JPS61198244A - Treatment of undercoat layer of electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To maintain close adhesion of a photoconductive layer comparatively good, and yet to control the thickness of a barrier layer to extremely small thickness, preferably, to <=10nm by executing anodic oxidation treatment of the surface of a conductive substrate with an electrolytic voltage maintained low. CONSTITUTION:The surface of the conductive substrate 1 made of Al is anodized at a low electrolytic voltage maintained at 2-10V to form an anodized film 2 as an interface in order to form a photoconductive layer 3 in close adhesion to the surface. When below 2V, sufficient current necessary complete the anodized film in the time limit allowable for the operation does not flow, and a film good in adhesion cannot be obtained, and when above 10V, the barrier layer 2a o the film 2 exceeds 10nm in thickness in most cases.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an electrophotographic photoreceptor used in electrostatic copying machines, computer printers, and the like.

2. Description of the Related Art This type of photoreceptor is generally made of aluminum (the term "aluminum" is used in this specification to include its alloys) on an sTi support to improve adhesion. A photoconductive layer made of a photoconductive insulating material is formed through the interface layer. Various materials mainly composed of amorphous selenium have been widely used as photoconductive materials, but recently, materials with even better properties in terms of photosensitivity, spectral characteristics, acceptance potential, charge retention, etc. have been widely used. Amorphous silicon (hereinafter abbreviated as a-3i) has been attracting attention due to its advantages such as having high properties and being non-polluting, and efforts are being made to put it into practical use.

However, of course when using conventional selenium-based photoconductive materials, especially when forming a photoconductive layer with a-8i, the adhesion of the photoconductive layer to the conductive support and the charging and Problems often arise in terms of residual potential characteristics after exposure.

Conventionally, when using a conductive support made of aluminum, the support is subjected to anodization treatment using a sulfuric acid method or the like as a base treatment in advance to improve the adhesion of the optical If layer, thereby forming an interface on the support surface. It is known to form an anodic oxide film as a layer (for example, Japanese Patent Publication No. 57-1049).
No. 38).

The problem that the invention seeks to solve However, it is true that the anodic oxide film formed by such base treatment, especially the sulfuric acid film, has a highly adsorbent surface and is relatively difficult to interact with the photoconductive layer unless it is sealed. Good adhesion can be achieved, but on the other hand, in the electrophotographic image forming process, the residual potential after light irradiation, that is, the residual potential after light decay, is relatively high, which is particularly harmful to continuous tone image formation. The problem is that it can have a negative impact. For example, the most common anodizing treatment condition is sulfur 1! ! ! Using an electrolyte with a concentration of 15% and a temperature of 20°C, the current density is 1.3A/d'I.
When an aluminum electrode support is anodized under the conditions of It, the anodizing voltage at that time varies slightly depending on the material used, but is about 15 to 20 V. It is said that the thickness of the insulation layer (underneath the insulation layer) is approximately 150 to 20 OA. When such a film is used as an interface layer between a support and a photoconductive layer, relatively good adhesion can be obtained due to the presence of a porous layer with high adsorption properties on the surface, but There is a problem in that the residual potential becomes high after that, and it is not necessarily possible to obtain a photoreceptor of high quality in terms of electrical properties.

As a result of intensive research aimed at overcoming the above-mentioned problems, the present inventors have discovered that the cause of the deterioration of electrical characteristics is mainly due to the barrier layer that is inevitably formed in the lower layer of the anodic oxide film. The present invention was completed based on this knowledge.

Therefore, the intended purpose of the present invention is to control the thickness of the first layer to be extremely thin, preferably 100A or less, while maintaining relatively good adhesion to the leading RIIl, so that no residue remains after exposure. The object of the present invention is to provide a method for forming an interfacial anodic oxide film that can reduce the potential, that is, a method for anodizing a conductive support layer.

As a means for solving the problem, the present invention provides an interface layer on the surface of a conductive support (1) made of aluminum in order to form a photoconductive layer (3) on the surface in an intimate manner. An electrophotographic photoreceptor characterized in that when forming the anodic oxide film (2), the anodic oxidation electrolytic treatment of the conductive support (1) is carried out by keeping the electrolytic voltage at a low voltage of 2 to 10 V. The main topic is the surface treatment method.

Specific explanation of means The type of electrolytic treatment bath for forming the anodic oxide film is not particularly limited in this invention, but in general, solutions such as sulfuric acid, phosphoric acid, and oxalic acid are preferably used. It will be done. However, when a conductive support is anodized using an electrolytic solution, it is not possible to form an anodic oxide film having the low residual potential effect desired by the present invention under normal electrolytic treatment conditions. Therefore, in order to generate an anodic oxide film (2) that can exhibit the above effects, the present invention includes the following steps:
Porous layer (2b) on the surface of the anodic oxide film (2)
An underlying barrier 1 (2a) which acts in particular as an insulating layer
This paper presents specific anodic oxidation treatment conditions that can control the thickness of 1) to be as thin as 100 Å or less. That is, the processing conditions according to the method of the present invention are such that the electrolysis voltage is particularly kept at an extremely low voltage of 2 to 10V. Such voltage is 15 to 20 in the case of normal anodic oxidation electrolysis.
Whereas a voltage of approximately V is applied, this voltage is significantly lower than this. If the voltage is less than 2 V, the current required to chemically form the anodic oxide film will not flow sufficiently within a work-permissible time, making it impossible to obtain a film with good adhesion. Conversely, when a voltage exceeding 10V is applied, the barrier layer (2a) of the anodic oxide film (2) often becomes 1
If the thickness exceeds 0.00 mm, it becomes difficult to maintain the low residual potential characteristic of the present invention in the photoreceptor. The most preferred range of formation voltage is 3 to 8 V wedge. Other electrolytic treatment conditions may follow general treatment conditions. Therefore, for example, in the case of the sulfuric acid method, 1 degree is 10 to 70%
, particularly preferably 10 to 20%, and the temperature can be arbitrarily changed within a range of about 15 to 30°C. Moreover, the electrolysis time can be varied within a range of about 10 to 60 minutes. When a phosphoric acid solution is used, it is advantageous in that a porous layer with a particularly large pore size can be obtained, and further improvement in adhesion can be expected. In the case of phosphoric acid method, the concentration is 5~
Approximately 20% is suitable, and it can be changed as appropriate within the range of temperature of approximately 10 to 30°C and time of approximately 3 to 30 minutes.

Furthermore, in the case of oxal pickling, the concentration is 1 to 5% and the temperature is 10 to 5%.
The temperature is about 30°C, and the processing time is about 5 to 30 minutes.

In this invention, the type of aluminum material used as the constituent material of the conductive support (1) is not particularly limited, and various commercially available aluminum materials may be used in consideration of machinability, strength, hardness, etc. An appropriate one can be selected and used from among them. Generally, pure aluminum, A
30Oo series aluminum wrought material is preferably used.

Effects of the Invention In the surface treatment method according to the present invention, the anodic oxide film interposed as an interface layer between the conductive support and the photoconductive layer formed thereon is particularly effective in reducing the burr V layer. It is formed to be extremely thin with a thickness of 100 Å or less. Therefore, even though the interface layer is an anodic oxide film, its insulating properties are low, and it does not hinder the rapid optical attenuation of the light guide 'f4WI during charging and fogging, and further reduces the residual potential after exposure. It becomes possible to make it sufficiently low. Therefore, it is possible to provide a photoreceptor with good electrical characteristics and excellent resolution of continuous tone image features. Since the interfacial layer is originally formed as an anodic oxide film on the surface of the aluminum conductive support, it has a porous layer on the surface, which exhibits good adhesion to photoconductivity. Not only when a photoconductive material of the 3jj type is used, but also when a photoconductive material of the a-3i type is used, after the formation of the photoconductive layer, separation, blistering, etc. of the layer during the cooling process etc. This has the effect of contributing to the stable construction of a photoreceptor without causing phenomena such as cracks.

Examples Example 1 Made of A1070-H14, outer diameter 80 m, inner diameter 74 tm
1. An aluminum cylindrical body with a length of 340 mm was used as a conductive support, the surface was polished to a mirror finish, and after being degreased with a weak alkaline degreaser, it was heated in a 15% sulfuric acid electrolyte at a liquid temperature of 20"C. , anodic oxidation electrolytic treatment was carried out for 20 minutes by constant voltage electrolysis at 3V.Then, after thoroughly washing with water and air drying, a film made of a-3i with a thickness of about 20 μm was placed on the above support by glow discharge method. A photoconductive layer was formed thereon, and the sample was naturally cooled to room temperature to obtain sample No. 11 of the electrophotographic photoreceptor of the present invention.

Example 2 An aluminum conductive support pretreated in the same manner as in Example 1 was subjected to constant voltage anodic oxidation treatment in a 10% phosphorus II electrolyte at a temperature of 30° C. and a formation voltage of 5 V for 15 minutes. Thereafter, the process was carried out in the same manner as in Example 1 to obtain sample No. 002 of the present invention, a photoreceptor having an a-3i photoconductive layer on the surface.

Example 3 An aluminum conductive support pretreated in the same manner as in Example 1 was electrolytically treated by constant voltage anodic oxidation in a 2% oxalic acid electrolyte at a temperature of 35° C. and a formation voltage of 5 V for 10 minutes. Thereafter, the process was carried out in the same manner as in Example 1 to obtain sample No. 083 of the present invention, a photoreceptor having an a-8i photoconductive layer on the surface.

Comparative Examples 1-2 After pre-treating the same aluminum cylindrical conductive support as in Examples 1-3, 15% 1iII was added according to a conventional method.
Anodization electrolytic treatment was performed using I'fIi lightning solution at a temperature of 20° C. for 1.5 minutes under constant current conditions with a current density of about 1.3 A/d. And the unsealed pores of the anodic oxide film (
Comparative Example Sample No. 0.1) and one that was further subjected to conventional sealing treatment (Comparative Example Sample No. 2>) were prepared. ni a-
81 Comparative example of photoreceptor having light guiding M layer Test F! lN01~
I got 2.

Present invention samples N011 to 3 and comparative example sample N of the above examples
For each of 011 to 2, the anodized film (2)
The thickness of the barrier layer (2a) and the porous layer (2b) of
l)(t2) was measured, and the adhesion of the photoconductive layer was evaluated. Furthermore, these photoreceptor samples were charged with a corona voltage of 5.5 KV in the dark, and then exposed to 10 ρχ·S using a halogen lamp, after which the residual potential was measured.

These results are shown in the table below.

(The following is a blank space) According to the results in the above table, the photoreceptor manufactured using the surface treatment method according to the present invention has a particularly good effect of reducing the residual potential after exposure while maintaining good adhesion of the photoconductive layer. It was acceptable.

[Brief explanation of the drawing]

The drawing is a schematic diagram showing the structure of the interface between the support and the photoconductive layer of a photoreceptor produced by subjecting it to the surface treatment of the present invention. (1) Conductive support, (2) Anodized film, (2a) Single barrier layer, (2b) Porous layer, (3> Photoconductive layer. that's all

Claims (1)

[Claims] When forming an anodic oxide film as an interfacial layer on the surface of a conductive support made of aluminum in order to closely coat the surface with a photoconductive layer, the electrolytic voltage is particularly set at 2 to 10%.
A method for surface treatment of an electrophotographic photoreceptor, characterized in that the electroconductive support is subjected to anodic oxidation electrolytic treatment while being maintained at a low voltage of V.