Light control sheet

Abstract

To provide a light control sheet that enables enhancement of peel strength between an alignment layer and a light control layer.SOLUTION: A light control sheet includes: a first transparent electrode layer 11; a second transparent electrode layer 12; a light control layer 13 positioned between the first transparent electrode layer 11 and the second transparent electrode layer 12, the light control layer 13 including a transparent polymer layer containing voids and a liquid crystal composition positioned in the voids; a first alignment layer 14 positioned between the first transparent electrode layer 11 and the light control layer 13; and a second alignment layer 15 positioned between the second transparent electrode layer 12 and the light control layer 13, the light control sheet being configured for increasing the haze value of the light control sheet by application of the voltage between the first transparent electrode layer 11 and the second transparent electrode layer 12, at least one of the first alignment layer 14 and the second alignment layer 15 including inorganic fine particles, and the average particle diameter D of the inorganic fine particles and the thickness H of the alignment layer satisfying H / D≤2.4 in the one alignment layer including the inorganic fine particles of the first alignment layer 14 and the second alignment layer 15.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a light-control sheet. [Background technology]

[0002] The reverse-type light-control sheet comprises a light-control layer, a first alignment layer, and a second alignment layer. The light-control layer comprises a transparent polymer layer defining a large number of voids, and a liquid crystal composition located within the voids and containing a liquid crystal compound with negative dielectric anisotropy. The first alignment layer and the second alignment layer are vertical alignment films. The first alignment layer and the second alignment layer sandwich the light-control layer in the thickness direction of the light-control layer and are in contact with the light-control layer.

[0003] The reverse-type light-controlling sheet further includes a first transparent electrode layer and a second transparent electrode layer. The first transparent electrode layer and the second transparent electrode layer sandwich a first alignment layer and a second alignment layer in the thickness direction. The reverse-type light-controlling sheet has a low haze value when no voltage is applied between the first transparent electrode layer and the second transparent electrode layer, and has a high haze value when a voltage is applied between the first transparent electrode layer and the second transparent electrode layer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-150731 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in a reverse-type light-controlling sheet, it is required to increase the peel strength between the light-controlling layer and each alignment layer. [Means for solving the problem]

[0006] A light-controlling sheet that solves the above-mentioned problems includes a first transparent electrode layer, a second transparent electrode layer, a light-controlling layer located between the first transparent electrode layer and the second transparent electrode layer, the light-controlling layer including a transparent polymer layer containing voids and a liquid crystal composition located in the voids, a first alignment layer located between the first transparent electrode layer and the light-controlling layer, and a second alignment layer located between the second transparent electrode layer and the light-controlling layer, and is configured to increase the haze value of the light-controlling sheet by applying a voltage between the first transparent electrode layer and the second transparent electrode layer. At least one of the first alignment layer and the second alignment layer contains inorganic fine particles. In the alignment layer containing the inorganic fine particles, of the first alignment layer and the second alignment layer, the average particle diameter D of the inorganic fine particles and the thickness H of the alignment layer satisfy the following: H / D≦2.4

[0007] In the above light-controlling sheet, the thickness H divided by the average particle diameter D is 2.4 or less, so that the alignment layer has unevenness at the interface between the alignment layer and the light-controlling layer compared to when the alignment layer does not contain inorganic fine particles, thereby improving the adhesion between the alignment layer and the light-controlling layer, and as a result, the peel strength between the alignment layer and the light-controlling layer can be increased.

[0008] In the above light-controlling sheet, when the weight of the alignment layer is 100% by weight, the alignment layer may contain 0.5% by weight or more of the inorganic microparticles, and the average particle diameter D and the thickness H may satisfy the following. H / D≦2.0

[0009] According to the above-mentioned light-controlling sheet, the value obtained by dividing the thickness H by the average particle diameter D is 2.0 or less, and the content of inorganic microparticles in the alignment layer is 0.5% by weight or more, thereby more reliably increasing the peel strength between the alignment layer and the light-controlling layer.

[0010] In the light controlling sheet, the average particle diameter D and the thickness H may satisfy the following. H / D≦1.67

[0011] According to the above-mentioned light-adjusting sheet, the value obtained by dividing the thickness H by the average particle diameter D is 1.67 or less, so that a steep decrease in peel strength is suppressed within the range set by the value obtained by dividing the thickness H by the average particle diameter D.

[0012] In the above light-controlling sheet, when the weight of the alignment layer is 100% by weight, the alignment layer may contain 4% by weight or less of the inorganic fine particles, and the average particle diameter D and the thickness H may satisfy the following. H / D≧0.38

[0013] In the light-controlling sheet, the content of inorganic fine particles is 4% by weight or less, and the value obtained by dividing the thickness H by the average particle diameter D is 0.38 or more. This prevents the number of irregularities in the alignment layer at the boundary between the alignment layer and the light-controlling layer from becoming excessive, and prevents each irregularity from becoming excessively large, thereby preventing the haze value of the light-controlling sheet from increasing when no voltage is applied between the transparent electrode layers.

[0014] In the light controlling sheet, the average particle diameter D may be 10 nm or more and 100 nm or less.

[0015] According to the light-controlling sheet, the average particle diameter D is 10 nm or more, which makes it possible to more reliably increase the peel strength between the alignment layer and the light-controlling layer. The average particle diameter D is 100 nm or less, which suppresses scattering by the inorganic fine particles, thereby preventing an increase in the haze value of the light-controlling sheet when no voltage is applied between the transparent electrode layers.

[0016] In the light controlling sheet, the inorganic fine particles may be made of silicon dioxide. According to the light controlling sheet, the inorganic fine particles can be dispersed in an organic solvent, and a difference in refractive index is unlikely to occur between the inorganic fine particles and the base material of the alignment layer. [Effects of the Invention]

[0017] According to the light-controlling sheet of the present disclosure, it is possible to increase the peel strength between the alignment layer and the light-controlling layer. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view showing the structure of a light-controlling sheet provided in a light-controlling device together with a driving unit. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a light-controlling layer provided in the light-controlling sheet. [Figure 3] FIG. 3 is an enlarged cross-sectional view showing a schematic structure of a light-controlling layer provided in the light-controlling sheet. [Figure 4] FIG. 4 is a table showing the blending ratios of the fine particles used in the coating liquid for the alignment layer used in the examples and comparative examples. [Figure 5] FIG. 5 is a table showing the evaluation results of the examples and comparative examples. [Figure 6] FIG. 6 is a graph showing the relationship between the value obtained by dividing the thickness H by the average particle diameter D and the peel strength. [Figure 7] FIG. 7 is a graph showing the relationship between the value obtained by dividing the thickness H by the average particle diameter D and the haze value. [Figure 8] FIG. 8 is a graph showing the relationship between the content of fine particles and the peel strength. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the light controlling sheet will be described with reference to FIGS. [Light control device] The light control device 1 will be described with reference to FIG.

[0020] As shown in FIG. 1, the light control device 1 includes a light control sheet 2 and a drive unit 3. The light control device 1 may be used as a partition device that divides a space. The light control sheet 2 itself may be a partition member that divides a space, or a light control adhesive body in which the light control sheet 2 is mounted on a transparent member may be a partition member that divides a space. The partition member may be window glass or a partition. The window glass may be mounted on a moving body such as a vehicle or an airplane, or may be installed in a building such as an office building or a public facility. The partition may be placed in the interior of a vehicle or in an indoor space.

[0021] The light control device 1 may be used as a screen for displaying an image. The light control sheet 2 itself may be the screen, or a light control adhesive body in which the light control sheet 2 is mounted on a transparent member may be the screen. The screen may be a front screen that uses reflected light for the image, or a rear screen that uses transmitted light for the image.

[0022] The light-controlling adhesive may have one light-controlling sheet 2 mounted on one transparent member, or may have multiple light-controlling sheets 2 mounted on one transparent member. The light-controlling adhesive may have the light-controlling sheet 2 sandwiched between two transparent substrates. The light-controlling sheet 2 is flexible. The light-controlling adhesive may or may not be flexible. The light-controlling adhesive may have a flat shape or a curved shape.

[0023] The driving type of the light controlling sheet 2 is a reverse type. The driving unit 3 supplies a voltage signal to the reverse type light controlling sheet 2. The reverse type light controlling sheet 2 changes from transparent to opaque in response to the input of a voltage signal. The reverse type light controlling sheet 2 remains opaque while the voltage signal is input. The reverse type light controlling sheet 2 returns from opaque to transparent in response to the cessation of the supply of the voltage signal.

[0024] The light controlling sheet 2 achieves its opacity by scattering transmitted light through the light controlling sheet 2. An opaque light controlling sheet 2 has a lower parallel light transmittance than a transparent light controlling sheet 2. An opaque light controlling sheet 2 has a higher haze value than a transparent light controlling sheet 2. The color of the opaque light controlling sheet 2 may be either achromatic or chromatic. The color of the transparent light controlling sheet 2 may be either achromatic or chromatic.

[0025] [Light-adjusting sheet] The light-controlling sheet 2 includes a first transparent electrode layer 11, a second transparent electrode layer 12, a light-controlling layer 13, a first alignment layer 14, and a second alignment layer 15. The light-controlling sheet 2 further includes a first transparent substrate 16 and a second transparent substrate 17. The light-controlling layer 13 is located between the first transparent electrode layer 11 and the second transparent electrode layer 12. The first alignment layer 14 is located between the first transparent electrode layer 11 and the light-controlling layer 13. The second alignment layer 15 is located between the second transparent electrode layer 12 and the light-controlling layer 13.

[0026] The light-controlling layer 13 is located between a first alignment layer 14 and a second alignment layer 15. A first surface 13S1 of the light-controlling layer 13 is in contact with the first alignment layer 14. A second surface 13S2 of the light-controlling layer 13 is in contact with the second alignment layer 15. The first alignment layer 14 is in contact with the light-controlling layer 13 and the first transparent electrode layer 11. The second alignment layer 15 is in contact with the light-controlling layer 13 and the second transparent electrode layer 12.

[0027] The first transparent electrode layer 11 is located between the first alignment layer 14 and the first transparent substrate 16, and is in contact with the first alignment layer 14 and the first transparent substrate 16. The second transparent electrode layer 12 is located between the second alignment layer 15 and the second transparent substrate 17, and is in contact with the second alignment layer 15 and the second transparent substrate 17.

[0028] The first transparent electrode layer 11 includes a first connection terminal 11A. The first transparent electrode layer 11 is connected to the driving unit 3 through the first connection terminal 11A and a first wiring 4A. The second transparent electrode layer 12 includes a second connection terminal 12A. The second transparent electrode layer 12 is connected to the driving unit 3 through the second connection terminal 12A and a second wiring 4B.

[0029] The first transparent electrode layer 11 and the second transparent electrode layer 12 are each colorless and transparent or colored and transparent. The materials constituting the first transparent electrode layer 11 and the second transparent electrode layer 12 are each a conductive inorganic oxide, a metal, or a conductive organic polymer compound. The conductive inorganic oxide may be, for example, any one selected from the group consisting of indium tin oxide, fluorine-doped tin oxide, tin oxide, and zinc oxide. The metal may be, for example, gold or silver nanowires. The conductive organic polymer compound may be, for example, any one selected from the group consisting of carbon nanotubes and poly(3,4-ethylenedioxythiophene). The thickness of the first transparent electrode layer 11 and the second transparent electrode layer 12 may each be, for example, 5 nm or more and 200 nm or less.

[0030] The first transparent substrate 16 and the second transparent substrate 17 are each colorless and transparent or colored and transparent. The materials constituting the first transparent substrate 16 and the second transparent substrate 17 are each an organic polymer compound or an inorganic polymer compound. The organic polymer compound may be, for example, any one selected from the group consisting of polyester, polyacrylate, polycarbonate, and polyolefin. The inorganic polymer compound may be, for example, any one selected from the group consisting of silicon oxide, silicon oxynitride, and silicon nitride. The thickness of the first transparent substrate 16 and the second transparent substrate 17 is, for example, 20 μm or more and 400 μm or less.

[0031] The driver 3 is connected separately to the first transparent electrode layer 11 and the second transparent electrode layer 12. The driver 3 applies a voltage between the first transparent electrode layer 11 and the second transparent electrode layer 12 by supplying a voltage signal. The driver 3 stops applying a voltage between the first transparent electrode layer 11 and the second transparent electrode layer 12 by stopping the supply of the voltage signal. Supplying and stopping the supply of the voltage signal changes the orientation of the liquid crystal compound LCM (see Figure 3). The driver 3 reversibly switches the light controlling sheet 2 from transparent to opaque by changing the orientation of the liquid crystal compound LCM. Because the driving type of the light controlling sheet 2 is reverse type, the light controlling sheet 2 is configured to increase the haze value of the light controlling sheet 2 by applying a voltage between the first transparent electrode layer 11 and the second transparent electrode layer 12.

[0032] When the driving unit 3 stops supplying a voltage signal, the alignment state of the liquid crystal compound LCM follows the alignment restriction force of the first alignment layer 14 and the second alignment layer 15. The alignment of the liquid crystal compound LCM according to the alignment restriction force allows visible light to pass through the light control layer 13. This makes the light control sheet 2 transparent. When the driving unit 3 is supplying a voltage signal, the liquid crystal compound LCM is subjected to the action force of an electric field that resists the alignment restriction force. The alignment of the liquid crystal compound LCM according to the action force of the electric field causes the light control layer 13 to scatter visible light. This makes the light control sheet 2 opaque.

[0033] The light-controlling sheet 2 may include another functional layer between the first transparent electrode layer 11 and the first transparent substrate 16. The light-controlling sheet 2 may include another functional layer between the second transparent electrode layer 12 and the second transparent substrate 17. The other functional layer may be a gas barrier layer that prevents oxygen and moisture from passing through toward the light-controlling layer 13, or an ultraviolet barrier layer that prevents ultraviolet light of a specific wavelength from passing through toward the light-controlling layer 13. The other functional layer may be a hard coat layer that mechanically protects the light-controlling sheet 2, or an adhesive layer that improves adhesion between layers in the light-controlling sheet 2.

[0034] The structure of the light controlling layer 13 included in the light controlling sheet 2 will be further described with reference to FIGS. 2, at least one of the first alignment layer 14 and the second alignment layer 15 contains inorganic fine particles. In this embodiment, both the first alignment layer 14 and the second alignment layer 15 contain inorganic fine particles. The first alignment layer 14 contains a large number of first fine particles 14P. The second alignment layer 15 contains a large number of second fine particles 15P.

[0035] In the light controlling sheet 2 of the present disclosure, of the first alignment layer 14 and the second alignment layer 15, the alignment layer containing inorganic fine particles satisfies the following condition 1.

[0036] (Condition 1) The average particle diameter D of the inorganic fine particles and the thickness H of the alignment layer satisfy the following. H / D≦2.4

[0037] According to the light-controlling sheet 2 of the present disclosure, by satisfying condition 1, the alignment layers 14, 15 have unevenness at the interface between the alignment layers 14, 15 and the light-controlling layer 13, compared to when the alignment layers 14, 15 do not contain inorganic fine particles, thereby improving the adhesion between the alignment layers 14, 15 and the light-controlling layer 13. As a result, the peel strength between the alignment layers 14, 15 and the light-controlling layer 13 can be increased. Note that when the value obtained by dividing the thickness H by the average particle diameter D exceeds 2.4, the alignment layers 14, 15 are unlikely to have unevenness at the interface between the alignment layers 14, 15 and the light-controlling layer 13, and as a result, it is difficult to increase the peel strength.

[0038] The first alignment layer 14 has a surface 14S in contact with the photochromic layer 13. The second alignment layer 15 has a surface 15S in contact with the photochromic layer 13. The surface 14S of the first alignment layer 14 has irregularities such that the portions of the first alignment layer 14 where the first fine particles 14P are located are convex toward the second alignment layer 15. The surface 15S of the second alignment layer 15 has irregularities such that the portions of the second alignment layer 15 where the second fine particles 15P are located are convex toward the first alignment layer 14. This allows the surfaces 14S and 15S of the alignment layers 14 and 15 to have an anchor effect on the photochromic layer 13, thereby increasing the peel strength between the alignment layers 14 and 15 and the photochromic layer 13.

[0039] The thickness H of each alignment layer 14, 15 is the average thickness of the alignment layer 14, 15 containing the fine particles 14P, 15P. When calculating the average thickness of each alignment layer 14, 15, the thickness of the alignment layer 14, 15 is measured at any 10 points within any 100 mm square area of ​​the alignment layer 14, 15. Next, the average thickness is calculated by dividing the sum of the measurements at each point by the number of measurements.

[0040] The method for measuring the average particle diameter D of the particles 14P, 15P may be selected according to the material of the particles 14P, 15P. For example, if the material of the particles 14P, 15P is silicon dioxide (SiO2) or indium tin oxide (ITO), the BET method may be used. Alternatively, if the material of the particles 14P, 15P is zirconium oxide (ZrO2), the DLS method may be used.

[0041] The thickness H of the first alignment layer 14 may be the same as or different from the thickness H of the second alignment layer 15. The average particle diameter D of the first fine particles 14P may be the same as or different from the average particle diameter D of the second fine particles 15P. In either case, as long as each alignment layer 14, 15 satisfies condition 1, it is possible to obtain an anchor effect by the surfaces 14S, 15S of the alignment layers 14, 15.

[0042] Each of the alignment layers 14, 15 has unevenness due to the organic polymer compound that is the base material of each of the alignment layers 14, 15 conforming to the surfaces of the fine particles 14P, 15P. If the average particle diameter D of the fine particles 14P, 15P is too large compared to the thickness H of the alignment layer 14, 15, the base material tends to have a flat shape without conforming to the surfaces of the fine particles 14P, 15P.

[0043] Each of the alignment layers 14 and 15 may satisfy at least one of the following conditions 2 to 6. That is, each of the alignment layers 14 and 15 may satisfy only one of the conditions 2 to 6, or any two or more of them.

[0044] (Condition 2) When the weight of the alignment layers 14, 15 is taken as 100% by weight, the alignment layers 14, 15 contain 0.5% by weight or more of the fine particles 14P, 15P, and the average particle diameter D and thickness H satisfy the following. H / D≦2.0

[0045] (Condition 3) The average particle diameter D and thickness H satisfy the following: H / D≦1.67

[0046] (Condition 4) When the weight of the alignment layers 14, 15 is taken as 100% by weight, the alignment layers 14, 15 contain 4% by weight or less of the fine particles 14P, 15P, and the average particle diameter D and thickness H satisfy the following.

[0047] H / D≧0.38

[0048] (Condition 5) The average particle diameter D is 10 nm or more and 100 nm or less. (Condition 6) The fine particles 14P and 15P are made of silicon dioxide.

[0049] When the light-controlling sheet 2 satisfies condition 2, the peel strength between the alignment layers 14, 15 and the light-controlling layer 13 is more reliably increased. That is, high peel strength can be obtained over the entire range of the compounding ratio of the fine particles 14P, 15P and over the entire range of the value obtained by dividing the thickness H by the average particle diameter D.

[0050] When the light-controlling sheet 2 satisfies condition 3, a steep decrease in peel strength is suppressed within the range set by the value obtained by dividing the thickness H by the average particle diameter D, i.e., within the range of condition 1.

[0051] When the light-controlling sheet 2 satisfies condition 4, the number of irregularities in the alignment layers 14, 15 at the boundary between the alignment layers 14, 15 and the light-controlling layer 13 and the size of each irregularity are prevented from becoming excessive. As a result, the haze value of the light-controlling sheet 2 is prevented from increasing when no voltage is applied between the transparent electrode layers 11, 12.

[0052] When the light-controlling sheet 2 satisfies condition 5, an average particle diameter D of 10 nm or more can more reliably increase the peel strength between the alignment layers 14, 15 and the light-controlling layer 13. An average particle diameter D of 100 nm or less can suppress scattering by the fine particles 14P, 15P, thereby preventing the haze value of the light-controlling sheet 2 from increasing when no voltage is applied between the transparent electrode layers 11, 12.

[0053] When the light controlling sheet 2 satisfies the condition 6, the particles 14P, 15P can be dispersed in an organic solvent, and a difference in refractive index between the particles 14P, 15P and the base material of the alignment layers 14, 15 is unlikely to occur.

[0054] The light control layer 13 and the alignment layers 14 and 15 included in the light control sheet 2 will be described in more detail below with reference to FIG. As shown in FIG. 3, the light-modulating layer 13 includes a transparent polymer layer 13P, a liquid crystal composition 13L, and spacers SP.

[0055] The liquid crystal composition 13L includes a liquid crystal compound LCM. The liquid crystal composition 13L may include additives such as a dichroic dye, an antifoaming agent, an antioxidant, a weatherproofing agent, a solvent, and a viscosity reducing agent. The weatherproofing agent may be, for example, an ultraviolet absorber or a light stabilizer. The liquid crystal compound LCM has a negative dielectric anisotropy in the long axis direction. The dielectric constant of the liquid crystal compound LCM in the long axis direction is lower than the dielectric constant of the liquid crystal compound LCM in the short axis direction.

[0056] The liquid crystal compound LCM may be at least one selected from the group consisting of Schiff base-based, azo-based, azoxy-based, biphenyl-based, terphenyl-based, benzoate ester-based, tolan-based, pyrimidine-based, pyridazine-based, cyclohexanecarboxylic acid ester-based, phenylcyclohexane-based, biphenylcyclohexane-based, dicyanobenzene-based, naphthalene-based, and dioxane-based liquid crystal compounds. The liquid crystal compound LCM is one type of liquid crystal compound LCM or a combination of two or more types of liquid crystal compounds LCM.

[0057] The spacers SP are dispersed throughout the transparent polymer layer 13P. The particle size of the spacers SP determines the thickness of the light-controlling layer 13. The thickness of the light-controlling layer 13 may be, for example, 5 μm or more and 100 μm or less. The spacers SP improve the uniformity of the thickness of the light-controlling layer 13. The spacers SP may be bead spacers or photospacers. The photospacers are formed by exposing and developing a photoresist. The spacers SP may be colorless and transparent, or colored and transparent. When the liquid crystal composition 13L contains a dichroic dye, the color of the spacers SP is preferably the same color as the color exhibited by the dichroic dye.

[0058] The transparent polymer layer 13P is a cured product of an ionizing radiation-curable composition. The ionizing radiation may be ultraviolet light or an electron beam. The ionizing radiation-curable composition may be an ultraviolet-curable composition or an electron beam-curable composition. The lower limit of the content of the transparent polymer layer 13P relative to the total amount of the transparent polymer layer 13P and the liquid crystal composition 13L is 20% by mass, and more preferably 30% by mass. If the content of the transparent polymer layer 13P is 20% by mass or more, high transmittance is likely to be obtained when transparent. The upper limit of the content of the transparent polymer layer 13P relative to the total amount of the transparent polymer layer 13P and the liquid crystal composition 13L is 70% by mass, and more preferably 60% by mass. If the content of the transparent polymer layer 13P is 70% by mass or less, a high haze value is likely to be obtained when opaque.

[0059] The lower and upper limits of the content of the transparent polymer layer 13P are within a range in which the liquid crystal particles composed of the liquid crystal composition 13L phase-separate from the polymer of the ionizing radiation-curable composition during the polymerization process of the ionizing radiation-curable composition. From the viewpoint of increasing the mechanical strength of the transparent polymer layer 13P, it is preferable that the lower limit of the content of the transparent polymer layer 13P is high. From the viewpoint of reducing the driving voltage of the liquid crystal compound LCM, it is preferable that the upper limit of the content of the transparent polymer layer 13P is low.

[0060] The transparent polymer layer 13P defines a void 13D in the light-controlling layer 13. The liquid crystal composition 13L is filled in the void 13D. The void 13D may be isolated from other voids 13D adjacent to it, or may be connected to other adjacent voids 13D. The voids 13D may have two or more sizes. The shape of the void 13D is spherical, ellipsoidal, or irregular. The diameter of the sphere circumscribing the void 13D is, for example, 1 μm or more and 10 μm or less. The diameter of the sphere circumscribing the void 13D is sufficiently larger than the irregularities in the alignment layers 14 and 15.

[0061] The voids 13D may be unevenly distributed in the transparent polymer layer 13P, or may be uniformly dispersed in the transparent polymer layer 13P. In the example shown in Fig. 3, the voids 13D are unevenly distributed in a range closer to the first alignment layer 14 than to the center in the thickness direction of the transparent polymer layer 13P, so that the voids 13D become more numerous in a region closer to the first alignment layer 14. The voids 13D are unevenly distributed in a range closer to the second alignment layer 15 than to the center in the thickness direction of the transparent polymer layer 13P, so that the voids 13D become more numerous in a region closer to the second alignment layer 15. This makes it easier for the alignment restricting force of the alignment layers 14 and 15 to act on the liquid crystal compound LCM in the voids 13D, making it easier to obtain high transmittance when transparent.

[0062] The type of retention of the liquid crystal composition 13L by the transparent polymer layer 13P is any one selected from the group consisting of a polymer dispersion type, a polymer network type, and an encapsulation type. The polymer dispersion type light control layer 13 has a transparent polymer layer 13P that defines a large number of isolated voids 13D, and retains the liquid crystal composition 13L in the voids 13D dispersed in the transparent polymer layer 13P. The polymer network type light control layer 13 has a three-dimensional network-like transparent polymer layer 13P that has voids 13D, and retains the liquid crystal composition 13L in the interconnected voids 13D. The encapsulation type light control layer 13 retains the liquid crystal composition 13L in capsule-like voids 13D dispersed in the transparent polymer layer 13P.

[0063] The transparent polymer layer 13P may be a cured product of a monofunctional ionizing radiation curable resin or a cured product of a polyfunctional ionizing radiation curable resin. The ionizing radiation curable resin may be at least one selected from the group consisting of a urethane acrylate compound, an alkyl acrylate compound, a glycol acrylate compound, a pentaerythritol compound, and a trimethylolpropane compound.

[0064] The transparent polymer layer 13P is formed by forming a coating film for a light-controlling layer from a coating liquid for a light-controlling layer containing an ionizing radiation-curable composition and a liquid crystal compound LCM, and then irradiating the coating film for a light-controlling layer with ionizing radiation. The coating liquid for a light-controlling layer contains a polymerization initiator for initiating polymerization of the ionizing radiation-curable composition. The transparent polymer layer 13P contains a polymerization initiator that initiates polymerization. The polymerization initiator is at least one selected from the group consisting of diketone compounds, acetophenone compounds, benzoin compounds, benzophenone compounds, and thioxanthone compounds.

[0065] The first alignment layer 14 and the second alignment layer 15 each regulate the alignment direction of the liquid crystal compound LCM. The first alignment layer 14 and the second alignment layer 15 each exhibit colorless transparency or colored transparency. The first alignment layer 14 and the second alignment layer 15 are vertical alignment films.

[0066] The material constituting the first alignment layer 14 and the second alignment layer 15 includes a base material and inorganic fine particles. The base material is an organic polymer compound. The organic polymer compound may be, for example, any one selected from the group consisting of polyimide, polyamide, and polyvinyl alcohol. The alignment layers 14 and 15 made of polyamide are formed using polyamic acid. In the alignment layers 14 and 15 made of polyamic acid, the pitch of the functional groups for aligning the liquid crystal compound LCM is significantly smaller than the average particle diameter D of the fine particles 14P and 15P.

[0067] The material constituting the inorganic fine particles may be, for example, any one selected from the group consisting of silicon oxide, zirconium oxide, and indium tin oxide. The silicon oxide may be, for example, silicon dioxide. The thickness of the first alignment layer 14 and the second alignment layer 15 may be, for example, 20 nm or more and 500 nm or less, respectively.

[0068] Since the first alignment layer 14 and the second alignment layer 15 are vertical alignment films, the first alignment layer 14 and the second alignment layer 15 each apply an alignment restriction force to the liquid crystal compound LCM so as to align the long axis direction of the liquid crystal compound LCM with the thickness direction of the light control layer 13. As a result, the first alignment layer 14 and the second alignment layer 15 allow visible light to pass through the light control layer 13 during a period when the supply of a voltage signal is stopped.

[0069] As described above, each alignment layer 14, 15 has unevenness at the boundary with the light-controlling layer 13. Therefore, compared to when the surfaces 14S, 15S of the alignment layers 14, 15 are flat, the direction in which the long axis direction of the liquid crystal compound LCM is aligned may be tilted relative to the thickness direction of the light-controlling layer 13 due to the unevenness. In this regard, when the light-controlling sheet 2 satisfies condition 4 or condition 5, even when the voids 13D are unevenly distributed near the first alignment layer 14 and the second alignment layer 15, it is possible to suppress the tilt of the long axis direction of the liquid crystal compound LCM relative to the thickness direction of the light-controlling layer 13 so as to maintain a low haze value when transparent.

[0070] [Light control sheet manufacturing method] The method for producing the light-controlling sheet 2 includes forming a first alignment layer 14 on the first transparent electrode layer 11 and forming a second alignment layer 15 on the second transparent electrode layer 12. The first alignment layer 14 is formed by forming an alignment layer coating film on the first transparent electrode layer 11 laminated on the first transparent substrate 16 using an alignment layer coating liquid, and then heating the alignment layer coating film. The second alignment layer 15 is formed by forming an alignment layer coating film on the second transparent electrode layer 12 laminated on the second transparent substrate 17 using an alignment layer coating liquid, and then heating the alignment layer coating film.

[0071] The coating film for the alignment layer contains an organic solvent. From the viewpoint of improving the dispersibility of the inorganic fine particles in the coating liquid for the alignment layer, it is preferable that the fine particles 14P, 15P are composed of silicon dioxide. This suppresses aggregation of the fine particles 14P, 15P in the coating liquid for alignment, thereby suppressing the local formation of unevenness on the surfaces 14S, 15S of the alignment layers 14, 15. As a result, the peel strength is likely to be increased over the entire surfaces 14S, 15S of the alignment layers 14, 15.

[0072] The method for producing the light-controlling sheet 2 includes forming a coating film for a light-controlling layer, which contains an ionizing radiation-curable composition and a liquid crystal compound LCM, between a first alignment layer 14 and a second alignment layer 15. The coating film for a light-controlling layer is formed by applying a coating liquid for a light-controlling layer to the first alignment layer 14 supported on a first transparent substrate 16. The coating film for a light-controlling layer is sandwiched between the first alignment layer 14 supported on the first transparent substrate 16 and the second alignment layer 15 supported on a second transparent substrate 17.

[0073] The method for producing the light-controlling sheet 2 includes irradiating the coating for the light-controlling layer with ionizing rays to form a light-controlling layer 13 having a transparent polymer layer 13P that defines voids 13D and a liquid crystal composition 13L that fills the voids 13D between a first alignment layer 14 and a second alignment layer 15. The coating for the light-controlling layer may be irradiated with ionizing rays from a first transparent substrate 16 toward the coating for the light-controlling layer, or from a second transparent substrate 17 toward the coating for the light-controlling layer, or a combination of these.

[0074] When irradiated with ionizing rays, the ionizing radiation-curable composition initiates polymerization and phase-separates the liquid crystal particles composed of liquid crystal composition 13L from the polymer. Phase separation of the liquid crystal particles composed of liquid crystal composition 13L proceeds through polymerization of the ionizing radiation-curable composition and diffusion of the liquid crystal composition 13L. The polymerization rate of the ionizing radiation-curable composition varies depending on the intensity of the ionizing radiation irradiated to the ionizing radiation-curable composition. The diffusion rate of the liquid crystal composition 13L varies depending on the processing temperature during polymerization of the ionizing radiation-curable composition. In phase separation of the liquid crystal composition 13L, the intensity of the ionizing radiation irradiated to the ionizing radiation-curable composition is set so that the liquid crystal particles have a desired size, i.e., so that the size of the voids 13D has a desired size. In addition, heating may be performed to promote diffusion of the liquid crystal composition 13L in phase separation of the liquid crystal composition 13L.

[0075] When it is desired to reduce the size of the voids 13D, it is preferable to increase the intensity of the ionizing radiation irradiated to the ionizing radiation-curable composition and to carry out the polymerization at a low temperature to suppress diffusion of the liquid crystal composition 13L. When it is desired to increase the size of the voids 13D, it is preferable to decrease the intensity of the ionizing radiation irradiated to the ionizing radiation-curable composition and to carry out the polymerization at a high temperature to promote diffusion of the liquid crystal composition 13L.

[0076] [Example] An example and a comparative example will be described with reference to FIGS. [Coating liquid for alignment layer] In the examples and comparative examples, the coating liquids described below were used as the coating liquids for the alignment layer.

[0077] [Coating Liquid A] When preparing coating solution A, the following materials were prepared. (Diamine compounds) B1: 4,4'-diaminodiphenylmethane (Tokyo Chemical Industry Co., Ltd.) B2: 3,5-diaminobenzoic acid (Tokyo Chemical Industry Co., Ltd.) (Tetracarboxylic acid component) C1: 1,2,3,4-cyclobutanetetracarboxylic dianhydride (Tokyo Chemical Industry Co., Ltd.) C2:3-(Carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride (Tokyo Chemical Industry Co., Ltd.) (solvent) NEP: N-ethyl-2-pyrrolidone Butyl cellosolve

[0078] First, polyamic acid was synthesized by mixing the above-mentioned materials in the following ratio and reacting them at 80°C for 5 hours.

[0079] B1: 10 parts by weight B2 :8 parts by weight C2 :4 parts by weight NEP: 75 parts by weight

[0080] Next, the following materials were further mixed with the reaction mixture, and the mixture was allowed to react at 40°C for 6 hours.

[0081] C1 :16 parts by weight NEP: 38 parts by weight

[0082] As a result, a polyamic acid solution with a solid content of 25% by weight was obtained. Next, the following materials were mixed into the polyamic acid solution, and then the mixture was stirred at 50° C. for 24 hours to obtain a coating liquid A.

[0083] Polyamic acid solution: 12 parts by weight NEP: 27 parts by weight Butyl cellosolve: 36 parts by weight

[0084] As shown in FIG. 4 and described below, Coating Liquids 1 to 12 were prepared using Coating Liquid A.

[0085] [Coating liquid 1] Coating liquid 1 was obtained by mixing 100 parts by weight of coating liquid A and 0.067 parts by weight of colloidal silica dispersion (IPA-ST-ZL, manufactured by Nissan Chemical Industries, Ltd., average particle diameter D 80 nm, solid content 30% by weight).

[0086] [Coating Liquid 2] Coating liquid 2 was obtained in the same manner as in Coating liquid 1, except that the blending ratio of the colloidal silica dispersion in Coating liquid 1 was changed to 0.267 parts by weight.

[0087] [Coating Liquid 3] Coating liquid 3 was obtained in the same manner as in Coating liquid 1, except that the blending ratio of the colloidal silica dispersion in Coating liquid 1 was changed to 0.533 parts by weight.

[0088] [Coating Liquid 4] Coating liquid 4 was obtained in the same manner as in Coating liquid 1, except that the blending ratio of the colloidal silica dispersion in Coating liquid 1 was changed to 0.667 parts by weight.

[0089] [Coating Liquid 5] Coating Liquid 5 was obtained in the same manner as Coating Liquid 2, except that the colloidal silica dispersion in Coating Liquid 2 was changed to a colloidal silica dispersion containing fine particles with an average particle diameter D of 12 nm (IPA-ST, manufactured by Nissan Chemical Industries, Ltd., average particle diameter D 12 nm, solid content concentration 30 wt%).

[0090] [Coating Liquid 6] Coating Liquid 6 was obtained in the same manner as Coating Liquid 2, except that the colloidal silica dispersion in Coating Liquid 2 was changed to a colloidal silica dispersion containing fine particles with an average particle diameter D of 45 nm (IPA-ST-L, manufactured by Nissan Chemical Industries, Ltd., average particle diameter D 45 nm, solid content concentration 30 wt %).

[0091] [Coating Liquid 7] Coating Liquid 7 was obtained in the same manner as in Coating Liquid 6, except that the blending ratio of the colloidal silica dispersion in Coating Liquid 6 was changed to 0.067 parts by weight.

[0092] [Coating Liquid 8] Coating liquid 8 was obtained in the same manner as in Coating liquid 6, except that the blending ratio of the colloidal silica dispersion in Coating liquid 6 was changed to 0.533 parts by weight.

[0093] [Coating Liquid 9] Coating Liquid 9 was obtained in the same manner as in Coating Liquid 6, except that the blending ratio of the colloidal silica dispersion in Coating Liquid 6 was changed to 0.667 parts by weight.

[0094] [Coating Liquid 10] Coating Liquid 10 was obtained in the same manner as Coating Liquid 2, except that the colloidal silica dispersion in Coating Liquid 2 was changed to a different colloidal silica dispersion (MEK-ST-ZL, manufactured by Nissan Chemical Industries, Ltd., average particle size D 80 nm, solid content concentration 30 wt %).

[0095] [Coating Liquid 11] Coating Liquid 11 was obtained in the same manner as Coating Liquid 2, except that the colloidal silica dispersion in Coating Liquid 2 was changed to an indium tin oxide (ITO) particle dispersion (DLIT-001, manufactured by Daiken Chemical Co., Ltd., average particle diameter 94 nm, solid content 30 wt%).

[0096] [Coating Liquid 12] Coating Liquid 12 was obtained in the same manner as Coating Liquid 2, except that the colloidal silica dispersion in Coating Liquid 2 was changed to a zirconia particle dispersion (OZ-S30P-AC, average particle diameter D 40 nm, solid content 30 wt %).

[0097] [Light Control Sheet 2] A coating liquid for forming the light-controlling layer 13 was prepared in the following blending ratio. Liquid crystal compound: MLC-6608, manufactured by Merck: 50 parts by weight ·Ionizing radiation curable composition: IBXA, manufactured by Osaka Organic Chemical Industry Co., Ltd.: 36 parts by weight ·Ionizing radiation curable composition: A-DPF, manufactured by Shin-Nakamura Kagaku Komyo Co., Ltd.: 10 parts by weight Ionizing radiation curable composition: Karenz MT NR-1, manufactured by Resonac Co., Ltd. : 2 parts by weight (Karens is a registered trademark) Initiator (1-hydroxycyclohexyl phenyl ketone, manufactured by IGM Resins BV) :1 part by weight Spacer: PMMA spherical particles, particle diameter 10 μm, manufactured by Sekisui Plastics Co., Ltd. :1 part by weight

[0098] In addition, the following materials were used to form the light controlling sheet 2. First transparent electrode layer 11: ITO, thickness 30 nm Second transparent electrode layer 12: ITO, thickness 30 nm First transparent substrate 16: PET film, thickness 125 μm Second transparent substrate 17: PET film, thickness 125 μm

[0099] An alignment layer coating film was formed by applying an alignment layer coating liquid onto each transparent electrode layer 11, 12 using a bar coater. The alignment layer coating film was then heated at 150°C for 4 minutes to obtain alignment layers 14, 15. Next, a light-control layer coating film was formed by applying a light-control layer coating liquid onto the first alignment layer 14, and then a second alignment layer 15 was placed on the light-control layer coating film. This sandwiched the light-control layer coating film between a pair of alignment films. Next, the light-control layer coating film was cured by irradiating it with ultraviolet light from the first transparent substrate 16 and the second transparent substrate 17. At this time, the intensity of the ultraviolet light on each transparent substrate 16, 17 was set to 7.2 mW / cm. 2 The temperature was set to 100°C, and the irradiation time of the ultraviolet light was set to 120 seconds. Thus, the light-control sheet 2 was obtained.

[0100] [Comparative Examples 1 to 4] In Comparative Examples 1 to 4, coating liquid A was used as the coating liquid for the alignment layer. The thickness H of the alignment layers 14 and 15 was set to 30 nm in Comparative Example 1, 75 nm in Comparative Example 2, 150 nm in Comparative Example 3, and 200 nm in Comparative Example 4.

[0101] [Examples 1 to 4 and Comparative Example 5] In Examples 1 to 4 and Comparative Example 5, coating liquid 1 was used as the coating liquid for the alignment layer. The thickness H of the alignment layers 14 and 15 was set to 20 nm in Example 1, 30 nm in Example 2, 75 nm in Example 3, 150 nm in Example 4, and 200 nm in Comparative Example 5.

[0102] [Examples 5 to 8 and Comparative Example 6] In Examples 5 to 8 and Comparative Example 6, coating liquid 2 was used as the coating film for the alignment layer. The thickness H of the alignment layers 14 and 15 was set to 20 nm in Example 5, 30 nm in Example 6, 75 nm in Example 7, 150 nm in Example 8, and 200 nm in Comparative Example 6.

[0103] [Examples 9 to 12 and Comparative Example 7] In Examples 9 to 12 and Comparative Example 7, coating liquid 3 was used as the coating liquid for the alignment layer. The thickness H of the alignment layers 14 and 15 was set to 20 nm in Example 9, 30 nm in Example 10, 75 nm in Example 11, 150 nm in Example 12, and 200 nm in Comparative Example 7.

[0104] [Examples 13 to 16] In Examples 13 to 16, coating liquid 4 was used as the coating liquid for the alignment layer. The thickness H of the alignment layers 14 and 15 was set to 20 nm in Example 13, 30 nm in Example 14, 75 nm in Example 15, and 150 nm in Example 16.

[0105] [Example 17 and Comparative Example 8] In Example 17 and Comparative Example 8, coating liquid 5 was used as the coating liquid for the alignment layer. The thickness H of the alignment layers 14 and 15 was set to 20 nm in Example 17, and to 36 nm in Comparative Example 8.

[0106] [Examples 18 to 21] In Examples 18 to 21, coating liquid 6 was used as the coating liquid for the alignment layer. The thickness H of the alignment layers 14 and 15 was set to 10 nm in Example 18, 20 nm in Example 19, 30 nm in Example 20, and 75 nm in Example 21.

[0107] [Example 22] In Example 22, the coating liquid for the alignment layer was the coating liquid 7. In Example 22, the thickness H of the alignment layers 14 and 15 was set to 75 nm.

[0108] [Example 23] In Example 23, the coating liquid for the alignment layer was the coating liquid 8. In Example 23, the thickness H of the alignment layers 14 and 15 was set to 75 nm.

[0109] [Example 24] In Example 24, the coating liquid for the alignment layer was the coating liquid 9. In Example 24, the thickness H of the alignment layers 14 and 15 was set to 75 nm.

[0110] [Example 25] In Example 25, the coating liquid 10 was used as the coating liquid for the alignment layer. In Example 25, the thickness H of the alignment layers 14 and 15 was set to 75 nm.

[0111] [Example 26] In Example 26, the coating liquid for the alignment layer was the coating liquid 11. In Example 26, the thickness H of the alignment layers 14 and 15 was set to 75 nm.

[0112] [Example 27] In Example 27, the coating liquid for the alignment layer was the coating liquid 12. In Example 27, the thickness H of the alignment layers 14 and 15 was set to 30 nm.

[0113] [Evaluation method] [Alignment layer thickness] An arbitrary 100 mm square area in each of the alignment layers 14, 15 was set as the measurement area. Then, the thickness of the alignment layers 14, 15 was measured at any 10 points within the measurement area. Subsequently, the thickness H of each alignment layer 14, 15 was calculated by dividing the sum of the measured values ​​at each point by the number of measurements. At this time, a scanning electron microscope (Regulus8220, manufactured by Hitachi High-Technologies Corporation) (Regulus is a registered trademark) was used to measure the thickness of the alignment layers 14, 15.

[0114] [Haze value] The haze value of the light-control sheet 2 of each example and comparative example was measured when transparent, i.e., when no voltage was applied between the transparent electrode layers 11 and 12. The method used was in accordance with JIS K 7136:2000 "Determination of haze for plastics - transparent materials." A haze meter (NDH-7000, manufactured by Nippon Denshoku Industries Co., Ltd.) was used to measure the haze value.

[0115] [Peel strength] A 25 mm wide test piece was cut from the light-controlling sheet 2 of each example and comparative example. The peel strength of the first alignment layer 14 from the light-controlling layer 13 was measured using a method conforming to JIS Z 0237:2009 "Test Methods for Adhesive Tapes and Sheets." A universal testing machine (Shimadzu Corporation, Autograph AGS-X, Load Cell 5kN) was used to measure the peel strength, and the test speed was set to 300 mm / min. When measuring the peel strength, the first transparent substrate 16 supporting the first alignment layer 14 was peeled off at an angle of 180° from the light-controlling layer 13.

[0116] [Evaluation results] The evaluation results of the haze value and peel strength for the light-control sheets of each example and comparative example are shown in Figures 5 to 8. The measured values ​​of the peel strength and the haze value were each evaluated according to the following three levels.

[0117] [Peel strength] ◎:0.2N / 25mm or more ○: 0.1N / 25mm or more and less than 0.2N / 25mm ×: Less than 0.1N / 25mm

[0118] [Haze value] ◎: Less than 5% ○: 5% or more and less than 10% ×: 10% or more

[0119] As shown in Figure 5, the 180° peel strength was found to be within the range of 0.07 N / 25 mm or more and 0.09 N / 25 mm or less in Comparative Examples 1 to 7. In contrast, the 180° peel strength was found to be within the range of 0.15 N / 25 mm or more and 0.42 N / 25 mm or less in Examples 1 to 27. Thus, the light controlling sheet 2 of the Example was found to have a higher 180° peel strength than the light controlling sheet 2 of the Comparative Example.

[0120] From these results, it can be said that when the value obtained by dividing the thickness H by the average particle diameter D is 2.5 or more, the alignment layers 14, 15 have the same peel strength as when they do not contain the fine particles 14P, 15P, that is, the peel strength cannot be increased. In contrast, it can be said that the peel strength can be increased by setting the value obtained by dividing the thickness H by the average particle diameter D to 2.4 or less, preferably 2.0 or less, and more preferably 1.88 or less.

[0121] The haze value was found to be 20% in Example 1, 30% in Example 5, 60% in Example 9, 75% in Examples 13 and 14, 70% in Example 15, 65% in Example 16, 50% in Examples 18 and 24, 15% in Example 26, and 14% in Example 27. In contrast, the haze value was found to be 5% or more and less than 10% in Examples 6, 10 to 12, 17, 19, 20, and 23 and Comparative Example 7. The haze value was also found to be less than 5% in Examples 2 to 4, 7, 8, 21, 22, and 25 and Comparative Examples 1 to 6 and 8.

[0122] From these results, it can be said that when the value obtained by dividing the thickness H by the average particle diameter D is within the range of 0.22 or more and 0.25 or less, scattering is likely to occur in the alignment layers 14, 15 because the average particle diameter D is large relative to the thickness H of the alignment layers 14, 15. As a result, it can be said that the haze value when transparent is increased. Also, when the content of the fine particles 14P, 15P is 5 wt%, scattering is likely to occur in the alignment layers 14, 15, resulting in an increase in the haze value when transparent. In contrast, it was found that when the content of the fine particles 14P, 15P is 4 wt% or less and the value obtained by dividing the thickness H by the average particle diameter D is 0.38 or more, the haze when transparent is maintained low.

[0123] Furthermore, from the results of the haze values ​​in Examples 26 and 27, it can be said that when the material constituting the microparticles 14P and 15P is silicon dioxide, the haze value when transparent is more likely to be maintained low than when the material constituting the microparticles 14P and 15P is indium tin oxide or zirconium oxide.

[0124] FIG. 6 shows the relationship between the value obtained by dividing the thickness H by the average particle diameter D, that is, the degree of protrusion of the alignment layers 14 and 15, and the peel strength. 6, it was found that, regardless of the content of microparticles 14P and 15P, the peel strength drops sharply when the value obtained by dividing thickness H by average particle diameter D is between 1.5 and 2. Therefore, it can be said that by keeping the value obtained by dividing thickness H by average particle diameter D at 2 or less, preferably 1.5 or less, the peel strength value can be maintained at a high level regardless of the content of microparticles 14P and 15P.

[0125] FIG. 7 shows the relationship between the degree of protrusion of the alignment layers 14 and 15 and the haze value. 7, when the content of fine particles 14P, 15P is 5 wt %, it is difficult to reduce the haze value. However, when the content of fine particles 14P, 15P is 4 wt % or less, it is possible to reduce the haze value by the value obtained by dividing thickness H by average particle diameter D. In particular, when the content of fine particles 14P, 15P is 4 wt % or less, it is possible to reduce the haze value by abruptly increasing the value obtained by dividing thickness H by average particle diameter D within a range of 1 or less. Therefore, from the viewpoint of maintaining a low haze value when transparent, it is preferable that the value obtained by dividing thickness H by average particle diameter D is 0.5 or more, and more preferably 1.0 or more.

[0126] FIG. 8 shows the relationship between the content of the fine particles 14P and 15P and the peel strength. As shown in FIG. 8, it was recognized that regardless of the degree of protrusion, which is the value obtained by dividing the thickness H by the average particle diameter D, the peel strength increased as the content of the fine particles 14P and 15P increased.

[0127] As described above, according to one embodiment, the following effects can be obtained. (1) When the light-controlling sheet 2 satisfies condition 1, the alignment layers 14, 15 have unevenness at the interface between the alignment layers 14, 15 and the light-controlling layer 13, compared to when the alignment layers 14, 15 do not contain inorganic fine particles, which improves the adhesion between the alignment layers 14, 15 and the light-controlling layer 13. As a result, the peel strength between the alignment layers 14, 15 and the light-controlling layer 13 can be increased.

[0128] (2) When the light-controlling sheet 2 satisfies the condition 2, the peel strength between the alignment layers 14, 15 and the light-controlling layer 13 is more reliably increased. (3) When the light controlling sheet 2 satisfies the condition 3, within the range set by the value obtained by dividing the thickness H by the average particle diameter D, a steep decrease in peel strength is suppressed.

[0129] (4) When the dimming sheet 2 satisfies condition 4, the number of irregularities in the alignment layers 14, 15 at the boundary between the alignment layers 14, 15 and the dimming layer 13 is prevented from becoming excessive, and each irregularity is prevented from becoming excessively large.As a result, the haze value of the dimming sheet 2 is prevented from increasing when no voltage is applied between the transparent electrode layers 11, 12.

[0130] (5) When the average particle diameter D is 10 nm or more, it is possible to more reliably increase the peel strength between the alignment layers 14, 15 and the light-controlling layer 13. When the average particle diameter D is 100 nm or less, scattering by the fine particles 14P, 15P is suppressed, thereby suppressing an increase in the haze value of the light-controlling sheet 2 when no voltage is applied between the transparent electrode layers 11, 12.

[0131] (6) When the light-controlling sheet 2 satisfies condition 6, the particles 14P, 15P can be dispersed in an organic solvent, and a difference in refractive index is unlikely to occur between the particles 14P, 15P and the base material of the alignment layers 14, 15.

[0132] The above-described embodiment can be modified as follows. [Alignment layer] Only one of the first alignment layer 14 and the second alignment layer 15 may contain inorganic fine particles. Even in this case, it is possible to increase the peel strength of the alignment layer between the alignment layer containing inorganic fine particles and the photochromic layer 13. [Explanation of symbols]

[0133] 1...Dimmer 11...First transparent electrode layer 12...Second transparent electrode layer 13...Photochromic layer 14...First alignment layer 15...Second alignment layer 16...First transparent base material 17...Second transparent base material

Claims

1. a first transparent electrode layer; A second transparent electrode layer; a light-controlling layer located between the first transparent electrode layer and the second transparent electrode layer, the light-controlling layer including a transparent polymer layer having voids and a liquid crystal composition located in the voids; a first alignment layer located between the first transparent electrode layer and the light control layer; a second alignment layer located between the second transparent electrode layer and the light control layer; A light-controlling sheet configured to increase the haze value of the light-controlling sheet by applying a voltage between the first transparent electrode layer and the second transparent electrode layer, At least one of the first alignment layer and the second alignment layer contains inorganic fine particles, In the alignment layer containing the inorganic fine particles, of the first alignment layer and the second alignment layer, an average particle diameter D of the inorganic fine particles and a thickness H of the alignment layer satisfy the following: H / D≦2.4, Dimming sheet.

2. When the weight of the alignment layer is taken as 100% by weight, the alignment layer contains 0.5% by weight or more of the inorganic fine particles, and The average particle diameter D and the thickness H satisfy the following: H / D≦2.0 The light-controlling sheet according to claim 1 .

3. The average particle diameter D and the thickness H satisfy the following: H / D≦1.67 The light-controlling sheet according to claim 1 or 2.

4. When the weight of the alignment layer is taken as 100% by weight, the alignment layer contains 4% by weight or less of the inorganic fine particles, and The average particle diameter D and the thickness H satisfy the following: H / D≧0.38 The light-controlling sheet according to claim 1 or 2.

5. The average particle diameter D is 10 nm or more and 100 nm or less. The light-controlling sheet according to claim 1 or 2.

6. The inorganic fine particles are composed of silicon dioxide. The light-controlling sheet according to claim 1 or 2.

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