JPH03184055A - Surface roughening method for organic electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent a cleaning defect without causing problems in electrophotographic characteristics by forming fine ruggedness on the surface of the org. electrophotographic sensitive body by using a spray coating method at the time of forming the surface layer of the photosensitive body. CONSTITUTION:The fine ruggedness is formed on the surface of the org. electrophotographic sensitive body by using the spray coating method. The uniformly rough surface condition which is expressed by the measuring method of the 10-point average roughness (Rz) defined by the requirements specified in JIS B 0601 and the max. value, average value and min. value of which are all within the range of 0.3 to 5.0mum is thereby easily obtd. with good reproducibility. The sable reproducing state is obtd. in this way and the cleaning defect is prevented without exerting an adverse influence on the electrophotographic characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an organic electrophotographic photoreceptor, and more specifically, an organic electrophotographic photoreceptor for obtaining an organic electrophotographic photoreceptor with good cleaning properties and image characteristics. The present invention relates to a method for forming a rough surface layer.

[Conventional technology]

-ffK In the electrophotographic process, the electrophotographic photoreceptor is at least charged, image exposed, and developed.

A cycle consisting of each step of transfer and cleaning is repeated. Especially after the transfer process.

A cleaning process for removing residual toner on the photoreceptor is an important process for always obtaining clear copy images.

The following two methods are generally used for cleaning. The first method is to eliminate the gap between the photoreceptor and the cleaning blade by pressing a rubber plate-shaped member called a cleaning blade onto the photoreceptor.
This is a method of scraping off residual toner to prevent toner from slipping through. The second method is to wipe or knock off the remaining toner by rotating the roller of the fur brush so that it comes into contact with the surface of the photoreceptor. Of these two methods, since the rubber blade is cheaper and easier to design, cleaning using a cleaning blade is currently the mainstream. Especially when performing natural color development, the three primary colors of magenta, cyan, and yellow,
Alternatively, since natural colors are produced by layering four colors including black, the amount of toner used is much greater than in normal one-color development, so a cleaning method is used in which a rubber blade is pressed against the photoreceptor. It is optimal that

However, the cleaning blade that exhibits excellent cleaning properties has a drawback in that the cleaning blade tends to flip over because of the large frictional force with the photoreceptor. This reversal of the cleaning blade is a phenomenon in which the cleaning blade in one direction of the counter is warped in the direction of movement of the photoreceptor, that is, in the opposite direction to the one direction of the counter.

This phenomenon of the cleaning blade P being reversed becomes more likely to occur when the surface of the photoreceptor is made hard, that is, less likely to be scraped, in order to extend the life of the photoreceptor. 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 it becomes thinner, reversal of the cleaning blade is more likely to occur.

When performing natural color development, one image is produced using toner of three colors, magenta, cyan, and yellow, or four colors including black, three or four times.
Since development is performed twice, the load on the cleaning blade becomes large, which tends to cause the cleaning blade to reverse or even cause damage to the edge portion.

When the surface layer of the photoreceptor is made of organic material, the frictional resistance between the cleaning blade and the photoreceptor surface increases compared to an inorganic surface, resulting in a 1% chance of the cleaning blade turning over or missing the part (error). It is more likely to occur.

Therefore, the present applicant previously proposed in Japanese Patent Application No. 62-256769 that by roughening the surface of the photoreceptor in advance, the cleaning grade could be reversed, the blade edge could be damaged, etc., without deteriorating the image quality. We proposed a method to prevent cleaning defects due to

The roughening state of the surface of the photoreceptor is expressed by the 10-point average roughness (R2) measurement method defined in JIS standard B0601, and the maximum value, average value, and minimum value are all preferably 0.3 to 0.3.
Within the range of 5.0Rn, more preferably 0.3 to 2
．． It is within the range of 0 μm. If the maximum value is greater than 5.0 μm, streak-like defects tend to appear in the image. Further, when the minimum value is smaller than 0.3 μm, the friction between the cleaning blade and the photoreceptor surface is hardly alleviated in some areas, and the effect of roughening the photoreceptor surface is not recognized. If the above maximum value, average value, and minimum value are within the range of 0.3 to 5.0 μm, the contact area between the photoconductor surface and the cleaning blade can be reduced, and a slight amount of dirt may be present in the toner. Small particles (less than 5 μm) and powder (less than 1 μm) on the surface of the photoconductor that has been scraped off due to use will moderately get into the gap between the photoconductor surface and the cleaning blade. Since the lubricity caused by sinking is facilitated, it is possible to prevent cleaning failures due to reversal of the cleaning blade, etc.

On the other hand, as a method for roughening the surface of a photoreceptor, there is
A method of mechanical polishing using a brush or an abrasive material, a sandblasting method, etc. as described in Japanese Patent Laid-open No. 3-92133 and Japanese Patent Application Laid-open No. 57-94772. As described, there is a method of making the surface into a citron-like shape under drying conditions during coating, a method of exposing the surface to a solvent, and a method of applying powder to the surface layer in advance as described in JP-A No. 52-26226. There are methods such as adding body particles and coating to roughen the surface. Among these methods, mechanical methods using abrasive materials or sandblasting involve secondary processing of the completed photoreceptor, and are inefficient. or,
The method of roughening the surface condition by changing the drying conditions during coating, etc. does not work as a method to obtain a uniform rough surface with good reproducibility. Again 1
Since the method of adding powder particles to the surface layer affects the electrophotographic properties of the photoreceptor, there are problems such as difficulty in achieving both surface roughening and electrophotographic properties.

[Problem to be solved by the invention]

The purpose of the present invention is to solve the above-mentioned efficiency problems, reproducibility problems, and! To provide an organic electrophotographic photoreceptor that can prevent poor cleaning and scratch patterns on images due to reversal of the cleaning blade, loss of air and dirt, etc., without causing problems in photographic characteristics. be.

Another object of the present invention is to uniformly roughen the surface of an organic electrophotographic photoreceptor within a predetermined range in order to prevent this cleaning failure.

An object of the present invention is to provide a method for forming a rough surface layer.

[Means to solve Section M]

As a result of intensive studies on roughening the surface of a photoreceptor, the present inventors have discovered that when forming the surface layer of an organic electrophotographic photoreceptor, a spray coating method is used to form fine irregularities on the surface. %1 defined in JIS standard B0601 by
The maximum value, average value, and minimum value expressed by the measurement method of 0-point average roughness (R2) (herein, these are referred to as maximum surface roughness, average surface roughness, and minimum surface roughness, respectively) It has been found that a uniformly roughened surface state in which the values are all within the range of 0.3 to 5.0 μm can be easily obtained with good reproducibility, and that poor cleaning can be prevented.

That is, 1. The method for forming a rough surface layer of an organic electrophotographic photoreceptor according to the present invention includes, when forming the surface layer of an organic electrophotographic photoreceptor,
It is characterized by forming fine irregularities on the surface using a spray coating method. Preferably, this fine unevenness is 0.3 to 5.0 μm as measured by the 10-point average roughness (R7) measurement method defined in JIS standard B0601.

In an organic electrophotographic photoreceptor, the outermost surface layer of the photoreceptor is either a charge generation layer, a charge transport layer, or a protective layer that protects these layers. When using the dip coating method, which is often used, the coated surface is usually obtained as a glossy surface. Mixing low-boiling point solvents or certain powders may cause whitening or roughening of the coated surface, but the reproduction state may be extremely unstable or the electrophotographic properties may be adversely affected. do. This also applies to spray coating methods, but since spray coating methods have a mechanism in which the paint is once atomized into fine particles and then layered, a binder (in many cases, a polymer resin) is used. ) type, molecular weight, solvent,
Or the size of spray paint particles can be controlled by the diameter and shape of the spray nozzle tip.
This makes it possible to roughen the photoreceptor surface layer with good roughness reproducibility when cleaning the photoreceptor surface layer with a blade.

Such spraying conditions can be achieved by applying the following paint using an air spray gun manufactured by Pix Co., Ltd. (USA), for example. Molecules specifically!
22. A photoconductive material paint was prepared by dissolving 4 parts each of bisphenol type 2 polycarbonate and hydrazone compound in 100 parts of chlorobenzene/dichloromethane = 1/1 solvent, and using the above-mentioned Pinx Air Spray Model 604 S ( The paint nozzle is Model 167SA manufactured by the same company, and the paint atomization air pressure is 1.
0 kgf/cm2 spray pattern air pressure 2.0
The photoconductive paint is applied onto a substrate under conditions of k17f^2.

A coated surface according to the invention is obtained.

These depend on the required film thickness and type of paint.

The set air pressure, nozzle diameter, paint solid content, etc. can be adjusted, and the conditions are not limited to the above conditions.

The organic electrophotographic photoreceptor processed by the method for forming a rough surface layer of the present invention has an organic photosensitive layer laminated on a conductive support, and this photosensitive layer preferably has a charge generating layer and a charge generating layer. Functionally separated into charge transport layer! ! This is a t/jI type photosensitive layer.

As a conductive support, metal such as aluminum, aluminum alloy, stainless steel, metal coated with a conductive substance alone or with a suitable binder to provide a conductive layer, or conductive treated glass dust or paper can be used in the form of a drum or sheet. Any conventionally known material can be used, such as one molded into.

The charge generation layer contains charge generation substances such as azo pigments, quinone pigments, quinocyanine pigments, polyurethane pigments, indigo pigments, and phthalocyanine pigments, and binders such as polyvinyl butyral, polystyrene, acrylic resin, polyester, polyvinyl acetate, and polycarbonate. It can be formed by being dispersed in a resin, or it can also be formed as a vapor deposited film using a vacuum evaporation apparatus. Good pA is 0.
01-3 μm.

The charge transport layer is made of styryl compounds, hydrazone compounds,
Triarylamine compounds, carbazole compounds,
Charge transport substances such as oxazole compounds and pyrazoline compounds, polyarylates, polystyrene, acrylic resins, and polyesters.

It can be formed by being dispersed in a binder resin such as polycarbonate. A preferred film thickness is 10 to 30 μm. Alternatively, a charge generation layer may be formed on the charge transport layer as a w+ rule of the photosensitive layer, and the photosensitive layer may be a single layer type in which the charge generation substance and the charge transport substance described above are contained in the same layer. Additionally, an intermediate layer such as a subbing layer may be provided between the conductive support and the photosensitive layer to improve adhesion and barrier properties.

The organic 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 further explained below with reference to Examples.

Example 1 An 80φ x 360mm aluminum cylinder was used as a support, and a 5-polymer methanol solution of soluble nylon (6-66-610-12 quaternary nylon copolymer) was coated on it to form a one-layer undercoat. Layers were set up.

Then the structural formula 10 parts (parts by weight, the same applies hereinafter) of disazo pigment.

Polyvinyl butyral (degree of butyralization: 68%, number average molecular weight [20000]) FIB and 50 parts of cyclohexanone were dispersed for 20 hours in a Santo 0 mill using 1φ glass beads. Add methyl ethyl keto 770 to 120 (
(as appropriate) and coated on the undercoat layer to form a charge generation layer with a thickness of 0.1 μm.

Next, 2 parts of bisphenol 2 type polycarbonate (number average molecular weight 22,000) and 2 parts of a hydrazone compound with the structural formula
1 part was dissolved in a mixture of 50 parts of monochlorpe/zene and 50 parts of dichloromethane, and this solution was applied onto the above charge generation layer by a bare surface spray method to form a charge transport layer with a thickness of 18 μm. A regular air spray gun was used to apply cough susolet, but the nozzle diameter was φ0, 7.
m, paint atomization air pressure is 1. Oklf 7cm2.
Spray pattern air pressure 2.0 kllf/ctn
The distance between the nozzle tip and the non-coated object was fixed at Fi306n, and the non-coated object was rotated in the circumferential direction at 200 rpm, and the device was installed in a device that gradually slid it in the axial direction so that the film thickness was uniform. It was applied. The average surface roughness Fil of this photoreceptor was 0 μm, and the minimum and maximum surface roughnesses were 0.8 μm and 1.2 fim, respectively.

When the above photoreceptor was incorporated into an electrophotographic device (NP-3525, Can y J!J) which includes charging, image exposure, development, transfer, and cleaning with a polyurethane rubber blade, repeated image output evaluations were performed and 50,000 sheets were printed. No problems occurred with the housing. The results are shown in Table 1.

Comparative Example 1 A photoreceptor was produced in the same manner as in Example 1 except that the charge transport layer was produced by dip coating. however.

The amount of solvent used to form a charge transport layer of 18 μm by dip coating was 35 parts of monochlorobenzene and 35 parts of dichloromethane.

The average surface roughness of the photoreceptor thus obtained was 00 μm (almost a perfectly glossy surface). When Comparative Sample 1 was evaluated in the same manner as in Example 1, the cleaning blade reversed after 5 sheets from the start and the device stopped working. The results are shown in Table 1.

Example 2 On the charge transport layer of the sample prepared by dip coating in Comparative Example 1, a 2 μm protective layer of rhinoceros was provided using a spray coating method. Protected J- was dissolved in 10 tftl of bisphenol type 2 polycarbonate (number average molecular weight 6sooo), 70 parts of monochlorobenzene, and 70 parts of dichloromethane, and the equipment conditions for spray coating were exactly the same as in Example 1.

The average surface roughness of the photoreceptor was 2.5 μm, and the minimum and maximum surface roughnesses were 1.1 μm and 3.2 An, respectively.

As a result of carrying out an evaluation of the photoreceptor on the same machine as in experiment fl11, no problems occurred at 100,000 copies.

The results are shown in Table 1.

Comparative Example 2 An attempt was made to apply a protective layer to the same machine as in Example 2 using a dip coating method, but this was not successful. A photoreceptor formed with charge transport layer 1 is immersed in a protective layer preparation.

We investigated the concentration of the protective layer preparation, the solvent, etc., but the coated surface showed significant yuzu skin or uneven sagging, and we could not obtain a material that could be used as an electrophotographic photoreceptor.0 Example 3 Example 1 and It was created in exactly the same manner using WJt (charge generation). Next, 2 parts of bisphenol 2 type polycarbonate (number average molecular weight 22,000), 0.5 parts of polytetrafluoroethylene powder with an average particle size of 0.3 μm, and 50 parts of monochlorobenzene were dispersed in a ball mill disperser for 6 hours to obtain a 2 parts of the hydrazone compound having the structural formula and 50 parts of dichloromethane were added to the dispersion liquid and dissolved therein, and spray coating was performed using the same apparatus as in Example 1 to form a charge transport layer of 18 μm. The average surface roughness of this photoreceptor is 1.5 μm, and the minimum and maximum surface roughnesses are each 1.5 μm. Otan was 1.8 μm.

This photoreceptor was evaluated in the same way as in Example 1! : Koro, 100,000 pieces! No problems such as cleaning blade reversal or image defects occurred. The results are shown in Table-1.

Comparative Example 3 A photoreceptor was prepared in the same manner as in Example 3, except that the charge transport layer was formed by dip coating. However, the amount of dichloromethane among the solvents used to obtain a film thickness of 18 μm by the dip coating method was 20 parts.

The average surface roughness of the photoreceptor thus obtained was 01 μm. When this sample was evaluated in the same manner as in Example 9111, the cleaning blade reversed after the 10th sheet from the start, and the apparatus stopped working.

Table 1 [Effects of the Invention] As described above, in an electrophotographic process using a cleaning means using a rubber blade, in order to prevent the cleaning blade from turning over and chipping of the edge portion due to friction between the cleaning blade and the surface of the photoreceptor, When forming fine irregularities on the surface of the photoreceptor in advance, the spray coating method should be determined by considering the nozzle diameter, coating pressure, and paint composition.
Appropriate surface roughness can be easily obtained with good reproducibility.

Claims (1)

[Scope of Claims] 1. A rough surface of an organic electrophotographic photoreceptor, characterized in that fine irregularities are formed on the surface using a spray coating method when forming the surface layer of the organic electrophotographic photoreceptor. How to form layers. 2. The above-mentioned fine irregularities are 0.3 as expressed by the 10-point average roughness (R_2) measurement method defined in JIS standard B0601.
The method for forming a rough surface layer of an organic electrophotographic photoreceptor according to claim 1, wherein the rough surface layer has a thickness of 5.0 μm.