JP2011011192A - Coating method and coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method for reducing ununiformity of coating by separation of a coating liquid and defect by mixing of a foreign matter and forming a coating film of high quality on a substrate even with a simple constitution being excellent in practical use, and a coating apparatus.SOLUTION: By covering a liquid reservoir part 8 stored with a coating liquid 15, moisture absorption and volatilization of the coating liquid are suppressed and ununiformity of coating caused by these is sufficiently reduced. Further, by covering the liquid reservoir part, the foreign matter is prevented from being mixed into the coating liquid.

Description

  INDUSTRIAL APPLICABILITY The present invention is a coating method for applying and casting a liquid material (hereinafter referred to as “coating liquid”) such as an adhesive or an adhesive on a sheet-like substrate such as resin, paper, and metal foil, and the coating method. The present invention relates to a coating apparatus.

  In general, a roll coater is widely used as a coating apparatus for applying a coating solution to the surface of a sheet-like substrate. The roll diameter, number, and transfer method are appropriately selected according to the coating thickness and coating accuracy of the target product, the properties and thickness of the base material, the viscosity of the coating liquid, and the like.

  There are various methods for supplying the coating liquid, such as a direct charging method and a circulation method. In recent years, a die coating method using a die and a roll has been adopted using the T-die technology of extrusion film formation.

  FIG. 9 is a perspective view schematically showing a configuration of a conventional roll coater. The coating apparatus 50 shown in the figure includes a comma coater 51 and a back roll 52 that are arranged to face each other, and a liquid reservoir 58 that stores the coating liquid 15. The liquid reservoir 58 includes a bottom plate 53 and a pair of side plates 54 and 55. The bottom plate 53 is inclined so that the back roll 52 side is lowered, and the coating liquid is supplied to the base material 30 on the back roll 52. The pair of side plates 54 and 55 are provided such that their positions can be adjusted with respect to the bottom plate 53, and the width of the coating film 15A can be adjusted by changing the fixing position.

  As shown in FIG. 9, in the conventional apparatus, the upper part of the liquid reservoir that stores the coating liquid is opened. For this reason, there existed a problem that the malfunction resulting from moisture absorption or volatilization of the solvent contained in a coating liquid occurred easily. That is, when the solvent of the coating liquid absorbs moisture or volatilizes, separation of the solvent component occurs, and when the separated solvent component is supplied to the substrate, there is a problem that unevenness occurs in the coating film.

  As a method for suppressing the evaporation of the coating liquid, for example, Patent Document 1 describes a method of disposing a flow path regulating block in a liquid reservoir of a comma coater.

JP 05-146733 A

  However, the method employing the flow path restriction block as described above requires a step of cleaning the block at a predetermined frequency. In addition, since the shape of the liquid reservoir changes depending on the fixing position of the side plate and the configuration (shape, thickness, etc.) of the side plate to be used, it is necessary to prepare many blocks in advance. There was room for improvement. In addition, a thing with a structure suitable for coating conditions (viscosity of a coating liquid, coating-film thickness) is selected suitably, and a side plate is used.

  The present invention has been made in view of the above problems, and while having a simple configuration excellent in practicality, it is possible to sufficiently reduce coating unevenness due to separation of coating liquids and defects due to contamination of foreign matter, and high quality coating. An object is to provide a coating method and a coating apparatus which are extremely useful for forming a film on a substrate.

  The present invention is a coating method using a coating apparatus having a liquid reservoir that contains a coating liquid, and applying the coating liquid onto the surface of a substrate, which covers the liquid reservoir. In this state, a coating method is provided in which a coating liquid is accommodated in the liquid reservoir.

  Further, the present invention is a coating apparatus that includes a liquid reservoir portion in which the coating liquid is accommodated, and applies the coating liquid onto the surface of the substrate, the liquid reservoir portion being covered. A coating apparatus is provided.

  According to the coating method and the coating apparatus, by covering the liquid reservoir, moisture absorption and volatilization of the coating liquid can be sufficiently suppressed, and coating unevenness caused by these can be sufficiently reduced. Moreover, it can also prevent effectively that a foreign material (Solid, liquid, gas which has a bad influence on a coating liquid) mixes in a coating liquid by covering a liquid reservoir part.

  In the present invention, it is preferable to provide a sheet so as to cover the opening of the liquid reservoir. By adopting such a configuration, the space in the liquid reservoir can be sufficiently sealed, and moisture absorption and volatilization of the coating liquid stored in the liquid reservoir can be further suppressed.

  The sheet covering the opening of the liquid reservoir is preferably adhesive or sticky. By using such a sheet, when the opening of the liquid reservoir is covered, the liquid reservoir can be sealed to a higher degree without using an adhesive tape or the like, and can be re-applied. There are advantages.

  Furthermore, it is preferable that the sheet has transparency. In order to perform continuous coating while maintaining the coating thickness sufficiently uniform, the liquid surface height of the coating liquid contained in the liquid reservoir is kept as constant as possible, and the liquid acting on the roll interval. It is required to suppress pressure fluctuations. By adopting a transparent sheet, the state of the liquid reservoir can be monitored visually or with a normal camera, and the amount of coating liquid to be supplied to the liquid reservoir while checking the liquid level position of the coating liquid Can be adjusted.

  ADVANTAGE OF THE INVENTION According to this invention, although it is a simple structure excellent in practicality, the coating nonuniformity by isolation | separation of a coating liquid and the defect by foreign material mixing can fully be reduced, and a high quality coating film can be formed on a base material.

It is a perspective view which shows the structure of the liquid storage part of the coating device which concerns on this invention. It is sectional drawing in the II-II line of the liquid storage part shown in FIG. It is a top view which shows typically the liquid storage part of the coating device which concerns on this invention. It is a figure which shows typically the structure of the apparatus which supplies a coating liquid to a liquid storage part. It is a side view which shows the structure of a side plate. It is sectional drawing of the side plate shown in FIG. It is sectional drawing which shows the mode inside the liquid reservoir part during the driving | operation of the coating apparatus shown in FIG. It is a top view which shows typically the nonuniformity which arose in the coating film formed with the coating apparatus. It is a perspective view which shows the structure of the liquid storage part of the conventional coating apparatus.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

<Coating device>
The coating apparatus 10 shown in FIGS. 1 to 3 is generally referred to as a “comma coater” and is used to continuously form a coating film by applying a coating liquid on the surface of a sheet-like substrate. It is. The coating apparatus 10 includes a comma coater 1 and a back roll 2 that are arranged to face each other, a bottom plate 3, a pair of side plates 4 and 5, a liquid reservoir 8 that stores a coating liquid 15, and a liquid reservoir 8 above And a sheet 9 provided so as to cover the opening. The sheet-like base material 30 transferred by the back roll 2 passes through the roll interval between the comma coater 1 and the back roll 2, so that the coating film 15 </ b> A is formed on the base material 30. The comma coater 1 is for regulating the thickness of the coating film 15A, and the side plates 4 and 5 are for regulating the width of the coating film 15A.

  As shown in FIGS. 1 and 2, the liquid reservoir 8 includes a bottom plate 3 that is inclined so as to be lowered toward the back roll 2, and a pair of side plates 4 and 5. A tip of a coating liquid supply pipe 16 is provided in the liquid reservoir 8 so that the coating liquid 15 is supplied from a coating liquid storage tank 17 (see FIG. 4).

  The pair of side plates 4 and 5 fixed to the bottom plate 3 are detachably attached to the bottom plate 3 and are movably provided in the width direction of the coating film 15A. The width of the coating film 15A can be adjusted by changing the fixing positions of the side plates 4 and 5. As shown in FIG. 5, the side plate 4 has arc-shaped end surfaces that come into contact with the comma coater 1 and the back roll 2, and is fixed to the support 13 by screws 14.

  As shown in FIG. 6, the side plate 4 has a three-layer structure, and includes a foam material 4a and two PTFE (polytetrafluoroethylene) plates 4b and 4c arranged so as to sandwich the foam material 4a. The foamed material 4a has the same shape as the PTFE plates 4b and 4c, but is provided so that the foamed material 4a protrudes from the end face, and is in contact with the comma coater 1 and the back roll 2. In addition, as long as the foam material 4a can be clamped, a material other than PTFE may be used as the plates 4b and 4c. The other side plate 5 has the same configuration as the side plate 4.

  As described above, the width of the coating film 15A can be changed by changing the positions of the side plates 4 and 5. Furthermore, when changing conditions other than the width of the coating film 15A, the side plate itself may be exchanged for another configuration. Specifically, when changing conditions such as the viscosity, non-volatile content, and coating thickness of the coating liquid 15, a side plate having a shape and size suitable for each condition is selected.

  The sheet 9 covers the opening of the liquid reservoir 8 as shown in FIG. Thereby, the airtightness of the liquid reservoir 8 is enhanced, and it is possible to suppress the entry of foreign substances from the outside and the moisture absorption and volatilization of the solvent in the coating liquid to be stored. When a sheet-like and flexible cover is used as the cover for the opening of the liquid reservoir 8, the position of the side plates 4 and 5 is changed due to changes in coating conditions, etc., and the side plate has other shapes and dimensions. There is an advantage that it is possible to respond flexibly to the exchange of the. In addition to this, it is possible to flexibly cope with a complicated configuration around the opening of the liquid reservoir 8. For example, even if the coating liquid supply pipe 16 passes through the liquid reservoir 8, the portion can be sufficiently sealed by arranging the sheet 9 so as to surround it (see FIG. 1).

  From the viewpoint of achieving both high sealing performance of the liquid reservoir 8 and excellent workability, it is preferable to use a sheet 9 having adhesiveness or adhesiveness. That is, since the sheet 9 has adhesiveness or adhesiveness, the gap between the sheet 9 and peripheral components can be sufficiently reduced, and the liquid reservoir 8 can be sealed to a higher degree. Further, since the sheet 9 can be attached again, it is very easy to rearrange the sheet 9 in accordance with the change of the coating conditions, and the work efficiency is improved. In addition, as long as the sheet | seat 9 has adhesiveness or adhesiveness at least one surface, the said effect can be acquired by arrange | positioning this surface toward the liquid reservoir part 8 side.

  The sheet 9 preferably has transparency. By using the sheet 9 having transparency, the inside of the liquid reservoir 8 can be monitored visually or with a normal camera, and the liquid level position of the coating liquid 15 can be confirmed. By keeping the liquid surface position constant, it is possible to sufficiently suppress the variation in the coating thickness due to the variation, and to form a coating with high thickness uniformity. In addition to this, it is possible to prevent the occurrence of unevenness caused by the decrease in the liquid level.

  As shown in FIG. 7, convection of the coating liquid 15 occurs in the liquid reservoir 8 due to the rotation of the back roll 2 in the direction of arrow A and the inflow of liquid from the coating liquid supply pipe 16. When the coating operation is continuously performed, a phenomenon in which the solvent whose solubility has been reduced by moisture absorption may be separated from the coating liquid. This solvent component tends to stay near the liquid surface (see arrow B in FIG. 7). ). When the liquid level of the coating liquid 15 decreases, the solvent component passes below the comma coater 1 and is applied onto the substrate 30 together with the normal coating liquid. Due to such a phenomenon, the coating thickness varies over a relatively wide area and has a thin transparent appearance, and defects such as mottled patterns, straight lines, and wavy patterns are formed on the film. Such defects appearing on the film are called unevenness. By monitoring the liquid level, the above situation can be prevented in advance.

  When the coating solution is applied onto the substrate 30, the above unevenness is generally recognized at the start and end of the coated film and is small in other areas. This is thought to be because the liquid level of the coating liquid in the liquid reservoir tends to fluctuate at the start of coating. On the other hand, before the end of coating, it is separated by moisture absorption of the coating liquid, or the coating liquid remains less. This is probably because the liquid level is lowered.

  Preferred materials for the sheet 9 include polymer sheets such as polyester, polyethylene, polyvinylidene chloride, and PTFE (polytetrafluoroethylene). In the case where adhesion and transparency are not necessarily required, a metal sheet such as stainless steel, copper, or aluminum may be used as the sheet 9.

<Coating method>
A method for forming the coating film 15 </ b> A on the surface of the substrate 30 using the coating apparatus 10 will be described. As shown in FIG. 1, a coating liquid 15 is accommodated in a liquid reservoir 8 whose opening is covered with a sheet 9, and a film such as a die bonding film is formed by applying the coating liquid 15 onto a substrate 30. To manufacture.

  The coating liquid 15 can be obtained by mixing a resin, a solvent, a filler, and the like. What is necessary is just to set the mixture ratio of these materials suitably according to the use of the film to manufacture, coating conditions, etc. For example, the viscosity of the coating liquid 15 can be adjusted by adjusting the mixing ratio of the solvent and the resin.

  What is necessary is just to select suitably resin to make it contain in the coating liquid 15 according to the use of the film to manufacture. For example, in the case of producing a die bonding film by coating, as a resin, a resin having a film forming property such as acrylic resin, polyimide resin, phenoxy resin; epoxy resin, bismaleimide resin, triazine resin, phenol resin, etc. Can be used.

  Specific examples of the solvent include nonpolar solvents such as hexane, toluene and ethyl acetate; polar solvents such as methyl ethyl ketone, ethanol and N-methyl-2-pyrrolidone. Here, the nonpolar solvent means a solvent having a dielectric constant of less than 10, and the polar solvent means a solvent having a dielectric constant of 10 or more. Polar solvents are further classified into low polar solvents such as methyl ethyl ketone (dielectric constant of 10 or more and less than 20) and high polar solvents such as ethanol and N-methyl-2-pyrrolidone (dielectric constant of 20 or more). Comparing the hygroscopic properties of the polar solvent and the nonpolar solvent, the polar solvent has a property of absorbing moisture more easily than the nonpolar solvent.

  As the filler, fine particles made of an inorganic material or an organic material can be used, and can be appropriately selected according to the application of the coating film 15A, coating conditions, and the like.

  The substrate 30 may be a sheet having a thickness of about 50 to 70 μm, and the material may be appropriately selected according to the use of the film to be manufactured, and a resin or metal one can be used. While setting the base material 30 so that the base material 30 is sequentially sent between the comma coater 1 and the back roll 2 while passing through the liquid reservoir 8, the interval between the base material 30 and the comma coater 1 is adjusted, The coating film 15A is set to have a desired thickness.

  The coating liquid 15 in the tank 17 is supplied to the liquid reservoir 8 through the coating liquid supply pipe 16 (see FIG. 4). As shown in FIG. 4, a nitrogen supply pipe 19 is connected to the tank 17, and the amount of the coating liquid 15 supplied to the liquid reservoir 8 can be controlled by adjusting the internal pressure. . A pressure gauge 20 and a pressure reducing valve 21 are disposed in the middle of the nitrogen supply pipe 19.

  Prior to coating, as shown in FIG. 1, the opening of the liquid reservoir 8 is covered with an adhesive or adhesive sheet 9, and the gas phase portion of the liquid reservoir 8 is sealed. That is, the sheet 9 is arranged so as to cover the curved surface 1a of the comma coater 1 forming the opening of the liquid reservoir 8, the upper end of the bottom plate 3, and the openings formed by the side plates 4 and 5, and the coating liquid supply pipe The sheet 9 is pasted along the outer periphery of 16 so that a gap is not formed as much as possible. In addition, when using what does not have adhesiveness etc. as the sheet | seat 9, you may adhere the sheet | seat 9 on the upper part of the liquid storage part 8 using an adhesive tape.

  After completion of the preparation as described above, the coating film 15 </ b> A is formed on the substrate 30 by transferring the substrate 30 so as to pass through the coating solution 15 accommodated in the liquid reservoir 8. The coating is preferably performed in an atmosphere of room temperature (15 to 30 ° C.) and humidity of 40 to 70%, and more preferably in an atmosphere of temperature 17 to 27 ° C. and humidity 45 to 65%.

  According to the coating apparatus 10 and the coating method using the same according to the above-described embodiment, by covering the opening of the liquid reservoir 8 with the sheet 9, coating unevenness due to separation of the coating liquid 15 and defects due to foreign matter contamination Can be sufficiently reduced, and a high-quality coating film 15 </ b> A can be formed on the substrate 30.

  Further, by using a sheet 9 having transparency and monitoring the liquid surface position of the coating liquid 15 in the liquid reservoir 8, even if separation occurs in the coating liquid 15 or foreign matter is mixed, It is possible to sufficiently suppress the coating film defect caused by. The reason is as described above (see FIG. 7).

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment. For example, in the said embodiment, although illustrated about the case where the opening part of the liquid storage part 8 of the coating device 10 generally called a comma coater was covered, it is not limited to this, A reverse roll coater, a kiss coater, etc. You may apply with respect to a liquid storage part.

  Moreover, in the said embodiment, since there exist various advantages, although the sheet | seat 9 was illustrated as a member which covers the opening part of the liquid storage part 8, it is not limited to this. Depending on the shape of the liquid reservoir, a plate-like member may be employed.

  A comma coater having the same configuration as that of the coating apparatus shown in FIG. 1 was prepared, and coating was performed in a state where the opening of the liquid reservoir was covered with a sheet and coating in a state where it was not covered. The coating solution was prepared by dissolving a resin in N-methyl-2-pyrrolidone and dispersing an inorganic filler therein. A metal protective film (trade name: SPV-M-6020 or SPV-M-6030, manufactured by Nitto Denko Corporation) was used as a sheet covering the liquid reservoir.

(Examples 1 and 2)
In order to obtain a coating film having a coating width shown in Table 1, a pair of side plates was fixed at a predetermined position of the coating apparatus. Thereafter, the opening of the liquid reservoir was covered with a sheet, and the coating liquid was applied onto a 2000 m long substrate. After the coating was completed, another substrate was set on the coating apparatus, and coating was performed again. Such operations were repeated, and coating was performed 15 times for each coating width.
(Comparative Examples 1 and 2)
Coating was performed 15 times in the same manner as in Examples 1 and 2 except that the opening of the liquid reservoir was not covered with a sheet.

<Evaluation of unevenness>
The unevenness of the coating film formed by the said Example and the comparative example was determined using the automatic overview inspection machine which combined the CCD camera and the image processing apparatus. Here, “unevenness” means a portion where portions with different coating thickness are scattered in a non-linear manner. Of the coating film formed over a length of 1000 to 2000 m, the length of the portion including unevenness was measured. The “part including unevenness” means a region where the unevenness 100 exists like the part X shown in FIG. 8, and the “length of the part including unevenness” is a case where there are a plurality of such parts on one base material. In this case, it means the total of each part including unevenness. For each example and each comparative example, Table 1 shows the length of the portion including unevenness of the coating film (average value of 15 coatings). The “length of the portion including unevenness” in Table 1 is the total length of the portions including the unevenness generated at the start and end.

DESCRIPTION OF SYMBOLS 1 ... Comma coater, 2 ... Back roll, 3 ... Bottom plate, 4, 5 ... Side plate, 8 ... Liquid reservoir, 9 ... Sheet (cover), 10 ... Coating apparatus, 15 ... Coating liquid, 15A ... Coating film, 16 ... coating liquid supply pipe, 30 ... sheet-like substrate, 100 ... unevenness.

Claims (8)

A coating method using a coating apparatus having a liquid reservoir in which a coating liquid is stored, and applying the coating liquid on the surface of a substrate,
The coating method, wherein the coating liquid is contained in the liquid reservoir in a state of covering the liquid reservoir.   The coating method according to claim 1, wherein a sheet is provided so as to cover the opening of the liquid reservoir.   The said sheet | seat has adhesiveness or adhesiveness, The coating method of Claim 2 characterized by the above-mentioned.   The coating method according to claim 2, wherein the sheet has transparency. A coating apparatus that includes a liquid reservoir that contains a coating liquid, and that applies the coating liquid onto the surface of a substrate,
The coating apparatus, wherein the liquid reservoir is covered.   The coating apparatus according to claim 5, wherein a sheet is provided so as to cover the opening of the liquid reservoir.   The said sheet | seat has adhesiveness or adhesiveness, The coating apparatus of Claim 6 characterized by the above-mentioned.   The coating apparatus according to claim 6 or 7, wherein the sheet has transparency.