Laminated film and method for manufacturing laminated film

Abstract

[Problem] To provide a laminated film capable of suppressing adhesive deficiency and separation of the first adhesive layer, and a method for manufacturing the laminated film. [Solution] A laminated film according to an embodiment of the present invention comprises a first release liner, a first adhesive layer, a functional film, a second adhesive layer, and a second release liner in this order. The end surface of the first adhesive layer includes a planar portion that extends in a substantially straight shape in a cross-section obtained by cutting the first adhesive layer in the thickness direction. The end surface of the first adhesive layer is located inward from the end surface of the functional film in a plane direction perpendicular to the thickness direction of the first adhesive layer. The functional film includes an adhesive region that overlaps with the first adhesive layer when the first adhesive layer is projected onto the functional film, and a margin region located outside the adhesive region in the plane direction. The thickness of the first adhesive layer relative to the width of the margin region is 0.5 or more and 4.5 or less.

Description

Technology Field

[0001] The present invention relates to a laminated film and a method for manufacturing a laminated film. Background Technology

[0002] It is known that functional films are applied to various industrial products to provide the products with any appropriate optical compensation function. In various industrial products, such functional films are sometimes inserted between two adjacent components. In this case, the functional film is typically attached to each component via an adhesive layer.

[0003] For this reason, it is desired to manufacture a laminated film having a first adhesive layer, a functional film, and a second adhesive layer in this order.

[0004] A double-sided adhesive-attached optical film is proposed, which is used as a laminated film, for example, between a front transparent plate or a touch panel and an image display cell, and comprises an optical film including a polarizing plate, a first adhesive layer formed on the side of the optical film that is bonded to the image display cell, and a second adhesive layer formed on the side of the optical film that is bonded to the transparent plate or touch panel, wherein a protective sheet is peelably bonded to each of the first adhesive layer and the second adhesive layer, and the thickness of the second adhesive layer is 30 μm or more (for example, see Patent Document 1). Prior art literature

[0005] Japanese Patent Publication No. 2014-115468 The problem to be solved

[0006] These laminated films are generally cut into shapes according to their intended use, and then the cut surface is finished using an arbitrary and suitable cutting tool. When finishing the laminated film, the end surface (side) of the adhesive layer comes into contact with the cutting tool, and there is a risk that the end portion of the adhesive layer may be missing (hereinafter referred to as adhesive deficiency).

[0007] Therefore, in the adhesive-attached optical film described in Patent Document 1, the end surface of the adhesive layer is positioned inwardly relative to the end surface of the optical film to suppress the lack of adhesive in the adhesive layer. In Patent Document 1, the double-sided adhesive-attached optical film is pressed in the thickness direction to protrude the end of the adhesive layer from the end of the optical film, and then the double-sided adhesive-attached optical film is cut. When the pressure is released, the end surface of the adhesive layer is retracted inwardly relative to the end surface of the optical film.

[0008] However, if the end surface of the adhesive layer is recessed inward relative to the end surface of the optical film by the method described in Patent Document 1, the end surface of the adhesive layer becomes a curved shape that is concave toward the inside. If the end surface of the adhesive layer has such a curved shape, depending on the amount of cutting during the finishing process of the adhesive-attached optical film, contact between the cutting tool and the adhesive layer cannot be sufficiently suppressed, and there may be a shortage of adhesive in the adhesive layer. In addition, when peeling the protective sheet from the adhesive layer, there is a risk that a phenomenon may occur in which a part of the adhesive layer peels off together with the protective sheet (hereinafter referred to as separation).

[0009] The present invention is made to solve the above-mentioned conventional problems, and its main objective is to provide a laminated film and a method for manufacturing a laminated film that can suppress the defect of the end portion of the first adhesive layer and also suppress the peeling of a part of the first adhesive layer together with the first peel liner when the first peel liner is peeled from the first adhesive layer. means of solving the problem

[0010] [1] A laminated film according to an embodiment of the present invention comprises a first release liner, a first adhesive layer, a functional film, a second adhesive layer, and a second release liner in this order. The thickness of the first adhesive layer is greater than the thickness of the second adhesive layer. The first adhesive layer has a first surface, a second surface, and an end surface. The first surface is in contact with the first release liner. The second surface is in contact with the functional film. The end surface connects the periphery edge portion of the first surface with the periphery edge portion of the second surface. The end surface of the first adhesive layer includes a planar portion that extends in a substantially straight shape in a cross-section obtained by cutting the first adhesive layer in the thickness direction. The end surface of the first adhesive layer is located inward from the end surface of the functional film in a plane direction orthogonal to the thickness direction of the first adhesive layer. The functional film includes an adhesive region and a margin region. The adhesive region overlaps with the first adhesive layer when the first adhesive layer is projected onto the functional film in the thickness direction. The margin region is located outward from the adhesive region in the plane direction. The thickness of the first adhesive layer relative to the width of the margin region is 0.5 or more and 4.5 or less.

[0011] [2] In the laminated film described in [1] above, the thickness of the first adhesive layer relative to the width of the margin area may be 3.0 or less.

[0012] [3] In the laminated film described in [1] or [2] above, the width of the margin area may be 60 μm or more and 350 μm or less. The thickness of the first adhesive layer may be 25 μm or more and 550 μm or less.

[0013] [4] In the laminated film described in any one of [1] to [3] above, the end surface of the first adhesive layer may have a first stage and a second stage. The first stage is connected to the periphery edge of the first surface. The second stage is connected to the periphery edge of the second surface. The first stage and the second stage may be positioned offset from each other in the direction of the surface.

[0014] [5] In the laminated film described in [4] above, the planar portion may extend over the entire area between the first stage and the second stage. The angle formed by the planar portion and the second surface may be 70° or more and less than 90°, or greater than 90° and less than 110°.

[0015] [6] In the laminated film described in any one of [1] to [5] above, in the plane direction, the end surface of the first adhesive layer may be located inwardly compared to the end surface of the second adhesive layer.

[0016] [7] In any one of [1] to [6] above, the functional film may be a polarizing plate including a polarizer.

[0017] [8] A method for manufacturing a laminated film according to another aspect of the present invention comprises: a process of preparing a first disc film having a first release liner and a first adhesive layer; a process of preparing a second disc film having a second release liner, a second adhesive layer and a functional film in this order; a process of cutting the first adhesive layer having the first disc film into a product portion having a desired shape and a non-product portion; a process of peeling off and removing the non-product portion from the first release liner; a process of contacting the functional film with the product portion to bond the first disc film and the second disc film to obtain an intermediate film; and a process of cutting the intermediate film to obtain a laminated film including the product portion. The thickness of the first adhesive layer is greater than the thickness of the second adhesive layer. The functional film provided by the laminated film includes an adhesive region that overlaps with the product portion when the product portion is projected onto the functional film in the thickness direction of the first adhesive layer. The adhesive region is located inward from the end surface of the functional film in a plane direction orthogonal to the thickness direction. Effects of the invention

[0018] According to an embodiment of the present invention, the invention provides a laminated film and a method for manufacturing the laminated film, which can suppress the failure of the end portion in the first adhesive layer and also suppress the peeling of a part of the first adhesive layer together with the first peel liner when the first peel liner is peeled from the first adhesive layer. Brief explanation of the drawing

[0019] FIG. 1 is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a laminated film according to another embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a laminated film according to another embodiment of the present invention. FIG. 4 is an explanatory diagram for describing the preparation process of a first disc film included in the method for manufacturing a laminated film according to another aspect of the present invention. FIG. 5 is an explanatory diagram for explaining the process of cutting the first adhesive layer provided by the first disc film of FIG. 4. FIG. 6 is an explanatory diagram for explaining a process of obtaining an intermediate film by bonding a second disc film to the first disc film of FIG. 5. Figure 7 is an explanatory diagram for explaining the process of obtaining a laminated film by cutting the intermediate film of Figure 6. Figure 8 is an explanatory diagram for explaining the finishing process of the laminated film of Figure 7. Specific details for implementing the invention

[0020] Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. Furthermore, in order to make the explanation clearer, the drawings may schematically depict the width, thickness, shape, etc. of each part compared to the embodiments; however, this is merely an example and does not limit the interpretation of the present invention.

[0021] A. Overview of the laminated film

[0022] FIG. 1 is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention; FIG. 2 is a schematic cross-sectional view of a laminated film according to another embodiment of the present invention; and FIG. 3 is a schematic cross-sectional view of a laminated film according to yet another embodiment of the present invention.

[0023] In one embodiment, the laminated film (100) comprises a first release liner (1), a first adhesive layer (2), a functional film (3), a second adhesive layer (4), and a second release liner (5) in this order.

[0024] The thickness of the first adhesive layer (2) is greater than the thickness of the second adhesive layer (4). The first adhesive layer (2) has a first surface (21), a second surface (22), and an end surface (23). The first surface (21) of the first adhesive layer (2) is one side in the thickness direction (hereinafter simply referred to as the thickness direction) of the first adhesive layer (2) and is in contact with the first release liner (1). The second surface (22) of the first adhesive layer (2) is the other side in the thickness direction and is in contact with the functional film (3). The end surface (23) of the first adhesive layer (2) is an end surface in a plane direction (hereinafter simply referred to as the plane direction) that is orthogonal to the thickness direction in the first adhesive layer (2), and connects the periphery edge portion of the first surface (21) and the periphery edge portion of the second surface (22).

[0025] The end surface (23) of the first adhesive layer (2) includes a planar portion (23a) that extends substantially in a straight shape in a cross-section obtained by cutting the first adhesive layer (2) in the thickness direction. The end surface (23) of the first adhesive layer (2) is located inward from the end surface of the functional film (3) in the plane direction. The functional film (3) includes an adhesive region (31) and a margin region (32). The adhesive region (31) of the functional film (3) overlaps with the first adhesive layer (2) when the first adhesive layer (2) is projected in the thickness direction onto the functional film (3). The margin region (32) of the functional film (3) is located outward from the adhesive region (31) in the plane direction.

[0026] The thickness t of the first adhesive layer (2) for the width A of the margin area (32) is 0.5 or more and 4.5 or less.

[0027] The inventors discovered that even if the end surface of the first adhesive layer is located inward from the end surface of the functional film, there may be a lack of adhesive in the first adhesive layer depending on the amount of cutting during the finishing process of the laminated film. Therefore, the inventors carefully examined the suppression of the lack of adhesive in the first adhesive layer and found that the relationship between the end surface shape of the first adhesive layer and the thickness of the first adhesive layer relative to the width of the margin area of ​​the functional film affects the lack of adhesive in the first adhesive layer.

[0028] In one embodiment, the end surface of the first adhesive layer includes a planar portion that extends in a substantially straight shape in a cross-section in which the first adhesive layer is cut in the thickness direction, and the thickness of the first adhesive layer relative to the width of the margin region of the functional film is 0.5 or more and 4.5 or less, so that the lack of adhesive in the first adhesive layer in the laminated film can be reliably suppressed.

[0029] In addition, since the end surface of the first adhesive layer includes a flat portion, compared to the case where the end surface of the first adhesive layer has a concave curved shape facing inward in the direction of the surface, the separation of the first adhesive layer can be sufficiently suppressed when the first release liner is peeled from the first adhesive layer.

[0030] The thickness t (t / A) of the first adhesive layer (2) relative to the width A of the margin area (32) is preferably 0.8 or more, more preferably 1.0 or more, and even more preferably 1.2 or more. If t / A in the laminated film is greater than this lower limit, the lack of adhesive in the first adhesive layer can be suppressed, and the amount of cutting during the finishing process of the laminated film can be reduced.

[0031] Meanwhile, the thickness t (t / A) of the first adhesive layer (2) relative to the width A of the margin area (32) is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less. If t / A in the laminated film is below this upper limit, the lack of adhesive in the first adhesive layer can be suppressed more stably. More specifically, if t / A in the laminated film is below this upper limit (i.e., if the width of the margin area has a sufficient width relative to the thickness of the first adhesive layer), even if the first adhesive layer is deformed by the pressure of the clamp during cutting, the contact of the first adhesive layer with the cutting blade can be suppressed stably.

[0032] The width A of the margin area (32) is a dimension in the normal direction of the end surface of the functional film (3), and is the distance (offset amount) at which the end surface (23) of the first adhesive layer (2) is offset from the end surface of the functional film (3).

[0033] The width A of the margin area (32) is, for example, 50 μm or more, preferably 80 μm or more, more preferably 100 μm or more, and even more preferably 150 μm or more. If the margin area has such a width, the lack of adhesive in the first adhesive layer can be suppressed more stably.

[0034] Meanwhile, the width A of the margin region (32) is, for example, 400 μm or less, preferably 300 μm or less, more preferably 200 μm or less. If the margin region has such a width, the thickness of the first adhesive layer relative to the width of the margin region can be stably adjusted to the above range.

[0035] The thickness of the first adhesive layer (2) is arbitrarily and appropriately adjusted according to the use of the laminated film after finishing.

[0036] The thickness t of the first adhesive layer (2) is, for example, 10 μm or more, preferably 25 μm or more, more preferably 100 μm or more, and even more preferably 200 μm or more.

[0037] Meanwhile, the thickness t of the first adhesive layer (2) is, for example, 600 μm or less, preferably 550 μm or less, more preferably 500 μm or less. If the first adhesive layer has such a thickness, the thickness of the first adhesive layer relative to the width of the margin region can be adjusted more stably to the above range.

[0038] The end surface (23) of the first adhesive layer (2) typically has a first end (231) and a second end (232). The first end (231) of the end surface (23) is the end on the side of the first release liner (1) and is connected to the periphery of the first surface (21). The second end (232) of the end surface (23) is the end on the side of the functional film (3) and is connected to the periphery of the second surface (22).

[0039] The first stage (231) and the second stage (232) may coincide with each other in the plane direction as shown in FIG. 1, or may be positioned offset from each other in the plane direction as shown in FIG. 2 and FIG. 3.

[0040] A flat portion (23a) is formed between the first stage (231) and the second stage (232) on the end surface (23). The flat portion (23a) may extend over the entire area between the first stage (231) and the second stage (232), or it may be a part of the area between the first stage (231) and the second stage (232).

[0041] As shown in FIG. 2, in one embodiment, the first stage (231) is located inwardly from the second stage (232) in the plane direction. In other words, the first stage (231) is located on the opposite side of the end surface of the functional film (3) with respect to the second stage (232) in the plane direction.

[0042] According to this configuration, the area of ​​the first surface in contact with the first release liner can be made smaller than the area of ​​the second surface in contact with the functional film. Therefore, the first release liner can be smoothly peeled off from the first adhesive layer, and sufficient adhesion of the first adhesive layer to the functional film can be ensured. As a result, separation of the first adhesive layer can be reliably suppressed.

[0043] In the laminated film (100) shown in FIG. 2, the angle formed by the flat portion (23a) and the second surface (22) is, for example, 70° or more, preferably 80° or more. Meanwhile, the angle formed by the flat portion (23a) and the second surface (22) is, for example, less than 90°. If the angle formed by the flat portion and the second surface is within this range, the separation of the first adhesive layer can be suppressed more stably.

[0044] As shown in FIG. 3, the first stage (231) may be located further outward than the second stage (232) in the plane direction.

[0045] In this case, the angle formed by the planar portion (23a) and the second surface (22) is, for example, greater than 90°, and preferably greater than 100°. Meanwhile, the angle formed by the planar portion (23a) and the second surface (22) is, for example, less than 120°, and preferably less than 110°.

[0046] As shown in FIG. 1, the thickness of the second adhesive layer (4) is smaller than the thickness t of the first adhesive layer (2). Therefore, in the finishing process of the laminated film, the second adhesive layer is less likely to be adhesive than the first adhesive layer.

[0047] The thickness of the second adhesive layer (4) is, for example, 1% to 50% when the thickness t of the first adhesive layer (2) is 100%, and preferably 4% to 20%.

[0048] The thickness of the second adhesive layer (4) is, for example, 5 μm or more, preferably 10 μm or more. Meanwhile, the thickness of the second adhesive layer (4) is, for example, 30 μm or less, preferably less than 25 μm, more preferably 23 μm or less.

[0049] If the thickness of the second adhesive layer is within this range, the lack of adhesive in the second adhesive layer can be reliably suppressed.

[0050] The end surface of the second adhesive layer (4) in the plane direction may be located inward from the end surface of the functional film (3) in the plane direction, or it may be a surface substantially at the same height as the end surface of the functional film (3) in the plane direction. In the example shown in the drawing, the end surface of the second adhesive layer (4) is a surface substantially at the same height as the end surface of the functional film (3).

[0051] In addition, regarding the surface direction, the end surface of the second adhesive layer (4) may be located inwardly to the end surface (23) of the first adhesive layer (2), may be located outwardly to the end surface (23) of the first adhesive layer (2), or may be located at the same position as the end surface (23) of the first adhesive layer (2).

[0052] In one embodiment, in the plane direction, the end surface of the second adhesive layer (4) is located outward from the end surface (23) of the first adhesive layer (2). In other words, in the plane direction, the end surface (23) of the first adhesive layer (2) is located inward from the end surface of the second adhesive layer (4). With this configuration, even if the thickness of the second adhesive layer is within the above range, sufficient adhesive strength of the second adhesive layer can be secured.

[0053] B. Details of the laminated film

[0054] Below, details of each component provided by the laminated film will be described.

[0055] The laminated film (100) is typically an end-faced film with a finished end surface. As described above, the laminated film (100) comprises a functional film (3), a first adhesive layer (2), a second adhesive layer (4), a first release liner (1), and a second release liner (5).

[0056] B-1. Functional Film

[0057] The functional film (3) has an appropriate optical compensation function.

[0058] The functional film (3) has any suitable shape when viewed from the thickness direction.

[0059] As for the shape of the functional film (3) viewed from the thickness direction, for example, a polygonal shape can be used, preferably a square shape can be used, and more preferably a rectangular shape can be used. When the functional film is rectangular, the dimensions of the long side are typically 50 mm or more and 1000 mm or less, and the dimensions of the short side are typically 30 mm or more and 550 mm or less.

[0060] The functional film (3) may have a single-layer structure or a laminated structure.

[0061] As functional films (3), examples include a polarizing plate containing a polarizer, a phase difference film, and an optical laminate in which they are stacked.

[0062] In one embodiment, the functional film (3) is a polarizing plate including a polarizer.

[0063] B-1-1. Polarizer

[0064] Any suitable polarizer may be used as the polarizer. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0065] Specific examples of a polarizer composed of a single-layer resin film include a hydrophilic polymer film, such as a polyvinyl alcohol (PVA)-based film, a partially formalized PVA-based film, or a partially saponified ethylene-vinyl acetate copolymer-based film, to which a dyeing treatment with a dichroic substance such as iodine or a dichroic organic dye and a stretching treatment have been performed, and a polyene-based oriented film, such as a dehydrated PVA or a dehydrochlorinated polyvinyl chloride. Preferably, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is used, as it has excellent optical properties.

[0066] The above iodine dyeing is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The stretching ratio of the above uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. In addition, dyeing may be performed after stretching. If necessary, swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc., are performed on the PVA-based film. For example, by immersing the PVA-based film in water and washing it before dyeing, not only can contamination or anti-blocking agents on the surface of the PVA-based film be washed, but the PVA-based film can also be swollen to prevent dyeing unevenness.

[0067] Specific examples of polarizers obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer applied and formed on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer applied and formed on the resin substrate can be manufactured by, for example, applying a PVA-based resin solution to a resin substrate and drying it to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In one embodiment of the present invention, preferably, a polyvinyl alcohol-based resin layer comprising a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes stretching the laminate by immersing it in an aqueous boric acid solution. In addition, the stretching process may further include air-stretching the laminate at a high temperature (e.g., 95° or higher) prior to stretching in an aqueous boric acid solution, if necessary. Furthermore, in one embodiment of the present invention, preferably, the laminate is subjected to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by heating while being conveyed in the longitudinal direction. Typically, the manufacturing method of the present embodiment includes performing an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment on the laminate in this order. By introducing assisted stretching, it becomes possible to increase the crystallinity of the PVA and achieve high optical properties, even when PVA is applied on a thermoplastic resin. Additionally, by simultaneously increasing the orientation of the PVA in advance, problems such as a decrease in orientation or dissolution of the PVA can be prevented when it is immersed in water during subsequent dyeing or stretching processes, and it becomes possible to achieve high optical properties.In addition, when the PVA-based resin layer is immersed in a liquid, the disturbance of the orientation of polyvinyl alcohol molecules and the deterioration of orientation can be suppressed compared to the case where the PVA-based resin layer does not contain halogens. By doing so, the optical properties of the polarizer obtained through processing steps performed by immersing the laminate in a liquid, such as dyeing and underwater stretching, can be improved. Furthermore, optical properties can be improved by shrinking the laminate in the width direction through a drying shrinkage treatment. The obtained resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate, and any suitable protective layer according to the purpose may be laminated onto the peeled surface for use. Details of such a method for manufacturing a polarizer are described, for example, in Japanese Patent Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0068] The thickness of the polarizer is, for example, 1 μm to 80 μm, preferably 1 μm to 15 μm, more preferably 1 μm to 12 μm, even more preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. If the thickness of the polarizer is within this range, curling during heating can be well suppressed, and good appearance durability during heating is obtained.

[0069] The polarizer preferably exhibits absorption dichroism at any one of wavelengths from 380 nm to 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 90.0%, preferably 43.0% to 80.0%, and more preferably 44.5% to 70.0%.

[0070] In addition, the individual transmittance can be calculated as a Y value with corrected visual sensitivity by measuring, for example, the 2-degree field of view (C light source) of JIS Z8701.

[0071] The polarization degree of the polarizer is, for example, 40% or more, preferably 50% or more, more preferably 60% or more, even more preferably 97.0% or more, particularly preferably 99.0% or more, and particularly preferably 99.9% or more.

[0072] B-1-2. Protective layer

[0073] In addition to the polarizer, the polarizer may be provided with a protective layer. The protective layer is formed on at least one surface of the polarizer. In one embodiment, the protective layer is formed on both surfaces of the polarizer. The protective layer is typically bonded to the polarizer via any suitable adhesive layer (not shown).

[0074] The protective layer is composed of any suitable film. Specific examples of materials that serve as the main components of the film include transparent resins such as poly(norbornene)-based cycloolefin (COP), polyester-based resins such as polyethylene terephthalate (PET), cellulose-based resins such as triacetylcellulose (TAC), polycarbonate (PC), (meth)acrylic, polyvinyl alcohol, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, polyolefin, and acetate. Additionally, thermosetting resins or UV-curing resins such as (meth)acrylic, urethane, (meth)acrylurethane, epoxy, and silicone may also be used. Furthermore, "(meth)acrylic resin" refers to acrylic resin and / or methacrylic resin. In addition to this, glassy polymers such as siloxane-based polymers may also be used. Furthermore, the polymer film described in Japanese Patent Publication No. 2001-343529 (WO01 / 37007) may also be used. As the material for this film, a resin composition containing, for example, a thermoplastic resin having substituted or unsubstituted imide groups in its side chains and a thermoplastic resin having substituted or unsubstituted phenyl and nitrile groups in its side chains may be used, and for example, a resin composition having an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer may be used. The polymer film may, for example, be an extruded product of the resin composition. The material for the resin film may be used alone or in combination.

[0075] The thickness of the protective layer is, for example, 1 mm or less, preferably 1 μm to 500 μm, more preferably 5 μm to 150 μm.

[0076] B-2. First adhesive layer

[0077] The first adhesive layer (2) is located on one side in the thickness direction with respect to the functional film (3). In the example shown in the drawing, the first adhesive layer (2) is formed on one side in the thickness direction of the functional film (3).

[0078] The first adhesive layer (2) has any suitable shape when viewed from the thickness direction.

[0079] As for the shape of the first adhesive layer (2) viewed from the thickness direction, examples include polygonal, circular, elliptical, and other shapes, preferably square or other shapes, and more preferably rectangular or other shapes.

[0080] The size of the first adhesive layer (2) is smaller than the size of the functional film (3). When the first adhesive layer (2) is rectangular, the length of the long side is typically 85 mm or more and 1500 mm or less, and the length of the short side is typically 40 mm or more and 500 mm or less.

[0081] Additionally, the first adhesive layer (2) may have a concave portion extending inward from the outer perimeter edge and / or a through hole.

[0082] The first adhesive layer (2) is composed of any suitable adhesive. In one embodiment, the first adhesive layer (2) is composed of an optically transparent adhesive.

[0083] Examples of optically transparent adhesives include (meth)acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination, and mixing ratio of monomers forming the base resin of the adhesive, as well as the amount of crosslinking agent, reaction temperature, reaction time, etc., an adhesive having desired characteristics according to the purpose can be prepared.

[0084] The base resin of the adhesive may be used alone, or two or more types may be used in combination.

[0085] Among these optically transparent adhesives, (meth)acrylic adhesives are preferably used.

[0086] (Metha)acrylic adhesives typically include a (meth)acrylic polymer as a base resin. The content of the (meth)acrylic polymer is, for example, 50 mass% or more, preferably 70 mass% or more, and more preferably 90 mass% or more of the solid content of the (meth)acrylic adhesive.

[0087] (Metha)acrylate polymers have constituent units derived from alkyl (meth)acrylates. Also, (meth)acrylates refer to acrylates and / or methacrylates. The content ratio of constituent units derived from alkyl (meth)acrylates is, for example, 80 mass% or more, preferably 90 mass% or more.

[0088] As the alkyl group of the alkyl (meth)acrylate, for example, a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms may be used. The average number of carbon atoms of the alkyl group is preferably 3 to 9, and more preferably 3 to 6. Among the alkyl (meth)acrylates, butyl acrylate may be used.

[0089] (Meta)acrylic polymers may further have constituent units derived from monomers capable of copolymerizing with alkyl (meth)acrylates (copolymerizing monomers). Examples of copolymerizing monomers include carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, and heterocyclic ring-containing vinyl monomers.

[0090] Representative examples of copolymer monomers include acrylic acid, 4-hydroxybutyl acrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone.

[0091] (Meta)acrylic adhesives preferably contain a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents and peroxide-based crosslinking agents.

[0092] (Meta)acrylic adhesives may further contain any suitable additives (e.g., silane coupling agents, tackifiers, etc.).

[0093] Details of the adhesive layer or (meth)acrylic adhesive are described, for example, in Japanese Patent Publication No. 2006-183022, Japanese Patent Publication No. 2015-199942, Japanese Patent Publication No. 2018-053114, Japanese Patent Publication No. 2016-190996, International Publication No. 2018 / 008712, and Japanese Patent Publication No. 2014-115468, and the descriptions in these publications are incorporated into this specification by reference.

[0094] The storage modulus of the first adhesive layer (2) at 25℃ is, for example, 1×10 4 Pa~30×10 4 It is Pa, preferably 2×10 4 Pa~25×10 4 It is Pa, and more preferably 3×10 4 Pa~20×10 4 It is Pa.

[0095] In addition, the storage modulus of the adhesive layer is measured in accordance with JIS K 6868, for example, at a heating rate of 5℃ / min and a frequency of 1Hz.

[0096] The total light transmittance of the first adhesive layer (2) at a wavelength of 420 nm is, for example, 80% or more, preferably 85% or more. Meanwhile, the total light transmittance of the first adhesive layer (2) at a wavelength of 420 nm is, for example, 95% or less, and for example, 93% or less.

[0097] B-3. ​​Second adhesive layer

[0098] The second adhesive layer (4) is located on the opposite side of the first adhesive layer (2) with respect to the functional film (3). In the example shown in the drawing, the second adhesive layer (4) is formed on the other side in the thickness direction of the functional film (3).

[0099] The second adhesive layer (4) is composed of any suitable adhesive. As an adhesive constituting the second adhesive layer (4), for example, the same as the first adhesive layer (2) can be cited.

[0100] The storage modulus of the second adhesive layer (4) at 25℃ is, for example, 2×10 4 Pa~16×10 4 It is Pa, preferably 4×10 4 Pa~15×10 4 It is Pa.

[0101] B-4. 1st Release Liner

[0102] The first peel-off liner (1) is peelably attached to the first surface (21) of the first adhesive layer (2).

[0103] The first peel liner (1) is composed of any suitable plastic film. Examples of plastic films include polyethylene terephthalate (PET) film, polyethylene film, and polypropylene film.

[0104] On the surface of the first adhesive layer (2) side of the first peel liner (1), any suitable release treatment layer may be formed as needed.

[0105] Examples of release agents that form a release treatment layer include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents. Release agents can be used alone or in combination.

[0106] The thickness of the first peeling liner (1) is, for example, 10㎛ to 150㎛, and also, for example, 25㎛ to 100㎛.

[0107] In one embodiment, the first peel liner (1) is a medium peel liner.

[0108] The peeling force of the first peel liner (1) against the first adhesive layer (2) is, for example, 0.01 N / 50 mm or more, preferably 0.05 N / 50 mm or more. Meanwhile, the peeling force of the first peel liner (1) against the first adhesive layer (2) is, for example, 1 N / 50 mm or less, preferably 0.8 N / 50 mm or less. In addition, the peeling force is measured, for example, by a peeling force test using an autograph.

[0109] B-5. Second release liner

[0110] The second release liner (5) is located on the opposite side of the functional film (3) with respect to the second adhesive layer (4). The second release liner (5) is attached to the surface of the second adhesive layer (4) in the thickness direction so as to be peelable.

[0111] The second peeling liner (5) is made of any suitable plastic film. Examples of plastic films include polyethylene terephthalate (PET) film, polyethylene film, and polypropylene film.

[0112] The surface of the second adhesive layer (4) side of the second peel liner (5) may have any suitable release treatment layer formed thereon as needed.

[0113] Examples of release agents that form a release treatment layer include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents. Release agents can be used alone or in combination.

[0114] The thickness of the second peeling liner (5) is, for example, 10㎛ to 50㎛, and also, for example, 25㎛ to 40㎛.

[0115] In one embodiment, the second release liner (5) is a light release liner. The release force of the second release liner (5) on the second adhesive layer (4) is typically smaller than the release force of the first release liner (12) on the first adhesive layer (2).

[0116] The peeling force of the second release liner (5) against the second adhesive layer (4) is, for example, 0.8 N / 50 mm or less, preferably 1 N / 50 mm or less. Meanwhile, the peeling force of the second release liner (5) against the second adhesive layer (4) is, for example, 0.05 N / 50 mm or more, preferably 0.1 N / 50 mm or more.

[0117] C. Method for manufacturing laminated film

[0118] Next, with reference to FIGS. 4 to 8, a method for manufacturing a laminated film according to one embodiment of the present invention will be described.

[0119] In one embodiment, the method for manufacturing a laminated film (100) comprises: a process of preparing a first disc film (10) (see FIG. 4); a process of cutting the first adhesive layer (2) of the first disc film (10) into a product portion (25) and an non-product portion (26) (see FIG. 5); a process of peeling the non-product portion (26) from a first release liner (1) (see FIG. 6); a process of preparing a second disc film (20) (see FIG. 6); a process of bonding the first disc film (10) and the second disc film (20) to obtain an intermediate film (30) (see FIG. 7); and a process of cutting the intermediate film (30) to obtain a laminated film (100) (see FIG. 7).

[0120] According to this method, a laminated film can be smoothly manufactured in which the end surface of the first adhesive layer includes a flat portion and the thickness of the first adhesive layer relative to the width of the functional film is within the above-mentioned range.

[0121] C-1. Preparation Process of the First Disc Film

[0122] As shown in FIG. 4, in one embodiment, a first adhesive layer (2) is formed on the release treatment layer of the first peel liner (1) by any suitable method.

[0123] In addition, in the first disc film (10), the end surface of the first adhesive layer (2) in the plane direction is typically a surface at the same height as the end surface of the first peel liner (1) in the plane direction.

[0124] By this, a first disc film (10) having a first peel liner (1) and a first adhesive layer (2) is prepared.

[0125] C-2. Process of cutting the first adhesive layer into the product part and the non-product part.

[0126] Next, as shown in FIG. 5, the first adhesive layer (2) provided by the first disc film (10) is cut into a product portion (25) and an external product portion (26).

[0127] As a method for cutting the first adhesive layer (2), examples include blade cutting and laser cutting, and preferably blade cutting.

[0128] In the example shown in the drawing, the first adhesive layer (2) provided by the first peel liner (1) is cut into a product part (25) and an external product part (26) by a cutting blade (6).

[0129] Examples of cutting blades include rotary blades, Thomson blades, and Pinnacle (registered trademark) blades, and preferably Thomson blades.

[0130] The product portion (25) has a desired shape. The shape of the product portion (25) viewed from the thickness direction is identical to the first adhesive layer (2) provided by the laminated film (100) described above.

[0131] C-3. Process of peeling off the product-external portion from the first peel liner

[0132] Next, as shown in FIG. 6, the product-external portion (26) is peeled off from the first peeling liner (1) by any suitable method.

[0133] C-4. Process for preparing the second disc film

[0134] In addition, in one embodiment, a second adhesive layer (4) is formed on the release treatment layer of the second peel liner (5) described above by any suitable method, and then a functional film (3) is attached through the second adhesive layer (4).

[0135] By this, a second disc film (20) is prepared having the second peel liner (5), the second adhesive layer (4), and the functional film (3) in this order.

[0136] C-5. Process of bonding the first disc film and the second disc film

[0137] Next, the functional film (3) provided by the second disc film (20) is brought into contact with the product portion (25) on the first peel liner (1), and the first disc film (10) and the second disc film (20) are bonded.

[0138] By this, an intermediate film (30) is obtained as shown in FIG. 7.

[0139] C-6. Process of cutting the intermediate film

[0140] Next, the intermediate film (30) is cut so that the end surface of the functional film (3) is outward from the end surface of the product part (25).

[0141] As a method of cutting the intermediate film (30), examples include blade cutting and laser cutting, and preferably blade cutting.

[0142] In the example shown in the drawing, the intermediate film (30) is cut by the cutting blade (7).

[0143] Examples of cutting blades include rotary blades, Thomson blades, and Pinnacle (registered trademark) blades, and preferably Thomson blades.

[0144] By this, the laminated film (100) described above is manufactured as shown in FIG. 1.

[0145] The laminated film (100) is provided with a first release liner (1), a product portion (25) (a first adhesive layer (2)), a functional film (3), a second adhesive layer (4), and a second release liner (5) in this order.

[0146] The functional film (3) provided by the laminated film (100) includes an adhesive area (31) that overlaps with the product portion (25) when the product portion (25) is projected onto the functional film (3) in the thickness direction. The adhesive area (31) is located inward from the end surface of the functional film (3) in the plane direction.

[0147] D. Finishing method for laminated films

[0148] As shown in FIG. 8, the end surface of the laminated film (100) described in items A to C is finished such that the thickness t (t / A) of the first adhesive layer (2) with respect to the width A of the margin area (32) is within the range described above.

[0149] In the finishing process of the laminated film, typically, a plurality of laminated films (100) are laminated on a lower pressure jig (81). More specifically, a plurality of laminated films (100) are laminated on the lower pressure jig (81) such that virtual lines passing through the center of the laminated film (100) and parallel to the thickness direction coincide with each other.

[0150] The lower pressure jig (81) has any suitable shape. The lower pressure jig (81) typically has a flat surface, and a laminated film (100) is laminated on the flat surface.

[0151] The number of layers of the laminated film (100) is, for example, 50 or more, preferably 100 or more, more preferably 150 or more, and even more preferably 200 or more. Meanwhile, the number of layers of the laminated film (100) is, for example, 1000 or less, preferably 600 or less, more preferably 400 or less, and even more preferably 300 or less.

[0152] Next, regarding a plurality of laminated films (100), an upper pressure jig (82) is brought into contact with the lower pressure jig (81) from the opposite side, and the plurality of laminated films (100) are inserted by the upper pressure jig (82) and the lower pressure jig (81).

[0153] The upper pressure jig (82) can move relative to the lower pressure jig (81) in the lamination direction of the laminated film (100). Any suitable configuration can be adopted for the upper pressure jig (82) as long as it can fit a plurality of laminated films (100) between it and the lower pressure jig (81).

[0154] The clamp pressure for a plurality of laminated films (100) can be any and appropriate value as long as it can fix the laminated films (100). The clamp pressure per unit area is, for example, 0.05 N / mm² or more, preferably 0.08 N / mm² or more, more preferably 0.1 N / mm² or more. Meanwhile, the clamp pressure per unit area is, for example, 0.5 N / mm² or less, preferably 0.3 N / mm² or less.

[0155] In addition, the clamp pressure is measured, for example, by a pressure distribution measuring system (tactile sensor).

[0156] By this, a plurality of laminated films (100) are fixed to the upper pressure jig (82) and the lower pressure jig (81).

[0157] With a plurality of laminated films (100) fixed to an upper pressure jig (82) and a lower pressure jig (81), the cutting target area of ​​the laminated film (100) is located outside the upper pressure jig (82) and the lower pressure jig (81) in a direction orthogonal to the lamination direction.

[0158] Next, the end surface of the fixed laminated film (100) is cut by an arbitrary and suitable cutting tool (9).

[0159] As a cutting tool (9), examples include an end mill rotatable about an axis parallel to the lamination direction of the laminated film, and a front plate rotatable about an axis perpendicular to the lamination direction of the laminated film. In the example shown in the drawing, the cutting tool (9) is an end mill. Below, the case where the cutting tool (9) is an end mill (9a) will be described in detail.

[0160] In the finishing process, the end mill (9a) contacts the end surface of the laminated film (100) and cuts the cutting target area of ​​the laminated film (100).

[0161] The number of cutting blades of the end mill (9a) can be appropriately set. The number of cutting blades is, for example, one or more. Meanwhile, the number of cutting blades is, for example, six or fewer, preferably four or fewer.

[0162] The twist angle of the cutting edge is, for example, 0° or more, preferably 10° or more. Meanwhile, the twist angle of the cutting edge is, for example, 70° or less, preferably 60° or less.

[0163] As a material for the cutting edge, examples include cemented carbide or high-speed steel, and preferably cemented carbide.

[0164] The Vickers hardness (HV hardness) of the cutting edge is, for example, 800 or higher, preferably 1500 or higher. Meanwhile, the HV hardness of the cutting edge is, for example, 2500 or lower, preferably 1900 or lower.

[0165] The rotational direction of the end mill (9a) may be clockwise or counterclockwise when viewed from a plane. In the finishing process, the end mill (9a) rotates at a constant speed.

[0166] The rotational speed of the end mill (9a) is, for example, 300 rpm or more, preferably 500 rpm or more. Meanwhile, the rotational speed of the end mill (9a) is, for example, 100,000 rpm or less, preferably 50,000 rpm or less.

[0167] The end mill (9a) can move relative to the fixed laminated film (100) while rotating as described above. The end mill may move while the laminated film (100) is not moving, or the laminated film (100) may move while the end mill is not moving. In one embodiment, the end mill moves around the laminated film (100) in a unidirectional direction (preferably clockwise when viewed from a plane) at the following feed speed around the laminated film (100) in the fixed state as described above, thereby cutting the entire cutting target area of ​​the laminated film (100).

[0168] The feed speed of the end mill in the finishing process (relative movement speed with respect to the end surface of the laminated film (100)) is, for example, 10 mm / min or more, preferably 50 mm / min or more, and, for example, 5000 mm / min or less, preferably 3500 mm / min or less.

[0169] The amount of material removed during finishing is, for example, 50㎛ to 1000㎛, and preferably 100㎛ to 500㎛.

[0170] By the above, a plurality of laminated films (100) with appropriately finished end surfaces can be manufactured collectively. In the following, the finished laminated film (100) is referred to as an end surface processed film and may be distinguished from the laminated film (100) before the finishing process. In the end surface processed film, the thickness t (t / A) of the first adhesive layer (2) with respect to the width A of the margin area (32) is adjusted to be within the above-mentioned range.

[0171] E. Image display device

[0172] The laminated film having undergone the finishing process described in item D above can be applied to an image display device. Examples of image display devices include liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices, inorganic EL display devices).

[0173] In one embodiment, the image display device includes an image display cell and a front transparent plate or touch panel disposed on the viewing side of the image display cell. When applying a laminated film to such an image display device, typically, a second release liner (5) is peeled off from a second adhesive layer (4), and a functional film (3) is attached to the image display cell by the second adhesive layer (4), and then a first release liner (1) is peeled off from a first adhesive layer (2) and a front transparent plate or touch panel is attached to the first adhesive layer (2). By doing so, the first adhesive layer (2) and the functional film (3) are formed between the front transparent plate or touch panel and the image display cell.

[0174] Examples

[0175] The present invention will be specifically described below by way of examples, but the present invention is not limited by these examples. The measurement method for each characteristic is as follows. Furthermore, unless specifically stated otherwise, "parts" and "%" in the examples and comparative examples are based on mass.

[0176] [Preparation Example 1: Fabrication of a Polarizing Plate]

[0177] As a thermoplastic resin substrate, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) having a long shape and a Tg of about 75°C was used, and corona treatment was performed on one side of the resin substrate.

[0178] A PVA aqueous solution (coating solution) was prepared by adding 13 parts by mass of potassium iodide to 100 parts by mass of a PVA-based resin mixed in a 9:1 ratio of polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Kosei Kagaku Kogyo Co., Ltd., trade name "Gosepamer") and dissolving the mixture in water.

[0179] A laminate was produced by applying the above PVA aqueous solution to the corona-treated surface of a resin substrate and drying it at 60°C to form a PVA-based resin layer with a thickness of 13 μm.

[0180] The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (length direction) in an oven at 130°C (air-assisted stretching treatment).

[0181] Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (an aqueous boric acid solution obtained by mixing 4 parts by mass of boric acid with 100 parts by mass of water) (insolubilization treatment).

[0182] Next, the polarizer was immersed for 60 seconds in a dyeing bath at a liquid temperature of 30°C (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by mass of water) while adjusting the concentration so that the final obtained polarizer's elemental transmittance (Ts) became a desired value (dyeing treatment).

[0183] Next, it was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (an aqueous boric acid solution obtained by mixing 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with 100 parts by mass of water) (crosslinking treatment).

[0184] Afterwards, the laminate was immersed in an aqueous boric acid solution (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%) at a liquid temperature of 70°C, and uniaxial stretching was performed between rolls of different peripheral speeds so that the total stretching ratio in the longitudinal direction (length direction) became 5.5 times (underwater stretching treatment).

[0185] Afterwards, the laminate was immersed in a cleaning bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by mass of potassium iodide with 100 parts by mass of water) (cleaning treatment).

[0186] Afterwards, while drying in an oven maintained at approximately 90°C, it was brought into contact with a heated SUS roller maintained at a surface temperature of approximately 75°C (drying shrinkage treatment).

[0187] In this way, a polarizer with a thickness of about 5 μm was formed on a resin substrate, and a laminate having a composition of a resin substrate / polarizer was obtained.

[0188] A TAC film (thickness 25 μm) was bonded as a first protective layer to the polarizer surface of the obtained laminate (the side opposite to the resin substrate) via an acrylic adhesive layer (thickness 5 μm). Subsequently, the resin substrate was peeled off, and a TAC film (thickness 25 μm) was bonded as a second protective layer to the exposed polarizer surface via an acrylic adhesive layer (thickness 5 μm). By doing this, a polarizing plate having a configuration of a first protective layer / polarizer / second protective layer was obtained. The polarizing plate had an elongated shape.

[0189] [Example 1]

[0190] An adhesive sheet having a long shape (manufactured by Nitto Denko, product name: LUCIACS CS98210U) was attached to a first release liner having a long shape (a PET-based resin film with a release treatment layer formed thereon).

[0191] By this, a first disc film having the composition of a first release liner / adhesive sheet (first adhesive layer) was prepared. The thickness t of the first adhesive layer is shown in Table 1.

[0192] Next, the first adhesive layer provided by the first disc film was cut by a Thomson blade into a product part having a desired shape and an excluding product part. The product part had an approximately rectangular shape when viewed from the thickness direction. The lengthwise dimension of the product part was 145.45 mm, and the widthwise dimension of the product part was 67.65 mm.

[0193] After that, the part outside the product was peeled off and removed from the first release liner.

[0194] As a result, only the product portion was left on the first peel liner.

[0195] In addition, an acrylic adhesive layer (thickness 23 μm) as a second adhesive layer was interposed on a second release liner (a PET-based resin film having a release treatment layer) having a long shape, and the polarizing plate obtained in Preparation Example 1 was attached.

[0196] By this, a second disc film having the configuration of a second release liner / second adhesive layer / polarizer was prepared.

[0197] Next, the polarizing plate provided by the second disc film was brought into contact with the product portion on the first release liner, and the first disc film and the second disc film were bonded.

[0198] By this, an intermediate film having the composition of a first release liner / product part / polarizer / second adhesive layer / second release liner was prepared.

[0199] Next, the first release liner, the polarizing plate, the second adhesive layer, and the second release liner were cut collectively by a Thomson blade so that the end surface of the polarizing plate was outside the end surface of the product part.

[0200] By this, a laminated film having a desired external shape was prepared.

[0201] In the laminated film, the end surface of the first adhesive layer was located inward from the end surface of the polarizer in the plane direction. Meanwhile, the end surface of the polarizer, the end surface of the second adhesive layer, and the end surface of the second release liner were substantially the same height plane.

[0202] The polarizer equipped with the laminated film had an approximately rectangular shape when viewed from the thickness direction. The lengthwise dimension of the polarizer was 146.2 mm, and the widthwise dimension of the polarizer was 68.4 mm.

[0203] 60 sheets of these laminated films were prepared.

[0204] Next, as shown in FIG. 8, 30 laminated films were laminated onto a lower pressure jig to form a workpiece. Then, the workpiece was inserted by the lower pressure jig and the upper pressure jig, and the workpiece was fixed. The clamp pressure with the workpiece fixed was 1800 N.

[0205] The finishing portion of the workpiece was located outside the compression jig when viewed from the stacking direction.

[0206] Next, the finished part of the workpiece was cut by an end mill that is rotatable and also moves relative to a pressure jig. In the end mill, the cutting edge material was cemented carbide, the helix angle of the cutting edge was 30°, and the number of cutting edges was 2. In addition, the feed rate of the end mill was 2000 mm / min, and the rotational speed of the end mill was 35000 rpm.

[0207] More specifically, when viewed from above (opposite side of the lower pressure jig relative to the workpiece), the end mill rotated clockwise and moved relative to the laminated film clockwise while in contact with the end face of the workpiece.

[0208] As described above, multiple laminated films are finished collectively, and an end-faced finished film is prepared.

[0209] The amount of material removed during the finishing process was 300 μm.

[0210] In the end-face processed film, the polarizer included an adhesive region that overlaps with the first adhesive layer when the first adhesive layer is projected onto the functional film, and a margin region located outside the adhesive region in the plane direction. The width A of the margin region and the thickness t (t / A) of the first adhesive layer with respect to the width A of the margin region are shown in Table 1.

[0211] The end of the first adhesive layer in the finished laminated film (end-face processed film) was imaged from the plane direction using a microscope, and the adhesive deficiency of the first adhesive layer was evaluated according to the following criteria. The results are shown in Table 1.

[0212] ○ (Excellent): The distance between the end surface of the first adhesive layer and the end surface of the polarizer is 300㎛ or less, and the end surface of the first adhesive layer has a straight shape.

[0213] △ (Good): The distance between the end surface of the first adhesive layer and the end surface of the polarizer is 300㎛ or less, but the end surface of the first adhesive layer has a non-linear shape.

[0214] × (Not possible): The distance between the end surface of the first adhesive layer and the end surface of the polarizer exceeds 300㎛.

[0215] In addition, for each of the 60 sheets (2 sets of 30 sheets) of laminated film (end-face processed film), the first release liner was peeled off from the first adhesive layer, and the separation of the first adhesive layer was evaluated according to the following criteria. The results are shown in Table 1.

[0216] ○ (Excellent): No separation occurred (occurrence rate 0%).

[0217] △ (Good): The separation rate is greater than 0% and less than or equal to 5%.

[0218] × (Not possible): Separation rate exceeds 5%.

[0219] [Examples 2–6, Comparative Examples 1, 2]

[0220] A laminated film (end-face processed film) after finishing was prepared in the same manner as in Example 1, except that the width A of the margin area was adjusted to the value in Table 1. Adhesive deficiency and separation in the prepared end-face processed film were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0221] [Comparative Example 3]

[0222] A laminated film before finishing was prepared in the same manner as in Example 1, except that the thickness of the first adhesive layer was changed to 100 μm.

[0223] Next, the laminated film was finished in the same manner as in Example 1, except that the clamp pressure was changed so that the end of the first adhesive layer protruded from the end surface of the polarizer. In the obtained end surface finished film, the end surface of the first adhesive layer had a curved shape that was concave toward the inside.

[0224] The adhesive deficiency and separation in the prepared end-face processing film were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0225]

[0226] [evaluation]

[0227] As is evident from Table 1, if the thickness (t / A) of the first adhesive layer relative to the width of the margin area is 0.5 or more and 4.5 or less, it can be seen that the lack of adhesive in the first adhesive layer can be reliably suppressed. Industrial applicability

[0228] The laminated film of the present invention can be used in various industrial products, and is particularly preferably used in display devices such as liquid crystal display devices, organic EL display devices, and inorganic EL display devices. Explanation of the symbols

[0229] 1: First release liner 2: First adhesive layer 21: Page 1 22: Page 2 23: End side 3: Functional film 3a: Polarizer 31: Adhesion area 32: Margin area 4: Second adhesive layer 5: Second release liner 100: Laminated film

Claims

Claim 1 A first release liner, a first adhesive layer, a functional film, a second adhesive layer, and a second release liner are provided in this order, wherein the thickness of the first adhesive layer is greater than the thickness of the second adhesive layer, and the first adhesive layer has a first surface in contact with the first release liner, a second surface in contact with the functional film, and an end surface connecting the periphery edge of the first surface and the periphery edge of the second surface, wherein the end surface of the first adhesive layer includes a planar portion that extends in a substantially straight shape in a cross-section obtained by cutting the first adhesive layer in the thickness direction, and is also located inward from the end surface of the functional film in a plane direction orthogonal to the thickness direction of the first adhesive layer, and the functional film overlaps with the first adhesive layer when the first adhesive layer is projected onto the functional film in the thickness direction. A laminated film comprising an adhesive region and a margin region located outside the adhesive region in the plane direction, wherein the thickness of the first adhesive layer relative to the width of the margin region is 0.5 or more and 4.5 or less. Claim 2 A laminated film according to claim 1, wherein the thickness of the first adhesive layer relative to the width of the margin region is 3.0 or less. Claim 3 A laminated film according to claim 1 or 2, wherein the width of the margin region is 60㎛ or more and 350㎛ or less, and the thickness of the first adhesive layer is 25㎛ or more and 550㎛ or less. Claim 4 A laminated film according to claim 1 or 2, wherein the end surface of the first adhesive layer has a first end connected to the periphery edge portion of the first surface and a second end connected to the periphery edge portion of the second surface, and the first end and the second end are positioned offset from each other in the direction of the surface. Claim 5 A laminated film according to claim 4, wherein the planar portion extends over the entire area between the first stage and the second stage, and the angle formed between the planar portion and the second surface is 70° or more and less than 90° or exceeds 90° and is 110° or less. Claim 6 A laminated film according to claim 1 or 2, wherein, in the plane direction, the end surface of the first adhesive layer is located inwardly compared to the end surface of the second adhesive layer. Claim 7 In claim 1 or 2, the functional film is a laminated film that is a polarizing plate including a polarizer. Claim 8 The method comprises a process of preparing a first disc film having a first release liner and a first adhesive layer, a process of preparing a second disc film having a second release liner, a second adhesive layer, and a functional film in this order, a process of cutting the first adhesive layer having the first disc film into a product portion having a desired shape and a non-product portion, a process of peeling and removing the non-product portion from the first release liner, a process of contacting the functional film with the product portion to bond the first disc film and the second disc film to obtain an intermediate film, and a process of cutting the intermediate film to obtain a laminated film including the product portion, wherein the thickness of the first adhesive layer is greater than the thickness of the second adhesive layer, and the functional film having the laminated film includes an adhesive region that overlaps with the product portion when the product portion is projected onto the functional film in the thickness direction of the first adhesive layer, and the adhesive region is in the thickness direction and A method for manufacturing a laminated film located inwardly from the end surface of the functional film in an orthogonal plane direction.

Images