JPH07178367A - Application method - Google Patents

Abstract

(57) [Summary] [Problem] To provide an industrially advantageous coating method capable of forming a sufficiently smooth coating film even when a solvent type coating solution having a high drying rate is used as a coating solvent. [Application] In a coating method in which a cylindrical or columnar substrate is horizontally supported and rotated, the coating liquid is spirally supplied from a coating liquid supply pipe that moves along the axial direction of the substrate to the surface of the substrate. A smoothing member (18) that moves together with the liquid supply pipe (17) along the axial direction of the substrate (1).
Is contacted with the coating surface to smooth the coating film. [Effect] In particular, the coating method of the present invention can be preferably used in the method of manufacturing an electrophotographic photosensitive member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method, and more particularly to a coating method improved from the spiral coating method, which is a coating film which is sufficiently smoothed by employing simple and easy smoothing means. The present invention relates to an industrially advantageous coating method capable of forming a film.

[0002]

2. Description of the Related Art Conventionally, a spiral coating method has been known as one of coating methods for the surface of a cylindrical or cylindrical substrate. The spiral coating method is a coating method in which a cylindrical or cylindrical substrate is horizontally supported and rotated while the coating liquid is supplied to the surface of the substrate spirally from a coating liquid supply pipe that moves along the axial direction of the substrate. is there.

[0003]

However, since the conventional spiral coating method is a method for forming a smooth coating film by expecting the wettability between the coating liquid and the substrate and the fluidity of the coating liquid, When a solvent type coating solution is used, there is a drawback that it is difficult to form a sufficiently smooth coating film because the drying rate of the coating solution on the surface of the substrate is high.

The present invention has been made in view of the above circumstances, and an object thereof is to form a sufficiently smooth coating film even if a solvent type coating solution having a high drying rate is used as a coating solvent. It is to provide an industrially advantageous coating method.

[0005]

That is, the gist of the present invention is that a cylindrical or columnar substrate is supported horizontally and is rotated and moved along the axial direction of the substrate from the coating liquid supply pipe to the surface of the substrate. In the coating method of spirally supplying the coating liquid to the substrate, a smoothing member that moves along the axial direction of the substrate together with the coating liquid supply pipe is brought into contact with the coating surface to smooth the coating film. Exist in.

The present invention will be described in detail below. The coating method of the present invention is a coating method which is an improvement of the spiral coating method, and can be particularly suitably used for the method of manufacturing an electrophotographic photoreceptor. That is, the coating liquid for forming the charge generation layer and the charge transfer layer is usually prepared as a solvent type coating liquid, and it is difficult to form a sufficiently smooth coating film by the conventional spiral coating method. However, according to the coating method of the present invention, a sufficiently smooth coating film can be easily formed.

FIG. 1 is an explanatory view showing an example of a coating apparatus for carrying out the coating method of the present invention, and FIG. 2 is a sectional explanatory view of a main part of the coating apparatus shown in FIG.

The coating apparatus illustrated in FIG. 1 is a substrate rotating mechanism for horizontally supporting and rotating a cylindrical or columnar substrate, and a coating device for supplying a coating liquid to the surface of the substrate while moving in the axial direction of the substrate. A solvent supply that mainly comprises a liquid supply mechanism and a smoothing member that moves along the axial direction of the substrate together with the coating liquid supply pipe, and in a preferred embodiment, supplies a solvent to the surface of the smooth member that comes into contact with the coating surface. Equipped with means.

The substrate (1) is not particularly limited, and in the case of a substrate for an electrophotographic photoreceptor, a glass tube, an aluminum extruded tube, an aluminum drawn tube, an aluminum cutting tube, a resin tube, a paper tube, an electrophotographic photoreceptor. For example, a reclaimed tube whose surface coating film has been removed after being used as is used.

The substrate rotating mechanism has support plates (2), (2) vertically arranged on the left and right with a predetermined gap, and bearings (not shown) in through holes provided in the upper portions of the respective support plates. A rotating shaft (3) arranged horizontally via
(3) A gear (4) fixed to one of the rotating shafts, a gear driving motor (5), and a timing belt (6) for transmitting the rotational drive of the motor (5) to the gear (4). There is.

The rotation of the cylindrical base body (1) is provided with a fitting hole for the rotating shaft (3) at the center and flanges (7), (7) preliminarily attached to both ends of the base body (1). Is done using. That is, after mounting the flanges (7) and (7) on both ends of the base body (1), the base body (1) is arranged between the rotary shafts (3) and (3), and one rotary shaft is moved forward, The rotary shaft (3) is attached to each central hole of the flanges (7) and (7),
(3) is fitted and the gear driving motor (5) is driven to rotate the substrate (1). The flanges (7) and (7) are mounted so that the axes of the base bodies determined by the respective center holes of the flanges are aligned.

The coating liquid supply mechanism comprises support plates (8), (8) arranged vertically with a predetermined space between them, and two guide rods (9) arranged between the support plates. (9), between the support plates (8), (8) and between the guide rods (9), (9), and one end of which is a screw screw (1) protruding from the support plate (8).
0), the gear (11) fixed to the end of the screw screw (10) projecting from the support plate (8), the gear driving motor (12), and the rotational drive of the motor (12) to the gear (11). Through the timing belt (13) for transmission, the fitting holes of the guide rods (9) respectively provided on the left and right sides thereof, and the bearing portion of the ball screw into which the screw screw (10) provided at the center of the fitting hole is fitted. Moving body (14) arranged between the supporting plates (8), (8), the surface of the base body (1) having one end fixed to the moving body (14) and the tip nozzle portion thereof arranged horizontally A flexible coating liquid supply pipe (15) arranged toward, a coating liquid container (16) arranged on the other end side of the coating liquid supply pipe (15), and a coating liquid supply pipe (15) in the middle thereof. Metered pump (1
7).

In the illustrated coating liquid supply mechanism, the movable body (14) is provided with only one coating liquid supply pipe (15), but it may be provided with a plurality of coating liquid supply pipes at a predetermined interval. Alternatively, it is also possible to provide a single coating liquid supply pipe in which the metering pump (17) is shared and the tip nozzle portion has a plurality of branched structures. Details of the internal structure of the moving body (14) will be described later.

The smoothing member (18) is the surface side of the moving body (14) facing the base body (1), and the tip nozzle of the coating liquid supply pipe (15) fixedly mounted on the moving body (14). It is arranged at a rear position with respect to the traveling direction of the moving body (14). Then, as shown in FIG. 2, the moving body (14) is
It has a box-shaped structure, and an air cylinder (1
9), L-shaped smooth member support plate (20), smooth member (18), and solvent supply pipe (2) as a preferred embodiment.
1) etc. are stored.

That is, the air cylinder (19) is fixed to the rear wall of the box-shaped moving body (14), and the smooth member supporting plate (20) has its horizontal portion positioned above and projects forward. And is fixed to the tip of the drive rod (22) of the air cylinder (19) in the lower part of the vertical part thereof, and the smooth member (18) is the lower part of the vertical part of the smooth member support plate (20). The solvent supply pipe (21) is inserted and arranged in a through hole provided in the through hole of the rear wall of the box-shaped moving body (14), and is bent downward from the middle thereof so that the tip nozzle portion is It is arranged so as to be located above the end surface of the smooth member (18). The arrangement structure of the solvent supply pipe (21) is such that a through hole having an opening on the base body (1) side is provided in the smooth member (18) and the solvent supply pipe (21) is passed through the through hole. Good. Smoothing member (18) and coating liquid supply pipe (15)
The distance (gap) from the tip nozzle part is determined in consideration of the drying speed of the coating liquid, but is usually selected from the range of about 0 to 30 mm.

The lower portion of the front wall of the box-shaped moving body (14) is in contact with the lower portion of the vertical portion of the smooth member supporting plate (20), and the smooth member (1) formed by the air cylinder (19).
8) Adjusting bolt (23) so as to regulate the forward distance of
Is provided. As shown in FIG. 1, the smoothing member (18) moves in parallel with the coating liquid supply pipe (15) along the axial direction of the substrate (1), and the coating liquid supplied to the surface of the substrate (1). It has the effect of homogenizing the liquid. That is,
The smooth member (18) allows the coating liquid to exist in a bridge shape between itself and the substrate (1) due to surface tension, or crushes the ridges of the coating liquid and moves the same to make the thickness of the coating liquid uniform. Have an effect. As a result of the action of such a smoothing member (18), a coating film having a constant film thickness that follows the surface shape of the substrate (1) is obtained.

Therefore, the shape of the smooth member is not particularly limited as long as its end face is smooth, and for example, a smooth plate is vertically attached to the tip of a cylindrical body or prism or a support rod cut perpendicular to the axis. It is possible to use the members provided in the. The width of the smooth member corresponding to the diametrical direction of the substrate is required to have a size capable of forming a bridge of the coating liquid with the substrate, and it is necessary to increase the width as the diameter of the substrate increases. About 5 to 50 mm is sufficient. The width of the smoothing member corresponding to the axial direction of the substrate is determined depending on the straightness of the substrate, but usually about 5 to 100 mm is sufficient.

The material constituting the smoothing member is not particularly limited, but a material that is difficult to wet with the coating liquid used is suitable. When the smoothing member is made of a material that easily wets the coating liquid, the coating liquid adheres to the smoothing member when the smoothing member comes into contact with and separates from the coating liquid applied to the surface of the substrate,
The smooth coating surface formed on the surface of the substrate may be disturbed. Usually, it is preferable that the smoothing member is made of a Teflon material or a Teflon coating material.

Further, the smoothing member (18) moves following the surface shape of the substrate (1), but if the straightness of the substrate (1) is too poor, the smoothing member (18) is moved to move the substrate. The surface of (1) may be scratched. Therefore, in order to deal with such a problem, it is preferable to bond a thin rubber material to the surface of the smooth member (18) to form the elastic layer.

The smooth member (18) illustrated in FIG. 2 is composed of a Teflon cylinder, and has a threaded portion (1) at one end thereof.
8a) and a stopper (18b) in the middle thereof. The smooth member (18) has a height such that the central portion of the smooth end face thereof opposes the central point of the base body (1).
A screw part (18a) is inserted and arranged in a through hole above the vertical part of the smooth member support plate (20), and a bolt (24) is screwed into the protruding part of the screw part (18a).
A spring (25) is interposed between the vertical portion of the smooth member support plate (20) and the stopper (18b).

Therefore, the surface of the smoothing member (18) in contact with the coating surface of the substrate (1) has a roundness of the substrate (1) and a thickness of the coating liquid due to the elastic action of the spring (25). It is made to follow forward and backward freely. When the size of the base body (1) is different, the maximum forward distance of the smooth member (18) can be adjusted by the adjusting bolt (23).

The coating method of the present invention is carried out as follows using the coating apparatus as described above. In other words, the substrate rotating mechanism supports the substrate (1) horizontally and rotates the coating liquid from the coating liquid supply pipe (15) moving along the axial direction of the substrate to the surface of the substrate (1) in a spiral shape. Supply.
The coating solution is supplied so that the wet film thickness on the surface of the substrate (1) calculated from the rotation speed of the substrate (1) and the moving speed of the coating solution supply pipe (15) is in the range of 5 to 400 μm. preferable. At the same time, a smoothing member (18) that moves in parallel with the coating liquid supply pipe (15) along the axial direction of the substrate (1) is brought into contact with the coating surface to smooth the coating film. .

In a preferred embodiment of the present invention, a solvent in which the coating liquid is soluble is attached to the surface of the smoothing member (18) which comes into contact with the coating surface to bring the smoothing member (18) into contact with the coating surface. Let When the solvent of the solvent-type coating liquid has a particularly low boiling point (for example, 60 to 100 ° C.), the smoothing member (1
Although it may be difficult to smooth the coating film on the surface of the substrate (1) by 8), according to a preferred embodiment of the present invention, smoothing can be easily performed even in such a case. Usually, the same solvent as that used for preparing the coating liquid is used as the solvent.

The solvent is adhered to the surface of the smoothing member (18) by the solvent supplied from the solvent supply pipe (21), but the solvent does not necessarily have to be continuously supplied. Therefore, for example, it suffices to use a syringe-type supply jig (26) as shown in FIG. Of course, the supply can also be performed by the liquid head difference. Usually, the supply of the solvent from the solvent supply pipe (21) has a diameter of 0.5 to 2 mm.
Each droplet is performed at an appropriate timing, and when the smoothness of the coating film is not good, the solvent is constantly supplied.

As the coating liquid, any coating liquid can be used as long as it is a coating liquid to which the spiral coating method can be applied. In the production of an electrophotographic photoreceptor, the coating method of the present invention can be applied to the formation of a conductive layer, an undercoat layer, a charge generation layer, a charge transfer layer, a coating layer and the like. In particular, the present invention is suitable for a solvent type coating liquid, that is, a coating liquid using a solvent having a high drying rate. Of course,
In the present invention, if necessary, coating and smoothing treatment may be performed in a space covered with a solvent vapor, and then drying may be performed in a space where evaporation of the solvent is promoted. Specifically, using an applicator equipped with a suitable detachable cover, perform coating and smoothing with the cover covered,
It is also possible to perform drying with the cover removed.

However, in the present invention, a coating film can be formed well without controlling the drying rate as described above. In addition, a coating solution that causes a large change in volume of the coating film by curing after coating, for example, a volume change of the coating film is 50%
In the case of the above-mentioned coating liquid, the coating, smoothing, and curing treatments can be performed as a series of operations, and the operations can be repeated.

The means for gripping the base body is not particularly limited as long as it is a means for gripping the axis of the base body so that the axis of the base body comes out. Means (internal expansion type collect chuck) or the like can be adopted. Further, in the case of a cylindrical base body, a gripping means or the like which holds the base body in contact with both end surfaces thereof can be adopted.

[0028]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following examples, the coating device shown in FIGS. 1 and 2 equipped with a Teflon cylinder having a diameter of 8 mm was used as a smoothing member, and a charge generation layer and a charge transfer layer were coated on the surface of an aluminum drum. To produce an electrophotographic photoreceptor.

The coating liquid for the charge generation layer was prepared by the following method. That is, first, 200 parts by weight of n-propanol was added to 10 parts by weight of oxytitanium phthalocyanine, and the mixture was pulverized and dispersed by a sand grind mill for 10 hours. Next, polyvinyl butyral (Denka Butyral # -6000 manufactured by Denki Kagaku Kogyo Co., Ltd.)
Then, 5 parts by weight of a 10% by weight methanol solution of C ") was added, mixed and dispersed to obtain a coating liquid for the charge generation layer.

The coating liquid for the charge transfer layer was prepared by the following method. That is, 56 parts by weight of a hydrazone compound represented by the following chemical formula [I], 14 parts by weight of a hydrazone compound represented by the following chemical formula [II], 1.5 parts by weight of a cyano compound represented by the following chemical formula [III], a polycarbonate resin 100 parts by weight (“Novarex 7030A” manufactured by Mitsubishi Kasei Co., Ltd.) was dissolved in a mixed solvent of 500 parts by weight of 1,4-dioxane and 500 parts by weight of tetrahydrofuran to obtain a coating liquid for a charge transfer layer.

[0031]

[Chemical 1]

Example 1 First, an aluminum drum (diameter 3
Flange was attached to both ends (0 mm, length 266 mm). The flange was mounted so that the drum axis determined by each central hole of the flange would match. An aluminum drum was arranged between the rotating shafts of the substrate rotating mechanism, the rotating shafts were fitted in the center holes of the flanges at both ends, and the gear driving motor was driven to rotate the aluminum drum at 200 rpm.

Next, the tip of the coating liquid supply pipe is provided on the surface of the rotating aluminum drum (nozzle hole diameter: 0.
The coating liquid for the charge generation layer was supplied in a spiral shape from 5 mm) to perform coating. The coating conditions are 0.5 and 0.5.
7 cc / min. The moving speed of the moving body (the tip nozzle portion of the coating liquid supply pipe) was 3 mm / rotation, and the wet film thickness on the drum surface was 10 μm. In addition, the gap between the aluminum drum and the smoothing member was adjusted by an adjusting bolt so that the gap was 20 to 30 μm. That is, when the gap measuring spacer is inserted into the gap between the smoothing member and the aluminum drum along the entire length along the axis, it is 2
The 0 μm gap measuring spacer passes everywhere, but the 30 μm gap measuring spacer does not pass depending on the straightness of the aluminum drum.

On the other hand, on the surface of the smoothing member that comes into contact with the coating surface, one drop of the same solvent as used in the preparation of the coating liquid for the charge generation layer was supplied from the solvent supply pipe to smooth the solvent. The surface of the member is brought into contact with the coating surface of the drum surface, and the coating and smoothing treatment is performed from the position of 10 mm from the end of the drum to the final end, and the surface of the smoothing member which comes into contact with the coating surface during the process. Was also fed with 2 drops of solvent at intervals.

In the above coating and smoothing treatment,
The following phenomena were observed. That is, at the position before the smoothing treatment, the coated surface on the surface of the drum had a large uncoated portion, but at the position after the smoothing treatment, a uniform coating surface was formed. Then, in the observation of the coated surface after air-drying, the coating film is uniform, and the phthalocyanine color that predicts coating film unevenness in comparison with a sample obtained by the dip coating method using the same coating solution is used. There was no shading. Such light and shade was not observed even at the position where the solvent was dropped on the surface of the smoothing member.

Next, the tip of the coating liquid supply pipe is provided on the surface of the drum on which the charge generation layer is formed (nozzle hole diameter: 0.
The coating liquid for the charge transfer layer was supplied in a spiral shape from 8 mm) to perform coating. The coating condition is 4.3.
cc / min. The wet film thickness on the drum surface was 75 μm, and the other conditions were the same as above. However, the solvent was not additionally supplied to the surface of the smoothing member that was in contact with the coating surface, and the gap between the charge generation layer formed on the aluminum drum and the smoothing member was 50 to 60 by a gap meter.
It was adjusted to be μm.

After air-drying the coated surface (at 130 ° C. for 20 minutes), the film thickness was measured by spectral interferometry at a total of 80 points, that is, 4 strands in the circumferential direction and 20 spots from 15 to 251 mm for each strand. As a result, the average value was 18.7 μm and the maximum value was 1.
The value was 9.0 μm and the minimum value was 18.5 μm.

[0038]

According to the present invention described above, a coating film which is sufficiently smoothed by employing a simple and easy smoothing means even when a solvent type coating liquid having a fast drying rate is used as a coating solvent. An industrially advantageous coating method capable of forming
In particular, the coating method of the present invention can be preferably used in the method for producing an electrophotographic photosensitive member.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a coating apparatus for carrying out a coating method of the present invention.

FIG. 2 is a cross-sectional explanatory view of a main part of the coating device shown in FIG.

[Explanation of sign]

 1: Base 3: Rotating Shaft 10: Screw Screw 14: Moving Body 15: Coating Liquid Supply Pipe 17: Metering Pump 18: Smoothing Member 19: Air Cylinder 20: Smoothing Member Support Plate 21: Solvent Supply Pipe

Claims (2)

[Claims] 1. A coating method for supplying a coating solution in a spiral shape from a coating solution supply pipe that moves in the axial direction of the substrate while horizontally supporting and rotating a cylindrical or cylindrical substrate. A coating method, wherein a smoothing member that moves along the axial direction of the substrate together with the coating liquid supply tube is brought into contact with the coating surface to smooth the coating film. 2. The coating method according to claim 1, wherein a solvent in which the coating liquid is soluble is attached to the surface of the smoothing member that comes into contact with the coating surface to bring the smoothing member into contact with the coating surface.