Coating device, coating method and laminate manufacturing method

Abstract

To provide a coating device which can suppress lowering of film thickness accuracy in laminate, and has such a wide process window as to suppress lowering of film thickness accuracy.SOLUTION: A coating device includes a coat part for forming a coated film of a liquid resin on a first film, and a laminate part for bonding a second film to the first film through the coated film, wherein the laminate part has a pair of rollers composed of a first roller having a metal outer peripheral part and a second roller having an outer peripheral part composed of an elastic member, and a fixing mechanism for fixing each of the rollers so as to keep a distance between the pair of rollers, and the laminate part bonds the first film and the second film where the coated film is formed by the pair of rollers, in a state in which the distance is held by the fixing mechanism.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] BACKGROUND ART 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-reflecting 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 wet coating film. In conventional wet lamination processes using rubber rollers known as nip rollers, not limited to the manufacturing method of Patent Document 1, the distance between the rubber roller and the metal roller is changed during coating in accordance with changes in the contact area between the rollers in order to maintain a constant pressure of the rubber roller against one roller (a metal roller in Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-115157 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, various film products having multiple functional layers, such as optical films, require high uniformity in the thickness of the adhesive layers that bond 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 film thickness accuracy, in the coating process for forming the coating film.

[0007] However, according to the inventors' investigations, the wet lamination process using a rubber roller that changes its 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 Figure 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 have outer peripheral surfaces that are less likely to deform than rubber rollers. Therefore, a pair of rollers made of metal rollers is thought to be easier to maintain a constant gap between the outer peripheral surfaces of the metal rollers and to maintain film thickness accuracy. However, according to the inventors' investigations, a wet lamination process using a pair of metal rollers has the problem that the gap range over which film thickness accuracy can be maintained is narrow, i.e., 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 that has 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 a metal outer periphery 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 and the second film together using 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 and second films (passing objects) on which coating films have been formed pass between the first and second rollers, a pressing force from the film corresponding to the thickness of each film and the thickness of the coating is applied to the outer periphery of each roller. Because the rollers are fixed as described above, the outer periphery of the second roller is easily deformed in response to the pressing force. That is, the outer periphery of the second roller deforms in the radial direction of the roller according to the thickness of the passing object. This prevents liquid from puddling immediately before the rollers and reduces the deterioration of film thickness accuracy during lamination. Furthermore, 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 between the pair of rollers over which the deterioration of film thickness accuracy can be reduced, i.e., 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 surface of the second roller is pressed against the outer surface of the first roller via the first film and the second film on which the coating film is formed.

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

[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, the state in which the outer peripheral surface of the second roller is in contact with the outer peripheral surface of the first roller, that is, the state defined by d = r1 + r2 + t, or even in a state in which the central axes of the rollers are closer to each other than this state, that is, the 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 action 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, the rollers are 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 coating methods described above; 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 on the first film via the adhesive layer.

[0021] According to this configuration, a laminate having an adhesive layer with high film thickness accuracy can be obtained. [Effects 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 using a liquid resin, and it is possible to provide a coating device and a coating method with a wide process window that can suppress a decrease in film thickness accuracy. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram of a coating device according to an embodiment. [Figure 2] 2 is a schematic enlarged view of a pair of rollers in a wet laminating unit of the coating device of FIG. 1. FIG. [Figure 3] 3 is a schematic view of a fixing mechanism for fixing the pair of rollers in FIG. 2. FIG. [Figure 4] FIG. 10 is a diagram showing a state in which a liquid pool occurs immediately before the roller. [Figure 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] 10 is a graph showing the evaluation results of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[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 device 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 a first film F1 to form a coating film C of a predetermined thickness, and a wet laminating 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 and 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 a photocurable liquid resin.

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

[0028] The coating unit 10 of this embodiment is located upstream of the wet laminating unit 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 unit 10 is equipped with a die 11 for coating the adhesive composition. The die 11 has a slot 12 that serves as a discharge port for discharging the adhesive composition. In other words, the coating unit 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. Furthermore, the die 11 is 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 the slot 12 (the opening distance in the direction perpendicular to the width direction of the slot 12) is preferably adjustable within a range of at least 0.1 μm to 1000 μm. The width of the slot 12 is preferably adjustable within a range of 200 mm to 5000 mm. The height of the slot 12 refers to the average height of the heights of nine points that divide the slot 12 into ten 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 is equipped with rollers (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 peripheral 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 circumferential portion 212 formed from the shaft portion 211 to the outer circumferential surface. In this embodiment, both the shaft portion 211 and the outer circumferential portion 212 of the metal roller 21 are made of metal. The rubber roller 22 has a shaft portion 221 including a central axis P2 and an outer circumferential portion 222 formed from the shaft portion 221 to the outer circumferential surface. In this embodiment, at least the outer circumferential portion 222 of the rubber roller 22 is made of rubber. The metal roller 21 and the rubber roller 22 are arranged so that their respective central axes (central axes P1 and P2) are parallel to each other. In the following, a first direction that is perpendicular to the direction in which the central axes of the rollers extend and is the direction in which a line segment connecting the central axes of the rollers extends will be referred to as the up-down direction D1, and a second direction that is perpendicular to both the direction in which the central axes of the rollers extend and the up-down direction D1 will be referred to as the front-rear direction D2.

[0034] The pair of rollers are configured so that the outer surface of the first film F1 abuts against the outer peripheral surface of one roller, and the outer surface of the second film F2 abuts against the outer peripheral surface of the other roller, while rotating in a direction that pulls the first film F1 and the second film F2 (the passing object) on which the coating film C has been formed between the rollers. In this embodiment, the metal roller 21 and the rubber roller 22 are aligned in the vertical 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. Alternatively, 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 peripheral surface of the rubber roller 22 so that it is partially wrapped around the outer peripheral surface. The coating device 1 may also include a means (e.g., a roller) for applying tension to the second film F2 in the direction opposite to the traveling direction as it comes into contact with the rubber roller 22. This allows the second film F2 to be sufficiently pressed against the outer peripheral 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) as a propulsion unit that applies a propulsive force to one roller to move the other roller toward the other roller, and an adjustment unit 23 that adjusts the distance of the other roller relative to the one roller.

[0038] The cylinder may be connected to the metal roller 21 or the rubber roller 22. The cylinder in this embodiment is connected to the shaft 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 unit 23 of this embodiment includes a first unit 23a having an inclined portion 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 portion 232 connected to one of the rollers and contacting the inclined portion 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, which is in contact with the inclined portion 231 at the contact portion 232, can move in both directions in the up-down direction D1 while being guided by the inclined portion 231.

[0040] The inclined portion 231 has an inclined surface that is inclined from one side to the other in the front-rear direction D2 and faces upward. In this embodiment, the inclined surface 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 in the front-rear direction D2 and faces downward so as to abut against the inclined surface. In this embodiment, the abutting surface is inclined upward from the upstream side to the downstream side in the front-rear direction D2 to correspond to the inclination of the inclined surface. 3(a) and 3(b), the fixing mechanism of this embodiment slides the second unit 23b, which presses the inclined surface with the contact surface, in one direction in the front-to-rear direction D2 (forward in FIG. 3(b)), accompanied by the propulsive force. This causes the inclined surface to be displaced in one direction in the front-to-rear direction D2 relative to the contact surface, and moves the rubber roller 22 in a direction that brings 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(b)). Meanwhile, as shown in FIGS. 3(a) and 3(c), the fixing mechanism of this embodiment slides the second unit 23b in the other direction in the front-to-rear direction D2 (rear in FIG. 3(c)), causing the inclined surface to be displaced in the other direction in the second direction D2 relative to the contact surface, and moves the rubber roller 22 in a direction that moves the central axis P2 of the rubber roller 22 away from the central axis P1 of the metal roller 21 (a direction that increases the distance d, upward in FIG. 3(c)). The first unit 23a is configured to be fixed from the time the distance d is adjusted until the lamination is completed.

[0041] 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 C is t, the fixing mechanism of this embodiment is configured to fix the rubber roller 22 at a position such that d≦r1+r2+t. In this case, the fixing mechanism can fix each roller in a state where the outer surface of the rubber roller 22 is pressed against the outer surface of the metal roller 21 via the first film F1 and the second film F2 on which the coating C is formed. Furthermore, since d≦r1+r2+t, there is essentially no gap between the coating C and the second film F2, and the films can be bonded together without causing the second film F2 to lift up relative to the coating C (a factor that causes unevenness on the surface of the second film F2).

[0042] Furthermore, when the radius when the rubber roller 22 is 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 an embodiment that satisfies the above inequality.

[0043] Here, the state in which each roller is fixed so that d = r1 + r2 + t is defined as the reference position of the central axes P1 and P2 (the positional relationship of the central axes in FIG. 3(a)), and 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 (the 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 (the 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 axes P1 and P2 are positioned at a positive side of +2000 μm from the reference position, with +1000 μm being preferred, and +500 μm being more preferred. 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 positioned on the negative side of -2000 μm from the reference position, with the value being preferably -1000 μm, and more preferably -500 μm.

[0044] The wet lamination section 20 of this embodiment is particularly excellent at suppressing a decrease in film thickness accuracy when the distance d is adjusted to achieve the positive side positional relationship so that the outer surface of the rubber roller 22 is pressed against the outer 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, i.e., the thickness of the rubber portion 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, it 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 the compression test (method D) specified in JIS K 6254. The density of the rubber can be measured by the underwater displacement method.

[0047] The rubber composition for forming the outer circumferential portion 222 of the rubber roller 22 may contain a thermosetting elastomer, which is rubber, or a thermoplastic elastomer. Examples include 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. Examples of the rubber composition include styrene-based thermoplastic elastomers, acrylic-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyvinyl chloride-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers. That is, the elastic member for forming the outer circumferential portion of the first roller may be a thermosetting elastomer, which is rubber, or a thermoplastic elastomer, 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 or a laminate manufacturing method according to one embodiment of the present invention will be described by taking as an example a method using the coating apparatus 1 or laminate manufacturing apparatus 100 described above.

[0050] The method for manufacturing the laminate of this embodiment includes a coating process that includes a coating step in which a photocurable adhesive composition is applied to a first film F1 to form a coating film C of a predetermined thickness on the first film F1, and a wet lamination step in which a second film F2 is bonded to the first film F1 via the coating film C, and further includes a curing step in which the coating film C is cured 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 form that can be formed into a roll. Alternatively, 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 by measuring the thickness at the center and both ends in the width direction at 10 arbitrary points in the conveyance direction, and averaging these 30 thicknesses to determine the average thickness.

[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 separates from the outer peripheral surface of the guide roller 40 until the coating film C becomes the 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 abutted against the outer surface of one roller, and the outer surface of the second film F2 is abutted against the outer surface of the other roller, and the passing object is pulled between the rollers, and the second film F2 is bonded to the first film F1 via the coating film C. At this time, each roller is fixed so as to maintain a distance d between the pair of rollers, and the first film F1 and the second film F2, each having the coating film C formed thereon, 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 presses the outer surface of the rubber roller 22, thereby radially deforming the outer surface of the rubber roller 22 and bonding the second film F2 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 wrapped around the outer surface.

[0057] In the wet lamination step, 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 via the first film F1 and the second film F2 on which the coating film C is formed.

[0058] In the wet lamination process, it is preferable that the object is passed between the rollers with the central axes P1 and P2 positioned at a positive position of +2000 μm from the reference position. Alternatively, in the wet lamination process, the object may be passed between the rollers with the central axes P1 and P2 positioned at a negative position of -2000 μm from the reference position.

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

[0060] The adhesive composition of this embodiment forms a pressure-sensitive adhesive sheet when 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 2-ethylhexyl (meth)acrylate. (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 (meth)acrylic monomer, or two or more types.

[0062] The amount of the (meth)acrylic acid alkyl ester blended per 100 parts by mass of the monomer group 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 blending 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 (or 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 (or 5 or less), such as itaconic acid, maleic acid, and fumaric acid. The amount of the carboxyl group-containing monomer in 100 parts by mass of the monomer group is, for example, 10 parts by mass or less, and may be 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 does not necessarily need to contain a carboxyl group-containing monomer.

[0064] The monomer group may include a hydroxy group-containing monomer. The hydroxy group-containing monomer may be the (meth)acrylic monomer, in other words, the (meth)acrylic monomer may contain a hydroxy group. The hydroxy group-containing monomer may contribute to improving the cohesive strength of the PSA sheet. Examples of the hydroxy 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 (4-hydroxymethylcyclohexyl)-methyl acrylate. The hydroxy group-containing monomer is preferably 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate. The amount of the hydroxy group-containing monomer blended per 100 parts by mass of the monomer group is, for example, 20 parts by mass or less, and may be 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 blended 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 necessarily contain a hydroxy group-containing monomer.

[0065] The adhesive composition may contain the above-described monomers as partial polymers. The partial polymers may be either homopolymers or copolymers. The partial polymers may appropriately increase the viscosity of the adhesive composition, thereby contributing to the stable formation of the coating film C.

[0066] The adhesive composition typically contains a photopolymerization initiator, such as a photoradical generator that generates radicals when exposed to visible light and / or ultraviolet light with 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; and 2-methyl-2-hydroxypropionyl ether. Substituted alpha-ketols in which the α-hydrogen of acetophenone, such as phenone, is replaced with a hydroxyl group; 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) benzophenone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and 2,4-diethylthioxanthone; thioxanthone compounds such as 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, and 2-(p-tolyl)-4,6-bis( triazine compounds such as 2-(4-methoxy-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)], and 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 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 of the total of the monomer group and its partial polymer.

[0069] The adhesive composition may contain a crosslinking agent. An example of the crosslinking agent is a polyfunctional monomer having two or more polymerizable functional groups in one molecule. The polyfunctional monomer may be the (meth)acrylic monomer. Examples of the polyfunctional monomer include a monomer having two or more C=C bonds in one molecule, and 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 (e.g., 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, or dipentaerythritol hexa(meth)acrylate.

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

[0072] The amount of 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 polymers. 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 low solvent content on the first film F1. From this perspective, 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. Furthermore, 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 mentioned above, such as a chain transfer agent, a silane coupling agent, a viscosity modifier, a tackifier, a plasticizer, a softener, an antioxidant, a filler, a colorant, an antioxidant, a surfactant, an antistatic agent, and an ultraviolet absorber.

[0075] The coating device and coating method according to the present invention are not limited to the above-described embodiments. Furthermore, the coating device and coating method according to the present invention are not limited to the above-described effects. The coating device and coating method according to the present invention can be modified in various ways without departing from the spirit and scope 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 believed that the desired effects can also be achieved with an adhesive composition containing a thermosetting polymer. When using an adhesive composition containing a thermosetting polymer, it is preferable to use a second film F2 that is breathable and allows the solvent of the adhesive composition to pass through, and further to use a curing unit 30 that has a heating unit that can volatilize the solvent while crosslinking the polymer.

[0078] The matters disclosed by 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 a metal outer periphery 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 uses the pair of rollers to bond the first film, on which the coating film has been formed, to the second film 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 surface of the second roller is pressed against the outer 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 thickness of the first film, the thickness of the second film, and the thickness of the coating film is t, When the distance from the center axis of the first roller to the center 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 laminating step of bonding a second film to the first film via the coating film, In the laminating step, a pair of rollers is used to bond 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 while the distance is maintained. (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 thickness of the first film, the thickness of the second film, and the thickness of the coating film is t, When the distance from the center axis of the first roller to the center 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 where d≦r1+r2+t is satisfied. (8) The 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 on 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 the form of a continuous sheet or sheets. [Example]

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

[0080] [Preparation of adhesive composition] A monomer mixture was prepared by adding 61 parts by weight of 2-ethylhexyl acrylate (2EHA), 14 parts by weight of N-vinylpyrrolidone (NVP), 22 parts by weight of 4-hydroxybutyl acrylate (4HBA), 3 parts by weight of hydroxyethyl acrylate (HEA), and 0.05 parts by weight of two photopolymerization initiators (trade name: Irgacure 184, manufactured by BASF) and 0.05 parts by weight of a photopolymerization initiator (trade name: Irgacure 651, manufactured by BASF) to a four-neck flask. The monomer mixture was then partially photopolymerized by exposure to ultraviolet light under a nitrogen atmosphere to obtain a partially polymerized product (acrylic polymer syrup) with a polymerization rate of approximately 10% by weight.

[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 (trade 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 38 μm-thick PET film was used as the first film, and a 38 μm-thick PET film was used as the second film. The roller type and the positional relationship of the central axes of the rollers were varied. A 20 μm-thick coating (t=96 μm) was formed on the first film using a die coater, and then the second film was laminated using the coating device shown in FIG. 1 under the wet lamination conditions listed in Table 1 below. The evaluation results for film thickness accuracy and process window under each condition are shown in FIGS. 5 to 7. In Example 1, narrowing the gap (in the + direction on the vertical axis of the graph) caused the outer periphery of the rubber roller to deform in response to the pressure from the film, thereby widening the process window. In Comparative Example 1, on the other hand, the roller did not deform, so puddling was likely to occur, resulting in a narrower process window than in Example 1. In Comparative Example 2, although the rubber roller deformed, the gap changed spontaneously, narrowing the gap beyond the roller's deformation limit and causing puddling.

[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 laminating unit has a pair of rollers consisting of a first roller having a metal outer periphery 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 uses the pair of rollers to bond the first film, on which the coating film has been formed, to the second film 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 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.

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 thickness of the first film, the thickness of the second film, and the thickness of the coating film is defined as t, When the distance from the center axis of the first roller to the center axis of the second roller is d, The coating device according to claim 2 , wherein the first roller and the second roller are fixed by the fixing mechanism at positions where d≦r1+r2+t is satisfied.

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 laminating step of bonding a second film to the first film via the coating film, In the laminating step, a pair of rollers is used to bond 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 the curing step converts the coating film 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 continuous sheet or a sheet.

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