JPH09269602A - Manufacture of electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain homogeneous cleaning and to draw out physical detergency up to almost the upper limit of a range where the surface of a substrate is not damaged by scanning the full surface of the conductive substrate, while keeping the contact state of the same part of a sliding cleaning material constant. SOLUTION: This photoreceptor is constituted of the conductive substrate 1 (its center axis 2) as a material to be cleaned, the sliding cleaning material 3 (its center axis 4 and the relative moving direction 5 of the sliding cleaning material) and a contact part 6. Then, the substrate 1 is restrained by a clamping mechanism in the end part or inside and rotated on the center axis 2 of the substrate 1 as the axis of rotation by an external mechanism. The sliding cleaning material 3 is deformed in the contact part, to impart the physical detergency. For instance, a brush, a sponge, etc., are exemplified. The sliding cleaning material 3 is reduced in size and weight, so that a high-speed rotation is attained and a processing speed is increased. The rotational direction is set to be a vertical direction in the contact part with the material to be cleaned and the resticking of soiling is prevented. Moreover, an angle formed by two axis 2 and 4 is 90 deg..

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 electrophotographic photosensitive member, and more particularly to a method for cleaning a conductive substrate for an electrophotographic photosensitive member.

[0002]

2. Description of the Related Art Generally, an electrophotographic photosensitive member is one in which a photoconductive layer is formed on a cylindrical conductive substrate. The cylindrical conductive substrate includes aluminum, iron, stainless steel, copper,
Examples of the material include zinc, nickel, conductive plastic, and glass. Among these, aluminum is widely used because it is relatively inexpensive, lightweight, has good workability, and does not impair electrical characteristics.

Usually, when aluminum is used as a cylindrical substrate, an aluminum billet is processed into an extruded tube by a porthole method, a mandrel method or the like, and then a cylinder having a predetermined wall thickness and outer diameter is formed, so that it is drawn out. It can be made by processing, impact processing, ironing, or mirror finishing by cutting. In addition, an anodized film may be formed on the surface of the substrate in order to prevent image defects such as dust fog. The drawing oil, cutting oil used for mirror finishing, dust in the air, cutting chips, and a sealing agent at the time of forming an anodic oxide film adhere to the surface of the base material, so the surface of the base material is cleaned and removed to remove photoconductivity. Layers are provided. As the photoconductive layer, various inorganic and organic photoconductive layers can be used, but a laminated photoconductive layer including a charge generation layer and a charge transfer layer is extremely useful.

The charge generating layer and the charge transfer layer are formed on the surface of the cylindrical conductive substrate by immersing the cylindrical conductive substrate in a coating method containing the substances constituting the charge generating layer and the charge transfer layer by a known method. It is formed. Examples of the dip coating method include JP-A-49-130736 and JP-A-5-
7-5047 and the methods disclosed in JP-A-59-46171. If the surface of the conductive substrate, which is a pretreatment in the dip coating method, is insufficiently cleaned, processing oil, dust, and a sealing agent used for forming the anodic oxide film will remain on the surface and will be applied during coating. It causes coating defects such as unevenness and foreign matter. Such defects generated on the electrophotographic photosensitive member appear as black spots, white spots, uneven halftone images on the image, and adversely affect the quality, and are not suitable for practical use.

As the method for cleaning the surface of the substrate, immersion cleaning is carried out by immersing the substrate in an organic solvent heated as necessary or under the action of ultrasonic waves, and the substrate is immersed in a solvent.
Alternatively, while sprinkling the solvent on the substrate, a rubbing cleaning that gives a physical cleaning power by a rubbing cleaning material such as a brush or sponge,
Methods such as jet cleaning in which a solvent is jetted from the nozzle onto the surface of the substrate under high pressure, vapor cleaning in which the substrate is inserted into solvent vapor, and the like are mentioned, and the combination thereof is used to clean the surface of the substrate. However, in an actual cleaning machine, the dissolving power of the cleaning agent itself is not sufficient for cleaning, and ultrasonic waves have restrictions such as the target dirt particles being small on the order of μm and the cleaning power differing depending on the spatial position. For many reasons, the scrubbing cleaning step using a brush or sponge is used as the core of the cleaning process.

Generally, when the surface of a substrate is to be cleaned by rubbing, the conductive substrate 1 which is the object to be cleaned is arranged with the central axis 2 in the vertical direction as shown in FIG. While rotating about the axis, a cylindrical scrubbing cleaning material 3 which is substantially longer than the base 1 is arranged so that its central axis 4 is in the vertical direction like 2 and is contact rotated about the axis 4.
A cleaning method in which a cleaning liquid is continuously supplied to the contact portion is adopted.

The reason why the axis of rotation is vertical is that the conductive substrate is well drained, dust adhesion after cleaning is suppressed, and the transport mechanism can be simplified. Brushes, sponges, etc. are used as scrubbing cleaning agents, and organic solvents such as 1,1,1-trichloroethane and trichlorethylene are often used as cleaning fluids, but use of these is suppressed as a countermeasure against environmental problems. Demand is increasing, and there is a tendency to replace hydrocarbon-based, alcohol-based, water-based, etc. detergents.

[0008]

When the rotation axis of the substrate and the rubbing cleaning material are in a substantially parallel positional relationship as in the conventional cleaning method shown in FIG. 3, a specific portion of the rubbing cleaning material is By selectively contacting a specific part of the substrate surface,
There arises a problem that unevenness on the side of the cleaning material is transferred to the surface of the substrate. In other words, in a commonly used cleaning device, the rotation axis of the scrubbing cleaning material is not parallel to the rubbing cleaning material in a strict sense in many cases. It may be uneven.

Further, when a brush is used as a scrubbing cleaning material, for example, in a strict sense, it is not generally taken into consideration that the density of the brush is planted and the length of the bristle at each part is considered. It is unavoidable that a pressure distribution is generated in the direction, and problems such as uneven cleaning and scratches on the surface of the substrate are apt to occur at locations where the contact pressure is high. Of course, these problems can occur with scrubbing cleaning materials other than brushes.
Furthermore, since the size and shape of the substrate differ depending on the type of the photoconductor, the abrasion of the scrubbing cleaning material occurs unevenly in the rotation axis direction, and this also easily causes uneven cleaning. These cleaning irregularities and brush scratches cause image defects such as white streaks, black streaks, white spots and black spots in the image inspection after the photoconductor layer is formed, and thus become a serious quality problem.

If a scrubbing cleaning material is prepared in consideration of this problem, the scrubbing cleaning material needs to have at least a length equal to or longer than the longest object to be cleaned, and further, the entire contact surface must be uniform. Therefore, a considerable amount of technology and careful attention are required in manufacturing, which increases the cost, but this is not suitable as a consumable item. In addition, the fact that defects due to wear or the like only partially occur makes it unusable also contributes to the cost increase.

In addition to the above, when the rotation axis direction of the scrubbing cleaning material is close to vertical, the cleaning liquid that flows down along with the dirt on the surface of the substrate accumulates at the bottom of the scrubbing cleaning material, and the surface of the substrate may be re-contaminated. , There are a wide variety of problems. That is, in the conventional cleaning method as described above, it is substantially difficult to uniformly clean the electroconductive substrate for electrophotography. Therefore, the development of a new cleaning method has been desired.

[0012]

The inventors of the present invention have diligently studied a new method for cleaning a conductive substrate for an electrophotographic photosensitive member which solves these problems, and as a result, have found that a cylindrical substrate and a scrubbing cleaning material are used. The rotating shafts of the two are arranged in a geometrical twisting relationship or a positional relationship where they intersect with each other, and the rubbing cleaning material is relatively moved in the rotating shaft direction of the base body while rotating in contact with each other to overcome the above problems. The present invention has been accomplished by finding that uniform cleaning can be realized. That is, the present invention
A cylindrical conductive substrate for an electrophotographic photosensitive member, which is an object to be cleaned, is rotated with its central axis as a rotation axis, while the scrubbing cleaning material is geometrically substantially twisted with respect to the rotation axis of the substrate. The gist of the present invention is to provide a method for manufacturing an electrophotographic photosensitive member, which comprises rotating the shaft of FIG.

[0013]

1 and 2, 1 is a conductive substrate for an electrophotographic photosensitive member which is an object to be cleaned, 2 is a central axis of the substrate, 3 is a scrubbing cleaning material, 4 is a scrubbing cleaning material center Axis, 5
Is a relative moving direction of the scrubbing cleaning material, and 6 is a contact portion. The base body 1 shown in FIGS. 1 and 2 is constrained by a gripping mechanism at an end or inside, and is rotated by an external drive mechanism with the central axis of the base body 2 shown in FIGS. 1 and 2 as a rotation axis.

In the conventional cleaning method shown in FIG. 3, since the base is rubbed over the generatrix of the base and receives a force from the cleaning material, it is necessary to support both ends of the base to stabilize the rotation of the base. In the cleaning method of the present invention shown in FIGS. 1 and 2, since the cleaning site is limited, the force applied to the substrate is weak, and it is possible to support only from one end side, and the mechanism can be simplified. Further, in the conventional cleaning method, since the same portion of the scrubbing cleaning material repeatedly contacts a specific portion of the object to be cleaned, there is a drawback that the substrate is easily scratched at a portion where the contact pressure locally increases. The cleaning method of the present invention essentially does not cause such a problem for mechanical reasons.

Further, in the conventional cleaning method, it is necessary to drop the contact pressure at the point where the contact pressure is maximized to such an extent that the substrate is not damaged. In this case, however, cleaning failure is likely to occur at the point where the contact pressure is low. . As a countermeasure, the contact pressure difference at each site is suppressed by using, for example, a brush with soft bristles and a fine wire diameter, but the upper limit of the physical cleaning power allowed within the range where scratches do not occur can be used up. The current situation is that there are none. On the other hand, in the cleaning method of the present invention, the difference in contact pressure between the various parts of the substrate can be reduced mechanically, so that the maximum allowable physical cleaning power can be used up.

The scrubbing cleaning material shown in 3 of FIGS. 1 and 2 is
It is substantially softer than the object to be cleaned, and gives physical cleaning power by being deformed at the contact portion. For example, brushes, sponges, etc. are preferable as they are cost effective and easy to manufacture. To be As a material, nylon, polypropylene or the like can be arbitrarily selected. Polypropylene is preferred for water-based cleaning, and nylon is preferred for organic solvent-based cleaning. The shape of the scrubbing cleaning material is preferably rotationally symmetrical about the central axis 4 in FIGS. 1 and 2. The size is substantially smaller than the object to be cleaned, and the diameter D of each part in the rotation axis direction is D ≦ 10 cm at the maximum part,
It is desirable that the length L in the direction of the rotation axis be L ≦ 10 cm for the following reason and because it does not complicate the structure of rotation or movement.

That is, the scrubbing cleaning material is rotated by an external drive mechanism, but by reducing the size of the scrubbing cleaning material as described above, high-speed rotation can be realized and the processing speed can be improved. In addition, miniaturization is also excellent in cost, and as an effect of increasing centrifugal force due to high-speed rotation, there are advantages such as improvement of physical cleaning power and self-cleaning action of the rubbing cleaning material itself due to easy discharge of cleaning liquid to the outside. . The number of rotations in the vicinity of the contact portion is determined to be an appropriate value in consideration of various conditions such as the required cleaning processing speed, the effect on the surface of the object to be cleaned, and the abrasion of the scrubbing cleaning material. As the conditions usually used, the brush side is selected in the range of 100 to 1000 rpm, and the substrate is selected in the range of about 100 to 400 rpm. In the cleaning method shown in FIG. 1, it is more desirable that the rotation direction of the scrubbing cleaning material is set to be substantially downward in the vertical direction at the contact portion with the object to be cleaned in order to prevent redeposition of dirt.

In FIG. 1, the two axes of 2 and 4 are geometrically spatially twisted, but because the moving direction of the substrate, which is the object to be cleaned, and the moving direction of the scrubbing cleaning material intersect at the contact portion. It is preferable that the angle formed by the two axes is substantially 90 °, considering that cleaning unevenness due to inhomogeneity of the cleaning material can be suppressed. 2 and 4 in FIG.
The two axes may intersect, but from the idea that the uneven cleaning due to the non-uniformity of the scrubbing cleaning material can be suppressed by making the moving direction of each part of the scrubbing cleaning material in the contact portion complicated. It is preferable that the angle formed by is substantially 90 °.

The relative movement direction of the scrubbing cleaning material shown in 5 of FIGS. 1 and 2 is parallel to the rotation axis which is the central axis of the substrate of 2 of FIGS. 1 and 2, and the scrubbing cleaning material and the surface of the substrate are substantially. Since it is always kept equidistant, a uniform contact state can be obtained regardless of the part. Industrially, it is more realistic and preferable to move the substrate side, but it is also possible to move the rubbing cleaning material side or both the substrate and the rubbing cleaning material. The relative movement process is such that at least the contact portion includes one end to the other end with respect to the rotation axis direction of the base body. It is desirable to set the direction of relative movement so that the cleaning material is rubbed against the object to be cleaned so as to be substantially downward in the vertical direction in order to prevent the cleaning liquid after cleaning from reattaching to the substrate surface.

The relative movement speed V is set so that there is no uncontacted portion on the surface of the substrate, that is, when the maximum value of the length of the contact surface in the rotation axis direction on the surface of the substrate is 1 and the rotation speed of the substrate is ω. , V <1ω. However, when a special movement method such as rocking is used, the speed may be out of the regulation range.
Note that the number of times of processing is basically one, but the processing may be performed a plurality of times. In the case of performing the treatment a plurality of times, it is preferable to repeat the cleaning direction downward in the vertical direction rather than repeating the reciprocating movement, but in consideration of productivity, the final cleaning may be performed in the vertical downward direction.

It is preferable to supply a cleaning liquid to the contact portion between the scrubbing cleaning material and the surface of the substrate shown in 6 of FIGS. 1 and 2, and it is preferable that the liquid supply is substantially continuous, but a dry system is also used. Intermittent supply may be carried out as necessary. As a method of supplying the cleaning liquid, there are a method of selectively supplying to the cleaning site and a method of cleaning by placing the contact site in the cleaning liquid, but the former supply method is preferable for preventing redeposition of stains, and further cleaning It is more preferable that the cleaning liquid is supplied from above the portion so that the flow of the cleaning liquid is substantially vertically downward. Examples of the cleaning liquid to be used include, but are not limited to, water, an aqueous cleaning agent, an organic cleaning agent, an organic solvent, and the like.

[0022]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Example 1 An electrophotographic photosensitive member which has been washed and formed with a photosensitive layer after being stored for a long time since the production of a conductive substrate, and the electrophotographic photosensitive member washed by a conventional cleaning method is at a portion corresponding to the lower end side during storage of the substrate. There was a problem that many white streak defects were observed. Therefore, in order to confirm the effect of the cleaning method of the present invention on this problem, the photoreceptor layer was actually formed after the cleaning of the substrate, and the evaluation by the image was performed.

A conductive substrate of an electrophotographic photosensitive member, which is an object to be cleaned, has a diameter of 30 mm, a length of 348 mm, and a wall thickness of 1 mm.
The mirror-cutting circular tube made of A6063 was used, and the storage period from the substrate formation by mirror-cutting to the cleaning treatment was 3 weeks and 3 months. The conductive substrate first passes through a degreasing process with an aqueous cleaning agent and a cleaning process with pure water, and after a hot water cleaning process with pure water at 50 ° C., the process proceeds to a brush cleaning process based on the cleaning method of the present invention. In this brush cleaning step, pure water is supplied to the contact portion between the base and the brush. Subsequently, the process was moved to a final cleaning step using ultrapure water, and finally, drying was performed. Here, pure water is water having a resistivity of 1 MΩcm or more at room temperature, and ultrapure water is water having a resistivity of 5 MΩcm or more at room temperature. In addition, as a comparative example, the results obtained by performing the treatment excluding the brush cleaning step from this cleaning process were also evaluated.

FIG. 4 shows details of the brush cleaning step portion based on the cleaning method of the present invention. The conductive substrate 1 is held by the inner expansion type gripping tool 7 and is rotated about the central axis 2 by the external driving device 8, and the cylindrical scrubbing cleaning material 3 is rotated about the central axis 4 by the external driving device 9. The direction of rotation, that is, the vertical direction is downward. Here, 2 and 4 are in a positional relationship of twist so that the angle formed by both is substantially 90 °. The base body 1 moves in a direction 11 from the lower side to the upper side of the rubbing and cleaning material 3 while rotating, and comes into contact with the rubbing and cleaning material 3. Here, the moving direction 11 of the base 1 is parallel to the central axis 2. The contact portion was supplied with ultrapure water as the cleaning liquid 13 from the cleaning liquid supply pipe 12.

Here, the brush material is polypropylene, the brush wire diameter is 200 μm, the brush outer diameter is 80 mm, the brush portion length is 80 mm, the brush rotation speed is 500 rpm, the contact margin is 5 mm, the circular tube rotation speed is 240 rpm, and the circular tube is pulled up. The speed is 10 mm / sec, the number of strokes is once, that is, the actual contact time is less than 30 seconds.

An electrophotographic photosensitive member was obtained by forming a photoconductor layer of a charge generation layer and a charge transfer layer in this order on the conductive substrate thus washed. A specific explanation is given below. 1 part of a bisazo compound was used as a charge generating substance, 20 parts of dimethoxyethane was added to this, and after dispersion treatment with a sand grinder, polyvinyl acetal resin (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: Butyral # 6000C)
0.5 part was added to a solution prepared by dissolving 10 parts of dimethoxyethane to obtain a charge generation layer forming dispersion liquid. An aluminum substrate that had been previously washed was applied by dip coating to this dispersion, and a charge generation layer was provided so that the film thickness after drying was 0.63 μm. 110 parts of a hydrazone compound having the following structure as a charge transfer material on the charge generation layer,

[0027]

Embedded image 100 parts of a polycarbonate resin having the following repeating structural unit (viscosity average molecular weight: about 22000),

[0028]

Embedded image

A solution was prepared by dissolving 8 parts of the phenol compound in 500 parts of tetrahydrofuran, and an aluminum substrate provided with a charge generation layer was dip-coated on this solution and dried at 125 ° C. for 20 minutes. The film thickness after drying is 21
An electrophotographic photosensitive member was manufactured by providing a charge transfer layer so as to have a thickness of μm.

The obtained electrophotographic photosensitive member was mounted on a commercially available copying machine and a real copying test was conducted to evaluate the halftone image by visual observation. Table 1 shows the results.

[0031]

[Table 1]

When there is no scrubbing with a brush, 4 out of 6 were stored for 3 months after cutting, and 3 out of 9 were stored even for a relatively short period of 3 weeks after cutting. Although streak defects were observed, no white streak defects were observed in the image when the brush cleaning step according to the present invention was added, which resulted in the high cleaning effect of the cleaning method of the present invention. . In this experiment, no image defect caused by brush scratches or poor cleaning was observed.

[0033]

The cleaning method realized by the present invention can solve the above-mentioned problems in the conventional cleaning method. That is, by scanning the entire surface of the conductive substrate while keeping the contact state substantially constant with substantially the same portion of the scrubbing cleaning material, uniform cleaning of the surface of the conductive substrate can be realized, and the physical cleaning force is reduced. It can be pulled up to the upper limit of the range that does not damage the surface. As a side effect,
Compared with the conventional method, a smaller and lighter scrubbing agent can be used, which is superior in terms of cost and as a result of the high-speed rotation of the scrubbing agent, the physical cleaning force is improved and the scrubbing is increased by the centrifugal force increase in the vicinity of the contact surface. There is a self-cleaning effect of the cleaning material itself.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the present invention.

FIG. 3 is an explanatory view showing a conventional mode.

FIG. 4 is a detailed explanatory diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Conductive Substrate 2 Central Axis of Conductive Substrate 3 Rubbing Cleaning Material 4 Central Axis of Rubbing Cleaning Material 7 Inner Expansion Grip 12 Cleaning Liquid Supply Pipe 13 Cleaning Liquid

Claims (5)

[Claims] 1. A cylindrical conductive substrate for an electrophotographic photosensitive member, which is an object to be cleaned, is rotated about its central axis as a rotation axis,
On the other hand, the scrubbing cleaning material is rotated around an axis that is geometrically substantially twisted with respect to the rotation axis of the base body as a rotation axis, and while being in contact with the base body, it is relatively moved in the rotation axis direction of the base body for cleaning. A method of manufacturing an electrophotographic photosensitive member, comprising: 2. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the cylindrical conductive substrate for the electrophotographic photosensitive member and the rotation axis of the scrubbing cleaning material have a geometrically intersecting relationship. 3. A cylindrical conductive substrate for an electrophotographic photosensitive member has a rotation axis oriented substantially in the vertical direction, and a relative direction of movement of the scrubbing cleaning material with respect to the substrate is oriented substantially vertically downward. 2. The method for producing an electrophotographic photosensitive member according to 2. 4. The cylindrical conductive substrate for an electrophotographic photosensitive member has a rotation axis oriented substantially in the vertical direction, and a sweeping direction of the scrubbing cleaning material at the contact portion is oriented substantially in the vertical direction downward. Manufacturing method of electrophotographic photoreceptor. 5. A cylindrical conductive substrate for an electrophotographic photosensitive member has a rotation axis oriented substantially in a vertical direction, and a cleaning liquid is supplied from above the cleaning material by rubbing the cleaning liquid toward a contact portion.
The method for producing an electrophotographic photosensitive member according to any one of the above.