Dimming sheet

Abstract

A light control sheet is provided with: a light control layer that contains a transparent polymer layer that contains a plurality of microcells, and a liquid crystal composition that fills the microcells and contains a liquid crystal compound and a dichroic dye; and a pair of transparent electrode layers that sandwich the light modulation layer. The dimming sheet switches from a colored opaque state to a transparent state by changing the orientation of the liquid crystal compound and the dichroic dye according to a change in a potential difference between the pair of transparent electrode layers. The average diameter of the microcells is 0.7 [mu] m or less.

Description

Technical Field

[0001] The present disclosure relates to a dimming film. Background Art

[0002] The dimming sheet includes a dimming layer in which a liquid crystal composition is dispersed in a polymer material and a pair of transparent electrode layers sandwiching the dimming layer. A driving voltage is applied between the pair of transparent electrode layers. Since the orientation state of the liquid crystal molecules changes depending on whether the driving voltage is applied, it is possible to switch between a transparent state in which light passes through the dimming layer and an opaque state in which light is scattered in the dimming layer.

[0003] Generally, the dimming sheet in a transparent state is colorless and transparent, while the dimming sheet in an opaque state looks whitish and turbid. On the other hand, from the perspective of design corresponding to the use environment, it is sometimes preferred that the dimming sheet in an opaque state is colored different from white. Therefore, a scheme of adding a dichroic pigment to a liquid crystal composition has been proposed (for example, refer to Patent Document 1). The dichroic pigment has the property that the absorbance in the long axis direction of the molecule is greater than the absorbance in the short axis direction, and is oriented according to the liquid crystal molecules. By adding the dichroic pigment, the dimming sheet in the opaque state shows the color from the dichroic pigment.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 7024801 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] In order to clearly distinguish the difference between the transparent state and the opaque state in the dimming sheet containing dichroic pigments, it is preferred that the ratio of the total light transmittance of the transparent state to that of the opaque state is large. For example, in the dimming sheet of Patent Document 1, since a horizontal orientation film is provided between the transparent electrode layer and the dimming layer, when no driving voltage is applied, the liquid crystal molecules and the dichroic pigments are horizontally oriented relative to the transparent electrode layer. That is, a large amount of dichroic pigments are oriented in a direction whose long axis direction is substantially orthogonal to the incident direction of light. Therefore, the color rendering of the dichroic pigments becomes stronger in the opaque state, so the ratio of the total light transmittance of the transparent state to that of the opaque state can be increased.

[0009] On the other hand, in a dimming film in which no horizontal alignment film or other alignment film is provided, i.e., in which the orientations of liquid crystal molecules and dichroic dyes are irregular in the opaque state, there is still room for improvement in the structure for increasing the ratio of the total light transmittance between the transparent state and the opaque state.

[0010] Means for solving technical problems

[0011] One mode of a dimming sheet comprises: a dimming layer comprising a transparent polymer layer and a liquid crystal composition, wherein the transparent polymer layer comprises a plurality of microdomains, the liquid crystal composition fills the microdomains and comprises a liquid crystal compound and a dichroic pigment; and a pair of transparent electrode layers sandwiching the dimming layer, wherein the orientation of the liquid crystal compound and the dichroic pigment is changed according to a change in the potential difference between the pair of transparent electrode layers, thereby switching from a colored opaque state to a transparent state. The average diameter of the microdomain is 0.7 μm or less. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a cross-sectional view showing the stacked structure of the dimming sheet according to the first embodiment.

[0013] Figure 2 It is a schematic diagram showing the structure of the light-adjusting layer according to the first embodiment. DETAILED DESCRIPTION

[0014] (First Embodiment)

[0015] A first embodiment of a dimming sheet will be described with reference to the drawings.

[0016] [Structure of dimming film]

[0017] Reference Figure 1 , the overall structure of the dimming film is explained.

[0018] like Figure 1 As shown, the dimming sheet 10 includes a dimming layer 20, a first transparent electrode layer 31, a second transparent electrode layer 32, a first transparent support layer 41, and a second transparent support layer 42. The dimming layer 20 is sandwiched between the first transparent electrode layer 31 and the second transparent electrode layer 32, and is in contact with these transparent electrode layers 31 and 32. The first transparent support layer 41 supports the first transparent electrode layer 31 on the side opposite to the dimming layer 20 with respect to the first transparent electrode layer 31, and the second transparent support layer 42 supports the second transparent electrode layer 32 on the side opposite to the dimming layer 20 with respect to the second transparent electrode layer 32.

[0019] The light-adjusting layer 20 includes a transparent polymer layer having a plurality of voids and a liquid crystal composition held in the voids. The light-adjusting layer 20 has a structure of, for example, polymer dispersed liquid crystal (PDLC) or polymer network liquid crystal (PNLC).

[0020] The first transparent electrode layer 31 and the second transparent electrode layer 32 are respectively conductive and transparent to light in the visible region. The transparent electrode layers 31 and 32 are made of materials such as indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, poly(3,4-ethylenedioxythiophene), silver, silver alloys, etc.

[0021] The first transparent support layer 41 and the second transparent support layer 42 are substrates that are transparent to light in the visible region. The materials of the transparent support layers 41 and 42 are, for example, synthetic resins and inorganic compounds. Synthetic resins are, for example, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyacrylates such as polymethyl methacrylate, polycarbonates, polyolefins, etc. Inorganic compounds are, for example, silicon dioxide, silicon oxynitride, silicon nitride, etc.

[0022] The first transparent electrode layer 31 and the second transparent electrode layer 32 are connected to the control unit 50 via wiring. The control unit 50 generates a voltage for driving the dimming sheet 10, and applies the generated voltage to the transparent electrode layers 31 and 32 through the wiring. The control unit 50 controls the potential difference between the transparent electrode layers 31 and 32 by controlling whether the voltage is applied and the magnitude of the applied voltage. The dimming sheet 10 and the control unit 50 constitute a dimming device.

[0023] In addition, the dimming sheet 10 is attached to a transparent substrate as an object to be installed. The transparent substrate is a glass substrate or a resin substrate. An example of a transparent substrate is a window glass carried by a mobile body such as a vehicle or an airplane, a window glass installed in a building, or a partition arranged in a car or indoors. The surface to which the dimming sheet 10 is attached is a flat surface or a curved surface. In addition, the dimming sheet 10 can also be sandwiched between two transparent substrates.

[0024] [Structure of dimming layer]

[0025] Reference Figure 2 , describing the detailed structure of the dimming layer 20. Figure 2 The figure schematically shows the stacked portion of the light control layer 20 and the transparent electrode layers 31 and 32 in the cross-sectional structure of the light control sheet 10 , with emphasis on the structure of the light control layer 20 .

[0026] The light-adjusting layer 20 includes a transparent polymer layer 21, a liquid crystal composition 22, and a spacer 23. The transparent polymer layer 21 is a cured product of a photopolymerizable compound. The transparent polymer layer 21 is divided into a plurality of dispersed microdomains 21D inside. In other words, the microdomains 21D are voids. The shape of the microdomains 21D is, for example, a roughly spherical shape, a roughly ellipsoidal shape, or an indefinite shape. The space inside the microdomains 21D is filled with the liquid crystal composition 22.

[0027] The microdomain diameter, which is an indicator of the size of the microdomain 21D, is greater than or equal to 0.3 μm and less than or equal to 0.7 μm. The microdomain diameter is the average diameter of the microdomains 21D included in the light-adjusting layer 20, and is determined by the microdomains 21D included in the cross section in the thickness direction of the light-adjusting layer 20, in other words, in the cross section orthogonal to the plane in which the light-adjusting layer 20 extends. That is, for each microdomain 21D included in the above cross section, the diameter of a circle having the same area as the area of ​​the microdomain 21D is defined as the microdomain diameter of the microdomain 21D, and the average of the microdomain diameters of the microdomains 21D included in the above cross section is set as the microdomain diameter of the light-adjusting layer 20.

[0028] The ratio of the transparent polymer layer 21 in the transparent polymer layer 21 and the liquid crystal composition 22 is preferably 20 mass % or more and 80 mass % or less, and more preferably 30 mass % or more and 60 mass % or less. When the ratio of the transparent polymer layer 21 is within the above range, the micro-domain 21D can be appropriately ensured. Within the above range, the greater the ratio of the transparent polymer layer 21, the more the mechanical strength of the transparent polymer layer 21 can be improved, and the smaller the ratio of the transparent polymer layer 21, the lower the driving voltage of the dimming sheet 10 can be.

[0029] The photopolymerizable compound of the material of the transparent polymer layer 21 may be an ultraviolet curable compound or an electron beam curable compound. The photopolymerizable compound is compatible with the liquid crystal composition 22. If the photopolymerizable compound is an ultraviolet curable compound, the controllability of the size of the microdomain 21D is improved. The photopolymerizable compound may be one type of polymerizable compound or a combination of two or more types of polymerizable compounds.

[0030] An example of an ultraviolet curable compound includes a polymerizable unsaturated bond at the end of the molecular structure. Another example of an ultraviolet curable compound includes a polymerizable unsaturated bond other than the end of the molecular structure. Examples of ultraviolet curable compounds include acrylate compounds, methacrylate compounds, thiol compounds, styrene compounds, and oligomers of these compounds. Acrylate compounds include diacrylate compounds, triacrylate compounds, and tetraacrylate compounds. An example of an acrylate compound is butyl ethyl acrylate, ethylhexyl acrylate, and cyclohexyl acrylate. Methacrylate compounds include dimethacrylate compounds, trimethacrylate compounds, and tetramethacrylate compounds. An example of a methacrylate compound is N,N-dimethylaminoethyl methacrylate, phenoxyethyl methacrylate, methoxyethyl methacrylate, and tetrahydrofurfuryl methacrylate. An example of a thiol compound is 1,3-propanedithiol and 1,6-hexanedithiol. An example of a styrene compound is styrene and methyl styrene.

[0031] The transparent polymer layer 21 is formed by polymerizing a photopolymerizable compound using a photopolymerization initiator. In order to form a microdomain diameter of 0.7 μm or less, it is preferred to use one or more selected from oxime ester compounds, alkyl phenone compounds, and acyl phosphine oxide compounds as the photopolymerization initiator. It is particularly preferred that the photopolymerization initiator contains an oxime ester compound, or contains an alkyl phenone compound and an acyl phosphine oxide compound.

[0032] These photopolymerization initiators are excited by the absorption of light in the ultraviolet region and initiate a cleavage reaction, and the free radicals thus generated react with the photopolymerizable compound to initiate polymerization. Therefore, in the case where an oxime ester compound is included in the photopolymerization initiator, the polymer compound constituting the transparent polymer layer 21 includes a polymer compound containing an intramolecular dissociation group of the oxime ester compound at the end of the molecular structure. For example, in the case where the photopolymerizable compound is a (meth)acrylate compound, the transparent polymer layer 21 includes a polymer compound having a skeleton derived from (meth)acrylate and having an intramolecular dissociation group of the oxime ester compound at the end of the molecular structure. "(Meth)acrylate" includes acrylate and methacrylate. It should be noted that the transparent polymer layer 21 may also include a polymer compound containing an intramolecular dissociation group of the oxime ester compound other than the end of the molecular structure.

[0033] Similarly, when the photopolymerization initiator contains an alkylphenone compound, the polymer compound constituting the transparent polymer layer 21 contains a polymer compound containing an intramolecular dissociation group of the alkylphenone compound at the terminal of the molecular structure. The transparent polymer layer 21 may further contain a polymer compound containing an intramolecular dissociation group of the alkylphenone compound other than the terminal of the molecular structure.

[0034] In addition, when the photopolymerization initiator contains an acylphosphine oxide compound, a polymer compound containing an intramolecular dissociation group of the acylphosphine oxide compound at the terminal of the molecular structure is contained in the polymer compound constituting the transparent polymer layer 21. The transparent polymer layer 21 may further contain a polymer compound containing an intramolecular dissociation group of the acylphosphine oxide compound other than the terminal of the molecular structure.

[0035] Oxime ester compounds have, for example, any one of a carbazole skeleton, a diphenyl sulfide skeleton, and a fluorene skeleton. Specific examples of oxime ester compounds are 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(O-benzoyloxime), ethyl ketone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-, 1-(O-acetyloxime), methyl ketone, [8-[[(acetoxy)imino][2-(2,2,3,3-tetrafluoropropoxy)phenyl]methyl]-11-(2-ethylhexyl)-1 1H-benzo[a]carbazole-5-yl]-,(2,4,6-trimethylphenyl), ethyl ketone, 1-[9-ethyl-6-(1,3-dioxolane,4-(2-methoxyphenoxy)-9H-carbazole-3-yl]-,1-(o-acetyl oxime), methyl ketone,(9-ethyl-6-nitro-9H-carbazole-3-yl)[4-(2-methoxy-1-methylethoxy-2-methylphenyl]-,o-acetyl oxime, etc.

[0036] As commercially available products of oxime ester compounds, for example, Irgacure OXE01 (manufactured by BASF Japan), Irgacure OXE02 (manufactured by BASF Japan), Irgacure OXE03 (manufactured by BASF Japan), Irgacure OXE04 (manufactured by BASF Japan), ADEKA ARKLS N-1919T (manufactured by ADEKA), ADEKA ARKLS NCI-831E (manufactured by ADEKA), ADEKA ARKLS NCI-930 (manufactured by ADEKA), ADEKA ARKLS NCI-730 (manufactured by ADEKA), etc. can be used.

[0037] Alkylphenone compounds include, for example, α-aminoalkylphenone compounds, α-hydroxyalkylphenone compounds, α-hydroxyacetophenone compounds, benzyl ketal compounds, etc. Among them, α-aminoalkylphenone compounds are preferably used. Specific examples of alkylphenone compounds include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one, 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methylpropiophenone, 2,2-dimethoxy-2-phenylacetophenone, etc.

[0038] As commercially available products of the alkylphenone compound, for example, Irgacure 907 (manufactured by BASF Japan), Irgacure 184 (manufactured by BASF Japan), Irgacure 1173 (manufactured by BASF Japan), and Irgacure 651 (manufactured by BASF Japan) can be used.

[0039] Examples of the acylphosphine oxide compound include monoacylphosphine oxide, bisacylphosphine oxide, etc. Specific examples of the acylphosphine oxide compound include diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, etc.

[0040] As a commercially available product of the acylphosphine oxide compound, for example, Irgacure TPO (manufactured by BASF Japan Co., Ltd.) etc. can be used.

[0041] The liquid crystal composition 22 includes a liquid crystal compound 22L and a dichroic pigment 22P. It should be noted that the liquid crystal composition 22 may further include a viscosity reducer, a defoaming agent, an antioxidant, a weathering agent, etc. An example of a weathering agent is an ultraviolet absorber and a light stabilizer.

[0042] The liquid crystal compound 22L is a non-polymerizable compound. The dielectric constant of the liquid crystal compound 22L in the long axis direction is higher than the dielectric constant of the liquid crystal compound 22L in the short axis direction. That is, the liquid crystal compound 22L has positive dielectric anisotropy.

[0043] The liquid crystal compound 22L is, for example, a Schiff base compound, an azo compound, an azoxy compound, a biphenyl compound, a terphenyl compound, a benzoate compound, a diphenylacetylene compound, a pyrimidine compound, a pyridazine compound, a cyclohexanecarboxylate compound, a phenylcyclohexane compound, a biphenylcyclohexane compound, a dicyanobenzene compound, a naphthalene compound, or a dioxane compound. The liquid crystal compound 22L may be one liquid crystal compound or a combination of two or more liquid crystal compounds.

[0044] An example of the liquid crystal compound 22L is a compound represented by the following general formula (1).

[0045] R 11 -A 11 -Z 11 -A 12 -Z 12 -A 13 -Z 13 -A 14 -R 12 (1)

[0046] In the above general formula (1), R 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 R may 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 any one selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group, and an alkyl group having 1 to 15 carbon atoms. 12One or two or more non-adjacent methylene bonds contained in may be substituted with any one selected from the group consisting of an oxygen atom, an ethylene bond, an ester bond, and a diether bond.

[0047] A 11 , A 12 , A 13 , A 14 Each is independently 1,4-phenylene or 2,6-naphthylene. One or more hydrogen atoms in the above 1,4-phenylene and 2,6-naphthylene may be substituted with any one selected from the group consisting of fluorine atoms, chlorine atoms, trifluoromethyl and trifluoromethoxy. Alternatively, A 11 , A 12 , A 13 , A 14 Each independently may be any one selected from 1,4-cyclohexylene, 3,6-cyclohexenylene, 1,3-dioxane-2,5-diyl and pyridine-2,5-diyl. 13 , A 14 Each independently may be a single bond.

[0048] Z 11 , Z 12 , Z 13 Each is independently any one selected from a single bond, an ester bond, a diether bond, an ethylene bond, a fluoroethylene bond and a carbonyl bond.

[0049] The dichroic pigment 22P has an elongated molecular shape, and the absorbance in the visible region in the long axis direction of the molecule is greater than the absorbance in the short axis direction. The dichroic pigment 22P displays a predetermined color in a state where the long axis direction is substantially orthogonal to the incident direction of light. The color presented by the dichroic pigment 22P is, for example, black or a color close to black. The dichroic pigment 22P is driven by a guest-host mode with the liquid crystal compound 22L as the main body to display the color.

[0050] The dichroic pigment 22P is, for example, polyiodine, azo compounds, anthraquinone compounds, naphthoquinone compounds, azomethine compounds, tetrazine compounds, quinophthalone compounds, merocyanine compounds, perylene compounds, and dioxazine compounds. The dichroic pigment 22P can be one pigment or a combination of two or more pigments. From the viewpoint of improving light resistance and dichroic ratio, the dichroic pigment 22P is preferably selected from at least one of an azo compound and an anthraquinone compound, and more preferably an azo compound.

[0051] The ratio of the dichroic pigment 22P in the transparent polymer layer 21 and the liquid crystal composition 22 is preferably 0.5 mass % or more and 10 mass % or less, and more preferably 1 mass % or more and 5 mass % or less. By setting the ratio of the dichroic pigment 22P to 0.5 mass % or more, the difference in color between the transparent state and the opaque state of the dimming sheet 10 can be easily and clearly identified. By setting the ratio of the dichroic pigment 22P to 10 mass % or less, the precipitation of particles formed by the aggregation of the dichroic pigment 22P can be suppressed.

[0052] The spacers 23 are dispersed throughout the entire transparent polymer layer 21. The spacers 23 regulate the thickness of the light-adjusting layer 20 around the spacers 23, thereby making the thickness of the light-adjusting layer 20 uniform. The spacers 23 may be bead spacers or photospacers formed by exposure and development of a photoresist. The spacers 23 may be colorless and transparent or colored and transparent as long as they are light-transmissive. The color presented by the colored and transparent spacers 23 is preferably the same color as the color presented by the dichroic pigment 22P.

[0053] The thickness of the light-adjusting layer 20 is substantially the same as the size of the spacer 23, so the thickness of the light-adjusting layer 20 can be controlled by changing the average particle size of the spacer 23. As an example, the average particle size of the spacer 23 is 10 μm or more and 30 μm or less in terms of median diameter D50. In this case, the thickness of the light-adjusting layer 20 is 10 μm or more and 30 μm or less.

[0054] [Modifier Operation]

[0055] Based on the control of the control unit 50, a voltage for changing the orientation state of the liquid crystal compound 22L and the dichroic dye 22P, that is, a driving voltage, is applied to the first transparent electrode layer 31 and the second transparent electrode layer 32. Based on the change in the orientation state of the liquid crystal compound 22, the dimming sheet 10 switches from one of the transparent state and the opaque state to the other. In the opaque state, the total light transmittance of the dimming sheet 10 is lower than that in the transparent state, and the haze of the dimming sheet 10 is higher than that in the transparent state.

[0056] When the driving voltage is not applied, the orientation of the long axis direction of the liquid crystal compound 22L and the dichroic pigment 22P is disordered. Therefore, due to the refractive index difference between the liquid crystal compound 22L and the transparent polymer layer 21 caused by the birefringence of the liquid crystal compound 22L, the light incident on the dimming sheet 10 is scattered in various directions in the dimming layer 20. In addition, the orientation of the long axis direction of the dichroic pigment 22P is disordered, so at least a part of the dichroic pigment 22P is colored. Therefore, when the driving voltage is not applied, the dimming sheet 10 becomes opaque and looks colored.

[0057] When a driving voltage is applied, the liquid crystal compound 22L and the dichroic pigment 22P are oriented in a direction in which their long axis directions are along the direction of the electric field. That is, the orientation of the liquid crystal compound 22L and the dichroic pigment 22P is changed in a manner in which the long axis directions are along the thickness direction of the dimming layer 20. As a result, the scattering of light in the dimming layer 20 and the color development of the dichroic pigment 22P are suppressed, and light easily passes through the dimming sheet 10. Therefore, when a driving voltage is applied, the dimming sheet 10 becomes transparent.

[0058] As described above, the opaque state and the transparent state of the light control sheet 10 are switched by switching the application and release of the driving voltage.

[0059] Here, in the present embodiment, the size of the microdomain 21D included in the dimming layer 20 is smaller than before. Therefore, in the opaque state, the scattering of light at the interface between the transparent polymer layer 21 and the liquid crystal composition 22, that is, the boundary between the microdomain 21D and the liquid crystal composition 22 becomes larger. As a result, the scattered light in the dimming layer 20 increases and the absorption of light by the dichroic pigment 22P becomes larger, and the color development of the dichroic pigment 22P becomes stronger, so the total light transmittance of the dimming sheet 10 in the opaque state decreases. Therefore, even if an alignment film is not used, the difference in total light transmittance between the transparent state and the opaque state can be increased. Specifically, by making the microdomain diameter less than 0.7μm, the ratio of the total light transmittance between the transparent state and the opaque state becomes sufficiently large. On the other hand, if the microdomain diameter is more than 0.3μm, the microdomain 21D will not become excessively smaller, so the reduction in the freedom of movement of the liquid crystal compound 22L can be suppressed.

[0060] The ratio of the total light transmittance TTa in the transparent state to the total light transmittance TTb in the opaque state (TTa / TTb) is preferably 8.0 or more. If the above ratio is 8.0 or more, it is easy to clearly identify the difference in transmittance between the opaque state and the transparent state by visual observation. It should be noted that the total light transmittance is measured in accordance with JIS K 7361-1:1997 (ISO 1468-1).

[0061] The microdomain diameter in the light-adjusting layer 20 can be controlled by the sensitivity of the photopolymerization initiator to light, the intensity of light irradiated to the photopolymerizable compound, the irradiation time, the processing temperature during the polymerization of the photopolymerizable compound, etc. In particular, if an oxime ester compound or an acylphosphine oxide compound is used as a photopolymerization initiator, the polymerization reaction is carried out with high sensitivity to light, so it is easy to suppress the microdomain diameter to a small size.

[0062] Furthermore, by using an oxime ester compound as a photopolymerization initiator, yellowing of the dimming sheet 10 can be suppressed compared to the case of using an acylphosphine oxide compound.

[0063] On the other hand, if an acylphosphine oxide compound is used, the dimming sheet 10 tends to be yellowish due to the color tone of the compound, but by using an acylphosphine oxide compound and an alkylphenone compound in combination, good sensitivity to light can be obtained and the yellowing of the dimming sheet 10 can be suppressed. For example, the photopolymerization initiator only needs to contain the same mass of the acylphosphine oxide compound and the alkylphenone compound.

[0064] In the manufacturing process of the dimming layer 20, the color tone of the photopolymerization initiator usually disappears by a photobleaching reaction. However, when the liquid crystal composition 22 includes the dichroic pigment 22P, part of the light energy is absorbed by the dichroic pigment 22P, so the photopolymerization initiator is likely to remain in the dimming layer 20 in an unreacted state. In addition, if the photopolymerization initiator is mixed into the phase-separated liquid crystal composition 22, the photopolymerization initiator is difficult to react. Therefore, it is believed that the color tone of the photopolymerization initiator is likely to remain in the dimming sheet 10.

[0065] The dimming sheet 10 of this embodiment includes the dichroic pigment 22P. Therefore, in the opaque state where the dichroic pigment 22P is colored, even if the dimming sheet 10 has a yellow tint, such a tint can be suppressed from being seen. This effect is particularly significant when the dichroic pigment 22P is black or a color close to black. However, from the perspective of improving the appearance quality of the dimming sheet 10, the tint of the dimming sheet 10 in the transparent state is a problem.

[0066] When an oxime ester compound or a mixture of an acylphosphine oxide compound and an alkylphenone compound is used as a photopolymerization initiator, the yellow color of the dimming sheet 10 can be suppressed to such an extent that the dimming sheet 10 in a transparent state can be said to be achromatic.

[0067] When the color of the dimming sheet 10 is expressed using the CIE1976 (L*a*b*) colorimetric system based on JIS Z 8781-4, the chromaticity a* and chromaticity b* of the dimming sheet 10 in a transparent state preferably satisfy -6≤a*≤6 and -6≤b*≤6, and more preferably satisfy -3≤a*≤3 and -3≤b*≤3. Thus, the dimming sheet 10 tends to look colorless and transparent in a transparent state. In particular, by setting the chromaticity b* to be 6 or less, preferably 3 or less, it can be said that the yellow color of the dimming sheet 10 in a transparent state is appropriately suppressed.

[0068] In addition, when the dichroic pigment 22P presents a black color or a color close to black, the chromaticity a* and chromaticity b* of the dimming sheet 10 in the opaque state preferably satisfy -8≤a*≤8 and -8≤b*≤8, and more preferably satisfy -7≤a*≤7 and -7≤b*≤7. Thus, it is possible to prevent the dimming sheet 10 in the opaque state from appearing to have a color different from black.

[0069] [Method for manufacturing dimming sheet]

[0070] The method for manufacturing the dimming sheet 10 is described below. First, a first transparent supporting layer 41 on which the first transparent electrode layer 31 is stacked and a second transparent supporting layer 42 on which the second transparent electrode layer 32 is stacked are prepared. The transparent electrode layers 31 and 32 are formed by a known film forming method such as sputtering.

[0071] Next, a coating film for forming the light-adjusting layer 20 is formed between the first transparent electrode layer 31 and the second transparent electrode layer 32. The coating film contains a photopolymerizable compound, a liquid crystal compound 22L, a dichroic pigment 22P, and a photopolymerization initiator. The photopolymerization initiator may contain compounds other than the above-mentioned oxime ester compound, alkylphenone compound, and acylphosphine oxide compound.

[0072] It should be noted that the spacer 23 may be contained in the coating liquid for forming the coating film, or may be dispersed in the coating film when the coating film is formed.

[0073] The laminated body sandwiching the coating film is irradiated with light to polymerize the photopolymerizable compound, thereby generating phase separation of the liquid crystal composition 22 to form the dimming layer 20. The light that polymerizes the photopolymerizable compound is ultraviolet light or electron beam. The light that polymerizes the photopolymerizable compound can be irradiated toward the first transparent supporting layer 41, or toward the second transparent supporting layer 42, or toward both the first transparent supporting layer 41 and the second transparent supporting layer 42. Thus, the dimming sheet 10 is formed.

[0074] As described above, according to the dimming sheet of the first embodiment, the following effects can be obtained.

[0075] (1) In the light control sheet 10 , by setting the domain diameter to 0.7 μm or less, the ratio of the total light transmittance in the transparent state to that in the opaque state can be increased.

[0076] (2) As the photopolymerization initiator, one or more selected from the group consisting of oxime ester compounds, alkylphenone compounds, and acylphosphine oxide compounds are used. Furthermore, the multiple ends of the polymer compound included in the transparent polymer layer 21 include one or more selected from the group consisting of intramolecular dissociation groups of oxime ester compounds, intramolecular dissociation groups of alkylphenone compounds, and intramolecular dissociation groups of acylphosphine oxide compounds. According to such a structure, the structure of the light-adjusting layer 20 in which the liquid crystal composition 22 is retained in the microdomain 21D can be appropriately formed.

[0077] (3) The photopolymerization initiator contains an oxime ester compound, and the polymer compound contained in the transparent polymer layer 21 contains intramolecular dissociative groups of the oxime ester compound at multiple terminals. With such a structure, it is particularly easy to form a microdomain diameter of 0.7 μm or less, and the yellowing of the light-adjusting sheet 10 in a transparent state can be appropriately suppressed.

[0078] (4) The photopolymerization initiator includes an alkylphenone compound and an acylphosphine oxide compound, and the multiple ends of the polymer compound included in the transparent polymer layer 21 include intramolecular dissociation groups of the alkylphenone compound and intramolecular dissociation groups of the acylphosphine oxide compound. According to such a structure, it is easy to form a microdomain diameter of 0.7 μm or less, and it is possible to suppress the yellowing of the light-adjusting sheet 10 in a transparent state.

[0079] (5) The dimming sheet 10 in the transparent state satisfies -6≤b*≤6 for the chromaticity b*. Thus, the dimming sheet 10 in the transparent state tends to look achromatic. Such a dimming sheet can be appropriately realized by adopting the above-mentioned structure (3) or (4).

[0080] (6) The light control sheet 10 in the opaque state satisfies -8≤b*≤8 with respect to the chromaticity b*. Therefore, the light control sheet 10 in the opaque state tends to look achromatic.

[0081] (7) The ratio of the total light transmittance in the transparent state to that in the opaque state is 8.0 or more. Thus, a good contrast ratio between the transparent state and the opaque state can be obtained. Therefore, visible light can be fully blocked in the opaque state, and the transparency in the transparent state can be improved.

[0082] (8) The ratio of the dichroic pigment 22P in the transparent polymer layer 21 and the liquid crystal composition 22 is 0.5 mass % or more and 10 mass % or less. This makes it easy to clearly identify the difference in color between the transparent state and the opaque state of the dimming sheet 10, and also suppresses the precipitation of the dichroic pigment 22P and the increase in the manufacturing cost of the dimming sheet 10.

[0083] (9) The ratio of the transparent polymer layer 21 in the transparent polymer layer 21 and the liquid crystal composition 22 is 30% by mass or more and 60% by mass or less. Thus, the transparent polymer layer 21 can appropriately ensure the microdomains 21D, and the structure of the light-adjusting layer 20 in which the liquid crystal composition 22 is dispersed in the transparent polymer layer 21 can be appropriately formed.

[0084] (10) The spacer 23 exhibits the same color as the dichroic dye 22P in the opaque state, thereby making it possible to suppress the spacer 23 from being conspicuous. In addition, the total light transmittance in the opaque state may be reduced.

[0085] (Second Embodiment)

[0086] The second embodiment of the dimming sheet is described. In the manufacturing process of the dimming sheet, a coating film to be a dimming layer is formed from a coating liquid containing a liquid crystal composition, a photopolymerizable compound, and a photopolymerization initiator, and a polymerization reaction of the photopolymerizable compound is carried out in the coating film by irradiating the coating film with light. Thus, a polymer structure is formed, and phase separation of the liquid crystal composition occurs, forming a dimming layer.

[0087] When a dichroic dye is added to a liquid crystal composition, part of the light energy applied to the coating is absorbed by the dichroic dye, so the polymerization reaction is difficult to proceed, and there is a problem of difficulty in inducing phase separation. If the amount of photopolymerization initiator contained in the coating is increased, such a problem can be improved, but the unreacted photopolymerization initiator contained in the dimming layer and the residue of the photopolymerization initiator after the reaction increase, which may lead to a decrease in the performance of the optical properties of the dimming layer.

[0088] Therefore, when the liquid crystal composition contains a dichroic dye, in order to smoothly proceed the reaction required for forming the light-adjusting layer, further improvement of the material of the light-adjusting layer is desired.

[0089] The technical problem of the second embodiment is that the reaction required for the formation of the dimming layer can be smoothly carried out. In addition to the structure of the dimming sheet of the first embodiment, the dimming sheet of the second embodiment also uses an oxime ester compound as a photopolymerization initiator, thereby solving the technical problem. In addition, in the second embodiment, the dimming layer adopts a polymer dispersed liquid crystal structure. The following description focuses on the differences between the second embodiment and the first embodiment, and the same figure marks are marked on the same structures as the first embodiment and their descriptions are omitted.

[0090] [Structure of dimming film]

[0091] In the second embodiment, the light-adjusting layer 20 has a polymer-dispersed liquid crystal structure. That is, the light-adjusting layer 20 includes a transparent polymer layer 21 having a plurality of independent microdomains 21D and a liquid crystal composition 22 held in the microdomains 21D. In other words, the light-adjusting layer 20 has a structure in which liquid crystal droplets are dispersed in a polymer material.

[0092] In the second embodiment, the photopolymerization initiator contains an oxime ester compound, so the polymer compound constituting the transparent polymer layer 21 contains a polymer compound containing an intramolecular dissociation group of the oxime ester compound at the end of the molecular structure. The transparent polymer layer 21 may further contain a polymer compound containing an intramolecular dissociation group of the oxime ester compound other than the end of the molecular structure.

[0093] The ratio of the transparent polymer layer 21 in the transparent polymer layer 21 and the liquid crystal composition 22 is preferably 30 mass % or more and 60 mass % or less, and more preferably 40 mass % or more and 50 mass % or less. When the ratio of the transparent polymer layer 21 is within the above range, the size of the microdomain 21D can be appropriately ensured, and the structure of the polymer dispersed liquid crystal can be appropriately formed.

[0094] The ratio of the liquid crystal compound 22L in the transparent polymer layer 21 and the liquid crystal composition 22 is preferably 40% by mass or more and 70% by mass or less, and more preferably 50% by mass or more and 60% by mass or less. When the ratio of the liquid crystal compound 22L is within the above range, the size of the microdomain 21D can be appropriately ensured, and the structure of the polymer dispersed liquid crystal can be appropriately formed.

[0095] The ratio of the dichroic dye 22P in the transparent polymer layer 21 and the liquid crystal composition 22 is preferably 0.5 mass % or more and 10 mass % or less, and more preferably 1 mass % or more and 5 mass % or less. By setting the ratio of the dichroic dye 22P to 0.5 mass % or more, the degree of polymerization promoted by using the oxime ester compound as a photopolymerization initiator becomes appropriate, and the difference in color between the transparent state and the opaque state of the dimming sheet can be easily and clearly identified.

[0096] The total light transmittance of the light control sheet in the opaque state is preferably 30% or less. This allows the visible light to be sufficiently shielded in the opaque state. The total light transmittance is a value obtained using a measurement method in accordance with JIS K 7361-1: 1997 (ISO 1468-1).

[0097] The total light transmittance of the dimming sheet in the opaque state can be changed by changing the content of the dichroic pigment 22P in the dimming layer 20 and the thickness of the dimming layer 20. Specifically, the total light transmittance in the opaque state can be reduced by increasing the proportion of the dichroic pigment 22P in the dimming layer 20. In addition, the total light transmittance in the opaque state can be reduced by increasing the thickness of the dimming layer 20.

[0098] [Method for manufacturing dimming sheet]

[0099] The manufacturing method of the dimming sheet is described. First, a first sheet having a first transparent electrode layer 31 formed on a first transparent support layer 41 and a second sheet having a second transparent electrode layer 32 formed on a second transparent support layer 42 are prepared. The first transparent electrode layer 31 and the second transparent electrode layer 32 are formed by a known thin film forming method such as sputtering or vacuum evaporation.

[0100] Next, a coating liquid for forming the light-adjusting layer 20 is prepared, and a coating film serving as the light-adjusting layer 20 is formed between the transparent electrode layers 31 and 32 of the first and second sheets by applying the coating liquid.

[0101] The coating liquid contains the above-mentioned photopolymerizable compound, liquid crystal compound 22L, dichroic pigment 22P and photopolymerization initiator. The proportion of the photopolymerizable compound in the coating liquid is preferably 30% by mass or more and 60% by mass or less, more preferably 40% by mass or more and 50% by mass or less. The proportion of the liquid crystal compound 22L in the coating liquid is preferably 40% by mass or more and 70% by mass or less, more preferably 50% by mass or more and 60% by mass or less. If the proportion of the photopolymerizable compound and the liquid crystal compound 22L is within the above range, the size of the microdomain 21D is appropriately ensured by the formed transparent polymer layer 21, and the structure of the polymer dispersed liquid crystal can be appropriately formed. As a result, good optical properties are obtained in the dimming layer 20.

[0102] The proportion of the dichroic pigment 22P in the coating liquid is preferably 0.5 mass % or more and 10 mass % or less, and more preferably 1 mass % or more and 5 mass % or less. By making the proportion of the dichroic pigment 22P 0.5 mass % or more, the degree of polymerization promoted by using the oxime ester compound as a photopolymerization initiator becomes appropriate, and it is easy to clearly identify the difference in color of the light-adjusting sheet in a transparent state and an opaque state. By making the proportion of the dichroic pigment 22P 10 mass % or less, the precipitation of particles formed by the aggregation of the dichroic pigment 22P can be suppressed.

[0103] The ratio of the photopolymerization initiator in the coating liquid is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 1% by mass or more and 3% by mass or less. By setting the ratio of the photopolymerization initiator to 0.1% by mass or more, the polymerization reaction can be properly carried out. By setting the ratio of the photopolymerization initiator to 5% by mass or less, the excessive promotion of the polymerization reaction can be suppressed, and the unreacted photopolymerization initiator can be suppressed from remaining in the light-adjusting layer 20 and reducing the optical properties.

[0104] It should be noted that, in addition to the oxime ester compound, the photopolymerization initiator may also contain a compound different from the oxime ester compound. Photopolymerization initiators other than the oxime ester compound are, for example, diketone compounds, acetophenone compounds, benzoin compounds, benzophenone compounds, thioxanthone compounds, etc. An example of a photopolymerization initiator other than the oxime ester compound is benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, cyclohexyl phenyl ketone, etc.

[0105] The lower limit temperature of the isotropic phase in the coating liquid is 0° C. or higher and lower than 30° C. The lower limit temperature of the isotropic phase is the temperature at which the coating liquid changes from the nematic phase to the isotropic phase.

[0106] The lower limit temperature of the isotropic phase can be adjusted by the type and content of the liquid crystal compound 22L. In particular, by setting the proportion of the liquid crystal compound 22L in the coating liquid to 40 mass % or more and 70 mass % or less, the lower limit temperature of the isotropic phase can be easily set to 0°C or more and less than 30°C.

[0107] If the lower limit temperature of the isotropic phase is within the above range, the coating liquid exhibits properties of an isotropic liquid or a liquid close to an isotropic liquid at room temperature, thereby suppressing the precipitation of liquid crystal components in the coating film, and thus forming a uniform coating film.

[0108] It should be noted that as a structure comparable to the polymer dispersed liquid crystal, a polymer network liquid crystal having a plurality of interconnected voids in the polymer layer can be cited. Compared with the polymer dispersed liquid crystal, the coating liquid used to form the polymer network liquid crystal contains a large amount of liquid crystal compounds and has a higher lower temperature limit of the isotropic phase. Therefore, the coating liquid used to form the polymer network liquid crystal is an anisotropic liquid, i.e., a liquid crystal state, at room temperature, and the properties of the coating liquid are greatly different from those of the present embodiment.

[0109] In the coating film forming step, a coating liquid is applied on the transparent electrode layer of one of the first and second sheets to form a coating film, and the other of the first and second sheets is superimposed on the coating film to form a laminated body with the coating film sandwiched between the first and second sheets.

[0110] The coating liquid can be applied by a known coating method such as drop casting, inkjet, gravure coating, spin coating, slit coating, bar coating, flexographic coating, die coating, dip coating, or roll coating.

[0111] It should be noted that the spacers 23 may be dispersed in the coating film after the coating film is formed, or may be dispersed in the coating film by mixing with the coating liquid. When the spacers 23 are mixed in the coating liquid, the ratio of the spacers 23 in the coating liquid is, for example, about 1 mass %.

[0112] Next, the laminate of the first sheet, the second sheet, and the coating film is irradiated with light of a specific wavelength that causes a polymerization reaction. The light of the specific wavelength is, for example, ultraviolet light. The light can be irradiated toward the first sheet, toward the second sheet, or toward both the first sheet and the second sheet. Thus, a polymerization reaction of the photopolymerizable compound is carried out in the coating film, and phase separation of the droplet-shaped liquid crystal composition 22 is generated, thereby forming a light-adjusting layer 20.

[0113] By forming a laminate including the light-adjusting layer 20 , the transparent electrode layers 31 , 32 , and the transparent supporting layers 41 , 42 as described above, and molding the laminate into an outer shape as necessary, a light-adjusting sheet is formed.

[0114] In the present embodiment, the coating film includes an oxime ester compound as a photopolymerization initiator. Compared with other compounds used as photopolymerization initiators, the oxime ester compound is particularly sensitive to light, that is, the light energy required for the cleavage reaction is small. Therefore, even if a part of the energy of the light irradiated to the laminate is absorbed by the dichroic pigment 22P, the polymerization reaction of the photopolymerizable compound caused by the oxime ester compound can be appropriately induced. Therefore, even if the amount of the photopolymerization initiator is not increased, and even if the content of the dichroic pigment 22P is more, the polymerization of the photopolymerizable compound and the phase separation of the liquid crystal composition 22 can be appropriately carried out.

[0115] Specifically, by properly carrying out the polymerization reaction, in the formed dimming layer 20, it is possible to suppress the increase of the unreacted photopolymerizable compound contained in the liquid crystal composition 22, in other words, it is possible to suppress the increase of the amount of impurities in the liquid crystal composition 22. As a result, it is possible to suppress the decrease of the NI temperature (nematic-isotropic transition temperature) of the liquid crystal composition 22, thereby suppressing the narrowing of the temperature range in which the dimming sheet can be driven.

[0116] In addition, by appropriately carrying out the polymerization reaction, it is possible to prevent the microdomains 21D in the transparent polymer layer 21 from becoming too large and the light scattering property from being reduced in the opaque state. Therefore, it is possible to prevent the light component absorbed by the dichroic dye from being reduced, and thus it is possible to prevent the optical properties of the light modulating sheet such as the total light transmittance from being reduced in the opaque state.

[0117] It should be noted that when a photopolymerization initiator other than an oxime ester compound is used in the first embodiment, in the manufacturing method of the second embodiment, that is, in the coating liquid used to form the dimming layer 20, the lower limit temperature of the isotropic phase can be set to above 0°C and less than 30°C, and the dimming layer 20 can be set to a polymer dispersed liquid crystal.

[0118] In addition, when the domain diameter is larger than 0.7 μm, the structure of the second embodiment can be adopted. Even in this case, the technical problem of the second embodiment can be solved.

[0119] As described above, according to the dimming sheet and the manufacturing method thereof of the second embodiment, the following effects can be obtained.

[0120] (11) Since an oxime ester compound is used as a photopolymerization initiator, polymerization reaction and phase separation of the liquid crystal composition can be appropriately performed when forming the light-adjusting layer 20. Therefore, degradation of the light-adjusting sheet's optical characteristics and drivable temperature range can be suppressed.

[0121] (12) In the coating liquid for forming the light-adjusting layer 20, the lower limit temperature of the isotropic phase is 0° C. or higher and lower than 30° C. Thus, the coating liquid exhibits properties of an isotropic liquid or similar properties, so that a uniform coating film can be easily obtained, and the structure of the polymer-dispersed liquid crystal can be appropriately formed.

[0122] (13) In the coating liquid used to form the dimming layer 20, the proportion of the liquid crystal compound is 40% by mass or more and 70% by mass or less, and the proportion of the photopolymerizable compound is 30% by mass or more and 60% by mass or less. In addition, in the dimming layer 20, the proportion of the liquid crystal compound 22L in the transparent polymer layer 21 and the liquid crystal composition 22 is 40% by mass or more and 70% by mass or less, and the proportion of the transparent polymer layer 21 is 30% by mass or more and 60% by mass or less. According to the above-mentioned structure, the size of the microdomain 21D is appropriately ensured by the transparent polymer layer 21, and the structure of the polymer dispersed liquid crystal can be appropriately formed. As a result, good optical characteristics are obtained in the dimming film. That is, it is possible to suppress the situation where the microdomain 21D becomes too large and the scattering of light in the opaque state is reduced, the light component absorbed by the dichroic pigment 22P is reduced, and the situation where the microdomain 21D becomes too small and the freedom of movement of the liquid crystal compound 22L corresponding to the applied voltage is reduced.

[0123] (14) In the coating liquid for forming the dimming layer 20, the proportion of the dichroic pigment 22P is greater than 0.5% by mass and less than 10% by mass. In addition, in the dimming layer 20, the proportion of the dichroic pigment 22P in the transparent polymer layer 21 and the liquid crystal composition 22 is greater than 0.5% by mass and less than 10% by mass. By making the proportion of the dichroic pigment 22P greater than 0.5% by mass, the degree of polymerization promoted by using an oxime ester compound as a photopolymerization initiator becomes appropriate, and it is easy to clearly identify the difference in color between the dimming sheet in a transparent state and an opaque state. In addition, by making the proportion of the dichroic pigment 22P less than 10% by mass, the precipitation of particles formed by the aggregation of the dichroic pigment 22P can be suppressed.

[0124] (15) In the coating liquid for forming the light-adjusting layer 20, the proportion of the photopolymerization initiator is 0.1% by mass or more and 5% by mass or less. By setting the proportion of the photopolymerization initiator to 0.1% by mass or more, the polymerization reaction can be properly carried out. By setting the proportion of the photopolymerization initiator to 5% by mass or less, excessive promotion of the polymerization reaction can be suppressed, and the reduction in optical properties caused by the unreacted photopolymerization initiator remaining in the light-adjusting layer 20 can be suppressed.

[0125] (16) The total light transmittance of the light control sheet in the opaque state is 30% or less, and visible light can be sufficiently blocked in the opaque state.

[0126] (Example)

[0127] The dimming film described above is described using a specific embodiment.

[0128] <Analysis of the Relationship between Domain Diameter, Type of Photopolymerization Initiator, and Characteristics of the Dimming Sheet>

[0129] Dimming sheets of Examples and Comparative Examples were produced, and the relationship between the domain diameter and the type of photopolymerization initiator and the characteristics of the dimming sheets was analyzed.

[0130] [Example 1]

[0131] A liquid crystal compound, a dichroic pigment, a photopolymerizable compound, and a photopolymerization initiator are mixed to generate a coating liquid for forming a light-adjusting layer. The details of the materials are as follows. In addition, regarding the proportion of each material in the coating liquid, the liquid crystal compound is 52.1% by mass, the dichroic pigment is 4.0% by mass, the photopolymerizable compound is 42.4% by mass, and the photopolymerization initiator is 1.5% by mass.

[0132] Liquid crystal compounds: Cyanobiphenyl compounds

[0133] Dichroic dye: Black dichroic dye (YH-428, manufactured by Mitsui Chemicals Fine Co., Ltd.)

[0134] · Photopolymerizable compound (ultraviolet curable compound): a mixture of isobornyl acrylate, pentaerythritol triacrylate, and urethane acrylate

[0135] Photopolymerization initiator: Oxime ester compound (mixture of (E)-(8-{[(acetyloxy)imino][2-(2,2,3,3-tetrafluoropropoxy)phenyl]methyl}-11-(2-ethylhexyl)-11H-benzo[a]carbazole-5-yl)(2,4,6-trimethylphenyl)methanone and (Z)-(8-{[(acetyloxy)imino][2-(2,2,3,3-tetrafluoropropoxy)phenyl]methyl}-11-(2-ethylhexyl)-11H-benzo[a]carbazole-5-yl)(2,4,6-trimethylphenyl)methanone) (Irgacure OXE03, manufactured by BASF Japan)

[0136] The first transparent electrode layer is formed on the first transparent support layer by sputtering, and the first sheet as a laminate of the first transparent support layer and the first transparent electrode layer is produced. Similarly, the second transparent electrode layer is formed on the second transparent support layer by sputtering, and the second sheet as a laminate of the second transparent support layer and the second transparent electrode layer is produced. For each of the first transparent support layer and the second transparent support layer, the material is polyethylene terephthalate, and the thickness is 125 μm. For each of the first transparent electrode layer and the second transparent electrode layer, the material is indium tin oxide, and the thickness is 30 nm.

[0137] The coating solution is applied to the first sheet to form a coating film on the first transparent electrode layer, and the spacer is further dispersed in the coating film. As the spacer, black spherical particles made of polymethyl methacrylate are used. The particle size of the spacer is 25 μm. Then, the second sheet is attached to the first sheet with the coating film formed thereon by lamination processing to obtain a laminate of the first sheet, the coating film and the second sheet.

[0138] Next, the first transparent supporting layer of the stack was irradiated with ultraviolet rays of 365 nm to form a light-adjusting layer, thereby obtaining the light-adjusting sheet of Example 1. The intensity of the ultraviolet rays was 28 mW / cm 2 , the UV irradiation time is 120 seconds.

[0139] [Example 2]

[0140] Compared with Example 1, the photopolymerization initiator was changed to an α-aminoalkylphenone compound (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one) (Irgacure 907, manufactured by BASF Japan) and an acylphosphine oxide compound (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide) (Irgacure TPO, manufactured by BASF Japan). Regarding the proportion of each material in the coating liquid, the liquid crystal compound was 51.3% by mass, the dichroic dye was 4.0% by mass, the photopolymerizable compound was 41.7% by mass, the photopolymerization initiator Irgacure 907 was 1.5% by mass, and the photopolymerization initiator Irgacure TPO was 1.5% by mass. The intensity of ultraviolet light was 7.2 mW / cm 2 , the UV irradiation time is 120 seconds.

[0141] [Example 3]

[0142] Compared with Example 1, the intensity of ultraviolet light was changed to 7.2 mW / cm 2 The UV exposure time was 120 seconds.

[0143] [Example 4]

[0144] Compared with Example 1, the photopolymerization initiator was changed to an oxime ester compound (Irgacure OXE04, manufactured by BASF Japan). The ratio of each material in the coating liquid was the same as that in Example 1. The intensity of ultraviolet light was 7.2 mW / cm 2 , the UV irradiation time is 120 seconds.

[0145] [Example 5]

[0146] Compared with Example 1, the photopolymerization initiator was changed to an oxime ester compound (1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(O-benzoyloxime)) (Irgacure OXE01, manufactured by BASF Japan). The ratio of each material in the coating liquid was the same as that in Example 1. The intensity of ultraviolet light was 7.2 mW / cm 2 , the UV irradiation time is 120 seconds.

[0147] [Comparative Example 1]

[0148] Compared with Example 1, the photopolymerization initiator was changed to an acylphosphine oxide compound (diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide) (Irgacure TPO, manufactured by BASF Japan). The ratio of each material in the coating liquid was the same as that in Example 1. The intensity of ultraviolet light was 7.2 mW / cm 2 , the UV irradiation time is 120 seconds.

[0149] [Comparative Example 2]

[0150] Compared with Example 1, the photopolymerization initiator was changed to a benzyl ketal compound (2,2-dimethoxy-2-phenylacetophenone) (Irgacure 651, manufactured by BASF Japan). The ratio of each material in the coating liquid was the same as that in Example 1. The intensity of ultraviolet light was 7.2 mW / cm 2 , the UV irradiation time is 120 seconds.

[0151] [Comparative Example 3]

[0152] Compared with Example 1, the photopolymerization initiator was changed to an α-hydroxyalkylphenone compound (1-hydroxycyclohexylphenyl ketone) (Irgacure 184, manufactured by BASF Japan). The ratio of each material in the coating liquid was the same as that in Example 1. The intensity of ultraviolet light was 7.2 mW / cm 2 , the UV irradiation time is 120 seconds.

[0153] [Comparative Example 4]

[0154] Compared with Example 1, the photopolymerization initiator was changed to an α-hydroxyacetophenone compound (2-hydroxy-2-methylpropiophenone) (Irgacure 1173, manufactured by BASF Japan). The ratio of each material in the coating solution was the same as that in Example 1. The intensity of ultraviolet light was 7.2 mW / cm 2 , the UV irradiation time is 120 seconds.

[0155] [Comparative Example 5]

[0156] Compared with Example 1, the photopolymerization initiator was changed to an α-aminoalkylphenone compound (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one) (Irgacure 907, manufactured by BASF Japan). The ratio of each material in the coating liquid was the same as that in Example 1. The intensity of ultraviolet light was 7.2 mW / cm 2 , the UV irradiation time is 120 seconds.

[0157] [Evaluation method]

[0158] Determination of micro-area diameter

[0159] For each embodiment and each comparative example, a cross-sectional image along the thickness direction of the dimming sheet was obtained using a scanning electron microscope. The area of ​​each micro-region contained in the cross-sectional image was calculated using the image processing software ImageJ, and the diameter of a circle with the same area as the area of ​​the micro-region was taken as the micro-region diameter of the micro-region. Then, the average value of the micro-region diameters of the micro-regions contained in the cross-sectional image of each dimming sheet was taken as the micro-region diameter of the dimming sheet.

[0160] Determination of total light transmittance

[0161] For each of the Examples and Comparative Examples, the total light transmittance of the light control sheet in each of the opaque state and the transparent state was measured by a method based on JIS K 7361-1.

[0162] Determination of chromaticity

[0163] For each of the Examples and Comparative Examples, the chromaticity a* and the chromaticity b* of the light control sheet in each of the opaque state and the transparent state were measured by a method in accordance with JIS Z 8781-4.

[0164] Visual evaluation

[0165] For each Example and each Comparative Example, the transmittance ratio between the opaque state and the transparent state and the color tone were visually evaluated.

[0166] In the evaluation of the transmittance ratio, the contrast between the transparency of the dimming film in the opaque state and the transparent state is evaluated in three levels, and the case where the contrast is good is set to "○", the case where the contrast is worse than "○" but to an acceptable degree is set to "△", and the case where the contrast is poor to an unacceptable degree is set to "×".

[0167] In the evaluation of color tone, the case where no color tones other than achromatic colors from white to black are confirmed in the dimming sheet for either the opaque state or the transparent state is marked as "○", and the case where a color tones other than achromatic colors are confirmed in the dimming sheet for at least one of the opaque state and the transparent state is marked as "×".

[0168] [Evaluation results]

[0169] Table 1 shows the results of visual evaluation of microdomain diameter, total light transmittance TTb and chromaticity a*, chromaticity b* in an opaque state, total light transmittance TTa and chromaticity a*, chromaticity b*, ratio of TTa to TTb, transmittance ratio, and hue for each embodiment and each comparative example. The state where no driving voltage is applied is the opaque state, and the state where an AC voltage of 100V is applied as the driving voltage is the transparent state.

[0170]

[0171] As shown in Table 1, regarding the total light transmittance, in Examples 1 to 5 where the microdomain diameter is less than 0.7 μm, the ratio of TTa to TTb is 8.0 or more, and the visual evaluation is also good. In particular, it can be confirmed that the total light transmittance TTb in the opaque state is reduced compared to the comparative example. Referring to the total light transmittance of the embodiments and comparative examples, it is confirmed that as the microdomain diameter becomes smaller, the ratio of TTa to TTb tends to increase, and in particular, the ratio of TTa to TTb changes sharply with the microdomain diameter of about 1 μm as the boundary. Therefore, if the microdomain diameter is less than 0.7 μm, it can be said that a particularly good contrast can be obtained for the opaque state and the transparent state.

[0172] In addition, regarding the color tone, in Examples 1 to 5, in the transparent state, -6≤a*≤6 and -6≤b*≤6 were satisfied, and in the opaque state, -8≤a*≤8 and -8≤b*≤8 were satisfied. Moreover, in the visual evaluation, no color tone other than achromatic color was confirmed in the dimming sheet in either the opaque state or the transparent state. Therefore, in Examples 1 to 5, it can be said that the situation where the dimming sheet appears to be colored is appropriately suppressed.

[0173] Specifically, in Examples 1 and 3 to 5 using an oxime ester compound as a photopolymerization initiator, -3≤a*≤3 and -3≤b*≤3 were satisfied in a transparent state, and tones other than achromatic colors were significantly suppressed. Therefore, it was confirmed that by using an oxime ester compound as a photopolymerization initiator, the domain diameter can be reduced and the yellow color in a transparent state can be appropriately suppressed.

[0174] In addition, in Comparative Example 1, in which an acylphosphine oxide compound was used alone as a photopolymerization initiator, the domain diameter was small, but the yellow color in the transparent state was strong, compared with Comparative Examples 2 to 5, in which an alkylphenone compound was used alone as a photopolymerization initiator. In contrast, in Example 2, in which an acylphosphine oxide compound and an alkylphenone compound were mixed as photopolymerization initiators, b* in the transparent state was closer to 0 than in Comparative Example 1. That is, it was confirmed that the domain diameter could be reduced and the yellow color in the transparent state could be suppressed by using an acylphosphine oxide compound and an alkylphenone compound in combination.

[0175] <Analysis of the relationship between the type of photopolymerization initiator and the properties of the coating liquid and the characteristics of the dimming sheet>

[0176] A dimming sheet of a test example was produced, and the relationship between the type of photopolymerization initiator and the properties of the coating liquid and the characteristics of the dimming sheet was analyzed.

[0177] [Materials and manufacturing methods of dimming film]

[0178] A liquid crystal compound, a dichroic dye, a photopolymerizable compound, and a photopolymerization initiator are mixed to produce a coating liquid for forming a light-adjusting layer. The details of the materials are as follows.

[0179] Liquid crystal compounds: Cyanobiphenyl compounds

[0180] Dichroic dye: Black dichroic dye (YH-428, manufactured by Mitsui Chemicals Fine Co., Ltd.)

[0181] · Photopolymerizable compound (ultraviolet curable compound): a mixture of isobornyl acrylate, pentaerythritol triacrylate, and urethane acrylate

[0182] · Photopolymerization initiator: one or more of the following eight types

[0183] Photopolymerization initiator I1: oxime ester compound (1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(O-benzoyloxime)) (Irgacure OXE01, manufactured by BASF Japan Co., Ltd.)

[0184] Photopolymerization initiator I2: Oxime ester compound (a mixture of (E)-(8-{[(acetyloxy)imino][2-(2,2,3,3-tetrafluoropropoxy)phenyl]methyl}-11-(2-ethylhexyl)-11H-benzo[a]carbazole-5-yl)(2,4,6-trimethylphenyl)methanone and (Z)-(8-{[(acetyloxy)imino][2-(2,2,3,3-tetrafluoropropoxy)phenyl]methyl}-11-(2-ethylhexyl)-11H-benzo[a]carbazole-5-yl)(2,4,6-trimethylphenyl)methanone) (Irgacure OXE03, manufactured by BASF Japan)

[0185] Photopolymerization initiator I3: oxime ester compound (Irgacure OXE04, manufactured by BASF Japan)

[0186] Photopolymerization initiator I4: α-hydroxyalkylphenone compound (1-hydroxycyclohexylphenylketone) (Irgacure 184, manufactured by BASF Japan)

[0187] Photopolymerization initiator I5: acylphosphine oxide compound (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide) (Irgacure TPO, manufactured by BASF Japan)

[0188] Photopolymerization initiator I6: α-aminoalkylphenone compound (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one) (Irgacure 907, manufactured by BASF Japan Co., Ltd.)

[0189] Photopolymerization initiator I7: benzyl ketal compound (2,2-dimethoxy-2-phenylacetophenone) (Irgacure 651, manufactured by BASF Japan)

[0190] Photopolymerization initiator I8: α-hydroxyacetophenone compound (2-hydroxy-2-methylpropiophenone) (Irgacure 1173, manufactured by BASF Japan)

[0191] The first transparent electrode layer is formed on the first transparent support layer by sputtering, and the first sheet as a laminate of the first transparent support layer and the first transparent electrode layer is produced. Similarly, the second transparent electrode layer is formed on the second transparent support layer by sputtering, and the second sheet as a laminate of the second transparent support layer and the second transparent electrode layer is produced. For each of the first transparent support layer and the second transparent support layer, the material is polyethylene terephthalate, and the thickness is 125 μm. For each of the first transparent electrode layer and the second transparent electrode layer, the material is indium tin oxide, and the thickness is 30 nm.

[0192] The coating solution is applied to the first sheet by a drop casting method, thereby forming a coating film on the first transparent electrode layer, and then the spacer is dispersed in the coating film. The thickness of the coating film is 25 μm. As the spacer, spherical particles made of polymethyl methacrylate are used. The particle size of the spacer is 20 μm. Then, the second sheet is attached to the first sheet with the coating film formed thereon by lamination processing to obtain a laminate of the first sheet, the coating film and the second sheet.

[0193] Next, the first transparent support layer of the stack was irradiated with ultraviolet light of 365 nm to form a light-adjusting layer, thereby obtaining a light-adjusting sheet. The intensity of the ultraviolet light was 12 mW / cm 2 , the UV irradiation time is 120 seconds.

[0194] [Configuration of Test Example]

[0195] Using the above materials and manufacturing methods, the mixing ratio of the liquid crystal compound, the dichroic dye, the photopolymerizable compound and the photopolymerization initiator in the coating liquid was changed to obtain Test Examples 1 to 8 and 13 to 17. In addition, in Test Examples 1 to 6, 8, 13 to 17, a black spacer was used, and in Test Example 7, a white transparent spacer was used. Furthermore, the above Examples 1, 3, 4, and 5 were sequentially designated as Test Examples 9, 10, 11, and 12, and the above Example 2 and Comparative Examples 1, 2, 3, 4, and 5 were sequentially designated as Test Examples 18, 19, 20, 21, 22, and 23. The mixing ratio of the coating liquid and the color of the spacer in the test examples are shown in Tables 2 and 3.

[0196]

[0197]

[0198] [Characteristics evaluation]

[0199] The following characteristics were measured and evaluated for the coating liquid and the dimming sheet of each test example.

[0200] The lower limit temperature of the isotropic phase of the coating liquid

[0201] The coating liquid of each test example was gradually cooled from a temperature indicating an isotropic phase, and the temperature at which the liquid crystal component began to precipitate was measured, and this temperature was taken as the lower limit temperature of the isotropic phase (ISO temperature). The ISO temperature of each test example is shown in Tables 2 and 3.

[0202] Haze in transparent state

[0203] An AC voltage of 100 V was applied as a driving voltage to the dimming sheet of each test example to make it transparent, and the haze in the transparent state was measured using a haze meter (NDH2000, manufactured by Nippon Denshoku Co., Ltd.). The haze was measured in accordance with JIS K 7136.

[0204] The evaluation results of the haze in the transparent state are shown in Tables 2 and 3. In the evaluation, a case where the haze was 10% or less was rated as "○", and a case where the haze exceeded 10% was rated as "×".

[0205] Total light transmittance in opaque state

[0206] For each test example, the total light transmittance in the light control sheet in an opaque state to which no driving voltage was applied was measured by a method in accordance with JIS K 7361-1. The measurement results are shown in Tables 2 and 3.

[0207] Uneven coating

[0208] For each test example, during the manufacturing process of the dimming sheet, the presence or absence of stripe-shaped unevenness on the surface of the coating film was visually observed. The unevenness is caused by the precipitation of liquid crystal components on the surface of the coating film. The case where no unevenness occurs is marked as "○", and the case where unevenness occurs is marked as "×", and the observation results are shown in Tables 2 and 3.

[0209] NI temperature

[0210] For each test example, the NI temperature of the liquid crystal composition constituting the dimming layer after formation was measured. The NI temperature of the measured liquid crystal composition was compared with the NI temperature of the liquid crystal compound alone, and the difference (NI temperature difference) was calculated. The evaluation results of the NI temperature are shown in Tables 2 and 3. In the evaluation, the case where the NI temperature difference is within 20°C is set as "○", the case where the NI temperature difference exceeds 20°C and is within 25°C is set as "△", and the case where the NI temperature difference exceeds 25°C is set as "×".

[0211] [Evaluation results]

[0212] As shown in Tables 2 and 3, in Test Examples 13, 14, and 17 to 23 in which the photopolymerization initiator does not contain an oxime ester compound, the NI temperature of the liquid crystal composition constituting the light-adjusting layer is significantly lower than the NI temperature of the liquid crystal compound alone, and the difference exceeds 25° C. In Test Examples 13, 14, and 17 to 23, it is believed that since the oxime ester compound is not contained, the polymerization reaction is difficult to proceed, and the unreacted photopolymerizable compound in the liquid crystal composition of the light-adjusting layer increases, resulting in a significant decrease in the NI temperature of the liquid crystal composition.

[0213] In contrast, in Test Examples 1 to 12 in which the photopolymerization initiator contained an oxime ester compound, the difference between the NI temperature of the liquid crystal composition constituting the light-adjusting layer and the NI temperature of the liquid crystal compound alone was within 25° C. That is, it is suggested that by using an oxime ester compound as a photopolymerization initiator, the polymerization reaction is initiated with high sensitivity to light energy, and the amount of unreacted photopolymerizable compound remaining in the liquid crystal composition of the light-adjusting layer is reduced, resulting in the suppression of a decrease in the NI temperature.

[0214] In addition, in the test examples in which the photopolymerization initiator does not contain an oxime ester compound, a tendency for the total light transmittance in the opaque state to be larger than that in the test examples in which the photopolymerization initiator contains an oxime ester compound is confirmed. It is believed that when the photopolymerization initiator does not contain an oxime ester compound, the polymerization reaction is difficult to proceed, so the microdomains divided in the transparent polymer layer tend to become larger, and as a result, the scattering of light in the opaque state is reduced, and the component of light absorbed by the dichroic pigment is reduced.

[0215] In Test Example 15, the proportion of the liquid crystal compound in the coating liquid exceeds 70% by mass, and the lower limit temperature of the isotropic phase of the coating liquid exceeds 40°C. That is, the coating liquid of Test Example 15 is an anisotropic liquid when the coating film is formed, and the liquid crystal component is easy to precipitate on the surface of the coating film. Therefore, it is believed that unevenness is generated on the surface of the coating film and it is difficult to obtain a uniform surface of the dimming layer. In addition, due to the large proportion of the liquid crystal compound, the micro-regions divided in the transparent polymer layer are easy to become larger, and it is believed that the total light transmittance in the opaque state in Test Example 15 is also slightly larger.

[0216] In Test Example 16, the proportion of the liquid crystal compound in the coating liquid was less than 40% by mass, and the lower limit temperature of the isotropic phase of the coating liquid was less than 0° C. In Test Example 16, optical properties such as haze in a transparent state and total light transmittance in an opaque state were reduced. In Test Example 16, since the proportion of the liquid crystal compound was small, the microdomains divided in the transparent polymer layer tended to become smaller, and as a result, it is believed that the freedom of movement of the liquid crystal compound corresponding to the applied voltage was reduced, so that the NI temperature was reduced and the optical properties were reduced.

[0217] Compared with Test Examples 15 and 16, in Test Examples 1 to 14 and 17 to 23, the proportion of the liquid crystal compound in the coating liquid was 40% by mass or more and 70% by mass or less, and the lower limit temperature of the isotropic phase of the coating liquid was 0° C. or more and less than 30° C. Therefore, in Test Examples 1 to 14 and 17 to 23, the coating film was an isotropic liquid when the coating film was formed, so the unevenness of the coating film surface was suppressed. In addition, in Test Examples 1 to 12, since microdomains of appropriate size were formed in the transparent polymer layer, good optical properties were obtained.

[0218] Comparing Test Examples 1 to 3, it was confirmed that the lower limit temperature of the isotropic phase of the coating liquid increased as the proportion of the liquid crystal compound increased, and the total light transmittance in the opaque state tended to increase. In addition, when comparing Test Examples 1, 5, and 6, it was confirmed that the total light transmittance in the opaque state tended to decrease as the proportion of the dichroic dye increased. In addition, when comparing Test Examples 1 and 7, it was found that when a black spacer of the same color as the dichroic dye was used, the total light transmittance in the opaque state became smaller.

[0219] In addition, in Test Example 8, the difference between the NI temperature of the liquid crystal composition constituting the light-adjusting layer and the NI temperature of the liquid crystal compound alone is slightly larger than that of Test Examples 1 to 7. In Test Example 8, the ratio of the dichroic pigment is less than 0.5% by mass, that is, the content of the dichroic pigment is significantly less than that of other test examples, so the absorption of light energy by the dichroic pigment in the polymerization process is small. Therefore, it is believed that the sensitivity of the photopolymerization initiator as an oxime ester compound becomes excessive and the polymerization reaction becomes easy to proceed excessively, so the micro-domains divided in the transparent polymer layer tend to become smaller, resulting in a decrease in the NI temperature.

[0220] In this way, the sensitivity of the oxime ester compound as a photopolymerization initiator is easily excessive when the liquid crystal composition does not contain a dichroic pigment, or the dichroic pigment in the liquid crystal composition contains a small amount. If the ratio of the dichroic pigment is more than 0.5% by mass, it is easy to obtain the effect of the appropriate conduction of the polymerization reaction based on the use of the oxime ester compound as a photopolymerization initiator and the phase separation of the liquid crystal composition.

Claims

1. A dimming film, comprising: A dimming layer comprising a transparent polymer layer and a liquid crystal composition, wherein the transparent polymer layer comprises a plurality of microdomains, and the liquid crystal composition fills the microdomains and comprises a liquid crystal compound and a dichroic pigment; and a pair of transparent electrode layers, which sandwich the dimming layer, in, The orientation of the liquid crystal compound and the dichroic dye is changed according to the change of the potential difference between the pair of transparent electrode layers, thereby switching from a colored opaque state to a transparent state. The average diameter of the micro-domain is less than 0.7 μm.

2. The dimming sheet according to claim 1, wherein: The chromaticity b* of the dimming film in the transparent state with respect to the CIE1976 (L*a*b*) colorimetric system satisfies -6≤b*≤6.

3. The dimming sheet according to claim 1 or 2, wherein: The transparent polymer layer comprises a polymer compound, wherein the polymer compound has a terminal end. The plurality of terminals in the transparent polymer layer include one or more selected from the group consisting of an intramolecular dissociative group of an oxime ester compound, an intramolecular dissociative group of an alkylphenone compound, and an intramolecular dissociative group of an acylphosphine oxide compound.

4. The dimming sheet according to claim 3, wherein: The plurality of terminals in the transparent polymer layer include intramolecular dissociative groups of an oxime ester compound.

5. The dimming sheet according to claim 3, wherein: The plurality of terminals in the transparent polymer layer include an intramolecular dissociative group of an alkylphenone compound and an intramolecular dissociative group of an acylphosphine oxide compound.

6. The dimming sheet according to claim 5, wherein: The alkylphenone compound is an α-aminoalkylphenone compound.

7. The dimming sheet according to any one of claims 1 to 3, wherein: The ratio of the liquid crystal compound in the transparent polymer layer and the liquid crystal composition is 40% by mass or more and 70% by mass or less, The transparent polymer layer includes a polymer compound including an intramolecular dissociative group of an oxime ester compound at a terminal of the molecular structure.

8. The dimming sheet according to claim 7, wherein: The polymer compound has a skeleton derived from (meth)acrylate.

9. The dimming sheet according to any one of claims 1 to 8, wherein: The chromaticity b* of the dimming film in the opaque state with respect to the CIE1976 (L*a*b*) colorimetric system satisfies -8≤b*≤8.

10. The dimming sheet according to any one of claims 1 to 9, wherein: A ratio of a total light transmittance of the dimming sheet in the transparent state to a total light transmittance of the dimming sheet in the opaque state is greater than 8.

0.

11. The dimming sheet according to any one of claims 1 to 10, wherein: The total light transmittance in the opaque state is less than 30%.

12. The dimming sheet according to any one of claims 1 to 11, wherein: The ratio of the dichroic dye in the transparent polymer layer and the liquid crystal composition is 0.5 mass % or more and 10 mass % or less.

13. The dimming sheet according to any one of claims 1 to 12, wherein: The ratio of the transparent polymer layer to the transparent polymer layer in the liquid crystal composition is 30 mass % or more and 60 mass % or less.

14. The dimming sheet according to any one of claims 1 to 13, wherein: The light-adjusting layer further includes a spacer that presents the same color as the color presented by the dichroic pigment in the opaque state.

15. A dimming film, comprising: A dimming layer comprising a transparent polymer layer and a liquid crystal composition, wherein the transparent polymer layer comprises a plurality of microdomains, and the liquid crystal composition fills the microdomains and comprises a liquid crystal compound and a dichroic pigment; and a pair of transparent electrode layers, which sandwich the dimming layer, The orientation of the liquid crystal compound and the dichroic dye is changed according to the change of the potential difference between the pair of transparent electrode layers, thereby switching from a transparent state to a colored opaque state. in, The ratio of the liquid crystal compound in the transparent polymer layer and the liquid crystal composition is 40% by mass or more and 70% by mass or less, The transparent polymer layer includes a polymer compound including an intramolecular dissociative group of an oxime ester compound at a terminal of the molecular structure.

16. A method for manufacturing a dimming film, comprising the following steps: generating a coating liquid including a liquid crystal composition containing a liquid crystal compound and a dichroic pigment, a photopolymerizable compound, and a photopolymerization initiator; forming a coating film composed of the coating liquid between a first sheet having a first transparent electrode layer formed on a first transparent supporting layer and a second sheet having a second transparent electrode layer formed on a second transparent supporting layer; The coating film is irradiated with light to cause a polymerization reaction of the photopolymerizable compound to proceed, thereby forming a light-adjusting layer having a transparent polymer layer including a plurality of microdomains and the liquid crystal composition filling the microdomains. Wherein, the photopolymerization initiator comprises an oxime ester compound, The lower limit temperature of the isotropic phase of the coating liquid is 0°C or higher and lower than 30°C.

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