JP7266746B2 - die head - Google Patents

Description

The present disclosure relates to die heads.

For example, in a method of forming a coating layer on an object to be coated (for example, a substrate), a coating device equipped with a die head is used. A die head is a member that ejects a material that forms a coating layer.

Japanese Unexamined Patent Application Publication No. 2002-248399 discloses manufacturing of a coating member in which a coating liquid ejection port is formed between a pair of lip tip portions and a coating film is formed on the surface of a member to be coated that moves relative to the ejection port. A manufacturing apparatus for a coating member is disclosed in which the tip of the downstream lip located on the coating film formation side has a larger contact angle with water than the tip of the upstream lip.

Japanese Patent Application Laid-Open No. 2016-068047 discloses a die coater used for forming a transparent conductive layer by coating a transparent conductive layer-forming coating liquid containing at least a metal material on a transparent substrate, wherein the transparent A die head that discharges a conductive layer-forming coating liquid, a coating liquid tank that stores the transparent conductive layer-forming coating liquid, and a liquid feeding path that feeds the transparent conductive layer-forming coating liquid from the coating liquid tank to the die head. and the die head has a liquid-repellent area formed at least on the surface located in the direction opposite to the coating direction.

A problem to be solved by one aspect of the present disclosure is to provide a die head that allows quick application and can suppress the occurrence of coating defects.
Here, "quick coating" means that in coating using a die head, it takes a short time to form a coating film on the object to be coated to a width corresponding to the slot width of the die head. .

The present disclosure includes the following aspects.
<1> having at least two lips arranged in parallel and defining a slot for transferring and discharging the coating liquid between adjacent lips;
The at least two lips are located at one end in the parallel direction of the lips, and have a land surface, a slot-forming surface connected to the land surface, and an outer surface connected to the land surface on the opposite side of the slot-forming surface. including a lip of
The dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface of the first lip is 20° or less,
A die head having a curved surface at a portion of the outer surface of the first lip connected to the land surface in a side view along the parallel direction.

<2> The die head according to <1>, wherein the curved surface of the first lip has a curvature radius of 0.5 mm or more.
<3> The die head according to <1> or <2>, wherein the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the curved surface of the first lip is 20° or less.
<4> The at least two lips are positioned at the other end in the parallel direction of the lips, and include a land surface, a slot-forming surface connected to the land surface, and an outer surface connected to the land surface on the opposite side of the slot-forming surface. a second lip having
The die head according to any one of <1> to <3>, wherein the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the outer surface is 20° or less.
<5> At least one surface selected from the group consisting of the land surface and the curved surface of the first lip, and the outer surface of the second lip has a ten-point average roughness Rzjis of 1.0 μm or less. The die head according to any one of <1> to <4>.
<6> Among the land surface and curved surface of the first lip and the outer surface of the second lip, the surface having a dynamic contact angle hysteresis of 20° or less for methyl ethyl ketone contains a fluorine-containing compound. The die head according to any one of <1> to <5>, comprising a surface layer.
<7> The die head according to <6>, wherein the fluorine-containing compound is a compound having a perfluoropolyether group.

According to one aspect of the present disclosure, there is provided a die head die head that can be applied quickly and can suppress the occurrence of coating defects.

It is a schematic side view which shows an example of the process which discharges a coating liquid from a die head. 1 is a schematic perspective view of a first embodiment of a die head according to the present disclosure; FIG. FIG. 4 is a schematic cross-sectional view showing an example of a coating layer forming process using the first embodiment of the die head according to the present disclosure; Fig. 2 is a schematic perspective view of a second embodiment of a die head according to the present disclosure; FIG. 5 is a schematic cross-sectional view showing an example of a coating layer forming process using the second embodiment of the die head according to the present disclosure;

Hereinafter, embodiments of the present disclosure will be described in detail. The present disclosure is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of the present disclosure.

When the embodiments of the present disclosure are described with reference to the drawings, descriptions of overlapping components and reference numerals in the drawings may be omitted. Components shown using the same reference numerals in the drawings mean the same components. The dimensional ratios in the drawings do not necessarily represent the actual dimensional ratios.

In the description of the embodiments of the present disclosure, one direction in the width direction of the die head is defined as direction X, one direction in the length direction of the die head is defined as direction Y, and one direction in the height direction of the die head is defined as direction Z. Direction X, direction Y, and direction Z are orthogonal to each other.

In the present disclosure, a numerical range indicated using "to" indicates a range including the numerical values described before and after "to" as lower and upper limits, respectively. In the numerical ranges described step by step in the present disclosure, upper or lower limits described in a certain numerical range may be replaced with upper or lower limits of other numerical ranges described step by step. In addition, in the numerical ranges described in the present disclosure, upper or lower limits described in a certain numerical range may be replaced with values shown in Examples.

In the present disclosure, the amount of each component in the composition means the total amount of the multiple substances present in the composition unless otherwise specified when there are multiple substances corresponding to each component in the composition. .

In the present disclosure, ordinal numbers (e.g., “first” and “second”) are terms used to distinguish between multiple components and limit the number of components and the relative superiority of components. isn't it.

In the present disclosure, the term "step" includes not only independent steps, but also if the intended purpose of the step is achieved even if it cannot be clearly distinguished from other steps. .

In the present disclosure, "% by mass" and "% by weight" are synonymous, and "parts by mass" and "parts by weight" are synonymous.

In the present disclosure, a combination of two or more preferred aspects is a more preferred aspect.

In the present disclosure, "(meth)acrylic" means acrylic, methacrylic, or both acrylic and methacrylic.

In the present disclosure, the term “solid content” refers to all components of an object excluding solvents (eg, water, organic solvents, etc.).

<Die head>
A die head according to the present disclosure has at least two lips arranged in parallel and defining a slot for transporting and discharging a coating liquid between adjacent lips,
The at least two lips are located at one end in the parallel direction of the lips, and have a land surface, a slot-forming surface connected to the land surface, and an outer surface connected to the land surface on the opposite side of the slot-forming surface. wherein the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface of the first lip is 20° or less, and when viewed from the side along the parallel direction, the outer surface of the first lip has a curved surface at a portion connected to the land surface in .
According to the die head according to the present disclosure, coating can be performed quickly and the occurrence of coating defects can be suppressed.

The reason why the die head according to the present disclosure has the above effect is presumed as follows.
Formation of a coating layer using a die head includes, for example, a step of discharging a coating liquid from a die head onto a continuously transported object to be coated. The coating liquid discharged from the die head forms a bead (also called liquid pool) between the tip of the die head and the object to be coated. Then, a part of the coating liquid forming the bead moves to the side of the object to be coated, thereby forming a coating film on the object to be coated. However, at the tip of the die head, particularly around the land surface of the lip, the coating liquid separated from the bead may remain partially in the length direction of the die head (that is, the coating width direction). When the coating liquid that has once stayed on the land surface moves toward the object to be coated, the amount of coating increases locally at the location where the coating liquid moves, resulting in uneven thickness of the coating film. The film thickness unevenness of the coating film that occurs here is, for example, a film that extends along the conveying direction of the object to be coated and has a width of 0.1 mm to 5 mm and a length of about 100 mm to 10000 mm. Thickness is uneven. A film thickness unevenness observed in such a size is referred to as a "coating defect" in the present disclosure.
The coating defects as described above appear conspicuously particularly in the case where the process of discharging the coating liquid from the die head is in the following manner.
That is, as shown in FIG. 1, the lateral side of the backup roll 200 is wound on the backup roll 200 and conveyed along the rotation of the backup roll in the direction of the arrow (that is, the object to be coated). In this embodiment, the coating liquid is discharged from the die head 100 arranged in the .
In this embodiment, before the start of coating (specifically, before the coating liquid comes into contact with the substrate F), the coating liquid dripping from the die head 10 is applied to the land surface of the upstream lip of the die head 10, etc. As a result, the contact surface of the upstream lip with the coating liquid is covered with the coating liquid. Therefore, the land surface of the upstream lip after the application is started and the bead is formed is also covered with the coating liquid or at least part of the coating liquid is dried. The coating liquid on the land surface or a film of the coating liquid that is at least partially dried has a composition close to that of the coating liquid that forms the beads, so it is very compatible, and the coating liquid is easily supplied from the beads due to surface tension flow. . Therefore, the coating liquid often stays on a part of the land surface of the upstream lip in the length direction, and the coating liquid remaining on the land surface of the upstream lip causes the coating defects described above.
Here, FIG. 1 is a schematic side view showing an example of the process of discharging the coating liquid from the die head.

Therefore, in the die head of the present disclosure, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface is set to 20° or less on the first lip located at one end in the lip parallel direction. Even if the land surface having a dynamic contact angle hysteresis of 20° or less for methyl ethyl ketone is covered with the coating liquid, the surface covered with the coating liquid is exposed again to form a three-phase interface. A three-phase interface is an interface composed of a solid (ie, land surface), a liquid (ie, a coating liquid forming a bead), and a gas (ie, air). Since such a three-phase interface is formed on the land surface of the first lip, the coating liquid separated from the bead is less likely to remain on the land surface and is more likely to separate.
In addition, in the die head of the present disclosure, the first lip has a land surface, a slot forming surface connected to the land surface, and an outer surface opposite to the slot forming surface and connected to the land surface. The part that connects with is curved. When the first lip is the upstream lip in the above-described aspect, if the part connected to the land surface on the outer surface of the first lip is a corner, due to this "corner" shape and the three-phase interface, The coating liquid separated from the bead may remain in this portion. As in the die head of the present disclosure, in the first lip as the upstream lip, by forming a curved surface at the portion connected to the land surface, the coating liquid separated from the bead is less likely to remain at the portion where the land surface and the outer surface are connected. You can also
From the above, according to the die head of the present disclosure, it is possible to reduce the coating liquid remaining on the land surface of the first lip, and as a result, it is presumed that the occurrence of coating defects is suppressed.

In the die head, when the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface of the upstream lip is 20° or less, the wettability of the coating liquid to the land surface is lower than when the dynamic contact angle hysteresis is greater than 20°. Therefore, it takes time for the bead to wet and spread in the length direction of the die head (that is, the coating width direction), and as a result, it takes a long time to apply the coating. In particular, as described above, when the coating liquid stays on the part where the land surface and the outer surface of the upstream lip are connected, this coating liquid inhibits the wetting and spreading of the bead in the length direction of the die head (that is, the coating width direction). This is thought to increase the application time.
In contrast, in the die head according to the present disclosure, in the first lip as the upstream lip, the portion connected to the land surface is curved, so that the coating liquid separated from the bead is connected to the land surface and the outer surface. It does not stay in the part and leaves the die head (specifically, the first lip) quickly. Therefore, according to the die head according to the present disclosure, as described above, the wetting and spreading of the bead in the length direction of the bead in the die head (that is, the coating width direction) is not hindered, so it is presumed that the coating is faster. be.

In the die heads described in JP-A-2002-248399 and JP-A-2016-068047, the dynamic contact angle hysteresis of the lip with respect to the land surface is not 20° or less, and the land surface once comes into contact with the coating liquid. Since the land surface is not exposed again, the above three-phase interface is not formed.

In the present disclosure, the “parallel direction of the lips” means the direction in which the plurality of lips constituting the die head are arranged.

[Preferred embodiment]
In the present disclosure, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface of the first lip is 20° or less, but the dynamic contact angle hysteresis of methyl ethyl ketone with respect to this land surface is preferably 18° or less, It is more preferably 16° or less. Although the lower limit of the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface of the first lip is not particularly limited, 1° is an example from the viewpoint of measurement limit.
When the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface of the first lip is 20° or less, it is possible to suppress the occurrence of coating defects due to the coating liquid separated from the bead remaining on the land surface. .
In addition, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface of the first lip is 20° or less, thereby suppressing the occurrence of coating streaks caused by deformation of the bead contacting the first lip side. can also
The term “coating streak” used herein refers to linear film thickness unevenness (i.e., streaks) extending along the conveying direction of the object to be coated, which appears singly or continuously in a plurality, and has a width of 0.1 mm. ~5 mm.

The dynamic contact angle hysteresis will be described in detail below.
Dynamic contact angle hysteresis refers to the difference (θa-θr) between the advancing contact angle (θa) and the receding contact angle (θr) when a droplet slides down the surface of a solid wall. In the present disclosure, droplets of methyl ethyl ketone are used as the droplets. The die head itself may be used as a solid wall. Also, a plate-like object having the same surface as the target surface (for example, land surface) may be used as the solid wall. The advancing contact angle (θa) and receding contact angle (θr) are measured by the sliding method. In the sliding method, a droplet is dropped onto the surface of a horizontally arranged solid wall, and then the solid wall is gradually tilted to reduce the advancing contact angle (θa) when the droplet starts sliding down. , and the receding contact angle (θr) are measured. The advancing contact angle (θa) is the contact angle on the downstream side in the sliding direction of the droplet. The receding contact angle (θr) is the contact angle on the upstream side in the sliding direction of the droplet. In the sliding down method, the advancing contact angle (θa) and the receding contact angle (θr) are measured under an environment of room temperature of 25° C. and humidity of 50%. The surface temperature of the solid wall is 25°C. The droplet temperature is 25°C. Drop volumes typically range from 1 μL to 4 μL. However, from the viewpoint of reproducing a situation close to the actual phenomenon, the droplet amount is not limited to the above numerical range.

In the die head according to the present disclosure, the curved surface on the outer surface of the first lip is preferably a curved surface with a radius of curvature of 0.3 mm or more, and more preferably a curved surface with a radius of curvature of 0.5 mm or more.
The upper limit of the radius of curvature of the curved surface is, for example, 10 mm.
That is, the curved surface of the outer surface of the first lip preferably has a radius of curvature of 0.3 mm to 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 determine the radius of curvature from the observed image.
The radii of curvature are obtained at 10 points on the curved surface, and the arithmetic average value at the 10 points is taken as the radius of curvature of the curved surface on the outer surface.

In addition, in the die head according to the present disclosure, from the viewpoint of making it difficult for the coating liquid separated from the bead to stay at the portion where the land surface and the outer surface are connected, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the curved surface on the outer surface of the first lip is preferably 20° or less.
Moreover, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the curved surface of the outer surface of the first lip is more preferably 18° or less, and even more preferably 16° or less. Also, the lower limit of the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the curved surface of the outer surface of the first lip is not particularly limited, but from the viewpoint of the measurement limit, 1° is an example.

The die head according to the present disclosure preferably has the following aspects.
That is, in the die head according to the present disclosure, at least two lips are positioned at the other end in the parallel direction of the lips, the land surface, the slot forming surface connected to the land surface, and the land on the side opposite to the slot forming surface. It preferably includes a second lip having an outer surface in contact with the surface, against which methyl ethyl ketone has a dynamic contact angle hysteresis of 20° or less.
Here, unless otherwise specified, "the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the outer surface of the second lip is 20° or less" means that methyl ethyl ketone It includes a dynamic contact angle hysteresis of 20° or less.
On the outer surface of the second lip, it is preferable that the region where the dynamic contact angle hysteresis of methyl ethyl ketone is 20° or less includes at least the region that contacts the coating liquid.
Hereinafter, in the die head according to the present disclosure, the area that comes into contact with the coating liquid is also referred to as the "liquid contact portion".

As described above, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the outer surface of the second lip is 20 ° or less, so that the generation of coating streaks caused by the shape of the bead in contact with the second lip collapses. can also be suppressed.
Moreover, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the outer surface of the second lip is more preferably 18° or less, and even more preferably 16° or less. In addition, the lower limit of the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the outer surface of the second lip is not particularly limited, but from the viewpoint of measurement limit, 1° is an example.

In the die head according to the present disclosure, from the viewpoint of further reducing the dynamic contact angle hysteresis of methyl ethyl ketone, at least one surface selected from the group consisting of the land surface and curved surface of the first lip and the outer surface of the second lip The ten-point average roughness Rzjis is preferably 2.0 or less, more preferably 1.5 μm or less, even more preferably 1.0 μm or less.
From the viewpoint of the measurement limit, the lower limit of the ten-point average roughness Rzjis of the surface is, for example, 0.001 μm or more.
Here, the ten-point average roughness Rzjis is measured by the method described in "JIS B 0601:2001". As a measuring device, a stylus-type surface roughness measuring machine (for example, Surfcom, Tokyo Seimitsu Co., Ltd.) is used.

In the die head according to the present disclosure, among the land surface and curved surface of the first lip and the outer surface of the second lip, the surface having a dynamic contact angle hysteresis of 20 ° or less for methyl ethyl ketone is a surface layer containing a fluorine-containing compound is preferably provided.
Moreover, it is preferable that the fluorine-containing compound contained in the surface layer is a compound having a perfluoropolyether group.
The details of the surface layer and the fluorine-containing compound contained in the surface layer will be described later.

[First embodiment]
A first embodiment of a die head according to the present disclosure will be described with reference to FIGS. 2 and 3. FIG. 2 is a schematic perspective view of a first embodiment of a die head according to the present disclosure; FIG. FIG. 3 is a schematic cross-sectional view showing an example of a coating layer forming process using the first embodiment of the die head according to the present disclosure.
In FIG. 3, the contact portion 20Cz is shown as if there is a step with respect to the surface 20C of the second lip 20, which is the downstream lip. 20Cz does not have a stepped configuration with respect to the surface 20C of the second lip 20 . The same applies to the contact portion 20Cz on the surface 20C of the second lip 20, which is the downstream lip shown in FIG. 5, which will be described later.

The die head 100A shown in FIGS. 2 and 3 is a die head for single layer coating. The die head 100A has a first lip 10 and a second lip 20. As shown in FIG.
In addition, in the coating layer forming process shown in FIG. 3, the first lip 10 corresponds to the upstream lip, and the second lip 20 corresponds to the downstream lip.

The die head 100A is made of metal.
Metals include, for example, stainless steel. Note that the die head 100A may be made of a plurality of metals. For example, in the die head 100A, the tip of the first lip 10 and the tip of the second lip 20 are made of a superfine alloy (eg, TF15, Mitsubishi Materials Corporation) or a cemented carbide (eg, Nippon Tungsten). Co., Ltd.), and portions other than the tip of the first lip 10 and the tip of the second lip 20 may be made of stainless steel.

[First lip 10]
The first lip 10 is the member which together with the second lip 20 defines the slot 30 .

As shown in FIGS. 2 and 3, the first lip 10 is arranged side by side in the direction X with the second lip 20 . That is, the first lip 10 is arranged at one end in the parallel direction of the lip.

The first lip 10 is made of the metal described above.

As shown in FIG. 2, the shape of the first lip 10 may be columnar with the direction Y as the length direction, and may have a recess for forming a manifold, which will be described later.

As shown in FIG. 3, the first lip 10 has a land surface 10A, a slotted surface 10B and an outer surface 10C.
Each surface constituting the first lip 10 will be described below.

(Land surface 10A)
As shown in FIG. 3, the land surface 10A faces the Z direction. The land surface 10A faces the surface of the substrate F, which is the object to be coated, during the process of discharging the coating liquid L from the die head 100A, for example.

The dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A is 20° or less. Since the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A is 20° or less, it is possible to suppress the occurrence of coating defects due to the coating liquid separated from the bead staying on the land surface 10A. The occurrence of coating streaks described above can also be suppressed.
The dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A is preferably 18° or less, more preferably 16° or less.
Although the lower limit of the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A is not limited, 1° is an example from the viewpoint of the measurement limit.

Land surface 10A has a surface layer containing a fluorine-containing compound.
According to the surface layer containing the fluorine-containing compound, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A can be 20° or less.

The type of fluorine-containing compound is not limited as long as it contains a fluorine atom in its molecule. The fluorine-containing compound is preferably a compound that can adjust the land surface 10A (specifically, the surface layer of the land surface 10A) so that the dynamic contact angle hysteresis due to methyl ethyl ketone is 20° or less.

The fluorine-containing compound is preferably a compound having a perfluoropolyether group. Examples of perfluoropolyether groups include -(OCF ₂ ) _n1 -, -(OC ₂ F ₄ ) _n2 -, -(OC ₃ F ₆ ) _n3 -, -(OC ₄ F ₈ ) _n4 -, and these is a group in which two or more are linked. n1 to n4 each independently represent an integer of 1 or more. n1 to n4 are each independently preferably 20 to 200, more preferably 30 to 200. provided that when the fluorine-containing compound contains -(OCF ₂ ) _n1 -, -(OC ₂ F ₄ ) _n2 -, -(OC ₃ F ₆ ) _n3 -, or -(OC ₄ F ₈ ) _n4 -, n1 , n2, n3, or n4 represent an integer of 2 or more. The perfluoro group in -(OC ₃ F ₆ ) _n3 - and -(OC ₄ F ₈ ) _n4 - may be linear or branched, preferably linear.

The fluorine-containing compound is preferably a compound having, in addition to a perfluoropolyether group, a hydrolyzable group or a group containing a silicon atom to which a hydroxy group is bonded.

A hydrolyzable group or a group containing a silicon atom bonded to a hydroxy group is preferably a group represented by —Si(R ^a ) _m (R ^b ) _3-m . In the group represented by —Si(R ^a ) _m (R ^b ) _3-m , R ^a represents a hydroxy group or a hydrolyzable group, R ^b is a hydrogen atom, and has 1 to 22 carbon atoms. represents an alkyl group or -Y-Si(R ^c ) _p (R ^d ) _3-p , where m represents an integer of 1-3; Y represents a divalent organic group, R ^c has the same definition as R ^a , R ^d has the same definition as R ^b , and p represents an integer of 0-3.

Hydrolyzable groups include, for example, groups that give hydroxy groups upon hydrolysis. A silanol group (Si—OH) is formed by converting a hydrolyzable group attached to a silicon atom into a hydroxy group by hydrolysis. Specific hydrolyzable groups include, for example, alkoxy groups having 1 to 6 carbon atoms, cyano groups, acetoxy groups, chlorine atoms, and isocyanate groups. The hydrolyzable group is preferably an alkoxy group having 1 to 6 carbon atoms (preferably 1 to 4) or a cyano group, and an alkoxy group having 1 to 6 carbon atoms (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, the fluorine-containing silane compound described in paragraphs 0033 to 0103 of JP-A-2015-200884, and the formulas (1a), (1b), ( The description of the compound represented by 2a), (2b), (3a), or (3b) (perfluoropolyether compound) can be referred to. The contents of these are incorporated herein by reference.

Fluorine-containing compounds may be commercially available. Commercially available compositions (eg, coating agents) containing fluorine-containing compounds include, for example, “Fluorine-based ultra-thin film coat MX-031” (Surf Industry Co., Ltd.). Examples of commercially available compositions (eg, coating agents) containing a fluorine-containing compound having a perfluoropolyether group include "Optool (registered trademark) DSX" (Daikin Industries, Ltd.) and "Optool DSX-E." (Daikin Industries, Ltd.), "Optool UD100" (Daikin Industries, Ltd.), "KY-164" (Shin-Etsu Chemical Co., Ltd.), and "KY-108" (Shin-Etsu Chemical Co., Ltd.). be done. These commercial products can be used as sources of fluorine-containing compounds.

A surface layer containing a fluorine-containing compound is formed, for example, by surface treatment using a fluorine-containing compound.
Examples of surface treatment methods include a method of applying a composition containing a fluorine-containing compound to the surface to be treated, then drying and curing the composition containing the fluorine-containing compound. Means for applying the composition containing a fluorine-containing compound include, for example, brush coating, dip coating, and spray coating.

Prior to the surface treatment using the fluorine-containing compound, the surface to be treated may be pretreated.
Pretreatment includes, for example, acid treatment, alkali treatment, primer treatment, surface roughening treatment, and surface modification treatment with plasma.

From the viewpoint of further reducing the dynamic contact angle hysteresis of methyl ethyl ketone, the ten-point average roughness Rzjis of the land surface 10A is preferably 2.0 μm or less, more preferably 1.5 μm or less, and more preferably 1.0 μm. More preferably:
From the viewpoint of the measurement limit, the lower limit of the ten-point average roughness Rzjis of the land surface 10A is, for example, 0.001 μm or more.
Here, the ten-point average roughness Rzjis of the land surface 10A may be the ten-point average roughness Rzjis of the above-described surface layer containing the fluorine-containing compound.

(Slot forming surface 10B)
The slot-forming surface 10B is the surface that defines the slot 30 together with the slot-forming surface 20B of the second lip 20 .

The slot forming surface 10B is connected to the land surface 10A on the side opposite to the outer surface 10C.
The slot forming surface 10B faces the slot forming surface 20B of the second lip 20. As shown in FIG.

The slot forming surface 10B is a surface extending in the Z direction.

(outer surface 10C)
The outer surface 10C is a surface that faces the opposite direction to the direction in which the slot forming surface 10B faces.

The outer surface 10C is connected to the land surface 10A on the side opposite to the slot forming surface 10B.

10 C of outer surfaces incline with respect to the direction Z in the front-end|tip part of 100 A of die heads.
Specifically, the outer surface 10C extends toward the slot forming surface 10B as it goes in the Z direction.

The outer surface 10C has a convex curved surface 12 at a portion connected to the land surface 10A in cross-sectional view as shown in FIG.
The convex curved surface 12 on the outer surface 10C is preferably an arc curved surface from the viewpoint of processing accuracy.
Further, as described above, the convex curved surface 12 on the outer surface 10C is preferably a curved surface with a curvature radius of 0.3 mm or more, more preferably a curvature radius of 0.5 mm or more.
The upper limit of the radius of curvature of the convex curved surface 12 is, for example, 10 mm.

As described above, the convex curved surface 12 on the outer surface 10C has a dynamic contact angle hysteresis of 20° or less due to methyl ethyl ketone from the viewpoint of making it difficult for the coating liquid separated from the bead to stay at the portion where the land surface and the outer surface are connected. is preferably

[Second lip 20]
The second lip 20 is the member that defines the slot 30 together with the first lip 10 .

As shown in FIGS. 2 and 3, the second lip 20 is arranged side by side with the first lip 10 in the X direction.

The second lip 20 is made of the metal described above.

As shown in FIG. 2, the shape of the second lip 20 may be columnar with the direction Y as the length direction, and may have a recess for forming a manifold, which will be described later.

As shown in FIG. 3, the second lip 20 has a land surface 20A, a slotted surface 20B and an outer surface 20C.
Each surface constituting the second lip 20 will be described below.

(Land surface 20A)
The land surface 20A is a surface facing the Z direction.
For example, the land surface 20A faces the surface of the substrate F, which is the object to be coated, in the process of discharging the coating liquid L from the die head 100A.

(Slot forming surface 20B)
The slot-forming surface 20B is the surface that defines the slot 30 together with the slot-forming surface 10B of the first lip 10 .

The slot forming surface 20B is connected to the land surface 20A on the side opposite to the outer surface 20C.
The slot-forming surface 20B faces the slot-forming surface 10B.

The slot forming surface 20B is a surface extending in the Z direction.

(outer surface 20C)
The outer surface 20C is a surface facing the opposite direction to the slot forming surface 20B.

The outer surface 20C is connected to the land surface 20A on the side opposite to the slot forming surface 20B.

20 C of outer surfaces incline with respect to the direction Z in the front-end|tip part of 100 A of die heads.
Specifically, the outer surface 20C extends toward the slot forming surface 20B as it goes in the Z direction.

As described above, the wetted portion 20Cz, which is a part of the outer surface 20C, preferably has a dynamic contact angle hysteresis of 20° or less due to methyl ethyl ketone from the viewpoint of suppressing the occurrence of coating streaks.
The dynamic contact angle hysteresis of methyl ethyl ketone with respect to the wetted portion 20Cz is preferably 18° or less, more preferably 16° or less.
The lower limit of the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the wetted portion 20Cz is not limited, but from the viewpoint of the limit of measurement, 1° can be mentioned.

The wetted part 20Cz preferably has a surface layer containing a fluorine-containing compound.
The surface layer containing a fluorine-containing compound is synonymous with the surface layer containing a fluorine-containing compound described in the section of the land surface of the "first lip 10", and preferred embodiments are also the same.
Also, the method of forming the surface layer containing the fluorine-containing compound is the same as the method described in the section "first lip 10".

[Slot 30]
The slot 30 is a space for transferring and discharging the coating liquid L. As shown in FIG.

A slot 30 is formed between the first lip 10 and the second lip 20 adjacent in the direction X. As shown in FIG.
Specifically, slot 30 is formed by slot-forming surface 10B of first lip 10 and slot-forming surface 20B of second lip 20 .

The slot 30 extends in the Z direction. In addition, in the die head 100A, the slot 30 communicates with the manifold 50. As shown in FIG.
The manifold 50 is a space extending along the length direction of the die head 100A (that is, the Y direction in FIG. 2), and spreads the coating liquid L supplied to the die head 100A in the coating width direction (that is, the length direction of the die head 100A). , Y direction in FIG. 2), and the coating liquid L is temporarily stored.
A manifold 50 is formed between the first lip 10 and the second lip 20 .

[how to use]
A method of using the die head 100A will be described below with reference to FIG.

As shown in FIG. 3, in the step of forming a coating layer using the die head 100A, the die head 100A applies the land surface 10A of the first lip 10 and the second lip to the substrate F, which is the object to be coated. 20 are arranged with the land surfaces 20A facing each other.
The die head 100A has a first lip 10 on the lateral side of the backup roll 200 as shown in FIG. is positioned upstream in the direction in which the substrate F is conveyed.

The distance between the land surface 10A of the first lip 10 and the substrate is not limited, and may be determined, for example, according to the viscosity of the coating liquid L and the thickness of the coating film to be formed.
The distance between the land surface 10A of the first lip 10 and the substrate F is, for example, in the range of 50 μm to 500 μm. The distance between the land surface 10A of the first lip 10 and the substrate F may be determined, for example, within the range of 100 μm to 300 μm. "Distance between land surface and substrate" refers to the shortest distance between the land surface and the substrate. The distance between the land surface and the substrate can be measured using, for example, a taper gauge.

The distance between the land surface 20A of the second lip 20 and the substrate F is not limited, and may be determined, for example, according to the viscosity of the coating liquid L and the thickness of the coating film to be formed.
The distance between the land surface 20A of the second lip 20 and the substrate F is, for example, in the range of 50 μm to 500 μm. The distance between the land surface 20A of the second lip 20 and the substrate F may be determined, for example, within the range of 100 μm to 300 μm. The distance between the land surface 20A of the second lip 20 and the substrate F may be the same as the distance between the land surface of the first lip and the substrate. The distance between the land surface 20A of the second lip 20 and the substrate F may be different than the distance between the land surface 10A of the first lip 10 and the substrate F.

The substrate F is transported in the direction X with respect to the die head 100A.

The coating liquid L supplied to the die head 100A is discharged through the slot 30. As shown in FIG.
The coating liquid L ejected from the die head 100A forms a bead B between the die head 100A and the substrate F. By discharging the coating liquid L from the die head 100A while continuously conveying the substrate F, the coating liquid L forming the bead B moves onto the substrate F to form a coating film on the substrate F. be able to.
After the coating film is formed on the base material F, the desired coating is formed on the base material F, which is the object to be coated, by passing through a process as necessary (for example, a drying process of the coating film, etc.). A layer is formed.

A method of forming a coating layer to which the die head 100A is applied will be described below. However, the method of forming the coating layer to which the die head 100A is applied is not limited to the following.

(Base material)
The type of base material is not limited, and may be appropriately selected, for example, from known base materials depending on the application. Examples of substrates include polyester-based substrates (e.g., polyethylene terephthalate and polyethylene naphthalate), cellulose-based substrates (e.g., diacetylcellulose and triacetylcellulose (TAC)), polycarbonate-based substrates, poly(meth ) Acrylic base material (e.g., polymethyl methacrylate), polystyrene base material (e.g., polystyrene, and acrylonitrile styrene copolymer), olefin base material (e.g., polyethylene, polypropylene, polyolefin having a cyclic structure, norbornene structure Polyolefin and ethylene propylene copolymer), polyamide base material (e.g., polyvinyl chloride, nylon, and aromatic polyamide), polyimide base material, polysulfone base material, polyethersulfone base material, polyether ether Ketone base material, polyphenylene sulfide base material, vinyl alcohol base material, polyvinylidene chloride base material, polyvinyl butyral base material, poly(meth)acrylate base material, polyoxymethylene base material, epoxy resin base material material, and a base material made of a blend polymer obtained by blending the above polymer material.

The substrate is preferably a polymer film from the viewpoint of transportability.

In the application of the optical film, the light transmittance of the substrate is preferably 80% or more. Moreover, when a polymer film is used as a substrate in the application of the optical film, the polymer film is preferably an optically isotropic polymer film.

The shape of the substrate is not restricted. The shape of the substrate may be, for example, a film or a sheet.

A layer may be formed in advance on the surface of the substrate. Examples of the above layers include adhesive layers, barrier layers, refractive index adjusting layers, and alignment layers. Barrier layers include, for example, barrier layers against water or oxygen.

(Conveying Means for Base Material)
The transport means for the substrate is not limited.
The means for conveying the base material is preferably a backup roll, for example, from the viewpoint that the base material can be conveyed in a stretched state and the coating accuracy is improved.

A backup roll is a rotatable member. The base material can be transported by rotating the backup roll. The backup roll can also be conveyed by winding the base material thereon.

The backup roll may be heated from the viewpoint of promoting drying of the coating film and suppressing brushing of the coating film due to a decrease in film surface temperature (that is, whitening of the coating film due to fine condensation).

The surface temperature of the backup roll is preferably controlled by temperature control means. More preferably, the surface temperature of the backup roll is controlled by temperature control means based on the detected surface temperature.

Examples of temperature control means include heating means and cooling means. In the heating means, for example, induction heating, water heating, or oil heating is used. In the cooling means, for example, cooling by cooling water is used.

The diameter of the backup roll is preferably 100 mm to 1,000 mm, more preferably 100 mm to 800 mm, from the viewpoints of easy winding of the base material, easy coating with a die head, and the production cost of the backup roll. More preferably, 200 mm to 700 mm is particularly preferred.

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

The wrap angle of the substrate with respect to the backup roll is preferably 60° or more, more preferably 90° or more, from the viewpoint of stabilizing the substrate transport during coating and suppressing the occurrence of uneven thickness of the coating film. preferable. Also, the upper limit of the wrap angle can be set to 180°, for example.
The wrap angle is an angle formed by the direction in which the substrate is conveyed when the substrate contacts the backup roll and the direction in which the substrate is conveyed when the substrate separates from the backup roll.

(Coating liquid)
The type of coating liquid is not limited as long as it is a fluid liquid.
The coating liquid may be, for example, a curable coating liquid containing a polymerizable or crosslinkable compound, or a non-curable coating liquid.

The coating liquid may contain an organic solvent. In general, when a coating liquid containing an organic solvent is used, coating streaks tend to occur. On the other hand, in the second lip of the die head according to the present disclosure, by setting the dynamic contact angle hysteresis of methyl ethyl ketone to the outer surface to 20 ° or less, the occurrence of coating streaks is suppressed even with a coating liquid containing an organic solvent. The effect is easy to appear.

The organic solvent may be any organic solvent that dissolves or disperses the components contained in the coating liquid. Moreover, the content of the organic solvent in the coating liquid is not limited.

An example of the coating liquid is a coating liquid for forming an optically anisotropic layer.
The coating liquid includes, for example, one or more polymerizable liquid crystal compounds, a polymerization initiator, a leveling agent, and an organic solvent, and has a solid content concentration of 20% by mass to 40% by mass. A coating liquid is mentioned. The coating liquid may further contain a liquid crystal compound other than the polymerizable liquid crystal compound, an alignment control agent, a surfactant, a tilt angle control agent, an alignment aid, a plasticizer, or a cross-linking agent.

Another example of the coating liquid is a coating liquid forming a polarizing layer.
The coating liquid includes, for example, a liquid crystalline polymer, a dichroic compound, and an organic solvent that dissolves the liquid crystalline polymer and the dichroic compound, and has a solid content concentration of 1% by mass to 7% by mass. A coating liquid is mentioned. The coating liquid may further contain an interface improver, a polymerization initiator, or various additives.

Still another example of the coating liquid is a coating liquid for forming a hard coat layer.
The coating liquid includes, for example, a polymerizable compound (preferably a polyfunctional polymerizable compound), inorganic particles (preferably silica particles), a polymerization initiator, and an organic solvent, and has a solid concentration of 40 mass. % to 60% by mass. The coating liquid may further contain monomers or various additives.

Still another example of the coating liquid is a coating liquid for forming an alignment layer.
Examples of the coating liquid include a coating liquid containing polyvinyl alcohol (preferably modified polyvinyl alcohol having an acryloyl group), water, and an organic solvent, and having a solid content concentration of 1% by mass to 10% by mass. be done. The coating liquid may further contain a cross-linking agent.

(Coating layer)
The type of coating layer formed on the article to be coated is not limited. Coating layers for use in optical films include, for example, a hard coat layer, an optically anisotropic layer, a polarizing layer, and a refractive index adjusting layer.

The thickness of the coating layer is not limited, and may be determined, for example, according to the application. The thickness of the coating layer may be, for example, in the range of 0.1 μm to 100 μm, preferably 5 μm or less (more preferably 0.1 μm to 5 μm).

<<Second Embodiment>>
Next, a second embodiment of the die head according to the present disclosure will be described with reference to FIGS. 4 and 5. FIG.
4 is a schematic perspective view of a second embodiment of a die head according to the present disclosure; FIG. FIG. 5 is a schematic cross-sectional view showing an example of a coating layer forming process using the second embodiment of the die head according to the present disclosure.
In the following description, the same reference numerals as in the first embodiment are assigned to the same components as in the first embodiment, and detailed description thereof will be omitted.

The second embodiment differs from the first embodiment in the following matters. That is, the die head according to the second embodiment has the third lip 40 in addition to the first lip 10 and the second lip 20 .

A die head 100B shown in FIGS. 4 and 5 is a die head for multi-layer coating.
The die head 100B can eject two types of coating liquids.
The die head 100B has a first lip 10, a second lip 20 and a third lip 40.
In addition, in the coating layer forming process shown in FIG. 5, the first lip 10 corresponds to the most upstream lip, and the second lip 20 corresponds to the most downstream lip.

The die head 100B is made of metal.
Metals include, for example, stainless steel. Note that the die head 100B may be made of a plurality of metals. For example, the tip of the first lip 10, the tip of the second lip 20, and the tip of the third lip 40 are made of ultrafine alloy (for example, TF15 (Mitsubishi Materials Co., Ltd.)) or cemented carbide. The parts other than the tip of the first lip 10, the tip of the second lip 20, and the tip of the third lip 40 are made of an alloy (for example, Nippon Tungsten Co., Ltd.), It may be made of stainless steel.

[Third lip 40]
The third lip 40 is a member that together with the first lip 10 and the second lip 20 define slots 30a and 30b, respectively.

As shown in FIGS. 4 and 5 , the third lip 40 is arranged side by side in the direction X with the first lip 10 and the second lip 20 .
A third lip 40 is arranged between the first lip 10 and the second lip 20 .

The third lip 40 is made of the metal described above.

As shown in FIG. 4, the shape of the third lip 40 may be columnar with the width direction Y as the length direction, and may have a recess for forming a manifold, which will be described later.

As shown in FIG. 5, the third lip 40 has a land surface 40A, a slot-forming surface 40B _-1 , and a slot-forming surface 40B _-2 .
Each surface constituting the third lip 40 will be described below.

(Land surface 40A)
As shown in FIG. 5, the land surface 40A faces the Z direction.
The land surface 40A faces the surface of the substrate F, which is the object to be coated, during the process of discharging the coating liquid _L1 and the coating liquid _L2 from the die head 100B, for example.

(Slot forming surface 40B ₁ )
The slot-forming surface _40B1 is the surface that, together with the slot-forming surface 10B of the first lip 10, defines the slot 30a.

The slot forming surface 40B- ₁ is connected to the land surface 40A on the side opposite to the slot forming surface 40B _-2 .
The slot forming surface _40B1 faces the slot forming surface 10B.

The slot forming surface _40B1 is a surface extending in the Z direction.

(Slot forming surface 40B ₂ )
Slot-forming surface _40B2 is the surface that, together with slot-forming surface 20B of second lip 20, defines slot 30b.

The slot forming surface 40B- ₂ is connected to the land surface 40A on the side opposite to the slot forming surface 40B- ₁ .
The slot forming surface _40B2 faces the slot forming surface 20B.

The slot forming surface _40B2 is a surface extending in the Z direction.

[Slot 30a]
The slot 30a is a space for transferring and discharging the coating liquid _L1 .

The slot 30a is formed between the first lip 10 and the third lip 40 that are adjacent in the X direction.
Specifically, the slot 30a is formed by the slot-forming surface 10B of the first lip 10 and the slot-forming surface _40B1 of the third lip 40. As shown in FIG.

The slot 30a extends in the Z direction.
In addition, in the die head 100B, the slot 30a communicates with the first manifold 50a.
The first manifold 50a is a space extending along the length direction of the die head 100B (that is, the Y direction in FIG. 4), and spreads the coating liquid _L1 supplied to the die head 100B in the coating width direction (that is, the die head 100B). , the Y direction in FIG. 4) to temporarily store the coating liquid _L1 .
A first manifold 50 a is formed between the first lip 10 and the third lip 40 .

[Slot 30b]
The slot 30b is a space for transferring and discharging the coating liquid _L2 .

The slot 30b is formed between the second lip 20 and the third lip 40 that are adjacent in the X direction.
Specifically, the slot 30b is formed by the slot-forming surface 20B of the second lip 20 and the slot-forming surface _40B2 of the third lip 40. As shown in FIG.

The slot 30b extends in the Z direction.
In addition, in the die head 100B, the slot 30b communicates with the second manifold 50b.
The second manifold 50b is a space extending along the length direction of the die head 100B (that is, the Y direction in FIG. 4), and spreads the coating liquid _L2 supplied to the die head 100B in the coating width direction (that is, the die head 100B). , the Y direction in FIG. 4) to temporarily store the coating liquid _L2 .
A second manifold 50 b is formed between the second lip 20 and the third lip 40 .

[how to use]
A method of using the die head 100B will be described below with reference to FIG.

As shown in FIG. 5, in the step of forming the coating layer using the die head 100B, the die head 100B applies the land surface 10A of the first lip 10 and the second lip 10 to the substrate F, which is the object to be coated. 20 and the land surface 40A of the third lip 40 are arranged to face each other.
The die head 100B is located on the lateral side of the backup roll 200, as shown in FIG. is positioned upstream in the direction in which the substrate F is conveyed.

The distance between the land surface 40A of the third lip 40 and the substrate F is not limited, and is determined, for example, according to the viscosity of the coating liquid _L1 , the viscosity of the coating liquid _L2 , and the thickness of the coating film to be formed. do it.
The distance between the land surface 40A of the third lip 40 and the base material F is in the range of 50 μm to 500 μm. The distance between the land surface 40A of the third lip 40 and the substrate F may be determined, for example, within the range of 100 μm to 300 μm. The distance between the land surface 40A of the third lip 40 and the substrate F is the distance between the land surface of the other lip (referring to the first lip or the second lip; hereinafter the same in this paragraph) and the substrate. may be the same as the distance of The distance between the land surface 40A of the third lip 40 and the substrate F may be different than the distance between the land surface of the other lip and the substrate F.

The substrate F is conveyed in the direction X with respect to the die head 100B.

The coating liquid _L1 supplied to the die head 100B is discharged through the slot 30a. The coating liquid _L2 supplied to the die head 100B is discharged through the slot 30b. The type of coating liquid _L1 may be the same as or different from the type of coating liquid _L2 .
The coating liquid L ₁ and the coating liquid L ₂ discharged from the die head 100A form a bead B between the die head 100B and the substrate F. By discharging the coating liquid L ₁ and the coating liquid L ₂ from the die head 100B while continuously conveying the substrate F, the coating liquids L ₁ and L ₂ forming the bead B move onto the substrate F. , a coating film can be formed on the substrate F.
After the coating film is formed on the base material F, the desired coating is formed on the base material F, which is the object to be coated, by passing through a process as necessary (for example, a drying process of the coating film, etc.). A layer is formed.

As for the method of forming the coating layer to which the die head 100B is applied, for example, the same method as the method of forming the coating layer to which the die head 100A is applied, which is described in the section "First Embodiment" above, is applied. be.

The disclosure is not limited to the embodiments described above. The present disclosure encompasses embodiments that are appropriately modified from the above embodiments within the scope of the present disclosure.

EXAMPLES The present disclosure will be described in detail below with reference to Examples. However, the present disclosure is not limited to the following examples.

<Preparation of base material>
A long triacetyl cellulose film (TD40UL, Fuji Film Co., Ltd., refractive index: 1.48, thickness: 60 μm, width: 1,340 mm) was prepared as a substrate. Hereinafter, it is also referred to as a TAC film.

<Preparation of coating liquid A>
A coating liquid A was prepared by mixing the following components.
- The following polymerizable liquid crystal compound L-9: 47.50 parts by weight - The following polymerizable liquid crystal compound L-10: 47.50 parts by weight - The following polymerizable liquid crystal compound L-3: 5.00 parts by weight - Below 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 polymerizable liquid crystal compound L-9 and the polymerizable liquid crystal compound L-10, one of R ¹ and R ² represents a methyl group, the other represents a hydrogen atom, and one of R ³ and R ⁴ 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 positions of methyl groups.

<Preparation of coating liquid B>
A coating liquid B was prepared by mixing the following components.
・The following liquid crystalline polymer LP1 (weight average molecular weight: 13,300): 4.011 parts by mass ・The following dichroic compound D1: 0.792 parts by mass ・The following dichroic compound D2: 0.963 parts by mass - The following interface improver F2 (weight average molecular weight: 10,000): 0.087 parts by weight - The following interface improver F3: 0.073 parts by weight - The following interface improver F4: 0.073 parts by weight - Tetrahydrofuran (Organic solvent having a boiling point of 80°C or less): 37.6004 parts by mass Cyclopentanone: 56.4006 parts by mass

The liquid crystalline polymer LP1 contains the structural unit (1) and the structural unit (2) in the molecule at a mass ratio of 80:20 ((1):(2)).

<Preparation of coating liquid C>
For methyl ethyl ketone (500 parts by mass), IPA (isopropanol, 500 parts by mass), partial caprolactone-modified polyfunctional acrylate (KAYARAD DPCA-20, Nippon Kayaku Co., Ltd., 750 parts by mass), silica sol (MIBK-ST, Nissan Chemical Industries, Ltd., 200 parts by mass) and a photopolymerization initiator (Omnirad 184, IGM Resins B.V., 50 parts by mass) 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), and methanol (120 parts by mass) are mixed with the following modified polyvinyl alcohol (PVA, degree of polymerization: 1,000, 20 parts by mass). Thus, a coating liquid D was prepared.

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

<Preparation of die head 1>
Using stainless steel (SUS630) and cemented carbide (M15, Nippon Tungsten Co., Ltd.) for the tip, a die head a having the same configuration as the die head 100A shown in FIG. 3 was produced. The die head a has a convex curved surface 12 with a radius of curvature of 0.4 mm at a portion of the outer surface 10C of the first lip 10 connected to the land surface 10A.
Surf containing a fluorine-containing compound (also referred to as an F compound) is applied to the land surface 10A and the outer surface 10C of the first lip 10 and the land surface 20A and the outer surface 20C of the second lip 20 of the die head a. A die head 1 was obtained by surface treatment using MX-031 manufactured by Kogyo Co., Ltd.
The dynamic contact angle hysteresis with methyl ethyl ketone of the surface layer obtained by surface treatment as described above was measured by the method described above, and it was 18°.
Further, the Rzjis of the surface layer was 1.1 μm when measured by the method described above.

<Preparation of die head 2>
A die head b having the same structure as the die head a was produced except that a convex curved surface 12 with a radius of curvature of 0.5 mm was provided at a portion of the outer surface 10C of the first lip 10 connected to the land surface 10A.
Die head b was subjected to surface treatment in the same manner as the preparation of die head 1 to obtain die head 2 .
The surface layer of the die head 2 was measured for dynamic contact angle hysteresis with methyl ethyl ketone by the method described above, and was found to be 18°.
Further, the Rzjis of the surface layer was 1.1 μm when measured by the method described above.

<Preparation of die head 3>
In the same manner as the die head b, except that the grinding finish conditions for the surfaces corresponding to the land surface 10A and the outer surface 10C of the first lip 10 and the land surface 20A and the outer surface 20C of the second lip 20 were changed. A die head c having the same configuration as the die head 100A shown in FIG. 3 was produced.
A die head 3 was obtained by subjecting the die head c to surface treatment in the same manner as the preparation of the die head 1 .
When the surface layer of the die head 3 was measured for dynamic contact angle hysteresis with methyl ethyl ketone by the method described above, it was 15°.
Further, the Rzjis of the surface layer was 0.9 μm when measured by the method described above.

<Preparation of die head 4>
Using stainless steel (SUS630) and cemented carbide (M15, Nippon Tungsten Co., Ltd.) for the tip, a die head d having the same configuration as the die head 100C shown in FIG. 5 was produced. In the die head d, a convex curved surface 12 with a radius of curvature of 0.4 mm was provided at a portion of the outer surface 10C of the first lip 10 connected to the land surface 10A.
A fluorine-containing compound is applied to the land surface 10A and the outer surface 10C of the first lip 10, the land surface 20A and the outer surface 20C of the second lip 20, and the land surface 40A of the third lip 40 of the die head d. A die head 4 was obtained by performing surface treatment using MX-031 of Surf Industry Co., Ltd. containing (that is, an F compound).
The dynamic contact angle hysteresis with methyl ethyl ketone of the surface layer obtained by surface treatment as described above was measured by the method described above, and it was 18°.
Further, the Rzjis of the surface layer was 1.1 μm when measured by the method described above.

<Preparation of die head 5>
A die head 5 was produced in the same manner as the die head 1, except that the surface treatment was changed to the following method.
That is, DuPont's tetrafluoroethylene resin (F resin Fluororesin coating was performed using
Further, the Rzjis of the surface layer obtained as described above was 1.1 μm when measured by the method described above.

<Preparation of die head 6>
A die head 6 was produced in the same manner as the die head 1, except that the surface treatment was changed to the following method.
That is, the land surface 10A and outer surface 10C of the first lip 10 and the land surface 20A and outer surface 20C of the second lip 20 of the die head a are coated with nickel and polytetrafluoroethylene by electroless plating. A composite plating layer (also called F-based plating) was formed.
Further, the Rzjis of the surface layer obtained as described above was 1.1 μm when measured by the method described above.

<Preparation of the die head 7>
A die head e having the same structure as the die head a was produced except that a portion of the outer surface 10C of the first lip 10 connected to the land surface 10A was flat.
A die head 7 was obtained by subjecting the die head e to surface treatment in the same manner as the preparation of the die head 1 .
The surface layer of the die head 7 was measured for dynamic contact angle hysteresis with methyl ethyl ketone by the method described above and found to be 18°.
Further, the Rzjis of the surface layer was 1.1 μm when measured by the method described above.

<Example 1>
A coating film having a width of 200 mm was formed by disposing the die head 1 as shown in FIG. 1 and coating the coating liquid A on the TAC film.
Specifically, the TAC film is transported onto a backup roll having a surface temperature of 60° C. and an outer diameter of 300 mm, and the TAC film is wound around the backup roll and transported on the lateral side of the backup roll. The coating liquid A was applied using the die head 1 arranged at .
When applying the coating liquid A, the wrap angle of the TAC film was 150°. Also, the transport speed of the TAC film was 30 m/min.
When applying the coating liquid A, the distance between the land surface 10A of the first lip 10 and the TAC film was 100 μm, and the distance between the land surface 20A of the second lip 20 and the TAC film was 100 μm. .

<Examples 2 to 4>
A coating film was formed by the same procedure as in Example 1, except that the type of coating liquid was changed according to Table 1.

<Examples 5 to 13, and Comparative Examples 1 to 9>
A coating film was formed by the same procedure as in Example 1 except that the type of die head was changed according to Table 1 and the type of coating liquid was changed as appropriate according to Table 1.
In Example 13, multilayer coating of coating liquid A and coating liquid A was performed.

<Confirmation of three-phase interface>
In the above-described examples and comparative examples, a glass transparent roll having a camera inside was used as a backup roll to observe the land surface 10A of the first lip 10 while the coating liquid was being applied. . When the land surface 10A of the first lip 10 was once covered with the coating liquid and then exposed again to form a three-phase interface, it was determined that the three-phase interface was present. Observation results are shown in Table 1.

<Evaluation of coating defects>
Five evaluation samples each having a width of 200 mm and a length of 2,000 mm were cut out from the obtained coating film. Each of the obtained evaluation samples was placed on a light table, and then the coating film was exposed to light to visually observe the presence or absence of shading, the number of shadings, and the length of the shading. The total number of shades (that is, the number of coating defects) in the five evaluation samples was calculated, and the coating defects were evaluated according to the following criteria.
Table 1 shows the evaluation results.

-standard-
1: No shading was observed, and no coating defects were observed.
2: Darkness (that is, coating defects) having a length of about 100 mm to 1000 mm was observed, and 1 to 4 coating defects were observed.
3: Darkness (that is, coating defects) having a length of about 100 mm to 1000 mm was observed, and 5 or more coating defects were observed.

<Evaluation of coating>
Based on the transport speed of the TAC film and the observation of the shape of the obtained coating film, the time from the start of the coating film formation to the formation of the coating film over a width of 200 mm on the TAC film was determined.
Table 1 shows the evaluation results.

<Evaluation of Coating Streaks>
The shape of the bead during application in each of the above examples is the front direction side (that is, the outer surface 10C side of the first lip 10) and the back direction side (that is, the outer surface 20C of the second lip 20). side), the formed coating film (width 200 mm × length 5000 mm) is placed on a light table, transmitted light is applied, and the presence or absence of shading or repetition of shading is visually observed, Coating streaks were evaluated by linking the observation results of the bead shape with the film thickness unevenness indicated by the gradation.
With respect to the conveying direction of the substrate, the coating streak 1 was caused by the lip on the most upstream side (that is, the first lip), and the coating streak 2 was caused by the lip on the most downstream side (that is, the second lip). .
The criteria are as follows.
Table 1 shows the evaluation results.

-standard-
1: No coating streak is observed.
2: Coating streaks were observed very slightly.
3: One or more but less than five distinct coating streaks were observed.
4: Five or more clear coating streaks were observed on the entire surface.

According to Table 1, as is clear from Examples 1 to 13, the use of die heads 1 to 4 suppresses the occurrence of coating defects and speeds up coating.
It is also found that the use of die heads 1 to 4 and 7 suppresses the occurrence of coating streaks.

[Description of symbols]
10: first lip 10A: land surface of first lip 10B: slot forming surface of first lip 10C: outer surface of first lip 12: curved surface 20: second lip 20A: second lip Land surface 20B: Slot forming surface of second lip 20C: Outer surface of second lip 20Cz: Wetted part 30, 30a, 30b: Slot 40: Third lip 40A: Land surface of third lip 40B ₁ , 40B ₂ : Slot forming surface of third lip 50: Manifold 50a: First manifold 50b: Second manifold 100, 100A, 100B: Die head B: Bead F: Substrate L, L ₁ , L ₂ : Application liquid

The disclosure of Japanese Patent Application No. 2020-042282 filed on March 11, 2020 is incorporated herein by reference in its entirety. All publications, patent applications and technical standards mentioned herein are to the same extent as if each individual publication, patent application and technical standard were specifically and individually indicated to be incorporated by reference. incorporated herein by reference.

Claims (7)

having at least two lips arranged in parallel and defining slots between adjacent lips for transporting and discharging the coating liquid;
The at least two lips are located at one end in the parallel direction of the lips, and have a land surface, a slot-forming surface connected to the land surface, and an outer surface connected to the land surface on the opposite side of the slot-forming surface. including a lip of
The dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface of the first lip is 20° or less,
In a side view along the parallel direction, a portion of the outer surface of the first lip connected to the land surface has a curved surface,
A die head , wherein the first lip is an upstream lip . The die head according to claim 1, wherein the curved surface of the first lip has a radius of curvature of 0.5 mm or more. The die head according to claim 1 or 2, wherein the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the curved surface of the first lip is 20° or less. The at least two lips are positioned at the other end in the parallel direction of the lips, and have a land surface, a slot-forming surface connected to the land surface, and an outer surface connected to the land surface on the opposite side of the slot-forming surface. 2 lips,
The die head according to any one of claims 1 to 3, wherein the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the outer surface of the second lip is 20° or less. At least one surface selected from the group consisting of the land surface and the curved surface of the first lip and the outer surface of the second lip has a ten-point average roughness Rzjis of 1.0 μm or less. The die head according to any one of claims 1 to 4. Among the land surface and the curved surface of the first lip and the outer surface of the second lip, the surface having a dynamic contact angle hysteresis of 20° or less for methyl ethyl ketone is provided with a surface layer containing a fluorine-containing compound. The die head according to any one of claims 1 to 5. 7. The die head of claim 6, wherein said fluorine-containing compound is a compound having a perfluoropolyether group.

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