WO2019225648A1

WO2019225648A1 - Method for forming coating film

Info

Publication number: WO2019225648A1
Application number: PCT/JP2019/020272
Authority: WO
Inventors: 雅士三宅; 道平　創
Original assignee: 日東電工株式会社
Priority date: 2018-05-22
Filing date: 2019-05-22
Publication date: 2019-11-28
Also published as: CN112154034A; TWI832860B; KR20210015829A; JP2019202251A; TW202003119A; CN112154034B; JP6554580B1

Abstract

In a method for forming a coating film, in which a coating device is used to form a coating film by coating a coating liquid onto an object being coated, a liquid having a prescribed degree of elongation is used as the coating liquid, and a gap between a discharge port and the object being coated is adjusted in such a way that a bulging part of a bead does not come into contact with the object being coated, while said bead including the bulging part and an extended part is being formed.

Description

Coating film forming method

Cross-reference of related applications

This application claims the priority of Japanese Patent Application No. 2018-097673, and is incorporated herein by reference.

The present invention relates to a coating film forming method.

Conventionally, in a coating film forming method, for example, a die coater that coats a coating liquid onto an object to be coated such as a substrate is used as one of coating apparatuses.

For example, as shown in FIG. 8, the coating apparatus 50 that is a die coater discharges the coating liquid 23 from the discharge port 53aa to the workpiece 21 that moves relatively while being supported by the support portion 65. A die as a coating part 53 to be coated is provided. The coating device 50 is applied to the coating object 21 by the coating unit 53 while moving the coating object 21, and the coating liquid 23 applied to the coating object 21 is solidified and applied. A construction film 25 is formed. The coating unit 53 includes an upstream die block 55 and a downstream die block 57 that are arranged to face each other so as to form a slot 58, and a leading edge of the slot 58 serves as a discharge port 53 aa. Yes.

In such a coating apparatus 50, the distance (gap) G between the workpiece 21 and the discharge port 53aa is the thickness of the coated coating solution 23, that is, the thickness of the coating film 25 before solidification ( Wet thickness) is set to about twice or less of T.

However, when the gap G is small as described above, foreign matter such as dust may be caught between the workpiece 21 and the discharge port 53aa, resulting in a problem that streaks are generated. When such a defect occurs, the quality of the obtained coating film is deteriorated.

Therefore, the gap G is set to 2.5 times or more the wet thickness T of the coating film, and the coating liquid is discharged straight from the discharge port along the direction perpendicular to the object to be coated. There has been proposed a coating apparatus configured to cause a coating liquid to collide with an object to be coated by spraying in such a manner (see Patent Document 1).

Japanese Laid-Open Patent Publication No. 10-290946

However, in the coating apparatus of Patent Document 1, the exit interval (slot width) of the slit (slot) is as narrow as 0.1 mm or less. For this reason, when applying the coating liquid to the coating object, due to this narrowness, the variation in the processing accuracy of the slot in the width direction of the coating object is large in the variation of the wet thickness of the coating liquid. As a result, a coating film having coating unevenness may be obtained. Such a coating film has a reduced quality.

In view of the above circumstances, an object of the present invention is to provide a coating film forming method capable of obtaining a coating film in which deterioration in quality due to coating unevenness is suppressed.

The coating film forming method according to the present invention is:
An object to be coated that has a discharge port for discharging the coating liquid and moves relative to the discharge port.
A coating film forming method for forming a coating film by applying the coating liquid to the object to be coated, using a coating apparatus that discharges the coating liquid from the discharge port. And
Using the coating liquid having a predetermined elongation, when the coating liquid is discharged from the discharge port to the coated object, a bulging portion that swells on the discharge port side, and Forming the bead having an extended portion extending downstream in the moving direction of the coated object so as to taper from the bulging portion to the coated object, and the discharge port and the coated object; Applying the coating liquid to the object to be coated while maintaining the state of tying, and
According to the size of the bulging portion, the gap between the discharge port and the coating object is adjusted so that the bulging portion does not contact the coating object. It is a method of applying the coating liquid.

Here, the bulging portion is a portion that swells more than a portion (extended portion) on the side of the object to be coated on the discharge port side, and is coated so as not to come into direct contact with the object to be coated. It means a part where a gap is formed between the workpiece.
Further, the degree of elongation means that the coating liquid is discharged at a speed of 5 g / min from a opening of a cylindrical member having an inner diameter of 2 mm to a roll rotating at a rotational speed of 30 m / min at a position 1 mm away from the opening. When the distance between the opening of the cylindrical member and the roll (measurement gap D) is increased from 1 mm, the distance between the opening and the roll when the coating liquid connecting the opening and the roll is cut is represented. A numerical value (mm) is meant.

In the coating film forming method of the above configuration,
The predetermined extension may be 2 mm or more.

In the coating film forming method of the above configuration,
A gap between the object to be coated and the discharge port may be set to 0.5 to 2 mm.

In the coating film forming method of the above configuration,
The interval between the discharge ports may be 0.05 to 1.5 mm.

The schematic side view which shows the coating apparatus used for the coating film formation method of one Embodiment of this invention 1 is a schematic side view showing the periphery of the gap in FIG. 1 together with a schematic state in which the coating liquid is discharged. Schematic side view showing an apparatus for measuring the elongation of a coating solution In Experimental example 1, the photograph which shows an example of the state in which the bulging part and extension part of the coating liquid are formed In Experimental example 1, the schematic side view which shows typically an example of the state in which the bulging part and extension part of a coating liquid are not formed In Experimental example 1, the schematic side view which shows typically an example of the state in which the bulging part and extension part of a coating liquid are not formed In Experimental Example 1, a photograph showing an example of a state where the bulging portion and the extending portion of the coating liquid are not formed Schematic side view showing the periphery of the gap of a conventional coating apparatus together with a schematic state in which the coating liquid is discharged

First, a coating apparatus used in the coating film forming method of one embodiment of the present invention will be described.

As shown in FIG. 1 and FIG. 2, the coating apparatus 1 used in the coating film forming method of the present embodiment is
The coating liquid 23 is discharged from the discharge port 3aa to the coating object 21 having a discharge port 3aa for discharging the coating liquid 23 and moving relative to the discharge port 3aa. It has a coating part 3 to work on,
The coating unit 3 is configured to solidify the coating solution 23 applied to the workpiece 21 to form a coating film 25.
In the coating apparatus 1, when the coating liquid 23 having a predetermined elongation degree is discharged from the discharge port 3aa to the workpiece 21, the coating liquid 23 swells on the discharge port 3aa side. A bulging portion 23a that extends, and an extending portion that extends obliquely toward the downstream side in the moving direction M of the workpiece 21 so as to taper from the bulging portion 23a to the workpiece 21. 23b is formed so as to maintain a state of connecting the discharge port 3aa and the workpiece 21 while forming a bead having 23b.
The coating apparatus 1 is arranged between the discharge port 3aa and the workpiece 21 so that the bulging portion 23a does not contact the workpiece 21 according to the size of the bulging portion 23a. The gap G is configured to be adjusted.

The coating apparatus 1 further includes a solidifying unit 13 that solidifies the coating liquid 23 applied by the coating unit 3 to form a coating film 25.

The coating apparatus 1 further includes a support portion 15 that moves relative to the coating portion 3 in the longitudinal direction of the workpiece 21 while supporting the workpiece 21 on the surface.

Although it does not specifically limit as the to-be-coated article 21, For example, a strip | belt-shaped thing as shown in FIG. 1 is mentioned, For example, a strip | belt-shaped sheet | seat member etc. are mentioned.
An example of such a sheet member is a resin film. Moreover, as a resin film, the following resin films etc. are mentioned, for example.
That is, the resin film is not particularly limited, and can be appropriately selected depending on the application. For example, as resin films used for optical applications, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, polycarbonate polymers, acrylic polymers such as polymethyl methacrylate, polystyrene Styrene polymer such as acrylonitrile-styrene copolymer, polyethylene, polypropylene, polyolefin having cyclic or norbornene structure, olefin polymer such as ethylene-propylene copolymer, vinyl chloride polymer, amide such as nylon and aromatic polyamide A film made of a transparent polymer such as a base polymer can be suitably used.
Furthermore, resin films used for optical applications include imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral. A film made of a transparent polymer such as a polymer, an arylate polymer, a polyoxymethylene polymer, an epoxy polymer or a blend of the above-mentioned polymers can also be exemplified.
The workpiece 21 will be described later.

The support portion 15 supports the workpiece 21 that moves in the longitudinal direction from the opposite side of the coating portion 3. The coating liquid 23 is applied to the workpiece 21 that is supported by the support portion 15 and moves relative to the coating portion 3.
Examples of the support portion 15 include a roll.

In the present embodiment, the support portion 15 is configured so that the workpiece 21 is relatively moved from one side (upper side in FIG. 1) to the other side with respect to the discharge port 3aa at a position facing the discharge port 3aa of the coating unit 3. (Below FIG. 1).

The solidifying unit 13 is configured to form the coating film 25 by solidifying the coating liquid 23.
The coating film 25 is formed by being solidified by the solidified portion 13. The solidification part 13 should just be what can solidify the coating liquid 23, and is not specifically limited. The solidifying part 13 is appropriately set according to the type of the coating liquid 23 and the like.

In this embodiment, a die having a slot 8 is employed as the coating unit 3. The coating apparatus 1 provided with a die in this way is called a die coater.

The coating unit 3 discharges the coating liquid 23 from the discharge port 3aa of the slot 8 to apply the coating liquid 23 onto the workpiece 21 that is relatively moving.
The coating unit 3 is disposed so that the discharge port 3aa of the slot 8 faces sideward (horizontal direction), and is applied to the workpiece 21 that is moving up and down relative to the discharge port 3aa. The coating liquid 23 is discharged. The coating liquid 3 is supplied to the coating part 3 from a container (not shown) for the coating liquid 23 via a pipe (not shown) and a pump (not shown).

Specifically, the coating unit 3 includes an upstream die block 5 and a downstream die block 7 arranged to face the upstream die block 5. The coating part 3 is formed by bringing the upstream die block 5 and the downstream die block 7 together. By bringing the two

die blocks

5 and 7 together, the manifold 9 in which the coating liquid 23 supplied by a pump (not shown) is stored and the manifold 9 toward the leading edge are provided between them. A slot 8 is formed. Further, a gap between the upstream lip portion 5 a that is the leading edge of the upstream die block 5 and the downstream lip portion 7 a that is the leading edge of the downstream die block 7 becomes the discharge port 3 aa of the slot 8. ing.

The upstream lip portion 5 a and the downstream lip portion 7 a are disposed so as to be positioned on a plane perpendicular to the radial direction R of the support portion 15. The slot 8 is arranged in parallel with the radial direction R of the support portion 15.
The interval between the discharge ports 3aa, that is, the length (slot width) in the moving direction M of the workpiece 21 is not particularly limited and can be set as appropriate.
For example, if the slot width is too small, the variation in the processing accuracy of the slot 8 will have an adverse effect on the variation in the wet thickness of the coating film 25, and the variation may be unacceptable. On the other hand, if the slot width is too large, the internal pressure of the die is lowered, and the coating liquid 23 cannot be uniformly distributed in the width direction inside the die, so that there is a possibility that variation in the wet thickness of the coating film 25 cannot be allowed.
Considering this viewpoint, for example, the slot width is preferably 0.05 to 1.5 mm, more preferably 0.1 to 1.5 mm, and further preferably 0.3 to 1.2 mm. In particular, as shown in the examples to be described later, when the slot width is 0.3 to 1.2 mm, even if the slot width is changed within this numerical range, the coating condition range does not change. This is also preferable.

The smaller the length of the downstream lip portion 7a, the smaller the bulging portion 23a, and accordingly, the workpiece 21 is maintained while the bulging portion 23a and the workpiece 21 are not in contact with each other. And the discharge port 3aa can be reduced in distance (gap) G. Considering this viewpoint, the length of the downstream lip 7a is preferably 0.1 mm or more and 4 mm or less.
The gap G is preferably 2.5 to 20 times, and more preferably 3 to 15 times the thickness of the coated coating solution 23 before solidification (wet thickness of the coating film 25). The gap G is preferably 0.5 to 2 mm, and more preferably 0.5 to 1.5 mm.

FIG. 1 shows a mode in which the coating unit 3 continuously applies the coating liquid 23 to the strip-shaped coated object 21 that moves relatively. The aspect of applying the coating liquid 23 is not limited to the aspect of FIG. FIG. 1 shows a mode in which the workpiece 21 moves clockwise, but the moving direction of the workpiece 21 is not particularly limited.

Next, the coating film forming method of the present embodiment using the coating apparatus 1 will be described.

The coating film forming method of the present embodiment has a discharge port 3aa for discharging the coating liquid 23, and the discharge port 3aa is applied to an object to be coated 21 that moves relative to the discharge port 3aa. In this method, the coating liquid 23 is applied to the workpiece 21 to form a coating film by using the coating apparatus 1 that discharges the coating liquid 23 to apply the coating liquid 23.

In the coating film forming method, the coating liquid 23 having a predetermined elongation is used. That is, a material capable of forming a bead having the following shape is used.
In the coating film forming method, when the coating liquid 23 is being discharged from the discharge port 3aa to the object to be coated 21, a bulging portion 23a that swells on the discharge port 3aa side, While forming a bead having an extended portion 23b extending obliquely toward the downstream side in the moving direction M of the workpiece 21 so as to taper from the protruding portion 23a to the workpiece 21, The coating liquid 23 is applied to the coating object 21 while maintaining a state where the discharge port 3aa and the coating object 21 are connected.

Moreover, in the coating film forming method, the discharge port 3aa and the article to be coated are arranged so that the bulging part 23a does not contact the article to be coated 21 according to the size of the bulging part 23a. The coating liquid 23 is applied to the workpiece 21 by adjusting the gap G between the coating liquid 21 and the workpiece 21.

Specifically, the coating film forming method of this embodiment is:
Coating of the coating apparatus 1 using the coating liquid 23 having the above-described elongation and adjusting the gap G so that the bulging portion 23a does not contact the workpiece 21 according to the size of the bulging portion 23a. A step of discharging the coating liquid 23 from the discharge port 3aa of the section 3 and applying the coating liquid 23 to the workpiece 21 moving relative to the discharge port 3aa;
And a step of solidifying the coating liquid 23 applied to the workpiece 21 to obtain a coating film 25.

More specifically, in the coating film forming method of the present embodiment, first, the coating liquid 23 that connects the discharge port 3aa and the article to be coated 21 is the above-described bulging portion 23a and extending portion 23b. In accordance with the type and properties of the coating liquid 23, the coating liquid 23 from the discharge port 3 aa is formed so that a bead having a thickness is formed and the bulging portion 23 a is not in contact with the workpiece 21. The discharge amount, the moving speed of the workpiece 21 and the arrangement of the coating unit 3 with respect to the workpiece 21 are set. In setting the arrangement of the coating portion 3, the coating liquid 23 having the above-described elongation is used, and a gap is provided so that the bulging portion 23 a does not contact the workpiece 21 according to the size of the bulging portion 23 a. Adjust G. Then, under the set conditions, the coating liquid 23 is discharged from the discharge port 3aa of the coating unit 3 to the object to be coated 21 for coating. Next, the coating liquid 23 applied on the workpiece 21 is solidified by the solidifying unit 13 to obtain a coating film 25.

The shape of the bulging portion 23 a and the extending portion 23 b of the coating liquid 23 is different from the discharge port 3 aa according to the type of the coating liquid 23, the wet thickness T of the coating film 25, and the moving speed of the workpiece 21. It is determined by adjusting the gap G with the workpiece 21.

The coating liquid 23 contains a solidifying component, and is applied to the object 21 to be solidified on the object 21.

The kind of the coating liquid 23 is a predetermined degree of elongation such that the coating liquid 23 that connects the discharge port 3aa and the workpiece 21 has a shape having the bulging portion 23a and the extending portion 23b. Can be set as appropriate.

Here, as shown in FIG. 3, the extension degree is rotated at a rotational speed of 30 m / min at a position 1 mm away from the opening of a cylindrical member (cylindrical member for measuring the extension degree) having an inner diameter of 2 mm. When the coating liquid 23 is discharged at a speed of 5 g / min to a roll (a roll for measuring the degree of elongation) and the distance between the opening of the cylindrical member and the roll (measurement gap D) is increased from 1 mm This is a numerical value (mm) representing the distance between the opening and the roll when the coating liquid 23 connecting the opening and the roll is cut.
When measuring the elongation, the temperature of the coating solution 23 is set to 23 ± 2 ° C. in an environment of room temperature 23 ° C. and relative humidity 50% RH.
The elongation degree of the coating liquid 23 is preferably 2 mm or more, and more preferably 5 mm or more, in that it tends to have a shape having the bulging portion 23 a and the extending portion 23 b.

When the elongation degree of the coating liquid 23 is 2 mm or more, the coating liquid 23 is sufficiently easily stretched. Therefore, it is easy to form the bulging portion 23a so as not to come into contact with the article 21 to be coated. It becomes easy to form the extending part 23b without.
Thus, formation of the bulging part 23a and the extension part 23b becomes easy.
Therefore, it is possible to more reliably obtain the coating film 25 in which the deterioration in quality due to the coating unevenness is suppressed.

The upper limit of the degree of elongation is not particularly limited, and can be set as appropriate. For example, when the degree of elongation of the coating liquid 23 becomes too large, the liquid of the coating liquid is deteriorated, and due to this, the handling property of the coating liquid tends to deteriorate. Therefore, for example, considering the viewpoint of suppressing the occurrence of such defects, the degree of elongation of the coating liquid 23 is preferably 100 mm or less, and more preferably 50 mm or less.

Examples of the coating solution 23 include a polymer solution, and examples of the material used as the solidifying component include a thermosetting material, an ultraviolet curable material, and an electron beam curable material.

Specific examples of the coating liquid 23 include an adhesive.
Among these, as the coating liquid 23, for example, an acrylic polymer is preferable. By using this, there is an advantage that a polarizing plate can be produced.

The viscosity of the coating liquid 23 is preferably 0.1 Pa · s or more and 100 Pa · s or less, more preferably 0.5 Pa · s or more and 20 Pa · s or less, and further preferably 1 Pa · s or more and 20 Pa · s or less. It is. Such a viscosity is a value measured by a measuring method described in Examples described later.
When the viscosity of the coating liquid 23 is 0.1 Pa · s or more, there is an advantage that the coating film is hardly affected by drying.
When the viscosity of the coating liquid 23 is 100 Pa · s or less, there is an advantage that a known pump can be used widely and the handling property of the coating liquid is excellent.

The density of the coating liquid 23 is preferably 700 ~ 1500kg / ^{m 3,} more preferably 800 ~ 1400kg / ^{m 3,} more preferably 800 ~ 1000kg / ^{m 3.} Such a density is a value measured by a measuring method described in Examples described later.

The thickness (the wet thickness of the coating film 25) T of the coated coating solution 23 is not particularly limited, and can be set as appropriate. The thickness T is adjusted, for example, by adjusting at least one of the discharge amount of the coating liquid 23 from the coating unit 3 and the moving speed of the workpiece 21 according to the viscosity of the coating liquid 23. obtain.
The thickness T of the coated coating solution 23 is preferably 1 μm or more and 500 μm or less, and more preferably 10 μm or more and 300 μm or less.
The thickness T is a value measured by the measurement method described in the examples described later.

The discharge amount (flux) of the coating liquid 23 from the discharge port 3aa of the coating unit 3 can be, for example, 8.3 × 10 ⁻⁸ to 2.5 × 10 ⁻³ m ² / s.
The discharge amount of the coating liquid 23 from the discharge port 3aa can be adjusted, for example, by adjusting the supply speed of the coating liquid supplied to the coating unit 3 by the pump (not shown).

The thickness of the object to be coated 21 is not particularly limited, but is preferably 5 to 500 μm, for example.
Although FIG. 1 shows an aspect in which the article to be coated 21 is a long and flexible object, other aspects in which the article to be coated 21 is a single plate or inflexibility are shown. An aspect can also be employ | adopted.

The moving speed of the workpiece 21 can be adjusted, for example, by adjusting the rotational speed of the support portion 15. Such a moving speed is preferably 5 to 300 m / min, more preferably 10 to 100 m / min, still more preferably 10 to 50 m / min.
When the moving speed of the workpiece 21 is 5 m / min or more, there is an advantage that the drive system is stabilized.
When the moving speed of the object to be coated 21 is 300 m / min or less, it is difficult for air to enter between the object to be coated 21 and the coating liquid 23. There is an advantage that meandering due to air entrainment between them can be suppressed.

As described above, in the coating film forming method of the present embodiment, the coating liquid 23 has a viscosity of 1 to 20 Pa · s, a density of 800 to 1000 kg / m ³ , and an object to be coated 21. It is more preferable that the moving speed is 5 to 50 m / min.

The gap G between the object to be coated 21 and the discharge port 3aa may be set as appropriate so that the bulging portion 23a does not contact the object to be coated 21, and is not particularly limited. 0.5 to 2 mm is preferable, and 0.5 to 1.5 mm is more preferable.

Since the coating apparatus according to this embodiment is configured as described above, it has the following advantages.

As a result of intensive studies by the present inventors, the following findings have been found.
That is, when coating is performed as shown in FIG. 8 (proximity coating), there is a risk that a foreign matter is caught in the gap.

Here, if it is going to form a coating film continuously, it is necessary to join to-be-coated objects, and to apply to the joined to-be-coated object. In this case, if the gap is small, the seam may be caught in the gap, so that it may be necessary to temporarily retract the object to be coated or the coating portion. If it does so, it will lead to the fall of workability.

In addition, when the object to be coated is moved while being supported by a roll, if the gap is small, the variation in roll processing accuracy (cylindricity, deflection, deflection, etc.) affects the wet thickness of the coating film. Since the influence becomes large, there is a possibility that the thickness of the obtained coating film varies.

On the other hand, if the gap is increased as in the coating apparatus of Patent Document 1, the above-described problems caused by the proximity coating can be solved.

However, in Patent Document 1, unlike the coating apparatus of FIG. 8, the coating liquid is ejected straight and in a film form. For this reason, when applying the coating liquid to the object to be coated, the variation in the processing accuracy of the slot in the width direction of the object to be coated has a great influence on the variation in the wet thickness of the coating liquid. There is a possibility that a coating film having unevenness of work may be obtained.

Therefore, the inventors of the present invention have further studied earnestly by paying attention to the appearance shape of the coating liquid existing from the discharge port to the object to be coated.

As a result, when the coating liquid is discharged from the discharge port, the coating liquid (bead) connecting the discharge port and the object to be coated swells on the discharge port side, and the swelled portion. When it has a shape having an extending part that extends from the protruding part to the object to be coated on the downstream side in the moving direction of the object to be coated, the object can be coated without causing uneven coating. It has been found that a coating liquid can be applied to a workpiece. In addition, such a shape uses a coating liquid having a degree of elongation such that the bulging part and the extending part are formed, and the interval between the discharge port and the object to be coated is set according to the coating liquid. It has been found that it can be realized by adjusting.

On the other hand, in the proximity coating as shown in FIG. 8, the bulging portion is not formed.
On the other hand, even if the gap is larger than the proximity coating, if the size is not sufficient, for example, as shown in FIG. As a result, the variation in wet thickness increases both in the direction of movement of the article to be coated and in the direction perpendicular to the movement direction (width direction), which may cause uneven coating. If the gap becomes too large, as shown in FIGS. 6 and 7, the extended portion is interrupted (the discharge port and the object to be coated are not connected by the coating liquid), and the coating becomes impossible. Even if it can be applied, streaky coating unevenness may occur.

Thus, when the shape of the coating liquid in the gap is the specific shape, it has been found that it is possible to obtain a coating film in which deterioration in quality due to coating unevenness is suppressed. It came to complete the coating film formation method of embodiment.

That is, the coating film forming method of this embodiment is
The coating liquid 23 is discharged from the discharge port 3aa to the coating object 21 having a discharge port 3aa for discharging the coating liquid 23 and moving relative to the discharge port 3aa. A coating film forming method for forming a coating film 25 by applying the coating liquid 23 to the workpiece 21 using the coating apparatus 1 to be worked,
When the coating liquid 23 having a predetermined elongation is used and discharged from the discharge port 3aa to the object to be coated 21, a bulging portion 23a that swells on the discharge port 3aa side, The discharge port 3aa is formed while forming a bead having an extended portion 23b extending downstream in the moving direction M of the workpiece 21 so as to taper from the bulging portion 23a to the workpiece 21. And applying the coating liquid 23 to the object to be coated 21 while maintaining a state of connecting the object 21 and the object to be coated 21, and
According to the size of the bulging portion 23a, the gap G between the discharge port 3aa and the workpiece 21 is adjusted so that the bulging portion 23a does not come into contact with the workpiece 21. In this method, the coating liquid 23 is applied to the workpiece 21.

According to such a configuration, the gap G is larger than that of the conventional proximity coating as shown in FIG. 8, so that it is possible to suppress the occurrence of coating unevenness due to the gap G being too small.
Further, although the gap G is larger than that of the proximity coating, if the size is not sufficient, the swelled portion (swelled portion) 23a of the coating liquid 23 may come into contact with the workpiece 21. However, by adjusting the gap G as described above, it is possible to suppress the occurrence of coating unevenness due to the variation in the wet thickness of the coating film 25 caused by this contact.
Furthermore, it is possible to suppress the occurrence of coating unevenness caused by the coating liquid 23 being interrupted, which is generated when the gap G is too large.
Moreover, compared to the case of Patent Document 1 in which the slot width needs to be reduced so that the coating liquid 23 is ejected straight and in the form of a film from the discharge port 3aa, there is a bulging portion 23a and an extending portion 23b. Since it becomes possible to discharge the coating liquid 23 by increasing the slot width so as to weaken the momentum of discharging the coating liquid 23 to the extent obtained, the variation in the wet thickness of the coating film 25 occurs accordingly. Can be suppressed.
Thus, the coating unevenness caused by the gap G being too small, or the coating unevenness caused by the coating liquid 23 colliding with the workpiece 21 with a large gap G can be suppressed.
Therefore, it is possible to obtain the coating film 25 in which deterioration in quality due to coating unevenness is suppressed.

In the coating film forming method of this embodiment, it is preferable that the predetermined elongation is 2 mm or more.
By using a coating liquid having an extension degree of 2 mm or more, the coating liquid 23 can be sufficiently stretched, so that it is easy to form the bulging portion 23 a so as not to contact the workpiece 21, and it is interrupted. It becomes easy to form the extending part 23b without.
Therefore, it is possible to more reliably obtain the coating film 25 in which the deterioration in quality due to the coating unevenness is suppressed.

In the coating film forming method of the present embodiment, the gap G between the coating object 21 and the discharge port 3aa is preferably set to 0.5 to 2 mm.
By setting the gap G to 0.5 mm or more, it is possible to further suppress appearance defects, particularly point defects, of the coating film 25. By setting the gap G to 2 mm or less, winding failure (ear height) Can be further suppressed.

In the coating film forming method of the present embodiment, it is preferable that the interval (slot width) of the discharge ports 3aa is 0.05 to 1.5 mm.
Here, if the interval between the discharge ports 3aa is too small, the variation in the processing accuracy of the slot 8 may have an adverse effect on the variation in the wet thickness of the coating film 25, and the variation may be unacceptable. If the interval between the discharge ports 3aa is too large, the internal pressure of the die is lowered, and the coating liquid 23 cannot be uniformly distributed in the width direction inside the die, and there is a possibility that the variation in the wet thickness of the coating film 25 cannot be allowed. .
However, by setting the interval between the discharge ports 3aa to 0.05 mm or more, the adverse effect of the variation in the processing accuracy of the slot 8 on the wet thickness of the coating film 25 can be reduced. In addition, since the interval between the discharge ports 3aa is 1.5 mm or less, it is possible to more uniformly distribute the coating liquid 23 in the width direction inside the die while suppressing a decrease in the internal pressure of the die. 25 variation in wet thickness can be suppressed.
Therefore, it is possible to more reliably obtain the coating film 25 in which the deterioration in quality due to the coating unevenness is suppressed.

As described above, according to the present embodiment, a coating film forming method in which deterioration in quality due to coating unevenness is suppressed is provided.

The coating film forming method of the present embodiment is as described above, but the present invention is not limited to the above-described embodiment, and can be appropriately modified within the intended scope of the present invention.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the following, unless otherwise specified, all measurement environmental conditions are 23 ° C. and 50% RH.

(Materials used)
・ Coating object: Polyethylene terephthalate (PET) film (Product name: Diamond wheel, manufactured by Mitsubishi Plastics)
-Coating solution: Acrylic polymer solutions A to H (see Table 1), Solvent: Toluene, Ethyl acetate

(Density measurement method)
The density of the coating solution was measured by using the density measuring function of a Coriolis flow meter (Promass 83F, manufactured by Endless Hauser).

(Measurement method of viscosity)
Rheometer (MCR302, jig: cone plate with a diameter of 50 mm, angle 1 °, manufactured by Anton Paar) equipped with a jig (cone plate with a cone diameter of 25-50 mm and a cone angle of 0.5-2 °) Was used to measure the viscosity of the coating solution at a temperature of 21 to 25 ° C. and a shear rate of 1 (1 / s).

(Measurement method of elongation)
As shown in FIG. 3 described above, a roll (extension degree) that rotates at a rotational speed of 30 m / min at a position 1 mm away from the opening of a cylindrical member (cylindrical member for measuring extension) having an inner diameter of 2 mm. When the coating liquid 23 is discharged at a speed of 5 g / min and the distance between the opening of the cylindrical member and the roll (measurement gap D) is increased from 1 mm, the opening and the roll A numerical value (mm) representing the distance between the opening and the roll when the coating solution 23 tying was cut. During the measurement, the temperature of the coating solution 23 was set to 23 ° C. ± 2 ° C.

(Experimental example 1)
Using the above materials, the coating solution was discharged onto the article to be coated under the conditions described below and in Table 1, and the coating state was examined by the following method. The results are shown in Table 1. Moreover, the result about the coating state in case a gap is 1.0 mm is shown in FIG. 4, the result about the coating state in case a gap is 0.2 mm is shown in FIG. The result about a coating state is shown in FIG.6 and FIG.7.

(Coating conditions)
・ Discharge rate (flux) of coating liquid: 4.2 × 10 ⁻⁵ m ² / s
・ Slot width: 0.6mm
・ Movement speed of workpiece: 25 m / min
・ Length of downstream lip of coating part: 1.0mm
-Wet thickness of coating film: 100 μm
・ Coating width: 150mm
-Distance (gap) between the object to be coated and the discharge port: 0.2 to 5.0 mm

(Measurement method of wet thickness of coating film)
The wet thickness of the coating film was measured in-line using a spectral interference thickness meter (Si-T, manufactured by Keyence Corporation).

(Evaluation of coating state)
-Existence of formation of bulging part and extension part Discharged coating liquid by visually observing the coating liquid discharged from the coated part between the coated part and the object to be coated Whether or not the bulging portion and the extending portion were formed was examined and evaluated as follows.
○: A bulging portion and an extending portion are formed, and the coating state is good.
Δ: A bead was formed, but a bulging portion and an extending portion were not formed, and a so-called proximity coating state was obtained.
*: Since the area | region which should become a bulging part is contacting the to-be-coated object, the bead is not formed and the coating state is unsatisfactory.
X: The bead is not formed because the coating liquid hangs down, and therefore, the coating cannot be performed and the coating state is poor.

-Appearance state of the coating liquid before being solidified applied to the object to be coated Visually observe the coating liquid (wet state coating film) before being applied to the object and solidified By observing, the appearance state of the coating solution was examined and evaluated as follows.
(Double-circle): The external appearance defect has not generate | occur | produced in the coating liquid before solidifying applied to the to-be-coated article, and the external appearance is very favorable.
○: Appearance defects (so-called ear heights at which both ends rise) that cannot be wound up in the coating solution before solidification applied to the object to be coated have not occurred, point defects, streaks Other appearance defects such as unevenness are not generated, and the appearance is good.
(Triangle | delta): The external appearance defect (point defect) has generate | occur | produced in the coating liquid before solidifying applied to the to-be-coated article, and the external appearance is unsatisfactory.
*: Appearance defects (streaks, unevenness) have occurred in the coating liquid before solidification applied to the object to be coated, and the appearance is poor.
X: Appearance defects (ear heights) that cannot be wound up are generated in the coating liquid before solidification applied to the object to be coated, and the appearance is poor.
-: The coating film does not form because the coating liquid does not reach the workpiece.

As a result, as shown in Table 1 and FIG. 4, when the coating liquid had a bulging portion and an extending portion in the gap, no coating failure was observed.

As shown in Table 1, FIG. 6 and FIG. 7, when the gap is 5.0 mm, the coating liquid cannot connect the discharge port and the object to be coated, and the coating liquid is interrupted. A coating film was not formed.

As shown in Table 1 and FIG. 5, when the gap was 0.2 mm, it was in the state of proximity coating, and appearance defects (point defects) occurred. In the acrylic polymer solutions D, E, and F, when the gap is 0.5 mm, the coating liquid that connects the discharge port and the object to be coated has a bulging portion and an extending portion, but the bulging Such a portion contacted the object to be coated, and no bulging portion was formed.

In addition, for a sample having a gap of 2.5 mm and an appearance defect with a high ear height, the coating liquid applied to the object to be coated was solidified, and then the object to be wound was wound. Occurred and could not be wound well. As a result, it was found that when the gap was 2.5 mm or more, an appearance defect with a high height occurred and a winding failure could occur.

(Experimental example 2)
Using the acrylic polymer solutions D and G of Experimental Example 1 (see Table 1) and changing the slot width to 0.3 mm and 1.2 mm, the coating liquid was applied to the object to be coated in the same manner as Experimental Example 1. The coating state was evaluated. The results are shown in Table 2. In Table 2, in the acrylic polymer solutions D and G, the result in the case of the slot width of 0.6 mm is the result of the experiment example 1.

(Experimental example 3)
Experimental Example 1 except that the length of the downstream lip is changed to 0.5 mm and 1.5 mm when the acrylic polymer solution D of Experimental Example 1 (see Table 1) is used and the gap is 1.5 mm. In the same manner as described above, the coating liquid was applied to the object to be coated, and the coating state was evaluated. The results are shown in Table 3. In Table 3, the result in Experimental Example 1 is transcribed as the result when the length of the downstream lip portion is 1.0 mm.

As shown in Table 3, even if the length of the downstream lip portion was changed, the bulging portion and the extending portion could be formed, and no coating failure was observed.

(Reference Example 1)
As shown in Table 4 below, coating is performed so that the dimensionless number M in Patent Document 1 is larger than 0.2 (M = (ρ · U · hw2) / (μ · d)> 0.2). A liquid was selected, and each condition was set as shown in Table 4 and below. When coating was performed on the following coated objects under each set condition, the coating liquid was dripping and could not be coated.

・ Coating object: Polyethylene terephthalate (PET) film (trade name: Diamond wheel, manufactured by Mitsubishi Plastics)

-Coating liquid (1): acrylic polymer solution, solvent: toluene, ethyl acetate Polymer average weight molecular weight: about 800,000 Polymer concentration: 2.6 wt%
(Coating conditions)
Coating liquid discharge rate (flux): 5.0 × 10 ⁻⁶ to 1.0 × 10 ⁻⁴ m ² / s
Slot width: 19-25μm
Movement speed of the object to be coated: 25 m / min
Length of downstream lip of coating part: 1.0mm
Wet thickness of coating film: 10-200μm
Coating width: 150mm
Distance (gap) between workpiece and discharge port: 0.5mm

-Coating liquid (2): Glycerin aqueous solution, Solvent: Water Glycerin concentration: 60 wt%
(Coating conditions)
Coating liquid discharge rate (flux): 8.3 × 10 ⁻⁶ to 1.33 × 10 ⁻⁴ m ² / s
Slot width: 19-75μm
Movement speed of the object to be coated: 25 m / min
Length of downstream lip of coating part: 1.0mm
Wet thickness of coating film: 5-80μm
Coating width: 150mm
Distance (gap) between workpiece and discharge port: 0.5mm

Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the features of the embodiments and examples. The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the embodiments and examples described above but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

1: coating device, 3: coating part, 3a: tip part, 3aa: discharge port, 5: first die block, 7: second die block, 7a: downstream lip part, 8: slot, 13 : Solidification part, 15: support part, 21: article to be coated, 23: coating liquid, 25: coating film

Claims

A coating apparatus that has a discharge port for discharging a coating liquid, and discharges the coating liquid from the discharge port to be applied to an object to be moved relative to the discharge port. A coating film forming method of forming a coating film by applying the coating liquid to the object to be coated,
Using the coating liquid having a predetermined elongation, when the coating liquid is discharged from the discharge port to the coated object, a bulging portion that swells on the discharge port side, and Forming the bead having an extended portion extending downstream in the moving direction of the coated object so as to taper from the bulging portion to the coated object, and the discharge port and the coated object; Applying the coating liquid to the object to be coated while maintaining the state of tying, and
According to the size of the bulging portion, the gap between the discharge port and the coating object is adjusted so that the bulging portion does not contact the coating object. A method for forming a coating film, wherein the coating solution is applied.
The coating film forming method according to claim 1, wherein the predetermined elongation is 2 mm or more.
The coating film forming method according to claim 1 or 2, wherein an interval between the coating object and the discharge port is set to 0.5 to 2 mm.
The coating film forming method according to claim 1 or 2, wherein an interval between the discharge ports is 0.05 to 1.5 mm.
The coating film forming method according to claim 3, wherein the interval between the discharge ports is 0.05 to 1.5 mm.