JPS622264A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a laminate type electrophotographic sensitive body having very high sensitivity by using a specified polycyclic quinone pigment as a charge generating material in a charge generating layer and a specified hydrazone compound in a charge transferring layer. CONSTITUTION:A charge generating layer is made of a layer contg. a polycyclic quinone pigment represented by formula I and a charge transferring layer is made of a layer contg. a hydrazone compound represented by formula II. The charge generating layer contains the charge generating material to the utmost limit so as to obtain satisfactory absorbance, and the layer is preferably formed as a thin film of 0.01-1mum thickness so as to efficiently implant generated charge carriers into the charge transferring layer. The charge generating layer can be formed by mixing the pigment represented by the formula I with a proper binder, adding a charge transferring material as required and coating the mixture on a substrate. Since there is a limit in the capacity of the charge transferring layer to transfer charge carriers, the thickness of the layer can not be made larger than the necessary thickness. The preferred thickness is 8-20mum.

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.

[Prior Art] 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 such as carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, polyaryl alkanes, phthalocyanine pigments, azo pigments, cyanine pigments, polycyclic bovine pigments, perylene pigments, indigo dyes Organic pigments and dyes such as , thioindigo dyes and methine squarate 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 been expanded.
Numerous photoconductive organic pigments and dyes have been proposed, such as U.S. Pat. Nos. 4,123,270 and 4,247,614
No. 4251613, No. 4251614, No. 4256821, No. 42606-72, No. 4
No. 268596, No. 4278747, No. 4293
As disclosed in No. 628, etc., 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. An electrophotographic photoreceptor using such an organic photoconductor can be produced by coating by appropriately selecting the binder 1, so it is possible to provide an extremely productive and inexpensive photoreceptor. It has the advantage of being able to freely control the photosensitive liquid wall.

The A-layer type photoreceptor, which is obtained by layering a charge transport layer and a charge generation layer mainly composed of a charge generation material, has higher sensitivity and higher residual potential after durability tests than other single-layer photoreceptors. Although it is advantageous, it is 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 and effects for solving the problems] The present invention achieves the above 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 bovine non-based 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 invention provides an FF single-layer type 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 non-containing pigment represented by structural formula (1). , □ The charge transport layer is a 3-drazo compound represented by the general formula (II)
□N-based compound 7\ (II) R engineering R1 (wherein R and RL are a hydrogen atom, a halogen atom, a nitro group, an alkoxy group, a substituted or unsubstituted 7-aryloxy group, or a substituted or unsubstituted amino group) , provided that at least one of R1 and R2 is a substituted amine group or an alkoxy group, R3 and R4 are a substituted or unsubstituted alkyl group or a substituted or unsubstituted 7-aryl group, provided that RJ and R At least one of them is a substituted or unsubstituted aryl group, and R3 and R may complete a nitrogen-containing heterocycle, and R, R, R2 and R1 are hydrogen atoms, halogen atoms, 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 7-mino group). It consists of an electrophotographic photoreceptor.

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 film thickness of Lop or less, preferably 0.01 to IJL. This means that most of the incident light is absorbed by the charge generation layer and many charges are generated. generation of carriers, and recombination and capture of generated charge carriers (
This is due to the need to inject into the charge transport layer without being deactivated by traps.

The charge generating material used in the present invention is a polycyclic bovine non-based 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 device. 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 (111 polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, Examples include insulating resins such as 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. 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 impropatol. alcohols such as acetone, methyl ethyl ketone, ketones such as 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 quasi-ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, benzene, toluene, xylene, ligroin, monochlorobenzene, Aromatics such as dichlorobenzene 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 preferably carried out by drying to the touch at room temperature, followed by heat drying. Heat drying can be carried out at a temperature of 30 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 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 on the charge generation layer (or a substance that transports the charge transport material (hereinafter simply referred to as charge transport substance) which may be laminated under the charge generation layer). , it is preferable that the charge generation layer is substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive.

The term "r@electromagnetic waves" as used herein includes the broad definition of "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 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 the general formula (1).

(In the formula, R1 and R represent a hydrogen atom, a halogen atom, a nitro group, an alkoxy group, a substituted or unsubstituted arylene group, or a substituted or unsubstituted amino group, provided that R
At least one of 7 and R is a substituted amine group or an alkoxy group, and R3 and R+ represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, provided that at least one of R5 and R One is a substituted or unsubstituted 7-aryl group, and R3 and R, -r
The nitrogen-containing heterocycle may be completed, R, r, R,, R2
and R? represents a hydrogen atom, a halogen 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 amino group)
.

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

It has excellent properties in terms of durability.

Representative examples of the hydrazone compounds used in the present invention are shown below.

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,
The sensitizing effect becomes even more remarkable. Trt, when a charge transport material is added to the charge generation layer, the hydrazone compound is 10 times or less (weight ratio) of the charge generation material, preferably 0.
．． 01 to 1 times (weight ratio) is suitable from the viewpoint of high sensitivity, low residual potential, and repetition stability. To form a charge transport layer containing a hydrazone compound, a coating can be formed by selecting an appropriate binder. Resins that can be used as binders include, for example, acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, etc. Examples include insulating resins and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally, the thickness is 5 to 30 JL, but the preferred range is 8 to 20 JL. 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. 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, moritaden, 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 layer of plastic (e.g. polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoroethylene, etc.) with a formed layer, conductive particles (e.g. carbon black, silver particles, etc.) on top 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, co-in nylon, alkoxymethylated nylon, etc.), polycarbonate, It can be formed from gelatin, aluminum oxide, etc. The thickness of the undercoat layer is 0.1 to 40J.
L, preferably 0.1 to 3 JL is appropriate.

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, and then visually imaged 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, it is necessary to charge the surface of the charge transport layer negatively, 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 charge, resulting in an attenuation of the surface potential and an electrostatic contrast with 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., 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 10" is required.
The protective layer used in the present invention is preferably made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic edge copolymer, styrene. A solution prepared by dissolving a resin such as acrylonitrile fubolymer in an appropriate organic solvent is applied onto the photosensitive layer.
Can be formed by drying. 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 to 20 pL, preferably 0.2 to 20 pL.
It is in the range of 5 pL.

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

Example 1 An 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 method and dried to a coating amount of 1. A subbing layer of Og/m was formed.

Next, 1 part by weight of the charge-generating material of structural formula (L), 1 part by weight of butyral resin (Eslec BM-2, manufactured by Tsukiki Kagaku ■), 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,
The mixture was stirred and dissolved using a stirrer.

This liquid was applied onto the charge generation layer by dip coating and dried to form a charge transport layer.

The radius thickness was 13JL.

A corona discharge of 13 KV was applied to the photoreceptor thus prepared. The surface potential (initial potential Vo) at this time was measured. Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay field).

Sensitivity was evaluated by measuring the exposure fit (E 1/21ux, 5ee) required to attenuate the outside potential to 1/2 after dark decay.

These results were as follows.

V,: -610V, V,: -6O0V, E I/2
:5, Olux, secExamples 2 to 5 Completely the same as Example 1 except that the hydrazone compound example (1) used in Example 1 was replaced with humanrecin compound examples (2) to (5), respectively. A photoreceptor was prepared in a similar manner, and the characteristics of this photoreceptor were measured.

These results are shown below.

笈舅Jsimilar beans 1V, +I-V V-V E 1/2
tug 5ee2 (2) 595 585
4.83 (3) 585 570
4.94 (4) eoo 585 4
．． 75 (5) 620 810
5.3 Comparative Examples 1 to 6 The photosensitive materials of Comparative Examples 1 to 6 were prepared in exactly the same manner except that the following comparative charge transport substances (1) to (6) were used in place of the hydrazone compound used in Example 1. They created a body and measured its charging characteristics.

C engineering H5- Charging characteristics 1 (1) Boo 575 8
．． 22 (2) 590 565 8
．． 03 (3) 595 570 8
．． 84 (4) 610 580 7
．． 45 (5) 585 555 7
．． 16 (6) 580
555 6.8 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 of . Further, images were produced 20,000 times using the photoconductors of Examples 1 to 5 using a copying machine (NP-1502, manufactured by Canon Inc.).

As a result, good quality images were obtained even after repeating the test 20,000 times with each photoreceptor, indicating 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 quinone pigment as a charge generation material in the charge generation layer and a specific hydracin compound in the charge transport layer. This makes it possible to provide an edge layer type electrophotographic photoreceptor with extremely high sensitivity compared to conventional ones.

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 atoms,
It represents a nitro group, an alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted amino group, provided that at least one of R_1 and R_2 is a substituted amino group or an alkoxy group, and R_3 and R_4 are substituted or represents an 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,
Also, R_3 and R_4 may complete a nitrogen-containing heterocycle,
R_5, R_6, R_7 and R_8 are hydrogen atoms, halogen atoms, nitro groups, substituted or unsubstituted alkyl groups,
1. An electrophotographic photoreceptor comprising a layer containing an alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted amino group. (2) The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a hydrazone compound represented by formula (II).