WO2021065579A1

WO2021065579A1 - Die head

Info

Publication number: WO2021065579A1
Application number: PCT/JP2020/035541
Authority: WO
Inventors: 諭司國安
Original assignee: 富士フイルム株式会社
Priority date: 2019-09-30
Filing date: 2020-09-18
Publication date: 2021-04-08
Also published as: CN114450095A; JP7270757B2; JPWO2021065579A1; KR102636770B1; KR20220051853A; CN114450095B

Abstract

Provided is a die head, which has: two or more lips disposed in a row and a slot for transferring and discharging coating liquid, the slot being formed between adjacent lips. The land surface of one of the lips at one end in the direction of the row and/or the outer surface of another lip at the other end in the direction of the row, the outer surface being on the side opposite the slot-forming surface of the lip and joining with the land surface, forms a dynamic contact angle hysteresis of 20° or less, which is provided by methyl ethyl ketone.

Description

Die head

This disclosure relates to die heads.

In a coating device equipped with a die head, a method of forming a target coating layer on a base material is known.

Patent Document 1 describes coating in a coating member manufacturing apparatus in which a coating liquid discharge port is formed between a pair of lip tips and a coating film is formed on the surface of a member to be coated that moves relative to the discharge port. Described is an apparatus for manufacturing a coating member in which the tip of the downstream lip located on the film forming side has a larger contact angle with water than the tip of the upstream lip.

Patent Document 2 describes a die coating device used when a coating liquid for forming a transparent conductive layer containing at least a metal material is applied onto a transparent base material to form a transparent conductive layer, and is used for forming the transparent conductive layer. It has a die head that discharges the coating liquid, a coating liquid tank that houses the coating liquid for forming the transparent conductive layer, and a liquid feeding path that sends the coating liquid for forming the transparent conductive layer from the coating liquid tank to the die head. As the die head, a die coating device in which a liquid-repellent region is formed on a surface located at least in a direction opposite to the coating direction is described.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-248349 Patent Document 2: Japanese Patent Application Laid-Open No. 2016-68047

In the die head, usually, the contact portion of the lip with the coating liquid is covered with the coating liquid once the coating liquid adheres (that is, a film formed by the coating liquid is formed on the contact portion. Will be done). Since the contact portion of the lip with the coating liquid is covered with the coating liquid, that becomes the starting point and coating streaks are generated.
There are two types of coating streaks referred to here. That is, for example, there are two coating streaks caused by the lip on the most upstream side and the coating streaks caused by the lip on the most downstream side with respect to the transport direction of the base material to be coated.
The coating streaks caused by the lip on the most upstream side are the streaks caused by the dry matter (that is, solid content) of the coating liquid generated on the land surface or the edge of the land surface disturbing the shape of the bead end, and the land. There are cases where the streaks are caused by the droplets formed by the difference in surface tension between the coating liquid formed on the surface and the bead and the droplets adhering to the end of the bead. In the former case, linear film thickness unevenness (that is, streaks) extending along the transport direction of the base material appears individually or continuously in a plurality of layers, and the width thereof is about 0.1 mm to 5 mm. In the latter case, linear film thickness unevenness (that is, streaks) extending along the transport direction of the base material appears sporadically alone or in plurality, and the width thereof is about 0.1 mm to 5 mm.
On the other hand, the coating streaks caused by the lip on the most downstream side reach the surface connected to the land surface on the side opposite to the slot forming surface of the lip, and are droplets of the coating liquid or a dried product (that is, solid content) of the coating liquid. However, the streak is caused by disturbing the shape of the bead end. In the case of this streak, linear film thickness unevenness (that is, streaks) extending along the transport direction of the base material appears individually or continuously in a plurality of streaks, and the width thereof is about 0.1 mm to 5 mm.
To confirm the coating streaks caused by the most upstream lip and the coating streaks caused by the most downstream lip, the film is observed by observing the surface shape of the formed coating film while observing the shape of the bead at the time of coating. It can be confirmed by capturing the shape of the uneven thickness. That is, by associating the observation result of the shape of the bead with the shape of the formed film thickness unevenness, it is a coating streak caused by the lip on the most upstream side, or a coating streak caused by the lip on the most downstream side. You can check if it is.
Here, the planar observation of the coating film may be visually observed, a magnifying glass may be used, or an apparatus for observing the planar surface by transmission or reflection may be used. Further, a microscope may be used for observing the surface shape of the coating film, or a cross Nicol method may be used depending on the type of the coating film.

Therefore, an object to be solved by one embodiment of the present disclosure is to provide a die head capable of suppressing the occurrence of coating streaks.

Specific means for solving the problem include the following aspects.

<1> It has two or more lips in parallel and a slot formed between adjacent lips to transfer and discharge the coating liquid.
At least one of the land surface of the lip at one end in the parallel direction and the outer surface of the lip at the other end in the parallel direction connected to the land surface on the side opposite to the slot forming surface has a dynamic contact angle hysteresis of 20 ° or less due to methyl ethyl ketone. Is a die head.

<2> The die head according to <1>, wherein the land surface of the lip at one end in the parallel direction and the outer surface of the lip at the other end in the parallel direction have a ten-point average roughness Rzjis of 1.0 μm or less. ..

<3> The die head according to <1> or <2>, wherein the dynamic contact angle hysteresis due to the methyl ethyl ketone on the land surface of the lip at the other end in the parallel direction is 20 ° or less.

<4> Of the land surface of the lip at one end in the parallel direction and the outer surface of the lip at the other end in the parallel direction, the surface having the dynamic contact angle hysteresis of 20 ° or less due to the methyl ethyl ketone is the fluorine-containing compound. The die head according to any one of <1> to <3>, comprising a surface treatment layer formed in use.
<5> The die head according to <4>, wherein the fluorine-containing compound is a compound having a perfluoropolyether group.
<6> The die head according to any one of <1> to <5>, wherein the lip at the other end in the parallel direction has a curved surface at a portion connected to the land surface on the outer surface in a side view.
<7> The die head according to <6>, wherein the curved surface of the lip at the other end in the parallel direction is a curved surface having a radius of curvature of 0.2 mm or more.
<8> At the time of coating, the lip at one end in the parallel direction is located on the downstream side with respect to the coating direction, and the lip at the other end in the parallel direction is located on the upstream side with respect to the coating direction, <1> to <7. The die head described in any one of>.

According to one embodiment of the present disclosure, a die head capable of suppressing the occurrence of coating streaks is provided.

It is a schematic side view which shows an example of the tip part of the die head in this disclosure. It is a schematic side view which shows another example of the tip part of the die head in this disclosure. It is a schematic side view which shows still another example of the tip part of the die head in this disclosure.

Hereinafter, the die head of the present disclosure will be described in detail.
It should be noted that the present disclosure is not limited to the embodiments described below with reference to the drawings, and can be carried out with appropriate modifications within the scope of the purpose of the present disclosure. The components shown by using the same reference numerals in each drawing mean that they are the same components. The description of overlapping components and symbols in each embodiment may be omitted.
The dimensions in the drawings do not necessarily represent the actual dimensions and ratios.

In the present disclosure, the term "process" is included in the term not only in an independent process but also in the case where the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes.
In the present disclosure, the numerical range indicated by using "-" indicates a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively.
In the numerical range described stepwise in the present disclosure, the upper limit value described in one numerical range is the upper limit value of the numerical range described in another stepwise description, or the lower limit value described in a certain numerical range is. , May be replaced with the lower limit of the numerical range described in other steps. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.
In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.
In the present disclosure, the "solid content" refers to a component other than a solvent (preferably an organic solvent).

As described above, in coating using a die head, a method of suppressing the occurrence of the above-mentioned coating streaks has been studied.
As a result of the study by the present inventor, with respect to the transport direction of the base material to be coated, the outer surface of the lip on the most upstream side, which is opposite to the slot forming surface and is connected to the land surface, and the most downstream side. It was found that the occurrence of coating streaks can be suppressed by setting the dynamic contact angle hysteresis due to methyl ethyl ketone to 20 ° or less for at least one of the two locations, that is, the land surface of the lip.
Even if the outer surface and the land surface having the dynamic contact angle hysteresis of 20 ° or less are once covered with the coating liquid, the coating liquid moves quickly and can return to a clean state when the bead is formed. The clean state is a three-phase interface composed of a solid (that is, an outer surface and a land surface), a liquid (that is, a coating liquid), and a gas (that is, an atmosphere) on the outer surface and the land surface when the die head is viewed from the side. Refers to the formation of.
In particular, by setting the dynamic contact angle hysteresis of methyl ethyl ketone having a low surface tension of about 20 ° to 20 ° or less, the above-mentioned effect of forming a clean state can be obtained regardless of the type of coating liquid applied to the die head. Conceivable.
When a three-phase interface is formed on the outer surface and the land surface, the amount of the coating liquid staying on the outer surface and the land surface is reduced, and a film of the coating liquid is present on the outer surface and the land surface. It is considered that the occurrence of coating streaks caused by this can be suppressed.
In the die heads described in Patent Documents 1 and 2, once a film is formed by the coating liquid on the outer surface, this film is not removed and the outer surface is not exposed, so that the three-phase interface is not formed. ..

Based on the above findings, the die head of the present disclosure has two or more lips in parallel and a slot formed between adjacent lips to transfer and discharge the coating liquid, and the land surface of the lip at one end in the parallel direction. And at least one of the outer surface of the lip at the other end in the parallel direction, which is opposite to the slot forming surface and is connected to the land surface, has a dynamic contact angle hysteresis of 20 ° or less due to methyl ethyl ketone.
In the die head of the present disclosure, at the time of coating, the lip at one end in the parallel direction is on the downstream side with respect to the coating direction, and the lip at the other end in the parallel direction is on the upstream side with respect to the coating direction. Can be suppressed.
Here, the "coating direction" in the present disclosure refers to the direction in which the coating film is formed.
When coating using the die head of the present disclosure, the die head and the member to be coated are relatively moved. That is, "moving the die head and the member to be coated relative to each other" means moving the member to be coated with respect to the fixed die head, moving the die head with respect to the fixed member to be coated, and the die head. And the member to be coated are moved to each other in one direction.
When the base material, which is the member to be coated, is transported and moved to the fixed die head, the transport direction of the base material and the above-mentioned "coating direction" are opposite to each other.
Further, in the present disclosure, "the outer surface of the lip at the other end in the parallel direction, which is opposite to the slot forming surface and is connected to the land surface, has a dynamic contact angle hysteresis of 20 ° or less due to methyl ethyl ketone." Unless otherwise noted, this includes the dynamic contact angle hysteresis of methyl ethyl ketone of 20 ° or less on all or part of the outer surface of the lip at the other end in the parallel direction. On the outer surface of the lip at the other end in the parallel direction, the region where the dynamic contact angle hysteresis of methyl ethyl ketone is 20 ° or less preferably includes at least a region in contact with the coating liquid.
Hereinafter, the region in contact with the coating liquid is also referred to as a contact portion.
Further, in the present disclosure, the lower limit of the dynamic contact angle hysteresis due to methyl ethyl ketone is 1 ° in any aspect, for example, from the viewpoint of the measurement limit.

In the conventional die head (for example, the die head described in Patent Documents 1 and 2 above), depending on the type of the coating liquid and the coating conditions, the lip on the most upstream side with respect to the transport direction of the base material described above is caused. The amount of coating streaks generated due to the most downstream lip may be different.
Therefore, in the die head of the present disclosure, the corresponding surface of the lip on the side where coating streaks are likely to occur, that is, the land surface of the lip at one end in the parallel direction and / or the outer surface of the lip at the other end in the parallel direction is moved by methyl ethyl ketone. By setting the target contact angle hysteresis to 20 ° or less, the amount of coating streaks generated can be effectively reduced.
In order to more effectively reduce the amount of coating streaks generated, in the die head of the present disclosure, the land surface of the lip at one end in the parallel direction and the land surface of the lip at the other end in the parallel direction on the opposite side of the slot forming surface. This is an embodiment in which the dynamic contact angle hysteresis due to methyl ethyl ketone is set to 20 ° or less for both the outer surface connected to and the outer surface.

[Dynamic contact angle hysteresis by methyl ethyl ketone]
First, the dynamic contact angle hysteresis due to methyl ethyl ketone will be described.
The "dynamic contact angle hysteresis by methyl ethyl ketone" is also simply referred to as "dynamic contact angle hysteresis".
The dynamic contact angle hysteresis refers to the difference [θa−θr] between the forward contact angle (θa) and the receding contact angle (θr) when the droplet slides down the surface of the solid wall. In the present disclosure, as the droplet, a droplet of methyl ethyl ketone is used.
Dynamic contact angle hysteresis is based on the forward and backward contact angles when the droplet is plucked on the surface of a horizontally supported solid wall, the solid wall is gradually tilted, and the droplet begins to slide down. Calculated.
The measurement is performed by the sliding method as described above (that is, the state of the droplet when the droplet is plucked on the surface of a horizontally supported solid wall, the solid wall is gradually tilted, and the droplet starts to slide). Method of measuring) is used. The measurement is performed in an environment of room temperature of 25 ° C. and humidity of 50%. The conditions for the measurement are that the surface temperature of the solid wall is 25 ° C., the droplet temperature is 25 ° C., and the droplet amount is usually 1 μL. The amount is ~ 4 μL, but the amount of liquid is not limited from the viewpoint of reproducing a situation close to an actual phenomenon. The die head itself may be used for the solid wall, or the same surface as the land surface, outer surface, etc., which is the measurement target area (specifically, the same surface treatment layer and the same ten-point average roughness) may be used. A plate-like material having a surface having Rzjis) may be used.

The die head of the present disclosure is an extrusion type die head, and a bead is formed by collecting the coating liquid discharged from the slot between a slot for discharging the coating liquid and a member to be coated (for example, a base material) to form a bead. The coating liquid is applied to the member to be coated via the above.
That is, the bead is a coating liquid pool formed between the die head and the member to be coated.

Hereinafter, the die head of the present disclosure will be described in detail with reference to the drawings.
FIG. 1 is a schematic side view showing an example of the tip end portion of the die head in the present disclosure.

The die head 100A shown in FIG. 1 has an upstream lip 10 located on the upstream side and a downstream lip 20 located on the downstream side with respect to the transport direction X of the base material F to be coated.
That is, in the embodiment shown in FIG. 1, since the coating liquid is applied onto the base material F that is transported and moved, the transport direction X of the base material is opposite to the coating direction.
In addition, in FIG. 1, the contact portion 20Cz in the downstream lip 20 is described so as to have a step with respect to the surface 20C of the downstream lip 20, but this notation is for convenience of explanation and the contact portion 20Cz. Does not have a configuration in which there is a step with respect to the surface 20C of the downstream lip 20. This also applies to the contact portion 20Cz on the surface 20C of the downstream lip 20 shown in FIG. 2, which will be described later, and the contact portion 50Cz on the surface 50C of the downstream lip 50 shown in FIG.

In the die head 100A, the upstream lip 10 has a slot forming surface 10B, and the downstream lip 20 has a slot forming surface 20B. As shown in FIG. 1, the upstream lip 10 has a slot forming surface 10B and a downstream side lip 10. A slot 30 for transferring and discharging the coating liquid L is formed between the side lip 20 and the slot forming surface 20B.
The slot 30 communicates with a manifold (not shown). The manifold is a space extending along the width direction of the die head 100A (that is, the depth direction in FIG. 1), and the coating liquid L supplied to the die head 100A is expanded in the coating width direction (that is, the width direction of the die head 100A). It is poured and the coating liquid L is temporarily stored.

In the die head 100A shown in FIG. 1, a bead B is formed between the slot 30 and the base material F at the time of coating, and the coating liquid L is applied to the base material F via the bead B.

In the die head 100A, the land surface 10A of the upstream lip 10 has a dynamic contact angle hysteresis of 20 ° or less. The land surface 10A is an example of the land surface of the lip at one end in the parallel direction. Further, the contact portion 20Cz with the coating liquid on the surface 20C of the downstream lip 20 also has a dynamic contact angle hysteresis of 20 ° or less. The contact portion 20 Cz is a part of the outer surface of the lip at the other end in the parallel direction, which is connected to the land surface on the side opposite to the slot forming surface, and is an example of the contact portion with the coating liquid.
When the dynamic contact angle hysteresis of the land surface 10A and the contact portion 20Cz with the coating liquid is 20 ° or less, the above-mentioned three-phase interface is formed at the land surface 10A and the contact portion 20Cz with the coating liquid. As a result, the occurrence of coating streaks can be suppressed.
The region of the contact portion 20Cz with the coating liquid, which occupies the surface 20C of the downstream lip 20, may be a region where the coating liquid can come into contact, which is assumed in consideration of the coating liquid, coating conditions, and the like. As the formation region of the contact portion 20Cz with the coating liquid, for example, a region of 1 mm or more from the edge portion of the land surface 20A is set.
From the viewpoint of surface treatment efficiency and the like, it is preferable that the dynamic contact angle hysteresis of the entire surface of the surface 20C of the downstream lip 20 is 20 ° or less.

Further, even if the three-phase interface moves from the contact portion 20Cz to the land surface 20A due to disturbance such as vibration, the downstream lip 20 can be prevented from forming a coating liquid film on the land surface 20A. The land surface 20A also preferably has a dynamic contact angle hysteresis of 20 ° or less.
Further, from the viewpoint that the coating liquid is easily removed when cleaning the die head 100A and failure due to dirt on the slot 30 is unlikely to occur when the subsequent coating is restarted, the slot forming surface 10B of the upstream lip 10 and the slot forming surface of the downstream lip 20 are less likely to occur. It is preferable that the dynamic contact angle hysteresis of both 20B is 20 ° or less.
Here, the

land surfaces

10A and 20A both refer to surfaces facing the base material F.

In the die head 100A, the distance between the land surface 10A of the upstream lip 10 and the base material F and the distance between the land surface 20A of the downstream lip 20 and the base material F are both the viscosity of the coating liquid and the coating film to be formed. It may be determined according to the film thickness and the like.
For example, the distance between the land surface 10A of the upstream lip 10 and the base material F and the distance between the land surface 20A of the downstream lip 20 and the base material F can be selected from 50 μm to 500 μm, respectively, and are 100 μm. You may choose up to 300 μm.
Here, the above distance refers to the shortest distance between the land surface and the base material. Such a distance can be measured with, for example, a taper gauge.

Subsequently, another aspect of the die head in the present disclosure will be described with reference to FIG.
Here, FIG. 2 is a schematic side view showing another example of the tip end portion of the die head in the present disclosure.
The die head shown in FIG. 2 is a die head for multi-layer coating.

The die head 100B shown in FIG. 2 has an upstream lip 10 on the most upstream side, a downstream lip 20 on the most downstream side, and an upstream lip 10 and a downstream side with respect to the transport direction X of the base material F to be coated. It has an intermediate lip 40, which is between the lip 20 and the lip 20.
The upstream lip 10 has a slot forming surface 10B, the downstream lip 20 has a slot forming surface 20B, and the intermediate lip 40 has slot forming surfaces 40B ₁ and 40B ₂ . Slot 30a for transferring and discharging the coating liquid L ₁ between the slot formation surface 40B ₁ of the slot forming surface 10B and the intermediate lip 40 of the upstream lip 10 is formed. The slot 30b for transferring and discharging the coating liquid L ₂ between the slot formation surface 20B of the slot forming surface 40B ₂ and the downstream lip 20 of the intermediate lip 40 is formed.
Then, the slot 30a and the slot 30b communicate with each other through a manifold (not shown). The manifold in the die head 100B is the same as the manifold in the die head 100A.

Die head 100B shown in FIG. 2, the time of coating, slot 30a, slots 30b, and between the base material F, and the bead B is formed by the coating solution _{L 1} and the coating solution _{L 2,} via the bead B The coating liquid L ₁ and the coating liquid L ₂ are applied to the base material F.

In the die head 100B, the land surface 10A of the upstream lip 10 has a dynamic contact angle hysteresis of 20 ° or less. The land surface 10A is an example of the land surface of the lip at one end in the parallel direction. Further, the contact portion 20Cz with the coating liquid on the surface 20C of the downstream lip 20 also has a dynamic contact angle hysteresis of 20 ° or less. The contact portion 20 Cz is a part of the outer surface of the lip at the other end in the parallel direction, which is connected to the land surface on the side opposite to the slot forming surface, and is an example of the contact portion with the coating liquid.
When the dynamic contact angle hysteresis of the land surface 10A and the contact portion 20Cz with the coating liquid is 20 ° or less, the above-mentioned three-phase interface is formed at the land surface 10A and the contact portion 20Cz with the coating liquid. As a result, the occurrence of coating streaks can be suppressed.
Even in the die head 100B, the region where the contact portion 20Cz with the coating liquid occupies the surface 20C of the downstream lip 20 is a region where the coating liquid can come into contact, which is assumed in consideration of the coating liquid, the coating conditions, and the like. Good. As the formation region of the contact portion 20Cz with the coating liquid, for example, a region of 1 mm or more from the edge portion of the land surface 20A is set.
From the viewpoint of surface treatment efficiency and the like, it is preferable that the dynamic contact angle hysteresis of the entire surface of the surface 20C of the downstream lip 20 is 20 ° or less.

Further, in the die head 100B, even if the three-phase interface moves from the contact portion 20Cz to the land surface 20A due to disturbance such as vibration, it can be prevented from forming a coating liquid film on the land surface 20A, which is downstream. The land surface 20A of the side lip 20 also preferably has a dynamic contact angle hysteresis of 20 ° or less.
Further, from the viewpoint that the coating liquid can be easily removed when cleaning the die head 100B, it is preferable that the land surface 40A of the intermediate lip 40 also has a dynamic contact angle hysteresis of 20 ° or less.
Further, from the viewpoint that the coating liquid can be easily removed when cleaning the die head 100B and failure due to dirt on the

slots

30a and 30b is unlikely to occur when the subsequent coating is restarted, the slot forming surface 10B of the upstream lip 10 and the slot of the downstream lip 20 The forming surface 20B and the slot forming surfaces 40B ₁ and 40B _{2 of the} intermediate lip 40 also preferably have a dynamic contact angle hysteresis of 20 ° or less.
Here, the land surfaces 10A, 20A, and 40A all mean surfaces facing the base material F.

In the die head 100B, the distance between the land surface 10A of the upstream lip 10 and the base material F, the distance between the land surface 20A of the downstream lip 20 and the base material F, and the land surface 40A and the base material F of the intermediate lip 40 The distances may be determined according to the viscosity of the coating liquid, the thickness of the coating film to be formed, and the like.
For example, the distance between the land surface 10A of the upstream lip 10 and the base material F, the distance between the land surface 20A of the downstream lip 20 and the base material F, and the distance between the land surface 40A of the intermediate lip 40 and the base material F. Can be selected from 50 μm to 500 μm, respectively, and may be selected from 100 μm to 300 μm.

In addition, FIG. 3 will be used to describe yet another aspect of the die head in the present disclosure.
Here, FIG. 3 is a schematic side view showing still another example of the tip end portion of the die head in the present disclosure.
The die head 100C shown in FIG. 3 has an upstream lip 10 on the upstream side and a downstream lip 50 on the downstream side with respect to the transport direction X of the base material F to be coated.
The die head 100C shown in FIG. 3 has a configuration in which the downstream lip 50 is provided instead of the downstream lip 20 in the die head 100C shown in FIG. Since each component other than the downstream lip 50 shown in FIG. 3 has the same function and configuration as each component in the die head 100A shown in FIG. 1, description thereof will be omitted here.

The downstream lip 50 in the die head 100C has a land surface 50A, a slot forming surface 50B, and a surface 50C. The surface 50C of the downstream lip 50 has a contact portion 50Cz with the coating liquid. The contact portion 50 Cz is a part of the outer surface of the lip at the other end in the parallel direction, which is connected to the land surface on the side opposite to the slot forming surface, and is an example of the contact portion with the coating liquid. The contact portion 50Cz has a curved surface whose portion connected to the land surface 50A is convex when viewed from the side as shown in FIG.
In the die head 100C, since the dynamic contact angle hysteresis of the land surface 10A and the contact portion 50Cz with the coating liquid is 20 ° or less, the above-mentioned three-phase interface is formed on the land surface 10A and the contact portion 50Cz. As a result, the occurrence of coating streaks can be suppressed.
The three-phase interface formed during the application of the coating liquid by the die head 100C usually moves in the region of the contact portion 50 Cz due to various factors. Since the portion connected to the land surface 50A has a convex curved surface such as the contact portion 50Cz, the degree of freedom of movement of the formed three-phase interface can be improved. That is, the movement of the three-phase interface is not hindered by the corners of the downstream lip 50. Further, at the contact portion 50 Cz, the liquid does not remain at the corner even if the three-phase interface moves (even if the liquid separates from the three-phase interface and adheres to the corner, it remains at the corner. It is possible to suppress the occurrence of coating streaks.
By improving the degree of freedom of movement of the three-phase interface at the contact portion 50 Cz, the occurrence of coating streaks can be suppressed more effectively.

The convex curved surface at the contact portion 50 Cz is preferably an arc curved surface from the viewpoint of processing accuracy.
Further, the convex curved surface at the contact portion 50 Cz is preferably a curved surface having a radius of curvature of 0.1 mm or more, and preferably a curved surface having a radius of curvature of 0.2 mm or more.
The upper limit of the radius of curvature of the convex curved surface is, for example, 10 mm.

Here, the radius of curvature of the curved surface is measured by the following method.
Observe from the side with a microscope (for example, manufactured by KEYENCE CORPORATION), and obtain the radius of curvature from the observed image.
The radius of curvature is obtained for 10 points on the curved surface, and the arithmetic mean value at 10 points is taken as the radius of curvature of the curved surface on the outer surface.

The region (including the convex curved surface) of the contact portion 50Cz with the coating liquid, which occupies the surface 50C of the downstream lip 50, is a region where the coating liquid can come into contact, which is assumed in consideration of the coating liquid, coating conditions, and the like. It should be. As the formation region of the contact portion 50 Cz with the coating liquid, for example, a region of 1 mm or more from the edge portion of the land surface 50A is set.
From the viewpoint of surface treatment efficiency and the like, it is preferable that the dynamic contact angle hysteresis of the entire surface of the surface 50C of the downstream lip 50 is 20 ° or less.

Further, even if the three-phase interface moves from the contact portion 50 Cz to the land surface 50 A due to disturbance such as vibration, the downstream lip 50 can be prevented from forming a coating liquid film on the land surface 50 A. The land surface 50A also preferably has a dynamic contact angle hysteresis of 20 ° or less.
When the portion of the contact portion 50Cz connected to the land surface 50A has a convex curved surface as in the downstream lip 50, the land surface 50A is a surface facing the base material F and refers to a flat surface portion. That is, when viewed from the side as shown in FIG. 3, the region indicated by the straight line is the land portion of the downstream lip.

In the die head 100C, the distance between the land surface 10A of the upstream lip 10 and the base material F and the distance between the land surface 50A of the downstream lip 50 and the base material F are both the viscosity of the coating liquid and the coating film to be formed. It may be determined according to the film thickness and the like.
For example, the distance between the land surface 10A of the upstream lip 10 and the base material F and the distance between the land surface 50A of the downstream lip 50 and the base material F can be selected from 50 μm to 500 μm, respectively, and are 100 μm. You may choose up to 300 μm.
Here, the above distance refers to the shortest distance between the land surface and the base material. Such a distance can be measured with, for example, a taper gauge.

The die head of the present disclosure is preferably made of metal, and the main body of the die head and the tip of the lip may be made of different metals.
Specifically, as the metal constituting the die head of the present disclosure, in addition to stainless steel, cemented carbide (for example, TF15 (Mitsubishi Materials Corporation), cemented carbide (for example, Nippon Tungsten)) used for the tip of the lip is used. Co., Ltd.) and the like.
In the die head of the present disclosure, as described above, when the contact portion of the coating liquid has a convex curved surface, the convex curved surface may be formed by chamfering.

[surface treatment]
Subsequently, a method of controlling the dynamic contact angle hysteresis will be described.
As a method for reducing the dynamic contact angle hysteresis of the land surface 10A, the contact portion 20 Cz with the coating liquid, and the like to 20 ° or less, at least one compound selected from the group consisting of a fluorine-containing compound and a silicon-containing compound is used. The surface treatment used can be mentioned.
That is, it is preferable that the land surface 10A, the contact portion 20Cz with the coating liquid, and the like include a surface treatment layer formed by using a fluorine-containing compound. The surface treatment layer formed by using the fluorine-containing compound is, for example, a composition such as "Fluorine-based ultrathin film coat MX-031" of Surf Industry Co., Ltd. (specifically, a composition containing a fluorine-containing compound). , For example, a coating agent) is preferably used.

(Fluorine-containing compound)
The fluorine-containing compound used for the surface treatment is not particularly limited as long as it is a compound capable of having a dynamic contact angle hysteresis of 20 ° or less.
Specifically, the fluorine-containing compound is preferably a compound having a perfluoropolyether group.

Examples of the perfluoropolyether group include-(OCF ₂ ) _n1 -,-(OC ₂ F ₄ ) _{n 2} -,-(OC ₃ F ₆ _{) n 3} -,-(OC ₄ F ₈ ) _n4- , and these. Examples include two or more linked groups. In addition, n1 to n4 each independently represent an integer of 1 or more, and 20 to 200 is preferable, and 30 to 200 is more preferable. However, when the fluorine-containing compound contains-(OCF ₂ ) _n1 -,-(OC ₂ F ₄ ) _n ₂ -,-(OC ₃ F ₆ ) n 3-, or-(OC ₄ F ₈ ) _{n 4-} , n1 , N2, n3, or n4 represent an integer greater than or equal to 2.
The barfluoro group at − (OC ₃ F ₆ ) _n3 − and − (OC ₄ F ₈ ) _n4 − may be a straight chain or a branched chain, and is preferably a straight chain.

Further, the fluorine-containing compound is preferably a compound having a hydrolyzable group or a Si atom-containing group to which a hydroxyl group is bonded (that is, a silicon-containing compound) in addition to the perfluoropolyether group.
As the hydrolyzable group or the Si atom-containing group to which a hydroxyl group is bonded, a group represented by −Si ( ^Ra ) _m (R ^b ) _3-m is preferable. R ^a represents a hydroxyl group or a hydrolyzable group, R ^b represents a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, or −Y—Si (R ^c ) _p (R ^d ) _3-p , and m Represents an integer of 1 to 3. Here, Y is a divalent organic group, ^{R c} has the same meaning as ^{R a,} ^{R d} have the same meanings as ^{R b,} p is an integer of 0-3.
Examples of the hydrolyzable group include a group that imparts a hydroxy group (silanol group) by hydrolysis. Specifically, an alkoxy group having 1 to 6 carbon atoms, a cyano group, an acetoxy group, a chlorine atom, and an isocyanate group. And so on. Among them, as the hydrolyzable group, an alkoxy group having 1 to 6 carbon atoms (more preferably 1 to 4) or a cyano group is preferable, and an alkoxy group having 1 to 6 carbon atoms (more preferably 1 to 4) is more preferable. ..
Examples of the divalent organic group represented by Y include an alkylene group, a group in which an alkylene group and an ether bond (—O—) are combined, and a group in which an alkylene group and an arylene group are combined.

For details of the fluorine-containing compound, see the fluorine-containing silane compound described in paragraphs 0033 to 0103 of JP-A-2015-200884, and the formulas (1a), The description of the compound (perfluoropolyether-based compound) represented by 1b), (2a), (2b), (3a), or (3b) can be referred to, and these contents are incorporated in the present specification.

As the fluorine-containing compound having a perfluoropolyether group, a commercially available product may be used. Specifically, as a composition (for example, a coating agent) containing a fluorine-containing compound having a perfluoropolyether group, Daikin Industries, Ltd. Examples thereof include "Optur DSX", "Optur DSX-E" and "Optur UD100" from Shinetsu Chemical Industry Co., Ltd., and "KY-164" and "KY-108" from Shinetsu Chemical Industry Co., Ltd.

-surface treatment-
For the surface treatment using the fluorine-containing compound, for example, the following method is used.
That is, the fluorine-containing compound is applied to the surface-treated portion of the die head (specifically, the region where the dynamic contact angle hysteresis is 20 ° or less, such as the land surface 10A and the contact portion 20 Cz with the coating liquid). After applying, it is dried and cured.
Examples of the means for applying the fluorine-containing compound include brush coating, dip coating, and spray coating.

-Preparation-
Before the surface treatment using the fluorine-containing compound, the dynamic contact angle hysteresis of the surface-treated portion of the die head (specifically, the land surface 10A, the contact portion 20 Cz with the coating liquid, etc.) is set to 20 ° or less. It is preferable to perform pretreatment on the area to be treated.
Examples of the pretreatment include acid treatment, alkali treatment, primer treatment, rough surface treatment, surface modification treatment such as plasma, and the like.

The surface-treated layer preferably has a ten-point average roughness Rzjis of 2.0 or less, more preferably 1.5 μm or less, and even more preferably 1.0 μm or less. The lower limit of the ten-point average roughness Rzjis of the surface-treated layer is, for example, 0.001 μm or more from the viewpoint of the measurement limit.
Here, the ten-point average roughness Rzjis is a value measured by the method described in JIS B 0601-2001. As the measuring device, for example, a stylus type surface roughness measuring machine (Surfcom, Tokyo Seimitsu Co., Ltd.) is used.

Next, the base material to be coated by the die head, the means for transporting the base material, and the coating liquid will be described.

[Base material]
The base material F is not particularly limited as long as it is a member to be coated, and may be appropriately selected depending on the use of the coating layer. For example, when continuous coating is performed by the die head of the present disclosure, a long base material may be used. In particular, from the viewpoint of transportability and the like, a polymer film is preferably used as the base material.

For optical film applications, the light transmittance of the base material is preferably 80% or more.
For optical film applications, when a polymer film is used as the base material, it is preferable to use an optically isotropic polymer film.
Examples of the base material include a polyester-based base material (film or sheet of polyethylene terephthalate, polyethylene naphthalate, etc.), a cellulose-based base material (film or sheet of diacetyl cellulose, triacetyl cellulose (TAC), etc.), and a polycarbonate-based base material. , Poly (meth) acrylic base material (film or sheet such as polymethyl methacrylate), polystyrene base material (film or sheet such as polystyrene, acrylonitrile styrene copolymer), olefin base material (polyethylene, polypropylene, cyclic or Polyamide having a norbornene structure, film or sheet of ethylene-propylene copolymer, etc.), polyamide-based substrate (film or sheet of polyvinyl chloride, nylon, aromatic polyamide, etc.), polyimide-based substrate, polysulfone-based substrate, poly Ethersulfone-based base material, polyether ether ketone-based base material, polyphenylene sulfide-based base material, vinyl alcohol-based base material, polyvinylidene chloride-based base material, polyvinyl butyral-based base material, poly (meth) acrylate-based base material, polyoxy Examples thereof include a transparent base material such as a methylene-based base material and an epoxy resin-based base material, and a base material made of a blended polymer blended with the above polymer materials.

The base material may be one in which a layer is formed in advance on the above polymer film.
Examples of the layer formed in advance include an adhesive layer, a barrier layer against water, oxygen and the like, a refractive index adjusting layer, an alignment layer and the like.

[Means for transporting base material]
In FIGS. 1 and 2, the base material F is transported in the transport direction X, but the means for transporting the base material is not limited to this embodiment.
That is, the means for transporting the base material is not particularly limited, and for example, the base material can be transported in a stretched state, and the transport means at the time of coating by the die head is a backup roll from the viewpoint of improving the coating accuracy. Is preferable.
That is, the coating liquid is preferably applied to the base material wound on the backup roll by the die head.

The backup roll is a member that is rotatably configured and can be continuously transported by winding the base material, and rotationally drives the transport speed of the base material at the same speed.

The backup roll may be heated from the viewpoint of suppressing brushing of the coating film due to a decrease in the film surface temperature (that is, whitening of the coating film due to the occurrence of fine dew condensation) in order to enhance the drying promotion of the coating film. ..
Further, it is preferable that the backup roll detects the surface temperature and the surface temperature of the backup roll is maintained by the temperature control means based on the temperature.
The temperature control means of the backup roll includes a heating means and a cooling means. As the heating means, induction heating, water heating, oil heating and the like are used, and as the cooling means, cooling with cooling water is used.

The diameter of the backup roll is preferably 100 mm to 1000 mm, more preferably 100 mm to 800 mm, further preferably 200 mm to 700 mm, from the viewpoint of easy wrapping of the base material, easy application by the die head, and the manufacturing cost of the backup roll. preferable.

The transport speed of the base material on the backup roll is preferably, for example, 10 m / min to 100 m / min from the viewpoint of ensuring productivity and coatability.

The lap angle of the base material with respect to the backup roll is preferably 60 ° or more, more preferably 90 ° or more, from the viewpoint of stabilizing the transport of the base material during coating and suppressing the occurrence of uneven thickness of the coating film. The upper limit of the lap angle can be set to, for example, 180 °.
The lap angle refers to an angle including a transport direction of the base material when the base material comes into contact with the backup roll and a transport direction of the base material when the base material is separated from the backup roll.

[Coating liquid]
The coating liquid is not particularly limited as long as it can be discharged by the die head.
Since the die head of the present disclosure suppresses the generation of coating streaks, its effect is remarkably exhibited by applying it particularly when forming a coating film having a thin layer (for example, a wet thickness of 20 μm or less).

The coating liquid applied to the die head of the present disclosure is not particularly limited as long as it is a fluid liquid material.
The coating liquid may be a curable coating liquid containing a polymerizable or crosslinkable compound, or may be a non-curable coating liquid.

Further, in the case of a coating liquid containing an organic solvent, coating streaks tend to occur easily. Therefore, when a coating liquid containing an organic solvent is applied to the die head of the present disclosure, the effect of suppressing the occurrence of coating streaks is likely to appear.
The organic solvent used in the coating liquid is not particularly limited as long as it is an organic solvent capable of dissolving or dispersing the components contained in the coating liquid.
The content of the organic solvent is not particularly limited.

(Example of coating liquid)
The coating liquid applied to the die head of the present disclosure is not particularly limited as long as it is a fluid liquid material. However, when a coating liquid in which coating streaks are likely to occur is used, the effect is remarkably exhibited by using the die head of the present disclosure.

One example of the coating liquid is a coating liquid that forms an optically anisotropic layer, and is, for example, one kind or two or more kinds of polymerizable liquid crystal compounds, a polymerization initiator, a leveling agent, an organic solvent, and the like. Examples thereof include a coating liquid containing 20% by mass to 40% by mass of a solid content concentration. This coating liquid may further contain a liquid crystal compound other than the polymerizable liquid crystal compound, an orientation control agent, a surfactant, a tilt angle control agent, an orientation aid, a plasticizer, a cross-linking agent, and the like.

Another example of the coating liquid is a coating liquid that forms a polarizing layer, for example, a liquid crystal polymer, a dichroic compound, and an organic solvent that dissolves the liquid crystal polymer and the dichroic compound. Examples thereof include a coating liquid containing 1% by mass to 7% by mass of a solid content. This coating liquid may further contain an interface improver, a polymerization initiator, various additives and the like.

Yet another example of the coating liquid is a coating liquid that forms a hard coat layer, for example, a polymerizable compound (preferably a polyfunctional polymerizable compound), inorganic particles (preferably silica particles), and polymerization. Examples thereof include a coating liquid containing an initiator and an organic solvent and having a solid content concentration of 40% by mass to 60% by mass. This coating liquid may further contain a monomer, various additives, and the like.

Yet another example of the coating liquid is a coating liquid that forms an alignment layer, which contains, for example, polyvinyl alcohol (preferably modified polyvinyl alcohol having an acryloyl group), water, and an organic solvent, and is solid. Examples thereof include a coating liquid having a component concentration of 1% by mass to 10% by mass. This coating liquid may further contain a cross-linking agent or the like.

(Target coating layer)
The target coating layer formed from the coating liquid is not particularly limited, and examples thereof include a hard coat layer, an optically anisotropic layer, a polarizing layer, and a refractive index adjusting layer in the case of an optical film application. ..
The thickness of the layer formed from the coating liquid varies depending on the application, but can be, for example, 5 μm or less, more preferably 0.1 μm to 100 μm.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded.

<Preparation of base material>
As a base material, a long triacetyl cellulose (TAC) film (TD40UL, FUJIFILM Corporation, refractive index 1.48) having a thickness of 60 μm and a width of 1340 mm was prepared.

<Preparation of coating liquid>
(Preparation of coating liquid A)
The following components were mixed to prepare a coating liquid A.
-The following polymerizable liquid crystal compound L-9: 47.50 parts by mass-The following polymerizable liquid crystal compound L-10: 47.50 parts by mass-The following polymerizable liquid crystal compound L-3: 5.00 parts by mass-The following polymerization initiator PI-1: 0.50 parts by mass, the following leveling agent T-1 (weight average molecular weight: 10,000): 0.20 parts by mass, methyl ethyl ketone: 235.00 parts by mass

In the above-mentioned polymerizable liquid crystal compound L-9 and the above-mentioned polymerizable liquid crystal compound L-10, ^one of R ^{1 and R 2} represents a methyl group and the other represents a hydrogen atom, and R ³ and R ⁴ represent one of them. Represents a methyl group and the other represents a hydrogen atom. That is, the polymerizable liquid crystal compound L-9 and the polymerizable liquid crystal compound L-10 are mixtures of positional isomers having different methyl group positions.

In the above polymerizable liquid crystal compounds L-9 and L-10, the group adjacent to the methacryloyl group represents a divalent group in which an ethylene group is replaced with a methyl group. The polymerizable liquid crystal compounds L-9 and L-10 are mixtures of positional isomers having different methyl group substitution positions, respectively.

(Preparation of coating liquid B)
The following components were mixed to prepare a coating liquid B.
The following liquid crystal polymer LP1: 4.011 parts by mass (weight average molecular weight: 13,300, structural unit (1) and structural unit (2) in the molecule 80:20 [(1) :( 2); mass Ratio].)
The following bicolor compound D1: 0.792 parts by mass The following bicolor compound D2: 0.963 parts by mass The following interface improver F2: 0.087 parts by mass The following interface improver F3: 0.073 parts by mass The following interface improver F4 (weight average molecular weight: 10,000): 0.073 parts by mass tetrahydrofuran (organic solvent having a boiling point of 80 ° C. or less): 37.6004 parts by mass Cyclopentanone: 56.4006 parts by mass

(Preparation of coating liquid C)
500 parts by mass of IPA (isopropanol), 750 parts by mass of partially caprolactone-modified polyfunctional acrylate (KAYARAD DPCA-20, Nippon Kayaku Co., Ltd.), silica sol (MIBK-ST, Nissan Chemical Industry Co., Ltd.) with respect to 500 parts by mass of methyl ethyl ketone. Co., Ltd.) 200 parts by mass and 50 parts by mass of a photopolymerization initiator (Omnirad 184 (formerly Irgacure 184) and IGM Resins VV) were added to prepare a coating liquid C.

(Preparation of coating liquid D)
Glutaraldehyde (crosslinking agent): 1 part by mass, water: 378 parts by mass, methanol: 120 parts by mass are mixed with 20 parts by mass of the following modified polyvinyl alcohol (PVA, degree of polymerization 1,000): coating liquid. D was prepared.

In the above (PVA), the numerical value added to each structural unit of the main chain is the molar ratio.

<Preparation of die head 1>
Using stainless steel (SUS630), a die head 100A having the same configuration as that shown in FIG. 1 was produced.
In the die head 100A shown in FIG. 1, the land surface 10A of the upstream lip 10, the surface 20C of the downstream lip 20, and the surface corresponding to the land surface 20A of the downstream lip 20 were surface-treated by the following method. ..
First, a 0.1% by mass NaOH aqueous solution was attached, and then the preparation was carried out by drying.
Then, surface treatment was performed using MX-031 of Surf Industry Co., Ltd.
With respect to the surface-treated layer formed as described above, the dynamic contact angle hysteresis by methyl ethyl ketone was measured by the method described above and found to be 18 °.
The Rzjis of the surface-treated layer was measured by the method described above and found to be 1.1 μm.

<Preparation for die head 2>
Similar to the die head 1, stainless steel (stainless steel, except that the grinding finish conditions for the land surface 10A of the upstream lip 10 and the surface 20C of the downstream lip 20 and the surface corresponding to the land surface 20A of the downstream lip 20 were changed. A die head 100A having the configuration shown in FIG. 1 using SUS630) was produced.
Then, the die head 2 was obtained by performing a pretreatment and a surface treatment in the same manner as the die head 1.
When the dynamic contact angle hysteresis by methyl ethyl ketone was measured for the surface-treated layer of the die head 2 by the method described above, it was 15 °.
The Rzjis of the surface-treated layer was measured by the method described above and found to be 0.9 μm.

<Preparation of die head 3>
Using stainless steel (SUS630), a die head 100B having the same configuration as in FIG. 2 was produced.
In the die head 100B shown in FIG. 2, the land surface 10A of the upstream lip 10, the surface 20C of the downstream lip 20, the land surface 20A of the downstream lip 20, and the land surface 40A of the intermediate lip 40 are surfaced by the following method. Processing was performed.
First, a 0.1% by mass NaOH aqueous solution was attached, and then the preparation was carried out by drying.
Then, surface treatment was performed using MX-031 of Surf Industry Co., Ltd.
With respect to the surface-treated layer formed as described above, the dynamic contact angle hysteresis by methyl ethyl ketone was measured by the method described above and found to be 18 °.
The Rzjis of the surface-treated layer was measured by the method described above and found to be 1.1 μm.

<Preparation of die head 4>
In the die head 1, the die head 4 was produced in the same manner as the die head 1 except that the pretreatment and the surface treatment were changed to the following methods.
That is, in the die head 100A having the same configuration as that of FIG. 1, the surface corresponding to the land surface 10A of the upstream lip 10, the surface 20C of the downstream lip 20, and the land surface 20A of the downstream lip 20 is opposed to the tetrafluoroethylene of DuPont. Fluororesin coating was performed using an ethylene resin.
When the dynamic contact angle hysteresis by methyl ethyl ketone was measured on the surface coated with the fluororesin as described above by the method described above, it was 21 °.
Further, the Rzjis of the fluororesin-coated surface was measured by the method described above and found to be 1.1 μm.

<Preparation of die head 5>
In the die head 1, the die head 5 was produced in the same manner as the die head 1 except that the pretreatment and the surface treatment were changed to the following methods.
That is, in the die head 100A having the same configuration as that of FIG. 1, the surfaces corresponding to the land surface 10A of the upstream lip 10 and the land surface 20C of the downstream lip 20 and the land surface 20A of the downstream lip 20 are subjected to nickel by electroless plating. And a composite plating layer of polytetrafluoroethylene was formed.
With respect to the composite plating layer formed as described above, the dynamic contact angle hysteresis by methyl ethyl ketone was measured by the method described above and found to be 40 °.
Further, the Rzjis of the composite plating layer was measured by the method described above and found to be 1.1 μm.

<Preparation of die head 6>
Using stainless steel (SUS630), a die head 100C having the same configuration as in FIG. 3 was produced.
In the die head 100C shown in FIG. 3, the land surface 10A of the upstream lip 10, the surface 50C of the downstream lip 50, and the surface corresponding to the land surface 50A of the downstream lip 50 were surface-treated by the following method. .. As the downstream lip 50, a lip 50 having a convex curved surface having a radius of curvature of 0.1 mm was used at a portion of the surface 50C connected to the land surface 50A of the contact portion 50Cz.
First, a 0.1% by mass NaOH aqueous solution was attached, and then the preparation was carried out by drying.
Then, surface treatment was performed using MX-031 of Surf Industry Co., Ltd.
With respect to the surface-treated layer formed as described above, the dynamic contact angle hysteresis by methyl ethyl ketone was measured by the method described above and found to be 18 °.
The Rzjis of the surface-treated layer was measured by the method described above and found to be 1.1 μm.

<Preparation of die head 7>
In the die head 6, the die head 7 was produced in the same manner as the die head 6 except that the downstream lip having the following shape was subjected to the above surface treatment.
That is, as the downstream lip 50, a lip 50 having a convex curved surface having a radius of curvature of 0.2 mm was used at a portion of the surface 50C connected to the land surface 50A of the contact portion 50Cz.
With respect to the surface-treated layer formed as described above, the dynamic contact angle hysteresis by methyl ethyl ketone was measured by the method described above and found to be 18 °.
The Rzjis of the surface-treated layer was measured by the method described above and found to be 1.1 μm.

(Example 1)
The die head 1 was arranged as shown in FIG. 1, and the coating liquid A was continuously applied onto the TAC film to form a coating film having a thickness of 3 μm and a width of 200 mm.
Specifically, the TAC film was conveyed on a backup roll having a surface temperature of 60 ° C. and an outer diameter of 300 mm, and the coating liquid A was applied to the base material on the backup roll using the die head 1. At this time, the lap angle of the TAC film was 150 °, and the transport speed of the TAC film was 30 m / min.
Further, the distance between the land surface 10A of the upstream lip 10 of the die head 1 and the base material (TAC film) F is 100 μm, and the distance between the land surface 20A of the downstream lip 20 and the base material (TAC film) F is 100 μm. Met.
Here, the coating film was formed in an environment of 23 ° C. and 50% RH.

(Example 2)
A coating film having a thickness of 0.5 μm was formed with a width of 200 mm in the same manner as in Example 1 except that the coating liquid A was replaced with the coating liquid B.

(Example 3)
A coating film having a thickness of 5 μm was formed with a width of 200 mm in the same manner as in Example 1 except that the coating liquid A was replaced with the coating liquid C.

(Example 4)
A coating film having a thickness of 1 μm was formed with a width of 200 mm in the same manner as in Example 1 except that the coating liquid A was replaced with the coating liquid D.

(Example 5, Comparative Examples 1 and 5)
A coating film having a thickness of 3 μm was formed with a width of 200 mm in the same manner as in Example 1 except that the die head 1 was replaced with the die heads 2, 4 or 5.

(Example 6, Comparative Examples 2 and 6)
A coating film having a thickness of 0.3 μm was formed with a width of 200 mm in the same manner as in Example 2 except that the die head 1 was replaced with the die heads 2, 4 or 5.

(Example 7, Comparative Examples 3 and 7)
A coating film having a thickness of 5 μm was formed with a width of 200 mm in the same manner as in Example 3 except that the die head 1 was replaced with the die heads 2, 4 or 5.

(Example 8, Comparative Examples 4 and 8)
A coating film having a thickness of 1 μm was formed with a width of 200 mm in the same manner as in Example 4 except that the die head 1 was replaced with the die heads 2, 4 or 5.

(Example 9)
The die head 3 was arranged as shown in FIG. 2, and the coating liquid A and the coating liquid A were continuously coated on the TAC film to form a coating film having a total thickness of 30 μm (upper layer 5 μm, lower layer 25 μm) with a width of 200 mm.
Specifically, the TAC film was conveyed on a backup roll having a surface temperature of 60 ° C. and an outer diameter of 300 mm, and the coating liquid A was applied to the base material on the backup roll using a die head. At this time, the lap angle of the TAC film was 150 °, and the transport speed of the TAC film was 30 m / min.
Further, the distance between the land surface 10A of the upstream lip 10 of the die head 3 and the base material (TAC film) F is 100 μm, and the distance between the land surface 20A of the downstream lip 20 and the base material (TAC film) F is 120 μm. The distance between the land surface 40A of the intermediate lip 40 and the base material (TAC film) F was 70 μm.

(Examples 10 and 12)
A coating film having a thickness of 3 μm was formed with a width of 200 mm in the same manner as in Example 1 except that the die head 1 was replaced with the die head 6 or 7 shown in Table 1 below.

(Examples 11 and 13)
A coating film having a thickness of 0.5 μm was formed with a width of 200 mm in the same manner as in Example 2 except that the die head 1 was replaced with the die head 6 or 7 shown in Table 1 below.

(Observation: Confirmation of three-phase interface)
The land surface 10A of the upstream lip 10 and the downstream lip 20 when the coating is applied on a transparent glass roll provided with a camera in the same manner as in each of the above examples. Surface 20C was observed with a camera inside the transparent roll.
If the land surface 10A of the upstream lip 10 and the surface 20C of the downstream lip 20 are once covered with the coating liquid, the covered area is exposed again, and a three-phase interface is formed as a solid surface. , It was judged that there was a three-phase interface.
The results are shown in Table 1.

(Evaluation: Evaluation of coating streaks)
Observe the shape of the bead during coating in each of the above examples from the front side (that is, the surface 10C side of the upstream lip 10) and the back side (that is, the surface 20C side of the downstream lip 20). At the same time, the formed coating film (size of width 200 mm × length 5000 mm) is placed on a light table, exposed to transmitted light, and visually observed for the presence or absence of repeated shades or shades of the bead. The coating streaks were evaluated by associating the observation results of the shape with the uneven film thickness indicated by the shading.
With respect to the transport direction of the base material, the coating streaks 1 caused by the lip on the most upstream side were used, and the coating streaks 2 caused by the lip on the most downstream side were used.
The evaluation of the coating streaks was performed on the sample 1 in which the coating film formed 5 minutes after the start of coating was cut out to the above size, and the sample 2 in which the coating film formed 2 hours after the start of coating was cut out to the above size. I went about two of them. The former was designated as "application streaks after 5 minutes", and the latter was designated as "application streaks after 2 hours".
The evaluation indexes are as follows. The results are shown in Table 1.

-Evaluation index of coating streaks-
1: No coating streaks are seen.
2: The coating streaks were observed to be extremely weak.
3: Clear application streaks were observed with 1 or more and less than 5 streaks.
4: Five or more clear coating streaks were observed on the entire surface.

As shown in Table 1, it can be seen that in each of the coating films formed by the examples, the generation of the coating streaks 1 and the coating streaks 2 is suppressed.
This will be described more specifically.
According to a coating film formed by using a die head having a dynamic contact angle hysteresis value of 21 ° or 40 ° on the land surface 10A of the upstream lip 10 and the surface 20C of the downstream lip 20, that is, Comparative Examples 1 to 8. In the formed coating film, coating streaks due to the lip on the most upstream side with respect to the transport direction of the base material were observed in all of the coating liquids A to D. Similarly, in the coating films formed in Comparative Examples 1 to 8, in all of the coating liquids A to D, coating streaks caused by the lip on the most downstream side with respect to the transport direction of the base material were also observed.
On the other hand, a coating film formed by using a die head having a dynamic contact angle hysteresis value of 18 ° or 15 ° on the land surface 10A of the upstream lip 10 and the surface 20C of the downstream lip 20, that is, Example 1. In the coating films formed by 9 to 9, no coating streaks due to the lip on the most upstream side with respect to the transport direction of the base material were observed in all of the coating liquids A to D. Similarly, in the coating films formed in Examples 1 to 9, in all of the coating liquids A to D, no coating streaks due to the lip on the most downstream side with respect to the transport direction of the base material were observed.

As shown in Table 1, in Examples 10 to 13, it can be seen that the occurrence of the coating streaks 1 and the coating streaks 2 is suppressed even after 2 hours. In particular, it can be seen that the occurrence of the coating streaks 1 and the coating streaks 2 after 2 hours is effectively suppressed by setting the radius of curvature of the curved surface of the downstream lip 50 to 0.2 mm or more.

The disclosures of Japanese patent application 2019-180291 filed on September 30, 2019 and Japanese patent application 2020-039221 filed on March 6, 2020 are incorporated herein by reference in their entirety.

10 Upstream lip 10A Upstream lip land surface 10B Upstream lip slot formation surface 10C Upstream lip slot formation surface Opposite

surface

20, 50

Downstream lip

20A, 50A Downstream

lip land surface

20B, 50B Downstream lip

slot forming surface

20C, 50C Downstream lip slot forming surface opposite to the slot forming surface (that is, the outer peripheral surface)
20Cz, 50Cz Contact part with

coating liquid

30, 30a, 30b Slot 40 Intermediate lip 40A Land surface of intermediate lip 40B ₁ , 40B ₂ Slot forming surface of

intermediate lip

100A, 100B, 100C Die head F base material (example of member to be coated) )
L, L ₁ , L ₂ Coating liquid X Substrate transfer direction B bead

Claims

It has two or more lips in parallel and a slot formed between adjacent lips to transfer and discharge the coating liquid.
At least one of the land surface of the lip at one end in the parallel direction and the outer surface of the lip at the other end in the parallel direction connected to the land surface on the side opposite to the slot forming surface has a dynamic contact angle hysteresis of 20 ° or less due to methyl ethyl ketone. Is a die head.
The die head according to claim 1, wherein the land surface of the lip at one end in the parallel direction and the outer surface of the lip at the other end in the parallel direction have a ten-point average roughness Rzjis of 1.0 μm or less.
The die head according to claim 1 or 2, wherein the dynamic contact angle hysteresis due to the methyl ethyl ketone on the land surface of the lip at the other end in the parallel direction is 20 ° or less.
Of the land surface of the lip at one end in the parallel direction and the outer surface of the lip at the other end in the parallel direction, a surface having a dynamic contact angle hysteresis of 20 ° or less due to the methyl ethyl ketone is formed by using a fluorine-containing compound. The die head according to any one of claims 1 to 3, further comprising a surface-treated layer.
The die head according to claim 4, wherein the fluorine-containing compound is a compound having a perfluoropolyether group.
The die head according to any one of claims 1 to 5, wherein the lip at the other end in the parallel direction has a curved surface at a portion connected to the land surface on the outer surface in a side view.
The die head according to claim 6, wherein the curved surface of the lip at the other end in the parallel direction is a curved surface having a radius of curvature of 0.2 mm or more.
Any of claims 1 to 7, wherein at the time of coating, the lip at one end in the parallel direction is located on the downstream side with respect to the coating direction, and the lip at the other end in the parallel direction is located on the upstream side with respect to the coating direction. The die head according to item 1.