Coating device, coating method, and laminate manufacturing method

Abstract

An object of the present invention is to provide a coating device that can suppress deterioration in film thickness accuracy in lamination and has a wide process window that can suppress deterioration in film thickness accuracy. [Solution] A coating device comprising a coating unit that forms a coating of liquid resin on a first film, and a laminating unit that bonds a second film to the first film via the coating, wherein the laminating unit has a pair of rollers consisting of a first roller having an outer periphery made of metal and a second roller having an outer periphery made of an elastic material, and a fixing mechanism that fixes each roller so as to maintain the distance between the pair of rollers, and the laminating unit bonds the first film on which the coating has been formed and the second film by the pair of rollers with the distance maintained by the fixing mechanism.

Description

[Technical field]

[0001] The present invention relates to a coating device, a coating method, and a method for producing a laminate. [Background technology]

[0002] Conventionally, in the production of film products such as optical films, films that serve as functional layers are bonded together with an adhesive layer.

[0003] For example, Patent Document 1 describes a method for manufacturing a light reflective film in which a pair of rollers consisting of a rubber pressure roller and a metal heating roller is used, and a second film is passed between the pair of rollers onto a first film on which a coating film that serves as an adhesive layer has been formed, thereby bonding the second film to the first film via the coating film.

[0004] The manufacturing method of Patent Document 1 employs a wet lamination process in which a second film is bonded to a first film via a coating film in a wet state. In conventional wet lamination processes using rubber rollers called nip rollers, not limited to the manufacturing method of Patent Document 1, the distance between the rubber roller and the metal roller is changed according to the change in the contact area between the rollers during coating in order to keep the pressure of the rubber roller against one roller (a metal roller in Patent Document 1) constant. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-115157 A Summary of the Invention [Problem to be solved by the invention]

[0006] Meanwhile, various film products having multiple functional layers such as optical films require high uniformity in the thickness of the adhesive layer that bonds the functional layers together. One method for satisfying this requirement is to form a coating film having a uniform thickness, i.e., a coating film with high thickness accuracy, in a coating process for forming the coating film.

[0007] However, according to the inventors' investigation, the wet lamination process using a rubber roller that changes the distance from one roller has the problem that the coating film passing between the rollers is partially blocked by the roller, causing a liquid pool just before the roller, reducing the thickness of the coating film after passing through the roller (see FIG. 4). This causes a decrease in the film thickness accuracy achieved in the coating process.

[0008] Next, in order to suppress the above-mentioned decrease in film thickness accuracy, it is considered to use a pair of rollers in which both rollers are metal rollers. Metal rollers are rollers whose outer circumferential surfaces are less likely to deform than rubber rollers. Therefore, it is considered that a pair of rollers made of metal rollers is easy to maintain a constant gap between the outer circumferential surfaces of the metal rollers, and easy to maintain film thickness accuracy. However, according to the study by the present inventors, the wet lamination process using a pair of metal rollers has a problem that the range of the gap in which film thickness accuracy can be maintained is narrow, that is, the process window is narrow.

[0009] In view of the above problems, the present invention aims to provide a coating device and a coating method that can suppress a decrease in film thickness accuracy in lamination using a liquid resin and have a wide process window that can suppress a decrease in film thickness accuracy. [Means for solving the problem]

[0010] The coating device according to the present invention comprises: a coating unit that forms a coating film of a liquid resin on a first film, and a laminating unit that bonds a second film to the first film via the coating film; the laminating unit has a pair of rollers consisting of a first roller having an outer periphery made of metal and a second roller having an outer periphery made of an elastic member, and a fixing mechanism that fixes each roller so as to maintain a distance between the pair of rollers; The laminating unit bonds the first film, on which the coating film has been formed, to the second film by the pair of rollers, while the distance is maintained by the fixing mechanism.

[0011] In the coating device of the present invention, when the first film and the second film (passing object) on which the coating film is formed pass between the first roller and the second roller, a pressing force from the film according to the thickness of each film and the thickness of the coating film is applied to the outer periphery of each roller. Since each roller is fixed as described above, the outer periphery of the second roller is easily deformed according to the pressing force. That is, the outer periphery of the second roller is deformed in the radial direction of the roller according to the thickness of the passing object. This suppresses the occurrence of a liquid pool just before the roller, and the deterioration of the film thickness accuracy during lamination can be suppressed. In addition, in the coating device of the present invention, the deformation of the outer periphery of the second roller as described above widens the distance range of the pair of rollers in which the deterioration of the film thickness accuracy can be suppressed, that is, the process window is wide.

[0012] A coating device according to one aspect of the present invention comprises: The fixing mechanism is configured to fix each roller in a state in which the outer peripheral surface of the second roller is pressed against the outer peripheral surface of the first roller via the first film and the second film on which the coating is formed.

[0013] In the coating device of the above aspect, because the outer circumferential portion of the second roller deforms as described above, even when the outer circumferential surface of the second roller is pressed against the outer circumferential surface of the first roller, deterioration in film thickness accuracy can be suppressed, and the process window in this state is wide.

[0014] A coating device according to one aspect of the present invention comprises: Let the radii of the first roller and the second roller when they are not in contact with each other be r1 and r2, respectively. Let the total thickness of the thickness of the first film, the thickness of the second film, and the thickness of the coating film be t. When the distance from the central axis of the first roller to the central axis of the second roller is d, the first roller and the second roller are fixed by the fixing mechanism at a position where d ≤ r1 + r2 + t.

[0015] In the coating apparatus of the above aspect, since the outer peripheral portion of the second roller is deformed as described above, even in a state where the outer peripheral surface of the second roller is in contact with the outer peripheral surface of the first roller, that is, a state defined by d = r1 + r2 + t, or a state where the central axes of the rollers are closer to each other than this state, that is, a state defined by d < r1 + r2 + t, it is possible to suppress a decrease in film thickness accuracy.

[0016] A coating apparatus according to an aspect of the present invention the second roller is a rubber roller having an outer peripheral portion made of rubber.

[0017] If the second roller is a rubber roller, the above-described operation can be easily obtained, and a decrease in film thickness accuracy can be further suppressed.

[0018] A coating method according to the present invention includes a coating step of forming a coating film of a liquid resin on a first film, and a laminating step of laminating a second film on the first film through the coating film, In the laminating step, a pair of rollers for laminating the second film on the first film, one of which is a first roller having an outer peripheral portion made of metal and the other of which is a second roller having an outer peripheral portion made of an elastic member, are used, and each roller is fixed so as to maintain the distance between the pair of rollers, and the first film and the second film on which the coating film is formed are passed between the first roller and the second roller between which the distance is maintained.

[0019] As described above, the coating method of the present invention can suppress a decrease in film thickness accuracy during lamination, and also provides a wide process window.

[0020] The method for producing a laminate according to the present invention comprises the steps of: Any of the above coating methods; and a curing step of curing the coating film to form an adhesive layer, thereby obtaining a laminate in which the second film is laminated to the first film via the adhesive layer.

[0021] According to this configuration, a laminate having an adhesive layer with high thickness accuracy can be obtained. Effect of the Invention

[0022] As described above, according to the present invention, it is possible to suppress a decrease in film thickness accuracy in lamination via a liquid resin, and it is possible to provide a coating device and a coating method having a wide process window that can suppress a decrease in film thickness accuracy. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram of a coating device according to an embodiment. [Diagram 2] 2 is a schematic enlarged view of a pair of rollers of a wet laminating unit included in the coating device of FIG. 1. [Diagram 3] 3 is a schematic diagram of a fixing mechanism for fixing the pair of rollers in FIG. 2. [Figure 4] FIG. 13 is a diagram showing a state in which a liquid pool occurs immediately before the roller. [Diagram 5] 1 is a graph showing the evaluation results of Example 1. [Figure 6] 1 is a graph showing the evaluation results of Comparative Example 1. [Figure 7] 13 is a graph showing the evaluation results of Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, a coating device according to an embodiment of the present invention will be described with reference to the drawings, while illustrating a laminate manufacturing apparatus including the coating device.

[0025] As shown in FIG. 1, the laminate manufacturing apparatus 100 of this embodiment includes a coating device 1 having a coating section 10 that applies a photocurable adhesive composition to form a coating film C of a predetermined thickness on a first film F1, and a wet lamination section 20 that bonds a second film F2 to the first film F1 via the coating film C, and further includes a curing section 30 that irradiates active energy rays to cure the coating film C to form an adhesive layer A.

[0026] The adhesive composition of this embodiment is a liquid containing a photocurable resin. More specifically, the adhesive composition of this embodiment has a viscosity of 0.001 to 100 Pa·s. The viscosity of the adhesive composition is measured using a rheometer (manufactured by HAAKE). The measurement conditions are a shear rate of 0.1 [1 / s] and a temperature of 20° C. The coating liquid used to form the coating film C may be made of a photocurable liquid resin.

[0027] The coating apparatus 1 through the manufacturing apparatus 100 are configured to transport the first film F1 and the second film F2 at a speed of 1 to 100 m / min.

[0028] The coating section 10 of this embodiment is disposed upstream of the wet lamination section 20, and is configured to coat the adhesive composition on a strip-shaped first film F1 being transported by a guide roller 40. The coating section 10 includes a die 11 for coating the adhesive composition. The die 11 has a slot 12 that serves as an outlet for discharging the adhesive composition. That is, the coating section 10 of this embodiment is a die coater. The die 11 is installed so that the width of the slot 12 is parallel to the axis of the guide roller 40. The die 11 is also installed so that the slot 12 is close to the first film F1 being transported (running).

[0029] The coating unit 10 is configured to discharge the adhesive composition at a constant flow rate from the slot 12. Here, a constant flow rate means that during steady operation, the value calculated by [maximum flow rate - minimum flow rate] / average flow rate is 0.2 or less, preferably 0.1 or less. Here, the flow rate means the mass flow rate.

[0030] The height of slot 12 (opening distance in a direction perpendicular to the width direction of slot 12) is preferably adjustable at least in the range of 0.1 μm to 1000 μm. Also, the width of slot 12 is preferably adjustable in the range of 200 mm to 5000 mm. Note that the height of slot 12 means the average height of the heights of 9 points that divide slot 12 into 10 equal parts in the width direction.

[0031] The manufacturing apparatus 100 of this embodiment is configured to transport the first film F1 along a horizontal plane from after the coating film C is formed on the first film F1 until the coating film C is cured in the curing section 30. More specifically, the manufacturing apparatus 100 includes a roller (not shown) for transporting the first film F1 along a horizontal plane from a position where the outer surface of the first film F1 separates from the outer circumferential surface of the guide roller 40 until the coating film C becomes an adhesive layer A in the curing section 30. The first film F1 may be transported from the upstream side to the downstream side so as to be inclined upward or downward with respect to the horizontal plane, or may be transported along a vertical plane.

[0032] 2, the wet laminating unit 20 of this embodiment has a pair of rollers for laminating a second film F2 to a first film F1 via a coating film C. The pair of rollers includes a metal roller 21 as the first roller and a rubber roller 22 as the second roller.

[0033] The metal roller 21 has a shaft portion 211 including a central axis P1, and an outer peripheral portion 212 formed from the shaft portion 211 to the outer peripheral surface. In the metal roller 21 of this embodiment, both the shaft portion 211 and the outer peripheral portion 212 are made of metal. The rubber roller 22 has a shaft portion 221 including a central axis P2, and an outer peripheral portion 222 formed from the shaft portion 221 to the outer peripheral surface. In the rubber roller 22 of this embodiment, at least the outer peripheral portion 222 is made of rubber. The metal roller 21 and the rubber roller 22 are arranged so that their respective central axes (central axis P1 and central axis P2) are parallel to each other. In the following, the first direction, which is perpendicular to the direction in which the central axis of each roller extends and is the direction in which the line segment connecting the central axes of each roller extends, is referred to as the up-down direction D1, and the second direction, which is perpendicular to both the direction in which the central axis of each roller extends and the up-down direction D1, is referred to as the front-rear direction D2.

[0034] The pair of rollers are configured to rotate in a direction in which the first film F1 and the second film F2 (passing object) on which the coating film C has been formed are drawn between the rollers while the outer surface of the first film F1 is in contact with the outer surface of one roller and the outer surface of the second film F2 is in contact with the outer surface of the other roller. In this embodiment, the metal roller 21 and the rubber roller 22 are aligned in the up-down direction D1, and the metal roller 21 is arranged so as to support the outer surface of the first film F1 from below, and the rubber roller 22 is arranged on the opposite side of the metal roller 21 across the passing object. Note that the rubber roller 22 may be arranged so as to support the outer surface of the first film F1 from below, and the metal roller 21 may be arranged on the opposite side of the rubber roller 22 across the passing object.

[0035] The wet laminating unit 20 of this embodiment supports the film (specifically, the second film F2) supported on the outer circumferential surface of the rubber roller 22 so that it is partially wound around the outer circumferential surface. The coating device 1 may also include a means (e.g., a roller) for applying tension to the second film F2 that is about to come into contact with the rubber roller 22 in the opposite direction to the traveling direction. This allows the second film F2 to be sufficiently pressed against the outer circumferential surface of the rubber roller 22.

[0036] 2 and 3, the wet laminating unit 20 of this embodiment has a fixing mechanism that adjusts the distance d between the central axis P1 of the metal roller 21 and the central axis P2 of the rubber roller 22, and fixes each roller in the adjusted position. In other words, the fixing mechanism is configured to fix each roller so as to maintain the distance d that has been adjusted as desired.

[0037] As shown in FIG. 3, the fixing mechanism of this embodiment includes a cylinder (not shown) which acts as a propulsion unit that applies a propulsive force to one roller to move the one roller toward the other roller, and an adjustment unit 23 which adjusts the distance of the other roller relative to the one roller.

[0038] The cylinder may be connected to the metal roller 21 or to the rubber roller 22. The cylinder in this embodiment is connected to the shaft portion 221 of the rubber roller 22. The cylinder is configured to continuously apply a propulsive force toward the metal roller 21 to the rubber roller 22 at least when an object is passed between the rollers.

[0039] The adjustment part 23 of this embodiment includes a first unit 23a having an inclined part 231 inclined with respect to the front-rear direction D2 and moving parallel to the front-rear direction D2, and a second unit 23b having a contact part 232 connected to one of the rollers and abutting against the inclined part 231 by the propulsion force. When the first unit 23a moves parallel to either direction in the front-rear direction D2, the second unit 23b abutting against the inclined part 231 at the contact part 232 can move in both directions in the up-down direction D1 while being guided by the inclined part 231.

[0040] The inclined portion 231 has an inclined surface that is inclined from one side to the other side in the front-rear direction D2 and faces upward. The inclined surface in this embodiment is inclined downward from the downstream side to the upstream side in the front-rear direction D2. On the other hand, the abutting portion 232 has an abutting surface that is inclined from one side to the other side in the front-rear direction D2 and faces downward so as to abut against the inclined surface. The abutting surface in this embodiment is inclined upward from the upstream side to the downstream side in the front-rear direction D2 so as to correspond to the inclination of the inclined surface. As shown in (a) and (b) of FIG. 3, the fixing mechanism of this embodiment can displace the inclined surface relative to the contact surface to one side in the front-rear direction D2 (forward in FIG. 3(b)) by sliding the second unit 23b, which presses the inclined surface with the contact surface by the contact surface, in one side in the front-rear direction D2 (forward in FIG. 3(b)). On the other hand, as shown in (a) and (c) of FIG. 3, the fixing mechanism of this embodiment can displace the inclined surface relative to the contact surface to the other side in the second direction D2 by sliding the second unit 23b in the other side in the front-rear direction D2 (rear in FIG. 3(c)). In addition, the fixing mechanism of this embodiment can move the rubber roller 22 in a direction that moves the central axis P2 of the rubber roller 22 closer to the central axis P1 of the metal roller 21 (a direction that reduces the distance d, downward in FIG. 3(c)). The first unit 23a is configured to be fixed from after the adjustment of the distance d until the end of lamination.

[0041] As shown in FIG. 2, when the radius of the metal roller 21 and the radius of the rubber roller 22 are r1 and r2, respectively, when they are not in contact with each other, and the total thickness of the first film F1, the second film F2, and the coating film C is t, the fixing mechanism of this embodiment is configured to fix the rubber roller 22 at a position where d≦r1+r2+t is satisfied. In this case, the fixing mechanism can fix each roller in a state where the outer circumferential surface of the rubber roller 22 is pressed against the outer circumferential surface of the metal roller 21 via the first film F1 and the second film F2 on which the coating film C is formed. In addition, since d≦r1+r2+t is satisfied, there is substantially no gap between the coating film C and the second film F2, and each film can be bonded together without causing the second film F2 to rise up from the coating film C (a factor that causes unevenness on the surface of the second film F2).

[0042] Furthermore, when the radius of the rubber roller 22 when pressed to the limit is r2', the fixing mechanism may be configured to fix the rubber roller 22 at a position where d≧r1+r2'+t is satisfied. This prevents the coating film C passing between the rollers from being blocked by the rollers, and prevents a decrease in film thickness accuracy during lamination. Note that the present invention is not limited to the embodiment that satisfies the above inequality.

[0043] Here, the state in which each roller is fixed so as to satisfy d=r1+r2+t is defined as the reference position of the central axis P1 and the central axis P2 (positional relationship of the central axes in FIG. 3(a)), the direction in which the central axis P2 of the rubber roller 22 approaches the central axis P1 of the metal roller 21 from the reference position is defined as the positive direction (positional relationship of the central axes in FIG. 3(b)), and the direction in which the central axis P2 of the rubber roller 22 moves away from the central axis P1 of the metal roller 21 from the reference position is defined as the negative direction (positional relationship of the central axes in FIG. 3(c)). In this definition, the fixing mechanism of this embodiment is configured to be able to adjust the distance d so that the central axis P1 and the central axis P2 are in a positional relationship on the positive side up to +2000 μm from the reference position, with +1000 μm being preferable, and +500 μm being more preferable. In addition, the fixing mechanism of this embodiment is configured to be able to adjust the distance d so that the central axis P1 and the central axis P2 are in a negative positional relationship of -2000 μm from the reference position, with this value being preferably -1000 μm, and more preferably -500 μm.

[0044] The wet lamination section 20 of this embodiment is particularly excellent at suppressing deterioration in film thickness accuracy when the distance d is adjusted to achieve the positive side positional relationship so that the outer peripheral surface of the rubber roller 22 is pressed against the outer peripheral surface of the metal roller 21 through the passing object.

[0045] The diameter of the metal roller 21 is preferably 30 to 1000 mm. The diameter of the rubber roller 22 is preferably 50 to 1000 mm. The diameter of the outer periphery 222 of the rubber roller 22, that is, the thickness of the rubber part of the rubber roller 22, is preferably 1 to 100 mm.

[0046] The elastic modulus of the rubber constituting the outer circumferential portion 222 of the rubber roller 22 is 1 to 1×10 7 kg / m s 2 Preferably, the concentration is 1×10 3 ~1×10 4 The density of the rubber is more preferably 800 to 2000 kg / m 3The elastic modulus of the rubber can be measured by a compression test (method D) specified in JIS K 6254. The density of the rubber can be measured by an underwater displacement method.

[0047] The rubber composition for forming the outer periphery 222 of the rubber roller 22 may contain a thermosetting elastomer, which is rubber, or may contain a thermoplastic elastomer. For example, the rubber composition may contain rubber such as natural rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, acrylic rubber, nitrile rubber, acrylonitrile butadiene rubber, chloroprene rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, silicone rubber, and fluororubber. In addition, the rubber composition may contain a styrene-based thermoplastic elastomer, an acrylic-based thermoplastic elastomer, a polyolefin-based thermoplastic elastomer, a polyvinyl chloride-based thermoplastic elastomer, a polyurethane-based thermoplastic elastomer, a polyester-based thermoplastic elastomer, and a polyamide-based thermoplastic elastomer. That is, the elastic member for forming the outer periphery of the first roller may be a thermosetting elastomer, which is rubber, or may be a thermoplastic elastomer, and is preferably rubber (thermosetting elastomer).

[0048] The curing section 30 of this embodiment is configured to irradiate ultraviolet rays as active energy rays. In the curing section 30, a laminate in which the second film F2 is bonded to the first film F1 by the adhesive layer A is obtained.

[0049] Next, a coating method and a laminate manufacturing method according to one embodiment of the present invention will be described by taking as an example a method using the above-mentioned coating apparatus 1 and laminate manufacturing apparatus 100.

[0050] The method for manufacturing the laminate of this embodiment includes a coating process including a coating step of applying a photocurable adhesive composition to a first film F1 to form a coating film C of a predetermined thickness, and a wet lamination step of bonding a second film F2 to the first film F1 via the coating film C, and further includes a curing step of curing the coating film C to form an adhesive layer A.

[0051] Examples of the first film F1 and the second film F2 include optical films such as polarizing films, polarizer protective films, retardation films, surface-treated films, brightness-enhancing films, and PET separators, as well as various other films. Each of the first film F1 and the second film F2 may be in a long shape capable of forming a roll. Each of the first film F1 and the second film F2 may be in the form of a sheet obtained by cutting from a long film. The thickness of the first film F1 and the second film F2 is preferably 10 to 500 μm.

[0052] In the coating method or laminate manufacturing method of this embodiment, the first film F1 and the second film F2 are transported at a speed of 1 to 100 m / min.

[0053] In this embodiment, the viscosity of the adhesive composition is set to 0.001 to 100 Pa·s.

[0054] In the coating step of this embodiment, a coating film C having a coating thickness of 0.1 μm to 1000 μm is formed by a die coater (coating unit 10) equipped with a die 11. The coating thickness is determined as an average thickness obtained by measuring the thickness at the center and both ends in the width direction at any 10 points in the conveyance direction, and averaging these thicknesses at 30 points.

[0055] In the method for producing a laminate of this embodiment, the first film F1 is transported along a horizontal plane from after the coating film C is formed on the first film F1 until the coating film C is cured in the curing section 30. More specifically, in the method for producing a laminate of this embodiment, the first film F1 is transported along a horizontal plane from a position where the outer surface of the first film F1 leaves the outer circumferential surface of the guide roller 40 until the coating film C becomes an adhesive layer A in the curing section 30. Note that the first film F1 may be transported from the upstream side to the downstream side so as to be inclined upward or downward with respect to the horizontal plane, or may be transported along a vertical plane.

[0056] In the wet lamination process of this embodiment, the outer surface of the first film F1 is brought into contact with the outer surface of one roller, and the outer surface of the second film F2 is brought into contact with the outer surface of the other roller, while the passing object is drawn between the rollers, and the second film F2 is bonded to the first film F1 via the coating film C. At this time, the rollers are fixed so as to maintain the distance d between the pair of rollers, and the first film F1 and the second film F2 on which the coating film C is formed are passed between the metal roller 21 and the rubber roller 22, with the distance d maintained. Then, in the wet lamination process, the passing object is pressed against the outer surface of the rubber roller 22, thereby deforming the outer surface of the rubber roller 22 in the radial direction, while the second film F2 is bonded to the first film F1 via the coating film C. Furthermore, in this embodiment, the passing object is passed between the rollers while the film supported on the outer surface of the rubber roller 22 (specifically, the second film F2) is supported so as to be partially wound around the outer surface of the rubber roller 22.

[0057] In the wet lamination process, the rubber roller 22 may be fixed at a position where d≦r1+r2, and the object may be passed between the rollers. In this case, the outer circumferential surface of the rubber roller 22 may be pressed against the outer circumferential surface of the metal roller 21 through the first film F1 and the second film F2 on which the coating film C is formed, and the object may be passed between the rollers.

[0058] In the wet lamination process, it is preferable to pass the object between the rollers in a state where the central axis P1 and the central axis P2 are in a positive positional relationship of +2000 μm from the reference position. In the wet lamination process, the object may be passed between the rollers in a negative positional relationship of -2000 μm from the reference position.

[0059] In the curing step of the present embodiment, ultraviolet rays are applied as active energy rays to cure the coating film C of the passed material to form an adhesive layer A. That is, in the curing step, a laminate in which the second film F2 is bonded to the first film F1 by the adhesive layer A is produced.

[0060] The adhesive composition of the present embodiment forms a pressure-sensitive adhesive sheet by being irradiated with light. The adhesive composition contains, for example, a monomer group containing a (meth)acrylic monomer and / or a partial polymer of the monomer group. The content of the (meth)acrylic component, i.e., the (meth)acrylic monomer and its partial polymer, in the adhesive composition may be 50% by mass or more, 60% by mass or more, 70% by mass or more, or 80% by mass or more. In this case, an acrylic pressure-sensitive adhesive sheet containing a (meth)acrylic polymer and its crosslinked product as the main components can be formed. However, the adhesive composition is not limited to the above examples. In this specification, (meth)acrylic means acrylic and methacrylic. (Meth)acrylate means acrylate and methacrylate.

[0061] Examples of the (meth)acrylic monomer include (meth)acrylic acid alkyl esters, which are condensates of (meth)acrylic acid and alcohols having a carbon chain with 1 to 20 carbon atoms. The number of carbon atoms in the carbon chain may be 7 or less, 6 or less, 5 or less, or 4 or less. The carbon chain may be linear or branched. Examples of the (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and the like. (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate (lauryl (meth)acrylate), n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate and octadecyl (meth)acrylate. The (meth)acrylic acid alkyl ester is preferably n-butyl (meth)acrylate. The adhesive composition may contain only one type of the (meth)acrylic monomer, or may contain two or more types.

[0062] In 100 parts by mass of the monomer group, the amount of the (meth)acrylic acid alkyl ester may be, for example, 40 parts by mass or more, 50 parts by mass or more, 60 parts by mass or more, 70 parts by mass or more, 80 parts by mass or more, 85 parts by mass or more, 90 parts by mass or more, or 95 parts by mass or more. In calculating the amount of a specific monomer, the mass of the partially polymerized product is converted into the mass of each monomer before polymerization.

[0063] The monomer group may include a carboxyl group-containing monomer. The carboxyl group-containing monomer may be the (meth)acrylic monomer, in other words, the (meth)acrylic monomer may contain a carboxyl group. Examples of the carboxyl group-containing monomer include the (meth)acrylic monomers having an alkyl group with 6 or less carbon atoms, such as carboxyethyl (meth)acrylate and carboxypentyl (meth)acrylate, unsaturated monocarboxylic acids having 6 or less carbon atoms (5 or less or 4 or less), such as (meth)acrylic acid and crotonic acid, and unsaturated dicarboxylic acids having 6 or less carbon atoms (5 or less), such as itaconic acid, maleic acid, and fumaric acid. In 100 parts by mass of the monomer group, the amount of the carboxyl group-containing monomer may be, for example, 10 parts by mass or less, 9 parts by mass or less, 8 parts by mass or less, 7 parts by mass or less, 6 parts by mass or less, 5 parts by mass or less, 4.8 parts by mass or less, 4 parts by mass or less, 3 parts by mass or less, 2 parts by mass or less, 1 part by mass or less, or 0.5 parts by mass or less. The lower limit of the amount is, for example, 0.1 parts by mass or more, and in some cases, may be 0.5 parts by mass or more. The monomer group may not contain a carboxyl group-containing monomer.

[0064] The monomer group may include a hydroxyl group-containing monomer. The hydroxyl group-containing monomer may be the (meth)acrylic monomer, in other words, the (meth)acrylic monomer may contain a hydroxyl group. The hydroxyl group-containing monomer may contribute to improving the cohesive strength of the pressure-sensitive adhesive sheet. Examples of the hydroxyl group-containing monomer include condensates of (meth)acrylic acid and a dihydroxy compound having 12 or less carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate, and dihydroxy compounds containing a cycloalkyl group, such as (meth)acrylic acid and (4-hydroxymethylcyclohexyl)-methylacrylate. The hydroxyl group-containing monomer is preferably 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate. The amount of the hydroxyl group-containing monomer in 100 parts by mass of the monomer group may be, for example, 20 parts by mass or less, 15 parts by mass or less, 10 parts by mass or less, 7.5 parts by mass or less, 5 parts by mass or less, 4 parts by mass or less, 3 parts by mass or less, 2 parts by mass or less, 1 part by mass or less, or 0.5 parts by mass or less. The lower limit of the amount may be, for example, 0.01 parts by mass or more, 0.03 parts by mass or more, or 0.05 parts by mass or more. The monomer group may not contain a hydroxyl group-containing monomer.

[0065] In the adhesive composition, each of the above-mentioned monomers may be contained as a partial polymer. The partial polymer may be either a homopolymer or a copolymer. The partial polymer may appropriately increase the viscosity of the adhesive composition, thereby contributing to the stable formation of the coating film C.

[0066] The adhesive composition usually contains a photopolymerization initiator, such as a photoradical generator that generates radicals when exposed to visible light and / or ultraviolet light having a wavelength shorter than 450 nm.

[0067] Examples of the photopolymerization initiator include benzoin ethers such as benzoin methyl ether and benzoin isopropyl ether; substituted benzoin ethers in which hydrogen atoms on the benzene ring of the benzoin ethers are substituted with alkoxy groups; substituted acetophenones in which the α hydrogen atoms of acetophenone are substituted with alkoxy groups, such as 2,2-diethoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; α-hydroxyalkylphenones such as 1-hydroxycyclohexyl-phenyl ketone; 2-methyl-2-hydroxypropionyl ether; Substituted alpha-ketols in which the alpha hydrogen of acetophenone is replaced by a hydroxyl group, such as 2-naphthalenesulfonyl chloride; aromatic sulfonyl chlorides, such as 2-naphthalenesulfonyl chloride; photoactive oximes, such as 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime; benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(t-butoxy)-2-phenylbenzoylsulfide, 4-benzoyl-4'-methyldiphenyl ... benzophenone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and 2,4-diethylthioxanthone; 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis( triazine-based compounds such as 2-(naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-piperonyl-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxy-naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, and 2,4-trichloromethyl-(4'-methoxystyryl)-6-triazine;Oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyloxime)], O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxy-naphthyl)ethylidene)hydroxylamine; phosphine compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; quinone compounds such as 9,10-phenanthrenequinone, camphorquinone, and ethylanthraquinone; borate compounds; carbazole compounds; imidazole compounds; and titanocene compounds. The adhesive composition may contain only one type of photopolymerization initiator, or may contain two or more types.

[0068] The amount of the photopolymerization initiator in the adhesive composition is, for example, 0.02 to 10 parts by mass, and may be 0.05 to 5 parts by mass, relative to 100 parts by mass in total of the monomer group and the partial polymer thereof.

[0069] The adhesive composition may contain a crosslinking agent. The crosslinking agent is, for example, a polyfunctional monomer having two or more polymerizable functional groups in one molecule. The polyfunctional monomer may be the (meth)acrylic monomer. The polyfunctional monomer may be, for example, a monomer having two or more C=C bonds in one molecule, or a monomer having one or more C=C bonds and one or more polymerizable functional groups such as epoxy groups, aziridine groups, oxazoline groups, hydrazine groups, or methylol groups in one molecule. The polyfunctional monomer is preferably a monomer having two or more C=C bonds in one molecule.

[0070] Examples of the polyfunctional monomer include (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol diacrylate. Examples of the polyfunctional monomer include polyfunctional acrylates (such as ester compounds of polyhydric alcohols and (meth)acrylic acid) such as 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate; allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate. The polyfunctional monomer is preferably a polyfunctional acrylate, and more preferably trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0071] The adhesive composition may contain a crosslinking agent other than the polyfunctional monomer, such as an isocyanate crosslinking agent.

[0072] The amount of the crosslinking agent in the adhesive composition varies depending on the molecular weight, the number of functional groups, etc., but may be, for example, 5 parts by mass or less, 3 parts by mass or less, 2 parts by mass or less, 1 part by mass or less, or 0.5 parts by mass or less, relative to 100 parts by mass of the total of the monomer group and its partial polymer. The lower limit of the amount may be, for example, 0.01 parts by mass or more, or 0.05 parts by mass or more.

[0073] The adhesive composition of this embodiment is a solvent-free coating liquid that does not substantially contain a solvent. In order to deform the outer peripheral surface of the rubber roller 22 as described above, it is preferable to form a coating film C with a small solvent content on the first film F1. From this viewpoint, the mass ratio of the solvent to the total mass of the adhesive composition is preferably 10 mass % or less, more preferably 5 mass % or less. In addition, the adhesive composition may be a solvent-free system that does not substantially contain a solvent.

[0074] The adhesive composition may contain any additive other than those described above, such as a chain transfer agent, a silane coupling agent, a viscosity modifier, a tackifier, a plasticizer, a softener, an antiaging agent, a filler, a colorant, an antioxidant, a surfactant, an antistatic agent, and an ultraviolet absorbing agent.

[0075] The coating device and coating method according to the present invention are not limited to the above-mentioned embodiment. The coating device and coating method according to the present invention are not limited to the above-mentioned action and effect. The coating device and coating method according to the present invention can be modified in various ways without departing from the gist of the present invention.

[0076] For example, the coating unit 10 is not limited to a die coater, and may be a gravure coater, tension web coater, roll coater, comma coater, bar coater, or the like, as long as it is capable of forming a coating film C of a predetermined thickness.

[0077] In the above embodiment, an adhesive composition containing a photocurable polymer is exemplified, but it is considered that an adhesive composition containing a thermosetting polymer can also achieve the desired effect. When using an adhesive composition containing a thermosetting polymer, it is preferable to use a second film F2 having air permeability that allows the solvent of the adhesive composition to pass through, and further to use a curing unit 30 having a heating unit that can volatilize the solvent while crosslinking the polymer.

[0078] The matters disclosed in this specification include the following. (1) a coating unit that forms a coating film of a liquid resin on a first film, and a laminating unit that bonds a second film to the first film via the coating film; the laminating unit has a pair of rollers consisting of a first roller having an outer periphery made of metal and a second roller having an outer periphery made of an elastic member, and a fixing mechanism that fixes each roller so as to maintain a distance between the pair of rollers; The laminating unit is a coating device that bonds the first film, on which the coating film has been formed, to the second film by the pair of rollers while the distance is maintained by the fixing mechanism. (2) The coating device described in (1) above, wherein the fixing mechanism is configured to fix each roller in a state in which the outer circumferential surface of the second roller is pressed against the outer circumferential surface of the first roller via the first film and the second film on which the coating film is formed. (3) The radii of the first roller and the second roller when not in contact with each other are r1 and r2, respectively; The total thickness of the first film, the second film, and the coating film is defined as t; When the distance from the central axis of the first roller to the central axis of the second roller is d, The coating device according to (1) or (2) above, wherein the first roller and the second roller are fixed by the fixing mechanism at positions that satisfy d≦r1+r2+t. (4) The coating device according to any one of (1) to (3) above, wherein the second roller is a rubber roller having an outer periphery made of rubber. (5) The method includes a coating step of forming a coating film of a liquid resin on a first film, and a lamination step of bonding a second film to the first film via the coating film, The lamination process uses a pair of rollers for bonding the second film to the first film, one of which is a first roller having an outer periphery made of metal and the other of which is a second roller having an outer periphery made of an elastic material, and each roller is fixed so as to maintain a distance between the pair of rollers.The first film on which the coating film has been formed and the second film are passed between the first roller and the second roller while maintaining the distance.This is a coating method. (6) The coating method according to (5) above, wherein in the laminating step, the rollers are fixed in a state in which the outer peripheral surface of the second roller is pressed against the outer peripheral surface of the first roller via the first film and the second film on which the coating film is formed. (7) The radii of the first roller and the second roller when not in contact with each other are r1 and r2, respectively; The total thickness of the first film, the second film, and the coating film is defined as t; When the distance from the central axis of the first roller to the central axis of the second roller is d, The coating method according to (6) or (7) above, wherein the first roller and the second roller are fixed at positions satisfying d≦r1+r2+t. (8) A coating method according to any one of (5) to (7) above, a curing step of curing the coating film to form an adhesive layer, and obtaining a laminate in which the second film is laminated to the first film via the adhesive layer. (9) the liquid resin is a photocurable resin, The method for producing a laminate according to (8) above, wherein in the curing step, the coating film is converted into the adhesive layer by light irradiation. (10) The method for producing a laminate according to (8) or (9) above, wherein the first film and the second film are in a continuous shape or in a sheet shape. EXAMPLES

[0079] The present invention will now be further described with reference to examples.

[0080] [Preparation of adhesive composition] As monomer components, 61 parts by mass of 2-ethylhexyl acrylate (2EHA), 14 parts by mass of N-vinylpyrrolidone (NVP), 22 parts by mass of 4-hydroxybutyl acrylate (4HBA), 3 parts by mass of hydroxyethyl acrylate (HEA), and 0.05 parts by mass of two kinds of photopolymerization initiators (trade name: Irgacure 184, manufactured by BASF) and 0.05 parts by mass of a photopolymerization initiator (trade name: Irgacure 651, manufactured by BASF) were charged into a four-neck flask to prepare a monomer mixture. Next, the monomer mixture was exposed to ultraviolet light under a nitrogen atmosphere to be partially photopolymerized, thereby obtaining a partially polymerized product (acrylic polymer syrup) with a polymerization rate of about 10% by mass.

[0081] To 100 parts by mass of the acrylic polymer syrup, 0.035 parts by mass of trimethylolpropane triacrylate (TMPTA) and 0.3 parts by mass of a silane coupling agent (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added, and then these were mixed uniformly to prepare an adhesive composition. The viscosity of this adhesive composition was 9 Pa s.

[0082] [Evaluation of film thickness accuracy and process window] A PET film having a thickness of 38 μm was used as the first film, and a PET film having a thickness of 38 μm was used as the second film. The type of roller and the positional relationship of the central axis of each roller were changed in various ways. A coating film having a thickness of 20 μm (t=96 μm) was formed on the first film using a die coater, and then the second film was laminated under the wet lamination conditions in Table 1 below using a coating device as shown in FIG. 1. The evaluation results of the film thickness accuracy and process window under each condition are as shown in FIG. 5 to FIG. 7. In Example 1, when the gap is narrowed (in the + direction of the vertical axis of the graph), the outer periphery of the rubber roller is deformed according to the pressing force from the film, so that the process window can be widened. On the other hand, in Comparative Example 1, since the roller does not deform, liquid puddles are easily generated, and the process window is narrower than that of Example 1. Also, in Comparative Example 2, although the rubber roller is deformed, the gap changes as the situation progresses, so that the gap narrows beyond the deformation limit of the roller, and liquid puddles are generated.

[0083] [Table 1] [Explanation of symbols]

[0084] 1: coating device, 10: coating section, 11: die, 12: slot, 20: wet lamination section, 21: first roller (metal roller), P1: central axis, 211: shaft section, 212: outer periphery, r1: radius, 22: second roller (rubber roller), P2: central axis, 221: shaft section, 222: outer periphery, r2: radius, 23: adjustment section, 23a: first unit, 23b: second unit, 231: inclined section, 232: contact section, 30: hardening section, 40: guide roller, D1: up-down direction (first direction), D2: front-back direction (second direction), d: distance, F1: first film, F2: second film, C: coating film, t: total thickness, A: adhesive layer,

Claims

1. a coating unit that forms a coating film of a liquid resin on a first film, and a laminating unit that bonds a second film to the first film via the coating film; The coating unit is configured to discharge the liquid resin at a constant flow rate, the laminating unit has a pair of rollers including a first roller having an outer periphery made of metal and a second roller having an outer periphery made of an elastic member, and a fixing mechanism that fixes each roller so as to maintain a distance between the pair of rollers; The laminating unit is a coating device that bonds the first film, on which the coating film has been formed, and the second film by the pair of rollers while the distance is maintained by the fixing mechanism.

2. 2. The coating device according to claim 1, wherein the fixing mechanism is configured to fix each roller in a state in which the outer circumferential surface of the second roller is pressed against the outer circumferential surface of the first roller via the first film and the second film on which the coating film is formed.

3. The radii of the first roller and the second roller when not in contact with each other are r1 and r2, respectively; The total thickness of the first film, the second film, and the coating film is defined as t; When the distance from the central axis of the first roller to the central axis of the second roller is d, The coating device according to claim 2 , wherein the first roller and the second roller are fixed at positions satisfying d≦r1+r2+t by the fixing mechanism.

4. The coating device according to claim 1 , wherein the second roller is a rubber roller having an outer periphery made of rubber.

5. The method includes a coating step of forming a coating film of a liquid resin on a first film, and a lamination step of bonding a second film to the first film via the coating film, In the coating step, the liquid resin is discharged at a constant flow rate, In the lamination process, a pair of rollers is used for bonding the second film to the first film, one of which is a first roller having an outer periphery made of metal and the other is a second roller having an outer periphery made of an elastic material, and each roller is fixed so as to maintain a distance between the pair of rollers, and the first film on which the coating film has been formed and the second film are passed between the first roller and the second roller with the distance maintained.

6. The coating method according to claim 5 ; a curing step of curing the coating film to form an adhesive layer, and obtaining a laminate in which the second film is laminated to the first film via the adhesive layer.

7. the liquid resin is a photocurable resin, The method for producing a laminate according to claim 6 , wherein in the curing step, the coating film is converted into the adhesive layer by light irradiation.

8. The method for producing a laminate according to claim 6 or 7, wherein the first film and the second film are in the form of a long film or a sheet.

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