Method for producing cut film

Abstract

Provided is a method for manufacturing a cut thin film with which it is possible to easily determine whether or not cutting has been performed normally. A method of manufacturing a cut film according to an embodiment of the present invention includes a step of cutting a resin film with a milling cutter, the milling cutter being controlled so that a rotational speed is constant in the cutting step of the resin film, and a current value required for driving the milling cutter being monitored.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a cutting film. Background Art

[0002] Resin films are widely used in various industrial products. It is known that after such resin films are cut into a shape that meets the purpose, their cut surfaces are finely processed by cutting. For example, the following scheme has been proposed: the end face of the resin film is cut by an end mill to seek to improve the smoothness of the end face of the resin film (for example, refer to patent document 1). However, in the cutting process using milling cutter tools such as end mills, insufficiently cut parts are sometimes produced. At this time, due to the deterioration of the end face state of this part, cracks may occur. Therefore, when manufacturing a cut resin film (cutting film), a part of the manufactured cutting film is usually sampled and provided for destructive inspection to determine whether there is poor cutting during the cutting process. However, the destructive inspection requires a long inspection time, and the cutting film provided for inspection will be destroyed, resulting in time loss and product loss. Therefore, there is still room for improvement in improving the manufacturing efficiency of cutting films, and it is expected to smoothly determine whether the cutting process has been carried out normally.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-191464 Summary of the invention

[0006] Problems to be solved by the invention

[0007] The present invention has been made to solve the above-mentioned conventional problems, and a main object of the present invention is to provide a method for producing a cut film that can smoothly determine whether or not a cutting step has been normally performed.

[0008] Means used to solve problems

[0009] [1] A method for manufacturing a cut film according to an embodiment of the present invention includes a step of cutting a resin film with a milling cutter tool, wherein the milling cutter tool is controlled to have a constant rotation speed during the resin film cutting step, and a current value required to drive the milling cutter tool is monitored.

[0010] [2] In the method for producing a cut-to-size film described in [1] above, the milling cutter tool may be an end mill.

[0011] [3] In the method for manufacturing a cut film described in [1] or [2] above, when the current value monitored from the start of cutting to the end of cutting the resin film exceeds the first threshold value, the cut film can be judged as a good product; when the current value monitored from the start of cutting to the end of cutting the resin film is below the first threshold value, the cut film can be judged as a defective product.

[0012] [4] In the method for manufacturing a cutting film described in any one of [1] to [3] above, when the cutting amount of the resin film is greater than 75 μm, the first threshold value can be calculated based on the expected current value set according to the cutting amount and the reference current value when the milling cutter tool is idling, and by the following formula (1-1).

[0013] First threshold value = expected current value - {(expected current value - reference current value) × 0.7} (1-1)

[0014] [5] In the method for manufacturing a cutting film described in any one of [1] to [3] above, when the cutting amount of the resin film is less than 75 μm, the first threshold value can be calculated based on the expected current value set according to the cutting amount and the reference current value when the milling cutter tool is idling, and by the following formula (2-1).

[0015] First threshold value = expected current value - {(expected current value - reference current value) × 0.4} (2-1)

[0016] [6] In the method for producing a cutting-machined thin film described in any one of [1] to [3] above, the first threshold value may be a maximum current value when the milling cutter tool is idling.

[0017] [7] In the method for manufacturing a cut film described in any one of [3] to [6] above, when the current value monitored from the start of cutting to the end of cutting the resin film is less than a second threshold value, the cut film can be judged as a good product; and when the current value monitored from the start of cutting to the end of cutting the resin film is greater than the second threshold value, the cut film can be judged as a defective product.

[0018] [8] In the method for manufacturing a cutting film described in [7] above, when the cutting amount of the resin film is greater than 75 μm, the second threshold value can be calculated based on the expected current value set according to the cutting amount and the reference current value when the milling cutter tool is idling, and by the following formula (1-2).

[0019] Second threshold value=expected current value+{(expected current value-reference current value)×0.7} (1-2).

[0020] [9] In the method for manufacturing a cutting film described in [7] above, when the cutting amount of the resin film is less than 75 μm, the second threshold value can be calculated based on the expected current value set according to the cutting amount and the reference current value when the milling cutter tool is idling, and by the following formula (2-2).

[0021] Second threshold value=expected current value+{(expected current value-reference current value)×0.4} (2-2).

[0022]

[10] In the method for producing a cutting film according to any one of [1] to [9] above, the resin film may be a laminated film including a first film and a pressure-sensitive adhesive layer laminated on the first film.

[0023]

[11] In the method for producing a cut-machined film described in

[10] above, the surface to be cut by the milling cutter tool in the laminated film may include a portion having an arc shape when viewed in the lamination direction of the laminated film.

[0024] Effects of the Invention

[0025] According to the embodiment of the present invention, it is possible to smoothly determine whether or not cutting processing has been normally performed, and it is possible to improve the production efficiency of the cutting-processed thin film. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flowchart of a method for producing a cut-to-size thin film according to one embodiment of the present invention.

[0027] Figure 2 yes Figure 1 A top view of a laminated film used in a method for producing a cutting film.

[0028] Figure 3 yes Figure 2 Schematic cross-sectional view of a laminated film.

[0029] Figure 4 It is a top view of a laminated film having an opening.

[0030] Figure 5 This is an enlarged photograph of the cut surface of the cut film judged as a good product in Example 1.

[0031] Figure 6 This is an enlarged photograph of the cut surface of the cut film determined as a defective product in Example 1. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0033] A. Overview of the method for producing a cutting film

[0034] Figure 1 is a flow chart of a method for manufacturing a cutting film according to one embodiment of the present invention; Figure 2 yes Figure 1 A top view of a laminated film used in a method for manufacturing a cutting film; Figure 3 yes Figure 2 Schematic cross-sectional view of a laminated film.

[0035] The manufacturing method of the cutting film of the embodiment of the present invention includes a process (cutting process) of cutting a resin film 2 with a milling cutter tool 1. In the cutting process of the resin film 2, the milling cutter tool 1 is controlled in a manner that the rotation speed is constant, and the current value required to drive the milling cutter tool 1 is monitored. In such a cutting process, the rotation speed of the milling cutter tool is controlled to be constant, so when the cutting amount of the resin film by the milling cutter tool changes, the resistance applied to the milling cutter tool will change, and therefore the current value required to drive the milling cutter tool will also change. Therefore, by monitoring the current value required to drive the milling cutter tool, the degree of cutting performed by the milling cutter tool can be grasped, and it can be smoothly determined whether the cutting process is carried out normally. As a result, it is possible to seek to improve the manufacturing efficiency of the cutting film.

[0036] Examples of the milling tool include an end mill rotatable about an axis parallel to the thickness direction of the resin film and a face mill rotatable about an axis orthogonal to the thickness direction of the resin film. In the example shown, the milling tool is an end mill.

[0037] In one embodiment, when the current value monitored from the start of cutting of the resin film to the end of cutting exceeds the first threshold value, the cut film is judged as a good product, and when the current value monitored from the start of cutting of the resin film to the end of cutting reaches below the first threshold value, the cut film is judged as a defective product. When the monitored current value reaches below the first threshold value, the end surface of the resin film is not sufficiently processed, and the risk of defects such as cracks on the customer side or in the market may become greater. Thus, the cut film that has been properly cut can be stably judged as a good product.

[0038] In one embodiment, when the current value monitored from the start of cutting of the resin film to the end of cutting is less than the second threshold value, the cut film is judged as a good product, and when the current value monitored from the start of cutting of the resin film to the end of cutting reaches or exceeds the second threshold value, the cut film is judged as a defective product. In other words, when the monitored current value exceeds the first threshold value as the lower limit and is less than the second threshold value as the upper limit, the cut film is judged as a good product. Therefore, the cut film can be accurately judged.

[0039] In one embodiment, when the cutting amount of the resin film is greater than 75 μm, the first threshold value can be calculated based on the expected current value set according to the cutting amount and the reference current value when the milling cutter tool (representatively, the end mill 1) is idling, and the following formula (1-1) can be used.

[0040] First threshold value = expected current value - {(expected current value - reference current value) × 0.7} (1-1)

[0041] In this case (when the cutting amount is 75 μm or more), the second threshold value serving as the upper limit may be set by the following formula (1-2).

[0042] Second threshold value = expected current value + {(expected current value - reference current value) × 0.7} (1-2)

[0043] When the cutting amount of the resin film is less than 75 μm, the first threshold value can be obtained by the following formula (2-1) based on the expected current value set according to the cutting amount and the reference current value when the milling tool (representatively, the end mill 1) is idling.

[0044] First threshold value = expected current value - {(expected current value - reference current value) × 0.4} (2-1)

[0045] In this case (when the cutting amount is less than 75 μm), the second threshold value serving as the upper limit may be set by the following formula (2-2).

[0046] Second threshold value = expected current value + {(expected current value - reference current value) × 0.4} (2-2)

[0047] When the cutting amount (the width of the cutting portion) of the resin film is more than 75μm, the current value required to drive the milling tool (end mill) will be relatively large, and when the cutting amount (the width of the cutting portion) of the resin film is less than 75μm, the current value required to drive the milling tool (end mill) will be relatively small. Therefore, different thresholds can be set according to the cutting amount. If the judgment criterion for good and bad products, i.e., the threshold, is set as described above, the cut film with a cutting surface in an appropriate state can be stably manufactured into a good product.

[0048] In addition, the current value required to drive the milling tool varies when cutting and when idling. The expected current value is typically the average of the maximum current value and the minimum current value assumed to be required when the milling tool (end mill) cuts the corresponding amount of cutting. In addition, the reference current value is typically the average of the maximum current value and the minimum current value when the milling tool (end mill) is idling.

[0049] In another embodiment, the first threshold is the maximum current value when the milling tool (end mill) is idling. Even if the first threshold is used as a judgment standard, it is possible to appropriately judge whether the cut film is good or bad.

[0050] B. Details of resin film

[0051] The resin film cut in the cutting step may also be a laminated film 2 formed by laminating a plurality of films (layers). The laminated film 2 typically includes a first film 51 and an adhesive layer 71 laminated on the first film 51. In one embodiment, the laminated film 2 includes: a polarizer 5 including a polarizer 51 as an example of a first film; a first adhesive layer 71 laminated on the polarizer 5; a brightness enhancement film 8 attached to the polarizer 5 via the first adhesive layer 71; and a second adhesive layer 72 laminated on the opposite side of the polarizer 5 from the first adhesive layer 71. A release liner 6 may be temporarily adhered to the surface of the second adhesive layer 72 in a removable manner. A surface protective film 9 may also be attached to the surface of the brightness enhancement film 8 on the opposite side of the polarizer 5. That is, the laminated film 2 shown in the figure is an optical laminate, and includes: a release liner 6; a second adhesive layer 72; a polarizer 5; a first adhesive layer 71; and a surface protective film 9 in this order.

[0052] The total thickness of the laminated film 2 is, for example, 3000 μm or more, preferably 1500 μm or more, and, for example, 1000 μm or less, preferably 800 μm or less.

[0053] The laminate film 2 can adopt any appropriate shape. As the shape of the laminate film, a polygonal shape can be cited as a representative example, a quadrilateral shape can be cited as a preferred example, and a rectangular shape can be cited as a more preferred example. When the laminate film is a rectangular shape, the size of its long side is typically 30 mm or more and 1800 mm or less, and the size of its short side is typically 30 mm or more and 1200 mm or less.

[0054] The cutting surface of the milling cutter tool (end mill 1) in the laminated film 2 may also be the end surface of the laminated film 2. In one embodiment, the end surface (cutting surface) of the laminated film 2 includes a portion (arc surface) having an arc shape when viewed from the stacking direction of the laminated film 2. When the cutting surface has an arc surface, poor cutting of the arc surface is more likely to occur, and cracks are more likely to occur, compared with when the cutting surface does not have an arc surface. However, in a method for manufacturing a cut film of one embodiment, the current value required to drive the end mill is monitored during the cutting process. Therefore, even when the cutting surface has an arc surface, it is still possible to stably determine whether the cutting process has been performed normally, and it is possible to fully suppress the occurrence of cracks in the cut film that has been determined to be a good product.

[0055] In one embodiment, if Figure 2As shown, the cutting target surface of the milling cutter tool (end mill 1) in the laminate film 2 is the end face of the laminate film 2, and the end face of the laminate film 2 includes the inner surface of the recess 2a formed in the laminate film 2. In the present embodiment, the laminate film 2 is a special shape having a recess. The recess 2a is recessed inward from the peripheral edge of the laminate film 2. When the recess 2a is viewed from the stacking direction of the laminate film 2, it typically has a roughly U-shape. The radius of curvature of the arc surface of the recess 2a is, for example, greater than 0.5 mm and less than 7.0 mm. In addition, the arc surface contained in the end face of the laminate film may also be the chamfered portion of the corner of the laminate film.

[0056] In addition, if Figure 4 As shown, the cutting target surface of the end mill 1 in the laminated film 2 may also be the inner peripheral surface of the opening 2b formed in the laminated film 2. The opening 2b is typically a circular hole that penetrates the laminated film 2 in the lamination direction. The inner diameter range of the opening 2b is the same as the range of the curvature radius of the arc surface of the above-mentioned recessed portion.

[0057] The components of the laminated film 2 will be described in more detail below.

[0058] B-1. Polarizer

[0059] B-1-1. Polarizer

[0060] like Figure 3 As shown, any appropriate polarizer can be adopted as the polarizer 51. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0061] Specific examples of polarizers composed of a single-layer resin film include polarizers obtained by dyeing and stretching hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified films of ethylene-vinyl acetate copolymers using dichroic substances such as iodine and dichroic dyes, and polyene-based oriented films such as dehydrated PVA and dehydrochlorinated polyvinyl chloride films. Due to its excellent optical properties, it is preferred to use a polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching it.

[0062] The dyeing using iodine is performed, for example, by immersing the PVA membrane in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching can be performed after the dyeing treatment or while dyeing. In addition, dyeing can be performed after stretching. As needed, the PVA membrane is subjected to swelling treatment, cross-linking treatment, cleaning treatment, drying treatment, etc. For example, by immersing the PVA membrane in water and washing it with water before dyeing, not only can the dirt and anti-blocking agent on the surface of the PVA membrane be washed away, but the PVA membrane can also be swelled to prevent uneven dyeing.

[0063] As a specific example of a polarizer obtained using a laminate, there can be cited a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate or a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. The polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be made, for example, by the following method: a PVA-based resin solution is coated on a resin substrate, and the PVA-based resin layer is formed on the resin substrate by drying, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; and the PVA-based resin layer is made into a polarizer by stretching and dyeing the above-mentioned laminate. In one embodiment of the present invention, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. Stretching typically includes immersing the laminate in a boric acid aqueous solution for stretching. Furthermore, stretching may further include stretching the laminate in the air at a high temperature (e.g., above 95°C) before stretching in a boric acid aqueous solution as required. Furthermore, in one embodiment of the present invention, it is preferred to supply the laminate to a drying shrinkage treatment in which the laminate is transported in the length direction and heated to shrink by more than 2% in the width direction. Representatively, the manufacturing method of this embodiment includes sequentially applying an air auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment to the laminate. By introducing auxiliary stretching, the crystallinity of PVA can be improved even when PVA is coated on a thermoplastic resin, and high optical properties can be achieved. In addition, by simultaneously improving the orientation of PVA in advance, problems such as a decrease in orientation or dissolution of PVA when immersed in water in a subsequent dyeing process or a stretching process can be prevented, and high optical properties can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, the orientation disorder and decrease in orientation of the polyvinyl alcohol molecules can be suppressed compared to when the PVA-based resin layer does not contain a halide. Thus, the optical properties of the polarizer obtained by the treatment process of immersing the laminate in a liquid such as a dyeing treatment and an underwater stretching treatment can be improved. Furthermore, by shrinking the laminate in the width direction using a drying shrinkage treatment, the optical properties can be improved. The obtained laminate of resin substrate / polarizer can be used directly (that is, the resin substrate can be used as a protective layer of polarizer), or the resin substrate can be peeled off from the laminate of resin substrate / polarizer, and any appropriate protective layer corresponding to the purpose can be laminated on the peeled surface for use. The details of the manufacturing method of such a polarizer are recorded in, for example, Japanese Patent Publication No. 2012-73580 and Japanese Patent No. 6470455. These publications are cited in this specification as a reference for their entirety.

[0064] 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, further preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is within such a range, curling during heating can be well suppressed and good appearance durability during heating can be obtained.

[0065] The polarizer preferably exhibits absorption dichroism at any wavelength in the range of 380 nm to 780 nm. The single-unit transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and more preferably 44.5% to 46.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more.

[0066] B-1-2. Protective layer

[0067] In addition to the polarizer 51, the polarizing plate 5 may further include a protective layer 52. The protective layer 52 is provided on at least one side of the polarizer 51. The protective layer 52 of the illustrated example is arranged on the opposite side of the polarizer 51 from the brightness enhancement film 8. The protective layer 52 is typically bonded to the polarizer 51 via any appropriate adhesive layer (not shown).

[0068] The protective layer is formed by any suitable film that can be used as the protective layer of the polarizer. As the specific example of the material that becomes the main component of the film, cycloolefin (COP) systems such as polynorbornene systems, polyester systems such as polyethylene terephthalate (PET) systems, cellulose resins such as triacetyl cellulose (TAC), polycarbonate (PC) systems, (methyl) acrylic acid systems, polyvinyl alcohol systems, polyamide systems, polyimide systems, polyether sulfone systems, polysulfone systems, polystyrene systems, polyolefin systems, acetate systems and other transparent resins can be enumerated. In addition, thermosetting resins or ultraviolet curing resins such as (methyl) acrylic acid systems, carbamate systems, (methyl) acrylic acid carbamate systems, epoxy systems, silicone systems, etc. can also be enumerated. In addition, " (methyl) acrylic acid resin" refers to acrylic resin and / or methacrylic resin. In addition, glassy polymers such as siloxane polymers can also be enumerated. In addition, the polymer film described in Japanese Patent Publication No. 2001-343529 (WO01 / 37007) can also be used. As the material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl and nitrile group in the side chain can be used, for example, a resin composition having an alternating copolymer formed by isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be mentioned. The polymer film can be, for example, an extrusion molding of the above-mentioned resin composition. The material of the resin film can be used alone or in combination.

[0069] The thickness of the protective layer is preferably 1 mm or less, more preferably 1 μm to 500 μm, and further preferably 5 μm to 150 μm.

[0070] B-2. Brightness Enhancement Film

[0071] The brightening film 8 is attached to the polarizing plate 5 (polarizer 51) via the first adhesive layer 71. The brightening film 8 is a film that seeks to improve brightness by separating polarized light, and can be a linear polarized light separation type or a circular polarized light separation type. As the brightening film 8, for example, a film composed of a stretched film and a film composed of a liquid crystal layer can be cited. The brightening film 8 has the following functions: when light (for example, light from the backlight of an image display device) is incident, the light is separated into two polarized light components, so that linear polarized light of a specified polarization axis or circular polarized light of a specified direction is transmitted, and non-transmitted polarized light is reflected. By passing the non-transmitted polarized light through a reflective plate, etc., the light after depolarization is made to enter the brightening film 8 again, thereby improving the utilization efficiency of the specified polarized light. The details of the brightening film are recorded, for example, in Japanese Patent Gazette No. 2021-056304. The entire contents of the gazette are cited in this specification as a reference.

[0072] The thickness of the brightness enhancement film is, for example, 11 μm to 200 μm, and preferably 15 μm to 100 μm.

[0073] B-3. ​​Adhesive layer

[0074] The first adhesive layer 71 is located between the polarizer 51 and the brightness enhancement film 8 to bond them together. The second adhesive layer 72 is provided on the surface of the protective layer 52 opposite to the brightness enhancement film 8 .

[0075] The storage modulus of each of the first adhesive layer 71 and the second adhesive layer 72 at 25° C. is preferably 1.0×10 4 Pa~1.0×10 6 Pa, more preferably 1.0×10 4 Pa~1.0×10 5 When the storage elastic modulus of the adhesive layer is within the above range, the occurrence of defects in the adhesive layer can be stably suppressed during the cutting process.

[0076] The first adhesive layer 71 and the second adhesive layer 72 are respectively composed of adhesives. As an adhesive, any appropriate composition can be adopted. As a specific example of an adhesive constituting an adhesive layer, acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives can be cited. By adjusting the type, quantity, combination and ratio of the monomers of the base resin forming the adhesive, as well as the amount of the crosslinking agent, the reaction temperature, the reaction time, etc., an adhesive having the desired characteristics corresponding to the purpose can be prepared. The base resin of the adhesive can be used alone or in combination of two or more. From the viewpoints of transparency, processability and durability, acrylic adhesives (acrylic adhesive compositions) are preferred. Acrylic adhesive compositions typically include (meth) acrylic polymers as the main component. (Meth) acrylic polymers can be included in the adhesive composition in a ratio of, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more in the solid content of the adhesive composition. (Meth) acrylic polymers contain (meth) alkyl acrylate as the main component as a monomer unit. In addition, (meth)acrylate refers to acrylate and / or methacrylate. (Meth) alkyl acrylate can be preferably contained in the monomer component forming the (meth) acrylic polymer at a ratio of 80% by mass or more, more preferably at a ratio of 90% by mass or more. As the alkyl group of the (meth) alkyl acrylate, for example, a linear or branched alkyl group having 1 to 18 carbon atoms can be cited. The average number of carbon atoms of the alkyl group is preferably 3 to 9, more preferably 3 to 6. The preferred (meth) alkyl acrylate is butyl acrylate. As monomers (comonomers) constituting the (meth) acrylic polymer, in addition to the (meth) alkyl acrylate, carboxyl-containing monomers, hydroxyl-containing monomers, amide-containing monomers, aromatic ring-containing (meth) acrylates, heterocyclic vinyl monomers, etc. can be cited. As representative examples of comonomers, acrylic acid, 4-hydroxybutyl acrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone can be cited. The acrylic adhesive composition preferably contains a silane coupling agent and / or a crosslinking agent. As the silane coupling agent, for example, epoxy-containing silane coupling agents can be mentioned. As the cross-linking agent, for example, isocyanate cross-linking agents and peroxide cross-linking agents can be mentioned. In addition, the acrylic adhesive composition may contain an antioxidant and / or a conductive agent. The details of the adhesive layer or the acrylic adhesive composition are, for example, recorded 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, and International Publication No. 2018 / 008712, and the records of these publications are cited in this specification as reference.

[0077] The thickness of each of the first adhesive layer 71 and the second adhesive layer 72 is, for example, 5 μm to 30 μm.

[0078] B-4. Surface protection film

[0079] In the example shown in the figure, the surface protection film 9 is located on the opposite side of the polarizer 5 relative to the brightness enhancement film 8, and is attached to the brightness enhancement film 8. The surface protection film 9 typically includes a base material 92 and an adhesive layer 91. As a material of the base material 92, for example, the same resin as the resin constituting the protective layer 52 can be cited. The adhesive layer 91 attaches the base material 92 of the surface protection film 9 to the brightness enhancement film 8. The adhesive layer 91 is described in the same manner as the above-mentioned adhesive layers 71 and 72.

[0080] B-5. Release liner

[0081] The release liner 6 is temporarily adhered to the surface of the second adhesive layer 72. The release liner 6 is formed of any appropriate resin film that can be used as a release liner. Specific examples of materials that become the main component of the resin film include polyethylene terephthalate (PET), polyethylene, and polypropylene. The materials of the resin film can be used alone or in combination. A release treatment layer can also be provided on the contact surface of the release liner 6 with the second adhesive layer 72. As release treatment agents that form the release treatment layer, for example, silicone-based release treatment agents, fluorine-based release treatment agents, and long-chain alkyl acrylate-based release agents can be mentioned. The release treatment agents can be used alone or in combination.

[0082] The thickness of the release liner 6 is, for example, 5 to 60 μm, or preferably 20 to 45 μm. When a release treatment layer is provided, the thickness of the release liner refers to the thickness including the thickness of the release treatment layer.

[0083] C. Details of the method for producing a cutting film

[0084] In one embodiment, the method for making a cutting film is as follows Figure 1 The method includes the following steps: the above-mentioned cutting step (S1); a step of judging whether the current value monitored in the cutting step exceeds the first threshold value as the lower limit (the first judging step, S2); a step of judging whether the current value monitored in the cutting step is less than the second threshold value as the upper limit (the second judging step, S3); and a step of confirming the quality (the quality confirming step, S4). Such a method for manufacturing a cutting film can be implemented by any appropriate cutting device. In addition, the milling cutter tool can be an end mill or a front milling cutter, but the following is a detailed description of the case where the milling cutter tool is an end mill.

[0085] C-1. Cutting device

[0086] like Figure 2As shown, in one embodiment, the cutting device 10 includes: a stage (not shown); an end mill 1 ; a motor 3 ; and a control unit 4 .

[0087] The stage can support a laminated film 2 as an example of a resin film. In the cutting step, the laminated film 2 is fixed to a desired position on the stage by a jig (not shown).

[0088] In the cutting process, the end mill 1 contacts the cutting target surface of the laminated film to cut the laminated film. The end mill 1 can adopt any appropriate structure. The end mill has a cutting edge. The number of cutting edges can be set appropriately. The number of cutting edges of the cutting edge is, for example, more than 1, and for example, less than 6, preferably less than 4. The helix angle of the cutting edge is, for example, more than 0°, preferably more than 10°, and for example, less than 70°, preferably less than 60°. As the material of the cutting edge, for example, super-hard alloy and high-speed steel can be listed, and preferably super-hard alloy can be listed. The Vickers hardness (HV hardness) of the cutting edge is, for example, more than 800, preferably more than 1500, and for example, less than 2500, preferably less than 1900.

[0089] The end mill 1 is typically rotatable around an axis parallel to the stacking direction of the stacked film 2. The rotation direction of the end mill can be clockwise or counterclockwise when viewed from above. In the example shown in the figure, the rotation direction of the end mill is clockwise when viewed from above. During the cutting process, the end mill 1 rotates at a constant speed. The rotation speed of the end mill 1 is, for example, 300 rpm or more, preferably 500 rpm or more, and, for example, 100,000 rpm or less, preferably 50,000 rpm or less.

[0090] The end mill 1 rotates as described above while moving relative to the laminated film 2 supported by the stage. The end mill may move while the laminated film is fixed to the cutting device, or the end mill may move while the laminated film is fixed. In one embodiment, the end mill moves in one direction (preferably clockwise when viewed from above) around the laminated film 2 fixed to the cutting device at the following feed speed to cut the entire end surface of the laminated film 2.

[0091] The feed rate of the end mill in the cutting step (relative movement speed with respect to the cutting target surface of the laminated film) 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.

[0092] The motor 3 is a driving source that applies a driving force for rotation to the end mill 1. The motor 3 is connected so as to be able to transmit the driving force to the end mill 1. The motor 3 can adopt any appropriate motor.

[0093] The control unit 4 includes, for example, a central processing unit (CPU), a ROM, and a RAM. The control unit 4 is electrically connected to the motor 3 and can control the operation of the motor 3. More specifically, the control unit 4 can control the current value supplied to the motor 3 from a power supply (not shown) in such a manner that the number of rotations of the end mill 1 is constant. In addition, the control unit 4 can typically monitor and record the current value supplied to the motor 3 during the cutting process.

[0094] C-2. Cutting process (S1)

[0095] like Figure 1 As shown, in the cutting process (S1), the desired cutting amount of the cutting target surface of the laminated film is first set. The cutting amount is, for example, greater than 10 μm and less than 3 mm. Next, the control unit 4 calculates the expected current value required for cutting the cutting amount. Then, based on the calculated expected current value and the reference current value when the end mill is idling without contacting the laminated film, the control unit 4 calculates the first threshold value (lower limit) by the above formula (1-1) when the cutting amount is greater than 75 μm, and calculates the first threshold value (lower limit) by the above formula (2-1) when the cutting amount is less than 75 μm. In addition, the control unit 4 may also set the maximum current value when the end mill is idling as the first threshold value (lower limit).

[0096] In addition, the control unit 4 calculates the second threshold value (upper limit) by the above formula (1-2) based on the calculated expected current value and the reference current value when the end mill is idling, when the cutting amount is greater than 75 μm, and calculates the second threshold value (upper limit) by the above formula (2-2) when the cutting amount is less than 75 μm.

[0097] Next, in a state where the end mill 1 is in contact with the cutting target surface (end surface) of the laminate film 2, the control unit 4 controls the power supply to supply the current value to the motor 3. Thus, the end mill 1 is driven at the above-mentioned rotation speed and starts cutting the laminate film 2. Next, the end mill 1 rotates at a constant speed while moving along a pre-set route at the above-mentioned feed speed to cut the entire cutting target surface of the laminate film 2. Thus, the cutting process (S1) is completed and a cut film can be obtained. In the cutting process, the control unit 4 controls in such a way that the rotation speed of the end mill 1 is constant, so when the actual cutting amount is greater than the set value (the desired cutting amount), the resistance applied to the end mill 1 becomes larger and the current value supplied to the motor 3 becomes larger. On the other hand, when the actual cutting amount is less than the set value, the resistance applied to the end mill 1 becomes smaller and the current value supplied to the motor 3 becomes smaller. The control unit 4 monitors and stores the change in the current value.

[0098] C-3. First determination step (S2)

[0099] Next, in the first determination step (S2), it is determined whether the current value monitored and stored from the start of cutting of the laminated film to the end of cutting exceeds the first threshold value (lower limit value) of the cutting step. More specifically, when the first threshold value (lower limit value) is calculated by the above formula (1-1) or (2-1), it is determined whether the average value of the monitored and stored current values ​​exceeds the first threshold value (lower limit value). In addition, when the first threshold value (lower limit value) is the maximum current value when the end mill is idling, it is determined whether the monitored and stored current value exceeds the first threshold value (lower limit value) throughout the entire cutting process (from the start of cutting to the end of cutting).

[0100] For example, when the laminated film is fixed and supplied to the cutting process while being shifted from a desired position on the stage of the cutting device, the current value may become less than the first threshold value (lower limit value).

[0101] When the current value is below the first threshold value (lower limit value) (No in S2), the cut film contains insufficiently cut areas. Therefore, the cut film is judged as a defective product. Afterwards, it is determined whether the cut film that has been judged as a defective product can be readjusted to the desired size (S2-1). If the size cannot be readjusted (No in S2-1), it is discarded (S5). On the other hand, if the size can be readjusted, it is provided to the cutting process again (Yes in S2-1).

[0102] C-4. Second determination step (S3)

[0103] When the current value exceeds the first threshold value (lower limit value) in the first determination step (Yes in S2), the cut film is determined to be a good product, and in the second determination step (S3), it is determined whether the current value monitored and stored from the start to the end of cutting of the laminated film is less than the second threshold value (upper limit value) of the cutting process. More specifically, it is determined whether the average value of the monitored and stored current values ​​is less than the second threshold value (upper limit value).

[0104] For example, when the size of the laminated film provided for the cutting process is too large (when the laminated film is cut out from a bent mother sheet), or when the laminated film is cut due to an incorrect recipe (the route of the end mill), the current value may reach above the second threshold (upper limit).

[0105] When the current value is above the second threshold value (upper limit value) (No in S3), the cut film may be smaller than the desired product size. Therefore, the cut film is judged as a defective product. Afterwards, it is determined whether the size of the cut film that has been judged as a defective product is within the allowable range (S3-1). If the size of the cut film is outside the allowable range (No in S3-1), it is discarded (S5).

[0106] C-5. Quality confirmation process (S4)

[0107] When the current value is less than the second threshold value (upper limit value) in the second determination step (Yes in S3), or when the current value is greater than the second threshold value (upper limit value) but the size is within the allowable range in the second determination step (Yes in S3-1), it is determined in the quality confirmation step (S4) whether the quality of the cut film is within the allowable range. Examples of the quality confirmation step include size inspection, appearance inspection, and reliability inspection.

[0108] When the quality of the cutting film is outside the allowable range (No in S4), the cutting film is judged as a defective product and is discarded (S5). On the other hand, when the quality of the cutting film is outside the allowable range (Yes in S4), the cutting film has the desired size and excellent quality. Through the above, a cutting film with the desired size and excellent quality can be smoothly manufactured. The cutting surface of such a cutting film has cutting marks. In particular, when the helix angle of the cutting edge of the end mill is 0°, the cutting mark extends in a direction roughly parallel to the direction orthogonal to the thickness direction of the laminated film.

[0109] D. Image display device

[0110] The cutting film described in the above items A to C can be applied to an image display device. Therefore, an image display device including a cutting film is also included in the embodiment of the present invention. The image display device typically includes: an image display unit, and a cutting film attached to the image display unit via an adhesive layer. When the cutting film is manufactured by cutting a laminated film, the cutting film is typically attached to the image display unit via the second adhesive layer after the release liner is peeled off from the second adhesive layer. In addition, the surface protection film can be peeled off before using the cutting laminated film, and can also be used in a state attached to the surface of the polarizer. As representative examples of image display devices, liquid crystal display devices and electroluminescent (EL) display devices (for example, organic EL display devices, inorganic EL display devices) can be cited.

[0111] Example

[0112] The present invention is specifically described below by way of examples, but the present invention is not limited to these examples. The measuring methods of each characteristic are as follows. In addition, unless otherwise specified, the "parts" and "%" in the examples and comparative examples are based on mass.

[0113] [Preparation Example 1]

[0114] 1. Preparation of polarizer

[0115] As the thermoplastic resin substrate, a long amorphous polyethylene terephthalate copolymer film (thickness: 100 μm) having a Tg of about 75° C. was used, and one surface of the resin substrate was subjected to a corona treatment.

[0116] 13 parts by mass of potassium iodide was added to 100 parts by mass of a PVA-based resin prepared by mixing polyvinyl alcohol (polymerization degree of 4200, saponification degree of 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") in a ratio of 9:1, and the mixture was dissolved in water to prepare a PVA aqueous solution (coating solution).

[0117] The PVA aqueous solution was applied onto the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate.

[0118] The obtained laminate was uniaxially stretched to 2.4 times in the longitudinal direction (length direction) in an oven at 130° C. (in-air auxiliary stretching treatment).

[0119] Next, the laminate was immersed in an insolubilization bath (boric acid aqueous solution prepared by mixing 4 parts by mass of boric acid with respect to 100 parts by mass of water) at a liquid temperature of 40° C. for 30 seconds (insolubilization treatment).

[0120] Next, the film was immersed in a dyeing bath (an iodine aqueous solution prepared by mixing iodine and potassium iodide at a weight ratio of 1:7 per 100 parts by mass of water) at a liquid temperature of 30° C. for 60 seconds while adjusting the concentration so that the single body transmittance (Ts) of the polarizer finally obtained would be a desired value (dyeing treatment).

[0121] Next, the film was immersed in a crosslinking bath (boric acid aqueous solution prepared by blending 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with respect to 100 parts by mass of water) at a liquid temperature of 40° C. for 30 seconds (crosslinking treatment).

[0122] Afterwards, the laminate was immersed in an aqueous boric acid solution (boric acid concentration of 4 wt%, potassium iodide concentration of 5 wt%) at a liquid temperature of 70°C, and uniaxially stretched (underwater stretching treatment) between rollers with different peripheral speeds in such a way that the total stretching ratio in the longitudinal direction (length direction) reached 5.5 times.

[0123] Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution prepared by mixing 4 parts by mass of potassium iodide with respect to 100 parts by mass of water) having a liquid temperature of 20° C. (cleaning treatment).

[0124] Thereafter, the sheet was brought into contact with a SUS heating roll whose surface temperature was maintained at about 75° C. while being dried in an oven maintained at about 90° C. (drying shrinkage treatment).

[0125] In this manner, a polarizer having a thickness of about 5 μm was formed on the resin substrate, thereby obtaining a laminate having a structure of resin substrate / polarizer.

[0126] A TAC film (25 μm thick) was bonded as a protective layer to the polarizer surface (the surface opposite to the resin substrate) of the obtained laminate. Next, the resin substrate was peeled off to obtain a polarizing plate having a structure of protective layer / polarizer.

[0127] 2. Preparation of laminated film

[0128] A brightness enhancement film (manufactured by 3M, trade name DBEF, thickness 80 μm) was bonded to the polarizer surface of the polarizer obtained in 1. above via an acrylic adhesive layer (thickness 5 μm, first adhesive layer). Then, a surface protective film (thickness 55 μm) having a substrate (PET resin film) and an acrylic adhesive layer laminated on the substrate was bonded to the surface of the brightness enhancement film. A release liner (PET resin film provided with a release treatment layer) was bonded to the protective layer surface of the polarizer via an acrylic adhesive layer (thickness 20 μm, second adhesive layer).

[0129] Through the above, a laminated film having a structure of release liner / second adhesive layer / polarizer / first adhesive layer / brightness enhancement film / surface protection film is obtained. The laminated film has a substantially rectangular shape when viewed from the lamination direction. In the laminated film, the size of the long side is 146 mm, and the size of the short side is 68 mm.

[0130] [Example 1]

[0131] The laminated film obtained in Modulation Example 1 is set in a cutting device. The cutting device includes: a carrier; a rotatable end mill that can move relative to the carrier; a motor that provides driving force to the end mill; and a control unit that controls the current value supplied to the motor in such a way that the rotation speed of the end mill is constant. Regarding the end mill, the material of the cutting edge is superhard alloy, the HV hardness of the cutting edge is 1600, the helix angle of the cutting edge is 30°, and the number of cutting edges is 2. The laminated film is fixed to the carrier by a clamp.

[0132] Next, the first threshold is set according to the following cutting conditions. More specifically, the expected current value set according to the following cutting amount is 2.6A (maximum value 2.8V, minimum value 2.4V), and the reference current value when the end mill is idling is 1.8A (maximum value 2.0V, minimum value 1.6V). Therefore, the first threshold value of the lower limit of the current value during cutting is set to 2.0A (=2.6A-{(2.6A-1.8A)×0.7}).

[0133] <Cutting conditions>

[0134] Feed speed of end mill: 3000mm / min

[0135] End mill rotation speed: 35000rpm

[0136] Expected cutting amount: 0.1mm (100μm)

[0137] Next, the laminated film is cut under the above-mentioned cutting conditions. In the cutting process, the end mill rotates clockwise when viewed from above (on the opposite side of the carrier relative to the laminated film), and while it contacts the end surface of the laminated film, it moves relatively clockwise around the laminated film. At this time, the current value flowing in the motor driving the end mill is monitored. Thus, a cut film (optical laminate) is obtained.

[0138] The manufacturing of the above-mentioned cutting film is repeated for a plurality of times. Then, when the average value of the monitored current value exceeds the first threshold value (lower limit), the obtained cutting film is judged as a good product, and when the average value of the monitored current value reaches below the first threshold value (lower limit), the obtained cutting film is judged as a defective product.

[0139] [Example 2]

[0140] In the same manner as in Example 1, the laminated film obtained in Preparation Example 1 was set in a cutting device.

[0141] Next, the first threshold is set according to the following cutting conditions. More specifically, the expected current value set according to the following cutting amount is 2.3A (maximum value 2.4V, minimum value 2.2V), and the reference current value when the end mill is idling is 1.8A (maximum value 2.0V, minimum value 1.6V). Therefore, the first threshold value of the lower limit of the current value during cutting is set to 2.1A (=2.3A-{(2.3A-1.8A)×0.4}).

[0142] <Cutting conditions>

[0143] Feed speed of end mill: 3000mm / min

[0144] End mill rotation speed: 35000rpm

[0145] Expected cutting amount: 50μm

[0146] Next, the laminated film was cut under the above-mentioned cutting conditions in the same manner as in Example 1. At this time, the current value flowing through the motor driving the end mill was monitored. Thus, a cut film (optical laminate) was obtained.

[0147] The manufacturing of the above-mentioned cutting film is repeated for a plurality of times. Then, when the average value of the monitored current value exceeds the first threshold value (lower limit), the obtained cutting film is judged as a good product, and when the average value of the monitored current value reaches below the first threshold value (lower limit), the obtained cutting film is judged as a defective product.

[0148] [evaluate]

[0149] According to an embodiment of the present invention, by monitoring the current value required to drive the end mill, it is easy to determine whether the cutting process of the laminated film is normally performed. More specifically, when the monitored current value exceeds the first threshold value (lower limit), the cut film can be determined to be a good product. At this time, the cutting process is performed normally, and the cutting surface of the cut film is fully cut as a whole. Therefore, the cutting surface of the cut film is as follows: Figure 5 On the other hand, when the monitored current value is below the first threshold value, the cut film can be judged as a defective product. When the current value is below the first threshold value (lower limit) during the cutting process, the cut surface of the cut film includes an insufficiently cut portion. The insufficiently cut portion of the cut surface is as shown in FIG. Figure 6 As shown, it is relatively rough. Insufficient cutting in such a cutting surface can become the main cause of damage such as cracks.

[0150] Industrial Applicability

[0151] The method for producing a cut-processed film of the present invention can produce a cut-processed film for use in various industrial products. The cut-processed film is suitable for use in display devices such as liquid crystal display devices, organic EL display devices, and inorganic EL display devices.

[0152] Explanation of symbols

[0153] 1 End mill

[0154] 2 Laminated Film

[0155] 3 Motor

[0156] 4 Control Unit

[0157] 10 Cutting device

Claims

1. A method for producing a cut-processed film, comprising the step of cutting a resin film with a milling cutter tool, The milling cutter tool is controlled so that the rotation speed is constant during the cutting process of the resin film. The current value required for driving the milling cutter tool is monitored.

2. The method for producing a cutting film according to claim 1, wherein: The milling cutter tool is an end mill.

3. The method for producing a cutting film according to claim 1, wherein: When the current value monitored from the start to the end of cutting of the resin film exceeds a first threshold value, the cut film is determined to be a good product. When the current value monitored from the start to the end of cutting of the resin film is equal to or less than a first threshold value, the cut film is determined to be a defective product.

4. The method for producing a cutting film according to claim 3, wherein: When the cutting amount of the resin film is 75 μm or more, the first threshold value is obtained by the following formula (1-1) based on the expected current value set according to the cutting amount and the reference current value when the milling tool is idling. First threshold value=expected current value-{(expected current value-reference current value)×0.7}(1-1).

5. The method for producing a cutting film according to claim 3, wherein: When the cutting amount of the resin film is less than 75 μm, the first threshold value is obtained by the following formula (2-1) based on the expected current value set according to the cutting amount and the reference current value when the milling tool is idling: First threshold value=expected current value-{(expected current value-reference current value)×0.4}(2-1).

6. The method for producing a cutting film according to claim 3, wherein: The first threshold value is a maximum current value when the milling cutter tool is idling.

7. The method for producing a cutting film according to any one of claims 3 to 6, wherein: When the current value monitored from the start to the end of cutting of the resin film is less than the second threshold value, the cut film is determined to be a good product. When the current value monitored from the start to the end of cutting of the resin film is equal to or greater than a second threshold value, the cut film is determined to be a defective product.

8. The method for producing a cutting film according to claim 7, wherein: When the cutting amount of the resin film is 75 μm or more, the second threshold value is obtained by the following formula (1-2) based on the expected current value set according to the cutting amount and the reference current value when the milling tool is idling: Second threshold value=expected current value+{(expected current value-reference current value)×0.7}(1-2).

9. The method for producing a cutting film according to claim 7, wherein: When the cutting amount of the resin film is less than 75 μm, the second threshold value is obtained by the following formula (2-2) based on the expected current value set according to the cutting amount and the reference current value when the milling tool is idling: Second threshold value=expected current value+{(expected current value-reference current value)×0.4}(2-2).

10. The method for producing a cutting film according to claim 1, wherein: The resin film is a laminated film including a first film and an adhesive layer laminated on the first film.

11. The method for producing a cutting film according to claim 7, wherein: The surface of the laminated film to be cut by the milling tool includes a portion having an arc shape when viewed from a lamination direction of the laminated film.

Images