JPH03105349A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the generation of printing defects and the degradation in characteristics in the function separated and laminated electrophotographic sensitive body by providing an intermediate layer contg. specific polyvinyl pyrrolidone between a supporting body and the charge generating layer of the above-mentioned photosensitive body. CONSTITUTION:The intermediate layer 2 is applied and formed on a conductive base 1 consisting of an aluminum alloy, etc., by dissolving the polyvinyl pyrrolidone expressed by formula I (where n is the integer necessary for imparting 1,000 to 300,000 weight average mol. wt.) in a solvent, such as ethanol, and applying this soln. by a dip coating method, etc. The film thickness is preferably 0.1 to 5mum. This film is subjected to a heating treatment at 140 to 180 deg.C to apply and form the charge generating 3 on the layer. The good conformability property is obtd. and the good sensitivity characteristics are attained without causing a characteristic degradation, such as the increase of residual potential when a phthalocyanine pigment is used for the generating layer. A charge transfer layer 4 consisting of hydrazone, etc., is formed thereon by dip coating and drying, by which the electrophotographic sensitive body is obtd.

Description

[Detailed Description of the Invention] [Summary] An electrophotographic photosensitive member that does not cause pinholes or printing defects, and does not cause uneven coating or unevenness in the film layer of the charge generation layer. (where n is an integer necessary to provide a weight average molecular weight of 1,000 to 300,000).

[Industrial application field]

The present invention relates to a functional component M laminated type electrophotographic photoreceptor, and more specifically, a charge generation layer and a charge transport layer are laminated,
Moreover, the present invention relates to a functionally separated laminated electrophotographic photoreceptor in which an intermediate layer is interposed between a conductive support and a layer thereon.

The electrophotographic photoreceptor of the present invention can be widely applied to copying machines, printers, etc. that apply an electrophotographic method.

[Conventional technology]

As an example of electrophotography, it is common to obtain printed matter by repeating the steps of charging, exposing, developing, transferring, and fixing. Charging applies a uniform positive or negative electrostatic charge to the surface of a photoconductive photoreceptor. In the subsequent exposure process, an electrostatic latent image corresponding to the image information is formed on the photoreceptor by irradiating it with laser light or the like to erase the surface charge on a specific portion. Next, this latent image is electrostatically developed with a powder ink called toner, thereby forming a visible image of the toner on the photoreceptor. Finally, this toner image is electrostatically transferred onto recording paper and fused using heat, light, pressure, or the like. Through this series of processes,
Electrophotographic prints can be obtained.

Conventionally, inorganic photoreceptors typified by selenium-based photoreceptors have been widely used as photoreceptors having photoconductivity. This inorganic photoreceptor is highly sensitive and resistant to mechanical abrasion, making it suitable for high-speed, large-scale machines. However, it must be manufactured using a vacuum deposition method and is harmful to the human body, so it must be collected. Due to the necessity, the cost is high and it is difficult to apply it to maintenance-free, small-sized, low-priced machines.

Organic photoreceptors were developed as an alternative to inorganic photoreceptors. Since this photoreceptor can be manufactured by a coating method, it is easy to reduce costs through mass production, and compared to inorganic photoreceptors that use inorganic substances such as selenium, there is a wider range of materials to choose from, so non-toxic compounds can be selected. , it is also possible to make it maintenance-free by disposing of it by the user;
It had the following characteristics.

In particular, a functionally separated layer type photoreceptor in which a charge generation layer and a charge transport layer are laminated on a conductive support is attracting attention. Here, the charge generation layer has the function of absorbing incident light and generating electron/regular tag bears (carrier pairs), and the charge transport layer retains a charge on its surface and transfers the carriers generated in the charge generation layer. It has the function of transporting one side to the surface of the photoreceptor to form an electrostatic latent image.

The charge generation layer is made by dispersing a charge generation substance that absorbs light and generates carrier bare in a binder resin, coating it, drying it, and then applying it to a 0.0000000000000000000 layer. It is shaped to have a film thickness of about 1 to 31, particularly about 1 mark or less. Further, the charge transport layer is prepared by dissolving a charge transport material having carrier transport ability into a binder resin, applying the mixture and drying it for 10 to 30 I! The film is formed to have a film thickness of m. By separating the functions of the photoreceptor into two layers in this way, it is possible to select the optimal compound for each function almost independently, and improve various properties such as sensitivity, spectral characteristics, and mechanical abrasion resistance. can be promoted.

However, from a practical standpoint, it is difficult to obtain satisfactory performance simply by forming a photosensitive layer on the conductive support J-. That is,
When charged due to corona discharge, etc., discharge breakdown often occurs, resulting in bottle holes. Alternatively, there is a problem in that printing defects are likely to occur due to the fact that charges are easily injected from the conductive support. Furthermore, when a thin charge generating layer is coated, unevenness in film thickness and uneven coating are likely to occur due to minute defects or stains on the conductive support.

As a countermeasure against this problem, a method is known in which an intermediate layer made of a specific resin is provided between the conductive support and the charge generation layer. However, if a resin that is easily soluble in the solvent used to coat and form the charge generation layer is used as the resin for such an intermediate layer, the intermediate layer and charge generation layer may mix, resulting in deterioration of characteristics or uneven coating. This will cause some inconvenience. Further, unless sufficient attention is paid to the properties of the resin and the compatibility between the intermediate layer and the charge generation layer, the characteristics of the photoreceptor may be significantly deteriorated. For example, by thermally curing epoxy, acrylic, and phenolic resins using known methods, an intermediate layer that is difficult to dissolve in solvents can be formed, but in the case of such highly insulating resins, the residual potential increases significantly. However, there is a problem that the print density decreases.

It is currently desired, therefore, to provide an electrophotographic photoreceptor that is free from such problems.

[Problem to be solved by the invention]

The purpose of the present invention is to eliminate the occurrence of pinholes and printing defects.
It is an object of the present invention to provide an electrophotographic photoreceptor that does not cause nonuniform film thickness or uneven coating of a charge generation layer.

[Means to solve the problem]

The above-mentioned object, according to the present invention, is a polyvinyl pyro IJF expressed by the following formula: where n is an integer necessary to give a weight average molecular weight of 1,000 to 300,000. This is achieved by a functionally separated laminated electrophotographic photoreceptor characterized by having an intermediate layer containing . It can be eclipsed.

This polyvinylpyrrolidone used to form the intermediate layer is soluble in solvents such as 2, ethanol, methylene chloride, and chloroform, so it can be used by dipping coating method, spray coating method,
It can be easily coated using known methods such as doctor blade coating. On the other hand, when the formed coating film is heat-treated at about 150° C., it becomes difficult to dissolve in a solvent, and elution can be prevented when a charge generation layer is coated on an intermediate layer. Furthermore, it is particularly compatible with a photoreceptor using a charge generating material such as a phthalocyanine compound, and can achieve good sensitivity characteristics without causing a decrease in characteristics such as an increase in residual potential. The heat treatment temperature of this intermediate layer is preferably 140 to 180°C, since if it is too low, the medium resistance will be insufficient. 1 to 5n.

As explained in the prior art section, the electrophotographic photoreceptor according to the present invention has a layer structure of a functionally separated layered photoreceptor in which a charge generation layer and a charge transport layer are laminated. An example of such a photoreceptor is a photoreceptor as shown in FIG. 1. An electrophotographic photoreceptor consists of a conductive support 1, an intermediate layer 2, and a charge generation layer, which are successively laminated thereon. 3 and a charge transport layer 4. The photosensitive layer refers to a laminate of the charge generation layer 3 and the charge transport layer 4. Note that, if necessary, the positions of layer 3 and layer 4 may be reversed to reverse the direction of current flow.

In the electrophotographic photoreceptor of the present invention, the support may be anything as long as it is conductive and can ground the photoreceptor, such as various metal cylinders, cylinders made of conductive resin or paper, and insulating materials. It is possible to use a cylinder in which metal is vapor-deposited or laminated on the surface of the cylinder, a conductive organic thin film on an insulating cylinder, a film having the same structure as above, and the like. Furthermore, if the material is an aluminum alloy, etc., it may be electrolytically oxidized using oxalic acid, chromic acid, sulfuric acid, etc. to form a corrosion-resistant coating of 20 Ilm or less in order to improve adhesion, storage stability, or photoreceptor characteristics. . Further, the corrosion-resistant film may be a film that is subjected to pressure treatment with water vapor after electrolytic oxidation.

The charge-generating substance that should constitute the charge-generating layer or be contained in the charge-generating layer includes various dyes such as azo-based, cyanine-based, indigo-based, berylene-based, squarylium-based, quinone-based, etc. Pigments can be used, and particularly good sensitivity can be obtained by using phthalocyanine pigments. As the cap cyanine, metal-free cap cyanine, or various metal cap cyanines such as copper phthalocyanine, aluminum chloride phthalocyanine, titanyl phthalocyanine, vanadyl phthalocyanine, and indium phthalocyanine can be used.

The charge generation layer is formed by vapor depositing the above charge generation substance on the support, or by coating and drying a mixture dispersed in a solvent together with a binder resin. Binder resins include polyester, polyvinyl alcohol,
Various resins can be used, such as polyvinyl acecool, acrylic, epoxy, and silicone, and are selected in consideration of adhesion to the base and dispersibility of the charge-generating substance. As the solvent used for forming the coating solution, various W-containing solvents such as tetrahydrofuran, methanol, and ethanol can be used alone or in combination, depending on the binder resin of the charge generation layer. The charge generation layer can be applied using the same method 4 as for the intermediate layer, and a preferable film j1 is
is 0. Ol~3)nn, more preferably 0.1~1
! ! It is m.

The charge transport layer may be anything that can transport the charges generated in the charge generation layer. For example, a hole-transporting charge-transporting substance such as hydrazone, triarylamine, or stilbene, or an electron-transporting charge-transporting substance such as chloranil, bromanyl, or trinitrofluorenone dissolved in a binder resin can be used. , a hole-transporting charge-transporting substance is more suitable. Furthermore, photoconductive polymers which themselves have charge transport ability, such as polyvinyl ruhasol, can also be used. As the binder resin for the charge transport layer, known binder resins such as polyester, polycarbonate, epoxy, acrylic-styrene, etc. can be used. As a solvent, depending on the binder resin used, etc.
Various organic solvents such as tetrahydrofuran, toluene, dichloromethane, and methyl cellosolve can be used alone or in combination. The charge transport layer can be coated using the same method as for the intermediate layer, and the preferred film thickness is 5 to 50 mm, more preferably 10 to 30 mm! It is rrl.

(Function) In the electrophotographic photoreceptor according to the present invention, a functionally separated structure is adopted, and an intermediate layer made of a specific polyvinyl bilonodone that has solubility and can be made insolubilized by heat treatment is connected to the support. Because it is interposed between the generation layer,
Pinholes and printing defects are eliminated, a uniform charge generation layer is obtained, and good sensitivity characteristics are achieved.

[Example] Next, the present invention will be explained with reference to Examples and Comparative Examples.

In this example, an electrophotographic photoreceptor having a layer structure as shown in FIG. 1 was prepared, and a printing test was conducted on the electrophotographic photoreceptor.

Polyvinylpyrrolidone (molecular weight = approximately 100,000)
] part (ii parts, the same shall apply hereinafter) was dissolved in 10 parts of ethanol, and this was applied by dip coating onto an aluminum support.
The mixture was dried at .degree. C. for 1 hour to form an intermediate layer having a thickness of about 1 um.

Next, 1 part of titanium oxide phthalocyanine, 1 part of polyester
A mixture of 40 parts of tetrahydrofuran and 40 parts of tetrahydrofuran for IO hours using a hard glass pole and a hard glass pot was dip coated onto the intermediate layer, and dried at 110°C for 1 hour to give a film thickness of about 0. A charge generation layer of 5 Ilrn was formed.

Further, 1 part of a human razone derivative represented by the following structure 2 and 1 part of polycarbonate were dissolved in 8 parts of dichloromethane, and the solution was applied onto the charge generation layer by dip coating, and dried at 70°C for 2 hours to form a film. A charge transport layer having a thickness of about 15 μm was formed.

When the obtained photoconductor was mounted on a prototype small laser printer manufactured by Fujitsu ■ and a printing test was conducted, the printing was clear and satisfactory printing results could be obtained. Furthermore, as a result of continuous printing, it was confirmed that good printing characteristics could be maintained.

The procedure of Example 1 was repeated with the difference that the middle layer was omitted. When the obtained photoreceptor was subjected to a printing test in the same manner as in Example 1, a large number of printing defects occurred.

The comparison group also repeated the procedure of Example 1 above. However, in this example, instead of the intermediate layer of Example 1, 1 part of thermosetting acrylic resin was dissolved in 10 parts of tetrahydrofuran, and this was used to form an intermediate layer having a film thickness of I μm.

When the obtained photoreceptor was subjected to a printing test in the same manner as in Example 1, clear printing results were obtained. However, as a result of continuous printing, it was found that the residual potential increased and the print density decreased after printing only a few sheets.

〔Effect of the invention〕

According to the present invention, by providing the above-mentioned specific intermediate layer between the support and the charge generation layer, it is possible to obtain an electrophotographic photoreceptor without printing defects and without deterioration of characteristics.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a preferred example of an electrophotographic photoreceptor according to the present invention. In the figure, 1 is a conductive support, 2 is an intermediate layer, 3 is a charge generation layer, and 4 is a charge transport layer.

Claims (1)

[Claims] 1. Polyvinylpyrrolidone represented by the following formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. 1. A functionally separated laminated electrophotographic photoreceptor, characterized in that it has an intermediate layer containing (an integer).