JPH08320587A - Electrophotographic organic photoreceptor - Google Patents

Abstract

PURPOSE: To obtain a high image quality without producing fog or black spots by specifying the loss factor of a film between an aluminum body and an anodically oxidized surface, namely, by specifying the ratio of the reactance to the serial resistance. CONSTITUTION: This electrophotographic org. photoreceptor is produced by forming an org. photosensitive layer on an aluminum base body having an aluminum anodically oxidized film on its surface. The loss factor of the anodically oxidized film between the aluminum body and the surface of the film, namely, the ratio of the reactance (Xc) to the serial resistance (R) is specified to <=0.8. The ratio is the product of the serial resistance (R) of the anodically oxidized film and the capacitor (C) which constitutes the reactance (Xc), and namely, it is inverse of the product of the specific resistance and dielectric const. of the anodically oxidized film. Therefore, it is necessary that the serial resistance (R) and the capacitor (C) are larger than certain values. Namely, when the photosensitive layer is charged, injection of charges from the aluminum base body is prevented by the anodically oxidized film and the injection current is suppressed small, so that the charge potential is maintained in a good state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor which uses an aluminum substrate having an aluminum anodic oxide film on the surface.

[0002]

2. Description of the Related Art Electrophotographic technology has been developed in the field of copying machines, and has recently been applied to laser printers, etc., and has high image quality, high speed, and quietness that are incomparable to those of conventional impact printers. Proud and rapidly spreading. Organic photoconductors used in these devices are formed by providing a photoconductive layer on the surface of a conductive substrate. FIG. 1 is a cross-sectional view of a typical organic photoconductor having a function-separated structure. An undercoat layer 2, a charge generation layer 3 and a charge transport layer 4 are sequentially formed on the surface of the conductive substrate 1.

As the undercoat layer 2, a resin material typified by polyamide or an anodized film is generally used. As the undercoat layer 2, the latter aluminum anodic oxide film is generally more advantageous in terms of reliability under a high temperature and high humidity environment. However, it is not easy to control the surface condition of this film, and an organic photoreceptor having good characteristics is not always obtained.

The charge generating layer 3 is a layer of a binder resin in which, for example, an X-type metal-free phthalocyanine is dispersed as a charge generating substance. The charge transport layer 4 is a layer of binder resin in which, for example, a hydrazone compound is dispersed as charge transport. The conventional manufacturing process of the undercoat layer of an anodized film on an aluminum substrate is roughly classified into a cleaning process, an anodizing process, and a sealing treatment process. The purpose of the cleaning process is to degrease the surface of the aluminum substrate after machining, and to remove alkali (NaO
(H, KOH, etc.) Etching and pure water cleaning are main. The anodizing step includes, for example, a step of forming an anodized film having a thickness of several μm by electrolytic treatment in a sulfuric acid bath and a subsequent water washing step. The sealing treatment step is carried out for the purpose of reducing the adsorptivity of dirt and improving the cleaning performance, and is a step of sealing fine pores of the anodized film by nickel acetate treatment and smoothing the surface. It consists of dipping with pure water, washing with a shower, and drying.

[0005]

When the photosensitive layer is applied after the sealing treatment, the ions and oxides in the sealing agent remaining on the surface of the anodized film (hereinafter referred to as the film) (when nickel acetate is used, oxidation occurs). Nickel or the like) lowers the potential holding rate (dark decay rate) of the photoconductor, and causes a fogging phenomenon or black spots in the reversal development method. That is, the image quality is degraded.

In order to avoid this, an operation of washing the anodized film after the sealing treatment and then applying the organic photosensitive layer is performed. Alkaline detergents with a pH of 9 to 10 are effective cleaning agents, but depending on the surface condition of the coating, the alkali resistance may be weak or the cleaning performance may be poor. The density unevenness occurs in the photoconductor on which the photosensitive layer is applied.

These problems are caused by the fact that the surface condition of the anodic oxide film is not constant for the same anodic oxidation process and sealing treatment process, and may be avoided if the image quality can be predicted from the surface condition. The present invention has been made in view of the situation that an anodized film suitable for an organic photoconductor cannot be stably obtained even after the sealing treatment of the anodized film, and a fog phenomenon or a black spot does not occur. , To provide an organic photoreceptor having high image quality.

[0008]

In order to achieve the above object, an electrophotographic organic photoreceptor having an aluminum anodized film on the surface of an aluminum substrate and an organic photosensitive layer formed on the anodized film is formed. The loss factor between the aluminum and the surface of the anodized film of the film, that is, the ratio of the reactance (Xc) to the series resistance (R), is
It shall be 0.8 or less.

[0009]

According to the present invention, an aluminum substrate in which the loss factor between the aluminum and the surface of the anodized film of the anodized film, that is, the ratio of the reactance (Xc) to the series resistance (R), is 0.8 or less. This ratio is the product of the series resistance (R) of the anodized film and the capacitance (C) that constitutes the reactance (Xc), that is, the reciprocal of the product of the specific resistance of the anodized film and the dielectric constant. is there. Therefore, the series resistance (R) and the capacitance (C) are larger than a certain value. That is, injection of charges from the aluminum substrate when the photosensitive layer is charged is hindered by the anodic oxide film, the injection current is small, and the charged voltage is maintained well.

[0010]

EXAMPLE An admittance test method is specified in JIS H8683 as a nondestructive test method for the sealing degree of an anodized film. This is to measure the admittance between the substrate and aluminum (counter electrode) using a potassium sulfate aqueous solution as an electrode on the coating side. However, there was not much correlation between admittance and image quality, and the image quality could not be predicted. However, the present invention was made because it was found that there is a clear relationship between the d value (loss factor: Xc / R) simultaneously obtained at the time of admittance measurement and the image quality. Example 1 A degreasing agent (fine cleaner 31
5, degreasing was performed at a temperature of 50 ° C.), and the degreasing agent was removed by washing with water. Further, it was degreased with nitric acid. The next anodic oxidation treatment was performed in sulfuric acid at a temperature of 20 ° C. for 24 minutes and then washed with pure water. The optimum sulfuric acid concentration is 160 to 200 g / l. The temperature during electrolysis is preferably 18 to 22 ° C, and particularly preferably 20 to 21 ° C. Dissolved aluminum in sulfuric acid is 1
It is preferably 0 g / l or less, and more preferably 3 to 7 g / l.

Additives (Meltex Co., Ltd.)
Manufactured by Sealex B), using nickel acetate solution, the treatment temperature is 70 ° C., the treatment time is 3 minutes, 5 minutes, 8
Min, 4/10 conditions. After the sealing treatment, the aluminum substrate was washed with pure water and dried with hot air to form an anodized film. After measuring the loss factor d value of the obtained aluminum substrate (measuring device is made by Fischer, an anotester, film side electrode is 3.5% potassium sulfate aqueous solution, and measuring frequency is 1 kHz), then alkali System cleaner (U cleaner AD68 manufactured by Uemura Industry Co., Ltd.)
After that, it was washed with pure water, immersed in warm pure water at 65 ° C., pulled up and dried.

Next, a dispersion in which a charge-generating substance, X-type metal-free phthalocyanine, was dispersed in a vinyl chloride / vinyl acetate copolymer at a ratio of 40% by weight was applied and dried in a drying oven at 80 ° C. for 30 minutes. Then, a charge generation layer was formed. Subsequently, a liquid in which a hydrazone-based material as a charge-transporting substance and polycarbonate were mixed was applied and dried in a drying oven at 90 ° C. for 2 hours to form a charge-transporting layer, thereby preparing an organic photoreceptor.

The organic photoreceptor thus prepared was mounted on an electrophotographic copying machine and an image evaluation test was conducted. Table 1 shows the d value of the aluminum substrate and the image evaluation test results. The number of test photoreceptors was 100 under each condition, and image defects were counted in duplicate.

[0014]

[Table 1] It can be seen from Table 1 that the organic photoreceptor using an aluminum substrate having a d value of 0.8 or less has almost no uneven density, black spots, and fog. Example 2 The same anodized film as in Example 1 was formed on an aluminum substrate, and the sealing treatment was performed as follows.

Nickel acetate solution (Japan Chemical Industry Co., Ltd.)
Manufactured by Alumite Sealer), the treatment time is 8 minutes, and the treatment temperature is 40 ° C, 50 ° C, 60 ° C, 80 ° C, 9
The treatment was performed while changing the temperature to 0 ° C. Then, after washing in pure water, it was dried with hot air. After measuring the loss factor d value in the same manner as in Example 1, the alkaline cleaning agent (Johnson 200)
After that, it was washed with pure water and dried with warm pure water at 65 ° C.

Next, a liquid prepared by dispersing X-type metal-free phthalocyanine, which is a charge generating substance, in a vinyl chloride / vinyl acetate copolymer at a ratio of 40% by weight is applied, and the solution is dried in an oven at 80 ° C. for 3 hours.
It was dried for 0 minutes to form a charge generation layer. Subsequently, a liquid containing a mixture of a charge transporting substance obtained by mixing a butadiene-based material and a hydrazone-based material, which are charge transporting substances, and a polycarbonate is applied, and dried in a drying oven at 90 ° C. for 2 hours to form a charge transporting layer, An organic photoconductor was prepared.

The produced organic photoreceptor was mounted on an electrophotographic copying machine and an image evaluation test was conducted. Table 2 shows the d value of the aluminum substrate and the image evaluation test results.

[0018]

[Table 2] It can be seen from Table 2 that the organic photoconductor using the aluminum substrate having the d value of 0.8 or less has almost no uneven density, black spots, and fog. Example 3 A film was formed in the same manner as in Example 1 and, after measuring the loss factor d value of the aluminum substrate which had been subjected to the pore-sealing treatment, it was subjected to 16 hr at 60 ° C. and 90% RH.
Let it stand, re-measure the loss factor, wash with alkali,
It was dried in warm water, an organic photosensitive layer was applied, and an image evaluation test was conducted.

Table 3 shows the loss factor and the image evaluation result.

[0020]

[Table 3] It can be seen from Table 3 that the anodic oxide film having a large initial d value also improved in image quality when the d value was 0.8 or less by being left at high temperature and high humidity. Example 4 A film was formed in the same manner as in Example 2, and after measuring the loss factor d value of the aluminum substrate which had been subjected to the pore-sealing treatment, it was subjected to 16 hr at 60 ° C. and 90% RH.
Let it stand, re-measure the loss factor, wash with alkali,
It was dried in warm water, an organic photosensitive layer was applied, and an image evaluation test was conducted.

Table 4 shows the loss factor and the image evaluation result.

[0022]

[Table 4] From Table 4, it can be seen that even for an anodized film having a large initial d value, a defect-free image can be obtained when the d value is decreased to 0.8 or less by standing at high temperature and high humidity.

[0023]

According to the present invention, an organic substrate is exposed to an aluminum substrate in which the loss factor between aluminum and the surface of the anodized film, that is, the ratio of the reactance (Xc) to the series resistance (R) is 0.8 or less. Since the layer is applied, charge injection from aluminum when the organic photosensitive layer is charged is suppressed, and image defects such as uneven density, black spots, and fog do not occur.

[Brief description of drawings]

FIG. 1 is a sectional view of a conventional organic photoconductor for electrophotography.

[Explanation of symbols]

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

Claims (1)

[Claims] 1. An organic photoconductor for electrophotography, comprising an aluminum anodic oxide coating on the surface of an aluminum substrate, and an organic photosensitive layer formed on the aluminum anodic oxide coating. An organic photoconductor for electrophotography, wherein a loss factor between them, that is, a ratio of reactance (Xc) to series resistance (R) is 0.8 or less.