JP5899424B2 - Coating apparatus and coating method - Google Patents

Description

  The present invention relates to a coating apparatus and a coating method for coating a material such as an antireflection film on the surface of a glass substrate for a solar cell.

  Currently, a coating technique for applying a functional film such as an antireflection film or a wavelength adjusting film that blocks light of a specific wavelength to a large area has been developed for solar cells, display panels, lighting, and the like. For example, there is a die coating method as a method for forming a coating film on a substrate. FIG. 9 is a schematic diagram for explaining a conventional die coating method.

  In this figure, when a functional film is applied to the substrate 111, a coating solution 114 is discharged from a die 112D having a long length in the coating width direction through a slit 113 formed in the longitudinal direction of the die 112D. Apply on top. At this time, the coating liquid 114 is applied onto the substrate 111 while moving relative to the die 112D and the substrate 111 while maintaining the gap 115 between the die 112D and the substrate 111.

  However, the above-described die coating method has a problem that the film thickness becomes non-uniform at the start and end of coating. In order to control the film thickness at the start and end of coating stably, the gap 115 between the die 112D and the base material 111 is held in a narrow state, and the relative movement between the die 112D and the substrate 111 is slowed down. And have time.

  In order to solve the above problem, the contents disclosed in Patent Document 1 are known and will be described with reference to FIG.

  When the substrate 111 is relatively moved while discharging the coating liquid 114 from the die 112D and a coating film is formed on the substrate 111, the dummy plate 117 is disposed at the coating start position 116, and coating is started from the upper surface of the dummy plate. Thus, the film thickness variation portion 118 at the coating start end portion can be removed.

  In addition to the non-contact coating method such as the die coating method, there are contact coating methods such as a porous coating method and a roll coating method.

  For example, the contents shown in Patent Document 2 are known as a porous coating method and will be described with reference to FIG.

  In this method, the porous material 112 supplied with the coating liquid 114 is brought into contact with the substrate 111 and the porous material 112 and the substrate 111 move relative to each other to apply the coating liquid 114 on the substrate 111.

JP 2007-000865 A JP-A-9-047703

  However, even in the method disclosed in Patent Document 2, the porous material 112 is impregnated at the application start end portion by crushing the tip of the porous material 112 when the porous material 112 contacts the substrate 111. The coating liquid 114 oozes out onto the substrate 111 at a time, resulting in a problem that the film thickness at the start end is increased. In addition, the exuded coating liquid 114 is dragged to the tip of the porous material 112, causing a problem that film thickness unevenness occurs on the entire coating film surface.

  Therefore, it is easily considered that the die coating dummy plate concept is applied to the porous material coating method, but the following problems occur.

  This problem will be described with reference to FIG.

  FIG. 12 is a cross-sectional view showing a coating process when a dummy plate is introduced into the porous coating method.

  The coating liquid 114 oozes out at a location where the porous material 112 supplied with the coating liquid 114 contacts the dummy plate 117, and a liquid pool 119 is generated. When the porous material 112, the substrate 111, and the dummy plate 117 are relatively moved in this state, the porous material 112 is transferred from the dummy plate onto the substrate 111 at the front end portion 120 of the dummy plate 117.

  At this time, the liquid puddle 119 that has oozed out on the dummy plate 117 is dragged to the tip of the porous material 112, and a part of the liquid puddle 119 moves on the substrate 111, so that the film thickness of the coating film on the substrate 111 is reduced. It becomes uniform and defects such as streaks occur. Further, a part of the liquid pool 119 goes around to the back side of the dummy plate front end portion 120, that is, the substrate side 121 of the dummy plate, and enters the gap between the dummy plate and the substrate 111 by capillary action, so that it is formed on the substrate 111. The coating boundary line at the start end of the coating film bleeds, resulting in poor appearance.

  Therefore, the present invention has been made in view of such problems, and an object of the present invention is to provide a coating apparatus and a coating method capable of stably forming a coating film without unevenness.

  In order to achieve the above object, the coating apparatus of the present invention has the following characteristics.

  [1] A substrate holder on which a substrate is placed, a porous material for applying a coating liquid to the surface of the substrate, a liquid supply mechanism for supplying the coating liquid to the porous material, a substrate holding table and a porous material, A movable mechanism capable of relatively moving the substrate, a vertical driving mechanism capable of contacting the porous material and the substrate, and a dummy plate disposed on the outer periphery of the substrate and covering a part of the surface of the substrate. The dummy apparatus is a coating apparatus in which the dummy plate is disposed to be inclined to the outside of the substrate holding table with respect to the surface of the substrate holding table on which the substrate is placed.

[2] In the above [1], the surface of the dummy plate, upstream of the point of contact with the porous material, a groove for flowing the excess coating solution is provided, the coating equipment.

  [3] The coating apparatus according to [1] or [2], wherein the tip portion of the dummy plate is rounded.

  [4] The coating apparatus according to [1] to [3], wherein the upper surface of the dummy plate is coated with a film that repels the coating liquid on an upstream side from a position in contact with the porous material.

  [5] The coating apparatus according to [1] to [4], wherein a part of the lower surface of the dummy plate is coated with a film that repels the coating liquid.

  The coating method of the present invention has the following characteristics.

  [6] A coating method in which the coating liquid is applied by infiltrating the coating liquid into the porous material and bringing the porous material into contact with the surface of the substrate, and covers a part of the substrate at the substrate coating start portion. A dummy plate inclined toward the outside of the substrate is placed on the outer periphery of the substrate, and the porous material and the substrate are moved relative to each other in one direction while the porous material is in contact with the dummy plate. Forming a coating film, coating method.

  [7] The coating method according to [6], wherein the dummy plate is separated from the substrate immediately after the porous material passes through the dummy plate.

  As described above, in the coating apparatus and the coating method, by installing the dummy plate at the coating start portion, the variation in film thickness for the coating start end can be reduced, and a uniform coating film can be formed on the coating target.

Schematic showing the basic configuration of the coating apparatus of the present invention The figure which shows the application | coating process in Example 1 The figure which shows the behavior near the dummy board in Example 1. The figure which shows the visual result of the coating film in Example 1 The top view which shows the dummy board shape in Example 2. The upper surface and sectional view showing the dummy plate shape in Example 3 Sectional drawing which shows the dummy plate shape in Example 4 Sectional drawing which shows the dummy plate shape in Example 5 Diagram showing conventional die coating method The figure which shows the basic operation | movement of the coating device in patent document 1 The figure which shows the conventional porous coating method of patent document 2 The figure which shows the case where the dummy board of patent document 1 is applied to the porous coating method

  The structure of the coating apparatus of this invention is demonstrated using FIG.

  FIG. 1 is a schematic view showing the basic configuration of the coating apparatus of the present invention. The coating apparatus of the present invention holds a liquid supply nozzle 4 that sends a coating liquid to the porous material 2 in a fixed amount and a substrate 7 that is an application target, and a transport mechanism (movable relative to the porous material 2). (Not shown), and a vertical drive mechanism (not shown) that enables the porous material 2 and the substrate 7 to be in contact with each other, and a mechanism for disposing the dummy plate 6 at the coating start end of the substrate 7. .

  Below, these structural members are explained in full detail. The coating apparatus of the present invention has a configuration in which a porous material 2 is sandwiched between two metal plates 1 such as SUS and Al having a width equal to or larger than the coating width. In this state, the coating liquid 5 is supplied to the liquid supply nozzle 4 at a predetermined speed by the pump 3, and the coating liquid 5 is supplied to the upper surface of the porous material 2 through the liquid supply nozzle 4.

  The coating liquid 5 supplied to the porous material 2 penetrates into the entire porous material 2. Further, the substrate 7 is in contact with the porous material 2 in a state of being fixed to the transfer stage 8, and can be relatively moved while maintaining the contacted state. A dummy plate 6 is installed at the application start portion of the substrate 7. The porous material 2 once comes into contact with the dummy plate 6, and the dummy plate 6 and the substrate 7 move relative to the porous material 2 as they are. The porous material 2 moves from the dummy plate 6 to the substrate 7.

  In FIG. 1, the dummy plate 6 is fixed to the transfer stage 8 that fixes the substrate 7, and moves in synchronization with the substrate 7. However, it is not limited to that. For example, it may be fixed to the application nozzle or fixed to a completely different location.

  More specific operation of the apparatus will be described as an example with reference to the drawings.

(Example 1)
The coating operation of the coating apparatus described in FIG. 1 will be described with reference to FIG.

  First, the substrate 7 is fixed to the transfer stage 8 by a reduced pressure adsorption method, an electrostatic adsorption method, physical fixation, etc. so as not to be displaced by conveyance / application, and is moved below the porous material 2 (FIG. 2A). .

  Next, the dummy plate 6 is disposed on the application start position of the substrate 7 (FIG. 2B). Then, the distance between the porous material 2 and the dummy plate 6 is reduced by the vertical drive mechanism (not shown) of the porous material 2, and the tip of the porous material 2 is brought into contact with the surface of the dummy plate 6.

  Here, a coating liquid pool 9 is generated at the tip of the porous material 2 (FIG. 2C). In this state, the porous material 2 and the substrate 7 are relatively moved, and the porous material 2 is moved from the dummy plate 6 onto the substrate 7 (FIG. 2D). The coating film 10 is formed on the substrate 7 by continuing the relative movement as it is.

  When the porous material 2 is relatively moved to the application end position, the porous material is separated from the substrate 7 and the application operation is completed (FIGS. 2E to 2G). Here, as shown in FIG. 2 (e), when the porous material 2 passes through the dummy plate 6 and moves onto the substrate 7, a mechanism for moving the dummy plate 6 away from the substrate 7 is added. Thus, there is an effect of preventing a problem that the coating liquid enters between the dummy plate 6 and the substrate 7.

  As described in the above problem, it is desirable that the upper surface of the dummy plate 6 is disposed in a direction away from the surface of the substrate 7 in the application direction in order to solve the dragging of the liquid pool. This has the effect of scraping off excess liquid from the porous material 2 and the effect of preventing the liquid pool 9 from being dragged onto the substrate 7. Furthermore, there is an effect of preventing the liquid pool 9 remaining on the dummy plate 6 from flowing down onto the substrate 7.

  Further, the state of the tip of the porous material 2 and the tip of the dummy plate 6 before and after FIG. 2 (d) described in the above operation will be described in detail with reference to FIG.

  As shown in FIG. 3A, the liquid pool 9 of the coating liquid that has once oozed out from the tip of the porous material 2 that has been in contact with the dummy plate 6 moves to the dummy plate 6 when the tip of the porous material 2 relatively moves. The tip of the porous material 2 is further compressed by the height of the upper surface of, so that the liquid oozes out (FIG. 3B).

  Next, when the tip of the porous material 2 moves from the dummy plate 6 onto the substrate 7, the amount of compression of the porous material 2 is relaxed at the portion A in the figure (FIG. 3C). That is, the porous material absorbs excess liquid at the extreme tip of the dummy plate 6 due to relaxation of the compression amount of the porous material, and when the tip of the porous material 2 comes into contact with the substrate 7, the liquid pool 9 is formed on the substrate. 7 Prevents dragging up. This demonstrates the effect of eliminating coating unevenness.

  In the present embodiment, the positional relationship between the porous material 2 and the substrate 7 is shown as the porous material 2 on the upper side and the substrate 7 on the lower side. However, the present invention is not limited to this.

  In order to further exhibit the above-described effects, it is also effective to vary the height of the porous material 2 when the porous material 2 moves from the dummy plate 6 to the substrate 7.

  Alternatively, it is also effective to vary the speed of relative movement between the porous material 2 and the dummy plate 6 and the substrate 7. Specifically, when the porous material 2 moved from the dummy plate 6 to the substrate 7, the height of the porous material 2 was moved slightly higher, and the moving speed was reduced. Since this varies depending on the viscosity and surface tension of the coating solution used, it is desirable to provide a mechanism that can be varied on the apparatus.

  Further, the dummy plate 6 will be described in detail. In this embodiment, a material that can be used as an antireflection film when applied as a coating solution is used. Specifically, a solution having a solvent content of 90 to 98% and a solid content capable of forming a film: 2 to 10% was used, and a low viscosity solution having a viscosity of 1 to 10 mPa · s was used.

  Moreover, foam materials, such as a melamine resin and a urethane resin, were used as a porous material. When this solution was used, an optimal numerical value was experimentally obtained by visual confirmation of the coating film for the shape of the dummy plate 6 for obtaining the above-described effect. The result is shown in FIG.

First, on the upper surface of the dummy plate 6, the distance (A in FIG. 2) from the position where the porous material 2 abuts to the substrate 7 is required to be 5 mm or more, preferably 10 mm or more from the experiment. Obtained. Further, the coating film formed on the substrate 7 tends to be more stable when the length is longer, but if it is too long, there are problems that the equipment becomes larger and the material loss increases.
Further, although the upper surface of the dummy plate 6 is arranged in a direction away from the surface of the substrate 7 in the coating direction, the angle (B in FIG. 2) formed by the upper surface of the dummy plate 6 and the surface of the substrate 7 is From the experimental results, it is desirable that the angle is greater than 0 ° and 15 ° or less. The effect described above is difficult to obtain at 0 °, and if it is larger than 15 °, the coating liquid is oozed out from the porous material 2 more than necessary. This is because a problem occurs.

  Next, the height between the tip of the upper surface of the dummy plate 6 and the surface of the substrate 7, that is, the height that falls when the tip of the porous material 2 moves from the dummy plate 6 to the substrate 7 (C in FIG. 2). Is described.

  Visual confirmation of the coating film in the case where the height of C was changed by changing the thickness of the dummy plate 6 with the above A and B fixed. As a result, the height (C) between the tip of the upper surface of the dummy plate 6 and the surface of the substrate 7 is preferably 0.5 mm or more and 1.5 mm or less. If it is smaller than 0.5 mm, it is presumed that the above-described effects are hardly obtained.

  On the other hand, when the diameter is larger than 1.5 mm, unevenness occurs due to air bubbles being caught between the tip of the porous material 2 and the substrate 7 when the tip of the porous material 2 moves from the dummy plate 6 onto the substrate 7. I think to do.

(Example 2)
Next, the contents relating to the shape of the dummy plate will be described. In FIG. 3 described above, when the tip of the porous material 2 is in contact with the substrate 7 in FIGS. 3 (c) to 3 (d), if it is simultaneously contacted in the coating width direction, in any place in the width direction, It is conceivable that bubbles are involved between the tip of the porous material 2 and the substrate 7. If it becomes such a state, it will apply | coating with a bubble being involved, and generation | occurrence | production of an application | coating unevenness will be anxious.

This problem can be solved by using the following apparatus configuration. FIG. 5 is a schematic view of the positional relationship between the substrate 7, the tip of the porous material 2, and the dummy plate 6 as viewed from above.

  The tip of the porous material 2 and the substrate 7 are installed in the vertical direction with respect to the relative movement direction of the tip of the porous material 2 and the substrate 7. For example, as shown in FIGS. 5A and 5B, a dummy plate The tip of 6 was installed with a predetermined angle. As a result, the tip of the porous material 2 and the substrate 7 can be prevented from contacting simultaneously in the width direction, and can be contacted with a time difference in the width direction. As a result, an effect of preventing entrainment of bubbles between the tip of the porous material 2 and the substrate 7 can be obtained. Furthermore, by relaxing the relative speed between the tip of the porous material 2 and the substrate 7, the above effect can be further enhanced.

  Here, the angle between the tip of the dummy plate 6 and the tip of the porous material 2 (D in FIG. 5) is not limited because it varies depending on the material of the porous material 2, the viscosity of the coating solution, and the like. However, if the angle is large, the starting end portion of the coating film formed on the substrate 7 has a tilted shape, so that it is necessary to finally tilt the product film within the allowable range.

(Example 3)
Next, the shape of the dummy plate will be described . 6 (a) is a top view, FIG. 6 (b) shows a XX 'cross-sectional view of FIGS. 6 (a).

  As described in the first and second embodiments, the coating liquid oozes out and a liquid pool is generated at a portion where the tip of the porous material 2 and the dummy plate 6 are in contact with each other. However, in consideration of mass production, cleaning the dummy plate 6 each time has a lot of loss such as tact and member / solvent necessary for cleaning, and the cost becomes high. Therefore, in order to easily remove the liquid pool generated on the surface of the dummy plate 6, a mechanism for removing unnecessary liquid from the dummy plate 6 is provided. An example thereof will be described with reference to FIG.

  A groove 12 in which the generated liquid pool is accumulated is provided on the upstream side (the opposite side to the direction in which the tip of the porous material 2 relatively moves) from the portion 11 where the tip of the porous material 2 of the dummy plate 6 contacts. In addition, a guide groove 13 is provided so that the liquid can easily flow from the groove 12 to a liquid recovery port 14 connected to a liquid recovery tank (not shown).

  Here, the groove 12 is desirably longer than the coating width (the width of the porous material 2), and the end 15 of the groove is preferably inclined so that the liquid can easily flow into the groove. . Also, the bottom surface 16 of the groove is desirably shaped so that the vicinity of the guide groove is lowered so that the liquid can easily flow into the guide groove. Here, the shape and number of the guide groove 13 and the liquid recovery port are not particularly limited.

  Further, when the tip of the porous material 2 moves from the dummy plate 6 to the substrate 7, it is desirable that the pole tip W of the dummy plate 6 is R-processed in order to reduce wear of the tip of the porous material.

Example 4
Next, the surface treatment of the tip of the dummy plate 6 will be described. FIG. 7 shows a cross-sectional view of the dummy plate 6 used in this embodiment. By forming the water repellent film 17 that repels the coating liquid on the upper surface of the dummy plate 6 upstream of the portion 11 where the tip of the porous material 2 abuts, the excess liquid described in the third embodiment flows into the groove 12. The effect which makes it easy is acquired.

  Further, by forming the water repellent film 18 that repels the coating liquid on the substrate side on the lower surface of the dummy plate 6, it is possible to prevent the liquid from entering the gap formed between the dummy plate 6 and the substrate 7. In addition, an effect of easily controlling the linearity of the coating start end can be obtained.

  Here, a film made of at least one material of DLC, silicon nitride, silicon oxide, and silicon carbide was used as the film used in this example as a film for repelling the coating liquid.

(Example 5)
The effect of the dummy plate described above can be exhibited in various shapes. FIGS. 8A to 8C show examples of the shape of the tip of the dummy plate. A similar effect can be obtained with such a shape. The necessary elements are not particularly limited as long as the angle, height, and length of the upper surface of the dummy plate 6 are the same as those described in the first embodiment.

  The coating apparatus and coating method of the present invention can be used for coating functional films such as antireflection films and wavelength adjusting films on substrates such as solar cells and displays.

DESCRIPTION OF SYMBOLS 1 Metal plate 2,112 Porous material 3 Pump 4 Liquid supply nozzle 5,114 Coating liquid 6,117 Dummy plate 7,111 Substrate 8 Transfer stage 10 Coating film 12 Groove 14 Liquid collection port 17, 18 Water repellent film

Claims (7)

A substrate holder on which the substrate is placed;
A porous material for applying a coating solution to the surface of the substrate;
A liquid supply mechanism for supplying the coating liquid to the porous material;
A transport mechanism capable of relatively moving the substrate holding table and the porous material;
An up-and-down drive mechanism capable of contacting the porous material and the substrate;
A dummy plate that is in contact with the porous material and disposed on the outer periphery of the substrate, and covers a part of the end surface of the substrate;
The dummy plate is disposed to be inclined to the outside of the substrate holding table with respect to a surface on which the substrate is placed in the substrate holding table;
An applicator characterized by. The coating apparatus according to claim 1, wherein a groove for allowing an excessive coating liquid to flow is provided on the surface of the dummy plate upstream of a position in contact with the porous material. The dummy plate, R processing was facilities in the tip section, coating apparatus according to claim 1 or 2. The coating apparatus according to any one of claims 1 to 3, wherein a film that repels the coating liquid is coated on an upper surface of the dummy plate upstream of a position in contact with the porous material. The coating apparatus according to claim 1 , wherein a part of the lower surface of the dummy plate is coated with a film that repels a coating liquid. An application method for applying the coating liquid by infiltrating a coating liquid into a porous material and bringing the porous material into contact with the surface of a substrate,
In the application start part of the substrate, a dummy plate that covers a part of the substrate and is inclined toward the outside of the substrate is installed on the outer periphery of the substrate, and the porous material is in contact with the dummy plate, Applying the coating liquid on the surface of the substrate by relatively moving the porous material and the substrate in one direction;
A coating method characterized by the above. The coating method according to claim 6, wherein the dummy plate is separated from the substrate immediately after the porous material passes through the dummy plate.

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