Gas resistance reduction structure and mobile body

Abstract

To provide a gas resistance reduction structure that can maintain the effect of reducing gas resistance due to uneven surfaces. [Solution] The gas resistance reduction structure 1 comprises a base body 2 and a resin layer 3 disposed on one surface of the base body 2. The resin layer 3 has, in order from the base body 2 side, a covering portion 4 that covers one surface of the base body 2 and a protrusion portion 5, and the thickness of the covering portion 4 is 5 μm or more and 50 μm or less.

Description

[Technical Field]

[0001] This disclosure relates to a gas resistance reducing structure for reducing gas resistance, and a mobile body using the same. [Background technology]

[0002] In recent years, research on fluid resistance reduction technologies has been actively conducted in fields such as mobile bodies moving through fluids and fluid transfer, with the aim of achieving energy conservation and reduction of carbon dioxide emissions. Specifically, in recent years, research on fluid resistance reduction technologies has been actively conducted in fields such as automobiles, railway vehicles, and aircraft, with the aim of improving fuel efficiency and reducing carbon dioxide emissions.

[0003] Conventionally, techniques for reducing fluid resistance include, for example, creating irregularities on the surface of an object. For instance, riblets are known as a method for reducing frictional resistance, and dimples are known as a method for reducing pressure resistance (see, for example, Patent Document 1). Patent Document 2 also discloses a technical concept in which rough and smooth surfaces are arranged to generate longitudinal vortices at the boundary between the rough and smooth surfaces and suppress flow separation. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2010 / 29844 [Patent Document 2] Japanese Patent Publication No. 2013-57390 [Overview of the project] [Problems that the invention aims to solve]

[0005] The inventors of this disclosure were considering forming the above-mentioned irregularities using resin, and in doing so, discovered a new problem: when the irregularities are formed using resin, the protrusions wear down over time due to deterioration, reducing the height of the protrusions and thus decreasing the gas resistance reduction effect due to the irregularities.

[0006] This disclosure has been made in view of the above-mentioned problems, and aims to provide a gas resistance reduction structure that can maintain the effect of reducing gas resistance due to unevenness. [Means for solving the problem]

[0007] One embodiment of the present disclosure provides a gas resistance reducing structure comprising a substrate and a resin layer disposed on one surface of the substrate, wherein the resin layer has, in order from the substrate side, a covering portion that covers one surface of the substrate and a protruding portion, and the thickness of the covering portion is 5 μm or more and 50 μm or less.

[0008] Other embodiments of the present disclosure provide a mobile body having the gas resistance reduction structure described above. [Effects of the Invention]

[0009] This disclosure provides the effect of maintaining the gas resistance reduction effect due to the uneven surface. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic cross-sectional view illustrating an example of a gas resistance reduction structure in this disclosure. [Figure 2] This is a schematic cross-sectional view illustrating the change in the height of the protrusions due to aging in the gas resistance reduction structure described herein. [Figure 3] This is a schematic cross-sectional view illustrating the change in the height of the protrusions due to aging in a gas resistance reduction structure. [Figure 4] These are schematic plan views and cross-sectional views illustrating gas resistance reduction structures in this disclosure. [Figure 5] This is a schematic perspective view illustrating an example of a gas resistance reduction structure in this disclosure. [Figure 6] This is a schematic diagram illustrating the gas flow in the gas resistance reduction structure described herein. [Figure 7] This is a schematic diagram illustrating the gas flow in a gas resistance reduction structure. [Figure 8] It is a schematic cross-sectional view illustrating the gas resistance reduction structure in the present disclosure. [Figure 9] It is a schematic perspective view illustrating the gas resistance reduction structure in the present disclosure. [Figure 10] It is a schematic plan view and cross-sectional view illustrating the gas resistance reduction structure in the present disclosure. [Figure 11] It is a schematic plan view and cross-sectional view illustrating the gas resistance reduction structure in the present disclosure. [Figure 12] It is a schematic plan view illustrating the gas resistance reduction structure in the present disclosure. [Figure 13] It is a schematic cross-sectional view illustrating the first region of the gas resistance reduction structure in the present disclosure. [Figure 14] It is a schematic cross-sectional view illustrating the convex portion in the first region of the gas resistance reduction structure in the present disclosure. [Figure 15] It is a schematic plan view illustrating the gas resistance reduction structure in the present disclosure. [Figure 16] It is a schematic side view illustrating an application example of the gas resistance reduction structure in the present disclosure. [Figure 17] It is a schematic diagram illustrating a method for manufacturing the film-like gas resistance reduction structure of the present disclosure. [Figure 18] It is a schematic diagram illustrating a method for manufacturing another film-like gas resistance reduction structure. [Figure 19] It is a schematic perspective view illustrating the film-like gas resistance reduction structure of the present disclosure. [Figure 20] It is a schematic perspective view illustrating another film-like gas resistance reduction structure. [Figure 21] It is a schematic plan view and cross-sectional view illustrating the gas resistance reduction structure in the present disclosure. [Figure 22] It is a schematic plan view and cross-sectional view illustrating the gas resistance reduction structure in the present disclosure. [Figure 23] It is a schematic plan view and cross-sectional view illustrating the gas resistance reduction structure in the present disclosure. [Figure 24]This is a schematic cross-sectional view illustrating an example of a gas resistance reduction structure in this disclosure. [Figure 25] These are schematic plan views and cross-sectional views illustrating gas resistance reduction structures in this disclosure. [Figure 26] This is a schematic cross-sectional view illustrating an example of a gas resistance reduction structure in this disclosure. [Figure 27] This is a schematic cross-sectional view illustrating an example of a gas resistance reduction structure in this disclosure. [Figure 28] This graph shows the height of the protrusions after weathering tests in the gas resistance reduction structures of Example 1 and Comparative Example 1. [Figure 29] These are schematic top, side, and rear views showing a model of the truck's shape. [Modes for carrying out the invention]

[0011] Embodiments of this disclosure will be described below with reference to drawings and other figures. However, this disclosure can be implemented in many different ways and should not be interpreted as being limited to the embodiments described below. In addition, the drawings may be schematically represented in terms of width, thickness, shape, etc. of each part compared to the actual form in order to make the explanation clearer, but these are merely examples and should not limit the interpretation of this disclosure. Furthermore, in this specification and each figure, elements similar to those described above with respect to previously shown figures will be denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0012] In this specification, when describing a configuration in which one member is placed on top of another member, unless otherwise specified, the terms "on top" or "below" include both cases: one in which the other member is placed directly above or below the other member so as to be in contact with it, and another in which the other member is placed above or below the other member via yet another member. Similarly, when describing a configuration in this specification in which one member is placed on the surface of another member, unless otherwise specified, the terms "on the surface" include both cases: one in which the other member is placed directly above or below the other member so as to be in contact with it, and another in which the other member is placed above or below the other member via yet another member.

[0013] Furthermore, in this specification, the terms “film,” “sheet,” and “plate” are not distinguished from each other solely on the basis of name differences. For example, “film” includes sheets and plates.

[0014] The inventors of this disclosure were considering forming irregularities using resin to reduce gas resistance, and discovered a new problem: for example, as shown in Figure 3(a), when a resin-containing protrusion 105 is arranged on one surface of a substrate 102, as shown in Figures 3(a) and 3(b), the protrusion 105 deteriorates over time, causing the height of the protrusion to decrease from X1 to X2, thus reducing the gas resistance reduction effect due to the irregularities. The inventors of this disclosure then found that by covering one surface of the substrate with a coating, arranging the protrusion on the surface of the coating opposite to the substrate, and using resin for both the coating and the protrusion, the reduction in the height of the protrusion due to deterioration over time can be suppressed. This disclosure is based on these findings.

[0015] The gas resistance reduction structure and mobile body described herein will be explained in detail below.

[0016] A. Gas resistance reduction structure The gas resistance reduction structure in this disclosure comprises a substrate and a resin layer disposed on one surface of the substrate, wherein the resin layer has, in order from the substrate side, a covering portion that covers one surface of the substrate and a protruding portion, and the thickness of the covering portion is 5 μm or more and 50 μm or less.

[0017] Figure 1 is a schematic cross-sectional view showing an example of a gas resistance reduction structure in this disclosure. As shown in Figure 1, the gas resistance reduction structure 1 includes a base body 2 and a resin layer 3 disposed on one surface of the base body 2. The resin layer 3 has, in order from the base body 2 side, a covering portion 4 that covers one surface of the base body 2 and a plurality of protrusions 5. The thickness T1 of the covering portion 4 is within a predetermined range.

[0018] Figure 2 is a schematic cross-sectional view illustrating the change in the height of the protrusions due to aging in the gas resistance reduction structure of this disclosure. As shown in Figures 2(a) and 2(b), the protrusions 5 thin out due to aging. At this time, since a covering portion 4 is arranged on one surface of the substrate 2, in the areas where the protrusions 5 are not arranged, the covering portion 4 also thins out due to aging, and the thickness of the covering portion 4 decreases from T1 to T2. Therefore, even if the protrusions 5 thin out due to aging, the heights H1 and H2 of the protrusions 5 do not change much because the covering portion 4 also thins out, and the height of the protrusions 5 can be maintained. Thus, the gas resistance reduction effect due to the uneven surface can be maintained.

[0019] Furthermore, in this disclosure, since one surface of the substrate is covered by the coating, the substrate can be protected by the coating, thereby improving weather resistance.

[0020] The following describes the various components of the gas resistance reduction structure in this disclosure.

[0021] 1. Resin layer The resin layer in this disclosure is a component disposed on one surface of a substrate, and has, in order from the substrate side, a covering portion that covers one surface of the substrate and a protruding portion.

[0022] (1) Covered part The covering portion in this disclosure is arranged to cover one surface of the substrate.

[0023] In this disclosure, the thickness of the coating portion is 5 μm or more, preferably 10 μm or more, more preferably 12 μm or more, and may be 20 μm or more. If the thickness of the coating portion is within the above range, even if the coating portion thins out along with the protrusions due to aging deterioration, it is possible to suppress the disappearance of the coating portion and the exposure of the substrate. On the other hand, the thickness of the coating portion is 50 μm or less, may be 40 μm or less, may be 30 μm or less, and may be 20 μm or less. If the substrate is a resin film and is stretchable, the thickness of the coating portion being within the above range can suppress the occurrence of cracks in the coating portion when the substrate is stretched. Specifically, the thickness of the coating portion is 5 μm or more and 50 μm or less, preferably 10 μm or more and 40 μm or less, more preferably 10 μm or more and 30 μm or less, and even more preferably 12 μm or more and 20 μm or less.

[0024] Furthermore, as will be described later, the height of the protrusions is appropriately selected according to the gas flow velocity. Therefore, the ratio of the thickness of the covering to the height of the protrusions is also appropriately selected according to the gas flow velocity.

[0025] The thickness of the coating is the thickness of the portion of the resin layer where no protrusions are located, and is indicated by the symbol T1 in Figure 1, for example. The thickness of the coating is measured by observing the cross-section of the gas resistance reduction structure with a microscope. The thickness of the coating is the arithmetic mean of the thicknesses of 10 randomly selected locations.

[0026] The covering may be transparent or opaque.

[0027] Resin is used as the material for the coating. The material for the coating is not particularly limited, and examples include cured products of curable resin compositions and thermoplastic resins. Examples of curable resin compositions include ionizing radiation curable resin compositions such as ultraviolet curable resin compositions and electron beam curable resin compositions, and thermosetting resin compositions. In particular, the coating preferably contains cured products of curable resin compositions, and more preferably contains cured products of ultraviolet curable resin compositions. This can improve the durability of the coating. Furthermore, when the gas resistance reduction structure in this disclosure is used in moving objects such as automobiles, railway vehicles, and aircraft, the material for the coating may be paint used for painting moving objects. In addition to resin, the coating may also contain metal particles and ceramic particles.

[0028] The coated portion preferably contains an ultraviolet absorber. In this case, the protruding portion also preferably contains an ultraviolet absorber. That is, it is preferable that the resin layer having the coated portion and the protruding portion contains an ultraviolet absorber. This can improve the weather resistance of the coated portion and the protruding portion, and suppress the film loss of the coated portion and the protruding portion due to aging. As a result, the reduction in the height of the protruding portion due to aging can be further suppressed.

[0029] The UV absorber preferably absorbs long-wavelength ultraviolet light. The absorption wavelength peak of the UV absorber is preferably, for example, 290 nm to 364 nm, more preferably 300 nm to 350 nm, and even more preferably 310 nm to 340 nm. The UV absorber can efficiently absorb long-wavelength ultraviolet light, which can further suppress film loss on the coated and protruding parts due to aging.

[0030] The absorption wavelength peak of an ultraviolet absorber is determined by the following method. First, the transmittance of the resin layer is determined as described later. Next, the cut wavelength of the resin layer is determined. The cut wavelength is the wavelength at which the transmittance is 10% or less. Then, the wavelength at which the transmittance is lowest within the cut wavelength range of the resin layer is considered to be the absorption wavelength peak of the ultraviolet absorber.

[0031] When the resin layer contains a cured product of an ultraviolet-curable resin composition, it is preferable that the absorption wavelength band of the ultraviolet absorber contained in the resin layer differs from the absorption wavelength band of the polymerization initiator contained in the ultraviolet-curable resin composition. Specifically, it is preferable that the absorption wavelength peak of the ultraviolet absorber differs from the absorption wavelength peak of the polymerization initiator. More specifically, it is preferable that the absorption wavelength peak of the ultraviolet absorber differs from the exposure wavelength for curing the ultraviolet-curable resin composition. By shifting the absorption wavelength band of the ultraviolet absorber from the absorption wavelength band of the polymerization initiator for curing the ultraviolet-curable resin composition, curing inhibition can be suppressed. That is, by shifting the absorption wavelength band of the ultraviolet absorber from the exposure wavelength, curing inhibition can be suppressed. This further suppresses film loss of the coated portion and protrusions due to aging. As a result, the reduction in the height of the protrusions due to aging can be further suppressed.

[0032] When the resin layer contains a cured product of an ultraviolet-curable resin composition, the transmittance of the ultraviolet absorber contained in the resin layer at a wavelength of 365 nm is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. The exposure wavelength for curing ultraviolet-curable resin compositions is mainly the i-line (365 nm). Therefore, if the transmittance of the ultraviolet absorber at a wavelength of 365 nm is within the above range, it can be said that the absorption wavelength band of the ultraviolet absorber is shifted from the exposure wavelength. Thus, as described above, the reduction in the height of the protrusions due to aging can be further suppressed.

[0033] Furthermore, when the resin layer contains a cured product of an ultraviolet-curable resin composition, the transmittance of the ultraviolet absorber contained in the resin layer at a wavelength of 405 nm is preferably 50% or more, more preferably 70% or more, and even more preferably 90% or more. In some cases, the g-line (405 nm) is used as the exposure wavelength for curing the ultraviolet-curable resin composition. Therefore, if the transmittance of the ultraviolet absorber at a wavelength of 405 nm is within the above range, it can be said that the absorption wavelength band of the ultraviolet absorber is shifted from the exposure wavelength. Thus, as described above, the reduction in the height of the protrusions due to aging can be further suppressed.

[0034] The transmittance of the UV absorber is determined by the following method. First, the transmittance of the resin layer is determined as described later. Then, the transmittance of the resin layer is considered to be the transmittance of the UV absorber.

[0035] When the resin layer contains an ultraviolet absorber, the transmittance of the resin layer at a wavelength of 380 nm is preferably 95% or less, more preferably 80% or less, and even more preferably 70% or less. If the transmittance of the resin layer at a wavelength of 380 nm is within the above range, it can be said that the resin layer containing the ultraviolet absorber is absorbing long-wavelength ultraviolet light. Therefore, the resin layer can protect the gas resistance reduction structure from long-wavelength ultraviolet light. Thus, film loss of the coating and protrusions due to aging can be further suppressed. On the other hand, the transmittance of the resin layer at a wavelength of 380 nm is, for example, 40% or more. If the transmittance of the resin layer at a wavelength of 380 nm is too low, the transmission of visible light around 380 nm will be inhibited, which may cause the resin layer to take on a yellowish tint.

[0036] The transmittance of the resin layer is determined by the following method. First, the transmittance of the gas resistance reduction structure is measured using a spectrophotometer. Next, only the resin layer is removed from the gas resistance reduction structure. Methods for removing the resin layer include polishing. Then, the transmittance of the gas resistance reduction structure after the resin layer has been removed is measured using a spectrophotometer. Finally, the transmittance of the resin layer is calculated from the difference in transmittance before and after the removal of the resin layer. The spectrophotometer used conforms to JIS K7361-1:1997 (Plastics - Test methods for total light transmittance of transparent materials - Part 1: Single beam method). The transmittance of the resin layer is the arithmetic mean of three measured values.

[0037] The UV absorber is preferably one that satisfies the above characteristics, and examples include triazine-based UV absorbers, benzotriazole-based UV absorbers, and benzophenone-based UV absorbers. Among these, triazine-based UV absorbers are preferred from the viewpoint of absorption wavelength range. Furthermore, hydroxyphenyltriazine-based UV absorbers are preferred from the viewpoint of weather resistance.

[0038] The amount of ultraviolet absorber in the resin layer is, for example, 0.1 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the resin component.

[0039] When the resin layer contains a cured product of an ultraviolet-curable resin composition, the ultraviolet-curable resin composition contains a polymerization initiator. As described above, it is preferable that the absorption wavelength peak of the polymerization initiator differs from that of the ultraviolet absorber. In particular, it is preferable that the polymerization initiator absorbs long-wavelength ultraviolet light, and more preferably absorbs long wavelengths within long-wavelength ultraviolet light. By having the absorption wavelength peak of the polymerization initiator be on the longer wavelength side than the cut-off wavelength of the ultraviolet absorber, inhibition of the polymerization reaction can be suppressed. The polymerization initiator is appropriately selected from known radical polymerization initiators. Among these, 2,4,6-trimethylbenzoyldiphenylphosphine oxide is preferably used.

[0040] Furthermore, the coating may contain additives such as light stabilizers, antioxidants, plasticizers, stabilizers, lubricants, fillers, colorants, processing aids, antistatic agents, and twist-resistant agents, as needed.

[0041] (2) Convex part In this disclosure, the resin layer has a protrusion on the surface of the coating portion opposite to the substrate.

[0042] Details of the protrusions will be explained in the preferred embodiment of the gas resistance reduction structure described later.

[0043] The material of the protrusions is the same as the material of the coating portion described above. The material of the protrusions may be the same as the material of the coating portion, or it may be different, but it is preferable that they be the same. By having the protrusions and the coating portion made of the same material, the amount of film loss of the protrusions and the coating portion due to aging can be made uniform. Therefore, the height of the protrusions can be maintained, and the gas resistance reduction effect can be maintained.

[0044] Furthermore, when the gas resistance reduction structure in this disclosure is used in a moving object such as an automobile, railway vehicle, or aircraft, the material of the protrusions may be paint used for painting the moving object. In this case, by shaping the paint film, a coating portion and protrusions made of the same material can be formed.

[0045] The protrusion may be integrally formed with the covering portion, or it may be formed separately from the covering portion. If the protrusion is integrally formed with the covering portion, the material of the protrusion will be the same as the material of the covering portion.

[0046] (3) Method for forming a resin layer The method for forming the resin layer may be to form a coating portion on a substrate and then form a protrusion on the coating portion, or to form the coating portion and the protrusion on the substrate simultaneously. Among these, the method of forming the coating portion and the protrusion simultaneously is preferred. The protrusion and coating portion can be made from the same material. The method of forming the coating portion and the protrusion simultaneously may be, for example, a method of forming the coating portion and the protrusion on a substrate, or a method of forming an uneven shape on the surface of the resin layer opposite to the substrate. Alternatively, a resin layer having a coating portion and a protrusion may be formed separately, and that resin layer may be laminated onto the substrate.

[0047] Methods for forming coatings and protrusions on a substrate include, for example, a method using an ultraviolet-curable resin composition, applying the ultraviolet-curable resin composition to a mold, pressing the substrate into contact with the coating film, curing the ultraviolet-curable resin composition by irradiation with ultraviolet light, and then peeling it off the mold; and a method using an ultraviolet-curable resin composition, applying the ultraviolet-curable resin composition onto a substrate, pressing a mold against the coating film, curing the ultraviolet-curable resin composition by irradiation with ultraviolet light, and then peeling it off the mold. These methods are known as the photopolymer method (2P method). Another method for forming coatings and protrusions on a substrate is the so-called lithography method, which uses an ionizing radiation-curable resin composition, applying the ionizing radiation-curable resin composition to a substrate, irradiating it in a pattern with ionizing radiation such as ultraviolet light or electron beams, and then developing it.

[0048] The method for applying the curable resin composition is not particularly limited as long as it can uniformly apply the curable resin composition onto the substrate, and general application methods can be used.

[0049] Furthermore, methods for creating a textured surface on the side of the resin layer opposite the substrate include, for example, embossing and laser processing. In the case of embossing, the material of the resin layer is not particularly limited as long as it is a material that can be embossed, and thermoplastic resins can be used.

[0050] Among these methods, the photopolymerization method is preferred, and a more preferred method involves using an ultraviolet-curable resin composition, applying the ultraviolet-curable resin composition to a mold, adhering a substrate to the coating, curing the ultraviolet-curable resin composition by irradiation with ultraviolet light, and then peeling it off the mold. This is because it allows for the easy formation of high aspect ratio protrusions.

[0051] 2.Base The substrate in this disclosure is not particularly limited and includes, for example, a resin member, a metal member, and a ceramic member.

[0052] (1) Resin component For example, thermoplastic resins are used as materials for resin components. Specifically, general-purpose plastics and engineering plastics are examples. Among these, polyvinyl chloride resin is preferred because it has excellent weather resistance and abrasion resistance. Furthermore, when the gas resistance reduction structure is applied to the surface of an object, it also exhibits excellent conformability to the object.

[0053] Furthermore, the resin component may contain additives such as plasticizers, stabilizers, lubricants, fillers, colorants, processing aids, UV absorbers, antioxidants, antistatic agents, and twist-resistant agents, as needed. In particular, it is preferable that the resin component contains a weather-resistant agent. Examples of weather-resistant agents include UV absorbers, light stabilizers, and antioxidants. By containing a weather-resistant agent, the weather resistance of the resin component can be improved. Also, when the weather resistance of the resin component is high, the resin component is less likely to wear down due to aging deterioration, so if a covering is not provided, the reduction in the height of the protrusions due to aging deterioration becomes significant. For this reason, this disclosure is useful when the resin component contains a weather-resistant agent, that is, when the weather resistance of the resin component is high. In particular, it is preferable that the resin component contains a UV absorber.

[0054] When the resin layer contains a cured product of an ultraviolet-curable resin composition, it is preferable that the absorption wavelength band of the ultraviolet absorber contained in the resin member differs from the absorption wavelength band of the polymerization initiator contained in the ultraviolet-curable resin composition used in the resin layer. Specifically, it is preferable that the absorption wavelength peak of the ultraviolet absorber contained in the resin member differs from the absorption wavelength peak of the polymerization initiator used in the resin layer. More specifically, it is preferable that the absorption wavelength peak of the ultraviolet absorber contained in the resin member differs from the exposure wavelength for curing the ultraviolet-curable resin composition used in the resin layer. By shifting the absorption wavelength band of the ultraviolet absorber contained in the resin member from the absorption wavelength band of the polymerization initiator for curing the ultraviolet-curable resin composition used in the resin layer, inhibition of resin layer curing can be suppressed. In other words, by shifting the absorption wavelength band of the ultraviolet absorber contained in the resin member from the exposure wavelength during resin layer formation, inhibition of resin layer curing can be suppressed. This further suppresses film loss of the coated portion and protrusions due to aging. As a result, the reduction in the height of the protrusions due to aging can be further suppressed.

[0055] When the resin layer contains a cured product of an ultraviolet-curable resin composition, the transmittance of the resin member at a wavelength of 365 nm is preferably 10% or more, more preferably 20% or more, and even more preferably 25% or more. The exposure wavelength is mainly the i-line (365 nm). Therefore, by having the transmittance of the resin member at a wavelength of 365 nm within the above range, the resin layer can be sufficiently cured. Furthermore, if the transmittance of the resin member at a wavelength of 365 nm is within the above range, it can be said that the absorption wavelength band of the ultraviolet absorber contained in the resin member is shifted from the exposure wavelength. Thus, as described above, the reduction in the height of the protrusions due to aging can be further suppressed.

[0056] Furthermore, when the resin layer contains a cured product of an ultraviolet-curable resin composition, the transmittance of the resin member at a wavelength of 405 nm is preferably 50% or more, more preferably 70% or more, and even more preferably 90% or more. In some cases, the g-line (405 nm) may be used as the exposure wavelength. Therefore, by having the transmittance of the resin member at a wavelength of 405 nm within the above range, the resin layer can be sufficiently cured. Also, if the transmittance of the resin member at a wavelength of 405 nm is within the above range, it can be said that the absorption wavelength band of the ultraviolet absorber contained in the resin member is shifted from the exposure wavelength. Thus, as described above, the reduction in the height of the protrusions due to aging can be further suppressed.

[0057] The transmittance of the resin component is measured using a spectrophotometer. When measuring the transmittance of the resin component, only the substrate (resin component) is removed from the gas resistance reduction structure. Methods for removing components other than the substrate (resin component) from the gas resistance reduction structure include polishing. The spectrophotometer used conforms to JIS K7361-1:1997 (Plastics - Test methods for total light transmittance of transparent materials - Part 1: Single beam method). Furthermore, the transmittance of the resin component is the arithmetic mean of three measured values.

[0058] The resin component may be transparent or opaque.

[0059] The form of the resin member is not particularly limited and includes, for example, a resin film and a resin molded product. Among these, a resin film is preferred. When the resin member is a resin film, a resin layer is arranged on one side of the resin film. When the resin member is a resin molded product, a resin layer is arranged on at least one side of the resin molded product.

[0060] The thickness of the resin film is not particularly limited and is selected appropriately depending on the application. For example, when the resin film is used as a wrapping film or marking film for moving objects such as automobiles, trains, and aircraft, the thickness of the resin film is, for example, 80 μm to 350 μm.

[0061] In this disclosure, the substrate is preferably a resin member. As described above, the method for forming the resin layer is preferably a photopolymerization method. If the substrate is a resin member, when forming the resin layer by the photopolymerization method, ultraviolet light can be irradiated from the substrate side.

[0062] (2) Metal members Examples of metal component forms include metal sheets and metal parts. If the metal component is a metal sheet, a resin layer is placed on one side of the metal sheet. If the metal component is a metal part, a resin layer is placed on at least one side of the metal part.

[0063] The metal sheet may have at least a metal layer. The thickness of the metal layer is not particularly limited and can be appropriately selected depending on the application.

[0064] Examples of materials for metal components include aluminum, aluminum alloys, titanium, titanium alloys, copper, iron, and stainless steel.

[0065] (3) Ceramic components Examples of ceramic component forms include molded ceramic products. Fine ceramics can be used as the material for the ceramic component.

[0066] 3. Embodiment of a Gas Resistance Reduction Structure The gas resistance reduction structure described herein has three preferred embodiments. Each embodiment is described below.

[0067] (1) First Embodiment A first embodiment of a gas resistance reduction structure in this disclosure comprises a substrate and a resin layer disposed on one surface of the substrate, wherein the resin layer has, in order from the substrate side, a covering portion that covers one surface of the substrate and a convex portion, wherein the gas resistance reduction structure has a first region having an uneven structure including the convex portion and concave portion on the surface on the resin layer side and a second region adjacent to the first region, and the first region and the second region extend in a band shape in a second direction intersecting the first direction.

[0068] This embodiment utilizes a technique that generates vortices at the boundary between a rough surface and a smooth surface to suppress flow separation. When gas flows along a rough surface and a smooth surface, the frictional resistance of the rough surface is greater than that of the smooth surface. Therefore, the gas flow velocity is faster on the smooth surface and slower on the rough surface, resulting in a difference in gas flow velocity between the smooth and rough surfaces. As a result, vortices are generated at the boundary between the rough and smooth surfaces. In this embodiment, the first region has an uneven structure including convex and concave parts, and is a region with high gas frictional resistance. On the other hand, the second region is a region with low gas frictional resistance. Therefore, when gas flows along the resin layer side of the gas resistance reduction structure, vortices are generated at the boundary between the first region and the second region.

[0069] As described above, the second region is a region where the frictional resistance of the gas is smaller compared to the first region. The second region has, for example, a flat surface without an uneven structure. Alternatively, the second region may have an uneven structure, in which case the height of the protrusions in the second region is smaller than the height of the protrusions in the first region.

[0070] Figures 4(a) to 4(c) and 5 are schematic plan views, cross-sectional views, and perspective views showing an example of a gas resistance reduction structure of this embodiment. Figure 4(b) is a cross-sectional view along line AA of Figure 4(a), Figure 4(c) is a cross-sectional view along line BB of Figure 4(a), and Figure 5 is a perspective view of Figure 4(a). As shown in Figures 4(a) to 4(c) and 5, in the gas resistance reduction structure 1A, a first region 11 having an uneven structure including convex portions 5 and concave portions 6, and a second region 12 are alternately arranged in the first direction d1.

[0071] Figures 6(a) and 6(b) are schematic diagrams illustrating the flow of gas in the gas resistance reduction structure of this embodiment, with Figure 6(b) being a cross-sectional view along line AA in Figure 6(a). As shown in Figure 6(a), when gas F flows along the surface of the gas resistance reduction structure 1A, as shown in Figure 6(b), the flow direction d of gas F between the first region 11 and the second region 12 F Near the boundary parallel to the first region, a vortex V is generated. The generation of vortex V suppresses the separation of the gas F flow from the surface of the gas resistance reduction structure 1A. When an object is placed in a gas flow, the drag forces acting on the object include, for example, frictional resistance and pressure resistance. Frictional resistance is generated by friction between the gas and the surface. Pressure resistance is generated by the pressure difference between the front and back. In other words, pressure resistance is generated by flow separation. In this embodiment, the focus is on reducing pressure resistance among the gas resistances. In the gas resistance reduction structure of this embodiment, by generating vortices near the boundary between the first region and the second region, flow separation can be suppressed and gas resistance, especially pressure resistance, can be reduced.

[0072] The following describes the various components of the gas resistance reduction structure of this embodiment.

[0073] (a) First area In this embodiment, the first region has an uneven structure including convex and concave portions.

[0074] In the gas resistance reduction structure of this embodiment, it is preferable that the height H1 of the protrusion 5 is within a predetermined range.

[0075] As mentioned above, when an object is placed in a gas flow, the drag forces acting on the object include, for example, frictional resistance and pressure resistance, with pressure resistance arising from flow separation. Pressure resistance is a problem in moving objects such as automobiles, trains, and aircraft, as well as pipes such as ducts and gas pipes, wind turbines, and air conditioning equipment. The gas flow velocity through these objects is, for example, between 3 m / s and 250 m / s (between 10 km / h and 900 km / h).

[0076] In the gas resistance reduction structure of this embodiment, for example, when the flow velocity of the gas flowing through the object is within the above range, the height H1 of the protrusion 5 can be appropriately adjusted within a predetermined range to facilitate the generation of vortices V near the boundary between the first region 11 and the second region 12. As a result, flow separation from the surface of the gas resistance reduction structure can be suppressed, and pressure resistance can be reduced.

[0077] The height of the protrusion is preferably, for example, 1 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, and particularly preferably 50 μm or more. On the other hand, the height of the protrusion is preferably, for example, 1000 μm or less, more preferably 800 μm or less, even more preferably 500 μm or less, and particularly preferably 200 μm or less. Specifically, the height of the protrusion is preferably 1 μm or more and 1000 μm or less, more preferably 10 μm or more and 1000 μm or less, even more preferably 15 μm or more and 800 μm or less, even more preferably 20 μm or more and 500 μm or less, particularly preferably 20 μm or more and 200 μm or less, and most preferably 50 μm or more and 200 μm or less. As described above, in moving objects such as automobiles, trains, and aircraft, as well as pipes such as ducts and gas pipes, and objects such as wind turbines and air conditioning equipment, the flow velocity of the gas flowing through the object is approximately 3 m / s to 250 m / s, that is, approximately 10 km / h to 900 km / h. When the flow velocity is within the above range, vortices can be easily generated near the boundary between the first and second regions by appropriately adjusting the height of the protrusions within the above range. Also, for example, the speed of an automobile is approximately 10 km / h to 120 km / h, and in this case, the flow velocity of the air flowing through the automobile is approximately 3 m / s to 33 m / s, that is, approximately 10 km / h to 120 km / h. When the flow velocity is within the above range, vortices can be easily generated near the boundary between the first and second regions by appropriately adjusting the height of the protrusions within the range of 20 μm to 500 μm. Furthermore, by keeping the height of the protrusions within the above range, the benefit of reducing pressure resistance can be made greater than the increase in frictional resistance due to the first region.

[0078] In the flow around an object, the very thin layer on the object's surface is strongly affected by viscosity. This layer, strongly affected by viscosity, is called the boundary layer. The height of the protrusion is more preferably between 1 / 100 and 1 / 10 of the boundary layer thickness. Furthermore, since the boundary layer thickness decreases as the gas flow velocity increases, it is preferable that the height of the protrusion be lower within the above range as the gas flow velocity increases.

[0079] Here, the height H1 of the protrusion 5 refers to the height from the surface of the covering portion 4 opposite to the base 2 to the top of the protrusion 5, as shown in Figure 2(a), for example, that is, the height from the bottom of the recess 6 of the first region 11 to the top of the protrusion 5, as shown in Figure 4(c). Specifically, the height of the protrusion refers to the height from the bottom of the recess located between two adjacent protrusions to the top of the protrusion.

[0080] In the gas resistance reduction structure of this embodiment, it is preferable that the width W1 of the first region 11 in the first direction d1 is within a predetermined range.

[0081] As mentioned above, in the flow around an object, the very thin layer on the object's surface is strongly affected by viscosity. This layer, which is strongly affected by viscosity, is called the boundary layer.

[0082] Figures 7(a) to 7(c) are schematic diagrams showing the relationship between the width of the first region and the width of the second region in the first direction and the vortices generated near the boundary between the first and second regions in a gas resistance reduction structure. In Figures 7(a) to 7(c), δ represents the boundary layer thickness. For example, as shown in Figure 7(a), when the widths W1 of the first region 11 and W2 of the second region 12 in the first direction are large, large vortices V are generated near the boundary between the first region 11 and the second region 12, but the vortices V do not easily wrap around to the central part of the first region 11 and the central part of the second region 12. Also, as shown in Figure 7(c), for example, when the widths W1 of the first region 11 and W2 of the second region 12 in the first direction are small, the vortices V generated near the boundary between the first region 11 and the second region 12 are small, and the vortices V do not easily reach the outer edge of the boundary layer. In these cases, flow separation can be suppressed, but the effect is small.

[0083] In contrast, by setting the width W1 of the first region 11 and the width W2 of the second region 12 in the first direction d1 to a predetermined range, a large vortex V is generated near the boundary between the first region 11 and the second region 12, as shown in Figure 7(b), for example, and vortices V can be generated throughout the entire boundary layer.

[0084] The width of the first region in the first direction is preferably 0.2 mm or more, and more preferably 1 mm or more. On the other hand, the width of the first region in the first direction is preferably 50 mm or less, and more preferably 25 mm or less. Specifically, the width of the first region in the first direction is preferably 0.2 mm or more and 50 mm or less, and more preferably 1 mm or more and 25 mm or less. By having the width of the first region in the first direction within the above range, a large vortex V is generated near the boundary between the first region 11 and the second region 12, as shown in Figure 7(b), for example, and vortices V can be generated throughout the boundary layer.

[0085] It is more preferable that the width of the first region in the first direction is the same as the boundary layer thickness. Furthermore, since the boundary layer thickness decreases as the gas flow velocity increases, it is preferable that the width of the first region in the first direction is smaller within the above range as the gas flow velocity increases.

[0086] The width of the first region in the first direction may be the same as or different from the width of the second region in the first direction, as long as it is within the above range. In particular, it is preferable that the width of the first region in the first direction and the width of the second region in the first direction are the same. In this case, vortices can be generated more efficiently near the boundary between the first and second regions.

[0087] Here, the width W1 of the first region 11 in the first direction d1 refers to the distance from one end to the other end of the first region 11 in the first direction d1, as shown in Figures 4(a) and 4(b). Also, as shown in Figure 4(b), for example, if the surface of the gas resistance reduction structure 1A is flat, the width of the first region in the first direction refers to the width W1 of the first region 11 on the flat surface in the first direction d1. Also, as shown in Figure 8(b), for example, if the surface of the gas resistance reduction structure 1A is curved, the width of the first region in the first direction refers to the width W1 of the first region 11 on the curved surface in the first direction d1.

[0088] In the gas resistance reduction structure of this embodiment, it is preferable that the length L1 of the first region 11 in the second direction d2 is greater than or equal to a predetermined value. This allows for the efficient generation of vortices V near the boundary between the first region 11 and the second region 12.

[0089] The length of the first region in the second direction is 30 mm or more, preferably 50 mm or more. If the length of the first region in the second direction is too short, vortices will be less likely to be generated near the boundary between the first and second regions, potentially reducing the effect of suppressing flow separation. Furthermore, by having the length of the first region in the second direction within the above range, vortices can be efficiently generated near the boundary between the first and second regions. On the other hand, the length of the first region in the second direction is not particularly limited, but for example, 1000 mm or less is preferred, and 200 mm or less is more preferred. If the length of the first region in the second direction is too long, even if pressure resistance can be reduced, frictional resistance will increase, potentially reducing the effect of reducing gas resistance. Also, manufacturing costs may increase. Specifically, the length of the first region in the second direction is preferably 30 mm or more and 1000 mm or less, more preferably 50 mm or more and 1000 mm or less, and even more preferably 50 mm or more and 200 mm or less.

[0090] Here, the length L1 of the first region 11 in the second direction d2 refers to the distance from one end to the other end of the first region 11 in the second direction d2, as shown in Figure 4(a), for example. Specifically, the length of the first region in the second direction refers to the distance from the end of the protrusion located at one end of the first region in the second direction to the end of the protrusion located at the other end. Furthermore, if the surface of the gas resistance reduction structure 1A is flat, as shown in Figure 4(c), for example, the length of the first region in the second direction refers to the length L1 of the first region 11 on the flat surface in the second direction d2, as shown in Figure 4(a), for example. Furthermore, if the surface of the gas resistance reduction structure 1A is curved, as shown in Figure 8(a), for example, the length of the first region in the second direction refers to the length L1 of the first region 11 on the curved surface in the second direction d2.

[0091] Therefore, in this embodiment, the gas resistance reduction structure has a first region having an uneven structure including convex and concave portions on the resin layer side surface, and a second region adjacent to the first region. The length of the first region in the second direction is greater than or equal to a predetermined value, the height of the convex portions is within a predetermined range, and the width of the first region and the width of the second region in the first direction intersecting the second direction are within a predetermined range. As a result, vortices can be efficiently generated near the boundary between the first and second regions. Furthermore, by generating vortices near the boundary between the first and second regions, the vortices can be enlarged in the direction in which the boundary line between the first and second regions extends. Therefore, flow separation from the surface of the gas resistance reduction structure can be effectively suppressed. Thus, by applying the gas resistance reduction structure of this embodiment to the surface of an object, the pressure resistance among the gas resistances can be reduced. With the above configuration, the benefit of pressure resistance reduction can be made greater than the increase in frictional resistance due to the first region.

[0092] Furthermore, in the first region, the convex portion may protrude relative to the surface of the second region, and the concave portion may be recessed relative to the surface of the second region. Figures 5 and 10(b) show examples where the convex portion 5 of the first region 2 protrudes relative to the surface of the second region 12, and Figures 9 and 11(b) show examples where the concave portion 6 of the first region 2 is recessed relative to the surface of the second region 12.

[0093] In particular, it is preferable that the convex portion protrudes from the surface of the second region. In such a case, it is possible to easily generate vortices near the boundary between the first and second regions.

[0094] When the convex portion protrudes relative to the surface of the second region, typically, as shown in Figure 5, for example, the bottom of the concave portion 5 lies on the same plane as the surface of the second region 12. Conversely, when the concave portion is recessed relative to the surface of the second region, typically, as shown in Figure 9, for example, the top of the convex portion 5 lies on the same plane as the surface of the second region 12.

[0095] The first region has an uneven structure including convex and concave portions. In the first region, it is sufficient that the convex and concave portions are uniformly distributed.

[0096] The planar pattern shape of the convex and concave portions may be, for example, a regular pattern or a random pattern. In the case of a regular pattern, examples include line-shaped, dot-shaped, grid-shaped, and so on.

[0097] Examples of linear patterns include straight lines and wavy patterns such as sine waves and triangular waves. Among these, linear patterns are preferred.

[0098] Furthermore, in dot patterns, possible arrangements of the dots include, for example, parallel arrangements and staggered arrangements.

[0099] Examples of grid-like patterns include square grids, rectangular grids, triangular grids, hexagonal grids, rhombic grids, and parallelogram grids.

[0100] For example, Figure 5 shows an example where the pattern shape of the convex portion 5 in plan view is linear. Figure 9 shows an example where the pattern shape of the concave portion 6 in plan view is linear. Figures 10(a) and 10(b) show examples where the pattern shape of the convex portion 5 in plan view is dot-like and arranged in a staggered pattern. Note that Figure 10(b) is a cross-sectional view of Figure 10(a) along line AA. Figures 11(a) and 11(b) show examples where the pattern shape of the concave portion 6 in plan view is dot-like and arranged in a staggered pattern. Note that Figure 11(b) is a cross-sectional view of Figure 11(a) along line AA. Figure 12 also shows an example where the pattern shape of the convex portion 5 in plan view is grid-like and rectangular grid-like.

[0101] When the pattern shape of the convex and concave portions in plan view is linear, it is preferable that the longitudinal direction of the linear pattern of the convex and concave portions intersects with the second direction, and is more preferably substantially perpendicular to the second direction, that is, substantially parallel to the first direction. Specifically, when the pattern shape of the convex and concave portions is linear, it is preferable that the longitudinal direction of the linear pattern of the convex and concave portions intersects with the second direction, and is more preferably substantially perpendicular to the second direction, that is, substantially parallel to the first direction, as shown in Figure 4, for example. That is, it is preferable that the first region has convex and concave portions that extend linearly along the first direction. As will be described later, the gas resistance reduction structure of this embodiment is, for example, as shown in Figure 6(a), in the flow direction d of the gas F. F It is preferable that the first region 11 and the second region 12 are arranged and used so that their boundary lines are substantially parallel. That is, the gas resistance reduction structure of this embodiment is used in the flow direction d of the gas F, as shown in Figure 6(a), for example. F The first direction d1 is approximately perpendicular to the flow direction of the gas F, that is, the flow direction d F It is preferable to arrange and use the components such that the second direction d2 is substantially parallel to the first direction. Therefore, if the longitudinal direction of the linear patterns of the convex and concave portions intersects with the second direction, the longitudinal direction of the linear patterns of the convex and concave portions can be made to intersect with the gas flow direction. In such cases, vortices can be easily generated near the boundary between the first and second regions. Furthermore, if the longitudinal direction of the linear patterns of the convex and concave portions is substantially perpendicular to the second direction, the longitudinal direction of the linear patterns of the convex and concave portions can be made substantially perpendicular to the gas flow direction. In such cases, vortices can be further easily generated near the boundary between the first and second regions.

[0102] Furthermore, when the longitudinal direction of the linear patterns of the convex and concave portions intersects with the second direction, the angle between the longitudinal direction of the linear patterns and the second direction is preferably, for example, 45° to 135°. Similarly, when the longitudinal direction of the linear patterns of the convex and concave portions intersects with the second direction, the angle between the longitudinal direction of the linear patterns and the second direction is preferably, for example, 45° to 135°.

[0103] In other words, when the longitudinal direction of the linear patterns of the convex and concave portions intersects with the gas flow direction, the angle between the longitudinal direction of the linear patterns and the gas flow direction is preferably, for example, 45° to 135°. Similarly, when the longitudinal direction of the linear patterns of the convex and concave portions intersects with the gas flow direction, the angle between the longitudinal direction of the linear patterns and the gas flow direction is preferably, for example, 45° to 135°.

[0104] Here, the longitudinal direction of the linear patterns of the convex and concave portions is said to be approximately parallel to the first direction if the angle between the longitudinal direction of the linear patterns and the first direction is between -5° and 5°. Similarly, the longitudinal direction of the linear patterns of the convex and concave portions is said to be approximately parallel to the first direction if the angle between the longitudinal direction of the linear patterns and the first direction is between -5° and 5°.

[0105] Furthermore, the longitudinal direction of the linear patterns of the convex and concave portions is said to be approximately perpendicular to the gas flow direction if the angle between the longitudinal direction of the linear patterns and the gas flow direction is 85° or more and 95° or less. Similarly, the longitudinal direction of the linear patterns of the convex and concave portions is said to be approximately perpendicular to the gas flow direction if the angle between the longitudinal direction of the linear patterns and the gas flow direction is 85° or more and 95° or less.

[0106] Note that the longitudinal direction of a linear pattern refers to the direction in which the linear pattern extends, for example, in the case of a straight line pattern, or the direction in which the wavy line pattern extends, in the case of a wavy line pattern.

[0107] Therefore, the angle between the longitudinal direction of the linear pattern and the second direction is preferably, for example, 45° or more and 135° or less, more preferably 80° or more and 100° or less, and even more preferably 85° or more and 95° or less. Also, if the line is straight, the angle between the longitudinal direction of the straight pattern and the second direction is preferably, for example, 45° or more and 135° or less, more preferably 80° or more and 100° or less, and even more preferably 85° or more and 95° or less.

[0108] Furthermore, the angle between the longitudinal direction of the linear pattern and the gas flow direction is preferably, for example, 45° to 135°, more preferably 80° to 100°, and even more preferably 85° to 95°. Also, if the line is straight, the angle between the longitudinal direction of the straight pattern and the gas flow direction is preferably, for example, 45° to 135°, more preferably 80° to 100°, and even more preferably 85° to 95°.

[0109] When the plan view pattern shape of the convex and concave portions is linear, the width of the linear convex portion is preferably, for example, 1 to 2 times the height of the convex portion. Specifically, when the pattern shape of the convex portion is straight, the width of the straight convex portion is preferably 1 to 2 times the height of the convex portion. If the width of the linear convex portion is too small, it may be difficult to form the first region. Also, if the width of the linear convex portion is too large, it may be difficult to generate sufficient vortices near the boundary between the first and second regions.

[0110] Here, the width of the linear protrusion is the width W3 of the protrusion 5, as shown in Figures 13(a) to 13(i), and refers to the largest width among the widths of the protrusion 5.

[0111] Furthermore, if the pattern shape of the convex portion in plan view is linear, the width of the linear recess is preferably, for example, 1 or more times the height of the convex portion, and more preferably 4 or more times. On the other hand, the width of the linear recess is preferably, for example, 12 times or less the height of the convex portion, and more preferably 10 times or less. Furthermore, the width of the linear recess is preferably, for example, 1 to 12 times the height of the convex portion, and more preferably 4 to 10 times. Specifically, if the pattern shape of the convex portion in plan view is linear, the width of the linear recess is preferably, for example, 1 or more times the height of the convex portion, and more preferably 4 or more times. On the other hand, the width of the linear recess is preferably, for example, 12 times or less the height of the convex portion, and more preferably 10 times or less. Furthermore, the width of the linear recess is preferably, for example, 1 to 12 times the height of the convex portion, and more preferably 4 to 10 times. If the width of the linear recesses is too small, the density of the convex areas will be high, making it difficult to generate sufficient vortices near the boundary between the first and second regions. Conversely, if the width of the linear recesses is too large, the density of the convex areas will be low, also making it difficult to generate sufficient vortices near the boundary between the first and second regions. Furthermore, if the width of the linear recesses is between 4 and 10 times the height of the convex areas, vortices can be generated near the boundary between the first and second regions, effectively suppressing flow separation.

[0112] Here, the width of the linear recess is the width W4 of the recess 6, as shown in Figures 13(a) to 13(i), and refers to the smallest width of the recess 6. For example, in Figure 13(d), the width of the recess 6 is zero.

[0113] Furthermore, when the pattern shape of the convex and concave portions in plan view is linear, the pitch of the linear convex portions is preferably, for example, 2 times or more the height of the convex portion, and more preferably 5 times or more. On the other hand, the pitch of the linear convex portions is preferably, for example, 14 times or less the height of the convex portion, and more preferably 12 times or less. Furthermore, the pitch of the linear convex portions is preferably, for example, 2 times or more and 14 times or less the height of the convex portion, and more preferably 5 times or more 12 times or less. Specifically, when the pattern shape of the convex portion in plan view is linear, the pitch of the linear convex portions is preferably, for example, 2 times or more the height of the convex portion, and more preferably 5 times or more. On the other hand, the pitch of the linear convex portions is preferably, for example, 14 times or less the height of the convex portion, and more preferably 12 times or less. Furthermore, the pitch of the linear convex portions is preferably, for example, 2 times or more and 14 times or less the height of the convex portion, and more preferably 5 times or more 12 times or less. If the pitch of the linear protrusions is too small, the density of the protrusions will be high, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. Conversely, if the pitch of the linear protrusions is too large, the density of the protrusions will be low, which may also make it difficult to generate sufficient vortices near the boundary between the first and second regions.

[0114] Here, the pitch of the linear protrusions is the pitch P1 of the protrusions 5, as shown in Figures 13(a) to 13(i), and refers to the distance between adjacent protrusions 5.

[0115] Furthermore, if the pattern shape of the convex portion in plan view is dot-like, the size of the dot-like convex portion in plan view is preferably, for example, 1 to 2 times the height of the convex portion. If the size of the dot-like convex portion is too small, it may be difficult to form the first region. Also, if the size of the dot-like convex portion is too large, it may be difficult to generate sufficient vortices near the boundary between the first and second regions.

[0116] Furthermore, if the pattern shape of the recess in plan view is dot-shaped, the size of the dot-shaped recess in plan view is preferably 1 or more times the height of the convex portion, and more preferably 4 or more times. On the other hand, the size of the dot-shaped recess in plan view is preferably 12 times or less the height of the convex portion, and more preferably 10 times or less. Furthermore, the size of the dot-shaped recess in plan view is preferably 1 to 12 times the height of the convex portion, and more preferably 4 to 10 times. If the size of the dot-shaped recess is too small, the density of the convex portion becomes high, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. Also, if the size of the dot-shaped recess is too large, the density of the convex portion becomes low, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. Furthermore, if the size of the dot-shaped recess is 4 to 10 times the height of the convex portion, vortices can be generated near the boundary between the first and second regions, and flow separation can be effectively suppressed.

[0117] Here, the size of a dot-shaped protrusion in plan view refers to, for example, the diameter if the plan view shape of the protrusion is circular, the major axis if the plan view shape of the protrusion is elliptical, and the length of the diagonal if the plan view shape of the protrusion is rectangular. Similarly, the size of a dot-shaped recess in plan view refers to, for example, the diameter if the plan view shape of the recess is circular, the major axis if the plan view shape of the recess is elliptical, and the length of the diagonal if the plan view shape of the recess is rectangular.

[0118] Furthermore, if the pattern shape of the convex or concave portion in plan view is dot-shaped, the pitch of the dot-shaped convex or concave portion is preferably, for example, 2 times or more the height of the convex portion, and more preferably 5 times or more. On the other hand, the pitch of the dot-shaped convex or concave portion is preferably, for example, 14 times or less the height of the convex portion, and more preferably 12 times or less. Furthermore, the pitch of the dot-shaped convex or concave portion is preferably, for example, 2 times or more and 14 times or less the height of the convex portion, and more preferably 5 times or more and 12 times or less. If the pitch of the dot-shaped convex or concave portion is too small, the density of the convex portion will be high, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. Also, if the pitch of the dot-shaped convex or concave portion is too large, the density of the convex portion will be low, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions.

[0119] Here, the pitch of the dot-shaped protrusions refers to the distance between adjacent protrusions. Similarly, the pitch of the dot-shaped recesses refers to the distance between adjacent recesses.

[0120] Furthermore, if the pattern shape of the convex portion in plan view is grid-like, the width of the grid-like convex portion is preferably, for example, 1 to 2 times the height of the convex portion. If the width of the grid-like convex portion is too small, it may be difficult to form the first region. Also, if the width of the grid-like convex portion is too large, it may be difficult to generate sufficient vortices near the boundary between the first and second regions.

[0121] Furthermore, if the pattern shape of the convex portion in plan view is grid-like, the spacing between the grid-like convex portions is preferably, for example, 1 or more times the height of the convex portion, and more preferably 4 or more times. On the other hand, the spacing between the grid-like convex portions is preferably, for example, 12 times or less the height of the convex portion, and more preferably 10 times or less. Furthermore, the spacing between the grid-like convex portions is preferably, for example, 1 to 12 times the height of the convex portion, and more preferably 4 to 10 times. If the spacing between the grid-like convex portions is too small, the density of the convex portions will be high, and it may become difficult to generate sufficient vortices near the boundary between the first and second regions. Conversely, if the spacing between the grid-like convex portions is too large, the density of the convex portions will be low, and it may become difficult to generate sufficient vortices near the boundary between the first and second regions. Furthermore, when the spacing between the grid-like convex portions is 4 to 10 times the height of the convex portion, vortices can be generated near the boundary between the first and second regions, and flow separation can be effectively suppressed.

[0122] Furthermore, if the pattern shape of the recess in plan view is grid-like, the width of the grid-like recess is preferably 1 or more times the height of the convex portion, and more preferably 4 or more times. On the other hand, the width of the grid-like recess is preferably 12 times or less the height of the convex portion, and more preferably 10 times or less. Furthermore, the width of the grid-like recess is preferably 1 to 12 times the height of the convex portion, and more preferably 4 to 10 times. If the width of the grid-like recess is too small, the density of the convex portion becomes high, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. Also, if the width of the grid-like recess is too large, the density of the convex portion becomes low, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. Furthermore, if the width of the grid-like recess is 4 to 10 times the height of the convex portion, vortices can be generated near the boundary between the first and second regions, and flow separation can be effectively suppressed.

[0123] Furthermore, if the pattern shape of the convex or concave portion in plan view is grid-like, the pitch of the grid-like convex or concave portion is preferably, for example, 2 times or more, and more preferably 5 times or more, the height of the convex portion. On the other hand, the pitch of the grid-like convex or concave portion is preferably, for example, 14 times or less, and more preferably 12 times or less, the height of the convex portion. Furthermore, the pitch of the grid-like convex or concave portion is preferably, for example, 2 times or more and 14 times or less, and more preferably 5 times or more and 12 times or less, the height of the convex portion. If the pitch of the grid-like convex or concave portion is too small, the density of the convex portion becomes high, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. Also, if the pitch of the grid-like convex or concave portion is too large, the density of the convex portion becomes low, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions.

[0124] The dimensions of the first region, the convex portion, and the concave portion are measured using a laser displacement sensor.

[0125] Furthermore, the cross-sectional shapes of the convex and concave portions are not particularly limited and include, for example, rectangular, trapezoidal, triangular, semicircular, and semielliptical shapes. For example, Figure 13(a) shows an example where the cross-sectional shapes of the convex portion 5 and concave portion 6 are rectangular, Figure 13(b) shows an example where the cross-sectional shapes of the convex portion 5 and concave portion 6 are trapezoidal, Figures 13(c) to 13(e) show an example where the cross-sectional shape of the convex portion 5 is triangular, Figure 13(f) shows an example where the cross-sectional shape of the convex portion 5 is semielliptical, Figures 13(g) to 13(h) show an example where the cross-sectional shape of the concave portion 6 is triangular, and Figure 13(i) shows an example where the cross-sectional shape of the concave portion 6 is semicircular.

[0126] In particular, the cross-sectional shape of the convex or concave portion is preferably trapezoidal, semicircular, or semielliptical. With these shapes, the formation of the first region is easy, and the durability of the first region can be increased.

[0127] Furthermore, the convex portion is preferably the part extending from the top of the convex portion to the side, and the part connected to the top has a rounded shape, that is, a curved surface.

[0128] Figures 14(a) and 14(b) are schematic cross-sectional views illustrating the protrusions in the gas resistance reduction structure of this embodiment. Figure 14(a) is a schematic cross-sectional view of the protrusions in the first direction, and Figure 14(b) is a schematic cross-sectional view of the protrusions in the second direction.

[0129] As illustrated in Figures 14(a) and 14(b), the convex portion 5 has a rounded shape in the portion 5R that connects to the top 5T, from the top 5T to the side portion 5S. In other words, the convex portion 5 has a curved surface in the portion 5R. When the convex portion 5 has a rounded shape in the portion 5R in this way, the scratch resistance and wear resistance of the convex portion 5 can be improved. Furthermore, frictional resistance at the boundary side portion 5R of the convex portion 5 can be suppressed against vortices generated at the boundary between the first region and the second region. Therefore, it is expected that the effect of vortices, that is, the effect of suppressing gas separation from the surface, will be further enhanced.

[0130] In the above-mentioned portion of the protrusion, the radius of curvature of the curved surface is preferably, for example, 10 μm or more, and more preferably 20 μm or more. On the other hand, the radius of curvature of the curved surface is preferably, for example, 400 μm or less, and more preferably 200 μm or less. Specifically, the radius of curvature of the curved surface is preferably 10 μm or more and 400 μm or less, and more preferably 20 μm or more and 200 μm or less. If the radius of curvature of the curved surface is excessively small, it may become difficult to improve the scratch resistance and wear resistance of the gas resistance reduction structure. Also, if the radius of curvature of the curved surface is excessively large, the height of the protrusion must also be increased. If the height of the protrusion exceeds a size suitable for reducing gas resistance, the gas resistance reduction effect may become insufficient.

[0131] Here, the radius of curvature of the curved surface at the above-mentioned portion of the convex portion refers to the radius of curvature of the curve at the above-mentioned portion of the convex portion in a cross-section in the thickness direction of the gas resistance reduction structure. For example, Figure 14(a) is a cross-sectional view of the gas resistance reduction structure in the thickness direction, and is a cross-sectional view of the convex portion in the first direction. Also, for example, Figure 14(b) is a cross-sectional view of the gas resistance reduction structure in the thickness direction, and is a cross-sectional view of the convex portion in the second direction. In Figures 14(a) and 14(b), the radius of curvature of the curved surface at the above-mentioned portion 5R of the convex portion 5 is the radius of curvature r1 of the curve at the above-mentioned portion 5R of the convex portion 5.

[0132] Furthermore, in the first region, the number of protrusions is multiple and is appropriately set to satisfy the dimensions of the first region, protrusions, and recesses described above. Specifically, the number of protrusions in the first region is 14 or more, may be 83 or more, or may be 181 or more. On the other hand, the number of protrusions is, for example, 1500 or less, may be 714 or less, or may be 200 or less. Specifically, the number of protrusions is 14 or more and 1500 or less, may be 83 or more and 714 or less, or may be 181 or more and 200 or less. By having the number of protrusions within the above range, the reduction of pressure resistance can be maximized and the increase in frictional resistance can be minimized. This makes it possible to maximize the effect of reducing air resistance.

[0133] The plan view shape of the first region is not particularly limited as long as it is a shape that can generate a vortex near the boundary between the first region and the second region, and examples include a rectangular shape and an arc shape. For example, Figure 4(a) is an example in which the plan view shape of the first region 11 is rectangular, and Figure 15 is an example in which the plan view shape of the first region 11 is rectangular and an arc shape. Among these, the plan view shape of the first region is preferably rectangular.

[0134] (b) Second area In this embodiment, the second region is adjacent to the first region.

[0135] The width of the second region in the first direction is 0.2 mm or more, preferably 1 mm or more. On the other hand, the width of the second region in the first direction is 50 mm or less, preferably 25 mm or less. Specifically, the width of the second region in the first direction is preferably 0.2 mm or more and 50 mm or less, and 1 mm or more and 25 mm or less. By having the width of the second region in the first direction within the above range, a large vortex V is generated near the boundary between the first region 11 and the second region 12, as shown in Figure 7(b), for example, and vortex V can be generated throughout the boundary layer.

[0136] It is more preferable that the width of the second region in the first direction is the same as the boundary layer thickness. Furthermore, since the boundary layer thickness decreases as the gas flow velocity increases, it is preferable that the width of the second region in the first direction is smaller within the above range as the gas flow velocity increases.

[0137] Here, the width W2 of the second region 12 in the first direction d1 refers to the distance from one end to the other end of the second region 12 in the first direction d1, in a second region 12 located between adjacent first regions 11, as shown in Figures 4(a) and 4(b). Furthermore, if the surface of the gas resistance reduction structure 1A is flat, as shown in Figure 4(b), the width of the second region in the first direction refers to the width W2 of the second region 12 on the flat surface in the first direction d1. Furthermore, if the surface of the gas resistance reduction structure 1A is curved, as shown in Figure 8(b), the width of the second region in the first direction refers to the width W2 of the second region 12 on the curved surface in the first direction d1.

[0138] (c) Area 1 and Area 2 The gas resistance reduction structure of this embodiment has a first region and a second region adjacent to the first region on the resin layer side, and the first and second regions extend in a strip shape in a second direction intersecting the first direction.

[0139] In this embodiment, since vortices are generated near the boundary between the first and second regions, it is sufficient to have at least one first region and at least one second region. In particular, it is preferable that the first and second regions are arranged alternately in the first direction.

[0140] When the first and second regions are arranged alternately in the first direction, for example, the first and second regions may be arranged alternately parallel to each other in the first direction, or alternately non-parallel to each other in the first direction. For example, Figure 4(a) shows an example where the first region 11 and the second region 12 are arranged alternately parallel to each other in the first direction d1, and Figure 15 shows an example where the first region 11 and the second region 12 are arranged alternately non-parallel to each other in the first direction d1. For example, when applying a gas resistance reduction structure to the three-dimensional curved surface of an object, the first and second regions may be arranged alternately non-parallel to each other in the first direction. Among these, it is preferable that the first and second regions are arranged alternately parallel to each other in the first direction.

[0141] (d) First direction and second direction The first direction intersects the second direction. In particular, it is preferable that the first direction is perpendicular to the second direction. The angle between the first direction and the second direction is preferably 85° or more and 95° or less, and more preferably 90°.

[0142] The gas resistance reduction structure of this embodiment is preferably used in such a configuration that the angle between the boundary line between the first and second regions and the direction of gas flow is, for example, 0°±15°, that is, -15° or more and 15° or less. In other words, the gas resistance reduction structure of this embodiment is preferably used in such a configuration that the angle between the second direction and the direction of gas flow is, for example, 0°±15°, that is, -15° or more and 15° or less. To put it another way, the gas resistance reduction structure of this embodiment is preferably used in such a configuration that the angle between the first direction and the direction of gas flow is, for example, 90°±15°, that is, 75° or more and 105° or less.

[0143] In particular, the gas resistance reduction structure of this embodiment, as shown in Figure 6(a), for example, has a boundary line between the first region 11 and the second region 12 in the flow direction d of the gas F. F It is more preferable that the gas resistance reduction structure of this embodiment be positioned and used so as to be substantially parallel to the flow direction d of the gas F, as shown in Figure 6(a). F It is more preferable that the second direction d2 be approximately parallel to the first direction d1, that is, that the first direction d1 be approximately perpendicular to the second direction d1. This makes it easier to generate vortices near the boundary between the first and second regions, and suppresses flow separation.

[0144] Here, the boundary line between the first and second regions is said to be approximately parallel to the gas flow direction if the angle between the boundary line between the first and second regions and the gas flow direction is between -5° and 5°. The second direction is said to be approximately parallel to the gas flow direction if the angle between the second direction and the gas flow direction is between -5° and 5°. The first direction is said to be approximately perpendicular to the gas flow direction if the angle between the first direction and the gas flow direction is between 85° and 95°.

[0145] Therefore, it is preferable that the gas resistance reduction structure of this embodiment is arranged and used such that the angle between the second direction and the gas flow direction is, for example, -15° or more and 15° or less, more particularly -10° or more and 10° or less, and especially -5° or more and 5° or less.

[0146] In other words, the gas resistance reduction structure of this embodiment is preferably used in such a configuration that the angle between the first direction and the gas flow direction is, for example, 75° to 105°, more particularly 80° to 100°, and especially 85° to 95°.

[0147] If the gas resistance reduction structure of this embodiment is a film, as will be described later, it is preferable that the elongation in the first direction is smaller than the elongation in the second direction in the film-like gas resistance reduction structure. In other words, it is more preferable that the elongation in the first direction is smaller than the elongation in any other direction in the film-like gas resistance reduction structure.

[0148] When a film-like gas resistance reducing structure possesses such physical properties, it can conform to the surface of an object and, even when stretched in a second direction, prevent damage to the uneven structure constituting the gas resistance reducing structure. Therefore, by applying the film-like gas resistance reducing structure to the surface of an object, especially the surface of an object with a curved surface, gas resistance can be effectively reduced.

[0149] For example, as shown in Figures 4 and 5, if the protrusion 5 has a shape that extends linearly along the first direction d1, it is preferable that the film-like gas resistance reducing structure has little elongation in the first direction d1. If the protrusion 5 is made of a material that does not have flexibility with respect to elongation, when the film-like gas resistance reducing structure is stretched in the first direction d1, the protrusion 5 may not be able to withstand the stretching, and collapse or peeling may occur.

[0150] On the other hand, in a direction intersecting the first direction d1, for example the second direction d2, even if the film-like gas resistance reducing structure is stretched in the second direction d2, the recesses 6 between the multiple arranged protrusions 5 also stretch. Therefore, compared to when it is stretched in the first direction d1, the possibility of collapse or peeling of the protrusions 5 is lower.

[0151] Therefore, in a film-like gas resistance reducing structure, it is preferable that the elongation in the first direction is smaller than the elongation in the second direction.

[0152] Furthermore, many trucks, buses, and trains, for example, have corners that connect a planar front section, which is roughly perpendicular to the ground, to a planar side section, which is also roughly perpendicular to the ground, and these corners usually have a small radius of curvature. In sections including such corners, air, which is a gas, flows from the front section to the side section. Therefore, as described above, it is preferable to attach the film-like gas resistance reduction structure so that the second direction is roughly parallel to the direction of gas flow. For example, the film-like gas resistance reduction structure is attached so that the second direction is in the direction from the front section to the side section along the curved surface of the corner with a small radius of curvature. For example, Figure 16 shows an example of applying the film-like gas resistance reduction structure 1A to the above-mentioned location on truck 50A.

[0153] In this case, the film-like gas resistance reducing structure may be stretched in a second direction along a curved surface with a small radius of curvature at its corners. Therefore, from the viewpoint of facilitating application, it is preferable that the film-like gas resistance reducing structure has a certain degree of elongation in the second direction.

[0154] On the other hand, in the above case, the film-like gas resistance reducing structure is not stretched in the first direction, so a particularly large elongation is not required.

[0155] Therefore, when a film-like gas resistance reducing structure is applied to the surface of an object with a curved surface, the gas resistance can be effectively reduced because the elongation in the first direction is smaller than the elongation in the second direction.

[0156] Furthermore, in the manufacturing method of the film-like gas resistance reducing structure, a cylindrical plate may be used to form the first region. For example, a cylindrical plate can be used in the photopolymerization method or embossing described above. Using a cylindrical plate is preferable for mass production.

[0157] In particular, as shown in Figures 4 and 5, when the protrusion 5 has a shape that extends linearly along the first direction d1, it is preferable to form the protrusion 5 using a cylindrical plate that rotates along the first direction d1. By making the rotation direction of the cylindrical plate the same as the longitudinal direction of the protrusion 5, that is, the same as the first direction, it is possible to suppress the destruction of the protrusion 5 when it is released from the cylindrical plate. In other words, it is possible to reduce the formation of defective protrusions 5.

[0158] For example, as shown in Figure 17, when forming a protrusion 5 having a linear shape extending along the first direction d1 using a cylindrical plate 110A that rotates along the second direction d2, the direction in which the film flows due to the rotation of the cylindrical plate 110A (second direction d2) is different from the longitudinal direction of the protrusion 5 (first direction d1). Therefore, the resistance that the formed protrusion 5 receives from the cylindrical plate 110A when it is released from the mold is large. Consequently, there is a possibility that the protrusion 5 may be destroyed by the cylindrical plate 110A. Note that in the example shown in Figure 17, the film-like gas resistance reduction structure 1A has a long shape along the second direction d2.

[0159] On the other hand, as shown in Figure 18, when a cylindrical plate 110B that rotates along a first direction d1 is used to form a protrusion 5 that extends linearly along the first direction d1, the direction in which the film flows due to the rotation of the cylindrical plate 110B is the same as the longitudinal direction (first direction d1) of the protrusion 5. Therefore, the resistance that the formed protrusion 5 receives from the cylindrical plate 110B when it is released from the mold is small. Thus, the destruction of the protrusion 5 by the cylindrical plate 110B is suppressed. In the example shown in Figure 18, the film-like gas resistance reducing structure 1A has a long shape along the first direction d1.

[0160] Therefore, the film-like gas resistance reducing structure has a long form along the first direction, and by using a cylindrical plate that rotates along the first direction to form the protrusions, defects in the formation of the protrusions can be suppressed.

[0161] When a convex portion is formed using a cylindrical plate that rotates along the first direction, as described above, the film-like gas resistance reducing structure has a long form along the first direction. Generally, it is preferable to mass-produce films using a roll-to-roll method. Therefore, it is preferable for the film-like gas resistance reducing structure to be in a rolled form for ease of manufacturing and transportation. Furthermore, it is preferable that the winding direction is in a direction that matches the characteristics of the film-like gas resistance reducing structure. In order to prevent adverse effects from tensile forces acting on the film-like gas resistance reducing structure, it is preferable that the elongation in the winding direction of the film-like gas resistance reducing structure be small.

[0162] For example, the roll body 100A shown in Figure 19 is a roll body in which a film-like gas resistance reduction structure 1A is wound around a winding core 101. In the roll body 100A, the film-like gas resistance reduction structure 1A is wound along a first direction d1. In the film-like gas resistance reduction structure, if the elongation in the first direction d1 on the first surface is smaller than the elongation in a direction intersecting the first direction d1 on the first surface, for example, in a second direction d2, then when forming the roll body 100A, winding the film-like gas resistance reduction structure 1A along the first direction d1 can suppress excessive elongation of the film-like gas resistance reduction structure 1A. In the example shown in Figure 19, the film-like gas resistance reduction structure 1A has a long form along the first direction d1.

[0163] On the other hand, for example, the roll body 100B shown in Figure 20 is a roll body in which a film-like gas resistance reduction structure 1A is wound along the second direction d2. In the film-like gas resistance reduction structure, if the elongation in the first direction d1 on the first surface is smaller than the elongation in the direction intersecting the first direction d1 on the first surface, for example, the elongation in the second direction d2, then winding the film-like gas resistance reduction structure 1A along the second direction d2 may cause the film-like gas resistance reduction structure 1A to stretch excessively. In the example shown in Figure 20, the film-like gas resistance reduction structure 1A has a long form along the second direction d2.

[0164] Furthermore, because the film-like gas resistance reducing structure 1A is held in the state of the roll body 100B, that is, because the film-like gas resistance reducing structure 1A is held in a state of being excessively stretched in the second direction d2, there is a possibility that the stretch in the second direction d2 has already decreased in the film-like gas resistance reducing structure 1A that has been unwound from the roll body 100B. In the case of the film-like gas resistance reducing structure 1A with reduced stretch in the second direction d2, the effect when applied to the corners connecting the front and side parts of trucks, buses, trains, etc., as described above will be reduced.

[0165] Therefore, when a film-like gas resistance reducing structure is rolled up, if the elongation in the first direction is less than the elongation in the second direction, excessive elongation of the film-like gas resistance reducing structure during winding can be suppressed by winding the film-like gas resistance reducing structure along the first direction.

[0166] Therefore, it is preferable that the film-like gas resistance reducing structure has a long shape along the first direction, and that the elongation in the first direction is smaller than the elongation in the second direction. This suppresses defects in the formation of protrusions when forming them using a cylindrical plate, and also suppresses excessive elongation of the film during winding.

[0167] Here, the term "elongation" refers to the amount of deformation when a tensile force is applied to a material. Specifically, if the original length is L and the amount of deformation is ΔL, then ΔL is called "elongation."

[0168] For example, the relative magnitudes of the "elongation" of a film-like gas resistance-reducing structure in each direction can be compared by performing tensile tests using a tensile testing machine or similar device, applying the same tensile force and speed in each direction, and then comparing the magnitudes of the resulting deformation. In this comparison of elongation, it is not necessary to break the sample (the film-like gas resistance-reducing structure); comparing the magnitudes of deformation due to elongation before breakage is sufficient.

[0169] Furthermore, the magnitude of the "elongation" in each direction of the film-like gas resistance reducing structure may be evaluated by the tensile modulus. The tensile modulus is measured in accordance with JIS K7161-1:2014 (Plastics - Determination of tensile properties - Area 1: General rules) and JIS K7127:1999 (Plastics - Test methods for tensile properties - Part 3: Measurement conditions for films and sheets). In this case, for example, the tensile modulus in each direction is measured by performing a tensile test on the sample (film-like gas resistance reducing structure) in each direction using a tensile testing machine. The conditions for the tensile test are shown below. As a tensile testing machine, for example, the "Instron 5565" manufactured by Instron Japan Co., Ltd. is used. The tensile modulus is defined as the slope between two points on the stress / strain curve at strains of 0.05% and 0.25%.

[0170] <Measurement conditions> • Test specimen: 150mm in length, 25mm in width ·Distance between gauge lines: 75mm • Tensile speed: 50 mm / min • Load cell: 1kN • Number of measurements: 3

[0171] In order to create such a film-like gas resistance reducing structure, it is preferable that the elongation in a specific direction is smaller than the elongation in a direction intersecting that specific direction, even in the substrate constituting the film-like gas resistance reducing structure. An example of such a substrate is a uniaxially stretched resin film. For example, in a uniaxially stretched resin film, the elongation in the stretching direction is smaller than the elongation in a direction intersecting the stretching direction.

[0172] Furthermore, depending on the material of the resin film, whether uniaxially oriented or biaxially oriented, the elongation in the MD (Machine Direction) direction is usually smaller than the elongation in the TD (Transverse Direction) direction during the manufacturing process. For example, biaxially oriented PET (polyethylene terephthalate) film is one such resin film. Therefore, even biaxially oriented resin films can be used if, for example, the elongation in the MD direction is smaller than the elongation in the TD direction, or if the elongation in one direction is smaller than the elongation in the other direction intersecting that direction.

[0173] (2) Second Embodiment The second embodiment of the gas resistance reduction structure in this disclosure has an uneven structure including protrusions and recesses on the entire surface of the resin layer side.

[0174] Figures 21(a) and 21(b) are schematic plan view and cross-sectional view, respectively, showing an example of a gas resistance reduction structure according to this embodiment. Figure 21(b) is a cross-sectional view taken along line AA of Figure 21(a). As shown in Figures 21(a) and 21(b), the gas resistance reduction structure 1B has an uneven structure 7 including protrusions 5 and recesses 6 on the entire surface of the resin layer 3 side.

[0175] In the gas resistance reduction structure of this embodiment, the uneven structure generates small vortices, thereby suppressing flow separation and preventing the generation of large vortices, particularly Karman vortices. As a result, pressure resistance, which is a component of gas resistance, can be reduced.

[0176] The following describes the various components of the gas resistance reduction structure of this embodiment.

[0177] The height of the protrusion is preferably, for example, 1 μm or more, but may be 10 μm or more, 20 μm or more, or 50 μm or more. On the other hand, the height of the protrusion is, for example, 20 mm or less, or 15 mm or less. Specifically, the height of the protrusion is 1 μm or more and 20 mm or less, may be 10 μm or more and 20 mm or less, may be 20 μm or more and 15 mm or less, or may be 50 μm or more and 15 mm or less.

[0178] Here, the height H1 of the protrusion 5 refers to the height from the surface of the covering portion 4 opposite to the base 2, as shown in Figure 2(a), that is, the height from the bottom of the recess 6 to the top of the protrusion 5, as shown in Figure 21(b).

[0179] The gas resistance reduction structure of this embodiment has an uneven structure including protrusions and recesses on the entire surface of the resin layer side. On the surface of the resin layer on the protrusion side, it is sufficient that the protrusions and recesses are uniformly distributed.

[0180] The planar pattern shape of the convex and concave portions may be, for example, a regular pattern or a random pattern. In the case of a regular pattern, examples include line-shaped, dot-shaped, grid-shaped, and so on.

[0181] Examples of linear patterns include straight lines, sine waves, triangular waves, and other wave-like patterns.

[0182] Furthermore, in a dot pattern, it is preferable that the arrangement of the dots is such that the gas flow strikes the convex parts, regardless of the direction of the gas flow. An example of such a dot arrangement is a staggered arrangement.

[0183] Examples of grid-like patterns include square grids, rectangular grids, triangular grids, hexagonal grids, rhombic grids, and parallelogram grids.

[0184] For example, Figures 23(a) and 23(b) show examples where the pattern shape of the convex portion 5 in plan view is linear. Note that Figure 23(b) is a cross-sectional view of Figure 23(a) along line AA. Figures 21(a) and 21(b) show examples where the pattern shape of the convex portion 5 in plan view is dot-like and arranged in a staggered pattern. Figures 22(a) and 22(b) show examples where the pattern shape of the concave portion 6 in plan view is dot-like and arranged in a staggered pattern. Note that Figure 22(b) is a cross-sectional view of Figure 22(a) along line AA.

[0185] If the pattern shape of the convex portion in plan view is linear, the width of the linear convex portion may be, for example, 1 μm or more, 10 μm or more, or 20 μm or more. On the other hand, the width of the linear convex portion and concave portion may be, for example, 20 mm or less, or 15 mm or less. Specifically, the width of the linear convex portion and concave portion may be 1 μm or more and 20 mm or less, 10 μm or more and 20 mm or less, or 20 μm or more and 15 mm or less.

[0186] Here, the width of the linear protrusion is the width W11 of the protrusion 5, as shown in Figures 24(a) to 24(i), and refers to the largest width among the protrusions 5.

[0187] Furthermore, if the pattern shape of the recess in plan view is linear, the width of the linear recess is the same as the width of the linear protrusion described above.

[0188] Here, the width of the linear recess is the width W12 of the recess 6, as shown in Figures 24(a) to 24(i), and refers to the smallest width of the recess 6. For example, in Figure 24(d), the width of the recess 6 is zero.

[0189] Furthermore, if the pattern shape of the convex portion in plan view is linear, the pitch of the linear convex portion is set appropriately so that the width of the linear convex portion and the width of the linear concave portion are within the above range. The pitch of the linear convex portion is, for example, the pitch P11 of the convex portion 5 as shown in Figures 24(a) to 24(i), and refers to the distance between adjacent convex portions 5.

[0190] Furthermore, if the pattern shape of the convex portion in plan view is dot-like, the size of the dot-like convex portion in plan view is, for example, 1 μm or more, may be 10 μm or more, or may be 20 μm or more. On the other hand, the size of the dot-like convex portion in plan view is, for example, 20 mm or less, or may be 15 mm or less. Specifically, the size of the dot-like convex portion in plan view is 1 μm or more and 20 mm or less, may be 10 μm or more and 20 mm or less, or may be 20 μm or more and 15 mm or less.

[0191] Here, the size of the dot-shaped protrusion in plan view refers to, for example, the diameter if the plan view shape of the protrusion is circular, the major axis if the plan view shape of the protrusion is elliptical, and the length of the diagonal if the plan view shape of the protrusion is rectangular.

[0192] Furthermore, if the pattern shape of the convex portion in plan view is dot-like, the pitch of the dot-like convex portion is set appropriately so that the gas flow hits the convex portion, regardless of the direction of gas flow.

[0193] Furthermore, if the pattern shape of the convex portion in plan view is grid-like, the width of the grid-like convex portion may be, for example, 1 μm or more, 10 μm or more, or 20 μm or more. On the other hand, the width of the grid-like convex portion may be, for example, 20 mm or less, or 15 mm or less. Specifically, the width of the grid-like convex portion may be 1 μm or more and 20 mm or less, 10 μm or more and 20 mm or less, or 20 μm or more and 15 mm or less.

[0194] Furthermore, if the pattern shape of the convex portion in plan view is grid-like, the spacing between the grid-like convex portions may be, for example, 1 μm or more, 10 μm or more, or 20 μm or more. On the other hand, the spacing between the grid-like convex portions may be, for example, 20 mm or less, or 15 mm or less. Specifically, the spacing between the grid-like convex portions may be 1 μm or more and 20 mm or less, 10 μm or more and 20 mm or less, or 20 μm or more and 15 mm or less.

[0195] The dimensions of the convex and concave parts are measured using a laser displacement sensor.

[0196] The cross-sectional shape of the convex portion is not particularly limited and can be rectangular, trapezoidal, triangular, semicircular, semielliptical, etc. For example, Figure 24(a) shows an example where the cross-sectional shape of the convex portion 5 is rectangular, Figure 24(b) shows an example where the cross-sectional shape of the convex portion 5 is trapezoidal, Figures 24(c) to 24(e) show examples where the cross-sectional shape of the convex portion 5 is triangular, Figure 24(f) shows an example where the cross-sectional shape of the convex portion 5 is semielliptical, Figures 24(g) to 24(h) show examples where the cross-sectional shape of the concave portion 6 is triangular, and Figure 24(i) shows an example where the cross-sectional shape of the concave portion 6 is semicircular. Specifically, when the pattern shape of the convex portion in plan view is dot-shaped, examples of dot-shaped cones include hemispheres, semiellipsoids, frustums of cones, square pyramids, frustums of square pyramids, triangular pyramids, and frustums of triangular pyramids.

[0197] When the pattern shape of the convex and concave portions in plan view is linear, it is preferable that the longitudinal direction of the linear pattern of the convex and concave portions intersects with the gas flow direction, and more preferably is approximately perpendicular to the gas flow direction. Specifically, as shown in Figure 23(a), when the pattern shape of the convex portion 5 is linear, the longitudinal direction of the linear pattern of the convex portion 5 is perpendicular to the gas flow direction d F It is preferable that it intersects with respect to the gas flow direction d F It is preferable that the structure be approximately perpendicular to the curve. In this case, the gas flow strikes the convex portion, generating small vortices due to the uneven structure, thereby suppressing flow separation.

[0198] When the longitudinal direction of the linear pattern of the convex portion intersects with the gas flow direction, the angle between the longitudinal direction of the linear pattern and the gas flow direction is preferably, for example, 45° to 135°. Similarly, when the longitudinal direction of the straight line pattern of the convex portion intersects with the gas flow direction, the angle between the longitudinal direction of the straight line pattern and the gas flow direction is preferably, for example, 45° to 135°.

[0199] Here, the longitudinal direction of the linear pattern of the convex portion is said to be approximately perpendicular to the gas flow direction if the angle between the longitudinal direction of the linear pattern and the gas flow direction is between 85° and 95°. Similarly, the longitudinal direction of the straight line pattern of the convex portion is said to be approximately perpendicular to the gas flow direction if the angle between the longitudinal direction of the straight line pattern and the gas flow direction is between 85° and 95°.

[0200] Note that the longitudinal direction of a linear pattern refers to the direction in which the linear pattern extends, for example, in the case of a straight line pattern, or the direction in which the wavy line pattern extends, in the case of a wavy line pattern.

[0201] Therefore, the angle between the longitudinal direction of the linear pattern and the gas flow direction is preferably, for example, 45° to 135°, more preferably 80° to 100°, and even more preferably 85° to 95°. Also, if the line is straight, the angle between the longitudinal direction of the straight pattern and the gas flow direction is preferably, for example, 45° to 135°, more preferably 80° to 100°, and even more preferably 85° to 95°.

[0202] Furthermore, the number of protrusions or recesses is multiple, and is set appropriately to satisfy the dimensions of the protrusions and recesses described above.

[0203] (3) Third Embodiment The third embodiment of the gas resistance reduction structure in this disclosure has an uneven surface including linear protrusions and recesses on the entire surface of the resin layer.

[0204] Figures 25(a) and 25(b) are schematic plan view and cross-sectional view, respectively, showing an example of a gas resistance reduction structure according to this embodiment. Figure 25(b) is a cross-sectional view taken along line AA of Figure 25(a). As shown in Figures 25(a) and 25(b), the gas resistance reduction structure 1C has an uneven surface 7 including linear protrusions 5 and recesses 6 on the entire surface facing the resin layer 3.

[0205] In the gas resistance reduction structure of this embodiment, the linear uneven structure is a so-called riblet. In the gas resistance reduction structure of this embodiment, the linear uneven structure can reduce frictional resistance with the gas.

[0206] The following describes the various components of the gas resistance reduction structure of this embodiment.

[0207] The gas resistance reduction structure of this embodiment has an uneven surface structure including linear protrusions and recesses on the entire surface of the resin layer. On the surface of the resin layer, it is sufficient that the linear protrusions and recesses are uniformly distributed.

[0208] Examples of linear patterns include straight lines and wavy patterns such as sine waves.

[0209] The cross-sectional shapes of the convex and concave portions are not particularly limited and include rectangular, trapezoidal, triangular, semicircular, and semi-elliptical shapes. Furthermore, the cross-sectional shapes of the convex and concave portions may have rounded vertices or corners. For example, Figure 25(b) shows an example where the cross-sectional shapes of the convex portion 5 and concave portion 6 are rectangular. Figure 26(a) shows an example where the cross-sectional shapes of the convex portion 5 and concave portion 6 are triangular. Figure 26(b) shows an example where the cross-sectional shape of the convex portion 5 is trapezoidal and the cross-sectional shape of the concave portion 6 is triangular. Figure 26(c) shows an example where the cross-sectional shape of the convex portion 5 is triangular and the cross-sectional shape of the concave portion 6 is trapezoidal. Figure 26(d) shows an example where the cross-sectional shapes of the convex portion 5 and concave portion 6 are trapezoidal.

[0210] As illustrated in Figure 25(b), when the cross-sectional shapes of the protrusion 5 and recess 6 are rectangular, the width W21 of the protrusion 5 may be, for example, 0.1 μm or more and 200 mm or less, or 20 μm or more and 5 mm or less. In this case, the width W22 of the recess 6 may be, for example, 0.1 μm or more and 500 mm or 20 μm or more and 5 mm or less. Also in this case, the height H1 of the protrusion 5 may be, for example, 0.1 μm or more and 100 mm or less, or 3 μm or more and 500 μm or less.

[0211] As illustrated in Figure 26(a), when the cross-sectional shapes of the protrusion 5 and recess 6 are triangular, the width W21 of the protrusion 5 may be, for example, 0.1 μm or more and 500 mm or less, or 20 μm or more and 5 mm or less. In this case, the height H1 of the protrusion 5 may be, for example, 0.1 μm or more and 100 mm or less, or 3 μm or more and 500 μm or less.

[0212] As illustrated in Figure 26(b), when the cross-sectional shape of the convex portion 5 is trapezoidal and the cross-sectional shape of the concave portion 6 is triangular, the width W23 of the upper base of the trapezoidal convex portion 5 may be, for example, 0.01 μm or more and 100 mm or less, or 1 μm or more and 5 mm or less. In this case, the width of the lower base of the trapezoidal convex portion 5, i.e., the width W21 of the convex portion 5, may be, for example, 0.1 μm or more and 200 mm or less, or 20 μm or more and 5 mm or less. Also in this case, the height H1 of the convex portion 5 may be, for example, 0.1 μm or more and 100 mm or less, or 3 μm or more and 500 μm or less.

[0213] As illustrated in Figure 26(c), when the cross-sectional shape of the protrusion 5 is triangular and the cross-sectional shape of the recess 6 is trapezoidal, the width W21 of the protrusion 5 may be, for example, 0.01 μm or more and 100 mm or less, or 1 μm or more and 5 mm or less. In this case, the width W22 of the recess 6 may be, for example, 0.1 μm or more and 200 mm or less, or 20 μm or more and 5 mm or less. Also in this case, the height H1 of the protrusion 5 may be, for example, 0.1 μm or more and 100 mm or less, or 3 μm or more and 500 μm or less.

[0214] As illustrated in Figure 26(d), when the cross-sectional shape of the convex portion 5 and the concave portion 6 is trapezoidal, the width W23 of the upper base of the trapezoidal convex portion 5 may be, for example, 0.01 μm or more and 100 mm or less, or 1 μm or more and 5 mm or less. In this case, the width of the lower base of the trapezoidal convex portion 5, i.e., the width W21 of the convex portion 5, may be, for example, 0.1 μm or more and 200 mm or less, or 20 μm or more and 5 mm or less. In this case, the width W22 of the concave portion 6 may be, for example, 0.01 μm or more and 100 mm or less, or 1 μm or more and 5 mm or less. Also in this case, the height H1 of the convex portion 5 may be, for example, 0.1 μm or more and 100 mm or less, or 3 μm or more and 500 μm or less.

[0215] Note that the dimensions of the convex and concave portions are measured by a laser displacement sensor.

[0216] The longitudinal direction of the linear patterns of the convex and concave portions is preferably substantially parallel to the gas flow direction. Specifically, as shown in Fig. 25(a), when the pattern shapes of the convex portion 5 and the concave portion 6 are linear, the longitudinal direction of the linear patterns of the convex portion 5 and the concave portion 6 is preferably substantially parallel to the gas flow direction d F In such a case, the frictional resistance with the gas can be reduced.

[0217] Also, the number of the convex or concave portions is plural and is appropriately set so as to satisfy the above-mentioned dimensions of the convex and concave portions.

[0218] 4. Form of the Gas Resistance Reduction Structure The form of the gas resistance reduction structure in the present disclosure is not particularly limited, but it is preferably a film. The gas resistance reduction structure can be easily applied to the surface of an object.

[0219] 5. Other Configurations When the gas resistance reduction structure in the present disclosure is a film, the film-like gas resistance reduction structure may further have other configurations in addition to the substrate and the resin layer. The other configurations are appropriately selected according to the type of the substrate.

[0220] (1) When the substrate is a resin film (a) Adhesive layer For example, as shown in Fig. 27(a), the gas resistance reduction structure 1 in the present disclosure may have an adhesive layer 21 on the surface of the substrate 2 opposite to the resin layer 3. The adhesive layer is a layer for attaching the film-like gas resistance reduction structure to the surface of an object. By arranging the adhesive layer, the gas resistance reduction structure can be easily attached to the surface of the object.

[0221] The adhesive used in the adhesive layer is appropriately selected depending on the application of the gas resistance reduction structure, and examples include acrylic adhesives, urethane adhesives, silicone adhesives, rubber adhesives, and vinyl ether adhesives.

[0222] Furthermore, the adhesive layer may or may not have repositionable properties. In particular, it is preferable that the adhesive layer has repositionable properties. When the adhesive layer has repositionable properties, it is possible to reposition the gas resistance reduction structure when attaching it to the surface of an object, and when replacing or removing the gas resistance reduction structure, it is possible to peel it off the object without leaving any adhesive residue.

[0223] Furthermore, "removability" refers to the property of being able to easily remove a gas resistance-reducing structure from the surface of an object without damaging the object or leaving any adhesive residue on the object's surface.

[0224] Furthermore, the adhesive layer may contain a coloring agent. By including a coloring agent in the adhesive layer, shielding properties can be provided. For example, if an object has a design applied to its surface, and the adhesive layer contains a coloring agent, and the gas resistance reduction structure further has a printed layer as described later, then by attaching the gas resistance reduction structure to the surface of the object, the existing design can be concealed and a new design can be applied.

[0225] The thickness of the adhesive layer is not particularly limited and is selected appropriately depending on the application. For example, when using a gas resistance reduction structure as a wrapping film or marking film for moving objects such as automobiles, trains, and aircraft, the thickness of the adhesive layer is, for example, 5 μm to 50 μm. If the adhesive layer is too thin, the adhesion to the moving object may be insufficient.

[0226] Methods for forming an adhesive layer include, for example, applying an adhesive composition or laminating an adhesive film.

[0227] (b) Printing layer The gas resistance reduction structure in this disclosure may have a printed layer on the surface opposite to the resin layer of the substrate. The presence of the printed layer can provide aesthetic appeal.

[0228] The printing layer can display information such as letters, numbers, symbols, pictures, patterns, and marks.

[0229] Furthermore, the method for forming the printed layer may be, for example, by directly printing onto a resin film substrate, or, as shown in Figure 27(b), the printed layer 23 may be formed by printing onto a support layer 22. The printed layer may be arranged in a pattern on the substrate or support layer, or it may be arranged over the entire surface of the substrate or support layer. The printing method is not particularly limited.

[0230] The support layer is not particularly limited as long as it can be printed on; for example, a resin substrate can be used.

[0231] Furthermore, the support layer may contain a coloring agent. By including a coloring agent in the support layer, shielding properties can be provided. For example, if an object has a design applied to its surface, and the gas resistance reduction structure has a printed layer and the support layer contains a coloring agent, then by attaching the gas resistance reduction structure to the surface of the object, the existing design can be concealed and a new design can be applied.

[0232] The thickness of the support layer is not particularly limited and can be selected as appropriate depending on the application.

[0233] Furthermore, when forming a printed layer by printing on a support layer, for example, as shown in Figure 27(b), a printed sheet having a support layer 22 and a printed layer 23 arranged on one side of the support layer 22 may be separately manufactured, and this printed sheet may be bonded to the substrate 2 via a second adhesive layer 24, or the printed layer, substrate, and resin layer may be formed in order on the support layer.

[0234] 6.Applications The gas resistance reduction structure described herein can be applied to the surface of an object. Specifically, it can be applied to the casings and components of automobiles such as passenger cars, trucks, and buses; railway vehicles such as trains, bullet trains, and locomotives; aircraft such as airplanes, helicopters, and drones; and bicycles, which move through gas. Furthermore, the gas resistance reduction structure described herein can also be applied to the inner surface of pipes such as ducts and gas pipes, the surface of wind turbine blades, and the surface of air outlets or louvers of air conditioning equipment such as air conditioners. In particular, the gas resistance reduction structure described herein is preferably applied to the surface of the casings and components of a moving object, and is especially preferably applied to the surface of a non-streamlined object, specifically a bluff body. This is because in a bluff body, the contribution of pressure resistance to gas resistance is large, and the effects of this disclosure are significantly exhibited. Examples of bluff bodies include trucks and buses.

[0235] Furthermore, when applying the gas resistance reduction structure described herein to the surface of an object, the surface of the object may be flat or curved.

[0236] When applying the gas resistance reduction structure described herein to the surface of an object, for example, a film-like gas resistance reduction structure may be placed on the surface of the object, or the gas resistance reduction structure may be formed directly on the surface of the object.

[0237] The gas resistance reducing structure in this disclosure may be arranged over the entire surface of an object, or on a portion of the surface of an object.

[0238] In particular, it is preferable to place the gas resistance reduction structure in a location where flow separation is likely to occur. The location where flow separation is likely to occur varies depending on the type and shape of the moving object, etc.

[0239] Furthermore, while the gas resistance reduction structure in this disclosure can reduce gas resistance, the gas is not particularly limited. The density of the gas can be, for example, 0.08 kg / m³.3 More than 10kg / m 3 The following is preferable. Among these, the gas is preferably air.

[0240] B. Mobile object The mobile body in this disclosure has the gas resistance reduction structure described above.

[0241] Examples of mobile objects include automobiles such as passenger cars, trucks, and buses; railway vehicles such as trains, bullet trains, and locomotives; aircraft such as airplanes, helicopters, and drones; and mobile objects that move through gases, such as bicycles.

[0242] In particular, the moving body is preferably a non-streamlined object, specifically a bluff body. This is because, in a bluff body, the contribution of pressure resistance to fluid resistance is large, and the effects of this disclosure are significantly exhibited. Examples of moving bodies having the form of a bluff body include trucks and buses.

[0243] Figure 16 is a diagram showing an example of a mobile body of the present disclosure, in which the mobile body is an example of a track 50A. As shown in Figure 16, the mobile body, track 50A, has the gas resistance reduction structure 1 described above on its surface. Specifically, the mobile body, track 50A, has the gas resistance reduction structure 1 described above on its front side.

[0244] In Figure 16, a truck is shown as an example of a mobile body, illustrating a configuration in which the gas resistance reduction structure is applied to its front side. However, the mobile body having the gas resistance reduction structure is not limited to this.

[0245] In the mobile body described herein, the gas resistance reduction structure described above may be arranged on the entire surface of the mobile body or on a part of the surface of the mobile body. In particular, it is preferable that the gas resistance reduction structure described above be arranged on the surface of the mobile body at a location where flow separation is likely to occur. The location where flow separation is likely to occur varies depending on the type and shape of the mobile body, etc.

[0246] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and achieves similar effects is included within the technical scope of this disclosure. [Examples]

[0247] The present disclosure will be further explained below with reference to examples and comparative examples.

[0248] [Example 1] A UV-curable resin (urethane acrylate containing cyclohexyl acrylate) manufactured by DNP Fine Chemical Co., Ltd. was used to coat a mold with an uneven surface. As the resin film, Avery Dennison's laminate film "DOL1460," which has a vinyl chloride resin film, an adhesive layer, and a release liner in that order, was used. With the release liner still attached, the vinyl chloride resin film side of the laminate film was brought into close contact with the UV-curable resin coating, and after curing the UV-curable resin by irradiation with ultraviolet light, it was peeled off the mold. After peeling the release liner from the laminate of the resin layer with an uneven surface structure and the laminate film, the laminate film side of the laminate was laminated to 3M's printing material "IJ180mc-114." In this way, a gas resistance reduction structure having a resin layer with an uneven surface structure, a vinyl chloride resin film, an adhesive layer, and a printing material in that order was fabricated. The height of the protrusion was 140 μm, and the thickness of the coating was 15 μm.

[0249] [Comparative Example 1] As the resin film, Avery Dennison's laminate film "DOL1460," which has a polyvinyl chloride resin film, an adhesive layer, and a release liner in that order, was used. After peeling off the release liner from the laminate film, the adhesive layer side of the laminate film was laminated onto 3M's printing substrate "IJ180mc-114." Next, UV-curable ink was ejected and cured onto the polyvinyl chloride resin film side of the laminate film using a UV inkjet device to form a textured structure with multiple linear protrusions and recesses. Furthermore, as shown in Figure 4, the first and second regions with the textured structure were formed to be arranged alternately in a stripe pattern. In this way, a structure having the textured structure, polyvinyl chloride resin film, adhesive layer, and printing substrate in that order was fabricated. The height of the protrusions was 140 μm, and the thickness of the covering was 0 μm.

[0250] [Rating 1] To evaluate the change in the height of the protrusions due to aging, the following weather resistance test was conducted, and the height of the protrusions was measured after a predetermined period of time. The results are shown in Figure 28.

[0251] <Weather resistance test> • Equipment: Atlas Ci4000 weather meter ·Condition: Irradiance 180W / m 2 (Wavelengths from 300nm to 400nm) Black panel temperature: 63℃ Humidity 50%RH (during irradiation), 95%RH (during spraying) Tank temperature 38℃ Program 1 cycle: 102 minutes irradiation, 18 minutes irradiation, spray

[0252] Figure 28 shows that in Example 1, the height of the protrusion can be maintained because the covering portion is in place.

[0253] [Reference examples 1~7] A printing master sheet (3M's "IJ180 mc-114") with a transparent substrate was used. Also, a laminate film (Avery Dennison's "DOL1460Z") having a vinyl chloride resin film, an adhesive layer, and a release paper in this order was used. After peeling the release paper from the laminate film, the surface on the adhesive layer side of the laminate film was laminated on the printing master sheet. Next, a UV curable ink (Dainichi Seika Co., Ltd.'s "Seika Beam HT509") was ejected and cured onto the surface on the vinyl chloride resin film side of the laminate film using a UV inkjet device to form a first region having a plurality of linear convex portions and concave portions. Also, as shown in Fig. 4(a), the first region was formed such that the first region and the second region were alternately arranged in a stripe pattern. The dimensions of the first region and the second region were as shown in Table 1 below. Thereby, an A4-sized wrapping film was produced.

[0254] [Evaluation 2] The wrapping films of Reference Examples 1 to 7 were attached to the front side and the upper front part of a truck-shaped model (length 1250 mm, width 260 mm, height 387 mm), and a wind tunnel experiment was conducted under the following conditions to measure the air resistance coefficient (Cd value). Figs. 29(a) to 29(c) show the truck-shaped model. Fig. 29(a) is a top view of the model, Fig. 29(b) is a side view of the model, and Fig. 29(c) is a rear view of the model. This truck-shaped model is a simplified model that is 1 / 10 the size of a 10-ton truck.

[0255] <Wind tunnel experiment conditions> · Outlet dimensions: Rectangle with a width of 1.0 m and a height of 0.7 m · Measurement section length: 1.45 m · Wind speed: Five levels of 10 m / s, 15 m / s, 20 m / s, 25 m / s, and 30 m / s · Film size: 210 mm × 297 mm · Attachment location: Front side and upper front part of the truck-shaped model · Attachment method: With the R start part at the front of the truck-shaped model as the tip, the film was attached toward the rear.

[0256] The Cd value was calculated using the following formula. Cd = D / (ρU 2 S × 1 / 2) (In the above formula, D: drag force (N), ρ: density (kg / m³) 3 ), U: Representative speed (m / s), S: Representative area (m 2 ) is. ) In this experiment, the drag force D was measured using a load cell attached to a wire mounted on a track-shaped model. The density ρ was 1.124 kg / m³. 3 The representative velocity U is the same as the wind speed, and the representative area S is 0.101 m². 2 That's what I decided.

[0257] Additionally, Example 8 shows the case where no wrapping film is applied.

[0258] [Table 1]

[0259] Reference Examples 1-7 confirmed that the wind speed dependence of the Cd value changes depending on the height of the protrusion. Therefore, it was shown that when the height of the protrusion changes, especially when the height of the protrusion decreases, the wind speed dependence of the Cd value changes, and depending on the speed of the moving object, the gas resistance reduction effect becomes smaller, meaning that a stable gas resistance reduction effect cannot be obtained. In this disclosure, as described above, even if the film on the protrusion decreases due to aging, the film on the coating portion of the resin layer decreases along with the protrusion, so the height of the protrusion can be maintained. Therefore, a stable gas resistance reduction effect can be obtained.

[0260] [Reference example 9] A printing substrate with a transparent base material (3M "IJ180 mc-114") was used. A laminate film (Avery Dennison "DOL1460Z") having a polyvinyl chloride resin film, an adhesive layer, and a release liner in that order was also used. After peeling the release liner from the laminate film, the adhesive layer side of the laminate film was laminated onto the printing substrate. Next, UV-curable ink (Dainichi Seika "Seika Beam HT509") was ejected and cured onto the polyvinyl chloride resin film side of the laminate film using a UV inkjet device, forming a textured structure with multiple linear protrusions and recesses. As shown in Figure 23(a), the textured structure was formed across the entire surface of the polyvinyl chloride resin film. The height of the protrusions was 140 μm, the width of the protrusions was 140 μm, the width of the recesses was 980 μm, and the length of the protrusions was 210 mm. This resulted in the creation of an A4-sized wrapping film.

[0261] [Rating 3] Similar to evaluation 2 above, wind tunnel experiments were conducted to measure the drag coefficient (Cd value).

[0262] [Table 2]

[0263] This disclosure provides the following inventions. [1] comprising a substrate and a resin layer disposed on one surface of the substrate, The above resin layer has, in order from the substrate side, a covering portion that covers one surface of the substrate and a protruding portion, A gas resistance reducing structure in which the thickness of the above-mentioned coating portion is 5 μm or more and 50 μm or less. [2] The gas resistance reducing structure according to [1], wherein the resin layer contains a cured product of a curable resin composition. [3] The gas resistance reducing structure according to [1] or [2], wherein the resin layer contains a cured product of an ultraviolet-curable resin composition. [4] The gas resistance reducing structure according to any one of [1] to [3], wherein the resin layer contains an ultraviolet absorber. [5] The resin layer contains a cured product of an ultraviolet curable resin composition containing an ultraviolet absorber, The gas resistance reducing structure according to any one of [1] to [4], wherein the transmittance of the ultraviolet absorber at a wavelength of 365 nm is 10% or more. [6] The gas resistance reducing structure according to any one of [1] to [5], wherein the substrate is a resin member. [7] The gas resistance reducing structure according to any one of [1] to [6], wherein the substrate is a resin film. [8] The gas resistance reducing structure according to [6] or [7], wherein the substrate contains an ultraviolet absorber. )[9] The resin layer contains a cured product of an ultraviolet curable resin composition, The gas resistance reducing structure according to any one of [6] to [8], wherein the transmittance of the substrate at a wavelength of 365 nm is 10% or more.

[10] The gas resistance reducing structure according to any one of [1] to [9], wherein the coating portion and the convex portion contain the same material.

[11] The gas resistance reducing structure has a first region having an uneven structure including the convex portion and the concave portion on the surface on the resin layer side, and a second region adjacent to the first region, The first region and the second region extend in a strip shape in a second direction intersecting the first direction, The gas resistance reducing structure according to any one of [1] to

[10] , wherein the height of the convex portion is 1 μm or more and 1000 μm or less.

[12] The gas resistance reducing structure according to

[11] , wherein the first region and the second region are alternately arranged in the first direction.

[13] The gas resistance reducing structure has an uneven structure including the convex portion and the concave portion on the entire surface on the resin layer side, The gas resistance reducing structure according to any one of [1] to

[10] , wherein the height of the convex portion is 1 μm or more and 20 mm or less.

[14] The gas resistance reducing structure has an uneven structure including the linear convex portion and the concave portion on the entire surface on the resin layer side, A gas resistance reducing structure according to any one of [1] to

[10] , wherein the height of the above-mentioned protrusion is 0.1 μm or more and 100 mm or less.

[15] A mobile body having a gas resistance reducing structure as described in any of [1] to

[14] . [Explanation of Symbols]

[0264] 1, 1A, 1B ... Gas resistance reduction structure 2...Base 3… Resin layer 4. Covering part 5 ... protruding part 6… recess 7 … Uneven structure 11 … 1st area 12…Second area d1 … 1st direction d2…Second direction H1 ... Height of the protrusion

Claims

1. It comprises a substrate and a resin layer disposed on one surface of the substrate, The resin layer has, in order from the substrate side, a covering portion that covers one surface of the substrate and a protruding portion, A gas resistance reducing structure in which the thickness of the coating portion is 5 μm or more and 50 μm or less.

2. The gas resistance reducing structure according to claim 1, wherein the resin layer contains a cured product of a curable resin composition.

3. The gas resistance reducing structure according to claim 2, wherein the resin layer contains a cured product of an ultraviolet-curable resin composition.

4. The gas resistance reducing structure according to claim 1, wherein the resin layer contains an ultraviolet absorber.

5. The resin layer contains a cured product of an ultraviolet-curable resin composition containing an ultraviolet absorber, The gas resistance reducing structure according to claim 1, wherein the transmittance of the ultraviolet absorber at a wavelength of 365 nm is 10% or more.

6. The gas resistance reducing structure according to claim 1, wherein the substrate is a resin member.

7. The gas resistance reducing structure according to claim 6, wherein the substrate is a resin film.

8. The gas resistance reducing structure according to claim 6, wherein the substrate contains an ultraviolet absorber.

9. The aforementioned resin layer contains a cured product of an ultraviolet-curable resin composition, The gas resistance reducing structure according to claim 8, wherein the transmittance of the substrate at a wavelength of 365 nm is 10% or more.

10. The gas resistance reducing structure according to claim 1, wherein the covering portion and the protrusion portion contain the same material.

11. The gas resistance reduction structure has a first region having an uneven structure including the convex and concave portions on the surface facing the resin layer, and a second region adjacent to the first region. The first region and the second region extend in a strip-like manner in a second direction intersecting the first direction, The gas resistance reducing structure according to claim 1, wherein the height of the protrusion is 1 μm or more and 1000 μm or less.

12. The gas resistance reduction structure according to claim 11, wherein the first region and the second region are alternately arranged in the first direction.

13. The gas resistance reducing structure has an uneven surface including the convex and concave portions on the entire surface of the resin layer side, The gas resistance reducing structure according to claim 1, wherein the height of the protrusion is 1 μm or more and 20 mm or less.

14. The gas resistance reducing structure has an uneven surface on the entire surface of the resin layer side, including linear protrusions and recesses. The gas resistance reducing structure according to claim 1, wherein the height of the protrusion is 0.1 μm or more and 100 mm or less.

15. A mobile body having a gas resistance reducing structure according to any one of claims 1 to 14.

Images