JPS61189552A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and to reduce residual potential after durability test by using a polycyclic quinone type pigment for an electrostatic charge generating layer and a specified pyrazoline deriv. for a charge transfer layer. CONSTITUTION:The charge generating layer formed together with the charge transfer layer on the conductive substrate of a laminate type electrophotographic sensitive body contains the polycyclic quinone type pigment represented by formula (1) and the charge transfer layer contains the charge transfer material of a pyrazoline deriv. represented by formula (2) in which R1, R2 are each alkyl or a residue forming a ring together with an N atom, and optionally same or different, and X is a pyridyl or quinolyl group optionally substd. by at least one alkyl or alkoxy group. It is preferred that the charge generating layer contains the charge generating material as much as possible in order to obtain sufficient light absorbance, and is formed into a thin layer, for example, <=10mum thick in order to inject generated charge carriers efficiently to the charge transfer layer. Since the charge transfer layer is limited to the upper thickness limit for transferring the charge carriers, it is impossible to make the layer too thick, and it is formed generally in a thickness of 5-30mum, general, and preferably, 8-20mum.

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an organic photoconductor, and more particularly to an electrophotographic photoreceptor having a charge transport layer and a charge generation layer. 2. Description of the Related 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 it was discovered that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed.
For example, organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene, carbazole, anthracene, pyrazolines, oxadiazoles,
hydrazones. Organic pigments and dyes such as low-molecular organic photoconductors such as polyarylalkane, tuthalocyanine pigments, azo pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and squaric acid methine dyes are used. 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 Patent No. 4123270, US Patent No. 424761
No. 4, No. 4251613, No. 4251614,
Same No. 4256821, Same No. 4260672, Same No. 4
No. 268596, No. 4278747, No. 4293
628, 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. 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 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 susceptible to crushing and increased residual potential after durability tests than other single layer photoconductors. Although it is advantageous, the nose is 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 and Action for Solving the Problems The above-mentioned object of the present invention is to form a two-layer structure on a conductive support, consisting of 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. This is achieved by using a polycyclic bovine non-based pigment of structural formula (1) in the charge generation layer and a pyrazoline compound represented by general formula (2) in the charge transport layer in the laminated electrophotographic photoreceptor having Ru. Further, a uni≧4:phosphorus compound used in the charge transport layer can be added to the charge generation layer, and the effect becomes even more remarkable. Further, the charge generation layer used in the present invention can be used as a single layer, or a layer in which a charge generation material and a charge transport material are mixed can be used as a single layer. 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. The charge generation layer is composed of a layer containing a polycyclic quinone pigment represented by structural formula (1), and the charge transport layer is a pyrazoline compound represented by general formula (2).

[In the formula, R,,R, is an alkyl group or a residue that forms a ring with a nitrogen atom, R1 and R2 may be the same or different, and X is an unsubstituted pyridyl group or quinolyl group. or a pyridyl group or quinolyl group substituted with at least one alkyl group or alkoxy group. Representative compounds of the pyrazoline compound represented by the general formula (2) used in the present invention are illustrated below. In the laminated electrophotographic photoreceptor of the present invention, the charge generation layer contains as much of the above charge generation material as possible in order to obtain sufficient absorbance, and efficiently injects the generated charge carriers into the charge transport layer. For example, a thin film layer, e.g. 10
It is desirable to form a thin film layer having a thickness of less than 1 g, preferably 0.01 to 1 l. 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 injected into the charge transport layer without being deactivated by recombination or trapping. This is due to the need to do so. The charge generation layer can be formed by coating the above-mentioned polycyclic quinone pigment and, if necessary, a charge transporting material together with a suitable binder (or without a binder) on the substrate, and can also be formed by coating the deposited film with a vacuum evaporation device. can be obtained by forming . When a charge transporting material is added to the charge generation layer, the amount of the pyrazoline compound is preferably 10 times or less (by weight), preferably 0.01 to 1 times (by weight) the charge generation material. The binder that can be used in 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 (
polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol and insulating resins such as polyvinylpyrrolidone. 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 above-mentioned charge transport layer and undercoat layer. Specific organic solvents include methanol, ethanol,
Alcohols such as Impropatool, ketones such as 7setone, methyl ethyl ketone, cyclohexanone, N, N
-dimethylformamide, N. Amides such as N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol methyl 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 coach ink method, a roller coach ink method, or a curtain coating method. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying can be carried out at a temperature of 30 to 200°C for a period of time ranging from 5 minutes to 2 hours, either still or under blowing air. 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 or under the charge generation layer. However, it is desirable that the charge transport layer is laminated on the charge generation layer. 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. It includes a broad definition of "light ray" that includes radiation, visible light, near infrared rays, infrared rays, far infrared rays, etc. 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. When the charge transport material does not have a film formation, a film can be formed by selecting an appropriate binder. Examples of resins that can be used as binders include: Acrylic resin, polyarylate, polyester. Polycarbonate, polystyrene, acrylonitrile
Styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacryl 7mide, polyamide,
Examples include insulating resins such as chlorinated rubber, and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. 1TI + 7 Takashi 2) 6-~II-Tokubetsu t □] 吃 yo tt → :, -TO 1TI + 7 Takashi 2) Since there is a It is not possible to increase the thickness of the film. Generally it is 5 to 30 tt, but the preferable range is 8 to 30 tt.
It is 20μ. When forming the charge transport layer by coating, the above-mentioned J"+ coating method can be used. A photosensitive layer consisting of such a laminated structure of a charge generation layer and a charge transport layer is a conductive layer. The conductive layer is provided on a base having conductivity, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, Gold, platinum, etc. can be used, and in addition, plastics (for example, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate (acrylic resin, polyfluorinated ethylene, etc.), conductive particles,
A substrate in which plastic is coated with (for example, carbon black, silver particles, etc.) together with a suitable binder, a substrate in which plastic or paper is impregnated 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 consists of 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, aluminum oxide, etc. The thickness of the subbing layer is 0.1 to 40 g, preferably 0.1 to 40 g.
3uL 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 is made of an electron transporting material, it is necessary to charge the surface of the charge transport layer to 77 F after charging. When exposed to light, 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 a decrease in surface potential and creating an electrostatic contrast with the unexposed area. . A visible image can be obtained by developing the static %lC1 image thus produced 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 made of a hole transport material, it is necessary to charge the surface of the charge transport layer negatively, and when exposed to light after charging, the genuine tag generated in the charge generation layer is 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 about one surface type, and an electrostatic contrast is created 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 used in the present invention is subject to deterioration due to ultraviolet rays, ozone, etc., dirt due to oil, etc., scratches due to 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 for the purpose of preventing scratching. In order to form static M and WJ images on this protective layer. It is desirable that the surface resistivity is 10''Ω or more. The protective layer used in the present invention is made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene. −
It can be formed by applying a solution prepared by dissolving a resin such as an acrylic acid copolymer or a styrene-7crylonitrile copolymer in a suitable organic solvent onto the photosensitive layer and drying it. Moreover, additives such as ultraviolet absorbers can be added to the resin liquid. The thickness of the protective layer is generally in the range of 0.805 to 20 g, preferably 0.2 to 5 g. Example 1 An ammonia aqueous solution of casein (casein 11, 2 g, 28% ammonia 2, F 1 g, water 222 ml) was applied by dip coating to an aluminum cylinder, and dried to give a coating weight of 1.0 g/m. A subbing layer was formed. Next, 1 part by weight of the charge-generating material of structural formula (1), 1 part by weight of butyral resin (Nislec BM-2, manufactured by Sekisui Chemical Co., Ltd.), 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 0.3 l. Next, 1 part of the compound of pyrazoline compound example (1) described in 1i7N, 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 (initial potential Va) 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 v7). Sensitivity was evaluated by measuring the exposure amount (E I/21ux, +ec) required to attenuate the potential V after dark decay to 1/2. These results were as follows. V: -580V, V: -570V. El/2:5, 6 lut, sea Examples 2 to 10 Except for using pyrazoline compound examples (2) to (10) in place of pyrazoline compound example (1) used in Example 1, A photoreceptor was created in exactly the same manner as in Example 1,
The characteristics of this photoreceptor were measured. These results are shown in Table 1. Table 1 ′i! JJ kajuE billion vo-vv3-vEl12
lu heavy, 5ec2 (2) 590580 8.4
3 (3) 580570 5.54 (4)
5805Ei5 5.75 (5) 57051
110 8.16 (ill) 575580 1
11.3? (7) 575565 5.88
(8) 580570 8.59 (!3) 5
90575 8.710 (10) 590580
8.3 Comparative Examples 1 to 6 The following Table 2 was used instead of the pyrazoline compound used in Example 1.
Photoreceptors of Comparative Examples 1 to 6 were prepared using the charge transport materials (1) to (6) shown in Table 1, but in the same manner as above. Table 2 Structural Formula Table 3 shows the charging characteristics of the above photoreceptor. Table 3 1 (1) 575 550 7.72 (2
) 570 550 7.53 (3) 5
80 555 8.14 (4) 590 57
0 8.85 (5) 580 560 8.3
8 (8) 585 585 7.9 Effects of the Invention As is clear from the above results, the laminated photoreceptor of the present invention has extremely high sensitivity compared to the photoreceptors of Comparative Examples 1 to 6. I understand that. Furthermore, the photoreceptors of Examples 1 to 3 were used as NP manufactured by Canon Co., Ltd.
Image production was repeated 200 times using a -1502 copying machine. 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.

Claims (1)

[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 is a polycyclic quinone pigment having the structural formula (1) ▲ Numerical formula, chemical formula, table, etc. ▼(1) A pyrazoline compound whose charge transport layer is represented by the general formula (2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(2) [In the formula, R_1 and R_2 are alkyl groups or a residue that forms a ring with a nitrogen atom, and R_1 and R_2 may be the same or different. X is an unsubstituted pyridyl group, a quinolyl group, or a pyridyl group or a quinolyl group substituted with at least one alkyl group or alkoxy group.