JP3215829B2 - Method of manufacturing aluminum substrate for photosensitive drum - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum substrate used as a photosensitive drum of an electrophotographic apparatus such as a laser printer, an LED printer, a liquid crystal printer, a laser facsimile, and a copying machine.

[0002] In this specification, the term aluminum is used to include both aluminum and aluminum alloys.

[0003]

2. Description of the Related Art In general, a photosensitive drum for electrophotography is constructed by coating a surface of an aluminum substrate with a photosensitive layer. As the photosensitive layer, inorganic photosensitive materials such as selenium are used. 2. Description of the Related Art Organic photoconductors using organic materials instead of conductive materials (so-called OPC photoconductors) have come to be used because of their excellent film-forming properties, light weight, and low cost.

Recently, in order to further improve the function and characteristics of the organic photoreceptor, the photosensitive layer has recently been replaced with a charge generation layer (CGL).
And a charge-transporting layer (CTL). Then, in order to obtain a high-sensitivity stacked photosensitive drum, the charge generation layer should be 0.2 to 0.2 mm.
Coating on a 0.3 μm thin film has also been performed.

However, when the above-described thin film coating is performed on the surface of an aluminum tube having a large surface roughness, there is a problem that a coating pool is partially formed and a uniform image cannot be formed. Therefore, it is desired to provide an aluminum substrate having a smooth coated surface.

On the other hand, as for the method of uniformly charging the surface of the photosensitive drum, a corona charging method has been conventionally used, but there is a problem of generation of ozone. Therefore, a direct charging method such as roller charging or brush charging is used. Has been increasingly adopted.

[0007] However, in the direct charging method, the air layer, which worked as an insulating layer during conventional corona charging, is eliminated, so that the load on the photosensitive drum is increased, causing local and minute defects on the surface of the aluminum substrate. As a result, there is a problem that a leak (electric leakage) occurs and the photosensitive layer is burned. For this reason, even if the direct charging method is adopted, an aluminum substrate having no unevenness on its surface is desired so that no leakage occurs during uniform charging.

As described above, it is desired to provide an aluminum substrate having a uniform smooth surface from the viewpoint of coating the photosensitive layer or from the viewpoint of the charging method.

[0009] Naturally, smoothness can be ensured by mirror-cutting the surface of the aluminum tube, but there has been a problem that the mirror-finish requires high precision and skill and is costly.

The present invention has been made in view of such a technical background, and does not require mirror finishing.
It is an object of the present invention to manufacture and provide an aluminum substrate for a photosensitive drum having reduced surface irregularities.

[0011]

In order to achieve the above object, the present invention provides an aluminum pipe having a surface Rmax1 to Rmax1.
A step of simply cutting to 5 μm, a step of anodizing the aluminum tube after cutting to form an anodic oxide film having fine irregularities on the surface that inherits the surface irregularities of the aluminum tube, Polishing the surface of the anodic oxide film by a polishing method using a grindstone until the thickness of the fine unevenness disappears and the thickness of the aluminum tube is not exposed. The gist is a method for manufacturing an aluminum substrate.

The reason why the surface of the aluminum tube is simply cut to an Rmax (maximum height) of 1 to 5 μm is that if the Rmax is less than 1 μm, it becomes equivalent to a mirror-finished surface, resulting in an increase in cost. If Rmax exceeds 5 μm,
This is because it is necessary to increase the thickness of the anodic oxide film to be formed so that the background of the aluminum tube is not exposed by the polishing described later, which increases the cost. As shown in FIG. 1, minute irregularities (2) are formed on the surface of the aluminum tube (1) which is simply cut.

Next, the aluminum tube (1) is anodized to form an anodized film (3).
As shown in FIG. 2, the surface of the anodic oxide film (3) has an inherited uneven portion (4) that inherits the minute unevenness (2) of the aluminum tube surface.

According to the present invention, at least the lowest part (4a) of the inherited uneven part (4) is located above the highest part (2a) of the minute unevenness (2) on the surface of the aluminum tube (1). In other words, in other words, the anodic oxide film (3) covers the highest part (2a) of the minute irregularities (2) of the aluminum tube (1) so that the anodic oxide film (3) covers the upper part (2a) and the film exists above the anodic oxide film (3). ) Thickness must be set. The reason is that in the subsequent step of polishing the anodic oxide film (3), the anodic oxide film is polished until the inherited irregularities (4) disappear and the aluminum pipe (1) has a thickness that does not expose the background. It is to be able to do it. In order to reliably satisfy this condition, it is preferable that the thickness t of the anodic oxide film (3) is at least 1.5 times the maximum roughness Rmax of the concave defect (2) on the surface of the aluminum tube (1). 1.5
If it is less than twice, the distance T between the highest part (2a) of the minute unevenness (2) of the aluminum tube (1) and the lowest part (4a) of the inherited uneven part (4) becomes small, and it becomes difficult to adjust the polishing allowance. There is fear. It is particularly desirable to secure 2.0 times or more.

The type and processing conditions of the anodic oxide film (3) are not particularly limited except for the thickness, but the adhesion to the aluminum tube (1), the adhesion to the photosensitive layer, It is desirable to employ a sulfuric acid film or an oxalic acid film having excellent charge injection prevention properties.

After the above anodic oxidation treatment, the surface of the anodic oxide film (3) is polished. This polishing, as described above,
The process is performed until the thickness of the anodic oxide film (3) becomes such that the inherited irregularities (4) disappear and the background of the aluminum pipe (1) is not exposed. Polishing is performed by a polishing method using a grindstone. The reason for this is that a uniform polished surface can be efficiently obtained by using a grindstone. Moreover, the anodic oxide film (3) has a high Hv hardness of 180 to 2
This is also because the use of a grindstone does not cause new surface defects due to the penetration of abrasive grains into the film, and a good surface can be obtained. Representative examples of the polishing method using a grindstone include a centerless polishing method (centerless polishing method), a super-finishing polishing method, and a combination thereof. Centerless polishing is a well-known method suitable for polishing the surface of a cylindrical tube. In this method, the outer surface of the aluminum tube is supported by an adjusting whetstone and a receiving plate without supporting the center hole of the aluminum tube, and the surface of the aluminum tube is polished by the adjusting whetstone. is there. Also,
In the super-finishing polishing method, a relatively fine-grained soft stick grindstone is modified according to the surface to be machined, pressed against the surface of the rotating aluminum tube at a relatively low pressure, and in some cases, generates minute vibration in the axial direction. This is a method of polishing to give a smooth mirror surface.

By the above-described polishing step, as shown in FIG. 3, the surface of the anodic oxide film (3) is transferred to the concavo-convex portion (4) regardless of the presence or absence of the concave defect (2) in the aluminum tube (1). Can be provided as a smooth surface free from the presence of.

After completion of the polishing step, the surface of the anodic oxide film (3) is washed, and after ensuring sufficient wettability, a photosensitive layer is formed by coating to form a desired photosensitive drum. If necessary, the anodic oxide film (3) may be sealed using a nickel acetate solution.

The type of the photosensitive layer is not particularly limited. However, according to the present invention, it is preferable to use a laminated type in which the charge generation layer is preferably made thinner in that a uniform thin film can be applied.

[0020]

After the anodic oxidation treatment, the surface of the anodic oxide film (3) has a thickness such that the thickness of the anodic oxide film (3) is such that the inherited irregularities (4) disappear and the background of the aluminum pipe (1) is not exposed. Until the above, the surface of the anodic oxide film (3) can be made to be a uniform smooth surface without any irregularities by polishing and removing it by a polishing method using a grindstone. In addition, since the hardness of the anodic oxide film (3) is high, even if it is polished by a polishing method using a grindstone, a new surface defect due to the penetration of the dropped abrasive grains as in the case of polishing the surface of the aluminum tube (1). Does not occur.

Further, by ensuring that the thickness of the anodic oxide film (3) before the polishing step is at least 1.5 times the surface roughness Rmax of the aluminum tube (1), the polishing allowance during polishing can be reduced. You can expand the selection.

[0022]

【Example】

(Example 1) The surface of an aluminum tube made of A3003 alloy having a diameter of 30 mm and a length of 260.5 mm was subjected to Rmax.
Simple cutting was performed until the thickness became 0 μm.

Next, the above aluminum tube was anodized. The anodic oxidation treatment is performed using a treatment liquid: sulfuric acid (14
w / v%), liquid temperature: 20 ° C., current density: 1.0 A / dm
^2. Time: 30 minutes. The thickness of the anodized film was 8 μm, which was 2.7 times the Rmax of the aluminum tube. In addition, when the surface of the anodic oxide film was observed with a microscope, irregularities which inherited the irregularities were formed at positions corresponding to the minute irregularities of the aluminum tube.

Next, the surface of the anodic oxide film was uniformly polished by a centerless polishing method. The polishing allowance from the surface of the anodic oxide film was 4 μm. After polishing, the surface of the anodic oxide film was observed with a microscope. As a result, the irregularities had disappeared, and the entire surface had a uniform smooth surface.

Comparative Example 1 The same aluminum tube as in Example 1 was used, and the aluminum tube was anodized under the same conditions as in Example 1. Then, the aluminum substrate was used as it was without performing the polishing step.

Comparative Example 2 The same aluminum tube as in Example 1 was used as an aluminum substrate without anodizing.

A photosensitive layer having a charge generation layer and a charge transport layer was coated on the three types of aluminum substrates obtained as described above in the following manner. That is, the charge generation layer was formed by diluting a metal-free phthalocyanine to 4% with tetrahydrofuran, coating the film to a thickness of about 0.3 μm, and drying. Next, a CT agent (hydrazone compound) and a CT resin (polycarbonate) were dissolved in methylene chloride at a ratio of 1: 2, applied to a thickness of 20 μm, and dried to form a charge transport layer.

Next, when these photosensitive drums were incorporated in a commercially available laser printer of a direct charging system and charged uniformly at a voltage of 700 V, no leak was observed in the photosensitive drum of Example 1, but a comparative example was obtained. Leaks were observed in the photosensitive drums 1 and 2.

[0029]

According to the present invention, as described above, the step of simply cutting the surface of the aluminum tube to Rmax 1 to 5 μm, and after the cutting, the aluminum tube is anodized to inherit the surface irregularities of the aluminum tube. A step of forming an anodic oxide film having a roughened surface on the surface, and after the anodic oxidation treatment, the surface of the anodic oxide film is changed to the unevenness (4).
Until the thickness of the aluminum tube disappears and the thickness of the aluminum tube does not expose the background, and the step of polishing and removing the surface by an abrasion method using a grindstone is performed. A non-existent uniform smooth surface can be obtained. Therefore, even when a thin film such as a charge generation layer is applied to a laminated type photoreceptor, it is possible to suppress the accumulation of coating and to form a uniform and good image. In addition, it is possible to suppress the leakage when uniformly charged by the direct charging method, and it is possible to make the photosensitive drum suitable for the direct charging method.

Of course, the cutting of the aluminum tube is performed using Rm
Since simple cutting with a surface of ax1 to 5 μm is sufficient, mirror finishing is not required, and it can be manufactured at low cost.

Moreover, since the hardness of the anodic oxide film is high,
Even when polishing is performed by a polishing method using a whetstone, a uniform smooth surface can be easily obtained without generating a new surface defect due to the penetration of the dropped abrasive grains as when polishing the surface of the aluminum tube. .

Further, the thickness of the anodic oxide film before the polishing step is set to be 1.5 times the surface roughness Rmax of the aluminum pipe (1).
By ensuring twice or more, the selection range of the polishing allowance at the time of polishing can be expanded, and a smooth surface after polishing can be reliably and stably obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional enlarged view of an aluminum pipe after simple cutting.

FIG. 2 is an enlarged schematic cross-sectional view of the aluminum tube of FIG. 1 after anodizing treatment.

FIG. 3 is a schematic cross-sectional enlarged view after polishing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Aluminum tube 2 ... Micro unevenness 3 ... Anodized film 4 ... Inherited unevenness part

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 5 / 10,5 / 14

Claims (2)

(57) [Claims] 1. The surface of an aluminum tube (1) is Rmax
A step of simply cutting to 1 to 5 μm, and after the cutting, the aluminum tube is anodized to form an anodized film (3) having an uneven portion (4) inheriting the surface unevenness of the aluminum tube (1) on the surface. And polishing the surface of the anodic oxide film (3) after the anodizing treatment using a grinding stone until the unevenness (4) disappears and the aluminum tube (1) does not expose the background. And a step of polishing and removing the aluminum substrate by a polishing method. 2. The thickness t of the anodic oxide film (3) before the polishing step is determined by setting the surface roughness Rmax of the aluminum tube (1) to 1.
2. The method for producing an aluminum substrate for a photosensitive drum according to claim 1, wherein the aluminum substrate is secured at least 5 times.