JPH02150850A - Surface roughening method for electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the cleaning defect by the turning over, edge chipping, etc., of a cleaning blade without degrading electrophotographic characteristics by mechanically polishing the surface by using spherical shot or abrasive particles. CONSTITUTION:The surface is mechanically polished by using the spherical shot or abrasive particles. The shot collides against the surface of the electrophotographic sensitive body and bounces back without being captured by the surface if a sandblasting method is executed by using the shot and, therefore, the embedment of the shot arises only when the shot collides against the surface of the electrophotographic sensitive body as the external force to further embed the shot at the moment when the shot exists on the surface; in addition, the probability thereof is extremely low and, therefore, the embedment of the shot is substantially prevented. The turning over and edge chipping of the cleaning blade by the friction on the surface of the photosensitive body are prevented in this way and the excellent cleanability and images are obtd. without degrading the electrophotographic characteristics at all.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly, to a method for improving the surface of an electrophotographic photoreceptor for obtaining an electrophotographic photoreceptor with good cleaning properties and electrophotographic properties. Concerning surface roughening method.

[Prior Art] Generally, in an electrophotographic process, an electrophotographic photoreceptor is at least charged, image exposed, and developed.

A cycle consisting of transfer and cleaning steps is repeated. In particular, the cleaning process for removing residual toner from the photoreceptor after the transfer process is an important process in order to always obtain clear copy images.

The following two methods are generally used for this cleaning. The first method is to press a rubber plate-shaped member called a cleaning blade onto the photoconductor to eliminate the gap between the photoconductor and the cleaning blade, thereby preventing toner from slipping through and scraping off the remaining toner. be. FIG. 2 is a schematic cross-sectional view showing a typical example of a cleaning device using such a leaning blade, in which the cleaning device 7 is placed close to a cylindrical photoreceptor 8 rotating in the direction of arrow A. , one edge of one end of the cleaning blade 9 attached to the cleaning device is applied to the surface of the photoreceptor 8 in one direction counter to the rotational direction of the photoreceptor as shown in the figure, or in one direction (not shown). The remaining toner is scraped off by applying pressure in the forward direction (it is known that the cleaning performance is better in one direction of the counter).The second method is to rotate the roller of the fur brush so that it is in contact with the surface of the photoreceptor. Let me wipe off the leftover toner, or
Or you can knock it off. Of these two methods, since the rubber blade is cheaper and easier to design, cleaning using a cleaning blade is currently the mainstream. In particular, when performing natural color development, natural colors are produced by overlapping the three primary colors of magenta, cyan, and yellow, or four colors including black, so the amount of toner used is 1/2 of the normal amount. color development, and therefore it is best to use a cleaning method in which a rubber blade is pressed against the photoreceptor.

However, cleaning blades with (*) cleaning performance have a large frictional force with the photoreceptor, so
There was a drawback that the cleaning blade was likely to reverse. This reversal of the cleaning blade is a phenomenon in which the cleaning blade 9a shown in FIG. 2, which is oriented in one counter direction, is warped in the direction in which the photoreceptor moves, that is, in the opposite direction to the one direction counter, as shown by 9b.

What is the phenomenon of this cleaning blade turning over?

If the surface of the photoreceptor is made hard, ie, less likely to be scraped, in order to extend the life of the photoreceptor, this problem becomes more likely to occur. In addition, when toner particle size is made uniform and minute toner particles are removed to improve image quality, the lubricity caused by toner entering the gap between the cleaning blade and the photoreceptor surface is reduced. As the cleaning blade fades, reversal of the cleaning blade is more likely to occur.6 Also, when performing natural coloring, it takes three colors, magenta, cyan, and yellow, or four colors, including black, to produce one image. 3 or 4 times using the same toner.
In order to carry out the phenomenon of
Furthermore, the edges are more likely to be damaged.

Additionally, when the surface layer of the photoreceptor is made of organic matter, the frictional resistance between the cleaning blade and the photoreceptor surface increases compared to an inorganic surface, making it particularly likely that the cleaning blade will flip over and the edges will be damaged. .

Therefore, in Japanese Patent Application No. 62-256769, the applicant previously proposed that the surface of the photoreceptor be roughened in advance so as to avoid deterioration in image quality by cleaning the cleaning blade by inverting the cleaning blade, chipping the blade edge, etc. We proposed a method to prevent defects. The roughening state of the photoreceptor surface is expressed by the 10-point average roughness (R2) measurement method defined in JIS Standard 80601, and the maximum value, average value, and minimum value are all preferably 0.3 to 5. It is within the range of 0 μm, more preferably within the range of 0.3 to 2.0 μm. If the maximum value is larger than 5.0 μm, streaks are likely to appear on the image as an image defect. When the maximum value, average value, and minimum value are 0.3 to 5.0, the friction with the surface is hardly alleviated and the effect of roughening the photoreceptor surface is not recognized.
If it is within the range of 0 μm, the contact area between the photoreceptor surface and the cleaning blade will be reduced, and if the particle size is small (approximately 5 μm or less) contained in the toner,
The surface of the photoreceptor has been scraped off due to use (1μ
m or less) easily penetrates into the gap between the photoreceptor surface and the cleaning blade to provide lubricity (this makes it possible to prevent cleaning failures due to inversion of the cleaning blade, etc.).

On the other hand, as a method for roughening the surface of a photoreceptor.

JP-A-53-92133 and JP-A-57-9477
A mechanical polishing method such as a sandblasting method using a brush or abrasive particles as described in Publication No. 2, and drying conditions for the coating mold as described in Japanese Patent Application Laid-Open No. 53-92133. There are also methods to make the surface into a yuzu dish shape, methods to expose it to a solvent, and even JP-A-52-26226.
As described in the above publication, there is a method in which powder particles are added to the surface layer in advance and coated to roughen the surface. Among these methods, the mechanical polishing method is the most preferable in that it increases the lubricity between the cleaning blade and the photoreceptor surface, because the shavings on the photoreceptor surface generated by mechanical polishing directly act as a lubricant. This is because it works.

[Problems to be Solved by the Invention] However, in this mechanical polishing, a considerable amount of the abrasive particles and grains are embedded in the surface of the photoreceptor, which affects the electrophotographic characteristics of the photoreceptor, especially the increase in residual potential and dark decay. This was causing the negative effect of an increase in That is, due to the increase in residual potential, the potential contrast of the photoreceptor decreases, resulting in a decrease in the density of one image, and the increase in dark decay causes staining of the underlying portion of the image.

The object of the present invention is to solve the problem without the above-mentioned problems.
That is, it is an object of the present invention to provide an electrophotographic photoreceptor that can prevent cleaning failures due to inversion of a cleaning blade, loss of edges, etc., without degrading the electrophotographic characteristics of the electrophotographic photoreceptor.

Another object of the present invention is to provide a roughened surface that can be used to roughen the surface of an electrophotographic photoreceptor in order to prevent this cleaning failure without embedding abrasive particles or sandals into the surface of the electrophotographic photoreceptor. The aim is to provide a method for converting

[Means for Solving the Problems] As a result of intensive studies on the abrasive particles and sand particles, the present inventors found that by using particles with a spherical shape, embedding in the surface of the electrophotographic photoreceptor is significantly reduced, and roughness is reduced. It has been found that surface coating does not affect the electrophotographic properties of the electrophotographic photoreceptor. This is because if the shape of the abrasive particles or squares is irregular, the sharp edges of the particles will pierce or get caught on the electrophotographic photoreceptor, and the subsequent pressure of the abrasive particles or squares will embed them onto the photoreceptor. This is thought to be because, on the other hand, when the shape is spherical, there are no acute angles, so it is difficult for the punch 11 to hit or catch on the electrophotographic photoreceptor, and therefore embedding does not occur.

That is, the present invention is characterized in that, in a method for roughening the surface of an electrophotographic photoreceptor, the surface is mechanically polished using spherical grinding or abrasive particles.

In the surface roughening method of the present invention, the maximum value, average value, and minimum value of surface roughness (herein, ,
It is possible to obtain a uniform rough surface condition in which the maximum surface roughness, average surface roughness, and minimum surface roughness are all within the range of 0.3 to 5.0 μm, thereby reducing cleaning defects. It can be prevented.

Furthermore, as a result of repeated studies by the present inventors on a method for roughening the surface of an electrophotographic photoreceptor, by roughening the surface using a sandblasting method using a medium having a spherical shape as described above,
It was found that there was no embedding of meji on the electrophotographic photoreceptor. That is, in the conventional method of polishing the surface of an electrophotographic photoreceptor, the surface of the electrophotographic photoreceptor is roughened by pressing abrasive particles onto the electrophotographic photoreceptor. Even if sticking and catching are eliminated, the abrasive particles are isolated and exist on the electrophotographic photoreceptor, and are embedded by the pressure of the abrasive, whereas a spherical particle When sandblasting is performed using sandblasting, the sandblasting collides with the surface of the electrophotographic photoreceptor and bounces off without being caught. Since embedding of meji only occurs when there is a collision, and the probability of this happening is extremely low, it is thought that embedding of meji will virtually disappear.

Therefore, it is desirable to roughen the surface of the electrophotographic photoreceptor by preferably using a sandblasting method using a spherical sandpaper.

In carrying out the surface roughening method of the present invention, a film-like abrasive material can be used as a method other than the sandblasting method. Can be used. Rotate the organic electrophotographic photoreceptor l clockwise or counterclockwise. On the other hand, when the film-like abrasive material 2 is moved in the direction of arrow 6 from the delivery roller 3 to the take-up roller 5 via the rubber presser roller 4 which is in pressure contact with the electrophotographic photoreceptor, the film-like abrasive material 2 rubs the surface of the electrophotographic photoreceptor l at the position of the presser roller 4. In the present invention, the relative polishing speed is determined by the difference between the speed of the surface of the electrophotographic photoreceptor l and the moving speed of the film-like abrasive material 2. preferably 1
．． Maintain at 0 mm/5000 mm/sec.

Film-like abrasives used in the practice of the present invention include those in which fine particles of aluminum oxide, silicon carbide, chromium oxide, diamond, etc. are coated and fixed on a film of polyester or the like.

The electrophotographic photoreceptor treated by the surface roughening method of the present invention may be an inorganic photoreceptor or an organic photoreceptor. For example, in the case of an organic photoreceptor, as shown in FIG. An organic photosensitive layer 11 is laminated on a support lO, and this photosensitive layer 11 preferably includes a charge generation layer I2 and a charge transport layer 1.
This is a laminated photosensitive layer with three functionally separated layers.

As the conductive support 10, a metal such as aluminum, an aluminum alloy, or stainless steel, a metal coated with a conductive substance alone or together with a suitable binder to provide a conductive layer, or a conductive treated plastic deck or paper may be used in a drum shape or Any conventionally known material can be used as long as it is shaped into a sheet.

The charge generation layer 12 contains a charge generation substance such as an azo pigment, a quinone pigment, a quinocyanine pigment, a perylene pigment, an indigo pigment, or a phthalocyanine pigment, and a binding agent such as polyvinyl butyral, polystyrene, acrylic resin, polyester, polyvinyl acetate, or polycarbonate. It can be formed by being dispersed in a resin, or it can also be formed as a vacuum deposited film using a vacuum deposition apparatus. The preferred film thickness is 0.5 μm to 3 μm.

The charge transport layer 13 contains a charge transport material such as a styryl compound, a hydrazone compound, a triarylamine compound, a carbazole compound, an oxazole compound, or a pyrazoline compound, or a charge transport material such as a polyarylate, polystyrene, acrylic resin, polyester, or polycarbonate. It can be formed by being dispersed in a binder resin. The preferred film thickness is 10 to 30 μm. Further, as a structure of the photosensitive layer 11, a charge generation layer 12 may be formed on the charge transport layer 13, and furthermore, the photosensitive layer 11 may be formed of a monolayer containing the above-mentioned charge generation substance and charge transport substance in the same layer. It may be of a single layer type.

Furthermore, an intermediate layer such as an undercoat layer may be provided between the conductive support 10 and the photosensitive layer 511 in order to improve adhesiveness and barrier properties.

The electrophotographic photoreceptor whose surface has been roughened by the method of the present invention is used in an electrophotographic process having a cleaning means using a rubber blade brought into contact with the photoreceptor in one counter direction.

The present invention will be explained in detail below based on a specific example. The photoreceptors prepared in each example and comparative example were charged,
It is installed in an electrophotographic device (NP-3525, manufactured by Canon) that has image exposure, development, transfer, and cleaning with a polyurethane rubber blade (linear pressure 11 g/cm), and repeatedly evaluates the image output from the beginning of paper feeding up to 50,000 sheets. I did it. For each photoreceptor, the difference in electrophotographic characteristics (residual potential, dark decay) between the photoreceptor and the photoreceptor before roughening was measured.

Here, the residual potential is 6, Ol after primary charging of -700V.
This is the potential when irradiated with light of ux·sec, and dark decay is the potential that decays within 0.5 seconds after being charged to -700V. Further, the number of abrasive particles or grains embedded on the photoreceptor after surface roughening was observed using an optical microscope photograph, and was measured as the number of particles embedded in a square of 10011 m on one side of the photoreceptor surface.

Table 1 summarizes the results of the repeated image development evaluations, etc.

[Example 1] An aluminum cylinder of 80φ x 360mm was used as a support, and soluble nylon (6-66-610-12
A 1 μm thick undercoat layer was provided by dip coating a 5% methanol solution of a quaternary nylon copolymer.

Next, 10 parts (parts by weight, the same applies hereinafter) of a disazo pigment having the following structural formula, 5 parts of polyvinyl butyral (degree of butyralization 68%, number average molecular weight [20000)] and 5 parts of cyclohexanone
Dispersion was carried out for 20 hours in a sand mill using 0 parts lφ glass beads. This dispersion contains 70 to 120 methyl ethyl ketone.
(appropriate) and coated on the undercoat layer to a film thickness of 0. lLL
A charge generation layer of m was formed.

Next, 10 parts of bisphenol Z-type car recarbonate (viscosity average molecular weight: 1130000) and 10 parts of a hydrazone compound having the following structural formula were dissolved in 65 parts of monochlorobenzene, and this solution was applied on the charge generation layer for 18 hours.
A charge transport layer with a thickness of μm was formed. The average surface roughness of this photoreceptor was 0.0 μm.

When the surface of the photoreceptor prepared by the above method was polished by sandblasting using 10,000 spherical squares with a diameter of 2.0 μm, the surface roughness was as shown in Table 1. Evaluations were made before and after the surface roughening. The results are shown in Table 1 as Example 1.

It was polished to the values shown in Table 1 (Example 1.2.3). Thereafter, as a cleaning treatment, the specimens were immersed in distilled water for ultrasonic cleaning, and then thoroughly dried before evaluation. The results are shown in Table 1.

[Example 2] n'+'Ii was prepared using the same photoreceptor as that used in Example 1, except that the charge transport layer was prepared by the following method.
As a 4:l transport layer, bisphenol Z 1111
Bono carbonate (viscosity = r-equal molecular weight: 1t30000
1 I 0 parts.

As a fluorine-containing resin powder, 10 parts of polytetrafluoroethylene (trade name: Nilbrone L-2 Daikin 1: manufactured by Kogyo) was dispersed for 50 hours with 40 parts of monochlorohensen and 15 parts of tetrahedral L'J furan in a Sdenless ball mill. death,? i
10 parts of a hydrazone compound having the following structural formula as a charge transport substance was dissolved in the prepared dispersion. This solution was applied on the charge generation layer by dip coating for 13 times to form a charge transport layer having a thickness of 18 μm.

This photoreceptor was used as a medium IO [10(l
rI? The surface was roughened to the same degree of roughness as in Example 1 by sandblasting using No. 4. Evaluations were made before and after the surface roughening. This is Example 2, and the results are shown in Example 1.
Shown in the table.

[Example 3] A photoreceptor similar to that in Example 1 was prepared, and the surface of the photoreceptor was coated with a wrapping tape having 10,000 particles as abrasive particles that were exactly the same in shape, size, and material as those in Example 1. The surface was roughened to the same degree as in Example 1. Evaluations were made before and after the surface roughening. This was treated as Example 3 and the results are shown in Table 1.

[Example 41] A photoconductor similar to that in Example 2 was prepared, and the surface of the photoconductor was polished using a lapping tape having 10,000 particles as abrasive particles that were exactly the same in shape, size, and material as those in Example 1. The surface was roughened to the same degree as in Example 1. Evaluations were made before and after the surface roughening. This was treated as Example 4 and the results are shown in Table 1.

[Comparative Example I] A photoreceptor similar to that in Example 1 was prepared, and 100 pieces of Meji were prepared that had the same size and material as those of Example 1, but had an irregular shape.
The surface of the photoreceptor was roughened to the same degree of roughness as in Example 1 by sandblasting. Evaluations were made before and after the surface roughening. This was treated as Comparative Example 1 and the results are shown in Table 1.

[Comparative Example 2] A photoreceptor similar to that in Example 2 was prepared, and 100 pieces of Meji were prepared, having the same size and material as those of Example 1, but having an irregular shape.
The surface of the photoreceptor was roughened to the same degree of roughness as in Example 1 by sandblasting. Evaluations were made before and after the surface roughening. This was treated as Comparative Example 2 and the results are shown in Table 1.

[Comparative Example 3] A photoreceptor similar to that of Example 1 was prepared, and 100 particles having the same size and material as those of Example 1 but having an irregular shape were prepared.
The surface of the photoreceptor was roughened to the same degree of roughness as in Example 1 using a lapping tape having 0.00 abrasive particles. Evaluations were made before and after the surface roughening. This was treated as Comparative Example 3 and the results are shown in Table 1.

[Comparative Example 4] A photoreceptor similar to that of Example 2 was prepared, and particles 1oo of the same size and material as those of Example 1 but with irregular shapes were prepared.
The surface of the photoreceptor was roughened to the same degree of roughness as in Example 1 using a lapping tape having 00 abrasive particles. Evaluations were made before and after the surface roughening. This was treated as Comparative Example 4 and the results are shown in Table 1.

In Table 1, passing means reversing the cleaning blade,
This means that no cleaning defects such as loss of edges and no image defects occurred.

However, as is clear from Table 1, when the surface of a photoreceptor is roughened using irregularly shaped abrasive particles or abrasives, the abrasive particles or abrasives become embedded on the photoreceptor, and the electrophotograph of the photoreceptor is Reduce properties. On the other hand, when the photoreceptor surface is roughened using spherical 1iJF abrasive particles or Meji, the embedding on the photoreceptor is significantly reduced, and especially when sandblasting is used, the electrophotographic characteristics are not affected at all. This makes it possible to appropriately roughen the surface of the photoreceptor without causing any damage.

[Effect of the Invention 1] As explained above, in an electrophotographic process using a cleaning means using a rubber blade, this invention is effective in preventing the cleaning blade from being reversed or chipping of the edge portion due to friction between the cleaning blade and the surface of the photoreceptor. Regarding the method of roughening the surface of the photoreceptor, according to the present invention, the surface is roughened by using abrasive particles or sandblasting having a spherical shape, preferably by a sandblasting method, without any deterioration of the electrophotographic characteristics. It has become possible to obtain excellent cleaning performance and images.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a device capable of being used in the surface roughening method of the present invention. FIG. 2 is a schematic cross-sectional view for explaining the operation of a cleaning means using a cleaning blade. FIG. 3 is a sectional view showing an example of an organic electrophotographic photoreceptor treated by the surface roughening method of the present invention. In the figure, l is an organic electrophotographic photoreceptor, 2 is a film-like abrasive material, 3 is a delivery roller, 4 is a press roller, 5 is a take-up roller, 7 is a cleaning device, 8 is a photoreceptor, 9
10 is a cleaning blade, 10 is a conductive support, 11 is a photosensitive layer, 12 is a charge generation layer, and 13 is a charge transport layer.

Claims (2)

[Claims] (1) A method for roughening the surface of an electrophotographic photoreceptor, which method comprises mechanically polishing the surface using spherical grinding or abrasive particles. (2) The method for roughening the surface of an electrophotographic photoreceptor according to claim 1, characterized in that mechanical polishing is performed using a sandblasting method.