Window film and window member

Abstract

To provide a window film capable of reducing visibility when looking at the inside from the outside while maintaining visibility when looking at the outside from the inside.SOLUTION: The window film includes in this order: an adhesive portion; a substrate; and a reflective portion that reflects light, the reflective portion having a plurality of convex portions provided on the surface of the substrate, and the plurality of convex portions being approximately hemispherical.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] It relates to a window film and a window material.

Background Art

[0002] In some cases, a reflective film is pasted on the windows of a building as a blind so that the outside cannot be seen from the outside. On the other hand, when a reflective film that reflects light excessively is pasted on a window, the view from the inside to the outside cannot be seen. Therefore, a film that functions as a half mirror that reflects light at an appropriate ratio is used. Since the half mirror film reflects a part of the incident light and transmits a part of it, it looks like a mirror from one side, and the view on the other side of the film can be seen from the other side.

[0003] Patent Document 1 discloses a half mirror film in which a metal thin film is formed on a plastic film by vapor deposition or the like. Non-Patent Document 1 discloses a technique for forming a dome-shaped structure with an outer diameter of several μm to several tens of μm on one surface of a transparent substrate with a transparent resin. Non-Patent Document 1 describes that the substrate looks transparent from the side provided with the dome-shaped structure, and has a specific color when viewed from the opposite side.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, since the half-mirror film described in Patent Document 1 reflects part of the incident light with a metal thin film, the visibility from indoors may decrease depending on the wavelength of the incident light. Further, Non-Patent Document 1 does not disclose a technique for imparting a similar function to window glass.

[0006] The present invention has been made to solve the above-described problems, and an object thereof is to provide a window film capable of reducing the visibility when looking from the outside to the inside while maintaining the visibility when looking from the inside to the outside. Another object of the present invention is to provide a window material capable of reducing the visibility when looking from the outside to the inside while maintaining the visibility when looking from the inside to the outside.

Means for Solving the Problems

[0007] The above object is achieved by the following present invention. That is, according to the present invention, there is provided a window film having an adhesive portion, a base material, and a reflection portion that reflects light, in this order, wherein the reflection portion has a plurality of convex portions provided on the surface of the base material, and the plurality of convex portions are substantially hemispherical.

[0008] Further, according to the present invention, there is provided a window material having a base material and a reflection portion that reflects light, wherein the reflection portion has a plurality of convex portions provided on the surface of the base material, and the plurality of convex portions are substantially hemispherical.

Effects of the Invention

[0009] According to the present invention, it is possible to provide a window film capable of reducing the visibility when looking from the outside to the inside while maintaining the visibility when looking from the inside to the outside. Further, according to the present invention, it is possible to provide a window material capable of reducing the visibility when looking from the outside to the inside while maintaining the visibility when looking from the inside to the outside.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0011] The present inventors have studied a technique for making it difficult to be seen from the outside while maintaining visibility from the inside in window materials such as window glass and window films used by being attached to window materials. As a result, it has been found that by providing a reflecting portion having a plurality of hemispherical convex portions on the surface of the base material, the base material side can be visually recognized from the convex portion side, while the convex portion side is difficult to be seen from the base material side. Furthermore, in the window film, it has been found that by providing an adhesive portion on the surface of the base material on the side opposite to the side where the convex portion is provided, it can be used by being attached to a window material having no reflecting function.

[0012] The reason why such an effect is obtained is presumably that the light incident from the base material side passes through the inside of the plurality of convex portions and is reflected by the surface of the convex portion, so that the light from the base material side is efficiently reflected.

[0013] Hereinafter, preferred embodiments will be given to explain the present invention in more detail.

[0014] (First Embodiment) In this embodiment, a window film that can be attached to a window material attached to a building will be described. FIG. 1(a) is a schematic cross-sectional view showing the configuration of the window film 100 in this embodiment. FIG. 1(b) is an enlarged view of the convex portion 2 formed on the window film 100. Here, for convenience, from the positional relationship between the base material and the convex portion, the side where the base material is located is referred to as the base material side (negative Z direction), and the side where the convex portion is located is referred to as the convex portion side (positive Z direction).

[0015] The base material 1 is a layer that serves as the base of the window film. The base material 1 is composed of a material that transmits light, and preferably has a visible light transmittance of 80% or more. Examples of the material used for the base material 1 include synthetic resins such as polycarbonate, acrylic resin, and polyethylene terephthalate. Also, the base material 1 may be composed of materials such as soda-lime glass, lead glass, and optical glass.

[0016] The reflection part reflects the light incident on the window film 100 and has a plurality of convex portions 2. The convex portion 2 is provided on the base material 1 and is substantially hemispherical. The convex portion 2 is composed of a material that transmits light, and preferably has a visible light transmittance of 80% or more. For the convex portion 2, similar to the base material 1, synthetic resins such as polycarbonate, acrylic resin, and polyethylene terephthalate can be used. Also, it may be composed of materials such as soda-lime glass, lead glass, and optical glass.

[0017] The adhesive part 3 serves to attach the film to the window material and has adhesiveness. The adhesive part 3 may be configured to contain an ultraviolet absorber. The material that can be used to form the adhesive part 3 is not particularly limited as long as it is transparent, that is, has a visible light transmittance of 80% or more, and can be appropriately selected according to the purpose. For example, polyester resin, silicone resin, acrylic resin, etc. can be mentioned. These may be used alone or in combination of two or more. The adhesive part 3 containing these materials can be formed by coating.

[0018] When each convex portion 2 satisfies the conditions, it appears colored when viewed from the substrate side in an environment containing light of various wavelengths such as sunlight. On the other hand, when viewed from the convex portion side, it appears colorless and transparent.

[0019] The angle θ is the angle formed by the end of the convex portion 2 and the surface of the substrate 1. The diameter d is the diameter of the convex portion 2. When the angle θ is 46° or more and the diameter d is within a certain range, the convex portion 2 reflects light of a specific wavelength and is likely to appear colored when viewed from the substrate side. The color when it appears colored depends on the angle θ, the diameter d, and the refractive index of the material constituting the convex portion 2, etc.

[0020] For example, when the angle θ is 68.5° and the refractive index is 1.54, the convex portion 2 appears blue when the diameter d is 6.6 μm. Under the same conditions, it appears yellow when the diameter d is 8.6 μm and red when the diameter d is 10.0 μm. The diameter d and the angle θ of the convex portion 2 in the present embodiment are not limited to these, and other numerical values can be taken according to the refractive index of the material and the target color of the design. The diameter d is preferably 1.0 μm or more and 30 μm or less. Also, the angle θ is preferably 45° or more and 90° or less.

[0021] FIG. 2 is a schematic view of the window film 100 in the present embodiment as viewed from the Z direction. In the present embodiment, the case where the convex portions 2 are regularly arranged vertically and horizontally at the same interval on a plane will be described as an example, but it is not limited to this, and the convex portions 2 can be arranged in various ways. When providing convex portions 2 that reflect light of the same diameter and the same wavelength, the higher the density of arranging the convex portions 2, the greater the intensity of the light reflected to the convex portion side and the brighter it becomes. Also, when arranging a plurality of types of convex portions 2 that reflect light of different wavelengths in a mixed manner, it appears to be a mixed color to the human eye.

[0022] The window film in this embodiment is used by being attached to a window material such as window glass of a building facing the outside from the indoor side. Then, in the area where the window film is attached, when looking from the outside to the inside, it appears colored, and as a result, it becomes difficult to see inside from the outside, and privacy is maintained. On the other hand, when looking from the inside to the outside, it appears transparent like ordinary window glass, and the scenery outside the building can be seen from the inside.

[0023] In this embodiment, the film is provided with an adhesive portion, but this is not necessarily required as long as the film can be in close contact with the window glass. For example, the base material 1 may be configured to be electrostatically adsorbed directly to the window glass.

[0024] In this embodiment, the configuration in which the window film having a reflective portion is attached to the window material has been described, but a configuration in which the window film is attached to the window material in advance may also be used. Further, a configuration may be adopted in which the reflective portion (a plurality of convex portions) is directly provided on the window glass (base material) without having an adhesive portion.

[0025] (Second Embodiment) The window film according to this embodiment is different from the first embodiment in that a coating layer 4 for protecting the convex portion 2 which is a reflective portion is provided. Since the other elements of this embodiment are the same as the corresponding ones of the first embodiment described above, the same reference numerals are given for description.

[0026] FIG. 3 is a schematic cross-sectional view showing the configuration of the window film 100 in this embodiment.

[0027] The surface of the coating layer 4 opposite to the side in contact with the convex portion 2 is smooth. The coating layer 4 is provided to protect the convex portion 2 from external physical contact. By the coating layer 4, the convex portion 2 can be protected from external contact, and a situation where the convex portion 2 peels off from the base material 1 can be prevented.

[0028] The coating layer 4 is made of a material that transmits light, and preferably has a visible light transmittance of 80% or more. Further, since the light reflection phenomenon caused by the convex portion 2 depends on the refractive index difference on the surface of the convex portion 2, the refractive index n1 of the convex portion 2 needs to be larger than the refractive index n2 of the coating layer 4. Also, the difference in refractive index needs to be relatively large. Specifically, the refractive index n1 of the convex portion 2 is preferably 1.70 or more. Also, the refractive index n2 of the coating layer 4 is preferably 1.35 or less.

[0029] The window film according to the present embodiment can provide a window film with improved durability while maintaining the functions of the first embodiment.

[0030] In addition, in the present embodiment, although the configuration in which the window film having the reflection portion is attached to the window material has been described, a configuration in which the window film is attached to the window material in advance may be used. Also, a configuration in which the reflection portion (a plurality of convex portions) is directly provided on the window glass (base material) without having an adhesive portion may be used.

[0031] (Third Embodiment) In the present embodiment, the laminated window glass that is attached to a building in advance and used will be described. The laminated window glass according to the present embodiment is different from the second embodiment in that the window film is sandwiched between two glass substrates. Since the other elements are the same as the corresponding ones in the second embodiment described above, the description will be omitted by aligning the last digit of the figure number.

[0032] FIG. 4 is a schematic cross-sectional view showing the configuration of the laminated window glass 200 in the present embodiment. The laminated window glass 200 has a plurality of glass substrates 25 as the base material. The glass substrate 25 may be composed of any glass substrate that can be used as a base material for laminated window glass, and is, for example, composed of soda lime or float glass.

[0033] The laminated window glass in this embodiment can be used as window glass to be attached to a building, similar to ordinary laminated window glass, and can have the function of appearing colored when viewed from one side and appearing transparent when viewed from the opposite side.

[0034] The disclosure of this embodiment includes the following configurations.

[0035] (Configuration 1) A window film having, in this order, an adhesive portion, a base material, and a reflective portion that reflects light, wherein the reflective portion has a plurality of convex portions provided on the surface of the base material, The plurality of convex portions are substantially hemispherical, characterized window film.

[0036] (Configuration 2) The plurality of convex portions have a diameter of 1.0 μm or more and 30 μm or less, characterized window film according to Configuration 1.

[0037] (Configuration 3) The angle formed by the end of the plurality of convex portions and the surface of the base material is 45° or more and 90° or less, characterized window film according to Configuration 1 or 2.

[0038] (Configuration 4) The visible light transmittance of the base material is 80% or more, characterized window film according to any one of Configurations 1 to 3.

[0039] (Configuration 5) The visible light transmittance of the plurality of convex portions is 80% or more, characterized window film according to any one of Configurations 1 to 4.

[0040] (Configuration 6) Further having a coating layer in contact with the plurality of convex portions, The surface of the coating layer on the side opposite to the side in contact with the plurality of convex portions is smooth, characterized window film according to any one of Configurations 1 to 5.

[0041] (Configuration 7) The window film according to Configuration 6, wherein the visible light transmittance of the coating layer is 80% or more.

[0042] (Configuration 8) The window film according to Configuration 6 or 7, wherein the refractive index of the plurality of convex portions is 1.70 or more, and the refractive index of the coating layer is 1.35 or less.

[0043] (Configuration 9) The window film according to any one of Configurations 1 to 8, wherein the visible light transmittance of the adhesive portion is 80% or more.

[0044] (Configuration 10) A window material having a base material and a reflecting portion that reflects light, wherein the reflecting portion has a plurality of convex portions provided on the surface of the base material, The window material, wherein the plurality of convex portions are substantially hemispherical.

[0045] (Configuration 11) Further having a coating layer in contact with the plurality of convex portions, The window material according to Configuration 10, wherein the surface of the coating layer on the side opposite to the side in contact with the plurality of convex portions is smooth.

[0046] (Configuration 12) Having a plurality of the base materials, The window material according to Configuration 10, wherein a first base material, the reflecting portion, and a second base material are positioned in this order.

Explanation of Reference Numerals

[0047] 1 Base material 2 Convex portion 3 Adhesive portion 4 Coating layer 100 Window film 200 Laminated window glass

Claims

1. A window film having, in this order, an adhesive portion, a base material, and a reflective portion that reflects light, The reflective portion has a plurality of convex portions provided on the surface of the base material, The plurality of convex portions are substantially hemispherical, characterized window film.

2. The plurality of convex portions have a diameter of 1.0 μm or more and 30 μm or less, characterized window film according to claim 1.

3. The angle formed by the end of the plurality of convex portions and the surface of the base material is 45° or more and 90° or less, characterized window film according to claim 1.

4. The visible light transmittance of the base material is 80% or more, characterized window film according to claim 1.

5. The visible light transmittance of the plurality of convex portions is 80% or more, characterized window film according to claim 1.

6. Further having a coating layer in contact with the plurality of convex portions, The surface of the coating layer on the side opposite to the side in contact with the plurality of convex portions is smooth, characterized window film according to claim 1.

7. The visible light transmittance of the coating layer is 80% or more, characterized window film according to claim 6.

8. The refractive index of the plurality of convex portions is 1.70 or more, and the refractive index of the coating layer is 1.35 or less, characterized window film according to claim 6.

9. The visible light transmittance of the adhesive portion is 80% or more, characterized window film according to claim 1.

10. A window material having a base material and a reflective portion that reflects light, The reflective portion has a plurality of convex portions provided on the surface of the base material, The window material is characterized in that the plurality of convex portions are substantially hemispherical.

11. It further has a coating layer in contact with the plurality of convex portions, The window material according to claim 10, characterized in that a surface of the coating layer on a side opposite to a side in contact with the plurality of convex portions is smooth.

12. It has a plurality of the base materials, The window material according to claim 10, characterized in that a first base material, the reflection portion, and a second base material are located in this order.

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