Manufacturing method of laminate

Abstract

A method for producing a multilayer body, said method comprising a step wherein application of a first coating liquid onto a first surface of a base material is started when the base material is continuously conveyed on a conveyance path, and application of a second coating liquid onto a second surface of the base material, said second surface being on the reverse side of the first surface, is started during the time when the solid content concentration of a first coating liquid film formed of the first coating liquid is from 40% by mass to 80% by mass. With respect to this method for producing a multilayer body, the application of the second coating liquid onto the second surface is carried out in a region where the base material is conveyed along the conveyance path that is curved, with respect to the first surface side, by being applied with a pressure by means of a gas; and the amount of positional shift between the width of the first coating liquid film on the first surface and the width of a second coating liquid film formed of the second coating liquid on the second surface is 1 mm or less.

Description

[Technical Field]

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

[0002] A method is known in which a desired film is formed on both sides (i.e., a first side and a second side opposite to the first side) of a strip-shaped substrate in a continuous roll-to-roll process, thereby producing a laminate in which the film, substrate, and film are arranged in this order. The laminate can be produced, for example, by applying a coating liquid for obtaining a desired film onto a substrate and then drying the resulting coating liquid film.

[0003] As an example of a method for producing a laminate, Japanese Patent Application Laid-Open No. 2004-344693 discloses a sequential coating method in which a coating liquid is applied to the surface of a traveling strip-shaped plastic support, and the applied coating film is dried at a temperature equal to or higher than the glass transition temperature of the support, and this coating and drying process is carried out on both sides of the support.

[0004] Furthermore, Japanese Patent Application Laid-Open No. 2-119968 discloses a method in which a coating liquid is applied to a first surface of a web, the coating liquid applied to the first surface is cooled to promote gelation, and then the first surface (i.e., the coated surface) is supported by a gas ejection device and allowed to run continuously, and the coating liquid is applied to a second surface (the surface opposite to the first surface). Summary of the Invention [Problem to be solved by the invention]

[0005] For example, as described in Japanese Patent Application Laid-Open No. 2004-344693, there is a method for producing a laminate, which involves sequentially applying a coating liquid to both sides of a substrate while the substrate is being continuously transported. This involves starting application of a coating liquid to a first side of the substrate and then starting application of a coating liquid to a second side opposite the first side of the substrate. In this production method, curling may occur at the widthwise edges of the substrate during the drying stage of the coating liquid film formed on the first side. The curling may make it difficult to form a desired coating liquid film on the second side. For example, if curling occurs during this stage, it becomes impossible to reduce the misalignment between the width of the coating liquid film formed on the first side and the width of the coating liquid film formed on the second side. As a result, curling may also occur in the resulting laminate (specifically, a laminate having a dried film).

[0006] Therefore, the problem to be solved by one embodiment of the present disclosure is to provide a method for manufacturing a laminate, which includes a step of starting application of a coating liquid to a first surface of a substrate that is being continuously transported, and then starting application of the coating liquid to a second surface of the substrate opposite to the first surface, and which produces a laminate with reduced curl and a small amount of positional misalignment between 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. [Means for solving the problem]

[0007] Means for solving the above problems include the following embodiments. <1> a step of starting application of a first coating liquid to a first surface of a substrate being continuously transported on a transport path, and starting application of a second coating liquid to a second surface of the substrate opposite to the first surface while the solid content concentration of the first coating liquid film formed by the first coating liquid is 40% by mass to 80% by mass; the second coating liquid is applied to the second surface in a region where the substrate is conveyed along the curved conveyance path while pressure is applied to the first surface side by gas; A method for producing a laminate, wherein the amount of misalignment between the width of a first coating liquid film on a first surface and the width of a second coating liquid film formed by a second coating liquid on a second surface is within 1 mm.

[0008] <2> The thickness of the substrate is 5 μm or more and 80 μm or less. <1> A method for producing the laminate described in 1. <3> The film thickness of the first coating liquid film and the second coating liquid film is 40 μm or more. <1> or <2> A method for producing the laminate described in . <4> The radius of curvature of the curved conveying path is 100 mm to 500 mm. <1> ~ <3> 10. A method for producing the laminate according to any one of the preceding items. <5> The length of the curved conveying path is 350 mm to 1750 mm. <1> ~ <4> 10. A method for producing the laminate according to any one of the preceding items. <6> the distance from the curve start point of the conveying path to the application start point of the second coating liquid is 50±25% of the distance of the curved conveying path; <1> ~ <5> 10. A method for producing the laminate according to any one of the preceding items. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, there is provided a method for manufacturing a laminate, which includes a step of starting application of a coating liquid to a first surface of a substrate that is being continuously transported, and then starting application of the coating liquid to a second surface of the substrate opposite to the first surface, and which produces a laminate with a small amount of positional misalignment between 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, and with reduced curl. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating each step of a method for producing a laminate according to an embodiment. [Figure 2] 5A and 5B are cross-sectional schematic views for explaining the amount of curl at the end portions in the width direction of the substrate. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of a method for producing a laminate will be described. However, the present invention is not limited to the following embodiment, and can be practiced with appropriate modifications within the scope of the object of the present invention.

[0012] In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. The elements in the drawings shown in this disclosure are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. In addition, in each drawing, components having the same functions are given the same reference numerals, and duplicated explanations will be omitted. In the present disclosure, a "substrate" refers to a substrate that is continuously transported and has a belt-like shape. In the present disclosure, the "width direction" refers to a direction perpendicular to the longitudinal direction (i.e., the transport direction) of any of the continuously transported substrate (i.e., the belt-shaped substrate), the coating liquid film, and the film. In the present disclosure, the "first side" of a substrate refers to one side of a strip-shaped substrate, and unless otherwise specified, refers to the side on which a coating liquid is applied first. The "second side" of a substrate refers to the other side of the strip-shaped substrate, i.e., the side opposite to the first side, and unless otherwise specified, refers to the side on which a coating liquid is applied second. In the present disclosure, a combination of two or more preferred aspects or embodiments is a more preferred aspect or embodiment.

[0013] <<Laminate manufacturing method>> As described above, when using double-sided coating, in which coating liquids are sequentially applied to both sides of a substrate while the substrate is being continuously transported, such as by starting application of a coating liquid to a first side of the substrate and then starting application of a coating liquid to a second side opposite the first side of the substrate, curling may occur at the widthwise edges of the substrate during the drying stage of the coating liquid film formed on the first side. The curling at this stage may make it difficult to form a desired coating liquid film on the second side. For example, if curling occurs at this stage, it becomes impossible to reduce the misalignment between the width of the coating liquid film formed on the first side and the width of the coating liquid film formed on the second side. As a result, curling may also occur in the resulting laminate (specifically, a laminate having a dried film). Therefore, the inventors discovered that when double-sided coating is performed as described above, even if curl occurs at the widthwise end of the substrate on which a coating liquid film is formed on the first side, by applying the coating liquid to the second side while correcting the curl while the solid content concentration of the coating liquid film on the first side is within a certain range, the amount of positional misalignment between the width of the coating liquid film formed on the first side and the width of the coating liquid film formed on the second side can be reduced, and a laminate with reduced curl can be obtained.

[0014] The method for manufacturing a laminate according to this embodiment includes a step of starting application of a first coating liquid to a first surface of a substrate being continuously conveyed on a conveyance path, and starting application of a second coating liquid to a second surface of the substrate opposite to the first surface while the solid content of the first coating liquid film formed by the first coating liquid is 40% by mass to 80% by mass, in which the second coating liquid is applied to the second surface in a region where the substrate is conveyed along a curved conveyance path while gas pressure is applied to the first surface side, and the amount of positional deviation 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. According to the method for manufacturing a laminate of this embodiment, a laminate is obtained in which a film formed on the first surface side of a substrate, the substrate, and a film formed on the second surface side of the substrate are arranged in this order.

[0015] According to the method for producing a laminate according to this embodiment, application of the second coating liquid to the second surface opposite the first surface of the substrate is initiated while the solid content of the first coating liquid film formed by the first coating liquid is between 40% and 80% by mass. By setting the solid content of the first coating liquid film formed by the first coating liquid to 80% by mass or less at the start of application of the second coating liquid to the second surface, the substrate having the first coating liquid film with some residual solvent is conveyed along the curved conveyance path, and any curl present at the widthwise edge is straightened. Therefore, when the substrate having the first coating liquid film is conveyed along the curved conveyance path, the curl has been straightened and the flatness of the substrate is not impaired, allowing the second coating liquid to be applied to the desired region of the second surface. As a result, the amount of misalignment between 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 (i.e., within 1 mm). By keeping the misalignment within 1 mm, the force of curling toward the first surface due to shrinkage caused by drying of the first coating liquid film and the force of curling toward the second surface due to shrinkage caused by drying of the second coating liquid film can be counterbalanced with the substrate as the center. As a result, in a laminate obtained by drying the substrate on which the first and second coating liquid films have been formed, curling that occurs at the width direction edges of the substrate can be reduced. Furthermore, by setting the solid content concentration of the first coating liquid film from the first coating liquid to 40 mass % or more at the start of coating the second coating liquid on the second surface, the shape retention of the first coating liquid film is improved, and even if gas pressure is applied to the first surface side, the surface condition of the first coating liquid film can be prevented from becoming rough, thereby forming a film with excellent surface condition on the first surface.

[0016] On the other hand, in the method described in JP 2004-344693 A, the coating of the second surface of the substrate is started after the coating liquid film formed on the first surface of the substrate has dried, and it is estimated that the solid content concentration of the coating liquid film formed on the first surface is 100 mass % or a value close to that at the stage when coating of the second surface is started. Furthermore, in the method described in JP-A-2-119968, coating of the second surface of the substrate is initiated after the coating liquid film formed on the first surface of the substrate has gelled. This method is a special example using a gelling coating liquid film, and it is presumed that the solid content concentration of the coating liquid film formed on the first surface remains low (for example, less than 40 mass %) during the gelling process of the coating liquid film. Furthermore, in this method, the gelling process tends to be very long, and it is thought that the amount of positional deviation between the width of the coating liquid film on the first surface and the width of the coating liquid film on the second surface becomes large.

[0017] Hereinafter, each step of the method for producing the laminate of this embodiment will be described.

[0018] First, an example of a method for producing a laminate will be described with reference to Fig. 1. Here, Fig. 1 is a schematic diagram of an apparatus to which the method for producing a laminate of one embodiment is applied, and is used to explain each step. As shown in Fig. 1, conveyance of a strip-shaped substrate 10 wound into a roll begins when its leading end is fed in the direction of the arrow, and the substrate is continuously conveyed until it is wound into a roll. The substrate 10 shown in Fig. 1 is continuously conveyed by a backup roll 20, a floating conveying means 40, and other conveying means (not shown). Therefore, in Fig. 1, the "line" marked with the symbol 10 also serves as a "conveying path," which is the path along which the substrate 10 moves. 1, in a region where the substrate 10 is wound around the backup roll 20, the coating means 30 starts coating the first surface of the substrate 10 with the first coating liquid (hereinafter also referred to as step A). ​​In step A, a first coating liquid film (not shown) made of the first coating liquid is formed on the first surface of the belt-shaped substrate 10. Next, the strip-shaped substrate 10, having a first coating liquid film (not shown) formed on its first surface, is curved along the outer peripheral surface of the roll-shaped floating transport means 40 and transported in a state of non-contact with the surface on the first side (i.e., a state of non-contact with the first coating liquid film). Here, the substrate 10 is transported along the curved transport path by applying gas pressure to the first side by the floating transport means 40. Then, in the region where the strip-shaped substrate 10 is transported in a curved state by the floating transport means 40, the coating means 50 begins applying the second coating liquid to the second side of the substrate 10 (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 side of the strip-shaped substrate 10. Subsequently, after the second coating liquid film is formed on the second surface, the belt-shaped substrate 10 passes through drying means 60 (hereinafter also referred to as step C). In step C, the first coating liquid film on the first surface of the belt-shaped substrate 10 and the second coating liquid film on the second surface thereof are dried, and films are formed on both surfaces of the substrate 10. Furthermore, the substrate 10 after passing through the drying means 60 is wound up in a roll after undergoing any step not shown, as required.

[0019] [Step A] In step A, application of the first application liquid to a first surface of a substrate that is being continuously transported is started.

[0020] The substrate used in this step is not particularly limited as long as it can be continuously transported, and a substrate may be selected depending on the application of the laminate to be formed. The substrate may be made of resin or metal, and may have a multi-layer structure including a resin layer and a metal layer.

[0021] Furthermore, the substrate may have 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 substrate as a whole may have a thermal conductivity of 200 W / m K or more. The upper limit of the thermal conductivity of the substrate is not particularly limited, and is, for example, 500 W / m·K.

[0022] Specific examples of substrates exhibiting the above thermal conductivity include metal substrates made of copper, aluminum, silver, gold, and alloys thereof. Among these, copper substrates and aluminum substrates are preferably used from the viewpoint of shape stability as a substrate, usage track record, and the like.

[0023] The thermal conductivity of the substrate is measured as follows. First, the substrate is cut to a size suitable for the apparatus described below to obtain a measurement sample. The thermal diffusivity of the obtained measurement sample in the thickness direction is measured using the laser flash method. Next, the specific gravity of the measurement sample is measured using a balance equipped with a specific gravity measurement kit. Furthermore, using a differential scanning calorimeter (DSC), the specific heat of the measurement sample at 25°C is measured under a temperature increase condition of 10°C / min. The thermal conductivity of the measurement sample (i.e., the substrate) is calculated by multiplying the obtained thermal diffusivity by the specific gravity and specific heat. Here, for example, the "LFA467" manufactured by NETZSCH is used to measure thermal diffusivity. Furthermore, for example, the "XS204" balance manufactured by Mettler-Toledo K.K. using a solid specific gravity measurement kit is used to measure specific gravity. Furthermore, for example, the "DSC320 / 6200" manufactured by Seiko Instruments Inc. is used to measure specific heat.

[0024] The thickness of the substrate may be appropriately set from the viewpoint of application to the roll-to-roll method. 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. Even when the thickness of the substrate is as thin as described above, the method for producing a laminate according to this embodiment can reduce curling. The width and length of the substrate may be appropriately set in consideration of application to the roll-to-roll method and the width and length of the desired film.

[0025] The thickness of the substrate is measured as follows. That is, using a contact-type thickness measuring device, the thickness of the substrate is measured at three points in the width direction (specifically, 5 mm from both edges in the width direction and at the center in the width direction) at three points spaced 500 mm apart in the longitudinal direction. The arithmetic mean value of the nine measured values ​​is calculated and used as the thickness of the substrate. As a contact type thickness measuring instrument, for example, S-2270 manufactured by Fuji Work Co., Ltd. is used.

[0026] -First coating liquid- The first coating liquid used in this step is not particularly limited as long as it is a fluid liquid containing a solvent (or a dispersion medium) and is capable of forming the desired film. The first coating liquid may use an organic solvent or water as the solvent (or dispersion medium).

[0027] The first coating liquid may be, for example, a water-based 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 the inclusion of a solvent other than water that is introduced when using a solid component in preparing the coating liquid is permitted. 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, preferably 95% by mass or more, and particularly preferably all solvents (or all dispersion media) are water. The solid content refers to components excluding the solvent (or dispersion medium).

[0028] The water-based coating liquid is not particularly limited as long as it is a liquid containing water as a solvent (or dispersion medium) and a solid content. The solid content contained in the water-based coating liquid includes components for obtaining the desired film, as well as components for improving coating suitability.

[0029] Examples of water contained in the aqueous coating liquid include natural water, purified water, distilled water, ion-exchanged water, pure water, and ultrapure water (e.g., Milli-Q water). Milli-Q water is ultrapure water obtained using a Milli-Q water production system manufactured by Merck Ltd.

[0030] The water content in the water-based coating liquid is not particularly limited, and is, for example, preferably 40% by mass or more, more preferably 50% by mass or more, based on the total mass of the water-based coating liquid. The upper limit of the water content is sufficient as long as it is less than 100% by mass, but from the viewpoint of coating suitability, it is, for example, 90% by mass relative to the total mass of the water-based coating liquid.

[0031] The water-based coating liquid may contain particles as one of its solid components, that is, the water-based coating liquid may be a coating liquid containing particles. When a water-based coating liquid containing particles is used, the particles also aggregate during the drying stage, which tends to cause curling at the width direction edges of the substrate. In the method for producing a laminate according to this embodiment, even when a water-based coating liquid containing particles is used as the first coating liquid, curling at the width direction edges of the substrate can be reduced.

[0032] The particles are not particularly limited as long as they are granular, and may be inorganic particles, organic particles, or composite particles of inorganic and organic substances.

[0033] As the inorganic particles, known inorganic particles that can be applied to the desired film can be used. Examples of inorganic particles include particles of metals (alkali metals, alkaline earth metals, transition metals, alloys of these metals, etc.), particles of semi-metals (silicon, etc.), particles of compounds containing metals or semi-metals (oxides, hydroxides, nitrides, etc.), and inorganic pigments containing carbon black, etc. Other examples of inorganic particles include particles of minerals such as mica.

[0034] As the organic particles, known organic particles that can be applied to the target film can be used. The organic particles are not particularly limited as long as they are particles of solid organic matter, including resin particles and organic pigment particles.

[0035] 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.

[0036] The particles may be surface-treated for the purpose of imparting dispersibility or the like. The particles may be surface-treated to become the composite particles described above.

[0037] There are no particular limitations on the particle size, shape, specific gravity, or usage form (e.g., whether or not to use in combination), and these may be selected appropriately depending on the desired membrane or the conditions suitable for producing the membrane.

[0038] The content of particles in the aqueous coating liquid is not particularly limited, and may be determined appropriately depending on the desired film, the conditions suitable for producing the film, or the purpose of adding the particles.

[0039] The solid content contained in the aqueous coating liquid is not particularly limited, and may include various components used to obtain the desired film. Specific examples of 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, reactive components such as polymerizable compounds and polymerization initiators, components for improving coating performance such as surfactants, and other additives.

[0040] -Thickness of the first coating liquid film- There are no particular limitations on the thickness of the first coating liquid film formed in this step, and it may be determined appropriately depending on the desired film. The thickness of the first coating liquid film is, for example, preferably 40 μm or more, more preferably 40 μm to 200 μm, and even more preferably 40 μm to 100 μm. The thicker the first coating liquid film, the more likely it is that curling will occur at the width direction edges of the substrate when the first coating liquid film is dried. In the method for producing a laminate according to this embodiment, curling at the width direction edges of the substrate can be reduced even when the first coating liquid film is thick.

[0041] The thickness of the coating liquid film is measured as follows. That is, the thickness of the first coating liquid film is measured at three locations along the width direction (specifically, at positions 5 mm from both edges in the width direction and at the center in the width direction) using an optical interference thickness measuring device. The arithmetic mean value of the measurements at the three points is calculated and used as the thickness of the coating liquid film. As an optical interference type thickness measuring device, for example, Keyence Corporation's infrared spectroscopic interference type film thickness meter SI-T80 is used.

[0042] -Width of coating liquid film- The width of the first coating liquid film in this step (ie, coating width) is not particularly limited, and may be determined depending on the width of the substrate, the use of the film, and the like. The width of the first coating liquid film can be selected to be, for example, 100 mm or more, or 1000 mm or more. The upper limit of the width of the first coating liquid film is the width of the substrate.

[0043] -Width of non-coated area- When the first coating liquid film is formed on the first surface of the substrate, the width of the non-coated region (i.e., the width of the exposed portion of the substrate) is preferably, for example, 2 mm or more, and more preferably 5 mm or more, at both widthwise ends of the substrate, from the viewpoint of easily achieving the effects of the manufacturing method of the laminate according to this embodiment. The upper limit of the width of the non-coated area on the first surface is preferably, for example, 30 mm.

[0044] The width of the coating liquid film is measured as follows. That is, the width of the coating liquid film is measured at three points with a ruler at intervals of 500 mm in the longitudinal direction when viewed from above from the film surface side of the coating liquid film. The arithmetic mean value of the measurements taken at the three points is calculated and is regarded as the width of the coating liquid film. The width of the coated area is measured as follows. That is, when viewed from above from the film surface side of the coating liquid film, the shortest distance from the end of the substrate in the width direction to the end of the coating liquid film is measured with a ruler at three points spaced 500 mm apart in the longitudinal direction. This measurement is performed at each end of the substrate in the width direction. The arithmetic mean value of the six measured values ​​is calculated and used as the width of the coated area.

[0045] - Application of the first coating liquid - In this step, the first coating liquid is applied by a known coating means. Specific examples of the coating means (for example, coating means 30 in FIG. 1) include coating devices that use a curtain coating method, a dip coating method, a print coating method, a spray coating method, a slot coating method, a roll coating method, a slide coating method, a blade coating method, a gravure coating method, a wire bar method, etc. Among these, as the coating means in this step, a coating device using a slot coating method, more specifically an extrusion type die coater, is preferably used from the viewpoint of enabling high-definition coating.

[0046] -Backup role- In this step, when applying the first coating liquid, the substrate can be transported in a tensioned state, and from the viewpoint of improving coating accuracy, it is preferable that the application be performed in an area where the substrate is wound around a backup roll, as shown in FIG.

[0047] The backup roll is a rotatable member, and when the backup roll rotates, the substrate can be transported in a tensioned state along the outer circumferential surface of the backup roll.

[0048] The backup roll may be heated 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 (i.e., whitening of the coating film due to the formation of fine condensation).

[0049] The surface temperature of the backup roll is preferably controlled by a temperature control means, and more preferably controlled by a temperature control means based on the detected surface temperature.

[0050] The temperature control means may be, for example, a heating means or a cooling means. The heating means may be, for example, induction heating, water heating, or oil heating. The cooling means may be, for example, cooling with cooling water.

[0051] The diameter of the backup roll is preferably 100 mm to 1,000 mm, more preferably 100 mm to 800 mm, and particularly preferably 200 mm to 700 mm, from the viewpoints of ease of winding the substrate, ease of application using a die head, and the manufacturing cost of the backup roll.

[0052] From the viewpoints of productivity and coating properties, the transport speed of the substrate by the backup roll is preferably, for example, 10 m / min to 100 m / min.

[0053] The wrap angle of the substrate relative to the backup roll is preferably 60° or more, more preferably 90° or more, from the viewpoint of stabilizing the substrate transport during coating of the first coating liquid and suppressing the occurrence of uneven thickness of the coating liquid film. The upper limit of the wrap angle can be set to, for example, 180°. The wrap angle refers to the angle formed by the substrate transport direction when the substrate contacts the backup roll and the substrate transport direction when the substrate separates from the backup roll.

[0054] [Step B] In step B, while the solid content of the first coating liquid film made of the first coating liquid is 40% by mass to 80% by mass, coating of the second coating liquid is started on a second surface opposite to the first surface of the substrate. In this step, the second coating liquid is applied to the second surface in a region where the substrate is transported along a curved transport path while gas pressure is applied to the first surface side.

[0055] -Solid content of the first coating liquid film- The timing to start applying the second coating liquid to the second surface of the substrate is when the solid content of the first coating liquid film is between 40% by mass and 80% by mass. The timing to start applying the second coating liquid to the second surface of the substrate is preferably when the solid content of the first coating liquid film is between 45% by mass and 75% by mass, and more preferably when it is between 50% by mass and 65% by mass. If the solid content concentration of the first coating liquid film is less than 40% by mass, the solid content concentration of the first coating liquid surface is low, and when gas is applied to the first surface side, the first coating liquid film may flow, causing the surface to become rough and the thickness of the first coating liquid film to become uneven.On the other hand, if the solid content concentration of the first coating liquid film exceeds 80%, when the substrate is transported along a curved transport path, the first coating liquid film may not be able to follow the changes in shape of the substrate, and cracks may occur in the first coating liquid film.

[0056] 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 device (for example, Keyence's infrared spectroscopic interference film thickness meter SI-T80). Specifically, first, the optical thickness is measured from the time of application until the film becomes dry. Next, the thickness of the film (dry film) after drying is measured using a contact thickness meter. The measured dry film thickness is divided by the optical thickness, and the thickness of the wet film (coating 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 obtained amount of solvent (or dispersion medium), and the solid concentration value at the measurement point is calculated.

[0057] The timing to start applying the second coating liquid to the second surface of the substrate can be determined based on a position on the transport path where the solid content concentration of the first coating liquid film formed on the first surface is within the above range, which is determined in advance. Specifically, the transition of the solid content concentration of the coating liquid film is investigated in advance by the above-mentioned method, and the position on the transport path where the solid content concentration of the first coating liquid film formed on the first surface is within the above-mentioned range is identified. Then, the installation position of the coating means 50 may be set so that coating of the second coating liquid on the second surface starts at the identified position on the transport path.

[0058] Alternatively, the installation position of coating unit 50 may be fixed, and the solid content concentration of the first coating liquid film formed on the first surface may be controlled so that the solid content concentration of the first coating liquid film is within the above range at the point where coating unit 50 starts applying the second coating liquid. In this case, the solid content concentration of the first coating liquid used in step A may be adjusted. Furthermore, pre-drying of the first coating liquid film may be performed between the start of application of the first coating liquid on the first surface and the start of application of the second coating liquid on the second surface, to adjust the solid content concentration of the first coating liquid film formed on the first surface.

[0059] -Floating transport means- In this step, pressure is applied by gas to the first surface side of the substrate (the surface of the first coating liquid film), causing the substrate to be transported along a curved transport path. To form such a curved transport path, a floating transport means using a roll member equipped with a gas ejection mechanism capable of ejecting gas from an ejection port on the outer circumferential surface is used. When a roll member equipped with the above-mentioned gas ejection mechanism is used and gas is ejected from the ejection port on the outer peripheral surface of the roll member to apply pressure to the first surface side of the substrate, the substrate floats up from the outer peripheral surface of the roll member and is conveyed while curving along the outer peripheral surface.

[0060] The floating transport means is not limited to the roll member as long as it can form the curved transport path. For example, it may be a member having an arc-shaped outer circumferential surface in a side view and equipped with a gas ejection mechanism capable of ejecting gas from an outlet on the outer circumferential surface.

[0061] The substrate being conveyed while being curved by the floating conveying means is stretched in a curved shape in the conveying direction, and therefore even if curl has occurred at the width direction end of the substrate when the application of the second coating liquid to the second surface begins, the curl can be regulated. More specifically, as shown in Figure 1, in the region where the substrate 10 (and the transport path) is transported while curving (specifically, the region from position P1 to position P2 in Figure 1), even if curl occurs at the widthwise end of the substrate 10 on which the first coating liquid film is formed in the previous region, the curl is regulated because a curl regulating force acts in the region from position P1 to position P2.

[0062] Furthermore, as shown in FIG. 1, in the region where the substrate 10 (and the transport path) is transported while curving (specifically, the region from position P1 to position P2 in FIG. 1), the substrate 10 can be transported in a tensioned state, and the transport of the substrate 10 is stabilized, thereby improving the accuracy of application of the second coating liquid by the coating means 50.

[0063] In this step, from the viewpoint of more strongly restricting curling, the radius of curvature of the curved transport path (specifically, for example, the region from position P1 to position P2 in Figure 1) is preferably 100 mm to 500 mm, more preferably 200 mm to 400 mm, and even more preferably 250 mm to 350 mm. The radius of curvature of the curved transport path can be determined by adjusting the radius of curvature of the outer circumferential surface of the floating transport means having a circular or arcuate outer circumferential surface in a side view.

[0064] Generally, from the viewpoint of stabilizing the transport of the substrate, the floating amount of the substrate from the floating transport means having a circular or arc-shaped outer peripheral surface in a side view is made constant. Therefore, the radius of curvature of the curved transport path corresponds to the sum of the floating amount and the radius of curvature of the floating transport means having a circular or arc-shaped outer peripheral surface in a side view (i.e., the radius of curvature of the circular or arc-shaped outer peripheral surface). However, as described below, the maximum floating amount is 500 μm, so the radius of curvature of the floating conveying means having a circular or arc-shaped outer surface in side view (i.e., the radius of curvature of the circular or arc-shaped outer surface) may be substituted for the radius of curvature of the curved conveying path.

[0065] In this step, from the viewpoint of more strongly restricting curling, the distance of the curved conveying path (specifically, for example, the distance from position P1 to position P2 in Figure 1) is preferably 350 mm to 1750 mm, more preferably 600 mm to 1500 mm, and even more preferably 800 mm to 1200 mm. The length of the curved transport path can be determined by adjusting the length of the outer peripheral surface of the floating transport means having a circular or arc-shaped outer peripheral surface in the transport direction of the substrate, or the wrap angle of the substrate.

[0066] In this step, from the viewpoint of more strongly restricting curling and increasing the accuracy of application of the second coating liquid, the distance from the start point of curvature of the curved conveying path to the start point of application of the second coating liquid (specifically, for example, the distance from position P1 to position P3 in FIG. 1) is preferably 50±25% of the length of the curved conveying path (specifically, for example, the distance from position P1 to position P2 in FIG. 1). The distance from the start point of curvature of the curved conveying path to the start point of application of the second coating liquid is preferably 50±20% of the length of the curved conveying path, and more preferably 50±10% of the length of the curved conveying path. In other words, it is preferable that the application of the second application liquid to the second surface starts near the center of the curved transport path. In order to satisfy the above conditions, the installation position of the coating means 50 may be adjusted.

[0067] Here, positions P1, P2, and P3 in FIG. 1 will be described. Position P1 in Figure 1 is the starting point of the curved conveying path, the point where the gas ejected from the floating conveying means 40 begins to be applied to the first surface side of the substrate 10 being conveyed, and corresponds to the inflection point of the conveying path. Position P2 in Figure 1 is the end point of the curve of the curved conveying path, the point where the application of gas ejected from the floating conveying means 40 to the first surface side of the substrate 10 being conveyed ends, and corresponds to the inflection point of the conveying path. Position P3 in FIG. 1 is a point where application of the second coating liquid to the second surface of the substrate 10 being transported starts, and is a point opposite the coating means 50.

[0068] The distance from position P1 to position P3 and the distance from position P1 to position P2 can be determined, for example, from the positions corresponding to positions P1, P2, and P3 on the mechanical drawing (i.e., design drawing) of the equipment to be used and the scale of the mechanical drawing. At this time, positions P1 and P2 are the contact points of the transport path between the floating transport means 40 and the substrate 10.

[0069] In this step, from the viewpoint of more strongly restricting curling and increasing the coating accuracy of the second coating liquid, the wrap angle of the substrate with respect to the floating transport means is preferably 60° or more, more preferably 90° or more, and more preferably 120° or more. The upper limit of the wrap angle can be set to, for example, 210°. The wrap angle refers to the angle formed by the transport direction of the substrate at the start point of curvature of the substrate by the floating transport means and the transport direction of the substrate at the end point of curvature.

[0070] The floating amount of the substrate relative to the floating transport means used in this step is, for example, preferably 500 μm or less, more preferably 300 μm or less, from the viewpoint of stabilizing the transport of the substrate. The lower limit of the floating amount of the substrate may be determined depending on the thickness of the first coating liquid film, and may 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. The floating amount of the substrate relative to the floating transport means refers to the shortest distance between the substrate on which the first coating liquid film is not formed and the outer circumferential surface of the floating transport means. Here, the flying height can be measured by a laser displacement meter.

[0071] Examples of the floating transport means used in this step include the backup roll (backup body) 11 described in JP 2001-310148 A, the non-contact transport device described in JP 2004-256264 A (see, for example, FIG. 2), the web support device described in JP 2020-050455 A (see, for example, FIG. 6), and the transport device described in JP 2020-152570 A (see, for example, FIG. 9). Note that the various conditions related to the floating transport of the substrate described in these publications can also be applied to the method for manufacturing a laminate according to this embodiment, as long as they do not impair the effects of the method for manufacturing a laminate according to this embodiment.

[0072] -Second coating liquid- The second coating liquid used in this step is not particularly limited as long as it is a fluid liquid containing a solvent (or dispersion medium) and capable of forming the desired film, similar to the first coating liquid. The second coating liquid may be a coating liquid similar to the first coating liquid (for example, an aqueous coating liquid exemplified as the first coating liquid), or may be a coating liquid different from the first coating liquid.

[0073] From the viewpoint of efficiently suppressing curling at the width direction edges of the substrate that occurs during the drying process of the first coating liquid film formed on the first surface, it is preferable that the second coating liquid is a coating liquid similar to the first coating liquid (for example, an aqueous coating liquid exemplified as the first coating liquid).

[0074] -Thickness of the second coating liquid film- There are no particular limitations on the thickness of the second coating liquid film formed in this step, and it may be determined appropriately depending on the desired film. The thickness of the second coating liquid film is, for example, preferably 40 μm or more, more preferably 40 μm to 200 μm, and even more preferably 40 μm to 100 μm. The second coating liquid film is more likely to reduce curl at the width direction edges of the substrate as the thickness thereof becomes the same as that of the first coating liquid film. Therefore, it is preferable that the difference in thickness between the first and second coating liquid films is small, for example, preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 0.

[0075] -Width of the coating liquid film and width of the non-coated area- The width of the second coating liquid film in this step (ie, the coating width) is preferably set to be equal to the width of the first coating liquid film, from the viewpoint of satisfying the range of the positional misalignment amount described below. Furthermore, it is preferable that the width of the non-coated area (i.e., the width of the exposed portion of the substrate) when the second coating liquid film is formed on the second surface of the substrate is equal to the width of the non-coated area on the first surface side, in order to satisfy the range of the positional misalignment amount described below.

[0076] - Application of second coating liquid - In this step, the second coating liquid is applied by a known coating means. Examples of the coating means (for example, coating means 50 in FIG. 1) include various coating devices similar to those used to apply the first coating liquid. Among these, as the coating means in this step, a coating device using a slot coating method, more specifically an extrusion type die coater, is preferably used from the viewpoint of enabling high-definition coating.

[0077] - Positional deviation amount - In the method for producing a laminate according to this embodiment, 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 formed by the second coating liquid on the second surface is set to within 1 mm. From the viewpoint of effectively suppressing curling of the width direction edges of the substrate that occurs during the drying process of the first coating liquid film formed on the first surface, the amount of misalignment is more preferably within 0.5 mm. When the amount of misalignment is small as described above, the coating liquid film is formed in approximately the same area on both sides of the substrate, thereby suppressing curling at the widthwise ends of the substrate. In other words, if the amount of misalignment exceeds 1 mm, curling at the width direction end of the substrate may not be suppressed.

[0078] The amount of misalignment can be determined by the same method as that for measuring the width of the non-coated area described above. The amount of misalignment can be controlled by adjusting the widthwise positions of the coating unit that coats the first coating liquid on the first surface and the coating unit that coats the second coating liquid on the second surface. The amount of misalignment can also be controlled by adjusting the alignment of the roll member that contacts the substrate between coating the first coating liquid on the first surface and coating the second coating liquid on the second surface, thereby changing the widthwise position of the substrate.

[0079] [Step C] In step C, the substrate on which the first and second coating liquid films are formed is dried, that is, in this step, the first and second coating liquid films are dried.

[0080] -Drying- In this step, a known drying method is used to dry the coating liquid film. Specific examples of the drying means (for example, the drying means 60 in FIG. 1) include an oven, a hot air blower, an infrared (IR) heater, and the like.

[0081] The drying conditions in this step may be determined appropriately depending on the material of the substrate, the type of coating liquid film, and the like.

[0082] In this manner, films are formed on both sides of the substrate, and a laminate is obtained in which the film, substrate, and film are arranged in this order.

[0083] The thickness of the film obtained through step C is not particularly limited, and may be any thickness depending on the purpose, application, etc. In the method for manufacturing a laminate according to this embodiment, the thickness of the film formed on each side of the substrate is preferably 40 μm or more, more preferably 50 μm or more, and even more preferably 60 μm or more. There is no particular upper limit to the thickness of the film formed on both sides of the substrate, and it may be determined depending on the application, but it is, for example, 300 μm. The thickness of the film obtained through step C is measured in the same manner as in measuring the thickness of the coating liquid film.

[0084] [Other processes] Before step A and / or after step C, other steps may be included as necessary. The other processes are not particularly limited, and examples thereof include a pretreatment process carried out before forming a coating liquid film, and a posttreatment process carried out on the film formed on the first and second surfaces or on the laminate depending on the application of the laminate. 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 laminate, and a step of cutting the laminate.

[0085] The method for producing a laminate according to this embodiment is a method for forming films on both sides of a substrate that is being continuously transported, and is therefore suitable for producing laminates for applications that require high productivity. [Example]

[0086] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, details of each step, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. All "parts" are based on mass.

[0087] <Preparing the substrate> An aluminum substrate 1 (thermal conductivity: 230 W / m·K) with a width of 220 mm, a thickness of 15 μm, and a length of 300 m was prepared (abbreviated as AL1). An aluminum substrate 2 (thermal conductivity: 230 W / m·K) with a width of 220 mm, a thickness of 40 μm, and a length of 300 m was prepared (abbreviated as AL2). A PET (polyethylene terephthalate) substrate 1 (thermal conductivity: 0.23 W / m·K) measuring 220 mm in width, 75 μm in thickness, and 300 m in length was prepared (abbreviated as P1).

[0088] <Preparing the water-based coating solution> [Preparation of Water-Based Coating Solution A] The following components were mixed to prepare a water-based coating liquid A. Polyvinyl alcohol: 58 parts (CKS-50: Saponification degree 99 mol%, polymerization degree 300, Nippon Synthetic Chemical Industry Co., Ltd.) Daiichi Kogyo Seiyaku Co., Ltd. Cellogen PR: 24 copies Surfactant (Nihon Emulsion Co., Ltd., Emalex 710): 5 parts 913 parts of Art Pearl (registered trademark) J-7P water dispersion prepared by the following method

[0089] (Art Pearl J-7P water dispersion) Three parts of Emalex 710 (a nonionic surfactant manufactured by Nippon Emulsion Co., Ltd.) and three parts of sodium carboxymethylcellulose were dissolved in 49 parts of pure water. 20 parts of Art Pearl J-7P (silica composite cross-linked acrylic resin microparticles manufactured by Negami Chemical Industrial Co., Ltd.) were added to the resulting aqueous solution, and the mixture was dispersed for 15 minutes at 10,000 rpm (revolutions per minute) using an Ace Homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.) to obtain an aqueous dispersion of Art Pearl J-7P (particle concentration: 20% by mass). The silica composite crosslinked acrylic resin fine particles in the resulting aqueous dispersion had a true specific gravity of 1.20 and an average particle size of 6.5 μm.

[0090] [Preparation of Water-Based Coating Solution B] The following components were mixed and stirred with a dissolver (2000 rpm, 30 minutes) to prepare water-based coating solution B (dispersion A:dispersion B=25:75). The viscosity of water-based coating solution B was 20 mPa·s, and the average particle size was 0.108 μm. Dispersion A prepared by the following method: 132.1 parts Dispersion B prepared by the following method: 396.2 parts Boric acid (crosslinking agent): 2.94 parts Polyvinyl alcohol (7.3% by weight aqueous solution): 230.7 parts (Kuraray Co., Ltd., PVA 235, saponification degree 88%, polymerization degree 3500) Diethylene glycol monobutyl ether: 2.7 parts (Butycenol 20-P, KH Neochem Co., Ltd.) Ion-exchanged water: 93.5 parts Polyoxyethylene lauryl ether (surfactant): 0.49 parts (Emulgen 109P 10% by weight aqueous solution, HLB value 13.6, Kao Corporation) Ethanol: 41.4 parts

[0091] (Preparation of Dispersion A) The following components were mixed and dispersed ultrasonically, and then the dispersion was heated to 30°C and maintained for 8 hours to prepare Dispersion A. Fumed silica particles (inorganic particles): 299.6 parts (AEROSIL 300SF75, Nippon Aerosil Co., Ltd.) Ion-exchanged water: 900 parts ·Alphaine 83 (40.0% by mass aqueous solution): 300 parts (Dispersant, Taimei Chemical Industry Co., Ltd.)

[0092] (Preparation of Dispersion B) The following components were mixed and dispersed ultrasonically, and then the dispersion was heated to 30° C. and maintained for 8 hours to prepare Dispersion B. Fumed silica particles (inorganic particles): 225.2 parts (AEROSIL 300SF75, Nippon Aerosil Co., Ltd.) Ion-exchanged water: 600 parts Cationic polymer A (25% by weight aqueous solution) having the following structure: 90 parts

[0093] [ka]

[0094] [Example 1] In an apparatus configured as shown in Figure 1, coating of aqueous coating liquid A (first coating liquid) was initiated on a first side of an aluminum substrate (AL1) being continuously conveyed, and then, when the solids concentration of the coating liquid film of aqueous coating liquid A formed on the first side reached the value shown in Table 1 below, coating of aqueous coating liquid A (second coating liquid) was initiated on the second side, forming coating liquid films of aqueous coating liquid A on both sides of the substrate. Thereafter, the aluminum substrate with coating liquid films of aqueous coating liquid A formed on both sides thereof was passed through drying means adjusted to 60°C, whereby the coating liquid films were dried. In this manner, films were formed on both sides of the aluminum substrate, and a laminate composed of the film, the aluminum substrate, and the film was obtained. Here, the water-based coating liquid A was applied to the first surface in the region where the aluminum substrate was wrapped around the backup roll 20, and the water-based coating liquid A was applied to the second surface in the region where the aluminum substrate was curved along the outer circumferential surface of the roll-shaped floating transport means. The transport speed of the substrate was 20 m / min. Other conditions, such as the radius of curvature of the curved transport path, the length of the curved transport path, and the ratio of the distance from the start of curvature to the start of application of the second coating liquid relative to the length of the curved transport path, were the values ​​shown in Table 1 below. The floating amount of the substrate from the outer peripheral surface of the roll-shaped floating transport means was set to 200 μm.

[0095] [Examples 2 to 13] A laminate was obtained in the same manner as in Example 1, except that the solid content concentration of the first coating liquid film when the second coating liquid was applied, the radius of curvature of the curved transport path, the distance of the curved transport path, and the ratio of the distance from the start point of curvature to the start point of application of the second coating liquid relative to the distance of the curved transport path were appropriately changed as shown in Table 1 below.

[0096] [Examples 14 and 15] A laminate was obtained in the same manner as in Examples 1 and 2, except that the water-based coating liquid A was changed to the water-based coating liquid B.

[0097] [Comparative Example 1] A laminate was obtained in the same manner as in Example 1, except that after starting the application of the water-based coating liquid A to the first surface, the coating liquid film of the water-based coating liquid A formed on the first surface was dried (after the solid content concentration of the coating liquid film of the water-based coating liquid A reached 100 mass %), and then starting the application of the water-based coating liquid A to the second surface.

[0098] [Examples 16 and 17] Films were formed on both sides of the substrate in the same manner as in Example 1, to obtain a laminate, except that the type of substrate was changed as shown in Table 2 below. In Examples 16 and 17, the displacement F of the substrate when the application of the water-based coating liquid A to the second surface was started, and the solid content concentration of the coating liquid film of the water-based coating liquid A formed on the first surface are shown in Table 2 below. In Examples 16 and 17, the positional deviation between the width of the first coating liquid film on the first surface (i.e., the coating liquid film made of water-based coating liquid A formed on the first surface) and the width of the second coating liquid film made of the second coating liquid on the second surface (i.e., the coating liquid film made of water-based coating liquid A formed on the second surface) is shown in Table 2 below.

[0099] [Examples 18 to 20] Films were formed on both sides of the aluminum substrate in the same manner as in Example 1, to obtain a laminate, except that the thickness of the first coating liquid film formed on the first side and the thickness of the second coating liquid film formed on the second side were appropriately changed as shown in Table 2 below. In Examples 18 to 20, the displacement F of the aluminum substrate when starting to apply the water-based coating liquid A to the second side, and the solid content concentration of the coating liquid film of the water-based coating liquid A formed on the first side are shown in Table 2 below. In Examples 18 to 20, the positional deviation between the width of the first coating liquid film on the first surface (i.e., the coating liquid film made of water-based coating liquid A formed on the first surface) and the width of the second coating liquid film made of the second coating liquid on the second surface (i.e., the coating liquid film made of water-based coating liquid A formed on the second surface) is shown in Table 2 below.

[0100] [Various measurements] The solid content concentration of the coating liquid film formed on the first surface of the aluminum substrate was measured by the method described above. In addition, the radius of curvature of the curved transport path, the distance of the curved transport path, and the ratio of the distance from the start point of curvature to the start point of application of the second coating liquid relative to the distance of the curved transport path were also measured using the methods described above. Furthermore, the amount of positional deviation 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 was also measured by the method already described. Note that 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 made of water-based Coating Liquid A formed on the first surface) and the width of the dry film of the second coating liquid film made of the second coating liquid on the second surface (i.e., the dry film of the coating liquid film made of water-based Coating Liquid A formed on the second surface) was measured only for Comparative Example 1. This measurement was carried out in the same manner as for 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. The results are shown in Tables 1 and 2.

[0101] [Evaluation of curl at the width direction edge of the substrate] The laminate obtained in each example was evaluated for curl at the widthwise edge. First, for the laminate obtained in each example, the curl amount C at the width direction end portion is measured as shown in Fig. 2. Fig. 2 is a schematic diagram of a main part of a cross section of a curled laminate cut along the width direction. As shown in FIG. 2, the amount of lift at the widthwise end of the laminate (i.e., the substrate) is measured with a ruler when the center of the laminate is used as a reference, and this is defined as the curl amount C at the widthwise end of the laminate. Based on the obtained curl amount C value, evaluation was performed according to the following criteria. -Evaluation criteria- G1: The curl amount C is 2 mm or less G2: The curl amount C is more than 2 mm and less than 5 mm G3: Curl amount C exceeds 5 mm The results are shown in Tables 1 and 2.

[0102] [Table 1]

[0103] [Table 2]

[0104] As is clear from Tables 1 and 2, the manufacturing method of the laminate of the example reduces the amount of misalignment, and the obtained laminate also has less curl. Furthermore, in the laminates obtained in the examples, the positional deviation 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 confirmed to be within 0.7 mm. As described above, it is presumed that the laminates obtained in the examples have reduced curling because the dry films are formed in almost the same region on the first and second surfaces of the substrate. On the other hand, as is clear from Table 1, in the laminate manufacturing method of Comparative Example 1, the amount of misalignment was large (that is, the amount of misalignment in the dry film was large), and the curl of the laminate was also large.

[0105] [Explanation of symbols] 10 Strip-shaped substrate (transport path) 20 Backup Roll 30 First application means 40 Floating conveyance means 50 Second application means 60 Drying means P1 Starting point of curve of curved transport path P2 End point of curve of curved transport path P3 Starting point of application of second coating liquid

[0106] The disclosure of Japanese Patent Application No. 2020-210736, filed on December 18, 2020, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. a step of starting application of a first coating liquid to a first surface of a substrate being continuously transported on a transport path, and starting application of a second coating liquid to a second surface of the substrate opposite to the first surface while the solid content concentration of the first coating liquid film formed by the first coating liquid is 40% by mass to 80% by mass; the second coating liquid is applied to the second surface in a region where the substrate is conveyed along the curved conveyance path while pressure is applied to the first surface side by gas; A method for manufacturing a laminate, wherein the amount of positional misalignment between the width of a first coating liquid film on the first surface and the width of a 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. 3. The method for producing a laminate according to claim 1, wherein the first coating liquid film and the second coating liquid film have a thickness of 40 μm or more.

4. The method for producing a laminate according to any one of claims 1 to 3, wherein the curved transport path has a radius of curvature of 100 mm to 500 mm.

5. The method for producing a laminate according to any one of claims 1 to 4, wherein the length of the curved transport path is 350 mm to 1750 mm.

6. The method for producing a laminate according to any one of claims 1 to 5, wherein a distance from a curvature start point of the curved transport path to a coating start point of the second coating liquid is 50±25% of the distance of the curved transport path.

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