Film manufacturing method

Abstract

To provide a film, a laminate, and a method for producing the film that can, for example, ensure elongation while suppressing breakage of a hard and brittle layer.SOLUTION: Provided is a film, which is a film in which a first layer, a second layer, a third layer are laminated in order from one side, and in which an uneven structure is formed on the surface of the first layer, the height of the uneven structure is higher than the total thickness of the first layer and the second layer, the recovery rate of the third layer when stretched by 20% exceeds 90%, and the Young's modulus of the second layer is 650 MPa or more and 3300 MPa or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention provides film This relates to a method for producing the above. [Background technology]

[0002] Generally, plastic films have properties such as being lightweight, chemically stable, easy to process, flexible and strong, and capable of mass production. For these reasons, plastic films are used in a wide variety of applications. Applications of plastic films are diverse, including, for example, packaging materials for food products and pharmaceuticals, intravenous drip packs, shopping bags, posters, tapes, optical films for LCD televisions, protective films, window films for application to windows, greenhouses, and building materials. For such applications, appropriate plastic materials are selected according to the application. Furthermore, multiple types of plastic films are often layered to form laminates.

[0003] For example, barrier films include films in which a film substrate such as OPP (Oriented Polypropylene) or PET (Polyethylene terephthalate) is dry-coated with a metal, oxide, or the like, or films in which polyvinylidene chloride, polyvinyl alcohol, metal alkoxide, or the like is wet-coated (see Patent Documents 1 and 2).

[0004] For example, an electromagnetic wave shielding film is made of a film in which metal is vapor-deposited on a substrate (see Patent Document 3), and a wiring board is made of a film in which metal wiring is printed on an elastomer substrate (see Patent Document 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 62-295931 [Patent Document 2] Japanese Patent Application Publication No. 5-9317 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-297714 [Patent Document 4] International Publication No. 2019 / 216425 Summary of the Invention [Problem to be solved by the invention]

[0006] However, none of these films can be said to have sufficient stretchability. Specifically, when the film is stretched, cracks appear in hard and brittle layers such as the coating layer, causing the film to lose its original functionality. In other words, there is a strong demand for a film that can maintain elongation while preventing damage to hard and brittle layers.

[0007] The present invention has been made in view of the above-mentioned problems, and provides a film that can ensure elongation while suppressing breakage of a hard and brittle layer, for example. of The object is to provide a manufacturing method. [Means for solving the problem]

[0008] In order to solve the above problems, a representative film of the present invention Manufacturing method One is a film with the first layer, second layer, and third layer laminated on one side in that order. And , The film is An uneven structure is formed on the surface on the side of the first layer, and the height of the uneven structure is greater than the total thickness of the first layer and the second layer, the recovery rate of the third layer at 20% elongation exceeds 90%, and the Young's modulus of the second layer is 650 MPa or more and 3300 MPa or less. In the method for producing a film, forming a concave-convex structure on the surface of a material obtained by laminating the flat second layer and the flat third layer; and forming the first layer by applying dry coating or wet coating to the second layer while the material is stretched so that the height of the concave-convex structure is reduced. A film characterized by Manufacturing method This is achieved by: [Effects of the Invention]

[0009] According to the present invention, for example, a film capable of ensuring elongation while suppressing breakage of a hard and brittle layer can be obtained. of A method of manufacture can be provided. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the film of this embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing an example of the film of this embodiment, where (a) shows the state before stretching and (b) shows the state after stretching. [Figure 3] FIG. 3 is a perspective view showing an example of the film of this embodiment. [Figure 4] FIG. 4 is a top view showing an example of the film of this embodiment, observed from the normal direction of the film. [Figure 5] FIG. 5 is a top view showing an example of the film of this embodiment, observed from the normal direction of the film. [Figure 6] FIG. 6 is a top view showing an example of the film of this embodiment, observed from the normal direction of the film. [Figure 7] FIG. 7 is a perspective view showing an example of the first layer of the film of this embodiment. [Figure 8] FIG. 8 is a top view showing an example of the first layer of the film of this embodiment, observed from the normal direction of the film. [Figure 9] FIG. 9 is a cross-sectional view showing an example of the film of this embodiment. [Figure 10] FIG. 10 is a diagram showing the cross-sectional contour of the concave-convex structure of the film of this embodiment. [Figure 11] FIG. 11 is a schematic diagram showing the regions of the film and the film of this embodiment. [Figure 12] FIG. 12 is a schematic diagram showing the regions of the film and the film of this embodiment. [Figure 13]FIG. 13 is a diagram showing a cross section of a film when measuring the interfacial peel strength. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that each figure is a schematic view, and the size and shape of each part are appropriately exaggerated for ease of understanding. Also, for ease of explanation, the same reference numerals are used to denote corresponding parts in each figure.

[0012] As shown in Figure 1, the film 1 of this embodiment is a film 1 having at least three laminated layers, with the first layer 2, second layer 3, and third layer 4 arranged in that order from one side. The first layer 2 has a surface (front side) 5, which is the interface with air, that has a concave-convex structure 7 formed on it. The third layer 4 has a surface (rear side) 6, which is the interface with air (the surface opposite to the surface on which the second layer 3 is laminated), that is substantially flat, and the height H of the concave-convex structure 7 is greater than the sum (T1 + T2) of the thickness T1 of the first layer 2 and the thickness T2 of the second layer 3. Furthermore, the recovery rate of the third layer 4 at 20% elongation exceeds 90%, and the second layer 3 has a Young's modulus of 650 MPa or more and 3300 MPa or less.

[0013] Here, "substantially flat" means that the size of the irregularities on the surface 6 is smaller than that of the irregularity structure 7, and specifically, the arithmetic mean roughness Ra (JIS B0601:1994) is 5 μm or less.

[0014] Furthermore, the height H of the concave-convex structure 7 refers to the difference in height between the peaks and valleys of the concave-convex structure 7 (the distance from the surface 5 closest to the surface 6 to the surface 5 farthest from the surface 6), and the thickness Tn (n = 1, 2, 3) of each layer refers to the thickness in the direction perpendicular to the surface or interface of each layer. The thickness Tn of each layer does not need to be uniform depending on the location of the concave-convex structure 7 and may be non-uniform. The thickness T3 of the third layer 4 refers to the thickness in the direction perpendicular to the surface or interface at the portion that is thinner due to the concave-convex structure 7. At any position, the total thickness (T1 + T2) of the thickness T1 of the first layer 2 and the thickness T2 of the second layer 3 must be less than the height H of the concave-convex structure 7.

[0015] In addition, the "restoration rate at 20% elongation" refers to the ratio C = (1.2AB) / 0.2A × 100% of the difference between the film length B after 10 seconds or more has elapsed since the film was stretched from an initial length A by 20%, held for 5 seconds or more, and then released from the elongation force, and the film length 1.2A at 20% elongation.

[0016] Furthermore, Young's modulus is a value that indicates material properties, and can be measured, for example, by preparing a flat film of the same material without any irregularities and subjecting it to a tensile test in accordance with JIS K7127:1999.

[0017] There are no particular restrictions on the first layer 2, but it is advisable to arrange a hard and brittle layer such as a vapor deposition layer or coating layer, as this will maximize the effect of preventing cracks from occurring during elongation.

[0018] Normally, when a hard, brittle layer is laminated on a stretchable film, cracks often appear in the hard, brittle layer when stretched, causing deterioration. Also, when an elastic film has an uneven surface and a hard, brittle layer is laminated on top of it, when stretched, the stretching does not occur due to a change in the shape of the unevenness, but rather only a portion stretches locally, causing cracks. This is because stress is concentrated in the thinner parts of the film.

[0019] However, in the film 1 of this embodiment, the presence of the relatively rigid second layer 3 as an intermediate layer makes it possible to prevent localized stretching. In other words, because the second layer 3 is in close contact with the first layer 2 as a reinforcing layer, localized stretching of only the first layer 2 is suppressed. As a result, as shown in Figures 2(a) and 2(b), the uneven structure 7 changes shape, causing stretching. Even if the film 1 stretches due to the change in shape of the uneven structure 7, the material of the first layer 2 itself does not stretch, so it is possible to suppress the occurrence of cracks. The above has been explained regarding stretching, but the same applies to shrinkage.

[0020] The total thickness (T1+T2) of the thickness T1 of the first layer 2 and the thickness T2 of the second layer 3 must be less than the height H of the concave-convex structure 7, and more preferably, the total thickness (T1+T2) of the thickness T1 of the first layer 2 and the thickness T2 of the second layer 3 is less than half the height H of the concave-convex structure 7, and even more preferably, is less than one-third. This is because if T1+T2≧H, the shape of the concave-convex structure 7 would not change.

[0021] The Young's modulus of the second layer 3 must be 650 MPa or more and 3300 MPa or less, and more preferably 1000 MPa or more and 2500 MPa or less. If the Young's modulus of the second layer 3 is less than 650 MPa, it becomes difficult to stop the localized elongation, and cracks are likely to occur in the first layer 2. On the other hand, if the Young's modulus of the second layer 3 exceeds 3300 MPa, it becomes difficult to change the shape of the concave-convex structure 7, and it becomes difficult to elongate.

[0022] The recovery rate of the third layer 4 at 20% elongation must exceed 90%, and is preferably 95% or higher. If the recovery rate of the third layer 4 is 90% or lower, the film 1 will not have sufficient repeated stretchability. More preferably, the recovery rate of the third layer 4 at 40% elongation is 90% or higher, and even more preferably 95% or higher.

[0023] The Young's modulus of the third layer 4 is preferably 1 / 10 or less, and more preferably 1 / 20 or less, of the Young's modulus of the second layer 3. This makes it possible to more effectively obtain the effects of this embodiment.

[0024] Furthermore, it is preferable that the thickness T2 of the second layer 3 is 3 μm or more and 50 μm or less. If the thickness T2 of the second layer 3 is less than 3 μm, the strength of the second layer 3 decreases, making it difficult to prevent localized elongation, and if it exceeds 50 μm, it becomes difficult to change the shape of the concave-convex structure 7.

[0025] The height H of the concave-convex structure 7 is preferably 150 μm or less. If the height H of the concave-convex structure 7 exceeds 150 μm, it becomes difficult to produce the film 1. As described above, the lower limit of the height H of the concave-convex structure 7 is determined by the total thickness (T1 + T2) of the thickness T1 of the first layer 2 and the thickness T2 of the second layer 3, and specifically, it is preferably 10 μm or more. More preferably, the height H of the concave-convex structure 7 is 20 μm or more, and even more preferably 30 μm or more. This increases the amount of elongation due to shape change of the second layer 3, thereby enhancing the effects of this embodiment.

[0026] It is preferable that the interfacial peel strength between the second layer 3 and the third layer 4 is 10 mN / mm or more. If it is less than 10 mN / mm, the second layer 3 and the third layer 4 may peel off during expansion and contraction.

[0027] Interfacial peel strength can be measured using a standard tensile testing machine. Figure 13 shows a cross section of film 1 (before the first layer is laminated) when measuring interfacial peel strength. After cutting out the second layer 3 and third layer 4 to a width of 15 mm and a length of 150 mm, the second layer 3 and third layer 4 are peeled apart by 50 mm. Each peeled end is held in the chuck 21 of the tensile testing machine, and a tensile test is performed by pulling the second layer 3 and third layer 4 apart in the direction of separation, with a chuck distance of 50 mm and a pulling speed of 200 mm / min. The interfacial peel strength indicates the maximum load obtained in this test.

[0028] As shown in Figures 3 and 4, the uneven structure 7 preferably has mountain-like ridges 7a or valley-like ridges 7b extending to the edge of the film 1. Figure 4 is a schematic diagram of Figure 3 as viewed from the film normal direction (the normal direction to the surface 6, hereinafter). Extending the ridges to the edge allows for easy stretching in directions perpendicular to the ridges. If the ridges are interrupted along the way, this is undesirable because the portion becomes less stretchable. As shown in Figure 5, the ridges may extend obliquely relative to the edge of the film. Here, "extension" does not necessarily have to be linear; it may be curved as shown in Figure 6 or at a different angle as shown in Figures 7 and 8. Note that Figure 7 is a perspective view of the film, but for simplicity, only the first layer 2 is shown. When the ridges are not perfectly linear, as shown in Figures 6, 7, and 8, they can be stretched in any direction. The ridges may intersect, but care must be taken to avoid restricting stretching if the intersection area is large.

[0029] The cross-sectional shape of the uneven structure 7 may be trapezoidal as shown in Figures 1 and 2, or triangular as shown in Figure 9, which shows the cross-section of the film in Figure 3. Other examples of the cross-sectional shape of the uneven structure 7 (surface 5) are shown in Figures 10(a) to 10(f), but any shape is acceptable and is not limited to these. However, trapezoids with flat shapes perpendicular to the film normal direction and shapes with triangular or arc-shaped shapes spaced apart are preferred because they can further increase the contact area when laminating another layer. On the other hand, when the ridge lines are not linear but change angle as shown in Figures 6, 7, and 8, shapes with repeatedly changing angles and no surface parallel to the back surface, as shown in Figures 9 and 10(a), are preferred because they are easily stretched with a weak force.

[0030] The film 1 of this embodiment may be formed by arranging one or more films 1 having the above characteristics on the same plane. That is, as shown in FIG. 11 , the film 1 may have a concave-convex structure 7 and multiple regions 1A having the above characteristics arranged at intervals. Here, when providing the film 1 with a concave-convex structure, the concave-convex structure is formed only in multiple regions 1A, as shown in FIG. 11 . This leaves flat portions where the second layer 3 and the third layer 4 are laminated between the regions 1A and between the regions 1A and the edges of the film. Then, cutting between the regions 1A and the flat portions in a direction perpendicular to the ridge lines, as shown by the dotted lines, results in a film with ridge lines extending to the widthwise ends. The flat portions at both ends of the film are pulled left and right in FIG. 11 to form the first layer 2 by performing deposition or the like while flattening the second layer 3. The desired film 1 is then obtained by cutting each region 1A.

[0031] Since the film 1 has anisotropic physical properties, in order to improve handling, it may be possible to make the film as a whole isotropic by, for example, rotating adjacent regions by 90 degrees to form a concave-convex structure 7 (FIG. 12). Here, the regions 1A may have gaps as shown in FIG. 11, or may not have gaps as shown in FIG. 12. In either case, by cutting each region 1A before use, each region 1A can be treated as film 1. It is preferable to perform deposition of the first layer 2, etc., on each region 1A separately.

[0032] Materials for the first layer 2 constituting the film 1 include inorganic compounds such as metals and ceramics, resins that can be cured by heat or UV light, and thermoplastic resins. Examples of inorganic compounds include metals such as Al, Cu, Zn, Fe, and Mn, and ceramics such as oxides and nitrides such as AlOx and SiOx. Examples of curable resins include acrylic resins, epoxy resins, and urethane resins. Examples of thermoplastic resins include polymethyl methacrylate, polyvinyl alcohol, and cyclic polyolefins. However, these materials are not particularly limited, and these materials may be used alone or in combination. The properties can be adjusted appropriately to meet desired characteristics, such as gas barrier properties, drug barrier properties, non-adsorption properties, electrical conductivity, and thermal conductivity.

[0033] Materials for the second layer 3 constituting the film 1 include thermoplastic resins and resins that can be cured by heat or UV light. Examples of curable resins include acrylic resins, epoxy resins, and urethane resins. Examples of thermoplastic resins include polyethylene, polypropylene, polystyrene, polymethyl methacrylate, ethylene vinyl acetate, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, polyvinylidene chloride, polyacrylonitrile, polylactic acid, cyclic polyolefins, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, and derivatives thereof. However, these materials are not particularly limited, and these materials may be used alone or in combination.

[0034] Materials for the third layer 4 constituting the film 1 include thermoplastic resins and resins that can be cured by heat or UV light. Examples of curable resins include acrylic resins, epoxy resins, and urethane resins, while examples of thermoplastic resins include thermoplastic elastomers such as polyethylene, polyolefin elastomers, polystyrene elastomers, polyurethane elastomers, and polyester elastomers. However, these materials are not particularly limited, and these materials may be used alone or in combination.

[0035] The film 1 of this embodiment can be produced by, for example, combining heat pressing or extrusion molding with dry coating or wet coating.

[0036] The second layer 3 and the third layer 4 can be produced by, for example, heat pressing or extrusion molding. In the hot pressing method, a flat film (material) having a flat second layer 3 and a flat third layer 4 laminated thereon can be passed between heated rolls having an uneven surface or through a heated flat press machine to impart an uneven structure 7. In this case, by adjusting the pressing depth and pressing pressure, a desired uneven structure can be imparted to the surface 5 of the film 1 and to the layer interface between the second layer 3 and the third layer 4.

[0037] In addition, in the extrusion molding method, a film having a multilayer structure of two or more layers can be obtained by co-extruding multiple different resins using multiple extruders using a feedblock method or a multi-manifold method. Specifically, in the cooling process for forming the film, a flat film having a flat second layer 3 and a flat third layer 4 stacked on top of each other is cooled while applying nip pressure to the surface on which the second layer 3 is placed, using a cooling roll with a surface having an unevenness corresponding to the uneven structure 7. At this time, if the height difference H between the peaks and valleys of the uneven structure 7 is large compared to the thickness T2 of the second layer 3, an uneven shape can also be imparted to the layer interface between the second layer 3 and the third layer 4.

[0038] The first layer 2 can be fabricated by, for example, dry coating or wet coating. The film (material) consisting of the second layer 3 and the third layer 4, to which the concave-convex structure 7 has been imparted using the above method, is stretched in a direction intersecting the ridges, reducing the height of the concave-convex structure 7 as shown in Figure 2(b). The first layer 2 can then be laminated and formed by dry coating, such as vapor deposition or sputtering, or wet coating, such as die coating or microgravure coating, in a flattened state. This allows particles scattered linearly from the target, such as in sputtering, to adhere uniformly to the surface of the second layer 3, enabling a coating with a relatively uniform thickness even with concave-convex structures. After laminating the first layer 2, the tension can be released, allowing the third layer 4 to restore the initial concave-convex structure 7, thereby providing the desired functionality for the film 1.

[0039] Additionally, the first layer 2 may also be formed by heat pressing or extrusion molding, and the manufacturing method is not particularly limited.

[0040] Furthermore, the film 1 according to this embodiment can also be made into a laminate by laminating a functional layer such as a print layer or an adhesive layer on the front surface 5 or the back surface 6 in a post-process.

[0041] Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments. In addition, the above-described embodiments may be used in combination as desired. [Example]

[0042] Examples prepared by the present inventors will be described in detail below in comparison with comparative examples, but the present invention is not limited to the following examples.

[0043] Example 1 The third layer 4 was made of BASF Japan's thermoplastic polyurethane elastomer (TPU) "Elastollan ET385-10" (with a recovery rate of 100% at 20% elongation), and the second layer 3 was made of Bell Polyester Products' polyethylene terephthalate (PET) resin "Bellpet EFG70" (Young's modulus of 2300 MPa). The two layers were laminated by co-extrusion molding, and the second layer 3 side was nipped with an uneven roll to produce a two-layer film with an uneven structure 7 on one side. Then, while stretching this film, an aluminum vapor deposition film was formed on the second layer 3 using a vacuum deposition machine, and the tension was released, yielding a three-layer film 1. The thickness T1 of the first layer 2 was 100 nm (0.1 μm), the thickness T2 of the second layer 3 was 14 μm, and the thickness T3 of the third layer 4 was 25 μm. The uneven structure 7 had a trapezoidal cross-sectional shape as shown in Figure 1 and a shape with ridge lines extending linearly in one direction as shown in Figure 3, and the height H of the uneven structure 7 was 300 μm.

[0044] (Examples 2, 3, 4, 5, Comparative Example 1) In Examples 2, 3, 4, and 5 and Comparative Example 1, the height H of the concave-convex structure 7 was set to 150 μm, 60 μm, 30 μm, 15 μm, and 10 μm, respectively, and the rest was the same as in Example 1.

[0045] (Example 6, Comparative Example 2, Examples 7, 8, 9, and 10) In Example 6, Comparative Example 2, Examples 7, 8, 9, and 10, the height H of the uneven structure 7 and the thickness T2 of the second layer 3 were set to 15 μm and 10 μm, 10 μm and 10 μm, 15 μm and 3 μm, 10 μm and 3 μm, 15 μm and 2 μm, and 10 μm and 2 μm, respectively, and the rest were the same as Example 1.

[0046] (Comparative Example 3) Comparative Example 3 was the same as Example 3, except that the material of the second layer 3 was a low-density polyethylene (PE) resin "Novatec LD LC600A" (Young's modulus: 150 MPa) manufactured by Japan Polyethylene Corporation.

[0047] (Examples 11, 12, 13, and 14) In Examples 11, 12, 13, and 14, the material of the second layer 3 was a polypropylene (PP) resin "Prime Polypro F-300SP" (Young's modulus 650 MPa) manufactured by Prime Polymer Co., Ltd., an ethylene-vinyl alcohol copolymer (EVOH) resin "Soarnol D4412" (Young's modulus 1500 MPa) manufactured by Mitsubishi Chemical Corporation, an ethylene-vinyl alcohol copolymer (EVOH) resin "Soarnol D2908" (Young's modulus 2600 MPa) manufactured by Mitsubishi Chemical Corporation, and a polymethyl methacrylate (PMMA) resin "Acrypet VH000" (Young's modulus 3300 MPa) manufactured by Mitsubishi Chemical Corporation, and the rest was the same as in Example 3.

[0048] Example 15 In Example 15, the materials for the third layer 4 and the second layer 3 were the polyethylene (EVOH) resin "Evolue SP1540" (with a recovery rate of 95% at 20% elongation) and the (PE) resin "Soarnol D2908" (Young's modulus of 2600 MPa), manufactured by Prime Polymer Co., Ltd., respectively, and the rest were the same as in Example 3.

[0049] Comparative Example 4 In Comparative Example 4, the materials for the third layer 4 and the second layer 3 were the polyethylene (EVOH) resin "Evolue SP3530" (with a recovery rate of 90% at 20% elongation) and the (PE) resin "Soarnol D2908" (Young's modulus of 2600 MPa), manufactured by Prime Polymer Co., Ltd., respectively, and the rest were the same as in Example 3.

[0050] (Comparative Example 5) In Comparative Example 5, the materials for the third layer 4 and the second layer 3 were the (PET) resin "Evolue SP3530" (with a recovery rate of 90% at 20% elongation) and the (PE) resin "Bellpet EFG70" (Young's modulus of 2600 MPa), respectively, and the rest was the same as in Example 3.

[0051] (Examples 16, 17, and 18) Examples 16, 17, and 18 were similar to Example 2 except that the thickness T2 of the second layer 3 and the thickness T3 of the third layer 4 were 30 μm and 50 μm, 50 μm and 50 μm, and 70 μm and 50 μm, respectively.

[0052] (Examples 19 and 20) In Examples 19 and 20, the shape of the uneven structure 7 was the same as in Example 3, with mountain-like ridges 7a or valley-like ridges 7b extending in two directions at different angles in a zigzag pattern as shown in Figure 7, and with mountain-like ridges 7a existing in a dot pattern and not extending to the end of the film.

[0053] (Comparative Example 6) In Comparative Example 6, the shape of the concave-convex structure 7 was a flat shape, i.e., there was no concave-convex structure, and the rest was the same as in Example 3. However, in the case of Comparative Example 6, which has a flat shape, i.e., there is no concave-convex structure, the height H of the concave-convex structure 7 is treated as 0.

[0054] (Examples 20 and 21) In Examples 20 and 21, the materials of the first layer 2 were SiOx and AlOx, respectively, and the rest were the same as in Example 3.

[0055] In the tables described later, with regard to the interfacial peel strength, "ND" indicates that the second layer 3 and the third layer 4 did not peel off in the peel test.

[0056] (Evaluation of film production) To confirm whether each example and comparative example was successfully produced, the shape was observed using a laser microscope (VHX-1000) manufactured by Keyence Corporation. Those that had the intended shape were marked with "○", those that did not have the intended shape were marked with "△", and those that could not be produced were marked with "×".

[0057] (evaluation of stretch, cracks in the vapor deposition layer, and repeated stretching) The performance of each example and comparative example was evaluated in terms of stretchability, cracks in the vapor-deposited layer, and repeated stretchability. The stretchability was evaluated as "○" if the fabric felt sufficiently stretchy to the touch, "◎" if it stretched with particularly little force, and "×" if it was judged to be insufficient. The evaluation was carried out by five test subjects, and the most common answer was adopted as the final evaluation result. The evaluation of cracks and fissures in the vapor-deposited layer was carried out by evaluating the water vapor transmission rate and observing the shape of the film after 10% elongation and subsequent release of stress. The water vapor transmission rate was evaluated in accordance with JIS Z0208. The storage environment was an Espec TBE-3HW2P3A build-in chamber at a temperature of 40°C and humidity of 90%. The moisture permeability cup used was an Imoto Manufacturing Moisture Permeability Cup 15BF, the moisture absorbent was Kanto Chemical's calcium chloride for moisture measurement, and the sealing grease used was Toray Dow Corning's high vacuum grease FE-50. The moisture permeability cup containing the sample was stored in the storage environment for 24 hours, and the weight change before and after storage was measured. The water vapor transmission rate was calculated using the specified calculation method. The measured values ​​of the samples in the Examples and Comparative Examples before and after 10% elongation were compared, and a change in water vapor transmission rate of 5 g / m was calculated. 2 For the levels where the change in water vapor transmission rate was 5g / m or more, a morphological observation evaluation was carried out. For the morphological observation evaluation, a scanning electron microscope (SEM) SU8020 from Hitachi High-Tech Corporation was used. In the morphological observation, if cracks were confirmed, the mark was "X", if no cracks were clearly confirmed despite the morphological observation, the mark was "△", and if the change in water vapor transmission rate was 5g / m or more, the mark was "△". 2 Those that were judged to be free of cracks and did not require morphological observation and were less than 1 day old were marked with an "O". The repeated stretchability was evaluated by stretching and releasing the stretch by 10% 10 times to check whether any problems occurred as a film. Those that had no problems were marked "○", those that had problems were marked "×", and those that had particular problems were marked "XX".

[0058] (comprehensive evaluation) In the above evaluations of film production, stretchability, cracks in the vapor-deposited layer, and repeated stretchability, if there was even one × or XX, it was marked as "X", if there was no × or XX, it was marked as "O", and if the evaluation of stretchability in particular was ◎ and the evaluations of film production and cracks in the vapor-deposited layer were ○, it was marked as "◎".

[0059] The conditions and evaluation results for each example are shown in Table 1. The conditions and evaluation results for each comparative example are shown in Table 2.

[0060] [Table 1]

[0061] [Table 2]

[0062] (Evaluation results) Comparing the overall evaluations of the Examples and Comparative Examples in Tables 1 and 2 reveals that all of the following were evaluated as "Good" or better: the height H of the concave-convex structure 7 was greater than the combined thickness of the first layer 2 and the second layer 3; the recovery rate of the third layer 4 at 20% elongation was greater than 90%; and the Young's modulus of the second layer 3 was 650 MPa or more and 3300 MPa or less; and all of the following were evaluated as "Poor": "Good" or better; and all of the following were evaluated as "Poor." This cannot be directly determined by the materials or thicknesses of the first layer 2, second layer 3, and third layer 4, but is achieved by satisfying the above characteristics.

[0063] Among the examples with an overall rating of "○" or higher, many examples received an elongation rating of "◎" and an overall rating of "◎", particularly when the height H of the uneven structure 7 was greater than twice the combined thickness of the first layer 2 and the second layer 3. However, in Example 1, in which the height H of the uneven structure 7 was 300 μm, unevenness in the height H of the uneven structure 7 was observed depending on the location, so film production was rated "△", but because it can be used depending on the application, the overall rating was rated "○".

[0064] In Examples 9 and 10, in which the thickness T2 of the second layer 3 was 2 μm, no clear cracks were observed in the morphological observation evaluation, but changes before and after elongation were confirmed in the water vapor permeability evaluation, suggesting that damage may have occurred locally due to material elongation rather than a change in the shape of the concave-convex structure 7. Therefore, the evaluation of cracks in the vapor deposition layer in Examples 9 and 10 was rated "△", but since it is usable depending on the application, the overall evaluation was rated "○". Furthermore, Example 20, in which the concave-convex structure 7 has a dot-like shape, was confirmed to be similar to Examples 9 and 10, but in this case, the sense of elongation was also rated "○".

[0065] In Comparative Examples 1 and 2, the height H of the uneven structure 7 was equal to or less than the total thickness of the first layer 2 and the second layer 3, resulting in no sense of stretching at all and resulting in an evaluation of "×". Even when the film was forcibly stretched and the deposition layer was evaluated for cracks and fractures, the evaluation of the deposition layer for cracks and fractures was also "×".

[0066] In Comparative Example 3, since the Young's modulus of the second layer 3 was low, the sense of stretch itself was good and the evaluation was "◎". However, the material itself stretched rather than the shape of the uneven structure 7 changed, resulting in many cracks and fissures in the vapor deposition layer and the evaluation was "×".

[0067] In Comparative Example 4, the recovery rate of the third layer 4 at 20% elongation was 90%, so that curling occurred when stretched repeatedly, and the repeated stretchability was evaluated as "X".

[0068] Comparative Example 5 was similar to Comparative Example 4, but furthermore, the peel strength between the second layer 3 and the third layer 4 was low at 3 mN / mm, causing the interface to peel off during stretching, and the repeated stretchability was evaluated as "XX".

[0069] Comparative Example 6 was a case in which no special modifications were made to the film, and all evaluations were "X". [Explanation of symbols]

[0070] 1 film 2 1st layer 3 2nd layer 4 3rd layer 5 surface 6 Back side 7 Uneven structure 7a Mountainous ridge 7b Valley ridge 1A area H Height of uneven structure 7 T1 Thickness of the first layer 2 T2 Thickness of the second layer 3 T3 Thickness of the third layer 4 Tn Thickness of the nth layer (n=1, 2, 3)

Claims

1. A film having a first layer, a second layer, and a third layer laminated in this order from one side, The film is a concave-convex structure is formed on the surface on the first layer side; the height of the concave-convex structure is greater than the total thickness of the first layer and the second layer; The recovery rate of the third layer at 20% elongation exceeds 90%; In the method for producing a film, the Young's modulus of the second layer is 650 MPa or more and 3300 MPa or less, forming a concave-convex structure on the surface of a material obtained by laminating the flat second layer and the flat third layer; and forming the first layer by applying dry coating or wet coating to the second layer while the material is stretched so that the height of the concave-convex structure is reduced. A method for producing a film comprising the steps of:

2. In the film, the surface of the third layer opposite to the surface on which the second layer is laminated is approximately flat. The method for producing the film according to claim 1 .

3. In the film, the height of the uneven structure is 150 μm or less. The method for producing a film according to claim 1 or 2.

4. In the film, the thickness of the second layer is 3 μm or more and 50 μm or less. The method for producing the film according to any one of claims 1 to 3.

5. In the film, the interfacial peel strength between the second layer and the third layer is 10 mN / mm or more.

5. A method for producing the film according to claim 1.

6. In the film, the uneven structure has mountain-like or valley-like ridges extending to the edge of the film.

6. A method for producing the film according to claim 1.

Images