JPH02296253A - Electrophotographic sensitive body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and in particular, an electrophotographic photoreceptor that has excellent charging stability even during repeated use and storage over a long period of time. It's about the body.

[Conventional technology]

Photoreceptors using organic photoconductive substances are being actively researched and developed because of their light weight, ease of film formation, manufacturing cost, and wide variation as organic compounds. For example, in the early days, there was a photoreceptor containing polyvinylcarbazole and 2,4,7-dolinitro-9-fluorenone described in Japanese Patent Publication No. 10496/1982;
A photoreceptor in which polyvinyl carbazole is sensitized with a pyrylium salt dye, as described in Japanese Patent No. 25658, or a photoreceptor having a eutectic complex as a main component has been proposed. However, these photoreceptors do not have sufficient sensitivity and durability.

Therefore, a functionally separated type photoreceptor in which a charge generation layer and a charge transport layer are separated was proposed, and the photoreceptor described in Japanese Patent Publication No. 55-42380 is a combination of chlordiane blue and a hydrazone compound, and a bisazo compound is used as the charge generation material. Described in JP-A-53-133445, JP-A-54-2
Known are those described in JP-A No. 1728, JP-A-54-22834, and as charge transport materials, those described in JP-A-58-198043 and JP-A-58-199352. However, even these functionally separated photoreceptors are not satisfactory in terms of mechanical and electrostatic durability. In recent years, as demands for durability have increased, ensuring charging stability has become an issue that cannot be ignored. That is, if the charging property decreases, it causes a decrease in the image density of the copy in a copying machine, and in the case of a laser printer using a reversal development method, it causes a decrease in image quality such as background staining. In order to solve these problems, it has been proposed to provide an intermediate layer between the conductive substrate and the photosensitive layer. However, when a high-resistance material with high barrier properties is used for the intermediate layer in order to stabilize chargeability, although the chargeability is improved, there are drawbacks such as a decrease in photosensitivity and an increase in residual potential. Furthermore, if a material with relatively low resistance that does not increase the residual potential is used, charging stability will be insufficient.

On the other hand, when a photoreceptor is actually used in a copying machine, the photoreceptor is exposed to ozone generated by a charger and is therefore subject to strong oxidation. In the case of organic photoreceptors in particular, this effect is large, and the constituent materials of the photoreceptor layer gradually oxidize and decompose, or oxidized substances adhere to the photoreceptor layer, resulting in deterioration of the performance and durability of the photoreceptor. It turns out. As a countermeasure to this problem, it has been proposed to add an antioxidant to the photosensitive layer as seen in JP-A-57122-444, JP-A-61-156052, and JP-A-62-39863. However, since antioxidants prevent the oxidation of other substances by undergoing oxidation themselves, deterioration of the antioxidant itself over time cannot be avoided, and the rate of deterioration increases particularly at high temperatures. Therefore, even in a photoreceptor containing an antioxidant, when stored for a long period of time at high temperatures, the effect of increasing durability is drastically reduced due to deterioration of the antioxidant.

Furthermore, in order to avoid the effects of ozone oxidation, etc.,
3-135955, it has been proposed to provide a resin having gas barrier properties (vinylidene chloride resin) on the charge transport layer. However, in this case as well, there are many problems such as the mechanical durability of the gas barrier resin and the weather resistance of the vinylidene chloride resin (because it is directly exposed to ozone).

Regarding mechanical durability, it has been proposed to provide a protective layer on the surface of the photosensitive layer. For example, a technique in which the film thickness of the protective layer is increased to improve the strength of the protective layer, and fog on copies due to residual potential is prevented by incorporating a resistivity reducing agent into the film (Japanese Patent Laid-Open No. 53-3338) Alternatively, a protective layer with high mechanical strength is provided with a thickness of 0.5 to 2 μm to improve the durability of the photoreceptor (Japanese Patent Application Laid-open No. 61-51155), or a fluorine-based resin is used. The abrasion resistance of the photoreceptor is improved by incorporating it into the protective layer and reducing the surface slip resistance (Japanese Patent Laid-Open No. 62-2
72281), but generally, as disclosed in JP-A-57-30846 and JP-A-58-60748, charge retention is applied to the photosensitive layer, or the photosensitive layer is coated when coating the protective layer. In order to provide protection against solvents, an intermediate layer is provided and a protective layer is provided on top of the intermediate layer. Although such photoreceptors have improved mechanical durability, improvements in electrostatic properties are still poor.

[Problem to be solved by the invention]

The present invention was made in order to solve the above-mentioned conventional problems, and specifically, it has excellent ozone resistance without impairing mechanical strength, and has excellent durability and storage stability during repeated use. The purpose of the present invention is to provide a photoreceptor for quantum photography.

[Means to solve the problem]

According to the present invention, in an electrophotographic photoreceptor in which at least a charge generation layer, a charge transport layer, an intermediate layer and a protective layer are laminated in sequence on a conductive support, the intermediate layer mainly contains a resin having gas barrier properties. Provided is an electrophotographic photoreceptor characterized by the following.

The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor in which at least a charge generation layer, a charge transport layer, an intermediate layer, and a protective layer are sequentially laminated on a conductive support, and the intermediate layer has gas barrier properties. By using resin as the main component, it has excellent ozone resistance without impairing mechanical durability, and has excellent charging stability even during repeated use.

The gas barrier resin that can be used in the present invention has a permeability of 0□ of 5 (cc/rrF/24hr/at
Any resin may be used as long as it has a dry temperature of 20° C. or less, but polyvinyl alcohol and ethylene-vinyl alcohol copolymer are particularly preferred.

In the case of a negatively charged laminated photoreceptor, (-) is used in a copy machine.
A large amount of ozone is generated by corona discharge.

For this reason, the photosensitive layer is affected by ozone, resulting in a decrease in sensitivity and an increase in residual potential. The gas barrier resin used in the present invention is difficult to transmit gases such as ozone.

Therefore, the present inventor provided an intermediate layer mainly composed of a gas barrier resin that does not allow gases such as ozone to pass through on the charge transport layer, thereby reducing the influence of ozone generated by (-) corona discharge on the photoreceptor. By providing a protective layer, preferably a low-resistance protective layer, in the intermediate layer in order to minimize the damage and improve mechanical strength, a photoreceptor with excellent mechanical durability and ozone resistance can be obtained. This discovery led to the completion of the present invention.

The thickness of the intermediate layer mainly composed of the resin having gas barrier properties is preferably 0.01 to 0.5 μm.

If it is less than 0.01 μm, the gas barrier effect will not be seen. On the other hand, if the thickness exceeds 0.5 .mu.m, although the gas barrier effect is sufficient, sensitivity decreases and residual potential increases, which is not preferable.

The protective layer according to the present invention preferably has a low resistance, and such a low-resistance protective layer is prepared by dissolving a binder resin in an appropriate solvent and then adding a conductive substance such as a metal oxide into the binder resin. It can be obtained by dispersing, coating this dispersion on the charge transport layer, and drying it.

Furthermore, various additives may be added to the protective layer for the purpose of improving dispersibility, adhesion, and smoothness. The thickness of the protective layer is 1 to 10 μm, preferably 2 to 7 μm.

If the thickness is less than 1p, the mechanical strength of the protective layer will be weak and the abrasion resistance will be low, making the protective layer ineffective for long-term use, and if it is more than 10p, charges will accumulate in the protective layer.
Residual potential increases during repeated use.

There are no particular restrictions on the structure of the protective layer, and the specific resistance is 10”-1.
A non-dispersive system may be used as long as the resistance is about 0.012 Ω·clll, preferably about 10 11 Ω'cm, and in this case, a photoreceptor with even higher sensitivity can be expected.

The charge generation layer in the present invention is formed from a charge generation substance or a resin binder together with the charge generation substance.

Examples of the charge generating substance that can be used in the present invention include an azo pigment having a carbazole core, an azo pigment having a styrylstilbene core, an azo pigment having a triphenylamine skeleton, an azo pigment having a dibenzylthiophene core, Azo pigments with oxadiazole cores, azo pigments with fluorenone cores, azo pigments with bisstilbene cores, azo pigments with distyryloxazole cores, azo pigments with distyrylcarbazole cores, diphenylamine cores Phthalocyanine pigments such as azo pigments having carbazole bone cores, trisazo pigments having carbazole bone cores, metal phthalocyanine pigments and metal-free phthalocyanine pigments, quinone pigments such as anthorone and pyranthrone, quinacridone pigments, bisbenzimidazole pigments, perylene pigments, indigo pigments, squalium. Known organic pigments such as pigments, quinoline pigments, biryllium salt pigments, and azulenium salt pigments can be used.

Among these charge-generating substances, azo pigments are particularly preferred, and among azo pigments, disazo pigments and trisazo pigments shown below are most preferred.

Specific examples of azo pigments are shown below.

Face 4F- To 111 111 Face JJIQ -1-J ``-m- Face 4L clothes 111 Δ--- Face 4L layer A Face'' [Fire face 4L gap Face 4 [To corner 111- -- Face 4 [Transition -1-to-11 These charge generating substances may be used alone or in combination of two or more.

The charge generation layer can be formed by dissolving or dispersing a resin binder and a charge generation substance in a suitable solvent, applying the solution, and drying the solution. As a solvent, benzene, toluene, xylene, methylene chloride, dichloroethane, monochlorobenzene, dichlorobenzene, ethyl acetate, butyl acetate, methyl ethyl ketone, dioxane, tetrahydrofuran, cyclohexanone, methyl cellosolve, ethyl cellosolve, etc. can be used alone or in combination. can.

The thickness of the charge generation layer is suitably 0.05 to 5 .mu.m, preferably 0.1 to 2.0 .mu.m. Further, it is appropriate to use the binder resin in an amount of 0 to 50 parts by weight, preferably 0 to 10 parts by weight, per 1 part by weight of the charge generating substance.

Further, a charge transport substance may be contained in the charge generation layer.

The charge transport layer can be formed by dissolving or dispersing a charge transport substance, a binder resin, etc. in a suitable solvent, coating the solution, and drying the solution. Moreover, a plasticizer and a leveling agent can also be added if necessary.

As the charge transport substance, poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethyl glutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives , imidazole derivatives, triphenylamine derivatives, 9-(p-diethylaminostyryl)anthracene, 1,1-bis-(4-dibenzylaminophenyl)propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene Examples include electron-donating substances such as derivatives.

These charge transport substances may be used alone or in combination of two or more.

As the solvent used in preparing the charge transport layer coating solution, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, etc. can be used.

The thickness of the charge transport layer is suitably about 5 to 100 μm. In addition, the binder resin is 0% per 1 part by weight of the charge transport material.
．． The amount is preferably 5 to 5 parts by weight.

Binder resins that can be used in the charge generation layer and the charge transport layer include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, and vinyl chloride. Vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyacrylate resin,
Phenoxy resin, polycarbonate, cellulose acetate,
Examples include thermoplastic or thermosetting resins such as ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenolic resin, and alkyd resin. It will be done.

If necessary, a subbing layer having a charge blocking function and an adhesive function can be provided between the conductive support and the photosensitive layer.

The undercoat layer, which is provided as needed, generally has a resin as its main component, but these resins have poor resistance to common organic solvents, considering that a photosensitive layer is coated on top of them using solvents. It is desirable that the resin be highly soluble. Examples of such resins include polyvinyl alcohol, casein, water-covering resins such as sodium polyacrylate, copolymerized nylon,
Alcohol-soluble resins such as methoxymethylated nylon,
Examples include curable resins that form a three-dimensional network structure, such as polyurethane, melamine resin, phenol resin, and epoxy resin.

In addition, fine powder pigments of metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the undercoat layer to prevent moire and reduce residual potential.

The photosensitive layer can be formed by immersing the conductive support in a coating solution for the charge generation layer, charge transport layer, or intermediate layer, or by spraying the coating solution onto the substrate.

The conductive support used in the electrophotographic photoreceptor of the present invention includes metal drums and sheets made of aluminum, brass, stainless steel, nickel, etc., materials such as polyethylene terephthalate, polypropylene, nylon, paper, and metals such as aluminum and nickel. Examples include sheet-like or cylindrical substrates made of plastic, paper, etc., which have been treated to be conductive by vapor deposition or by coating a conductive substance such as titanium oxide, tin oxide, or carbon black with a suitable inder.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Alkyd resin [Beccosol 1307-60-EL (
115 parts by weight of melamine resin [Super Beckamine G-821-60 (manufactured by Dainippon Ink Chemicals, Ltd.)] was dissolved in 150 parts by weight of methyl ethyl ketone, and oxidized to Titanium powder [Tie Bake CR
-EL (manufactured by Ishihara Sangyo Co., Ltd.)] was added and dispersed for 12 hours using a ball mill to prepare a coating solution for an undercoat layer.

This is made of a 0.2mm thick aluminum plate (A1080 (
(manufactured by Susumu Light Metal Co., Ltd.)] and dried at 140° C. for 20 minutes to form a subbing layer with a thickness of 2/111.

Next, 4 parts by weight of polyvinyl butyral resin [S-LEC BLS (manufactured by Tanezu Chemical Industry Co., Ltd.)] was added to 150 parts by weight of cyclohexanone.
10 parts by weight of a triazo pigment of exemplified azo pigment N039 was added thereto, dispersed for 48 hours in a ball mill, and further 210 parts by weight of cyclohexanone was added to give 3 parts by weight.
Time distribution was performed. Take this out into a container and the solid content will be 1.
It was diluted with cyclohexanone to a concentration of 5% by weight. The charge generation layer coating solution thus obtained was coated on the undercoat layer and dried at 130° C. for 20 minutes to form a charge generation layer having a thickness of 0.2 mm.

Next, polycarbonate resin [Panlite-1300
(manufactured by Ondai Kasei Co., Ltd.)] 10 parts by weight, silicone oil (KF
10.002 parts by weight of -50 (manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in 83 parts by weight of methyl chloride, and 7 parts by weight of the charge transport substance shown in structural formula (1) was added and dissolved to form a charge transport layer coating solution. Created. This was applied onto the charge generation layer and dried at 130°C for 20 minutes to a thickness of 20°C.
The charge transport layer of the door was formed.

Next, ethylene-vinyl alcohol copolymer [EVAL B
3 parts by weight of P-FIOI (manufactured by Kuraray) was added to n-BuOH
/n-Pr0f (/H20=18/42/40) was heated and dissolved in 100 parts by weight of a mixed solvent, coated on the charge transport layer, and dried at 140°C for 10 minutes to obtain a gas barrier property with a thickness of 0.2 mm. An intermediate layer was formed.

Finally, the protective layer coating solution shown below was dispersed on the intermediate layer using a ball mill for 120 hours, and the dispersion was coated at 120°C.
The electrophotographic photoreceptor of Example 1 was prepared by drying for 1 hour to form a five-tone protective layer.

[Protective layer coating liquid]

Resistance control agent 5n02 (Sb2.03 doped) fine powder (Mitsubishi Metals T-1) '13 parts Polyol-curing urethane resin 53 parts Hexamethylene diisocyanate 1 part Methyl ethyl ketone
46 parts Example 2, 3.4 The thickness of the intermediate layer with gas barrier properties was 0.057a, 0.
．． Electrophotographic photoreceptors of Examples 2 and 3.4 were prepared in the same manner as in Example 1 except that 1p and 0.31JIn were used.

Comparative Example 1.2 The thickness of the intermediate layer with gas barrier properties was 0.005 cm, 0.
．． An electrophotographic photoreceptor of Comparative Example 1.2 was prepared in the same manner as in Example 1 except that 6/I+n was used.

Comparative Example 3 Alcohol-soluble polyamide (CM-8
000 (manufactured by Toshisha Co., Ltd.) 33 parts by weight was added to MeOl (/n-Bu).
An electrophotographic photoreceptor of Comparative Example 3 was prepared in the same manner as in Example 1 except that the material was heated and dissolved in 100 parts by weight of a mixed solvent of OH=8/2.

Example 5 The electrophotographic photoreceptor of Example 5 was produced in the same manner as in Example 1, except that the exemplified azo pigment &39 was replaced with disazo pigment No. 1, and the charge transport material was replaced with one of the following structural formula (I[). It was created.

Comparative Example 4 Exemplary azo pigment Nα39 was replaced with No. 1 disazo pigment,
Furthermore, the electrophotograph of Comparative Example 4 was prepared in the same manner as in Example 1, except that the charge transport material was a compound of the structural formula [■], and the intermediate layer was made in the same manner as in Comparative Example 3, and CM-8000 was changed to 0.2 tones. A photoreceptor was created.

The electrostatic properties of the electrophotographic photoreceptor obtained as described above were measured using a dynamic method using 5P-428 (manufactured by Kawaguchi Denki Seisakusho). First, it was charged with an applied voltage of -6 KV for 20 seconds, dark decayed for 20 seconds, and then exposed to light for 30 seconds at a surface illuminance of 61 ux. This cycle was defined as one cycle, and the electrostatic characteristics at the initial stage and after 500 cycles were measured.

The charging potential is the surface potential V2 (V) after 2 seconds of charging, and the sensitivity = 35 = is the exposure amount E□/1G (1ux-sec) required for the surface potential to change from 1800V to 180V after exposure. The residual potential was determined by measuring the surface potential after 30 seconds of exposure. The evaluation results are shown in Table-1.

Table 1 (-) The influence of ozone generated by corona discharge can be minimized, and the increase in residual potential is small.
Moreover, it has excellent charging stability.

Furthermore, the gas barrier resin used in the present invention is resistant to coating solvents used when creating the protective layer, such as tetrahydrofuran, dichloromethane, 1,2-dichloroethane, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, butyl acetate, etc. Since the photosensitive layer is sufficiently protected, it has excellent durability.

〔Effect of the invention〕

As can be seen from the results obtained above, the electrophotographic photoreceptor of the present invention has an intermediate layer made of a gas barrier resin between the photosensitive layer and the protective layer.

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor in which at least a charge generation layer, a charge transport layer, an intermediate layer, and a protective layer are sequentially laminated on a conductive support, the intermediate layer is mainly composed of a resin having gas barrier properties. Characteristic electrophotographic photoreceptor. (2) The electrophotographic photoreceptor according to claim 1, wherein the resin having gas barrier properties is made of polyvinyl alcohol or an ethylene-vinyl alcohol copolymer.