JPS627054A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and to improve durability by incorporating a specified polycyclic quinone type pigment in an electrostatic charge generating layer and a specified hydrazone type compound in a charge transfer layer. CONSTITUTION:The charge generating layer containing the polycyclic quinone type pigment represented by formula I and the charge transfer layer containing the hydrazone type compound represented by formula II (each of R1, R2, R5-R8 is H, halogen, or optionally substituted alkyl, alkoxy, optionally substituted aryloxy, or optionally substituted amino; each of R3, R4 is optionally substituted alkyl or such aryl, and at least one of them is optionally substituted aryl, and each may combine with each other to form an N-containing hetero ring; and n is 0 or 1) are laminated on a conductive substrate. Such a structure permits the obtained photosensitive body to be enhanced in photosensitivity and further, the addition of said hydrazone type compound of formula II to the charge generating layer permits the sensitizing effect to be made more remarkable, residual potential to be lowered, and stability against repeated uses to be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 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, such as organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene. , carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, polyaryl alkanes, and other low-molecular organic photoconductors, phthalocyanine pigments, azo pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments, and indigo dyes. Organic pigments and dyes such as , thioindigo dyes and squaric acid methine dyes are known. In particular, organic pigments and dyes that have photoconductivity are easier to synthesize than inorganic materials, and the range of options for selecting compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded. A number of photoconductive organic pigments and dyes have been proposed, e.g., U.S. Pat. No. 4,123,270;
No. 7614, No. 4251613, No. 425161
No. 4, No. 4256821, No. 4260672,
Same No. 4268596, Same No. 4278747, Same No. 4
As disclosed in Japanese Patent No. 293,628, electrophotographic photoreceptors are known that use a photoconductive disazo pigment 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 they have extremely high productivity.
It has the advantage that it can provide an inexpensive photoreceptor, and the sensitive wavelength range can be freely controlled by selecting the organic pigment.

A multilayer photoconductor 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 photoconductors in terms of sensitivity and increased 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 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 multilayer electrophotographic photoreceptor having two layers.

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, wherein the charge generation layer is a layer containing a polycyclic quinone pigment represented by structural formula (I). , a hydrazone compound whose charge transport layer is represented by the general formula (II) (wherein R9 and R2 are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or an alkoxy group).

Represents a substituted or unsubstituted 7-aryloxy group or a substituted amino 7 group, provided that at least one of R and R2 is a substituted amino group or alkoxy group, and R3 and R4 are substituted or unsubstituted alkyl groups or substituted or an unsubstituted aryl group, provided that at least one of Machi and Inu is a substituted or unsubstituted 7-aryl group, and R
3 and R, -c to complete the nitrogen-containing heterocycle < , Rj
, R,, R2 and Rθ 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, and n represents 0 or l.) It is composed of an electrophotographic photoreceptor characterized in that it consists of a layer containing.

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 thickness of less than 10 μm, preferably 0.01 to 1 μm. 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.

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.),
Examples include insulating resins such as polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less. 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 in-propyl alcohol. Alcohols such as tools, ketones such as acetone, methyl ethyl ketone, cyclohexanone, N, N-dimethylformamide,
Amides such as N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, dichloroethylene,
Aliphatic halogenated hydrocarbons such as carbon tetrachloride and trichloroethylene, or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene and 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 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. At this time, this charge transport layer may be laminated on the charge generation layer, and
The material that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport material), which may be laminated thereunder, is substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. It is preferable that there be.

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 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 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.

It represents a substituted or unsubstituted aryloxy group or a substituted amino group, provided that at least one of the two is a substituted amino group or an alkoxy group.

R7 and R4 represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, provided that RJ and R
At least one of 4 is a substituted or unsubstituted 7-aryl group, and R3 and R4 may complete a nitrogen-containing heterocycle, and R1, RL, R7, and R are hydrogen atoms, halogen atoms, substituted or unsubstituted alkyl group, alkoxy group, substituted or unsubstituted 7-aryloxy group, or substituted amino 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, and the sensitizing effect thereof becomes even more remarkable. When a charge transporting material is added to the charge generation layer, the hydrazone compound is 10 times or less (weight ratio) of the charge generation material, preferably 0.0
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,
Polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide.

Insulating resins such as polyamide and chlorinated rubber, or poly-N-vinylcarbazole, polyvinylanthracene,
Organic photoconductive □polymers such as polyvinylpyrene 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. Generally, the thickness is 5 to 30 IL, but the preferred range is 8 to 20 μL. 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, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used, and in addition, aluminum, lluminium alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. can be used by vacuum evaporation. Plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoroethylene, etc.), conductive particles (e.g., carbon black, silver particles, etc.) that soften the formed layer are added to the plastic together with a suitable binder. A substrate coated on a substrate, a substrate obtained by impregnating a plastic or paper with conductive particles, a plastic having 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 subbing layer is casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, J-
610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The thickness of the undercoat layer is 0.1 to 40
JL, preferably 0.1 to 3 JL.

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 in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, causing a decrease in surface potential and the generation of static electricity between the exposed area and the unexposed area. Contrast 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 the surface potential and a gap between the exposed area and the unexposed area. 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 abutting 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 scratches and abrasion.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 0 or more, and is made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimad, polyarylate, polyurethane, styrene-butadiene copolymer, styrene □-acrylic acid copolymer, A solution prepared by dissolving a resin such as styrene-acrylon (styrene-acrylon) tolyl copolymer in an appropriate organic solvent is applied onto the photosensitive layer, dried, and shaped.
Can be done. In addition, adding ultraviolet absorbers, etc. to the resin liquid.
□ Additions can be added. At this time, the film thickness of the protective layer is generally i:o, 05 to 20 IL, preferably 0.2 to 5
This is within the IL range.

The present invention will be explained below according to examples.

Example 1 An ammonia aqueous solution of casein (2 g of casein 11, 1 g of 28% ammonia, 222 ml of water) was coated on an aluminum cylinder by dip coating and dried to form a subbing layer with a coating weight of 1.0 g/m. was formed.

Next, 1 part by weight of the charge-generating material of structural formula (I), 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 generation layer. The film thickness was 0.31L.

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,
1 on Wta plane! l! It was pressed and dissolved.

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 l.

A corona discharge of 15 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 V,).

Sensitivity was evaluated by measuring the amount of exposure (E 1/21ux, 5 eC) required to attenuate the potentials V and H after dark decay to 1/2.

These results were as follows.

V,: -570V, V,: -560V, E 1/
2:3, 6 lux, sec Examples 2 to 5 Example 1 except that hydrazone compound examples (2) to (5) were used in place of hydrazone compound example (1) used in Example 1. A photoreceptor was prepared in exactly the same manner as described above, and the characteristics of this photoreceptor were measured.

These results are shown below.

"1JJl! Audit lV -V V -V E 1
/2 lux 5ec2 (2) 575
585 3.43 (3) 580 57
0 3.94 (4) 585 575
3.85 (5) 595 585 4
．． 4 Comparative Examples 1 to 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 (6) were used in place of the hydrazone compound used in Example 1. were prepared and their charging characteristics were measured.

2Hs ■ Charging characteristics 1 (1) 550 500 5.4
2 (2) 530 495 5.0
3 (3) 500 485 5.7
4 (4) 580 515 7.1
5 (5) 580 580 8.2
6 (6) 570 580 8.9
Results of Examples and Comparative Examples 2!11 It is clear that the laminated photoreceptor of the present invention has extremely high sensitivity compared to the photoreceptors of Comparative Examples 1 to 6. I understand. Further, images were produced on the photoreceptors of Examples 1 to 5 20,000 times using a copying machine (manufactured by Canon Inc., NP-1507).

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 a specific hydrazone-based compound in the charge-transporting layer. This made it possible to provide a laminated electrophotographic photoreceptor with extremely high sensitivity compared to the previous one.

Patent applicant: Canon Corporation.

Representative Patent Attorney Yu Kano

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 represent a nitrogen-containing heterocycle. It may be completed, R_5, R_6, R_7 and R_8 are hydrogen atoms,
It represents 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 represents 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 formula (II).