JPS6310837Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a roll coater that can uniformly apply a coating liquid to the surface of a flat substrate. For example, if the coating liquid is a thin film forming liquid, It can be used in operations to form thin films. The present invention is particularly useful for forming thin films as exemplified below. For example, a transparent conductive film is provided on the inner surface of the front plate to shield external electric fields in a fluorescent display tube whose display part is observed through the front plate, and a so-called front-emitting type fluorescent display tube whose display part is observed through the substrate. In an optical display tube, it can be used as a coating device for a conductive film forming liquid in order to form a transparent conductive film provided on an anode substrate as an anode conductor and a wiring conductor. Furthermore, transparent conductive films used for electrodes of liquid crystal display devices, transparent oxide films formed on the surface of glass plates as a barrier to prevent the elution of alkaline components, and
To form a thin film that is formed on the surface of a glass plate to strengthen it, and a thin film that is applied to the surface of a glass plate to provide various features such as anti-reflection and improved heat reflection. It can also be used as a coating device for thin film forming liquid. [Prior Art] A three-roll roll coater shown in FIG. 9 is known as an apparatus for applying a thin film forming liquid to the surface of a substrate such as glass in order to form a thin film on the surface of the substrate. ing. A conventional roll coater 1 includes a backup roller 3 that supports a substrate 2 from below, and a coating roller 5 that is pressed against the upper surface of the substrate 2 and transfers a thin film forming liquid 4 onto the substrate 2. 4
is poured onto a doctor roller 6, spread uniformly by the doctor roller 6, and supplied to the coating roller 5. Furthermore, a depping method is known as another method for applying a thin film forming liquid to the surface of a substrate. The depping method is a method in which a tank large enough to accommodate the entire substrate is provided, the tank is filled with a thin film forming liquid, and the substrate is immersed and then pulled up to apply the thin film forming liquid to both sides of the substrate. [Problems to be solved by the invention] Conventional roll coaters cannot be applied when the thin film forming liquid is unstable. for example,
Consider the case of a thin film forming liquid in which an organometallic compound (alkoxy compound) containing indium, tin, titanium, etc. is dissolved in an organic solvent that has a low boiling point and is easily volatile. Before the liquid is transferred as a thin film onto the substrate 2, pressure is applied twice between the doctor roller 6 and the coating roller 5 and between the coating roller 5 and the substrate 2. Further, since the solvent component of the liquid continues to volatilize from the stage when the liquid is supplied to the doctor roller 6, the liquid is not uniformly transferred to the coating roller 5. Therefore, of the liquid adhering to the coating roller 5, the part where the solvent component has not volatilized is transferred to the substrate 2, but the part where the solvent component has evaporated remains attached to the coating roller 5 and is transferred to the substrate 2. is not transcribed. Therefore, the thin film forming liquid transferred to the substrate 2 becomes non-uniform. Further, according to the conventional roll coater using three rolls, it is necessary to sandwich the substrate 2 between the back-up roller 3 and the coating roller 5.
When processing substrates of different thicknesses, the roller spacing must be adjusted. Therefore, when using an unstable thin film forming liquid as mentioned above, the above-mentioned dipping method is applied, but this method requires a sufficient amount of liquid to immerse the entire substrate. However, there was a problem that it was not economical because the amount of liquid deteriorated over time increased. Also, when the substrate is pulled out of the liquid after immersion,
The thickness of the thin film-forming liquid that adheres to the substrate is not constant because volatilization starts from the top of the substrate that was lifted first, and the liquid that flows down the surface of the substrate after being lifted tends to accumulate in the lower part of the substrate. There was a problem. Furthermore, since the entire substrate is immersed, there is a problem that the thin film forming liquid cannot be applied to only one side of the substrate as in the case of the roll coater method. [Purpose of the invention] The present invention was made to solve the above-mentioned problems, and it is possible to uniformly apply the coating liquid to only one side of the substrate, and it is particularly effective in forming thin films, which can be unstable. It is an object of the present invention to provide an economical roll coater that can be used with a thin film forming liquid and uses a small amount of the thin film forming liquid. [Means for Solving the Problems] In order to achieve the above object, the roll coater of the present invention includes a saucer for storing the coating liquid, and a tray that is partially immersed in the coating liquid so that the coating liquid adheres to the outer peripheral surface. In a roll coater equipped with a rotating coating roller and a transfer roller that intermittently transfers a substrate onto the coating roller, on the outer circumferential surface of the coating roller, so that the coating amount is different between the central part and the outer part, The coating roller is characterized in that minute recesses are formed on the outer peripheral surface of the coating roller to change the surface condition of the coating roller. [Function] Since the coating roller rotates with a portion immersed in the coating liquid in the saucer, the coating liquid always adheres to the outer peripheral surface of the coating roller that rises from the coating liquid. A plurality of minute recesses such as grooves and dotted recesses are formed on the outer circumferential surface of the application roller, and the surface condition is largely uneven at the center of the outer circumferential surface and less uneven at the outer circumferential surface. Therefore, the amount of the coating liquid that adheres to the above-mentioned outer circumferential surface is larger in the central part than in the outer part. Here, the substrate is sent onto the coating roller by the transfer roller, but when the tip of the substrate comes into contact with the top of the outer peripheral surface of the coating roller, the transfer roller temporarily stops driving. The coating roller rotates with the tip of the substrate in contact with the top of the coating roller, and the coating liquid adheres to the outer peripheral surface of the coating roller and is drawn up. As the application roller rotates, a pool of application occurs in the gap in front of the contact portion between the substrate and the application roller. The application liquid in the pooled portion is pressed between the application roller and the substrate by the rotation of the application roller, and therefore moves toward the outside of the application roller where the substrate is not in contact. However, since the amount of the coating liquid that adheres to the outer peripheral surface of the coating roller and is drawn up is originally larger in the central portion, the shape of the pooled portion is stable. That is, the amount of the coating liquid accumulated is constant at any location on the coating roller. When the amount of liquid in the reservoir reaches a predetermined amount, the transfer roller starts transferring the substrate again. The bottom surface of the substrate comes into contact with the pool of coating liquid and is coated with the coating liquid, but some of the attached coating liquid is pushed back in the rotational direction of the coating roller at the contact area between the substrate and the coating roller. The coating liquid is uniformly applied to the lower surface of the substrate. [First Example] Hereinafter, a first example of the present invention will be described. FIG. 1 is a plan view showing the roll coater of the first embodiment, and FIG. 2 is an enlarged sectional view taken along the line - in FIG. 1. The roll coater 7 of this embodiment is incorporated in a part of a thin film forming apparatus that applies an unstable thin film forming liquid to a glass substrate 8 and then bakes it to form a thin film. Although not shown, the thin film forming apparatus includes a cleaning device for the substrate 8, a drying device for heating and drying the cleaned substrate 8, a cooling device for cooling the substrate 8 whose temperature has increased due to heating, and a substrate 8. It is equipped with a roll coater 7 for applying a thin film forming liquid to the substrate 8 and a heating device for baking the substrate 8 coated with the liquid. Now, in the figure, 9 is a transfer roller of the roll coater 7 which is disposed continuously next to the cooling device. The transfer roller 9 is configured such that a pair of guide rollers 11, 11 are respectively provided on a plurality of rotation shafts 10 that are rotationally driven by a drive source (not shown). As shown in FIG. 1, the guide roller 11 is
It is composed of a disk-shaped roller section 11a that supports both sides of the substrate 8 and conveys the substrate 8, and a dish-shaped guide section 11b provided on the outer end surface of the roller section 11a. The outer diameter of the guide portion 11b is preferably set to be at least larger than the outer diameter of the roller portion 11a. The outer circumferential surface of the portion 11b is set to protrude outward from the center of the rotating shaft 10, and serves as a guide for the board 8.
Ensures retention. Further, the inner end surface of the guide portion 11b is formed into a tapered surface that expands outward from the center of the rotating shaft 10. Even if the substrate 8 that is being transferred comes off the roller section 11a for some reason, the substrate 8 is guided by the tapered surface on both sides, so that it can easily return to the outer peripheral surface of the roller section 11a. In addition, a pair of guide rollers 11, 1
At least one of the substrates 1 can be slid freely in the direction of the rotating shaft 10 and fixed at any desired position, and is configured to be able to guide and transport substrates 8 of various sizes. Further, in this embodiment, a pair of guide rollers 1 are provided on a common rotating shaft 10.
1 and 11 to constitute the transfer roller 9, a shaft may be provided for each guide roller 11 so that each guide roller 11 is rotated independently. Further, the transfer roller 9 is provided with a height adjustment mechanism (not shown), and the transfer roller 9 is connected to the substrate 8.
The substrate 8 is moved in the vertical direction as a whole while maintaining the transfer direction in a horizontal state, and is configured such that the position at which the substrate 8 is fed to the coating roller 13, which will be described later, can be arbitrarily set. Next, in a portion adjacent to the transfer roller 9 in the transfer direction,
A tray 12 and an application roller 13 are provided. The saucer 12 has the shape of a cylinder divided in half in the axial direction, and is oriented such that the direction in which the substrate 8 is transferred and the axis (longitudinal direction) are orthogonal to each other, and the transfer roller 9 transfers the substrate 8. It is located below the transport plane. Although not shown, a drive mechanism is attached to the tray 12 so that it can be moved downward from the above-mentioned position during cleaning or the like. Further, inside the saucer 12, a thin film forming liquid 14 (hereinafter abbreviated as liquid 14) is stored as a coating liquid. In this embodiment, the liquid 14 in particular is a liquid that contains a thin film-forming component in a volatile organic solvent and is easily deteriorated. Although not shown, an automatic supply device for the liquid 14 is connected to the lower part of the saucer 12 via a supply pipe, and is configured to maintain the amount of liquid in the saucer 12 at a minimum constant level. ing. Further, on both side edges of the opening of the saucer 12, flange-shaped covers 12a are provided facing inward in order to suppress volatilization of the liquid. A portion of the applicator roller 13 enters inward from the opening of the tray 12 and is disposed at a position slightly away from the inner surface of the peripheral wall of the tray 12, so that a portion of the applicator roller 13 is always inside the tray 12. It is designed to be immersed in a liquid 14 stored in the container. The topmost position of the outer peripheral surface of the coating roller 13 is configured to be slightly above the lower surface of the substrate 8 transferred by the transfer roller 9. Further, the application roller 13 is connected to a drive source 15 and is configured to be freely driven according to the work order. Further, as shown in FIG. 3, a large number of vertical grooves 17 having a substantially constant depth are formed on the outer circumferential surface 16 of the application roller 13 as recesses for adhering and temporarily retaining the liquid 14. There is. The vertical grooves 17 are provided parallel to each other along the circumferential direction of the outer circumferential surface 16, and are formed densely in the central portion 16a of the application roller 13 and relatively sparsely in the outer portion 16b. The outer circumferential surface 16 near both ends of the application roller 13 is provided with a portion where almost no vertical grooves 17 are formed. Since the distribution density of the vertical grooves 17 changes continuously from the center portion 16a to both outer portions 16b, the surface condition of the outer circumferential surface 16 of the application roller 13 and the amount of adhesion vary depending on the center portion 16a.
It changes continuously from to the outer part 16b. Note that the above-mentioned surface condition indicates the roughness (that is, unevenness) of the outer circumferential surface 16 of the application roller 13, and the magnitude of this roughness is determined by the recesses (in this example, the vertical grooves 17) as in this example. It is determined by the density of the distribution of liquid 14, and also by the size of the depth of the recess itself (or the volume of the recess in which the liquid 14 is held). For example, as in this embodiment, the depth of the vertical grooves 17 may be constant and the surface condition may be changed by changing the distribution.
Although concavities are uniformly distributed throughout 6,
The surface condition may be changed so that the depth of the concave portion near the center portion 16a increases (so that the amount of liquid 14 that can be held increases) so that the amount of adhesion increases. Furthermore, the surface condition of the outer circumferential surface 16 of the application roller 13 may be changed by changing the density and density of the distribution of the recesses in combination with the depth and width of the recesses. The vertical grooves 17 can be easily formed by rotating the application roller 13 and applying a tool such as a file or a cutting tool to the outer peripheral surface 16. In this case, the depth, shape, distribution, etc. of the vertical grooves 17 can be varied in various ways by changing the rotational speed of the application roller 13, the feeding speed of the file, the roughness of the file, etc. Further, the material of the application roller 13 is made of metal with a long life in this embodiment, but ceramics or the like may be used, or resin or the like may be used as long as the material is not eroded by the liquid 14. Next, a press roller 18 is provided above the application roller 13. The presser roller 18 is
It can be moved downward by a drive means (not shown), and is configured to press the upper surface of the substrate 8 being transferred on the coating roller 13 by its own weight, thereby preventing the substrate 8 from lifting up. Next, adjacent to the application roller 13 in the rotational direction, a discharge-side transfer roller 19 is provided for transporting the substrate 8 from above the application roller 13 . The transfer roller 19 has substantially the same configuration as the transfer roller 9, and is configured to guide and convey the substrate 8, the lower surface of which is coated with a thin film of the liquid 14, while supporting only both sides. As described above, a heating device is continuously disposed adjacent to the transfer roller 19 on the discharge side in the transfer direction, and the substrate 8 coated with the liquid 14 on the lower surface is heated by the transfer roller 19. and is configured to be fed into a heating device. In this embodiment, the liquid 14 applied to the substrate 8 is unstable and easily deteriorates, and dust in the atmosphere poses an obstacle to the thin film forming operation.
Preferably, the substrate 8 and the liquid 14 are not exposed directly to the outside air. For example, roll coater 7
If the parts of the cleaning equipment, drying equipment, etc. where the substrate 8 is transferred are covered with a cover, etc., and configured so that the temperature, humidity, etc. inside the cover can be freely adjusted, dust and moisture in the outside air can be eliminated from the process. This enables consistent thin film formation operations under optimal environmental conditions. Next, the operation of the configuration described above will be explained. After the substrate 8 is cleaned by a cleaning device, it is heated by a drying device to remove moisture. The substrate 8 whose temperature has increased due to heating is conveyed while being cooled by a cooling device, and sent to the transfer roller 9 of the roll coater 7 . The transfer roller 9 transfers the substrate 8 while supporting both sides of the substrate 8 by the roller portions 11a of the guide rollers 11. Therefore, the upper and lower surfaces of the clean substrate 8 will not be contaminated during transportation. Next, the substrate 8 is fed into the coating roller 13 from a position slightly lower than the upper part of the outer peripheral surface of the coating roller 13. The substrate 8 is coated with a coating roller 13.
The lower edge of the tip contacts the outer peripheral surface 16 of the
The application roller 13 is moved by the driving force of the transfer roller 9.
While maintaining contact with the applicator roller 1, tilt it slightly.
I will move up to 3. From the time when the substrate 8 comes into contact with the coating roller 13, as shown in FIG. It becomes possible to be supported only by the department. Therefore, even if the substrate 8 is distorted or the rotation axis of the coating roller 13 is not kept horizontal, the tip of the substrate 8 and the coating roller 13
will definitely come into contact with. Furthermore, since the rear end of the substrate 8 is supported only by the pair of guide rollers 11, vibrations transmitted from the transfer roller 9 to the substrate 8 (and the contact portion with the coating roller 13) can be suppressed to a minimum. ing. When the tip of the substrate 8 reaches the top of the coating roller 13, the operation of the transfer roller 9 is temporarily stopped, but the coating roller 13 continues to rotate. The liquid 14 always adheres to the outer peripheral surface of the application roller 13 that rises from the liquid 14 stored in the saucer 12, and this adhered liquid 14, as shown in FIGS. 1 and 2, It is stopped forward in the rotational direction at the contact portion with the substrate 8. Then, as the application roller 13 rotates, the application roller 13
A pool 20 of the liquid 14 is formed in the gap between the substrate 8 and the application roller 13 (at the front in the rotational direction) due to capillary action.
will arise. Here, the pumping up of the liquid 14 by the application roller 13 and the formation of the reservoir 20 are explained in FIGS. 5 to 7.
This will be explained in more detail with reference to the drawings. As shown in FIG. 5, the liquid 14 that adheres to the outer peripheral surface 16 of the coating roller 13 and is drawn up and enters the reservoir 20 is transferred to the substrate 8 by the rotation of the coating roller 13.
, the substrate 8 tends to move toward the outer part 16b of the application roller 13 with which it is not in contact. Therefore, as shown in FIG.
The surface condition of the outer peripheral surface 16 of is uniform, and the attached liquid 1
If the amount of liquid 14 is approximately constant at any part of the outer circumferential surface 16, a large amount of liquid 14 will collect near both ends of the substrate 8, and the amount of liquid 14 will be relatively small at the center of the substrate 8, causing the substrate 8 The overall shape of the pool 20 formed on the lower side becomes uneven. However, since the applicator roller 13 of this embodiment has the vertical grooves 17 formed on the outer circumferential surface 16, the liquid 14
The amount of adhesion is greatest at the center portion 16a of the application roller 13, and decreases toward the outer portion 16b. Therefore, as shown in FIG. 7, due to the movement of the liquid 14 inside the pool 20 described above, the overall shape of the pool 20 is stabilized, and the amount of the liquid 14 accumulated at any part of the application roller 13 is almost constant. will be maintained. Since almost no vertical grooves 17 are formed on the outer circumferential surface near both ends of the application roller 13, there are some parts where the amount of liquid 14 adhered is small, so the liquid moves outward on the outer circumferential surface 16. 14
are successively discharged to both end surfaces of the application roller 13. In addition, the substrate 8 may be damaged by the application roller 13 for some reason.
If it floats away from the substrate 8, a gap will be created between the substrate 8 and the coating roller 13, and the reservoir 20 will no longer be able to maintain a constant amount of liquid, resulting in instability. However, as described above, in this embodiment, the contact between the substrate 8 and the coating roller 13 is ensured, and the vibration transmitted to the contact portion between the substrate 8 and the coating roller 13 is small. Therefore, as the application roller 13 rotates, the pool 2
0 grows smoothly and stably, has a constant liquid volume as described above, and has a regular shape with a constant width in the transfer direction of the substrate 8. Now, when the amount of liquid in the reservoir 20 reaches a predetermined amount, the presser roller 18 moves downward and the substrate 8
The substrate 8 is in contact with the upper surface of the substrate 8, and prevents the substrate 8 from lifting up due to distortion or the like due to its own weight. Then, the transfer roller 9 begins to transfer the substrate 8 again. The lower surface of the substrate 8 comes into contact with the reservoir 20 of the liquid 14 and is coated with the liquid 14, but a portion of the attached liquid 14 is mixed with the rotational direction of the coating roller 13 at the contact area between the substrate 8 and the coating roller 13. Since it is pushed back in the opposite direction, the liquid 14 is uniformly applied to the lower surface of the substrate 8. Note that in this step, instead of applying pressure to the liquid 14 and transferring it to the substrate 8, the application roller 13
A reservoir 20 of the liquid 14 is formed in the gap between the substrate 8 and the substrate 8, and the liquid 14 is applied by bringing the substrate 8 into contact with the reservoir 0. Therefore, it is sufficient that there is enough liquid in the saucer 12 to soak at least a portion of the application roller 13, and an automatic supply device is installed so that the amount of liquid in the saucer 12 is maintained at a constant minimum necessary amount. Just adjust it. In addition, since the saucer 12 is provided with a cover 12a and the volatilization of the liquid 14 is suppressed, it is possible to always apply the liquid 14 of a constant quality, and the yield of the liquid 14 is further improved. A low-cost thin film formation operation can be realized. Next, the substrate 8 is sent forward by the discharge side transfer roller 19 and taken out from the coating roller 13. Since the transfer roller 19 on the discharge side only contacts both sides of the substrate 8, it does not stain the back surface of the substrate 8 on which the liquid 14 has just been applied. Also,
Since the liquid 14 in this example contains volatile components,
The liquid 14 applied to the substrate 8 dries to some extent while being carried to the next step by the transfer roller 19. Next, the substrate 8 is fed into a heating device. Then, the liquid 1 attached to the bottom surface of the substrate 8
4 is heated and dried to form a uniform thin film. Further, in the above embodiments, a thin film forming liquid that is easily deteriorated was used as a coating liquid, but it goes without saying that the present invention can be applied to other stable thin film forming liquids as well as various other liquids. In addition, in the embodiment, one presser roller 18 was provided above the application roller 13, but when processing a light substrate, etc., it is necessary to prevent the substrate 8 from floating.
In order to ensure more reliable contact between the substrate 8 and the application roller 13, a plurality of presser rollers may be provided before and after the application roller 13. [Second Embodiment] Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in the shape of the recess formed in the outer circumferential surface 16 of the application roller 13 and in the manner in which the surface condition of the outer circumferential surface 16 is changed. The other configurations and operations are substantially the same as those in the first embodiment, so their explanations will be omitted. As shown in FIG. 4, a large number of lateral grooves 23 as recesses are formed on the outer circumferential surface 22 of the application roller 21. As shown in FIG. The horizontal groove 23 is connected to the rotation shaft 2 of the application roller 21.
4, and are formed at a relatively narrow interval in the central region A of the application roller 21, and with a slight interval in the outer regions B, B.
Then, a region C near both ends of the application roller 21,
In C, almost no lateral grooves 23 are formed. The density of the distribution of the lateral grooves 23 changes stepwise from the central part to both outer parts, so that the applicator roller 21
The surface condition of the outer peripheral surface 22 of
There is a stepwise change from 1 to 3, to region C where the amount of adhesion is relatively small. The lateral grooves 23 may be formed using sandpaper or the like with an appropriate particle size for each region, and the relationship between the depth of the lateral grooves 23 and the interval (density of distribution) between the lateral grooves 23 will be explained in the section of the first embodiment. As you can see, various settings can be made. [Third Embodiment] Next, a third embodiment of the present invention will be described. In this example, the shape of the recess formed on the outer peripheral surface of the application roller is different from the first example and the second example, and the way to change the surface condition of the outer peripheral surface is the same as in the second example. It is also said to be gradual. The other configurations and operations are substantially the same as those in the first embodiment, so their explanations will be omitted. Although not shown, a knurled groove serving as a recess is formed on the outer peripheral surface of the application roller. The knurled groove is a mesh-like groove composed of grooves in two directions that intersect with each other.The central area of the applicator roller has a relatively fine mesh and a large number of grooves, and the outer area has a large number of grooves. It is formed with a slightly rougher texture. Further, almost no knurling grooves are formed in the areas near both ends of the application roller.
Since the size of the knurled grooves changes stepwise from the center to the outer areas, the surface condition of the outer circumferential surface of the applicator roller also changes from a rough area with many unevenness in the center to a relatively rough area. There is a gradual change to the smooth outer region. The knurled grooves may be formed using sandpaper or the like with an appropriate particle size for each region, and the relationship between the depth of the knurled grooves and the spacing between the knurled grooves (density of distribution) will be explained in the section of the first embodiment. As you can see, various settings can be made. Further, in place of the knurled groove of this embodiment, an oblique groove inclined with respect to the rotation axis of the application roller may be provided. [Fourth Example] Next, a fourth example of the present invention will be described. In this example, the shape of the recess formed on the outer peripheral surface of the application roller is different from the first to third examples, and the way to change the surface condition of the outer peripheral surface is the same as in the first example. It is also considered continuous. The other configurations and operations are substantially the same as those in the first embodiment, so their explanations will be omitted. Although not shown in the drawings, irregular grooves with a substantially constant depth are formed as recesses on the outer circumferential surface of the application roller. Irregular grooves are composed of grooves in various directions that intersect at various angles, with a large number of grooves being relatively densely formed in the center of the applicator roller and relatively sparsely forming in the outer part. , are formed with spaces between them.
In addition, almost no irregular grooves are formed near both ends of the application roller. Since the density of the irregular groove distribution changes continuously from the center to both outer parts, the surface condition of the outer peripheral surface of the application roller also changes.
It changes continuously from the rough central part to the relatively smooth outer part. In addition, irregular grooves can be formed by rubbing the outer peripheral surface in various directions with sandpaper of an appropriate particle size, and the relationship between the depth of the irregular grooves and the density of the distribution was explained in the section of the first embodiment. It can be set in various ways. [Fifth Example] Next, a fifth example of the present invention will be described. In this example, the shape of the recess formed on the outer peripheral surface of the application roller is different from the first to fourth examples, and the way to change the surface condition of the outer peripheral surface is the same as in the second example. It is also said to be gradual. The other configurations and operations are substantially the same as those in the first embodiment, so their explanations will be omitted. Although not shown, dot-like (matte-like) recesses are formed on the outer circumferential surface of the application roller. The recess is formed relatively large in the central region of the application roller so that a large amount of liquid adheres thereto, and is formed relatively small in the outer region,
It is configured to reduce the amount of liquid attached. In addition, almost no recesses are formed in the areas near both ends of the application roller. Since the size (or depth) of the recesses changes stepwise from the center to each outer region, the surface condition of the outer circumferential surface of the applicator roller also varies from the center with many irregularities. There is a gradual change to a relatively smooth outer region. The recesses can be formed, for example, by sandblasting. When processing the central part of the applicator roller, the other parts are covered and blasted using relatively large-grained sand, and the outer part is When processing, you can cover the other parts and blast using relatively small-grained sand. [Effects of the invention] As explained above, the roll coater of the invention forms a concave portion on the outer peripheral surface of the coating roller so that the amount of coating liquid attached is large at the center of the coating roller and small at the outer portion. This configuration has the effect that the coating liquid can be uniformly applied to the surface of the substrate. In order to confirm the above effect, organic In was placed on a glass substrate with a width of 500 mm and a length of 1000 mm, as shown in
Thin film forming solution containing 5% compound and 5% organic Sn compound
The containing thin film forming liquid was applied using the roll coater of the present invention to form a thin film. Then, when sheet resistance values were measured at 15 positions as shown in FIG. 8, data as shown in the table below was obtained.

[Table] It is known that the sheet resistance of a thin film is proportional to the thickness of the thin film, so it is possible to infer the fluctuation in film thickness from the fluctuation in the sheet resistance value. By analogy with the above results and the measurement error range, it can be seen that the film thickness is uniform.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention;
Figure 2 is a sectional view taken along the - line in Figure 1;
The figure is a plan view of the applicator roller of the first embodiment, FIG. 4 is a plan view of the applicator roller of the second embodiment, FIG. 5 is a perspective view of the applicator roller in operation, and FIG. 6 is the shape FIG. 7 is a plan view of a coating roller and a substrate that have uneven pools, FIG. 8 is a plan view of a coating roller and a substrate that have pools that are uniform in shape, and FIG. FIG. 9 is a side view of a conventionally used roll coater. 7...Roll coater, 8...Substrate, 9, 19...
... Transfer roller, 13, 21 ... Application roller, 14
... Thin film forming liquid as a coating liquid, 16 ... Outer peripheral surface, 16a ... Central part, 16b ... Outer part, 17
...Vertical groove as a recess, 23...Horizontal groove as a recess.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A saucer into which a coating liquid is placed, a coating roller that is partially immersed in the coating liquid and rotates while adhering the coating liquid to the outer peripheral surface, and a substrate that is intermittently placed on the coating roller. In the roll coater, a plurality of minute recesses for retaining the coating liquid are formed on the outer peripheral surface of the application roller, the volume of the recesses is increased in the center of the outer peripheral surface, and A roll coater characterized in that the volume of the recess is reduced in the outer part of the surface. (2) The roll coater according to claim 1, wherein the volume of the recess on the outer circumferential surface of the application roller decreases continuously from the central part to the outer part. (3) The roll coater according to claim 1, wherein the volume of the recess on the outer circumferential surface of the application roller decreases stepwise from the center to the outer part. (4) The roll coater according to claim 1, 2, or 3, wherein the recessed portion is a vertical groove parallel to the rotation direction of the coating roller. (5) Utility model registration claim 1 or 2, wherein the recess is a lateral groove parallel to the rotation axis of the application roller.
The roll coater according to item 1 or 3. (6) The roll coater according to claim 1, 2, or 3, wherein the recessed portion is a knurled groove. (7) The roll coater according to claim 1, 2, or 3, wherein the recessed portion is an irregular groove. (8) The roll coater according to claim 1, 2, or 3, wherein the recesses are point-like recesses.