JPS61179451A - 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 functinally 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. 2 On the other hand, since it was discovered that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. For example, organic photoconductors such as poIJ + N-vinylcarbazole, polyvinylanthracene, etc. Low-molecular organic photoconductors such as remer, carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indica Organic pigments and dyes such as dyes, thioindyes, and methine squaric acid dyes are known. especially,
Organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded, so there are many photoconductive materials. Organic pigments and dyes have been proposed. For example, U.S. Patent Nos. 4,123,270 and 424
No. 7614, No. 4251613, No. 425161
No. 4, No. 4256821, No. 4260672,
Same No. 4268596, Same No. 4278747, Same No. 4
As disclosed in No. 293,628, an electrophotographic photoreceptor is known in which a disazo pigment exhibiting photoconductivity is used 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 selecting an appropriate binder, so it is possible to provide an extremely highly productive and inexpensive photoreceptor.
Moreover, it has the advantage that the sensitive wavelength range can be freely controlled by selecting the organic pigment. 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 K has advantages over 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 providing a photosensitive layer comprising a violanthrone derivative represented by the following general formula [I] and a ketazine compound represented by the following general formula [111] 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 general formula: The electrophotographic photoreceptor of the present invention ( This is achieved by the layered electrophotographic photoreceptor of the present invention).

〔Record〕

General formula CI) General formula [■]: However, in the general formula (If), R1, R2, R3 and R4 may be the same or different, and an alkyl group [this alkyl group] is, for example, a 710rn atom,
Alkoxyl group ring may have any substituent, specifically, for example, methyl group, ethyl group, n-propyl group,
Examples include linear or branched alkyl groups (the number of carbon atoms in the portion excluding substituents is preferably in the range of 1 to 4) such as n-butyl group, methoxymethyl group, and ethoxymethyl group. ]
, aralkyl group [This aralkyl group may have, for example, a halogen atom, an alkoxyl group ring or 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, such as a halogen atom, an alkyl group, or an alkoxyl group, specifically, for example, a phenyl group, a naphthyl group, a p-chlorophenyl group. , m-methoxyphenyl group and other aryl groups. ] represents. Or a combination of R1 and R2 and R
One to all four of the set of s and R4 together with the bonded nitrogen atoms are, for example, pyrrolidino, piperidino,
It may also represent a residue forming a cyclic amino group such as pyrrolidino.

[Detailed description and examples of the invention]

The violanthrone derivative of general formula C1) used in the present invention may be used alone in an amount of 1 m or in combination of two or more, and is included in 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.

Representative compounds of the ketazine compound of the general formula (II) used in the present invention are illustrated below.

Compound Example 1: Compound Example 2: Compound Example 3: Compound Example 4: Compound Example 5: The ketazine compound of the general formula (II) used in the present invention may be used alone or in combination of two types. The above 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. Further, by including the violanthrone derivative of general formula (1) in the photosensitive layer of the single-layer electrophotographic photoreceptor of the present invention, the effects of the present invention can be brought out even more markedly.

Furthermore, by including the ketazine compound of the general formula [■] in the charge generation layer of the laminated electrophotographic photoreceptor of the present invention together with the violanthrone derivative of the general formula CI),
The effects of the present invention can be brought out even more markedly.

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 efficiently injects generated charge carriers into the charge transport layer. 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, generating many charge carriers, and that the generated charge carriers are transported by recombination or trapping without being deactivated. This is due to the need to inject into the layer. - For example, the charge generation layer may have the above general formula (
It can be formed by coating a cr-dan conductor (No. 11) and, if desired, a ketazine compound of the general formula [■] above together with a suitable binder (or without a binder), or by vacuum evaporation. It can be obtained by forming a vapor-deposited film using an 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-vinylcarbasol, polyvinylanthracene, and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and heptalic acid, etc.), polycargenate, terester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin,
polyamide, polyvinylpyridine, cellulose resin,
Examples include insulating resins such as urethane resin, niboxy resin, casei 7.7f17 vinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is
A suitable content is 80 weight t% or less, preferably 40 weight tS 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 underlying charge transport layer or subbing layer. Specific solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl. Sulfoxides such as sulfoxide, ethers such as dihydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, etc. Aliphatic halodanized hydrocarbons 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, heat 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 charge generation layer described above, and has the function of receiving and receiving 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 (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 herein includes a broad definition of "light rays" that includes gamma rays, X-rays, ultraviolet rays, visible light, near infrared rays, infrared 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 can be used to form a film by selecting and using an appropriate binder as required.

Resins that can be used as binders include, for example, acrylic resins, polyarylates, polyesters, polycargonates, polystyrenes, acrylonitrile-styrene cotelemers, acrylonitrile-fil diene copolymers, polyvinyl butyrals, polyvinyl formals, ? Insulating resins such as risulfone, I-lyacrylamide, polyamide, chlorinated rubber, or poly-N-vinylcarbazole,
Organic photoconductive I remers such as polyvinylanthracene and I lipinylpyrene 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. 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. As the substrate having the conductive layer, materials that are conductive themselves such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum can be used. In addition, glass materials (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene 7 talate, acrylic resin, poly7tethylene, etc.), conductive particles (e.g., carbon black, silver particles, etc.) together with a suitable binder on a plastic substrate,
A base material made of plastic, resin or paper impregnated with conductive particles, a glass material containing a conductive polymer, etc. can be used. The shape of the conductive substrate is arbitrary, and may be any 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. Subbing layer, casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
It can be formed from acrylic acid copolymer, polyvinyl butyral, phenolic resin, I-lyamide (Fylon 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 using a photoreceptor in which a charge generation layer and a charge transport layer are laminated in this order on a conductive substrate, and the charge transport material is 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 to neutralize the positive charge, causing a decrease in surface potential and creating static electricity between the exposed area and the unexposed area. Contrast occurs. A visible image can be 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, glass 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 known methods, and are not limited to specific ones.

On the other hand, when the charge transport material consists of a hole transport material, it is necessary to charge the light surface of the charge transport layer negatively. When exposed to light after charging, holes generated in the charge generation layer are transferred to the charge transport layer in the exposed area. It is injected and then reaches the surface to neutralize 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 general formula [I] and the general formula (I).
In addition to the ketacin-based compound described in 1), a hydrazone-based compound, a pyrazoline-based compound, etc. may be added as necessary, and the layer may be coated using the same binder, solvent, etc. as described above for the charge generation layer. It can be formed into many shapes. 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,
The photosensitive layer or electric charge is used to prevent deterioration caused by ozone, etc., dirt caused by oil, etc., scratches caused by metal chips, etc., and scratches and abrasion of the photoconductor caused by photoconductor contact members such as developing members, transfer members, cleaning members, etc. 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 I x 10''Ω or more.

The protective layer used in the present invention is made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, ? It can be formed by dissolving a resin such as polyimide, polyarylate, polyurethane, styrene-butanoene copolymer, styrene-acrylic acid cotrimer, styrene-acrylonitrile corimer, etc. in an appropriate organic solvent on 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 in the range of 05 to 20 microns, particularly preferably 0.2 to 5 microns.

Example 1 Casein dissolved in ammonia on an aluminum cylinder! (casein t1.2.9,28 chia/monia water 111
1 water 222111) was applied by dip coating method and dried to give a coating amount of 1. A subbing layer of O17m2 was formed.

Next, 1 part by weight of the same violanthrone derivative as in Example 1, 0.5 part by weight of the above-mentioned exemplified compound (1) with general formula Cl), and polycarbonate resin (Idemitsu Polycarbonate) A-
1 part by weight of 2200) and 30 parts by weight of isopropyl alcohol were dispersed for 4 hours using a mail mill dispersion machine. This dispersion was applied by dip coating onto the previously formed subbing layer, and dried to form a charge generation layer. was formed. 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 measures the amount of exposure (E 1ux-sec) required to attenuate the potential V after dark decay to IA.
/2'.

These results were as follows.

Vo: -6QO Melt vs: -5so Zalto E1/2: 6.81ux・sec Example 2 An aqueous ammonia solution of casein (casein 11.2N, 28% aqueous ammonia III,
Water 22217) was applied by dip coating and dried to form a subbing layer with a coating weight of 1.0 J/m.

Next, 1 part by weight of the same violanthrone derivative as in Example 1, butyral resin (Esle, BM-2: fi water chemical)
Co., Ltd.) and 30 parts by weight of Improvil alcohol? - Fractionated for 4 hours using a Lumir disperser. This dispersion is applied onto the previously formed subbing layer using a dip coating method,
It was dried to form a charge generation layer. The film thickness at this time is O,3
It was a micron.

Next, 1 part by weight of the above-mentioned exemplified compound (1) of the general formula [■], 1 part by weight of polysulfone FM (P1700, manufactured by Union Carbide Co., Ltd.) and 6 parts by weight of heptanochlorobenzene 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 at this time was 12 microns.

Corona discharge of -5 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 1A, which measures the amount of exposure (E 1uxss・C) required to attenuate the potential vs after dark decay to V2.
′ was evaluated.

These results were as follows.

Vo: 585 Gelt Vs: -570 Melt El, 2: 4.411Hc'l@@eExamples 3 to 6 In place of the compound of exemplified compound (1) used in Example 2,
A photoreceptor was prepared in exactly the same manner as in Example 2, except that each of the exemplified compounds shown in Table 1 was used, and the characteristics of this photoreceptor were measured. The results are shown in Table 1.

Table 1 Comparative Examples 1 to 6 Photoreceptors were prepared in exactly the same manner as in Example 3, except that the charge transport substances shown in Table 2 were used in place of the ketazine compound used in Example 3. The charging characteristics are shown in Table 3.
The same photoreceptor as in Example 2 was prepared except that 5 parts by weight was added. Surface potential Vo and VI% of this photoreceptor
and the exposure amount E1. required to attenuate the potential Vs after dark decay to 1/2. ! was measured.

The results are shown below.

Vo: 600 del)Vs:
-595T1ehtEt/2: 4.
1 1ux*sec As is clear from the results of Examples 1 to 7, the laminated electrophotographic photoreceptor of the present invention has extremely high sensitivity compared to photoreceptors M1 to A6 of comparative examples. It turns out that Further, images of the photoreceptors of Examples 2 to 4 were repeatedly printed 20,000 times using a Canon Co., Ltd. jlliNP-150Z copying machine. As a result, good quality images were obtained on both photoreceptors even after 20,000 repetitions. As a result, it can be seen that the photoreceptor of the present invention has extremely poor 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 extremely low residual potential even after a durability test. .

Claims (2)

[Claims] (1) An electrophotographic photosensitive method characterized by having a photosensitive layer comprising a violanthrone derivative represented by the following general formula [I] and a ketazine compound represented by the following general formula [II] on a conductive support. body. [Note] General 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 of which may be the same or different and represents an alkyl group, an aralkyl group, or an aryl group which may have a substituent. Alternatively, one of the set of R_1 and R_2 and the set of R_3 and R_4 (One 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 general formula [I], and the charge transport An electrophotographic photoreceptor characterized in that the layer comprises a layer containing a ketazine compound represented by the following general formula [II]. [Note] General 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 of which may be the same or different and represents an alkyl group, an aralkyl group, or an aryl group which may have a substituent. Alternatively, one of the set of R_1 and R_2 and the set of R_3 and R_4 (One or all four may represent a residue that forms a cyclic amino group together with the nitrogen atom to which it is bonded.)