JPH0252012A - Filter method and its device - Google Patents

Abstract

PURPOSE:To accelerate dispersion of particles and prevent a filter material from getting clogged by filtering particle dispersion liquid for electronic photosensitive material while supersonic waves are directed. CONSTITUTION:A supersonic oscillator 21 is mounted on a bottom section of a supersonic irradiation tank 20, and an inserting type filter 21A connected with a liquid feeding tube 22 on the upper section of the oscillator, both of which are set in a medium 23 such as water or the like. When particle dispersion liquid for an electronic photosensitive material such as smoothing liquid or the like is passed through the liquid feeding tube 22 and filtered by a filter 24A, the particles in the dispersion liquid are prevented from cohering by the supersonic waves from the supersonic oscillator 21, or the cohesive particles are dispersed again. The filter 24, therefore, is prevented from clogging to make the life of the filter 24 longer.

Description

[Detailed description of the invention] B. Industrial application field The present invention relates to a filtration method and device.

BACKGROUND OF THE INVENTION In recent years, attempts have been made to develop organic photoreceptors with high sensitivity and durability by assigning carrier generation and carrier transport functions to different substances in the photosensitive layer of electrophotographic photoreceptors. being done. In such so-called function-separated type electrophotographic photoreceptors, substances that exhibit each function can be selected from a wide range of materials, so it is relatively easy to produce electrophotographic photoreceptors with arbitrary characteristics. Is possible.

When coating and forming the photosensitive layer of such an electrophotographic photoreceptor, it is necessary to form a thin, uniform layer with high precision in order to maintain good sensitivity characteristics and prevent image defects such as density unevenness, thereby exhibiting good performance as a photoreceptor. It is necessary to apply a layer.

Conventionally, various coating methods such as dip coating, spray coating, spinner coating, wire bar coating, blade coating, and roller coating have been known as coating methods for the photosensitive layer of electrophotographic photoreceptors, but dip coating and spray coating are the main methods. Coating is used.

Among these, dip coating is often used to form a uniform coating on a cylindrical object (such as a conductive substrate).

When forming a photosensitive layer of an electrophotographic photoreceptor by coating, it is necessary to prepare a predetermined photosensitive liquid and apply it to a conductive substrate or the like. At this time, for example, when coating and forming the carrier generation layer of a functionally separated photoreceptor, a coating liquid (paint) is used in which pigment particles of a carrier generation substance are dispersed in a solution in which a predetermined binder resin is dissolved in a solvent. .

When using such a particle-dispersed coating liquid for forming a carrier generation layer, it is necessary to remove foreign substances from the coating liquid to prevent coating defects.

For this reason, the coating liquid is first filtered at the stage of preparing the coating liquid (secondary filtration). Furthermore, in so-called overflow type coating apparatuses (described later), the coating liquid is repeatedly filtered in order to remove foreign matter and the like that are generated when the coating liquid is repeatedly applied.

When filtering such a particle-dispersed coating liquid, generally a filter (filtering element) is set in the piping, and the liquid is fed into the piping for filtration.

However, such a filtration method has the following problems.

That is, in a particle-dispersed liquid, particles tend to aggregate. Therefore, as shown in FIG.
When the coating liquid 1 passes through the mesh 24b formed by the mesh 4a as shown by the arrow, the particles 26 may aggregate and cause clogging.

Once clogging occurs, particles 26 around it gather, and the clogging instantly increases. For this reason, the life of the filter is shortened, and particles are captured by the filter, resulting in a decrease in the concentration of particles. In the case of the carrier-generating layer coating liquid and the like, this decrease in concentration results in a decrease in the concentration of the carrier-generating substance, which is manifested as a decrease in the carrier-generating ability of the electrophotographic photoreceptor and a decrease in the density of the copied image.

The purpose of the present invention is to provide a filtration system that can extend the life of filtration means such as a filter, prevent clogging and perform stable filtration, and also prevent a decrease in the concentration of dispersed particles. An object of the present invention is to provide a method and an apparatus thereof.

21. Structure of the Invention The present invention relates to a filtration method for filtering a particle dispersion for an electrophotographic photoreceptor while irradiating it with ultrasonic waves.

The present invention also provides an ultrasonic generation means, an ultrasonic irradiation tank,
and a filtration means housed in the ultrasonic irradiation tank, and while irradiating the filtration means with the ultrasonic waves generated by the ultrasonic generation means, a particle dispersion for an electrophotographic photoreceptor is produced by the filtration means. This relates to a filtration device that performs filtration.

Further, the present invention provides an ultrasonic transmission medium housed in the ultrasonic irradiation tank and transmitting the ultrasonic waves, and a temperature control means for controlling the temperature of the ultrasonic transmission medium. This relates to the filtration device described in Section 1.

E, Example The present invention will be explained in detail below.

FIG. 1 is a schematic partial cross-sectional view 71 showing the filtration device 30A.
8 A medium 23 such as water is contained in the ultrasonic irradiation tank 20, and an ultrasonic vibrator 21 is attached to the bottom of the ultrasonic irradiation tank 120. A pipe insertion type filter 24A is connected to the liquid sending pipe 22, and this filter 24A is set in the medium 23.

A particle dispersion liquid for an electrophotographic photoreceptor, such as a coating liquid for a carrier generation layer, is sent through the liquid sending pipe 22 as shown by the arrow, and is filtered by a filter 24A. During this filtration, the ultrasonic transducer 21 generates ultrasonic waves, and the ultrasonic waves are irradiated onto the filter 24A.

Therefore, as schematically shown in FIG. 2, the particles 26 are prevented from aggregating due to the ultrasonic vibration of the ultrasonic waves 27, or the aggregated particles 26 are again dispersed and uniformly pass through the mesh 24b. Therefore, the filter 24 is not clogged, and the life of the filter 24 is extended. In addition, since clogging can be prevented and stable filtration can be performed, the 7Il filtration efficiency and operation rate are improved. Furthermore, since the particles 26 are not captured by the mesh 24b, the concentration of the liquid 1 in the particle dispersion system does not decrease.

When a coating liquid for a carrier-generating layer of an electrophotographic photoreceptor or a coating liquid for a photosensitive layer with a single N structure described below is used as a particle dispersion liquid for an electrophotographic photoreceptor, a decrease in the concentration of the carrier-generating substance can be further prevented. As a result, a decrease in image density can be prevented.

FIG. 3 is a schematic partial sectional view showing another filtering device 30B.

In the filtration device of this example, a cartridge type filter 248 is used instead of the pipe insertion type filter. The configuration of other parts is the same as that in FIG.

Each type of filter has the following characteristics:

Pipe insertion type: The filter volume is small, there is little loss of liquid, and stagnation is less likely to occur, but the drawback is that the flow rate passing through is small. Suitable for receiving flow systems.

Car) IJ-edge type: The filter surface area is large (suitable for large flow rate systems. However, because the volume is large, stagnation occurs easily and liquid loss is large. Therefore, the filter should be selected depending on the flow rate through which it passes. be.

The distance between the ultrasonic transducer and the filter can be changed as appropriate depending on the output of the ultrasonic transducer, etc., and if this output is large, it is effective to increase the distance from the filter.

In addition to water, examples of the medium for propagating ultrasonic waves include trichlene, chlorofluorocarbons, perchlorene, and the like.

If the high frequency output of the ultrasonic transducer is too small, the above-mentioned effect will not be noticeable, and if it is too large, bubbles will be generated due to so-called cavitation. Such high frequency output may be appropriately determined according to the flow rate. For the time being, it may be easier to use 50 to 1200W, for example 300W. As the high frequency oscillation frequency, it may be preferable to set it to 23 to 50 KI+□, but this can also be selected as appropriate. Various types of ultrasonic transducers can be used; for example, U I -
304R, U I-304RL, U I-604R
, U I -1204R etc., immersion type ultrasonic transducer, U
Examples include plate-attached ultrasonic transducers such as I-304P R and U I-604P R (all manufactured by Sharp Corporation).

Various types of filters can be used.

For example, a wire type filter can be exemplified. It is also possible to sinter the contacting part of the wire to fix it, or to use a Zimesh cartridge, and for Rigimesh, two or more mesh sheets stacked together and sintered together can also be used. Multi-layer mesh has higher filtration capacity and longer filter life. The mesh size of the filter is preferably in the range of 1 to 300 uIll, for example 10 μm, for example, for filtering a dispersion of a carrier-generating substance for an electrophotographic photoreceptor.

The filtration device and filtration method of this example can generally be applied when a particle-dispersed liquid is prepared and then the liquid is filtered (secondary filtration). Of course, the present invention can also be applied to the preparation of a coating solution for a carrier generation layer for an electrophotographic photoreceptor or a coating solution for a single-layer photosensitive layer (pigment dispersion system) and primary filtration of these coating solutions.

Using the coating liquid that has been filtered in this way, a cylindrical conductive base drum (hereinafter sometimes referred to as a base drum), a belt-type conductive base drum, etc. Apply it on a sexual substrate, etc.
A carrier generation layer and a photosensitive layer having a single layer structure can be formed.

Next, an example in which the filtration device of this example is applied to a part of a coating device will be described.

FIG. 4 is a schematic partial sectional view showing a so-called overflow one-type coating device. In addition, the filtration device part is the first
4 is a further schematic representation of the filtration device of FIG.

A predetermined coating liquid 1 is stored in the coating tank 2, and during dip coating, the base drum 4 is immersed in the coating liquid 1 with the opening 4b facing downward, and then the handle 5a of the lid 5 is gripped. The base drum 4 is pulled up at a predetermined speed and coating is performed. When the base drum 4 is immersed, the base drum hollow part 4
Due to the air filling the hollow part 4c, the coating liquid 1 fills the hollow part 4c.
The liquid level drops to position 1b. Along with this, the liquid level rises to position 1a in the area sandwiched between the outer circumferential surface 4e of the base drum and the inner circumferential surface 2b of the side wall of the coating tank, and the coating liquid 1 is applied to the outer circumferential surface 4e of the base drum up to a predetermined position. , a coating film is formed.

A tray 6 is provided around the side wall 2d of the coating tank 2. The coating liquid 1 is sent out from the tank 12 by the pump (P) 10, is supplied into the coating tank 2 from the supply lower via the filter (F) 24A (or 24 days), and is further supplied to the upper edge of the side wall 2d. 2e issued. During dip coating of the base drum 4, the coating liquid 1 continues to overflow over the upper edge 2e of the side wall 2d as described above, so that the level of the coating liquid is kept constant.

The coating liquid sent by the pump 10 passes through the filtering device 30A (
30 days), ultrasonic waves are oscillated by the ultrasonic oscillator 21 as described above, and the filter 24A (24
B) is irradiated.

In the middle of the liquid sending pipe 22, for example, between the pump 10 and the filter 24
A (24B) may be provided with a pressure gauge 31 to measure the system pressure.

Furthermore, in addition to the ultrasonic irradiation tank 20, a cooling device 32 is provided,
A liquid feed pipe 33 connects the two. Cooling device 3
2 has a built-in cooler, and the medium 23 in the ultrasonic irradiation tank is transferred to the cooling device 3 through a liquid feed pipe 33 as shown by the arrow.
2 and is cooled by a cooler to a constant temperature.

Thereafter, the liquid is supplied from the cooling device 32 through the liquid sending pipe 33 into the ultrasonic irradiation tank 20 as shown by the arrow.

The medium 23, which is an ultrasonic transmission medium, causes a temperature rise while transmitting the ultrasonic wave, and this may cause a temperature rise of the fluid (coating liquid 1) in the filter 24A (24B). Ta.

In this regard, in this example, since the medium 23 is circulated and cooled to a constant temperature as described above, such inconvenience does not occur.

In addition, in this example, since the coating liquid stored in the coating tank is filtered while being circulated, the filter operation time and the amount of filtrate are large, which helps prevent clogging of the filter and extend its life as described above. The effect becomes even more noticeable.

FIG. 5 is a schematic partial cross-sectional view showing an example in which the above-mentioned filtration device is applied to another coating device.

A coating liquid outlet 17 and a coating liquid supply lower are provided on the coating tank bottom wall 2C, and the base drum 4 is fixed at a predetermined position in the coating tank 2. Next, the tank 1 is
The coating liquid 1 in 2 is supplied from the supply lower through the filtration device 304 (30B), and the coating liquid level is shown at position 1 with a dashed line.
C to position 1a shown by the solid line. After this,
Drive the drain pump (P out) 10A,
The coating liquid 1 is discharged from the tank 7 and flows into the tank 12. As a result, a coating film is formed on the outer peripheral surface 4e of the base drum.

In this example, the coating liquid 1 is transferred to the coating tank 2 by the liquid pump 10 days.
When feeding into the filter 24 while irradiating ultrasonic waves,
A (24B) may be used for filtration.

In this example as well, the same effects as in the example shown in FIG. 5 can be achieved. Further, since the coating liquid 1 is discharged by a metering pump to form a coating film, there is no problem such as vibration caused by lifting of the base drum, and a uniform coating film can be formed.

FIG. 6 is a schematic partial sectional view showing an example in which the above-described filtering device is applied to another coating device.

In this example, an outer wall 15 is provided concentrically at a constant interval around the outer periphery of the coating tank side wall 2d.
A notable feature is that a coating liquid receiver portion 11 is provided in an area sandwiched between the outer wall 15 and the outer wall 15 .

That is, the coating liquid 1 stored in the coating tank 2 uniformly passes over the upper edge 2e of the coating tank side wall in the outer circumferential direction, and flows down at a low speed while wetting the outer periphery 2a of the side wall and forming a thin film along the shape. do.

The coating liquid receiver part 11 is a coating liquid storage part that stores the coating liquid, that is, it also functions as a kind of coating liquid reservoir, and the coating liquid 1 flowing down along the outer periphery of the side wall 2a is transferred to the coating liquid receiver as shown in the figure. is accommodated in the lower part of section 11. Application liquid receiver is part 11
A discharge port 17 is provided at the bottom end of the part 11.
The coating liquid 1 once stored in is discharged from the discharge port 17,
It is supplied into the coating tank 2 from the supply lower via the pump 10 and the filtration device 30A (30B). Coating liquid 1 it
When performing the ultrasonic oscillator 21, as described above,
The filter 24A (24B) is irradiated with ultrasonic waves emitted from the filter 24A (24B).

In this example, in addition to the same effects as the example shown in FIG. 4, the following effects can also be achieved.

(a) Since the coating liquid flows down along the outer periphery of the side wall of the coating tank, the flowing area is very large, and the coating liquid flows down while wetting the outer periphery of the side wall of the coating tank. Therefore, as a result, the falling speed of the coating liquid is very low, and the flowing down is carried out quietly, and there is no risk of entraining air bubbles.

What is particularly noteworthy is that even when the base drum is immersed, the flow rate can be lowered due to the size of the flow area, and the coating liquid can flow down quietly.

Therefore, concave coating defects due to air bubbles do not occur, and a uniform coating film can be formed with high productivity. Of course, all the advantages of the conventional overflow type coating device, such as prevention of foreign matter defects, can be fully enjoyed.

(b) Since the coating liquid discharged from the discharge port is supplied from the supply port into the coating tank without passing through a coating liquid storage tank such as a tank, there is no need to provide a separate tank. There is no need to take up extra space, and it is possible to downsize the device and reduce costs.

(C) The coating liquid receiver is provided concentrically on the outer periphery of the side wall of the coating tank, and since both are integrated, both can be controlled as one when performing temperature control, etc., which is advantageous.

An example of an electrophotographic photoreceptor on which a layer is formed using a carrier generation layer coating liquid or the like that has been primarily filtered using the filtration apparatus of the present invention, or on which a layer is formed using the above-mentioned coating apparatus is shown in FIGS. 7 to 9.

In the photoreceptor shown in FIG.
A carrier generation layer 51 is provided as a layer, and a carrier transport layer 52 is provided as a second layer on the carrier generation layer 51. The photoreceptor shown in FIG. 8 has a carrier transport N52 as a first layer and a carrier generation layer 51 as a second layer stacked in this order when viewed from the conductive substrate 50 side. The photoreceptor shown in FIG. 9 has, as a first layer, a photosensitive layer 53 having a single-layer structure containing both a carrier-generating substance and a carrier-transporting substance.

Of course, the number and types of coating layers are not limited to the examples shown in FIGS. 7 to 9, and their compositions, functions, etc. are also not particularly limited, and can be freely set according to the design intention of the photoreceptor. Can be done.

For example, when viewed from the conductive substrate side, the first layer and the second layer are a subbing layer, a photosensitive layer with a single layer structure, a photosensitive layer with a single layer structure,
A protective layer, a first layer, a second layer, and a third layer are a subbing layer, a carrier transport layer, and a carrier generation layer, respectively.
carrier generation layer, carrier transport layer, protective layer;
The first layer, the second layer, the third layer, and the fourth layer are each a subbing layer, a carrier generation layer, a carrier transport layer, and a protective layer, or a subbing layer, a carrier transport layer, a carrier generation layer, and a protective layer. Examples include those that are.

The coating liquid for the carrier-generating layer and the coating liquid for the single-layer photosensitive layer are usually particle-dispersed liquids in which a carrier-generating substance is dispersed as a pigment.

Coating liquids for carrier generation layers and coating liquids for single-layer photosensitive layers include azo dyes such as monoazo dyes, disazo dyes, and trisazole dyes; perylene dyes such as berylene acid anhydride and perylenic acid imide; Indigo pigments such as indigo and thioindigo, polycyclic quinones such as anthraquinone, pyrenequinone and flavanmelones, quinacridone pigments, bisbenzimidazole pigments, induthrone pigments, squarelylium pigments, metal phthalocyanine, metal-free Various known carrier-generating substances, such as phthalocyanine pigments such as phthalocyanine, biryllium salt dyes, eutectic complexes formed from thiapyrylium salt dyes and polycarbonate, are dissolved or dispersed in a solvent together with a suitable binder resin and, if necessary, a carrier transport substance. things are used. Among these, the filtration device of the present invention is used for pigment dispersion systems.

In addition to electron-accepting substances that easily transport electrons, such as trinitrofluorenone or tetranitrofluorenone, the coating liquid contains heterocyclic substances such as poly-N-vinylcarbazole, birapurine derivatives, and polyarylalkane. derivatives, phenylenediamine derivatives,
Various known carrier transport substances that easily transport holes, such as hydrazone derivatives, amine-substituted chalcone derivatives, triarylamine derivatives, carbazole derivatives, stilbene derivatives, and phenothiazine derivatives, can be dissolved.

Examples of the binder resin used in the coating liquid for the carrier generation layer include polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate,
Styrene copolymer resins (e.g. styrene-butadiene copolymer, styrene-methyl methacrylate copolymer), acrylonitrile copolymer resins (e.g. vinylidene chloride-
acrylonitrile copolymer, etc.), vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol resin (e.g. phenol-formaldehyde resin, m-cresol-formaldehyde resin) Film-forming polymers such as styrene-alkyd resins, poly-N-vinylcarbazole, polyvinyl butyral, and polyvinyl formal are preferred.

Further, as a solvent for forming a carrier generation layer and a photosensitive layer having a single N structure, it is necessary to dissolve the binder resin and the carrier transport substance contained if necessary, and to transfer the carrier generation substance to a particle size of preferably 2 μm or less, more preferably 1 μm or less. A material that can be dispersed in the form of fine particles and provide a stable dispersion, and that does not unduly dissolve or swell the underlying carrier transport layer, subbing layer, etc., if present, is selected.

For example, acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,1.2-
Trichloroethane, 1,1゜2.2-tetrachloroethane, 1,1.2-trichloropropane, 1,1,2.2
-tetrachloropropane, 1,2.3-trichloropropane, 1゜1.2-trichlorobutane, 1,2,3.4
-Tetrachlorobutane, tetrahydrofuran, monochlorobenzene, dichlorobenzene, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methylcellosolve acetate, n-butylamine, diethylamine, ethylenediamine, isopropanolamine , triethanolamine, triethylenediamine, N,N-dimethylformamide, and the like. In particular, among the above, toluene,
Chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2-trichloroethane, 1. L.

2.2-Tetrachloroethane, tetrahydrofuran, monochlorobenzene, dioxane are preferred solvents.

The coating liquid used in the present invention may contain other substances in addition to those mentioned above. For example, the inclusion of a siloxane compound has the effect of smoothing the coating surface. Examples of siloxane compounds include dimethylpolysiloxane and methylphenylpolysiloxane.

The amount added is preferably 1 to 110,000 pp, more preferably 10 to 11,000 pp with respect to the total amount of the coating liquid.

In addition, in the coating liquid, for the purpose of reducing residual potential and memory, an electron-accepting substance such as succinic anhydride, maleic anhydride, or phthalic anhydride is preferably added to the carrier-generating substance 1.
It can be added in a proportion of 0.1 to 100 parts by weight per 00 parts by weight. Furthermore, if necessary, phthylamine is added to the coating solution for the purpose of improving sensitivity and reducing memory.
An organic amine such as diisobutylamine may be contained in an amount less than the number of moles of the carrier-generating substance.

More specifically, the following method is exemplified for forming the carrier generation layer and the photosensitive layer having a single layer structure.

A method in which a carrier-generating substance is made into fine particles in a dispersion medium using a ball mill, a homomixer, etc., and a binder is added as necessary to mix and disperse the obtained dispersion, and the resulting dispersion is applied.

Dispersing the particles under the action of ultrasound in this method allows for homogeneous dispersion.

The viscosity of the coating liquid is preferably within the range of 5 to 500 cp (centivoise), and 10 to 300 cp.
It is more preferable to fall within the range of . If the viscosity is lower than the above range, the coating film tends to sag, and the film tends to be thicker at the bottom of the drum than at the top. If the viscosity is higher than the above range, the viscosity of the coating liquid in the coating tank tends to become uneven. , there is a tendency for film thickness unevenness to occur in the coating film.

The carrier transport layer is formed by coating and drying a coating liquid obtained by mixing and dissolving the binder resin, carrier transport substance, etc. as described above in the solvent as described above.

Although the shape, material, etc. of the conductive substrate are not particularly limited, a seven-cylindrical shape is preferably used. In addition, the material may be a metal plate such as an aluminum alloy, a metal drum, or a conductive thin layer made of a conductive polymer, a conductive compound such as indium oxide, or a metal such as aluminum, palladium, or gold, such as coating, vapor deposition, or lamination. A material provided on a substrate such as paper or a plastic film is used.

Next, specific experimental examples will be described, but the embodiments of the present invention are not limited thereto.

Preparation of Coating Liquid for Carrier Generation Layer First, a coating liquid for carrier generation layer was prepared as follows.

■, 2-dichloroethane (manufactured by Kanto Kagaku Co., Ltd.) (boiling point 83.
5° C.), 5.0 g of polycarbonate (Panlite-L-1250, manufactured by Kijin Kasei Co., Ltd.) as a binder resin was dissolved in 100 d. In addition, as a carrier generating substance, 4. 10 g of lO-dibromoanthrone was pulverized in a ball mill for 24 hours, and the above solution was added thereto and further dispersed in a ball mill for 24 hours to obtain a carrier generation layer coating liquid (dispersion) having a viscosity of 160 Cp.

<Filtration Experiment, Coating Experiment> An experiment was conducted using the coating apparatus and filtration apparatus shown in FIG. 4 and the carrier generation layer coating liquid.

The experimental conditions are as follows.

Ultrasonic transducer: U I-304R (Sharp Corporation) High frequency manual power 300 W Frequency 40 K11□ Applicable oscillator U I-304R Ultrasonic bath: 300 mm : Built-in cooler, circulation sealed handy cooler TRL-C40 (manufactured by Thomas Scientific Co., Ltd.) Distance between ultrasonic vibrator and filter: Approximately 1011IIl
Using the above device, the coating solution for the carrier generation layer was circulated while irradiating ultrasonic waves (example) or without irradiating ultrasonic waves (comparative example), and the filter was clogged while reading the scale of the pressure gauge. I observed the condition.

The results are shown in FIG.

As can be seen from Figure 10, in the example, the pressure did not increase for more than 50 hours and clogging occurred, whereas in the comparative example, the pressure increased significantly after about 2 hours, and the filter was removed due to pump capacity etc. It had to be replaced.

Furthermore, when a coating experiment was carried out by immersing a cylindrical conductive substrate in a coating tank as shown in Figure 4, the coating yield was 85% in the comparative example, while it was 95% in the example. Improved. The coating yield was determined by visually observing the coating film on the cylindrical conductive substrate and determining the presence or absence of foreign matter and aggregation on the coating film.

From the above experimental results, it can be seen that according to the example, the life of the filter is extended, and the grade of the filter can be increased to use a denser filter. Moreover, the coating yield is also significantly improved.

The present invention has been exemplified above, but the embodiments of the present invention are as follows.
, and various modifications are possible.

For example, the ultrasonic generating means is not limited to those described above, and the shape, dimensions, number, etc. of the filtering means are not limited to those described above.

The particle dispersion liquid for an electrophotographic photoreceptor is not limited to a coating liquid for a carrier generation layer, and the composition, purpose, type of particles, etc. can be changed in various ways.

The present invention is applicable to various filtration methods and devices.

According to the filtration method and device of the present invention, the particle dispersion liquid for an electrophotographic photoreceptor is filtered while irradiating ultrasonic waves, so that the particles in the liquid are filtered by the ultrasonic vibrations. Agglomeration is prevented and particle dispersion is promoted. Therefore, clogging of the filtration means can be prevented, so stable filtration can be performed, filtration efficiency and device operation rate can be improved, and the life of the filtration means can be extended. Furthermore, since the particles are not captured by the filtering means due to clogging, a decrease in particle concentration in the particle dispersion liquid for electrophotographic photoreceptors can also be prevented. Therefore, the productivity of the electrophotographic photoreceptor can be increased and the quality can be made more uniform.

[Brief explanation of the drawing]

Figures 1 to 9 show examples, with Figure 1 being a schematic partial cross-sectional view of the filtration device, Figure 2 being a schematic diagram schematically showing the action of ultrasonic waves, and Figure 3 being another example. FIGS. 4 and 5 are schematic partial sectional views showing a coating device, respectively. FIG. 6(a) is a schematic partial sectional view showing another coating device, and FIG. ) is a cross-sectional view taken along the line {circle around (a)}b-vrb, and FIGS. 7, 8, and 9 are partial cross-sectional views showing an example of an electrophotographic photoreceptor, respectively. FIG. 10 is a graph showing the results of a filtration experiment using the filtration devices of Examples and Comparative Examples. FIG. 11 is a schematic diagram schematically showing a state in which a filter is clogged in a conventional filtration device. In addition, in the symbols shown in the drawings, 1... Coating liquid 2... Coating tank 4... Base drum 7... ...Coating liquid supply port 10...Pump 10A...Coating liquid discharge pump 10B...
......Coating liquid supply pump 12...
- Tank 17... Coating liquid outlet 20... Ultrasonic irradiation tank 21... Ultrasonic vibrator 22.33... ...Liquid sending pipe (liquid sending pipe) 2
3...Water (medium) 24A, 24B...Filter 24b.
......Filter mesh 26...
...Particles 27...Ultrasonic waves 32...Cooling device. Figure 1 OA /- Agent Patent Attorney Hiroshi Osaka Figure 3 Figure 5 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. A filtration method for filtering a particle dispersion for an electrophotographic photoreceptor while irradiating ultrasonic waves. 2. It has an ultrasonic generation means, an ultrasonic irradiation tank, and a filtration means housed in the ultrasonic irradiation tank, and irradiates the filtration means with the ultrasonic waves generated by the ultrasonic generation means. A filtration device that filters a particle dispersion liquid for an electrophotographic photoreceptor using this filtration means. 3. The ultrasonic wave transmission medium according to claim 2, further comprising an ultrasonic transmission medium housed in the ultrasonic irradiation tank and transmitting the ultrasonic waves, and a temperature control means for controlling the temperature of the ultrasonic transmission medium. Filtration device.