JPH08328283A - Electrophotographic photoreceptor and method for manufacturing the same - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To obtain an electrophotographic photoreceptor having good charging characteristics, residual potential characteristics, and the like, and excellent stability in repeated use. The subbing layer contains 12/6/66 copolymerized nylon and methyl hydrogen polysiloxane treated titanium dioxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor and a method for producing the same, and more particularly to an electrophotographic photoreceptor using an undercoat layer and a method for producing the same.

[0002]

2. Description of the Related Art Generally, an electrophotographic process using a photoconductive photoconductor is one of the information recording means utilizing the photoconductive phenomenon of the photoconductor. The photoconductor is placed in a dark place and its surface is subjected to corona discharge. After charging, exposure is performed to selectively extinguish the electric charge in the exposed portion to form an electrostatic latent image. Colored charged fine particles (toner) are attached to the obtained electrostatic latent image by electrostatic attraction or the like to form a visible image. The photoconductive photoconductor used in the electrophotographic technique that goes through these series of processes is required to have the following basic characteristics. (1) It can be uniformly charged to an appropriate potential in a dark place, (2) it has a high charge retention ability in a dark place, and has little discharge of charges, and (3) it has excellent photosensitivity, For example, the light is rapidly erased by light irradiation. Furthermore, (4) the surface of the photoconductor can be easily destaticized, (5) the residual potential is small, (6) mechanical strength and flexibility are excellent, and (7) when repeatedly used. Electrical characteristics, especially chargeability, photosensitivity, residual potential, etc. do not fluctuate, and (8) stability, durability, etc. with resistance to heat, light, temperature, humidity, ozone deterioration, etc. The characteristics of are required. Currently used electrophotographic photoreceptors are constructed by forming a photosensitive layer on a conductive support substrate. However, in order to satisfy the following requirements, a photosensitive layer is provided between the conductive support and the photosensitive layer. A pulling layer is provided.

(1) To prevent the surface potential of the photosensitive layer from being lowered by injecting unnecessary charges from the conductive supporting substrate to the photosensitive layer, or to prevent the occurrence of image defects due to development. (2) To cover defects on the surface of the conductive support substrate. (3) To improve chargeability.

(4) Improving the adhesiveness of the photosensitive layer. (5) Improving coatability. Examples of the resin used as the undercoat layer include polyethylene, polypropylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin,
Resin materials such as silicone resin, polybutyral resin, and polyamide resin, and copolymers containing two or more of these repeating units, for example, vinyl chloride-vinyl acetate copolymer,
Acrylonitrile-styrene copolymer and the like, and further casein, gelatin, polyvinyl alcohol, ethyl cellulose and the like are used. Among these resins, polyamide resin is said to be particularly preferable (Japanese Patent Laid-Open No. 48-473).
44, JP-A-52-25638, JP-A-5
8-95351).

[0005]

However, in the electrophotographic photosensitive member using the polyamide resin or the like as the undercoat layer as described above, the volume resistance value is 10 ¹² to 10 ¹⁵ Ω · cm.
The thickness of the undercoat layer is about 0.3 μm
Unless the thickness is reduced to a certain level or less, residual potential is accumulated on the photoconductor and fog occurs in the image. On the other hand, when the thickness of the undercoat layer is reduced, it becomes difficult to control the thickness during coating, and it becomes impossible to cover defects on the conductive support substrate, and it is not possible to improve the charging property of the photoconductor. There was a problem.

Therefore, for the purpose of preventing image defects and improving residual potential, a mixture of titanium oxide and tin oxide 1 to
An electrophotographic photoreceptor having 10 parts by weight dispersed in 100 parts by weight of 8-nylon to form an undercoat layer is disclosed in JP-A-62-62.
Japanese Unexamined Patent Publication (Kokai) No. 2-181158 discloses the use of alumina-coated titanium oxide fine particles for improving the dispersibility of titanium oxide.

As described above, by mixing titanium oxide into the undercoat layer, the undercoat layer can be made thicker and the residual potential can be improved. However, depending on the environmental conditions, particularly in an environment of low temperature and low humidity. Below, there was a problem in that the repeatability was affected. Therefore, the undercoat layer improves the charging characteristics and residual potential of the photoconductor, has little residual potential accumulation even after repeated use, has little deterioration in photosensitivity, and has good repeated stability and environmental characteristics. There must be. Even if the resin used for the undercoat layer is in contact with the photosensitive layer, the charge-generating substance should not aggregate, resulting in coating failure and resulting in deterioration of photosensitivity and image unevenness. The layer must be stable and its resistance value does not change due to environmental conditions such as low temperature and low humidity and high temperature and high humidity. Further, it must be one that forms a barrier against hole injection from the conductive support, and it is needless to say that it must also have resistance to the solvent during formation of the photosensitive layer.

As the solvent used for the undercoat layer coating liquid, alcohol-based nylon such as methanol and ethanol is often used because the material used for the undercoat layer is mostly alcohol-soluble nylon. However, the alcohol-based alone has a problem that uneven coating occurs because evaporation is not uniformly performed after coating the undercoat layer. When the photosensitive layer comes into contact with the uneven coating portion of the undercoat layer, the charge generating substance aggregates, resulting in coating failure. As a result, a decrease in photosensitivity and image unevenness occur, which causes a problem.

The present invention has been made in view of the above points, and an object thereof is to optimize the combination of a resin and titanium oxide used in the undercoat layer to obtain excellent characteristics such as charging characteristics and residual potential, and repeated use. To provide an electrophotographic photoreceptor having excellent stability. Another object of the present invention is to provide a method for producing an electrophotographic photosensitive member having improved characteristics by improving the solvent used for forming the undercoat layer without causing coating unevenness.

[0010]

The above-mentioned object is to provide an electrophotographic photoreceptor having an undercoat layer, a charge generation layer and a charge transport layer on a conductive support substrate, wherein the undercoat layer is 12/6.
Achieved by including / 66 co-heavy nylon and titanium dioxide treated with methyl hydrogen polysiloxane. Further, it is more effective that the undercoat layer contains a styrene-maleic acid half ester copolymer.

Further, 12/6/66 copolymerized nylon and titanium dioxide treated with methylhydrogenpolysiloxane are dispersed in a mixed solvent of an alcohol type and a halogenated hydrocarbon type, and the solution is placed on a conductive supporting substrate. It is achieved by applying the undercoat layer to the undercoat layer.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the photoconductor of the present invention, an undercoat layer is formed on a conductive support substrate for an electrophotographic photoconductor, and a photosensitive layer is further formed on the undercoat layer. As the conductive support substrate, metal such as aluminum, aluminum alloy, copper, zinc, stainless steel, nickel, titanium, polymer material such as polyethylene phthalate, nylon, polystyrene or hard paper and metal foil such as aluminum is aminated. It is possible to use, for example, a polymer material impregnated with a conductive material, or hard paper or the like on which aluminum, an aluminum alloy, indium oxide, tin oxide, gold or the like is deposited. The shape thereof is not particularly limited, and examples thereof include a drum shape, a sheet or a seamless belt.

In the present invention, as the 12/6/66 copolymerized nylon, 12/6/66 nylon obtained by copolymerizing laurinlactam with caprolactam and hexamethylenediamine adipate in equal amounts is used as a copolymer of styrene-maleic acid half ester. The polymer is used by mixing 1 to 30% by weight. If the addition amount is outside this range, the film-forming property will be problematic.

Specific product names of titanium dioxide are:
"SI-UFTR-ZF" (available from Miyoshi Kasei Co., Ltd.) is a commercially available product obtained by subjecting rutile type ultrafine particle titanium oxide to dispersion treatment with methylhydrogenpolysiloxane by a known method. In the present invention, the content of titanium dioxide is preferably set within a range of 50 to 70% by weight in the undercoat layer, and the film thickness of the undercoat layer is preferably 0.1 to 10 μm, and preferably It is most effective when used in the range of 0.2 to 1 μm.

12/6/66 used in the present invention
Nylon is not particularly limited as long as it is soluble in alcohol and insoluble in the organic solvent used when forming the photosensitive layer. As a specific trade name, for example, "Daiamide T-171" (manufactured by Daicel Huls Co., Ltd.) can be mentioned. The styrene-maleic acid half ester copolymer is not particularly limited as long as it is soluble in alcohol and insoluble in the organic solvent used when forming the photosensitive layer. As a specific product name, for example, "Srapal AP-20"
(Manufactured by BASF).

In the present invention, the above titanium dioxide particles, 12/6/66 nylon and styrene-maleic acid half ester copolymer are dispersed in an organic solvent to prepare a coating solution for forming an undercoat layer, and this coating is applied. The undercoat layer can be formed by applying the liquid to the conductive support. If the solvent of the coating liquid for the undercoat layer is an alcohol-based solvent such as methanol or ethanol alone, coating unevenness occurs. However, it can be improved by using a solvent in which an alcohol-based solvent such as methanol and ethanol and a halogenated hydrocarbon-based solvent such as methylene chloride, dichloroethane, and chrychloroethylene are mixed.

Solvents used for obtaining the coating liquid for forming the undercoat layer include alcohols such as methanol, ethanol, isopropyl alcohol or n-propyl alcohol and halogenated hydrocarbons such as methylene chloride, dichloroethane and trichloroethylene. It can be used in any combination and in any proportion. Examples of methods for dispersing the coating liquid for the undercoat layer include a ball mill, a sand mill, a vibration mill, and an ultrasonic disperser. As the coating means, there are coating methods such as dip coater, blade coater, applicator, rod coater, knife coater, casting and spraying.

The electrophotographic photoreceptor of the present invention further has a photosensitive layer on the undercoat layer. The photosensitive layer may have a function-separated type laminated structure or a single-layer structure, but high sensitivity,
A negative charging type photosensitive layer is desirable because it has high durability.
FIG. 1 is a sectional view of an essential part showing an electrophotographic photosensitive member having a photosensitive layer having a laminated structure of a function separation type.

FIG. 2 is a sectional view of an essential part showing an electrophotographic photosensitive member having a single-layer photosensitive layer. 1 and 2, 1 is a conductive support substrate, 2 is an undercoat layer, 3 is a charge generating layer, 4 is a charge generating substance, 5 is a charge transporting layer, 6 is a charge transporting substance, and 7 is a photosensitive layer. Indicates. As the conductive support substrate,
For example, a metal material such as aluminum, stainless steel or nickel, or a polyester film having a conductive layer such as aluminum, copper, vanadium, tin oxide or indium oxide provided on the surface thereof, an insulating support substrate such as paper or glass is used. Among them, an aluminum pipe is a preferable supporting substrate.

In the functionally dispersed electrophotographic photoreceptor shown in FIG. 1, a charge transport layer 5 is formed on the charge generation layer 3 as a photosensitive layer. Examples of the charge generating substance 4 used in the charge generating layer 3 include selenium and its alloys,
Organic pigments such as cadmium sulfide, other inorganic photoconductive materials, phthalocyanine pigments, azo pigments, disazo pigments, trisazo pigments, squarylium pigments, pyrylium pigments, perylene pigments, and anthanthrone pigments can be used.
It is also possible to use one kind or a combination of two or more kinds. These binders are not particularly limited as long as they are electrically insulating and capable of forming a film, and those preferably used include polyvinyl ketal resins such as polyvinyl (pormar, acetal, butyral), acrylic resins,
Examples thereof include styrene resin, polyester resin, polycarbonate resin, vinyl chloride resin, vinyl acetate resin, and silicone resin. The amount of these binders is preferably 10% by weight or more and 300% by weight or less with respect to the charge generating substance.

As the film thickness of these, a dry film thickness of 0.01 to
The charge generation layer is formed by applying the film to a thickness of 2 μm. For the charge transport layer 5 provided on the charge generation layer 3, charge transport substances and binders generally used in organic electrophotographic photoreceptors can be used as they are, and examples thereof include pyrazoline compounds, hydrazone compounds, styryl compounds, triphenyl. A coating solution in which a methane compound or a triphenylamine compound is dissolved in a suitable solvent together with a binder having a suitable film-forming property, such as polyester resin or polycarbonate resin, is applied and dried to form a charge transport layer having a thickness of 5 to 50 μm. Form.
Further, the charge transport layer may contain various additives such as an antioxidant, if necessary.

In the present invention, a photosensitive layer is laminated on a conductive support substrate with an undercoat layer interposed, and the undercoat layer is 12/6.
Since it is composed of / 66 nylon and titanium dioxide treated with methylhydrogenpolysiloxane, it is possible to suppress a decrease in charging property and sensitivity and an increase in residual potential due to repeated use. Further, the titanium dioxide and 12/6/66 nylon are dispersed in a mixed solvent of an alcohol type solvent such as methanol, ethanol, isopropyl alcohol and n-propyl alcohol and a halogenated salt hydrocarbon type solvent such as methylene chloride, dichloroethane and trichloroethylene. Then, when the liquid is applied onto the conductive support, uneven coating of the undercoat layer is suppressed.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. Example 1 In a mixed solvent of 70 parts by weight of methyl alcohol and 30 parts by weight of dichloromethane, 3.15 parts by weight of 12/6/66 copolymerized nylon (Daiamide T-171 manufactured by Daicel Hüls) and styrene-maleic acid half ester copolymerization weight were used. Combined (BA
0.8 parts by weight of AP-20 manufactured by SF was mixed with 6.1 parts by weight of methylhydrogenpolysiloxane-treated titanium dioxide (SI-UFTR-ZF manufactured by Miyoshi Kasei). This mixture was dispersed in a ball mill for 10 hours to prepare an undercoat layer coating liquid containing 10% by weight of titanium dioxide.
The coating solution prepared in this way has an outer diameter of 30 mm and a length of 2
An aluminum cylinder having a thickness of 45.3 mm, a thickness of 1 mm and a surface roughness of 0.8 S was applied by dip coating to provide an undercoat layer having a dry thickness of 0.5 μm.

Next, 2.1 parts by weight of an azo compound having the following structure and 10 parts by weight of polyvinyl acetal (S-REC KS-1 manufactured by Sekisui Chemical Co., Ltd.) were dispersed in a sand mill together with 16 parts by weight of methyl ethyl ketone and 9 parts by weight of cyclohexanone. Then, 75 parts by weight of methyl ethyl ketone was subsequently added to obtain a coating liquid.

[0025]

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This coating solution was applied by dip coating on the above-mentioned undercoat layer to form a charge generation layer having a dry thickness of 0.2 μm.
Next, 10 parts by weight of a hydrazone compound represented by the following structure:
10 parts by weight of polycarbonate (Iupilon PCZ-300, manufactured by Mitsubishi Gas Chemical Co., Inc.) was added to 80 parts of tetrahydrofuran.
A coating liquid dissolved in parts by weight was applied onto the above charge generation layer to form a charge transport layer having a dry thickness of 20 μm to prepare a photoreceptor.

[0027]

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Example 2 A photoconductor was prepared in the same manner as in Example 1 except that the polycyclic quinone compound represented by the following structure was used as the charge generating substance.

[0029]

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Example 3 A photoconductor was prepared in the same manner as in Example 1 except that the azo compound having the following structure was used as the charge generation layer.

[0031]

[Chemical 4]

Comparative Examples 1 to 3 In the layer structure of Examples 1 to 3, an undercoat layer containing no titanium dioxide was applied to the undercoat layer to a thickness of 0.3 μm to prepare photoconductors. Comparative Examples 4 to 6 In the layer structure of Examples 1 to 3, photoconductors containing no undercoat layer were prepared. Comparative Example 7 In the layer structure of Example 1, the undercoat layer was dispersed and produced only with methyl alcohol, and a photoreceptor was similarly produced. Comparative Example 8 In the layer structure of Example 1, an undercoat layer containing no styrene-maleic acid half ester copolymer in the undercoat layer was applied to a thickness of 0.5 μm to prepare a photoreceptor. Comparative Example 9 In the layer structure of Example 1, an undercoat layer containing titanium dioxide not treated with methylhydrogenpolysiloxane was applied in a thickness of 0.5 μm to prepare a photoreceptor. Comparative Example 10 In the layer structure of Example 1, an undercoat layer containing titanium dioxide subjected to conductive gold plating treatment was applied to the undercoat layer to a thickness of 0.5 μm to prepare a photoreceptor.

The photoreceptor prepared as described above was attached to a commercially available copying machine (Z-25 Sharp Co., Ltd.), and L, L
(Low temperature, low humidity: 5 ° C, relative humidity 20%), N, N (normal temperature, normal humidity: 22 ° C, relative humidity 50%), H, H (high temperature,
The following characteristics were evaluated under each atmosphere of high humidity: 40 ° C. and relative humidity of 85%). Electrical Characteristics The initial dark potential (Vd) and light potential (Vi) of the photoconductor are set to -600V and -30V, respectively, and the light intensity required to reach -300V from -600V by changing the light intensity of the irradiation light ( 1x · s) is the sensitivity. Further, the potential when the exposure amount is 10 (1 × · s) is defined as the residual potential. After repeating this operation 50,000 times, the dark part potential (V
d), bright part potential (Vi), sensitivity, and residual potential (Vr) were measured.

Image Characteristics Initially and after repeating 50,000 times, a black solid image and a white solid image were evaluated. Coating solution stability Using the coating solution for the undercoat layer immediately after the formation and after 30 days from the formation, a photoconductor was prepared, and the appearance of the photoconductor was visually evaluated.

Adhesion was carried out according to JIS K5400. Using a thin blade cutter, form grooves that reach the aluminum cylinder at 1 mm intervals in the axial and rotational directions of the photoconductor, and attach tape every 24 mm x 25 mm using a tape with a width of 24 mm, peel off in the rotational direction, and pull down with the aluminum cylinder. The adhesion between the layers was evaluated. The photoconductor in which peeling occurred was regarded as defective.

[0036]

[Table 1]

The photoreceptors of Examples 1, 2, and 3 showed no significant change in electrical characteristics after repeating 50,000 times, and had good image characteristics, stability of the coating liquid for the undercoat layer, and good adhesion. Example 4 The coating liquid for the undercoat layer prepared in Example 1 was 30 mm × 30.
mm × 1 mm aluminum plate, dry thickness of
An undercoat layer of 5 μm was provided.

Next, 5 parts by weight of an amine compound having the following structure, 5 parts by weight of polycarbonate (Iupilon PCZ-300, manufactured by Mitsubishi Gas Chemical Co., Inc.), and 0.3 parts by weight of butylated hydroxytoluene are added to 45 parts by weight of tetrahydrofuran. Dissolved in.

[0039]

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An azo compound having the following structure was added to this solution.
Add 5 parts by weight and disperse in a ball mill for 18 hours. Apply this dispersion on the undercoat layer with a wire bar, and leave at 110 ° C.
Was dried for 60 minutes, a photosensitive layer having a thickness of 20 μm was provided, and a flat-layer photosensitive member having a single layer structure was produced.

[0041]

[Chemical 6]

Comparative Example 11 In the layer structure of Example 4, a flat plate photosensitive member not including the undercoat layer was prepared. With respect to the thus prepared flat plate photosensitive member, the repeating characteristics with respect to the charging potential and the residual potential and the half-attenuation exposure amount were measured. An electrostatic charging test device EPA8100 (manufactured by Kawaguchi Electric Co., Ltd.) was used for these measurements.

Corona discharge on the surface of the photosensitive member is +6 KV, 10
It was charged for 2 seconds and then exposed to white light with an illuminance of 2 lx, and the exposure amount (half-attenuation exposure amount) lx · s required until the charged position reached half was measured. After charging, the illuminance is 2
The surface potential after irradiation with 1x white light for 5 seconds was measured as the residual potential. The results of these measurements are shown in Table 2.

[0044]

[Table 2]

The photoreceptor according to Example 4 did not show a large change in charge position even after repeating 5000 times.

[0046]

The photosensitive layer is laminated on the conductive support substrate through the undercoat layer, and the undercoat layer is composed of 12/6/66 nylon and methyl hydrogen polysiloxane-treated titanium dioxide. It is possible to suppress image defects and the like due to deterioration of charging performance during use and increase of residual potential, and it is possible to obtain an electrophotographic photosensitive member excellent in repeated stable production under any environment.

Also, the titanium dioxide and 12/6/66
Nylon is dispersed in an alcohol solvent such as methanol, ethanol, isopropyl alcohol and n-propyl alcohol and a halogenated hydrocarbon mixed solvent such as methylene chloride, dichloroethane and trichloroethylene,
By coating the liquid on a conductive support substrate, the coating unevenness of the undercoat layer is eliminated, and an electrophotographic photoreceptor having excellent image characteristics can be manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a function-separated type electrophotographic photoconductor of the present invention.

FIG. 2 is a cross-sectional view of essential parts showing a single-layer type electrophotographic photoconductor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive supporting substrate 2 Undercoat layer 3 Charge generating layer 4 Charge generating substance 5 Charge transporting layer 6 Charge transporting substance 7 Photosensitive layer

Claims (3)

[Claims] 1. An electrophotographic photoreceptor having an undercoat layer, a charge generation layer and a charge transport layer on a conductive support substrate, wherein the undercoat layer is a 12/6/66 copolymerized nylon and methyl hydrogen polysiloxane. An electrophotographic photosensitive member comprising treated titanium dioxide. 2. The electrophotographic photoreceptor according to claim 1, wherein the undercoat layer further contains a styrene-maleic acid half ester copolymer. 3. A 12/6/66 copolymerized nylon and titanium dioxide treated with methylhydrogenpolysiloxane are dispersed in an alcohol-based and halogenated hydrocarbon-based mixed solution and the solution is coated on a conductive support substrate. And a subbing layer are provided.