JPS61179443A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and durability by incorporating a specified pyranthrone 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 pyranthrone 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 capable of forming a good-quality image even after repeated cycles of image formations, and accordingly a superior photosensitive body small in residual potential after repeated uses to be obtained.

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 kino/pigments, beryleno pigments, indigo dyes, Organic pigments and dyes such as thioindigo dyes and methine squaric acid dyes are known. In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the range in which compounds that exhibit photoconductivity in an appropriate wavelength range can be selected 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 appropriately selecting a 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 photoreceptor obtained by laminating the above-mentioned materials is more advantageous than 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 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 electronic of the present invention, which has a photosensitive layer comprising a pyrantrone derivative represented by the following formula CI) and a ketazine compound represented by the following general formula [■] on a conductive support. In a photographic photoreceptor (hereinafter referred to as the 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 [■ ] 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] 〇 General formula [■]: However, in general formula [■], R1+ R2+ R5 and R4
may be the same or different, and may have an alkyl group [this alkyl group is, for example], a rhodane atom, or an alkoxyl group ring, and may have an arbitrary substituent, specifically, for example, a methyl group. , ethyl group, n-globyl group, n
A linear or branched alkyl group such as -butyl group, methoxymethyl group, or nidoxymethyl group (the number of carbon atoms in the portion excluding the substituents is preferably in the range of 1 to 4) is provided. ],
Aralkyl group [This aralkyl group may have, for example, a halodane atom or an arbitrary substituent on the alkoxyl ring, 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 halodane atom, an alkyl group, or an alkoxyl group, specifically, for example, a phenyl group, a naphthyl group, or a p-chlorophenyl group. , m-methoxyphenyl group and other aryl groups. ] represents. Or a set of R1 and R2 and R5
One to all four of the pairs of and 84 may represent a residue that forms a cyclic amino group, such as pyrrolidino, piperidino, pyrrolidino, etc., together with the bonded nitrogen atom.

[Detailed description and examples of the invention]

The vilantrone derivatives of formula CI] used in the present invention may be used alone or in combination of two or more, and are 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 be used as an excellent charge generation material as detailed below. It can show a significant effect.

Typical ketazine compounds 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 ketazine compounds of the general formula [1[] used in the present invention may be used alone or in combination with two More than one species may be used in combination, and by including it in the charge transport layer of the laminated electrophotographic photoreceptor of the present invention, it can exhibit excellent effects as a charge transport substance as detailed below. , in the photosensitive layer of the single-layer electrophotographic photoreceptor of the present invention together with the -lanthrone derivative of the general formula [1)]
, the effects of the present invention can be brought out even more markedly.

Further, the charge generation layer of the laminated electrophotographic photoreceptor of the present invention may contain the pyranthrone derivative of the general formula [■] as well as the pyranthrone derivative of the general formula [■].
When the ketazine compound (11) is included, 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. In order to achieve this, it is desirable to form one 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 without being deactivated (by recombination or trapping). This is due to the need to inject into the layer.

For example, the charge generation layer has the above formula (1) as a charge generation material.
and optionally) the above general formula [1[
It can be formed by coating the ketazine compound () together with a suitable binder (or without a binder) on a substrate, or by forming a vapor-deposited film using a vacuum vapor deposition apparatus.

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 when forming the charge generation layer by coating can be selected from a wide range of insulating resins, including poly-N-vinylcarbazole, ? It can be selected from organic photoconductive polymers such as libinyanthracene and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and heptalic acid, etc.), telicar'yne), /! J ester, phenoxy resin,
Polyvinyl acetate, acrylic resin, polyacrylamide resin, ? Examples include insulating resins such as lyamide, I-rivinylpyridine, cellulose resin, urethane resin, niboxy resin, casein, -rivinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is
A content of 80% by weight or less, preferably 40% by weight or less is suitable.

The solvent that dissolves these resins varies depending on the type of resin, and it is preferable to select a solvent that does not dissolve the underlying charge transport layer or subbing layer. Specific organic solvents include alcohols such as methanol, ethanol, and isopronol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide. Sulfoxides such as tetrahydrofuran, dioxane, ethers such as ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated carbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichlorethylene, etc. Hydrogens, aromatics such as lyhabenzene, toluene, xylene, refloin, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating method, spray coating method, subinnan coating method, bead coating method,
This can be carried out using a coating method such as a Mayer-Par coating method, a blade coach ink method, a roller coach ink method, or a curtain coating method. Drying is preferably carried out by drying to the touch at room temperature and then heating. The heating drying can be carried out at a temperature of 30° C. to 200° C. for a period of 5 minutes to 2 hours, either stationary 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 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 "r-electromagnetic waves" as used herein includes a broad definition of "light rays" including 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 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 formed into a film by selecting and using an appropriate inder as required.

Resins that can be used as binders include, for example, acrylic resins, prearylates, polyesters, precarnates, polystyrene, acrylonitrile-styrene co4rimer, acrylonitrile-phtadiene copolymers, polyvinyl butyral, polyvinyl formal, ? Risulphone, f! 97/Insulating resin such as lylamide, polyamide, chlorinated pumice, or poly-N-vinylcarbazole,
Organic photoconductive polymers such as polyvinylanthracene and -rivinylpyrene can 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, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic) have a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. (resin, prefluorinated ethylene, etc.), conductive particles (e.g. carbon black, silver particles, etc.) coated on glass with an appropriate binder, substrates made of plastic or paper impregnated with conductive particles, etc. Silaste, resin, etc. having a conductive I remer 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,
I-rivinyl alcohol, nitrose A/G2-s, ethylene-acrylic acid co-remer, teripinylgteral, phenolic resin, polyamide (nylon 6, nylon 66)
, nylon 610, copolymerized nylon, aluminum; oxymethylated 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. During post-exposure, electrons generated in the charge generation layer in the exposed area are injected into the charge transport layer, then reach the surface and neutralize the positive charge, causing a decrease in surface potential and creating an electrostatic contrast between the exposed area and the unexposed area. 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, 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, and then visually imaged 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 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, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. After that, the negative charges on the surface are neutralized, the surface potential is attenuated, and an electrostatic contrast is created between the surface potential 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 may contain, in addition to the pyranthrone derivative of the formula [■] and the ketazine compound of the general formula [1], a hydrazo/pyrazoline compound or a pyrazoline compound as necessary. It can be formed by adding a compound or the like and applying the same binder, solvent, etc. in the same manner as in the case of the charge generation layer.

. 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, and cleaning members. 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 Ω or more.

The temperature control layer used in the present invention is made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, ? Riimides, polyarylates, polyurethanes, sterene uptasoenco? Limer, styrene-acrylic acid copolymer, sterene-acrylonitrile copolymer? It can be formed by applying a solution prepared by dissolving a resin such as reamer in an appropriate organic solvent 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 in the range of 0.05 to 20 microns, particularly preferably 0.2 to 5 microns.

Example 1 An ammonia aqueous solution of casein (casein 11.2.9, 28% ammonia water IN,
Apply 222 m of water by dip coating method, dry and apply ii 1. A subbing layer of 117 m2 of O was formed.

Next, 1 part by weight of the same vilantrone derivative as in Example 1,
0.5 parts by weight of the above-mentioned exemplary compound (1) of general formula (II),
Polycarbonate resin (Idemitsu polycarbonate A-22
00: manufactured by Idemitsu Petrochemical Co., Ltd.) and 30 parts by weight of 1,4-dioxane 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 at this time was 14 microns.

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 after leaving this photoreceptor in a dark place for 5 seconds!
(dark decay Vs). The sensitivity is the exposure ft (
Evaluation was made by measuring E 1/21ux-see ).

These results were as follows.

Vo: -595N: -580: 5.51ux-sec Example 2 An ammonia aqueous solution of casein (casein 11.2!I, 28% ammonia water IF,
Water (222 rILl) was applied by dip coating and dried to form a subbing layer with a coating weight of 1.0 #/m.

Next, 1 part by weight of the same pyrantrone derivative as in Example 1,
Butyral resin (S-LEC BM-2: Sekisui Chemical Co., Ltd.)
1 part by weight of Improvil alcohol and 30 parts by weight of Improvil alcohol were dispersed for 4 hours using a Goal 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 at this time was 0.3 microns.

Next, 1 part by weight of the above-mentioned exemplified compound (1) of general formula [■], 1 part by weight of hollysulfone resin (P1700, manufactured by Union Carbide Co., Ltd.), 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 a dip coating method and dried to form a charge transport layer.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 chamber (iiVo
). Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (C dark decay Vs). Sensitivity is determined by the amount of exposure (E
The evaluation was made by measuring the V2.1ux-sec).

These results were as follows.

vo ° -615 volts V, ' -600 volts E%: 4. Q 1uxeaec Example 3
~6 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 in place of the exemplified compound A(1) used in Example 2. Body characteristics were measured. These results are shown in Table 1.

Table 1 Examples Exemplary compounds vo (volt)■, (volt)
E112 (1ux・5ec)3 (2)
-625-5154,74(3) -
610-5954, 25(4) -605-5
903,96(5) -620-6104,5
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. Its charging characteristics are shown in Table 3.

Table 2 2H5 Table 3 1 1 -595-575 6.0 2 2 -585-560 5.9 3 3 -590-565 6.6 4 4 -605-585 7.8 5 5 -600-580 6.4 6 6 -615-600 7.0 Example 8 Exemplary compound (1) of general formula (II) was added to the charge generation layer 0
．． The same photoreceptor as in Example 2 was prepared except that 5 parts by weight was added. The surface potential vo and 71 on this photoreceptor
The exposure iE'4 required to strongly attenuate the electric current fs7Vs after dark decay by 1% was measured. The results are shown below.

Vo: -605 Delt V, -59s Delt E's: 3.71 uxas*c Example 1~
As is clear from the results of No. 7, it can be seen that the laminated electrophotographic photoreceptor of the present invention has extremely high sensitivity compared to the comparative examples Nos. 1 to 46. Furthermore, Example 2
Using a Canon Co., Ltd. Kema NP-1502 copying machine, image formation was repeated 20,000 times on the photoreceptors of No. 4 to 4. 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 layer containing a pyranthone 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 pyranthrone 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] 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.)