JPH05150531A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enable the utilization of the photosensitive body with a positive charge and the formation of the body to a higher sensitivity and higher speed and to improve the durability by constituting the body of a base body, a specific photosensitive layer and a protective layer consisting of epoxy resin. CONSTITUTION:The photosensitive body has the base body, the photosensitive layer and the protective layer consisting of the epoxy resin provided on the photosensitive layer. The photosensitive layer is formed by dispersing a phthalocyanine based conductive material, a charge transfer material and tetracyanoethylene into a binder. The high sensitivity and the high speed responsiveness are improved by incorporating the tetracyanoethylene into the photosensitive layer. Further, the durability is improved by protecting the photosensitive layer with the epoxy resin. The axis of ordinate in the light attenuation characteristic diagram of the photosensitive body indicates surface potential and the axis of abscissa indicates an incident light quantity. In Fig. 1, 2 indicates an example of the photosensitive layer added with the tetracyanoethylene and 3 indicates the example of the photosensitive layer not added with the tetracyanoethylene.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor using a phthalocyanine photoconductive material powder as a charge generating material.

[0002]

2. Description of the Related Art Generally, in electrophotographic images, a photoreceptor is charged and exposed to form an electrostatic latent image, which is developed with a developer to be visualized, and the visible image is transferred onto a sheet. The transferred image is fixed and formed. Conventionally, selenium, selenium alloys, charge transfer complexes of polyvinylcarbazole and trinitrofluorenone, etc. have been used as photoconductive materials in the photosensitive layer of electrophotographic photoreceptors used for this type of purpose. .. However, selenium and selenium-based alloys require vapor deposition on a conductive support to be difficult to manufacture, and the vapor-deposited film has no plasticity and is highly toxic, requiring careful handling and being expensive. .. Further, the charge transfer complex of polyvinylcarbazole and trinitrofluorenone has a drawback that the recording speed is slow because of low photosensitivity. In order to solve the above-mentioned drawbacks, a laminated electrophotographic photoreceptor using phthalocyanine as a photoconductive material has been proposed. This type of photoconductor is excellent in processability and photosensitivity,
It is known to exhibit high sensitivity to light having a long wavelength such as a semiconductor laser.

[0003]

However, since the laminated type electrophotographic photoreceptor using phthalocyanine has photosensitivity only to negative charging, the specification of negative corona is inevitable. The negative corona has a problem that it generates a larger amount of ozone than the positive corona and the charging is unstable. Therefore, a photoreceptor having photosensitivity for positive charging is desired. As a positively charged photoconductor, a structure in which a phthalocyanine layer is laminated on a charge transport layer and a protective layer is further provided on the photoconductor has been proposed, but when the thickness of the protective layer is large, the sensitivity is significantly lowered, On the contrary, when the thickness is reduced, the protective layer is not easily scraped off by repetition, which causes a problem in durability.

Apart from that, as a positive charging type photoconductor, a publication {Japan Hardcopy '88 EP-
16}, there is a photoconductor formed by forming a photosensitive layer in which a phthalocyanine and a charge transport material are dispersed in a binder on a substrate. However, the electrons generated inside the photosensitive layer are the surface of the photosensitive layer. There is a problem of so-called induction effect in that it is difficult to be conducted to the surface, and as a result, it takes time for the surface charge to disappear, and there is a problem that it is difficult to increase the recording speed and a problem that performance deteriorates due to repeated use. In particular, there is a remarkable deterioration of the charging property due to repetition.

The present invention has been made to solve the above problems, and it is possible to obtain an electrophotographic photosensitive member which can be used by positive charging, realizes high sensitivity and high speed, and has improved durability. The purpose is.

[0006]

The electrophotographic photoreceptor of the present invention comprises a substrate, a photosensitive layer provided on the substrate, and a protective layer made of an epoxy resin provided on the photosensitive layer, wherein the photosensitive layer is a phthalocyanine-based material. The photoconductive material, the charge transport material, and tetracyanoethylene are dispersed in a binder.

[0007]

In the present invention, by containing tetracyanoethylene in the photosensitive layer, the sensitivity and the high speed response can be improved, and the durability can be improved by protecting the photosensitive layer with an epoxy resin. ..

[0008]

Examples The phthalocyanine-based photoconductive material according to the present invention may be any of phthalocyanines and their derivatives known per se, and examples thereof include metal-free phthalocyanines and copper phthalocyanines having high photosensitivity. The amount used is preferably 5 to 35% by weight, and if it exceeds 35% by weight, the charging property is poor, and if it is less than 5% by weight, the photosensitivity decreases.

The charge transport material according to the present invention is
Polycyclic aromatic compound or indole in the main chain or side chain,
Examples thereof include compounds having a nitrogen-containing cyclic compound such as carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole and triazole, and hydrazone compounds. The amount used is preferably 15 to 50% by weight, and if it exceeds 50% by weight, the charging property is poor.
The mechanical strength also decreases, and if it is less than 15% by weight, the photosensitivity decreases.

Generally, in a photoconductor composed of a charge generating material and a charge transporting material, in order for the photocarriers to be efficiently conducted from the charge generating material to the charge transporting material, the ionization potential of the charge generating material is the ionization potential of the charge transporting material. Greater than desired. In the present invention, phthalocyanine functions as a charge generation material, and its ionization potential is 5.0 to 5.4 eV. Therefore, as the charge transport material, a material having an ionization potential of 5.4 eV or less is used. Is desirable.

Examples of the binder according to the present invention include polycarbonate, butyral, polyarylate, polystyrene, polymethacrylic acid esters, polyester, polyvinyl acetate, acryl, polyvinyl butyral, polyvinylpyrrolidone, methylcellulose, cellulose esters and polysulfonic acid. , Styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer,
Thermoplastic resins such as polyamide, polyvinyl chloride, polyvinylidene, curable rubber, polyurethane resin, epoxy resin, alkyd resin, polyester resin, silicone resin, ester-melamine resin, acrylic-melamine resin, phenol resin and butyralu Although various resins such as thermosetting resins such as melamine resins can be used, thermosetting resins having high hardness are desirable from the viewpoint of improving durability.

A pigment shaker, a ball mill, a vibrating ball mill, a planetary ball mill, an attritor, a roll mill, a sand mill, a colloid is used to disperse a pigment containing a phthalocyanine photoconductive material, a charge transport material, tetracyanoethylene, a binder and a solvent. A conventional method such as a mill can be used. Wire bar coating, blade coating, knife coating, roll coating, screen coating, etc. are suitable for coating when the substrate is in the form of a sheet, and dip coating, ring coating, etc. when the substrate is in the shape of a cylinder. Is suitable. Further, the film thickness of the photosensitive layer is preferably 10 to 30 μm from the viewpoint of durability, photosensitivity and chargeability.

The substrate according to the present invention includes one having conductivity such as aluminum or aluminum alloy, or one having a drum or belt shape in which aluminum or the like is coated on a plastic by a vacuum deposition method. Those provided with an undercoat layer on the top can be used. A suitable thickness of the undercoat layer is usually 0.1 to 10 μm, and polyvinyl alcohol, casein, gelatin, nylon, aluminum oxide, nitrocellose, polyvinyl methyl ether,
Polyamide, methyl cellulose, ethylene-acrylic acid copolymer, butyral and polyurethane are suitable.

The tetracyanoethylene according to the present invention can be used as a commercially available product or after being purified, and is preferably 0.01 to 10% by weight. 0.01% by weight
If it is less than 10% by weight, the photosensitivity is not improved, and if it exceeds 10% by weight, the amount of water absorption is increased in a high temperature environment, and dark decay is significantly accelerated.

The epoxy resin used as the protective layer according to the present invention is bisphenol A type, bisphenol F type, bisphenol AD type, brominated epoxy resin, novolac epoxy resin, cycloaliphatic epoxy resin, glycidyl ester resin, glycidyl acyl resin. Various materials such as a heterocyclic epoxy resin can be used. Examples of the curing agent for the epoxy resin include acid anhydrides (phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylmedic anhydride, methyltetrahydrophthalic anhydride, succinic anhydride, maleic anhydride, pyromellitic anhydride. , Trimellitic anhydride), acyl hardeners (aliphatic amines, aromatic primary amines, tertiary amine hardeners, modified polyamines), dicyandiamide and organic acid dihydrazides.

The photoconductor of the present invention produces a small amount of ozone and has photosensitivity to positive charging which enables more stable charging, and is unique to a photoconductor using a phthalocyanine-based photoconductive material. It has a low induction effect, excellent photosensitivity and chargeability during continuous repetition, high physical strength of the photosensitive layer, and good printing durability. Further, even if the surface of the photosensitive layer is abraded by contact with the developing brush, transfer paper, cleaning blade, etc., the image quality can be maintained in good condition and can be used tens of thousands of times or more.

Embodiment 1. X-type metal-free phthalocyanine (manufactured by Dainippon Ink) 25 g, tetracyanoethylene {Tokyo Kasei, trade name: T-0077} 0.4 g, N, N-Di
phenyl-N, N-Bis (3-Methylph
enyl)-[1,1-Biphenyl] -4,4-D
iamine 27 g, acrylic resin solution {Mitsui Toatsu,
Trade name: 748-16AE} 38 g, butylated melamine resin solution {Mitsui Toatsu, trade name: 20SB} 7, 6 g,
Glass beads were added to a mixture of 200 g of toluene and 200 g of methyl ethyl ketone and dispersed with a paint shaker for 4 hours to prepare a photosensitive layer coating solution. This coating liquid was applied to an aluminum drum having a film of 1 μm of nylon {made by Toray, trade name: CM-8000}, dried, and baked at 150 ° C. to form a photosensitive layer. The film thickness is about 20 μm. Next, an epoxy resin solution consisting of 2 parts by weight of Epicoat 815, 1 part by weight of Epomate B002 and 400 parts by weight of ethanol is applied to the charge generation layer and dried at 120 ° C. to form a protective layer. To obtain a photoconductor for electrophotography. Most of the epoxy resin penetrated inside, and the photosensitive layer was protected inside.

Example 2. Instead of the charge transport material used in Example 1, it is represented by the following chemical formula.

[0019]

[Chemical 1]

Using the above materials, an electrophotographic photosensitive member of another embodiment of the present invention was manufactured in the same manner as in Example 1.

Example 3. A polyester resin (manufactured by Mitsui Toatsu Co., Ltd., trade name: P instead of the binder used in Example 1)
645} and a butylated melamine resin {manufactured by Mitsui Toatsu, trade name: 20HS} were used to prepare electrophotographic photoreceptors of other examples of the present invention in the same manner as in Example 1.

Example 4. Instead of the epoxy resin used in Example 1, Epicoat 1007 (Oilized Shell Chemistry) was used to prepare an electrophotographic photoreceptor of another example of the present invention in the same manner as in Example 1.

Comparative Example 1. An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the protective layer was not provided.

Comparative Example 2. An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that tetracyanoethylene was not added.

Each of the six types of photoconductors manufactured as described above was applied to an electrostatic recording test device (EPA-81) manufactured by Kawaguchi Electric Co., Ltd.
00), attenuation of the initial surface potential V ₀ which and V ₀ is the exposure amount E required to half _{1/2 (μJ} / cm ²⁾ and the surface potential after elapse 5 seconds at charging after dark (ДV ₀ ) And repeat 5000
The initial surface potential (ДV ₀ ⁵⁰⁰⁰ ) and the half-exposure amount (E _1/2 ⁵⁰⁰⁰ ) when measured repeatedly were measured, and the results are shown in Table 1.

[0026]

[Table 1]

According to this, it is understood that the electrophotographic photoreceptors of the examples of the present invention are excellent in sensitivity, response speed and durability. FIG. 1 is a light attenuation characteristic diagram of an electrophotographic photoreceptor for comparing the present invention with a conventional example, in which the vertical axis represents the surface potential and the horizontal axis represents the incident light amount. In the figure, 1, 2 and 3 are the characteristics of Example 1, Example 2 and Comparative Example 2 described above.

[0028]

As described above, the present invention provides a substrate,
A photosensitive layer provided on the base and a protective layer made of an epoxy resin provided on the photosensitive layer, wherein the photosensitive layer has a phthalocyanine photoconductive material, a charge transport material and tetracyanoethylene dispersed in a binder. By using the one having the above feature, it is possible to obtain an electrophotographic photosensitive member which can be used by positive charging, realize high sensitivity and high speed, and have improved durability.

[Brief description of drawings]

FIG. 1 is a light attenuation characteristic diagram of an electrophotographic photoreceptor for comparing the present invention with a conventional example.

[Explanation of symbols]

 1 Characteristics of Example 1 2 Characteristics of Example 2 3 Characteristics of Comparative Example 2

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kikuo Hayama 8-1-1 Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation Material Device Research Center (72) Inventor Hiromi Ueda 8-1-1 Tsukaguchihonmachi, Amagasaki MITSUBISHI ELECTRIC CORPORATION Material Devices Research Center

Claims (1)

[Claims] 1. A substrate, a photosensitive layer provided on the substrate, and a protective layer made of an epoxy resin provided on the photosensitive layer,
An electrophotographic photoreceptor, wherein the photosensitive layer comprises a phthalocyanine-based photoconductive material, a charge transport material and tetracyanoethylene dispersed in a binder.