Method for evaluating the curl of a film, and method for manufacturing a film product.

Abstract

To accurately assess the actual degree of curl in the film piece. [Solution] The curl evaluation method includes the steps of: supporting the film piece 1 on the support member 3 with the first direction D1 of the film piece 1 substantially parallel to the vertical direction V and the central part of the second direction which is perpendicular to the first direction D1 of the film piece 1 attached to the support member 3, thereby leaving the area other than the area attached to the support member 3 free; and evaluating the degree of curl along the second direction D2 of the film piece 1.

Description

Technical Field

[0001] The present invention relates to a method for evaluating the degree of curl of a film and the like.

Background Art

[0002] When a film is manufactured, the film may curl. In order to grasp the degree of curl, for example, the methods described in Patent Documents 1 and 2 are known. Patent Document 1 discloses a method for evaluating the warp of an optical film, which scans a laser beam from above the optical film toward an end of the optical film placed on a stage and detects the reflected light of the laser beam from the end to obtain information on the height position of the end. Patent Document 2 discloses a curl measurement system including a surface height measurement device that measures the height position of the surface of a sheet body over the entire plane of the sheet body, and a curl measurement device that converts the data of the height position into image data and records curl measurement data related to the curl of the sheet body based on the image data.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

[0004] In the above conventional method, the film is installed with the film surface parallel to the horizontal plane, and the height of the end of the film is measured. However, in this method, due to the influence of gravity, the end of the film, which is the measurement part, may drop, and the degree of curl may be measured to be smaller than the actual value. For example, in Patent Document 1, a film (10) is placed on a horizontal stage (4), and the height position of the film's edge is measured by scanning it with a laser beam from above. However, in this case, the weight of the film may cause the height position of the edge to shift downwards from the actual position, potentially making it impossible to accurately measure the actual degree of curl of the film (10). Furthermore, in films where the adhesive layer is exposed, that adhesive layer adheres to horizontal surfaces such as stages. Therefore, with such films, there is a risk that the actual curl cannot be accurately measured. [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide a method for evaluating the curl of a film that can accurately evaluate the actual degree of curl of a film piece. [Means for solving the problem]

[0006] The first method for evaluating the curl of a film comprises the steps of: supporting the film piece on the support member with the first direction of the film piece substantially parallel to the vertical direction and the central part of the second direction, which is perpendicular to the first direction of the film piece, attached to the support member, thereby leaving the area other than the area attached to the support member free; and evaluating the degree of curl along the second direction of the film piece.

[0007] The second embodiment of the method for evaluating the curl of a film is the method of the first embodiment described above, wherein the evaluation of the curl includes imagining a virtual plane that includes the second central portion of the film piece, and measuring the perpendicular length from one edge of the film piece in the second direction to the virtual plane. The third embodiment of the film curl evaluation method is the first or second embodiment described above, wherein the support member has a support surface portion that extends in the vertical direction and is in contact with the back surface of the film piece, and a part or all of the central portion of the film piece in the second direction is attached to the support surface portion. The fourth method for evaluating the curl of a film is the third method described above, wherein the support surface is in the shape of a strip extending from one end to the opposite end in the first direction of the film piece. The fifth method for evaluating the curl of the film involves attaching the entire central portion of the film piece in the second direction to the strip-shaped support surface, as described in the fourth method. The sixth method for evaluating the curl of a film is the method of the fourth method described above, wherein at least one end and the opposite end of the central portion of the film piece in the second direction are attached to the strip-shaped support surface. The seventh method for evaluating the curl of the film is the method of any of the first to sixth methods described above, wherein the width of the support surface is 0.03 to 0.35 times the maximum length of the film piece in the second direction. The eighth method for evaluating the curl of a film involves attaching the film piece to the support member using magnetic force, in any of the first to seventh methods described above.

[0008] According to another aspect of the present invention, a method for manufacturing film products is provided. A method for manufacturing one form of film product comprises a raw material production step of producing a long strip of film raw material, and a product production step of producing a plurality of film products from the film raw material, wherein between the raw material production step and the product production step, there is a step of cutting off a portion of the film raw material to obtain a film piece, and evaluating the curl of the film piece by any of the first to eighth forms described above.

[0009] In the method for manufacturing the film product of the above-described form, the product manufacturing step includes correcting the curl of the film roll. [Effects of the Invention]

[0010] According to the curl evaluation method of the present invention, the degree of curl actually occurring in a film piece can be accurately evaluated. [Brief explanation of the drawing]

[0011] [Figure 1]Plan view of a film piece. [Figure 2] Side view of a film piece. [Figure 3] Side view of the curl measuring device according to the first embodiment. [Figure 4] Top view of the measuring device as seen from the direction of arrow IV in FIG. 3. [Figure 5] Front view of the measuring device as seen from the direction of arrow V in FIG. 3. [Figure 6] Schematic explanatory view of a system for producing a film reel, evaluating a film piece, and producing a film product. [Figure 7] Reference perspective view showing the process of cutting a film piece from a film reel. [Figure 8] Side view showing the process of attaching a film piece to the curl measuring device. [Figure 9] Front view of the curl measuring device with a film piece attached, as seen from the direction of arrow IX in FIG. 8. [Figure 10] Top view showing the curl measuring device after attaching a film piece. [Figure 11] Top view showing the state when the film piece curls to the side opposite to that in FIG. 10. [Figure 12] Top view showing the state where a film piece is attached to the support surface of the support member in the first example of the second embodiment. [Figure 13] Front view of the same. [Figure 14] Front view showing the state where a film piece is attached to the support surface of the support member in the second example of the second embodiment. [Figure 15] Front view showing the state where a film piece is attached to the support surface of the support member in the third example of the second embodiment. [Figure 16] Front view of the curl measuring device having the support member in the first example of the third embodiment. [Figure 17] Front view showing the state where a film piece is supported by the support member in the second example of the third embodiment. [Figure 18] Top view showing the process of measuring the amount of curl of a film piece using the curl measuring device according to the fourth embodiment. [Figure 19]A front view showing several examples of how a film piece is supported by a support member. [Modes for carrying out the invention]

[0012] In this specification, a numerical range expressed as "lower limit AAA to upper limit BBB" means a range between lower limit AAA and upper limit BBB. If multiple numerical ranges are listed separately, any lower limit and any upper limit can be selected to set "any lower limit to any upper limit". Please note that the figures are for reference only, and the dimensions, scale, and shape of the components shown may differ from those of the actual parts.

[0013] [Evaluation of film piece curl] According to the evaluation method of the present invention, the actual degree of curl of the film piece can be accurately evaluated without being substantially affected by gravity or other factors. The evaluation method includes the steps of: supporting the film piece on the support member by aligning the first direction of the film piece parallel to the vertical direction and attaching a portion or all of the central part of the second direction, which is perpendicular to the first direction of the film piece, to the support member, thereby leaving the area other than the area attached to the support member free; and evaluating the degree of curl along the second direction of the film piece. The evaluation of the degree of curl includes measuring the degree of curvature of one edge of the film piece. A detailed explanation follows below.

[0014] <Film fragment> The film sample is the film to be measured for curl. The film sample is flexible enough to be easily deformed. In terms of shape, the film pieces are sheet-like. This sheet-like shape refers to a predetermined shape in plan view, such as a roughly square or rectangular shape in plan view.

[0015] The shape of the film piece in plan view is not particularly limited. Note that "plan view" refers to viewing the film piece from the direction normal to the front (or back) surface. Figure 1 shows the plan view shape of film piece 1. For example, film piece 1 is formed in a roughly square shape in plan view as shown in Figure 1(a), a roughly rectangular shape as shown in Figure 1(b), a roughly equilateral triangle shape as shown in Figure 1(c), a roughly circular shape as shown in Figure 1(d), a roughly elliptical shape as shown in Figure 1(e), and other arbitrary plan view shapes not shown. As described later, in the method of the present invention, the degree of curl along the second direction of the film piece 1 is evaluated with the first direction of the film piece 1 substantially parallel to the vertical direction. The first direction refers to any one direction within the plane of the film piece 1. The second direction refers to a direction perpendicular to the first direction within the plane of the film piece 1. The vertical direction refers to the direction along gravity.

[0016] The size of the film piece 1 is not particularly limited, but if it is too small, it may be difficult to evaluate the degree of curl. From this viewpoint, the maximum length of the film piece 1 is 50 mm or more, preferably 100 mm or more. Also, if the film piece 1 is too large, it may be difficult to handle. From this viewpoint, the maximum length of the film piece 1 is 700 mm or less, preferably 400 mm or less. The maximum length of the film piece 1 refers to the maximum value of the straight-line length from any one edge of the film piece 1 to any other edge. For example, if the film piece 1 is roughly rectangular as shown in Figure 1(b), the maximum length of the film piece 1 is the length of the diagonal, and if the film piece 1 is roughly elliptical as shown in Figure 1(e), the maximum length of the film piece 1 is the major axis.

[0017] In terms of layer structure, the film piece 1 may be a single-layer structure or a multi-layer structure of two or more layers. Figure 2 shows the layer structure of film piece 1. The film piece 1 shown in Figure 2(a) has a single-layer structure. This single-layer film piece 1 is made of a resin film. The film piece 1 shown in Figure (b) has a two-layer structure consisting of a first layer 11 and a second layer 12 from bottom to top. The film piece 1 shown in Figure (c) has a three-layer structure consisting of a first layer 11, a second layer 12, and a third layer 13 from bottom to top. The film piece 1 shown in Figure (d) has a four-layer structure consisting of a first layer 11, a second layer 12, a third layer 13, and a fourth layer 14 from bottom to top. The film piece 1 shown in Figure (e) has a five-layer structure consisting of a first layer 11, a second layer 12, a third layer 13, a fourth layer 14, and a fifth layer 15 from bottom to top. In addition, although not shown, the film piece 1 may have a multi-layer structure of six or more layers.

[0018] Film piece 1 includes a resin film. In addition to the resin film, film piece 1 may further include at least one selected from an adhesive layer, a bonding layer, and any other suitable layer.

[0019] The aforementioned resin film contains a known synthetic resin. The term "resin film" also includes what is called a resin layer. Examples of the aforementioned synthetic resins include polyester resins such as polyethylene terephthalate and polyethylene naphthalate; cellulosic resins such as triacetylcellulose; polycarbonate resins; polyacetal resins; acrylic resins such as polymethyl methacrylate; styrene resins such as polystyrene; olefin resins such as polyethylene and polyolefins having a cyclic or norbornene structure; vinyl chloride resins; amide resins such as nylon 6; imide resins; sulfone resins; polyvinyl alcohol resins; vinylidene chloride resins; vinyl butyral resins; arylate resins; polyoxymethylene resins; polyvinyl alcohol resins; urethane resins; vinyl acetate resins; and liquid crystal polymers. The thickness of the resin film is not particularly limited, and is, for example, 1 μm to 300 μm, preferably 10 μm to 150 μm.

[0020] From a functional standpoint, the aforementioned resin film may be a film having optical functionality (hereinafter referred to as an optical film), a film not having optical functionality (hereinafter referred to as a non-optical film), or a film in which an optical film and a non-optical film are laminated. Examples of the optical films include polarizing films, phase difference films, anti-reflective films, light-diffusing films, brightness-enhancing films, and light-reflecting films. The polarizing film has the property of transmitting light that vibrates in one specific direction (polarized light) and blocking light that vibrates in other directions. Typical examples of polarizing films include polyvinyl alcohol-based resin layers or polyvinyl alcohol-based films dyed with dichroic substances such as iodine. Examples of the non-optical film include release liners and protective films. A release liner is a resin film on which at least one side is treated with a release agent (also called an easy-peel treatment). Examples of release liners include polyester films, olefin films, and acrylic films that have been treated with a release agent. As a protective film, known resin films such as polyester films can be used.

[0021] The adhesive layer is a layer made of an adhesive. The adhesive is tacky at room temperature and maintains its tackiness for a long period of time. Examples of the adhesives that can be used include transparent acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinylpyrrolidone adhesives, polyacrylamide adhesives, and cellulose adhesives. The thickness of the adhesive layer is not particularly limited, and is, for example, 1 μm to 30 μm. The adhesive layer is a layer made of adhesive. The adhesive is a layer interposed between two layers in order to firmly bond the two layers together. As the adhesive, for example, electron beam curing adhesives such as ultraviolet curing adhesives, solvent volatile adhesives, water-based adhesives, one-component or two-component reactive adhesives can be used. The thickness of the adhesive layer is not particularly limited, and is, for example, 0.5 μm to 20 μm.

[0022] In one embodiment, as shown in Figure 2(b), the first layer 11 is an adhesive layer and the second layer 12 is a resin film (for example, an optical film such as a polarizing film). Also, as shown in Figure 2(c), the first layer 11 is a resin film (for example, a release liner), the second layer 12 is an adhesive layer, and the third layer 13 is a resin film (for example, an optical film such as a polarizing film). Also, as shown in Figure 2(d), the first layer 11 is a resin film (for example, a release liner), the second layer 12 is an adhesive layer, the third layer 13 is a resin film (for example, an optical film such as a polarizing film), and the fourth layer 14 is a resin film (for example, an optical film such as a phase difference film). Furthermore, as shown in Figure (e), the first layer 11 is a resin film (e.g., a release liner), the second layer 12 is an adhesive layer, the third layer 13 is a resin film (e.g., an optical film such as a polarizing film), the fourth layer 14 is an adhesive layer or bonding layer, and the fifth layer 15 is a resin film (e.g., a protective film). In the layer configuration shown in Figures (c) to (e), where the first layer 11 is a release liner and the second layer 12 is an adhesive layer, only the release liner (first layer 11) can be peeled off from the adhesive layer (second layer 12). In other words, the release liner (first layer 11) can be peeled off at the interface between the first layer 11 and the second layer 12. Furthermore, if the film piece 1 is obtained from a film roll described later, the layer structure of the film roll and the layer structure of the film piece 1 are the same.

[0023] [First Embodiment] <Curl measuring device> Figures 3 to 5 show a curl measuring device A according to the first embodiment. Figure 3 is a side view of device A, Figure 4 is a top view thereof (viewed from the direction of arrow IV in Figure 3), and Figure 5 is a front view thereof (viewed from the direction of arrow V in Figure 3). Referring to Figures 3 to 5, the curl measuring device A includes a support member 3 that supports the film piece 1 and a measuring instrument 4 that measures the degree of curl of the film piece 1.

[0024] The support member 3 comprises a support body 32 having a support surface portion 31 that contacts the back surface of the film piece 1, and legs 33 that fix the support body 32 onto the mounting base 6. As will be described later, with the first direction D1 of the film piece 1 approximately parallel to the vertical direction (direction of gravity), a part or all of the film piece 1 is attached to the support surface portion 31 of the support member 3. The support surface portion 31 of the support body 32 is a flat surface. The flat support surface portion 31 extends approximately parallel to the vertical direction V. Therefore, the flat support surface portion 31 extends approximately perpendicular to the horizontal plane. Here, in this specification, "approximately" means including the range in which the effects of the present invention are achieved. The phrase "the support surface portion 31 is substantially parallel to the vertical direction V" means parallel within the range in which the effects of the present invention are achieved, and includes not only strictly parallel but also cases in which the flat surface (support surface portion 31) is inclined by 10 degrees or less, preferably 5 degrees or less, with respect to the vertical direction V.

[0025] As shown in the front view of Figure 5, the support surface portion 31 is an elongated strip extending in the vertical direction V. The length of the support surface portion 31 (length along the vertical direction V) is set as appropriate, but if it is too small, the contact area on the back surface of the film piece 1 will be relatively small, and the support of the film piece 1 by the support member 3 may become unstable. From this viewpoint, the length of the support surface portion 31, expressed in relation to the film piece 1, is 0.5 times or more, preferably 0.7 times or more, the length of the film piece 1 at the center in the second direction. There is no particular upper limit to the length of the support surface portion 31 (length along the vertical direction V), but if it is too large, the measuring device A will become large. From this viewpoint, the length of the support surface portion 31, expressed in relation to the film piece 1, is 5 times or less, preferably 3 times or less, the length of the film piece 1 at the center in the second direction. The length of the film piece 1 at the center in the second direction refers to the maximum length of the film piece 1 in the first direction D1 at the center of the film piece 1 in the second direction attached to the support member 3. In terms of specific values, the length of the support surface 31 is, for example, 50 mm to 400 mm.

[0026] The width 31W of the support surface 31 is not particularly limited, but if it is too small, the support of the film piece 1 by the support member 3 may become unstable. From this viewpoint, the width 31W of the support surface 31, expressed in relation to the film piece 1, is 0.03 times or more, preferably 0.04 times or more, and more preferably 0.05 times or more, the maximum length of the film piece 1 in the second direction D2. Also, if the width 31W of the support surface 31 is too large, it may hinder the curling of the film piece 1 along the second direction D2. From this viewpoint, the width 31W of the support surface 31, expressed in relation to the film piece 1, is 0.35 times or less, preferably 0.3 times or less, and more preferably 0.25 times or less, the maximum length of the film piece 1 in the second direction D2. In terms of specific values, the width 31W of the support surface portion 31 is, for example, 1.5 mm to 25 mm, preferably 2 mm to 10 mm, and more preferably 3 mm to 5 mm. For the maximum length of the film piece 1 in the second direction D2, please refer to the reference numeral 1W in Figure 9.

[0027] In the illustrated example, the support body 32 of the support member 3 is made up of a relatively thick plate-like body. One of the thickness surfaces (also called the end surface) of this plate-like body forms the support surface portion 31 of the support body 32. The legs 33 are interposed between the support body 32 and the mounting base 6, and stably fix the support body 32 to the mounting base 6. The mounting base 6 has, for example, a horizontal flat surface, and the support body 32 is fixed to this flat surface via the legs 33. Alternatively, the support body 32 may be fixed directly to the mounting base 6 without the interposition of the legs 33 (not shown).

[0028] Furthermore, in this embodiment, since magnetic force is used to attach the film piece 1 to the support surface portion 31, at least the support surface portion 31 of the support member 3 is made of a magnetic material. For example, the support body 32 having the support surface portion 31 is made of a magnetic material such as iron, nickel, or an alloy thereof. In addition, in order to attach the film piece 1 to the support surface portion 31, a stopper member 5 that can be attached and detached by magnetic force is provided on the support surface portion 31. The stopper member 5 consists of a stopper body 51 having a magnet and a gripping portion 52 provided on the stopper body 51. The stopper body 51 can be attached and detached from the support surface portion 31 by magnetic force. In Figures 3 and 4, the stopper member 5 when removed from the support surface portion 31 is shown by a dashed line. As described later, by bringing the back surface of the second central portion of the film piece 1 into contact with the support surface portion 31 and applying the fastening member 5 from the front surface of the second central portion of the film piece 1, the fastening body 51 of the fastening member 5 magnetically attaches to the support surface portion 31. As a result, the film piece 1 is held between the support surface portion 31 and the fastening member 5, and the second central portion of the film piece 1 is attached to the support surface portion 31.

[0029] The fastening part body 51 is in the shape of a long, narrow strip. The length of the fastening part body 51 is not particularly limited and may be approximately the same as the length of the support surface 31, or it may be smaller or larger than it. In order to stably attach the film piece 1 to the support surface 31, it is preferable that the fastening part body 51 be relatively long. For example, the length of the fastening part body 51 is 0.5 times or more the length of the support surface 31, preferably 0.8 times or more. There is no particular upper limit to the length of the fastening part body 51, but considering handling, it is 3 times or less the length of the support surface 31, preferably 2 times or less. The width 51W of the fastening part body 51 is not particularly limited, but if it is too small, the fastening part body 51 may shift from or fall off the support surface 31. From this viewpoint, the width of the fastening part body 51 is 0.7 times or more, preferably 0.85 times or more, and more preferably 1 time, the width 31W of the support surface 31. Also, if the width 51W of the fastening part body 51 is too large, it may hinder the curling of the film piece 1 along the second direction D2. From this viewpoint, the width 51W of the fastening part body 51 is 1 time or less of the width 31W of the support surface 31. Specifically, the width 51W of the fastening part body 51 is, for example, 1.5 mm to 25 mm, preferably 3 mm to 5 mm. In this embodiment, in which the film piece 1 is attached to the support surface 31 using magnetic force, the support surface 31 may be formed from a magnet and the fastening part body 51 may be formed from a magnetic material, or both the support surface 31 and the fastening part body 51 may be formed from magnets.

[0030] The measuring instrument 4 includes, for example, a laser distance meter 42 having an emission unit 41, a rail unit 43 that supports the laser distance meter 42 so as to be movable in the horizontal direction, and a lifting unit 44 that supports the rail unit 43 so as to be movable in the vertical direction V. The laser distance meter 42 is a device that emits laser light onto an object (film piece 1) and calculates the distance from the time it takes for the reflected light to return. A conventionally known laser distance meter 42 can be used. The laser distance meter 42 emits laser light from the emission unit 41 towards the film piece 1 in a horizontal direction (a direction perpendicular to the vertical direction V). By emitting laser light from the emission unit 41 to a predetermined part of the film piece 1, the distance to the film piece 1 can be measured.

[0031] The rail section 43 has a groove 431 that extends horizontally. In relation to the film piece 1 attached to the support surface section 31, the groove 431 extends along the second direction D2 of the film piece 1. The laser distance meter 42 is movable along the groove 431 of the rail section 43. The lifting section 44 moves the rail section 43 up and down along the vertical direction V. Therefore, the laser distance meter 42 is also movable in the vertical direction V. Furthermore, the distance between the laser rangefinder 42's emission unit 41 and the virtual plane including the support surface 31 remains constant before and after movement.

[0032] <Method for evaluating the curl of film pieces and method for manufacturing film products> The curl evaluation method can be applied to various film pieces 1. The method of the present invention can evaluate curl occurring in film pieces 1 of various shapes and / or layer configurations as described above. In one embodiment, a film piece 1 is cut from a large roll of film, and the degree of curl of the film piece 1 is evaluated. Alternatively, a film piece 1 is cut from a long strip of film, and the degree of curl of the film piece 1 is evaluated. The cut film piece 1 may be used exclusively for curl evaluation, or after the curl evaluation, it may be subjected to appropriate processing and supplied to the market as a product. Cutting a film piece 1 from a roll of film includes obtaining a film piece 1 by cutting a part of the roll of film using a cutting means such as a cutter, and obtaining a film piece 1 by punching out a part of the roll of film using a punching blade or the like.

[0033] This section specifically describes a method for evaluating the degree of curl of a film piece 1 cut from a long, strip-shaped roll of film. In one embodiment, a method for manufacturing film products from a film roll is provided. The method for manufacturing film products includes a roll manufacturing step of producing a long strip of film roll, an evaluation step of cutting a film piece 1 from the film roll and evaluating the degree of curl of the film piece 1, and a product manufacturing step of producing a plurality of film products from the film roll. Since the degree of curl of the film roll can be confirmed in the evaluation step, it is preferable to correct the curl of the film roll in the product manufacturing step. The method for manufacturing a film product from a film roll includes a roll manufacturing step, an evaluation step, and a product manufacturing step, but it may also include steps other than these. These processes may be performed consecutively, or one or more processes selected from the above may be performed consecutively, with the remaining processes being performed separately at intervals. Alternatively, all of the above processes may be performed by a single implementer, or one or more processes selected from the above may be performed by a single implementer, with the remaining processes being performed by other implementers.

[0034] <Raw material production process> Figure 6 is a schematic diagram of the system that carries out each of the processes described above: the raw material production process, the evaluation process, and the product manufacturing process. Referring to Figure 6, the system comprises, in order from upstream, a raw material manufacturing line B, a curl measuring device A, and a product manufacturing line C. The illustrated example shows a raw material manufacturing line B that produces a five-layer film raw material as shown in Figure 2(e). This raw material production line B includes, for example, a first unwinding section 71 that unwinds a long strip of release liner 91 wound in a roll, a coating section 72 that applies adhesive to the release liner 91 to form an adhesive layer, a drying section 73 that dries the adhesive layer, a second unwinding section 74 that unwinds a long strip of polarizing film 92 wound in a roll, a first bonding section 75 that bonds the polarizing film 92 to the adhesive layer formed on the release liner 91, a third unwinding section 76 that unwinds a long strip of protective film 93 with a release liner that is wound in a roll, a peeling section 77 that peels and recovers the release liner 94 from the protective film 93 and exposes the adhesive layer laminated on the protective film 93, a second bonding section 78 that bonds the adhesive layer of the protective film 93 to the polarizing film 92, and a winding section 79 that winds up the obtained film raw material 9. A release liner 91 is unwound from the first unwinding section 71 of the raw material manufacturing line B, an adhesive layer is formed on it, and a polarizing film 92 and an adhesive protective film 93 are laminated in order to produce a five-layer film raw material 9 consisting of a release liner 91, an adhesive layer, a polarizing film 92, an adhesive layer, and a protective film 93. The obtained film raw material 9 is wound into a roll on the winding section 79. Furthermore, the film roll 9 produced is not limited to a five-layer structure, and can be changed to various layer configurations as illustrated in the film piece 1 above. Also, the film roll production line B is not limited to the illustrated example and may be modified as appropriate.

[0035] <Evaluation Process> (Preparing the film pieces) The roll of film material 9 is removed from the winding section 79. A portion of the film material 9 is cut off to form a film piece 1 in order to perform a curl evaluation. Specifically, as shown in Figures 6 and 7, a portion of the roll-shaped film roll 9 is cut to obtain a film piece 1. The cutting location can be arbitrarily set. The purpose of the curl evaluation in this embodiment is to confirm the degree of curl of the long strip-shaped film roll 9 by cutting a film piece 1 from the film roll 9 and evaluating the degree of curl of the film piece 1. For this reason, it is preferable to cut several locations on the film roll 9 and evaluate the curl of the film piece 1 caused by each of these locations. For example, as shown in Figures 6 and 7, the forward region in the MD direction of the roll-shaped film roll 9 is pulled out, and a portion of that region is cut to obtain a film piece 1. In the example in Figure 7, film pieces 1 are cut at three locations: one side of the film roll 9 in the TD direction, the opposite side, and the central region. If necessary, the degree of curl of the rear region of the film roll 9 in the MD direction (this rear region is the region near the winding core 98 in Figure 7) may also be checked. In this case, it is preferable to rewind the roll-shaped film roll 9 and obtain film pieces 1 at several locations in the rear region in the MD direction. For example, in the MD direction rear region, it is preferable to obtain film pieces 1 at three locations, similar to the front region: one side of the TD direction region, the opposite side, and the central region. The MD direction M and the TD direction T are perpendicular directions within the plane of the film roll 9, and in the case of a long strip of film roll 9, its longitudinal direction is the MD direction M.

[0036] The film piece 1 can be formed into any shape. When measuring the amount of curvature as part of the curl evaluation (evaluating the degree of curl by length), it is preferable to form the film piece 1 into a roughly square or rectangular shape, as this makes measurement easier. Curling of the film roll 9 can occur in various directions, but generally, curling is more likely to occur along the MD direction M and / or the TD direction T of the film roll 9. Alternatively, even if curling mainly occurs along directions other than the MD and TD directions T, if the degree of curling along the MD and TD directions T of the film roll 9 can be confirmed, an appropriate method for correcting the curl can be determined. For this reason, it is preferable to evaluate the degree of curling along the MD and TD directions T of the film roll 9. In order to evaluate the degree of curling in these directions, it is preferable to cut a film piece 1 from the film roll 9 so that the diagonal of the approximately square or approximately rectangular shape is approximately in the MD direction M (or TD direction T). In the illustrated example, a roughly square-shaped film piece 1 is cut from the film roll 9 such that the MD direction M (and TD direction T) of the film roll 9 aligns with the diagonal of the film piece 1.

[0037] (Installation of film pieces) The film piece 1 is supported by the support member 3 of the measuring device A. For example, when evaluating the degree of curl along the second direction D2 of the film piece 1, the first direction D1 of the film piece 1 is made approximately parallel to the vertical direction V, and the film piece 1 is supported by the support member 3. More specifically, as shown in Figure 8, the film piece 1 is positioned so that its first direction D1 is approximately parallel to the vertical direction V and the central part of the film piece 1 in the second direction contacts the support surface 31 of the support member 3, while the back surface of the film piece 1 is temporarily fixed to the support surface 31 of the support member 3. As described above, the support surface 31 consists of a flat surface extending approximately parallel to the vertical direction V, so when the back surface of the film piece 1 is placed against the support surface 31, the first direction D1 of the film piece 1 naturally becomes approximately parallel to the vertical direction V. The phrase "the first direction D1 of the film piece 1 is approximately parallel to the vertical direction V" means parallel within the range in which the effects of the present invention are achieved, and includes not only strictly parallel but also cases where the first direction D1 is inclined within 10 degrees, preferably within 5 degrees, relative to the vertical direction V. Next, the fastening member 5 is applied to the center of the film piece 1 in the second direction from the surface side and magnetically attached to the support surface 31, thereby causing the film piece 1 to adhere to the support surface 31 by magnetic force.

[0038] Figure 9 is a front view (viewed from the direction of arrow IX in Figure 8) showing the film piece 1 supported by the support member 3, and Figure 10 is a top view of that state. The central portion of the film piece 1 in the second direction is sandwiched between the fastening member 5 and the support surface portion 31, and is attached to the support surface portion 31 in the region where the fastening member 5 is magnetically attached. In the illustrated example, the length of the fastening member 5 is shorter than the length of the support surface portion 31, and a portion of the central portion of the film piece 1 in the second direction is attached to the support surface portion 31. Hereinafter, the region of the central portion of the film piece 1 in the second direction that is attached to the support surface portion 31 will be referred to as the "attached region". However, the attached region includes at least one end 1a and the opposite end 1b in the first direction of the central portion of the film piece 1 in the second direction.

[0039] The film piece 1 is supported by the support member 3 with the area other than the area attached to the support surface 31 (hereinafter referred to as the "non-attached area") free. In other words, the film piece 1 is suspended in mid-air, with its surface (or back surface) approximately perpendicular to the horizontal plane, except for the area attached to the support surface 31. Therefore, the non-attached area can move freely in a direction perpendicular to the surface of the film piece 1 without restriction. In reality, the surface (or back surface) of the film piece 1 is curved due to its own curl, so the statement "the surface (or back surface) of the film piece 1 is approximately perpendicular to the horizontal plane" means that it is approximately perpendicular to the horizontal plane assuming that the film piece 1 is not curled.

[0040] (Carl's evaluation) The portion of the film piece 1 that is attached to the support surface 31 is restricted, but the unrestricted, non-attached portion curls according to the properties of the film piece 1. The curl of the film piece 1 can result in either a concave curvature of the surface, as shown in Figure 10, or a convex curvature of the surface, as shown in Figure 11. In either case, by supporting the film piece 1 with its first direction D1 approximately parallel to the vertical direction V, it is possible to prevent gravity from causing the curl in the second direction D2 of the film piece 1 to be smaller or larger than it actually is. Therefore, the degree of the actual curl of the film piece 1 (the curl according to the properties of the film piece 1) can be accurately evaluated. Furthermore, this method can be implemented using a simple measuring device A. Therefore, the degree of curl can be evaluated easily and inexpensively.

[0041] The method for evaluating curl is not particularly limited, but typically it involves measuring the amount (length) of curvature. In one embodiment, the evaluation of curl includes imagining a plane P that includes the second central portion of the film piece 1, and measuring the perpendicular length L from one edge 1c of the film piece 1 in the second direction to the imaginary plane P. As shown in Figures 10 and 11, conceptually, a plane P is imagined that includes the central part of the film piece 1 in the second direction. The amount of warping can be determined by measuring the perpendicular length L from one edge 1c of the film piece 1 in the second direction to this virtual plane P.

[0042] Specifically, the laser distance meter 42 is moved along the second direction D2 and / or first direction D1 of the film piece 1, and the laser emission part 41 of the laser distance meter 42 is positioned on the extension of one edge 1c in the second direction of the film piece 1. As shown in the illustrated example, when the film piece 1 is supported by the support member 3 such that the diagonals of the film piece 1, which is oriented in a substantially positive direction, are in the first direction D1 and the second direction D2, one corner of the film piece 1 becomes the one edge 1c in the second direction. It is difficult to accurately position the laser beam to irradiate the edge of the film piece 1. Furthermore, even if the laser beam is positioned to hit the edge, there is a risk that the reflected light will not return to the laser distance meter 42. For this reason, in actual measurements, the laser distance meter 42 is positioned so that the laser beam irradiates a location slightly inward from the one edge 1c in the second direction (the surface near the one edge). The laser distance meter 42 measures the distance between the laser beam emission part 41 and one edge 1c in the second direction. The distance between the laser beam emission part 41 of the laser distance meter 42 and the virtual plane including the support surface part 31 is constant and is a known value from the design of the measuring device A. The thickness of the film piece 1 is also a known value. From these known values ​​and the distance between the laser beam emission part 41 and one edge 1c in the second direction, the perpendicular length L can be calculated.

[0043] If necessary, the laser rangefinder 42 can be moved to the opposite edge 1d of the film piece 1 in the second direction, and the amount of curvature (perpendicular length L) of the opposite edge 1d in the second direction can be determined in the same manner. The degree of curl along the second direction D2 of the film piece 1 can be confirmed from the average of the amount of curvature of one edge 1c in the second direction and the amount of curvature of the opposite edge 1d. For example, if the first direction D1 of the film piece 1 is the TD direction T of the film roll 9 and the second direction D2 of the film piece 1 is the MD direction M of the film roll 9, then the degree of curl in the MD direction M of the film roll 9 can be evaluated through the film piece 1.

[0044] After evaluating the degree of curl along the second direction D2, the curl along the first direction D1 may be evaluated as needed. To do this, the retaining member 5 is removed, the film piece 1 is detached from the support surface 31, the film piece 1 is rotated 90 degrees so that the second direction D2 is vertical direction V, and the central part in the first direction is supported by the support surface 31. Afterwards, the amount of curvature of one edge and / or the opposite edge of the film piece 1 in the first direction is measured in the same manner. In this way, the degree of curl of the film piece 1 along the first direction D1 can be confirmed.

[0045] <Product Manufacturing Process> After confirming the degree of curling of the film roll 9 through the evaluation process described above, multiple film products are manufactured from the film roll 9. Referring to Figure 6, the product manufacturing line C includes a fourth unwinding section 81 that unwinds a long, roll-shaped film raw material 9, a cutting section 82 that cuts a portion of the film raw material 9 into sheets of a predetermined shape, a collection section 83 that collects the waste 99, a conveyor 84 that transports the film products 100 cut by the cutting section 82, and a storage section 85 that stores the film products 100. Multiple film products 100 are obtained by unwinding the film roll 9 from the fourth unwinding section 81 of the product manufacturing line C and cutting it into predetermined shapes at the cutting section 82. The film products 100 are further subjected to any appropriate processing and then supplied to the market. If necessary, the curl of the film roll 9 is corrected during the process between the fourth unwinding section 81 and the cutting section 82. Methods for correcting the curl of long strip-shaped film are conventionally known, and the curl can be corrected using an appropriate method as appropriate. For example, if the film roll 9 is curled in the MD direction M, the curl in that direction can be corrected by adjusting the tension applied to the film roll 9 during the transport process of the film roll 9. Note that the raw material manufacturing line B is not limited to the illustrated example and may be modified as appropriate.

[0046] The following describes a second embodiment of the present invention, in which the description will mainly focus on configurations and effects that differ from those of the above-described embodiment. For similar configurations, the same terms or reference numerals will be used, and the description of those configurations may be omitted (the same applies to the third embodiment and subsequent embodiments).

[0047] [Second Embodiment] In the first embodiment described above, the fastening member 5 is in the shape of an elongated strip, and the fastening member 5 attaches the strip-shaped region including one end 1a and the opposite end 1b of the film piece 1 in the first direction to the support surface 31. However, multiple relatively small fastening members 5 may be used to attach the film piece 1 to the support surface 31. For example, as shown in Figures 12 and 13, a number of relatively small fastening members 5 may be prepared, and the film piece 1 may be attached to the support surface 31 by magnetically attaching the fastening members 5 to the support surface 31, respectively, to one end 1a and the opposite end 1b in the first direction of the central part of the film piece 1 in the second direction. Furthermore, in the first embodiment described above, a portion of the central part of the film piece 1 in the second direction is attached to the support surface 31. However, as shown in Figure 14, for example, the entire central part of the film piece 1 in the second direction may be attached to the support surface 31.

[0048] For example, as shown in Figure 15, the fastening member 5 may be magnetically attached only to the central part in the first direction of the central part of the film piece 1 in the second direction. However, if only the central part in the first direction is attached to the support surface 31 in this way, one end 1a of the film piece 1 in the first direction may bend (one end 1a may bend toward the front of the page in Figure 15). Such bending may affect the curl of the film piece 1 along the second direction D2, and it may be difficult to accurately evaluate the actual degree of curl. Considering these points, it is preferable to attach at least one end 1a and the opposite end 1b in the first direction to the support surface 31, as in the above embodiment, to support the film piece 1 on the support surface 31.

[0049] [Third Embodiment] In each of the embodiments described above, magnetic force is used as a means to attach the film piece 1 to the support surface 31, but for example, the film piece 1 may be attached to the support surface 31 by magnetism. For example, as shown in Figure 16, a plurality of suction holes 35 are formed in the support surface 31, and a cavity (not shown) communicating with the suction holes 35 is formed inside the support body 32. The back surface of the second central part of the film piece 1 is temporarily fixed to the support surface 31, and the cavity is vacuum-suctioned using a suction device (not shown), causing the film piece 1 to be attracted to the suction holes 35 and adsorbed to the support surface 31. In this way, the film piece 1 may be supported on the support surface 31.

[0050] Alternatively, as a means of attaching the film piece 1 to the support surface 31, an adhesive may be used to adsorb the film piece 1 to the support surface 31. In other words, by providing an adhesive layer on the back surface of the film piece 1 or on the support surface portion 31, when the back surface of the second central part of the film piece 1 is brought into contact with the support surface portion 31, the film piece 1 will adhere to the support surface portion 31 via the adhesive layer (not shown). The film piece 1 may be supported by the support member 3 in this manner. When attaching the film piece 1 to the support surface portion 31 using suction or adhesive as described above, a fastening member is not required, but a fastening member may be used in combination as needed.

[0051] For example, if a film piece 1 (film roll 9) has an adhesive layer and a release liner laminated on the adhesive layer, the release liner may be peeled off to expose the adhesive layer. Since the adhesive layer is exposed on the back surface of such a film piece 1, the film piece 1 can be attached to the support surface 31 using this adhesive layer. In conventional methods, it is difficult to evaluate the curl of a film piece with an exposed adhesive layer because the adhesive layer adheres to the horizontal surface. According to the present invention, the curl of a film piece 1 with an exposed adhesive layer can also be accurately evaluated. Generally, the release liner is peeled off and discarded when the film product is used, so it is desirable to evaluate the curl of a film piece 1 (film roll 9) without a release liner. According to the present invention, the degree of curl along the second direction D2 (or first direction D1) of a film piece 1 with the adhesive layer exposed after peeling off the release liner can be accurately evaluated.

[0052] Furthermore, although the above embodiments use a support member 3 having a support surface portion 31, the support member 3 is not limited to this. As described above, in the present invention, when evaluating the degree of curl of the film piece 1 along the second direction D2, the first direction D1 of the film piece 1 should be made substantially parallel to the vertical direction V and the non-adhering region should be left free. When evaluating the degree of curl of the film piece 1 along the first direction D1, the second direction D2 of the film piece 1 should be made substantially parallel to the vertical direction V and the non-adhering region should be left free. The configuration of the support member 3 can be changed in various ways, provided that the film piece 1 is supported in this state. For example, as shown in Figure 17, it may be a support member 3 that suspends and supports the film piece 1. This support member 3 has an upper holding portion 36 that holds one end 1a in the first direction of the film piece 1, and a lower holding portion 37 that holds the opposite end in the first direction D1. The upper holding portion 36 has an upper clip portion 361 that grips one end 1a of the film piece 1, a frame portion 362, and a connecting portion 363 made of a spring or the like interposed between the upper clip portion 361 and the frame portion 362. The lower holding portion 37 has a lower clip portion 371 that grips the opposite end 1b of the film piece 1, and a support leg 372 that attaches the lower clip portion 371 to the mounting base 6. Even with such a support member 3, the film piece 1 can be supported with the first direction D1 of the film piece 1 substantially parallel to the vertical direction V.

[0053] [Fourth Embodiment] In the first embodiment described above, the amount of curvature is measured using a laser distance meter 42. However, as shown in Figure 18, for example, the amount of curvature may be measured using a caliper 45 (digital or analog caliper). In this case, it is preferable to provide a flat plate 38 that is positioned parallel to the support surface 31 for applying one jaw 451 of the caliper 45. By applying one jaw 451 of the caliper to the flat plate 38 and aligning the other jaw 452 of the caliper 45 with one edge 1c in the second direction of the film piece 1, the distance between the flat plate 38 and the one edge 1c in the second direction can be measured. Also, as shown by the dashed line in the same figure, the distance between the flat plate 38 and the surface of the central part of the film piece 1 in the second direction can be measured. By subtracting the above two distances, the amount of curl along the second direction D2 of the film piece 1 can be calculated. Although not specifically illustrated, the amount of warping can also be measured using a ruler. Furthermore, in each of the above embodiments, the amount of curl is defined as the perpendicular length L from one edge 1c of the film piece 1 in the second direction to the virtual plane P. However, the amount of curl can also be defined as a length other than the perpendicular length (for example, the length from any fixed point to one edge 1c of the film piece 1 in the second direction). It should be noted that the perpendicular length L is merely one indicator for evaluating the degree of curl.

[0054] Furthermore, the method for evaluating the degree of curl is not limited to measuring the amount of warping; other indicators can also be used to evaluate curl. For example, the radius of curvature of film piece 1 can be determined, and the curl can be evaluated accordingly. The radius of curvature of film piece 1 can be determined, for example, by imaging film piece 1 from above, as shown in the top view in Figure 10 or Figure 11. Based on the captured image, an approximate curve following the shape of the surface of film piece 1 is created using image processing software, and the radius of curvature of that approximate curve is calculated.

[0055] [Fifth Embodiment] In each of the embodiments described above, the film piece 1 is supported by the support member 3 so that the diagonal of the film piece 1, which is formed in a substantially square shape, is parallel to the first direction D1. However, for example, as shown in Figure 19(a), the film piece 1 may be supported by the support member 3 so that one side of the film piece 1, which is substantially square (or substantially rectangular), is parallel to the first direction D1. Also, as shown in Figure 19(b), the film piece 1 may be supported by the support member 3 so that the direction of the film piece 1 is the first direction D1, except for the diagonal and one side of the film piece 1, which is substantially rectangular (or substantially square). As mentioned above, the shape of the film piece 1 is arbitrary, and for example, as shown in Figure 19(c), the degree of curl may be evaluated using a film piece 1 that is substantially elliptical in shape. [Explanation of symbols]

[0056] 1 film piece 1a One end of the film piece in the first direction 1b The opposite end of the film piece in the first direction 1c One edge of the film piece in the second direction 1d The second opposite edge of the film piece D1 First direction of film piece D2 Film piece, second direction V Vertical direction 3. Support member 31 Support surface part

Claims

1. A step of supporting the film piece on the support member by aligning the first direction of the film piece substantially parallel to the vertical direction and attaching the central portion of the second direction, which is perpendicular to the first direction of the film piece, to the support member, thereby leaving the area other than the area attached to the support member free. The process includes a step of evaluating the degree of curl of the film piece along a second direction. Method for evaluating film curl.

2. The method for evaluating the curl of a film according to claim 1, wherein the evaluation of the curl includes imagining a virtual plane that includes the second central portion of the film piece and measuring the length of the perpendicular from one edge of the film piece in the second direction to the virtual plane.

3. The support member has a support surface portion that extends vertically and is in contact with the back surface of the film piece. The method for evaluating the curl of a film according to claim 1, wherein a portion or all of the central part of the film piece in the second direction is attached to the support surface.

4. The method for evaluating the curl of a film according to claim 3, wherein the support surface portion is in the shape of a strip extending from one end to the opposite end in the first direction of the film piece.

5. The method for evaluating the curl of a film according to claim 4, wherein the entire central portion of the film piece in the second direction is attached to the strip-shaped support surface.

6. The method for evaluating the curl of a film according to claim 4, wherein at least one end and the opposite end of the central portion of the film piece in the second direction are attached to the strip-shaped support surface.

7. The method for evaluating the curl of a film according to claim 3, wherein the width of the support surface is 0.03 to 0.35 times the maximum length of the film piece in the second direction.

8. The curl evaluation method according to claim 1, wherein the film piece is attached to the support member using magnetic force.

9. A process for producing long strip-shaped film raw materials, The process includes a product manufacturing step for producing multiple film products from the aforementioned film roll, A method for manufacturing a film product, comprising the step of cutting off a portion of the film roll to obtain a film piece, and evaluating the curl of the film piece by the method described in any one of claims 1 to 8, between the raw material production step and the product production step.

10. The method for manufacturing a film product according to claim 9, wherein the product manufacturing step includes correcting the curl of the film roll.

Images