JPH08243477A - Method for formation of coating film - Google Patents

Abstract

PURPOSE: To enhance outer diameter accuracy and outer surface smoothness by moving a coating surface forming member in the tangential direction of a coated surface at the final contact position with a coating surface or delivering the surface of the forming member to which a coating soln. is bonded to separate the forming member from the coated surface. CONSTITUTION: A continuous film is formed on the surface of a base material 1 by a coating soln. supply mechanism while the base material 1 is horizontally supported to be rotated. Subsequently, a coating surface forming member 18 is rotated in the direction shown by an arrow before the coating soln. on the surface of the base material 1 loses flowability and made parallel to the axial line of the base material 1 to be brought into contact with a coating surface and this rotation is performed over the rotations of 3-30 of the base material 1. Thereafter, the forming member 18 is rotated and separated from the coating surface without being moved. This rotary direction is desirably made same to the rotary direction of the base material l. The A-part of the forming member 18 does not come into contact with the coating soln. at all during one rotation. By separating the forming member 18 from the coating surface by using the A-part, separation effect is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating film forming method, and more particularly, to a coating film forming method using a coating method of discharging a coating liquid from a nozzle or a slit.
Particularly, it is preferably used for correcting outer diameter accuracy such as straightness, roundness, cylindricity, and surface roughness of the outer diameter of a base material (for example, an aluminum extruded tube) in the production of a substrate for an electrophotographic photoreceptor. The present invention relates to a coating film forming method.

[0002]

2. Description of the Related Art Conventionally, a high degree of outer diameter accuracy is required particularly in the case of a substrate for an electrophotographic photoreceptor. For example, a diameter of 30.
In the case of a 0 mm substrate, its cylindricity is required to be 100 μm or less. Such a base having a high outer diameter accuracy is, for example, an aluminum extruded tube having a constant thickness as a base material, drawn out,
Even if thinning processing such as cutting, ironing and impact is not easily achieved, there is a problem that the higher the outer diameter accuracy is, the higher the processing cost becomes. On the other hand, one of the methods for forming a coating film on the surface of a cylindrical or columnar substrate
As one, a method of discharging the coating liquid from a nozzle or a slit is known. In these coating methods, the substrate is horizontally supported and rotated, and the coating liquid is supplied to the surface in a spiral shape, a ring shape, or a curtain shape, and a uniform coating film is formed by the fluidity of the coating liquid. Is the way.

[0003]

However, these conventional coating methods are methods for forming a uniform coating film by relying on the fluidity of the coating solution, and therefore, for example, the straightness and the perfect circle of the substrate itself are not used. When the degree is low, there is a drawback that these appear as they are on the surface of the coating film. These problems also occur in the method of applying the resin using a blade with a constant gap from the surface of the base material. For example, Japanese Patent Application Laid-Open No. 54-38801 discloses a method of forming a coating film using a coating liquid held in a gap portion between a blade and a surface of a substrate, but the gap is constant. Therefore, the outer diameter shape of the substrate appears as it is on the surface of the coating film. In particular, the diameter of the cylinder or cylinder formed by the fixed outer surface of the coating film is the diameter before coating plus twice the constant gap value. Therefore, when the straightness or roundness of the substrate itself is low, However, these low outer diameter precisions appear as they are on the surface of the coating film, and the outer diameter precision is not corrected.

Also, when the outer coating surface is formed by using a bar having a circular cross section or a blade having a knife-edge-shaped tip as already proposed by the present inventors, when the forming member is in contact with the coating surface. The accuracy of the outer surface to be formed is very good, but when the forming member is released, it disturbs the coating surface,
There is a problem that the accuracy at the time of contact is impaired.

That is, the present invention has been made in view of the above circumstances, and its purpose is to improve the outer diameter accuracy and the outer surface smoothness regardless of the processing accuracy of a cylindrical or cylindrical base material. It is an object of the present invention to provide an improved coating film forming method capable of achieving a uniform outer surface in which no band-shaped irregularities are formed in the central portion.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is to continuously support a cylindrical or columnar base material while horizontally supporting and rotating the base material while supplying an excessive amount of coating solution to the surface of the base material. Before the coating liquid loses fluidity, the coating surface forming member is made parallel to the rotation axis so as to keep a constant distance from the rotation axis of the base material and brought close to the coating surface. A method for forming a coated surface, which comprises separating the forming member from the coated surface by a method satisfying at least one of the following two conditions, and further forming the coated surface: A coating film forming method, characterized in that the member is a coating surface forming member having a constant cross section having a radius that decreases uniformly or gradually from the position where it comes into contact with the coating surface and then decreases, It is necessary to make the forming member parallel to the rotation axis of the substrate and separate it from the coating surface. In a coating film forming method according to symptoms. (B) It has a moving component in the tangential direction of the coating surface at the final contact position with the coating surface. (B) The surface of the forming member on which the coating liquid is not adhered is drawn out.

That is, when the coating surface forming member is used to improve the roundness, straightness, etc. of a cylinder or a cylinder by coating, the forming member is approaching the coating surface, or a proximity operation is performed. While stopping at the position where the rear outer surface is formed, if the removed excess coating liquid is successfully removed from the coating liquid surface forming member, a coating surface that is very smooth and has no unevenness is formed. However, when the forming member is subsequently separated from the coating surface, the coating surface, which should be smoothly formed, is disturbed. If the coating surface forming member is coated with Teflon to increase the liquid repellency or if the tip is knife-edge shaped to reduce the contact area with the coating liquid, the disturbance of the coating surface will be small, but it is insufficient.

As a result of various studies on these problems, it has been found that not only the rotational movement of the substrate but also the movement of the coating surface forming member in the tangential direction of the coating surface with respect to the coating surface reduces the disturbance of the coating surface. did. Further, when the coating surface forming member is separated from the coating surface, the contact portion between the coating surface and the coating surface of the forming member is kept parallel, and the peeling of the member from the coating surface is almost over the entire coating surface. It turned out to be desirable to happen at the same time. Furthermore, when the coating liquid surface forming member separates from the coating surface, and the removed coating liquid exists at the coating surface contact portion of the member, the coating liquid itself that has been adhered and removed determines the coating surface shape, not the member. It became clear that they would. In short, the member must be separated from the surface of the coating liquid while feeding out the surface on which the coating liquid is not adhered. The present invention has been achieved as a result of various studies on coating surface forming operations that satisfy the above requirements.

The present invention will be described in detail below. The coating film forming method of the present invention can be suitably used particularly for a method of manufacturing a substrate of an electrophotographic photoreceptor. That is, for example, when a coating liquid containing an ultraviolet curable resin is used as the coating liquid to improve the outer shape accuracy of the surface of the base material to manufacture the base body of the electrophotographic photosensitive member, cutting, ironing, impact processing, etc. It is possible to manufacture a base material having the required outer shape accuracy by a simple additional process called coating, regardless of the thinning of the metal material.

1 and 2 are explanatory views showing an example of a coating apparatus for carrying out the coating film forming method of the present invention. FIG. 1 shows a single nozzle discharge method, and FIG. 2 shows a large number of nozzle discharge methods. It is the figure which was adopted and is an explanatory view when the coating film forming method of the present invention is applied to a method of manufacturing a substrate of an electrophotographic photoreceptor. The coating apparatus illustrated in FIG. 1 employs a method of discharging the coating liquid in a spiral form from a nozzle, and the coating apparatus illustrated in FIG. 2 adopts a method of discharging the coating liquid in a ring shape from a nozzle. However, in the present invention, the method for supplying the coating liquid is not particularly limited, and in addition to the above, a method for supplying the coating liquid in a curtain shape or the like can also be adopted, both of which form a continuous coating film. It is preferable.

The coating apparatus illustrated in FIG. 1 comprises a base material rotating mechanism for horizontally supporting and rotating a cylindrical or cylindrical base material, and a coating liquid on the surface of the base material while moving in the axial direction of the base material. And a UV-curable resin as a coating liquid, which is mainly composed of a coating liquid supply mechanism for supplying the coating liquid, a rotating member arranged in parallel with the axis of the base material, and optionally, a coating surface forming member capable of advancing and retracting. A coating solution containing a is used, and an ultraviolet irradiation device for curing the coating solution is provided.

The substrate (1) is not particularly limited, and in the case of a substrate for an electrophotographic photosensitive member, a glass tube, an aluminum extruded tube, an aluminum drawn tube, an aluminum cutting tube, a resin tube, a paper tube, an electrophotographic photosensitive material. A reclaimed tube or the like, which is used as a body once and then the coating film on the surface is removed, is used.

The base material rotating mechanism includes a support plate with bearings (2) vertically arranged on the left and right at a predetermined interval.
(2) The rotary shafts (3), (3) horizontally arranged via bearings (not shown) in through holes provided in the upper part of each support plate, and fixed to one rotary shaft. It is composed of a gear (4), a gear driving motor (5), and a timing belt (6) for transmitting the rotation of the motor (5) to the gear (4).

The rotation of the cylindrical base material (1) is provided with a fitting hole for the rotary shaft (3) at the center and flanges (7), ( 7) is used. That is, after mounting the flanges (7) and (7) on both ends of the base material (1), the base material (1) is arranged between the rotary shafts (3) and (3) and one rotary shaft is moved forward. Then, 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 base material (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 includes support plates (8), (8) arranged vertically with a predetermined space therebetween, and two guide rods (9) arranged between the support plates. (9) A ball screw (1) disposed between the support plates (8) and (8) and between the guide rods (9) and (9) and having one end protruding from the support plate (8).
0), ball screw (1) protruding from the support plate (8)
The gear (11) fixed to the end of (0), the gear driving motor (12), and the rotation of the motor (12) are rotated by the gear (11).
To the timing belt (13), the fitting holes of the guide rods (9) respectively provided on the left and right sides of the timing belt (13), and the ball screw bearing portion for fitting the ball screw (10) provided at the center of the fitting hole. Support plates (8), (8)
A movable body (14) disposed between the two, flexible coating in which one end of the movable body (14) is fixed to the movable body (14) and the tip nozzle portion thereof is arranged toward the surface of the base body (1) arranged horizontally. Liquid supply pipe (15), coating liquid container (16) arranged at the other end of coating liquid supply pipe (15), coating liquid supply pipe (1)
It is composed of a metering pump (17) arranged in the middle of 5). In the illustrated coating liquid supply mechanism, the movable body (14) is provided with only one coating liquid supply pipe (15), but it is also possible to provide a plurality of coating liquid supply pipes at a predetermined interval. It is also possible to provide a single coating liquid supply pipe in which the metering pump (17) is common and the tip nozzle portion has a plurality of branched structures. The tip nozzle portion of the coating liquid supply pipe (15) is usually located right above the base material (1). . The liquid discharged from the tip of the nozzle should not form a continuous film and should not be applied in a spiral or ring shape. In order to form a continuous film, it is preferable to adopt a method in which the tip of the nozzle is flexible and the coating surface is rubbed while ejecting, a method in which a blade for smoothing immediately after ejection is provided, and the like.

The structure of the coating apparatus illustrated in FIG. 2 is the same as that of the coating apparatus illustrated in FIG. 1 except for the coating liquid supply mechanism, and therefore another coating liquid supply mechanism will be described.
In the coating liquid supply mechanism shown in FIG. 2, the L-shaped member (25) supporting the nozzle head (26) is attached with a ball screw (28) 〆 screw (not shown), and the motor (29) is rotated forward and backward. This moves the nozzle head up and down. A nozzle row (27) is attached to the nozzle head (26).

There is a pump driving motor, a pump (17), a discharge pipe (15) connected to the pump, and a suction pipe (15 '). The discharge pipe (15) is connected to the nozzle head (26). It is in a row. The suction tube is connected to the coating container (16). The nozzle head (26) has a cleaning cut tube (30), which is used for cleaning the nozzle head. Figure 2
Then, a slit may be provided instead of the nozzle row (27).

The coating surface forming member (18) has an elongated shape, for example, a rod shape as shown in FIG.
As shown in FIG. 4, both ends of the coated surface forming member (18) are supported by bearings (20) and (20), and one shaft of the bearing is further provided with an extension gear (21).
A timing belt (22) is hung on the gear (21), and the belt is moved by the drive of a geared motor provided at the other end of the support. When the belt is moved, the gear is rotated and the coating surface forming member is rotated.

The coating surface forming member is arranged parallel to the rotation axis of the substrate (1), and its length is made longer than the coating length of the substrate (1) in the axial direction, and the substrate (1). The portion located parallel to the axis of is made linear. In terms of production, the member (18) is desired to have a uniform cross section, and has a rotation axis (19). A particularly preferable cross-sectional shape of the member is a constant cross-sectional shape having a uniform radius or a gradually increasing radius from a position where the contact with the coating surface is started, and then a decreasing radius. The portion that first faces the coating surface is closest to the rotation axis, and the member surface does not reduce the distance from the rotation axis by rotation up to an angle.

If the above conditions are satisfied, the specific shape can be selected quite freely. Some examples (1) and (2) in FIG.
Shown in (1) shows an example of a sectional shape in which a part of an arc is linearly cut out, and (2) shows a part of the arc is cut out in a curved shape to have an elliptical arc with a small radius. An example of a cross-sectional shape is shown. The coated surface forming member having such a shape has high straightness. It can be easily achieved by processing rods and pipes. The forming member obtained by these processes is arranged so that the central axis of the forming member and the central axis of the base material (1) are positioned in parallel.

The material forming the coating surface forming member (18) is not particularly limited, but a material that is difficult to wet with the coating liquid used is suitable. When the coating surface forming member is made of a material that easily wets the coating liquid, the coating liquid adheres to the coating surface forming member when the coating surface forming member comes into contact with and separates from the coating liquid coated on the surface of the substrate. The smooth coating surface formed on the surface of the base material may be disturbed. Usually, as the coating surface forming member (18), a metal main body processed with Teflon or the like is applied.

The UV irradiator is required as long as it uses a coating solution containing an ultraviolet curable resin, and may be an apparatus having a structure capable of irradiating UV light over the coating surface in the axial direction of the base material. When a thermosetting resin or the like is used as the coating liquid, a hot air generator is used instead of the ultraviolet irradiation device.

The coating film forming method of the present invention is carried out as follows using the coating apparatus as described above. First, while the base material rotating mechanism horizontally supports and rotates the base material (1), the coating liquid supply mechanism supplies the coating liquid to the surface of the base material (1) to form a continuous film. Next, before the coating liquid on the surface of the base material (1) loses fluidity, the coated surface forming member (18) is made parallel to the axis of the base material (1) and brought into contact with the coating surface.

The coating surface forming member (18) is brought into contact with the coating surface by rotating the geared motor and the timing belt to sequentially change the distance from the member rotation axis. Then, the maximum advance distance (distance between the rotation axis of the base material and the rotation axis of the member) of the coating surface forming member (18) is
It can be adjusted by either or both of the shape of the member and the fixed position of the bearing that supports the rotation of the member. The contact of the coated surface forming member (18) with the coated surface may be normally performed during the rotation of the substrate (1) for 3 to 30 times. Then, the forming member (18) is further rotated, and the member (18) is separated from the coating surface without moving the forming member (18). At this time, the rotation direction of the forming member (18) is
It is desirable to be the same as the rotation direction of the base material (1). or,
The forming member (18) is fixed, and further the forming member (1
Since the cross-sectional shape of 8) is kept constant with high precision, the surface of the forming member (18) is kept parallel to the coating surface, and the member itself moves and separates at the same time at the same time. Therefore, it is difficult for the forming member (1) to remain on the coated surface after peeling. Furthermore, as shown in (1) and (2) of FIG. 3, the portion A of the coating surface forming member does not come into contact with the coating liquid at all during one rotation. Since the forming member is separated from the coating surface by using this A portion,
The effect of separating the members is further reduced.

By contact between the coated surface forming member (18) and the coated surface of the substrate (1), the coated surface forming member (18) (specifically, a linear portion parallel to the axis of the substrate (1)) ) And the axis of the base material (1), a coating film having a constant outer diameter can be formed over the coating surface of the base material (1).
By applying additional processing by coating, it is possible to obtain a base body with high outer diameter accuracy. Straightness of the base material (1) itself when the coated surface forming member (18) is not parallel to the axis of the base material (1) but is in contact with the coating surface in parallel with the body surface of the base material (1). And roundness appear as they are on the surface of the coating film, and the outer diameter accuracy of the base material (1) is not corrected. It should be noted that in the case of a base material whose straightness and roundness are too poor, it is difficult to obtain a substrate with high outer diameter accuracy even by the present invention.
If the B0621-1974) is in the range of about 500 μm or less, preferably about 300 μm or less, it can be an object to be modified by the coating film forming method of the present invention.

As the coating liquid, any coating liquid can be used as long as it is a coating liquid to which a nozzle coating method or a curtain coating method can be applied. Then, in the case of a solvent type coating liquid, that is, in the case of a coating liquid using a solvent having a fast drying rate, coating and contact treatment to the coating surface of the coating surface forming member are performed in a space covered with a solvent vapor, and thereafter, It is preferable to carry out the drying in a space where evaporation of the solvent is promoted.
Specifically, a coating device having an appropriate detachable cover is used to perform coating and contact treatment with the cover covered, and drying is performed with the cover removed. Further, in the case of a coating liquid in which the volume change of the coating film is large due to curing after coating, for example, in the case of a coating liquid in which the volume change of the coating film is 50% or more, the coating, contact treatment and drying are a series of operations It is good to repeat it.

The means for gripping the base material is not particularly limited as long as it is a means for gripping the base material so that the axis of the base material comes out, and the base material is inserted into the flange hole to open the base material by the outward opening action. A gripping means (inner expansion type collect chuck) or the like can be adopted. Further, in the case of a cylindrical base material, a gripping means or the like which holds the base material 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.

Example 1 The coating apparatus shown in FIG. 1 was used. That is, as the coating liquid supply pipe of the coating liquid supply mechanism, a supply pipe having a branched structure having four tip nozzles (nozzle hole diameter 0.4 mm, nozzle pitch 1.2 mm) is used. For this, a Teflon-coated stainless steel round bar having a diameter of 20 mm was processed as shown in FIG. 3 (1), and half of the cross section was used as a polished circular arc. This was subjected to 10 μm Teflon coating. An ultraviolet irradiation device equipped with a 3 Kw high-pressure mercury lamp was used as the ultraviolet irradiation device. The ultraviolet irradiation device was arranged at a position where the distance from the base material to the front surface of the mercury lamp was 25 cm.

A glass tube as a base material (outer diameter 29.7 mm,
Flange was attached to both ends of the inner diameter of 27.3 mm and the length of 250 mm). The flange was mounted so that the axis of the glass tube determined by each central hole of the flange would match. A glass tube was arranged between the rotating shafts of the base material rotating mechanism, each rotating shaft was fitted in each central hole of the flanges at both ends, and the gear driving motor was driven to rotate the glass tube at 200 rpm. The distance between the rotation axis of the base material and the coating surface forming member is 1 on average.
It was 5.00 mm. The direction of rotation of the substrate and the direction of rotation of the coating surface forming member are as shown by the arrows in FIG.
At the contact portion between the base material and the coating surface forming member, the base material was rotated in the same direction so that the moving direction of the base material was from top to bottom and the forming member was from bottom to top.

The coating solution is spirally supplied from the nozzle portion of the coating solution supply tube to the surface of the rotating glass tube to apply it.
A continuous film was formed. The coating liquid consists of urethane acrylate (A), 2-acryloyloxyethyl phthalic acid (B), dicyclopentenyloxyethyl acrylate (C), 1-hydroxy-cyclohexyl-phenyl ketone (D), and benzophenone (E). , A: B:
An ultraviolet curable resin composition having C: D: E = 30: 10: 40: 0.8: 0.8 (weight ratio) and a viscosity at room temperature of 500 (mpas) was used. The above-mentioned resin film applied in a spiral shape became a continuous film by leveling.

The spiral supply of the coating liquid was performed so that the pitch per rotation of the glass tube was 1.5 mm and the average thickness of the coating film was 170 μm. Immediately after coating, the coated surface forming member is rotated at 20 rpm with a geared motor.
The coating liquid surface was made to rotate by, and the bar was separated from the surface. Then, the coating surface was cured by irradiating the coating surface with ultraviolet rays having an irradiation energy amount of 1500 mJ / cm ² using an ultraviolet ray irradiation device from diagonally above. The straightness of the glass tube before and after the coating film formation was measured by thinly applying the pigment dispersion liquid on the glass surface and the coating surface to eliminate the influence of the back surface and layer surface reflection, and the result is shown in FIG. 6 and FIG. 6 (results after coating film formation). In the figure, the horizontal axis represents the distance (mm) in the axial direction of the glass tube, and the vertical axis represents the degree of unevenness (μm) from the reference value. Note that these straightnesses were measured using a laser length measuring machine (“KL131A”) manufactured by Anritsu Corporation.

Comparative Example 1 The coated surface forming member used in Example 1 was used. In this case, after the above member was contacted with the coated surface at the arc portion from the beginning,
Example 1 except that the entire member including the support system was retracted without rotating the member and the member was pulled away from the substrate surface.
A coating film was formed under the same conditions as above. When the shape of the work was measured with a laser length measuring machine after the effect of ultraviolet rays, a clear upward peeling of the bar was observed in the center of the work.

[0034]

According to the present invention described above, there is provided an improved coating film forming method which can be used to improve the outer diameter accuracy regardless of the processing accuracy of a cylindrical or cylindrical base material. To be done. And by using the coating film forming method of the present invention, the required outer diameter accuracy (straightness, roundness, cylinder Degree, surface roughness, etc.) of the electrophotographic photoreceptor.

[Brief description of drawings]

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

FIG. 2 is an explanatory view showing another example of a coating apparatus for carrying out the coating film forming method of the present invention.

FIG. 3 is an explanatory view showing an example of the shape of a coating film forming member of the present invention.

FIG. 4 is an explanatory view showing an example of a method of rotating the coating film forming member of the present invention.

5 is a graph showing the measurement results of straightness (results before coating film formation) of the glass tube used in Example 1. FIG.

FIG. 6 is a graph showing the measurement results of straightness of the glass tube obtained in Example 1 (results after coating film formation).

[Description of sign]

 1: Base material 3: Rotating shaft 10: Screw screw 14: Moving body 15: Coating liquid supply pipe 17: Metering pump 18: Coating surface forming member 20: Bearing 21: Gear 22: Timing belt 23: Geared motor 24: Ultraviolet irradiation Device 26: Nozzle head 27: Nozzle row

Claims (3)

[Claims] 1. A cylindrical or columnar base material is horizontally supported and rotated, and an excessive amount of coating liquid is supplied to the surface of the base material to form a continuous coating surface. A method for forming a coating surface by making the coating surface forming member parallel to the rotation axis so as to keep a constant distance from the rotation axis of the base material and close to the coating surface before losing fluidity. A method for forming a coating film, characterized in that the forming member is separated from the coating surface by a method satisfying at least one of the following two conditions. (B) It has a moving component in the tangential direction of the coating surface at the final contact position with the coating surface. (B) The surface of the forming member on which the coating liquid is not adhered is drawn out. 2. The coating surface forming member is a coating surface forming member having a constant cross section and a rotation center having a radius that decreases uniformly or gradually from a position where it comes into contact with the coating surface. The method for forming a coating film according to claim 1, which is characterized in that. 3. The method according to claim 1, wherein the forming member is parallel to the rotation axis of the substrate and is separated from the coating surface.
The coating film forming method described.