JP2000015164A - Coating applicator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the thin film coating of a coating liquid at a high speed even on a thin base by installing a flexible belt facing a coater head via auxiliary rolls to a side opposite to the coating surface of the base between a pair of guide rolls for guiding the base to the upstream side and downstream side of the coater head. SOLUTION: A pair of the guide rolls 10, 11 are installed before and behind the coater head 1 and the base 8 is run and guided along these rolls. A pair of the auxiliary rolls 12, 13 are installed aside therefrom and the flexible belt 9 is run under the guide thereof. Namely, the belt 9 is arranged to face the coater head 1 on the side opposite to the coating surface of the base 8. The base 8 is pressed to the front end of the lip of the coater head 1 by the belt 9, by which the tension deficiency of the thin base 8 is made up. The thin film coating of the coating liquid at a high speed from the coater heat 1 to the base 8 is made possible in spite in the thin base 8 and in spite of the presence of variation in the film thickness and the ruggedness of printing, or the like, on the surface of the base 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for applying a coating liquid to a running support, and more particularly to an apparatus for applying a coating liquid to a flexible support using a die coater.
Further, the present invention relates to a coating apparatus for performing high-speed and thin-film coating using a thin support.

[0002]

2. Description of the Related Art Conventionally, in a process of manufacturing a photographic photosensitive material, a magnetic recording medium, a surface treatment of a steel plate, and the like, there is a step of applying a coating solution on a flexible support. This coating liquid is prepared by mixing essential components such as a photosensitive material or magnetic particles with a resin binder, adding various additives as needed, and diluting the mixture with an organic solvent or the like to adjust the viscosity.

As a method of applying such a coating solution to a flexible support, various coating methods such as a roll coater, a gravure coater, a knife coater, a die coater, and various reverse coaters have hitherto been used. Have been. Among these, the die coater has no change in the coating liquid because the coating liquid is not exposed to air until immediately before coating, has excellent uniformity in the width direction of the coating film, and has a smooth surface. In recent years, its use has been increasing because of its superiority. Therefore, in addition to the conventional coating field, its application has been attempted in fields such as pressure-sensitive adhesives and surface treatment materials.

[0004] As a typical method of such a coating method using a die coater, a support is continuously provided on a pair of guide rolls arranged at a predetermined interval on the upstream and downstream sides of a coater head. There is known a method in which a coating liquid is uniformly, smoothly, and thinly guided by directly extruding a coating liquid onto a surface of an indicator from a coater head disposed between the guide rolls. In the case of this method, the amount of the coating solution pushed out from the slot of the die head is reduced by turning the lip portion at the tip of the die head that pushes the coating solution toward the support that continuously runs between the pair of guide rolls. Coating can be performed by changing the distance between the lip portion at the tip of the die head and the surface of the support by the balance between the corresponding application pressure and the reaction force generated by the support being pressed and bent by the die head.

The problem with the above coating method is that the balance between the coating pressure of the coating liquid extruded from the slot and the reaction force from the support obtained by the tension of the support is not stable, so that the distance between the tip of the coater head and the support is small. It is easy to change, and there is a disadvantage that the coating liquid formed between the tip of the coater head and the support is not stable, so that the entire coating width is not uniformly applied, that is, air entrainment is likely to occur. In addition, due to the instability of the liquid pool, there is also a defect that horizontal stripes called step unevenness occur in the width direction of the support intermittently in the running direction of the support. There is also the disadvantage of being difficult.

In order to achieve a thin film and a high speed by the above-mentioned method, the tension of the support is increased, or the amount of pushing the coater head into the support is increased so that the support is attached to the lip at the tip of the coater head. Consideration must be given to increasing the approach angle and the evacuation angle. The reason for increasing the tension is that the discharge amount of the application liquid pushed out from the slot of the coater head increases as the speed increases. The increase in the discharge amount means that the amount of the coating liquid supplied to the liquid pool of the coating liquid formed between the coater head tip and the support increases, and the pressure of the liquid pool increases.

When the pressure of the liquid pool increases, the distance between the tip of the coater head and the support increases even if the reaction force from the support obtained by pushing the coater head into the support until that time is constant. Would. An increase in the distance between the tip of the coater head and the support increases the instability of the coating behavior, easily causing air entrainment from the upstream lip side, and the generation of uncoated lines on the coating surface. Will happen. Therefore, in order to stabilize the coating state, it is necessary to increase the reaction force of the support as much as the pressure of the coating liquid and to reduce the distance between the tip of the die head and the support to a region where stable coating is possible.

However, when the tension of the support is increased, "vertical stripes" in which the support is bent in the width direction occur, and the uniformity of the coating film in the width direction is lost. Become. The magnitude of the tension at which the "vertical streaks" occur depends on the type and thickness of the support, but is, for example, about 20 kg / m or more when a PET film having a thickness of 20 μm is used.

When the amount of pushing the coater head into the support is increased to increase the angle of approach or retreat of the support to the lip at the tip of the coater head, in order to maintain a stable coating state, It is necessary to form an angle commensurate with the approach angle or the retreat angle of the support at the leading edge of the upstream lip and the downstream lip.

Further, when the approach angle of the support and the curvature of the upstream lip are changed by changing the application conditions, the angle of the leading edge of the lip often becomes smaller than the approach angle of the support. In such a case, a phenomenon occurs in which the entering support comes into contact with the lip tip edge, which may cause a problem that the support is damaged. Therefore, in order to solve these problems, a coater head has to be created again by changing the radius of curvature of the lip, which increases time and cost.

[0011] In particular, the above problems are caused when the support is thin,
The effect is large when there is unevenness on the support, especially when the support is printed as pre-processing, and the support is applied with a higher tension than before, such as when high speed and thin film coating are required. When transported, expansion of the support due to heat in the dryer and subsequent cooling may cause the pre-printed pitch to exceed the allowable range, and may cause partial contact due to contact with the lip tip when the support enters. It has been difficult to obtain a good coated surface, such as a scratch on a convex portion of the support, such as a printed portion.

[0012] In addition, a coating apparatus having a configuration in which a flexible guide belt is provided via upstream and downstream guide rolls in order to solve the above-mentioned problem has been known.

However, when the guide belt is installed via the guide roll which is a part of the pass line of the support as described above, since the contact area between the support and the guide belt is large, the guide belt is in close contact with the support. Then, the support deflects at the tip of the lip of the pressed coater head, etc.
There was a problem that stable running of the support was difficult to obtain.

[0014]

In a coating apparatus using a conventional die coater, when a thin support is used as described above, it is difficult to increase the speed and reduce the film thickness. It was difficult to obtain a uniform and good coated surface. However, the present invention has been made in consideration of the above-described circumstances, and even when a thin support is used, the thickness of the support may be “varied” or “unevenness” such as a print formed by pre-processing may be applied. And to provide a coating apparatus capable of high-speed and thin-film coating.

[0015]

According to the present invention, a pair of guide rolls for guiding a support member to an upstream side and a downstream side of a coater head are provided. What is claimed is: 1. A coating apparatus for directly applying a coating liquid to a support running between an upstream guide roll and a downstream guide roll, wherein said coater head includes an upstream lip and a downstream lip. In a coating apparatus for forming a slot portion capable of extruding a liquid and applying the coating liquid to a support running opposite to a coater head, the coating surface of the support opposite to the coating surface of the support between the upstream and downstream guide rolls And a flexible belt facing the coater head via an auxiliary roll.

Further, the invention according to a second aspect is characterized in that an adjustment roll capable of freely changing the tension of the belt by moving the belt is provided on a traveling path line of the belt stretched on the auxiliary roll. This is achieved by the coating apparatus according to claim 1.

According to a third aspect of the present invention, at least one of the auxiliary roll and the adjusting roll is driven at the same speed as the traveling speed of the support.
Alternatively, this is achieved by the coating apparatus according to claim 2.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a coater head (1) used in the coating apparatus of the present invention. The coater head (1) is provided on the side opposite to the coating surface of the support (8) with a coating solution (7) and a support (8). FIG. 9 is a cross-sectional view showing a use state in which a belt (9) is disposed to face the belt, and the belt (9) and the support (8) are provided with lips (2,
3) Contact only at the tip. Coater head (1)
Is a manifold provided to supply the coating liquid to the inside of the coater head (1) from a supply system (not shown) with respect to the upstream lip (2) and the downstream lip (3) with respect to the traveling direction of the support (8). (5) It is divided into a slot (4) which is a passage for pushing out the coating liquid from the manifold (5) to the lip (2, 3).

Guide rolls (10, 11) are arranged before and after the coater head (1), and separately from the auxiliary rolls (12, 11) for ensuring the running of the belt.
13) is installed. This state is shown in FIG.

The cross section of the manifold (5) is circular or elliptical, and is extended with the same or substantially the same cross-sectional shape in the width direction of the support (8). It is longer than or equal to the width of the support (8). The inside diameter of the manifold (5) is 5
The best size may be set to about 50 mm depending on the properties, viscosity, etc. of the coating liquid, and the open ends of the coating liquid are prevented from leaking to the outside of the coater head (1) by seal plates or the like. I have. Further, the supply of the coating liquid to the manifold (5) may be introduced from at least one of the opening ends, or at least one of the openings directly penetrates from the coater head (1) to the manifold (5). It may be introduced from the supply port.

Further, the slot (4) has a width of 0.1 mm which opens from the manifold (5) toward the support (8).
It is a slit-shaped coating liquid passage of 0.5 to 0.5 mm, and the distance from the manifold (5) to the tip of the lip is 5 to 10
0 mm. The width and distance of the slot (4) are also determined by the operating conditions such as the properties of the coating solution, the coating speed and the coating film thickness.

An upstream lip (2) and a downstream lip (3) located at the upstream and downstream sides with respect to the running direction of the support, respectively, are provided at the end of the slot (4) on the support side. Are located. The relative positions of the upstream lip (2) and the downstream lip (3) are set such that the position of the downstream lip (3) with respect to the upstream lip (2) is -0.0.
It can be set freely within the range of 01 to 0.5 mm. Further, the widths of the upstream lip (2) and the downstream lip (3) can be freely set independently in the range of 0.5 to 20 mm.

The coating liquid (7) is introduced from the outside of the coater head (1) into the manifold (5) via a supply system via a hose or a pipe. When the inside of the manifold (5) is filled with the coating liquid, the upstream lip (2) and the downstream lip pass through the slot (4) communicating with the manifold (5) with uniform pressure distribution and flow rate distribution in the width direction. (3) Further, a liquid pool (6) surrounded by the support (8) is formed. The liquid pool (6) is formed by the pressure (amount) of the coating liquid extruded from the slot (4) and the physical properties such as the viscosity of the coating liquid, the tension of the support (8) and the reaction force by the flexible belt (9). The size is determined by the total balance of the above, and the distance between the upstream lip (2) and the downstream lip (3) and the support (8) is determined.

The coating liquid having the liquid pool (6) is applied to the surface of the running support and the coating process is completed. The coating film thickness is determined by the flow rate of the coating liquid to be discharged and the running speed of the support. You. However, the applied coating solution does not necessarily spread in the width direction of the support, and a uniform film thickness distribution is not obtained. In some cases, air entrainment may occur, and uncoated portions may become streaks and defects may occur. . In such a case, since the distance between the lip and the support is too large, it is necessary to increase the tension of the support and reduce the liquid pool. This state will be described with reference to FIG. If the application conditions are constant except for the tension, by increasing the tension, the stable application region free of air entrainment will be extended to the low application film thickness side.

The flexible belt (9) via the auxiliary rolls (12, 13) is installed on the side opposite to the coating surface of the support (8), facing the coater head (1). The vehicle travels in a state where a certain tension is applied in the same direction as the traveling direction of (a). The belt stably supports the auxiliary roll (12,
13), and a seamless endless belt is required. Further, it is preferable that the belt has a thickness of 0.1 to 5.0 mm and has no thickness variation in both the width direction and the running direction, and it is more preferable that the belt has the same Young's modulus.
Further, it is desirable that the surface of the belt has a small coefficient of friction in order to improve the slip of the film.

The function of the flexible belt (9) is that, under coating conditions for high-speed thin film coating, the tension of the support must be increased when the film thickness is normally reduced. By applying the necessary tension like a thin support, the support is bent and vertical streaks are generated, and even under application conditions in which the support is wavy in the width direction, no vertical streak occurs in the tension of the support. The tension is reduced by reducing the tension to 20 kg / m or less for a PET film having a thickness of 20 μm, for example, and pressing the support against the tip of the coater head lip by a flexible belt from the opposite side to the coating surface. It is possible to make up for it.

In the present invention, the support (8) and the belt (9) are formed by the lips (2, 3) of the coater head (1).
The coater head (1) in which the belt is tightly pressed against the support, as in the case where the belt (9) is installed on a part of the traveling system of the support (8), because the belt is installed so as to contact only at the tip. The problem of unstable running of the support, such as bending of the support at the tip of the lip, has been resolved.

Further, in addition to the auxiliary rolls (12, 13), the tension of the belt (9) can be freely adjusted by adding an adjusting roll (14) capable of adjusting the length of the pass line of the belt by moving the roll. It becomes possible. 4 and 5 show an example. The effect of this is to change the belt tension without changing the amount of press of the coater head into the support and the tension of the support without changing the tension of the support, thereby expanding the stable coating area to the low coating thickness side. It is possible to do.

[0029]

As described above, by using the coating apparatus according to the present invention, when performing thin-film coating at a high speed using a thin support, a high tension is not applied to the support, and a stable air-free entrainment is performed. An enlargement of the application area can be achieved.

[0030]

[Brief description of the drawings]

FIG. 1 is a sectional view of a coater head of a coating apparatus of the present invention.

FIG. 2 is an embodiment of a coating apparatus of the present invention.

FIG. 3 is a graph showing a film tension and a stable application area when applied by a conventional method.

FIG. 4 is an embodiment of a coating apparatus of the present invention.

FIG. 5 is an embodiment of a coating apparatus of the present invention.

[Explanation of symbols]

 1 Coater head 2 Upstream lip 3 Downstream lip 4 Slot 5 Manifold 6 Liquid pool 7 Coating liquid 8 Support 9 Belt 10 Upstream guide Roll 11 ‥‥ Downstream guide roll 12 ‥‥ Auxiliary roll 13 ‥‥ Auxiliary roll 14 ‥‥ Adjustment roll A ‥‥ Running direction of support B ‥‥ Rotation direction of belt

Claims (3)

[Claims] 1. A coating liquid is applied directly to a support running between an upstream guide roll and a downstream guide roll, comprising a pair of guide rolls for guiding a support upstream and downstream of a coater head. A coating device, wherein the coater further comprises an upstream lip and a downstream lip, and a slot portion capable of extruding a coating liquid is formed between these lips, and the coating material is applied to a support running against a coater head. In a coating apparatus for applying a liquid, a flexible belt is provided between the upstream and downstream guide rolls on the side opposite to the coating surface of the support opposite to the coater head via an auxiliary roll. Coating equipment. 2. The coating apparatus according to claim 1, further comprising an adjusting roll on a traveling path line of the belt stretched on the auxiliary roll, the adjusting roll being capable of freely changing the belt tension by moving. . 3. The coating apparatus according to claim 1, wherein at least one of the auxiliary roll and the adjusting roll is driven at the same speed as the traveling speed of the support.