JPS61179452A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and durability by incorporating a specified violanthrone deriv. and a ketazine deriv. in a photosensitive layer formed on a conductive substrate. CONSTITUTION:The photosensitive layer formed on the conductive substrate contains the violanthrone deriv. represented by formula I, and the ketazine deriv. represented by formula II in which each of R1, R2, R3, and R4 is alkyl, aralkyl, or aryl, and a pair of R1 and R2, a pair of R3 and R4 each may form a cyclic amino group together with the combined N atom, or the electrostatic charge generating layer of a functionally separated photosensitive body contains the deriv. of formula I and the charge transfer layer contains the deriv. of formula II, thus permitting the photosensitive body contg. both in the single photosensitive layer or in the laminated layers to be enhanced in photosensitivity and small in residual potential even after repeated cycles of image formations, and superior in durability, and accordingly, a good image to be obtained even after a large number of repeated cycles of copying.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electrophotographic photoreceptor.

[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 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, polyvinylanthracene, carbazole,
Low-molecular organic photoconductors such as anthracene, pyrazolines, oxadiazoles, hydrazones, polyarylalkanes, 7-talocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo Organic pigments and dyes such as dyes or methine squarate dyes are known. In particular, organic pigments and dyes with 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.
Many photoconductive organic pigments and dyes have been proposed. For example, U.S. Patent No. 4123270, U.S. 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 selecting an appropriate binder, making it possible to provide photoreceptors with extremely high productivity and low cost. This has the advantage that the sensitive wavelength range can be freely controlled. However, electrophotographic photoreceptors having a single photosensitive layer are unsatisfactory in terms of sensitivity and increase in residual potential after durability tests. Although the laminated type photoreceptor obtained by laminating the photoreceptors is more advantageous than the single layer type photoreceptor in the above points, it is still not at a sufficient level.

[Purpose and outline of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned conventional drawbacks and to provide an electrophotographic photoreceptor with high sensitivity and extremely low residual potential even after a durability test.

The above object is achieved by the present invention, which has a photosensitive layer comprising a violanthrone derivative represented by the following formula [■] and a ketazine compound represented by the following general formula [■] on a conductive support. In an electrophotographic photoreceptor (hereinafter referred to as a single-layer electrophotographic photoreceptor of the present invention) or an electrophotographic photoreceptor having a charge generation layer and a charge transport layer on a conductive support, the charge generation layer has the following formula CI ) The electrophotographic photoreceptor of the present invention (hereinafter referred to as This is achieved by the layered electrophotographic photoreceptor of the present invention.

〔Record〕

Formula [I] General formula [■]: However, in the general formula [■], R1, R2, R3 and R4 are
Each may be the same or different, and an alkyl group [This alkyl group may have, for example, a halogen atom, an alkoxyl ring arbitrary substituent, and specifically, for example, a methyl group, an ethyl group, n-propyl group, n-butyl group, methoxymethyl group, etc.)-? Examples include linear or branched alkyl groups such as dimethyl group (the number of carbon atoms in the portion excluding substituents is preferably in the range of 1 to 4). ], aralkyl group [This aralkyl group is, for example, a halogen atom,
The alkoxyl group ring may have any substituent, and specific examples thereof include aralkyl groups such as benzyl group and phenethyl group. ], or an aryl group [this aryl group may have an arbitrary substituent on the ring, for example, a gun atom, an alkyl group, or an alkoxyl group, specifically, for example, a phenyl group, a naphthyl group, a p-chloro Examples include aryl groups such as phenyl group and m-methoxyphenyl group. ] represents. Or a pair of R4 and R2 and a pair of R3 and R
One to all four of the groups with 4 may represent all the residues forming a cyclic amine group, such as pyrrolidino, piperidino, pyrrolidino, etc., together with the bonded nitrogen atom.

[Detailed description and examples of the invention]

The violanthrone derivatives of the formula [■] used in the present invention may be used alone or in combination of two or more, and the photosensitive layer of the single-layer electrophotographic photoreceptor of the present invention By including it in the charge generation layer of the laminated electrophotographic photoreceptor of the present invention, it can exhibit a good photoconductive effect, and by including it in the charge generation layer of the laminated electrophotographic photoreceptor of the present invention, it can be used as an excellent charge generation material as detailed below. It can show a significant effect.

All representative compounds of the ketazine compound of the general formula (■) used in the present invention are illustrated below.

Compound Example 1: Compound Example 2: Compound Example 3: Compound Example 4: Compound Example 5: The Keta-Sin compound of the general formula [■] used in the present invention may be used alone, or Two or more types may be used in combination, and by including them in the charge transport layer of the laminated electrophotographic photoreceptor of the present invention, they can exhibit excellent effects as a charge transport substance as detailed below. Furthermore, the photosensitive layer of the single-layer electrophotographic photoreceptor of the present invention may contain the formula [I
] By including it together with the violanthrone derivative,
The effects of the present invention can be expressed even more markedly.

Furthermore, by including the ketazine compound of the general formula (Il) in the charge generation layer of the laminated electrophotographic photoreceptor of the present invention together with the violanthrone derivative of the formula CI), the effects of the present invention can be more clearly exhibited. can be done.

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 injects generated fc charge carriers into the charge transport layer with full efficiency. Therefore, it is desirable to use a thin film layer, for example, a thin film layer having a thickness of 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 to generate many charge carriers, and the generated charge carriers are injected into the charge transport layer without being deactivated by recombination or trapping. This is due to necessity.

For example, the charge generation layer may be formed using the above formula [■] as a charge generation material.
of the violanthrone derivative and optionally υ of the general formula (n
) can be formed by coating a ketazine compound on a substrate together with a suitable binder (or without a binder), or by forming a vapor deposited film using a vacuum vapor deposition apparatus.

When a ketazine compound is added to the charge generation layer, the amount of the ketazine compound to be used is preferably 10 times or less (by weight), preferably 0.01 to 1 times (by weight) the amount of the charge generating 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 (condensation polymer of hisphenol and heptalic acid, etc.), polycargonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin,
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 80
A weight percent or less, preferably a weight percent or less of 40 weight M% 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 completely dissolve the underlying charge transport layer or undercoat layer. Specific organic solvents include alcohols such as methanol, ethanol, and isoglopanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and dimethylsulfoxide. Sulfoxides, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated carbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichlorethylene. Hydrogens or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating method, spray coating method, spinner coating method, bead coating method,
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. 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° C. to 200° C. for a period of time ranging from 5 minutes to 2 hours, either stationary or under ventilation.

The charge transport layer is electrically connected to the above-mentioned charge generation layer 9 and charges carriers injected from the charge generation layer in the presence of an electric field. It has the function of receiving and transporting these charge carriers to the surface. 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 (referred to as 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" used here includes the broad definition of "light rays," which includes all types of rays such as gamma rays, X-rays, ultraviolet rays, visible light, near infrared rays, infrared rays, and far infrared rays. 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 can be used to form a film by selecting and using a suitable binder as required.

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, 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, the total thickness of the charge transport layer cannot be increased more than necessary. Typically it is 5 microns to 30 microns, with a preferred range of 8 microns to 20 microns. When forming the charge transport layer by coating, an appropriate coating method similar to that used for coating the charge generation layer 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 conductive substrate having, for example, a conductive layer. Substrates with conductive layers include those that are conductive themselves, such as aluminum, aluminum alloys, steel, bad lead, stainless steel, pananoum, molybdenum, chromium, titanium, nickel, indium, gold, platinum, and other gold layers. In addition, it can be made of glass having a layer formed by vacuum evaporation of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate). , acrylic resin, polyfluorinated ethylene, etc.), conductive particles (e.g., carbon black, silver particles, etc.) together with a suitable binder on a plastic substrate,
Conductive particles impregnated into whole plastic or paper substrates or conductive
.

For example, a plastic having a polymer with a chemical nature can be used. The shape of the conductive substrate is arbitrary, and may be a known shape such as a plate, a cylinder, or an endless belt.

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-
It can be formed from 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 undercoat layer is suitably 0.1 micron to 40 micron, preferably 0.1 micron to 3 micron. When the charge transport material is an electron transport material, it is necessary to positively charge the surface of the charge transport layer, and when exposed to light after charging, electrons generated in the charge generation layer are injected into the charge transport layer in the exposed area. , after which it reaches the surface and neutralizes the positive charges, causing attenuation of the surface potential and creating an electrostatic contrast with the unexposed area. A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be completely fixed directly, or toner@yfr: after being transferred to paper, plastic film, etc., it can be developed and fixed.

Alternatively, a method may be used in which the electrostatic latent 1# 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 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. After that, it reaches the surface and completely neutralizes the negative charges, resulting in attenuation of the surface potential and an electrostatic contrast 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.

On the other hand, the photosensitive layer of the single-layer electrophotographic photoreceptor of the present invention comprises the violanthrone derivative of the formula III) and the general formula (I).
In addition to the ketazine compounds I and I, a hydrazone compound, a pyrazoline compound, etc. are added as necessary, and the layer is coated using the same binder, solvent, etc. as in the case of the charge generation layer. In particular, it can be formed. Further, the same conductive substrate and undercoat layer as used in the laminated electrophotographic photoreceptor can be used.

The single-layer type to laminated type electrophotographic photoreceptor of the present invention has ultraviolet rays, ultraviolet rays,
To prevent deterioration caused by ozone, etc., stains caused by oil, etc., scratches caused by metal chips, etc., and scratches and scraping of the photoconductor caused by photoconductor contact members such as developing members, transfer members, cleaning members, etc., the photosensitive layer or charge A protective layer may be further provided on the generation layer and the like. In order to form an electrostatic latent image on this protective layer, it is desirable that the surface resistivity is 1×10 11 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-acrylic acid copolymer, styrene-acrylonitrile copolymer, etc. The photosensitive layer can be formed by dissolving a resin in a suitable organic solvent and applying the solution 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 to 2
0 micron, particularly preferably in the range 0.2 to 5 micron.

Example 1 Aqueous solution of casein in ammonia (casein 11.2.li', 28% aqueous ammonia I
I, water 222 mJ) 2 Coated by dip coating method,
Dry and coat ii 1. A subbing layer of 777 m2 of O was formed.

Next, 1 part by weight of the same violanthrone derivative as in Example 1, 0; 5 parts by weight of the exemplified compound (1) of general formula [■], and polycarnate resin (Idemitsu Polycargene) A-
2200) 1 part by weight and 30 parts by weight of Improvil alcohol? -Dispersed for 4 hours using a Lumil 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 is 13
It was a micron.

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 VS). Sensitivity is determined by the amount of exposure (E) required to attenuate to 1/2 of the potential after dark decay vs.
1/2, lux · see ) f was evaluated.

These results were as follows.

V, knee 580 delt V, knee 560 volt El/2: 6.31 ux-see Example 2 An ammonia aqueous solution of casein (casein 11.2 g, 28% ammonia water I11 water 222 ml) was coated on an aluminum cylinder by t-dip coating method. It was coated and dried to form a subbing layer with a coating weight of 1.09/m2.

Next, 1 part by weight of the same violanthrone derivative as in Example 1, 1 part by weight of butyral resin (S-LEC BM-2: manufactured by Sekisui Chemical Co., Ltd.) and 30 parts by weight of isopropyl alcohol were added.
kyl? -Dispersed for 4 hours using a Lumil 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 is 0
．． It was 3 microns.

Next, 1 part by weight of the exemplified compound (1) of general formula (II),
Polysulfone Il resin (P1700: manufactured by Union Carbide Co., Ltd., 1 part by weight and 6 parts by weight of monochlorobenzene were mixed and dissolved by stirring with a stirrer. This liquid was coated on the charge generation layer by dip coating and dried. A charge transport layer was formed.The film thickness at this time was 12 microns.A corona discharge of 15 KV was applied to the photoreceptor thus prepared.The surface potential at this time was measured (initial potential V, )
. Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay VS). Sensitivity was evaluated by measuring the exposure 1 (E 1/2, lux - see ) f required to attenuate the potential Vs 't'' 1/2 K after dark decay.

These results were less than the following.

ve: 615 & Ruto Vs: 600 & Ruto El/2: 5.31ux-see Examples 3 to 6 Exemplary Compound 4 used in Example 2 In place of the compound in (1), the exemplary compounds shown in Table 1 were used, respectively. Otherwise, a photoreceptor was prepared in the same manner as in Example 2, and the characteristics of this photoreceptor were measured. These results are shown in Table 1.

Table 1 Comparative Examples 1 to 6 Charge transport substances shown in Table 2 in place of the ketazine compound used in Example 3? A photoreceptor was produced in exactly the same manner as in Example 3, except that the photoreceptor was used. Its charging characteristics are shown in Table 3.

Table 2 Table 3 Example 7 Exemplary compound (1) of general formula [■]0.
The same photoreceptor as in Example 2 was prepared except that 51 plate parts were added. The surface potential V and v6 on this photoreceptor,
Also, the exposure amount E 1/2 Th required to attenuate the potential V after dark decay to 1/2 was measured.

The results are shown below.

Vo: 595 & Rut V: -585 Gert El/2: 5.01 ux-sec As is clear from the results of Examples 1 to 7, the laminated electrophotographic photoreceptor of the present invention has a It can be seen that a photoreceptor with extremely high sensitivity was obtained compared to .about./166.

Furthermore, the photoreceptors of Examples 2 to 4 were used as NP manufactured by Canon Co., Ltd.
Image output i was repeated 20,000 times using a -150Z copying machine. As a result, good quality images were obtained for each photoreceptor even after repeating 20,000 times. As a result, it can be seen that the photoreceptor of the present invention has extremely excellent durability.

〔Effect of the invention〕

The electrophotographic photoreceptor of the present invention has significantly higher sensitivity than conventional photoreceptors, whether it is a single layer type or a laminated type, and has an extremely low residual potential even after a durability test.

Claims (2)

[Claims] (1) An electrophotographic photoreceptor characterized by having a photosensitive layer comprising a violanthrone derivative represented by the following formula [I] and a ketazine compound represented by the following general formula [II] on a conductive support. . [Note] Formula [I] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ General formula [II]: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In general formula [II], R_1, R_2, R_3 and R_4 are Each represents an alkyl group, an aralkyl group, or an aryl group that may be the same or different and may have a substituent.Or one of the set of R_1 and R_2 and the set of R_3 and R_4. (Or all four may represent a residue that forms a cyclic amino group together with the nitrogen atom to which it is bonded.) (2) In an electrophotographic photoreceptor having a charge generation layer and a charge transport layer on a conductive support, the charge generation layer comprises a layer containing a violanthrone derivative represented by the following formula [I], and the charge transport layer An electrophotographic photoreceptor comprising a layer containing a ketazine compound represented by the following general formula [II]. [Note] Formula [I] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ General formula [II]: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In general formula [II], R_1, R_2, R_3 and R_4 are Each represents an alkyl group, an aralkyl group, or an aryl group that may be the same or different and may have a substituent.Or one of the set of R_1 and R_2 and the set of R_3 and R_4. (Or all four may represent a residue that forms a cyclic amino group together with the nitrogen atom to which it is bonded.)