JP2004050025A - Die head for coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die head for coating capable of carrying out high precision coating. <P>SOLUTION: In the die head for coating 12 for discharging a coating liquid while moving relative to a base material 1 and applying the coating liquid to the surface of the base material 1, the high precision coating is performed by providing a surface layer 13 having poor wettability to the coating liquid on a tip end side surface 12c to make the contact angle with the coating liquid larger than that of a lip part 12b with the coating liquid to prevent the instability caused by the spreading of a bead 3 to the tip end side surface 12c in the coating and preventing stripes or step nonuniformity which tend to occur on a coating layer 4. <P>COPYRIGHT: (C)2004,JPO

Description

（２）使用塗布液
有機溶剤系カラーレジスト
粘度：　５ｃｐ
表面張力：２５ダイン／ｃｍ
（３）塗布条件
図４に示すように、ダイヘッド１２を下向きに配置し、その下方を基材１を水平に、８０ｍｍ／秒の速度を移動させて、塗布液を約１０μｍ程度の厚さに塗布した。
（４）結果
塗布終了後、形成された塗布層を目視検査したところ、すじや段むらは見られなかった。その塗布層を乾燥させた後、厚さを測定したところ、厚さは１．５μｍであり、塗布厚さのばらつきは、±３％以下であった。従って、得られた塗布層は、カラーフィルタに要求される厚さむらの許容範囲内であり、従って、従来のようにスピンをかけることなく、カラーフィルタに用いことができることを確認できた。
【００１８】
【発明の効果】
以上のように、本発明の塗工用ダイヘッドは、ダイヘッドの先端側面の塗布液に対する接触角を、リップ部の塗布液に対する接触角よりも大きくしたことにより、塗布動作中、ビードの最外部の液がダイヘッドから離れる点を、先端側面とリップ部との境界線であるエッジ部に保持し、ビードを安定させることができ、塗布層に生じがちであったすじや段むらを防止でき、厚さむらをきわめて小さく抑制できるという効果を有している。そして、本発明のダイヘッドは高精度塗布が可能であるので、これを、液晶用カラーフィルタの製造におけるレジスト塗布に用いることにより、従来行っていたスピン工程を省略でき、コストダウンを図ることができるといった効果が得られる。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る塗工用ダイヘッドの概略斜視図及びその一部の拡大断面図
【図２】図１に示すダイヘッドの先端部を拡大して示す概略斜視図
【図３】（ａ）、（ｂ）は図１に示すダイヘッドの製造工程を説明する概略斜視図
【図４】図１のダイヘッドで基材表面に塗布する状態を示す概略断面図
【図５】本発明の他の実施の形態に係るダイヘッドの先端部の概略斜視図
【図６】本発明の更に他の実施の形態に係るダイヘッドの先端部の概略斜視図
【図７】従来のダイヘッドで基板表面に塗布する状態を示す概略斜視図
【図８】従来のダイヘッドで基板表面に塗布する状態を示す概略断面図
【図９】従来の他のダイヘッドで基板表面に塗布する状態を示す概略断面図
【符号の説明】
１　基材
２　ダイヘッド
３　ビード
４　塗布層
５　チャック台
１２　ダイヘッド
１２ａ　スリット
１２ｂ　リップ部
１２ｃ　先端側面
１３　表面層
１４　境界線[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for applying a coating liquid with high accuracy to a flat substrate such as a glass plate using a die head.
[0002]
[Prior art]
Conventionally, in a manufacturing process of a liquid crystal color filter, a liquid resist is applied to a base material such as a glass plate to form layers of each color of R, G, and B, or to form a surface protective layer and a pillar. Coating has been done. Since high-precision coating is required for coating these resists, a spin method is generally used in which an excessive amount of liquid droplets is supplied to the surface of the base material, and the base material is rotated at a high speed to spread the resist thinly and uniformly. . However, in this method, most of the supplied resist is scattered around, so that there is a problem that the consumption of the resist increases and the cost increases. Therefore, as an alternative method, as shown in FIG. 7, the substrate 1 is held on a chuck base 5 and the tip of a coating die head 2 is arranged close to the surface of the substrate 1 so that the substrate 1 is A liquid resist is discharged from the die head 2 while being moved relatively to the substrate 2, and the resist is applied to the surface of the substrate to form a coating layer 4. Immediately thereafter, the substrate 1 is rotated at a high speed to apply the coating layer 4. There is also known a method of making the thickness of the film uniform. Here, after the resist is applied to the base material 1, the base material 1 is rotated at a high speed to make the film thickness uniform. This is because unevenness 4b occurs, and unevenness of the coating thickness cannot be suppressed within an allowable range. However, this method requires two steps of a coating step using a die head and a subsequent spinning step, so that there is a problem that the cost is also high.
[0003]
Next, the cause of the unevenness of the coating thickness in the coating by the die head 2 will be described. As shown in FIG. 8, the die head 2 is provided with a slit 2a for discharging a resist to be coated (referred to as a coating liquid), lip portions 2b formed substantially at right angles to the slits on both ends of the slit, and located outside the slit. And a tip side surface 2c inclined with respect to the lip portion 2b. During application, a pool (bead) 3 of a coating liquid is formed between the lip portion 2b and the base material 1, and the bead 3 is applied. The liquid is applied to the surface of the substrate 1. During coating, if the bead 3 is stable and has a constant shape, that is, the points A and B where the outermost liquid of the bead 3 separates from the die head 2 are the lip portion 2b and the tip side surface 2c of the die head 2. If it is held on the boundary line (edge portion) of the coating layer 4, the thickness unevenness of the coating layer 4 hardly occurs. However, actually, the points A and B at which the outermost liquid of the bead 3 separates from the die head 2 are not held at the edge of the die head 2 but wrap around from the lip 2b to the tip side surface 2c as shown by an arrow C, It often moves on the tip side surface 2c, or moves at the lip portion 2b as shown by the arrow D, and the bead 3 often changes unstablely. When the movement of the points A and B occurs locally in the width direction of the die head 2, a streak 4a (see FIG. 7) extending in the movement direction of the base material is generated. The step unevenness 4b extending in the lateral direction was generated.
[0004]
Therefore, in order to stabilize the bead 3 by keeping the points A and B at which the outermost liquid of the bead 3 separates from the die head 2 and stabilize the bead 3, as shown in FIG. A die head 2A in which an edge 2d is formed is known. However, the die head 2A having this configuration can stabilize the bead 3 to some extent as compared with the die head 2 shown in FIG. 7, but at the points A and B where the outermost liquid of the bead 3 separates from the die head 2. Unstable movement cannot be sufficiently suppressed, and therefore stripes and step unevenness are reduced to some extent, and high-precision coating required at the time of manufacturing a color filter for liquid crystal cannot be performed.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coating die head capable of performing high-precision coating required when manufacturing a liquid crystal color filter.
[0006]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to stabilize beads during application using a die head.As a result, the contact angle of the tip side of the die head with respect to the coating liquid is made larger than the contact angle of the lip portion with the coating liquid. The present inventors have found that the point at which the outermost liquid of the bead separates from the die head can be held at the edge, which is the boundary between the tip side surface and the lip. In other words, the present invention provides a coating die head that discharges a coating liquid while relatively moving with respect to a base material, and adjusts a contact angle of the tip side surface to a coating liquid with a coating liquid at a lip portion. The configuration is such that the contact angle with respect to the liquid is made larger. This configuration can stabilize the bead at the time of application and prevent streaks and unevenness that tend to occur in the application layer. Thus, by using the die head of the present invention for resist coating in the production of color filters for liquid crystals, the high precision coating required for color filters for liquid crystals can be performed, and the spinning step conventionally performed can be omitted, thereby reducing costs. be able to.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The basic form of the coating die head of the present invention is configured such that the contact angle of the tip side of the die head with respect to the coating liquid is larger than the contact angle of the lip portion with the coating liquid. During coating, the beads formed between the lip portion and the base material are stabilized, and high-precision coating can be performed. Here, the difference between the contact angle of the tip side of the die head with the coating liquid and the contact angle of the lip with the coating liquid is too small, since the effect of stabilizing the bead becomes small. Is preferred. In addition, the greater the difference, the greater the effect of stabilizing the bead, and it is possible to cope with severe application conditions such as increasing the application speed. Is more preferably 10 degrees or more, and further preferably 20 degrees or more.
[0008]
As means for making the contact angle of the tip side of the die head to the coating liquid larger than the contact angle of the lip portion to the coating liquid, plating, coating or the like is performed on one or both of the tip side surface and the lip surface. The surface material of the tip side surface and the surface material of the lip portion may be made different from each other by performing a surface treatment or manufacturing the tip side surface and the lip portion as separate parts. It is also effective to make the surface roughness of the tip side surface different from the surface roughness of the lip. Further, these may be combined.
[0009]
As described above, the die head of the present invention makes the contact angle of the tip side to the coating liquid larger than the contact angle of the lip to the coating liquid, and the point at which the outermost liquid of the bead separates from the die head is referred to as the tip side face. It is held on the boundary with the lip. The straightness of this boundary line and the parallelism with respect to the slit are also important for suppressing coating unevenness, and when high-precision coating is desired as in the case of color filter production, the straightness and parallelism should be minimized. More specifically, the thickness is preferably 5 μm / m or less. Furthermore, when the boundary region between the tip side surface and the lip portion is microscopically viewed, the tip side surface and / or the lip portion does not always have a constant contact angle up to the boundary line. For example, when coating is applied to the tip side surface to increase the contact angle, even if the lip portion is masked and coated only on the tip side surface, the edge of the surface layer formed by coating is not necessarily the boundary. It does not always coincide with the line, and may not reach the boundary line or cross the boundary line in some places. For this reason, the boundary line between the region having a large contact angle and the region having a small contact angle may not exactly coincide with the boundary line between the tip side surface and the lip portion. If this difference is large, it may cause uneven coating. Therefore, when high-precision coating is desired as in the case of color filter production, the deviation between the boundary between the region with a large contact angle and the region with a small contact angle and the boundary between the tip side surface and the lip portion should be minimized. More specifically, the thickness is preferably 5 μm or less.
[0010]
The coating apparatus of the present invention, the coating die head of the above configuration, so that the coating liquid ejected by the coating die head is applied to the substrate surface, the tip of the coating die head is brought close to the substrate. And a means for relatively moving the coating die head and the base material in a state where the coating die head is placed. This configuration enables high-precision coating to be performed on the base material.
[0011]
The coating die head and the coating apparatus of the present invention can perform high-precision coating. Therefore, in the process of manufacturing a color filter for liquid crystal, a layer of each color of R, G, and B is applied to a substrate such as a glass plate. It can be used to apply a liquid resist for the formation of a surface protection layer or a column material, and can be applied with desired accuracy without adding a spin process. It goes without saying that it may be used for coating other than this purpose.
[0012]
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing a coating die head 12 according to an embodiment of the present invention and an enlarged cross-sectional view of a part thereof, and FIG. 2 is a schematic perspective view showing a tip end of the die head 12 in an enlarged manner. . This die head 12 also has a slit 12a for discharging a coating liquid to be applied, a lip portion 12b formed substantially at right angles to the slit 12a on both sides of the tip, and a lip portion 12b and a tip side surface 12c inclined with respect to 12b. The die head 12 is entirely formed of stainless steel. The width d of the lip portion 12b is usually set to about 0.3 to 0.5 mm. The lip portion 12b has a form in which the base material of the die head 12 is exposed as it is, and its surface is lapped to a roughness of about 0.1S to 0.4S. On the other hand, the tip side surface 12c is formed by lapping the surface of the base material to a roughness of about 0.1S to 0.4S, and then plating or coating a material having poor wettability with respect to the application liquid thereon to form the surface layer 13. Has formed. Therefore, the tip side surface 12c is a surface having poor wettability (large contact angle) with the coating liquid. Here, the surface layer 13 may be formed by a surface treatment such as electroless nickel plating, electroless nickel plating mixed with a fluororesin, or fluororesin coating. In selecting the material of the surface layer 13, the contact angle with the coating liquid is set to be larger than the contact angle of the lip portion 12b with the coating liquid, for example, 5 degrees or more, preferably 10 degrees or more, and more preferably. Is selected to be larger than 20 degrees. More specifically, when a liquid resist used for manufacturing a color filter for liquid crystal is used as the coating liquid, the contact angle of the lip portion 12b with the coating liquid is about 7 to 10 degrees. When formed by nickel plating, the contact angle becomes about 20 degrees, and a difference of 10 degrees or more can be secured. When the surface layer 13 is formed of a fluororesin coating, the contact angle is about 60 degrees, and a large difference of 50 degrees or more can be secured. The fluorocarbon resin alone coating can increase the contact angle compared to electroless nickel plating, but is inferior in durability.However, by mixing fluorocarbon resin into electroless nickel plating, the contact angle can be reduced by electroless nickel plating. And the durability can be improved as compared with the fluororesin coating. Therefore, the mixing ratio of nickel and fluororesin may be appropriately selected according to desired characteristics. The region where the surface layer 13 is formed may be at least a region where the coating liquid may flow around during coating.
[0013]
As shown in FIG. 2, the surface layer 13 formed on the tip side surface 12c is accurately formed up to a position corresponding to the boundary between the lip portion 12b and the surface layer 12c. Further, a boundary 14 between the lip portion 12b and the surface layer 13 of the tip side surface 12c is formed linearly, and the straightness of the boundary 14 and the parallelism to the slit 12a are 5 μm / m or less. Are made. Here, the surface layer 13 is formed accurately to a position coincident with the boundary between the lip portion 12b and the surface layer 12c, and the straightness of the boundary 14 and the parallelism to the slit 12a are set to 5 μm / m or less. As shown in FIG. 3A, the surface layer 13 is formed not only on the tip side surface 12c of the die head 12 but also on the lip portion 12b by plating, coating, or the like, and then, as shown in FIG. Then, the lip portion 12b may be polished to remove the surface layer 13 at that portion, and the boundary line 14 may have desired straightness and parallelism.
[0014]
In order to perform coating using the die head 12, as shown in FIG. 4, the tip of the die head 12 is arranged close to the surface of the base material 1 held on a chuck table (not shown), and the base material 1 is placed on the die head. The coating liquid is discharged from the die head 12 while being moved with respect to the substrate 12, a bead 3 is formed between the lip portion 12 b and the substrate 1, and the coating liquid of the bead 3 is applied to the surface of the substrate 1. Here, the tip side surface 12c of the die head 12 is configured such that the contact angle with respect to the coating liquid is larger than the lip portion 12b with which the bead 3 is in contact, and thus the wettability with respect to the coating liquid is deteriorated. During the coating, the points A and B where the outermost liquid of the bead 3 separates from the die head are held at the edge portion which is the boundary between the lip portion 12b having good wettability and the tip side surface 12c having poor wettability, and almost fluctuate. do not do. For this reason, during coating, the bead 3 is stable, and the coating layer 4 formed on the base material 1 hardly generates streaks or step unevenness which has conventionally occurred, and has extremely small thickness unevenness ( For example, the coating layer 4 (having a thickness of ± 3% or less) can be formed. For this reason, by using the die head 12 for resist coating in the production of a liquid crystal color filter, a coating with a coating accuracy required for the liquid crystal color filter (for example, unevenness in thickness is ± 3% or less of the thickness) is achieved. And the spin step conventionally performed can be omitted.
[0015]
In the above-described embodiment, the lip portion 12b is used as the surface of the base material, and the surface layer 13 having a poor wettability (a large contact angle) with respect to the coating liquid is formed on the tip side surface 12c of the die head 12. Although the contact angle is set to be larger than that of the base material 12b, the present invention is not limited to this configuration, and a surface layer of a material having good wettability is formed on the lip portion 12b, and the tip side surface 12c is the surface of the base material as it is. Alternatively, a modification may be made such that a surface layer of a material having good wettability is formed on the lip portion 12b, and a surface layer of a material having poor wettability is formed on the tip side surface 12c.
[0016]
Furthermore, the method of changing the contact angle between the lip portion 12b and the tip side surface 12c is not limited to surface treatment such as plating and coating, and can be changed as appropriate. For example, in the die head 12A shown in FIG. 5, a portion 16 forming the lip portion 12b and a portion 17 forming the tip side surface 12c are formed of different members, and the materials thereof are changed. Although the die head 12B shown in FIG. 6 is entirely made of the same material, the surface roughness of the lip portion 12b is increased so that the lip portion 12b is easily wetted with the coating liquid (the contact angle is reduced), and the tip side surface 12c is formed. The surface roughness is reduced to make it less likely to wet the coating liquid (increase the contact angle). Even with these configurations, the contact angle of the distal end side surface 12c can be made larger than the contact angle of the lip. In order to change the contact angle between the lip portion 12b and the tip side surface 12c, it is also possible to adopt a method of appropriately combining different surface materials of the lip portion 12b and the tip side surface 12c with different surface roughness. Good.
[0017]
【Example】

(2) Coating solution used Organic solvent-based color resist viscosity: 5 cp
Surface tension: 25 dynes / cm
(3) Coating conditions As shown in FIG. 4, the die head 12 is arranged downward, the base material 1 is moved horizontally under the die head 12 at a speed of 80 mm / sec, and the coating liquid is reduced to a thickness of about 10 μm. Applied.
(4) Results After the completion of the coating, the formed coating layer was visually inspected, and no streaks or unevenness was found. After drying the coating layer, when the thickness was measured, the thickness was 1.5 μm, and the variation in the coating thickness was ± 3% or less. Therefore, it was confirmed that the obtained coating layer was within the allowable range of the thickness unevenness required for the color filter, and thus could be used for the color filter without spinning as in the related art.
[0018]
【The invention's effect】
As described above, the coating die head of the present invention is such that the contact angle of the tip side of the die head with respect to the coating liquid is larger than the contact angle of the lip portion with the coating liquid, so that the outermost part of the bead during the coating operation is formed. The point at which the liquid separates from the die head is held at the edge, which is the boundary between the tip side surface and the lip, stabilizing the bead, preventing streaks and unevenness that tend to occur in the coating layer, and This has the effect that the unevenness can be extremely small. Since the die head of the present invention can perform high-precision coating, by using this for resist coating in the production of a liquid crystal color filter, the spin process conventionally performed can be omitted and cost can be reduced. Such an effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a coating die head according to an embodiment of the present invention and an enlarged cross-sectional view of a part thereof. FIG. 2 is a schematic perspective view showing a tip end of the die head shown in FIG. FIGS. 3 (a) and 3 (b) are schematic perspective views illustrating a manufacturing process of the die head shown in FIG. 1. FIG. 4 is a schematic cross-sectional view showing a state where the die head of FIG. FIG. 6 is a schematic perspective view of a tip portion of a die head according to another embodiment of the present invention. FIG. 6 is a schematic perspective view of a tip portion of a die head according to still another embodiment of the present invention. FIG. 8 is a schematic perspective view showing a state in which coating is performed on the surface; FIG. 8 is a schematic cross-sectional view illustrating a state in which coating is performed on the substrate surface with a conventional die head; FIG. [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base material 2 Die head 3 Bead 4 Coating layer 5 Chuck table 12 Die head 12a Slit 12b Lip part 12c Tip side 13 Surface layer 14 Boundary line

Claims (6)

A coating die head that discharges a coating liquid while moving relative to a base material and applies the coating liquid to the surface of the base material. In a coating die head having a formed lip portion and a tip side surface located outside thereof and inclined with respect to the lip portion, a contact angle of the tip side surface with respect to a coating liquid is determined with respect to a coating liquid of the lip portion. A coating die head having a larger contact angle. 2. The coating die head according to claim 1, wherein a contact angle of the tip side surface with respect to the coating liquid is larger than a contact angle of the lip portion with the coating liquid by 5 ° or more. 3. The coating die head according to claim 1, wherein a surface material of the tip side surface and a surface material of the lip portion are different from each other. 4. The coating die head according to claim 1, wherein the surface roughness of the tip side surface and the surface roughness of the lip portion are different from each other. The straightness of the boundary line between the tip side surface and the lip portion and the parallelism with respect to the slit are set to 5 μm / m or less, and the boundary line between the large contact angle region and the small contact angle region in the boundary region between the tip side surface and the lip portion. The coating die head according to any one of claims 1 to 4, wherein a deviation between a boundary line between the tip side surface and the lip portion is set to 5 µm or less. A coating die head according to any one of claims 1 to 5, and a tip of the coating die head close to the base material so that a coating liquid discharged from the coating die head is applied to a surface of the base material. Means for relatively moving the coating die head and the substrate in a state where the coating is performed.

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