Coating device and coating method

Abstract

According to one embodiment, a coating device and a coating method capable of forming a uniform coating film are provided. The coating device (100) is provided with a coating rod, a base material conveying part for conveying a base material, and a coating liquid supply part for supplying a coating liquid to the coating rod. Furthermore, a homogenizing rod is provided downstream of the coating rod, and the homogenizing rod is disposed at a position where the coating liquid forms a meniscus between the homogenizing rod and the substrate.

Description

Technical Field Embodiments of the present invention relate to a coating apparatus and a coating method that can be used in forming a device. Background Art Organic thin film solar cells and organic / inorganic hybrid solar cells using organic semiconductors are highly anticipated as low-cost solar cells because cheap coating methods can be applied in the formation of active layers. In order to realize organic thin film solar cells and organic / inorganic hybrid solar cells at low cost, it is required to uniformly coat the coating materials that form the organic active layer and other layers. The film thickness of each layer is about several nanometers to hundreds of nanometers, and it is required to form such very thin layers over a large area and with good uniformity. For example, as a roll-to-roll (R2R) coating method that can coat extremely thin layers over a large area at low cost, a meniscus coating method and a slit coating method are known. However, if these previously known methods are simply used directly, it is difficult to obtain a uniform film thickness in some cases, and a coating device that can use a uniform coating rod to coat the liquid to form a uniform coating film is more desired. Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2003-251256 Summary of the invention Problems to be solved by the invention Embodiments of the present invention provide a coating device and a coating method capable of forming a uniform coating film. Means for solving problems Embodiments provided by the present invention are as follows.

[0001] A coating device comprises a coating rod, a substrate conveying component for conveying a substrate, and a coating liquid supply component for supplying a coating liquid to the coating rod, wherein a uniformizing rod is further provided downstream of the coating rod, and the uniformizing rod is arranged at a position where the coating liquid forms a curved liquid surface between the uniformizing rod and the substrate.

[0002] The coating device according to [1] further comprises a uniformizing rod position adjusting member for controlling a distance between the uniformizing rod and the substrate.

[0003] The coating device according to [1] or [2], wherein the homogenizing rod is arranged in a non-rotating manner.

[0004] The coating device according to any one of [1] to [3], further comprising a coating rod position adjustment member for controlling the position of the coating rod.

[0005] The coating device according to any one of [1] to [4], wherein the coating liquid is supplied from a plurality of nozzles.

[0006] The coating device according to [5], wherein the opening surfaces of the plurality of nozzles are needle-shaped and cut at an angle of not less than 75 degrees and not more than 105 degrees.

[0007] The coating device according to [5] or [6], wherein the nozzle is detachable.

[0008] The coating device according to any one of [5] to [7], further comprising a nozzle for supplying the coating liquid to the leveling rod.

[0009] The coating device according to any one of [1] to [4], wherein the coating liquid is supplied from a slot die.

[0010] The coating device according to any one of [1] to [9], wherein the homogenizing rod is curved.

[0011] A coating method, using a coating rod to coat a coating liquid on the surface of a substrate to form a coating film, wherein a uniformizing rod is arranged downstream of the coating rod, and a secondary coating film is formed by forming a curved liquid surface between the substrate and the uniformizing rod using the coating liquid supplied from the primary coating film formed by the coating rod.

[0012] The coating method according to

[11] , wherein the coating liquid is supplied from a plurality of nozzles to the surface of the coating rod, and the coating liquid is supplied from the surface to between the coating rod and the substrate, thereby forming the primary coating film.

[0013] The coating method according to

[12] , wherein the coating liquid is supplied after adjusting the positions of the plurality of nozzles and detecting the distance between the coating rod and the plurality of nozzles.

[0014] The coating method according to

[13] , wherein the distance is detected by measuring the electrical resistance between the nozzle and the coating rod.

[0015] The coating method according to any one of

[12] to

[14] , wherein the plurality of nozzles are provided on a cantilever fixing plate that is rotatable, horizontally movable, or vertically movable. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a schematic side view illustrating the coating device according to the first embodiment. Figure 2 It is a schematic plan view illustrating a coating device according to the first embodiment. Figure 3 This is a flowchart illustrating the coating method according to the second embodiment. DETAILED DESCRIPTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the size between the parts, etc. are not necessarily the same as in reality. In addition, even when representing the same part, there are cases where the mutual dimensions and ratios are represented differently according to the drawings. In the specification and drawings of the present application, the same elements as those described in the drawings that have already appeared are denoted by the same reference numerals, and detailed description thereof will be appropriately omitted. (First Embodiment) Figure 1 It is a schematic side view illustrating the coating device according to the first embodiment. Figure 2 It is a schematic plan view illustrating a coating device according to the first embodiment. like Figure 1 As shown, the coating device 100 of the embodiment comprises: a coating rod 101; a substrate conveying member 102 for conveying a substrate; a coating liquid supplying member 104 for supplying a coating liquid 103 stored in a liquid storage portion 112 to the coating rod; and a homogenizing rod 105. The homogenizing rod 105 is arranged at a position where the coating liquid forms a meniscus between the homogenizing rod and the substrate. And, in this example, a coating film is formed once using the coating rod by a so-called meniscus method. Each component is arranged as follows: the coating liquid 103 is supplied to the surface of the coating rod 101 from a nozzle 106, the coating liquid flows from the surface of the coating rod into between the coating rod 101 and the substrate 107 to form a meniscus 103Ma, and the substrate is conveyed in the direction of the arrow, thereby forming a coating film 108a once. In an embodiment, the cross-sectional shape of the coating rod 101 is arbitrary. The cross-sectional shape is, for example, circular, flat circular or polygonal. Alternatively, a portion of the cross-sectional shape corresponding to the portion where the meniscus is formed is curved, and the other portion is linear. For example, the cross-sectional shape of the surface of the coating rod 101 that is opposite to the substrate 107 may be curved. The coating rod can be arranged in a non-rotating manner. By making the coating rod non-rotating like a roller, the stability of the meniscus is improved. The coating rod 101 for example comprises at least one selected from the group consisting of stainless steel, aluminum, titanium and glass. Thus, the processing when preparing the coating rod 101 becomes easy. In one example, the surface of the coating rod 101 is a mirror surface. In another example, the surface of the coating rod 101 can also include a concavo-convex structure. And, if Figure 1 and Figure 2 As shown, the homogenizing rod 105 is arranged downstream of the coating rod 101 . The coating liquid 103 is applied to the substrate 107 on the entire surface by the coating rod 101 to form a coating film 108a. However, the coating film 108a may not be uniform enough. The coating film 108a formed in this embodiment contacts the uniformizing rod 105 disposed downstream of the coating rod by conveying the substrate. Figure 1 As shown, a meniscus 103Mb of the coating liquid 103 can be formed between the substrate 107 and the equalizing rod 105. The surface tension of the coating liquid expands in the lateral direction of the gap between the equalizing rod 105 and the substrate 107, thereby producing a uniform meniscus 103Mb. By bringing the meniscus 103Mb into contact with the substrate 107, a secondary coating film 108b with high uniformity formed by the coating liquid 103 is formed on the substrate 107. For example, the coating film 108b is solidified by drying, thereby obtaining a target film (solid film). For example, this can be done by arranging a drying unit 109 downstream of the equalizing rod. In this way, for example, by moving the substrate 107 in the moving direction (the direction of the arrow in the figure), it is possible to form a coating film 108 b having a large area on the substrate 107 . Figure 1 and Figure 2 The coating device illustrated is a device that forms a single coating film by a meniscus method. In order to improve the uniformity of the single coating film, it may further include a nozzle position adjustment component 110 for adjusting the position of the nozzle 106, a nozzle position detection component 111 for detecting the distance between the coating rod 101 and the nozzle 106, etc. When a nozzle is used to form a primary coating film, Figure 2 As shown, the nozzle 106 can be provided in plurality, or the pump 104 can be provided in plurality. The plurality of nozzles 106 can be arranged opposite to the coating rod 101. Figure 2 As shown, a plurality of nozzles 106 can supply the coating liquid 103 toward the coating rod 101. In addition, another nozzle can be further provided to supply the coating liquid to the equalizing rod 105. By pre-arranging such another nozzle, a meniscus can be formed between the substrate and the equalizing rod before the primary coating film is formed before the coating starts. like Figure 2 As shown, a plurality of nozzles 106 are arranged along a first direction. The first direction is, for example, the Y-axis direction. A direction perpendicular to the Y-axis direction is set as the X-axis direction. The moving direction of the substrate can be consistent with the X-axis. A direction perpendicular to the Y-axis direction and the X-axis direction is set as the Z-axis direction. The coating rod 101 extends, for example, along the Y-axis direction. In the embodiment, the number of the plurality of nozzles 106 may be set to 3 or more. Thus, a large-area primary coating film 108a can be stably formed. Figure 2 In the example of FIG. 1 , the number of the plurality of nozzles 106 is 4. In the embodiment, the number may be any integer greater than 3. In an embodiment, as a nozzle, it can be set to a slot die or a needle-shaped one. By using a plurality of needle-shaped nozzles 106, for example, the discharge amount of the coating liquid 103 can be controlled with high precision. If the nozzle is needle-shaped, it is easy to make the front ends of the plurality of nozzles contact the coating rod 101, for example. In the needle-shaped nozzle, high flexibility can be obtained. Through high flexibility, for example, it is possible to suppress the nozzle from being damaged by vibration of the coating rod 101, etc. In the needle-shaped nozzle, the length of the nozzle is, for example, greater than 10 mm and less than 100 mm, and the inner diameter of the nozzle is, for example, greater than 0.5 mm and less than 2 mm. The angle between the end face of the front end of the nozzle and the extension direction of the nozzle is, for example, about 90 degrees (for example, greater than 75 degrees and less than 105 degrees). Through such a shape, for example, it is possible to suppress damage to the coating rod 101. However, when there are a plurality of nozzles, the distance between the coating rod 101 and the tip of each nozzle is likely to vary. If there is a variation, the meniscus 103Ma formed by each nozzle is likely to be disturbed, resulting in the coating film 108a being likely to become non-uniform. like Figure 1 and Figure 2 As shown, if a nozzle position adjustment component 110 for adjusting the position of each nozzle and a nozzle position detection component 111 for detecting the distance between the coating rod 101 and each nozzle 106 are provided, the deviation of the position and distance between the front end of each nozzle and the coating rod can be reduced, and uniform coating can be performed. In the embodiment, there may be a component for detecting the contact between the coating rod and each nozzle. For example, the contact can be easily and simply detected by measuring the resistance between the nozzle and the coating rod, so the coating conditions can be adjusted based on this to reduce the deviation. If contact occurs, the coating liquid can be directly applied to the coating rod, and it is difficult to cause the coating liquid to sink. In an embodiment, as a component for detecting the contact between the coating rod and each nozzle, a component for measuring the resistance between each nozzle and the coating rod may be provided. If each nozzle and the coating rod are made of conductive stainless steel or the like and each nozzle is insulated, when measuring the resistance between the coating rod and each nozzle, the resistance decreases sharply at the moment of contact. In addition, since the resistance changes due to the change of the contact state, the contact state can be monitored. For example, when the nozzle is strongly pressed by the coating rod and bent too much, not only the front end of the nozzle but also its side will contact the coating rod, and the resistance becomes very small. In this case, it is easy to discharge the coating liquid from the front end of the nozzle to the position outside the coating rod, which easily causes uneven coating. Since the optimal resistance varies according to the shape and material of the nozzle and the coating rod, it is preferably measured in advance. Preferably, wiring connected to the resistance measuring device is pre-arranged between each nozzle and on the coating rod. An opening and closing portion can be provided on the wiring to move each nozzle and confirm contact with the coating rod before coating. In addition, if the resistance is also measured during coating, it is possible to detect abnormal contact between the nozzle and the coating rod. The resistance measuring device can also be an external device separate from the coating device. In addition, in the coating device of the embodiment, the nozzle is preferably detachable. The nozzle is easily clogged due to a small opening. In the coating device of the embodiment, when such a clog occurs, the discharge amount of each nozzle can be adjusted by the coating liquid supply component and the coating liquid supply amount adjustment component, but in the case of obvious clogging or inability to discharge completely, it is necessary to clean or replace it. In such a case, it is preferred to make the nozzle detachable because it is easy to maintain. In the above description, Figure 1 and Figure 2 Although the case where the coating liquid is supplied from a plurality of nozzles and the coating film 108a is formed once by the meniscus method is described, the coating film may be formed once by other methods. For example, instead of the plurality of nozzles, the coating rod may be a slit-type die head for slit coating, which has a manifold inside and supplies the coating liquid to the substrate surface through the slit from the manifold. Furthermore, a slit-type die head may be used instead of Figure 1 and 2 The nozzle in the coating rod supplies the coating liquid. The coating device 100 may further include a drying unit 109. The drying unit 109 can dry the coating film 108b applied to the substrate 107. The drying unit 109 may include, for example, a gas nozzle or a far-infrared lamp. The distance between the coating rod 101 and the homogenizing rod 105 can also be freely changed. In addition, it is preferable to provide a means for controlling the distance between the homogenizing rod 105 and the substrate 107. For this purpose, a gap ring, a micrometer, or the like can be used. The homogenizing rod can be straight or curved. If it is straight, the uniformity of the thickness of the coating film can be easily obtained. If it is curved, although thickness changes such as thickening in the center are likely to occur, uniformity in the coating direction can be easily obtained. In the embodiment, the cross-sectional shape of the homogenizing rod 105 is arbitrary. The cross-sectional shape is, for example, circular, flat circular or polygonal. Alternatively, a portion of the cross-sectional shape is curved and the other portion is linear. For example, the cross-sectional shape of the surface of the homogenizing rod 105 facing the substrate 107 may also be curved. The homogenizing rod can be arranged in a non-rotating manner. By making the homogenizing rod non-rotating like a roller, the stability of the meniscus is improved. The homogenizing rod 105 includes, for example, at least one selected from the group consisting of stainless steel, aluminum, titanium, and glass. Thus, the processing of the homogenizing rod 105 becomes easy. In one example, the surface of the homogenizing rod 105 is a mirror surface. In another example, the surface of the homogenizing rod 26 may also include a concavo-convex structure. (Second Embodiment) The second embodiment relates to a coating method. In the coating method of the embodiment, coating is performed using, for example, the coating device 10 (and its modifications) described in the first embodiment. Figure 3 : is a flowchart illustrating a coating method (S30) of the second embodiment. In the coating method for forming a curved liquid surface of the coating liquid and performing coating, there are: a step of detecting and adjusting the distance between the coating rod and the curved liquid surface equalizing rod and the substrate (S31); a step of detecting and adjusting the distance between the coating rod and each nozzle (S32); a step of making a curved liquid surface between the substrate and the equalizing rod (S33); and a step of supplying the coating liquid to coat the substrate (S34). Here, by performing the step S33 before the step S34, the curved liquid surface M22 is stably generated during the coating process. In this way, in order to form a curved liquid surface between the substrate and the equalizing rod before starting the coating, it is preferable to configure other nozzles for supplying the coating liquid to the equalizing rod. In an embodiment, the distance between the coating rod and each nozzle can be detected by measuring the resistance between the coating rod and the nozzle. In addition, each nozzle can be arranged on a cantilever fixed plate that can rotate, move horizontally or move vertically. Through such a configuration, the position of all nozzles can be adjusted simultaneously. Hereinafter, specific examples of the coating apparatus and coating method according to the embodiment will be described. For example, a solar cell can be formed by coating with the coating device 100. In one example, the number of pumps is 4. A tube connected to one pump is connected to four nozzles. The total number of nozzles is 16. The nozzle is set on a cantilever rod. An actuator for moving and wiring for measuring resistance are provided for each nozzle. The wiring is connected to a resistance meter. A nozzle position detection component, such as a camera, is provided for observing the positional relationship between the nozzle and the coating rod. For example, the substrate 107 is a rolled PET film. The width of the PET film is, for example, 330 mm. A light-transmitting electrode having a width of 300 mm is produced on the PET film by a roll-to-roll corresponding sputtering device. The sheet resistance of the electrode is, for example, 10Ω / □. The electrode has, for example, a stacked structure of ITO film / Ag alloy / ITO film. For example, a plurality of electrodes are provided. The length of one of the plurality of electrodes is, for example, about 10 mm. The interval between the plurality of electrodes is, for example, 50 μm. The cross-section of the coating rod 101 and the homogenizing rod 105 is circular. The radius of the circle is 10 mm. The length of the coating rod 101 and the homogenizing rod 105 is 300 mm. The coating rod 101 and the homogenizing rod 105 are made of, for example, stainless steel (eg, SUS303). The nozzle includes a stainless steel locking base. The nozzle length is 50 mm. The coating liquid pipe is a polytetrafluoroethylene pipe. The nozzle and the pipe are connected by a detachable joint. The pipe is connected to the pump. In one example, the hole transport layer is formed using the coating liquid 103. In this case, the coating liquid 103 is an aqueous solution containing PEDOT and PSS. For example, the relative positional relationship between the coating rod 101 and the uniformizing rod 105 and the substrate 107 is controlled by a gap ring and an actuator. For example, the nozzle is placed in a horizontal state. In this state, the coating liquid 103 is supplied and the air in the nozzle is exhausted. Then, the tip of the needle nozzle was lowered to be inclined 20° from the horizontal. The cantilever rod was brought close to the coating rod. Next, each nozzle was brought close to the coating rod one by one and contacted therewith, so that the resistance was 10 to 50Ω. The coating liquid is supplied to the equalizing rod 105 by a syringe, and a meniscus 103Mb is formed between the equalizing rod and the substrate 107 . The coating liquid 103 is continuously supplied by a pump while the substrate 107 is conveyed. The moving speed of the substrate 107 is, for example, 5 m / min. The heated dry air is blown to the applied coating liquid 103 by the drying unit 109. A cured coating film is obtained from the coating liquid 103. In an embodiment, other coating liquids may be further applied after the above-mentioned coating. Other coating liquids, for example, contain semiconductor materials. Other coating liquids, for example, contain PTB7 ([poly{4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-1t-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl}]) and PC70BM ([6,6]phenyl C71butyric acid methyl ester). PTB7 is, for example, a p-type semiconductor. PC70BM is, for example, an n-type semiconductor. Other coating liquids, for example, further contain monochlorobenzene. The amount of PTB7 is 8 mg relative to 1 mL of monochlorobenzene. The amount of PC70BM is 12 mg relative to 1 mL of monochlorobenzene. Other coating liquids are dispersions containing organic semiconductors. Other coating liquids, for example, become semiconductor films of solar cells. In coating other coating liquids, the minimum gap distance between the coating rod 101 and the substrate 107 is 300 μm. The moving speed of the substrate 107 is, for example, 5 m / min. After coating, the substrate 107 is dried by the drying unit 109 . For example, there are organic thin film solar cells or organic / inorganic hybrid solar cells using organic semiconductors. By manufacturing these solar cells using a coating method, high-performance solar cells can be manufactured. In the embodiment, the coating liquid 103 may be applied to the substrate 107 at a position where the substrate 107 is conveyed in a vertical direction. In this way, for example, the effect of gravity is applied to the meniscus, and a uniform film can be easily obtained even at a high speed. According to the embodiment, a coating device and a coating method capable of forming a uniform coating film can be provided. The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific structure of each element such as a tube, a pump, a nozzle, and a holding portion included in the coating device is included in the scope of the present invention as long as those skilled in the art can implement the present invention in the same manner and obtain the same effect by appropriately selecting from the known range. Furthermore, any combination of two or more elements of the specific examples within a technically feasible range is also included in the scope of the present invention as long as it includes the gist of the present invention. In addition, all coating devices and coating methods that can be implemented by those skilled in the art by making appropriate design changes based on the coating head, coating device, and coating method described as embodiments of the present invention also belong to the scope of the present invention as long as they include the gist of the present invention. Furthermore, those skilled in the art can conceive of various changes and modifications within the scope of the concept of the present invention, and these changes and modifications are also considered to belong to the scope of the present invention. Several embodiments of the present invention have been described, but these embodiments are provided for example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments and their variations are included in the scope and spirit of the invention, and are included in the invention described in the claims and the scope of their equivalents. Description of Reference Numerals 100…Coating device 101…Coating rod 102…Substrate transport components 103…Coating liquid 104 ... coating liquid supply part 105…homogenizing rod 106…Nozzle 107…Base material 108a…One-time coating film 108b…Secondary coating film 109…Drying parts 110…Nozzle position adjustment parts 111…Nozzle position detection component 112…liquid storage department

Claims

1. A coating device comprising a coating rod, a substrate conveying member for conveying a substrate, and a coating liquid supplying member for supplying a coating liquid to the coating rod, characterized in that: A uniformizing rod is further provided downstream of the coating rod, and the uniformizing rod is arranged at a position where the coating liquid forms a meniscus between the uniformizing rod and the substrate.

2. The coating device according to claim 1, characterized in that: A uniformizing rod position adjusting member for controlling the distance between the uniformizing rod and the substrate is further provided.

3. The coating device according to claim 1 or 2, characterized in that: The homogenizing rod is arranged in a non-rotating manner.

4. The coating device according to claim 1 or 2, characterized in that: The coating rod position adjusting member for controlling the position of the coating rod is further provided.

5. The coating device according to claim 1 or 2, characterized in that: The coating liquid is supplied from a plurality of nozzles.

6. The coating device according to claim 5, characterized in that: The opening surfaces of the plurality of nozzles are in a needle shape cut at an angle of not less than 75 degrees and not more than 105 degrees.

7. The coating device according to claim 5, characterized in that: The nozzle is detachable.

8. The coating device according to claim 5, characterized in that: A nozzle for supplying the coating liquid to the leveling rod is further provided.

9. The coating device according to claim 1 or 2, characterized in that: The coating liquid is supplied from a slot die.

10. The coating device according to claim 1 or 2, characterized in that: The homogenizing rod is curved.

11. A coating method for forming a coating film by coating a coating liquid on a surface of a substrate using a coating rod, characterized in that: A uniformizing bar is arranged downstream of the coating bar, and a secondary coating film is formed by forming a meniscus between the substrate and the uniformizing bar using the coating liquid supplied from the primary coating film formed by the coating bar.

12. The coating method according to claim 11, characterized in that: The coating liquid is supplied from a plurality of nozzles to the surface of the coating rod, and the coating liquid is supplied from the surface to between the coating rod and the substrate, thereby forming the primary coating film.

13. The coating method according to claim 12, characterized in that: The coating liquid is supplied after the positions of the plurality of nozzles are adjusted and the distance between the coating rod and the plurality of nozzles is detected.

14. The coating method according to claim 13, characterized in that: The distance is detected by measuring the electrical resistance between the nozzle and the coating rod.

15. The coating method according to claim 12, characterized in that: The plurality of nozzles are arranged on a cantilever fixing plate which can be rotated, moved horizontally or moved vertically.

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