JPH06348052A - Organic electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To provide an org. electrophotographic photoreceptor having low dependency of the characteristics on the environment, less liable to a change in the characteristics at the time of repeated use and stably giving a high quality image. CONSTITUTION:In this org. electrophotographic photoreceptor with a photosensitive layer 3 formed by laminating an electric charge generating layer 4 and an electric charge transferring layer 5 on an electric conductive substrate 1 with an underlayer 2 in-between, the underlayer 2 contains alcohol-soluble polyamide and styrene-maleic acid resin and the electric charge generating layer 4 contains X-type metal-free phthalocyanine as an electric charge generating material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an undercoat layer for an electrophotographic organic photoreceptor, and more particularly to a material for the undercoat layer which eliminates the influence of humidity and improves the reliability of the electrophotographic organic photoreceptor.

[0002]

2. Description of the Related Art Electrophotographic photoconductors used in electrophotographic copying machines, printers and the like have become widespread using organic photosensitive materials which have advantages such as low cost and no pollution. The organic photoconductor for electrophotography includes a photoconductive resin type represented by PVK (polyvinylcarbazole), P
Charge transfer complex type represented by VK-TNF (2,4,7-trinitrofluorene), pigment dispersion type represented by phthalocyanine-binder, function separation type using a combination of a charge generating substance and a charge transporting substance, etc. Is known, and in particular, a function-separated type photoreceptor is drawing attention.

Such an organic function-separated high-sensitivity photoconductor has low chargeability and poor charge retention (large dark decay) when used in the Carlson process, and changes in characteristics upon repeated use. However, there are drawbacks in that density unevenness and fog occur on the obtained image, and background stain occurs in the case of the reversal development method. In order to eliminate the above drawbacks, it is known to provide an intermediate layer between the conductive substrate and the photosensitive layer as an undercoat layer of the photosensitive layer,
JP-A-48-47344, JP-A-52-2563
No. 8, JP 58-30757, and JP 58
-63945, JP-A-58-95351,
JP-A-58-98739 and JP-A-60-6
6258 discloses that a nylon-based resin intermediate layer is provided, and JP-A-49-69332 and JP-A-52-1138 disclose that a maleic acid-based resin intermediate layer is provided. JP-A-58-105155 discloses that a polyvinyl alcohol resin intermediate layer is provided.

[0004]

However, in the case of providing the undercoat layer as described above, since the insulating resin is often used as the material, the residual potential of the photoconductor becomes high and the obtained image Had a drawback that the contrast was poor. When a polyamide (nylon) having a low electric resistance is used, the residual potential can be controlled, but its water absorption is high, which causes a problem that the characteristics vary greatly depending on the humidity of the environment. For example, in the reversal development method, fog occurs at high humidity, and density decreases at low humidity. Further, polyamide has a problem in that it has a poor adhesion to an aluminum substrate having a rough surface, and cannot cover up pinholes on the substrate surface.

The present invention has been made in view of the above points, and an object thereof is to improve the polyamide used for the undercoat layer, thereby making it possible to obtain stable electrophotographic images with good resolution and little fluctuation due to environment. To provide an organic photoreceptor for use. Another object of the present invention is to provide an electrophotographic organic photoconductor having an undercoat layer having excellent adhesion to a conductive substrate.

[0006]

SUMMARY OF THE INVENTION According to the present invention, the above-mentioned problem is solved by an organic photosensitive material comprising a conductive substrate and a photosensitive layer in which a charge generation layer and a charge transport layer are laminated via an undercoat layer. In the present invention, the undercoat layer comprises an alcohol-soluble polyamide and a styrene-maleic acid resin, and the charge generation layer is an organic photoreceptor including X-type metal-free phthalocyanine as a charge generation substance.

The amount of the styrene-maleic acid resin contained in the undercoat layer is preferably in the range of 10% by weight or more and 40% by weight or less.

[0008]

When the undercoat layer is formed of a material obtained by adding styrene-maleic acid resin to polyamide, the adhesion between the undercoat layer and the conductive substrate is improved. In addition, good barrier properties occur. Furthermore, the dependence on water is eliminated and the dependence on the environment is reduced. Then, in particular, by combining with a charge generation layer using X-type metal-free fucorocyanine as the charge generation substance, characteristic fluctuation due to repeated use is reduced. Addition amount of styrene-maleic acid resin is 10% by weight
It is preferably in the range of 40 wt% or less. 1
If it is less than 0% by weight, the adhesion will not be improved, and fogging will occur in the image under high temperature and high humidity.
When it exceeds, the image density is lowered at a low temperature, which is not preferable.

[0009]

Embodiments of the present invention will be described below.
FIG. 1 is a schematic cross-sectional view of an embodiment of a photoconductor according to the present invention, in which a photosensitive layer 3 composed of a charge generation layer 4 and a charge transport layer 5 is formed on a conductive substrate 1 with an undercoat layer 2 interposed therebetween. Has been done.

As the conductive substrate 1, a metal such as aluminum, nickel, chromium, copper, silver, gold, platinum, or a metal oxide such as tin oxide or indium oxide is vapor-deposited or sputtered to form a film-shaped or cylindrical plastic. , Those covered with paper or the like, or plates of aluminum, aluminum alloy, nickel, stainless steel, etc., and those formed into a raw tube by a method such as extrusion or drawing. Surface roughness of blank tube is 0.5μ
It is set to about m to 10 μm. Further, when a smooth surface is required, a tube processed by cutting, superfinishing, polishing or the like can be used.

The undercoat layer 2 contains alcohol-soluble polyamide and styrene-maleic acid resin as main components. The undercoat layer 2 is formed by applying a coating solution in which a material containing both is dissolved in a solvent and then drying. The thickness of the undercoat layer is 0.1 μm
To about 5 μm, preferably 0.5 μm to 2 μm. The charge generation layer 4 is formed by applying and drying a liquid in which X-type metal-free phthalocyanine as a charge generation substance is dissolved and dispersed in a solvent together with an appropriate binder resin. A suitable film thickness of the charge generation layer is about 0.01 μm to 5 μm, preferably 0.03 μm to 2 μm.

The charge transport layer 5 is formed by coating and drying a coating solution prepared by dissolving or dispersing a charge transport material and a binder resin used as necessary in a suitable solvent. Examples of the charge transport material include hydrazone, pyrazoline, butadiene, anthracene, poly-N-vinylcarbazole, and derivatives thereof. As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinyl Vinylidene chloride, polyarylate resin,
Phenoxy resin, polycarbonate, cellulose acetate resin, ethylene cellulose resin, polyvinyl butyral,
Polyvinyl formal, polyvinyl toluene, poly-N
-A thermoplastic resin or thermosetting resin such as vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin, etc. is used.

If necessary, a plasticizer, an ultraviolet absorber, an antioxidant and a leveling agent may be used in the charge transport layer. Example 1 7 parts by weight of an alcohol-soluble graft copolymerized polyamide (CM8000, manufactured by Toray Industries, Inc.) and 3 parts by weight of a styrene-maleic acid resin (AP20, manufactured by BASF) are mixed solvent of 70 parts by weight of methanol and 30 parts by weight of dichloromethane. Was stirred at room temperature for 5 hours and dissolved to prepare a coating solution.

Surface roughness is 1.0 μm at maximum height Rmax
Aluminum alloy drum (outer diameter 60 mm, length 247
mm) and the coating solution was applied by dipping and dried at a temperature of 90 ° C. for 20 minutes to form an undercoat layer having a film thickness of 2 μm. On the undercoat layer, 100 parts by weight of X-type metal-free phthalocyanine,
A charge generation layer having a thickness of 0.2 μm was formed by a dip coating method using a liquid in which 100 parts by weight of a vinyl chloride-vinyl acetate copolymer and 100 parts by weight of dichloromethane were mixed and dispersed by a ball mill for 24 hours.

Subsequently, 100 parts by weight of a charge transporting material represented by the following chemical formula (I) and a polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Inc .; Iupilon Z-) are formed on the charge generating layer.
300) 100 parts by weight of dichloromethane was dissolved in 800 parts by weight of dichloromethane, and 0.5 parts by weight of silicone oil was further added to form a charge transport layer having a film thickness of 20 μm by a dip coating method to obtain a photoreceptor.

[0016]

[Chemical 1]

Comparative Example 1 Example 1 is the same as Example 1 except that the undercoat layer was formed only from an alcohol-soluble graft copolymerized polyamide (manufactured by Toray Industries, Inc .; CM8000) without using a styrene-maleic acid resin. A photoconductor was prepared in the same manner as in. The photoconductors of Example 1 and Comparative Example 1 thus obtained were mounted on a printer, respectively, and a printing test was conducted under various environments. The results are shown in Table 1.

[0018]

[Table 1]

As can be seen from Table 1, the photoconductor of Comparative Example 1 was unacceptable under high humidity of 90% RH (relative humidity) (fogging occurred). It can be seen that the photoconductor of Example 1 is more preferable although it can be practically used if it can be used favorably at 85% RH. Subsequently, when a continuous printing test of 10,000 sheets was conducted with a printer, a good image was obtained with the photoreceptor of Example 1, but the image density of the photoreceptor of Comparative Example 1 decreased after printing 1000 sheets. However, it was not practically preferable.

From the above results, the effect of the undercoat layer according to the present invention is clear. Example 2 Next, in order to investigate a suitable addition amount of a styrene-maleic acid resin, an alcohol-soluble polyamide (CM800
0) and the styrene-maleic acid resin (AP-20) in the ratio (weight ratio) as shown in Table 2, the undercoat layer was formed in the same manner as in Example 1 except that the undercoat layer was formed. Photoconductors having different styrene-maleic acid resin contents of the layers were prepared.

Similar to Example 1, these photoreceptors were subjected to a printing test by a printer in each environment and a continuous printing test of 10,000 sheets, and the results shown in Table 2 were obtained.

[0022]

[Table 2]

As shown in Table 2, when the content of the styrene-maleic acid resin in the undercoat layer is low, fog occurs in the image under high temperature and high humidity, and when the content is high, the print density decreases at low temperature. . Also, in the continuous printing test of 10,000 sheets,
Styrene-maleic acid resin content is 5% by weight or less, 4
If the content is 0% by weight or more, the image quality deteriorates. The content of the styrene-maleic acid resin is preferably in the range of 10% by weight to 40% by weight, more preferably 20% by weight to 30% by weight.
It is within the following range.

[0024]

According to the present invention, an undercoat layer is provided in an organic photoconductor for electrophotography, which comprises a photosensitive layer having a charge generation layer and a charge transport layer laminated on a conductive substrate through an undercoat layer. Comprises an alcohol-soluble polyamide and a styrene-maleic acid resin, and the charge-generating layer contains an X-type metal-free phthalocyanine as a charge-generating substance. Such an undercoat layer has a small change in electric resistance due to the environment, has a good barrier property, and has excellent adhesion to the conductive substrate and the photosensitive layer. By providing such an undercoat layer and a charge generation layer containing an X-type metal-free phthalocyanine as a charge generation material in combination, the electrophotographic characteristics are excellent, the environmental dependence of the characteristics is small, and the characteristics change during repeated use. It is possible to obtain an organic photoconductor for electrophotography, which has a small amount and can stably obtain a good image quality.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of a photoconductor of the present invention.

[Explanation of symbols]

 1 Conductive Substrate 2 Undercoat Layer 3 Photosensitive Layer 4 Charge Generation Layer 5 Charge Transport Layer

Claims (2)

[Claims] 1. An organic photoconductor for electrophotography comprising a photosensitive layer comprising a charge generation layer and a charge transport layer laminated on a conductive substrate via an undercoat layer, wherein the undercoat layer comprises alcohol-soluble polyamide and styrene. -A maleic acid resin, and the charge-generating layer contains X-type metal-free phthalocyanine as a charge-generating substance. 2. The organic photoreceptor for electrophotography according to claim 1, wherein the amount of the styrene-maleic acid resin contained in the undercoat layer is in the range of 10% by weight or more and 40% by weight or less.