JPS61179446A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and durability by incorporating a specified polycyclic quinone 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 polycyclic quinone 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]

Up to now, nine electrophotographic photoreceptors have been known that utilize inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components.

On the other hand, since it was discovered that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. For example, 'poIJ + organic photoconductive polymers such as N-vinylcarnozole and polyvinylanthracene; low-molecular organic photoconductors such as carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, and polyarylalkane; Organic pigments and dyes such as 7-talocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindylene dyes, and squaric acid methine dyes are known. In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and they can be used in a large number of light Conductive organic pigments and dyes have been proposed. For example, US Pat. No. 4,123,270, US Pat.
No. 247614, No. 4251613, No. 4251
No. 614, No. 4256821, No. 4260672
A disazo pigment that exhibits photoconductivity as a charge-generating substance in a photosensitive layer that is functionally separated into a charge-generating layer and a charge-transporting layer, as disclosed in Japanese Patent Nos. 4268596, 4278747, and 4293628. Electrophotographic photoreceptors using the same are 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 photoreceptors 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]

An object of the present invention is to improve the above-mentioned conventional drawbacks and provide a highly sensitive photographic photoreceptor.

The above-mentioned object is a book characterized by having a photosensitive layer comprising a polycyclic quinone compound represented by the following formula CII 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 is a polycyclic compound represented by the following formula [■]. The electrophotographic photoreceptor of the present invention (hereinafter referred to as the electrophotographic photoreceptor of the present invention) is composed of a layer containing a quinone compound, and the charge transport layer is composed of a layer containing a ketazine compound represented by the following general formula [II]. This is achieved using a multilayer electrophotographic photoreceptor).

〔Record〕

Formula [I] General formula [II]: However, in the general formula [II], R4, R2, R3 and R4 may each be the same or different, and are an alkyl group [this alkyl group is, for example]・Rhodan atom, alkoxyl group ring may have any substituent, specifically, for example, methyl group, ethyl group, n-propyl group, n-
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 a glutyl group, a methoxymethyl group, and an ethoxymethyl group. ], aralkyl group [this aralkyl group may have, for example, a halogen atom, an alkoxyl ring, or any substituent,
Specific examples include aralkyl groups such as benzyl group and phenethyl group. ], or an aryl group (this aryl group is, for example), a rhodane atom, an alkyl group, an alkoxyl group.The ring may have any substituent, specifically, for example, a phenyl group, a naphthyl group, Examples include aryl groups such as p-chlorophenyl group and m-methoxyphenyl group. ] represents. Or a combination of R1 and R2 and R3
One to all four of the combination of and R4 may represent a residue that forms a cyclic amine group, such as pyrrolidino, piperidino, pyrrolidino, etc., together with the bonded nitrogen atom.

[Detailed description and examples of the invention]

The polycyclic quinone compound of the formula [I] used in the present invention may be used alone or in combination of two or more, and the polycyclic quinone compound of the formula [I] may be used alone or in combination of two or more. By including it in the photosensitive layer, 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, as described in detail below. It can exhibit excellent effects as a charge-generating material.

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 compounds 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, it can exhibit excellent effects as a charge transport substance as detailed below. The photosensitive layer of the single-layer electrophotographic photoreceptor of the present invention has the formula [1
) together with the polycyclic quinone compound, the effects of the present invention can be brought out even more markedly.

Further, in the charge generation layer of the laminated electrophotographic photoreceptor of the present invention, the polycyclic quinone compound of the formula [I] may be added to the charge generating layer of the general formula 1.
By incorporating the ketazine-based compound (4), 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 has the above formula [1] as a charge generation material.
and optionally a polycyclic quinone compound of the general formula [II
It can be obtained by coating the ketazine compound of ] 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 vines used to form the charge generating layer by coating can be selected from a wide range 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 bisphenol A and phthalic acid, etc.),
Insulating resins such as polycarnate, I-lyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylgiridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, etc. can be mentioned. The resin contained in the charge generation layer is 8
Less than 0% by weight, preferably less than 40% by weight are 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 impropatol, 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, chloroform, mekylethochloride, etc. Aliphatic halodanized hydrocarbons, aromatic compounds such as lyhabenzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzenato, and the like can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using a coating method such as a Mayer 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 at a temperature of 30°C to 200°C for 5 minutes to 2
It can be carried out stationary or under a draft for a time range of hours.

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 the charge generation layer,
Moreover, it may be laminated thereunder. 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 of them 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.

Examples of resins that can be used as binders include acrylic resin, polyarylate, polyester, and polycarp. Insulating resins such as ester, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, privinyl formal, polysulfone, preacrylamide, polyamide, chlorinated rubber, or poly-N-vinylcarbazole, ?
Organic photoconductive polymers such as ribinyanthracene and polyvinylpyrene 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, steel, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used. In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic conductive particles (e.g., carbon black, silver particles, etc.) coated on plastic with a suitable binder; substrates made of plastic or paper impregnated with conductive particles; 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 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, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), I-urethane, 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, 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 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 of the charge transport layer negatively; after charging, when exposed to light, in the exposed area, the charge generation layer leaves the generated holes and the charge transport layer 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.

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 a polycyclic quinone compound of the formula [ID and a ketazine compound of the general formula [ID], as well as a hydrazone compound, a pyrazoline compound, if necessary. It can be formed by adding a compound, etc., 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, 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 resin such as polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile corimer, etc. The photosensitive layer can be formed by dissolving the photosensitive layer in an appropriate organic solvent and coating the photosensitive layer with the solution 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 thiammonia water 1g,
Water (z2zmJ) was applied by dip coating and dried to form a subbing layer with a coating weight of 1.0 and jil/m2.

Next, 1 part by weight of the same polycyclic quinone compound as in Example 1,
0.5 parts by weight of the above-mentioned exemplary compound (1) of general formula [II],
1 part by weight of polycarbonate resin and 3 parts by weight of 1,4-dioxane
0 parts by weight was dispersed for 4 hours using a sol 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 12 microns.

Corona discharge of -5 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 is determined by the amount of exposure (El/2) required to attenuate the potential vS after dark decay to 1/2.
．． 1ux-see). Rated 1,
7 These results were as follows.

Vonie sso gelt V5 knee 560 galt E 1/2: 3.61ux1ec Example 2 An ammonia aqueous solution of casein (casein x 1.2g, 28% ammonia water I11 water 222M) was applied by dip coating on an aluminum cylinder. , and dried to form a subbing layer with a coating weight of 1.0 g/m2.

Next, 1 part by weight of the same polycyclic quinone compound as in Example 1,
Butyral resin (S-LEC BM-2: Sekisui Chemical Co., Ltd.)
1 part by weight) and 30 parts by weight of isopropyl alcohol were dispersed for 4 hours using a Solmill disperser. This dispersion was first formed and coated on top of the nine sublayers by dip coating, 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 exemplary compound (1) of general formula (n), 1 part by weight of polysulfone resin (P1700, manufactured by Union Carbide Co., Ltd.) and 6 parts by weight of monochlorobenzene were mixed,
The mixture was stirred and dissolved using 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). The sensitivity is determined by the amount of exposure (El/2) required to attenuate the potential v5 after dark decay by half.
．． 1ux-sec).

These results were as follows.

Vo knee 580 volt v5: -560 volt E 1/2: 2.51ux-sea Example 3~
6 A photoreceptor was prepared in exactly the same manner as in Example 3, except that each of the exemplified compounds shown in Table 1 was used in place of the exemplified compound A(1) used in Example 3. We measured the characteristics of These results are shown in Table 1.

Table 1 3 (2) -610-6003,34(3)
-580-5602,8 5(4) -580-5653,1 6(5) -620-6103,0 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 . Its charging characteristics are shown in Table 3.

Table 2 2H5 Table 3 1 1 -590-565 4.3 2 2 -580-560 4.6 3 3 -565-550 5.0 4 4 -610-600 6.2 5 5 -585-555 5.7 6 6 -615-605 4.4 Example 7 The charge generation layer was further coated with the exemplified compound (1) of the general formula [ID]0.
The same photoreceptor as in Example 2 was prepared except that 5 parts by weight was added. Surface potential vo and VS% of this photoreceptor
In addition, the exposure amount E1/2 required to attenuate the potential V after dark decay to 1/2 was measured.

The results are shown below.

Vow-595 is Ruto V5: -575M Ruto E 1/2: 2.21ux-sec Example 1
As is clear from the results of Examples 1 to 7, it can be seen that the laminated electrophotographic photoreceptor of the present invention has extremely high sensitivity compared to the comparative example photoreceptors 1 to A6. Furthermore, Example 2
Using a Canon Co., Ltd. NP-1502 copying machine, image formation was repeated 20,000 times on the photoconductors 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 electronic device characterized by having a photosensitive layer comprising a polycyclic quinone compound represented by the following formula [I] and a ketazine compound represented by the following general formula [II] on a conductive support. Photographic photoreceptor. [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 polycyclic quinone compound represented by the following formula [I], and An electrophotographic photoreceptor characterized in that the charge transport 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.)