JPH0862876A - Organic photoconductor for electrophotography - Google Patents

Abstract

(57) [Abstract] [Purpose] Using a substrate containing a cross-linking type PPS resin as the main component, the adhesion between the substrate and the charge generation layer is good, there is no problem due to peeling, and there is little dark decay, which is good. A lightweight and inexpensive organic photoreceptor capable of obtaining various images is obtained. [Structure] The surface of a conductive substrate 1 containing a cross-linking type PPS resin as a main component is subjected to ultraviolet irradiation treatment or corona discharge treatment, and a film is formed thereon. A charge generating layer 2 having a thickness of 0.5 μm or more and 2 μm or less is formed by coating, and a charge transporting layer 3 is formed thereon by coating to form a photoreceptor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic photoconductor for electrophotography, and more particularly to an organic photoconductor using a conductive substrate containing an organic material as a main component.

[0002]

2. Description of the Related Art Organic photoconductors for electrophotography used in electrophotographic devices such as copying machines and printers to which electrophotographic technology is applied are mainly composed of a substrate and an organic material including an organic photoconductive material provided thereon. And a photosensitive layer as a component. The substrate is required to function not only as a support for the photosensitive layer but also as an electrode of the photosensitive body. The base material is aluminum, stainless steel, copper, nickel, zinc, iron,
Metals such as gold and titanium, glass, resins, and the like that have been subjected to a conductive treatment are used, but aluminum or aluminum alloys have been frequently used. The shape of the substrate may be any of a cylinder, a cylinder, a plate, a film, and the like, but when the photosensitive layer is formed on the outer surface of the cylinder or the cylinder to form a seamless layer, a space factor is good, and repeated use is not required. This is preferable because it has many advantages in terms of device design such as ease of use.

However, there is a problem in that it is costly to form a metal into a columnar shape or a cylindrical shape with high dimensional accuracy (for example, roundness ± 50 μm or less, diameter dimensional accuracy ± 40 μm or less). Another problem is that it is heavy. Further, in the organic photoreceptor,
In order to obtain high performance, the photosensitive layer is usually composed of a charge-generating layer and a charge-transporting layer in which functionally separated layers are laminated, and generally, a thin film of a submicron order is formed on a substrate. A charge generation layer is formed by coating, and the film thickness is several tens of μm on it.
Is formed by coating. It is important that the surface of the underlying substrate is appropriate, has a uniform roughness, and is homogeneous in order to form a thin, charge-generating layer of submicron order with a uniform thickness and with good adhesion. Is. In addition, in terms of the characteristics of the photoconductor, the charge injection property from the substrate is also important, and the surface performance of the substrate greatly affects the electrophotographic properties of the photoconductor. For this reason, it is necessary to individually perform high-precision machining in order to make the substrate surface have an appropriate and uniform surface roughness, and the surface may be oxidized or deteriorated under the influence of moisture and oxygen in the atmosphere. It is necessary to form an anodic oxide film or the like on the surface in order to prevent this and to control the charge injection property, and there is a problem that the number of manufacturing steps is high and the manufacturing cost is high.

On the other hand, the base made of a resin material is
By injection molding, it is relatively easy to obtain a cylinder or cylinder having a good surface shape with high dimensional accuracy, and there are advantages that surface deterioration is small and weight is light. Polyphenylene sulfide (PPS) resin, for example, is known as a resin material suitable for the base of the photoreceptor (Japanese Patent Publication 2-1).
7026).

By the way, since the volume resistivity of PPS resin is usually as high as 10 ¹⁰ Ω · cm to 10 ¹³ Ω · cm, for example, carbon black is added to the PPS resin to give conductivity. . In order to obtain good image quality and printing characteristics, the volume resistivity of the substrate should be at least 10 ⁴ Ω ・
It is required to be less than or equal to cm. When it is about 10 ⁵ Ω · cm or more, when the photoconductor is exposed and when the charge is removed, it is difficult to discharge charges to the substrate and the residual potential becomes large, so that good images and printing cannot be obtained.

[0006]

However, when a substrate containing a PPS resin as a main component is used, the carbon powder added to the PPS resin has the property of injecting free carriers from the substrate to the photosensitive layer side in the presence of an electric field. Therefore, the dark decay of the obtained photoconductor becomes large, there is no charge potential, and it is impossible to obtain a practical image especially when the thickness of the charge generation layer is as thin as less than 0.5 μm. There was a problem. Further, due to the good chemical stability and chemical resistance of the PPS resin, the adhesiveness of the charge generation layer mainly composed of an organic material formed by coating on the PPS resin is poor and the charge generation layer of the photoconductor is not used. There is also a problem that peeling is likely to occur, causing an image defect and a device failure.

Recently, there has been a need for a substrate having a small diameter (outer diameter of about 30 mm or less), a thin wall (thickness of about 3 mm or less) and a long shape (several hundred mm in length). . When the substrate is made of an ordinary linear-type PPS resin-based material, in the case of such a thin and long substrate, the solvent of the coating liquid is used in the process of coating and forming a layer of the organic material on the substrate. A slight deformation that is not a problem usually caused by heating or heating becomes a problem, and it is difficult to maintain the dimensional accuracy required for the substrate.

The present invention has been made in view of the above points, and increases dark decay, deteriorates adhesiveness of a charge generation layer, and has dimensional accuracy when a substrate containing a PPS resin as a main component is used. SUMMARY OF THE INVENTION An object of the present invention is to provide a light-weight and inexpensive organic photoreceptor in which good image quality is obtained, a problem due to peeling of a charge generation layer does not occur, and a problem is solved.

[0009]

According to the present invention, the above-mentioned problems are solved in an organic photoreceptor in which a charge generating layer containing an organic material as a main component and a charge transporting layer are sequentially formed on a conductive substrate. A film of a charge generation layer in which the conductive substrate contains a cross-linked PPS resin as a main component, the surface of which is subjected to ultraviolet irradiation treatment or corona discharge treatment, and which has a high ratio of a resin binder to a charge generation material. Thickness 0.5
The problem can be solved by using an organic photoconductor for electrophotography, which has a thickness in the range of 1 μm to 2 μm.

As the carbon black added to the cross-linking type PPS resin for imparting conductivity to the substrate, a highly conductive carbon black having a volume resistivity of 10 ^-1 Ω · cm or less is preferable. Ultraviolet rays containing wavelengths of 184.9 nm and 253.7 nm are suitable as the ultraviolet rays used for irradiating the surface of the conductive substrate.

Further, calcium carbonate, clay or the like may be added to the resin in order to uniformly disperse the carbon black in the resin. The average particle size of carbon black is 20
nm to 50 nm is preferable. Further, glass fibers may be included to enhance the mechanical strength.

[0012]

[Function] The PPS resin forming the substrate is cross-linked PP
By using the S resin, heat resistance and chemical stability are further improved, so that the deformation of the substrate when forming the charge generation layer and the charge transport layer thereon is reduced, and it is required as the substrate of the photoconductor. It is possible to maintain dimensional accuracy.

Then, by irradiating the surface of the substrate with ultraviolet rays or performing corona discharge, ozone is generated from oxygen in the atmosphere near the surface of the substrate, and by the action of this ozone, the outermost surface of the cross-linked PPS resin is removed. The molecular chain is cleaved, and the action of moisture in the atmosphere is added, and -OH group, -COOH
A polar group such as a group is generated and the surface is activated, the wettability of the surface is significantly improved and the adhesiveness is improved without impairing the necessary function as a substrate, and in addition to such surface modification By setting the film thickness of the charge generation layer having a high ratio of the resin binder to the charge generation material to 0.5 μm or more,
It is possible to suppress an increase in dark attenuation. If the film thickness of the charge generation layer is too thick, the charging characteristics of the photoconductor will be deteriorated and the image density will be low.

The volume resistivity of the cross-linked PPS resin is 1
Carbon black is added to impart conductivity of 0 ⁴ Ω · cm or less, but the addition amount can be reduced by using highly conductive carbon black having a volume resistivity of 10 ⁻¹ Ω · cm or less. It is preferable because the viscosity and fluidity of the material can be adjusted to a range suitable for injection molding.

[0015]

1 is a schematic cross-sectional view of an embodiment of a photoconductor according to the present invention, which comprises a base 1 on which a charge generation layer 2 and a charge transport layer 3 are sequentially laminated. Example 1 Crosslinked PPS (manufactured by Toray Industries, Inc .; M2900) 60
25 parts by weight of carbon black having a volume resistivity of 10 ^-1 or less (Cabot Furnace Carbon XC-72) and 15 parts by weight of glass fiber are added to the parts by weight, and the mixture is kneaded and injection molded into a cylindrical shape to obtain a substrate. An ultraviolet irradiation device for low pressure mercury lamp (manufactured by Sun Engineering Co., Ltd .; model SU)
V200NS) is used, the distance between the low-pressure mercury lamp and the substrate is set to 20 mm, and 184.9n from the 200-W low-pressure mercury lamp.
Ultraviolet rays containing m and a wavelength of 253.7 nm were irradiated for 20 seconds.

X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals Co., Ltd .;
FASTGEN BLUE 8120) 10 parts by weight, polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd .; Eslec BL1) 30 parts by weight, and a mixture prepared by mixing and dispersing for 1 hour in a sand mill device by dip coating. Method, and baked at a temperature of 80 ° C. to form a charge generation layer having a film thickness of 0.5 μm. On this charge generation layer, 10 parts by weight of a hydrazone compound represented by the following structural formula (I) (manufactured by Fuji Electric Co., Ltd.), a polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Inc .; Iupilon PCZ)
A coating liquid consisting of 10 parts by weight and 100 parts by weight of dichloromethane was applied by a dip coating method, followed by baking at a temperature of 100 ° C. to form a charge transport layer having a film thickness of 20 μm to prepare a photoreceptor.

[0017]

Embedded image

Regarding the photoconductor thus produced,
The adhesiveness of the photosensitive layer is checked by a goggles (JIS K5400
8.5.1) and printed on a commercially available semiconductor laser beam printer. The white paper density and black paper density were measured with a Macbeth densitometer to evaluate the printing characteristics. Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1 except that the surface of the substrate was not irradiated with ultraviolet rays, and the adhesiveness and the printing characteristics were evaluated in the same manner as in Example 1. .

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1 except that the film thickness of the charge generation layer was 0.3 μm.
Adhesion and printing characteristics were evaluated in the same manner as in Example 1. Example 2 Same as Example 1 except that the amount of polyvinyl butyral resin added to the coating liquid for the charge generation layer was 40 parts by weight and the film thickness of the charge generation layer was 1.1 μm. A photoconductor was prepared and evaluated for adhesiveness and printing characteristics in the same manner as in Example 1.

Comparative Example 3 A photoconductor was prepared in the same manner as in Example 2 except that the thickness of the charge generation layer was changed to 2.2 μm.
Adhesion and printing characteristics were evaluated in the same manner as in Example 1. Table 1 shows the evaluation results of the above photoreceptors. In Table 1, the presence / absence of ultraviolet irradiation of each photoconductor and the thickness of the charge generation layer are also shown.

[0021]

[Table 1]

As shown in Table 1, the photoreceptor of Comparative Example 1 in which the surface of the substrate was not irradiated with ultraviolet rays showed a poor goggles test result of 95/100 and the adhesion between the substrate and the photosensitive layer was poor. I understand. In addition, the thickness of the charge generation layer is 0.3.
The photoreceptor of Comparative Example 2 having a small thickness of μm has a large dark decay and a poor white paper density even though the surface of the substrate is irradiated with ultraviolet rays. Further, the photoconductor of Comparative Example 3 in which the thickness of the charge generation layer is as thick as 2.2 μm also has a poor white paper density. The surface of the substrate is irradiated with ultraviolet rays and the thickness of the charge generation layer is 0.5 μm or more and 2 μm or less.
The effect of making m or less is clear.

Example 3 The same substrate as in Example 1 was used, and the surface thereof was subjected to corona discharge treatment (discharge voltage of about 10 kv, gap between discharge electrode and substrate of 2 mm to 3 mm, discharge time of 30 seconds). . A charge generation layer was formed on this substrate in the same manner as in Example 1,
A charge-transporting layer was sequentially laminated to prepare a photoreceptor, and the adhesiveness and printing characteristics of the photosensitive layer were evaluated in the same manner as in Example 1.
The results are shown in Table 2.

[0024]

[Table 2]

As can be seen from Table 2, in Example 3 as well, the same results as in Example 1 were obtained, and it was found that the corona discharge treatment had the same effect as the ultraviolet irradiation treatment.

[0026]

According to the present invention, in an organic photoconductor in which a charge generating layer and a charge transport layer containing an organic material as a main component are sequentially formed on a conductive substrate, the conductive substrate is a cross-linked polyphenylene. A substrate having a sulfide resin as a main component, the surface of which is modified by ultraviolet irradiation treatment or corona discharge treatment, and the ratio of the resin binder to the charge generation material is high, and the thickness of the charge generation layer is 0.5.
The photosensitive member is in the range of μm or more and 2 μm or less.

By using the photoreceptor having such a structure, a base material containing a cross-linking type polyphenylene sulfide resin as a main component is used, and the adhesion between the base material and the charge generation layer is good and no problem due to peeling occurs. It is possible to obtain a good image with little dark decay, and to obtain a lightweight and inexpensive organic photoreceptor.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the configuration of an embodiment of a photoconductor of the present invention.

[Explanation of symbols]

 1 Conductive Substrate 2 Charge Generation Layer 3 Charge Transport Layer

Claims (3)

[Claims] 1. An organic photoreceptor comprising a conductive substrate, on which a charge generation layer containing an organic material as a main component and a charge transport layer are sequentially formed, wherein the conductive substrate contains a cross-linked polyphenylene sulfide resin as a main component. , The surface of which is a substrate that has been subjected to ultraviolet irradiation treatment or corona discharge treatment, and the thickness of the charge generation layer in which the ratio of the resin binder to the charge generation material is high is within the range of 0.5 μm or more and 2 μm or less. An organic photoconductor for electrophotography, which is characterized by: 2. The electrophotographic organic photoconductor according to claim 1, wherein the electroconductive substrate contains a highly electroconductive carbon black having a volume resistivity of 10 ⁻¹ Ω · cm or less. 3. The ultraviolet light applied to the surface of the conductive substrate is 1
3. The organic photoconductor for electrophotography according to claim 1, which is an ultraviolet ray having wavelengths of 84.9 nm and 253.7 nm.