JPH11276965A - Coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating device of high performance in which the thickness of a coating film can be made as thin as possible and the coating film of uniform thickness can be continuously formed for a long time, stably, with high accuracy, and with high quality. SOLUTION: A coating device is provided with a backup roll 14 and a coating head 18 having a nozzle end face 16 opposite to a backup roll outer peripheral surface 10. The nozzle end face 16 of the coating head 18 is divided into a first end face part 16a on the upstream side in the substrate web traveling direction and a second end face part 16b on the downstream side. A guide roll arranged on the downstream side of the coating head 18 leaves a traveling substrate web 20 at a leaving point P on the backup roll outer peripheral surface 10 on the upstream side from a downstream end 34 of the second end face part 16b and on the downstream side from the upstream end and defines a wedge shaped pressure void 32 between, the substrate web 20 and the second end face part 16b. A coating material that has entered the pressure void 32 is given fluid pressure equal to or more than the initial coating pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus for forming a coating film on the surface of a substrate web, and more particularly, to a backup roll for supporting a substrate web running at a predetermined speed, and a backup roll separated from the backup roll. The present invention also relates to a coating apparatus provided with a coating head for continuously extruding a coating material on a surface of a traveling base material web and applying the coating material to a predetermined thickness.

[0002]

2. Description of the Related Art As a method of applying a coating material to a surface of a base material web having a continuous length, such as a resin film, a resin sheet, and paper, a nozzle portion of an extrusion die is used as a coating head and the surface of a running base material web is used. A so-called die coating method is known in which a high-viscosity fluid paint is continuously extruded from a coating head to form a coating film having a predetermined thickness. The die coating method differs from the well-known roll coating method in that the thickness of the coating film can be directly controlled by adjusting the amount of extruded paint supplied. This is advantageous when it is desired to stably form a layer coating film with high precision. Conventionally, a coating apparatus that performs this type of die coating method holds a running base material web by a backup roll and applies the coating material in a state where a nozzle end surface of a coating head is separated from a surface of the base material web by a predetermined distance. One that appropriately applies the coating material while sliding along the nozzle end surface of the application head without supporting the traveling base material web on the back surface is employed.

In a conventional coating apparatus provided with a backup roll, the coating head passes through a minute gap fixedly defined between the nozzle end face of the coating head and the surface of a substrate web carried on the backup roll. The extruded paint is pressurized and weighed while flowing, and as a result, a coating film having a predetermined thickness is continuously formed on the surface of the running substrate web. Generally, the nozzle end surface of the coating head is a flat surface,
The downstream end of the nozzle end face in the substrate web running direction is
In order to smooth the surface of the coating film, it is formed with a very straight edge having a high straightness. In such a backup roll type coating apparatus, the thickness of the coating film formed on the substrate web can be controlled by adjusting the amount of the paint to be extruded and supplied and simultaneously adjusting the interval between the coating head and the backup roll. .

On the other hand, in a conventional coating apparatus which does not support the back surface of the base material web, the nozzle end face of the coating head formed in a curved surface is pressed against the base material web, and the pressure of the paint extruded from the coating head and the base material web are determined. In a state where the stress that is going to contact the nozzle end face is balanced, the paint is pressurized and weighed by the minute gap defined between the base web and the nozzle end face, and the coating is applied to the surface of the running base web. A coating film having a predetermined thickness is continuously formed. Therefore, the thickness of the coating film formed on the substrate web can be directly controlled by adjusting the amount of the paint to be extruded and supplied. At this time, the stress generated in the substrate web (for example, the tension applied to the substrate web) ) Greatly affects the thickness of the coating film.

[0005]

In a conventional coating apparatus provided with a backup roll, the gap between the surface of the substrate web and the nozzle end face of the coating head is fixedly maintained by the backup roll during the coating operation. Therefore, the thickness of the coating film formed on the substrate web is affected by factors unrelated to the structure of the coating head and the backup roll, such as the viscosity of the paint, the strain of the substrate web, and the tension applied to the substrate web. There is an advantage that is not substantially received. Further, it is possible to easily cope with base materials having different thicknesses by adjusting the distance between the coating head and the backup roll.

On the other hand, the machining accuracy and assembly accuracy of the coating head and the backup roll, such as run-out during rotation of the backup roll, depend on the thickness and quality of the coating film (thickness uniformity, surface smoothness, presence or absence of defects, etc.). Will be directly affected. In particular, in order to reduce the thickness of the coating film, it is necessary to reduce the distance between the coating head and the backup roll in response to the reduction in the amount of the extrusion supply of the coating material. Due to the factors on the side, there is a limit in reducing the interval, and as a result, there is a problem that it is difficult to reduce the thickness of the coating film.

Further, in order to continuously form a coating film having a uniform thickness stably for a long time, the fluid pressure of the coating material flowing between the coating head and the substrate web is applied to the downstream end of the nozzle end surface of the coating head. It has been found that the relative position between the nozzle end face of the coating head and the outer peripheral face of the backup roll should be set so that it does not substantially fluctuate, and preferably rises, as it approaches. Therefore, in the above-described conventional coating apparatus, the relative position is set so that the distance between the coating head and the backup roll is minimized at the downstream end of the nozzle end surface. However, in this case, if the backup roll is brought close to the downstream end of the nozzle end surface, which is an extremely sharp edge, in an attempt to reduce the thickness of the coating film, contact with foreign matter mixed in the coating material during the coating operation or the above-described machining There is a danger that the edges will be easily broken due to contact with the substrate web (i.e. indirect collision with the backup roll), which may result from accuracy and assembly accuracy problems. From such a viewpoint, it is difficult to make the thickness of the coating film as thin as possible with the conventional backup roll coating device.

[0008] Further, due to the problems of machining accuracy and assembly accuracy described above, there has been a limit to the running speed of a substrate web capable of continuously forming a coating film having a uniform thickness stably for a long time. In addition, during high-speed running, the amount of ambient air (hereinafter referred to as entrained air) entrained between the substrate web and the paint increases, and defects in the paint film such as pinholes and vertical stripes easily occur. There was a problem that the quality of the film deteriorated.
As described above, the conventional backup roll type coating apparatus is generally not suitable for a high-speed coating operation and a thin film coating operation.

On the other hand, in the conventional non-back support type coating apparatus, the above-mentioned problems caused by the machining accuracy and the assembly accuracy of the backup roll are eliminated, and the thickness of the coating film can be reduced as much as possible. However, since the gap size between the surface of the base web and the end face of the nozzle of the coating head can fluctuate during the coating operation, the viscosity of the paint, the strain and thickness of the base web, and the stress (for example, It has been found that various factors such as tension applied to the web) and the curved shape of the nozzle end surface of the coating head greatly affect the quality of the coating film and the stability of the coating operation. In particular, it is difficult to machine the nozzle end face of the coating head into a desired curved surface shape with high precision, and this has increased the manufacturing cost of the coating apparatus. In addition, the ability of the base material web to follow the nozzle end face of the coating head changes for base material webs with different thicknesses and materials, so that coating heads with different curved nozzle end faces must be prepared separately. There was an inconvenience. As described above, the conventional coating apparatus that does not support the substrate web on the back side generally has various constraints to be satisfied in order to ensure a desired level of coating film quality and the stability of the coating operation. The range was limited.

Accordingly, an object of the present invention is to solve the above-mentioned problems in a conventional backup roll type coating apparatus having relatively few restrictions in a coating apparatus for performing a die coating method, and to reduce the thickness of the coating film. To provide a high-performance coating apparatus that can be thinned as much as possible, can form a coating film of uniform thickness stably for a long time with high precision and high quality, and can be applied in a wide range. It is in. Furthermore, the present invention also effectively reduces the amount of entrained air entrained between the base material web and the paint, even for a base material web running at a high speed, to form a coating film having a uniform thickness stably for a long time. It is an object of the present invention to provide a high-performance coating apparatus capable of continuously forming with high accuracy and high quality.

[0011]

In order to achieve the above object, according to the present invention, a substrate web running at a predetermined speed is carried on an outer peripheral surface and rotated around a stationary shaft. A backup roll and a nozzle end face opposed to the outer peripheral surface of the backup roll and a paint supply path leading to the nozzle end face, which are arranged separately from the backup roll,
A coating head for continuously extruding and supplying the coating material on the nozzle end surface, while weighing the coating material between the outer peripheral surface of the backup roll and the nozzle end surface of the coating head, a predetermined thickness is applied to the surface of the traveling base material web. In a coating apparatus for continuously forming a coating film, a back-up roll of a nozzle end face of a coating head, which faces a pressurized area upstream of a downstream end in a substrate web traveling direction and downstream of a paint supply path, is provided. At a position on the outer peripheral surface, the moving substrate web is detached from the outer peripheral surface, and a fluid pressure higher than the initial application pressure of the paint entering the pressurized region of the nozzle end face is applied to the paint at the downstream end of the nozzle end face. And a coating device provided with a detaching means.

According to a second aspect of the present invention, in the coating apparatus according to the first aspect, the outer peripheral surface of the backup roll and the nozzle end surface of the coating head are closest to each other within a pressure area of the nozzle end surface. To provide a coating device that defines a minimum gap.

According to a third aspect of the present invention, there is provided the coating apparatus according to the first or second aspect, wherein the nozzle end face of the coating head is provided on the upstream side of the paint supply path in the substrate web running direction. Provided is a coating apparatus in which a decompression means for decompressing a space between the pressure roller and an outer peripheral surface of a backup roll is disposed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments with reference to the accompanying drawings. In the drawings, the same or similar components are denoted by common reference numerals. As schematically shown in FIG. 1, a coating apparatus according to an embodiment of the present invention has a cylindrical outer peripheral surface 10 and a stationary shaft 12.
And a nozzle end surface 16 facing the outer peripheral surface 10 of the backup roll 14.
And a coating head 18 that is disposed separately from the backup roll 14. Backup roll 14
And the coating head 18 are relatively movable so that the distance between the former outer peripheral surface 10 and the latter nozzle end surface 16 can be adjusted,
It is installed on a machine (not shown). Therefore, the stationary shaft 12
The term "stationary" means that the stationary shaft 12 is kept stationary at least during the rotation of the backup roll 14.

A base material web 20 having a continuous length, such as a resin film, a resin sheet, or paper, is fed from a storage unit (not shown) to the backup roll 14 and surrounds the outer peripheral surface 10 of a predetermined section of the backup roll 14. The vehicle continuously travels at a predetermined speed in a direction indicated by an arrow A by a feed mechanism (not shown). At the same time, the backup roll 14 closely supports the substrate web 20 on the outer peripheral surface 10 and smoothly rotates around the stationary shaft 12 in the direction of arrow B in the drawing.

With respect to the traveling direction A of the substrate web 20, that is, the rotation direction B of the backup roll 14, a pressing roll 22 having a diameter sufficiently smaller than that of the backup roll 14 is disposed upstream of the coating head 18. Presser roll 22
Has a stationary shaft 24 substantially parallel to the stationary shaft 12 of the backup roll 14 and is installed on a machine base (not shown). The presser roll 22 abuts its cylindrical outer peripheral surface 26 against the outer peripheral surface 10 of the backup roll 14, and sandwiches the running base material web 20 between the two before being uniformly adhered to the outer peripheral surface 10 of the backup roll 14. While rotating, it smoothly rotates around the stationary shaft 24 in the direction of arrow C in the figure.

The coating head 18 comprises a nozzle portion of an extrusion die, and has a flat nozzle end face 16 and a nozzle end face 1.
6 and a paint supply path 28 leading to the paint supply passage 28. Coating head 18
, A high viscosity fluid paint is continuously supplied by an external pump device 30. The paint is supplied to the nozzle end face 16 through the paint supply path 28 according to the set flow rate of the pump device 30.
It is continuously extruded upward and continuously supplied to the space between the nozzle end face 16 and the outer peripheral face 10 of the backup roll 14.

As shown in FIG.
The nozzle end face 16 of the nozzle 8 has an opening 28a of the paint supply path 28.
Is divided into a first end face portion 16a located on the upstream side in the base material web traveling direction A and a second end face portion 16b located on the downstream side in the same direction. The paint extruded on the nozzle end face 16 mainly includes the second end face portion 1 as described later.
6b and a minute space 32 (hereinafter, referred to as a space) defined between the surface of the substrate web 20 supported by the backup roll 14.
While flowing through the pressurized space 32), the film is pressurized and measured, and as a result, a coating film having a predetermined thickness is continuously formed on the surface of the traveling base material web 20. The downstream end 34 of the second end face portion 16b of the nozzle end face 16 is formed with a very straight edge having a high straightness in order to smooth the coating film surface with high precision.

The coating apparatus further includes a guide roll 36 disposed downstream of the coating head 18 with respect to the substrate web running direction A. The guide roll 36 has a stationary shaft 38 that is substantially parallel to the stationary shaft 12 of the backup roll 14, and is installed on a machine base (not shown), and the cylindrical outer peripheral surface 40 is sufficiently separated from the outer peripheral surface 10 of the backup roll 14. They are placed apart. The guide roll 36 supports the running base material web 20 on which the paint has been applied on the outer peripheral surface 40 on the back surface (the surface having no coating film), and smoothly rotates around the stationary shaft 38 in the direction indicated by arrow D in FIG. I do.

The guide roll 36 constitutes the detaching means of the present invention, and moves the running substrate web 20 carried on the backup roll 14 to the outer peripheral surface of the backup roll 14 facing the nozzle end face 16 of the coating head 18. It acts so as to be detached from the outer peripheral surface 10 at a predetermined position on the outer peripheral surface 10. More specifically, as shown in FIG. 2, a detachment position P at which the base material web 20 is detached from the outer peripheral surface 10 of the backup roll 14.
Is the second end face portion 1 of the nozzle end face 16 of the coating head 18.
A region upstream of the downstream end 34 of the base material web 6b in the traveling direction A of the base material and downstream of the upstream end of the second end surface portion 16b defining the opening 28a of the paint supply passage 28 (hereinafter, referred to as a region). (Referred to as a pressure region).

Further, the guide roll 36 is provided on the base material web 20 detached from the outer peripheral surface 10 of the backup roll 14.
From the detachment position P to the second end face portion 16 of the nozzle end face 16.
b so as to asymptotically approach the second end face portion 16b in a range reaching the downstream end 34. In the illustrated embodiment, the second
At the downstream end 34 of the end portion 16b, the second end portion 1
The pressurized gap 32 between 6b and the substrate web 20 shows the minimum dimension G1. On the other hand, at the upstream end of the second end face portion 16b that defines the opening 28a of the paint supply passage 28, the pressurized gap 32 has a maximum dimension G2. As a result, the nozzle end face 16
The pressurized space 32 between the second end face portion 16b and the base web 20 has a wedge shape as shown in the figure.

In the illustrated embodiment, the backup roll 1
The outer peripheral surface 10 of the nozzle 4 and the nozzle end surface 16 of the coating head 18 are arranged closest to each other at a predetermined position in the nozzle end surface 16 within the above-described pressurized region. In the present specification, the space defined between the backup roll 14 and the application head 18 at this closest position is referred to as a minimum spacing portion 42. As shown in FIG. 2, the detached position P of the substrate web 20 on the outer peripheral surface 10 of the backup roll 14 is determined by the outer peripheral surface 1 of the backup roll 14 defining the minimum space 42.
It is arranged more upstream than the position Q on 0 with respect to the substrate web running direction A.

Due to such a positional relationship, a gap between the surface of the base material web 20 carried on the backup roll 14 and the first end surface portion 16a of the nozzle end surface 16 of the coating head 18 is formed by the first end surface portion 16a. With respect to the substrate web traveling direction A, the minimum dimension G3 is shown at the downstream end, and the maximum dimension G4 is shown at the upstream end. Therefore, in the illustrated embodiment, the gap between the surface of the base web 20 and the nozzle end face 16 of the coating head 18 is defined by a relationship of G1 <G2 <G3 <G4.

The coating operation of the coating apparatus having the above configuration will be described below with reference to FIGS. The high-viscosity fluid paint F supplied to the nozzle end face 16 via the paint supply path 28 of the application head 18 is supplied from the opening 28 a of the paint supply path 28 to the surface of the substrate web 20 carried on the backup roll 14. It is extruded into the gap between the nozzle end face 16 and enters the downstream pressurized gap 32 along with the traveling substrate web 20. At this time, at the entrance of the pressurized gap 32 defined at the upstream end of the second end face portion 16b of the nozzle end face 16, the base material web 20 is still supported by the backup roll 14, so that the paint F according to the gap size G2. (Initial application pressure) is uniformly adjusted.

Further, the paint F is applied to the running base material web 20.
Along with this, it flows downstream along the pressurized area of the second end face portion 16b of the nozzle end face 16, and fills the pressurized gap 32 while gradually increasing the fluid pressure in the wedge-shaped pressurized gap 32.
At the same time, the paint F is supplied to the opening 28 of the paint supply passage 28 from the relationship between the supply flow rate from the pump 30 and the size of the pressurized space 32.
The surface of the base material web 20 supported by the backup roll 14 and the first end face portion 1 of the nozzle end face 16 on the upstream side of
Also it flows into the gap between the 6a, to form a bead-shaped reservoir portion F _B as shown.

Then, a nozzle defining an outlet of the pressurized space 32 is formed.
At the downstream end 34 of the second end surface portion 16b of the chisel end surface 16,
The maximum fluid pressure is applied to the paint F according to the gap size G1,
Immediately after that, pressure release occurs and the surface of the substrate web 20
Coating film F of predetermined thickness_CIs formed. The pressurized space 32
At the exit, the running substrate web 20 is no longer backed up.
Although not carried by the roll 14, the gap size G1 and
Surface of the base material web 20 and the second end face of the nozzle end face 16
The angle α formed with the minute 16b is affected by the action of the guide roll 36.
It is kept substantially more constant. As a result, the pressurized space 32
As the fluid pressure of the fluid F flowing in the
And the height of the downstream end 34 of the second end face portion 16b.
Synergistic with straightness, uniform thickness with high precision smoothness
Coating F _CAre formed stably.

As described above, according to the coating apparatus according to the illustrated embodiment, the inlet of the pressurized space 32 between the surface of the base material web 20 and the second end face portion 16b of the nozzle end face 16 is fixedly set. The initial application pressure of the coating material F is uniformly adjusted according to the determined gap size G2, and the inlet flow rate of the coating material F is regulated.
The thickness of the coating film F _C which is formed on the substrate web 20 is, the viscosity of the paint F, substrate web 20 leaving, tension or the like applied to the substrate web 20, irrelevant to the structure of the coating head 18 and the backup roll 14 This has the advantage of being substantially unaffected by various factors.

On the other hand, at the exit of the pressurized space 32, since the traveling base material web 20 is not supported by the backup roll 14, the base material web 20 is moved to the sharp downstream end 34 of the second end face portion 16 b of the nozzle end face 16. , So that the thickness of the coating film F _C can be reduced as much as possible. Even if the base web 20 and the downstream end 34 of the nozzle end face 16 are brought close to each other and brought into contact with each other, the downstream end 34 due to indirect collision with the backup roll as in a conventional backup roll type coating apparatus. The risk of breakage is certainly eliminated.

By the way, the reservoir portion F _B of the paint F described above is formed between the first end face portion 16a of the nozzle surface 16 of the coating and supported substrate web 20 of the surface to the backup roll 14 head 18, The stable formation in a bead shape as shown in FIG.
It has been found that this is an important factor in stably forming a high-quality coating film on the surface. However, in particular, the base web 2
0 when the high-speed running becomes unstable shape of the amount increased by reservoir portion F _B of entrained air caught between the reservoir portion F _B of the surface and the paint F of substrate web 20, the result As a result, defects in the coating such as pinholes and vertical stripes are likely to occur, and the quality of the coating deteriorates. Such a reservoir portion F _B
Is unstable due to the relative positional relationship and dimensional relationship between the backup roll 14 and the coating head 18, so that the distance between the surface of the base material web 20 and the first end surface portion 16 a of the nozzle end surface 16 becomes unnecessarily large. This also occurs in the case.

In order to solve such a problem, the coating apparatus according to the illustrated embodiment is further provided on the first end face portion 16a of the nozzle end face 16 of the coating head 18 further upstream with respect to the substrate web running direction A. A reduced pressure chamber 44. The decompression chamber 44 is formed so as to communicate with a space between the nozzle end face 16 and the outer peripheral face 10 of the backup roll 14. During the coating operation, the pressure reducing chamber 44 is connected to an external pressure reducing device 46.
Is reduced by the operation of (1), thereby reducing the entrained air being caught between the reservoir portion F _B of the paint F were surface above substrate web 20 traveling on the backup roll 14 effectively or with the exclusion, it acts to stably hold the reservoir portion F _B to the ideal bead shape.
A gap G5 is formed between the wall 48 of the decompression chamber 44 and the substrate web 20 carried on the backup roll 14 so as to effectively promote decompression.

As described above, according to the coating apparatus according to the illustrated embodiment, various problems in the conventional backup roll type coating apparatus can be solved, the thickness of the coating film can be reduced as much as possible, and high-speed running can be performed. For a base material web to be formed, a coating film having a uniform thickness can be continuously formed with high accuracy and high quality stably for a long time.

The applicator according to the illustrated embodiment has various arrangements, shapes, and shapes within the range in which the above-described special effects can be obtained.
Dimensions can be taken. For example, the first end face portion substrate web running direction length L1 of the 16a of the nozzle surface 16 of the coating head 18, in order to form a reservoir portion F _B of the paint F in a stable bead shape, for example 1 mm to 20 mm, Preferably, it is set in the range of 3 mm to 10 mm. The length L2 of the second end surface portion 16b of the nozzle end surface 16 in the same direction is:
For example, it is set in the range of 1 mm to 20 mm, preferably 3 mm to 10 mm. If L2 is shorter than this range, it becomes difficult to form the second end face portion 16b, particularly the downstream end 34 thereof, at a high degree of straightness due to rigidity, and the detachment position P of the base web 20 is set. Backup roll 1 by
4 and the downstream end 34 tend to have a reduced separation effect. L
2 is longer than this range, not only is the influence of the surface accuracy of the second end face portion 16b liable to be exerted, but also, in particular, when the detachment position P is set near the inlet of the pressurizing gap 32, The portion of the base material web 20 that is not supported on the back side in the gap 32 becomes longer, and the same problem as in a conventional non-back-supported type coating apparatus tends to occur.

The angle α formed between the surface of the running base material web 20 after being detached from the backup roll 14 and the second end face portion 16b of the nozzle end face 16 is, for example, 0 to 10 degrees.
Degrees, preferably in the range of 1 to 3 degrees. Angle α
Is larger than this range, the pressure rise of the coating material F in the downstream region in the pressurized gap 32 tends to be excessive, and the coating material F overflows from the nozzle end face 16 to the outside, and the edge of the coating film F _C In some cases, a protruding portion continuous in a rib shape is formed. Further, the case where the angle α is 0 degree means that in the illustrated embodiment,
This is the case where the position Q on the outer peripheral surface 10 of the backup roll that defines the minimum space 42 between the backup roll 14 and the coating head 18 is the detached position P of the substrate web 20. Also in this case, by reducing the size of the minimum gap 42 as much as possible, it is possible to achieve a rise in the pressure of the coating material F in the downstream area within the pressurized gap 32 and at the outlet of the pressurized gap 32. Again, since the base material web 20 is not carried by the backup roll 14, the second end face portion 16b
The risk of damage to the downstream end 34 of the vehicle is reduced.

In the illustrated embodiment, the base web 20 and the second
As the angle α formed with the end face portion 16b approaches the upper limit of the above range, the gap size G1 at the downstream end 34 of the second end face portion 16b is reduced, and at the same time, the detachment position P moves to the inlet side of the pressurized gap 32. It will be understood. Also,
The distance between the outer peripheral surface 10 of the backup roll 14 and the back surface of the substrate web 20 at the outlet of the pressurized gap 32 can be increased as the detachment position P is closer to the inlet side of the pressurized gap 32, so that the second end face The risk of damage to the downstream end 34 of the portion 16b can be more effectively eliminated.

The traveling direction of the substrate web 20 after being detached from the backup roll 14 can be represented by a detachment angle β with respect to the outer peripheral surface 10 of the backup roll 14. The detachment angle β is shown in FIG. 2 by the angle formed between the tangent at the position Q on the outer peripheral surface 10 of the backup roll defining the minimum space 42 and the base material web 20 after detachment. In the embodiment of FIG. 2, the detachment angle β is substantially equal to the above-mentioned angle α.

Backup roll 14 and coating head 18
As shown in FIGS. 4A and 4B, the minimum spacing portion 4 is provided at the downstream end 34 of the second end face portion 16b of the nozzle end face 16.
2 can also be arranged relative to one another. FIG.
The arrangement shown in (a) is different from the arrangement shown in FIG. 2 in that the backup roll 14 at the position Q defining the minimum space 42 is formed.
While keeping the tangent line parallel to the second end face portion 16b,
The backup roll 14 and the coating head 18 are relatively moved in parallel. The arrangement shown in FIG. 4B further differs from the arrangement shown in FIG.
4 and the coating head 18 are relatively rotated, and the detachment angle β of the substrate web 20 at this time is an angle α formed between the substrate web 20 and the second end face portion 16b (FIG. 2). Smaller than. Considering such a case, it can be said that it is preferable that the departure angle β is set in the range of 0 ° to 5 ° in view of the above numerical range of the angle α.

However, in the arrangement shown in FIGS. 4A and 4B, when the detachment angle β of the substrate web 20 is 0 degree, the detachment position P on the outer peripheral surface 10 of the backup roll is
And the same problem as the conventional backup roll type coating apparatus occurs. That is, in such an arrangement, in most cases, the backup roll 14 and the base material web at the minimum interval 42 are maintained while maintaining the angle α formed between the base material web 20 and the second end face portion 16b at or below the upper limit of the above-described range. 20, it is difficult to keep a sufficient distance from the second end face portion 16b.
This is not a preferable arrangement from the viewpoint of eliminating the risk of damage to the device.

As shown in FIG. 5, the coating head 18 is configured such that the first end face portion 16a of the nozzle end face 16 is
It may be configured to protrude above b. With such a configuration, the surface of the base material web 20 supported by the backup roll 14 and the first end face portion 1 of the nozzle end face 16 are formed.
Optimizing the size of the gap between 6a, the shape of the reservoir portion F _B of the paint F described above formed therein may be the ideal bead. However, if the protrusion amount S of the first end face portion 16a is too large, contact between the upstream end of the first end face portion 16a and the base material web 20 (that is, indirect collision with the backup roll 14) is likely to occur. It costs. From this viewpoint, in the illustrated embodiment, the gap size G2 ≦ G
3 is desirable.

[0039] preventing the entrainment of entrained air into the reservoir portion F _B of the paint F formed on the first end face portion 16a of the nozzle surface 16, to hold the reservoir portion F _B to the ideal bead shape, vacuum The chamber 44 has a pressure of 0 kPa to -2.94 kPa.
_{(0mmH 2 O ~-300mmH 2} O) are preferably reduced to the internal pressure in the range. When the decompression chamber 44 is reduced beyond this range, it tends to destabilize the shape of the reservoir portion F _B rather.

When the vertical direction in FIG. 1 is the direction of gravity, the coating head 18 can be moved to the side from the lower end position of the backup roll 14, as shown in FIG. Accordingly, the guide roll 36 also moves the substrate web 20 to the backup roll 1 within the numerical range described above.
4 can be appropriately moved and disposed at a position where it can be detached from the outer peripheral surface 10.

In the coating apparatus having the above-described range, in order to stably form the coating film F _C having high-precision surface smoothness on the surface of the substrate web 20 for a long time, the coating head 18 is required. The downstream end 34 of the second end face portion 16b of the nozzle end face 16 is preferably formed as an edge having a straightness of ± 2 μm or less. The rotation of the coating film F out of the machining accuracy or assembling _{accuracy C} is required for the viewpoint in the coating apparatus of the shelf, in particular backup affects the uniformity of the coating film thickness of the substrate web running direction roll 14 deflection of time, i.e., the amplitude in the direction perpendicular to the surface of the substrate web 20 traveling, it is desirable to form less than 10% of the thickness of the coating film F _C.

Although the present invention has been described based on the preferred embodiment, the present invention is not limited to this.
Various modifications are possible. For example, instead of the above-described guide roll 36, various other guide devices having a small running resistance, such as a pneumatic guide device, can be adopted as the detaching means.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A coating apparatus according to the illustrated embodiment is prepared by using a coating material supply path 2 having a length L1 of the first end face portion 16a of 8.5 mm, a length L2 of the second end face portion 16b of 5 mm, a gap size G1 of 5 μm,
8, the inner dimension in the traveling direction of the substrate web = 250 μm, the protrusion amount S of the first end face portion 16a = 0, and the detachment angle β of the substrate web 20
= 1 degree, and the internal pressure of the decompression chamber 44 = -0.98 kPa (-1
00 mmH ₂ O). FIG. 7 shows the outer peripheral surface 10 of the backup roll 14 and the coating head 1 in this coating apparatus.
The structure of the air gap between the nozzle end face 16 of FIG.
The horizontal axis represents the first end from the upstream end of the second end face portion of the nozzle end face.
The vertical axis represents the distance between the outer peripheral surface 10 of the backup roll 14 and the nozzle end surface 16, which is the distance to each position on the end surface portion 16 a and the second end surface portion 16 b. Accordingly, curve I shows the distance between the outer peripheral surface 10 of the backup roll 14 and the nozzle end surface 16 over the entire nozzle end surface 16, and curve II shows the surface of the base web 20 and the nozzle end surface 1.
6 is shown over the entire nozzle end face 16.

With this coating device, an organic pigment-dispersed coating material having a viscosity of 5 cps is applied to a 50 μm-thick PET (polyethylene terephthalate) substrate web running at 50 m / min, and dried to a film thickness of 1.4 μm. Coatings were formed continuously. FIG. 8 shows the thickness of the formed coating film along the transverse direction of the substrate web. The horizontal axis is the transverse distance between both edges of the substrate web, and the vertical axis is the thickness of the coating. As can be seen from FIG. 8, a coating film having extremely high smoothness was formed.

[0045]

As is apparent from the above description, according to the present invention, in the coating apparatus for performing the die coating method, the thickness of the coating film can be reduced as much as possible, Provides a high-performance coating device that can stably form a coating film of uniform thickness stably with high accuracy and high quality, and can be applied in a wide range regardless of the thickness of the substrate web or the viscosity of the paint. Is done. Furthermore, if a pressure reducing means is arranged on the upstream side of the nozzle end face of the coating head in the direction of travel of the substrate web, similarly high-precision and high-quality coatings can be stably applied for a high-speed traveling substrate web for a long time. Thus, a high-performance coating apparatus capable of continuously forming a uniform thickness is provided.

[Brief description of the drawings]

FIG. 1 shows a configuration of a coating apparatus according to an embodiment of the present invention.
It is a figure which shows roughly with the base material web to apply.

FIG. 2 is an enlarged view showing a main part of the coating apparatus of FIG. 1;

FIG. 3 is a view similar to FIG. 2, showing a state during a paint application operation.

FIG. 4 is a view corresponding to FIG. 2 and showing the coating apparatus of FIG. 1;
(A) A modification in which the coating head is moved in parallel, and (b) a modification in which the coating head is rotated are shown.

FIG. 5 is a view corresponding to FIG. 2 and shows still another modification of the coating apparatus of FIG. 1;

FIG. 6 is a view showing still another modified example of the coating apparatus of FIG. 1;

FIG. 7 is a diagram showing a configuration of a void in the embodiment of the coating apparatus of FIG. 1 by a curve.

8 is a view showing the smoothness of a coating film in the example of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Outer peripheral surface 12 ... Stationary shaft 14 ... Backup roll 16 ... Nozzle end surface 18 ... Coating head 20 ... Substrate web 22 ... Pressing roll 28 ... Paint supply path 32 ... Pressurized space 34 ... Downstream end 36 ... Guide roll 42 ... Minimum Interval 44: Decompression chamber

Claims (3)

[Claims] 1. A backup roll that carries a substrate web running at a predetermined speed on an outer peripheral surface thereof and rotates around a stationary axis, and is disposed separately from the backup roll, and is disposed on the outer peripheral surface of the backup roll. A coating head provided with an opposite nozzle end face and a paint supply path communicating with the nozzle end face, and a coating head for continuously extruding paint on the nozzle end face; and providing the outer peripheral surface of the backup roll and the coating head of the coating head. In a coating apparatus for continuously forming a coating film of a predetermined thickness on the surface of a running base material web while measuring the coating material between the nozzle end face, the nozzle end face of the coating head, with respect to the base material web running direction At a position on the outer peripheral surface of the backup roll facing the pressurized area upstream of the downstream end and downstream of the paint supply path, the running substrate web is moved to the outer periphery. A detaching means for applying a fluid pressure higher than the initial application pressure of the paint entering the pressurized area of the nozzle end face to the paint at the downstream end of the nozzle end face. Coating device. 2. The nozzle according to claim 1, wherein the outer peripheral surface of the backup roll and the nozzle end surface of the coating head are closest to each other within the pressurized region of the nozzle end surface to define a minimum gap. Coating equipment. 3. The nozzle end face of the coating head, on an upstream side of the coating material supply path with respect to a substrate web running direction,
3. The coating apparatus according to claim 1, further comprising a decompression unit configured to decompress a space between the nozzle end surface and the outer peripheral surface of the backup roll. 4.