JP2015066502A - Coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating apparatus capable of suppressing deterioration in coating quality.SOLUTION: A coating apparatus 10 of the present invention comprises: a first flow passage 13 connecting between a tank 11 for storing a coating liquid and a head 12 forming a coating film by coating the coating liquid on an object 19; a first pump 14 provided in the first flow passage 13 and supplying the coating liquid to the head 12 from the tank 11 in a coating execution period; a filter 15 provided in the first flow passage 13, upstream from the first pump 14 and filtering the coating liquid; a second flow passage 16 branched from the first flow passage 13, at a position between the filter 15 and the first pump 14 and connected to the first flow passage 13 on the upstream side of the filter 15; and a second pump 17 provided in the second flow passage 16 and circulating the coating liquid via at least the filter 15 and the second flow passage 16 in a coating stopping period.

Description

  The present invention relates to a coating apparatus, and more particularly to a coating apparatus that supplies slurry stored in a tank to a coating head using a pump.

  An example of this type of coating apparatus is disclosed in Patent Document 1. According to Patent Document 1, the coating liquid tank and the nozzle (coating head) are connected by a feed line. A pump and a three-way switching valve are attached to the feed line, and the three-way switching valve is connected to the coating liquid tank by a return line. A relief line is connected to the nozzle, and an automatic valve and a relief valve are attached to the relief line. The three-way switching valve and the relief valve are controlled in synchronization by the control unit.

  When applying the coating liquid to the substrate, the automatic valve is closed. The coating liquid pressurized by the pump passes through the three-way switching valve, is sent to the nozzle through the feed line, and is applied to the surface of the substrate (support) from the nozzle discharge port.

  When stopping the application of the coating liquid, the control unit switches the three-way switching valve. The coating liquid pressurized by the pump is returned to the coating liquid tank through a return line. At the same time, the control unit opens the automatic valve, and the coating liquid remaining in the internal space of the nozzle is discharged outward from the relief valve via the relief line. For this reason, the coating liquid does not leak out from the discharge port of the nozzle to the substrate side, and drag of the coating film can be prevented.

JP 2001-293418 A

  In consideration of contamination of the coating liquid stored in the coating liquid tank, it is necessary to attach a filter to the feed line. However, if the coating liquid stays in the upstream of the filter during the coating stop period, the filtering characteristics of the filter and the specific gravity of the coating liquid supplied to the coating head are unstable at least for a temporary period after the restart of coating. The coating quality may be reduced. The coating stop period is a period that is provided when the coating liquid in the support or tank that is the target of coating runs out, or when a coating abnormality occurs, which occurs on a daily basis in mass production. It is.

  Therefore, a main object of the present invention is to provide a coating apparatus that can suppress a decrease in coating quality.

  A coating apparatus according to the present invention (10: reference numeral corresponding to the embodiment, the same applies hereinafter) is applied to a tank (11) for storing a coating liquid and a coating film by applying the coating liquid to an object (19). Are provided in the first flow path (13) and the first flow path (13) connecting the head (12) forming the coating liquid, and the coating liquid is transferred from the tank (11) to the head (12) during the coating execution period. A first pump (14) to be supplied, a filter (15), a filter (15) provided on the first flow path (13) and at a position upstream of the first pump (14) for filtering the coating liquid; A second flow path (16) branched from the first flow path (13) to the first pump (14) and connected to the first flow path (13) on the upstream side of the filter (15), and a second flow A second pump (17) is provided in the passage (16) and circulates the coating liquid through at least the filter (15) and the second flow path (16) during the coating stop period.

  Preferably, the first pump (14) and the second pump (17) are driven alternatively.

  Alternatively, preferably, the second pump (17) is driven at least in a continuous period from the time preceding the end of the coating stop period to the end of the coating stop period.

  Preferably, the film thickness measuring device (21) for measuring the film thickness of the coating film applied to the object (19), and the driving time of the second pump (17) based on the measurement result of the measuring device (21) And a drive time adjusting device (22) for adjusting.

  Preferably, the second channel (16) is connected to the first channel (13) via the tank (11).

  If the coating liquid stays in the upstream of the filter during the coating stop period, the filtering characteristics of the filter and the specific gravity of the coating liquid supplied to the head become unstable at least during a temporary period after the resumption of coating. Based on this, the second flow path and the second pump are provided. The coating liquid circulates through a part of the first flow path and the second flow path during the coating stop period. As a result, the filtering characteristics of the filter and the specific gravity of the coating liquid supplied to the head are stabilized immediately after resuming the coating, and a decrease in coating quality is suppressed.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

FIG. 1 is a schematic diagram illustrating an example of a coating apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating another example of the coating apparatus according to the embodiment of the present invention. FIG. 3 is a graph showing the results of measuring the relationship between the coating distance and the coating film thickness from the point of time when the coating was resumed after the coating stop period. FIG. 3A is a graph in the example, and FIG. 3B is a graph in the comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited or limited to the following examples.

  Referring to FIG. 1, a coating apparatus 10 according to this embodiment connects a tank 11 that stores a coating liquid and a head 12 that forms a coating film by applying the coating liquid to an object 19. A first pump 14 provided in the first flow path 13 and the first flow path 13 for supplying the coating liquid from the tank 11 to the head 12 during the coating execution period, on the first flow path 13 and on the first pump 14. A filter 15 that is provided at an upstream side, filters the coating liquid, branches from the first flow path 13 between the filter 15 and the first pump 14, and is connected to the first flow path 13 on the upstream side of the filter 15. Provided in the second flow path 16 and the second flow path 16 is a second pump 17 that circulates the coating liquid through at least the filter 15 and the second flow path 16 during the coating stop period. The coating liquid in the coating execution period is applied onto the object 19 through the path of the solid arrow. The coating liquid in the coating stop period circulates along the path indicated by the broken arrow. Specifically, the first flow path 13 including the filter 15, the second flow path 16 including the second pump 17, and the tank 11 , Circulate through the connected pathways.

  The wet paint film 20 a applied to the object 19 is dried by the drying device 18. The thickness of the dried coating film 20 b after drying is continuously measured by the film thickness measuring device 21. Then, the drive time adjusting device 22 adjusts the drive time of the second pump 17 based on the thickness measurement result of the dry coating film 20b measured by the film thickness measuring device 21.

  A coating liquid is stored in the tank 11. The coating liquid may be of any type or property, such as ceramic slurry or resin.

  The ceramic slurry is a mixed solution containing ceramic particles, a resin component, and a solvent. The ceramic slurry is used for manufacturing a ceramic green sheet.

The ceramic particles are not particularly limited, and various dielectric materials can be used. For example, oxides made of metals such as titanium, aluminum, barium, lead, zirconium, silicon, yttrium, barium carbonate, barium titanate, Pb (Mg _1/3 , Nb _2/3 ) O ₃ , Pb (Sm _{1 / 2} , Nb _1/2 ) O ₃ , Pb (Zn _1/3 , Nb _2/3 ) O ₃ , PbThO ₃ , PbZrO _{3 and the} like can be used. These may be used alone or in combination of two or more.

  Examples of the resin component include a binder resin and a plasticizer. As the binder resin, water-based polymers such as polyurethane resin, urea resin, melamine resin, epoxy resin, vinyl acetate resin, acrylic resin, polyvinyl alcohol, polyvinyl butyral, and the like can be used. These may be used alone or in combination of two or more. As the plasticizer, for example, phthalic acid esters such as dioctyl phthalate can be used.

  As the solvent used for the slurry, toluene, ethanol, methyl ethyl ketone, isopropyl alcohol, γ-butyrolactone, or the like can be used. These may be used alone or in combination of two or more. Moreover, you may add a dispersing agent, an antistatic agent, surfactant, etc. in a slurry as needed.

The slurry preferably has a viscosity of 10 to 200 mPa · s. The slurry can be produced by a method such as wet mixing using a ball mill.
The coating liquid stored in the tank 11 is supplied from the tank 11 to the head 12 via the first flow path 13 by the first pump 14 provided in the first flow path 13. A filter 15 is provided on the upstream side of the pump 14 in the first flow path 13, and the coating liquid is filtered by the filter 15 and sent to the head.

  The filter 15 collects foreign matter in the coating liquid. When the coating liquid is filtered by the filter 15, solidified substances such as ceramic particles and binder resin contained in the slurry that is the coating liquid accumulate in the filter 15.

  The first pump 14 is provided on the downstream side of the filter 15 in the first flow path 13 and supplies the coating liquid to the head 12. As the first pump 14, for example, a positive displacement pump such as a gear pump can be used. However, the present invention is not limited to this, and any type of pump can be used.

  The coating liquid is pushed out from the head 12 and applied to the support (object) 19. In FIG. 1, the head 12 shows a die coating method, but the present invention is not limited to this. Depending on the viscosity and specific gravity of the coating liquid, the thickness of the coating film to be formed, and the like, for example, a coating method using a blade, air, knife, gravure, ink jet or the like may be employed.

  The support (object) 19 is a base on which the coating liquid is applied, and paper, plastic film, metal, or the like can be used, and the shape thereof may be flat (plate). However, it may be wound around a roll. As the plastic film, a polyester film, a polyester film coated with a release layer in advance, or the like can be used, and a PET film, a PEN film, a PP film, or the like can be preferably used.

  If the support is wound on a roll, the coating liquid can be applied continuously to the support, but the roll can be replaced even if the support is in the form of a single wafer or a roll. In this case, there is a case where a coating stop period for stopping the discharge of the coating liquid from the head is provided. In addition, a coating suspension period is provided when the tank is replaced.

  If the supply of the coating liquid is stopped during the coating stop period, the coating liquid stays in the filter 15, and the same component material adheres to the coagulated substance already accumulated in the filter 15, resulting in an increase in the coagulated substance. Therefore, the solvent ratio of the coating liquid staying in the filter 15 is increased, and the specific gravity of the coating liquid is temporarily decreased immediately after the restart of coating. However, immediately after that, a part of the material adhering to the solidified material flows out downstream of the filter 15 and the specific gravity of the coating liquid temporarily increases. As described above, immediately after resuming the coating, the specific gravity of the coating liquid is increased and decreased, resulting in instability of the coating film and the coating quality may be deteriorated. In order to prevent this deterioration in quality, a second flow path 16 that branches from the first flow path 13 between the filter 15 and the first pump 14 and is connected to the first flow path 13 on the upstream side of the filter 15 is provided. A second pump 17 is disposed in the path 16. The second pump 17 circulates the coating liquid via the filter 15 and the second flow path 16 during the coating stop period. In the present embodiment, the second flow path 16 is connected to the first flow path 13 via the tank 11.

  Thus, the specific gravity of the coating liquid downstream of the filter 15 can be stabilized by using the second pump 17 during the coating stop period to circulate the coating liquid along the path passing through the filter 15. Accordingly, since the coating liquid having the same specific gravity as that during continuous coating can be supplied to the head 12 even when the coating is resumed, it is possible to suppress coating film thickness defects caused by variations in the specific gravity of the coating liquid. .

  For example, a positive displacement pump such as a gear pump can be used as the second pump 17. Further, since the second pump 17 is used for the purpose of circulating the coating liquid during the coating stop period, the discharge accuracy may be lower than that of the first pump 14. Tube pumps and roller pumps can also be used as inexpensive pumps that do not require discharge accuracy. In particular, when a pump of a type that feeds metal parts without directly touching the coating liquid, the possibility that the metal wear pieces become foreign matters is low, and the life of the pump itself can be extended.

  The first pump 14 and the second pump 17 may alternatively be driven while corresponding to the coating execution period and the coating stop period, and the second pump 17 is at least from the time prior to the end of the coating stop period. You may drive in the continuous period until the end of a coating stop period. When the coating stop period is short, circulation by the second pump 17 is started immediately after the coating is stopped (after the first pump 14 is stopped), and the coating is resumed (driving the first pump 14). At the same time, the circulation is stopped. When the coating suspension period is long, it is not always necessary to continue the circulation. For example, the second pump 17 is continuously driven to start circulation for a predetermined time (from the time prior to the end of the coating stop period to the end of the coating stop period) before restarting the coating, and the coating is restarted. At the same time, the circulation can be stopped.

  When the coating liquid is retained in the filter 15, the time required to stabilize the coating quality immediately after resuming the coating can vary depending on the characteristics of the coating liquid and the coating conditions. When the circulation of the coating liquid by the second pump 17 is not continuously performed during the coating stop period, the stable state of the coating film thickness when the coating is resumed is observed, and the data is applied. It is good to feed back to adjustment of the drive time of the 2nd pump 17 of a stop period.

  After applying the coating liquid, the wet coating film 20 a is dried by the drying device 18. As a heat source of the drying device 18, hot air, electric heat, microwaves, infrared rays, far infrared rays and the like can be used alone or in combination, and it is preferable to carry out hot air drying and far infrared drying alone or in combination.

  The drying temperature and the drying air volume in the drying step may be appropriately selected according to the production line speed (coating speed), the type of coating liquid, and the like. When the coating liquid is a ceramic slurry, it may be appropriately selected according to the type of solvent used in the slurry, the slurry concentration, the coating thickness of the slurry, and the like. The drying temperature is preferably from room temperature to 150 ° C, more preferably from 50 ° C to 150 ° C. By setting the drying temperature to 50 ° C. or higher, the solvent does not remain in the slurry, and voids can be prevented from being generated in the ceramic in the subsequent firing step. Further, by setting the drying temperature to 150 ° C. or lower, it is possible to suppress the occurrence of blisters and dents on the surface of the green sheet due to the rapid volatilization of the solvent. Further, a plurality of drying zones may be provided, and the temperature may be changed for each drying zone.

  The thickness of the dried coating film 20 b after drying is continuously measured by the film thickness measuring device 21. The film thickness can be measured by methods such as fluorescent X-ray analysis, X-ray reflectance measurement, and ellipsometry. In the present embodiment, the film thickness is measured on the dried coating film 20b after drying, but the film thickness measuring device 21 is arranged upstream of the drying device 18 and the wet coating film 20a before drying is measured. Can also be done.

  The result measured by the film thickness measuring device 21 can be used for adjusting the driving time of the second pump 17 described above. In the coating apparatus 10 of this embodiment, the drive time adjustment apparatus 22 which adjusts the drive time of the 2nd pump 17 based on the measurement result of the film thickness measurement apparatus 21 is further provided. The drive time adjustment device 22 adjusts the drive conditions such as the drive time and flow rate of the second pump 17 during the coating stop period from the thickness variation information from the film thickness measuring device 21, thereby further improving the coating quality. The life of pumps and filters can be extended. For example, when the time until the film thickness stabilizes is longer than expected, adjustment is performed to increase the driving time or to increase the circulating flow rate. On the other hand, when the time until the film thickness stabilizes is shorter than expected, adjustment is performed so that the driving time is shortened or the circulating flow rate is decreased. By adjusting the driving time to be shortened or the flow rate to be circulated to be reduced, the life of the pump (second pump 17) can be extended, or the replacement time of the filter 15 can be extended.

  In the present embodiment, the second flow path 16 is connected to the first flow path 13 via the tank 11, but the present invention is not limited to this. As shown in FIG. 2, the second flow path 16 may be connected to the first flow path 13 between the tank 11 and the filter 15. In this case, the coating liquid during the coating stop period circulates through a path connected by the first flow path 13 including the filter 15 and the second flow path 16 including the second pump 17.

  Next, examples of the present invention will be described together with comparative examples. The present invention is not limited or restricted by the following examples and comparative examples.

[Example]
As coating liquid, ceramic particles (barium titanate), organic solvent (ethanol), organic binder (polyvinyl butyral), plasticizer (phthalate ester) and dispersant (polymer having polyoxyalkylene group and acid anhydride group) ) Was used. Specifically, barium titanate, polyvinyl butyral, dioctyl phthalate, and ethanol were introduced into a ball mill together with a zirconia cobblestone having a diameter of 1 mm, and wet mixing was performed for 24 hours to prepare a ceramic slurry.

  The ceramic slurry produced above was applied with the apparatus shown in FIG. 1 to form a slurry layer 20 on the support film 19 and dried to form a ceramic green sheet. In this example, polyethylene terephthalate (thickness 30 μm) was used as the support film 19. Here, the coating conditions of the ceramic slurry were set so that the coating speed was 150 m / min and the thickness after drying was 2.3 μm.

  Next, the driving of the second pump 17 was started simultaneously with the stop of the coating, and the circulation path of the coating liquid was switched to the second flow path 16. The coating was resumed 60 minutes later.

[Comparative example]
During the coating stop period, the ceramic slurry was applied in the same manner as in the example except that the second pump 17 was not driven.

[Evaluation]
The results of measuring the film thickness after resuming coating are shown in FIG. FIG. 3 is a graph showing the results of measuring the relationship between the coating distance and the coating film thickness from the point of time when the coating was resumed after the coating stop period. FIG. 3A is a graph when the coating apparatus according to the present invention is used (Example), and FIG. 3B is a case where the coating liquid is not circulated during the coating stop period (Comparative Example). It is a graph of. In the figure, the horizontal axis indicates the coating distance starting from the point of time when the coating is resumed, and the vertical axis indicates the coating film thickness at each coating distance.

  In the comparative example in which the coating liquid was not circulated during the coating stop period, a coating start loss with a length of nearly 700 m occurred until the coating film thickness was stabilized after the resumption of coating. On the other hand, in the Example which performed the circulation of the coating liquid in the coating stop period, it turns out that the coating film thickness is stabilized immediately after the restart of coating, and the coating start loss is small. As described above, according to the present invention, it is considered that the filtration characteristics of the filter, and thus the specific gravity of the coating liquid supplied to the head, are stabilized immediately after resuming the coating, and the deterioration of the coating quality can be suppressed.

DESCRIPTION OF SYMBOLS 10 ... Coating apparatus 11 ... Tank 12 ... Head 13 ... 1st flow path 14 ... 1st pump 15 ... Filter 16 ... 2nd flow path 17 ... 2nd pump 18 ... Drying device 19 ... Object (support film)
DESCRIPTION OF SYMBOLS 20 ... Coating liquid 20a ... Wet coating film 20b ... Dry coating film 21 ... Film thickness measuring apparatus 22 ... Drive time adjustment apparatus

Claims (5)

A first flow path connecting between a tank for storing a coating liquid and a head for coating the object with the coating liquid to form a coating film;
A first pump that is provided in the first flow path and supplies the coating liquid from the tank to the head during a coating execution period;
A filter provided on the first flow path and upstream of the first pump for filtering the coating liquid;
A second flow path branched from the first flow path between the filter and the first pump and connected to the first flow path on the upstream side of the filter; and provided in the second flow path, A coating apparatus comprising a second pump that circulates the coating liquid through at least the filter and the second flow path during a stop period.   The coating apparatus according to claim 1, wherein the first pump and the second pump are alternatively driven.   The coating apparatus according to claim 1, wherein the second pump is driven at least in a continuous period from a time prior to the end of the coating stop period to an end of the coating stop period. A film thickness measuring device for measuring a film thickness of the coating film applied to the object, and a driving time adjusting device for adjusting a driving time of the second pump based on a measurement result of the film thickness measuring device The coating apparatus in any one of Claims 1 thru | or 3 provided. The coating apparatus according to claim 1, wherein the second flow path is connected to the first flow path via the tank.

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