JP2022169914A - Film, and laminate - Google Patents

Abstract

To provide a film having flexibility extending with small force, and capable of easily expanding an area even in a film in which a material according to required properties is used, and a laminate therewith.SOLUTION: A film having a surface with an uneven shape extending in two directions and a back surface with an uneven shape extending in two directions according to the uneven shape on the surface satisfies, when a tensile modulus of elasticity is set to Ef, the tensile elastic modulus of the material constituting the film is set to Em, a height of the uneven shape of the film is set to H, and a thickness of the film is set to T, all of the following formulas 1 to 3 are satisfied: Formula 1 T<H; Formula 2<0.1×Em; Formula 3 7000 [N/m]<Em×T. Note that the tensile elastic modulus Ef of the film indicates the tensile elastic modulus in an arbitrary direction in the plane direction of the film.SELECTED DRAWING: Figure 1

Description

The present invention relates to films and laminates.

In general, plastic films have properties such as being lightweight, chemically stable, easy to process, flexible and strong, and mass-producible, and are used for various purposes. Its uses include, for example, packaging materials for packaging foodstuffs and pharmaceuticals, IV packs, shopping bags, posters, tapes, optical films used for liquid crystal televisions, protective films, decorative films, and body attachment. Films, window films pasted on windows, plastic greenhouses, construction materials, etc. Specific materials thereof include, for example, thermoplastic resins such as polyethylene, polypropylene, polystyrene, acrylic polymethyl methacrylate, polycarbonate, polyamide, polyethylene terephthalate, and polybutylene terephthalate, and thermosetting resins such as epoxy resins, polyurethanes, and polyimides. etc.

Appropriate plastic materials are selected depending on the application, and a plurality of types of these materials are stacked to form a laminate. There is also a method of use in which a plurality of plastic materials are mixed in one layer to compensate for the shortcomings of a single material. In many cases, appropriate film materials are selected based on heat resistance, mechanical strength, or transparency. However, it is difficult to say that the required physical properties such as heat resistance and mechanical strength and the flexibility to stretch with a light force are sufficiently compatible only with the devising of these materials and the layer structure.

For example, patches and tapes, which are formulations that are applied to the skin to deliver active ingredients into the body, are required to prevent the active ingredients from being transmitted or migrated to the backing film. Since the strength is high and the flexibility is insufficient, there is a problem that it does not follow the movement of the skin and the feeling of use when applied is not good. As another example, polyethylene terephthalate (PET) film is often used as a base film for various films from the viewpoint of heat resistance, durability, chemical resistance, mechanical properties, etc., but PET film is strong. is high and cannot be used for applications where it is expected to stretch with a light force.

In addition, plastic films generally have the characteristic of having a positive Poisson's ratio, that is, when they are pulled in one direction, they shrink in a direction perpendicular thereto. Therefore, there is a problem that a stronger force is required when trying to stretch in two directions so as to expand the area than when stretching in one direction.

For example, when a film is shaped into a bag and the bag is filled with contents, or when the bag is to be inflated with gas such as air, a considerably larger force is required than when the film is stretched in one direction. In another example, when you want to protect the surface of a curved object, if you try to cover it with a flat film, wrinkles will occur. It can cover the curved surface firmly without entering.

Patent Literature 1 discloses a technique for a film that can be stretched with a light force regardless of the plastic material and can be easily stretched in two directions at the same time. The film takes a shape that repeats mountain folds and valley folds, that is, a so-called bellows shape. By expanding the shape, the film can be stretched in any direction, and can also be stretched in conjunction with the direction perpendicular to the pulling direction. As a result, even a film made of a material that satisfies required properties such as heat resistance and mechanical strength has the flexibility to stretch with a light force, and the area can be easily expanded.

JP 2019-089319 A

According to the technique of Patent Document 1, in order for the film to spread in the direction perpendicular to the direction of tension when the film is stretched, it is necessary to transmit force in the direction perpendicular to the direction of tension. There is a need. However, if the material is too soft or the film thickness is too thin, the material itself will stretch instead of stretching due to the change in the shape of the bellows, or a certain aspect of the film will be distorted, resulting in a shape change that is different from the design. It was found that the If this happens, it will not expand in the orthogonal direction, but will stretch only in the tensile direction.

The present invention has been made in view of such problems, and a film that has flexibility to stretch with a light force and can easily expand the area even in a film using a material that meets the required properties. And it aims at providing the laminated body using the same.

In order to achieve the above object, a representative film of the present invention has a surface with unevenness extending in two directions and an unevenness extending in two directions corresponding to the unevenness on the surface. A film having a back surface, wherein the tensile elastic modulus of the film is Ef, the tensile elastic modulus of the material constituting the film is Em, the height of the uneven shape of the film is H, and the thickness of the film is T is achieved by satisfying all of the following formulas 1 to 3.
Formula 1 T<H
Formula 2 Ef<0.1×Em
Formula 3 7000 [N / m] < Em × T
The tensile elastic modulus Ef of the film indicates the tensile elastic modulus in an arbitrary direction in the plane direction of the film.

ADVANTAGE OF THE INVENTION According to this invention, the film which uses the material according to required property has the flexibility which stretches by light force, and can expand an area easily, and the laminated body using the same is provided. can do
Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

FIG. 1 is a perspective view showing an example of the film of this embodiment. FIG. 2 is a top view of an example of the film of this embodiment, viewed from above. FIG. 3 is a perspective view showing part of the film of this embodiment. FIG. 4 is a cross-sectional view showing a portion of the film of this embodiment. FIG. 5 is a top view (c) and cross-sectional views (a) and (b) showing a portion of the film of this embodiment. FIG. 6 is a top view showing part of the film of this embodiment. FIG. 7 is a top view showing part of the film of this embodiment. FIG. 8 is a perspective view showing a model (enlarged from the actual product) of an example of the film of this embodiment. FIG. 9 is a perspective view showing a model (enlarged from the actual product) of another example of the film of this embodiment. FIG. 10 is a perspective view showing a model (enlarged from the actual product) of another example of the film of this embodiment. FIG. 11 is a perspective view showing a model (enlarged from the actual product) of another example of the film of this embodiment. FIG. 12 is a cross-sectional view showing an example of the film of this embodiment. FIG. 13 is a cross-sectional view showing another example of the film of this embodiment. FIG. 14 is a top view showing an example of arrangement of sections when the film of this embodiment has a plurality of sections. FIG. 15 is a top view showing another example of arrangement of sections when the film of this embodiment has a plurality of sections. FIG. 16 is a cross section showing one example of film lamination according to this embodiment. FIG. 17 is a cross section showing another lamination example of the film of this embodiment. FIG. 18 is a perspective view showing an example of the film.

EMBODIMENT OF THE INVENTION Below, embodiment of the film concerning this invention is described with reference to drawings. Each figure is a schematic diagram, and the size, shape, etc. of each part are appropriately exaggerated for easy understanding. In order to simplify the explanation, the same reference numerals are given to the corresponding parts in each figure. The terms front and back used herein are used for convenience, and either of a pair of sides of the film may be the front or back.

The film 1 of the present invention is a film having an uneven shape 4 on both the front surface 2 and the back surface 3, and the front surface 2 and the back surface 3 are opposed to each other according to the uneven shape 4. That is, the film has a folded shape like origami. FIG. 1 is a perspective view showing an example of the film 1, and FIG. 2 is a top view showing an example of the film 1. As shown in FIG. 3 and 4 show a perspective view and a cross-sectional view showing a part of an example of the film 1 in order to clearly show the folded shape.

At this time, when Ef is the tensile elastic modulus of the film 1, Em is the tensile elastic modulus of the material forming the film 1, H is the height of the uneven shape 4 of the film 1, and T is the thickness of the film 1,
All of the following formulas 1 to 3 are satisfied.
Formula 1: T<H
Formula 2: Ef<0.1×Em
Formula 3: 7000 [N / m] < Em × T
The tensile elastic modulus Ef of the film 1 indicates the tensile elastic modulus in an arbitrary direction along the plane when the film 1 is placed on a plane (a plane parallel to the x direction and the y direction in FIG. 1). and That is, Expression 2 is satisfied in any direction on the plane.

Here, the tensile elastic modulus Ef of the film 1 is the tensile elastic modulus specified by JIS K 7161:2014, and the thickness that gives the cross-sectional area of the film 1 is the sum of the height H of the uneven shape and the film thickness T. It shall be given in sum. In other words, it is assumed to be the apparent tensile modulus. In addition, the tensile modulus Em of the material is the tensile modulus of the film, which is similarly defined in JIS K 7161:2014, for a flat film having no irregularities. At this time, T is the thickness that gives the cross-sectional area of the film.

When Expression 1 is satisfied, that is, when the unevenness height H exceeds the film thickness T, the present film 1 does not have a portion extending straight along the direction in which the unevenness is repeated. In other words, when the film 1 is cut along the x- and y-directions of FIG. is absent and intermittent. Therefore, instead of stretching the material, it becomes possible to stretch by deforming the concave-convex shape 4 like origami, and the flexibility to stretch can be produced with a light force.

Moreover, Equation 2 expresses that the tensile test force of the film 1 is sufficiently smaller than the tensile test force of a normal film made of the same material without the irregularities 4 . By satisfying Equation 2, first, the film 1 is elongated by the deformation of the uneven shape 4 without depending on the deformation of the material itself. Although the film exhibits anisotropy in tensile properties depending on the uneven shape 4, in this embodiment, Expression 2 is satisfied in any direction of the plane on which the film 1 is placed.

Furthermore, Equation 3 expresses the relationships necessary to transmit forces in the tensile direction also in orthogonal directions. In order to expand not only the tensile direction but also the orthogonal direction, it is necessary to transmit the force in the tensile direction to the orthogonal direction. At this time, it is necessary to develop a change in the tensile direction and the orthogonal direction due to the shape change of the uneven shape 4, but if Expression 3 is not satisfied, the material itself will be stretched, not the shape change of the uneven shape 4. Otherwise, one slope of the concave-convex shape 4 may be distorted. In that case, it will stretch by causing a shape change different from the design. In this case, it cannot be expanded in the direction perpendicular to the direction of tension.

As described above, by satisfying the formulas 1, 2, and 3, even a film using a material that meets the required properties has the flexibility to stretch with a light force due to the shape change of the uneven shape 4, and , the force in the tensile direction can also be transmitted in the orthogonal direction, and the area can be easily expanded.

The uneven shape 4 has at least continuous peaks 5 or valleys 6, and the continuous peaks 5 or valleys 6 extend while changing the direction of the ridgeline.

A portion of the uneven shape 4 is shown in FIG. 5(a) and 5(b) are cross-sectional views thereof, and FIG. 5(c) is a top view thereof. In FIG. 5(c), the dashed-dotted line indicates the ridgeline of the peak 5, and the dashed line indicates the ridgeline of the valley 6. As shown in FIG. Also in FIGS. 6 and 7, it is assumed that the one-dot chain line and the dashed line are the same. As shown in FIG. 5(c), the continuous ridgeline of the peaks 5 or the continuous ridgeline of the troughs 6 extending in the x-direction changes direction midway and extends in the y-direction. In this way, by having a shape that changes the direction, it becomes possible to smoothly change the direction of the force in the tensile direction to the direction perpendicular to the direction.

The changing portion for changing the direction of the ridgeline of the peak portion 5 or the ridgeline of the valley portion 6 may be rounded as shown in FIG. A non-absent portion and a rounded portion may be mixed, or may have a linear shape as shown in FIG. 6(c). Also, the change in direction (crossing angle between the x direction and the y direction) does not have to be 90°, and as shown in FIGS.

The concave-convex shape 4 is preferably formed by arranging structures as shown in FIGS. Also, as shown in FIG. 8, the basic form is one in which uneven shapes are arranged alternately. For example, as shown in FIG. They may be arranged by changing the angle, or may be arranged while reversing the uneven shapes arranged alternately as shown in FIG. 11 . In addition to the above, by arranging the structures as shown in FIGS. 5 to 7, the above effect can be exhibited if the shape is established. 8, 9, 10, and 11 are schematic diagrams for making it easy to understand the image of the structure, and needless to say, they are not diagrams showing the size or detailed structure.

The film thickness T and the unevenness height H do not need to be uniform within the film 1 . For example, as shown in FIG. 12, different values such as T1, T2, and T3 may be taken depending on the location of the uneven shape 4. FIG. Here, the film thickness Tn at each location indicates the distance between the front surface 2 and the back surface 3 facing each other as shown in FIG. The film thickness T is represented by the average value obtained by multiplying the ratio of each location and the thickness at that location. The same applies to the uneven shape height H, and different values may be shown depending on the location. Also, the uneven shape height H1 seen from the front surface 2 and the uneven shape height H2 seen from the back surface 3 are different. In that case, the uneven shape height H shall be represented by an average value.

However, the film thickness Tn at each location is within the range of 0.5T≤Tn≤2T regardless of location. Preferably, 0.6T≤Tn≤1.5T. Also, the film thickness T is desirably 1 μm or more and 100 μm or less, and more desirably 5 μm or more and 50 μm or less. The uneven shape height Hn is within the range of 0.6H≦Hn≦1.5H, preferably 0.8H≦Hn≦1.2H, regardless of the location or front and back surfaces. Further, the height H of the uneven shape is desirably 5 μm or more and 500 μm or less, and more desirably 10 μm or more and 200 μm or less. As described above, the height H of the irregularities should exceed the thickness T of the film, and it is desirable that the height H of the irregularities exceeds twice the thickness T of the film. By setting it in such a range, it is possible to have the property of being stretched more flexibly.
Furthermore, the pitch of the irregularities (interval between adjacent irregularities) is preferably 30 μm or more and 1000 μm or less, more preferably 50 μm or more and 500 μm or less, more preferably 50 μm or more and 200 μm or less. be. The inclination angle of the uneven shape is 0° when there is no uneven shape and 90° when perpendicular to the film normal direction, and the maximum value is preferably 40° or more and 90° or less. is preferably 45° or more and 85° or less. This is because by doing so, it is possible to have the property of being stretched more flexibly.

In the above description, the cross-sectional shape of the film is triangular, but the cross-sectional shape is not limited to triangular. Another example is shown in FIG. For example, as shown in FIG. 13(a), the apex of the cross section of the uneven shape may be rounded, or as shown in FIG. The uneven shape may be a trapezoidal shape as shown in 13(c), or convex shapes may be arranged at intervals as shown in FIGS. 13(d) and 13(e). ), only a portion of the uneven cross section may be rounded. Also, these shapes may be combined to combine a number of shapes in one film 1 .

The tensile modulus Ef of the film 1 is preferably 1 MPa<Ef<100 MPa. If it is less than 1 MPa, it will be stretched with a light force, making it difficult to handle. Moreover, if it exceeds 100 MPa, a large force is required to stretch it, and it is difficult to say that it stretches for practical use.

Further, the tensile elastic modulus Em of the material forming the film 1 is preferably 800 MPa<Em<3000 MPa. Within this range, it is possible to produce a film with an appropriate thickness that satisfies Formula 3 and has other appropriate physical properties as a film.

The ratio (surface area ratio) S of the surface area of the film 1 including the irregularities 4 to the area when the film 1 is viewed from above (in the z direction) is preferably 1.2 or more and 2 or less. The larger the surface area ratio S, the greater the possibility that the amount of elongation due to the shape change of the concave-convex shape 4 can be increased, which is preferable. Therefore, when the surface area ratio S is smaller than 1.2, a sufficient elongation cannot be ensured. On the other hand, when the surface area ratio S is larger than 2, it becomes difficult to produce the uneven shape 4 .

Moreover, the film 1 may be configured by arranging a plurality of regions (which are called sections 1A) having the above characteristics. That is, as shown in FIG. 14, the film 1 may have a plurality of sections 1A within the film plane, and each section 1A may have the properties of the film 1. FIG. At this time, the concave-convex shape 4 may not exist between the adjacent sections 1A. By doing so, the film 1 as a whole does not stretch even when pulled and can be handled without problems. It becomes possible to obtain a film.

The sections 1A may be lined up continuously, or may be lined up with gaps between them as shown in FIG. Also, the structure of each section 1A need not be the same, and may include a plurality of different structures as shown in FIGS.

The film 1 of the present embodiment has the effect of stretching even when a force is applied in the normal direction of the film, so it also has the effect of high impact resistance. In addition, even if the film 1 cannot be stretched due to the surrounding environment when a force is applied in the direction normal to the film, the uneven shape 4 is crushed and the impact absorption is high.

In addition, by using a transparent material, it is possible to provide a certain degree of transparency in spite of having the concave-convex shape 4 . This is because the front surface 2 and the back surface 3 basically face each other with the uneven shape 4 interposed therebetween. However, since the irregular shape 4 exists, it is difficult to make it completely transparent.

Furthermore, bending stiffness can be improved in either direction. Bending stiffness is determined by the integral of the product of the geometrical moment of inertia and Young's modulus. Since the film 1 of the present embodiment can increase the geometrical moment of inertia as compared with a normal film having the same amount of resin, the bending rigidity can be increased.

Furthermore, the uneven shape 4 also has the effect of improving the surface area of the film. The surface area of the film affects the rate and amount of release or adsorption of materials kneaded into the film. In addition, by increasing the surface area, it is possible to improve the efficiency of exchanging particles, ions, temperature, electricity, etc. through the film.

(film material)
The material of the film 1 is preferably a thermoplastic resin. Examples include polyethylene, polypropylene, polystyrene, polymethyl methacrylate, ethylene vinyl acetate copolymer, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyacrylonitrile, polylactic acid, cyclic polyolefin, polycarbonate, polyamide, polyethylene terephthalate. , polybutylene terephthalate, polyacetal, and derivatives thereof, but are not particularly limited. Moreover, there is no problem even if it is a cured resin or a metal. These materials may be used alone, or a plurality of these materials may be used in combination. Alternatively, a multilayer structure (also referred to as a laminate) in which a plurality of layers are superimposed may be formed.

(Film manufacturing method)
As for the manufacturing method, for example, a hot press method or an extrusion method can be used.

In the hot press method, the formed film can be produced by passing it between a pair of heating rolls having an uneven surface or through a pair of heated plate-like pressing machines. At this time, it is important that the upper and lower concave shapes and convex shapes are precisely aligned, and that the front and back surfaces of the film after pressing have a structure in which peaks and valleys are continuously repeated.
In addition, in the extrusion molding method, in the cooling process for filming the molten resin extruded from the T-die, a pair of cooling rolls and nip rolls with uneven surfaces corresponding to the uneven structure are used to apply nip pressure. By cooling while cooling, a concave-convex structure can be attached. In this method as well, it goes without saying that precise alignment of the irregularities of the cooling roll and the nip roll affects the film performance.

Furthermore, in another extrusion molding method, a plurality of extruders are used to co-extrude a plurality of different resins by a feed block method or a multi-manifold method to obtain a film having a multilayer structure of two or more layers. can be done. At this time, in the cooling process for forming a film, a cooling roll having surface irregularities corresponding to the irregular shape and a nip roll without irregularities are used to cool while applying nip pressure, so that the film surface in contact with the cooling roll An uneven structure can be attached. Furthermore, at this time, when the height of the uneven shape is large with respect to the film thickness of the first resin layer in contact with the cooling roll, the uneven structure is also added to the interface between the first resin layer and the adjacent second resin layer. be done. Therefore, if the second resin layer is peeled off from the multilayer film after cooling, the first resin layer having uneven shapes on both sides, that is, the film 1 can be obtained.
In addition, any method for adding the concave-convex structure, such as injection molding, can be selected, and the method is not particularly limited.

(Laminate)
The film 1 may be a single layer, or a laminate may be formed by laminating a plurality of films 1 by increasing the layer structure. For example, the first layer may be a gas barrier layer or a drug non-adsorbing layer, and the second layer may be an inexpensive resin layer (bulking layer), a high rigidity layer, or a layer that compensates for the physical properties of the first layer. Of course, the lamination of films may be three or more layers. Further, as shown in FIG. 16, a laminate obtained by laminating a functional layer 7 such as a vapor deposition layer, a hard coat layer, an antireflection layer, a printing layer, etc. by dry coating or wet coating in a post-process on the film 1. You can also At this time, the effect that the layer coated on the surface can be stretched according to the film 1 can be obtained. This is because it extends due to the shape change of the concave-convex shape 4 . In other words, for example, by applying it to a vapor deposition barrier film, it is possible to give elasticity in two directions while suppressing breakage of the vapor deposition layer. Examples of vapor deposition films include metal oxides such as alumina and silica, and metals such as aluminum, gold, silver, and copper. Of course, the function to be exhibited is not limited to barrier properties, but the same applies to light shielding properties, design properties, conductivity, etc., and is not limited to these functions.

In addition, as shown in FIG. 17, a laminate in which another layer (or film) 8 is laminated on the film 1 can also be used. At this time, the film 1 and another layer 8 may be in contact with each other only partially as shown in FIG. Further, it may be in the middle as shown in FIG. 17(b). At this time, another layer 8 is preferably made of a soft material so as not to impair the flexibility of the film 1 .

(Application of film)
For example, the film 1 or a laminate using it can be used as a barrier film, a packaging material, a patch support film such as a poultice, a support film for a tape to be applied to the skin or an object, a decorative film, an optical film, a protective film, and a wearable device. It is conceivable that it can be used as a base material for printing, various film base materials, design films, etc., but the uses are not limited to these.

An adhesive patch support film, which is an application example, is required to have resistance to drugs and additives contained in the adhesive patch, non-adsorptive properties, and barrier properties. All of these requirements can be met by adding an uneven shape to a material with high chemical resistance, non-adsorption properties, and barrier properties to form a film 1 that stretches with a light force. Materials with high chemical resistance, non-adsorption properties, and high barrier properties include, for example, cyclic polyolefins, ethylene-vinyl alcohol copolymers, and polyethylene terephthalate. In addition, since the stress applied to the film 1 when the elongation is the same is small, it is possible to make it difficult to feel the discomfort of being pulled when the film is stretched.

Although the embodiments of the present invention have been exemplified above, it goes without saying that the present invention is not limited to the above embodiments. Moreover, it is arbitrary to combine and use the above embodiments.

Examples prepared by the present inventors will be described in detail below, but the present invention is not limited only to the following examples.

In Comparative Examples 1, 2, and 3, flat films without uneven shapes 4 were used, and the materials constituting the films were polyethylene terephthalate (PET) resin "Bellpet EFG70" manufactured by Bell Polyester Products Co., Ltd., Mitsubishi Chemical Co., Ltd. Ethylene-vinyl alcohol copolymer (EVOH) resin "Soarnol D4403" manufactured by the company and polymethyl methacrylate (PMMA) resin "Acrypet VH000" manufactured by Mitsubishi Chemical Corporation were used. The film thickness T was set to 10 μm in each case. In the following description, the terms PET resin, EVOH resin, and PMMA resin all refer to equivalent resins.

Comparative Examples 4 and 5 have a shape in which the uneven shape 4 extends only in one direction as shown in FIG. The apex angle of peaks and valleys was set to 90°. The uneven shape height H was set to 60 μm in both cases, and PET resin was used as the material. The film thicknesses T were 15 μm and 3 μm, respectively.

Comparative Examples 6, 7, 8, 9, and 10 are shapes in which the uneven shape 4 extends in two directions as shown in FIG. 1 or FIG. , the cross section of which has a shape in which triangles with rounded tops are arranged as shown in FIG. 60°. The height H of the uneven shape was 42 μm when the apex angle was 100°, 50 μm when the apex angle was 90°, and 80 μm when the apex angle was 60°. As the film material, Comparative Examples 6 and 8 used PET resin, and Comparative Examples 7, 9 and 10 used EVOH resin. The film thickness T was 15 μm, 22 μm, 3 μm, 5 μm and 3 μm for Comparative Examples 6, 7, 8, 9 and 10, respectively.

Table 1 shows a summary of the uneven shape 4, the film material, the uneven shape height H, and the film thickness T of the comparative example.

In Example 1, the uneven shape 4 has a shape extending in two directions as shown in FIG. Shaped. The uneven shape height H was 80 μm, the material was PET resin, and the film thickness T was 15 μm.

In Examples 2 to 11, the uneven shape 4 has a shape extending in two directions as shown in FIG. 1 or FIG. A shape in which triangular shapes with rounded apexes as shown in (a) are arranged. The peak-to-valley angle was 120° for Examples 2 and 3, 100° for Example 4, 90° for Examples 5, 6, and 7, and 60° for Examples 8, 9, 10, and 11. The height H of the uneven shape was 28 μm when the peak angle was 110°, 42 μm when the angle was 100°, 50 μm when the angle was 90°, and 80 μm when the angle was 60°. As the film material, Examples 2, 3, 4, 5, 6, 8 and 9 used PET resin, Examples 7 and 10 used EVOH resin, and Example 11 used PMMA resin. The film thickness T was 8 μm for Examples 2, 4, 6, 8, 10 and 11, 5 μm for Examples 3 and 9, and 15 μm for Examples 5 and 7.

Table 2 shows a summary of the uneven shape 4, the film material, the uneven shape height H, and the film thickness T of the example.

A tensile test evaluation was performed as an evaluation for calculating the tensile elastic moduli Em and Ef.

The tensile test evaluation was carried out in accordance with JIS K 7161:2014 using a Tensilon universal material testing machine (RTC-1250A) manufactured by A&D Co., Ltd. The sample width was 15 mm, the distance between chucks was 50 mm, and the pulling speed was 100 mm/min. At this time, in order to consider the anisotropy of the sample, evaluation was performed for five directions with angles changed by 22.5° from the MD (machine direction) direction to the TD (transverse direction) direction. The average value of the elastic moduli in five directions of the samples of Comparative Examples 1, 2, and 3 without the uneven shape 4 is taken as the tensile elastic modulus Em of the material, and the maximum value of the elastic moduli in five directions in the other examples and comparative examples is taken as the tensile elasticity. Ef-max. The thickness necessary for calculating the tensile elastic modulus Ef-max is the sum of the uneven shape height H and the film thickness T, that is, the apparent thickness (H+T).

Indentation test evaluation and tensile test evaluation were performed as evaluations to confirm the effect of the present invention that "it has flexibility to extend with a light force and can be easily expanded in area".

The indentation test evaluation was performed using a texture analyzer (EZ-SX) manufactured by Shimadzu Corporation. A sample was fixed to a metal plate with a hole of 50 mm in diameter, and the center of the hole was pushed in with an indenter of 30 mm in diameter, and the pushing distance and pushing force at that time were evaluated. The indentation distance was measured from the position where the indenter touched the sample to zero, until reaching the position of 40 mm or until the sample broke. The indentation speed was set to 10 mm/min. As the indentation judgment, when the indentation force exceeded 10 N when the indentation distance was 5 mm, it was evaluated as ×, when it was 10 N or less, it was evaluated as ◯, and when it was 5 N or less, it was evaluated as ⊚.
Also, at this time, the samples were observed, and if neck-in was clearly observed as if only a part of the sample had elongated, it was evaluated as x as the neck-in evaluation result, and if it could not be confirmed as such, it was evaluated as ◯.

Tensilon universal material testing machine (RTC-1250A) manufactured by A&D Co., Ltd. was used for tensile test evaluation. The sample width was 15 mm, the distance between chucks was 50 mm, and the tensile speed was 100 mm/min. The sample was stopped when it was stretched by 10%, i.e., 5 mm, and the sample width at that time was evaluated to determine whether the sample spread in the width direction. At this time, evaluation was performed in three directions with an angle change of 45° from the MD direction to the TD direction. ○ indicates that it spreads in any direction, and ◎ indicates that it spreads in any direction.

As a comprehensive judgment, among the three judgments of indentation judgment, neck-in evaluation, and spread evaluation in the width direction, if even one was x, it was x, if all were ○ or more, it was 〇, especially the indentation with judgment ◎ When both the judgment and the spread evaluation in the width direction were ⊚, and the neck-in evaluation was also ◯, it was evaluated as ⊚.

Tables 3 and 4 show the summaries of the evaluation results of Comparative Examples and Examples, respectively.

From Tables 3 and 4, it can be seen that although the irregular shape 4, the film material, the irregular shape height H, and the film thickness T are important parameters, it is not possible to judge whether or not the effect can be obtained only by these parameters. On the other hand, any one that satisfies Equations 1, 2, and 3 has a certain effect.

Comparative Examples 1, 2, and 3, which did not satisfy the formula 1 (T<H), did not exhibit any elongation, and all evaluations were x. Further, in Comparative Examples 4, 5, 6, and 7, which did not satisfy Equation 2 (Ef-max<0.1×Em), the neck-in determination was all x. In Comparative Examples 4 and 6, it was very difficult to stretch by pressing, and the pressing force exceeded 10N. In Comparative Examples 5 and 7, the pressing force was 10 N or less, which suggests that the film was considerably thin and was stretched due to plastic deformation of the film itself. Furthermore, Comparative Examples 5, 8, 9, and 10, which do not satisfy Expression 3 (7000 [N/m]<Em×T), were judged to be x in width direction spread, that is, there was no spread. Also, in Comparative Example 10, the Ef-max was less than 1 MPa, and it was very difficult to handle as a sample in the first place.

On the other hand, Examples 1 to 11 all satisfied Expressions 1, 2 and 3, and the evaluation results were good. However, in Example 1, in which the ridgeline extending in two directions did not change direction, the "widthwise spread" was not sufficient, and the "widthwise spread" judgment did not reach ◎. became 0. In addition, in Examples 2 and 5, in which Ef-max exceeded 100 MPa, although the pushing force was 10 N or less, it exceeded 5 N. Since it did not reach, the overall judgment was also 0. In addition, in Examples 2 and 3 in which the surface area ratio S was less than 1.2, the pressing force was 10 N or less but exceeded 5 N, and it could not be said to be sufficiently soft. Since it did not reach, the overall judgment was also 0. Since the larger the surface area ratio S, the softer the sample, an attempt was made to prepare a sample having a concave-convex shape 4 exceeding 2, but it was difficult to produce a film, and as a result, it could not be obtained.

1 Film 2 Front 3 Back 4 Concavo-convex shape 5 Peak 6 Valley 7 Functional layer 8 Another layer 1A Section H Height T of concavo-convex shape 4 Thickness of film 1

Claims (8)

A film having a front surface with an uneven shape extending in two directions and a back surface with an uneven shape extending in two directions corresponding to the uneven shape of the surface,
When the tensile modulus of elasticity of the film is Ef, the tensile modulus of elasticity of the material constituting the film is Em, the height of the uneven shape of the film is H, and the thickness of the film is T,
A film characterized by satisfying all of the following formulas 1 to 3.
Formula 1 T<H
Formula 2 Ef<0.1×Em
Formula 3 7000 [N / m] < Em × T
The tensile elastic modulus Ef of the film indicates the tensile elastic modulus in an arbitrary direction in the plane direction of the film. 2. The film of claim 1, wherein 1 MPa<Ef<100 MPa. The uneven shape has at least continuous peaks or valleys,
The continuous peaks or valleys extend while changing the direction of the ridgeline.
The film according to claim 1 or 2, characterized by: A ratio S of the surface area of the film including the uneven shape to the area of the film when viewed from above is 1.2 or more and 2 or less.
The film according to any one of claims 1 to 3, characterized in that: Forming the uneven shape in the compartment,
A plurality of the partitions are arranged, and there is no uneven shape between the adjacent partitions,
The film according to any one of claims 1 to 4, characterized in that: A laminate comprising a functional layer laminated on at least one surface of the film according to any one of claims 1 to 5. A laminate comprising a plurality of the films according to any one of claims 1 to 5 laminated together. A laminate comprising the film according to any one of claims 1 to 5 and another film laminated thereon.

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