Light control film having three-dimensional curved surface and method for producing the same

Abstract

To provide a light-control film having a three-dimensional curved surface portion, which is suppressed from problems such as wrinkles and cracks in the electrode layer. [Solution] A light-controlling film having a three-dimensional curved surface portion, comprising a first transparent conductive film, a light-controlling layer containing a polymer matrix and a liquid crystal component, and a second transparent conductive film, in this order, wherein the first transparent conductive film comprises a first resin substrate and a first electrode layer arranged on the light-controlling layer side of the first resin substrate, and the second transparent conductive film comprises a second resin substrate and a second electrode layer arranged on the light-controlling layer side of the second resin substrate, and the ratio of the average thickness of the central portion to the average thickness of the edges 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 control film having a three-dimensional curved surface portion and a method for producing the same. [Background technology]

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

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

[0004] [Patent Document 1] Patent No. 7099578 Summary of the Invention [Problem to be solved by the invention]

[0005] During curved surface processing, a light control film is stretched from a flat shape to a three-dimensional curved shape, which can cause problems such as wrinkles and cracks in the electrode layer of the transparent conductive film. Therefore, a main object of the present invention is to provide a light control 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, there is provided a light control film having a three-dimensional curved surface portion, the light control film including, in this order, a first transparent conductive film, a light control layer including 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 arranged on the light control layer side of the first resin substrate, and the second transparent conductive film includes a second resin substrate and a second electrode layer arranged on the light control 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 portions of the three-dimensional curved surface portion of the first transparent conductive film and the second transparent conductive film is 97% or more. [2] In the light control film described in [1] above, the radius of curvature of the three-dimensional curved surface portion may be 60 mm to 320 mm. [3] In the light-control film according to the above [1] or [2], the glass transition temperature and linear expansion coefficient of the first resin substrate are T1°C and C1×10, respectively. -5 / °C, T1 and C1 may satisfy the relationship (T1-25) × C1≦650, and the glass transition temperature and linear expansion coefficient of the second resin base material may be T2°C and C2×10 -5 / °C, T2 and C2 may satisfy the relationship (T2-25) × C2 ≦ 650. [4] In the light control film according to any one of [1] to [3] above, the first resin substrate and the second resin substrate may each have a glass transition temperature of 130° C. or lower. [5] In the light control film according to any one of [1] to [4] above, the thickness of each of the first electrode layer and the second electrode layer may be 200 nm or less. [6] In the light control film according to any one of [1] to [5] above, the first resin substrate and the second resin substrate may each have a thickness of 20 μm to 200 μm. [7] In the light-control film according to any one 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, a method for producing a light control film includes preparing a flat light control film and processing the flat light control film into a three-dimensional curved shape while heating it, wherein the flat light control film includes a first transparent conductive film, a light control layer including a polymer matrix and a liquid crystal component, and a second transparent conductive film, in this order; the first transparent conductive film includes a first resin substrate and a first electrode layer disposed on the first resin substrate on the side of the light control layer; the second transparent conductive film includes a second resin substrate and a second electrode layer disposed on the second resin substrate on the side of the light control layer; and the glass transition temperature and linear expansion coefficient of the first resin substrate are set to T1°C and C1×10, respectively. -5 / °C, 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°C and C2 × 10 -5 / °C, T2 and C2 satisfy the relationship (T2-25) x C2 ≦ 650. [9] In the manufacturing method described in [8] above, the elongation of the light control film when processed 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 light-control film and T1 may be 25°C or less, and the difference between the heating temperature of the light-control 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 light control film may be more than 25°C higher than T1, and the heating temperature of the light control film may be more than 25°C higher than T2.

[12] In the manufacturing method according to any one of the above [8] to

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

[0007] In a light-controlling film having a three-dimensional curved surface according to an embodiment of the present invention, the difference in thickness of the transparent conductive film between the center and end portions of the three-dimensional curved surface is controlled within a predetermined range, thereby suppressing problems such as wrinkles and cracks in the electrode layer. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic plan view of a light management film according to one embodiment of the present invention. [Figure 2] 2 is a schematic cross-sectional view of the light control film shown in FIG. 1 taken along line II-II. [Figure 3A] FIG. 1 is a schematic diagram illustrating an example of a method for processing a flat light control film into a three-dimensional curved shape. [Figure 3B] This is a continuation of Figure 3A. [Figure 3C] This is a continuation of Figure 3B. [Figure 3D] This is a continuation of Figure 3C. DETAILED DESCRIPTION OF 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. In order to clarify the description, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in the drawings, the same or equivalent elements are given the same reference numerals, and duplicate explanations may be omitted.

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

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

[0012] As described above, in the light control film 100, the orientation state of the liquid crystal component can be changed depending on 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 light control layer 20 can be changed. For example, the light control film 100 can be switched 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 management 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 management film may have a lower haze in the transparent state than in the scattering state, for example, a haze of less than 20%, preferably 10% or less, and more preferably 1% to 5%. Haze can be measured, for example, according to JIS K 7136.

[0014] The operating voltage of the light management film, for example, the voltage applied to the light management film to switch between a scattering state and a non-scattering state (transparent state), can be, for example, 10 V to 100 V, preferably 40 V to 60 V. In this specification, "a state in which a voltage is applied" means a state in which an operating voltage is applied to the light management film, and can be, for example, a state in which a voltage of 60 V 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 control film to the average thickness of the first transparent conductive film and the second transparent conductive film at the edges of the three-dimensional curved portion can be, for example, 97% or more, preferably 98% or more, more preferably 99% or more, and can be, for example, 100% or less. When this ratio is within the above range, a light control film having a three-dimensional curved portion in which wrinkles and / or cracks in the electrode layer are suppressed can be suitably obtained. Note that 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. Furthermore, 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 peripheral edge of the three-dimensional curved portion.

[0016] The radius of curvature of the three-dimensional curved surface portion of the light control 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 light control film may have a three-dimensional curved shape (three-dimensional curved surface portion) as a whole, or may have a three-dimensional curved shape (three-dimensional curved surface portion) with the remaining portion being flat (flat surface portion). The planar shape of the light control film and its three-dimensional curved surface portion is not limited to a circular shape, and may be any appropriate shape depending on the application, etc. The major axis of the three-dimensional curved surface portion in planar view is, for example, 10 mm to 100 mm, and may be 30 mm to 70 mm. Here, the major axis of the three-dimensional curved surface portion in planar view is the distance between the two most distant points on the periphery of the three-dimensional curved surface portion when viewed from above.

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

[0019] The thickness of the light control film (if a flat portion exists, the thickness of each of the three-dimensional curved portion and the flat portion (the same applies hereinafter to thickness)) 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 switchable layer 20 side of the first resin substrate 12. The first transparent conductive film 10 may include an alignment film on the switchable layer 20 side of the first electrode layer 14, as needed.

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

[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, in accordance with JIS K 7361 at a measurement wavelength of 380 nm to 780 nm.

[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 light control film, the ratio of the thickness of the central portion to the thickness of the edge portion of the first transparent conductive film is, for example, 97% or more, preferably 98% or more, and more preferably 99% or more, and the upper limit of this ratio can be 100% or less.

[0026] The first resin substrate 12 is typically a resin film containing a thermoplastic resin as a main component. The glass transition temperature of the first resin substrate is T1°C, and the linear expansion coefficient is C1×10 -5 / °C, it is preferable that T1 and C1 satisfy the relationship (T1-25) × C1 ≦ 650. A first resin substrate whose glass transition temperature and linear expansion coefficient satisfy the above relationship exhibits excellent uniformity in elongation during curved surface processing, and therefore the effects of the present invention can be suitably obtained. T1 and C1 more preferably satisfy the relationship 20 ≦ (T1-25) × C1 ≦ 300, and even more preferably satisfy the relationship 100 ≦ (T1-25) × C1 ≦ 200.

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

[0028] The linear expansion coefficient of the first resin base material is, for example, 2.0×10 -5 / ℃~7.0×10 -5 / °C, preferably 2.0 x 10 -5 / ℃~6.0×10 -5 / °C, more preferably 2.0 × 10 -5 / ℃~5.0×10 -5 / ° C. The first resin substrate having a linear expansion coefficient within the above range exhibits good uniformity in elongation during curved surface processing, and therefore the effects of the present invention can be suitably obtained.

[0029] Examples of the thermoplastic resin contained in the first resin substrate include polyester resins such as polyethylene terephthalate (PET) and polybutylene naphthalate (PEN), acrylic resins such as polymethyl (meth)acrylate, acetyl cellulose resins such as triacetyl cellulose (TAC), cycloolefin polymers (COP), etc. One of the above resins may be used alone, or two or more may be used in combination.

[0030] The thickness of the first resin base material 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 a metal oxide such as zinc oxide (ZnO), tin oxide (SnO), indium tin composite oxide (ITO), indium zinc composite oxide (IZO), indium gallium zinc composite oxide (IGZO), indium gallium composite oxide (IGO), or antimony tin composite oxide (ATO). The metal oxide may be an amorphous oxide or a crystalline oxide. The first electrode layer can also be formed of metal nanowires such as silver nanowires (AgNW), carbon nanotubes (CNT), an organic conductive film, a metal layer, or a laminate thereof. Preferably, the first electrode layer contains ITO. Although electrode layers containing ITO have excellent transparency but tend to have low elongation, according to embodiments of the present invention, a light control film having a three-dimensional curved surface and suppressing the occurrence of cracks can be preferably obtained even when an electrode layer containing ITO is used. 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, and for example, 200 nm or less, preferably 150 nm or less, more preferably 100 nm or less.

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

[0034] A-2. Light-controlling layer The light-controlling layer 20 contains a polymer matrix and a liquid crystal component. Preferred examples of the light-controlling layer include a polymer-dispersed liquid crystal (PDLC) layer and a polymer-network liquid crystal (PNLC) layer. A PDLC layer has a structure in which droplets of a liquid crystal component are dispersed in a polymer matrix. A PNLC film has a continuous structure in which the liquid crystal component is filled into the gaps in a network-like polymer matrix.

[0035] Examples of the polymer matrix-forming resin include thermoplastic resins such as urethane resins, polyvinyl alcohol resins, polyethylene resins, polypropylene resins, and acrylic resins. Examples of the polymer matrix-forming resin include curable resins such as liquid crystal polymers, acrylic resins, silicone resins, epoxy resins, fluorine-containing resins, polyester resins, and polyimide resins. The above resins may be used alone or in combination of two or more.

[0036] The content of the polymer matrix in the light-controlling layer can 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 the liquid crystal component include a nematic liquid crystal component, a smectic liquid crystal component, a cholesteric liquid crystal component, etc. Among these, a nematic liquid crystal component is preferably used.

[0038] The content of the liquid crystal component in the light-modulating layer can 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-controlling layer is a PDLC layer, the average particle diameter of the liquid crystal component droplets can be, for example, 0.3 μm to 9 μm, preferably 0.4 μm to 8 μm. If the average particle diameter of the droplets is too small, the droplets are smaller than the wavelength of light, so light passes through the droplets without scattering, which can result in a problem of insufficient haze being obtained. On the other hand, if the average particle diameter of the droplets is too large, the droplets are too large compared to the wavelength of light, which can result in a problem of insufficient haze being obtained. The above average particle diameter of the droplets is the volume-average particle diameter of the droplets when viewed from a direction perpendicular to the main surface of the PDLC film.

[0040] The light-modulating layer may further contain any appropriate material such as a dichroic dye, a dispersant, a crosslinking agent, etc., depending on the purpose.

[0041] The thickness of the light-modulating 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 switchable layer 20 side of the second resin substrate 32. The second transparent conductive film may include an alignment film on the switchable layer 20 side of the second electrode layer 34, as needed.

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

[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 surface portion of the light control 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, and the upper limit of this ratio can be 100% or less.

[0048] The second resin substrate is typically a resin film containing a thermoplastic resin as a main component. The glass transition temperature of the second resin substrate is T2°C, and the linear expansion coefficient is C2×10 -5 / °C, it is preferable that T2 and C2 satisfy the relationship (T2-25) × C2 ≦ 650. A second resin substrate whose glass transition temperature and linear expansion coefficient satisfy the above relationship can exhibit excellent uniformity in elongation during curved surface processing, and therefore the effects of the present invention can be suitably obtained. T2 and C2 more preferably satisfy the relationship 20 ≦ (T2-25) × C2 ≦ 300, and even more preferably satisfy the relationship 100 ≦ (T2-25) × C2 ≦ 200.

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

[0050] The linear expansion coefficient of the second resin base material is, for example, 2.0×10 -5 / ℃~7.0×10 -5 / °C, preferably 2.0 x 10 -5 / ℃~6.0×10 -5 / °C, more preferably 2.0 × 10 -5 / ℃~5.0×10-5 / ° C. The second resin substrate having a linear expansion coefficient within the above range exhibits good uniformity in elongation during curved surface processing, and therefore the effects of the present invention can be suitably obtained.

[0051] Examples of the thermoplastic resin contained in the second resin substrate include the same resins as the thermoplastic resin that can be contained in the first resin substrate.

[0052] The thickness of the second resin base material 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 (material, thickness, etc.) as the first electrode layer, or may have a different configuration.

[0054] B. Light control film manufacturing method According to one aspect of the present invention, there is provided a method for manufacturing a light control film having a three-dimensional curved surface. The method for manufacturing the light control film includes preparing a planar light control film (Step I) and processing the planar light control film into a three-dimensional curved shape while heating it (Step II). The method for manufacturing the light control film can suitably obtain a light control film having a three-dimensional curved surface as described in Section A.

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

[0056] The planar light-controlling film comprises, in this order, a first transparent conductive film, a light-controlling layer containing 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 arranged on the light-controlling layer side of the first resin substrate, and the second transparent conductive film comprises a second resin substrate and a second electrode layer arranged on the light-controlling layer side of the second resin substrate.

[0057] The first transparent conductive film, light control layer, and second transparent conductive film in the planar light control film can be described in the same manner as the first transparent conductive film, light control layer, and second transparent conductive film in the light control film having a three-dimensional curved surface portion described in Section A. However, strictly speaking, because 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 control film can be equal to or greater than the thickness of the corresponding component in the three-dimensional curved surface portion in the light control film described in Section A. Furthermore, the thickness of each component in the planar light control film can be uniform throughout the plane. The ratio of the minimum to maximum in-plane thickness of each component in the planar light control film (minimum value / maximum value × 100) can be, for example, 99% to 100%.

[0058] When the light management film is a PDLC film or a PNLC film, these light management films can be obtained by fabrication methods known to those skilled in the art.

[0059] For example, a PDLC film can be obtained by a manufacturing method including: preparing a first transparent conductive film, a second transparent conductive film, and a coating liquid containing a polymer matrix-forming resin, a liquid crystal component, and a dispersion medium; applying the coating liquid to the electrode layer surface of one transparent conductive film 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 liquid is preferably an emulsion coating liquid in which liquid crystal particles containing the liquid crystal component are dispersed in a dispersion medium. The dispersion medium is preferably water or a mixture of water and a water-miscible organic solvent.

[0060] For example, a PDLC film can be obtained by a production method including: preparing a first transparent conductive film, a second transparent conductive film, and a coating liquid containing a curable resin for forming a polymer matrix, a liquid crystal component, and a polymerization initiator; applying the coating liquid 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, resulting in phase separation between the polymer matrix and the liquid crystal component to obtain a PDLC layer. Alternatively, the coating liquid may be filled between the first transparent conductive film and the second transparent conductive film, which are laminated via a spacer, followed by phase separation by polymerization.

[0061] B-2. Process II In step II, the planar light control film is processed into a three-dimensional curved shape while being heated. Step II may include, for example, applying the heated planar light control film to a curved mold to plastically deform it.

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

[0063] In FIG. 3A, the light control film 100 is placed on a sample stage 270 provided between the upper chamber 210 and the lower chamber 220. The upper chamber 210 accommodates a heating plate 230 that can be raised and lowered, and a convex mold 240 that is placed 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 accommodates 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 that corresponds to the convex curved surface of the convex mold 240. Openings are provided in the sample stage 270 at locations that correspond to the convex mold 240 and the concave mold 250 in a plan view.

[0064] Next, as shown in FIG. 3B, the heating plate 230 and the convex mold 240 are lowered to contact the light control film 100. When they come into contact with the light control film 100, the heating plate 230 and the convex mold 240 are heated to a predetermined temperature. The light control film 100 is heated by contact with the heated heating plate 230 and the convex mold 240, making it easier for its shape to be deformed. At this time, the pressure inside the upper chamber 210 may be reduced, for example, in a vacuum state. The pressure inside the lower chamber 220 may be atmospheric pressure or pressurized.

[0065] The heating temperature T3 of the heating plate 230 and the convex mold 240 (and consequently the heating temperature of the light control film 100) can be set to any appropriate temperature. For example, when the above (T1-25)×C1 and (T2-25)×C2 exceed 300, the heating temperature T3 can be set so 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. Furthermore, for example, when the above (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 higher than T1 and T2 by more than 25°C, for example, 30°C to 70°C or 40°C to 70°C. A resin substrate with a low Tg and a small linear expansion coefficient (e.g., a Tg of 90°C or less and a linear expansion coefficient of 3×10 -5 / °C or less) to a temperature sufficiently higher than Tg, the elongation and uniformity of the elongation during curved processing can be improved. In one embodiment, the heating temperature of the light control film 100 is, for example, 100°C to 150°C, and preferably 105°C to 145°C.

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

[0067] If necessary, a portion of the light control film 100 may be sandwiched between the convex curved surface of the convex mold 240 and the concave curved surface of the concave mold 250, and then in this state, the upper chamber 210 may be pressurized and the lower chamber 220 may be reduced in pressure. By pressing under pressure, the light control film 100 can be further pressed into the concave curved surface of the concave mold 250 (compressed air molding).

[0068] Thereafter, the interiors of upper chamber 210 and lower chamber 220 are returned to atmospheric pressure, heating of heating plate 230 and convex mold 240 is stopped, and they are raised and separated from light control film 100 (FIG. 3D).

[0069] In this manner, a light control film having a three-dimensional curved surface portion can be obtained. If necessary, unnecessary portions may be cut off from the light control film after the curved surface processing.

[0070] The elongation of the light control film due to 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 refers to the maximum value of the ratio of the length La between any two points on the periphery of the three-dimensional curved surface portion formed by curved surface processing to the length Lb between the corresponding two points on the light control film before curved surface processing (elongation (%) = (La - Lb) / Lb × 100). [Example]

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

[0072] [Example 1] (Transparent conductive film) PET film as a resin substrate (Tg: 85°C, linear expansion coefficient: 2.2 × 10 -5 An ITO layer (thickness: 30 nm) was formed by sputtering on one surface of the substrate (temperature: 100°C / °F). This resulted in a transparent conductive film having a 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 liquid crystal, birefringence Δn = 0.252 (ne = 1.766, no = 1.514), viscosity = 75 mPa s), 40.0 parts of purified water, and 1.2 parts of dispersant (Dai-ichi Kogyo Seiyaku Co., Ltd., "Noigen ET159") were mixed and coarsely dispersed by stirring at 100 rpm for 10 minutes in a homogenizer. The coarse dispersion was passed through a separation membrane with a uniform particle size distribution (SPG Techno Corporation, "SPG Pumping Connector", pore size 10 μm) at room temperature from the outside to the inside of the membrane at a flow rate of 80 mL / min / cm. 2 This procedure 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 liquid 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, product name "NeoRez R967", refractive index 1.49, average polymer particle size: 80 nm, solid 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]=propylidinetrimethyl), and 22.0 parts of pure water.

[0074] (PDLC layer) The emulsion coating liquid 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, and then 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 the PDLC layer using a laminator at a lamination pressure of 0.4 MPa / m, with the second electrode layer facing the PDLC layer. In this manner, a planar PDLC film having a structure 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 located between the upper and lower chambers. The upper chamber contained a heating plate that could be raised and lowered, and a convex mold located in the recess in the center of the heating plate. The lower chamber contained a concave mold and a support stand that supported the concave mold. The upper surface of the concave mold was circular with a diameter (φ) of 48.3 mm in plan view, and was a concave curved surface with a radius of curvature of 99.8 mm. The lower surface of the convex mold was a convex curved surface that corresponded to the concave curved surface of the concave mold. Openings were provided in the sample stage in the portions corresponding to the convex mold and the concave mold. (2) The heating plate and the convex mold were heated to 145°C. (3) The heated heating plate and the convex mold were lowered to contact the upper side of the PDLC film. (4) By creating a vacuum in the upper chamber, the PDLC film was strongly adsorbed onto the heating plate, and the film temperature was raised to 145°C. (5) The convex mold was further lowered to press the PDLC film against the concave surface of the concave mold. (6) By creating a vacuum in the lower chamber, the PDLC film was made to conform more closely to the concave surface of the concave mold. (7) Compressed air was introduced into the upper chamber to apply pressure, thereby carrying out further pressure forming. (8) The heating plate and the convex mold were returned to room temperature, and the pressure in the upper and lower chambers was returned to atmospheric pressure, and the PDLC film was removed.

[0077] In this way, a PDLC film was obtained that 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. The elongation of the PDLC film due to the curved surface processing (specifically, the elongation of the part corresponding to the diameter of the circle in plan view) was 1%.

[0078] [Example 2] The resin substrate was a polymethyl methacrylate (PMMA) film (Tg: 120°C, linear expansion coefficient: 6.5 × 10 -5A PDLC film having a three-dimensional curved surface portion with a circular diameter (φ) of 48.3 mm in plan view and a curvature radius of 99.8 mm was obtained in the same manner as in Example 1, except that a temperature of 1000 K / °C was used and the PDLC film was heated to 115°C during the curved surface processing.

[0079] [Comparative Example 1] The resin substrate was a polycarbonate (PC) film (Tg: 150°C, linear expansion coefficient: 6.9 × 10 -5 A PDLC film having a three-dimensional curved surface portion with a circular diameter (φ) of 48.3 mm in plan view and a curvature radius of 99.8 mm was obtained in the same manner as in Example 1, except that a temperature of 1000 K / °C was used and the PDLC film was heated to 115°C during the curved surface processing.

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

[0081] Comparative Example 3 Curved surface processing was performed in the same manner as in Example 1, except that the PDLC film was heated to 80°C during curved surface processing. However, fractures occurred in the resin substrate and the transparent conductive film, and therefore a PDLC film with a three-dimensional curved surface could not be obtained.

[0082] The appearance of the three-dimensional curved surface of the PDLC films having the three-dimensional curved surface obtained in the examples and comparative examples was visually observed. Furthermore, the three-dimensional curved surface was cut along the thickness direction and microscopically observed (at 200x magnification) to check for the presence or absence of cracks. The observation results are shown in Table 1 together with the thicknesses of the transparent conductive films. In the table, each thickness of 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 light control film according to the embodiment of the present invention is suitable for use in various devices having curved surfaces. [Explanation of symbols]

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

Claims

1. A light-control film including, in this order, a first transparent conductive film, a light-control layer including 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 first resin substrate on the side of the light-controlling layer, the second transparent conductive film includes a second resin substrate and a second electrode layer disposed on the second resin substrate on the side of the light-controlling layer, a ratio of the average thickness at the geometric center of the three-dimensional curved surface portion of each of the first transparent conductive film and the second transparent conductive film to the average thickness at the edge of the three-dimensional curved surface portion is 97% or more; Light-controlling film.

2. The light control film according to claim 1, wherein the three-dimensional curved surface portion has a radius of curvature of 60 mm to 320 mm.

3. The glass transition temperature and linear expansion coefficient of the first resin substrate are T1°C and C1×10, respectively. －５ / °C, T1 and C1 satisfy the relationship (T1-25) x C1 ≦ 650, The glass transition temperature and linear expansion coefficient of the second resin substrate are T2 ° C and C2 × 10, respectively. －５ / ° C., T2 and C2 satisfy the relationship (T2-25) × C2 ≦ 650.

4. The light control film according to claim 1 , wherein the first resin substrate and the second resin substrate each have a glass transition temperature of 130° C. or lower.

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

6. The light control film according to claim 1, wherein the thickness of the first resin substrate and the second resin substrate is 20 μm to 200 μm.

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

8. Providing a planar light management film; and The planar light control film is processed into a three-dimensional curved shape while being heated, The planar light control film includes, in this order, a first transparent conductive film, a light control layer including 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 first resin substrate on the side of the light-controlling layer, the second transparent conductive film includes a second resin substrate and a second electrode layer disposed on the second resin substrate on the side of the light-controlling layer, The glass transition temperature and linear expansion coefficient of the first resin substrate are T1°C and C1×10, respectively. －５ / °C, T1 and C1 satisfy the relationship (T1-25) x C1 ≦ 650, The glass transition temperature and linear expansion coefficient of the second resin substrate are T2 ° C and C2 × 10, respectively. －５ / °C, T2 and C2 satisfy the relationship (T2-25) x C2 ≦ 650.

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

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

11. The T1 and the C1 satisfy the relationship (T1-25) x C1 ≦ 300, T2 and C2 satisfy the relationship (T2-25) x C2≦300, The heating temperature of the light-control film is higher than T1 by more than 25°C, The manufacturing method according to claim 8, wherein the heating temperature of the light control film is more than 25°C higher than T2.

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

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