Method for producing laminate

Abstract

To provide a method for manufacturing a laminate capable of thinly and uniformly forming a thin film layer even when the viscosity of a coating liquid is high.SOLUTION: A method for producing a laminate according to the present disclosure is a method for producing a laminate including a substrate and a thin film layer formed on the substrate, the method including a coating step of applying a coating liquid onto a surface of the substrate using a die coater to form a coating liquid layer, and a thin film layer forming step of curing the coating liquid layer to form the thin film layer, wherein a viscosity μ of the coating liquid is 1 to 30 Pa·s, a thickness h of the coating liquid layer is 5 to 40 μ m, and the viscosity μ of the coating liquid and a width W of a slot of the die coater satisfy Formula (1): 0.01 μ + 0.08 ≤ W ≤ 0.06 μ + 0.2 (1) Here, the viscosity of the coating liquid is substituted for μ in Equation (1) in units of Pa·s. The slot width (unit: mm) of the die coater is substituted for W in the formula (1).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a laminate. [Background technology]

[0002] To date, a method for manufacturing a laminate having a thin film layer on a substrate has been used in which a coating liquid is applied to the surface of the substrate using a slot die coater to form a coating liquid layer, and then the coating liquid layer is cured to form a thin film layer. Hereinafter, in this specification, a slot die coater will also be simply referred to as a "die coater." Here, the die coater ejects the coating liquid from a slot via a manifold formed inside. Furthermore, the substrate is moved relative to the die coater to form a coating liquid layer on the substrate.

[0003] To date, technologies for forming a coating liquid layer using a die coater have been disclosed in Japanese Patent Laid-Open No. 2014-30786 (Patent Document 1), Japanese Patent Laid-Open No. 2016-175052 (Patent Document 2), and Japanese Patent Laid-Open No. 2008-149223 (Patent Document 3).

[0004] The method of applying a coating film using a die coater disclosed in Patent Document 1 involves bringing a slot die (die coater) close to a substrate film, ejecting a coating agent (coating liquid) from the tip of the slot die to form a bead between the slot die and the substrate film, and applying the coating agent to the surface of the substrate film while reducing the pressure on the upstream side of the bead. When μ is the viscosity of the coating agent, σ is the static surface tension of the coating agent, V is the relative speed between the substrate film and the tip of the slot die, L is the distance between the end of the upstream die lip's outlet and the contact line, L1 is the thickness of the downstream die lip, H is the coating gap, h is the coating film thickness, and Ca is the number of capillaries (Ca=μ·V / σ), Equation (1) is satisfied. Ca / (L / L1)≦0.1309e 0.2212(H / h) (1) Patent Document 1 states that this method makes it possible to consistently apply a coating film with a uniform thickness and good appearance, even when applying a thin coating of a low-viscosity coating agent, which is prone to causing poor appearance, by suppressing the occurrence of streaky unevenness caused by air entrainment that occurs with high-speed coating.

[0005] The coating device disclosed in Patent Document 2 is a coating device that includes at least a slit die (die coater) for applying a coating liquid to a substrate being transported, and a pressure reducing means located upstream of the slit die in the substrate transport direction, and the slit die is provided with baffles on both ends of the lip in the width direction outside the slit die to suppress air movement from the downstream side to the upstream side in the substrate transport direction relative to the slit die, and the baffles are arranged so as not to come into contact with the substrate. Patent Document 2 states that use of this coating device makes it possible to stably coat a coating liquid with a relatively low viscosity in a relatively thin film.

[0006] The coating device disclosed in Patent Document 3 moves a coating die (die coater) having a slit-shaped outlet at its tip for supplying the coating liquid relative to the workpiece (substrate), and supplies the coating liquid from the outlet. The coating device includes a gas ejection device that ejects gas downstream of the coating die in the direction of travel near the position where the coating liquid is supplied to the workpiece from the outlet, and ejects gas from the gas ejection device at an angle downstream of the direction of travel of the coating die. Patent Document 3 states that this coating device makes it possible to appropriately control the heel portion of the coating liquid supplied to the workpiece, and that even if dust or the like is present on the surface of the workpiece, the gas removes the dust or the like from the surface of the workpiece. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-30786 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-175052 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-149223 Summary of the Invention [Problem to be solved by the invention]

[0008] Incidentally, in recent years, with the miniaturization and high functionality of electronic devices, there has been a demand for thinner laminates. In other words, there has been a demand for technology that can form thinner thin film layers of laminates. On the other hand, in laminate manufacturing methods using a die coater, the higher the viscosity of the coating liquid, the thicker the coating liquid layer formed. The thicker the coating liquid layer, the thicker the thin film layer formed after curing. Therefore, there has been a demand for a laminate manufacturing method using a die coater that can form a thin and uniform coating liquid layer even when the viscosity of the coating liquid is high.

[0009] The above Patent Documents 1 to 3 disclose methods for forming a coating liquid layer using a die coater and die coater technologies. However, Patent Documents 1 to 3 do not consider at all a method for forming a thin coating liquid layer when the viscosity of the coating liquid is high.

[0010] An object of the present disclosure is to provide a method for producing a laminate that can form a thin, uniform thin film layer even when the viscosity of the coating liquid is high. [Means for solving the problem]

[0011] A method for producing a laminate according to the present disclosure includes: A method for manufacturing a laminate including a substrate and a thin film layer formed on the substrate, comprising: a coating step of applying a coating liquid onto a surface of the substrate using a die coater to form a coating liquid layer; and a thin film layer forming step of curing the coating liquid layer to form the thin film layer, The viscosity μ of the coating liquid is 1 to 30 Pa s, The thickness h of the coating liquid layer is 5 to 40 μm, The viscosity μ of the coating liquid and the width W of the slot of the die coater satisfy the formula (1). 0.01μ+0.08≦W≦0.06μ+0.2 (1) Here, the viscosity of the coating liquid is substituted for μ in the formula (1) in units of Pa·s, and the slot width of the die coater is substituted for W in the formula (1) in units of mm. [Effects of the Invention]

[0012] The method for producing a laminate according to the present disclosure can form a thin, uniform thin film layer even when the viscosity of the coating liquid is high. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a flow diagram showing an example of a method for producing a laminate according to this embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing an example of the coating step in the method for producing a laminate according to this embodiment. [Figure 3] FIG. 3 is a partial cross-sectional view showing region 100 of FIG. [Figure 4] FIG. 4 is a partial cross-sectional view showing another example of the region 100 in FIG. 2 in FIG. [Figure 5] FIG. 5 is a partial cross-sectional view showing another example of the region 100 in FIG. 2 in FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0014] The method for manufacturing a laminate according to the present embodiment will now be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0015] [Method of manufacturing laminate] In the method for manufacturing a laminate according to this embodiment, a thin film layer is formed on the surface of a substrate. FIG. 1 is a flow diagram showing an example of the method for manufacturing a laminate according to this embodiment. Referring to FIG. 1, the method for manufacturing a laminate according to this embodiment may include a coating step S1, a drying step S2, and a thin film layer forming step S3. Here, the drying step S2 is an optional step. That is, the method for manufacturing a laminate according to this embodiment may include only the coating step S1 and the thin film layer forming step S3. The method for manufacturing a laminate according to this embodiment may further include steps other than the coating step S1, the drying step S2, and the thin film layer forming step S3. For example, the method may include a step of preparing a substrate before the coating step S1, or a step of processing the laminate into a desired shape after the thin film layer forming step S3. Each step will be described below.

[0016] In this embodiment, the substrate is not particularly limited, and a well-known substrate can be used. The material of the substrate may be, for example, metal, resin, or glass. The substrate may further be formed by laminating multiple materials. Specifically, the substrate may be, for example, a metal substrate having a resin layer formed on its surface. The shape of the substrate is also not particularly limited. The substrate may be, for example, foil-shaped, plate-shaped, or tubular-shaped. That is, the substrate may be any substrate as long as a thin film layer can be formed on its surface. Preferably, the substrate is foil-shaped. In this case, the substrate can be transported by a backup roll described below, and a laminate can be continuously produced.

[0017] [Coating process S1] In the coating step S1, a coating liquid is applied onto the surface of a substrate using a die coater to form a coating liquid layer. FIG. 2 is a cross-sectional view showing an example of the coating step S1 in the method for producing a laminate according to this embodiment. In FIG. 2, the substrate 1 is transported by a backup roll 20, and the coating liquid is applied onto the surface of the substrate 1 by a die coater 10 supported by a support member (not shown), thereby forming a coating liquid layer 2. In the coating step S1, the substrate 1 may be transported as shown in FIG. 2, or the die coater 10 may be transported. That is, in the coating step S1, it is sufficient that the substrate 1 moves relative to the die coater 10.

[0018] Preferably, the coating step S1 is performed by a so-called roll-to-roll method in which the substrate 1 is transported by a backup roll 20, as shown in Fig. 2. In this case, the coating liquid is continuously applied to the substrate 1 while it is being transported. Therefore, the laminate can be produced with high production efficiency.

[0019] The die coater 10 includes a first die 11 and a second die 12 that are arranged in a direction in which the substrate 1 moves relative to the die coater 10. Hereinafter, in this specification, the direction in which the first die 11 is arranged in the die coater 10, i.e., the downward direction in FIG. 2, is also referred to as the "upstream coating side." Hereinafter, in this specification, the direction in which the second die 12 is arranged in the die coater 10, i.e., the upward direction in FIG. 2, is also referred to as the "downstream coating side."

[0020] Referring to FIG. 2 , the die coater 10 further includes a shim plate 13 between the first die 11 and the second die 12. The shim plate 13 forms a gap (slot) between the first die 11 and the second die 12, which serves as a flow path for the coating liquid. The die coater 10 also includes a manifold 14 for holding the coating liquid. The coating liquid is introduced into the manifold 14 from outside the die coater 10 through a flow path not shown. The coating liquid introduced into the manifold 14 is introduced onto the surface of the substrate 1 through the slot formed by the first die 11 and the second die 12.

[0021] The tip of the die coater 10 will be described in further detail. Fig. 3 is a partial cross-sectional view showing region 100 in Fig. 2. That is, Fig. 3 is a partial cross-sectional view showing an enlarged view of the tip of the die coater 10. Referring to Fig. 3, the coating liquid is discharged from a slot 15 formed by a first die 11 and a second die 12 of the die coater 10, and forms a bead 3 on the surface of the substrate 1. Further referring to Fig. 3, a coating liquid layer 2 is formed on the surface of the substrate 1 downstream of the bead 3 in the coating direction.

[0022] The tip of the first die 11 includes a first surface 111 facing the substrate 1, a second surface 112 adjacent to the first surface 111 on the upstream side of the coating, and a third surface 113 adjacent to the first surface 111 on the downstream side of the coating. Similarly, the tip of the second die 12 includes a first surface 121 facing the substrate 1, a second surface 122 adjacent to the first surface 121 on the downstream side of the coating, and a third surface 123 adjacent to the first surface 121 on the upstream side of the coating. In other words, the slot 15 is formed by the third surface 113 of the first die 11 and the third surface 123 of the second die 12. As will be described in detail later, the second die 12 may have a shape including multiple surfaces facing the substrate 1. In this case, of the surfaces of the second die 12 facing the substrate 1, the surface closest to the substrate 1 is referred to as the first surface 121. Similarly, when the first die 11 has a shape including a plurality of surfaces facing the substrate 1, the surface of the first die 11 facing the substrate 1 that is closest to the substrate 1 is referred to as the first surface 111.

[0023] 3, the distance between the surface of the substrate 1 and the first surface 111 of the first die 11 or the first surface 121 of the second die 12 is also referred to as the coating gap H. As described above, in the coating step S1 according to this embodiment, the bead 3 is formed on the surface of the substrate 1. In other words, in the coating step S1 according to this embodiment, the coating gap H is adjusted to stably form the bead 3.

[0024] [Coating liquid viscosity μ] As described above, in the coating step S1, the coating liquid discharged through the slot 15 forms a bead 3 on the surface of the substrate 1, thereby forming a coating liquid layer 2. In this embodiment, the viscosity μ of the coating liquid is 1 to 30 Pa·s. In this embodiment, the type of coating liquid is not particularly limited as long as the viscosity μ of the coating liquid is 1 to 30 Pa·s. The coating liquid may contain, for example, a polymerizable or crosslinkable compound, a functional material, and a solvent. Here, the functional material includes a flame retardant, a filler, an antioxidant, a surfactant, a pigment, and the like. The filler is, for example, silica.

[0025] [Formula (1)] In the coating step S1 according to this embodiment, the viscosity μ of the coating liquid and the width W of the slot 15 of the die coater 10 further satisfy the formula (1). 0.01μ+0.08≦W≦0.06μ+0.2 (1) Here, the viscosity of the coating liquid is substituted for μ in equation (1) in units of Pa·s, and the width of the slot 15 of the die coater 10 is substituted for W in equation (1) in units of mm.

[0026] As described above, the slot 15 is formed by the third surface 113 of the first die 11 and the third surface 123 of the second die 12. That is, the width W of the slot 15 means the width between the third surface 113 of the first die 11 and the third surface 123 of the second die 12. The width W of the slot 15 also corresponds to the thickness of the shim plate 13 of the die coater 10.

[0027] As described above, the higher the viscosity μ of the coating fluid, the thicker the coating fluid layer 2 tends to be. Therefore, one method for thinning the coating fluid layer 2 is to reduce the amount of coating fluid discharged from the slot 15. However, reducing the amount of coating fluid discharged from the slot 15 reduces the discharge pressure of the coating fluid. A reduction in the discharge pressure of the coating fluid results in a smaller bead 3 formed on the surface of the substrate 1. As a result, the coating gap H required for stable formation of the bead 3 becomes too small. In this case, there is a risk that the substrate 1 may come into contact with the die coater 10.

[0028] Therefore, the present inventors investigated stabilizing the coating fluid discharge pressure while reducing the amount of coating fluid discharged from the slot 15. As a result, it was found that by adjusting the width W of the slot 15 according to the viscosity μ of the coating fluid, the coating fluid discharge pressure can be adjusted and the coating fluid layer 2 can be stably formed. Specifically, Fn1 is defined as 0.01μ+0.08. Similarly, Fn2 is defined as 0.06μ+0.2. Fn1 and Fn2 correspond to the range of the width W of the slot 15 for stably forming the coating fluid layer 2 based on the viscosity μ of the coating fluid.

[0029] Here, the gas-liquid interface of the coating fluid downstream can be used as an indicator of the coating fluid discharge pressure. Referring to FIG. 3 , if the coating fluid discharge pressure is appropriate, the gas-liquid interface of the coating fluid downstream will be positioned at the interface between the first surface 121 and the second surface 122 of the second die 12. On the other hand, if the width W of the slot 15 is smaller than Fn1, the coating fluid discharge pressure will be too high. In this case, the gas-liquid interface of the coating fluid downstream will move toward the coating upstream and be positioned on the first surface 121 of the second die 12. As a result, streaky irregularities may form on the surface of the coating fluid layer 2. Therefore, in the coating step S1 according to this embodiment, the width W of the slot 15 is set to be equal to or greater than Fn1.

[0030] Furthermore, if the width W of the slot 15 is greater than Fn2, the discharge pressure of the coating liquid becomes too low. In this case, as described above, the bead 3 formed on the surface of the substrate 1 becomes small. As a result, the coating gap H required to stably form the bead 3 becomes too small. This raises the risk of the substrate 1 coming into contact with the die coater 10.

[0031] Therefore, in the coating step S1 according to this embodiment, the width W of the slot 15 is adjusted to Fn1 to Fn2. As a result, even when the viscosity μ of the coating liquid is as high as 1 to 30 Pa·s, the coating liquid layer 2 can be formed thin and uniform. As a result, the produced laminate has a thin and uniform thin film layer formed on the substrate 1. In this embodiment, Fn1 and Fn2 are calculated by rounding the obtained numerical values ​​to one decimal place.

[0032] [Thickness h of coating liquid layer 2] In the coating step S1 according to this embodiment, the thickness h of the coating fluid layer 2 formed is 5 to 40 μm. As described above, the higher the viscosity μ of the coating fluid, the thicker the coating fluid layer 2 is likely to be formed. On the other hand, in the coating step S1 according to this embodiment, the coating fluid layer 2 is formed thin, to 5 to 40 μm. To achieve this, the coating fluid discharge rate is reduced and the width W of the slot 15 is adjusted to Fn1 to Fn2, thereby adjusting the coating fluid discharge pressure. As a result, in the coating step S1 according to this embodiment, the thickness h of the coating fluid layer 2 can be reduced to 5 to 40 μm and then uniformly formed. Therefore, the thin film layer of the manufactured laminate is formed thin and uniformly.

[0033] [Method for measuring thickness h of coating liquid layer 2] In this embodiment, the thickness h of the coating fluid layer 2 is measured by the following method. Specifically, three arbitrary measurement positions are identified on the substrate 1 after the coating step S1 has been performed and before the thin film layer forming step S3, which will be described later, is performed. The thickness of the coating fluid layer 2 is measured at the three identified measurement positions using a laser measuring device. A well-known laser measuring device can be used as the laser measuring device. Specifically, for example, the double-scan high-precision laser measuring device LT-9000 manufactured by Keyence Corporation can be used. The arithmetic mean value of the thicknesses of the coating fluid layer 2 obtained at the three points is defined as the thickness h (μm) of the coating fluid layer 2. The thickness h (μm) of the coating fluid layer 2 is a value obtained by rounding the obtained value to one decimal place.

[0034] [Coating Gap H] As described above, in the coating step S1 according to this embodiment, the coating gap H is adjusted to stably form the bead 3. As described above, further referring to FIG. 3 , the coating gap H corresponds to the distance between the surface of the substrate 1 and the first surface 111 of the first die 11 or the first surface 121 of the second die 12.

[0035] As described above, in this embodiment, the viscosity μ of the coating fluid is high, at 1 to 30 Pa·s, and the coating fluid layer 2 is formed to a thickness of 5 to 40 μm. To achieve this, the amount of coating fluid discharged is reduced, and the width W of the slot 15 of the die coater 10 is adjusted to a range of Fn1 to Fn2. As a result, the coating gap H for stabilizing the bead 3 tends to become small. On the other hand, as described above, if the coating gap H is too small, there is a risk of contact between the substrate 1 and the die coater 10. Therefore, a larger coating gap H is preferable.

[0036] Preferably, the thickness h of the coating fluid layer 2 and the coating gap H in the coating step S1 satisfy the formula (2). 0.30≦h / H≦1.00 (2) Here, the thickness of the coating fluid layer 2 is substituted for h in equation (2) in μm, and the coating gap in the coating step S1 is substituted for H in equation (2) in μm.

[0037] Fn3 is defined as h / H. Fn3 is an index of the stability of coating of the coating liquid in the coating step S1. As described above, in this embodiment, the coating liquid layer 2 is formed as thin as 5 to 40 μm. Therefore, from a fluid dynamics perspective, the coating gap H is likely to be small. As a result, in the coating step S1 of this embodiment, there is a concern about contact between the substrate 1 and the die coater 10. On the other hand, when Fn3 is small, the coating gap H is large relative to the thickness h of the coating liquid layer 2. In this case, the coating liquid can be applied relatively stably.

[0038] Therefore, in the coating step S1 according to this embodiment, Fn3 is preferably 1.00 or less. On the other hand, in the coating step S1 according to this embodiment, the substantial lower limit of Fn3 is 0.30. Therefore, in the coating step S1 according to this embodiment, Fn3 is preferably 0.30 to 1.00.

[0039] In this embodiment, the coating gap H is determined as a value at which the bead 3 is stably formed. Therefore, there is no particular upper limit to the coating gap H. In this embodiment, the coating gap H is, for example, 100 μm or less. On the other hand, as described above, if the coating gap H is too small, there is a concern that the substrate 1 may come into contact with the die coater 10. Therefore, in this embodiment, the coating gap H is preferably 10 to 100 μm.

[0040] [Method for measuring coating gap H] In this embodiment, the coating gap H is measured by the following method. Specifically, before carrying out the coating step S1, a plastic gauge is sandwiched between the support member of the substrate 1 (backup roll 20 in FIG. 2) and the tip end (first surfaces 111 and 121) of the die coater 10, and the gap is measured. Furthermore, the support member of the die coater 10 is adjusted to fine-tune the gap between the substrate 1 and the die coater 10. The fine-tuned displacement is added to the gap measured by the plastic gauge, and the coating gap H (μm) is defined as the value obtained by rounding off the first decimal place.

[0041] [Air-liquid interface downstream of coating] Preferably, in the coating step S1 according to this embodiment, the interface of the coating liquid is positioned at the boundary between the first surface 121 of the second die 12 and the second surface 122 of the second die 12. As described above, if the width W of the slot 15 is smaller than Fn1, the discharge pressure of the coating liquid becomes too high. In this case, the gas-liquid interface of the coating liquid on the downstream side of the coating process moves toward the upstream side of the coating process and is positioned on the first surface 121 of the second die 12. As a result, streaky unevenness may be formed on the surface of the coating liquid layer 2.

[0042] Furthermore, in this embodiment, because the coating gap H is small, the gas-liquid interface of the coating fluid on the downstream side of the coating process may move toward the downstream side of the coating process and be positioned on the second surface 122 of the second die 12. In this case, the bead 3 may not be formed, and the coating fluid layer 2 may not be formed. Therefore, in the coating step S1 according to this embodiment, it is preferable that the interface of the coating fluid be positioned at the boundary between the first surface 121 of the second die 12 and the second surface 122 of the second die 12.

[0043] More preferably, the angle formed between the first surface 121 of the second die 12 and the second surface 122 of the second die 12 is 30 to 110° to prevent the gas-liquid interface of the coating fluid on the downstream side from migrating toward the coating downstream side.Alternatively, more preferably, the second surface 122 of the second die 12 is subjected to a liquid-repellent treatment to prevent the gas-liquid interface of the coating fluid on the downstream side from migrating toward the coating downstream side.

[0044] When the angle between the first surface 121 and the second surface 122 of the second die 12 is 30 to 110°, the surface tension of the coating liquid makes it difficult for the gas-liquid interface of the coating liquid downstream to move downstream in the coating direction. As a result, the interface of the coating liquid is stably positioned at the boundary between the first surface 121 of the second die 12 and the second surface 122 of the second die 12. Therefore, it is more preferable that the angle between the first surface 121 and the second surface 122 of the second die 12 is 30 to 110°.

[0045] Specifically, Fig. 4 is a partial cross-sectional view showing another example of the region 100 in Fig. 2 shown in Fig. 3. In Fig. 4, the angle between the first surface 121 and the second surface 122 of the second die 12 is 90°. Alternatively, as shown in Fig. 4, the angle between the first surface 121 and the second surface 122 may be set to 30 to 110° by cutting and removing a portion of the tip of the second die 12. Alternatively, the angle between the first surface 121 and the second surface 122 of the entire shape of the second die 12 may be set to 30 to 110°. However, when the angle between the first surface 121 and the second surface 122 is set to 30 to 110° by cutting and removing a portion of the tip of the second die 12, it is possible to prevent the gas-liquid interface of the coating liquid on the downstream side of the coating process from moving toward the downstream side of the coating process without changing the overall shape of the die coater 10.

[0046] In the second die 12, a more preferable upper limit of the angle between the first surface 121 and the second surface 122 is 100°, more preferably 95°, and even more preferably 90°. From the viewpoint of processability, a more preferable lower limit of the angle between the first surface 121 and the second surface 122 in the second die 12 is 60°, more preferably 80°, and even more preferably 85°.

[0047] 4 has a plurality of surfaces facing the substrate 1. In this case, as described above, the surface of the second die 12 facing the substrate 1 that is closest to the substrate 1 is referred to as the first surface 121.

[0048] Furthermore, when the second surface 122 of the second die 12 is subjected to a liquid-repellent treatment, the wettability of the second surface 122 is reduced, and the gas-liquid interface of the coating liquid downstream of the coating process is less likely to move downstream of the coating process. As a result, the interface of the coating liquid is stably located at the boundary between the first surface 121 of the second die 12 and the second surface 122 of the second die 12. Therefore, it is more preferable to perform a liquid-repellent treatment on the second surface 122 of the second die 12. The liquid-repellent treatment is not particularly limited, and may be any treatment that reduces wettability with the coating liquid. An example of a liquid-repellent treatment is a coating with a fluororesin.

[0049] [Regarding the atmospheric pressure near the tip of the first die 11] More preferably, in the coating step S1, the atmospheric pressure above the substrate 1 near the tip of the first die 11 is reduced by 0.1 to 0.8 kPa from atmospheric pressure. In this case, the gas-liquid interface of the coating liquid on the upstream side of the coating process moves toward the upstream side of the coating process. As a result, the bead 3 becomes more stable, and Fn3 can be further reduced. Therefore, in the coating step S1 according to this embodiment, it is more preferable to reduce the atmospheric pressure above the substrate 1 near the tip of the first die 11 by 0.1 to 0.8 kPa from atmospheric pressure.

[0050] 5 is a partial cross-sectional view showing another example of region 100 in FIG. 2, as shown in FIGS. 3 and 4. Comparing FIGS. 3 and 5, in FIG. 5, a vacuum chamber 16 is formed near the tip of first die 11. In FIG. 5, the vacuum chamber 16 is further depressurized by a decompression device (not shown). As a result, the atmospheric pressure inside vacuum chamber 16 is reduced by 0.1 to 0.8 kPa from atmospheric pressure. As a result, the gas-liquid interface of the coating liquid on the upstream side of coating has shifted toward the upstream side of coating in FIG. 5 compared to FIG. 3.

[0051] Note that the ambient pressure above the substrate 1 near the tip of the first die 11 may be reduced from atmospheric pressure by 0.1 to 0.8 kPa using a method other than the method shown in FIG. 5 . Even in this case, the above-described effect of stabilizing the bead 3 and further reducing Fn3 can be obtained. Note that when a vacuum chamber 16 is formed to reduce the ambient pressure above the substrate 1, the ambient pressure inside the vacuum chamber 16 can be measured using a pressure gauge disposed inside the vacuum chamber 16. Any known pressure gauge can be used as the pressure gauge. For example, a Bourdon tube type pressure gauge can be disposed inside the vacuum chamber 16 and used.

[0052] [Drying process S2] 1, the method for producing a laminate according to this embodiment may include a drying step S2 after the coating step S1 and before the thin film layer forming step S3. In the drying step S2, the coating fluid layer 2 is dried to volatilize the solvent component contained in the coating fluid layer 2. In this case, the coating fluid layer 2 can be efficiently cured in the thin film layer forming step S3 described below.

[0053] On the other hand, as described above, the drying step S2 is an optional step in the laminate manufacturing method according to the present embodiment. Specifically, for example, when the coating liquid layer 2 does not contain a solvent, the thin film layer forming step S3 can be performed without performing the drying step S2.

[0054] [Thin film layer formation process S3] In the thin film layer forming step S3, the coating fluid layer 2 is cured to form a thin film layer, thereby producing a laminate. The method for curing the coating fluid layer 2 is not particularly limited and can be selected appropriately depending on the type of coating fluid. For example, in the case of a coating fluid containing a polymerizable compound, the coating fluid layer 2 may be cured by promoting polymerization through heating. Alternatively, the coating fluid layer 2 may be cured by other methods.

[0055] A laminate is manufactured through the above steps. Hereinafter, this embodiment will be described in more detail using examples. Note that the examples described below are examples for explaining this embodiment, and the method for manufacturing a laminate according to this embodiment is not limited to the examples described below. [Example]

[0056] In the examples, copper foil was used as the substrate. A polyamic acid solution was used as the coating liquid. In these examples, a coating liquid layer was formed on the surface of the substrate using a roll-to-roll method. The viscosity μ (Pa·s) of the coating liquid for each test number is shown in Table 1. Furthermore, Fn1 (= 0.01μ + 0.08) and Fn2 (= 0.06μ + 0.2), which were calculated from the viscosity μ of the coating liquid, are also shown in Table 1.

[0057] [Table 1]

[0058] Furthermore, the slot width W (mm) of the die coater used for each test number is shown in Table 1. For the second die of the die coater used for each test number, if the angle between the first and second surfaces is 90°, it is indicated as "A" in the "Tip shape" column of the "Second surface of the second die" column in Table 1. On the other hand, for the second die of the die coater used for each test number, if the angle between the first and second surfaces is 135°, it is indicated as "B" in the "Tip shape" column of the "Second surface of the second die" column in Table 1.

[0059] Furthermore, for the second die of the die coater used for each test number, if a fluororesin coating was applied as a liquid-repellent treatment to the second surface, this is indicated as "A" in the "Liquid-repellent treatment" column of the "Second surface of the second die" column in Table 1. On the other hand, for the second die of the die coater used for each test number, if a liquid-repellent treatment was not applied to the second surface, this is indicated as "B" in the "Liquid-repellent treatment" column of the "Second surface of the second die" column in Table 1.

[0060] Furthermore, a vacuum chamber was installed in the die coater used for each test number. For test numbers in which the vacuum chamber was depressurized, the degree of depressurization from atmospheric pressure is shown in the "Upstream side depressurization degree (kPa)" column in Table 2. On the other hand, for test numbers in which the vacuum chamber was not depressurized, a "-" is shown in the "Upstream side depressurization degree (kPa)" column in Table 2.

[0061] [Table 2]

[0062] Under the above conditions, the coating gap H was adjusted so as to form a bead, and a coating liquid layer was formed. The coating gap H for each test number is shown in Table 2. The coating gap H was measured using the method described above. Note that for test number 12, the coating liquid wetted the second surface of the second die, and the coating liquid was not applied to the substrate.

[0063] Furthermore, the thickness h of the formed coating liquid layer was measured using the method described above. The thickness h of the formed coating liquid layer for each test number is shown in Table 2. Furthermore, Fn3 (= h / H) was calculated from the coating gap H and the thickness h of the coating liquid layer for each test number. The obtained Fn3 for each test number is shown in Table 2.

[0064] [Evaluation of coating liquid layer] In this example, instead of evaluating the uniformity of the thin film layer, the coating liquid layer formed on the surface of the substrate was evaluated visually. This is because an unevenly formed coating liquid layer would also affect the thin film layer after curing. Specifically, for each substrate with a test number on which a coating liquid layer was formed, a 100 mm × 100 mm area was identified from an arbitrary position. The identified area was visually inspected for the presence or absence of streak-like defects having a width of 0.5 mm or more. If the visual inspection revealed zero or one streak-like defect having a width of 0.5 mm or more, the coating liquid layer was determined to be uniformly formed ("E (Excellent)" in Table 2). On the other hand, if the visual inspection revealed two or more streak-like defects having a width of 0.5 mm or more, the coating liquid layer was determined to be not uniformly formed ("NA (Not Acceptable)" in Table 2).

[0065] Furthermore, the coating liquid layer formed on the surface of the substrate was cured in a far-infrared heating furnace. By the above method, laminates of each test number were produced.

[0066] [Evaluation results] Referring to Tables 1 and 2, for the laminates of test numbers 1 to 11, the slot width W of the die coater during the coating process satisfied Fn1 to Fn2. As a result, for these laminates, even though the viscosity μ of the coating fluid was high, ranging from 1 to 30 Pa·s, the thickness h of the coating fluid layer was 5 to 40 μm, and the coating fluid layer was formed uniformly. In other words, the thin film layer after curing was also formed uniformly.

[0067] On the other hand, in the laminate of test number 12, the coating liquid wetted onto the second surface of the second die, and as a result, the thickness h of the coating liquid layer did not reach 5 to 40 μm.

[0068] The slot width W of the die coater for the laminate of test number 13 was less than Fn1. As a result, the coating liquid layer was not formed uniformly, and the thin film layer after curing was also not formed uniformly.

[0069] The embodiments of the present disclosure have been described above. However, the above-described embodiments are merely examples for implementing the present disclosure. Therefore, the present disclosure is not limited to the above-described embodiments, and can be implemented by appropriately modifying the above-described embodiments within the scope of the present disclosure. [Explanation of symbols]

[0070] 1 Base material 2 Coating liquid layer 3 beads 10 Die Coater 11 First Die 12 Second Die 121 First Side 122 Second Side 123 Third Side 13 Shim plate 14 Manifold 15 slots 16 Vacuum Chamber 20 Backup Roll

Claims

1. A method for manufacturing a laminate including a substrate and a thin film layer formed on the substrate, comprising: a coating step of applying a coating liquid onto a surface of the substrate using a die coater to form a coating liquid layer; and a thin film layer forming step of curing the coating liquid layer to form the thin film layer, The viscosity μ of the coating liquid is 1 to 30 Pa s, The thickness h of the coating liquid layer is 5 to 40 μm, The viscosity μ of the coating liquid and the width W of the slot of the die coater satisfy the formula (1). A method for manufacturing a laminate. 0.01μ+0.08≦W≦0.06μ+0.2 (1) Here, the viscosity of the coating liquid is substituted for μ in the formula (1) in units of Pa·s, and the slot width of the die coater is substituted for W in the formula (1) in units of mm.

2. A method for producing the laminate according to claim 1, the thickness h of the coating liquid layer and the coating gap H in the coating step satisfy formula (2). A method for manufacturing a laminate. 0.30≦h / H≦1.00 (2) Here, the thickness of the coating liquid layer is substituted for h in equation (2) in the unit of μm, and the coating gap in the coating step is substituted for H in equation (2) in the unit of μm.

3. A method for producing the laminate according to claim 1, the die coater includes a first die and a second die that are arranged in a direction in which the substrate moves relative to the die coater; In the second die, a first surface facing the substrate, the first surface being closest to the substrate; a second surface adjacent to the first surface and forming an angle with the first surface, on the downstream side of the direction in which the substrate moves relative to the die coater, In the coating step, an interface of the coating liquid is disposed at the boundary between the first surface and the second surface. A method for manufacturing a laminate.

4. A method for producing the laminate according to claim 3, an angle formed between the first surface of the second die and the second surface of the second die satisfies 30 to 110 degrees; A method for manufacturing a laminate.

5. A method for producing the laminate according to claim 3, The second surface of the second die is subjected to a liquid-repellent treatment. A method for manufacturing a laminate.

6. A method for producing the laminate according to claim 1, In the coating step, The atmospheric pressure above the substrate in the vicinity of the tip of the first die is reduced by 0.1 to 0.8 kPa from atmospheric pressure. A method for manufacturing a laminate.

7. A method for producing the laminate according to claim 1, In the coating step, the substrate is transported and the coating liquid layer is formed. A method for manufacturing a laminate.

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