Dimming sheet and dimming device

Abstract

To improve the light resistance of a dimming sheet with improved design.SOLUTION: A dimming sheet 11 comprises: a layered product 13 having a dimming layer 31 containing a liquid crystal compound and a dichroic dye; and a first protective layer 38 and a second protective layer 39 that are provided in the layered product 13 and that absorb light in an absorption wavelength range including the ultraviolet region. The layered product 13 has, in a non-transparent state, a chromaticity a* of -15 to 15 and a chromaticity b* of -16 to 15 in the CIE1976 (L*a*b*) color system complying with JIS-Z-8781-4. The smallest values of the absorption wavelength ranges of the first protective layer 38 and the second protective layer 39 are at most 360 nm. The upper limits of the absorption wavelength ranges are in the range of 410-430 nm in the visible region. The protective layer has a chromaticity a* of -10 to 0 and a chromaticity b* of 0 to 15 in the CIE1976 (L*a*b*) color system complying with JIS-Z-8781-4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a dimming sheet and a dimming device.

Background Art

[0002] The dimming sheet includes a first transparent electrode layer, a second transparent electrode layer, and a dimming layer sandwiched between the first transparent electrode layer and the second transparent electrode layer. The alignment state of the liquid crystal compound contained in the dimming layer follows the change in the potential difference between the two transparent electrode layers, changing the light transmittance of the dimming sheet. For example, when the alignment order of the liquid crystal compound is established, the dimming sheet exhibits a high light transmittance. When the long axis direction of the liquid crystal compound is disordered, the dimming sheet exhibits a low light transmittance.

[0003] Generally, the dimming sheet is colorless and transparent in the transparent state showing a high light transmittance, and in the opaque state showing a low light transmittance, when visible light scatters inside the dimming sheet, it appears cloudy to the naked eye. Depending on the use environment, a colored dimming sheet may be preferred as having higher design quality than a cloudy dimming sheet. For this reason, it has been proposed to add a dichroic dye to the liquid crystal composition (see, for example, Patent Document 1). The dichroic dye has anisotropy in absorbance and exhibits a high absorbance when its long axis direction is disordered. At this time, the dimming sheet in the opaque state is not in a cloudy state, but exhibits a state in which the color derived from the dichroic dye is expressed and the light transmittance is low.

[0004] Since the dichroic dye undergoes a decomposition reaction by ultraviolet rays, there has been a problem of fading due to long-term use. The liquid crystal element described in the above document includes a liquid crystal composition containing an ultraviolet absorber capable of absorbing ultraviolet rays in the range of 290 nm to 400 nm.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] However, dichroic dyes may fade even with visible light. For this reason, there has been a demand for further improving the lightfastness of the light control sheet. [[Means for Solving the Problems]]

[0007] The light control sheet for solving the above problems includes a light control layer containing a liquid crystal compound and a dichroic dye, a pair of transparent electrode layers sandwiching the light control layer, and a pair of transparent support layers sandwiching the light control layer and the pair of transparent electrode layers. The light control sheet controls the alignment of the liquid crystal compound and the dichroic dye according to the potential difference between the pair of transparent electrode layers, and controls to a transparent state and a colored opaque state. The light control sheet further includes a protective layer provided on a surface of at least one of the transparent support layers facing the surface in contact with the transparent electrode layer, the protective layer absorbing light in an absorption wavelength range including the ultraviolet region. In the opaque state, the laminate has a chromaticity a in the CIE1976 (L * a * b * ) color system of -15 or more and 15 or less and a chromaticity b * of -16 or more and 15 or less. The absorption wavelength range of the protective layer has a lower limit value of 360 nm or less and an upper limit value of the absorption wavelength range of 410 nm or more and 430 * nm or less within the visible region. The chromaticity a of the protective layer in the CIE1976 (L nm a * a * b * ) color system is -10 or more and 0 or less, and the chromaticity b * is 0 or more and 15 or less. *

[0008] ​The light control device that solves the above problem includes a laminate having a light control layer containing a liquid crystal compound and a dichroic dye, a pair of transparent electrode layers sandwiching the light control layer, and a pair of transparent support layers sandwiching the light control layer and the pair of transparent electrode layers, and a drive unit that generates a potential difference between the pair of transparent electrode layers to control the orientation of the liquid crystal compound and the dichroic dye and control the laminate between a transparent state and an opaque state, and further includes a protective layer that is provided on a surface of at least one of the transparent support layers opposite to a surface in contact with the transparent electrode layer and absorbs light in an absorption wavelength range including an ultraviolet region, and the laminate in the opaque state has a CIE1976(L) conforming to JIS-Z-8781-4. * a * b * ) Chromaticity in the color system a * is between -15 and 15 and chromaticity b * The absorption wavelength range of the protective layer has a lower limit of 360 nm or less and an upper limit of 410 nm to 430 nm in the visible region. nm The range of the protective layer is as follows: CIE1976(L) conforming to JIS-Z-8781-4 * a * b * ) Chromaticity in the color system a * is between -10 and 0 and chromaticity b * is between 0 and 15 inclusive.

[0009] The laminate having the dichroic dye-containing light-control layer 31 is compliant with CIE1976(L * a * b * ) Chromaticity in the color system a * is -15 or more and 15 or less, chromaticity b *is -16 or more and 15 or less, and exhibits a black color or a color close to black. Further, since the dimming sheet includes the first protective layer and the second protective layer that absorb light in the absorption wavelength range including the ultraviolet region, it is possible to suppress the fading of the dichroic dye having lower light resistance than a liquid crystal compound or the like. By setting the upper limit value of the absorption wavelength range of the first protective layer and the second protective layer to 410 nm or more and 430 nm or less, while enhancing the fading suppression effect of the dichroic dye, the first protective layer and the second protective layer themselves have a yellowish tint. On the other hand, for the CIE1976 (L * a * b * ) color system, the chromaticity a * is set to -10 or more and 0 or less, and the chromaticity b * is set to 0 or more and 15 or less, so that the first protective layer and the second protective layer themselves are black or a color close to black, and the yellow color can be canceled. Further, since the first protective layer and the second protective layer that also exhibit a black color or a color close to black are laminated on the black-colored laminate, it is possible to prevent the color tone of the laminate from changing significantly.

[0010] Regarding the above dimming sheet, it is preferable that the total light transmittance of the protective layer is 70% or more. According to the above configuration, the dimming sheet can enhance the transparency in the transparent state while exhibiting a black color or a color close to black in the opaque state.

[0011] Regarding the above dimming sheet, it is preferable that the total light transmittance in the opaque state is 30% or less. According to the above configuration, it is possible to protect the privacy of the target space partitioned by the dimming sheet in the opaque state.

[0012] Regarding the above dimming sheet, it is preferable to further include a spacer in which the dichroic dye exhibits the same color as the color exhibited in the opaque state. Since the spacer exhibits the same color as the color exhibited by the laminate in the opaque state, the spacer can have a non-conspicuous appearance.

Effects of the Invention

[0013] According to the present invention, the light resistance of a dimming sheet containing a dichroic dye can be improved.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0015] One embodiment of a dimming sheet and a dimming device will be described. The dimming sheet is attached to a transparent base material which is an object to be attached. The transparent base material is a glass substrate or a resin substrate. An example of the transparent base material is window glass mounted on a moving body such as a vehicle or an aircraft, window glass installed in a building, or a partition arranged inside a vehicle or a room. The surface to which the dimming sheet is attached is planar or curved. The dimming sheet may be sandwiched between two transparent base materials.

[0016] The drive type of the dimming sheet is a normal type or a reverse type. The normal type dimming sheet transitions from an opaque state to a transparent state by applying a voltage, and returns from the transparent state to the opaque state by releasing the applied voltage. The reverse type dimming sheet transitions from a transparent state to an opaque state by applying a voltage, and returns from the opaque state to the transparent state by releasing the applied voltage.

[0017] Note that the normal type and the reverse type are common in that they both include two transparent electrode layers and a light control layer. Hereinafter, after explaining the configuration and operation of the normal type, the normal type and the reverse type will be described.

[0018] [Structure of Light Control Device] With reference to FIG. 1, the schematic structure of the light control device 10 and the light control sheet 11 will be described. The light control device 10 includes a light control sheet 11 and a drive unit 12. The light control sheet 11 includes a light control layer 31, a first transparent electrode layer 34, a second transparent electrode layer 35, a first transparent support layer 36, a second transparent support layer 37, a first protective layer 38, and a second protective layer 39.

[0019] The light control layer 31 is located between the first transparent electrode layer 34 and the second transparent electrode layer 35. The first transparent electrode layer 34 is connected to the drive unit 12 through a first connection terminal 22A and a first wiring 23A. The first transparent electrode layer 34 is located between the first transparent support layer 36 and the light control layer 31 and is in contact with the first transparent support layer 36 and the light control layer 31. The light control layer 31 has a structure such as polymer dispersed liquid crystal (PDLC), polymer network liquid crystal (PNLC), or capsule-type nematic liquid crystal (NCAP). The light control layer 31 including polymer dispersed liquid crystal has a resin layer provided with a large number of independent voids or voids having a shape in which a part of an independent shape is joined, and holds a liquid crystal composition in the voids. The polymer network liquid crystal includes a three-dimensional network-shaped polymer network, and holds liquid crystal molecules as alignment particles in the voids of the polymer network. The capsule-type nematic liquid crystal layer holds a capsule-shaped liquid crystal composition in a resin layer. The light control layer 31 of the present embodiment includes polymer dispersed liquid crystal. Note that the light control layer 31 does not necessarily need to be clearly distinguished.

[0020] The second transparent electrode layer 35 is positioned between the second transparent support layer 37 and the light control layer 31, and is in contact with the second transparent support layer 37 and the light control layer 31. The light control layer 31, the first transparent electrode layer 34, and the second transparent electrode layer 35, the first transparent support layer 36, and the second transparent support layer 37 constitute the laminate 13.

[0021] The first protective layer 38 and the second protective layer 39 are laminated on the laminate 13. The first protective layer 38 is provided on the surface 36F of the first transparent support layer 36 that faces the surface in contact with the first transparent electrode layer 34. The first protective layer 38 is in contact with the entire area or substantially the entire area of the surface 36F. The second protective layer 39 is in contact with the entire area or substantially the entire area of the surface 37F of the first transparent support layer 36 that faces the surface in contact with the second transparent electrode layer 35. Note that an adhesive layer may be interposed between the first protective layer 38 and the first transparent support layer 36, and between the second protective layer 39 and the second transparent support layer 37.

[0022] Next, the elements constituting the light control sheet 11 will be described in detail with reference to FIG. 2. FIG. 2 shows a part of the light control sheet 11 and shows the PDLC-type light control layer 31, the first transparent electrode layer 34, and the second transparent electrode layer 35.

[0023] (Light control layer) The light control layer 31 includes an organic polymer layer 31P, a liquid crystal composition 31LC, and spacers SP. The organic polymer layer 31P is a cured product of a photopolymerizable compound. The photopolymerizable compound may be an ultraviolet-curable compound or an electron beam-curable compound. The photopolymerizable compound has compatibility with the liquid crystal composition 31LC.

[0024] The organic polymer layer 31P partitions voids 31D within the light control layer 31. When it is necessary to enhance the controllability of the dimensions in the voids 31D, the photopolymerizable compound is preferably an ultraviolet curable compound. An example of the ultraviolet curable compound contains a polymerizable unsaturated bond at the terminal of the molecular structure. Alternatively, the ultraviolet curable compound contains a polymerizable unsaturated bond other than at the terminal of the molecular structure. The photopolymerizable compound is one type of polymerizable compound or a combination of two or more types of polymerizable compounds. The ultraviolet curable compound is at least one selected from the group consisting of acrylate compounds, methacrylate compounds, styrene compounds, thiol compounds, and oligomers of each compound. The acrylate compounds include diacrylate compounds, triacrylate compounds, and tetraacrylate compounds. An example of the acrylate compound is butyl ethyl acrylate, ethylhexyl acrylate, cyclohexyl acrylate. An example of the methacrylate compound is a dimethacrylate compound, trimethacrylate compound, tetramethacrylate compound. An example of the methacrylate compound is N,N-dimethylaminoethyl methacrylate, phenoxyethyl methacrylate, methoxyethyl methacrylate, tetrahydrofurfuryl methacrylate. An example of the thiol compound is 1,3-propanedithiol, 1,6-hexanedithiol. An example of the styrene compound is styrene, methylstyrene.

[0025] The lower limit of the content of the organic polymer layer 31P with respect to the total amount of the organic polymer layer 31P and the liquid crystal composition 31LC is 20% by mass, and a more preferable lower limit of the content is 30% by mass. The upper limit of the content of the organic polymer layer 31P with respect to the total amount of the organic polymer layer 31P and the liquid crystal composition 31LC is 70% by mass, and a more preferable upper limit of the content is 60% by mass.

[0026] The lower limit value and the upper limit value of the content of the organic polymer layer 31P are determined according to the range in which the liquid crystal particles composed of the liquid crystal composition 31LC can be phase-separated from the cured product of the photopolymerizable compound during the curing process of the photopolymerizable compound. When it is necessary to increase the mechanical strength of the organic polymer layer 31P, it is preferable that the lower limit value of the content of the organic polymer layer 31P is high. When it is necessary to lower the driving voltage of the liquid crystal compound LCM, it is preferable that the upper limit value of the content of the organic polymer layer 31P is low.

[0027] The liquid crystal composition 31LC contains a liquid crystal compound LCM and a dichroic dye DP. In addition, the liquid crystal composition 31LC may further contain a viscosity reducing agent, an antifoaming agent, an antioxidant, a weathering agent, and a solvent. An example of the weathering agent is an ultraviolet absorber or a light stabilizer.

[0028] The holding type of the liquid crystal composition 31LC by the organic polymer layer 31P is any one of the group consisting of a polymer dispersed type, a polymer network type, and a capsule type. Or, the holding type of the liquid crystal composition 31LC by the organic polymer layer 31P may be a type combining a plurality of types among these groups.

[0029] The organic polymer layer 31P of the polymer dispersed type light control layer 31 demarcates a large number of isolated voids 31D. The organic polymer layer 31P of the polymer network type light control layer 31 has a three-dimensional network-like void 31D. The liquid crystal composition 31LC is located in the mutually communicating network-like void 31D. The organic polymer layer 31P of the capsule type light control layer 31 has dispersed capsule-like voids 31D. There are two or more types of the sizes of the voids 31D, and the shapes of the voids 31D are spherical, ellipsoidal, or irregular.

[0030] The dielectric constant in the major axis direction of the liquid crystal compound LCM has positive dielectric anisotropy, which is larger than the dielectric constant in the minor axis direction of the liquid crystal compound LCM. Or, the dielectric constant in the major axis direction of the liquid crystal compound LCM has negative dielectric anisotropy, which is lower than the dielectric constant in the minor axis direction of the liquid crystal compound LCM. The dielectric anisotropy of the liquid crystal compound LCM is appropriately selected based on the presence or absence of each alignment layer in the light control sheet 11 and the driving type.

[0031] The liquid crystal compound LCM is at least one selected from the group consisting of Schiff base type, azo type, azoxy type, biphenyl type, terphenyl type, benzoic acid ester type, trans type, pyrimidine type, pyridazine type, cyclohexanecarboxylic acid ester type, phenylcyclohexane type, biphenylcyclohexane type, dicyanobenzene type, naphthalene type, and dioxane type. The non-polymerizable liquid crystal compound is one kind of liquid crystal compound or a combination of two or more kinds of liquid crystal compounds.

[0032] The dichroic dye DP has an elongated molecular shape, and the absorbance in the visible region in the molecular long axis direction is larger than the absorbance in the molecular short axis direction. The dichroic dye DP in the present embodiment exhibits a black or nearly black color in a state where the molecular long axis direction intersects the light incident direction at a predetermined angle. That is, the dichroic dye DP exhibits a black or nearly black color when it is oriented such that the molecular long axis direction is substantially orthogonal to the normal directions of the contact surfaces with the first transparent electrode layer 34 and the second transparent electrode layer 35 of the light control layer 31. The dichroic dye DP is driven and colored by a guest-host type using the liquid crystal compound LCM as a host.

[0033] In addition, for the dichroic dye DP, the chromaticity a in the CIE1976 (L * a * b * ) color system is -15 or more and 15 or less, and the chromaticity b * is -16 or more and 15 or less. A dye that satisfies this condition is used. The chromaticity a * and chromaticity b * a * b * ) in the CIE1976 (L * colorimetric system, and chromaticity b * are specified in accordance with the method for calculating the color coordinates of the CIE1976 (L * a * b * ) color space defined in JIS-Z-8781-4 (ISO 11664-4).

[0034] The dichroic pigment DP is 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 pigment DP is one kind of pigment or a combination of two or more kinds of pigments. When it is necessary to enhance light resistance and increase the dichroic ratio, the dichroic pigment is at least one selected from the group consisting of azo compounds and anthraquinone compounds, and more preferably an azo compound.

[0035] The content of the dichroic pigment DP is 10% by weight or less based on the total solid content of the light control layer 31. Further, when the content of the dichroic pigment DP is 5% by weight or less, a light control sheet 11 with excellent aesthetics can be obtained.

[0036] The spacer SP is dispersed throughout the entire organic polymer layer 31P. The spacer SP determines the thickness of the light control layer 31 around the spacer SP and equalizes the thickness of the light control layer 31. The spacer SP may be a bead spacer or a photo spacer formed by exposure and development of a photoresist. The spacer SP has light transmittance and may be colorless and transparent or colored and transparent. The color exhibited by the colored and transparent spacer SP is preferably the same as the color exhibited by the dichroic pigment DP.

[0037] (Transparent electrode layer) The first transparent electrode layer 34 and the second transparent electrode layer 35 are each colorless and transparent. The materials constituting the first transparent electrode layer 34 and the second transparent electrode layer 35 are each a conductive inorganic oxide, a metal, or a conductive organic polymer compound. An example of the conductive inorganic oxide is any one selected from the group consisting of indium tin oxide, fluorine-doped tin oxide, tin oxide, and zinc oxide. The metal is a nanowire of gold or silver. An example of the conductive organic polymer compound is any one selected from the group consisting of carbon nanotubes and poly(3,4-ethylenedioxythiophene).

[0038] (Transparent support layer) The materials constituting the first transparent support layer 36 and the second transparent support layer 37 are each an organic polymer compound or an inorganic polymer compound. An example of the organic polymer compound is any one selected from the group consisting of polyester, polyacrylate, polycarbonate, and polyolefin. An example of the inorganic polymer compound is any one selected from the group consisting of silicon oxide, silicon oxynitride, and silicon nitride. The first transparent support layer 36 and the second transparent support layer 37 are each preferably colorless and transparent.

[0039] (Protective layer) The first protective layer 38 and the second protective layer 39 are colored and transparent. The first protective layer 38 and the second protective layer 39 suppress light with a specific wavelength including the ultraviolet region from entering the light control layer 31, and suppress the fading of the dichroic dye DP contained in the light control layer 31.

[0040] The absorption wavelength regions of the first protective layer 38 and the second protective layer 39 include a part of the ultraviolet region and a part of the visible light region of 400 nm or more. The first protective layer 38 and the second protective layer 39 have a maximum absorbance value within a wavelength range of 360 nm or more and 430 nm or less. Further, the absorption wavelength regions of the first protective layer 38 and the second protective layer 39 have a lower limit value of 360 nm or less and an upper limit value of 410 nm or more and 430 nm within the following range in the visible region. The first protective layer 38 and the second protective layer 39 include an organic polymer compound or an inorganic compound and a light absorber. The light absorber preferably has transparency. As the light absorber, a cyanoacrylate-based, triazine-based, benzophenone-based, benzotriazole-based, or triazine-based light absorber can be used. As the first protective layer 38 and the second protective layer 39, a known short-wavelength cut filter (long-pass filter) can be used.

[0041] The first protective layer 38 and the second protective layer 39 may have a single-layer structure, or may have a multilayer structure in which a plurality of layers of a layer made of an organic polymer compound and a layer made of an inorganic compound are stacked.

[0042] The thicknesses of the first protective layer 38 and the second protective layer 39 are preferably 10 μm or more and 2.5 mm or less. When the first protective layer 38 and the second protective layer 39 have a multilayer structure and include a light absorption layer between support layers that are not light absorption materials, the thickness of this light absorption layer is 23 mm or less.

[0043] In addition, the first protective layer 38 and the second protective layer 39 may be colored by mixing a dye into a base material such as an organic polymer compound or an inorganic compound, or may be colored by printing a colored ink on a transparent substrate.

[0044] As long as the light control sheet 11 is configured to switch between a transparent state and an opaque state based on a change in the alignment state of the liquid crystal compound LCM, the light control sheet 11 may include one or more other functional layers. The other functional layer may be a gas barrier layer that suppresses the permeation of oxygen and moisture toward the light control layer 31, or may be an ultraviolet barrier layer that suppresses the permeation of ultraviolet light other than a specific wavelength toward the light control layer 31. The other functional layer may be a hard coat layer that mechanically protects each layer of the light control sheet 11, or may be an adhesive layer that enhances the adhesion between layers in the light control sheet 11.

[0045] The drive unit 12 is connected to the first transparent electrode layer 34 and the second transparent electrode layer 35. The drive unit 12 applies a drive voltage to the first transparent electrode layer 34 and the second transparent electrode layer 35 to control the alignment of the liquid crystal compound LCM and the dichroic dye DP according to the potential difference between the first transparent electrode layer 34 and the second transparent electrode layer 35. The drive voltage is a voltage for changing the alignment state of the liquid crystal compound LCM and the dichroic dye DP. The drive unit 12 changes the alignment state of the liquid crystal compound LCM and the dichroic dye DP to switch the light control sheet 11 from one of a transparent state and an opaque state to the other. In the opaque state, the light control sheet 11 exhibits a black color or a color close to black, and the total light transmittance is lower than that in the transparent state. In other words, the light control sheet 11 in the opaque state has a haze value that is higher than that in the transparent state.

[0046] When the application of the driving voltage is released, the long axis directions of the liquid crystal compound LCM and the dichroic dye DP become disordered. As a result, the dimming sheet 11 causes scattering in the dimming layer 31 over the entire visible light range and becomes opaque. Also, the long axis direction of the dichroic dye DP becomes disordered. Among the dichroic dyes DP, those in which at least the angle formed by the normal direction of the contact surface between the long axis direction and the first transparent electrode layer 34 of the dimming layer 31 and the contact surface with the second transparent electrode layer 35 of the dimming layer 31 is a predetermined angle such as an angle close to 90° exhibit black. Note that the normal direction is equivalent to the thickness direction of the dimming layer 31.

[0047] When a driving voltage is applied, the liquid crystal compound LCM receives an orientation regulating force by the electric field, and the long axis directions of the liquid crystal compound LCM and the dichroic dye DP become an orientation state along the electric field direction. As a result, the total light transmittance of the dimming sheet 11 becomes higher than in the opaque state. Also, since the long axis direction of the dichroic dye DP also becomes an orientation state along the electric field direction, the color of the dimming sheet 11 becomes colorless or nearly colorless.

[0048] When the application of the driving voltage is released again, the liquid crystal compound LCM and the dichroic dye DP are released from the orientation regulating force by the electric field, and the long axis directions of the liquid crystal compound LCM and the dichroic dye DP become disordered. As a result, the dimming sheet 11 causes scattering in the dimming layer 31 over the entire visible light range and becomes opaque again.

[0049] Next, the reverse type dimming sheet 11 will be described with reference to FIG. 3. FIG. 3 shows the reverse type dimming sheet 11. The reverse type dimming sheet 11 includes a first alignment layer 32 and a second alignment layer 33. A dimming layer 31 is provided between the first alignment layer 32 and the second alignment layer 33. The first alignment layer 32 and the second alignment layer 33 sandwiching the dimming layer 31 are located between the first transparent support layer 36 and the second transparent support layer 37.

[0050] When the application of the driving voltage to the first transparent electrode layer 34 and the second transparent electrode layer 35 is released, the liquid crystal compound LCM receives an alignment regulating force from the first alignment layer 32 and the second alignment layer 33, and the major axis direction of the liquid crystal compound LCM is along the thickness direction of the light control layer 31. As a result, the light control sheet 11 suppresses scattering in the light control layer 31 over the entire visible light range and becomes transparent.

[0051] When the application of the driving voltage starts, the liquid crystal compound LCM receives an alignment regulating force by the electric field, and the major axis direction of the liquid crystal compound LCM starts to move in a direction orthogonal to the electric field direction. At this time, the major axis direction of the liquid crystal compound LCM is restricted by the intermolecular interaction in the liquid crystal composition 31LC and the size of the void 31D, and cannot move sufficiently and becomes disordered. As a result, the light control sheet 11 generates scattering in the light control layer 31 over the entire visible light range and becomes opaque.

[0052] When the application of the driving voltage is released again, the liquid crystal compound LCM is released from the alignment regulating force by the electric field, and in accordance with the alignment regulating force by the first alignment layer 32 and the second alignment layer 33, the major axis direction of the liquid crystal compound LCM is aligned along the thickness direction of the light control layer 31. As a result, the light control sheet 11 suppresses scattering in the light control layer 31 over the entire visible light range and becomes transparent again.

[0053] [Optical characteristics of the light control sheet] Next, the optical characteristics of the light control sheet 11 will be described. The first protective layer 38 and the second protective layer 39 satisfy the following conditions 1 and 2.

[0054] ·(Condition 1) The absorption wavelength range has a lower limit value of 360 nm or less and an upper limit of the absorption wavelength range within the visible region of 410 nm or more and 430 nm The following range. ·(Condition 2) CIE1976 (L * a * b * ) In the colorimetric system, the chromaticity a * Is -10 or more and 0 or less, and the chromaticity b * Is 0 or more and 15 or less.

[0055] Furthermore, it is preferable that the first protective layer 38 and the second protective layer 39 satisfy the following condition 3. ·(Condition 3) The total light transmittance is 70% or more.

[0056] Also, as described above, the laminate 13 contains the dichroic dye DP and thus satisfies the following condition 4. ·(Condition 4) CIE1976 (L * a * b * ) In the color system, the chromaticity a * is -15 or more and 15 or less, and the chromaticity b * is -16 or more and 15 or less.

[0057] By constructing the light control sheet 11 using the laminate 13 that satisfies Conditions 1 to 4, the first protective layer 38, and the second protective layer 39, the light control sheet 11 satisfies the following characteristics 1 and 2. ·(Characteristic 1) The total light transmittance of the light control sheet 11 in the opaque state is 30% or less.

[0058] ·(Characteristic 2) CIE1976 (L * a * b * ) In the color system, the chromaticity a * is -10 or more and 10 or less, and the chromaticity b * is -10 or more and 10 or less. The above Conditions 1 and 2 will be described with reference to FIG. 4. FIG. 4 schematically shows an example of the absorption wavelength range R of the first protective layer 38 and the second protective layer 39. The absorption wavelength range R has a lower limit value R1 of 360 nm or less and an upper limit value R2 of 410 nm or more and 430 within the visible region nmThe following is an example of the range to be set. By setting the lower limit value R1 to 360 nm or less, it becomes possible to absorb light having a wavelength in the long-wavelength ultraviolet region. Since the dichroic dye DP is gradually decomposed by irradiation with ultraviolet light, the first protective layer 38 and the second protective layer 39 can suppress the fading of the dichroic dye DP by absorbing a part of the ultraviolet light. In addition, since light having a relatively short wavelength among visible light may also decompose the dichroic dye DP, by setting the upper limit value R2 to 410 nm or more and 430 nm nm or less, the effect of suppressing the fading of the dichroic dye DP can be further enhanced.

[0059] In FIG. 4, when the upper limit value is around 400 nm between the ultraviolet region and the visible light region as in the absorption spectrum R3 shown by the broken line, since there is little visible light that can be absorbed, the effect of suppressing the fading of the dichroic dye DP cannot be enhanced. Further, in FIG. 4, when the upper limit value exceeds 430 nm as in the absorption spectrum R4 shown by the broken line, while the effect of suppressing the fading of the dichroic dye DP becomes high, the transparency of the light control sheet 11 in the transparent state decreases.

[0060] The absorption spectra of the first protective layer 38 and the second protective layer 39 may be one continuous spectrum or may be composed of a plurality of continuous spectra. When composed of a plurality of continuous spectra, it is preferable that the ends of the absorption spectra overlap within the absorption wavelength range R. Thereby, since the first protective layer 38 and the second protective layer 39 can absorb light in the entire region within the absorption wavelength range R, fading can be suppressed.

[0061] However, when the upper limit value R2 of the absorption wavelength range R is 410 nm or more and 430 nm or less, since the first protective layer 38 and the second protective layer 39 absorb light in the short-wavelength violet to blue range in the visible region, when observed with the naked eye, the colors of the first protective layer 38 and the second protective layer 39 appear to have a yellowish tint. When the first protective layer 38 and the second protective layer 39 have a yellowish tint, the light control sheet 11 does not exhibit excellent black for aesthetics. Therefore, in order to cancel out the yellowish tint, the first protective layer 38 and the second protective layer 39 themselves are adjusted to the CIE1976 (L * a* b * ) Chromaticity a in the color system * is -10 or more and 0 or less, and chromaticity b * is a color that is 0 or more and 15 or less.

[0062] Next, condition 3 will be described. The first protective layer 38 and the second protective layer 39 preferably have a total light transmittance of 70% or more. The total light transmittance is a value obtained by using the method for measuring the total light transmittance using light source D65 in accordance with JIS K 7361-1:1997 (ISO 1468-1). When the total light transmittance is 70% or more, even if the first protective layer 38 and the second protective layer 39 are colored, high transparency can be maintained when the dimming sheet 11 is driven to the transparent state. Note that since the first protective layer 38 and the second protective layer 39 are colored, the total light transmittance becomes 95% or less.

[0063] Condition 4 is that the chromaticity of the laminate 13 can be adjusted by appropriately selecting one or more black dichroic dyes DP. Next, condition 5 will be described. The dimming sheet 11 has a total light transmittance of visible light in the opaque state of 30% or less. The total light transmittance is a value obtained by using the method for measuring the total light transmittance using light source D65 in accordance with JIS K 7361-1:1997 (ISO 1468-1). When the total light transmittance in the opaque state is 30% or less, it is possible to obtain a haze that can exhibit a privacy protection effect in the opaque state.

[0064] [Manufacturing method of dimming sheet] The manufacturing method of the dimming sheet 11 will be described. First, a first transparent support layer 36 having a first transparent electrode layer 34 and a second transparent support layer 37 having a second transparent electrode layer 35 are prepared. Next, a coating film for forming the dimming layer 31 is formed between the first transparent support layer 36 and the second transparent support layer 37. Note that the manufacturing method of the reverse type dimming sheet 11 is to form a coating film between the first transparent support layer 36 having the first transparent electrode layer 34 and the second transparent support layer 37 having the second transparent electrode layer 35.

[0065] The coating film contains a photopolymerizable compound, a liquid crystal composition 31LC, a dichroic dye DP, and a polymerization initiator for initiating the polymerization of the photopolymerizable compound. The polymerization initiator is at least one selected from the group consisting of a diketone compound, an acetophenone compound, a benzoin compound, a benzophenone compound, and a thioxanthone compound. The polymerization initiator may be one kind of compound or a combination of two or more kinds 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, and cyclohexyl phenyl ketone.

[0066] The method for manufacturing the light control sheet 11 includes phase-separating liquid crystal particles composed of the liquid crystal composition 31LC from the photopolymerizable compound by polymerizing the photopolymerizable compound in the coating film. The light for polymerizing the photopolymerizable compound may be ultraviolet light or an electron beam. The light for polymerizing the photopolymerizable compound may be irradiated toward the first transparent support layer 36, may be irradiated toward the second transparent support layer 37, or may be irradiated toward both the first transparent support layer 36 and the second transparent support layer 37.

[0067] The phase separation of the liquid crystal particles composed of the liquid crystal composition 31LC proceeds through the polymerization of the photopolymerizable compound and the diffusion of the liquid crystal composition 31LC. The polymerization rate of the photopolymerizable compound varies depending on the intensity of the light irradiated to the photopolymerizable compound. The diffusion rate of the liquid crystal composition 31LC varies depending on the processing temperature during the polymerization of the photopolymerizable compound. In the phase separation of the liquid crystal composition 31LC, the intensity of the light irradiated to the photopolymerizable compound, the irradiation time, and the processing temperature during the polymerization of the photopolymerizable compound are set so that the size of the liquid crystal particles becomes a desired size and the number of the liquid crystal particles becomes a desired number. That is, in the phase separation of the liquid crystal composition 31LC, the intensity of the light irradiated to the photopolymerizable compound, the irradiation time, and the processing temperature during the polymerization of the photopolymerizable compound are set so that the size of the voids 31D becomes a desired size and the number of the voids 31D becomes a desired number. Thereby, the laminate 13 composed of the light control layer 31, the first transparent electrode layer 34, the second transparent electrode layer 35, the first transparent support layer 36, and the second transparent support layer 37 is formed.

[0068] Next, a first protective layer 38 is joined to a surface 36F on the side opposite to the surface of the first transparent support layer 36 that is in contact with the first transparent electrode layer 34. Also, a second protective layer 39 is joined to a surface 37F on the side opposite to the surface of the second transparent support layer 37 that is in contact with the second transparent electrode layer 35. The first protective layer 38 and the second protective layer 39 may be adhered to the first transparent support layer 36 and the second transparent support layer 37 respectively by an adhesive material, or may be joined by other methods such as welding.

[0069] According to the above embodiment, the following effects can be obtained. (1) The laminate 13 having the light control layer 31 containing the dichroic dye DP has a chromaticity a * a * b * in the CIE1976 (L * ) color system that is -15 or more and 15 or less, and a chromaticity b * that is -16 or more and 15 or less, and exhibits a black color or a color close to black in the opaque state. Further, since the light control sheet 11 has a configuration in which the first protective layer 38 and the second protective layer 39 that absorb light in the absorption wavelength range including the ultraviolet region are stacked on the laminate 13, fading of the dichroic dye DP, which has lower light resistance than a liquid crystal compound LCM or the like, can be suppressed. By setting the upper limit value R2 of the absorption wavelength range R of the first protective layer 38 and the second protective layer 39 to be 410 nm or more and 430 nm or less, while the effect of suppressing the fading of the dichroic dye DP is enhanced, the first protective layer 38 and the second protective layer 39 themselves have a yellowish tint. On the other hand, by setting the chromaticity a * a * b * in the CIE1976 (L * ) color system of the first protective layer 38 and the second protective layer 39 to be -10 or more and 0 or less, and the chromaticity b * to be 0 or more and 15 or less, it is possible to suppress the first protective layer 38 and the second protective layer 39 from exhibiting a yellow color. Also, since the first protective layer 38 and the second protective layer 39 are stacked on the laminate 13, it is possible to suppress a significant change in the color tone of the laminate 13 itself.

[0070] (2) The total light transmittance in the visible region of the first protective layer 38 and the second protective layer 39 is 70% or more. Therefore, the transparency of the light control sheet 11 in the transparent state can be enhanced.

[0071] (3) The spacer SP exhibits the same color as the color exhibited by the laminate 13 in the opaque state. Therefore, the light control sheet 11 can have an appearance in which the spacer SP is not conspicuous. (4) Since the total light transmittance of the light control sheet 11 in the opaque state is 30% or less, it is possible to protect the privacy of the target space partitioned by the light control sheet 11 in the opaque state.

[0072] [Examples] With reference to FIG. 5, examples and comparative examples of the light control sheet 11 are shown below. The examples and comparative examples are normal-type light control sheets 11 in which the first alignment layer 32 and the second alignment layer 33 are omitted. Note that these examples do not necessarily limit the present invention.

[0073] (Example 1) The constituent materials of the light control sheet 11 of Example 1 are shown below. First transparent electrode layer 34 and second transparent electrode layer 35: Indium tin oxide, thickness 30 nm First transparent support layer 36 and second transparent support layer 37: Polyethylene terephthalate film, thickness 125 μm Spacer SP: True spherical particles made of PMMA, particle size 16 μm, black First protective layer 38 and second protective layer 39: Product name "TP402", manufactured by Kappakagaku Co., Ltd. Also, the materials and ratios of the coating liquid are shown below. The ratios indicate the ratios with respect to the solid content of the coating liquid.

[0074] Ultraviolet curable compound: Isobornyl acrylate, pentaerythritol triacrylate, urethane acrylate, 41% by weight Polymerization initiator: 1-Hydroxycyclohexyl phenyl ketone, 3% by weight Liquid crystal compound LCM: Cyano biphenyl compound, 54% by weight Dichroic pigments DP: Cyan dichroic pigment (product name: M-412, manufactured by Mitsui Chemicals, Inc.), 0.5% by weight, black dichroic pigment (product name: YH-428, manufactured by Mitsui Chemicals, Inc.), 1.5% by weight Using the coating solution of Example 1, a coating film with a thickness of 16 μm was formed on the first transparent electrode layer 34, and the spacers SP were dispersed in the coating film. Then, the coating film in which the spacers SP were dispersed was laminated by the first transparent electrode layer 34 and the second transparent electrode layer 35, and the dimming sheet 11 of Example 1 was obtained by irradiating ultraviolet light with a wavelength of 365 nm toward the first transparent support layer 36. At this time, the intensity of the ultraviolet light was set to 10 mW / cm 2 and the irradiation time of the ultraviolet light was set to 100 seconds.

[0075] Furthermore, the first protective layer 38 was bonded to the first transparent electrode layer 34 with an adhesive. Also, the second protective layer 39 was bonded to the second transparent electrode layer 35 with an adhesive. The optical properties of the laminate 13 are shown below. The total light transmittance was measured by a method conforming to JIS K 7361-1:1997 (ISO 1468-1). Chromaticity a * and chromaticity b * are specified in the CIE1976 (L * a * b * ) color system.

[0076] Total light transmittance: 15.5% Chromaticity a * : -4.4 Chromaticity b * : -14.6 The optical properties of the first protective layer 38 and the second protective layer 39 are shown below.

[0077] Absorption wavelength: 360 nm or more and 430 nm or less Chromaticity a * : -7.8 Chromaticity b * : +9.4 (Example 2) Only the black dichroic pigment (product name: YH-428, manufactured by Mitsui Chemicals, Inc.) was used as the dichroic pigment DP. The content of the black dichroic pigment was 2.0% by weight, the same as in Example 1. A coating liquid for Example 2 was prepared with the same mixing ratio as the coating liquid of Example 1. Under the same conditions as in Example 1, the light control sheet 11 of Example 2 was obtained.

[0078] The optical properties of the laminate 13 are shown below. Total light transmittance: 13.0% Chromaticity a * : -0.2 Chromaticity b * : +5.0 The optical properties of the first protective layer 38 and the second protective layer 39 are shown below.

[0079] Absorption wavelength: 360 nm or more and 430 nm or less Chromaticity a * : -7.8 Chromaticity b * : +9.4 (Example 3) A coating liquid for Example 3 was prepared with the same mixing ratio as the coating liquid of Example 1, using 1% by weight of a blue dichroic pigment (product name: M-412, manufactured by Mitsui Chemicals, Inc.) and 1% by weight of a black dichroic pigment (product name: YH-428, manufactured by Mitsui Chemicals, Inc.). Under the same conditions as in Example 1, the light control sheet 11 of Example 3 was obtained.

[0080] The optical properties of the laminate 13 are shown below. Total light transmittance: 14.0% Chromaticity a * : +4.8 Chromaticity b * : -15.6 The optical properties of the first protective layer 38 and the second protective layer 39 are shown below.

[0081] Absorption wavelength: 360 nm or more and 430 nm or less Chromaticity a * : -7.8 Chromaticity b * : +9.4 (Comparative Example 1) As the dichroic pigment DP, a black dichroic pigment (product name: YH-428, manufactured by Mitsui Chemicals, Inc.) was used, and a coating liquid for Comparative Example 1 was prepared with the same mixing ratio as the coating liquid of Example 1. Under the same conditions as in Example 1, a dimming sheet 11 for Comparative Example 1 was obtained.

[0082] The optical properties of the laminate 13 are shown below. Total light transmittance: 11.5% Chromaticity a * : -0.6 Chromaticity b * : +4.8 The optical properties of the first protective layer 38 and the second protective layer 39 are shown below.

[0083] Absorption wavelength: 360 nm or more and 395 nm or less Chromaticity a * : -2.0 Chromaticity b * : +2.0 (Comparative Example 2) As the dichroic pigment DP, a black dichroic pigment (product name: YH-428, manufactured by Mitsui Chemicals, Inc.) was used, and a coating liquid for Comparative Example 1 was prepared with the same mixing ratio as the coating liquid of Example 1. Under the same conditions as in Example 1, a dimming sheet 11 for Comparative Example 2 was obtained.

[0084] The optical properties of the laminate 13 are shown below. Total light transmittance: 11.6% Chromaticity a * : -0.6 Chromaticity b * : +4.8 The optical properties of the first protective layer 38 and the second protective layer 39 are shown below.

[0085] Absorption wavelength: 360 nm or more and 407 nm or less Chromaticity a * : -4.0 Chromaticity b * : +5.8 (Comparative Example 3) As the dichroic pigment DP, a blue dichroic pigment (product name: M-412, manufactured by Mitsui Chemicals, Inc.) was used, and a coating liquid for Comparative Example 1 was prepared at the same compounding ratio as the coating liquid of Example 1. Under the same conditions as in Example 1 except for this, a light control sheet 11 for Comparative Example 2 was obtained.

[0086] The optical properties of the laminate 13 are shown below. Total light transmittance: 11.5% Chromaticity a * : +17.7 Chromaticity b * : -48.7 The optical properties of the first protective layer 38 and the second protective layer 39 are shown below.

[0087] Absorption wavelength: 360 nm or more and 430 nm or less Chromaticity a * : -7.8 Chromaticity b * : +13.0 [Evaluation] Using the light control sheets 11 of Examples 1 to 3 and Comparative Examples 1 to 3, evaluations were performed on the following evaluation items (a) to (d).

[0088] (a) Total light transmittance of the light control sheet 11 in the opaque state (b) Chromaticity evaluation (c) Color tone evaluation (d) Light resistance evaluation In the measurement of the total light transmittance in (a) above, the light control sheet 11 was maintained in the opaque state without applying a driving voltage, and the total light transmittance was measured using a total light transmittance measuring device (product name: NDH7000, manufactured by Nippon Denshoku Industries Co., Ltd.) according to the method compliant with JIS K 7361-1:1997 (ISO 1468-1).

[0089] The total light transmittance of Example 1 was maximized at 15.0%, and the total light transmittances of Examples 1 to 3 and Comparative Examples 1 to 3 were all 30% or less. Therefore, Examples 1 to 3 and Comparative Examples 1 to 3 satisfied the above-described characteristic 1.

[0090] In the evaluation of the chromaticity in (b) above, the chromaticity a * , b * was measured using a colorimeter (product name U-4100, manufactured by Hitachi High-Tech Science). The dimming sheets 11 of Examples 1 to 3 and the dimming sheets 11 of Comparative Examples 1 and 2 satisfied Property 2. The chromaticity a * of the laminate 13 of Comparative Example 3 was 17.7, and the chromaticity b * was -48.7, not satisfying Property 2.

[0091] In the evaluation of the color tone in (c) above, it was determined by the naked eye whether there was a yellowish tint. No yellowish tint was confirmed in Examples 1 to 3 and Comparative Examples 1 and 2. In the table shown in FIG. 5, the evaluation was marked as "〇". Also, since a yellowish tint was confirmed in Comparative Example 3 that did not satisfy Property 2, the evaluation was marked as "×".

[0092] With reference to FIG. 6, the light resistance evaluation method in (d) above will be described. The dimming sheet 11 was placed on the stage 51, and the chromaticity was measured using a colorimeter. The chromaticity measured at this time was taken as the initial chromaticity. Further, a glass plate 50 with a thickness of 1.1 mm was placed on the dimming sheet 11, and ultraviolet light 52 was irradiated using an ultraviolet irradiation device (EYESUPER UV TESTER, manufactured by Iwasaki Electric Co., Ltd.). The irradiation conditions were a temperature of 60°C, an illuminance of 65 mW / cm 2 , and 500 hours. After irradiating the ultraviolet light for 500 hours, the chromaticity was measured and compared with the initial chromaticity. When the difference in chromaticity was 3 or less, the evaluation was marked as "〇" indicating high light resistance. When the difference in chromaticity was more than 3 and 5 or less, the evaluation was marked as "△" indicating low light resistance. When the difference in chromaticity was more than 5, the evaluation was marked as "×" indicating low light resistance.

[0093] In Examples 1 to 3 and Comparative Example 3, there was no significant change between the initial chromaticity and the chromaticity after ultraviolet irradiation, and they were found to have high light resistance. On the other hand, Comparative Example 1 had low light resistance and was evaluated as "×". This is presumably because the absorption wavelength ranges of the first protective layer 38 and the second protective layer 39 are from 360 nm to 395 nm and the maximum wavelength does not reach the visible region. Although Comparative Example 2 did not reach the degree of fading of Comparative Example 1, it was found to have low light resistance and was evaluated as "Δ". This is presumably because the absorption wavelength ranges of the first protective layer 38 and the second protective layer 39 are from 360 nm to 407 nm, and although the maximum wavelength reaches the visible region, it is not a long wavelength enough to sufficiently suppress the corrosion resistance of the dichroic dye DP.

[0094] (Modification example) Each of the above embodiments can be implemented with the following modifications. The above embodiments and the following modification examples can be implemented in combination with each other as long as they do not technically conflict with each other.

[0095] · In the above embodiment, the spacer SP was made to have the same color as the black color exhibited by the light control layer in the opaque state. Instead of or in addition to this, the spacer SP may be made to have a color similar to the black color exhibited by the light control layer 31 in the opaque state. Or, some or all of the plurality of spacers SP added to the light control layer 31 may be made colorless and transparent, and by adjusting the particle size, the appearance may be such that the spacers are not conspicuous.

[0096] · In the above embodiment, the first protective layer 38 and the second protective layer 39 were laminated on the laminate 13. Instead of this, a protective layer may be provided on one of the pair of surfaces of the laminate 13.

[0097] · In the above embodiment, the first protective layer 38 and the second protective layer 39 suppressed the incidence of light of a specific wavelength on the light control layer 31 by absorbing light of a specific wavelength including the ultraviolet region. Instead of or in addition to this, the first protective layer 38 and the second protective layer 39 may suppress the incidence of light of a specific wavelength on the light control layer 31 by reflecting light of a specific wavelength.

[0098] ·In the above embodiment, the dimming layer 31 has a structure including a resin layer and a liquid crystal composition. Alternatively, the dimming sheet 11 may be of the SPD (Suspended Particle Device) type having light control particles as alignment particles. The SPD method is a method of dispersing a light control suspension containing light control particles in a resin matrix.

Explanation of reference numerals

[0099] DP... Dichroic pigment LCM... Liquid crystal compound SP... Spacer 10... Dimming device 11... Dimming sheet

Claims

1. A dimming layer containing a liquid crystal compound and a dichroic dye, A pair of transparent electrode layers sandwiching the dimming layer, A laminate having a pair of transparent support layers sandwiching the dimming layer and the pair of transparent electrode layers, A dimming sheet that controls the alignment of the liquid crystal compound and the dichroic dye according to the potential difference between the pair of transparent electrode layers and controls to a transparent state and a colored opaque state, Further comprising a protective layer that absorbs light in an absorption wavelength range including the ultraviolet region, provided on a surface of at least one of the transparent support layers facing the surface in contact with the transparent electrode layer, In the opaque state, the laminate has a chromaticity a in the CIE1976 (L ＊ a ＊ b ＊ ) color system that is -15 or more and 15 or less, and a chromaticity b ＊ that is -16 or more and 15 or less, ＊ and The absorption wavelength range of the protective layer is The minimum wavelength of the wavelength range in which an absorption spectrum is observed is 360 nm or less, and The maximum wavelength of the wavelength range in which the absorption spectrum is observed is in the range of 410 nm or more and 430 nm or less within the visible region, The chromaticity a in the CIE1976 (L ＊ a ＊ b ＊ ) color system compliant with JIS-Z-8781-4 of the protective layer is -10 or more and 0 or less, and the chromaticity b ＊ is 0 or more and 15 or less ＊ ​ Dimming sheet.

2. The protective layer has a total light transmittance of 70% or more The dimming sheet according to claim 1.

3. Further comprising a spacer that exhibits the same color as the color exhibited by the dichroic dye in the opaque state The dimming sheet according to claim 1 or 2.

4. The total light transmittance in the opaque state is 30% or less The dimming sheet according to any one of claims 1 to 3.

5. A laminate having a dimming layer containing a liquid crystal compound and a dichroic dye, a pair of transparent electrode layers sandwiching the dimming layer, and a pair of transparent support layers sandwiching the dimming layer and the pair of transparent electrode layers, A dimming device comprising a driving unit that generates a potential difference between the pair of transparent electrode layers to control the alignment of the liquid crystal compound and the dichroic dye and controls to a transparent state and an opaque state, Further comprising a protective layer that absorbs light in an absorption wavelength range including the ultraviolet region, provided on a surface of at least one of the transparent support layers facing the surface in contact with the transparent electrode layer, In the opaque state, the laminate has a chromaticity a in the CIE1976 (L ＊ a ＊ b ＊ ) color system in accordance with JIS-Z-8781-4 such that the chromaticity a ＊ is not less than -15 and not more than 15, and the chromaticity b ＊ is not less than -16 and not more than 15. The absorption wavelength range of the protective layer is The minimum wavelength of the wavelength range in which an absorption spectrum is observed is 360 nm or less, and The maximum wavelength of the wavelength range in which the absorption spectrum is observed is in the range of 410 nm or more and 430 nm or less within the visible region, The chromaticity a in the CIE1976 (L ＊ a ＊ b ＊ ) color system compliant with JIS-Z-8781-4 of the protective layer is -10 or more and 0 or less, and the chromaticity b ＊ is 0 or more and 15 or less ＊ ​ Dimming device.

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