JP2004160320A - Coating device and coating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating device by which neither decolored stripes nor black stripes appear and to provide a coating method using the coating device. <P>SOLUTION: The coating device for applying a coating liquid onto at least one surface of a strip transported in a fixed direction, is provided with a coating bar for applying the coating liquid onto the strip, a weir plate which is disposed at the upstream side of the coating bar in the transportation direction of the strip so as to face the coating bar and a pressure-reducing chamber which is located at the back part of the weir plate being the upstream side from the weir plate in the transportation direction of the strip and in which the coating liquid overflowed the weir plate flows. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating apparatus and a coating method, and in particular, in a coating apparatus having a coating bar, even when a belt-like body is transported at a high speed, white lines, black lines, etc., without increasing the amount of coating liquid supplied. The present invention relates to a coating apparatus capable of preventing the occurrence of coating defects and a coating method using the coating apparatus.
[0002]
[Prior art]
The lithographic printing plate is usually a grained support web obtained by concentrating at least one surface of an aluminum web which is a strip-like thin plate of pure aluminum or an aluminum alloy, and forming an anodized film on the surface if necessary. A plate-making layer forming solution such as a photosensitive layer-forming solution or a heat-sensitive layer-forming solution is applied to the surface and dried to form a photosensitive or heat-sensitive plate-making surface.
[0003]
A coating solution such as the plate making layer forming solution is generally applied by a bar coater.
[0004]
The bar coater is usually disposed along a direction perpendicular to the transport direction of the support web, and rotates the plate-making layer forming liquid on the support web while rotating in the same direction as or opposite to the transport direction. A bar to be applied, a weir plate disposed relative to the bar on the upstream side (hereinafter simply referred to as “upstream side”) with respect to the travel direction of the support web, relative to the bar; A liquid supply slit for supplying a platemaking layer forming liquid is provided between the bar and the liquid plate.
[0005]
In the bar coater, the support web is transported so as to pass above the barrier plate and the bar, and the plate-making layer forming liquid is discharged from the liquid supply slit toward the support web. It is common to apply the platemaking layer forming liquid to the support web by forming a platemaking layer forming liquid pool in a space formed by the support web, the bar and the barrier plate.
[0006]
In the bar coater, a part of the platemaking layer forming liquid discharged from the liquid supply slit overflows the upstream side of the barrier plate.
[0007]
[Patent Document 1]
Japanese Patent Publication No. 58-004589 (1st page, Fig. 1)
[0008]
[Problems to be solved by the invention]
In the bar coater, if the plate-making layer forming liquid does not overflow uniformly over the entire width of the barrier plate, coating defects such as color loss stripes and black stripes occur.
[0009]
By increasing the amount of the platemaking layer forming liquid supplied between the barrier plate and the coating bar, the platemaking layer forming solution can be made to overflow uniformly over the entire width of the barrier plate.
[0010]
However, when the supply amount of the platemaking layer forming liquid increases, a filter is provided in parallel with the liquid supply system for supplying the platemaking layer forming liquid to the bar coater so that the pressure loss in the filter does not increase, and the supply It is necessary to increase the pipe diameter of the pipe forming the liquid system. Further, the loss of the plate making layer forming liquid increases.
[0011]
Therefore, there is a problem that the method of increasing the amount of the plate-making layer forming liquid supplied causes a significant cost increase.
[0012]
The present invention has been made to solve the above problem, and allows the coating liquid to overflow uniformly over the entire width of the dam plate without increasing the supply amount of the coating liquid such as a plate making layer forming liquid. And a coating apparatus that does not cause coating defects such as color loss stripes and black stripes even when the belt web or the like is transported at high speed, and a coating method using the coating apparatus. With the goal.
[0013]
[Means for Solving the Problems]
The invention described in claim 1 is a coating apparatus that applies a coating liquid to at least one surface of a belt-like body that is conveyed in a fixed direction, the coating bar that coats the coating liquid on the belt-like body, and the belt-like body A weir plate disposed upstream of the coating bar with respect to the transport direction of the body and facing the coating bar; and a weir upstream of the barrier plate with respect to the transport direction of the strip The present invention relates to a coating apparatus comprising a decompression chamber located on the back of the plate and into which the coating liquid overflowing the weir plate flows.
[0014]
In the coating apparatus, when the pressure in the decompression chamber is reduced, the coating solution overflowing the barrier plate is forced to flow down toward the decompression chamber. Therefore, even when the amount of the coating liquid supplied between the barrier plate and the coating bar is small, the coating liquid can be overflowed over the entire width of the barrier plate. The occurrence of coating defects such as streaks can be effectively prevented.
[0015]
The bar may be a smooth bar having a smooth surface, a grooved bar in which a circumferential groove is formed, or a wire bar in which a metal wire is wound around the surface at a predetermined pitch or densely wound. There may be.
[0016]
Examples of the belt-like body include a continuous belt-like base material having flexibility. Specifically, in addition to the support web described in the section of [PRIOR ART], a photosensitive material and a magnetic recording material are also included. The base material used for is mentioned. Examples of the base material include the support web, photographic film base material, photographic paper baryta paper, recording tape base material, video tape base material, floppy (R) disk base material, and the like. Other examples include thin metal plates used for painted metal plates such as colored iron plates.
[0017]
Examples of the coating solution include a plate making layer forming solution described in the section of “Prior Art”, a photosensitive agent colloid solution used for forming a photosensitive layer for silver salt photography, and a magnetic layer in the magnetic recording material. And the various coating materials used for the undercoat layer, intermediate coat layer, and overcoat layer of the coated metal sheet.
[0018]
The invention according to claim 2 relates to a coating apparatus in which a pressure reducing port in the pressure reducing chamber is provided at a position higher than a liquid surface height of the coating liquid in the pressure reducing chamber.
[0019]
In the coating apparatus of the present invention, the coating liquid overflowing the weir-like member flows into the decompression chamber, but in the coating apparatus, the decompression port is at a position higher than the liquid level of the coating liquid, The mouth is not blocked by the coating solution. Therefore, since the decompressed state in the decompression chamber can be maintained for a long time, the effect of preventing the occurrence of coating defects such as color loss stripes and black stripes can be stably maintained.
[0020]
The invention according to claim 3 relates to a coating apparatus in which a distance between a coating liquid inflow opening through which the coating liquid flows in the decompression chamber and a transport path transport surface of the belt-shaped body is 0.5 to 1 mm.
[0021]
In the coating apparatus, since the distance between the coating liquid inflow opening and the transport path transport surface is within the range, the belt-shaped body travels stably without contacting the wall of the decompression chamber or the weir plate. To do. Further, it is easy to keep the decompression chamber in a predetermined decompression state.
[0022]
The invention described in claim 4 relates to a coating apparatus in which the coating bar rotates at a peripheral speed different from the traveling speed of the belt-like body.
[0023]
In the coating apparatus, since a more stable coating liquid reservoir is formed in the space between the belt-shaped body, the coating bar, and the dam plate, a coating film with particularly high uniformity is formed.
[0024]
The invention according to claim 5 relates to a coating apparatus in which the coating bar rotates at the same peripheral speed as the traveling speed of the strip.
[0025]
In the coating apparatus, since the coating bar can be driven by the belt-like body, a coating bar driving device that rotates the coating bar can be omitted.
[0026]
The invention described in claim 6 relates to a rotating coating device in which the coating bar rotates in a direction opposite to the traveling speed of the belt-like body.
[0027]
In the coating apparatus, even when the transport speed of the strip is low, the difference between the peripheral speed of the coating bar and the traveling speed of the strip can be made large.
[0028]
Therefore, since a stable coating liquid reservoir is formed as in the coating apparatus according to claim 5, a coating film with particularly high uniformity is formed.
[0029]
The invention according to claim 7 relates to a coating apparatus in which the coating bar rotates in the same direction as the traveling speed of the belt-shaped body.
[0030]
In the coating apparatus, even when the transport speed of the strip is high, the difference between the peripheral speed of the coating bar and the traveling speed of the strip is not excessive, so that a stable coating liquid pool is formed, In particular, a highly uniform coating film is formed.
[0031]
The invention according to claim 8 is a coating method for applying a coating liquid to at least one surface of a belt-like body conveyed in a fixed direction, the coating bar for coating the coating liquid on the belt-like body, and the belt-like body A weir plate disposed on the upstream side of the coating bar with respect to the transport direction of the body and facing the coating bar, and a weir upstream of the weir plate along the transport direction of the strip It is related with the coating method characterized by performing the said application | coating using the coating device provided with the decompression chamber which is located in the board back part and the coating liquid which overflowed the said dam plate flows in.
[0032]
For the same reason as described in claim 1, even when the amount of coating liquid supplied between the barrier plate and the coating bar is small, the coating liquid is spread over the entire width of the barrier plate. Since overflow can be achieved, the coating method can effectively prevent the occurrence of coating defects such as color loss stripes and black stripes.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
1. Embodiment 1
FIG. 1 shows an example of a bar coater that is an example of a coating apparatus according to the present invention and that applies a plate-making layer forming liquid to a support web. In addition, the support body web W is an example of the strip | belt-shaped body in this invention.
[0034]
The bar coater 100 according to the first embodiment includes a coating bar 2 that applies the plate-making layer forming liquid to the grained surface Sg of the support web W conveyed in the direction of arrow a, and a plate-like bar that supports the coating bar from below. A support member 4, a primary side dam plate 6 erected so as to face the bar support member 4 and the coating bar 2 on the upstream side of the bar support member 4, and a bar on the downstream side of the bar support member 4 A secondary side dam plate 8 is provided so as to be opposed to the support member 4 and the application bar 2. The primary side weir plate 6 corresponds to the weir plate in the coating apparatus of the present invention.
[0035]
The application bar 2 may be a smooth bar, a grooved bar, or a wire bar.
[0036]
A V-shaped bar holding groove 4 </ b> A for holding the application bar 2 is formed on the top surface of the bar support member 4. However, the shape of the bar holding groove 4A is not limited to the V shape, and may be an arc shape or a curved surface shape.
[0037]
All of the coating bar 2, the bar support member 4, the primary side dam plate 6, and the secondary side dam plate 8 are placed on the base 16.
[0038]
The upstream side surface of the primary side dam plate 6 and the downstream side surface of the secondary side dam plate 8 are both inclined surfaces in which the upper half portion is inclined toward the application bar 2. The plate-making layer forming solution supplied in this way is formed to flow down.
[0039]
A decompression chamber forming weir plate 12 is erected on the upstream side of the primary side weir plate 6 so as to face the primary side weir plate 6, and the pressure is reduced by the primary side weir plate 6 and the decompression chamber forming weir plate 12. A chamber 10 is formed.
[0040]
The portion of the decompression chamber forming wall 12 that faces the primary side weir plate 6 is “ku” toward the downstream side in accordance with the shape of the upstream side surface of the primary side weir plate 6, that is, the back side surface. Bent into a letter shape.
[0041]
Formed on the upper surface of the decompression chamber 10 is a coating liquid inflow opening through which the platemaking layer forming liquid that has overflowed the primary side weir plate 6 flows. The distance from the coating liquid inflow opening to the transport surface T that is the transport path of the support web W, that is, the distance from the upper end of the decompression chamber forming wall 12 to the transport surface T is 0.5 to 1 mm.
[0042]
In a portion between the bent portion and the vertical portion of the decompression chamber forming weir 12, a decompression pipe line 14 that decompresses the inside of the decompression chamber 10 is provided upright.
[0043]
Although the pressure in the decompression chamber 10 should just be lower than atmospheric pressure, it is preferable that it is higher than the vapor pressure in the application temperature of the solvent in a platemaking layer forming liquid.
[0044]
The base 16 has a shallow box shape with an open upper surface, and a downstream return coating liquid reservoir 18 is formed between the downstream wall of the base 16 and the secondary dam plate 8.
[0045]
Between the primary side weir plate 6 and the bar support member 4, there is provided a primary side liquid supply slit 20 for supplying a plate-making layer forming liquid to the upstream side of the coating bar 2. Similarly, between the bar support member 4 and the secondary side dam plate 8, a secondary side liquid supply slit 22 that supplies a plate-making layer forming liquid is provided on the downstream side of the coating bar 2.
[0046]
A primary side liquid supply pocket 24 is formed at the lower end of the primary side liquid supply slit 20, and a secondary side liquid supply pocket 26 is formed at the lower end of the secondary side liquid supply slit 22. The primary side liquid supply pocket 24 corresponds to the liquid supply pocket in the coating apparatus according to the present invention. A concave surface is formed at the lower end of the surface of the primary side weir plate 6 facing the bar support member 4, and the concave surface forms part of the inner wall surface of the primary side liquid supply pocket 24. . Similarly, a concave surface is also formed at the lower end of the surface of the secondary side weir plate 8 facing the bar support member 4, and the concave surface forms part of the inner wall surface of the secondary liquid supply pocket 26. doing.
[0047]
Connected to the primary side liquid supply pocket 24 and the secondary side liquid supply pocket 26 is a liquid supply line 30 for supplying the platemaking layer forming liquid from a reservoir tank (not shown) in which the platemaking layer forming liquid is stored. Has been. On the other hand, a return line 32 is connected to the decompression chamber 10 and the downstream return coating solution reservoir 18 for returning the platemaking layer forming solution to the reservoir tank.
[0048]
A pressure roller 40 is disposed on the upstream side of the bar coater 100, and the support web W is pressed toward the coating roller 2 by the pressure roller 40 on the upper surface that is the surface opposite to the graining surface Sg.
[0049]
On the upstream side and the downstream side of the bar coater 100, web holding rollers 50 and 52 are provided so as to contact the upper surface of the support web W and hold the support web W so as to be conveyed along the conveyance surface T. Has been.
[0050]
Hereinafter, the operation of the bar coater 100 will be described.
[0051]
The plate-making layer forming liquid supplied from a reservoir tank (not shown) through the liquid supply line 30 passes through the primary liquid supply pocket 24 and the primary liquid supply slit 20 and is upstream of the coating bar 2. To the downstream side of the coating bar 2 through the secondary side liquid supply pocket 26 and the secondary side liquid supply slit 22.
[0052]
The coating liquid supplied to the upstream side of the coating bar 2 is discharged toward the support web W from between the coating bar 2 and the primary side weir plate 6, and the majority is applied to the support web W, and the rest Overflows the primary side weir plate 6 and flows into the decompression chamber 10.
[0053]
Here, since the inside of the decompression chamber 10 is decompressed, the plate-making layer forming liquid that has not been applied to the support web W is forcibly sucked into the decompression chamber 10. Accordingly, the plate-making layer forming liquid uniformly overflows over the entire width of the primary side weir plate 6.
[0054]
On the other hand, the downstream surface of the coating bar 2 is always kept moist by the plate-making layer forming liquid supplied from the secondary-side liquid supply slit 22, so that the plate-making layer forming liquid adhering to the surface is dried and fixed. The occurrence of dry sticking is prevented.
[0055]
As described above, in the bar coater 100, the plate-making layer forming liquid uniformly overflows over the entire width of the primary side weir plate 6 even when the conveyance speed of the support web W is high.
[0056]
Therefore, the accompanying air flow that adheres to the surface of the support web W and is brought into the bar coater 100 is pushed back upstream by the plate-forming layer forming liquid flow that overflows the primary side weir plate 6 toward the decompression chamber 10. Without particularly increasing the amount of the plate-making layer forming liquid supplied from the liquid supply pipe line 30, the color omission streaks due to the accompanying air flow and the amount of overflow of the plate-making layer forming solution are larger than the surroundings. Generation of black streaks can be prevented.
[0057]
Further, a primary side liquid supply pocket 24 and a secondary side liquid supply pocket 26 are provided between the primary side liquid supply slit 20 and the secondary side liquid supply slit 22 and the liquid supply pipe line 30, respectively. Therefore, even if a fluctuation occurs in the amount of liquid supplied from the liquid supply conduit 30, the fluctuation is absorbed by the primary side liquid supply pocket 24 and the secondary side liquid supply pocket 26. Therefore, since the flow rate of the plate-making layer forming liquid supplied from the primary side liquid supply slit 20 and the secondary side liquid supply slit 22 to the coating bar 2 is stable, the occurrence of coating defects due to the fluctuation of the flow rate is also achieved. Is prevented.
[0058]
【Example】
One surface of an aluminum web having a width of 1000 mm was subjected to brush grain treatment, alkali etching treatment, and electrolytic surface roughening in order to be grained, and then anodized to prepare a support web.
[0059]
Using the coating apparatus shown in FIG. 1, a photosensitive layer forming solution was applied as a plate making layer forming solution to the grained surface Sg of this support web and dried to form a photosensitive layer. The coating conditions for the photosensitive layer coating solution were set as follows.
[0060]
a. Bar coater feeding width ... 1600mm
b. Thickness of the support web W ... 0.3 mm
c. Conveying speed of support web W: 120 m / min d. Bar coating amount: 20cc / m ²
e. Outer diameter of application bar 2 ... 10mm
f. Rotation speed of coating bar 2 -30rpm (reverse rotation)
g. Viscosity of photosensitive layer forming solution: 20 cP
h. Amount of liquid fed as shown in FIG. Application amount of photosensitive layer forming solution to support web W 2 liters / minute j. Decompression degree in the decompression chamber 10 as shown in FIG.
FIG. 2 shows the relationship between the degree of decompression in the decompression chamber 10 and the liquid feeding amount. Here, the degree of decompression is the difference between the atmospheric pressure and the pressure inside the decompression chamber 10, and the greater the degree of decompression, the smaller the pressure inside the decompression chamber 10.
[0062]
As shown in FIG. 2, when the degree of decompression in the decompression chamber 10 is 0, the primary side liquid supply slit 20 is used to apply the photosensitive layer forming solution to the support web W at an application amount of 2 liters / minute. About 4.2 liters / minute was required for the amount of liquid fed to It has been found that as the degree of decompression increases and the pressure in the decompression chamber 10 decreases, the amount of liquid fed to the primary side liquid supply slit 20 necessary to achieve the coating amount decreases. And when the pressure reduction degree was 400 Pa, the said liquid feeding amount reduced to 3 liters / min.
[0063]
From this, it can be seen that in the coating apparatus of the present invention, the amount of liquid supply required to achieve the same coating amount is smaller.
[0064]
【The invention's effect】
As described above, according to the present invention, it is possible to uniformly overflow the coating liquid over the entire width of the barrier plate without increasing the amount of liquid supply, and even when the transport speed of the belt is high. Provided are a coating apparatus that does not cause coating defects such as color loss stripes and black stripes, and a coating method using the coating apparatus.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of a bar coater as an example of a coating apparatus of the present invention.
FIG. 2 is a graph showing the relationship between the degree of decompression of the decompression chamber 10 and the amount of liquid fed to the primary side liquid supply slit.
[Explanation of symbols]
2 Application bar 6 Primary side weir 8 Secondary side weir 10 Decompression chamber

Claims (8)

A coating apparatus that coats a coating liquid on at least one surface of a belt-like body conveyed in a certain direction,
An application bar for applying the application liquid to the strip;
A weir plate disposed on the upstream side of the coating bar with respect to the transport direction of the belt-like body so as to face the coating bar;
An applicator comprising: a decompression chamber which is located on a back of the weir plate on the upstream side of the weir plate with respect to the transport direction of the belt-like body and into which the coating liquid overflowing the weir plate flows. The coating apparatus according to claim 1, wherein the decompression port in the decompression chamber is provided at a position higher than a liquid surface height of the coating liquid in the decompression chamber. The coating apparatus according to claim 1 or 2, wherein a distance between a coating liquid inflow opening through which the coating liquid flows in the decompression chamber and a transport path transport surface of the belt-shaped body is 0.5 to 1 mm. The coating apparatus according to claim 1, wherein the coating bar rotates at a peripheral speed different from a traveling speed of the belt-shaped body. The coating apparatus according to claim 1, wherein the coating bar rotates at the same peripheral speed as the traveling speed of the strip. The coating apparatus according to claim 1, wherein the coating bar rotates in a direction opposite to a traveling speed of the belt-shaped body. The coating apparatus according to claim 1, wherein the coating bar rotates in the same direction as the traveling speed of the belt-shaped body. A coating method in which a coating liquid is applied to at least one surface of a belt-like body conveyed in a certain direction,
An application bar for applying the coating liquid to the belt, a weir plate disposed on the upstream side of the application bar along the conveying direction of the belt, so as to face the application bar, and the belt The coating is performed using a coating apparatus including a decompression chamber that is located on the back of the barrier plate upstream of the barrier plate with respect to the body conveyance direction and into which the coating liquid overflowing the barrier plate flows. Application method.

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