JP5176636B2 - Roll coating method and roll coating apparatus - Google Patents

Description

  The present invention relates to a roll coating method and a roll coating apparatus for coating a coating liquid on a substrate that runs continuously using a roll coating apparatus.

  Conventionally, various coating films are formed on a substrate surface in order to impart performances such as corrosion resistance, workability, aesthetics, and insulation to a continuously running substrate such as a steel plate. As this treatment method, a roll coater is generally used, and a two-roll coater using two rolls or a three-roll coater using three rolls is widely used. In particular, the three-roll coater is a mainstream coating method because it has excellent controllability of the coating film thickness and has a relatively beautiful surface appearance.

  In FIG. 4, an example of a structure of the roll coating device which is a 3 roll coater which does not have the precoater based on a prior art is shown. This three-roll coater includes a pickup roll 4 that draws up the coating liquid 3 from the coater pan 2 filled with the coating liquid, a mitering roll 5 that adjusts the amount of the coating liquid drawn up by the pickup roll 4, and a liquid amount The applicator roll 6 transfers the adjusted coating liquid from the pick-up roll 4 to the steel strip 1.

  The rotation direction of each roll may be a natural rotation that rotates in the same direction at a proximity point or a contact point between the rolls, or a reverse rotation that rotates in the reverse direction. In general, since reverse rotation makes it easier to obtain a coating surface with a uniform film thickness along the surface irregularities of the steel sheet, the substrate surface has irregularities and a uniform film thickness along the surface irregularities. When it is desired to obtain it, the reverse rotation is often performed particularly between the applicator roll and the steel plate. Moreover, the applicator roll is often a rubber roll in which rubber is lined on the steel roll so as not to damage the steel sheet surface.

  However, as a typical coating defect of a roll coater including a three roll coater, there is a defect called roping. In this roping, streaks in the circumferential direction of the roll are transferred to the steel sheet, resulting in uneven film thickness and deterioration of appearance. Roping tends to occur more easily as the viscosity of the coating liquid is higher and as the roll peripheral speed is higher. In particular, when the steel plate speed is increased, the circumferential speed of each roll is also increased, so that the occurrence of roping becomes significant.

  As a technique for preventing roping, for example, Patent Document 1 discloses a technique for controlling a ratio of a line speed, an applicator roll circumferential speed, and a pickup roll circumferential speed to a specific range. Patent Document 2 discloses a method of keeping the paint temperature in the vicinity of the temperature at which the paint viscosity is minimized. Furthermore, in Patent Document 3, as a method for reducing the occurrence of roping in high-speed coating at a line speed of 200 mpm or higher, the peripheral speed of the pickup roll is 20 to 80 mpm, and the peripheral speed of the applicator roll is 200 to 1000 mpm which is higher than the line speed. A method for performing coating is disclosed.

  However, with the techniques disclosed in Patent Document 1 and Patent Document 2, even when the line speed is low, roping can be prevented. However, when the line speed is high, the effect of preventing roping is insufficient. The line speed at which a uniform appearance without roping can be obtained is less than 200 mpm, which can be a factor that hinders productivity.

  Further, in the method disclosed in Patent Document 3, when the peripheral speed of the applicator roll is increased, the roping pitch on the applicator roll becomes finer and the roping is less noticeable on the steel plate, but the peripheral speed of the applicator roll is increased. If the line speed is increased too much, the flow of the coating solution is disturbed at the position where the applicator roll and the steel plate are in contact with each other, and the interface of the coating solution locally vibrates in the width direction, causing unevenness of the film thickness on the steel plate. In some cases, a pattern was generated. Thus, increasing the peripheral speed of the applicator roll is an effective means for roping, but there is a risk of creating a new deterioration factor of the appearance of coating.

In any of the coating methods disclosed in Patent Documents 1 to 3, the coating film thickness in the liquid film state after coating is about 10 μm. If the coating film thickness in the liquid film state after coating is about 10 μm, even if the liquid film immediately after coating has irregularities, it will be leveled during drying, so the film thickness unevenness after drying will be at a level that does not cause a problem Is suppressed until. Therefore, when the wet film thickness after application is about 10 μm, the problem of film thickness unevenness after drying has not been realized.
JP 2000-254580 A JP 9-47716 A JP-A-10-309512

  In recent years, from the viewpoint of improving functionality, it has been required to reduce the coating thickness so that the thickness after coating and drying is less than 0.1 μm. In order to reduce the coating film thickness, it is necessary to reduce the coating thickness when the coating film is applied to the substrate in a liquid state.

  However, even if any of the methods described in Patent Documents 1 to 3 above is used, if the film is thinned at the time of applying the coating film, there is a problem that film thickness unevenness after drying remains. Occur. This is because the minute unevenness of the film thickness at the time of applying the coating film is not eliminated by the subsequent leveling and remains as the film thickness unevenness after drying.

  Accordingly, the present invention provides a roll coating method capable of reducing the thickness of a coating film without inhibiting productivity on a continuously running substrate and without causing film thickness unevenness on the substrate surface. And it aims at providing a roll coating device.

In order to solve the above problems, the present invention has the following features.
[1] The amount of the coating liquid supplied to the pickup roll is adjusted with a metering roll, the adjusted amount of coating liquid is supplied from the pickup roll to the applicator roll, and the applicator supplied with the coating liquid In a roll coating method using a three-roll coater for contacting a roll with a continuously running substrate and applying a coating solution to the substrate surface,
As the applicator roll, a roll having a roll diameter of 50 mm to 150 mm is used.
Using a precoater having at least one roll on the upstream side of the three-roll coater in the substrate running direction, a coating solution having the same composition as the coating solution applied by the three-roll coater on the surface on which the coating solution for the substrate is applied With a liquid film thickness of less than 5 μm,
When the coating solution on the precoated substrate is in a liquid state, the coating solution is applied to the substrate with a thickness of a liquid film of less than 3 μm by the three-roll coater ,
A roll coating method, wherein the film thickness after drying is less than 0.1 μm .
[2] A roll coating method according to [1], wherein a roll having a roll diameter of 150 mm or less is used as the coating roll that comes into contact with the substrate during pre-coating.
[3] In the above [1] or [2], a gravure roll in which a large number of recesses are formed on the surface of the body is used as the pickup roll, and the volume of the large number of recesses formed on the surface of the body is large. A roll coating method characterized by being less than 10 cm ³ / m ² .
[4] A pickup roll to which the coating liquid is supplied, a metering roll for adjusting the liquid volume of the coating liquid supplied to the pickup roll, and a coating liquid supplied from the pickup roll with the liquid volume adjusted, A three-roll coater provided with an applicator roll for applying the supplied coating liquid to a continuously running substrate;
On the upstream side of the substrate running direction of the three-roll coater, a surface of the substrate to which the coating solution is applied is precoated with a coating solution having the same composition as the coating solution applied with the three-roll coater, and the precoated coating is applied. A roll coater provided with a precoater provided at a position where the liquid reaches the three-roll coater in a liquid state,
The roll diameter of the applicator roll constituting the three-roll coater is more than 50 mm and 150 mm or less, the thickness of the liquid film of the coating liquid applied by the precoater is less than 5 μm, and the liquid film of the coating liquid applied by the three-roll coater The roll coating apparatus is characterized by having a thickness of less than 3 μm and a dried film thickness of less than 0.1 μm .
[5] The roll coating apparatus according to [4], wherein in the precoater, the roll diameter of the coating roll contacting the substrate is 150 mm or less.

  According to the present invention, roll coating that can reduce the thickness of a coating film on a continuously running substrate without impairing productivity and without causing film thickness unevenness on the surface of the substrate. A method and roll applicator are provided.

  In order to reduce the film thickness after coating and drying, a method of diluting the coating liquid can be considered. However, it has been found that the appearance often deteriorates when diluted too much, and it is necessary to reduce the film thickness when it is applied to the substrate in a liquid state. The concentration that can be diluted varies slightly depending on the type of treatment liquid, and in some cases, even if there is an additive such as a surfactant, the film thickness is more uniform when applied at a concentration of about 1% or more. The result that it was easy to ensure the property and the good appearance was obtained. Therefore, in order to form a film with a thickness of less than 0.1 μm after drying, it is necessary to reduce the thickness of the liquid film at the time of application to less than 3 μm, and preferably to about 1 μm. We studied diligently.

  Hereinafter, an example of the best mode for carrying out the present invention will be described.

  FIG. 1 is a diagram showing an example of the configuration of a roll coating apparatus to which the roll coating method according to the present invention is applied. As shown in FIG. 1, a roll coating apparatus according to the present invention includes a pickup roll 4 that draws up a coating liquid 3 from a coater pan 2, and a mixing roll 5 that adjusts the amount of coating liquid supplied to the pickup roll 4. And an applicator roll 6 that is supplied (transferred) to the belt-like substrate 1 that is continuously supplied with the application liquid from the pickup roll 4 whose liquid amount is adjusted by the mitering roll 5. The 3-roll coater A provided with the above-mentioned 3-roll coater is coated on the surface of the 3-roll coater A on the upstream side of the substrate running direction with the 3-roll coater A. And a precoater B for precoating a coating liquid having the same composition as the liquid. Here, the precoater B is provided at a position where the coating liquid precoated by the precoater B reaches the three-roll coater A in a liquid state.

  In the present invention, the applicator roll 6 has a roll diameter of 150 mm or less. Moreover, as the coating roll 9 which comprises the said precoater B and contacts the base material 1 at the time of a precoat, it is preferable to use that whose roll diameter is 150 mm or less.

  Moreover, as the pick-up roll 4 which comprises the said 3 roll coater A, it is preferable to use the gravure roll in which many recessed parts were formed in the trunk | drum surface.

Here, there is no restriction | limiting in particular about the shape of the recessed part formed in the trunk | drum surface of this pick-up roll 4, For example, various things, such as a diagonal line shape, a grid | lattice shape, a pyramid shape, a polygonal shape, a linear shape, can be used. . However, with regard to the ratio of the recess pitch in the roll width direction to the recess depth, when the recess pitch is very long and the recess depth is extremely shallow, coating defects due to the recess pitch may occur. On the contrary, if the recess pitch is very fine and the recess depth is extremely deep, there is a high possibility that eyes will be clogged and the film thickness will not be stable. Therefore, it is preferable that the recess pitch in the roll width direction is about 3 to 7 times the recess depth. In addition, it is preferable to set it as about 30-100 micrometers as a space | interval of a recessed part pitch. Furthermore, it is preferable that the volume of a large number of recesses formed on the body surface is less than 10 cm ³ / m ² in order to achieve a target coating liquid film of 3 μm or less. In addition, when the material to be coated is a metal band, if it is less than 1 cm ³ / m ² , only the same effect as a flat roll can be obtained, and therefore it is preferably 1 cm ³ / m ² or more.

  The method of supplying the coating liquid 3 to the pickup roll 4 is not limited to the method of pumping the coating liquid 3 from the coater pan 2. For example, a pump type die coater, spray coater, etc., any method can be used as long as the supply system can adjust the film thickness of the coating liquid 3 to the pickup roll 4 and obtain a smooth coating surface. Can do.

  The rotation direction of each roll of the three-roll coater A is shown as a reverse direction between the rolls or between the applicator roll 6 and the substrate 1, but the rotation direction of the roll is not particularly specified. However, as described above, when the roughness of the belt-like substrate 1 is large, the reverse direction is preferable between the applicator roll 6 and the substrate 1 from the viewpoint of uniform film thickness applicability. Further, it is preferable to install a blade 7 for scraping the coating liquid 3 on the mixing roll 5.

  Here, when the substrate 1 is a metal plate such as a steel plate, the applicator roll 6 is preferably a rubber roll lined with rubber. This is to prevent the surface of a metal plate such as a steel plate from being damaged.

  In the example shown in FIG. 1, the base material 1 is in a state of being wound around the backup roll 8 and shows a general case where the coating liquid is applied to one side thereof. However, the present invention can also be applied to the case of simultaneous application on both sides where the three roll coater A is disposed on both sides of the substrate 1 and the backup roll 8 is not required. Further, the plate-passing direction of the substrate 1 may be either a horizontal pass method or a vertical pass method.

  In the example shown in FIG. 1, the precoater B, which is disposed upstream of the traveling direction of the base material 1 of the three-roll coater A and preliminarily coats (precoats) the coating liquid on the base material 1, is applied to the roll 9 and the roll 9. It comprises a roll 10 for supplying (transferring) and a pan 11. Here, the roll 9 is a rubber roll lined with rubber. The roll 10 uses a metal roll, and the pan 11 is supplied with the coating liquid 3 having the same composition as the coating liquid 3 applied to the substrate 1 by the three-roll coater A.

  In the example shown in FIG. 1, the precoater B is described as having two rolls, but when a supply device capable of controlling the film thickness is provided, a one-roll precoat device may be used. . In addition, a three-roll precoater having three rolls is more preferable than a two-roll precoater having two rolls because it is more advantageous in terms of film thickness controllability, but it is expensive. Further, the coating liquid supply device of the precoater B is not limited to the method of drawing up from the pan 11. For example, you may employ | adopt the system which coats a coating liquid from a nozzle to a roll.

  Moreover, the rotation direction of each roll when using two or more rolls in the precoater, or the rotation direction between the applicator roll 9 and the base material 1 is shown in the figure as a reverse direction. Is not particularly stipulated.

  By using the roll coating method according to the present invention using the roll coating apparatus configured as described above, a good appearance is ensured even when the thickness of the liquid film of the coating liquid applied by the three-roll coater A is less than 3 μm. can do. Further, when the thickness of the liquid film of the coating solution is less than 3 μm, the thickness of the liquid film of the coating solution applied (pre-coated) by the precoater B is preferably less than 5 μm.

  Hereinafter, the reason why the roll diameter of the applicator roll 6, the roll diameter of the coating roll 9 constituting the precoater B, and the thickness of the liquid film of the coating solution applied (precoated) by the precoater B will be described.

  In the three-roll type coater having the above configuration, a basic investigation was performed on the relationship between the roll diameter of the applicator roll 6 and the film thickness unevenness after coating. Using the 3-roll coater A shown in FIG. 1, the situation of the meniscus portion between the applicator roll and the substrate when the roll diameter of the applicator roll 6 is 50 mm to 450 mm, and after application to the substrate surface The film thickness distribution in the transport direction was investigated.

  The line speed of the substrate 1 was 100 mpm, and a galvanized steel plate having a thickness of 0.6 mm was used for the substrate 1. In addition, the coating liquid contains a phosphoric acid-based water-based paint (containing a phosphoric acid compound, an Mg compound, silica, and a tetravalent vanadium compound) (concentration 3%, viscosity at a liquid temperature of 20 ° C .: 3 mPa · s, surface tension: 40 dyn / cm, specific gravity of the film: 1.2) was used. The phosphoric acid-based water-based paint was used for all the coating liquids in this experiment, but a coating liquid having a predetermined concentration was adjusted by appropriately changing the dilution rate with water.

For example, a gravure roll having a surface recess volume of 5.8 cm ³ / m ² was used as the pickup roll 4.

  Moreover, the roll peripheral speed of the pick-up roll 4 was adjusted so that the coating film thickness in the liquid film state after application was 2.6 μm and the average film thickness after drying was 0.08 μm.

  Moreover, the coating roll 9 which comprises the precoater B used the thing with a diameter of 150 mm.

  FIG. 2 shows the relationship between the roll diameter of the applicator roll 6 and the film thickness unevenness after coating and drying. Here, the film thickness unevenness was calculated from the difference between the maximum value and the minimum value of the measured values by measuring the film thickness of a 3 mm area in the transport direction and the width direction at a pitch of 10 μm with respect to the coated substrate.

  As shown in FIG. 2, when the roll diameter of the applicator roll 6 is set to 150 mm or less, the film thickness unevenness becomes 5% or less with respect to the target film thickness, and it became clear that uniform application is possible. When the roll diameter of the applicator roll 6 is large, the contact length of the coating liquid at the meniscus portion between the applicator roll 6 and the substrate 1 becomes long. Therefore, it is considered that the vibration of the meniscus portion becomes remarkable and the film thickness unevenness is generated.

  By reducing the diameter of the applicator roll 6, the vibration of the meniscus portion was reduced, and when it was 150 mm or less, the occurrence of vibration was almost eliminated and it was confirmed that the applicator roll 6 was uniformly applied. The lower limit of the diameter of the applicator roll is not particularly limited as long as application is possible, but is preferably 50 mm or more in consideration of performing high-speed application of about 100 mpm.

  Next, the influence of the coating film thickness by Precoater B was investigated. In the roll coating apparatus according to the present invention, as described above, the precoater B is installed on the upstream side in the traveling direction of the base material 1 of the three-roll coater A, and the pre-coating (preliminary coating) is performed before the coating solution is applied by the three-roll coater A. ).

  The relationship between the film thickness of the coating liquid pre-coated with the pre-coater B and the film thickness of the coating liquid after coating with the 3-roll coater A was investigated. In the same manner as described above, a galvanized steel sheet having a plate thickness of 0.6 mm was used as the substrate 1 at a line speed of 100 mpm. Further, the above-described phosphoric acid-based water-based paint (concentration 3%, viscosity at a liquid temperature of 20 ° C .: 3 mPa · s, surface tension: 40 dyn / cm, specific gravity of film: 1.2) was used as the coating solution.

  The effect of the precoat liquid film thickness on the coating liquid film thickness was investigated under the peripheral speed conditions where the measurement result of the coating liquid film thickness without the precoat was 2.6 μm. FIG. 3 shows the relationship between the film thickness of the coating liquid precoated with the precoater B (precoat liquid film thickness) and the film thickness of the coating liquid after coating with the 3-roll coater A. When the film thickness applied in the pre-coating is thick, the liquid film applied by the pre-coating slips through the contact portion between the applicator roll 6 and the substrate 1, so that the liquid film after application by the 3-roll coater A is used. The thickness becomes thicker than when no pre-coating is performed. In order to realize thin film coating with a thickness of less than 3 μm in the 3-roll coater A, it has become clear that the film thickness of the coating solution pre-coated with the pre-coater B needs to be less than 5 μm.

  Here, if the thickness of the liquid film of the coating liquid applied by the precoater B is less than 5 μm, the final film thickness is not affected. Further, at the time of pre-coating, there is no influence on the final appearance even if there is film thickness non-uniformity on the order of roping. Therefore, it is possible to achieve the object of the present invention even with a single roll precoater.

  Further, even when the roll diameter of the coating roll 9 of the precoat roll is large, vibration of the meniscus portion between the coating roll 9 and the substrate 1 occurs, and the film thickness of the precoat liquid film becomes nonuniform. After the pre-coating, since the coating solution is applied by the 3-roll coater A, if the 3-roll coater is then applied under suitable conditions, the film thickness unevenness at a level with no problem occurs. However, when the precoat liquid film thickness is large, the liquid film supplied from the precoater B slips through at the contact portion between the applicator roll 6 and the substrate 1, and thus the film thickness unevenness generated in the precoater B cannot be completely removed. It also happens. Therefore, the diameter of the coating roll 9 of the roll precoat roll is preferably 150 mm or less.

  In the roll coating apparatus according to the present invention, as shown in FIG. 1, the pre-coater B is provided on the upstream side in the traveling direction of the base material 1 of the three-roll coater A. As shown in FIG. 4, in the case of a roll coating apparatus that does not have a precoater, when a coating film having a liquid film thickness of less than 3 μm is applied, streak-like patterns and creases are generated in the line direction. It becomes easy. The reason why the streaky pattern is generated is that the air flow accompanying the substrate 1 disturbs the meniscus between the substrate 1 and the applicator roll 6. As a cause of the occurrence of glazing, when the liquid film thickness to be applied is as thin as less than 3 μm, the amount of liquid applied to the convex portion becomes extremely thin due to the unevenness of the surface of the substrate 1. For this reason, liquid breakage is likely to occur. Therefore, in order to obtain a uniform film thickness without generating a streak pattern, it is necessary to prevent the air accompanying the substrate 1 from affecting the meniscus between the applicator roll 6 and the substrate 1.

  As shown in the roll coating apparatus according to the present invention in FIG. 1, the precoater B is installed on the upstream side in the traveling direction of the base material 1 of the three-roll coater A, so that the coating liquid precoated on the base material 1 is applied to the applicator roll. 6 flows into the gap between the base material 1 and the air accompanying the base material 1 effectively. As a result, uniform application was possible without generating streak patterns. Moreover, since pre-coating (preliminary application) is performed in advance with the pre-coater B, contact with the applicator roll 6 in a state in which a coating film is formed on the surface of the steel sheet 1, and generation of creases (wrinkles) is eliminated.

  In the above description, the substrate 1 can be applied to a steel plate such as a cold-rolled steel plate, a metal plate such as aluminum, and the like.

  The present invention will be described in detail by the following examples and comparative examples.

  For the coil of a galvanized steel sheet having a plate thickness of 0.6 mm and a plate width of 1200 mm, coating is performed under the coating conditions shown in Table 1 using the roll coating apparatus shown in FIG. The liquid film thickness at the time of coating was calculated from the presence and absence, the film thickness, the coating liquid concentration, the film thickness after drying, and the specific gravity of the film. In the roll coating apparatus shown in FIG. 1, the material of each roll is a rubber roll in which an applicator roll 6 is lined with rubber, and a pickup roll 4 is a gravure roll having a number of recesses formed on the surface (groove shape of recesses: oblique lines, The pitch of the recesses: 250 lines / inch), and the mitering roll 5 was a rubber roll lined with rubber. The roll diameter of each roll used was 150 mm for the applicator roll 6, 300 mm for the pickup roll 4, and 200 mm for the mitering roll 5.

  The peripheral speed of the mitering roll 5 was adjusted in the range of 10 to 90 mpm according to the target coating film thickness.

  The liquid film applied by the precoater B was adjusted to have a predetermined film thickness shown in Table 1 by adjusting the peripheral speed of the roll and the nip pressure. As the roll of the precoater B, a roll having a roll diameter of 150 mm was used. Moreover, the application roll 9 which contacts the base material 1 used a rubber roll, and used the metal roll for the roll 10 which draws up an application liquid from the pan 11.

  The above-mentioned phosphoric acid-based water-based paint was used by adjusting to various concentrations.

  For film thickness unevenness after coating by the 3-roll coater A, the film thickness distribution in the conveyance direction and width direction of the steel sheet is measured, the difference between the maximum value and the minimum value of the measured value is obtained, and the film thickness difference becomes the target film thickness. On the other hand, when it was 5% or less, there was no film thickness unevenness, and when it exceeded 5%, it was determined that there was film thickness unevenness.

  As a comparative example, when the pre-coating apparatus as shown in FIG. 4 is not used, when the diameter of the applicator roll 6 is 300 mm and the diameter of the application roll 9 is 150 mm, the diameter of the applicator roll 6 and the diameter of the application roll 9 are both 300 mm. In the case of the applicator roll 6 having a diameter of 150 mm and the coating roll 9 having a diameter of 300 mm, the liquid film thickness at the time of application is determined from the presence or absence of film thickness unevenness and the film thickness after drying, the coating liquid concentration, the film thickness after drying, and the film specific gravity. Was calculated.

  As shown in Table 1, in the example of the present invention, it is possible to uniformly apply a film having a liquid film thickness of less than 3.0 μm at the time of application by the 3-roll coater A and a film thickness of less than 0.1 μm after drying. It has become possible.

  On the other hand, when the coating film thickness when the precoat apparatus was not used was less than 3 μm and the film thickness after drying was less than 0.1 μm, the appearance on the surface of the steel sheet 1 was blurred. In addition, when the conditions for applying a film thickness of less than 0.1 μm after drying were examined without using a precoater and the film thickness was less than 0.1 μm were examined, it was suppressed if the coating liquid concentration was lowered to a coating liquid film thickness of 3 μm or more. However, repelling occurred.

  When the diameter of the applicator roll 6 is 300 mm, the liquid film thickness at the time of application by the 3 roll coater A is 10 μm, and when the film thickness after drying is less than 0.1 μm, the liquid is diluted too much. Although it seems, the repelling occurred and the film thickness unevenness after drying occurred. When the thickness of the applicator roll 6 was 300 mm and the liquid film thickness at the time of application was less than 3.0 μm, the film thickness unevenness after drying was noticeably generated.

  Even when a precoater was used, when the diameter of the coating roll 9 was 300 mm, the film thickness after drying occurred. In addition, when the precoat film thickness is 5 μm or more, the film thickness after coating with the 3-roll coater A is 3 μm or more, so that the film thickness after drying is less than 0.1 μm, the liquid concentration Under these conditions, repelling occurred and the film thickness after drying became non-uniform.

It is the figure which showed an example of the structure of the roll coating apparatus with which the roll coating method which concerns on this invention is applied. It is a figure which shows the relationship between the roll diameter of an applicator roll, and the film thickness nonuniformity after application | coating drying. It is a figure which shows the relationship between the film thickness (precoat film thickness) of the coating liquid precoated with a precoater, and the film thickness of the coating liquid after apply | coating with a 3 roll coater. It is the figure which showed an example of the structure of the roll coating device which does not have the precoater concerning a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Coater pan 3 Coating liquid 4 Pickup roll 5 Mitering roll 6 Applicator roll 7 Blade 8 Backup roll 9,10 roll 11 Pan plate A 3 roll coater B Precoater

Claims (5)

The liquid amount of the coating liquid supplied to the pickup roll is adjusted with a mitering roll, the coating liquid of the adjusted liquid amount is supplied from the pickup roll to the applicator roll, and the applicator roll supplied with the coating liquid is In a roll coating method using a three-roll coater that contacts a continuously running substrate and applies a coating solution to the substrate surface,
As the applicator roll, a roll having a roll diameter of 50 mm to 150 mm is used.
Using a precoater having at least one roll on the upstream side of the three-roll coater in the substrate running direction, a coating solution having the same composition as the coating solution applied by the three-roll coater on the surface on which the coating solution for the substrate is applied With a liquid film thickness of less than 5 μm,
When the coating solution on the precoated substrate is in a liquid state, the coating solution is applied to the substrate with a thickness of a liquid film of less than 3 μm by the three-roll coater ,
A roll coating method, wherein the film thickness after drying is less than 0.1 μm .   The roll coating method according to claim 1, wherein a roll having a roll diameter of 150 mm or less is used as the coating roll that comes into contact with the substrate during pre-coating. The pickup roll is a gravure roll having a large number of recesses formed on the surface of the body, and the volume of the large number of recesses formed on the surface of the body is less than 10 cm ³ / m ^2. The roll coating method according to claim 1 or 2. A pickup roll supplied with the coating liquid, a metering roll for adjusting the amount of the coating liquid supplied to the pickup roll, and the coating liquid supplied from the pickup roll with the liquid amount adjusted A three-roll coater provided with an applicator roll for applying a coating solution to a continuously running substrate;
On the upstream side of the substrate running direction of the three-roll coater, a surface of the substrate to which the coating solution is applied is precoated with a coating solution having the same composition as the coating solution applied with the three-roll coater, and the precoated coating is applied. A roll coater provided with a precoater provided at a position where the liquid reaches the three-roll coater in a liquid state,
The roll diameter of the applicator roll constituting the three-roll coater is more than 50 mm and 150 mm or less, the thickness of the liquid film of the coating liquid applied by the precoater is less than 5 μm, and the liquid film of the coating liquid applied by the three-roll coater The roll coating apparatus is characterized by having a thickness of less than 3 μm and a dried film thickness of less than 0.1 μm .   The roll coating apparatus according to claim 4, wherein in the precoater, the roll diameter of the coating roll that contacts the substrate is 150 mm or less.

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