阅读说明：本技术 涂布方法、涂布棒状头及涂布装置 (Coating method, coating rod head and coating device ) 是由 内藤胜之 信田直美 齐藤三长 齐田穰 于 2019-09-10 设计创作，主要内容包括：本发明提供即使高速地进行弯月面涂布,涂布膜厚也难以变动的涂布方法、涂布棒状头及涂布装置。在向涂布棒状头与基材之间供给涂布液而形成弯月面并使基材移动的涂布方法中,涂布方向上的棒状头涂布面剖面为凸起的曲线,在曲线的两端具有折弯点。(The invention provides an application method, an application bar head and an application device, wherein the thickness of an application film is difficult to change even if meniscus application is carried out at high speed. In the coating method in which a coating liquid is supplied between a coating rod head and a base material to form a meniscus and the base material is moved, the cross section of the coating surface of the rod head in the coating direction is a convex curve, and the curve has bending points at both ends.)

1. A coating method for forming a coating film on a surface of a base material by supplying a coating liquid between a coating rod head and the base material to form a meniscus and moving the base material, wherein,

the coating rod-shaped head has a cross section in a direction perpendicular to a longitudinal direction, the cross section having, at an outer peripheral portion:

(a) a curved portion protruding outward and corresponding to a cylindrical surface of the rod-shaped head facing the base material; and

(b) two bending points corresponding to the end parts parallel to the long side direction of the cylindrical surface at the two tail ends of the curve part,

and the curvature radius of the curved part in the section is 10-100 mm.

2. The coating method according to claim 1,

the curved portion is an arc.

3. The coating method according to claim 1 or 2,

the minimum interval between the coating rod-shaped head and the base material is 80-600 mu m.

4. The coating method according to any one of claims 1 to 3,

at least one of the two bending points has a bending angle of 90-150 degrees.

5. The coating method according to any one of claims 1 to 4,

the length of the curve part between the two bending points is 5-30 mm.

6. The coating method according to any one of claims 1 to 5,

the base material is curved in such a manner as to be convex toward the coating rod head at the formation portion of the meniscus,

r is a radius of curvature of the curved portion in the cross section of the coating rod head₁And the radius of curvature in the curved portion of the base material is defined as r₂When the temperature of the water is higher than the set temperature,

by r₀＝1/[(1/r₁)+(1/r₂)]R of₀20-80 mm.

7. The coating method according to claim 6, wherein:

r₂>r₁or is or

r₂≥200mm。

8. The coating method according to any one of claims 1 to 7,

the coating rod head is horizontally fixed, and the substrate is conveyed from bottom to top.

9. The coating method according to claim 8,

the coating liquid is supplied from the upper part of the coating rod head.

10. An application bar head for meniscus application in which a coating liquid is supplied between an application bar head and a base material to form a meniscus and the base material is moved,

the coating rod-shaped head has a cross section in a direction perpendicular to a longitudinal direction, the cross section having, at an outer peripheral portion:

(a) a curved portion protruding outward and corresponding to a cylindrical surface of the rod-shaped head facing the base material; and

(b) two bending points corresponding to the end parts parallel to the long side direction of the cylindrical surface at the two tail ends of the curve part,

and the curvature radius of the curved part in the section is 10-100 mm.

11. The coating rod head according to claim 10,

at least one of the two bending points has a bending angle of 90-150 degrees.

12. Coating rod head according to claim 10 or 11,

the length of the curve part between the two bending points is 5-30 mm.

13. An application apparatus which has a coating rod head, a base material conveying member, and a coating liquid supply member, and which is arranged so that a meniscus is formed when a coating liquid is supplied between the rod head and a base material conveyed by the base material conveying member, wherein,

the coating rod-shaped head has a cross section in a direction perpendicular to a longitudinal direction, the cross section having, at an outer peripheral portion:

(a) a curved portion protruding outward and corresponding to a cylindrical surface of the rod-shaped head facing the base material; and

(b) two bending points corresponding to the end parts parallel to the long side direction of the cylindrical surface at the two tail ends of the curve part,

and the curvature radius of the curved part in the section is 10-100 mm.

14. The coating apparatus according to claim 13,

the base material is curved in such a manner as to be convex toward the coating rod head at the formation portion of the meniscus,

r is a radius of curvature of the curved portion in the cross section of the coating rod head₁And the radius of curvature in the curved portion of the base material is defined as r₂When the temperature of the water is higher than the set temperature,

by r₀＝1/[(1/r₁)+(1/r₂)]R of₀20-80 mm.

15. The coating apparatus of claim 14, wherein:

r₂>r₁or is or

r₂≥200mm。

16. The coating apparatus according to any one of claims 13 to 15,

the coating rod head is horizontally fixed, and the substrate conveying member conveys the substrate from bottom to top.

17. The coating apparatus according to claim 16,

a coating liquid supply nozzle is disposed above the coating rod head.

18. The coating apparatus according to any one of claims 13 to 17,

the coating device further includes a member for measuring and controlling a distance between the coating rod head and the base material.

19. The coating apparatus according to any one of claims 13 to 18,

the coating device further includes a cleaning member for cleaning the coating rod head.

20. The coating apparatus according to any one of claims 13 to 19,

the coating device is also provided with a component for recovering the residual coating liquid during coating.

Technical Field

Embodiments of the present invention relate to a coating method, a coating rod head (bar head), and a coating apparatus.

Background

Organic thin-film solar cells and organic/inorganic hybrid solar cells using organic semiconductors can be applied with an inexpensive coating method for forming an active layer, and therefore are expected as low-cost solar cells. In order to realize an organic thin film solar cell or an organic/inorganic hybrid solar cell at low cost, it is required to uniformly coat a coating material forming an organic active layer or other layers. The thickness of each layer is about several nm to several 100nm, and it is required to form such a very thin layer over a large area with good uniformity. For example, a meniscus (meniscus) coating method is known as one of roll-to-roll (R2R) coating methods that can coat extremely thin layers over a large area at low cost. However, in the conventional meniscus coating method, since the distance between the base material and the coating rod head is likely to vary in the case of high-speed coating, the coating thickness is likely to vary. When a uniform coating thickness is required as in a general solar cell module, since the coating thickness is required to be less fluctuated, an improved meniscus coating method capable of obtaining a uniform coating thickness even in a high-speed coating is required.

Prior art documents

Patent document

Patent document 1: japanese patent No. 5981594

Disclosure of Invention

Problems to be solved by the invention

The invention provides an application method in which the thickness of an applied film is not easily changed even if meniscus application is performed at high speed, and an application bar head and an application apparatus capable of realizing the application method.

Means for solving the problems

The coating method of the embodiment is a coating method of forming a coating film on a surface of a base material by supplying a coating liquid between a coating rod head and the base material to form a meniscus and moving the base material, wherein,

the coating rod-shaped head has a cross section in a direction perpendicular to a longitudinal direction, the cross section having, at an outer peripheral portion:

(a) a curved portion protruding outward and corresponding to a cylindrical surface of the rod-shaped head facing the base material; and

(b) two bending points corresponding to the end parts parallel to the long side direction of the cylindrical surface at the two tail ends of the curve part,

and the curvature radius of the curved part in the section is 10-100 mm.

The coating rod head according to the embodiment is a meniscus coating rod head for supplying a coating liquid between a coating rod head and a base material to form a meniscus and moving the base material,

the coating rod-shaped head has a cross section in a direction perpendicular to a longitudinal direction, the cross section having, at an outer peripheral portion:

(a) a curved portion protruding outward and corresponding to a cylindrical surface of the rod-shaped head facing the base material; and

(b) two bending points corresponding to the end parts parallel to the long side direction of the cylindrical surface at the two tail ends of the curve part,

and the curvature radius of the curved part in the section is 10-100 mm.

Further, the coating apparatus of the embodiment has a coating rod head, a base material conveying member, and a coating liquid supply member, and each of the members is disposed so as to form a meniscus when a coating liquid is supplied between the rod head and a base material conveyed by the base material conveying member,

the coating rod-shaped head has a cross section in a direction perpendicular to a longitudinal direction, the cross section having, at an outer peripheral portion:

(a) a curved portion protruding outward and corresponding to a cylindrical surface of the rod-shaped head facing the base material; and

(b) two bending points corresponding to the end parts parallel to the long side direction of the cylindrical surface at the two tail ends of the curve part,

and the curvature radius of the curved part in the section is 10-100 mm.

Drawings

Fig. 1 is a conceptual diagram illustrating a coating method of an embodiment.

Fig. 2 is a perspective view of the coating rod head according to the embodiment.

Fig. 3 is a view showing a sectional shape of the coating rod head.

Fig. 4 is a cross-sectional view showing the relationship of the coating rod head, the planar base material, and the meniscus formed therebetween.

Fig. 5 is a conceptual diagram illustrating a coating apparatus according to an embodiment.

Detailed Description

Hereinafter, embodiments will be described with reference to the drawings.

In the embodiments, the same reference numerals are assigned to the common components, and redundant description is omitted. The drawings are schematic views for facilitating understanding of the embodiments, and although there are portions different from actual apparatuses in shape, size, ratio, and the like, they can be appropriately designed and changed by referring to the following description and known techniques.

Fig. 1 is a conceptual diagram (cross-sectional view) illustrating a coating method of an embodiment. In this coating method, a coating liquid 3 is supplied between a curved surface 1a of a coating rod head 1 facing a substrate 2 and the moving substrate 2, thereby continuously forming a coating film 6 on the substrate surface 2 a. In the embodiment shown in fig. 1, the base material 2 is moved upward from a lower side in the vertical direction, and is disposed so that the curved surface of the application bar head faces the base material surface 2 a. Then, the coating liquid 3 is supplied from the coating liquid supply nozzle 5 to the curved surface of the coating rod head, and a meniscus 4 is formed between the curved surface of the coating rod head and the base material by the surface tension of the coating liquid.

In an embodiment, the coating rod head has a specific shape. Fig. 2 is a perspective view of an application bar head used in the embodiment, fig. 3 is a cross-sectional view of the application bar head in a direction perpendicular to a longitudinal direction thereof, and fig. 4 is a view showing a state where a coating liquid 6 is introduced between the application bar head 1 and a planar base material 2 to form a meniscus 4. As shown in fig. 2, a surface 1a of the coating rod head facing the base material is a cylindrical surface protruding outward. The cylindrical surface has ridgelines 8 and 9 at its end portions parallel to the longitudinal direction of the cylindrical surface.

The shape of the coating rod head can be represented by the shape of a cross section in a direction perpendicular to the longitudinal direction. The cross-sectional shape of the device has:

(a) a curved portion protruding outward and corresponding to a cylindrical surface of the rod-shaped head facing the base material; and

(b) and two bending points corresponding to the end parts parallel to the long side direction of the cylindrical surface at the two tail ends of the curve part. And the curvature radius of the curved part in the section is 10-100 mm.

The portion of the coating rod head 1 corresponding to the surface 1a facing the substrate 2 is a curved portion 7. The curved portion 7 is convex outward. At both ends of the curved portion 7, bending points 8a and 9a corresponding to the ridge lines 8 and 9 are provided. The curved portion 7 is typically an arc of a single circle, in fig. 3 the radius of curvature r₁Is used for the arc of (1).

The bending angles at the bending points 8a and 8b are θ₈And theta₉The distance between the bending points 8a and 8b is d.

In addition, the minimum gap between the coating rod head 1 and the base material 2 is G₀The maximum thickness of the coating liquid layer formed between the coating rod head 1 and the base 2 is G, and the width of the coating liquid layer is b.

The inventors investigated the relationship between each of these parameters and the coating film thickness in detail, and investigated the minimum gap G₀Radius of curvature r₁And the thickness of the coating film when the meniscus liquid volume L varies. As a result, the following was found: when the surface 1a of the coating rod head is a cylindrical surface (developable surface) protruding outward, that is, when the portion corresponding to the cylindrical surface in the cross section of the coating rod head is a curved line protruding outward, the minimum gap G is set₀In the case of variation, the variation in coating film thickness is small. In the case of high-speed coating of R2R by the meniscus coating method, the gap between the coating rod head and the base material is likely to fluctuate due to vibration or the like, but the influence thereof can be reduced by using a coating rod head having a specific shape.

Further, by providing the coating bar head with ridges 8 and 9 on both sides of the surface 1a facing the substrate instead of a cylindrical shape, that is, by providing bending points 8a and 8b at both ends of the curved portion 7 in the cross section, the position of the meniscus is stabilized by a pinning effect (pinning effect), and variation in the coating film thickness is suppressed. Since a cylindrical rod is used in the conventional meniscus coating, when a circular rod having a large curvature is used, the size of the coating apparatus needs to be increased, and the shape and position of a nozzle or the like for introducing the coating liquid are limited, which results in poor workability. The coating rod head has the ridge lines at both ends of the cylindrical surface, so that the rod head can be miniaturized and the operability can be improved.

The parameters are specifically described below.

When the thickness G and the width b of the coating liquid layer existing between the coating rod head 1 and the substrate 2 are large, the coating film thickness becomes large. Therefore, if they are stable during coating, the coating film thickness becomes uniform. However, since the coating liquid supplied from the nozzle is generally constant at the time of coating, the thickness G or the minimum gap G is set to be constant₀If the width b varies, the coating film thickness tends to be uneven. In order to minimize the influence of such variations, the curvature radius r is adjusted₁Is effective. In the embodiment, the thickness G and the minimum gap G are set₀Or a uniform coating film with a stable width b and a radius of curvature r₁10 to 100mm, preferably 20 to 80 mm. The curved portion 7 need not be a circular arc of a single circle, and the radius of curvature may be locally different. In such a case, the average radius of curvature is preferably within the above range. In such a case, the average radius of curvature is referred to as a radius of curvature for convenience.

In addition, it is preferable to apply a minimum gap G between the bar head and the base material₀The particle size is 80 to 600 μm, more preferably 100 to 500 μm, and particularly preferably 150 to 400 μm. When the minimum interval is smaller than the above range, stripe unevenness is liable to occur, and when it is larger than the above range, the film thickness becomes excessively thick, and the coating film thickness is liable to become uneven due to unevenness of drying. The minimum clearance can be controlled using an actuator or a clearance ring (gap ring) or the like.

Preferred angle θ at the bend point₈And theta₉Is 90 to 150 degrees, and more preferably 100 to 130 degrees. If angle theta₈And theta₉If the amount is less than the above range, the coating liquid is less likely to return when it exceeds the ridge line from the cylindrical surface 1 a. If it exceeds the above range, the effect of stabilizing the position of the coating liquid layer (pinning effect) tends to be weak. Here, the bending points 8a and 8b do not need to be "points", and may be chamfered or curved, for example. However, in the case of performing the surface treatment, since the pinning effect or the like becomes weak when the curvature radius of the portion is large, the curvature radius of the bending point is preferably 1mm or less.

In addition, θ in FIG. 3₈And theta₉In contrast, the cross section of the rod head is asymmetric about the direction perpendicular to the application surface, but the cross section of the rod head may be symmetric.

The length d of the curved portion between the bending points is preferably 5 to 30mm, and more preferably 7 to 25 mm. When less than the above range, the meniscus easily becomes unstable. When it is larger than the above range, the film thickness tends to become excessively large, and the head becomes large, and liquid supply tends to be difficult.

The surface of the coating rod-shaped head can be a mirror surface or a matte surface with concave and convex. The coating liquid on the matte side tends to have good wettability. The surface may be a combination of a plurality of surfaces having different wettability. For example, it is preferable that the wettability of the surface 1a to which the coating liquid is supplied is good and the wettability of the side surface which is in contact with the ridge line 8 and 9 is poor, since the pinning effect is large.

In addition, the coating rod head may have a slit in the short side direction. This enables the formation of a long coating film.

The moving direction of the substrate is not particularly limited, and the coating is preferably performed while conveying the substrate from the bottom to the top. For example, as shown in fig. 1, since gravity is applied to the meniscus portion by moving the substrate from the bottom to the top in the vertical direction, a uniform film is easily formed even when the coating is performed at a higher speed. However, the moving direction can be adjusted depending on the structure of the apparatus, the physical properties of the coating liquid, and the like, and is generally within a range of ± 30 ° with respect to the vertical direction.

In fig. 1, the base material is shown as a flat plate, but the base material may be curved so as to protrude toward the application bar head. That is, by providing a roller or the like on the opposite side of the base material from the coating rod head, the base material surface can be curved so as to protrude toward the coating rod head at the meniscus forming portion.

In this case, the curvature radius of the curved portion of the application bar-shaped head is defined as r₁And the radius of curvature of the curved portion of the base material is set to r₂When the temperature of the water is higher than the set temperature,

by r₀＝1/[(1/r₁)+(1/r₂)]R of₀Preferably 20 to 80mm, and more preferably 40 to 60 mm. Moreover, it is preferable to satisfy

r₂>r₁Or is or

r₂≥200mm。

Radius of curvature r at curved portion of base material₂When the stress is large, the stress applied to the substrate is small, and the strain is also small. In the case where the substrate has a brittle film, r is preferably₂Is very large.

Fig. 5 is a conceptual diagram of the coating apparatus 10, which includes a coating rod head 1, a roller 11 as a substrate conveying member for conveying a substrate 2, a nozzle 5 as a coating liquid supply member for supplying a coating liquid 3 to the coating rod head 1, and a pump 14 for supplying the coating liquid from a container 13 to the nozzle via a pipe 12. When the coating width is wide, that is, when the length of the coating rod head in the longitudinal direction is long, it is preferable to arrange a plurality of nozzles in parallel in the longitudinal direction of the coating rod head. In order to facilitate maintenance and obtain a uniform film depending on the physical properties of the coating liquid, it is preferable that the nozzles be independently detachable and the distance between the nozzles be changeable. Alternatively, the nozzle may be a slit. In this case, it is preferable that the slit has a liquid reservoir, a concave-convex structure, a flow path, and the like for uniformizing the supply of the liquid.

The substrate conveying member preferably conveys the substrate from below to above, and the coating liquid supplying member preferably supplies the coating liquid from above the coating rod head. Thereby, gravity can be applied to the meniscus portion and coating can be performed at a higher speed. The liquid can be prevented from dripping by supplying the coating liquid from the upper part of the coating rod head.

The coating apparatus 10 may further include a device for measuring and controlling the distance (G or G) between the coating rod head and the base material₀) The member of (1). This member can further improve the uniformity of the coating film thickness.

The coating apparatus 10 may further include a member for cleaning the coating rod head. Thus, the application bar head can be periodically cleaned to remove impurities mixed from the environment or solids precipitated from the application liquid. Specifically, the solvent may be sprayed or irradiated with water, or the ultrasonic wave may be applied to the solution.

The coating apparatus 10 may further include a member for collecting the remaining coating liquid. This member makes it easy to prevent the coating liquid from flowing back after the coating is completed and to prevent the loss of the expensive coating liquid, and to prevent the solvent and the like from being discharged to the environment.

(example 1)

In example 1, the coating process of the coating material was performed in the following manner using the coating apparatus 10 shown in fig. 5. First, a radius of curvature r in a cross section of the coating rod head shown in FIG. 3 is prepared₁Is 40mm, the angle theta of the bending point₈Is 120 DEG theta₉The angle was 90 degrees, the length of the curved portion between the bending points was 25mm, and the length in the coating width direction was 100 mm.

A coating solution as a material for forming an organic active layer of a solar cell was prepared by dispersing 8mg of PTB7([ poly {4, 8-bis [ (2-ethylhexyl) oxy ] benzo [1,2-b:4,5-b' ] dithiophene-2, 6-diyl-1 t-alt-3-fluoro-2- [ (2-ethylhexyl) carbonyl ] thieno [3,4-b ] thiophene-4, 6-diyl } ]/p-type semiconductor) and 12mg of PC70BM ([6,6] phenyl C71 methyl butyrate/n-type semiconductor) in 1mL of monochlorobenzene. The coating liquid supply member is provided with 5 nozzles, and thereby supplies the coating liquid between the coating rod head and the base material. Nitrogen pressure was applied to the container from 5 tubes from one container and supplied to the nozzle. The interval between the nozzles was set to 20 mm. The nozzle is a needle made of stainless steel. As the object to be coated, a substrate in which Indium Tin Oxide (ITO) is provided on the coating surface side of a PET film roll is used. The coating rod head was disposed using an actuator so that the minimum gap distance between the coating rod head and the PET substrate became 150 μm. 40. mu.L of the coating liquid was supplied from each nozzle to each coating rod head and a meniscus column was formed. The coating liquid was applied to a PET substrate while controlling the angle and gap distance of the nozzle, thereby obtaining a coating film. The moving speed of the PET substrate was 83mm/s and constant. The liquid was continuously supplied from the nozzle, and the coating was performed at a length of 20m, and the thickness of the dried film at the center of 18m was measured from the absorption spectrum, and the coating film thickness in a wet state was determined. As a result, the coating film thickness was 10.5. + -. 0.1. mu.m.

(example 2)

Coating was carried out in the same manner as in example 1, except that a coating bar head made of SUS303 having a curvature radius of 10mm was used. The coating film was 11.2. + -. 0.3. mu.m.

(example 3)

Coating was carried out in the same manner as in example 1, except that a coating bar head made of SUS303 having a curvature radius of 100mm was used. The coating film was 9.5. + -. 0.3. mu.m.

(example 4)

Except for the minimum gap distance G₀Coating was carried out in the same manner as in example 1 except that the coating solution was 550 μm and 600 μ L of the coating solution was supplied from each nozzle to form a meniscus column. The coating film was 25.0. + -. 0.3. mu.m.

(example 5)

Coating was performed in the same manner as in example 1, except that a roll having a curvature radius of 200mm was disposed to face the coating rod head, the base material was bent to be convex with respect to the rod head, and a coating rod head made of SUS303 having a curvature radius of 80mm was used. Resultant radius of curvature r₀Is 57 mm. The coating film had a thickness of 10.0. mu.m, and the coating film had unevenness of less than 0.1. mu.m.

Comparative example 1

Coating was performed in the same manner as in example 1, except that a coating bar head made of SUS303 with a flat bottom surface was used. The coating film was 12.0. + -. 1.0. mu.m.

Comparative example 2

Coating was carried out in the same manner as in example 1, except that a coating bar head made of SUS303 having a curvature radius of 8mm was used. The coating film was 13.0. + -. 0.7. mu.m.

Comparative example 3

Coating was carried out in the same manner as in example 1, except that a coating bar head made of SUS303 having a curvature radius of 110mm was used. The coating film was 9.2. + -. 0.6. mu.m.

Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in other various forms, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the scope equivalent thereto.

Description of reference numerals

1 … coating rod head, 2 … base material, 3 … coating material, 4 … meniscus, 5 … nozzle, 6 … coating film, 7 … curved surface, 8 … bending point, 9 … bending point, 10 … coating device, 11 … roller, 12 … pipe, 13 … container, 14 … pump.