Method for producing laminated body

Abstract

A method for manufacturing a laminated body comprises the following steps: for a continuously conveyed substrate, a first coating liquid is initially applied to a first surface of the substrate, and before a widthwise end portion of the substrate on which a first coating liquid film formed by the first coating liquid is displaced, a second coating liquid is initially applied to a second surface of the substrate opposite to the first surface, wherein the displacement between the width of the first coating liquid film on the first surface and the width of the second coating liquid film formed by the second coating liquid on the second surface is within 1 mm.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a laminated body. Background Art

[0002] In a roll-to-roll continuous process, there is known a method for producing a laminated body in which a target film is formed on both sides of a strip-shaped substrate (i.e., a first side and a second side opposite to the first side) and arranged in the order of film, substrate, and film.

[0003] In addition, as a method for producing a laminated body, for example, there is a method of applying a coating liquid for obtaining a target film on a substrate and drying the obtained coating liquid film.

[0004] As an example of a method for manufacturing a laminate, Japanese Patent Gazette No. 2004-344693 discloses a sequential coating method for performing coating and drying steps on both sides of a support, wherein a coating liquid is coated on the surface of a traveling belt-shaped plastic support, and the coated coating film is dried at a temperature substantially above the glass transition point temperature of the support.

[0005] In addition, Japanese Patent Gazette No. 2-119968 discloses a method in which a coating liquid is applied to a first surface of a substrate, the coating liquid applied to the first surface is cooled to promote gelation, the first surface (i.e., the coating surface) is floated and supported by a gas jet, and the coating liquid is applied to a second surface (the surface opposite to the first surface) in a continuous state. Summary of the invention

[0006] Technical issues to be solved by the invention

[0007] For example, as described in Japanese Patent Application Laid-Open No. 2004-344693, there is a method for manufacturing a laminate, in which a coating liquid is applied to the first surface of a continuously conveyed substrate, and after the formed coating liquid film is dried, the coating liquid is applied to the second surface opposite to the first surface of the substrate, and the formed coating liquid film is dried. In this case, curling sometimes occurs at the width direction end of the substrate at the stage of drying the coating liquid film formed on the first surface.

[0008] Furthermore, as described in Japanese Patent Application Laid-Open No. 2-119968, even in the case of a method for manufacturing a laminated body in which a coating liquid is applied to the first surface of a substrate and the formed coating liquid film is gelled, and then the coating liquid is applied to the second surface opposite to the first surface of the substrate, curling sometimes occurs at the width direction end of the substrate during the gelation process inside the coating liquid film formed on the first surface.

[0009] The curling generated as described above may also impair the planarity of the substrate, and may cause problems in conveying the substrate, applying the coating liquid to the second surface, and the like.

[0010] Therefore, the problem to be solved by one embodiment of the present invention is to provide a method for manufacturing a laminate, which forms a film on both sides of a continuously conveyed substrate, and in the method for manufacturing a laminate, the curling of the width direction ends of the substrate generated in the process of forming the film on both sides of the substrate can be reduced.

[0011] Means for solving technical problems

[0012] Means for solving the above-mentioned problems include the following embodiments.

[0013] <1> A method for producing a laminate, comprising the following steps:

[0014] For a continuously conveyed substrate, a first coating liquid is applied to a first surface of the substrate, and before a widthwise end portion of the substrate on which a first coating liquid film formed by the first coating liquid is displaced, a second coating liquid is applied to a second surface of the substrate opposite to the first surface.

[0015] The misalignment amount between the width of the first coating liquid film on the first surface and the width of the second coating liquid film formed by the second coating liquid on the second surface is within 1 mm.

[0016] <2> The method for producing a laminate according to <1>, wherein:

[0017] The thickness of the substrate is 5 μm or more and 80 μm or less.

[0018] <3> The method for producing a laminate according to <1> or <2>, wherein:

[0019] The film thickness of the first coating liquid film and the second coating liquid film is 40 μm or more.

[0020] <4> The method for producing a laminate according to any one of <1> to <3>, wherein

[0021] The second coating liquid is applied to the second surface of the substrate opposite to the first surface until the solid content concentration of the first coating liquid film reaches 70% by mass.

[0022] <5> The method for producing a laminate according to any one of <1> to <4>, wherein

[0023] While the solid content concentration of the first coating liquid film is 55 mass % or more and 70 mass % or less, the second coating liquid is started to be applied to the second surface opposite to the first surface of the substrate.

[0024] <6> The method for producing a laminate according to any one of <1> to <5>, wherein

[0025] The second coating liquid was applied using an extrusion coater.

[0026] Effects of the Invention

[0027] According to one embodiment of the present invention, a method for manufacturing a laminate is provided, wherein a film is formed on both sides of a continuously conveyed substrate, and in the method for manufacturing a laminate, curling of the width direction ends of the substrate generated during the process of forming the film on both sides of the substrate can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram for explaining each step of the method for producing a laminated body according to one embodiment.

[0029] Figure 2 It is a schematic cross-sectional view for explaining displacement of the width direction end portion of the substrate. DETAILED DESCRIPTION

[0030] Hereinafter, an embodiment of a method for producing a laminate will be described. However, the present invention is not limited to the following embodiment at all, and can be implemented with appropriate modifications within the scope of the purpose of the present invention.

[0031] In the present invention, a numerical range expressed by "to" means a range including the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively.

[0032] In the numerical ranges recorded in stages in the present invention, the upper limit or lower limit recorded in a certain numerical range can be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical ranges recorded in the present invention, the upper limit or lower limit recorded in a certain numerical range can also be replaced by the value shown in the embodiment.

[0033] Each element in each drawing shown in the present invention is not necessarily to exact scale, but the focus is on clearly illustrating the principle of the present invention, and there are also emphasized portions.

[0034] In addition, in each drawing, the same reference numerals are given to components having the same function, and duplicate descriptions are omitted.

[0035] In the present invention, the "substrate" refers to a substrate that is continuously conveyed and has a belt-like shape.

[0036] In the present invention, the "width direction" refers to a direction orthogonal to any longitudinal direction (ie, conveyance direction) of a continuously conveyed substrate (ie, a belt-shaped substrate), a coating liquid film, and a film.

[0037] In the present invention, the "first surface" of the substrate is one surface of the strip-shaped substrate, and unless otherwise specified, it refers to the surface on which the coating liquid is first applied. Furthermore, the "second surface" of the substrate is the other surface of the strip-shaped substrate, that is, the surface opposite to the first surface, and unless otherwise specified, it refers to the surface on which the coating liquid is applied later.

[0038] In the present invention, a combination of two or more preferred aspects or configurations is a more preferred aspect or configuration.

[0039] 《Method for producing laminated body》

[0040] As described above, in a method for manufacturing a laminated body in which a coating liquid is applied to the first surface of a continuously transported substrate and the formed coating liquid film is dried (specifically, after the constant-speed drying and deceleration drying of the coating liquid film are completed), the coating liquid is applied to the second surface opposite to the first surface of the substrate and the formed coating liquid film is dried, and in the drying stage of the coating liquid film formed on the first surface, curling sometimes occurs at the width direction end of the substrate. If curling occurs at the width direction end of the substrate at this stage, the substrate is wrinkled and bent, which damages the flatness of the substrate or the substrate is cut, and sometimes the transportation of the substrate is problematic. In addition, if curling occurs at the width direction end of the substrate at the above stage, it becomes difficult to apply the coating liquid with a uniform thickness along the width direction when applying the coating liquid to the second surface.

[0041] Therefore, the inventors of the present invention have discovered that, for a continuously conveyed substrate, by controlling the timing of starting to apply the coating liquid to the second surface after starting to apply the coating liquid to the first surface of the substrate, the curling generated during the drying stage of the coating liquid film formed on the first surface can be reduced, thereby completing the method for manufacturing the laminate involved in this embodiment.

[0042] A method for manufacturing a laminated body involved in the present embodiment is a method for manufacturing a laminated body having the following steps: for a continuously conveyed substrate, a first coating liquid is first applied to the first surface of the substrate, and before the width-direction end portion of the substrate on which a first coating liquid film formed by the first coating liquid is formed is displaced, a second coating liquid is first applied to the second surface opposite to the first surface of the substrate, and the misalignment amount between the width of the first coating liquid film on the first surface and the width of the second coating liquid film formed by the second coating liquid on the second surface is within 1 mm.

[0043] According to the method for producing a laminated body according to the present embodiment, it is possible to obtain a laminated body in which a film formed on the first surface side of a substrate, a substrate, and a film formed on the second surface side of the substrate are arranged in this order.

[0044] According to the method for producing a laminated body according to the present embodiment, it is considered that curling of the width direction end portions of the substrate generated in the process of forming films on both surfaces of the substrate can be reduced by the mechanism described below.

[0045] That is, in the manufacturing method of the laminated body involved in the present embodiment, before the width direction end of the substrate formed with the first coating liquid film formed by the first coating liquid is displaced, the second surface of the substrate begins to be coated with the second coating liquid. In this way, the second coating liquid can be coated on the second surface while the substrate is stably transported and the planarity of the substrate is not damaged. As a result, in the manufacturing method of the laminated body involved in the present embodiment, when the second coating liquid is coated on the second surface, the coating liquid can be coated with a uniform thickness along the width direction to the set area of ​​the second surface. In this way, since the coating accuracy of the second coating liquid on the second surface is improved, the misalignment amount (i.e., within 1 mm) of the width of the coating liquid film formed on the first surface and the width of the coating liquid film formed on the second surface can be reduced.

[0046] Then, by setting the offset amount to within 1 mm, the force that will curl toward the first surface due to the shrinkage caused by the drying of the first coating liquid film and the force that will curl toward the second surface due to the shrinkage caused by the drying of the second coating liquid film can be balanced and well offset with the substrate as the center. As a result, in the process of applying the coating liquid to both sides of the substrate and drying it to form a film, it becomes difficult to curl at the width direction end of the substrate.

[0047] On the other hand, in the method described in Japanese Patent Application Laid-Open No. 2004-344693, it is believed that the coating liquid film formed on the first surface of the substrate starts to be coated on the second surface of the substrate after drying, so that curling occurs at the width direction end of the substrate at the stage of starting coating on the second surface.

[0048] In addition, in the method described in Japanese Patent Application Laid-Open No. 2-119968, after the coating liquid film formed on the first surface of the substrate is gelled, coating on the second surface of the substrate is started. In this method, there are problems such as curling caused by gelation inside the coating liquid film is easily caused during the gelation of the coating liquid film, and the gelation process is very long, so the misalignment amount between the width of the first coating liquid film on the first surface and the width of the second coating liquid film on the second surface becomes large.

[0049] Hereinafter, each step of the method for producing the laminated body according to the present embodiment will be described.

[0050] First, regarding an example of a method for producing a laminate, refer to Figure 1 Here, Figure 1 It is a schematic diagram of an apparatus to which a method for producing a laminated body according to one embodiment is applied, and is used to explain each step.

[0051] like Figure 1 As shown, the belt-shaped substrate 10 wound into a roll shape starts to be conveyed by sending out its front end in the direction of the arrow, and is continuously conveyed until it is wound into a roll shape.

[0052] like Figure 1 As shown, in the area where the substrate 10 is wound around the support roller 20, the first coating liquid is applied to the first surface of the substrate 10 by the coating mechanism 30 (hereinafter also referred to as step A). ​​By step A, a first coating liquid film (not shown) composed of the first coating liquid is formed on the first surface of the strip-shaped substrate 10.

[0053] Next, the strip-shaped substrate 10 having the first coating liquid film (not shown) formed on the first surface is conveyed along the outer peripheral surface of the roller-shaped floating conveying mechanism 40 in a state not in contact with the surface on the first surface side (i.e., in a state not in contact with the first coating liquid film). Then, in the area where the strip-shaped substrate 10 is conveyed by the floating conveying mechanism 40, the second coating liquid is applied to the second surface of the substrate 10 by the coating mechanism 50 (hereinafter also referred to as step B). By step B, a second coating liquid film (not shown) made of the second coating liquid is formed on the second surface of the strip-shaped substrate 10.

[0054] Next, after the second coating liquid film is formed on the second surface, the strip-shaped substrate 10 passes through a drying mechanism 60 (hereinafter, also referred to as step C). The first coating liquid film on the first surface and the second coating liquid film on the second surface of the strip-shaped substrate 10 are dried by step C, and films are formed on both surfaces of the substrate 10.

[0055] Then, the base material 10 having passed through the drying mechanism 60 is wound into a roll shape after going through an arbitrary step (not shown) as necessary.

[0056] [Step A]

[0057] In step A, the first coating liquid is initially applied to the first surface of the substrate which is continuously conveyed.

[0058] The substrate used in this step is not particularly limited as long as it can be continuously transported, and a substrate may be selected in accordance with the application of the laminate to be formed.

[0059] The substrate may be made of resin or metal, and may have a multilayer structure including a resin layer and a metal layer.

[0060] Furthermore, as the substrate, for example, a substrate having a thermal conductivity of 200 W / m·K or more can be used. As the substrate having a thermal conductivity of 200 W / m·K or more, for example, in the case of a substrate having a multilayer structure including a metal layer and a resin layer, the thermal conductivity of the substrate as a whole can be 200 W / m·K or more.

[0061] The upper limit of the thermal conductivity of the substrate is not particularly limited, and is, for example, 500 W / m·K.

[0062] Specific examples of the substrate having the above-mentioned thermal conductivity include copper, aluminum, silver, gold, and metal substrates based on alloys thereof.

[0063] Among them, from the viewpoints of shape stability as a substrate, practical use, and the like, a copper substrate and an aluminum substrate are preferably used.

[0064] The thermal conductivity of the substrate was measured in the following manner.

[0065] First, the substrate is cut into a size suitable for the device described later to obtain a sample for measurement. For the obtained sample for measurement, the thermal diffusion coefficient in the thickness direction is measured by the laser flash method. Next, the specific gravity of the sample for measurement is measured by a balance using a specific gravity measurement kit. In addition, the specific heat of the sample for measurement at 25°C is used to obtain the thermal conductivity of the sample for measurement (i.e., the substrate) by multiplying the obtained thermal diffusion coefficient by the specific gravity and specific heat.

[0066] Here, when measuring the thermal diffusion coefficient, for example, "LFA467" of NETZSCH is used. When measuring the specific gravity, for example, a balance "XS204" of Mettler-Toledo International Inc. using a solid specific gravity measurement kit is used. When measuring the specific heat, for example, "DSC320 / 6200" of Seiko Instruments Inc. is used.

[0067] From the viewpoint of suitability for a roll-to-roll method, the thickness of the substrate may be appropriately set.

[0068] The thickness of the substrate is, for example, preferably 5 μm to 100 μm, more preferably 5 μm to 80 μm, and even more preferably 10 μm to 30 μm.

[0069] Even if the thickness of the substrate is thin as described above and the width direction end portions of the substrate are easily displaced during the drying stage of the coating liquid film, the method for producing a laminated body according to the present embodiment can reduce curling.

[0070] From the viewpoint of suitability for a roll-to-roll method and from the perspective of the desired film width and length, the width and length of the substrate may be appropriately set.

[0071] The thickness of the substrate is measured in the following manner.

[0072] Specifically, the thickness of the substrate was measured at three locations in the width direction (specifically, 5 mm from both edges in the width direction and the center in the width direction) at intervals of 500 mm in the longitudinal direction using a contact thickness gauge.

[0073] The arithmetic mean of the 9 measured values ​​was calculated and used as the thickness of the substrate.

[0074] As the contact-type thickness measuring machine, for example, S-2270 from Fujiwork Co., Ltd. is used.

[0075] -First coating liquid-

[0076] The first coating liquid used in this step is not particularly limited as long as it is a liquid containing a solvent (or a dispersion medium) and has fluidity and can form a target film.

[0077] The first coating liquid may use an organic solvent or water as a solvent (or dispersion medium).

[0078] As the first coating liquid, for example, it can be an aqueous coating liquid in which the solvent (or dispersion medium) contained in the coating liquid is substantially water. "The solvent (or dispersion medium) is substantially water" means that when preparing the coating liquid, it is allowed to contain solvents other than water introduced when using solid components. Specifically, "the solvent (or dispersion medium) is substantially water" means that the proportion of water in all solvents (or all dispersion media) is 90% by mass or more, and the proportion of water in all solvents (or all dispersion media) is preferably 95% by mass or more, and it is particularly preferred that all solvents (or all dispersion media) are water.

[0079] Furthermore, the solid content refers to components other than the solvent (or dispersion medium).

[0080] The aqueous coating liquid is not particularly limited as long as it is a liquid containing water as a solvent (or dispersion medium) and a solid component.

[0081] The solid content contained in the water-based coating liquid includes, in addition to components for obtaining the target film, components for improving coating suitability and the like.

[0082] Examples of water contained in the aqueous coating liquid include natural water, purified water, distilled water, ion exchanged water, pure water, ultrapure water (e.g., Milli-Q water), etc. In addition, Milli-Q water refers to ultrapure water obtained by a Milli-Q water production device of Merck KGaA.

[0083] The content of water in the aqueous coating liquid is not particularly limited, but is, for example, preferably 40% by mass or more, and more preferably 50% by mass or more, relative to the total mass of the aqueous coating liquid.

[0084] The upper limit of the water content may be less than 100% by mass, and is, for example, 90% by mass with respect to the total mass of the aqueous coating liquid from the viewpoint of coating suitability.

[0085] The water-based coating liquid may contain particles as one of the solid components. That is, the water-based coating liquid may be a coating liquid containing particles.

[0086] When an aqueous coating liquid containing particles is used, the particles also flocculate during the drying stage, which tends to easily cause displacement of the widthwise end of the substrate. In the method for manufacturing a laminated body according to the present embodiment, even when an aqueous coating liquid containing particles is used as the first coating liquid, curling of the widthwise end of the substrate can be reduced.

[0087] The particles are not particularly limited as long as they are particulate materials, and may be inorganic particles, organic particles, or composite particles of inorganic and organic materials.

[0088] As the inorganic particles, known inorganic particles that can be suitably used in the target film can be used.

[0089] Examples of inorganic particles include particles of metals (alkali metals, alkaline earth metals, transition metals, alloys of these metals, etc.), particles of semimetals (silicon, etc.), particles of compounds containing metals or semimetals (oxides, hydroxides, nitrides, etc.), inorganic pigments containing carbon black, etc., and the like.

[0090] Inorganic particles include particles of minerals such as mica.

[0091] As the organic particles, known organic particles that can be suitably used in the target film can be used.

[0092] The organic particles are not particularly limited as long as they are particles of solid organic matter such as resin particles and organic pigments.

[0093] Examples of composite particles of an inorganic substance and an organic substance include composite particles in which inorganic particles are dispersed in a matrix of an organic substance, composite particles in which organic particles are coated with an inorganic substance, and composite particles in which inorganic particles are coated with an organic substance.

[0094] The particles may be surface treated for the purpose of imparting dispersibility or the like.

[0095] In addition, the particles may be subjected to surface treatment to form the above-mentioned composite particles.

[0096] The particle size, shape, specific gravity, and usage (for example, whether to use in combination) of the particles are not particularly limited and may be appropriately selected according to the target film or conditions suitable for film production.

[0097] The content of the particles in the water-based coating liquid is not particularly limited and may be appropriately determined depending on the target film, conditions suitable for producing the film, or the purpose of adding the particles.

[0098] The solid content contained in the water-based coating liquid is not particularly limited, and various components used to obtain a target film may be mentioned.

[0099] Specifically, the solid components contained in the aqueous coating liquid include, in addition to the above-mentioned particles, binder components, components that contribute to the dispersibility of the particles, polymerizable compounds, reactive components such as polymerization initiators, components for improving coating performance such as surfactants, and other additives.

[0100] -Thickness of the first coating liquid film-

[0101] The thickness of the first coating liquid film formed in this step is not particularly limited and may be appropriately determined depending on the target film.

[0102] The thickness of the first coating liquid film is, for example, preferably 40 μm or more, more preferably 40 μm to 200 μm, and further preferably 40 μm to 100 μm.

[0103] The thicker the first coating liquid film becomes, the more likely it is that the end portions in the width direction of the substrate will be displaced during the drying stage of the first coating liquid film. In the method for manufacturing the laminated body according to the present embodiment, even when the first coating liquid film becomes thicker, the curling of the end portions in the width direction of the substrate can be reduced.

[0104] The thickness of the coating liquid film was measured in the following manner.

[0105] Specifically, the first coating film was measured at three locations along the width direction (specifically, 5 mm from both edges in the width direction and the center in the width direction) using an optical interference thickness meter. The arithmetic mean of the measured values ​​at the three points was calculated and used as the coating film thickness.

[0106] As the optical interference type thickness measuring instrument, for example, an infrared spectroscopic interference type film thickness meter SI-T80 manufactured by KEYENCE CORPORATION is used.

[0107] -Width of coating film-

[0108] The width of the first coating liquid film in this step (ie, coating width) is not particularly limited and may be determined according to the width of the substrate, the application of the film, and the like.

[0109] The width of the first coating liquid film can be selected to be, for example, 100 mm or more, or 1000 mm or more.

[0110] The upper limit of the width of the first coating liquid film is the width of the substrate.

[0111] -Width of non-coated area-

[0112] When the first coating liquid film is formed on the first surface of the substrate, from the viewpoint of facilitating the effect of the method for manufacturing the laminate involved in the present embodiment, the width of the non-coated area at both ends in the width direction of the substrate (i.e., the width of the exposed portion of the substrate) is, for example, preferably greater than 2 mm, and more preferably greater than 5 mm.

[0113] The upper limit of the width of the non-coated region on the first surface depends on the width of the substrate, but is preferably 30 mm, for example.

[0114] The width of the coating liquid film is measured in the following manner.

[0115] That is, the upper surface of the coating liquid film was observed from the film surface side, and the width of the coating liquid film was measured at three points at intervals of 500 mm in the longitudinal direction using a ruler.

[0116] The arithmetic mean of the values ​​measured at the three points was calculated and used as the width of the coating liquid film.

[0117] Then, the width of the coated area was measured as follows.

[0118] That is, the top surface is observed from the film surface side of the coating film, and the shortest distance from the end of the width direction of the substrate to the end of the coating film is measured at three points with an interval of 500 mm in the length direction using a ruler. The measurement is performed at both ends of the width direction of the substrate.

[0119] The arithmetic mean of the measured values ​​at the six points was calculated and used as the width of the coated area.

[0120] - Application of the first coating liquid -

[0121] A known coating mechanism is applied to the coating of the first coating liquid in this step.

[0122] As a coating mechanism (e.g. Figure 1 The coating mechanism 30) in the method may specifically include coating devices utilizing curtain coating, dip coating, printing coating, spray coating, slit coating, roller coating, slide coating, blade coating, gravure coating, wire rod coating, and the like.

[0123] Among them, as the coating mechanism in this step, from the viewpoint of achieving high-definition coating, it is preferable to use a coating device using a slit coating method, more specifically, an extrusion coater.

[0124] -Support Roller-

[0125] In this step, when applying the first coating liquid, the substrate can be conveyed in a stretched state. From the viewpoint of improving the coating accuracy, Figure 1 As shown, this is preferably carried out in the region where the substrate is wound around the support roller.

[0126] The support roller is a rotatable member. When the support roller rotates, the substrate can be conveyed in a state of being stretched along the outer peripheral surface of the support roller.

[0127] From the viewpoint of controlling the drying process of the coating liquid film and suppressing blushing of the coating film due to a decrease in the film surface temperature of the coating liquid film (ie, whitening of the coating film due to the generation of fine condensation), the backup roll may be heated.

[0128] The surface temperature of the backup roller is preferably controlled by a temperature control mechanism. The surface temperature of the backup roller is more preferably controlled by a temperature control mechanism based on the detected surface temperature.

[0129] As the temperature control mechanism, for example, a heating mechanism and a cooling mechanism can be cited. In the heating mechanism, for example, induction heating, water heating or oil heating can be used. In the cooling mechanism, for example, cooling by cooling water is used.

[0130] The diameter of the backup roll is preferably 100 to 1,000 mm, more preferably 100 to 800 mm, and particularly preferably 200 to 700 mm, from the viewpoint of easy winding of the substrate, easy coating with a die, and the production cost of the backup roll.

[0131] From the viewpoint of productivity and coating properties, the conveyance speed of the substrate by the backup roll is preferably, for example, 10 m / min to 100 m / min.

[0132] From the viewpoint of stabilizing the substrate conveyance when applying the first coating liquid and suppressing the occurrence of uneven thickness of the coating liquid film, the wrap angle of the substrate relative to the support roller is preferably 60° or more, more preferably 90° or more. In addition, the upper limit of the wrap angle can be set to 180°, for example. The wrap angle refers to the angle formed by the conveyance direction of the substrate when the substrate is in contact with the support roller and the conveyance direction of the substrate when the substrate is separated from the support roller.

[0133] [Step B]

[0134] In step B, before the width direction end of the substrate on which the first coating liquid film formed by the first coating liquid is displaced, the second coating liquid is applied to the second surface opposite to the first surface of the substrate.

[0135] -Displacement of the end portion in the width direction of the substrate-

[0136] In this step, “displacement occurs at the width direction end portion of the substrate on which the first coating liquid film formed by the first coating liquid is formed” means that the displacement amount F of the width direction end portion of the substrate measured by the method described below is greater than 5 mm.

[0137] That is, in this step, the second coating liquid is applied to the second surface opposite to the first surface of the substrate until the displacement amount F of the width direction end of the substrate on which the first coating liquid film is formed reaches 5 mm.

[0138] Hereinafter, “the displacement amount F of the end portion in the width direction of the substrate on which the first coating liquid film formed of the first coating liquid is formed” is also simply referred to as “the displacement amount F”.

[0139] Regarding the measurement of the displacement F of the width direction end of the substrate, refer to Figure 2 Provide explanation.

[0140] Figure 2 This is a schematic diagram of a main part of a cross section when the base material is cut along the width direction.

[0141] like Figure 2 As shown, the floating amount of the end portion in the width direction of the substrate when the center portion of the substrate 10 on which the first coating liquid film is formed is used as a reference is measured with a ruler, and this is taken as the displacement amount F of the end portion in the width direction of the substrate.

[0142] In addition, the environmental conditions when the above-mentioned floating amount is measured are set to be the same as the environmental conditions when this step is performed.

[0143] When using existing equipment to perform this step, it is sufficient to appropriately adjust the pre-drying conditions, the coating speed of the first coating liquid (i.e., the conveying speed of the substrate) and the solid content concentration when the first coating liquid is adjusted (or coated) at the coating position of the second coating liquid onto the second surface so that the displacement F of the width direction end of the substrate on which the first coating liquid film formed by the first coating liquid is formed becomes less than 5 mm.

[0144] Here, the pre-drying refers to the drying of the first coating liquid film at a stage before the second coating liquid film is formed.

[0145] Furthermore, the timing for starting to apply the second coating liquid to the second surface of the substrate can be determined based on the position on the conveyance path where the displacement F reaches 5 mm during the drying process of the first coating liquid film formed on the first surface.

[0146] Specifically, by the above method, the displacement F is intermittently measured as the first coating liquid film formed on the first surface dries, and during the drying process of the first coating liquid film formed on the first surface, a position on the conveying path where the displacement F reaches 5 mm is determined (for example, Figure 1 Then, the second coating liquid is applied to the second surface at the determined position on the conveying path or upstream of the position in the conveying direction of the substrate. Figure 1 In the process, the coating mechanism 50 may be set at a position P on the determined conveying path or upstream of the position P in the conveying direction of the substrate 10 so as to start coating the second coating liquid onto the second surface.

[0147] Furthermore, the coating position of the second coating liquid onto the second surface can be fixed (for example, Figure 1 ), and changing the coating position of the first coating liquid to the first surface (for example, Figure 1 The coating mechanism 30 is set in the coating mechanism 30 in the coating mechanism 30, and the position on the conveying path is moved by a displacement amount F of 5 mm, thereby changing the position on the conveying path (for example, Figure 1 At position P) in the substrate or on the upstream side of the substrate conveying direction than this position, the second coating liquid starts to be applied to the second surface.

[0148] -Solid content concentration-

[0149] The second coating liquid is preferably applied to the second surface of the substrate until the solid content concentration of the first coating liquid film on the back surface, i.e., the first surface of the substrate, reaches 75% by mass, more preferably 70% by mass, and even more preferably 65% ​​by mass.

[0150] When the solid content concentration of the first coating liquid film formed on the first surface of the substrate is 75% by mass or less, the substrate is stably conveyed without damaging the planarity of the substrate, and the second coating liquid is easily coated with a uniform thickness in the width direction on the set area of ​​the second surface. As a result, the amount of misalignment between the width of the first coating liquid film formed on the first surface and the width of the second coating liquid film formed on the second surface can be further reduced.

[0151] The timing for starting to apply the second coating liquid to the second surface of the substrate is preferably when the fluidity of the first coating liquid film formed on the first surface decreases to a certain extent, for example, from the viewpoint of suppressing the influence on the first coating liquid film during transportation by the floating transportation mechanism described later.

[0152] Therefore, when the second coating liquid is applied to the second surface of the substrate, the solid content concentration of the first coating liquid film on the back side, i.e., the first surface of the substrate, is preferably in the range of 50% by mass to 75% by mass, more preferably in the range of 55% by mass to 75% by mass, further preferably in the range of 55% by mass to 70% by mass, and particularly preferably in the range of 55% by mass to 65% by mass.

[0153] The solid content concentration of the coating liquid film can be determined by measuring the optical thickness from the time of coating until the film becomes dry using an optical interference type thickness measuring instrument (for example, infrared spectral interference type film thickness meter SI-T80 manufactured by KEYENCE CORPORATION).

[0154] Specifically, first, the optical thickness is measured from the time of coating until the film becomes dry. Next, the thickness of the dried film (i.e., dry film) is measured using a contact thickness gauge. The thickness of the measured dry film is divided by the optical thickness, and the thickness of the wet film (i.e., coating liquid film) is calculated from the optical thickness. Then, the amount of solvent (or dispersion medium) at the measurement point is obtained. The mass of the solvent (or dispersion medium) is calculated from the amount of solvent (or dispersion medium) obtained, and the value of the solid content concentration at the measurement point is calculated.

[0155] In order to start applying the second coating liquid to the second surface of the substrate while the solid content concentration of the first coating liquid film formed on the first surface is within the above range until the displacement amount F reaches 5 mm, for example, the following method may be adopted.

[0156] That is, first, the relationship between the solid content concentration of the first coating liquid film formed on the first surface of the substrate and the displacement F is obtained by experiment. Then, based on the obtained relationship between the solid content concentration of the first coating liquid film and the displacement F, the position where the second coating liquid is to be applied in the device (for example, Figure 1The following (1) to (4) may be appropriately adjusted so that the displacement F reaches 5 mm and the solid content concentration of the first coating liquid film formed on the first surface falls within the above range. From the viewpoint of less restriction on the equipment, for example, it is preferred to adjust at least one of the following (1) and (2). When the formulation freedom of the first coating liquid is high, it is preferred to adjust the following (3).

[0157] (1) Coating speed of the first coating liquid (i.e., substrate conveying speed)

[0158] (2) Whether or not pre-drying is used and what are the conditions

[0159] (3) Solid content concentration of the first coating liquid during preparation (or coating)

[0160] (4) The position from which the first coating liquid is applied to the first surface of the substrate (for example, Figure 1 ) to the position where the second coating liquid is applied to the second surface of the substrate (for example, Figure 1 The distance to the setting position of the coating mechanism 50 in

[0161] -Second coating liquid-

[0162] The second coating liquid used in this step is not particularly limited as long as it is a liquid containing a solvent (or dispersion medium) and having fluidity like the first coating liquid and can form a target film.

[0163] The second coating liquid may be the same coating liquid as the first coating liquid (for example, the aqueous coating liquid exemplified in the first coating liquid), or may be a coating liquid different from the first coating liquid.

[0164] From the viewpoint of effectively reducing curling of the widthwise ends of the substrate generated during film formation on both sides of the substrate, the second coating liquid is preferably the same coating liquid as the first coating liquid (for example, the aqueous coating liquid exemplified in the first coating liquid).

[0165] -Thickness of the second coating liquid film-

[0166] The thickness of the second coating liquid film formed in this step is not particularly limited and may be appropriately determined depending on the target film.

[0167] The thickness of the second coating liquid film is, for example, preferably 40 μm or more, more preferably 40 μm to 200 μm, and further preferably 40 μm to 100 μm.

[0168] The more the thickness of the second coating liquid film is the same as that of the first coating liquid film, the easier it is to reduce the curling of the width direction end of the substrate. Therefore, it is preferred that the thickness difference between the first coating liquid film and the second coating liquid film is small, for example, preferably 10 μm or less, more preferably 5 μm or less, and further preferably 0.

[0169] -Width of coating film and width of non-coating area-

[0170] From the viewpoint of satisfying the range of the displacement amount described later, the width of the second coating liquid film (ie, coating width) in this step is preferably equal to the width of the first coating liquid film.

[0171] Furthermore, from the perspective of satisfying the range of the offset amount described later, it is preferred that the width of the non-coated area when forming the second coating liquid film on the second surface of the substrate (i.e., the width of the exposed portion of the substrate) is equal to the width of the non-coated area on the first surface side.

[0172] - Application of the second coating liquid -

[0173] The second coating liquid in this step is applied using a known coating mechanism.

[0174] As a coating mechanism (e.g. Figure 1 The coating mechanism 50) may be any of various coating devices similar to those used when coating the first coating liquid.

[0175] Among them, as the coating mechanism in this step, from the viewpoint of achieving high-definition coating, it is preferable to use a coating device using a slit coating method, more specifically, an extrusion coater.

[0176] -Floating conveying mechanism-

[0177] In this step, when the second coating liquid is applied to the second surface of the substrate, the first coating liquid film formed on the first surface is conveyed to the substrate in a non-contact state with respect to the conveying mechanism.

[0178] As a mechanism for conveying the substrate in a non-contact state, although a known mechanism is applicable, for example, from the viewpoint of less influence on the coating liquid film, it is preferable to use a floating conveying mechanism that ejects gas to the first surface side of the substrate (i.e., the film surface of the first coating liquid film) to float and convey the substrate from the conveying mechanism.

[0179] As a floating conveying mechanism, for example Figure 1The roller-shaped floating conveying mechanism 40 shown can be a mechanism that conveys the substrate 10 along the outer peripheral surface of the floating conveying mechanism 40 and in a state not in contact with the first surface (that is, in a state not in contact with the first coating liquid film). As the floating conveying mechanism, as in the case of using the roller-shaped floating conveying mechanism 40, a mechanism that bends the substrate and conveys it can also be a mechanism that conveys the substrate without bending the substrate (for example, a mechanism that conveys the substrate horizontally).

[0180] When the second coating liquid is applied in this step, the substrate can be conveyed in a stretched state, which is considered from the perspective of improving the coating accuracy. Figure 1 As shown, it is preferably performed in a region where the substrate 10 is transported along the outer peripheral surface of the roller-shaped floating transport mechanism 40 .

[0181] A gas ejection port is provided on the outer peripheral surface of the roller-shaped floating conveying mechanism, and the gas (preferably air) ejected therefrom can be directed toward the first surface side of the substrate, thereby making the substrate float and be conveyed along the outer peripheral surface of the roller-shaped floating conveying mechanism 40 from the outer peripheral surface.

[0182] As the roller-shaped floating conveying mechanism, for example, a mechanism having a curvature radius of 100 mm to 1000 mm is used. As the curvature radius of the roller-shaped floating conveying mechanism, it is preferably 150 mm to 500 mm.

[0183] The wrap angle of the substrate relative to the roller-shaped floating conveying mechanism is preferably 60° or more, preferably 90° or more, and more preferably 120° or more. The upper limit of the wrap angle can be set to 180°, for example. The wrap angle refers to the angle formed by the conveying direction of the substrate at the starting point of the bend when the substrate is bent by the floating conveying mechanism and the conveying direction of the substrate at the end point of the bend.

[0184] The floating amount of the substrate relative to the floating conveying mechanism used in this step is preferably 500 μm or less, and more preferably 300 μm or less, from the viewpoint of stabilizing the conveying of the substrate. The lower limit of the floating amount of the substrate can be determined based on the thickness of the first coating liquid film, and can be, for example, the thickness of the first coating liquid film + 50 μm, and preferably the thickness of the first coating liquid film + 100 μm.

[0185] The floating amount of the substrate with respect to the floating transport mechanism refers to the shortest distance between the substrate in a state where the first coating liquid film is not formed and the outer peripheral surface of the floating transport mechanism.

[0186] Here, the floating amount can be measured using a laser displacement meter.

[0187] As the roller-shaped floating transport mechanism, for example, as described above, a roller member including a gas ejection mechanism capable of ejecting gas from an ejection port on the outer peripheral surface is preferable.

[0188] As the roller-shaped floating conveying mechanism, the backup roller (support body) 11 described in Japanese Patent Application Laid-Open No. 2001-310148 can also be used. In addition, various conditions related to the floating conveying of the substrate described in Japanese Patent Application Laid-Open No. 2001-310148 can also be used in the present invention.

[0189] In addition, a floating conveying mechanism having an arc-shaped outer peripheral surface may be used instead of a roller-shaped floating conveying mechanism. As a floating conveying mechanism having an arc-shaped outer peripheral surface, any component having an outer peripheral surface having a gas ejection port that is arc-shaped when viewed from the side may be used. In the case of a floating conveying mechanism having an arc-shaped outer peripheral surface, the same values ​​as those described above may be selected for the radius of curvature, the wrap angle, the floating amount, etc. As a floating conveying mechanism having an arc-shaped outer peripheral surface, the non-contact conveying device described in Japanese Patent Gazette No. 2004-256264 (for example, reference JP-A-2004-256264) may be used. Figure 2 ), the sheet support device described in Japanese Patent Publication No. 2020-050455 (for example, refer to Figure 6), the conveying device described in Japanese Patent Publication No. 2020-152570 (for example, refer to Figure 9), etc.

[0190] -Amount of misalignment-

[0191] In the method for manufacturing the laminated body according to the present embodiment, the misalignment between the width of the first coating liquid film on the first surface and the width of the second coating liquid film formed by the second coating liquid on the second surface is set to within 1 mm. From the viewpoint of effectively suppressing the curling of the width direction end of the substrate, the above-mentioned misalignment is more preferably within 0.5 mm.

[0192] As shown above, when the amount of misalignment is small, the coating liquid film is formed in the substantially same range (i.e., the same region) on both sides of the substrate. In this way, the curling of the width direction end of the substrate generated in the process of forming the film on both sides of the substrate can be suppressed.

[0193] That is, when the amount of displacement is larger than 1 mm, curling of the width direction end portions of the substrate generated during the process of forming the films on both surfaces of the substrate may not be suppressed.

[0194] The amount of displacement can be determined by the same method as the measurement of the width of the non-coated region described above.

[0195] The above-mentioned offset amount can be controlled by adjusting the positions in the width direction of the coating mechanism for coating the first coating liquid on the first surface and the coating mechanism for coating the second coating liquid on the second surface. In addition, the above-mentioned offset amount can be controlled by adjusting the alignment of the roller member in contact with the substrate and changing the position in the width direction of the substrate between coating the first coating liquid on the first surface and coating the second coating liquid on the second surface.

[0196] [Step C]

[0197] In step C, the substrate on which the first coating liquid film and the second coating liquid film are formed is dried. That is, in this step, the first coating liquid film and the second coating liquid film are dried.

[0198] -dry-

[0199] In this step, when drying the coating liquid film, a known drying mechanism is applied.

[0200] As a drying mechanism (e.g. Figure 1 The drying mechanism 60) includes, specifically, an oven, a hot air blower, an infrared (IR) heater, and the like.

[0201] The drying conditions in this step may be appropriately determined according to the material of the substrate, the type of the coating liquid film, and the like.

[0202] In the above-described manner, a laminated body was obtained in which films were formed on both surfaces of the substrate and the films, the substrate, and the films were arranged in this order.

[0203] The thickness of the film obtained in step C is not particularly limited as long as it is a thickness corresponding to the purpose, application, etc.

[0204] In the method for producing a laminate according to the present embodiment, the thickness of each of the films formed on both surfaces of the substrate is preferably 40 μm or more, more preferably 50 μm or more, and further preferably 60 μm or more.

[0205] The upper limit of the thickness of the film formed on both surfaces of the substrate is not particularly limited and may be determined according to the intended use, and is, for example, 300 μm.

[0206] The thickness of the film obtained in step C is measured in the same manner as the thickness of the coating liquid film.

[0207] [Other processes]

[0208] In at least one of the steps before step A and after step C, other steps may be included as necessary.

[0209] The other steps are not particularly limited, and examples thereof include a pretreatment step before forming the coating liquid film, a post-treatment step for the film or laminate formed on the first and second surfaces, and the like, depending on the application of the laminate.

[0210] Specific examples of the other steps include a step of surface treating the substrate, a step of curing the formed film, a step of compressing the laminated body, and a step of cutting the laminated body.

[0211] Since the method for producing a laminated body according to the present embodiment is a method for forming films on both surfaces of a substrate that is continuously conveyed, it is suitable for producing a laminated body for applications requiring high productivity.

[0212] Example

[0213] Hereinafter, the present invention will be described in more detail by giving examples. The materials, usage amounts, ratios, details of each process, etc. shown in the following examples can be appropriately changed without departing from the purpose of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[0214] In addition, “portions” are based on mass.

[0215] <Preparation of base material>

[0216] An aluminum substrate 1 (thermal conductivity: 230 W / m·K) (abbreviated as AL1) having a width of 220 mm, a thickness of 20 μm, and a length of 300 m was prepared.

[0217] An aluminum substrate 2 (thermal conductivity: 230 W / m·K) (abbreviated as AL2) having a width of 220 mm, a thickness of 40 μm, and a length of 300 m was prepared.

[0218] A PET (polyethylene terephthalate) substrate 1 (thermal conductivity: 0.23 W / m·K) (abbreviated as P1) having a width of 220 mm, a thickness of 75 μm, and a length of 300 m was prepared.

[0219] <Preparation of water-based coating liquid>

[0220] [Preparation of water-based coating liquid A]

[0221] The following components were mixed to prepare a water-based coating liquid A.

[0222] Polyvinyl alcohol: 58 parts

[0223] (CKS-50: saponification degree 99 mol%, polymerization degree 300, Nippon Synthetic Chemical Industry Co., Ltd.)

[0224] ·DKS Co.Ltd.CELLOGEN PR: 24 copies

[0225] Surfactant (NIHON EMULSION Co., Ltd., EMALEX 710): 5 parts

[0226] · Water dispersion of Artpearl (registered trademark) J-7P prepared by the following method: 913 parts

[0227] (Water dispersion of Artpearl J-7P)

[0228] 3 parts of EMALEX 710 (NIHON EMULSION Co., Ltd., nonionic surfactant) and 3 parts of sodium carboxymethylcellulose were added and dissolved in 74 parts of pure water. 20 parts of Artpearl J-7P (Negami Chemical Industrial Co., Ltd., silica composite cross-linked acrylic resin microparticles) were added to the obtained aqueous solution, and dispersed for 15 minutes at 10,000 rpm (revolutions per minute; hereinafter, the same). Artpearl J-7P water dispersion (particle concentration: 20 mass%) was obtained.

[0229] The silica-composite cross-linked acrylic resin fine particles in the obtained water dispersion had a true specific gravity of 1.20 and an average particle size of 6.5 μm.

[0230] [Preparation of water-based coating liquid B]

[0231] The following components were mixed and stirred using a dissolver (2000 rpm, 30 minutes) to prepare a water-based coating liquid B (dispersion A:dispersion B=25:75). The viscosity of the water-based coating liquid B was 20 mPa·s, and the average particle size of the particles was 0.108 μm.

[0232] Dispersion A prepared by the following method: 132.1 parts

[0233] Dispersion B prepared by the following method: 396.2 parts

[0234] Boric acid (crosslinking agent): 2.94 parts

[0235] Polyvinyl alcohol (7.3 mass % aqueous solution): 230.7 parts

[0236] (Kuraray Co., Ltd., PVA235, saponification degree 88%, polymerization degree 3500)

[0237] ·Diethylene glycol monobutyl ether: 2.7 parts

[0238] (Butysenol 20-P, KH NEOCHEM CO.,LTD.)

[0239] Ion exchange water: 93.5 parts

[0240] Polyoxyethylene lauryl ether (surfactant): 0.49 parts

[0241] (10 mass % aqueous solution of EMULGEN 109P, HLB value 13.6, Kao Corporation)

[0242] Ethanol: 41.4 parts

[0243] (Preparation of Dispersion Liquid A)

[0244] After mixing the following components and dispersing them by ultrasonic wave, the dispersion liquid was heated to 30° C. and maintained for 8 hours to prepare a dispersion A.

[0245] Fumed silica particles (inorganic particles): 299.6 parts

[0246] (AEROSIL 300SF75, NIPPON AEROSIL CO.,LTD.)

[0247] Ion exchange water: 1400 parts

[0248] Alphain 83 (40.0 mass % aqueous solution): 300 parts

[0249] (Dispersant, TAIMEI CHEMICALS Co., Ltd.)

[0250] (Preparation of Dispersion Liquid B)

[0251] After mixing the following components and dispersing them by ultrasonic wave, the dispersion liquid was heated to 30° C. and maintained for 8 hours to prepare a dispersion B.

[0252] Fumed silica particles (inorganic particles): 225.2 parts

[0253] (AEROSIL 300SF75, NIPPON AEROSIL CO.,LTD.)

[0254] Ion exchange water: 1185 parts

[0255] Cationic polymer A of the following structure (25 mass % aqueous solution): 90 parts

[0256] [Chemical formula 1]

[0257]

[0258] [Example 1]

[0259] Through Figure 1In the apparatus as shown, after the first surface of the continuously conveyed aluminum substrate (AL1) is coated with the water-based coating liquid A, the displacement F of the aluminum substrate becomes the value described in the following Table 1. When the solid content concentration of the coating liquid film formed by the water-based coating liquid A on the first surface becomes the value described in the following Table 1, the water-based coating liquid A is coated on the second surface, and coating liquid films formed by the water-based coating liquid A are formed on both surfaces of the substrate. Then, the aluminum substrate with the coating liquid films formed by the water-based coating liquid A on both surfaces is passed through a drying mechanism 60 adjusted to 60° C., thereby drying the coating liquid film.

[0260] Films were formed on both surfaces of the aluminum substrate in the manner described above to obtain a laminated body.

[0261] Here, the application of the water-based coating liquid A to the first surface is performed in the area where the aluminum substrate is wound around the support roller 20, using the first coating mechanism (specifically, an extrusion type coater) 30. Furthermore, the application of the water-based coating liquid A to the second surface is performed in the area where the aluminum substrate is bent along the outer peripheral surface of the roller-shaped floating conveying mechanism 40, using the second coating mechanism (specifically, an extrusion type coater) 50. In addition, the conveying speed of the substrate is 20 m / min.

[0262] The curvature radius of the outer peripheral surface of the floating conveyor 40 was 150 mm, the wrap angle of the substrate 10 with respect to the floating conveyor 40 was 150°, and the floating conveying distance of the substrate 10 was 785 mm. The floating amount of the substrate 10 from the outer peripheral surface of the floating conveyor 40 was 200 μm.

[0263] In this embodiment, the misalignment amount of the width of the first coating liquid film in the first surface (i.e., the coating liquid film formed by the aqueous coating liquid A formed on the first surface) and the width of the second coating liquid film formed by the second coating liquid in the second surface (i.e., the coating liquid film formed by the aqueous coating liquid A formed on the second surface) is 0.2 mm.

[0264] [Examples 2 to 6]

[0265] A laminate was obtained by forming films on both surfaces of the aluminum substrate in the same manner as in Example 1 except that the timing of starting to apply the water-based coating liquid A to the second surface of the aluminum substrate was changed.

[0266] In Examples 2 to 6, the displacement F of the aluminum substrate when the water-based coating liquid A was applied to the second surface and the solid content concentration of the coating liquid film formed by the water-based coating liquid A on the first surface are shown in Table 1 below.

[0267] In the present Examples 2 to 6, the amount of misalignment between the width of the first coating liquid film on the first surface (i.e., the coating liquid film formed by the aqueous coating liquid A formed on the first surface) and the width of the second coating liquid film formed by the second coating liquid on the second surface (i.e., the coating liquid film formed by the aqueous coating liquid A formed on the second surface) is recorded in the following Table 1.

[0268] In Example 6, the surface shape of the coating liquid film was slightly disturbed by blowing gas from the surface of the coating liquid film formed of the aqueous coating liquid A formed on the first surface in a state where the solid content concentration was low through the floating conveying mechanism 40. In addition, in the case of Example 6, the drying process was extended.

[0269] [Examples 7 and 8]

[0270] Except that the water-based coating liquid A was changed to the water-based coating liquid B, films were formed on both surfaces of the aluminum substrate in the same manner as in Examples 1 and 2, respectively, to obtain a laminate.

[0271] In Examples 7 and 8, the displacement F of the aluminum substrate when the water-based coating liquid B was applied to the second surface and the solid content concentration of the coating liquid film formed by the water-based coating liquid B on the first surface are shown in Table 1 below.

[0272] In Examples 7 and 8, the amount of misalignment between the width of the first coating liquid film on the first surface (i.e., the coating liquid film formed by the aqueous coating liquid B formed on the first surface) and the width of the second coating liquid film formed by the second coating liquid on the second surface (i.e., the coating liquid film formed by the aqueous coating liquid B formed on the second surface) is recorded in Table 1 below.

[0273] [Example 9]

[0274] A laminate was obtained by forming films on both surfaces of the aluminum substrate in the same manner as in Example 1, except that the aqueous coating liquid A was applied to the second surface of the aluminum substrate while the aluminum substrate was horizontally conveyed by the floating conveyance mechanism.

[0275] Then, the distance of horizontal conveyance of the substrate by the floating conveyance mechanism was 785 mm, and the floating amount of the substrate from the outer peripheral surface (flat surface) of the floating conveyance mechanism was 200 μm.

[0276] [Comparative Example 1]

[0277] A laminate was obtained by forming films on both sides of the aluminum substrate in the same manner as in Example 1, except that after the water-based coating liquid A was initially applied to the first surface and after the coating liquid film of the water-based coating liquid A formed on the first surface was dried (specifically, after the constant-rate drying and the decelerated-rate drying were completed and the solid content concentration of the coating liquid film became 100% by mass), the water-based coating liquid A was applied to the second surface of the aluminum substrate bent by the floating conveying mechanism.

[0278] In Comparative Example 1, the displacement F of the aluminum substrate when the water-based coating liquid A was first applied to the second surface and the solid content concentration of the coating liquid film formed of the water-based coating liquid A on the first surface are shown in Table 1 below.

[0279] [Examples 10 and 11]

[0280] Except that the type of the substrate was changed as shown in the following Table 2, films were formed on both surfaces of the substrate in the same manner as in Example 1 to obtain a laminate.

[0281] In Examples 10 and 11, the displacement F of the substrate when the water-based coating liquid A was applied to the second surface and the solid content concentration of the coating liquid film formed by the water-based coating liquid A on the first surface are shown in Table 2 below.

[0282] In Examples 10 and 11, the amount of misalignment between the width of the first coating liquid film on the first surface (i.e., the coating liquid film formed by the aqueous coating liquid A formed on the first surface) and the width of the second coating liquid film formed by the second coating liquid on the second surface (i.e., the coating liquid film formed by the aqueous coating liquid A formed on the second surface) is recorded in Table 2 below.

[0283] [Examples 12 to 14]

[0284] Except that the thickness of the first coating liquid film formed on the first surface and the thickness of the second coating liquid film formed on the second surface were appropriately changed as shown in Table 2 below, films were formed on both surfaces of the aluminum substrate in the same manner as in Example 1 to obtain a laminate.

[0285] In Examples 12 to 14, the displacement F of the aluminum substrate when the water-based coating liquid A was first applied to the second surface and the solid content concentration of the coating liquid film formed by the water-based coating liquid A on the first surface are shown in Table 2 below.

[0286] In the present Examples 12 to 14, the amount of misalignment between the width of the first coating liquid film on the first surface (i.e., the coating liquid film formed by the aqueous coating liquid A formed on the first surface) and the width of the second coating liquid film formed by the second coating liquid on the second surface (i.e., the coating liquid film formed by the aqueous coating liquid A formed on the second surface) is recorded in the following Table 2.

[0287] [Various measurements]

[0288] The thickness of the substrate, the thickness of the first coating liquid film, and the thickness of the second coating liquid film were measured by the methods described above.

[0289] The displacement amount F of the end portion in the width direction of the aluminum substrate at the time when the second coating liquid started to be applied to the second surface of the aluminum substrate was measured by the method described above.

[0290] The solid content concentration of the coating liquid film formed on the first surface of the aluminum substrate at the time of starting to apply the second coating liquid to the second surface of the aluminum substrate was measured by the method described above.

[0291] [Evaluation of the amount of misalignment]

[0292] In the examples, the displacement amount between the width of the first coating liquid film on the first surface and the width of the second coating liquid film formed of the second coating liquid on the second surface was also measured by the method described above.

[0293] In addition, the amount of misalignment between the width of the dry film of the first coating liquid film on the first surface (i.e., the dry film of the coating liquid film formed by the aqueous coating liquid A formed on the first surface) and the width of the dry film of the second coating liquid film formed by the second coating liquid on the second surface (i.e., the dry film of the coating liquid film formed by the aqueous coating liquid A formed on the second surface) was measured only for Comparative Example 1. This measurement was performed in the same manner as the amount of misalignment between the width of the first coating liquid film on the first surface and the width of the second coating liquid film on the second surface.

[0294] The results are shown in Tables 1 and 2.

[0295] [Evaluation of Curl at the Width-Direction End of the Substrate]

[0296] The curling of the width direction end portions of the aluminum substrate obtained in each example and provided with films on both surfaces was evaluated.

[0297] The curling amount C was measured in the same manner as the measurement of the floating amount when the displacement amount F was obtained as described above, and was evaluated based on the following criteria.

[0298] -Evaluation Criteria-

[0299] G1: Curl amount C is less than 2 mm

[0300] G2: Curl amount C is greater than 2mm and less than 5mm

[0301] G3: Curl amount C is greater than 5mm

[0302] The results are shown in Tables 1 and 2.

[0303]

[0304]

[0305] As is clear from Tables 1 and 2, the laminate obtained by the method for producing a laminate in the example has little curling after drying the coating liquid films formed on both surfaces of the substrate.

[0306] Furthermore, in the laminate obtained in the example, the offset between the width of the dry film of the first coating liquid film and the width of the dry film of the second coating liquid film was measured by the method described above, and it was confirmed that it was limited to within 1 mm. Thus, since the laminate obtained in the example has dry films formed in substantially the same area on the first surface and the second surface of the substrate, it is estimated that curling is reduced.

[0307] On the other hand, as is clear from Table 1, when the amount of misalignment is large as in Comparative Example 1, the curling becomes larger.

[0308] Explanation of symbols

[0309] 10-belt-shaped substrate, 20-support roller, 30-first coating mechanism, 40-floating conveying mechanism, 50-second coating mechanism, 60-drying mechanism, P-position on the conveying path where the displacement F reaches 5 mm during the drying process of the first coating liquid film formed on the first surface.

[0310] All disclosed contents of Japanese Patent Application No. 2020-210735 filed on December 18, 2020 are incorporated into this specification by reference. All documents, patent applications, and technical standards described in this specification are incorporated into this specification by reference to the same extent as if each document, patent application, and technical standard was specifically and separately described as being incorporated by reference.

Claims

1. A method for producing a laminate, comprising the following steps: The first coating liquid is applied to the first surface of the substrate being continuously conveyed, and the second coating liquid is applied to the second surface of the substrate opposite to the first surface before the width direction end of the substrate on which the first coating liquid film formed by the first coating liquid is curled and causes a displacement of 5 mm, in, The misalignment amount between the width of the first coating liquid film on the first surface and the width of the second coating liquid film formed by the second coating liquid on the second surface is within 1 mm.

2. The method for producing a laminate according to claim 1, wherein: The thickness of the substrate is 5 μm or more and 80 μm or less.

3. The method for producing a laminate according to claim 1 or 2, wherein: The film thickness of the first coating liquid film and the second coating liquid film is 40 μm or more.

4. The method for producing a laminate according to claim 1 or 2, wherein: The second coating liquid is applied to the second surface of the substrate opposite to the first surface until the solid content concentration of the first coating liquid film reaches 70% by mass.

5. The method for producing a laminate according to claim 1 or 2, wherein: While the solid content concentration of the first coating liquid film is 55 mass % or more and 70 mass % or less, the second coating liquid is started to be applied to the second surface of the substrate opposite to the first surface.

6. The method for producing a laminate according to claim 1 or 2, wherein: The second coating liquid was applied using an extrusion coater.

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