JPS628159A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a laminate type electrophotographic sensitive body high in sensitivity and extremely low in residual potential even after a durability test by forming a layer containing a specified quinone type pigment as an electrostatic charge generating layer and a layer containing a hydrazone type compound as a charge transfer layer. CONSTITUTION:The charge generating layer contains the polycyclic quinone type pigment represented by structural formula (I) and the charge transfer layer contains the hydrazone type compound represented by general formula (II). The charge generating layer can be formed by coating a substrate with said pigment, and when needed, the charge transfer layer is electrically connected with the charge generating layer, and has a function of receiving charge carriers injected from the charge generating layer in the presence of an electric field and transferring them to the surface. The hydrazone type compound to be used as the charge transfer material is typified by formulae (1)-(3), and when the charge transfer material is added to the charge generating layer, it is proper to add it in an amount of 1-100pts.wt. per 100pts.wt. of the charge generating material from the view points of high sensitivity, low residual potential, and stability against repeated uses.

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 generation layer and a charge transport layer.

[Conventional Technique #i] Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been known. On the other hand, since the discovery that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. Low-molecular organic photoconductors and phthalocyanine pigments such as polymers, carbazole, anthracene, pyrazolines, oxadiazoles, human)sins, and aryl alkanes.

Organic pigments and dyes such as azo pigments, cyanine pigments, polycyclic bovine pigments, perylene pigments, indigo dyes, thioindigo dyes, and methine square phosphate 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, US Pat. No. 4,123,270;
Same No. 4247614, Same No. 4251613, Same No. 4
No. 251614, No. 4256821, No. 4260
No. 672, No. 4268596, No. 4278747
Electrophotographic photoreceptors using disazo pigments 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 No. 4293628, etc., are known. It is being 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 that the sensitive wavelength range can be freely controlled by selection.

A multilayer photoreceptor 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 photoreceptors in terms of sensitivity and increase in residual potential after durability tests. However, it was still not at a sufficient level.

[Problems to be Solved by the Invention] An object of the present invention is to improve the above-mentioned drawbacks and to provide a laminated electrophotographic photoreceptor with high sensitivity and extremely low residual potential even after a durability test.

[Means for Solving the Problems 1 Effect] The present invention achieves the above-mentioned object by forming 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 charge generation layer and a specific hydrazone compound in the charge transport layer in a laminated electrophotographic photoreceptor having two layers.

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, wherein the charge generation layer is a layer containing a polycyclic bovine non-based pigment of structural formula (I). .

The charge transport layer is a hydrazone compound represented by the general formula (II) (wherein R1 and R, Jf hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, alkoxy group, substituted or unsubstituted aryloxy group or substituted amino group, provided that at least R,2:R2
□One is a substituted amino group or alkoxy group,
R1 and R are substituted or unsubstituted alkyl groups or
At least one of 1R2 and R4 is a substituted or device 1 represents a substituted or unsubstituted 7-aryl group, provided that it is a substituted 7-aryl group, and even if R7 and R complete a nitrogen-containing heterocycle, Often, Rt, R, and RP represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted amine group,
The electrophotographic photoreceptor is composed of a layer containing (n represents O or 1).

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 μl or less, preferably 0.01 to 1 μl. This means that most of the incident light is absorbed by the charge generation layer and a large amount of 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 (trasving).

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

The charge generation layer can be formed by coating the above-mentioned pigment and, if necessary, a charge transport 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. can be obtained by 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 polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.)
, polycarbonate, polyester, phenoxy resin,
polyvinyl acetate, acrylic resin, polyacrylamide,
polyamide, polyvinylpyridine, 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 8
A content of 0% by weight or less, preferably 40% by weight or less is suitable. Solvents that dissolve these resins vary depending on the type of resin, and are preferably selected from those that do not dissolve the underlying charge transport layer or subbing layer.Specific organic solvents include methanol, ethanol, and isopropanol. Alcohols such as tools, ketones such as acetone, methyl ethyl ketone, cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, etc. ethers, esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene, or benzene, toluene, and xylene.

Aromatic compounds such as licroin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using coating methods such as Mayer coating, bar coating, blade coating, roller coating, and curtain coating.

Drying is preferably carried out by drying to the touch at room temperature and then heating. Drying by heating is performed at a temperature of 30 to 200°C for 5 minutes to
It can be carried out stationary or under draft for a period of time in the range of 2 hours.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and taking charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. have. In this case, this charge transport layer may be laminated over the charge generation layer, or may be laminated under it, and may be a substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as a charge transport material). ) 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 the broad definition of "light rays" including γ-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 trap each other, resulting in a decrease in sensitivity.

The charge transport material used in the present invention is a hydrazone compound represented by the general formula (H).

In the formula, R1 and R2 are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or an alkoxy group.

Substituted or unsubstituted 7-aryloxy group or substituted amino group i, provided that at least one of CR2 and R2 is a substituted amino group or alkoxy group.

R3 and R4 represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted 7-aryl group, provided that RJ and R
At least one of 4 is a substituted or unsubstituted 7-aryl group, and R3 and Rgin may complete a nitrogen-containing heterocycle, Ryo, R,, R? , BiR? represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted amine group, and n represents 0 or 1.

This hydrazone compound satisfies the above-mentioned conditions as a charge transport material, and has excellent properties particularly in terms of sensitivity and durability.

Typical hydrazone compounds used in the present invention are illustrated below.

Further, in the present invention, the above-mentioned hydrazone compound used in the charge transport layer can be added to the charge generation layer.
The sensitizing effect becomes even more remarkable. In the charge generation layer,
When a charge transporting material is added, the hydrazone compound is 10 times or less (weight ratio) of the charge generating material, preferably 0.0
A ratio of 1 to 1 times (weight ratio) is appropriate from the viewpoints of high sensitivity, low residual potential, and repeated 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 resins, polyarylates,
Insulating resins such as polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, 7-crylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N-vinylcarbazole, polyvinylanthracene , organic photoconductive polymers such as polyvinylpyrene.

The charge transport layer has a limit to its ability to transport charge carriers.
Therefore, the film thickness cannot be made thicker than necessary. Generally, the thickness is 5 to 30 g, but the preferable range is 8 to 30 g.
It is 20JL. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photosensitive layer having such an aM structure of a charge generation layer and a charge transport layer is provided on a substrate having a conductive layer. Examples of the substrate having a conductive layer include those whose substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc,
Stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used, and in addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. can be coated by vacuum evaporation method. A plastic having a formed layer (e.g. polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoroethylene, etc.), conductive particles (e.g. carbon black, silver particles, etc.) are added to the main body of the plastic with a suitable binder. A substrate coated with a conductive material, a substrate made of plastic 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. The undercoat layer is casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, The thickness of the undercoat layer, which can be formed from aluminum oxide etc., is 0.1 to 40.
A suitable range is 0.1 to 3 wells, preferably 0.1 to 3 wells.

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 and neutralize the positive charge, resulting in attenuation of the surface potential and an electrostatic contrast between it and the unexposed area. occurs. A visible image is 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 methods, and are not limited to specific ones or methods.

On the other hand, when the charge transport material is a hole transport material, the surface of the charge transport layer must be negatively charged.

After charging, when exposed to light, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, resulting in attenuation of one surface type, and the gap between the exposed area and the unexposed area is injected into the charge transport layer. Electrostatic contrast occurs. 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., 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 for the purpose of preventing scratching.In order to form an electrostatic latent image on this protective layer, a surface resistivity of 101 is required.
The protective layer used in the present invention, which is preferably 1Ω or more, is made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene.
The photosensitive layer can be formed by dissolving a resin such as butadiene copolymer, styrene-acrylic acid copolymer, styrene-7crylonitrile copolymer, etc. in a suitable organic solvent and drying the solution. Moreover, additives such as ultraviolet absorbers can be added to the resin liquid. At this time, the film thickness of the protective lIN is generally O,OS~20pL, preferably 0.2~20pL.
It is within the range of 5IL.

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

Example 1 A 7 ammonia aqueous solution of casein (11.2 g of casein, 28% Ig of ammonia, 2 g of water) was placed on an aluminum cylinder.
22 ml) was applied by dip coating and dried to form a subbing layer with a coating weight of 1.0 g/a+.

Next, 1 part by weight of a charge generating material of structural formula (I).

Butyral resin (Eslec BM-2% manufactured by Sekisui Chemical ■)
1 part 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 was 0.3%.

Next, 1 part by weight of the above-mentioned hydrazone compound example (1), 1 part by weight of polysulfone (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 was 12 mm.

A corona discharge of 15 KV was applied to the photoreceptor thus prepared. The surface potential at this time (initial potential V6) was measured. Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay Vr). eSensitivity is the amount of exposure required to attenuate the potential (2) to 1/2 after dark decay. (E 1/
21ux, 5ec).

These results were as follows.

Vo: -580V, V): -570V, E 1/
2:3.4 Iux, sec Examples 2 to 5 In addition to using hydrazone compound examples (2) to (5) in place of the hydrazone compound example (1) used in Example 1, t1°, Examples A photoreceptor was prepared in exactly the same manner as in i. The characteristics of this photoreceptor were measured.

These results are shown below.

LLf21 good standing 1va-v■-vEl/21u! 5e
c2 (2) 570 580 3.3
3 (3) 580 570 3.74
(4) 590 580 3.55
(5) 590 585 3.9 Comparative example 1~
6 The photoreceptors of Comparative Examples 1 to 6 were prepared in exactly the same manner except that the following comparative charge transport substances (1) to (El) were used in place of the hydrazone compound used in Example 1, and the charged Characteristics were measured.

C Engineering H.

Charging characteristics 1 (1) 590 585 4.3
2 (2) 580 580 4.8
3 (3) 585 550 5.0
4 (4) 810 800 8.2
5 (5) 585 555 5.7
6 (8) a70 5H4, 4 As is clear from the results of Examples and Comparative Examples, the M type photoreceptor of the present invention has extremely high sensitivity than the photoreceptors of Comparative Examples 1 to 6. I can see that it was done. Furthermore, the photoreceptors of Examples 1 to 5 were copied using fi (NP-150 manufactured by Canon Co., Ltd.).
Image generation was repeated 20,000 times using 2).

As a result, good quality images were obtained even after repeating 20,000 times with each photoreceptor, and the electrophotographic photoreceptor of the present invention
It can be seen that the durability is also extremely excellent.

[Effects of the Invention] As is clear from the above, the present invention uses a specific polycyclic bovine non-based pigment as a charge-generating material in the charge-generating layer, and uses a specific hydrazone-based compound in the charge-transporting layer i. 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 electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, the charge generation layer consists of a layer containing a polycyclic quinone pigment of structural formula (I), and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) Hydrazone compounds whose charge transport layer is represented by the general formula (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) (In the formula, R_1 and R_2 are hydrogen atoms , halogen atom,
Represents a substituted or unsubstituted alkyl group, alkoxy group, substituted or unsubstituted aryloxy group, or substituted amino group, provided that at least one of R_1 and R_2 is a substituted amino group or alkoxy group, and R_3 and R_
4 represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, provided that at least one of R_3 and R_4 is a substituted or unsubstituted aryl group, and R_3 and R_4 complete a nitrogen-containing heterocycle. R_5, R_6, R_7 and R_8 represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted amino group, and n is 0 or 1. An electrophotographic photoreceptor comprising a layer containing: (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by the general formula (II).