JP5581589B2 - Coating head cleaning method, paste coating method, and plasma display manufacturing method - Google Patents

Description

  The present invention relates to a coating head cleaning method for removing coating liquid and coating paste adhering to the vicinity of a discharge port of a coating head by pressing an adhesive tape against the coating head.

  In recent years, DC type and AC type plasma displays have been developed and are already on the market, forming a large market. In the plasma display, a structure having various functions such as pixel partitioning is formed. For example, an AC type plasma display generates a plasma discharge between an anode and a cathode electrode facing each other in a discharge space provided between a front substrate and a rear substrate, and a Xe-Ne mixed gas sealed in the discharge space. The display is performed by irradiating a phosphor provided in the discharge space with ultraviolet rays having a very short wavelength such as 147 nm and 172 nm generated from a discharge gas such as the above.

  The structure is provided in order to suppress the spread of the discharge to a certain area and to perform display in a prescribed cell, and to ensure a uniform discharge space, and is called a partition (also referred to as a barrier or rib). ing. The shape of the partition generally includes a stripe shape or a lattice shape having a width of 20 to 120 μm and a height of 50 to 250 μm. The phosphor is applied as a phosphor paste containing phosphor powder, an organic binder, and an organic solvent as main components between predetermined barrier ribs, and dried and fired as necessary to form a phosphor layer. As a method for applying the phosphor paste between predetermined barrier ribs, there are a screen printing method and a dispenser method (sometimes called a nozzle method), and a dispenser method with little material loss is attracting attention.

  A schematic diagram showing a phosphor paste coating method by the dispenser method is shown in FIG. The dispenser method has a space (manifold) for storing the phosphor paste 2 in the coating head 1 and moves relative to the substrate 3 while applying pressure through a pressure pipe 4 connected to the space. This is a coating method in which the phosphor paste 2 is ejected into the partition walls from the ejection port 5 by introducing controlled compressed air. Since intermittent coating is performed for each substrate, it is important that the discharge of the paste from the coating head is stable with good reproducibility at the start of each coating.

  The application of the phosphor paste by this dispenser method is a leaf-by-leaf application, and after the application to one substrate, the discharge of the phosphor paste 2 from the discharge port 5 is stopped. Residual paste tends to adhere to the exit surface 6 (the surface including the discharge port of the coating head). If residual paste or foreign matter adheres to the discharge port surface 6 in the vicinity of the discharge port 5 before the next application, or if the discharge port surface 6 in the vicinity of the discharge port 5 has damage such as a scratch or a dent, There is a problem that the coating tends to become unstable, such as variations in the discharge amount and disordered paste discharge behavior. As a result, the coating quality is greatly impaired, and a large number of defective products are generated.

For this reason, it is important that the discharge port surface 6 including the discharge port 5 be sufficiently clean before coating. That is, it is essential to clean the coating head before coating. As a method for cleaning such an application head, conventionally, a method is known in which a wiping member is slid while pressing against a discharge port surface to wipe off residual paste and foreign matter (see Patent Document 1). As shown in FIG. 4, the wiping member 9 made of a woven or knitted fabric is pressed against the discharge port surface 6 by the pressing member 10 and is slid in a predetermined direction 11 while being attached to the discharge port 5 and the discharge port surface 6 by friction. This is a method of wiping off the remaining paste 8. In particular, for the purpose of improving the wiping effect, there is known a wiping method in which, for example, a woven or knitted fabric of ultra-fine fibers is wetted with a clean solvent such as acetone.
However, this method has a problem that the cost of the woven or knitted fabric of ultra-fine fibers having a high wiping effect is high, and the inorganic powder such as phosphor powder contained in the phosphor paste wiped by the wiping member is discharged from the discharge port. By sliding in contact with the surface, there is a problem that an abrasion 12 as shown in FIG. 5 occurs on the surface of the coating head. When such a scratch occurs in the coating head, the discharge behavior of the coating liquid at the start of coating tends to become unstable, and the coating quality is greatly impaired, so that it cannot be used and must be replaced with a coating head having no scratch. .

  In addition, the dispensing head 1 of the dispenser method generally has about 1000 to 4000 fine discharge ports 5 with a diameter of about 50 to 200 μm and is processed with high accuracy, and is very expensive. Such replacement of the coating head due to generation is not preferable because it significantly increases the manufacturing cost of the plasma display panel.

  On the other hand, not a method of wiping using a woven or knitted fabric, but a method of using a scraper to scrape and clean the phosphor paste adhering to the discharge port surface in the vicinity of the discharge port (see Patent Document 2). However, scraping with a scraper is complicated to adjust, and dust generation due to wear of the scraper tends to be a problem. Moreover, since inorganic powder such as phosphor powder contained in the phosphor paste scraped by the scraper may cause scratches on the discharge port surface near the discharge port of the coating head, it is also not preferable.

  In addition, in order to solve the problem of damage to the discharge port due to scraping, a small amount of low-viscosity and low-concentration coating liquid is discharged onto the discharge port surface of the inkjet nozzle, so that the scraper wears and discharges due to the lubricating action of the coating liquid. A technique for preventing damage to the exit surface is known (see Patent Document 3). However, in the case of a high-viscosity paste containing solid fine particles at a high concentration, such as a phosphor paste, the lubricating action of the coating liquid is not sufficient, and the wear of the scraper and the scratches on the discharge port surface are worsened.

  On the other hand, in order to prevent the discharge port surface from being scratched by such sliding, a cleaning material made of a porous adsorbent is pressed on the discharge port surface of the inkjet nozzle substantially vertically with a pressing member such as rubber, and then separated. The technique to do is known (refer patent document 4). However, in the case of a high-viscosity paste containing a high concentration of solid fine particles such as a phosphor paste, sufficient absorption and transfer do not occur just by pressing a porous adsorbent, resulting in poor cleaning.

  Furthermore, the adhesive tape with solvent absorption ability is brought into contact with the discharge port surface of the coating head to which the phosphor paste is adhered, and the residual paste is solidified by absorbing the solvent component from the residual paste. A technique for peeling and transferring from the surface of a material to be cleaned is known (see Patent Document 5).

  Therefore, such a pressure-sensitive adhesive tape is mounted on a coating head cleaning device similar to the device described in Patent Document 4, and is actually applied by a phosphor coating device similar to the device described in Patent Document 1, resulting in a phosphor paste. Could not be completely removed, and the coating quality was significantly impaired. Even if the pressing time of the adhesive tape was extended or the number of times of pressing was repeated a plurality of times, not only the removal failure could not be completely eliminated, but also worsened in some cases. Detailed analysis of the phenomenon revealed the following.

FIG. 6 is a schematic diagram showing an adhesion state of residual paste in the vicinity of the discharge port in the cleaning method in which the pressing operation is performed only once. First, after cleaning the vicinity of the discharge port as shown in FIG. 6A using a conventional coating head cleaning device similar to the device described in Patent Document 1, the phosphor paste is normally applied to the substrate on which the barrier ribs are formed. Applied. When the coating head discharge port surface 6 after application was observed, as shown in FIG. 6B, the residual pastes 8a to 8c adhered as a coating liquid pool irregularly varying in shape and amount. When applied several times, the adhesion state of the residual paste was different each time.
Next, the pressure-sensitive adhesive tape is pressed against the discharge port surface with a flat rubber pressing member similar to the apparatus described in Patent Document 4 against the nozzle discharge port surface 6 to which the irregularly dispersed coating liquid reservoir has adhered. After the transfer, when the cleaned nozzle discharge port surface was observed, the following situation shown in FIG. 6C was confirmed.

  In a portion where a small amount of the residual paste 8a is adhered, the paste solidified by the solvent being absorbed by the adhesive tape while the adhesive tape is being pressed adheres thinly and firmly to the discharge surface in the vicinity of the discharge port, and the fixed state is attached. The kimono 13a remained. On the other hand, in the portion where a large amount of residual paste 8b was adhered, solidification due to solvent absorption during pressing of the adhesive tape could not be sufficiently performed, and the liquid paste remained thin, and the wet deposit 13b remained. That is, it has been found that two types of transfer defects with different states occur. In the portion where the intermediate amount of the residual paste 8c adhered, no transfer failure occurred, and the transfer was a good portion 13c.

  When the adhesive tape was pressed again to further remove the wet deposit, the wet deposit could be removed. It adhered more and more firmly to the exit surface, and it could not be removed even after trying to remove it using an adhesive tape.

  Therefore, as a result of examining the relationship between the amount of residual paste and the optimum holding time for removing the amount of residual paste, it was found that there is a positive correlation between the two. That is, when the residual paste amount is small, a short pressing and holding time is suitable, and when the residual paste amount is large, a long pressing and holding time is suitable. For this reason, if the pressing and holding time is shortened according to the portion where the small amount of residual paste is adhered, the transfer failure of the portion where the small amount of residual paste is adhered is improved, but conversely, the medium amount of residual paste is A wet deposit remains in a portion where a large amount of paste has adhered, or a portion where a large amount of residual paste has adhered, and in particular, a transfer defect has deteriorated in a portion where a large amount of residual paste has adhered. The pressing holding time refers to the time until the adhesive tape is peeled off after coming into contact with the discharge port surface near the discharge port.

  Next, if the pressing time is increased in accordance with the portion where a large amount of residual paste is adhered, the transfer failure of the portion where the large amount of residual paste is adhered will be improved. Adhered matter remained in the adhering portion or a portion where a small amount of residual paste was adhered, and the transfer defect was particularly deteriorated in a portion where a small amount of the residual paste adhered.

As a result of various investigations on cleaning conditions that are effective for both of the above-described two types of transfer defects, the inventors have found that one cleaning condition is applied to the residual paste that remains irregularly on the coating nozzle surface. It was concluded that it was not possible to remove all of the residual paste adhering to the above irregularities by repeating the process. Therefore, as a result of further investigation, it finally came to invent the present technology.
JP 2002-126599 A JP 2004-014393 A Japanese Patent Laid-Open No. 2006-247756 JP 2004-330027 A JP 2001-353856 A

  The present invention relates to a coating head cleaning method capable of efficiently removing the coating liquid adhering to the ejection port and the ejection port surface of the coating head using an adhesive tape without damaging the coating head, and paste application using the same It is an object to provide a method and a method for manufacturing a plasma display.

  Means for solving the above problem is a coating head cleaning method for cleaning the coating liquid adhering to the discharge port surface near the discharge port of the coating head, and the adhesive tape is substantially perpendicular to the discharge port surface near the discharge port. The contact operation is performed one or more times after being brought close to each other and brought into contact with each other and then pulled away in a substantially vertical direction. Thereafter, a minute discharge operation for discharging a small amount of coating liquid from the discharge port is performed, and the adhesive tape is further discharged to the discharge port near the discharge port. A method of cleaning an application head characterized in that a pressing operation of bringing a surface close to and in contact with a surface in a substantially vertical direction and then pulling it apart in a substantially vertical direction is performed one or more times.

  According to the present invention, even if the nozzle discharge port surface has an irregularly dispersed coating liquid reservoir that could not be removed by conventional cleaning techniques, it can be removed by a single pressing operation using an adhesive tape or repeated operations. The remaining coating liquid that cannot be completely removed can be transferred and removed, and it can be cleaned cleanly and does not slide, so there is no damage.

  According to the present invention, a thin deposit remains in a wet state in a portion where a large amount of residual coating liquid is adhered by one or more pressing operations performed before a micro discharge operation, and a medium amount of residual coating liquid is left. The adhering part can be wiped off cleanly, and in the part where a small amount of residual coating liquid has adhered, a thin adherent remains. A small coating liquid reservoir having a uniform size is formed by the micro discharge operation performed next. Thereafter, the pressing operation is performed once or more, thereby removing the coating liquid reservoir formed by the micro discharge operation. At this time, the thin wet deposits remaining in the pressing operation before the micro discharge operation are removed together with the coating liquid reservoir by the subsequent pressing operation. In addition, since the portion firmly fixed by the pressing operation before the micro-discharge operation is brought into a wet state by contacting the coating liquid reservoir, it is removed by the subsequent pressing operation. The portion that has been removed by the pressing operation before the micro discharge operation is removed by the pressing operation that is performed after that, although the coating liquid reservoir newly adheres.

  According to the present invention, it is possible to cleanly remove the residual paste from the vicinity of the discharge port even on the nozzle discharge port surface to which the residual coating liquid with irregularly dispersed sizes adhered that could not be removed by the conventional adhesive transfer technology. .

  The means for solving the above problem is a coating head cleaning method in which a pressing member made of an elastic body is pressed so as to face the coating head discharge port surface via the adhesive tape in each pressing operation. .

  The coating head cleaning method as described above, wherein the coating liquid is a phosphor paste.

  The coating head is a coating head cleaning method in which the coating head is a phosphor coating nozzle for manufacturing a plasma display.

  Further, the present invention is a paste coating method characterized in that after the coating head is cleaned using the coating head cleaning method, coating is performed by discharging a coating liquid from the coating head.

  Further, the present invention is a method for manufacturing a plasma display, wherein a phosphor layer is formed using the paste application method.

  When the coating head cleaning method of the present invention is used, the residual coating liquid can be surely removed from the coating head discharge port surface even though it is a simple method, and thus a simple coating head cleaning method can be provided at low cost. Further, since the discharge port surface of the coating head is not slid by the cleaning material, there is a desirable effect that the discharge port surface of the coating head is not damaged and the life of the expensive coating head is remarkably extended.

It is the schematic diagram which showed embodiment of the cleaning method of the coating head of this invention. It is the schematic diagram which showed the adhesion state of the residual paste of the discharge port vicinity in the cleaning method of this invention. It is the schematic diagram which showed the fluorescent substance paste coating method by the dispenser method. It is the schematic diagram which showed the cleaning method of the conventional coating head. It is the schematic diagram which showed the state of the abrasion near a discharge outlet. It is the schematic diagram which showed the adhesion state of the residual paste of the discharge opening vicinity in the cleaning method which performs a pressing operation only once.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coating head 2 Phosphor paste 3 Substrate 4 Pressurized piping 5 Discharge port 6 Discharge port surface 7 Discharged paste 8 Residual paste 8a Small amount of residual paste 8b Large amount of residual paste 8c Medium amount of residual paste 9 From woven or knitted fabric Wiping member 10 Pressing member 11 Sliding direction 12 Scratch 13a Adhered substance 13b Adhering substance 13c Wet adhering part 13c Good transfer part 14 Adhesive tape 15 Wrinkle-stretching guide 16 Transferred paste 17 Coating liquid reservoir

  The present invention provides a coating head having a step of removing the coating liquid adhering to the discharge port surface near the discharge port of the coating head by pressing the pressure-sensitive adhesive tape against the coating head and then pulling the pressure-sensitive adhesive tape away from the coating head. It relates to a cleaning method.

  In the present invention, the coating head refers to a member having a discharge port for discharging a coating liquid, which is a member such as a coating nozzle or a base constituting the coating apparatus. The discharge port refers to an opening through which the coating liquid supplied to the coating head is discharged toward the object to be coated. Further, the discharge port surface refers to a surface including the peripheral portion of the discharge port on the outer surface of the coating head, that is, a surface on which the discharge port opens. Further, the vicinity of the discharge port is a region near the outer edge of the discharge port. If the coating liquid remains applied in this region, the coating quality is significantly impaired.

  The discharge port may be singular or plural, and may have any shape such as a slit, a circle, an ellipse, or a polygon, but the coating head applies a phosphor for plasma display described later. In the case of a coating head for a plasma display, a phosphor layer necessary for one screen in a plasma display can be applied at least once for each color by a number more than the number according to the number of pixels in the scanning direction (1000 to 4000). It is preferable that the coating head is provided with circular discharge ports (about 50 to 200 μm in diameter) arranged in the longitudinal direction of the coating head.

  In the present invention, the pressing operation means that the above-mentioned adhesive tape is brought into contact with the discharge port surface in a substantially vertical direction and the coating liquid is solidified by absorbing the solvent in the coating liquid into the adhesive tape while holding for a certain period of time. The coating liquid solidified by peeling off in a substantially vertical direction is transferred from the discharge port surface to an adhesive tape and removed. By contacting the discharge port surface in a substantially vertical direction, holding it without sliding, and separating it in a substantially vertical direction, it is possible to efficiently remove the coating liquid adhering to the discharge port surface without damaging the coating head. it can.

  In the coating head cleaning method of the present invention, it is preferable to use a phosphor coating nozzle for manufacturing a plasma display as the coating head and a phosphor paste as the coating liquid. Hereinafter, although the example of the coating head cleaning method in the case of apply | coating fluorescent substance paste using the fluorescent substance application nozzle for plasma display manufacture is demonstrated, this invention is not limited to this.

FIG. 1 is a schematic view showing an embodiment of a coating head cleaning method of the present invention.
FIG. 1A schematically shows an operation in which the adhesive tape 14 is pressed against the residual paste 8 attached to the discharge port surface 6 of the coating head 1 using the pressing member 10. FIG. 1B is a cross section in a plane perpendicular to the longitudinal direction of FIG. 1A, and the wrinkle-stretching guide 15 prevents wrinkles and sagging on the adhesive tape before and after the pressing member 10. It shows how to do.

  FIGS. 1C and 1D show a state in which the adhesive tape 14 has been peeled from the discharge port surface 6 after a predetermined time from the contact state of FIGS. 1A and 1B, and the residual paste 8 is the adhesive tape. 14 schematically shows a state where the image has been transferred. The pressing conditions controlled in the pressing operation include a pressing pressure, a pressing amount, a pressing holding time, a pressing member elastic modulus, and the most important is a pressing holding time.

  As described above, there is a positive correlation between the residual paste amount and the holding time, and a short pressing time is appropriate when the residual paste amount is small, and a long pressing hold when the residual paste amount is large. Experiments have shown that the time is appropriate.

  In the coating head cleaning method of the present invention, an adhesive tape is first applied to the discharge port surface as shown in FIG. A first pressing operation is performed in which the coating liquid is substantially solidified, and the coating liquid is substantially solidified and then peeled off in a substantially vertical direction. The pressing condition used in the first pressing operation can be appropriately set according to the state of the residual paste. By the first pressing operation, wet thin deposits remain in the areas where a large amount of residual paste is adhered, and the areas where a moderate amount of residual paste is adhered are wiped cleanly and a small amount of residual paste is adhered. In the part, a thin adherent remains. The pressing operation performed before the micro discharge operation described below is preferably performed once, but may be performed twice or more as necessary.

  FIG. 2 is a schematic view showing a state of adhesion of residual paste in the vicinity of the discharge port in the cleaning method of the present invention. FIG. 2A shows the state of adhesion of the residual paste on the discharge port surface before performing a minute discharge operation. Due to one or more pressing operations performed before the minute discharge operation, the transfer good portion 13c from which the residual paste has been removed cleanly, the portion where the adhered matter 13a remains, and the wet matter 13b remain. There is a part that.

  Next, a micro discharge operation for discharging a small amount of coating liquid from the discharge port is performed. FIG. 2B shows the state of adhesion of the residual paste on the discharge port surface after a small amount of discharge operation. A small coating liquid reservoir 17 whose size is accurately and uniformly controlled is formed in the periphery of the discharge port 5 on the discharge port surface 6 by a small amount of discharge operation. Originally, the application head normally has a function of uniformly discharging the paste with high accuracy, so that it is not necessary to provide a special facility for the minute discharge operation, and the setting of the minute discharge operation may be provided. The setting conditions for the small amount of discharge can be appropriately set according to the paste viscosity and the flow resistance at the discharge port. For example, a discharge pressure of 300 to 1000 kPa and a pressurization time of 0.01 to 1 s are preferably used. In the case of a small amount of discharge, it is preferable to form a coating liquid reservoir so as to cover the discharge port. However, the present invention is not limited to this, and it is sufficient that the paste covers the discharge port at least during pressing.

  Subsequently, by the pressing operation performed after the micro discharge operation, the thin wet deposit 13b remaining before the micro discharge operation is removed together with the coating liquid reservoir 17. The adhering deposit 13a remaining before the minute discharge operation becomes wet when it comes into contact with the coating liquid reservoir, and is therefore easily removed by the pressing operation performed after the minute discharge operation. A coating liquid reservoir 17 is newly formed in the transfer-good portion 13c that has been cleanly removed by the pressing operation performed before the micro discharge operation, but the residual paste in the coating liquid reservoir 17 formed by the micro discharge operation. Since the pressing holding time of the pressing operation performed after the micro discharge operation is set according to the amount, it is surely removed.

  As described above, the residual paste can be clearly removed from the vicinity of the discharge port even on the surface of the nozzle discharge port to which the residual paste having irregularly dispersed sizes that could not be removed by the conventional adhesive transfer technique is attached. In addition, although it is preferable that the pressing operation performed after a trace amount discharge operation is one time, you may perform it twice or more as needed.

  By the way, since the adhering matter in the fixed state is removed only by the pressing operation after the micro discharge operation is in the vicinity of the discharge port which becomes wet due to the coating liquid pool formed by the micro discharge operation. There may be a case where a part of the adhered matter at a position away from the outlet remains. However, even in that case, there is no problem because the size of the coating liquid reservoir 17 can be appropriately adjusted so as to sufficiently clean the vicinity of the discharge port so as not to affect the application.

  The size of the coating liquid reservoir may be appropriately set according to the discharge port diameter of the coating head and the distance between the discharge ports, that is, the discharge port pitch. For example, a suitable discharge port diameter of 50 to 200 μm in the case of a PDP phosphor coating nozzle, With respect to the outlet pitch of 100 to 1000 μm, the size of the coating liquid reservoir 17 is preferably 10 μm or more and 1000 μm or less from the outer edge of the discharge port. If it is less than 10 μm, the vicinity of the discharge port is not sufficiently cleaned, causing variations in the discharge amount when discharging is resumed, and the shape of the discharged paste is likely to be disturbed, making the application unstable. If it is larger than 1000 μm, it will be difficult to remove uniformly by a pressing operation performed after a small amount of discharging operation. More preferably, the size of the coating liquid reservoir 17 is not less than 50 μm and not more than 500 μm from the outer edge of the discharge port.

  Further, the variation in the size of the coating liquid reservoir is preferably small, but the variation is preferably 1 μm or more and 100 μm or less. In order to obtain a variation smaller than 1 μm, a very complicated and expensive discharge amount control means is required, which is not preferable. If the variation is larger than 100 μm, it is difficult to remove uniformly by the pressing operation performed after the micro discharge operation.

  Hereinafter, various elements that affect the setting of the pressing condition used in the pressing operation will be described. However, the setting of the pressing condition is not limited to this, and the number of times of pressing may be set as appropriate.

  The pressing and holding time is preferably 0.1 to 10 seconds. If the time is shorter than 0.1 seconds, the paste cannot be solidified sufficiently, and wet transfer failure tends to occur. If it is longer than 10 seconds, the paste is excessively solidified, so that a sticking transfer failure tends to occur. More preferably, it is 0.5 seconds to 5 seconds.

  In order to make the above-mentioned pressing more reliable, it is preferable to press the pressing member in a substantially vertical direction so as to face the coating head discharge port surface from the back side of the pressure-sensitive adhesive tape. It is even more preferable that an elastic body is provided on the contact surface of the member.

  When the pressing member is used, for example, as shown in FIG. 1, the discharge port is configured such that the pressing member 10 is pressed against the discharge port surface 6 of the coating head 1 via the pressure-sensitive adhesive tape 14. The residual paste 8 adhered to the discharge port surface 6 in the vicinity of the discharge port 5 is adhered to the pressure-sensitive adhesive layer by being pressed by moving in a substantially vertical direction with respect to the surface 6, and then the adhesive tape 14 is removed from the discharge port surface 6. The residual paste 8 attached to the discharge port surface 6 can be removed by pulling apart. When the adhesive tape 14 is pulled away from the discharge port surface 6, the pressing member 10 is pulled away so as to be away from the discharge port surface 6 in a substantially vertical direction. If the adhesive tape 14 is pulled away quickly by giving a slightly higher tension, the effect is great.

  A preferable pressing pressure (contact pressure) is 0.01 to 1 MPa. When the contact pressure is less than 0.01 MPa, uniform transfer of the paste becomes insufficient. On the other hand, when the pressure is higher than 1 MPa, a great load is generated on the contact pressure mechanism, which is not preferable, and the coating head is also easily damaged, which is not preferable. 0.05 to 0.3 MPa is more preferable. For example, a pressure sensitive sheet (trade name: Prescale) manufactured by Fuji Photo Film Co., Ltd. is used for measuring the contact pressure. Alternatively, the contact pressure sensor is installed in combination with the pressing member, and the contact pressure measurement result is fed back to the contact pressure operation controller to obtain a uniform contact pressure.

  Such contact pressure can be suitably realized particularly when the amount of pressing of the coating head into the elastic body pressing member is 0 mm to 5 mm. When the pushing amount is less than 0, a state in which no contact pressure is generated easily occurs. If it is larger than 5 mm, the coating head is liable to be damaged, which is not preferable.

  Various materials can be used as the elastic body constituting the pressing member, but rubber is most preferable. Various rubbers can be used, but those that do not suffer damage such as residual strain even after repeated contact and are quick to recover are preferred. Examples of such rubbers include silicone rubber and natural rubber.

  Further, a rubber material that is not easily deteriorated even if a paste adheres is preferable. If such a suitable combination of paste and rubber material cannot be selected, a cover film or the like may be provided on the rubber surface.

  The hardness of the rubber is preferably A20 to A60 degrees (JIS K 6253 (2006)). If it is smaller than A20 degrees, the contact pressure tends to be insufficient, and wet transfer failure tends to occur. On the other hand, if it is larger than A60 degrees, the elasticity is impaired and a uniform contact pressure cannot be obtained, and the coating head is liable to be damaged, which is not preferable. More preferably, it is A30 to A40 degrees.

  If the variation in the hardness of the rubber on the pressing member contact surface is large, a uniform contact pressure cannot be obtained. Therefore, the variation in hardness is preferably small, but 20 degrees or less is preferable. More preferably, it is 10 degrees or less.

  When the discharge holes are provided in a row in the coating head, it is preferable that the straightness of the contact surface of the pressing member is 1 mm or less because uniform contact pressure can be easily obtained. It is still more preferable if it is 0.5 mm or less. Further, the surface roughness of the abutting surface of the pressing member is preferably 0.5 mm or less because a uniform contact pressure is easily obtained. It is still more preferable if it is 0.1 mm or less.

  The rubber thickness is preferably 1 to 30 mm, and more preferably 5 to 15 mm. If it is smaller than 1 mm, the elasticity is impaired and an appropriate contact pressure cannot be obtained. If it is larger than 30 mm, unnecessary materials increase and the apparatus becomes large, which is uneconomical.

  It is preferable that the cross-sectional shape of the abutting surface of the pressing member is a convex shape because particularly important contact pressure of the discharge port portion can be ensured. If it is a flat surface or a concave shape, a portion with insufficient contact pressure tends to occur, which is not preferable. In particular, it is more preferable that the shape of the contact surface is a part of the cylindrical surface. In this case, the contact pressure is started near the discharge ports arranged in a row, and then expands to the periphery of the discharge port, which is preferable because the spread of the paste is made uniform. Further, it is preferable that the shape of the abutting surface is a part of the cylindrical surface, since the processing of the abutting surface becomes easy and as a result, straightness is improved.

  The diameter of the cylindrical surface is preferably 10 to 1000 mm. If it is smaller than 10 mm, the position of the discharge port is liable to deviate from the top of the cylinder, and an appropriate pressure is not applied to the discharge port. If it is larger than 1000 mm, the convex effect is reduced, and a portion with insufficient contact pressure tends to occur, which is not preferable. More preferably, the diameter of the cylindrical surface is 20 to 100 mm. It is more preferable to match the top of the cylinder with the position of the discharge port because the contact pressure tends to be uniform. The deviation between the top of the cylinder and the position of the discharge port is preferably small, but is preferably 5 mm or less, and more preferably 2 mm or less.

  Regarding the operation speed of the pressing operation of the present invention, transfer can be most effectively performed when the contact speed is 1 to 100 mm / s and the peeling speed is 10 to 1000 mm / s.

  In the pressure-sensitive adhesive tape applicable to the present invention, the surface tension of the surface in contact with the paste is preferably larger than that of the paste or the paste solvent. If the surface tension of the adhesive tape is smaller than the paste, the paste cannot be transferred stably.

The pressure-sensitive adhesive tape applicable to the present invention can be appropriately selected and used in order to cope with a wide variety of coating liquid types and adhesion amounts. The pressure-sensitive adhesive tape is preferably composed of a base material and a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is a pressure-sensitive adhesive tape composed of a solvent-absorbing pressure-sensitive adhesive. It is preferable that the pressure-sensitive adhesive can absorb the paste or the paste solvent because the fluidity of the paste is reduced (solidified) and removably transferred. For this purpose, the solubility parameter of the adhesive material is preferably a value close to that of the paste or paste solvent. The solvent absorption capacity of the pressure-sensitive adhesive tape is preferably 10 mL or more, more preferably 20 mL or more per 1 m ^{2 of} area. If the solvent absorption capacity is less than 10 mL per 1 m ² , the solvent absorption residue tends to occur. In addition, the solvent absorption capability of an adhesive tape is the value measured by the amount increased by absorption in 1 minute after being immersed in the solvent which comprises a coating liquid.

The solvent absorption rate of the pressure-sensitive adhesive tape is preferably 1 mL / second or more, more preferably 3 mL / second or more per 1 m ^{2 of} area. If the solvent absorption rate is less than 1 mL / ^second per 1 m ² of area, it takes too much time to absorb the paste solvent, and the tact of the apparatus tends to be longer. The solvent absorption rate of the pressure-sensitive adhesive tape was measured by immersing the tape in the solvent constituting the coating liquid, and repeating the weight increase per unit area per unit time by absorbing the solvent for 5 seconds. Value.

  Furthermore, the adhesive force of the adhesive tape is preferably 0.5 to 4.0 N per 20 mm width, and more preferably 2.0 to 3.0 N. If the adhesive strength per 20 mm width is less than 0.5 N, the solidified product remaining after absorbing the solvent in the paste remaining on the discharge port surface tends to be completely removed, and if it exceeds 4.0 N, it takes time to peel off the tape. The pressure-sensitive adhesive layer tends to peel from the base material of the pressure-sensitive adhesive tape. The adhesive strength of the adhesive tape was measured by bonding it to a PET film having a thickness of 25 μm and peeling it in a 180 ° direction at 23 ° C. and a tensile speed of 300 mm / min by a method according to JIS Z 0237 (2000). Value. It is important to have adhesive strength even after solvent absorption.

  Moreover, it is preferable that it is 0.005-0.3 mm, and, as for the thickness of the adhesive layer of the said adhesive tape, it is more preferable that it is 0.01-0.15 mm. If the thickness of the pressure-sensitive adhesive layer is less than 0.005 mm, there is a tendency that the solvent in the paste cannot be completely absorbed. Tend.

  The pressure-sensitive adhesive tape used in the present invention is preferably one having elasticity and a smooth pressure-sensitive adhesive surface in order to press the coating head without damaging it. As such an adhesive tape, what was equipped with the adhesive layer which consists of foaming adhesives is preferable. The foamed adhesive means an adhesive having bubbles (cells) or fine pores in the adhesive layer, and has elasticity. For example, what is disclosed in JP 2000-169803 A can be used.

  As the main component, an acrylic resin or a rubber resin is used for the adhesive. The acrylic resin is a copolymer having an acrylic ester as a main monomer component, and more specifically, a main monomer having a low glass transition temperature that gives tackiness, and a comonomer for imparting adhesiveness and cohesive force. Furthermore, a functional group-containing monomer for improving crosslinkability and adhesiveness is copolymerized.

  Examples of the main monomer include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate. Examples of the comonomer include vinyl acetate, acrylonitrile, acrylamide, styrene, methyl methacrylate, and methyl acrylate. Examples of functional group-containing monomers include carboxyl group-containing monomers such as methacrylic acid, acrylic acid, and itaconic acid; hydroxyl group-containing monomers such as hydroxyethyl methacrylate and hydroxypropyl methacrylate; amino group-containing monomers such as dimethylaminoethyl methacrylate; acrylamide and methylol. Examples thereof include amide group-containing monomers such as acrylamide; epoxy group-containing monomers such as glycidyl methacrylate; and acid anhydride group-containing monomers such as maleic anhydride.

  Examples of the rubber-based resin include those obtained by adding an elastomer as a main component and adding a tackifier resin, a softening agent, an anti-aging agent, a filler and the like thereto. The elastomer is a polymer having a low glass transition point and a wide rubber-like flat region up to a high temperature. For example, natural rubber; isoprene rubber, styrene / butadiene rubber, styrene / butadiene block copolymer, styrene / isoprene block copolymer. Examples include, but are not limited to, polymers, butyl rubber, polyisobutylene, polyvinyl isobutyl ether, chloroprene rubber, nitrile rubber, and synthetic rubber such as graft rubber or thermoplastic elastomer.

  The tackifier resin, softening agent, anti-aging agent, and filler are not particularly limited, and known and commonly used ones can be used. For example, examples of adhesion imparting resins include rosin resins, terpene resins, petroleum resins (aliphatic petroleum resins, aromatic petroleum resins, hydrogenated petroleum resins), coumarone / indene resins, styrene resins, and the like. It is done. Among these, as the rubber-based resin, those mainly composed of a styrene / isoprene block copolymer or a natural rubber-based elastomer are particularly preferable.

  The apparatus used for the coating head cleaning method of the present invention is one in which the pressure-sensitive adhesive tape is unwound from a roll shape. The unwinding means for intermittently supplying the pressure-sensitive adhesive tape and the cleaned pressure-sensitive adhesive tape are wound in a roll shape. It is preferable to have winding means for taking up, means for controlling the tension of the adhesive tape, means for controlling the feed amount of the adhesive tape, and means for detecting the remaining amount of the tape.

  Although it does not specifically limit as tension | tensile_strength of an adhesive tape, 10-1000 N / m is preferable. If it is less than 10 N / m, the conveyance of the adhesive tape material becomes unstable and wrinkles are likely to occur, or the pressing tends to be uneven. If it is larger than 1000 N / m, the driving equipment for applying high tension becomes large, or the load on the apparatus increases and it becomes fragile, which is not preferable. More preferably, it is 30 to 200 N / m.

  It is also preferable to install various known wrinkle stretching means or a means for preventing charging. In particular, it is preferable that the charge amount is 1000 kV or less because it is easy to prevent discharge and it is easy to prevent the adsorption of dust. More preferably, it is 100 kV or less.

  In addition, when a coating failure occurs, a large amount of paste may adhere to the discharge port surface due to disorder of paste discharge. In such a case, it is necessary to repeat cleaning several times with the pressure-sensitive adhesive tape, and it takes a long time, and when the pressure is pressed with the pressure-sensitive adhesive tape, the paste spreads greatly, and the application head may be unnecessarily soiled. It is preferable in terms of production efficiency to provide a mechanism for wiping and cleaning the discharge port surface with a woven or knitted fabric of ultrafine fibers having a single yarn fineness of 0.1 dtex or less, which has been a conventional technique for the adhesion of such a large amount of paste.

  By using a woven or knitted fabric of ultrafine fibers having a single yarn fineness of 0.1 dtex or less, even when a fine inorganic powder of about several μm is contained in the paste, it can be cleaned without wiping. In this case, it is also preferable to discharge the cleaning solution onto the woven or knitted fabric so that the paste can be easily removed.

  Even when combining conventional techniques in this way, the amount of friction at the time of wiping can be greatly reduced compared to the method of cleaning the application head by only wiping with a woven or knitted fabric, so that damage to the application head can be greatly suppressed. .

The present invention can be suitably applied particularly when the paste viscosity is 10 to 100 Pa · S. If it is less than 10 Pa · S, the paste tends to be dripped from the coating head even when it is not applied, and depending on the amount of adhesion, transfer residue tends to occur, which is not preferable. On the other hand, when the pressure is higher than 100 Pa · S, the discharge pressure tends to be too high and it is difficult to increase the coating speed. More preferably, it is 20-70 Pa * S. The paste viscosity is a value measured using a Brookfield viscometer at a measurement temperature of 25 ° C. and a shear rate of 2.4 s ⁻¹ .

  The coating liquid may be selected according to the coating material such as a phosphor paste, a reflective layer paste, a dielectric paste, and an electrode paste used in plasma display manufacturing. As an example, the phosphor paste contains phosphor powder, a binder, an additive, a solvent, and the like.

  The present invention is even more effective when combined with known charge coating. Charge coating is a coating method in which a charge is applied to either a coating head, a paste, or a substrate, and the paste is drawn to the substrate using electrostatic force. In electrification coating, there is a tendency that the adhesion of the paste to the nozzle ejection surface after the completion of coating tends to be small.

  When the coating head of the present invention is a phosphor coating nozzle for manufacturing a plasma display, it can be more preferably cleaned. When the coating head cleaning method of the present invention is applied to a single-wafer coating method in which coating is started and finished for each surface, the conventional technique uniformly coats the discharge port surface or causes wiping scratches. Even if it is not possible, it is possible to obtain a very uniform and high-quality coated surface because the discharge port surface can be cleaned without scratches and residual paste, which is preferable. In particular, it is preferable to use it for applying a phosphor paste for manufacturing a plasma display because the effect is great.

  Examples in which the present invention is applied to cleaning a phosphor coating head for plasma display will be described below, but the present invention is not limited to such examples.

The phosphor paste used was prepared by the following method. A phosphor paste was prepared by dispersing and mixing in a 16 wt% terpineol / benzyl alcohol (3/1) solution of ethyl cellulose having a weight ratio of 19 and a weight ratio of the inorganic phosphor powder of 19. The phosphor powder used is (Y, Gd) BO ₃ : Eu for red light emission, ZnSiO ₄ : Mn for green light emission, and BaMgAl ₁₀ O ₁₇ : Eu for blue light emission. The cumulative average particle size and the maximum particle size of each color phosphor powder are R phosphor: 2.7 μm, 27 μm, B phosphor: 3.7 μm, 27 μm, G phosphor: 3.6 μm, 25 μm. The respective viscosities are R phosphor: 52 Pa · s, B phosphor: 39 Pa · s, and G phosphor: 40 Pa · s.

  The coating head for coating the phosphor is a coating head having 1920 discharge holes with a hole diameter of 100 μm arranged in the longitudinal direction of the coating head, and a pressure of 200 to 700 kPa is applied to the inside by air to adjust the traveling speed to the substrate to 20 A coating head that fills the phosphor paste between predetermined barrier ribs by discharging the phosphor paste while changing within a range of ˜200 mm / s was used.

The pressure-sensitive adhesive tape used for cleaning the phosphor paste adhered to the discharge port and the discharge port surface of the coating head is as follows.
Adhesive tape: Nitto Denko Corporation: ELEP Cleaner (registered trademark)
Moreover, the fiber woven or knitted fabric is as follows.
Super extra fine fiber knitted fabric: Toray Industries, Inc .: Toraysee (registered trademark)
Acetone was used as a cleaning solvent for wetting the woven or knitted fabric.

  Evaluation was performed as follows. When the residual paste is applied to the edge of the discharge hole as shown in FIG. 6c, normal application tends to be hindered. Accordingly, the surface of the discharge holes is observed after a series of cleaning operations, and the ratio of the number of discharge holes in which a part of the residual paste adheres to the edges of the discharge holes is checked with respect to the total discharge ports. % Or less was marked with ◯, and 1% or less was marked with ◎.

Example 1
The coating head was filled with the phosphor paste prepared as described above, and the phosphor paste was coated between predetermined partitions using the coating head. Thereafter, using a roll of adhesive tape, the discharge head and the coating head with the phosphor paste adhered to the discharge port surface were cleaned by the method shown in FIG. A first pressing operation was performed using a rubber roll (diameter 60 mm, Shore A rubber hardness 30 degrees, rubber thickness 10 mm) installed so as to face the discharge port surface of the coating head as a pressing member. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape is brought into contact with the discharge port and the discharge port surface of the coating head, and is held for 4 seconds while pressing the pressure-sensitive adhesive tape against the coating head at a pressure of 0.2 MPa, and then the pressing member is separated from the discharge port surface. While moving in the direction at 50 mm / s, a tension of 1 kg / m was applied to the adhesive tape to peel off the adhesive surface from the discharge port surface. A thin paste film remained in about 50% of the discharge port.
Prior to the second pressing, a small amount of coating liquid was discharged from the discharge port, and a small amount of discharge operation was performed in which a coating liquid reservoir having a diameter of about 300 μm was adhered in the vicinity of each discharge port.

  Subsequently, the adhesive tape was fed 20 mm, the new adhesive surface was moved to the transfer position, and the second pressing was performed. The pressure-sensitive adhesive tape was again pressed against the coating head at a pressure of 0.2 MPa with the pressing member and held for 2 seconds, and then the pressure-sensitive adhesive tape was moved at a rate of 50 mm / s in a direction away from the discharge port surface, The pressure-sensitive adhesive surface was peeled off from the discharge port surface by applying a tension of m. The discharge port to which the residual paste adhered was reduced to about 0.5%. When the cleaning operation was carried out continuously 2000 times, no scratches were generated.

Example 2
A rubber roll having a diameter of 200 mm was used as the pressing member. The other conditions were the same as in Example 1. The discharge port to which the residual paste adhered was reduced to about 5%. When wiping was performed continuously 2000 times, no wiping scratches were generated.

Example 3
A rubber roll having a Shore A rubber hardness of 60 degrees was used as the pressing member. The other conditions were the same as in Example 1. The discharge port to which the residual paste adhered was reduced to about 8%. When wiping was performed continuously 2000 times, no wiping scratches were generated.

Comparative Example 1
The sliding wiping described in Patent Document 1 was performed using a fiber woven or knitted fabric as the belt-shaped wiping member. The discharge port to which the residual paste adhered was about 0.2%, but when wiping was continuously carried out 2000 times, a strong wiping wound was generated and it became unusable.

Comparative Example 2
Subsequent to pressing for 4 seconds, pressing was performed for 2 seconds without discharging a small amount of coating liquid from the discharge port. The other conditions were the same as in Example 1. The discharge port to which the residual paste adhered reached about 20% and was unusable.

  It is suitable for a method for manufacturing a thin display such as a plasma display or a liquid crystal display.

  The present invention is preferably applied to a high-viscosity paste containing solid particles at a high concentration, but can also be applied to a low-viscosity discharge liquid such as an ink jet.

Claims (6)

A coating head cleaning method for cleaning a coating liquid adhering to a discharge port surface in the vicinity of a discharge port of a coating head, wherein the adhesive tape is brought into contact with a discharge port surface in the vicinity of the discharge port in a substantially vertical direction and then substantially vertical. The pressing operation is performed once or more in the direction of separation, and then a small amount discharging operation is performed to discharge the coating liquid from the discharge port so that the size of the coating liquid reservoir is 10 to 1000 μm from the outer edge of the discharge hole. A coating head cleaning method, wherein a pressing operation of bringing the surface close to and in contact with a discharge port surface in the vicinity of the discharge port and then pulling it away in a substantially vertical direction is performed once or more. The coating head cleaning method according to claim 1, wherein in each pressing operation, a pressing member made of an elastic body is pressed so as to face the coating head discharge port surface through the adhesive tape. The coating head cleaning method according to claim 1, wherein the coating liquid is a phosphor paste. The coating head cleaning method according to claim 1, wherein the coating head is a phosphor coating nozzle for manufacturing a plasma display. A paste coating method, wherein the coating head is cleaned by using the coating head cleaning method according to claim 1, and then coating is performed by discharging a coating liquid from the coating head. A method of manufacturing a plasma display, comprising forming a phosphor layer using the paste coating method according to claim 5.

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