JPS61179447A - 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 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]

Heretofore, 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, polyvinylanthracene, carbazole,
Low-molecular organic photoconductors such as anthracene, pyrazolines, oxadiazoles, hydrazones, polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes Alternatively, organic pigments and dyes such as squaric acid methine dyes are known. In particular, 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.
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
No. 628, etc., and is known as an electrophotographic photoreceptor using a photoconductive water disazo pigment as a charge generation material in a photosensitive layer which is functionally separated into a charge generation layer and a charge transport layer in a skin-like manner. .

FCT photographic 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.
Moreover, it has all the advantages of being able to freely control the sensitive wavelength range 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 photoreceptor obtained by fully laminating the photoreceptor has advantages over the single-layer 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 provide an electrophotographic photoreceptor which improves all of the above-mentioned conventional drawbacks, has high sensitivity, and has extremely low residual potential even after a durability test.

The above object is to have a photosensitive layer comprising a violanthrone derivative represented by the following general formula [■] and a ketazine compound represented by the following general formula [II] on a conductive support. Electrophotographic photoreceptor of the invention (hereinafter referred to as
In the single-layer electrophotographic photoreceptor of the present invention) or the 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 [I].
The electrophotographic photoreceptor of the present invention (hereinafter referred to as 1 This is achieved by the layered electrophotographic photoreceptor of the present invention.

〔Record〕

General formula [■] General formula [II]: However, in the general formula [II], R1, R2, R3 and R4 may be the same or different, and an alkyl group [this alkyl group is, for example, A halogen atom, an alkoxyl group ring may have any substituent, and specifically, a straight chain such as a methyl group, ethyl group, n-propyl group, n-butyl group, methoxymethyl group, ethoxymethyl group, etc. and branched alkyl groups (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 ring may have any substituents and may have a temperature of 0.degree. C., 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 pair of R1 and R2 and R3 and 8
One to all four of the group with 4 may represent all the residues forming a cyclic amino group, such as pyrrolidino, piperidino, pyrrolidino, etc., together with the bonded nitrogen atom.

[Detailed description and examples of the invention]

The violanthrone derivative of the general formula 〇) used in the present invention may be used alone at a good temperature, or two or more types may be used in combination. By including the charge generating material in the charge generating layer of the laminated electrophotographic photoreceptor of the present invention, it is possible to exhibit a good photoconductive effect. .

It can exhibit excellent effects as a supplement.

Representative compounds of the ketazine compound of the general formula [1] 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 compounds of the general formula CUE used in the present invention may be used singly, or two or more thereof may be used in combination. They 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. ,
The photosensitive layer of the single type electrophotographic photoreceptor of the present invention has the general formula [
By including it together with the violanthrone derivative ((ii)), the effects of the present invention can be brought out even more markedly.

However, by including the ketazine compound of the general formula [l] in the charge generation layer of the laminated electrophotographic photoreceptor of the present invention together with the violanthrone derivative of the general formula [■],
The effects of the present invention can be expressed 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. Next, it is desirable to have a thin film layer, for example, a thin film layer having a total thickness of 10 microns or less, preferably 0.001 micron to 1 micron. This means that most of the incident light is absorbed by the charge generation layer, generating a large number of charge carriers, and that the generated charge carriers are recombined, trapped, and transported without being deactivated. This is due to the need to inject into the layer.

For example, the charge generation layer has the general formula C as a charge generation material.
It can be formed by coating the violanthrone derivative of I) and, if desired, the ketazine compound of the general formula [11] on a substrate together with an appropriate binder (or without a binder). It can be obtained by forming a vapor-deposited film.

When the entire 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-vinylcarnogzole, polyvinylanthracene, and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and 7-talic acid, etc.),
Examples of insulating resins include polycarnate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. I can do it. The resin contained in the charge generation layer is 8
Less than 0% by weight, preferably less than 40% by weight is suitable.

The solvent that dissolves these resins is preferably selected from those that do not dissolve the charge transport layer or subbing layer, which varies depending on the type of resin. Specific organic solvents include alcohols such as methanol, ethanol, Impro/4-nol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl Sulfoxides such as sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol, methyl ether, esters such as methyl acetate and ethyl acetate, aliphatic compounds such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, etc. 10 Gunified hydrocarbons or benzene, toluene,
Aromatic compounds such as xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
Mayer coating method, blade coach ink method, roller coating method.

One step can be carried out using a coating method such as a curtain coating method. Drying is done after drying to the touch at room temperature.
A method of heating and drying is preferred. Heat drying at 30℃~2
It can be carried out at a temperature of 00°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 receives and takes charge carriers injected from the charge generation layer in the presence of an electric field, and transports these charge carriers to the surface. It has the ability to be transported. In this case, the charge transport layer may be laminated as above or below the charge generation layer. However, it is desirable that the charge transport layer is laminated on the charge generation layer.

It is preferable that the substance that completely transports charge carriers in the charge transport layer (referred to as a charge transport material) is substantially insensitive to the wavelength range of electromagnetic waves to which the above-mentioned charge generation layer is sensitive.

What do we mean by "electromagnetic waves" here?

Includes a broad definition of "light rays" that includes r-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 matches or overlaps that of the charge generation layer, charge carriers generated in both layers capture 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, polycarbanates, polystyrene, acrylonitrile-styrene copolymers, acrylonitrile-butadiene copolymers, polyvinyl butyral, polyvinyl formal, folysulfone (f+)7p rylamide, polyamide, Examples include insulating resins such as chlorinated rubber, and organic photoconductive polymers such as polyN-vinylcarnogzole, polyvinylanthracene, and polyvinylpyrene.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. 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 a conductive layer, it is possible to use a substrate which itself is conductive, such as evaporated aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. In addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, and other plastics with nine layers formed by full vacuum deposition (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic) resin, polyfluoroethylene, etc.), conductive particles (e.g. car & black, silver particles, etc.) - A substrate coated on plastic with a suitable binder, conductive particles are impregnated into plastic or paper, and then the substrate or Plastic or the like having a conductive polymer can also 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-
Acrylic acid copolymer, polyvinyl butyral1. Phenolic resin, polyamide (nylon 6, nylon 66,
It can be formed from nylon 610° copolymerized nylon, aluminum (oxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is suitably 0.1 to 40 microns, preferably 0.1 to 3 microns.A charge generation layer and a charge transport layer are laminated in this order on a conductive substrate to form a photoreceptor. When the charge transport material is made of an electron transport material, it is necessary to positively charge the surface of the charge transport layer.When exposed to light after charging, good electrons are generated in the charge generation layer in the exposed area and the charge transport layer is charged. After reaching the surface, the positive charges are completely neutralized, the surface potential is attenuated, and an electrostatic contrast is created between the surface potential and 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 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 all 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 surface metal of the charge transport layer, and after charging, when exposed to light, 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 neutralizes the negative charges, resulting in attenuation of the surface potential and an electrostatic contrast between it and the unexposed area.

At the time of development, it is necessary to use an electron transporting substance and, contrary to the case where a positively charged toner is used, a positively charged toner.

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 CI) and the general formula [
In addition to the ketazine compound in step 1 [], 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,
The photosensitive layer is included in order to completely prevent deterioration caused by ozone, dirt caused by oil, etc., scratches caused by metal chips, etc., and damage and scraping of the photoconductor caused by photoconductor abutting members such as developing members, transfer members, and cleaning members. A protective layer may be further provided on the charge 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 Ω or more.

The protective layer used in the present invention includes /IJ vinyl butyral,
Polyester, l-licarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate,
The photosensitive layer can be formed by dissolving a resin such as polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer, etc. in a suitable organic solvent and drying the solution. Furthermore, additives such as ultraviolet absorbers and the like can be added to the resin liquid. At this time, the thickness of the protective layer is generally 0.05 to 20
microns, particularly preferably in the range from 0.2 to 5 microns.

Example 1 Ammonia aqueous solution of casein (casein 11.2, 9, 28% ammonia water II,
222 m of water) was applied using a dip coating method and dried to form a subbing layer with a coating weight of 1.01/m''.

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) of the general formula ([1), 1 part by weight of polycarbonate resin, and 30 parts by weight of isopropyl alcohol"f!: Dispersion was performed using a coal mill dispersion machine for 4 hours.This dispersion was first formed and coated on top of the sublayer by dip coating, and dried to form a charge generation layer.

The film thickness at this time was 14 microns.

Corona discharge of 5kv per 1cm photoreceptor after preparing in this way? I did it. The surface potential at this time was measured (initial potential Vo
). Furthermore, the surface potential of this photoreceptor after being left in the dark for t-5 seconds was measured at 7'C (dark decay Vs).

Sensitivity was evaluated by measuring the amount of exposure (El, 4, tuX·5ea) i required for dark decay to attenuate to the final potential Vst'l/2.

These results will be shared with you next time.

Vo Knee 585 Gault vs Knee 570 & Ruth E%: 6.2 tux*@ec Example 2 An ammonia aqueous solution of casein (casein 11.21I, 28N ammonia water II,
Water 22m) Coated by t-dip coating method and dried to a coating weight of 1. Q,! A subbing layer of i'/m'' was formed.

Next, 1 part by weight of the same violanthrone derivative as in Example 1, 1 part by weight of butyral resin (Eslec BM-2, manufactured by Tsukiki Kagaku ■) and 30 parts by weight of isopropyl alcohol were added.
The mixture was dispersed for 4 hours using a ylf-lumil 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 at this time is 0.
It was 3 microns.

Next, 1 part by weight of the exemplified compound (1) of general formula (II),
1 part by weight of polysulfone m fat (P1700: manufactured by Union Carnoguito) and 7G parts by weight of monochlorobense were completely mixed and dissolved by stirring with a stirrer. This liquid was coated on top of the charge generation layer by a dip coating method and dried to form a charge transport layer. The film thickness at this time was 12 microns.

The thus prepared photoreceptor was subjected to a corona discharge of 15 kV. The entire 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 amount gH11ux*sec) t- required to attenuate the potential after dark decay to V5'il/2.

These results were as follows.

Vonie 615 Delt V, Nee 605 Gault Ey2: 4.8 tux-aee Examples 3 to 6 Exemplary compound (1) of the following general formula [II] used in Example 3
A photoreceptor was prepared in exactly the same manner as in Example 3 using the exemplified compounds shown in Table 1 instead of K, and the characteristics of this photoreceptor were measured. The results are shown in Table 1.

Table 1 3 (2) -625-6105,74(
3) -610-6004,95(4)
-610-5955,06(5) -620-6
055,5 Comparative Examples 1 to 6 Photoreceptors were prepared in exactly the same manner as in Example 3, except that the charge transport materials shown in Table 2 were used in place of the ketazine compound used in Example 3. The charging characteristics are shown in Table 3.

Table 2 Table 3 11-600-5807.7 22-590-5657.1 33-595-5707.5 44-615-5908.3 55-600-5707.4 66-590-5607.9 Example 7 Charge The generation layer further contains exemplified compound (1)0 of the general formula [1[).
．． A photoreceptor was prepared in the same manner as in Example 2, except that 5 parts by weight was added. Surface potentials vo and v6 on this photoreceptor
, and the exposure amount Elt required to attenuate the potential after dark decay to Vs t''1/2.

The results are shown below.

Vo knee 610 Zaruto Vs knee 600 Zaruto B1112: 4.3 Aux-sec Examples 1 to 7
As is clear from the results, it can be seen that the laminated electrophotographic photoreceptor of the present invention has extremely high sensitivity compared to photoreceptors 41 to 6 of comparative examples. Furthermore, Examples 2 to 4
Using a Canon Co., Ltd. NP-150Z copier, the photoreceptor was imaged 20,000 times. 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, whether it is a single layer type or a laminated type, has significantly higher sensitivity than conventional photoreceptors, and has an 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.)