Dimmable film having a three-dimensional curved surface and method for manufacturing the same.

Abstract

To provide a light-adjustable film having a three-dimensional curved surface, in which problems such as wrinkles and cracks in the electrode layer are suppressed. [Solution] A light-adjusting film comprising, in this order, a first transparent conductive film, a light-adjusting layer comprising a polymer matrix and a liquid crystal component, and a second transparent conductive film, and having a three-dimensional curved surface portion, wherein the first transparent conductive film comprises a first resin substrate and a first electrode layer disposed on the light-adjusting layer side of the first resin substrate, and the second transparent conductive film comprises a second resin substrate and a second electrode layer disposed on the light-adjusting layer side of the second resin substrate, and the ratio of the average thickness of the central portion to the average thickness of the edge portion of the three-dimensional curved surface portion of the first transparent conductive film and the second transparent conductive film is 97% or more.

Description

[Technical Field]

[0001] The present invention relates to a light-adjusting film having a three-dimensional curved surface and a method for manufacturing the same. [Background technology]

[0002] A light-adjusting film having a pair of transparent conductive films and a light-adjusting layer disposed between them, which includes a polymer matrix and a liquid crystal component, can change the orientation of the liquid crystal component in response to the potential difference between the pair of transparent conductive films, thereby changing the degree of scattering of transmitted light (Patent Document 1).

[0003] When applying the above-mentioned dimming film to devices with curved shapes, such as head-mounted displays and curved monitors, it may be necessary to process the flat dimming film into a three-dimensional curved shape (hereinafter also referred to as "curved surface processing"). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 7099578 [Overview of the project] [Problems that the invention aims to solve]

[0005] When a light-adjustable film is stretched from a flat surface to a three-dimensional curved surface during curved surface processing, problems such as wrinkles and cracks in the electrode layer of the transparent conductive film may occur. Therefore, the main objective of the present invention is to provide a light-adjustable film having a three-dimensional curved surface portion in which problems such as wrinkles and cracks in the electrode layer are suppressed. [Means for solving the problem]

[0006] [1] According to one aspect of the present invention, a light-adjusting film is provided which comprises, in this order, a first transparent conductive film, a light-adjusting layer comprising a polymer matrix and a liquid crystal component, and a second transparent conductive film, and having a three-dimensional curved portion, wherein the first transparent conductive film comprises a first resin substrate and a first electrode layer disposed on the light-adjusting layer side of the first resin substrate, and the second transparent conductive film comprises a second resin substrate and a second electrode layer disposed on the light-adjusting layer side of the second resin substrate, and the ratio of the average thickness of the central portion to the average thickness of the edge portion of the three-dimensional curved portion of the first transparent conductive film and the second transparent conductive film is 97% or more. [2] In the dimming film described in [1] above, the radius of curvature of the three-dimensional curved surface may be 60 mm to 320 mm. [3] In the dimming film described in [1] or [2] above, the glass transition temperature and the coefficient of linear expansion of the first resin substrate are set to T1℃ and C1×10 -5 When set to / ℃, T1 and C1 may satisfy the relationship (T1-25)×C1≦650, and the glass transition temperature and linear expansion coefficient of the second resin substrate are T2℃ and C2×10 -5 When the temperature is set to / ℃, T2 and C2 may satisfy the relationship (T2-25)×C2≦650. [4] In the dimming film described in any of [1] to [3] above, the glass transition temperatures of the first resin substrate and the second resin substrate may each be 130°C or lower. [5] In the dimming film described in any of [1] to [4] above, the thickness of the first electrode layer and the second electrode layer may each be 200 nm or less. [6] In the dimming film described in any of [1] to [5] above, the thickness of the first resin substrate and the second resin substrate may be 20 μm to 200 μm, respectively. [7] In the dimming film described in any of [1] to [6] above, the first electrode layer and the second electrode layer may contain an indium tin composite oxide. [8]According to another aspect of the present invention, the invention includes preparing a planar light-adjustable film and processing the planar light-adjustable film into a three-dimensional curved shape while heating, wherein the planar light-adjustable film comprises, in this order, a first transparent conductive film, a light-adjustable layer comprising a polymer matrix and a liquid crystal component, and a second transparent conductive film, wherein the first transparent conductive film comprises a first resin substrate and a first electrode layer disposed on the light-adjustable layer side of the first resin substrate, and the second transparent conductive film comprises a second resin substrate and a second electrode layer disposed on the light-adjustable layer side of the second resin substrate, and the glass transition temperature and linear expansion coefficient of the first resin substrate are T1℃ and C1×10 -5 When set to / ℃, T1 and C1 satisfy the relationship (T1-25)×C1≦650, and the glass transition temperature and linear expansion coefficient of the second resin substrate are T2℃ and C2×10 -5 A method for manufacturing a dimmable film having a three-dimensional curved surface is provided, such that when T2 and C2 are set to / ℃, the relationship (T2-25)×C2≦650 is satisfied. [9] In the manufacturing method described in [8] above, the elongation rate of the light-adjusting film when processing it into the three-dimensional curved shape may be 0.1% to 3.0%.

[10] In the manufacturing method described in [8] or [9] above, T1 and C1 may satisfy the relationship 300 < (T1 - 25) × C1, T2 and C2 may satisfy the relationship 300 < (T2 - 25) × C2, the difference between the heating temperature of the dimming film and T1 may be 25°C or less, and the difference between the heating temperature of the dimming film and T2 may be 25°C or less.

[11] In the manufacturing method described in [8] or [9] above, T1 and C1 may satisfy the relationship (T1-25)×C1≦300, T2 and C2 may satisfy the relationship (T2-25)×C2≦300, the heating temperature of the dimming film may be more than 25°C higher than T1, and the heating temperature of the dimming film may be more than 25°C higher than T2.

[12] In the manufacturing method described in any of [8] to

[10] above, the first electrode layer and the second electrode layer may contain an indium tin composite oxide.

Advantages of the Invention

[0007] In the dimming film having a three-dimensional curved surface portion according to an embodiment of the present invention, since the difference in the thickness of the transparent conductive film between the central portion and the end portion of the three-dimensional curved surface portion is controlled within a predetermined range, problems such as wrinkles and cracks in the electrode layer can be suppressed.

Brief Description of the Drawings

[0008] [Figure 1] It is a schematic plan view of a dimming film according to one embodiment of the present invention. [Figure 2] It is a schematic cross-sectional view taken along line II-II of the dimming film shown in FIG. 1. [Figure 3A] It is a schematic diagram for explaining an example of a method of processing a planar dimming film into a three-dimensional curved surface shape. [Figure 3B] It is a figure following FIG. 3A. [Figure 3C] It is a figure following FIG. 3B. [Figure 3D] It is a figure following FIG. 3C.

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. For the sake of clearer explanation, the drawings may schematically represent the width, thickness, shape, etc. of each part compared with the embodiments, but this is merely an example and does not limit the interpretation of the present invention. Also, for the drawings, the same or equivalent elements may be denoted by the same reference numerals, and duplicate explanations may be omitted.

[0010] A. Dimming Film Figure 1 is a schematic plan view of a dimmable film according to one embodiment of the present invention, and Figure 2 is a schematic cross-sectional view of the dimmable film shown in Figure 1 along line II-II. As shown in Figures 1 and 2, the dimmable film 100 is circular in plan view and has a three-dimensional curved shape that is convex upwards. In this specification, a three-dimensional curved surface means a curved surface that is not developable.

[0011] The dimming film 100 includes, in this order, a first transparent conductive film 10, a dimming layer 20, and a second transparent conductive film 30. The first transparent conductive film 10 includes a first resin substrate 12 and a first electrode layer 14 disposed on the dimming layer 20 side of the first resin substrate 12. The second transparent conductive film 30 includes a second resin substrate 32 and a second electrode layer 34 disposed on the dimming layer 20 side of the second resin substrate 32. The dimming layer 20 includes a polymer matrix and a liquid crystal component, and can change the orientation state of the liquid crystal component according to the potential difference between the first electrode layer 14 and the second electrode layer 34.

[0012] As described above, in the dimmable film 100, the orientation state of the liquid crystal components can be changed according to the potential difference between the first electrode layer 14 and the second electrode layer 34, and as a result, the degree of scattering of transmitted light in the dimmable layer 20 can be changed. For example, the dimmable film 100 can switch between a scattering state and a non-scattering state (transparent state) by switching between a state in which no voltage is applied to the first electrode layer 14 and the second electrode layer 34 and a state in which a voltage is applied.

[0013] In one embodiment, the light-adjusting film may have a haze of, for example, 50% or more, preferably 80% or more, and more preferably 95% to 99% in the scattering state. Furthermore, the light-adjusting film may have a lower haze in the transparent state than in the scattering state, for example, less than 20%, preferably 10% or less, and more preferably 1% to 5%. The haze can be measured, for example, according to JIS K 7136.

[0014] The operating voltage of the above-mentioned dimming film, for example, the voltage applied to the dimming film to switch between a scattering state and a non-scattering state (transparent state), may be, for example, 10V to 100V, preferably 40V to 60V. In this specification, "state with applied voltage" means the state in which an operating voltage is applied to the dimming film, which may be, for example, a state in which a voltage of 60V is applied.

[0015] The ratio of the average thickness of the first transparent conductive film and the second transparent conductive film at the center of the three-dimensional curved portion of the light-adjusting film to the average thickness of the first transparent conductive film and the second transparent conductive film at the edge of the three-dimensional curved portion of the light-adjusting film is, for example, 97% or more, preferably 98% or more, more preferably 99% or more, and may be, for example, 100% or less. When the above ratio is within the above range, a light-adjusting film having a three-dimensional curved portion with suppressed wrinkles and / or cracks in the electrode layer can be suitably obtained. The thickness of the center of the three-dimensional curved portion of the first transparent conductive film and the second transparent conductive film is typically the thickness at the geometric center of the three-dimensional curved portion. The thickness of the edge of the three-dimensional curved portion of the first transparent conductive film and the second transparent conductive film is typically the thickness at the outer edge of the three-dimensional curved portion.

[0016] The radius of curvature of the three-dimensional curved surface portion of the above-mentioned dimming film is preferably 60 mm to 320 mm, and may be, for example, 70 mm or more or 90 mm or more, and may be, for example, 250 mm or less or 140 mm or less.

[0017] The above-mentioned dimming film may be entirely a three-dimensional curved surface (three-dimensional curved portion), or it may be partially a three-dimensional curved surface (three-dimensional curved portion) with the remaining portion being planar (planar portion). The planar shape of the dimming film and its three-dimensional curved portion is not limited to a circle, but may be any appropriate shape depending on the application, etc. The major axis of the three-dimensional curved portion in planar view may be, for example, 10 mm to 100 mm, or 30 mm to 70 mm. Here, the major axis of the three-dimensional curved portion in planar view is the distance between the two points that are furthest apart on the outer circumference of the three-dimensional curved portion when viewed from above.

[0018] In one embodiment, the shape of the three-dimensional curved portion of the dimming film may be spherical.

[0019] The thickness of the above-mentioned dimming film (if a flat surface exists, the thickness of the three-dimensional curved surface and the flat surface (the same applies to thickness hereinafter)) is, for example, 50 μm to 450 μm, preferably 50 μm to 200 μm, and more preferably 50 μm to 100 μm.

[0020] A-1. First transparent conductive film The first transparent conductive film 10 includes a first resin substrate 12 and a first electrode layer 14 disposed on the light-adjusting layer 20 side of the first resin substrate 12. The first transparent conductive film 10 may optionally include an alignment film on the light-adjusting layer 20 side of the first electrode layer 14.

[0021] The surface resistance of the first transparent conductive film is preferably 3000 Ω / □ or less, more preferably 1000 Ω / □ or less, and may be, for example, 1 Ω / □ to 1000 Ω / □, 5 Ω / □ to 300 Ω / □, or 10 Ω / □ to 200 Ω / □.

[0022] The haze value of the first transparent conductive film is preferably 20% or less, more preferably 10% or less, and even more preferably 0.1% to 10%.

[0023] The total light transmittance of the first transparent conductive film is preferably 40% or more, more preferably 60% or more, and even more preferably 80% or more. The total light transmittance can be measured, for example, at a measurement wavelength of 380 nm to 780 nm in accordance with JIS K 7361.

[0024] The thickness of the first transparent conductive film is preferably 20 μm to 200 μm, more preferably 20 μm to 100 μm, and even more preferably 20 μm to 50 μm.

[0025] In the three-dimensional curved surface portion of the above-described dimming film, the ratio of the thickness of the central portion to the thickness of the end portion of the first transparent conductive film is, for example, 97% or more, preferably 98% or more, more preferably 99% or more. The upper limit of the above ratio can be 100% or less.

[0026] The first resin substrate 12 is typically a resin film mainly composed of a thermoplastic resin. Let the glass transition temperature of the first resin substrate be T1 °C and the linear expansion coefficient be C1×10 -5 / °C. In this case, it is preferable that T1 and C1 satisfy the relationship of (T1 - 25)×C1 ≤ 650. Since the first resin substrate whose glass transition temperature and linear expansion coefficient satisfy the above relationship is excellent in the uniformity of elongation during curved surface processing, the effects of the present invention can be preferably obtained. More preferably, T1 and C1 satisfy the relationship of 20 ≤ (T1 - 25)×C1 ≤ 300, and still more preferably, they satisfy the relationship of 100 ≤ (T1 - 25)×C1 ≤ 200.

[0027] The glass transition temperature of the first resin substrate can be, for example, 130 °C or less, preferably 60 °C to 120 °C, more preferably 70 °C to 100 °C. Since the first resin substrate having a glass transition temperature within the above range has good uniformity of elongation during curved surface processing, the effects of the present invention can be preferably obtained.

[0028] The linear expansion coefficient of the first resin substrate is, for example, 2.0×10 -5 / °C to 7.0×10 -5 / °C, preferably 2.0×10 -5 / °C to 6.0×10 -5 / °C, more preferably 2.0×10 -5 / °C to 5.0×10 -5 / °C. Since the first resin substrate having a linear expansion coefficient within the above range has good uniformity of elongation during curved surface processing, the effects of the present invention can be preferably obtained.

[0029] Examples of thermoplastic resins included in the first resin substrate include polyester resins such as polyethylene terephthalate (PET) and polybutylene naphthalate (PEN), acrylic resins such as polymethyl (meth)acrylate, acetylcellulose resins such as triacetylcellulose (TAC), and cycloolefin polymers (COP). These resins may be used individually or in combination of two or more.

[0030] The thickness of the first resin substrate is preferably 20 μm to 200 μm, more preferably 20 μm to 100 μm, and even more preferably 20 μm to 50 μm.

[0031] The first electrode layer 14 can be formed using metal oxides such as zinc oxide (ZnO), tin oxide (SnO2), indium tin composite oxide (ITO), indium zinc composite oxide (IZO), indium gallium zinc composite oxide (IGZO), indium gallium composite oxide (IGO), and antimony tin composite oxide (ATO). The metal oxide may be amorphous or crystalline. The first electrode layer can also be formed from metal nanowires such as silver nanowires (AgNW), carbon nanotubes (CNTs), organic conductive films, metal layers, or laminates thereof. Preferably, the first electrode layer contains ITO. While electrode layers containing ITO tend to have excellent transparency but low elongation, according to embodiments of the present invention, even when using an electrode layer containing ITO, a photochromic film having a three-dimensional curved surface and suppressing crack formation can be suitably obtained. The first electrode layer can be patterned into a desired shape depending on the purpose.

[0032] The thickness of the first electrode layer is, for example, 10 nm or more, preferably 15 nm or more. The thickness of the first electrode layer is, for example, 200 nm or less, preferably 150 nm or less, and more preferably 100 nm or less.

[0033] The first electrode layer is formed on one side of the first resin substrate, for example, by sputtering. After forming an amorphous oxide layer by sputtering, it can be converted into a crystalline oxide layer by annealing. Annealing is performed, for example, by heat treatment at 120°C to 300°C for 10 to 120 minutes.

[0034] A-2. Dimming layer The light-adjusting layer 20 includes a polymer matrix and liquid crystal components. Preferred examples of the light-adjusting layer include a polymer-dispersed liquid crystal (PDLC) layer and a polymer-network liquid crystal (PNLC) layer. The PDLC layer has a structure in which droplets of liquid crystal components are dispersed in a polymer matrix. The PNLC film has a continuous structure in which liquid crystal components fill the gaps in a network-like polymer matrix.

[0035] Examples of resins for forming polymer matrices include thermoplastic resins such as urethane resins, polyvinyl alcohol resins, polyethylene resins, polypropylene resins, and acrylic resins. Also, examples of resins for forming polymer matrices include curable resins such as liquid crystal polymers, acrylic resins, silicone resins, epoxy resins, fluororesins, polyester resins, and polyimide resins. These resins may be used individually or in combination of two or more.

[0036] The content of the polymer matrix in the light-adjusting layer may be, for example, 30% to 70% by weight, preferably 35% to 65% by weight, and more preferably 40% to 60% by weight.

[0037] Examples of liquid crystal components include nematic liquid crystal components, smectic liquid crystal components, and cholesteric liquid crystal components. Among these, nematic liquid crystal components are preferred.

[0038] The liquid crystal component content in the light-adjusting layer may be, for example, 30% to 70% by weight, preferably 35% to 65% by weight, and more preferably 40% to 60% by weight.

[0039] When the light-adjusting layer is a PDLC layer, the average particle size of the liquid crystal component droplets may be, for example, 0.3 μm to 9 μm, preferably 0.4 μm to 8 μm. If the average particle size of the droplets is too small, the droplets will be smaller than the wavelength of light, causing the light to pass through the droplets without scattering, resulting in a problem where sufficient haze cannot be obtained. Conversely, if the average particle size of the droplets is too large, the droplets will be larger than the wavelength of light, resulting in a problem where sufficient haze cannot be obtained. The above average particle size of the droplets is the volume-average particle size of the droplets when viewed from a direction perpendicular to the main surface of the PDLC film.

[0040] The light-adjusting layer may further contain any suitable materials such as dichroic dyes, dispersants, and crosslinking agents, depending on the purpose.

[0041] The thickness of the light-adjusting layer is, for example, 50 μm or less, preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less, and may be, for example, 3 μm or more or 5 μm or more.

[0042] A-3. Second transparent conductive film The second transparent conductive film 30 includes a second resin substrate 32 and a second electrode layer 34 disposed on the light-adjusting layer 20 side of the second resin substrate 32. The second transparent conductive film may optionally include an alignment film on the light-adjusting layer 20 side of the second electrode layer 34.

[0043] The surface resistance of the second transparent conductive film 30 is preferably 3000 Ω / □ or less, more preferably 1000 Ω / □ or less, and may be, for example, 1 Ω / □ to 1000 Ω / □, 5 Ω / □ to 300 Ω / □, or 10 Ω / □ to 200 Ω / □.

[0044] The haze value of the second transparent conductive film is preferably 20% or less, more preferably 10% or less, and even more preferably 0.1% to 10%.

[0045] The total light transmittance of the second transparent conductive film is preferably 40% or more, more preferably 60% or more, and even more preferably 80% or more.

[0046] The thickness of the second transparent conductive film is preferably 20 μm to 200 μm, more preferably 20 μm to 100 μm, and even more preferably 20 μm to 50 μm.

[0047] In the three-dimensional curved portion of the above-mentioned dimming film, the ratio of the thickness of the central portion to the thickness of the edge portion of the second transparent conductive film is, for example, 97% or more, preferably 98% or more, and more preferably 99% or more. The upper limit of the above ratio may be 100% or less.

[0048] The second resin substrate is typically a resin film mainly composed of thermoplastic resin. The glass transition temperature of the second resin substrate is T2°C, and the coefficient of linear expansion is C2 × 10⁻⁶. -5 When the temperature is set to / ℃, it is preferable that T2 and C2 satisfy the relationship (T2-25)×C2≦650. A second resin substrate whose glass transition temperature and coefficient of linear expansion satisfy the above relationship can exhibit excellent uniformity of elongation during curved surface processing, thus allowing the effects of the present invention to be favorably obtained. T2 and C2 more preferably satisfy the relationship 20≦(T2-25)×C2≦300, and even more preferably 100≦(T2-25)×C2≦200.

[0049] The glass transition temperature of the second resin substrate may be, for example, 130°C or less, preferably 60°C to 120°C, and more preferably 70°C to 100°C. Since the second resin substrate having a glass transition temperature within the above range exhibits good uniformity of elongation during curved surface processing, the effects of the present invention can be suitably obtained.

[0050] The coefficient of linear expansion of the second resin substrate is, for example, 2.0 × 10⁻⁶. -5 / ℃~7.0×10 -5 / ℃, preferably 2.0 × 10 -5 / ℃~6.0×10 -5 / ℃, more preferably 2.0 × 10 -5 / ℃~5.0×10-5 It can be / ℃. The second resin substrate, whose coefficient of linear expansion is within the above range, exhibits good uniformity of elongation during curved surface processing, thus allowing the effects of the present invention to be suitably obtained.

[0051] Examples of thermoplastic resins included in the second resin substrate include those similar to those that may be included in the first resin substrate.

[0052] The thickness of the second resin substrate is preferably 20 μm to 200 μm, more preferably 20 μm to 100 μm, and even more preferably 20 μm to 50 μm.

[0053] The same explanation as for the first electrode layer can be applied to the second electrode layer 34. The second electrode layer may have the same configuration (forming material, thickness, etc.) as the first electrode layer, or it may have a different configuration.

[0054] B. Method for manufacturing dimmable film According to one aspect of the present invention, a method for manufacturing a light-adjustable film having a three-dimensional curved surface is provided. The method for manufacturing the light-adjustable film includes preparing a planar light-adjustable film (step I) and processing the planar light-adjustable film into a three-dimensional curved shape while heating it (step II). According to the method for manufacturing the light-adjustable film, the light-adjustable film having a three-dimensional curved surface described in section A can be suitably obtained.

[0055] B-1. Process I In step I, a flat light-adjusting film is prepared.

[0056] A planar light-adjusting film comprises, in this order, a first transparent conductive film, a light-adjusting layer containing a polymer matrix and a liquid crystal component, and a second transparent conductive film, wherein the first transparent conductive film includes a first resin substrate and a first electrode layer disposed on the light-adjusting layer side of the first resin substrate, and the second transparent conductive film includes a second resin substrate and a second electrode layer disposed on the light-adjusting layer side of the second resin substrate.

[0057] The same explanations as those for the first transparent conductive film, the light-adjusting layer, and the second transparent conductive film in a planar light-adjusting film described in Section A, apply to the first transparent conductive film, the light-adjusting layer, and the second transparent conductive film in a light-adjusting film having a three-dimensional curved surface. However, strictly speaking, since each component is stretched from a planar shape to a three-dimensional curved shape by the curved surface processing in step II, the thickness of each component in the planar light-adjusting film may be greater than or equal to the thickness of the corresponding component in the three-dimensional curved surface in the light-adjusting film described in Section A. Furthermore, the thickness of each component in the planar light-adjusting film may be uniform across the plane. The ratio of the minimum and maximum in-plane thickness of each component in the planar light-adjusting film (minimum / maximum × 100) may be, for example, 99% to 100%.

[0058] If the light-adjustable film is a PDLC film or a PNLC film, these light-adjustable films can be obtained by manufacturing methods known to those skilled in the art.

[0059] For example, a PDLC film can be obtained by a manufacturing method that includes preparing a coating solution containing a first transparent conductive film, a second transparent conductive film, a polymer matrix forming resin, a liquid crystal component, and a dispersion medium; applying the coating solution to the electrode layer surface of one of the transparent conductive films to form a coating layer; drying the coating layer to obtain a PDLC layer in which droplets of the liquid crystal component are dispersed in the polymer matrix; and laminating the other transparent conductive film on the PDLC layer. The coating solution is preferably an emulsion coating solution in which liquid crystal particles containing the liquid crystal component are dispersed in a dispersion medium. Water or a mixed solvent of water and a water-miscible organic solvent can preferably be used as the dispersion medium.

[0060] For example, a PDLC film can be obtained by a manufacturing method that includes: preparing a coating solution containing a first transparent conductive film, a second transparent conductive film, a curable resin for forming a polymer matrix, a liquid crystal component, and a polymerization initiator; applying the coating solution to the electrode layer surface of one transparent conductive film to form a coating layer; laminating the other transparent conductive film on the coating layer to form a laminate; and polymerizing the curable resin to form a polymer matrix, and obtaining a PDLC layer by phase separation between the polymer matrix and the liquid crystal component. Alternatively, the coating solution may be filled between the first transparent conductive film and the second transparent conductive film, which are laminated with a spacer in between, and then phase separation by polymerization may be performed.

[0061] B-2. Process II In step II, the planar light-adjusting film is heated and processed into a three-dimensional curved shape. Step II may include, for example, applying the heated planar light-adjusting film to a curved mold and causing plastic deformation.

[0062] Figures 3A to 3D are schematic diagrams illustrating an example of a method for processing a planar light-adjusting film into a three-dimensional curved surface shape according to one embodiment of the present invention.

[0063] In Figure 3A, the dimming film 100 is placed on a sample stage 270 located between the upper chamber 210 and the lower chamber 220. The upper chamber 210 houses a height-adjustable heating plate 230 and a convex mold 240 positioned in a recess 230a in the center of the heating plate 230. The convex mold 240 has a convex curved surface that protrudes downward. The lower chamber 220 houses a concave mold 250 and a support base 260 that supports the concave mold 250. The upper surface of the concave mold 250 is a concave curved surface corresponding to the convex curved surface of the convex mold 240. Openings are provided in the sample stage 270 at locations corresponding to the convex mold 240 and the concave mold 250 in a plan view.

[0064] Next, as shown in Figure 3B, the heating plate 230 and the convex mold 240 are lowered and brought into contact with the dimming film 100. At the time of contact with the dimming film 100, the heating plate 230 and the convex mold 240 are heated to a predetermined temperature. Contact with the heated heating plate 230 and the convex mold 240 heats the dimming film 100, making it easier to deform. At this time, the upper chamber 210 may be under reduced pressure, for example, in a vacuum. The lower chamber 220 may be under atmospheric pressure or under pressurized pressure.

[0065] The heating temperature T3 of the heating plate 230 and the convex mold 240 (and consequently the heating temperature of the dimming film 100) can be set to any suitable temperature. For example, if (T1-25)×C1 and (T2-25)×C2 exceed 300, the heating temperature T3 can be set such that the difference between the glass transition temperature T1 of the first resin substrate and the glass transition temperature T2 of the second resin substrate is 25°C or less, preferably 20°C or less, and more preferably 15°C or less. Also, for example, if (T1-25)×C1 and (T2-25)×C2 are 300 or less (e.g., 200 or less), the heating temperature T3 can be set to be more than 25°C higher than T1 and T2, for example, 30°C to 70°C or 40°C to 70°C higher. A resin substrate with a low Tg and a small coefficient of linear expansion (e.g., Tg is 90°C or less and the coefficient of linear expansion is 3×10) -5 The resin substrate (with a temperature of / °C or lower) can be heated to a temperature sufficiently higher than Tg to improve elongation and uniformity of elongation during curved surface processing. In one embodiment, the heating temperature of the dimming film 100 is, for example, 100°C to 150°C, preferably 105°C to 145°C.

[0066] Next, as shown in Figure 3C, the convex mold 240 is lowered further to press the dimming film 100 against the concave surface of the concave mold 250. As a result, a portion of the dimming film 100 is sandwiched between the convex surface of the convex mold 240 and the concave surface of the concave mold 250, and is deformed into a curved shape corresponding to those surfaces (press molding). At this time, the upper chamber 210 may be under reduced pressure, and the lower chamber 220 may be under atmospheric pressure or under pressurized pressure.

[0067] If necessary, a portion of the dimming film 100 may be sandwiched between the convex surface of the convex mold 240 and the concave surface of the concave mold 250, and then the upper chamber 210 may be pressurized and the lower chamber 220 may be depressurized. By pressurizing, the dimming film 100 can be further pressed into the concave surface of the concave mold 250 (pressure molding).

[0068] Subsequently, the pressure inside the upper chamber 210 and the lower chamber 220 is returned to atmospheric pressure, the heating of the heating plate 230 and the convex mold 240 is terminated, and they are raised to separate them from the dimming film 100 (Figure 3D).

[0069] As described above, a dimmable film having a three-dimensional curved surface can be obtained. If necessary, any unnecessary portions may be cut off from the dimmable film after the curved surface processing.

[0070] The elongation rate of the dimming film due to the curved surface processing is, for example, 0.1% to 3.0%, and may be 0.5% or more or 1.0% or more, and may be 2.5% or less or 2.0% or less. The above elongation rate represents the maximum value of the ratio (elongation rate (%) = (La - Lb) / Lb × 100) of the length La between any two points on the outer circumference of the three-dimensional curved surface formed by the curved surface processing to the length Lb between the corresponding two points in the dimming film before the curved surface processing. [Examples]

[0071] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way to these examples. The measurement methods for each characteristic are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight. <thickness> The film was cut vertically using a microtome under cooling conditions, and the cross-section of the film was observed using a digital inverted microscope (Nikon ESLIPSE LV100) to measure its thickness. <Volume-average particle diameter of liquid crystal particles in liquid crystal emulsion> The volume-average particle size was calculated using a particle size distribution analyzer (Microtrac, "MT3300EX II"). <Average particle size of resin particles> A sample was prepared by adding a few drops of resin dispersion to 100 ml of water. Using a dynamic light scattering particle size distribution analyzer (Microtrac, name "Nanotrac150"), the sample was placed in the instrument's measurement holder, and after confirming that the concentration was measurable on the instrument's monitor, the measurement was performed. <Glass transition temperature> The glass transition temperature was measured in accordance with JIS K 7121. <Coefficient of linear expansion> The coefficient of linear thermal expansion was measured in accordance with JIS K 7197.

[0072] [Example 1] (Transparent conductive film) PET film as a resin substrate (Tg: 85℃, coefficient of linear expansion: 2.2 × 10⁻⁶) -5 An ITO layer (thickness: 30 nm) was formed on one side of a material ( / °C) by sputtering. This resulted in a transparent conductive film having the structure of [resin substrate / electrode layer (surface resistance: 100 Ω / □)]. The above transparent conductive film was used as the first transparent conductive film and the second transparent conductive film.

[0073] (Emulsion coating liquid) 58.8 parts of liquid crystal component (JNC Corporation, product name "JC-5240XX", positive type liquid crystal, birefringence Δn=0.252 (ne=1.766, no=1.514), viscosity=75 mPa·s), 40.0 parts of pure water, and 1.2 parts of dispersant (Daiichi Kogyo Seiyaku Co., Ltd., "Neugen ET159") were mixed and stirred in a homogenizer at 100 rpm for 10 minutes to achieve a rough dispersion. The rough dispersion was then passed through a separation membrane with a uniform particle size distribution (SPG Techno Co., Ltd., "SPG Pumping Connector", pore size 10 μm) at a flow rate of 80 mL / min / cm² at room temperature, allowing the liquid to pass from the outside to the inside of the membrane. 2 The liquid was transmitted at a certain speed. This operation was repeated five times. The volume-average particle size of the liquid crystal particles in the resulting liquid crystal emulsion was 3.0 μm. An emulsion coating solution was obtained by mixing 30.8 parts of the above liquid crystal emulsion, 44.3 parts of an aqueous dispersion of polyether-based polyurethane resin (manufactured by DSM, trade name "NeoRez R967", refractive index 1.49, average polymer particle size: 80 nm, solids content: 40 wt%), 0.2 parts of a leveling agent (manufactured by DIC, product name "F-444"), 1.3 parts of a crosslinking agent (tris[3-(2-methylaziridin-1-yl)propionic acid]=propyridinetrimethyl) and 22.0 parts of pure water.

[0074] (PDLC layer) The emulsion coating solution was applied to the first electrode layer surface of the first transparent conductive film using a wire bar to form a coating layer with a thickness of 30 μm. Next, the coating layer was dried at 25°C for 60 minutes to form a PDLC layer with a thickness of 8 μm.

[0075] (PDLC film) A second transparent conductive film was laminated on top of the PDLC layer using a laminator while applying a lamination pressure of 0.4 MPa / m. At this time, the second transparent conductive film was laminated so that the second electrode layer surface faced the PDLC layer side. As described above, a planar PDLC film having the configuration of [first transparent conductive film / PDLC layer / second transparent conductive film] was obtained.

[0076] (Curved surface processing) (1) The PDLC film was placed on a sample stage positioned between the upper and lower chambers. The upper chamber houses a height-adjustable heating plate and a convex mold positioned in the central recess of the heating plate. The lower chamber houses a concave mold and a support base for supporting the concave mold. The upper surface of the concave mold is a circular surface with a diameter (φ) of 48.3 mm in plan view and a concave curved surface with a radius of curvature of 99.8 mm. The lower surface of the convex mold is a convex curved surface corresponding to the concave curved surface of the concave mold. Openings are provided in the parts of the sample stage corresponding to the convex and concave molds. (2) The heating plate and the convex mold were heated to 145°C. (3) The heated heating plate and the convex mold were lowered and brought into contact with the PDLC film from above. (4) By creating a vacuum in the upper chamber, the PDLC film was strongly adsorbed onto the heating plate, raising the film temperature to 145°C. (5) The convex mold was lowered further and the PDLC film was pressed against the concave surface of the concave mold. (6) By creating a vacuum in the lower chamber, the PDLC film was made to conform even more closely to the concave surface of the concave mold. (7) Compressed air was introduced into the upper chamber and pressurized to perform further pressure forming. (8) The heating plate and the convex mold were returned to room temperature, and the upper and lower chambers were returned to atmospheric pressure, after which the PDLC film was removed.

[0077] As described above, a PDLC film was obtained that was circular in plan view with a diameter (φ) of 48.3 mm and had a three-dimensional curved surface with a radius of curvature of 99.8 mm. The elongation rate of the PDLC film due to the curved surface processing (specifically, the elongation rate of the portion corresponding to the diameter of the circular area in plan view) was 1%.

[0078] [Example 2] Polymethyl methacrylate (PMMA) film as the resin substrate (Tg: 120℃, coefficient of linear expansion: 6.5 × 10⁻⁶) -5Except for using a temperature of 48.3 mm (φ) and heating the PDLC film to 115°C during curved surface processing, the procedure was the same as in Example 1 to obtain a PDLC film having a circular shape with a diameter (φ) of 48.3 mm in plan view and a three-dimensional curved surface with a radius of curvature of 99.8 mm.

[0079] [Comparative Example 1] Polycarbonate (PC) film as the resin substrate (Tg: 150℃, coefficient of linear expansion: 6.9 × 10) -5 Except for using a temperature of 48.3 mm (φ) and heating the PDLC film to 115°C during curved surface processing, the procedure was the same as in Example 1 to obtain a PDLC film having a circular shape with a diameter (φ) of 48.3 mm in plan view and a three-dimensional curved surface with a radius of curvature of 99.8 mm.

[0080] [Comparative Example 2] A PDLC film was obtained in the same manner as in Comparative Example 1, except that the PDLC film was heated to 145°C during the curved surface processing. The PDLC film had a circular shape with a diameter (φ) of 48.3 mm in plan view and a three-dimensional curved surface with a radius of curvature of 99.8 mm.

[0081] [Comparative Example 3] When the curved surface processing was performed in the same manner as in Example 1, except that the PDLC film was heated to 80°C during the curved surface processing, the resin substrate fractured and the transparent conductive film tore, making it impossible to obtain a PDLC film with a three-dimensional curved surface.

[0082] The appearance of the three-dimensional curved portion of the PDLC film obtained in the examples and comparative examples was visually observed. Furthermore, the cross-section obtained by cutting the three-dimensional curved portion along the thickness direction was observed under a microscope (200x magnification) to check for the presence or absence of cracks. The observation results, along with the thickness of the transparent conductive film, are shown in Table 1. In the table, each thickness for the transparent conductive film is the average value of the thickness of the first transparent conductive film and the thickness of the second transparent conductive film.

[0083] [Table 1] [Industrial applicability]

[0084] The dimming film according to an embodiment of the present invention is suitably used in various devices having a curved shape. [Explanation of Symbols]

[0085] 10 First transparent conductive film, 12 First resin substrate, 14 First electrode layer, 20 Light-adjusting layer, 30 Second transparent conductive film, 32 Second resin substrate, 34 Second electrode layer, 100 Light-adjusting film

Claims

1. A light-adjusting film comprising, in this order, a first transparent conductive film, a light-adjusting layer containing a polymer matrix and a liquid crystal component, and a second transparent conductive film, and having a three-dimensional curved surface portion, The first transparent conductive film includes a first resin substrate and a first electrode layer disposed on the light-adjusting layer side of the first resin substrate. The second transparent conductive film includes a second resin substrate and a second electrode layer disposed on the light-adjusting layer side of the second resin substrate. The ratio of the average thickness of the central portion to the average thickness of the edge portion of the three-dimensional curved portion of the first transparent conductive film and the second transparent conductive film is 97% or more. Dimming film.

2. The dimmable film according to claim 1, wherein the radius of curvature of the three-dimensional curved surface portion is 60 mm to 320 mm.

3. The glass transition temperature and linear expansion coefficient of the first resin substrate are defined as T1°C and C1×10, respectively. －５ When the temperature is set to / °C, T1 and C1 satisfy the relationship (T1 - 25) × C1 ≤ 650. The glass transition temperature and linear expansion coefficient of the second resin substrate are, respectively, T2°C and C2×10 －５ The light-adjusting film according to claim 1, wherein when the temperature is set to / °C, T2 and C2 satisfy the relationship (T2 - 25) × C2 ≤ 650.

4. The light-adjusting film according to claim 1, wherein the glass transition temperatures of the first resin substrate and the second resin substrate are each 130°C or lower.

5. The light-adjusting film according to claim 1, wherein the thickness of the first electrode layer and the second electrode layer are each 200 nm or less.

6. The light-adjusting film according to claim 1, wherein the thickness of the first resin substrate and the second resin substrate are each 20 μm to 200 μm.

7. The light-adjustable film according to claim 1, wherein the first electrode layer and the second electrode layer contain an indium tin composite oxide.

8. Prepare a flat dimming film, and This includes processing the aforementioned planar light-adjusting film into a three-dimensional curved shape while heating it, The planar light-adjusting film comprises, in this order, a first transparent conductive film, a light-adjusting layer containing a polymer matrix and a liquid crystal component, and a second transparent conductive film. The first transparent conductive film includes a first resin substrate and a first electrode layer disposed on the light-adjusting layer side of the first resin substrate. The second transparent conductive film includes a second resin substrate and a second electrode layer disposed on the light-adjusting layer side of the second resin substrate. The glass transition temperature and linear expansion coefficient of the first resin substrate are defined as T1°C and C1×10, respectively. －５ When the temperature is set to / °C, T1 and C1 satisfy the relationship (T1 - 25) × C1 ≤ 650. The glass transition temperature and linear expansion coefficient of the second resin substrate are, respectively, T2°C and C2×10 －５ A method for manufacturing a light-adjustable film having a three-dimensional curved surface portion, wherein T2 and C2 satisfy the relationship (T2 - 25) × C2 ≤ 650 when the temperature is set to / °C.

9. The manufacturing method according to claim 8, wherein the elongation rate of the light-adjusting film when processed into the three-dimensional curved shape is 0.1% to 3.0%.

10. The relationship T1 and C1 satisfy the relationship 300 < (T1 - 25) × C1, The relationship T2 and C2 satisfy the relationship 300 < (T2 - 25) × C2, The difference between the heating temperature of the dimming film and T1 is 25°C or less. The manufacturing method according to claim 8, wherein the difference between the heating temperature of the dimming film and T2 is 25°C or less.

11. The above T1 and the above C1 satisfy the relationship (T1 - 25) × C1 ≤ 300, The relationship T2 and C2 satisfy (T2 - 25) × C2 ≤ 300, The heating temperature of the dimming film is more than 25°C higher than T1. The manufacturing method according to claim 8, wherein the heating temperature of the dimming film is more than 25°C higher than T2.

12. The manufacturing method according to claim 8, wherein the first electrode layer and the second electrode layer contain an indium tin composite oxide.

Images