JPS5911101B2 - Photosensitive plate for electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photosensitive plate for electrophotography, and more specifically, a photoconductive layer comprising an inorganic glass binder having a specific composition ratio, a photoconductive substance dispersed therein, and sintered. The present invention relates to an electrophotographic photosensitive plate provided on a conductive support.

Conventionally, various insulating binders have been used to finish fine powders of cadmium sulfide, zinc oxide, and other inorganic photoconductive substances into photosensitive plates.

This binder, which has properties as a dispersion medium, has a high dielectric constant and excellent insulating properties, and is preferably colorless and transparent and has excellent film-forming ability. Therefore, in general, natural or synthetic resins are most commonly used, and among them, silicone resin, styrene rubber, and vinyl acetate resin are often used. However, when such a resin binder is used, the photosensitive plate has poor mechanical strength, abrasion resistance,
There are problems with heat resistance, corona resistance, solvent resistance, etc., and therefore there has been a demand for an electrophotographic photosensitive plate that satisfies these properties. To meet these demands, a ceramic photosensitive plate using an inorganic binder has been proposed (Japanese Patent Publication No. 17186/1986).

This ceramic photosensitive plate has excellent abrasion resistance and mechanical strength, but it has a binder (inorganic glass binder).
Since a large amount of alkaline substances are used in the photoconductive layer, the dark resistance is not high, and when baking is performed to obtain the photoconductive layer, the alkaline substances inevitably tend to float to the surface. The disadvantage is that it is difficult to form a uniform layer. In addition, since the surface resistance is low, surface treatment such as para-polishing with a red iron is required, and there is a drawback that a photosensitive plate cannot be easily obtained. The present inventor has been conducting research on inorganic binders that can be used in electrophotographic photosensitive plates for a long time, and found that bismuth oxide (50 to 90% by weight) and boron oxide (9 to 30% by weight) are used as inorganic binders. It has been found that by using an inorganic glass binder containing 250.001 to 5% by weight of cobalt oxide, a photoconductive layer can be obtained that fully satisfies various performances.

The present invention has been completed based on this. That is, in the present invention, Bi20350 to 90% by weight, 30B20
A photoconductive substance is dispersed in an inorganic glass binder containing 0.001 to 5% by weight of Cd and 0.001 to 5% by weight as essential components, and 00 to 30% by weight of Cd and 00 to 30% of Ca added as necessary. Dry it at a low temperature, preferably on a conductive support, within a temperature range where the conductive material does not change in quality, and dry it at a temperature of 400 to 800 °C just before cracks appear.
This is an electrophotographic photosensitive plate obtained by sintering within the temperature range of .

This invention is most characterized by the composition of the inorganic glass binder, and the main component is bismuth oxide 50-90%.
Weight% preferably 60-70% by weight, boron oxide 9-3
0% by weight, preferably 10-20% by weight, COOO. O
Ol~5% by weight, preferably 0.1~1% by weight. To this may be further added ~30% by weight CdOO, preferably 10-20% by weight, and ~30% by weight, preferably 1-5% by weight CaOO. Addition of CdO is advantageous because it improves electrostatic properties, and addition of CaO is effective because it improves electrostatic properties and hardness. The softening point of an inorganic glass binder with such a composition is 400~
Since the temperature is relatively low at 800°C, CdS.
The firing temperature for producing a photosensitive plate by dispersing powder of an inorganic photoconductive substance such as ZnO and coating it on a conductive support is within the temperature range of 400 to 800°C. . However, it is not preferable to fire at 400 to 800°C from the beginning, and it is necessary to dry at a low temperature, for example, 20 to 70°C, until cracks are about to appear. Therefore, firing is performed after considerable drying has progressed. At a firing temperature of 800° C. or higher, CdS sublimes or decomposes, changing its properties.

Therefore, when ZnO is used as the inorganic photoconductive material, a firing temperature of 800° C. or higher may be used. Other components include XYm (where X is Mg, .BalPb, .Z
n,. Mn,. Y is 0,. F. ．． C1, m=1 or 2)
Metal oxides, fluorides, chlorides, etc. shown in may be added in an amount of 5% by weight or less. A photoconductive substance is dispersed in this binder and baked to form a photoconductive layer. In this case, the photoconductive substance is added so as to account for about 50% or less of the photoconductive layer. . A photosensitive plate of the present invention can be obtained by applying a photoconductive substance dispersed in a binder onto a conductive support using a spray gun, for example, and then baking it.

As the support, a stainless steel plate, an aluminum plate, an iron plate, and various other materials can be used, and among metal substrates, a stainless steel plate is particularly suitable. In other words, the expansion coefficient of stainless steel and the expansion coefficient of the binder used in the present invention are similar, so even when a thin stainless steel substrate is used, the curl of the support after firing and cooling is extremely small. be. The thickness of the photoconductive layer in the electrophotographic photosensitive plate according to the present invention does not need to be so strictly defined, but it is in the range of 30 to 150 μm, preferably 40 to 70 μm, and the particle size of the binder is 2 μm. It has been confirmed through experiments that the following is desirable. The photosensitive plate for electrophotography of the present invention has a photoconductive layer with excellent mechanical strength, so it is hard to be scratched and has wear resistance, so it can be used for a long period of time, and the surface is smooth and glossy. It is easy to clean and does not cause stains.

In particular, the inorganic glass binder according to the present invention has a large dielectric constant,
Not only does it have excellent insulation properties, but it also has good adhesion to the metal substrate, so the photoconductive layer hardly peels off from the metal substrate. Next, examples and comparative examples will be shown.

The oxide powder consisting of Example 1 was sufficiently mixed and ground in a mortar, transferred to a porcelain crucible, melted in an electric furnace maintained at 860°C for 1 hour, and then poured into distilled water and rapidly cooled. A granular glaze was obtained.

50 cc of distilled water was added to this glaze 707, which was ground in a ball mill for 30 hours, a portion of which was applied onto a stainless steel substrate using a spray gun, and dried at about 60°C.

After that, by baking at 550℃ for 10 minutes, 35μ
A thick film layer was obtained. The charge retention property of this product was as shown by curve a in FIG. Next, glaze 50rVCcds powder (manufactured by GE) 307 obtained by pulverization using the ball mill was added, and further 40cc of distilled water was added as a solvent and dispersed using a homogenizer for 30 minutes.

This was applied onto a degreased stainless steel substrate with a spray gun, dried, and then baked at 550° C. for 10 minutes to produce an electrophotographic photosensitive plate having a photoconductive layer with a thickness of 50 μm. This photosensitive plate was left in the dark for 10 seconds under discharge conditions of -5.7 K and 20 μA, and then irradiated with tungsten light at an illuminance of 10 lux. When the surface potential was measured, curve b in Figure 2 was obtained. . This curve b shows sufficient characteristics as an electrophotographic photosensitive plate. Example 2 Calcium oxide powder 10 was added to the oxide powder of Example 1.
The electrophotographic photosensitive plate obtained by adding No. 7 and carrying out the same method as in Example 1 had extremely high mechanical strength.

When the surface potential of this photosensitive plate was measured under the same conditions as in Example 1, curve c in FIG. 2 was obtained. Curve c represents an electrophotographic photosensitive plate having better properties than curve b. Comparative Example 50cc of distilled water was added to the granular glaze 707 obtained in Example 1.
was added, pulverized for 30 minutes in a ball mill, a part of it was applied onto a stainless steel substrate using a spray gun, and a 35μ thick film layer was obtained by baking at 500°C for 10 minutes. .

The charge retention property of this product was as shown by curve d in FIG. Further, CdS powder (manufactured by GE) 30y was added to the glaze 507 obtained by grinding with the ball mill, and 40 cc of distilled water was added as a solvent, dispersed for 30 minutes in a homogenide, and this was placed on a degreased stainless steel substrate. An electrophotographic photosensitive plate having a photoconductive layer with a thickness of 50 μm was prepared by coating the photoconductive layer on a substrate and baking it at 500° C. for 10 minutes, but the charge retention property of this plate was close to zero.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are diagrams showing the state of charge retention.

Claims (1)

[Claims] 1. In an electrophotographic photosensitive plate having a photoconductive layer provided on a conductive support, the photoconductive layer comprises bismuth oxide 50-50
90% by weight of boron oxide, 9-30% of boron oxide, 0.001-5% of cobalt oxide, 0-30% of cadmium oxide, and 0-30% of calcium oxide. 1. A photosensitive plate for electrophotography, characterized in that it is sintered within a temperature range in which a substance is dispersed and a photoconductive substance does not deteriorate.