JPH1048852A - Device for dip-coating electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the vibration of the liquid level of a coating liquid stored in a dipping tank and to reduce the irregular coating of the surface of a base substance by giving the vibration of specified frequency thereby cancelling the vibration in the coating liquid which makes the liquid level unstable. SOLUTION: An exciting means 6 for giving the vibration of 10500Hz to the coating liquid in the dipping tank 1 is installed. A proper vibration device such as a vibration device generating mechanical vibration by amplifying a signal adjusted to specified frequency by a frequency converter or a vibration device generating the mechanical vibration by utilizing the rotation of a motor is used as the exciting means 6, which is attached to the main body 10 of the tank 1 or a piping near the main body 10. Thus, the rocking of the liquid level caused by other vibration given from the outside is cancelled, and the liquid level of the coating liquid is stably held so that it can approach to a still state much further. As a result, the irregular coating which is called a gear mark on the surface of the cylindrical base substance W is effectively prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dip coating apparatus for an electrophotographic photoreceptor, and more particularly, to stabilizing the vibration of a coating liquid contained in a dip tank and coating the surface of a cylindrical substrate. The present invention relates to a dip coating apparatus for an electrophotographic photosensitive member that can further reduce unevenness.

[0002]

2. Description of the Related Art A drum-shaped electrophotographic photoreceptor is manufactured by forming a coating of a photoreceptor material on the surface of a cylindrical substrate. Such a coating is usually formed by coating a photoreceptor material. A dip coating apparatus is used which contains a liquid and has a dip tank in which the cylindrical substrate is dipped. In the treatment by the dip coating device, the smoothness of the formed photosensitive coating film is required,
It is an important issue to prevent coating unevenness on the surface of the cylindrical substrate.

[0003] The causes of the uneven coating include, for example, variations in the concentration of the coating solution and the incorporation of bubbles in the vaporized solvent. However, it is intended to make the coating solution uniform and to eliminate bubbles in the coating solution. As a dip coating method, there has been proposed a method of dip coating while applying ultrasonic vibration to a dip tank by an ultrasonic vibration generator in the dip coating apparatus described above (JP-A-3-62035, JP-A-3-62035). 5-1136
No. 85).

By the way, in a dip coating apparatus which coats the surface of a substrate when it is lifted from a dip tank, vibrations generated on the liquid surface of the coating liquid, that is, the liquid generated before the problems of the mixing state of the coating liquid and bubbles, are suppressed. Surface shaking is considered to be an extremely large factor that causes coating unevenness. In general, seismic isolation structures are used for the foundation of immersion tanks and the foundations of cylindrical base transfer devices such as robot hands. As the pump for supplying the liquid, a pump without vibration or pulsation is employed.

[0005]

However, in the dip coating apparatus described above, the cylindrical substrate is hung by a transfer device including a driving device, and furthermore, noise is generated from peripheral equipment and the like. However, it is difficult to completely suppress the vibration of the liquid surface of the coating liquid.
Depending on the processing conditions such as the immersion speed and the circulation speed of the coating solution, coating unevenness may occur on the surface of the substrate, and the defect rate may increase. Therefore, a new means capable of further reducing the vibration of the liquid surface of the coating liquid contained in the immersion tank is desired.

[0006]

The present inventors have conducted various studies to solve the above-mentioned problems, and as a result, the vibration of the liquid surface in the immersion tank is suppressed to some extent even by the base-isolated structure in the foundation of the immersion tank. However, when a vibration of a certain frequency is transmitted, the vibration of the liquid surface is further amplified due to the relationship with the natural frequency of the coating liquid itself or the natural frequency of the immersed cylindrical substrate. I got the knowledge. The present inventors have further studied based on such knowledge, as a result, if dare to give a vibration of a specific frequency to the coating solution of the immersion tank,
It has been found that vibrations in the coating liquid that make the liquid surface unstable are offset, and as a result, the liquid surface can be stably maintained. Then, it was learned that the vibration to be applied to the coating liquid can be easily generated by skillfully selecting a pump that circulates the coating liquid between the immersion tank and the stirring storage tank. Reached.

That is, the present invention comprises the following two aspects. The first aspect is a dip coating apparatus for forming a coating film of a photosensitive material on the surface of a cylindrical substrate. An immersion tank containing a coating liquid and charged with a cylindrical substrate, a storage tank for preparing and storing the coating liquid, a circulation pipe and a circulation pump for circulating the coating liquid between the immersion tank and the storage tank And an oscillating means for applying a vibration of 10 to 500 Hz to the coating liquid in the immersion tank is provided.

[0008] A second aspect of the present invention is a dip coating apparatus for forming a coating film of a photosensitive material on the surface of a cylindrical substrate. A immersion tank into which a liquid is prepared, a storage tank for preparing and storing the coating liquid, a circulation pipe and a circulation pump for circulating the coating liquid between the immersion tank and the storage tank, and the circulation pump Is a pump for applying a vibration of 10 to 500 Hz to the coating liquid in the immersion tank due to the pulsation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a dip coating apparatus for an electrophotographic photosensitive member according to the present invention will be described with reference to the drawings. FIG.
1 is a system diagram showing main components of the dip coating apparatus for an electrophotographic photosensitive member according to the present invention. FIG. 2 is a graph showing the relationship between the frequency of vibration applied to the coating liquid in the immersion tank, the amplitude of the liquid surface, and the occurrence of coating unevenness.

As shown in FIG. 1, the dip coating apparatus of the present invention is an apparatus for forming a coating film of a photosensitive material on the surface of a cylindrical substrate (W), and contains a coating liquid as a photosensitive material. And an immersion tank (1) into which the cylindrical substrate (W) is loaded, a storage tank (2) for preparing and storing the coating liquid, and circulating the coating liquid between the immersion tank (1) and the storage tank (2). Circulation piping (5
1) to (55) and a circulation pump (3).

In the present invention, the cylindrical substrate (W) is
For example, aluminum, brass, metal materials such as stainless steel, polyethylene terephthalate, polybutylene terephthalate, polypropylene, nylon, polystyrene,
A polymer material such as phenolic resin or other material such as hard paper with an outer diameter of about 20 to 200 mm
It is a conventionally known substrate formed into a cylindrical shape having a length of about 1000 mm. When the surface of the cylindrical substrate (W) is made of an insulating material, conductive treatment is performed by impregnation of a conductive substance, lamination of metal foil, vapor deposition of metal, and the like.

The coating solution is a known coating solution comprising a photosensitive material and one or more solvents. A coating solution of a photoreceptor material for producing a single-layer electrophotographic photoreceptor is prepared by mixing a charge generating substance, a charge transporting substance, a binder resin and a solvent. Further, the coating solution of the photoreceptor material in the case of manufacturing a laminated electrophotographic photoreceptor, the charge generation material, a coating solution for a charge generation layer comprising a binder resin and a solvent, the charge transport material, A coating solution for a charge transport layer comprising a binder resin and a coating solvent is separately prepared.

Examples of the charge generating substance include azo pigments such as Sudan Red, Diane Blue, and Dienase Green B, disazo pigments, quinone pigments such as argol yellow and pyrenequinone, quinocyanine pigments, perylene pigments, and the like.
Examples include indigo pigments, bisbenzimidazole pigments such as indofast orange toner, phthalocyanine pigments such as copper phthalocyanine, quinacridone pigments, pyrylium salts, and azurenium salts.

As the charge transporting substance, polyaromatic compounds such as anthracene, pyrene, phenanthrene, coronene, or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, Examples thereof include compounds having a skeleton of a nitrogen-containing cyclic compound such as thiadiazole and triazole, and other hole transport substances such as hydrazone compounds.

As the binder resin, polycarbonate,
Polyarylate, polystyrene, polymethacrylates, styrene-methyl methacrylate copolymer, polyester, styrene-acrylonitrile copolymer,
Examples include polysulfone and the like, polyvinyl acetate, polyacrylonitrile, polyvinyl butyral, polyvinyl pyrrolidone, methyl cellulose, hydroxymethyl cellulose, cellulose esters and the like.

As the solvent, a solvent having high volatility and having a vapor density higher than that of air is preferably used. For example, n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, N, N-dimethylformamide, acetone, methylethylketone, cyclohexanone, benzene, 4-methoxy-4-methylpentanone-2, dimethoxymethane,
Dimethoxyethane, 2,4-pentadione, anisole, methyl 3-oxobutanoate, monochlorobenzene,
Examples include toluene, xylene, chloroform, 1,2-dichloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methylcellosolve, ethylcellosolve, and methylcellosolve acetate.

The concentration of each component in the coating solution is appropriately set according to a known technique. The concentration of the solid content is mainly determined according to the thickness of the layer to be formed. In the case of a coating solution for producing a single-layer type electrophotographic photoreceptor, Is 40% by weight or less, preferably 10 to 3%,
It is adjusted to 5% by weight or less. In the case of these coating solutions, the viscosity is 50 to 350 cps, preferably 70 cps.
２５０250 cps, and its dry film thickness is 15-40 μm.
m.

In the dip coating apparatus of the present invention, the dip tank (1) is preferably a dip tank that performs treatment while overflowing a coating solution. That is, the immersion tank (1) accommodates the immersion tank body (10), which is open at the upper end and is supplied with the coating liquid from the lower end side, and the coating liquid attached to the upper outer peripheral side of the immersion tank body and overflowing. Gutter member (1
1) mainly.

In the immersion tank body (10), a body for accommodating the cylindrical substrate (W) is formed in a substantially cylindrical shape, and a bottom portion is formed in an inverted conical shape in order to eliminate a partial stagnation of the coating liquid. A pipe (branch pipe) (54) for supplying a coating liquid is connected to the lower end of the bottom. The immersion tank body (10) may be provided alone, but for efficient operation, usually a plurality of immersion tank bodies are provided in parallel.

The gutter member (11) is formed, for example, in a cylindrical shape with a short axis and a bottom. It is made possible to discharge by (55). Further, a flexible hood (1) that expands and contracts as the cylindrical base (W) is immersed and pulled up is provided on the upper outer peripheral side of the gutter member (11).
2) is provided, and the hood (12) adjusts the drying speed of the coating solution applied to the surface of the cylindrical substrate (W) while reducing the evaporation of the solvent in the coating solution.

The storage tank (1) is provided to always supply a sufficient amount of the coating liquid to the immersion tank (1), and the inside thereof stores the coating liquid supplied from the immersion tank (1) in a predetermined amount. In order to prepare the composition and mix it uniformly, it is divided into a preparation tank (21) and a mixed layer (22) by a partition wall. Preparation tank (2
To 1), the other end of the pipe (55) is connected to introduce a coating solution overflowing from the immersion tank main body (10), and a solvent pipe (5) for supplying a solvent for dilution is provided.
6) is inserted. The mixing layer (22) is provided with a stirring blade for uniformly stirring and mixing the coating solution flowing from the preparation tank (21) across the partition wall, and the mixed coating solution is immersed in the dipping tank (1). ) Side piping (51)
Is connected.

The piping (5) between the immersion tank (1) and the storage tank (2)
The arrangement of 1) to (55) and the circulation pump (3) is such that the pipe (51) extending from the mixing layer (22) is connected to the suction side of the circulation pump (3), and the discharge side of the circulation pump (3). The pipe (52) extending from the pipe (53) is connected to the pipe (53) via the filter (4), and branch pipes (54) and (54) branching from the pipe (53) are connected to the immersion tank body (1).
0) and (10). Further, a pipe (55) extending from the gutter member (11) of the immersion tank (1) has a storage tank (2).
Is connected to the preparation tank (21).

That is, in the dip coating apparatus shown in FIG. 1, the circulation pump (3) sucks the coating liquid from the mixed layer (22) of the storage tank (2) through the pipe (51), and
2) The coating liquid is supplied to each immersion tank body (10), (10) of the immersion tank (1) through the filter (4), the pipe (53), and the branch pipes (54, 54). Then, the coating liquid continuously supplied to each of the immersion tank bodies (10), (10) overflows from these immersion tank bodies to the gutter member (11), and then flows through the pipe (55) to the gutter member (11). The overflowing coating solution is returned to the preparation tank (21) of the storage tank (2) again.

In the present invention, a vibrating means (6) for applying a vibration of 10 to 500 Hz to the coating solution in the immersion tank (1) is provided. As the vibration means (6), a vibration device that amplifies the signal adjusted to the predetermined frequency by a frequency converter to generate mechanical vibration, a vibration device that mechanically generates vibration using the rotation of a motor, and the like Any suitable vibration device can be used, and such a device is attached to the immersion tank body (10) of the immersion tank (1) or a pipe near the immersion tank body (10).

As a dip coating method in the dip tank (1), the cylindrical substrate (W) is vertically held from the inner peripheral surface by a transfer device such as a robot hand, and the cylindrical substrate (W) is placed in the overflowing coating solution. A conventionally known method of vertically lowering the cylindrical substrate (W) after vertically lowering the cylindrical substrate (W) and immersing it in the coating solution is applied. Immersion speed is 500 ~
2000 mm / min, pulling speed (coating speed) 200-1
About 000 mm / min (Japanese Patent Publication No. 5-45951,
See JP-A-5-72760 and JP-A-5-88384.

In the immersion treatment as described above, the vibrating device (6) for applying a predetermined frequency of vibration to the coating liquid in the immersion tank (1) is provided with a vibration of the liquid surface caused by other external vibrations. As a result, the liquid level of the coating liquid can be stably maintained, and the stationary state can be further approached. As a result, it is possible to effectively prevent the occurrence of coating unevenness called a so-called gear mark on the surface of the cylindrical substrate (W).

The reason why the surface of the coating liquid is stabilized by vibrating the coating liquid in the immersion tank (1) positively is considered as follows. That is, the immersion tank body (10) and the cylindrical substrate (W) immersed therein each have a natural frequency, and when these elements are immersed in the cylindrical substrate (W), the external frequency is reduced. Is propagated from the immersion tank body (10) and the cylindrical substrate (W), and the coating liquid itself has a predetermined natural frequency.
The vibration of the immersion tank body (10) and the cylindrical substrate (W) is further amplified in the coating liquid. As a result, a specific vibration (fluctuation of the liquid surface) causing uneven coating on the liquid surface of the coating liquid.
Is considered to be further increased. In contrast, when the coating liquid is vibrated at a frequency of about 10 to 500 Hz,
It is considered that such vibration acts on the liquid surface so as to cancel the amplitude of the vibration that causes coating unevenness.

When the vibration and unevenness of the coating liquid were experimentally confirmed, for example, in the case of the CG liquid, when the vibration in the range of about 1 to 10 Hz was applied around about 3 Hz, the amplitude of the liquid surface was changed. And the amplitude of the liquid surface is 5 μm or more, especially 15 μm
When a vibration having a strength of at least m was applied, it was found that coating irregularities were extremely likely to occur regardless of the diameter of the immersion tank body (10) or the cylindrical substrate (W). On the other hand, when a vibration having a frequency of about 10 to 500 Hz is given, the amplitude of the liquid surface is in a range of about 15 to 25 μm without being affected by the strength of the vibration, and the occurrence of coating unevenness is reduced. It was confirmed that it was not present (see FIG. 2). The change in the liquid level can be measured by a displacement sensor, and the vibration and the magnitude of the coating liquid can be measured by using a vibration analysis technique.

In the present invention, if a pump having an appropriate pulsation is selected as the circulating pump (3), the circulating pump (3) itself is used as a vibrating means instead of the above-described vibration device. You can do it. That is, the circulating pump (3) is a pump that can apply the vibration of the predetermined frequency to the application liquid in the immersion tank (1).
Specifically, for example, Toko Sangyo; Ibex MO
A quantitative rotary pump such as a G pump (trade name) can be used. Such a pump gives an appropriate pulsation to the discharged coating liquid by the two rotors, and as a result, can apply a predetermined vibration to the coating liquid in the immersion tank (1) through the supplied coating liquid.

Further, in the dip coating apparatus of the present invention, a coating liquid for the charge generation layer whose viscosity is adjusted to 1 to 10 cps is particularly suitable as the coating liquid. In the operation using such a coating liquid, Application unevenness can be effectively prevented.

[0031]

As described above, according to the dip coating apparatus for an electrophotographic photosensitive member of the present invention, a vibrating apparatus for applying a predetermined frequency to the coating liquid in the dip tank is externally applied. Fluctuations in the liquid level due to other vibrations can be canceled out, and the liquid level of the coating liquid can be stably maintained, so that coating unevenness on the surface of the cylindrical substrate can be further reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram showing main constituent members of a dip coating apparatus for an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a graph showing the relationship between the frequency of vibration applied to a coating liquid in an immersion tank, the amplitude of a liquid surface, and the occurrence of coating unevenness.

[Explanation of symbols]

 1: Immersion tank 10: Immersion tank body 11: Gutter member 2: Storage tank 3: Circulation pump 51: Circulation pipe 52: Circulation pipe 53: Circulation pipe 54: Circulation pipe (branch pipe) 55: Piping for circulation W: Cylindrical substrate

Claims (4)

[Claims] 1. A dip coating apparatus for forming a coating film of a photoreceptor material on a surface of a cylindrical substrate, comprising: a dip tank containing a coating liquid as a photoreceptor material and receiving the cylindrical substrate; A storage tank for preparing and storing the coating liquid; a circulation pipe and a circulation pump for circulating the coating liquid between the immersion tank and the storage tank;
A dip coating apparatus for an electrophotographic photosensitive member, further comprising a vibrating means for giving a vibration of up to 500 Hz. 2. A dip coating apparatus for forming a coating film of a photoreceptor material on a surface of a cylindrical substrate, the dip tank containing a coating liquid as a photoreceptor material and receiving the cylindrical substrate, A storage tank for preparing and storing the coating liquid, comprising a circulating pipe and a circulation pump for circulating the coating liquid between the immersion tank and the storage tank, and wherein the circulating pump causes the pulsation of the immersion tank. An immersion coating apparatus for an electrophotographic photosensitive member, which is a pump for applying a vibration of 10 to 500 Hz to the coating liquid. 3. An immersion tank, wherein an upper end is opened and a coating liquid is supplied from a lower end side, and a gutter member provided on an upper outer peripheral side of the immersion tank main body and containing an overflowing coating liquid is provided. The dip coating device for an electrophotographic photosensitive member according to claim 1, wherein the dip coating device comprises: 4. The dip coating apparatus for an electrophotographic photoreceptor according to claim 1, wherein the coating liquid is a coating liquid for a charge generation layer.