Light control sheet

Abstract

This light control sheet comprises a first transparent electrode sheet, a second transparent electrode sheet, and a light control layer located between the first transparent electrode sheet and the second transparent electrode sheet. The light control layer includes a transparent polymer layer including a plurality of voids, a liquid crystal composition located in each void, and a spacer. The liquid crystal composition contains a liquid crystal compound and a dichroic dye. A first brightness of the spacer is L*1. A second brightness of the light control sheet exhibiting an opaque state is L*2. A brightness difference that is an absolute value obtained by subtracting the first brightness L*1 from the second brightness L*2 is ΔL*. The areal percentage (%) of the spacer in the light control layer is SR in a plan view facing a plane over which the light control sheet spreads. A value obtained by multiplying the brightness difference ΔL* and the areal percentage SR together satisfies the following.　20 ≤ ΔL*×SR ≤ 81

Description

Light-adjusting sheet

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

[0002] The light-controlling sheet includes a first transparent electrode sheet, a second transparent electrode sheet, and a light-controlling layer. The light-controlling layer is located between the first transparent electrode sheet and the second transparent electrode sheet. The light-controlling layer includes a transparent polymer layer containing a plurality of voids, a liquid crystal compound located in the voids, and spacers that determine the thickness of the light-controlling layer. The spacers are dispersed throughout the light-controlling layer (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-078443

[0004] Incidentally, light-controlling sheets installed on window glass in buildings are required to have high transmittance in order to increase the efficiency of light transmission through the light-controlling sheet. For this reason, white granular spacers are often used as the spacers contained in the light-controlling layer.

[0005] In recent years, the applications of light-controlling sheets have become increasingly diverse, including partitions installed in offices and medical facilities, and windows in vehicles and aircraft. Light-controlling sheets used in these applications are required to be able to protect privacy, so light-controlling sheets containing dichroic dyes that exhibit a specific color have been proposed. Compared to light-controlling sheets that do not contain dichroic dyes, these light-controlling sheets tend to have a larger difference in the amount of light transmitted through the spacer-located areas of the light-controlling layer and the transparent polymer layer or liquid crystal compound-located areas. As a result, the light-controlling sheet is prone to exhibiting poor in-plane appearance.

[0006] One embodiment of the light-controlling sheet comprises a first transparent electrode sheet, a second transparent electrode sheet, and a light-controlling layer located between the first and second transparent electrode sheets. The light-controlling sheet can be reversibly switched between a transparent state and an opaque state depending on whether or not a voltage is applied to the light-controlling sheet. The light-controlling layer comprises a transparent polymer layer containing a plurality of voids, a liquid crystal composition located in the voids, and a spacer. The liquid crystal composition comprises a liquid crystal compound and a dichroic dye. The first brightness of the spacer is L ＊1, and the second lightness of the light-controlling sheet exhibiting the opaque state is L ＊ 2, and the second lightness L ＊ 2 to the first lightness L ＊ The absolute value of the brightness difference obtained by subtracting 1 is ΔL ＊ In a plan view opposite to the plane on which the light-controlling sheet spreads, the area occupancy (%) of the spacers in the light-controlling layer is SR. ＊ and the area occupancy SR satisfy the following: 20≦ΔL ＊ ×SR≦81

[0007] One embodiment of the light-controlling sheet comprises a first transparent electrode sheet, a second transparent electrode sheet, and a light-controlling layer located between the first transparent electrode sheet and the second transparent electrode sheet. The light-controlling layer comprises a transparent polymer layer including a plurality of voids, a liquid crystal composition located in the voids, and spacers. The liquid crystal composition comprises a liquid crystal compound and a dichroic dye. The first brightness of the spacer is L ＊ 1, and in a plan view opposite to the plane on which the light-controlling sheet spreads, the area occupancy rate of the spacer in the light-controlling layer is SR, and the first brightness L ＊ The product of 1 and the area occupancy rate SR satisfies the following: 0.2≦L ＊ 1×SR≦0.83

[0008] Fig. 1 is a cross-sectional view showing the structure of a normal-type light-adjusting sheet. Fig. 2 is a cross-sectional view showing the structure of a reverse-type light-adjusting sheet. Fig. 3 is a cross-sectional view showing the structure of the light-adjusting layer provided in the light-adjusting sheet shown in Fig. 1. Fig. 4 is a schematic diagram for explaining a testing method for the light-adjusting sheet. Fig. 5 is a table showing the evaluation results of test examples. Fig. 6 is a table showing the evaluation results of test examples.

[0009] An embodiment of a light controlling sheet will be described with reference to Figures 1 to 3. The light controlling sheet of the present disclosure may be of either a normal type or a reverse type. Below, we will explain the conditions that the light controlling sheet of the present disclosure satisfies regardless of the type of light controlling sheet, and then we will explain a normal type light controlling device equipped with a normal type light controlling sheet with reference to Figure 1, and we will explain a reverse type light controlling device equipped with a reverse type light controlling sheet with reference to Figure 2.

[0010] The light-controlling sheet is attached to a transparent member provided in a window of a moving object such as a vehicle or an aircraft. Alternatively, the light-controlling sheet may be attached to a transparent member provided in a window of various buildings such as a house, a station, or an airport, a partition installed in an office, or a show window installed in a store. The shape of the light-controlling sheet may be flat or curved.

[0011] [Light-modulating sheet] [First embodiment] A first embodiment of the light-modulating sheet of the present disclosure comprises a first transparent electrode sheet, a second transparent electrode sheet, and a light-modulating layer located between the first transparent electrode sheet and the second transparent electrode sheet. The light-modulating sheet can be reversibly switched between a transparent state and an opaque state depending on whether or not a voltage is applied to the light-modulating sheet. The light-modulating layer includes a transparent polymer layer containing a plurality of voids, a liquid crystal composition located in the voids, and a spacer. The liquid crystal composition includes a liquid crystal compound and a dichroic dye. The first brightness of the spacer is L ＊ 1, and the second lightness of the light-controlling sheet exhibiting an opaque state is L ＊ 2, and the second brightness L ＊ 2 to 1st brightness L ＊ The absolute value of the brightness difference obtained by subtracting 1 is ΔL ＊ In a plan view opposite to the plane on which the light-controlling sheet spreads, the area occupancy rate (%) of the spacers in the light-controlling layer is SR. The light-controlling sheet satisfies the following condition 1-1. (Condition 1-1) Lightness difference ΔL ＊ The multiplication value of ΔL and the area occupancy rate SR satisfies the following: 20≦ΔL ＊ ×SR≦81

[0012] When the amount of spacers contained in the light-controlling layer is at least, and the brightness difference, which is the difference between the first brightness of each spacer and the second brightness of the light-controlling sheet, is large, an observer viewing the light-controlling sheet is likely to see each spacer dispersed throughout the light-controlling sheet. On the other hand, even if the brightness difference is small, if the area ratio occupied by all spacers in the light-controlling layer is high, there is a high probability that each spacer will be visible to the observer, and there is also a high possibility that a collection of multiple spacers will be perceived by the observer as a single object. As a result, the observer will recognize that there is unevenness in the appearance of the light-controlling sheet within the surface of the light-controlling sheet. Unevenness is an example of an appearance defect.

[0013] In this regard, because the product of the lightness difference between the spacer and the light-controlling sheet and the area occupancy of the spacer satisfies the above range, the lightness difference and the area occupancy are prevented from becoming excessively large, making the spacers in the light-controlling layer less visible and reducing unevenness in the appearance of the light-controlling sheet within its plane.

[0014] If it is required to further reduce the unevenness of the appearance within the surface of the light-controlling sheet, the lightness difference ΔL ＊ It is preferable that the upper limit of the multiplication value of the surface area ratio SR be small. The upper limit may be, for example, 70, 60, or 30.

[0015] The light-controlling sheet may satisfy the following conditions 1-2 and 1-3. (Condition 1-2) Lightness difference ΔL ＊ is equal to or greater than 20 and equal to or less than 74. (Condition 1-3) The area occupancy rate SR is equal to or greater than 1% and equal to or less than 3%.

[0016] When the light-control sheet satisfies conditions 1-2 and 1-3, the brightness difference ΔL ＊ Therefore, it is more effective that the multiplied value of the area occupancy SR satisfies the above range.

[0017] [Second embodiment] A second embodiment of the light-controlling sheet of the present disclosure includes a first transparent electrode sheet, a second transparent electrode sheet, and a light-controlling layer located between the first transparent electrode sheet and the second transparent electrode sheet. The light-controlling layer includes a transparent polymer layer including a plurality of voids, a liquid crystal composition located in the voids, and spacers. The liquid crystal composition includes a liquid crystal compound and a dichroic dye. The first brightness of the spacer is L ＊ 1, and when the area occupancy rate of the spacers in the light-controlling layer is SR in a plan view opposite to the plane on which the light-controlling sheet spreads, the light-controlling sheet satisfies the following condition 2-1. (Condition 2-1) First brightness L ＊ The product of 1 and the area occupancy rate SR satisfies the following: 0.2≦L ＊ 1×SR≦0.83

[0018] The brightness L of the object ＊ The higher the value of , the less the object tends to absorb light. Therefore, when the first lightness of each spacer is high, the light not absorbed by each spacer is easily visible. As a result, even if the area occupancy of the spacers contained in the light-controlling layer is low, the light transmitted through the area where the spacers are located is easily visible, and the appearance of the light-controlling sheet is likely to be mottled. On the other hand, when the lightness L of each spacer in the light-controlling layer is low, the light transmitted through the area where the spacers are located is easily visible, and the appearance of the light-controlling sheet is likely to be mottled. ＊ Even if the surface area occupancy rate SR of the spacers is low, if the surface area occupancy rate SR of the spacers is high, multiple spacers are likely to be perceived as a single bright area. As a result, the in-plane appearance of the light-controlling sheet is likely to be perceived as having a mottled appearance. The mottled appearance is an example of an appearance defect in which the spacers stand out compared to the other parts of the light-controlling sheet, giving the impression of being mottled.

[0019] In this regard, according to the light controlling sheet of the present disclosure, the first brightness L ＊ Since the product of 1 and the area occupancy rate satisfies the above-mentioned range, the in-plane appearance of the light controlling sheet is less likely to be mottled. In other words, it is possible to suppress the in-plane appearance of the light controlling sheet.

[0020] When it is required to further reduce the uneven appearance of the light-controlling sheet, the area occupancy rate SR and the first lightness L ＊ It is preferable that the upper limit value for the multiplication value with 1 is small. The upper limit value may be, for example, 0.65, 0.45, or 0.30.

[0021] The light-controlling sheet can be reversibly switched between transparency and opaqueness depending on whether or not a voltage is applied to the light-controlling sheet. ＊ In the case of 2, the light controlling sheet may satisfy the following condition 2-2. (Condition 2-2) Second lightness L ＊ The absolute value obtained by subtracting the multiplied value from 2 satisfies the following: 0≦|L ＊ 2-L ＊ 1×SR|≦0.66

[0022] If the light-adjusting sheet satisfies condition 2-2, when the light-adjusting sheet becomes opaque, the difference in brightness between the light-adjusting sheet and the spacer is reduced, thereby reducing the visibility of the spacer.

[0023] When it is required to further reduce the uneven appearance of the light controlling sheet, the second lightness L ＊ It is preferable that the upper limit value of the absolute value obtained by subtracting the multiplied value from 2 is small. The upper limit value may be, for example, 0.63, 0.45, 0.30, or 0.10.

[0024] The light-controlling sheet may satisfy the following conditions 2-3 and 2-4. (Condition 2-3) First lightness L ＊ 1 is equal to or greater than 21 and equal to or less than 27. (Condition 2-4) The area occupancy ratio SR is equal to or greater than 0.01 and equal to or less than 0.03.

[0025] When the light-controlling sheet satisfies the conditions 2-3 and 2-4, the first brightness L ＊ The effectiveness of the multiplication of 1 and the surface area occupancy rate SR satisfying the above-mentioned range is enhanced.

[0026] 1 , a normal-type light control device 10N includes a normal-type light control sheet 11N and a drive unit 12. The light control sheet 11N includes a first transparent electrode sheet 21, a second transparent electrode sheet 22, and a light control layer 23. The light control sheet 11N is configured so that the light control layer 23 can be switched between a transparent state and an opaque state by switching between a state in which a voltage is applied between the first transparent electrode sheet 21 and the second transparent electrode sheet 22 and a state in which it is not applied.

[0027] The first transparent electrode sheet 21 includes a first transparent electrode layer 21A and a first transparent substrate 21B that supports the first transparent electrode layer 21A. The second transparent electrode sheet 22 includes a second transparent electrode layer 22A and a second transparent substrate 22B that supports the second transparent electrode layer 22A.

[0028] In the light-controlling sheet 11N, the light-controlling layer 23 is located between the first transparent electrode sheet 21 and the second transparent electrode sheet 22. The first transparent electrode layer 21A is located between the first transparent substrate 21B and the light-controlling layer 23. The second transparent electrode layer 22A is located between the second transparent substrate 22B and the light-controlling layer 23.

[0029] The light-controlling sheet 11N is either transparent or opaque, with a haze value higher than that of transparency, depending on the magnitude of the voltage applied to the light-controlling layer 23. Because the light-controlling sheet 11N provided in the normal-type light-controlling device 10N is a normal type, the light-controlling sheet 11N is opaque when no voltage is applied to the light-controlling layer 23. In contrast, the light-controlling sheet 11N is transparent when a voltage is applied to the light-controlling layer 23. For the normal-type light-controlling sheet 11N, when a voltage is applied to the light-controlling sheet 11N, the state in which the haze value is saturated on the V (voltage)-H (haze) curve is the transparent state of the light-controlling sheet 11N.

[0030] For example, the haze value of the opaque light-controlling sheet 11N may be 80% or more, and the haze value of the transparent light-controlling sheet 11N may be 5% or less. The haze value of the light-controlling sheet 11N is a value measured by a method in accordance with JIS K 7136:2000 "Determination of haze of plastic transparent materials."

[0031] The light controlling sheet 11N includes a first electrode 21E attached to a portion of the first transparent electrode layer 21A and a second electrode 22E attached to a portion of the second transparent electrode layer 22A. The light controlling sheet 11N further includes a wiring 24 connected to the first electrode 21E and a wiring 24 connected to the second electrode 22E. The first electrode 21E is connected to the drive unit 12 via the wiring 24. The second electrode 22E is connected to the drive unit 12 via the wiring 24.

[0032] The first transparent electrode sheet 21 and the second transparent electrode sheet 22 apply a voltage to the light-controlling layer 23 to switch the light-controlling layer 23 between transparent and opaque. Each transparent electrode sheet 21, 22 has optical transparency that allows visible light to pass through. The optical transparency of the first transparent electrode sheet 21 enables visual recognition of objects through the light-controlling sheet 11N. The optical transparency of the second transparent electrode sheet 22, like the optical transparency of the first transparent electrode sheet 21, enables visual recognition of objects through the light-controlling sheet 11N.

[0033] The material for forming each transparent electrode layer 21A, 22A may be, for example, any one selected from the group consisting of indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, and poly(3,4-ethylenedioxythiophene).

[0034] The material forming each of the transparent substrates 21B, 22B may be a synthetic resin or an inorganic compound. Examples of synthetic resins include polyester, polyacrylate, polycarbonate, and polyolefin. Examples of polyesters include polyethylene terephthalate and polyethylene naphthalate. Examples of polyacrylates include polymethyl methacrylate. Examples of inorganic compounds include silicon dioxide, silicon oxynitride, and silicon nitride.

[0035] Each of the electrodes 21E, 22E is, for example, a flexible printed circuit (FPC). The FPC includes a support layer, a conductor portion, and a protective layer. The conductor portion is sandwiched between the support layer and the protective layer. The support layer and the protective layer are formed of an insulating synthetic resin. The support layer and the protective layer are formed of, for example, polyimide. The conductor portion is formed of, for example, a thin metal film. The thin metal film may be formed of, for example, copper. Each of the electrodes 21E, 22E is not limited to an FPC, and may be, for example, a metal tape.

[0036] Each of the electrodes 21E and 22E is attached to the corresponding transparent electrode layer 21A and 22A by a conductive adhesive layer (not shown). In each of the electrodes 21E and 22E, the conductor portion is exposed from the protective layer or the support layer at the portion connected to the conductive adhesive layer.

[0037] The conductive adhesive layer may be formed of, for example, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), an isotropic conductive film (ICF), an isotropic conductive paste (ICP), etc. From the viewpoint of ease of handling in the manufacturing process of the normal-type dimming device 10N, the conductive adhesive layer is preferably an anisotropic conductive sheet.

[0038] Each of the wirings 24 is formed of, for example, a metal wire and an insulating layer covering the metal wire. The wire is formed of, for example, copper.

[0039] The driver 12 is configured to be able to apply a voltage to the light-controlling layer 23 included in the light-controlling sheet 11N. The driver 12 applies an AC voltage between the first transparent electrode layer 21A and the second transparent electrode layer 22A. The driver 12 preferably applies an AC voltage having a rectangular waveform between the pair of transparent electrode layers 21A, 22A. In other words, the driver 12 preferably outputs a rectangular wave voltage signal.

[0040] [Reverse-type dimming device] The reverse-type dimming device 10R shown in Fig. 2 differs from the above-described normal-type dimming device 10N in that it includes a reverse-type dimming sheet 11R. The differences between the reverse-type dimming device 10R and the normal-type dimming device 10N will be described in detail below. Meanwhile, components of the reverse-type dimming device 10R that are common to the normal-type dimming device 10N are assigned the same reference numerals as those of the normal-type dimming device 10N, and detailed descriptions of those components will be omitted.

[0041] 2, the reverse dimming device 10R includes a reverse dimming sheet 11R and a drive unit 12. In addition to the layer structure of the normal dimming sheet 11N, the dimming sheet 11R includes a first alignment film 21C and a second alignment film 22C. Therefore, in the reverse dimming device 10R, the first transparent electrode sheet 21 includes the first alignment film 21C in addition to the first transparent electrode layer 21A and the first transparent substrate 21B. The second transparent electrode sheet 22 includes the second alignment film 22C in addition to the second transparent electrode layer 22A and the second transparent substrate 22B.

[0042] The light-controlling layer 23 is located between the first alignment film 21C and the second alignment film 22C. The first alignment film 21C is located between the light-controlling layer 23 and the first transparent electrode layer 21A, and is in contact with the light-controlling layer 23. The second alignment film 22C is located between the light-controlling layer 23 and the second transparent electrode layer 22A, and is in contact with the light-controlling layer 23.

[0043] The material for forming the first alignment film 21C and the second alignment film 22C may be an organic compound, an inorganic compound, or a mixture thereof. The organic compound may be, for example, polyimide, polyamide, polyvinyl alcohol, or a cyanide compound. The inorganic compound may be, for example, silicon oxide or zirconium oxide. The material for forming the alignment films 21C and 22C may be silicone. Silicone is a compound having both an inorganic portion and an organic portion.

[0044] The first alignment film 21C and the second alignment film 22C are, for example, vertical alignment films. The vertical alignment films align the long axes of the liquid crystal compounds so that they are perpendicular to the surface opposite to the surface in contact with the first transparent electrode layer 21A and the surface opposite to the surface in contact with the second transparent electrode layer 22A. In this way, the alignment films 21C and 22C regulate the orientation of the multiple liquid crystal compounds contained in the light control layer 23.

[0045] The light-adjusting sheet 11R is transparent or opaque with a haze value higher than that of transparency, depending on the magnitude of the voltage applied to the light-adjusting layer 23. Because the light-adjusting sheet 11R provided in the reverse-type light-adjusting device 10R is a reverse type, the light-adjusting sheet 11R is transparent when no voltage is applied to the light-adjusting layer 23. In contrast, the light-adjusting sheet 11R is opaque when a voltage is applied to the light-adjusting sheet 11R. Therefore, the reverse-type light-adjusting sheet 11R is transparent when no voltage is applied to the light-adjusting sheet 11R. With the reverse-type light-adjusting sheet 11R, when a voltage is applied to the light-adjusting sheet 11R, the opaque state of the light-adjusting sheet 11R is the state in which the haze value is saturated in the V (voltage)-H (haze) curve.

[0046] For example, the haze value of the opaque light-controlling sheet 11R may be 80% or more, and the haze value of the transparent light-controlling sheet 11R may be 5% or less. The haze value of the light-controlling sheet 11R is a value measured by a method in accordance with JIS K 7136:2000 "Determination of haze of plastic transparent materials."

[0047] [Light Control Layer] Fig. 3 shows the cross-sectional structure of a normal-type light control sheet 11N. Note that a reverse-type light control sheet 11R has the same layer structure as the structure shown in Fig. 3, except that it includes a first alignment film 21C and a second alignment film 22C.

[0048] 3, the light-controlling layer 23 includes a transparent polymer layer 23P including a plurality of voids 23D, a liquid crystal composition 23LC located in the voids 23D, and spacers SP. The liquid crystal composition 23LC includes a liquid crystal compound LCM and a dichroic dye DD.

[0049] As described above, in the first embodiment, the brightness difference is ΔL ＊ In addition, when the area occupancy rate of the spacers SP in the light-controlling layer 23 is SR in a plan view opposite to the plane on which the light-controlling sheet 11N spreads, the light-controlling sheet satisfies condition 1-1. ＊ When the multiplication value of the area occupancy rate SR is 20 or more, the photochromic layer 23 can contain a sufficient amount of spacers SP to suppress variation in the thickness of the photochromic layer 23 within the plane of the photochromic layer 23.

[0050] On the other hand, in the second embodiment, as described above, the first brightness of the spacer SP is L ＊ 1, and when the area occupancy rate of the spacers SP in the light-controlling layer 23 is SR in a plan view opposite to the plane on which the light-controlling sheet 11N spreads, the light-controlling sheet satisfies condition 2-1. ＊ By setting the multiplication value by 1 to 0.2 or more, the photochromic layer 23 can contain a sufficient amount of spacers SP to suppress variations in the thickness of the photochromic layer 23 within the plane of the photochromic layer 23.

[0051] The light control layer 23 is of a polymer dispersion type. The polymer dispersion type light control layer 23 may be a polymer network type light control layer 23 or an capsule type light control layer 23. The polymer network type light control layer 23 includes a transparent polymer layer 23P having a three-dimensional mesh shape, and holds a liquid crystal composition 23LC in interconnected mesh voids 23D. The capsule type light control layer 23 holds a liquid crystal composition 23LC in capsule-shaped voids 23D dispersed in the transparent polymer layer 23P.

[0052] [Liquid Crystal Composition] The liquid crystal composition 23LC contains a liquid crystal compound LCM. The mass content of the liquid crystal compound LCM relative to the mass of the light-controlling layer 23 may be, for example, 40% by mass or more and 65% by mass or less. That is, the mass M23 of the light-controlling layer 23 and the mass MLCM of the liquid crystal compound LCM may satisfy the following formula: The mass M23 of the light-controlling layer 23 is the sum of the mass MLCM of the liquid crystal compound LCM, the mass M23P of the transparent polymer layer 23P, and the mass MSP of the spacer SP. 40 (mass%)≦(MLCM / M23)×100≦65 (mass%)

[0053] The liquid crystal composition 23LC may contain additives such as an antifoaming agent, an antioxidant, a weathering agent, a solvent, a viscosity reducing agent, etc. The weathering agent may be an ultraviolet absorber or a light stabilizer.

[0054] The liquid crystal compound LCM may have positive dielectric anisotropy. When the liquid crystal compound LCM has positive dielectric anisotropy, the dielectric constant ε∥ of the liquid crystal compound LCM in the long axis direction is higher than the dielectric constant ε⊥ of the liquid crystal compound LCM in the short axis direction. The liquid crystal compound LCM may have negative dielectric anisotropy. When the liquid crystal compound LCM has negative dielectric anisotropy, the dielectric constant ε∥ of the liquid crystal compound LCM in the long axis direction is lower than the dielectric constant ε⊥ of the liquid crystal compound LCM in the short axis direction. The dielectric anisotropy of the liquid crystal compound LCM is appropriately selected based on the type of the light controlling sheets 11N and 11R. The normal-type light controlling sheet 11N may contain, for example, a liquid crystal compound LCM having positive dielectric anisotropy. The reverse-type light controlling sheet 11R may contain, for example, a liquid crystal compound LCM having negative dielectric anisotropy.

[0055] The liquid crystal compound LCM is at least one selected from the group consisting of, for example, 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 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. The refractive index difference of the liquid crystal compounds LCM may be 0.05 or more. The dielectric constant difference of the liquid crystal compounds LCM may be 2 or more or -2 or less.

[0056] An example of the structure of the liquid crystal compound LCM is represented by the following formula 1: １１ -A １１ -Z １１ -A １２ -Z １２ -A １３ -Z １３ -A １４ -R １２ ...Equation (1) R shown in Equation 1 １１ is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. １１ One or two or more non-adjacent methylene bonds contained in the alkyl group of formula (1) can be substituted with any one selected from the group consisting of an oxygen atom, an ethylene bond, an ester bond, and a diether bond. １２ is a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group, or an alkyl group having 1 to 15 carbon atoms. １２ One or two or more non-adjacent methylene bonds contained in the alkyl group can be substituted with any bond selected from the group consisting of an oxygen atom, an ethylene bond, an ester bond, and a diether bond.

[0057] A shown in formula (1) １１ , A １２ , A １３ , A １４each independently represents a 1,4-phenylene group or a 2,6-naphthylene group. One or more hydrogen atoms in the 1,4-phenylene group or the 2,6-naphthylene group can be substituted with a fluorine atom, a chlorine atom, a trifluoromethyl group, or a trifluoromethoxy group. １１ , A １２ , A １３ , A １４ may each independently represent a 1,4-cyclohexylene group, a 3,6-cyclohexenylene group, a 1,3-dioxane-2,5-diyl group, or a pyridine-2,5-diyl group. １３ , A １４ may each independently be a single bond. １１ , Z １２ , Z １３ each independently represents any one bond selected from the group consisting of a single bond, an ester bond, a diether bond, an ethylene bond, a fluoroethylene bond, and a carbonyl bond.

[0058] [Transparent Polymer Layer] The transparent polymer layer 23P is a cured product of a photopolymerizable compound. The light for polymerizing the photopolymerizable compound may be ultraviolet light or an electron beam. The photopolymerizable compound may be an ultraviolet-polymerizable composition or an electron-beam-polymerizable composition. The lower and upper limits of the content of the transparent polymer layer 23P in the light-controlling layer 23 are within a range in which liquid crystal particles composed of the liquid crystal compound LCM phase-separate from the polymer of the photopolymerizable compound during the polymerization process of the photopolymerizable compound. If it is necessary to increase the mechanical strength of the transparent polymer layer 23P, it is preferable that the lower limit of the content of the transparent polymer layer 23P is high. If it is necessary to lower the voltage for driving the liquid crystal compound LCM, it is preferable that the upper limit of the content of the transparent polymer layer 23P is low.

[0059] The photocurable compound forming the transparent polymer layer 23P may be at least one selected from the group consisting of acrylate compounds, methacrylate compounds, styrene compounds, thiol compounds, and oligomers of each of these compounds. The acrylate compound may be at least one selected from the group consisting of monoacrylate compounds, diacrylate compounds, triacrylate compounds, and tetraacrylate compounds. The acrylate compound may be at least one selected from the group consisting of butyl ethyl acrylate, ethylhexyl acrylate, and cyclohexyl acrylate. The methacrylate compound may be at least one selected from the group consisting of dimethacrylate compounds, trimethacrylate compounds, and tetramethacrylate compounds. The methacrylate compound may be at least one selected from the group consisting of N,N-dimethylaminoethyl methacrylate, phenoxyethyl methacrylate, methoxyethyl methacrylate, and tetrahydrofurfuryl methacrylate. The thiol compound may be 1,3-propanedithiol or 1,6-hexanedithiol. The styrene compound may be styrene or methylstyrene.

[0060] For example, by changing the size of the voids 23D in the transparent polymer layer 23P from a first value to a second value, the second brightness L of the light controlling sheet 11N can be increased. ＊ 2 can be changed from a first value to a second value.

[0061] [Spacer] The spacers SP are dispersed throughout the transparent polymer layer 23P. The thickness of the spacers SP determines the thickness of the light-controlling layer 23. The thickness of the spacers SP may be the particle size of the spacers SP. The spacers SP make the thickness of the light-controlling layer 23 uniform. The spacers SP may be bead spacers or photospacers formed by exposing and developing a photoresist. The spacers SP may be colorless and transparent, colored and transparent, or colored and opaque. The color of the spacers SP preferably exhibits the same color as the color exhibited by the dichroic dye DD.

[0062] For example, the outer surface of the spacer SP may be black. In this case, light transmission through the outer surface of the spacer SP is suppressed, and the transmitted light is prevented from being locally visible within the plane of the light controlling sheet 11N. This further reduces poor appearance within the plane of the light controlling sheet 11N.

[0063] Alternatively, the spacer SP may have an outer surface and a center portion covered by the outer surface, and the center portion may be black. In this case, the center portion of the spacer SP as well as the outer surface of the spacer SP is black, further increasing the absorbance of the spacer SP. This further reduces light transmission through the spacer SP, making the spacer SP less visible. As a result, poor appearance within the plane of the light controlling sheet 11N is further reduced.

[0064] The total light transmittance of the spacer SP may be 30% or less. In this case, light transmission through the spacer SP is suppressed, thereby preventing the light that has transmitted locally within the plane of the light controlling sheet 11N from being visible. When improved transmittance is required for the transparent light controlling sheet 11N, the total light transmittance of the material that constitutes the spacer may be, for example, 80% or more. The total light transmittance of the spacer SP is a value measured by a method in accordance with ASTM D 1003-00 "Standard Test Method For Haze And Luminous Transmittance Of Transparent Plastics."

[0065] For example, by changing the color of the spacer SP from a first color to a second color, the first brightness L of the spacer SP can be ＊ For example, the first brightness L of the spacer SP can be changed by changing the area occupancy rate of the area exhibiting a predetermined color on the outer surface of the spacer SP from the first value to the second value. ＊ It is possible to change 1 from a first value to a second value.

[0066] For example, by changing the number of spacers SP per unit area from a first value to a second value, the area occupancy rate SR of the spacers SP can be changed from a first value to a second value. Also, by changing the average diameter of the spacers SP from a first value to a second value, the area occupancy rate SR of the spacers SP can be changed from a first value to a second value.

[0067] The spacers SP may have a spherical shape or a columnar shape. The size of the spacers SP in the thickness direction of the photochromic layer 23 is appropriately changed based on the thickness required for the photochromic layer 23. The size of the spacers SP in the thickness direction of the photochromic layer 23 may be, for example, 5 μm or more and 50 μm or less. When the spacers SP have a spherical shape, the average particle diameter of the spacers may be, for example, 5 μm or more and 50 μm or less. The average particle diameter of the spacers SP is obtained using a particle size distribution measuring device using principles such as laser light scattering, electrical resistance change, and image analysis after imaging. The average particle diameter of the spacers SP is the number average particle diameter. When the spacers SP have a columnar shape, the average diameter of the spacers is, for example, 5 μm or more and 50 μm or less. When power saving of the dimming sheets 11N and 11R is required, in order to reduce the thickness of the dimming layer 23, it is preferable that the average particle diameter of the spacers SP, or the average diameter of the spacers SP, is, for example, 5 μm or more and 30 μm or less.

[0068] The average particle size of the spacers SP may be 5 μm or more and 30 μm or less. When the average particle size of the spacers SP is within the range of 5 μm or more and 30 μm or less, in the first embodiment, the lightness difference ΔL ＊ On the other hand, in the second embodiment, when the average particle diameter of the spacers SP is within the range of 5 μm or more and 30 μm or less, the first lightness L of the spacers SP is increased. ＊ The effectiveness of the multiplication of 1 and the surface area occupancy rate SR satisfying the above-mentioned range is enhanced.

[0069] As described above, the area occupancy SR of the spacers SP may be, for example, 1% or more and 3% or less. In other words, as described above, the area occupancy SR of the spacers SP may be, for example, 0.01 or more and 0.03 or less. The area occupancy SR of the spacers SP is the ratio of the area occupied by the spacers SP to the unit area of ​​the light-controlling sheet 11N. The area occupied by the spacers SP is obtained by observing the transparent light-controlling sheet 11N from a viewpoint opposite one of a pair of opposing surfaces in the thickness direction. An example of the unit area of ​​the light-controlling sheet 11N is 1 mm x 1 mm. The area occupied by the spacers SP is calculated by observing the unit area of ​​the transparent light-controlling sheet 11N using an optical microscope. The slight difference in refractive index between the spacers SP and the transparent polymer layer 23P causes the area corresponding to the spacers SP to appear slightly whiter than the surrounding area in an image captured by the optical microscope. Alternatively, in an image captured by an optical microscope, the area corresponding to the spacer SP is made slightly darker than the surrounding area. The area occupied by the spacer SP is obtained by binarizing the image captured by the optical microscope and then adding up the area of ​​the granular areas that are slightly whiter than the surrounding area. If the spacer SP has a spherical shape, the granular areas also have a spherical shape. If the spacer SP has a cylindrical shape, the granular areas also have a rectangular shape.

[0070] The material forming the spacers SP may be a transparent inorganic compound having insulating properties or a transparent resin having insulating properties. The transparent inorganic compound is any one selected from the group consisting of silicon dioxide and aluminum oxide. The transparent resin is at least one selected from the group consisting of acrylic resin, epoxy resin, phenolic resin, melamine resin, polyester, polycarbonate, polyolefin, polyvinyl chloride, polyvinylidene chloride, polystyrene, and acetyl cellulose. When the spacers SP are colored and transparent, the material forming the spacers SP may be a transparent resin in which a colored pigment is dispersed. When the spacers SP are dispersed in a coating liquid for forming the light-controlling layer 23, i.e., a liquid containing a photocurable compound and a liquid crystal composition, the surfaces of the spacers SP may be subjected to a surface treatment to impart lyophilicity to the coating liquid.

[0071] The refractive index of the material forming the spacers SP may be 1.4 or more and 1.6 or less, and is different from the refractive index of the transparent polymer layer 23P constituting the light-controlling layer 23.

[0072] [Dichroic Dye] The dichroic dye DD exhibits color when driven by a guest-host system using a liquid crystal compound LCM as a host. The dichroic dye DD is, for example, at least one selected from the group consisting of polyiodine, azo compounds, anthraquinone compounds, naphthoquinone compounds, azomethine compounds, tetrazine compounds, quinophthalone compounds, merocyanine compounds, perylene compounds, and dioxazine compounds. The dichroic dye DD may be a single compound or a combination of two or more compounds. When increased light resistance and an increased dichroic ratio are required, the dichroic dye DD is preferably at least one selected from the group consisting of azo compounds and anthraquinone compounds, and more preferably an azo compound.

[0073] The dichroic dye DD preferably exhibits black color. When the dichroic dye DD exhibits black color, the dichroic dye DD may be a single compound exhibiting black color. Alternatively, the dichroic dye DD may exhibit black color by combining two or more compounds exhibiting colors different from black.

[0074] For example, by changing the content of the dichroic dye DD in the light-controlling layer 23 from a first value to a second value, the second brightness L ＊ 2 can be changed from a first value to a second value.

[0075] [Method for manufacturing light controlling sheet] The method for manufacturing the light controlling sheet 11N includes forming a coating film containing a photopolymerizable compound, a liquid crystal compound LCM, a dichroic dye DD, and a spacer SP between the first transparent electrode sheet 21 and the second transparent electrode sheet 22. When manufacturing the normal-type light controlling sheet 11N, a coating film is formed between the first transparent electrode layer 21A of the first transparent electrode sheet 21 and the second transparent electrode layer 22A of the second transparent electrode sheet 22. In contrast, when manufacturing the reverse-type light controlling sheet 11R, a coating film is formed between the first alignment film 21C of the first transparent electrode sheet 21 and the second alignment film 22C of the second transparent electrode sheet 22.

[0076] The coating film contains a polymerization initiator for initiating polymerization of the photopolymerizable compound. The polymerization initiator is, for example, at least one selected from the group consisting of diketone compounds, acetophenone compounds, benzoin compounds, benzophenone compounds, thioxanthone compounds, and oxime ester compounds. The polymerization initiator may be one type of compound or a combination of two or more types of compounds. An example of the polymerization initiator is any one selected from the group consisting of benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, cyclohexyl phenyl ketone, and phenylacetophenone.

[0077] The manufacturing method of the light controlling sheets 11N and 11R includes polymerizing a photopolymerizable compound in the coating film to phase-separate liquid crystal particles composed of the liquid crystal compound LCM from the polymer. The light irradiated onto the coating film may be irradiated toward the first transparent electrode sheet 21, the second transparent electrode sheet 22, or both the first transparent electrode sheet 21 and the second transparent electrode sheet 22.

[0078] Phase separation of liquid crystal particles composed of the liquid crystal compound LCM proceeds through polymerization of the photopolymerizable compound and diffusion of the liquid crystal compound LCM. The polymerization rate of the photopolymerizable compound varies depending on the intensity of light irradiated onto the photopolymerizable compound. The diffusion rate of the liquid crystal compound LCM varies depending on the processing temperature during polymerization of the photopolymerizable compound. In phase separation of the liquid crystal compound LCM, the intensity of light irradiated onto the photopolymerizable compound is set so that the size of the liquid crystal particles is the desired size, i.e., so that the size of the voids 23D is the desired size. Furthermore, in phase separation of the liquid crystal compound LCM, heating may be performed to promote diffusion of the liquid crystal compound LCM.

[0079] When it is desired to reduce the size of the voids 23D, it is preferable to increase the intensity of the light irradiated onto the photopolymerizable compound and proceed with the polymerization at a low temperature to suppress the diffusion of the liquid crystal compound LCM, whereas when it is desired to increase the size of the voids 23D, it is preferable to decrease the intensity of the light irradiated onto the photopolymerizable compound and proceed with the polymerization at a high temperature to promote the diffusion of the liquid crystal compound LCM.

[0080] [Test Examples] Test examples of the light controlling sheet 11N will be described with reference to Figures 4 to 6. The light controlling sheet 11N in each test example was a normal-type light controlling sheet 11N. The light controlling sheet 11N was obtained by forming a coating film containing a photopolymerizable compound and a liquid crystal compound LCM between the first transparent electrode sheet 21 and the second transparent electrode sheet 22, and then polymerizing the photopolymerizable compound in the coating film.

[0081] The materials listed below were used to form the light controlling sheet 11N of the test example. [Materials] First transparent electrode layer 21A: indium tin oxide Second transparent electrode layer 22A: indium tin oxide First transparent substrate 21B: polyethylene terephthalate film Second transparent substrate 22B: polyethylene terephthalate film Liquid crystal compound LCM: biphenyl-based liquid crystal compound, terphenyl-based liquid crystal compound, tolan-based liquid crystal compound, cyclohexanecarboxylic acid ester-based liquid crystal compound, phenylcyclohexane-based liquid crystal compound, biphenylcyclohexane-based liquid crystal compound, cyano-based liquid crystal compound, fluorine-based liquid crystal compound, 54 parts by weight Dichroic dye DD: blue dichroic dye (product name M-412: manufactured by Mitsui Fine Chemicals, Inc.), 0.5 parts by weight, and black dichroic dye (product name YH-428: manufactured by Mitsui Fine Chemicals, Inc.), 1.5 parts by weight Polymerization initiator: 1-hydroxycyclohexyl phenyl ketone, 3 parts by weight Spacer SP: spherical, 25 μm in diameter Ultraviolet-polymerizable compound : Isobornyl acrylate, pentaerythritol triacrylate, urethane acrylate, 41 parts by weight

[0082] [Test Example 1] A coating liquid was prepared by mixing a liquid crystal compound LCM, a dichroic dye DD, and an ultraviolet-polymerizable compound. Next, 1 part by weight of a spacer SP was mixed with 100 parts by weight of the coating liquid, and 3 parts by weight of a polymerization initiator was mixed with the 100 parts by weight of the coating liquid. A spacer SP with a black color on both the outer surface and the center was used. Next, a coating film having a thickness of 25 μm was formed on the first transparent electrode layer 21A using the coating liquid. Next, with the coating film sandwiched between the first transparent electrode layer 21A and the second transparent electrode layer 22A, ultraviolet light having a wavelength of 365 nm was irradiated toward the first transparent substrate 21B. This resulted in the light-controlling sheet 11N of Test Example 1. At this time, the ultraviolet intensity was set to 10 mW / cm. ２ and the ultraviolet irradiation time was set to 100 seconds.

[0083] Test Example 2 A light controlling sheet 11N of Test Example 2 was obtained in the same manner as in Test Example 1, except that 3 parts by weight of spacer SP was added to 100 parts by weight of the coating liquid.

[0084] [Test Example 3] The light-controlling sheet 11N of Test Example 3 was obtained in the same manner as Test Example 1, except that the spacer SP in Test Example 1 was changed to a spacer SP having a black outer surface and a white central portion covered by the outer surface.

[0085] Test Example 4 A light controlling sheet 11N of Test Example 4 was obtained in the same manner as in Test Example 3, except that the content of the spacer SP in Test Example 3 was changed to 3 parts by weight per 100 parts by weight of the coating liquid.

[0086] [Test Example 5] In Test Example 1, the spacer SP was changed to a spacer SP whose outer surface and center were white, and when preparing the coating liquid by mixing the liquid crystal compound LCM, the dichroic dye DD, and the ultraviolet-polymerizable compound, the proportion of the dichroic dye DD in the coating liquid was reduced. Otherwise, a light-controlling sheet 11N of Test Example 5 was obtained by the same method as Test Example 1.

[0087] Test Example 6 A light controlling sheet 11N of Test Example 6 was obtained in the same manner as in Test Example 1, except that the content of the spacers SP in Example 1 was changed to 4 parts by weight per 100 parts by weight of the coating liquid.

[0088] Test Example 7 A light controlling sheet 11N of Test Example 7 was obtained in the same manner as in Test Example 3, except that the content of the spacer SP in Test Example 3 was changed to 4 parts by weight per 100 parts by weight of the coating liquid.

[0089] [Test Example 8] The light-controlling sheet 11N of Test Example 8 was obtained in the same manner as Test Example 1, except that the spacer SP in Test Example 1 was changed to a spacer SP whose outer surface and the central portion covered by the outer surface were white.

[0090] [Evaluation Method] [Total Light Transmittance] The total light transmittance of the light controlling sheet 11N of each example and each comparative example was measured using a method in accordance with ASTM D 1003-00. No voltage was applied to each light controlling sheet 11N during this measurement. In other words, the total light transmittance of the light controlling sheet 11N was measured when the light controlling sheet 11N was opaque and had the highest haze value.

[0091] As with the light controlling sheet 11N, the total light transmittance of each spacer SP was measured using a method in accordance with ASTM D 1003-00. A measurement sample was prepared by filling a glass sample holder with spacers SP so that the spacers SP were packed tightly together without any gaps. The total light transmittance of the measurement sample was then measured.

[0092] A haze meter (BYK haze-gard instrument, manufactured by BYK Gardner) was used to measure the total light transmittance of the light-control sheet 11N and the spacer SP.

[0093] [Area Occupancy Ratio] Nine measurement areas for measuring the area occupancy ratio were set on the light-adjusting sheet 11N of each example and comparative example. These measurement areas did not overlap each other in a planar view facing the plane on which the light-adjusting sheet 11N was spread. Each measurement area was set to a square with a side length of 1 mm, and the nine measurement areas were set to be equally spaced in a 3-by-3 matrix. Next, an image of each measurement area was obtained by capturing images of each light-adjusting sheet 11N using an optical microscope. After binarizing the captured images, the total area of ​​granular areas that were slightly whiter or blacker than their surroundings was calculated. The total area occupancy ratio of the spacers SP in the measurement area was then calculated by dividing the total area by the area of ​​the measurement area. For each light-adjusting sheet 11N of each example and comparative example, the average value of the area occupancy ratios in the nine measurement areas was calculated, and this average value was set as the area occupancy ratio of the spacers SP in each example and comparative example.

[0094] [Lightness L ＊ ] Second brightness L of the light controlling sheet 11N＊ To obtain 2, first, the Y value of the light-controlling sheet 11N was calculated when no voltage was applied to the light-controlling sheet 11N, i.e., when the light-controlling sheet was opaque. A spectrophotometer (UH4150, Hitachi High-Tech Corporation) was used to measure the spectral reflectance in the range from 360 nm to 830 nm. Then, using a method in accordance with JIS Z 8781-3:2016 "Colorimetry - Part 3: CIE Tristimulus Values," the Y value of the light-controlling sheet 11N, when the Y value of a perfect diffuse reflector was set to 100, was calculated from the measurement results using the spectrophotometer.

[0095] Next, JIS Z 8781-4:2013 "Colorimetry - Part 4: CIE 1976L ＊ a ＊ b ＊ The second brightness L is calculated from the Y value of the light controlling sheet 11N by a method conforming to the "color space" ＊ 2 was calculated.

[0096] First brightness L of spacer SP ＊ To obtain the second lightness L 1, a measurement sample was prepared by first filling a glass sample holder with spacers SP so that the spacers SP were packed tightly together without any gaps, in the same manner as when measuring the total light transmittance of the spacers SP. ＊ After obtaining the Y value of the spacer SP by the same method as in the calculation of 2, the first brightness L ＊ 1 was calculated.

[0097] [Visual Evaluation] Visual evaluation of the light controlling sheet 11N was performed using the method shown in Figure 4. As shown in Figure 4, a light source was positioned opposite the second transparent electrode sheet 22 of the light controlling sheet 11N, and an observer OB was positioned on the opposite side of the light source from the light controlling sheet 11N. Next, light L was irradiated from the light source onto the second transparent electrode sheet 22 of the light controlling sheet 11N to which no voltage was applied, and the observer OB was asked to visually observe the light that had transmitted through the light controlling sheet 11N. Of the visual observation results, the observation results for uneven appearance were evaluated using the following two levels.

[0098] [Uneven appearance] A: The spacers SP are barely visible, so there is almost no uneven appearance within the surface of the light controlling sheet 11N. B: Light transmitted through the spacers SP scattered within the surface of the light controlling sheet 11N is visible, so there is uneven appearance within the surface of the light controlling sheet 11N.

[0099] Furthermore, among the results of visual observation, the results of observation of the appearance of the product with respect to its lumpy texture were evaluated according to the following two levels.

[0100] [Bumpy appearance] A: The spacers SP are barely visible, so there is barely any bumpy appearance within the surface of the light controlling sheet 11N. B: The spacers SP scattered within the surface of the light controlling sheet 11N are visible as if they are floating above the light controlling sheet 11N, so there is a bumpy appearance within the surface of the light controlling sheet 11N.

[0101] [Evaluation Results] The evaluation results for the light-adjusting sheet 11N of each test example are shown in Figures 5 and 6. The total light transmittance of the light-adjusting sheet 11N was found to be 6.6% in Test Example 1, 6.9% in Test Example 2, 6.7% in Test Example 3, 7.3% in Test Example 4, and 14.1% in Test Example 5. The total light transmittance of the light-adjusting sheet 11N was found to be 7.0% in Test Example 6, 7.5% in Test Example 7, and 5.1% in Test Example 8.

[0102] The total light transmittance of the spacer SP was found to be 21.0% in Test Examples 1, 2 and 6, 27.0% in Test Examples 3, 4 and 7, and 86.0% in Test Examples 5 and 8.

[0103] The area occupancy rate of the spacer SP was found to be 1% in Test Examples 1, 3, 5, and 8, 3% in Examples 2 and 4, and 4% in Test Examples 6 and 7. That is, the area occupancy rate of the spacer SP was found to be 0.01 in Test Examples 1, 3, 5, and 8, 0.03 in Examples 2 and 4, and 0.04 in Test Examples 6 and 7.

[0104] Second brightness L of light controlling sheet 11N ＊ The second lightness L2 of the light-modulating sheet 11N was found to be 0.1719 in Test Example 1, 0.1750 in Test Example 2, 0.1729 in Test Example 3, 0.1794 in Test Example 4, and 15.4247 in Test Example 5. ＊ 2 was found to be 0.1761 in Test Example 6, 0.1817 in Test Example 7, and 0.1582 in Test Example 8.

[0105] First brightness L of spacer SP ＊ It was found that the RI was 21.0 in Test Examples 1, 2 and 6, 27.0 in Test Examples 3, 4 and 7, and 88.9 in Test Examples 5 and 8.

[0106] 1st lightness L ＊ 1 to 2nd brightness L ＊ The brightness difference ΔL obtained by subtracting 2 ＊ It was found that the lightness difference ΔL was 20.828 in Test Example 1, 20.825 in Test Example 2, 26.827 in Test Example 3, 26.821 in Test Example 4, and 73.475 in Test Example 5. ＊ was found to be 20.824 in Test Example 6, 26.818 in Test Example 7, and 88.742 in Test Example 8.

[0107] Brightness difference ΔL ＊ The lightness difference ΔL was found to be 20.828 in Test Example 1, 62.475 in Test Example 2, 26.827 in Test Example 3, 80.462 in Test Example 4, and 73.475 in Test Example 5. ＊ The product of the surface area ratio SR and the surface area ratio SR was found to be 83.296 in Test Example 6, 107.273 in Test Example 7, and 88.742 in Test Example 8.

[0108] The area occupancy SR of the spacer SP and the first lightness L ＊The multiplication value by 1 was found to be 0.21 in Test Example 1, 0.63 in Test Example 2, 0.27 in Test Example 3, and 0.81 in Test Example 4. ＊ The multiplication value by 1 was found to be 0.889 in Test Example 5, 0.84 in Test Example 6, 1.08 in Test Example 7, and 0.889 in Test Example 8.

[0109] 2nd lightness L ＊ 2, the area occupancy rate SR and the first lightness L ＊ The value obtained by subtracting the multiplied value by 1 was found to be 0.0381 in Test Example 1, 0.455 in Test Example 2, 0.0971 in Test Example 3, and 0.6306 in Test Example 4. ＊ 2, the area occupancy rate SR and the first lightness L ＊ The value obtained by subtracting the multiplied value by 1 was found to be 14.5357 in Test Example 5, 0.6639 in Test Example 6, 0.8983 in Test Example 7, and 0.708 in Test Example 8.

[0110] The results of the visual evaluation of unevenness were "A" in Test Examples 1 to 5, and "B" in Test Examples 6 to 8. The results of the visual evaluation of lumpy texture were "A" in Test Examples 1 to 4, and "B" in Test Examples 5 to 8.

[0111] In this way, in the light controlling sheet 11N, the brightness difference ΔL ＊ It was found that when the multiplication value of the surface area occupancy rate SR is 20 or more and 81 or less, the unevenness of the appearance within the surface of the light controlling sheet 11N can be suppressed.

[0112] In addition, in the spacer SP, the area occupancy SR and the first brightness L ＊ It was found that by setting the multiplication value by 1 to 0.81 or less, the uneven appearance within the surface of the light controlling sheet 11N was suppressed.

[0113] As described above, according to one embodiment of the light controlling sheet, the following effects can be obtained: (1) Lightness difference ΔL ＊ and the area occupancy rate SR satisfies condition 1-1, so that unevenness in the appearance within the surface of the light controlling sheets 11N, 11R is less noticeable. In other words, it is possible to suppress unevenness in the appearance within the surface of the light controlling sheets 11N, 11R.

[0114] (2) First lightness L of spacer SP ＊ Since the product of 1 and the area occupancy rate SR satisfies condition 2-1, the mottled appearance of the light controlling sheets 11N and 11R within the plane is less noticeable. In other words, it is possible to suppress the mottled appearance of the light controlling sheets 11N and 11R within the plane.

[0115] (3) When the light-adjusting sheets 11N, 11R satisfy condition 2-2, when the light-adjusting sheets 11N, 11R are opaque, the difference in brightness between the light-adjusting sheets 11N, 11R and the spacer SP is reduced, and the appearance is less lumpy.

[0116] (4) When the outer surface of the spacer SP is black, light transmission through the outer surface of the spacer SP is suppressed, and the transmitted light is prevented from being locally visible within the plane of the light controlling sheets 11N, 11R. This further reduces poor appearance within the plane of the light controlling sheets 11N, 11R.

[0117] (5) When the center of the spacer SP is black in addition to the outer surface of the spacer SP, the absorbance of the spacer SP is further increased. This further reduces light transmission through the spacer SP, making the spacer SP less visible. As a result, poor appearance within the surface of the light controlling sheets 11N and 11R is further reduced.

[0118] (6) When the total light transmittance of the spacer SP is 30% or less, the transmission of light through the spacer SP is suppressed, thereby suppressing the visibility of transmitted light locally within the surface of the light-controlling sheets 11N and 11R.

Claims

1. A light-controlling sheet comprising a first transparent electrode sheet, a second transparent electrode sheet, and a light-controlling layer located between the first transparent electrode sheet and the second transparent electrode sheet, which can be reversibly switched between a transparent state and an opaque state depending on whether or not a voltage is applied to the light-controlling sheet, wherein the light-controlling layer comprises a transparent polymer layer including a plurality of voids, a liquid crystal composition located in the voids, and a spacer, wherein the liquid crystal composition comprises a liquid crystal compound and a dichroic dye, and wherein the first brightness of the spacer is L ＊ 1, and the second lightness of the light-controlling sheet exhibiting the opaque state is L ＊ 2, and the second lightness L ＊ 2 to the first brightness L ＊ The absolute value of the brightness difference obtained by subtracting 1 is ΔL ＊ In a plan view opposite to the plane on which the light-controlling sheet extends, the area occupancy (%) of the spacers in the light-controlling layer is SR, and the brightness difference ΔL ＊ and the area occupancy SR satisfy the following: 20≦ΔL ＊ ×SR≦81 Light-adjusting sheet.

2. The light-controlling sheet according to claim 1, wherein the brightness difference ΔL* is 20 or more and 74 or less, and the surface area occupancy rate SR is 1% or more and 3% or less.

3. A light-controlling sheet comprising a first transparent electrode sheet, a second transparent electrode sheet, and a light-controlling layer located between the first transparent electrode sheet and the second transparent electrode sheet, wherein the light-controlling layer comprises a transparent polymer layer including a plurality of voids, a liquid crystal composition located in the voids, and a spacer, wherein the liquid crystal composition comprises a liquid crystal compound and a dichroic dye, and the first brightness of the spacer is L ＊ 1, in a plan view opposite to the plane on which the light-controlling sheet spreads, the area occupancy rate of the spacers in the light-controlling layer is SR, and the first brightness L ＊ The multiplication value of 1 and the area occupancy rate SR satisfies the following: 0.2≦L ＊ 1 x SR ≦ 0.83 Light control sheet.

4. The light-controlling sheet is reversibly switched between transparency and opacity depending on whether or not a voltage is applied to the light-controlling sheet, and the second brightness of the opaque light-controlling sheet is L ＊ 2, and the second lightness L ＊ The absolute value obtained by subtracting the multiplied value from 2 satisfies the following: 0≦|L ＊ 2-L ＊ The light-controlling sheet according to claim 3, wherein 1×SR|≦0.

66.

5. The first lightness L ＊ The light-controlling sheet according to claim 3 , wherein SR is 21 or more and 27 or less, and the surface area ratio SR is 0.01 or more and 0.03 or less.

6. The light-controlling sheet according to any one of claims 1 to 5, wherein the outer surface of the spacer is black.

7. The light-controlling sheet according to claim 6, wherein the spacer has the outer surface and a center portion covered by the outer surface, and the center portion is black.

8. The light-controlling sheet according to any one of claims 1 to 5, wherein the spacer has a total light transmittance of 30% or less.

9. The light-controlling sheet according to any one of claims 1 to 5, wherein the average diameter of the spacers is 5 μm or more and 30 μm or less.

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