/m''0 subbing layer. 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 0.31L.
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 a dipping coating method and dried to form a charge transport layer. The film thickness at this time is
It was 12 wells.

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 v5).
jLuxe 5ec).

These results were as follows.

ve: -590 volts Vs: -580 volts El/2: 6. 2, uxasec Examples 2 to 5 1 in place of compound No. (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) E
l/21ux@5ec 2 2 5905755.9 3 3 5805706.6 4 4 5955856.2 5 5 6005906.8 Comparative Examples 1 to 6 The charge transport substances shown in Table 3 were used in place of the hydrazone compound used in Example 1. A photoreceptor was produced in exactly the same manner except for the following. Its charging characteristics are shown in Table 4.

Table 3 Comparative example Comparative charge Comparative charge transport material structural formula Comparative example
Comparative charge Comparative charge transport material structural formula transport material table 4 Comparative example Comparative charge Vo (-V) Vs (-V) E
l/2 transport substance NOlux*5ec 1 1 58G5557.8 2 2 5705457.4 3 3 5705507.7 4 4 5905758.6 5 5 5905707.5 6 6' 5805507.9 As is clear from the results of the examples and comparative examples In addition, it can be seen that the laminated photoreceptor of the present invention has extremely high sensitivity compared to the comparative example of photoreceptor movement 1 to cold and 6. Furthermore, images were produced 20,000 times using the photoconductors of Examples 1 to 3 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.

[Effects of the Invention] As is clear from the above, the present invention uses a specific polycyclic non-based pigment as a charge generation material in the charge generation layer and a specific hydrazone compound in the charge transport layer, thereby improving the conventional structure. This made it possible to provide a laminated electrophotographic photoreceptor with extremely high sensitivity compared to the previous one.

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) It consists of a layer containing a polycyclic quinone pigment represented by the general formula (II) (where R_1 and R_2 are hydrogen atoms, Indicates a halogen atom, a nitro group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted amino group, provided that R_
At least one of 1 and R_2 is a substituted amino group or an alkoxy group, and R_3 and R_4 represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. However, at least one of R_3 and R_4
One is a substituted or unsubstituted aryl group. Also R_
3 and R_4 may form a nitrogen-containing heterocycle. R_5R
_6R_7 and R_8 are hydrogen atoms, halogen atoms,
It represents 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 amino group. ) 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).