JP7273242B2 - 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.

Patent Document 1 discloses a coating member manufacturing apparatus 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 an application member is disclosed 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 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 base material. It has a die head for discharging the coating liquid, a coating liquid tank for containing the coating liquid for forming the transparent conductive layer, and a liquid feeding path for feeding the coating liquid for forming the transparent conductive layer from the coating liquid tank to the die head. , a die coating apparatus characterized in that a liquid-repellent region is formed at least on the surface of the die head located in the direction opposite to the coating direction.

JP-A-2002-248399 JP 2016-68047 A

However, in a coating layer formed by a coating device equipped with a conventional die head, streaks formed along the coating direction (referring to the direction in which the coating liquid is applied to the object to be coated; the same shall apply hereinafter) defects (hereinafter referred to as "coating streaks") may be observed. Furthermore, in a coating apparatus provided with a conventional die head, there is a problem that the variation in the thickness of the coating liquid discharged from the die head increases in the coating direction. Problems such as those described above cause, for example, deterioration of the appearance of the coating layer or the properties of the coating layer.

The present disclosure has been made in view of the circumstances described above.
An object of one aspect of the present disclosure is to provide a die head that suppresses the occurrence of coating streaks and reduces variations in the thickness of a coating liquid.

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 being arranged at one end in the parallel direction of the lips a first lip positioned thereon and having 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 dynamic contact angle hysteresis of methyl ethyl ketone with respect to at least one selected from the group consisting of the land surface and the outer surface of the first lip is 20° or less, and the land surface of the first lip A die head having a length in the parallel direction of 0.01 mm to 0.2 mm.
<2> At least one ten-point average roughness Rzjis selected from the group consisting of the land surface of the first lip and the outer surface of the first lip is 1.0 μm or less <1> The die head described in .
<3> In at least one selected from the group consisting of the land surface of the first lip and the outer surface of the first lip, the dynamic contact angle hysteresis is 20° or less, The die head according to <1> or <2>, which has a layer containing a fluorine-containing compound as a surface layer.
<4> The die head according to <3>, wherein the fluorine-containing compound is a compound having a perfluoropolyether group.
<5> The dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface of the first lip is 20° or less, and the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the outer surface of the first lip is 20. ° or less, the die head according to any one of <1> to <4>.
<6> The dynamic contact angle hysteresis of methyl ethyl ketone with respect to at least a region of the outer surface of the first lip that contacts the coating liquid is 20° or less, according to any one of <1> to <5>. die head.

According to one aspect of the present disclosure, a die head is provided that suppresses the occurrence of coating streaks and reduces variations in the thickness of the coating liquid.

1 is a schematic perspective view showing a die head according to a first embodiment of the present disclosure; FIG. FIG. 4 is a schematic cross-sectional view showing an example of a coating layer forming process using the die head according to the first embodiment of the present disclosure; FIG. 5 is a schematic perspective view showing a die head according to a second embodiment of the present disclosure; FIG. 7 is a schematic cross-sectional view showing an example of a coating layer forming process using a die head according to a second embodiment of 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.

<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 coating liquid between adjacent lips, the at least two lips being parallel to each other. a first lip positioned at one end in a direction and having 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; The dynamic contact angle hysteresis of methyl ethyl ketone on at least one selected from the group consisting of the land surface of the first lip and the outer surface of the first lip is 20 ° or less, and the first lip The length of the land surface in the parallel direction is 0.01 mm to 0.2 mm. According to the die head according to the present disclosure, the occurrence of coating streaks is suppressed, and variations in the thickness of the coating liquid are reduced.

The reason why the die head according to the present disclosure has the above effect is presumed as follows. In a method of forming a coating layer (hereinafter sometimes referred to as a "coating film") using a die head, for example, the coating liquid is discharged from the die head while continuously conveying the object to be coated. For example, in the process of ejecting the coating liquid from the die head, if the solid content of the coating liquid adheres to the tip of the die head (for example, the land surface of the lip), the thickness of the coating layer in the width direction will vary, causing coating streaks. easier to do. Moreover, the coating liquid discharged from the die head forms a bead (that is, a liquid pool) between the die head and the object to be coated. If the volume of the bead changes during the process of discharging the coating liquid from the die head, the variation in the thickness of the coating liquid in the coating direction also increases. In addition, variations in the thickness of the coating liquid due to changes in the volume of the beads often appear in short cycles, and it has been difficult to reduce the effects of variations in the thickness of the coating liquid on the appearance or properties of the coating layer. On the other hand, according to the die head according to the present disclosure, a specific region of the first lip located at one end of the parallel direction of the lip (that is, a group consisting of the land surface of the first lip and the outer surface of the first lip (at least one selected from the It is possible to suppress the formation of lumps and the retention of droplets of the coating liquid in the specific region. As a result, it is possible to prevent the solid content of the coating liquid from adhering to the specific region. In addition to adjusting the dynamic contact angle hysteresis in the specific region to a predetermined range, adjusting the length of the land surface of the first lip to a range of 0.01 mm to 0.2 mm can Volume fluctuation can be suppressed. Therefore, according to the die head according to the present disclosure, the occurrence of coating streaks is suppressed, and variations in the thickness of the coating liquid are reduced.

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

In the present disclosure, “the dynamic contact angle hysteresis of methyl ethyl ketone on the outer surface of the first lip is 20° or less” means that methyl ethyl ketone on the entire or part of the outer surface of the first lip unless otherwise specified. dynamic contact angle hysteresis of 20° or less. In the outer surface of the first lip, the area where the dynamic contact angle hysteresis of methyl ethyl ketone is 20° or less preferably includes at least the area in contact with the coating liquid. In one embodiment, the dynamic contact angle hysteresis of methyl ethyl ketone on at least the region of the outer surface of the first lip that contacts the coating liquid is preferably 20° or less. In the present disclosure, the term “region in contact with the coating liquid” means a region in contact with the coating liquid discharged from the die head. Hereinafter, the area that comes into contact with the coating liquid may be referred to as a "liquid contact portion".

<<First Embodiment>>
A die head according to a first embodiment of the present disclosure will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic perspective view showing a die head according to a first embodiment of the present disclosure; FIG. FIG. 2 is a schematic cross-sectional view showing an example of a coating layer forming process using the die head according to the first embodiment of the present disclosure.

A die head 100A shown in FIGS. 1 and 2 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.

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 grain alloy (for example, TF15 (Mitsubishi Materials Co., Ltd.)) or a cemented carbide (for example, 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 that defines the slot 30 .

As shown in FIGS. 1 and 2, the first lip 10 is arranged side by side along the direction X with the second lip 20 . The first lip 10 is arranged in the direction X upstream of the second lip 20 . That is, the first lip 10 is arranged at one end in the parallel direction of the lip. As will be described later, the direction X shown in FIG. 2 also corresponds to the conveying direction of the substrate F, which is the object to be coated. For example, in the description of the position of the first lip 10 based on the conveying direction of the article to be coated, the first lip 10 is arranged in the direction X, that is, the most upstream in the conveying direction of the article to be coated.

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

As shown in FIG. 1, the shape of the first lip 10 is columnar with the direction Y as its longitudinal direction.

As shown in FIG. 2, the first lip 10 has a land surface 10A, a slotted surface 10B and an outer surface 10C. The constituent elements of the first lip 10 will be described below.

(Land surface 10A)
As shown in FIG. 2, 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 length of the land surface 10A (referring to the distance from end to end of the land surface 10A in the direction X; the same shall apply hereinafter) is set within a range of 0.01 mm to 0.2 mm. Since the length of the land surface 10A is 0.01 mm or more, the straightness (that is, grinding accuracy) of the land surface 10A in the X direction and the Y direction can be increased. In particular, by increasing the straightness of the land surface 10A in the direction Y, it is possible to form a uniform bead in the width direction of the bead (meaning the direction along the direction Y), thereby suppressing the occurrence of coating streaks. be able to. Since the length of the land surface 10A is 0.2 mm or less, it is possible to reduce fluctuations in the position of the tip of the bead on the upstream side. The length of the land surface 10A is preferably 0.15 mm or less, more preferably 0.1 mm or less, from the viewpoint of reducing fluctuations in the position of the upstream end of the bead. From the viewpoint of improving grinding accuracy, the length of the land surface 10A is preferably 0.02 mm or longer, and more preferably 0.05 mm or longer.

The land surface 10A has a layer containing a fluorine-containing compound as a surface layer. According to the layer containing the fluorine-containing compound, as will be described later, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A can be set in the range of 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 capable of adjusting the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A within a range of 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. Compositions containing fluorine-containing compounds (eg, coating agents) can also be used as sources of fluorine-containing compounds. Examples of commercially available fluorine-containing compounds having a perfluoropolyether group include "Optool (registered trademark) DSX" (Daikin Industries, Ltd.), "Optool DSX-E" (Daikin Industries, Ltd.), and "Optool UD100". (Daikin Industries, Ltd.), "KY-164" (Shin-Etsu Chemical Co., Ltd.), and "KY-108" (Shin-Etsu Chemical Co., Ltd.). The commercial products described above can be used as a supply source of the fluorine-containing compound. As a supply source of the fluorine-containing compound, for example, "fluorine-based ultra-thin coat MX-031" (Surf Industry Co., Ltd.) can also be used.

A 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 fluorine-containing compound to the surface to be treated, drying and curing the fluorine-containing compound. Examples of means for applying the fluorine-containing compound include brush coating, dip coating, and spray coating.

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

The dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A is set within a range of 20° or less. When the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A is 20° or less, the occurrence of coating streaks can be suppressed. The lower limit of dynamic contact angle hysteresis of methyl ethyl ketone with respect to land surface 10A is not limited. The dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A may be set, for example, in the range of 1° or more from the viewpoint of the measurement limit.

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.

The ten-point average roughness Rzjis of the land surface 10A is set within a range of 2.0 μm or less. When the land surface 10A has a ten-point average roughness Rzjis of 2.0 μm or less, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A can be reduced. The ten-point average roughness Rzjis of the land surface 10A is preferably 1.5 μm or less, more preferably 1.0 μm or less. The lower limit of the ten-point average roughness Rzjis of the land surface 10A is not limited. 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.

In the present disclosure, 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.

(Slot forming surface 10B)
The slot-forming surface 10B is a surface that defines the slot 30. As shown in FIG.

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 extends 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.

A wetted portion 10Cz, which is a part of the outer surface 10C, has a layer containing a fluorine-containing compound as a surface layer.

Examples of the fluorine-containing compound contained in the surface layer of the liquid-contacting portion 10Cz include the fluorine-containing compound described in the above section of "first lip 10". Preferred aspects of the fluorine-containing compound are the same as the preferred aspects of the fluorine-containing compound described in the section "First lip 10" above. As a method for forming the layer containing the fluorine-containing compound, for example, the method described in the above section "First lip 10" can be used.

The dynamic contact angle hysteresis of methyl ethyl ketone with respect to the wetted portion 10Cz is set within a range of 20° or less. When the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the liquid contact portion 10Cz is 20° or less, the occurrence of coating streaks can be suppressed. The preferred range of the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the liquid contact portion 10Cz is the same as the preferred range of the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A.

The ten-point average roughness Rzjis of the wetted portion 10Cz is set within a range of 2.0 μm or less. When the liquid contact portion 10Cz has a ten-point average roughness Rzjis of 2.0 μm or less, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the liquid contact portion 10Cz can be reduced. The preferred range of the ten-point average roughness Rzjis of the liquid contact portion 10Cz is the same as the preferred range of the ten-point average roughness Rzjis of the land surface 10A.

[Second lip 20]
The second lip 20 is the member that defines the slot 30 .

As shown in FIGS. 1 and 2, the second lip 20 is arranged along the direction X along with the first lip 10 . The second lip 20 is arranged in the direction X downstream of the first lip 10 .

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

As shown in FIG. 1, the shape of the second lip 20 is columnar with the direction Y as its longitudinal direction.

As shown in FIG. 2, the second lip 20 has a land surface 20A, a slotted surface 20B and an outer surface 20C. The constituent elements of 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 a surface that defines the slot 30. As shown in FIG.

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 extends 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.

[Slot 30]
The slot 30 is a space for transferring and discharging the coating liquid L between the adjacent first lip 10 and second lip 20 .

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 for temporarily storing the coating liquid L supplied to the die head 100A. 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. 2, in the coating layer forming process using the die head 100A, the die head 100A is arranged above the substrate F, which is the object to be coated.

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 may be determined, for example, within 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 may be determined, for example, within 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. The coating liquid L supplied onto the substrate F moves in the direction X together with the substrate F. As shown in FIG. A coating layer can be formed on the substrate F by ejecting the coating liquid L from the die head 100A while the substrate F is continuously conveyed.

In the die head 100A, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A and the liquid contact portion 10Cz that is part of the outer surface 10C is 20° or less, and the length of the land surface 10A is 0.01 mm to 0. When the thickness is 0.2 mm, it is possible to suppress adhesion of solid matter that causes coating streaks to the tip portion of the first lip 10 in the process of discharging the coating liquid L from the die head 100A. In addition, in the die head 100A, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A and the liquid contact portion 10Cz, which is a part of the outer surface 10C, is 20° or less, and the length of the land surface 10A is 0.01 mm. A variation of the bead volume can be suppressed by being 0.2 mm. Therefore, according to the die head 100A, the occurrence of coating streaks is suppressed, and variations in the thickness of the coating liquid are reduced.

Raw materials and conditions in the method for forming the coating layer are described below. However, the method for forming the coating layer 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, according to the die head according to the present disclosure, even with a coating liquid containing an organic solvent, the effect of suppressing the occurrence of coating streaks is likely 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 content concentration of 40. A coating liquid having a content of 60% by mass to 60% by mass may be mentioned. 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 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 can be, for example, in the range of 5 μm or less (preferably 0.1 μm to 100 μm).

<<Second Embodiment>>
Next, a die head according to a second embodiment of the present disclosure will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a schematic perspective view showing a die head according to a second embodiment of the present disclosure; FIG. FIG. 4 is a schematic cross-sectional view showing an example of a coating layer forming process using a die head according to the second embodiment of the present disclosure. In the following description, the same constituent elements as in the first embodiment are assigned the same reference numerals as in the first embodiment, and detailed description thereof will be omitted.

The second embodiment differs from the first embodiment in the following points. 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. 3 and 4 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.

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 (for example, Nippon Tungsten Co., Ltd.), and 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 stainless steel may be formed by

[Third lip 40]
The third lip 40 is a member that defines slots 30a and 30b, respectively.

As shown in FIGS. 3 and 4, the third lip 40 is arranged along the direction X along 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. 3, the shape of the third lip 40 is columnar with the width direction Y as the longitudinal direction.

As shown in FIG. 4, the third lip 40 has a land surface 40A, a slot-forming surface 40B _-1 , and a slot-forming surface 40B _-2 . The constituent elements of the third lip 40 are described below.

(Land surface 40A)
As shown in FIG. 4, 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 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 extends in the Z direction.

(Slot forming surface 40B ₂ )
The slot-forming surface _40B2 is the surface that defines the 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 extends in the Z direction.

[Slot 30a]
The slot 30a is a space for transferring and discharging the coating liquid _L1 between the first lip 10 and the third lip 40 adjacent to each other.

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 for temporarily storing the coating liquid _L1 supplied to the die head 100B. 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 between the second lip 20 and the third lip 40 adjacent to each other.

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 for temporarily storing the coating liquid _L2 supplied to the die head 100B. 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. 4, in the coating layer forming process using the die head 100B, the die head 100B is arranged above the substrate F, which is the object to be coated.

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 substrate F may be determined within 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. The coating liquid _L1 and the coating liquid _L2 supplied onto the substrate F move in the direction X together with the substrate F. As shown in FIG. A coating layer can be formed on the base material F by ejecting the coating liquid L ₁ and the coating liquid L ₂ from the die head 100B while the base material F is continuously conveyed.

As in the first embodiment described above, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A and the wetted portion 10Cz that is a part of the outer surface 10C is 20° or less, and the length of the land surface 10A is is 0.01 mm to 0.2 mm, solid content that causes coating streaks at the tip of the first lip 10 during the process of discharging the coating liquid L ₁ and the coating liquid L ₂ from the die head 100B. Adhesion can be suppressed. In addition, in the die head 100B, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A and the liquid contact portion 10Cz, which is a part of the outer surface 10C, is 20° or less, and the length of the land surface 10A is 0.01 mm. A variation of the bead volume can be suppressed by being 0.2 mm. Therefore, according to the die head 100B, the occurrence of coating streaks is suppressed, and variations in the thickness of the coating liquid are reduced.

As the raw materials and conditions in the method of forming the coating layer, for example, the raw materials and conditions described in the section "First Embodiment" can be used.

<<Modification>>
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 purpose of the present disclosure.

In the above-described embodiment, it was explained that the land surface 10A has a layer containing a fluorine-containing compound as a surface layer. However, instead of the layer containing the fluorine-containing compound, a layer having properties similar to those of the layer containing the fluorine-containing compound with respect to the dynamic contact angle hysteresis of methyl ethyl ketone may be used. Layers having similar properties to the layer containing the fluorine-containing compound include, for example, layers containing the silicon-containing compound. Examples of silicon-containing compounds include siloxanes. Siloxanes include, for example, silicones. Moreover, as long as the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A is set within the range of 20° or less, the layer containing the fluorine-containing compound may be omitted.

In the embodiment described above, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A and the wetted portion 10Cz, which is a part of the outer surface 10C, is set to 20° or less. However, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A or the wetted portion 10Cz, which is a part of the outer surface 10C, may be set within a range of 20° or less.

In the above-described embodiment, it has been described that the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the wetted portion 10Cz, which is a part of the outer surface 10C, is set within the range of 20° or less. However, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the entire outer surface 10C may be set within a range of 20° or less.

In the above-described embodiment, the land surface 10A and the liquid contact portion 10Cz, which is a part of the outer surface 10C, have the ten-point average roughness Rzjis set in the range of 2.0 μm or less. However, the ten-point average roughness Rzjis of the land surface 10A or the wetted portion 10Cz, which is a part of the outer surface 10C, may be set to a range of 2.0 μm or less. Ten-point average roughness Rzjis of the land surface 10A and the wetted portion 10Cz, which is a part of the outer surface 10C, may exceed 2.0 μm.

In the above-described embodiment, the ten-point average roughness Rzjis of the wetted portion 10Cz, which is a part of the outer surface 10C, is set to a range of 2.0 μm or less. However, the ten-point average roughness Rzjis of the entire surface of the outer surface 10C may be set within a range of 2.0 μm or less.

In the embodiment described above, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 20A may be set within a range of 20° or less. According to the above aspect, it is possible to further suppress the occurrence of coating streaks. The preferred range of dynamic contact angle hysteresis of methyl ethyl ketone with respect to land surface 20A is the same as the preferred range of dynamic contact angle hysteresis of methyl ethyl ketone with respect to land surface 10A.

In the above-described embodiment, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the outer surface 20C (preferably, the area of the outer surface 20C that contacts the coating liquid) may be set within a range of 20° or less. According to the above aspect, it is possible to further suppress the occurrence of coating streaks. The preferred range of the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the outer surface 20C is the same as the preferred range of the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 10A.

In the second embodiment described above, the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface 40A may be set within a range of 20° or less. According to the above aspect, it is possible to further suppress the occurrence of coating streaks. The preferred range of dynamic contact angle hysteresis of methyl ethyl ketone with respect to land surface 40A is the same as the preferred range of dynamic contact angle hysteresis of methyl ethyl ketone with respect to land surface 10A.

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.

<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, and the other of R ¹ and R ² represents a hydrogen atom. , one of R ³ and R ⁴ represents a methyl group, and the other of R ³ and R ⁴ 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 : 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 die head 1>
Using stainless steel (SUS630), a die head 1 having the same configuration as the die head 100A shown in FIG. 2 was produced. The length of the land surface 10A of the first lip 10 was 0.01 mm. Next, the land surface 10A of the first lip 10 and the outer surface 10C of the first lip 10 were surface-treated by the following method. First, a 0.1% by mass aqueous solution of NaOH was applied to the surface to be treated, followed by drying to perform pretreatment. Next, the surface to be treated was subjected to surface treatment using MX-031 manufactured by Surf Industry Co., Ltd. Through the above procedure, surface treatment layers were formed as the surface layers of the land surface 10A of the first lip 10 and the outer surface 10C of the first lip 10 . The dynamic contact angle hysteresis of methyl ethyl ketone with respect to each surface treatment layer measured by the method described above was 18°. The ten-point average roughness Rzjis of each surface treatment layer measured by the method described above was 1.1 μm.

<Preparation of die head 2>
A die head 2 was produced in the same manner as the die head 1, except that the length of the land surface 10A of the first lip 10 was changed to 0.2 mm. The dynamic contact angle hysteresis of methyl ethyl ketone with respect to each surface treatment layer measured by the method described above was 18°. The ten-point average roughness Rzjis of each surface treatment layer measured by the method described above was 1.1 μm.

<Preparation of die head 3>
A die head 3 was produced in the same manner as the die head 1 except that the grinding finishing conditions for the land surface 10A of the first lip 10 and the outer surface 10C of the first lip 10 were changed. The dynamic contact angle hysteresis of methyl ethyl ketone with respect to each surface treatment layer measured by the method described above was 15°. The ten-point average roughness Rzjis of each surface treatment layer measured by the method described above was 0.9 μm.

<Preparation of die head 4>
Changing the grinding finish conditions for the land surface 10A of the first lip 10 and the outer surface 10C of the first lip 10, and changing the length of the land surface 10A of the first lip 10 to 0.2 mm A die head 4 was produced in the same manner as the die head 1 except for the above. The dynamic contact angle hysteresis of methyl ethyl ketone with respect to each surface treatment layer measured by the method described above was 15°. The ten-point average roughness Rzjis of each surface treatment layer measured by the method described above was 0.9 μm.

<Preparation of die head 5>
A die head 5 was produced in the same manner as the die head 1, except that the length of the land surface 10A of the first lip 10 was changed to 0.005 mm. The dynamic contact angle hysteresis of methyl ethyl ketone with respect to each surface treatment layer measured by the method described above was 18°. The ten-point average roughness Rzjis of each surface treatment layer measured by the method described above was 1.1 μm.

<Preparation of die head 6>
A die head 6 was produced in the same manner as the die head 1 except that the length of the land surface 10A of the first lip 10 was changed to 0.3 mm. The dynamic contact angle hysteresis of methyl ethyl ketone with respect to each surface treatment layer measured by the method described above was 18°. The ten-point average roughness Rzjis of each surface treatment layer measured by the method described above was 1.1 μm.

<Example 1>
By disposing the die head 1 as shown in FIG. 2 and applying the coating liquid A on a triacetyl cellulose film (that is, a TAC film), a coating film (thickness: 10 μm, width: 200 mm, length: 5 ,000 mm) were formed. Specifically, the TAC film was transported onto 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 TAC film on the backup roll using the die head 1 . When applying the coating liquid A, the wrap angle of the TAC film was 150°. 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 F was 100 μm. rice field.

<Example 2>
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 3 to 8, and Comparative Examples 1 to 4>
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 appropriately changed according to Table 1.

<Evaluation of Coating Streaks>
A coating film (width: 200 mm, length: 5,000 mm) was placed on a light table and then exposed to light to visually observe the presence or absence of shading or the presence or absence of repetition of shading. Coating streaks were evaluated according to the above observation results and the following criteria. Table 1 shows the evaluation results.

(standard)
1: No coating streak is observed.
2: Very weak coating streaks were observed.
3: One or more but less than 5 clear coating streaks were observed.
4: 5 or more clear coating streaks were observed.

<Evaluation of Thickness Variation of Coating Liquid>
Using a film thickness measuring instrument (SI-T90, spot diameter: 30 μm, Keyence Corporation), the thickness in the longitudinal direction of the central portion of the dried coating film was measured at 10 locations every 5 mm. Since the thickness of the coating film in the longitudinal direction varies according to the thickness variation of the coating liquid, the thickness variation of the coating liquid can be evaluated by measuring the thickness of the coating film in the longitudinal direction. In addition, since the cycle of the thickness variation of the coating film due to the bead volume variation is often shortened, the thickness variation of the coating film can be evaluated in the narrow measurement range as described above. Based on the thickness variation in the longitudinal direction of the coating film, the thickness variation of the coating liquid was evaluated according to the following criteria. Table 1 shows the evaluation results.

(standard)
1: ±2% or less 2: greater than ±2% and ±4% or less 3: greater than ±4%

Table 1 shows the following results. In Examples 1 to 8, as compared to Comparative Examples 1 to 4, the occurrence of coating streaks was suppressed, and variation in the thickness of the coating liquid was reduced.

The disclosure of Japanese Patent Application No. 2020-037735 filed on March 5, 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.

10: first lip 10A: land surface of first lip 10B: slot forming surface of first lip 10C: outer surface of first lip 10Cz: wetted portion 20: second lip 20A: second lip Land surface of lip 20B: Slot forming surface of second lip 20C: Outer surface of second lip 30, 30a, 30b: Slot 40: Third lip 40A: Land surface of third lip _40B1 , _40B2 : Slot forming surface of third lip 50: Manifold 50a: First manifold 50b: Second manifold 100A, 100B: Die head B: Bead F: Base material L, L ₁ , L ₂ : Coating liquid

Claims (5)

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. a first lip having
The dynamic contact angle hysteresis of methyl ethyl ketone with respect to the land surface of the first lip is 20° or less , and the dynamic contact angle hysteresis of methyl ethyl ketone with respect to the outer surface of the first lip is 20 ° or less. can be,
The die head, wherein the land surface of the first lip has a length in the parallel direction of 0.01 mm to 0.2 mm. 2. The ten-point average roughness Rzjis of at least one selected from the group consisting of the land surface of the first lip and the outer surface of the first lip is 1.0 μm or less. die head. 3. The die head according to claim 1, wherein the region where the dynamic contact angle hysteresis is 20[deg.] or less has a layer containing a fluorine-containing compound as a surface layer. 4. A die head according to claim 3, wherein said fluorine-containing compound is a compound having a perfluoropolyether group. The die head according to any one of claims 1 to 4, wherein the dynamic contact angle hysteresis of methyl ethyl ketone with respect to at least a region of the outer surface of the first lip that contacts the coating liquid is 20° or less.

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