Anthraquinone derivatives, dye compositions, and photochromic sheets

Abstract

The present invention provides anthraquinone derivatives, dye compositions, and light-adjusting sheets that can enhance the two-color ratio and solubility in liquid crystals. [Solution] An anthraquinone derivative represented by the following formula (1). JPEG0007865447000019.jpg27169 In formula (1), X and Y are each independently alkyl groups, and at least one of X and Y is a branched alkyl group.

Description

[Technical Field]

[0001] This disclosure relates to anthraquinone derivatives, dye compositions, and photochromic sheets. [Background technology]

[0002] Development of dichroic dyes used in liquid crystal elements such as liquid crystal displays and dimming sheets is progressing. In particular, anthraquinone derivatives, which are compounds with an anthraquinone skeleton, tend to exhibit high resistance to light, heat, and temperature, and are therefore expected to be used not only in indoor applications but also in automotive liquid crystal elements. For this reason, a great deal of research has been conducted on the structure and properties of anthraquinone derivatives (see, for example, Patent Documents 1-3). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2008-106200 [Patent Document 2] Japanese Patent Publication No. 2018-154704 [Patent Document 3] International Publication No. 2023 / 100848 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In dichroic dyes, the dichroic ratio and solubility in liquid crystals are important properties. In particular, improving the dichroic ratio of magenta-based dichroic dyes with absorption maximum wavelengths in the wavelength range of 470 nm to 600 nm has a significant impact on brightness and is therefore effective in improving the contrast of liquid crystal elements. However, magenta-based dichroic dyes reported to date have not adequately combined both dichroic ratio and solubility in liquid crystals. [Means for solving the problem]

[0005] This paper describes embodiments of anthraquinone derivatives, dye compositions, and photochromic sheets for solving the above problems. [Aspect 1] An anthraquinone derivative represented by the following formula (1).

[0006] [ka]

[0007] In formula (1), X and Y are each independently alkyl groups, and at least one of X and Y is a branched alkyl group. According to the above configuration, both a high dichroic ratio and high solubility in liquid crystals can be obtained in magenta-based dichroic dyes. Furthermore, high solubility in monomers can also be obtained.

[0008] [Aspect 2] The anthraquinone derivative according to [Aspect 1], wherein in formula (1), X and Y are each independently a branched alkyl group. According to the above configuration, branching in the molecular structure increases, making it easier to suppress the aggregation of anthraquinone derivatives.

[0009] [Aspect 3] The anthraquinone derivative according to [Aspect 1] or [Aspect 2], wherein in formula (1), X and Y are each independently alkyl groups, and at least one of X and Y is a branched alkyl group represented by the following formula (2), wherein in the following formula (2), n is an integer of 1 or more, and m and l are each independently integers of 1 or more and 6 or less. -C n H 2n-1 (C m H 2m+1 )C l H 2l+1 ...(2) According to the above configuration, high solubility for liquid crystals and monomers can be obtained.

[0010] [Aspect 4] In the formula (1), X and Y are different alkyl groups from each other, and at least one of X and Y is a branched alkyl group. The anthraquinone derivative according to any one of [Aspect 1] to [Aspect 3].

[0011] According to the above configuration, even when the device using the anthraquinone derivative is stored for a long time, precipitation of the anthraquinone derivative can be suppressed. Also, the solubility in each of the liquid crystal and the monomer is increased.

[0012] [Aspect 5] A dye composition containing the anthraquinone derivative according to any one of [Aspect 1] to [Aspect 4] and a liquid crystal compound. According to the above configuration, since an anthraquinone derivative having a high dichroic ratio and high solubility in a liquid crystal is used, the dye composition can be suitably used for a liquid crystal device.

[0013] [Aspect 6] A dye composition containing the anthraquinone derivative according to any one of [Aspect 1] to [Aspect 4], a liquid crystal compound, and a polymerizable compound. According to the above configuration, since an anthraquinone derivative having a high dichroic ratio and high solubility in a liquid crystal and a monomer is used, the dye composition can be suitably used for the production of a liquid crystal device provided with a liquid crystal layer including a transparent polymer layer.

[0014] [Aspect 7] A dimming sheet including a dimming layer containing the anthraquinone derivative and a liquid crystal compound according to any one of [Aspect 1] to [Aspect 4], and a pair of transparent electrode layers sandwiching the dimming layer.

[0015] According to the above configuration, since an anthraquinone derivative having a high dichroic ratio and high solubility in a liquid crystal is used, suitable production of the dimming sheet is possible and characteristics such as contrast are also enhanced.

[0016] [Aspect 8] The light-adjusting sheet according to [Aspect 7], wherein the light-adjusting layer comprises a transparent polymer layer containing a plurality of voids, and a liquid crystal composition held in the voids, the liquid crystal composition containing the anthraquinone derivative and the liquid crystal compound.

[0017] According to the above configuration, since an anthraquinone derivative having a high dichromatic ratio and high solubility in liquid crystals and monomers is used, suitable manufacturing of dimmable sheets is possible, and properties such as contrast can also be enhanced. [Effects of the Invention]

[0018] According to this disclosure, the dichroic ratio and solubility in liquid crystals can be improved in magenta-based dichroic dyes. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 shows the structure of a dimming sheet according to one embodiment. [Figure 2] Figure 2 is a table showing the structures and evaluation results of the anthraquinone derivatives of Examples 1 to 6. [Figure 3] Figure 3 is a table showing the structures and evaluation results of the anthraquinone derivatives of Examples 7-8 and Comparative Examples 1-4. [Modes for carrying out the invention]

[0020] The following describes one embodiment of an anthraquinone derivative, a dye composition, and a photochromic sheet. An anthraquinone derivative is a compound having a 9,10-anthraquinone skeleton. In addition, at the substitution sites of the anthraquinone skeleton, positions 1, 4, 5, and 8 are α-positions, and positions 2, 3, 6, and 7 are β-positions.

[0021] [Anthraquinone derivatives] The anthraquinone derivative of this embodiment is a compound represented by the following formula (1).

[0022] [ka]

[0023] In formula (1), X and Y are each independently alkyl groups, and at least one of X and Y is a branched alkyl group. The branched alkyl group preferably has 3 to 15 carbon atoms. If only one of X and Y is a branched alkyl group, the other X and Y is preferably a linear alkyl group. The linear alkyl group preferably has 1 to 10 carbon atoms.

[0024] In the anthraquinone derivative of this embodiment, the alkyl chains branch around the ends of the molecular structure, making it difficult for molecules to come into close proximity to each other. Therefore, aggregation of the anthraquinone derivative is suppressed, and the solubility of the anthraquinone derivative in liquid crystal is improved. Furthermore, in the anthraquinone derivative of this embodiment, an absorption maximum wavelength is obtained in the wavelength range of 470 nm to 600 nm. Therefore, it can be used as a magenta-based dye.

[0025] In anthraquinone derivatives, the absorption wavelength changes depending on the introduction of electron-withdrawing or electron-donating groups to the anthraquinone skeleton. Therefore, when attempting to improve solubility while obtaining a desired absorption wavelength, it is important to carefully consider the type and position of the substituents to be introduced.

[0026] In cases where numerous substituents are bonded to the anthraquinone skeleton, such as in cyanide-based anthraquinone derivatives, there is a high degree of freedom in structural improvement because there are many substituents that can be modified to improve solubility. On the other hand, in magenta-based anthraquinone derivatives, as in this embodiment, the number of substituents bonded to the anthraquinone skeleton is smaller compared to cyanide-based derivatives, thus greatly limiting structural improvement. Against this backdrop, the inventors of the present invention have found an anthraquinone derivative that can improve solubility in liquid crystals while maintaining the magenta-based absorption wavelength by examining the structure of substituents located far from the anthraquinone skeleton, which have little effect on the absorption wavelength.

[0027] Furthermore, for improving the dichroism ratio, it is advantageous that the orientation of the dichroic dye can easily follow the orientation of the liquid crystal. Generally, an increase in the steric bulk of the dichroic dye molecule leads to an increase in steric repulsion with the liquid crystal molecule, which reduces the ability of the dichroic dye orientation to follow the liquid crystal and is therefore unfavorable for improving the dichroism ratio. However, in the case of the anthraquinone derivative of this embodiment, a substituent is introduced that has enough flexibility to keep the steric repulsion with the liquid crystal molecule within an acceptable range, even while increasing the bulk, thus enabling the expression of a high dichroism ratio.

[0028] Therefore, the anthraquinone derivative of this embodiment provides a high dichroism ratio and high solubility in liquid crystals in magenta-based dichroic dyes. For use as a magenta-based dye, the absorption maximum wavelength is preferably 470 nm to 560 nm, and for use as a dichroic dye, the dichroism ratio is preferably 7 or higher. With the anthraquinone derivative of this embodiment, high solubility in liquid crystals can be obtained along with these absorption maximum wavelengths and dichroism ratios. The dichroism ratio is the ratio of the absorbance of polarization parallel to the long axis of the dichroic dye to the absorbance of polarization perpendicular to the long axis.

[0029] Another method to increase solubility in liquid crystals is to introduce substituents containing structures that frequently appear as partial structures of liquid crystal molecules, such as fluorine-containing functional groups or cyclohexane rings, into the dichroic dye molecule, thereby increasing the affinity between the liquid crystal and the dichroic dye.

[0030] On the other hand, in this embodiment, by focusing on suppressing the aggregation of dichroic dye molecules and introducing a branched alkyl group, we discovered an anthraquinone derivative that exhibits high solubility in liquid crystals from a different perspective than the affinity between liquid crystals and dichroic dyes.

[0031] The anthraquinone derivatives of this embodiment can be synthesized more easily compared to cases where fluorine-containing functional groups or cyclohexane rings are introduced. Furthermore, since the anthraquinone derivatives do not contain fluorine, even if regulations on organofluorine compounds are strengthened due to concerns about their impact on human health and the environment, anthraquinone derivatives can avoid being subject to such regulations.

[0032] Furthermore, when a dichroic dye is a mixture of stereoisomers, such as when a cyclohexane ring is introduced, there is a concern that the properties will not be stable because the ratio of isomers will change with each synthesis, as the ratio of isomers will vary depending on the isomer ratio. In contrast, the anthraquinone derivative of this embodiment is not a mixture of isomers, so stable properties are more easily obtained.

[0033] Furthermore, suppressing the aggregation of dichroic dye molecules to improve solubility is effective not only for liquid crystals but also for monomers. Furthermore, in the anthraquinone derivative of this embodiment, the substituent at the α-position of the anthraquinone skeleton is -NH2. With this structure, higher solubility in liquid crystals can be obtained compared to conventional anthraquinone derivatives where the substituent at the α-position is -OH, and good solubility in monomers can also be obtained.

[0034] Generally, monomers have a lower structural affinity for anthraquinone derivatives than liquid crystals. Therefore, even anthraquinone derivatives that are highly soluble in liquid crystals may have insufficient solubility in monomers. In contrast, anthraquinone derivatives with an α-substituted -NH2 molecule have more potential hydrogen bonding sites with the monomer compared to those with an α-substituted -OH molecule, resulting in higher solubility in monomers. Consequently, they can be suitably used in liquid crystal elements manufactured from a mixture of liquid crystal, monomer, and dichroic dye, such as in dimmable sheets.

[0035] The structure of the branched alkyl group, which is at least one of X and Y in formula (1) above, will be explained further. The branched point of the branched alkyl group is one, and the branched alkyl group preferably has one side chain. With such a structure, the compound used for the synthesis of the anthraquinone derivative can be easily obtained, and the load required for the synthesis can be reduced. In addition, it is possible to suppress an excessive increase in the bulkiness of the molecule. The branched alkyl group is represented by the general formula of the following formula (2). In the following formula (2), n, m, and l are each independently an integer of 1 or more. -C n H 2n-1 (C m H 2m+1 )C l H 2l+1 ···(2)

[0036] In the above formula (2), n is preferably an integer of 1 or more and 5 or less. With such a structure, within a preferable carbon number range, it is easy to obtain a high effect of suppressing the aggregation of molecules by lengthening the alkyl chain from the branch. From the viewpoint of further enhancing such an effect, n is preferably 1. That is, the first carbon atom bonded to the oxygen atom is the carbon atom at the branched point, and it is preferable that two carbon atoms are bonded to the first carbon.

[0037] In the above formula (2), m and l are each independently preferably an integer of 1 or more and 6 or less. That is, for the alkyl chain bonded to the carbon atom at the branched point, the carbon number of the alkyl chain including the terminal of the molecule is preferably 1 or more and 6 or less. According to such a structure, it is possible to suppress an excessive increase in the bulkiness of the branched alkyl group.

[0038] For example, in the above formula (2), when n is 1 and m and l are equal, the branched alkyl group is represented by the general formula of -CH(C m H 2m+1 )2. With such a structure, the compound used for the synthesis of the anthraquinone derivative can be easily obtained, and the load required for the synthesis can be reduced.

[0039] Furthermore, in the anthraquinone derivative of this embodiment, it is preferable that X and Y in formula (1) are independently branched alkyl groups. With this structure, compared to the case where only one of X or Y is a branched alkyl group, the branching structure increases, making it easier to suppress the aggregation of the anthraquinone derivative.

[0040] Furthermore, in the anthraquinone derivative of this embodiment, it is preferable that X and Y in formula (1) above are different from each other. With such a structure, the molecular structure is asymmetric, which suppresses high crystallinity of the anthraquinone derivative. High crystallinity makes it difficult for the aggregate structure of the anthraquinone derivative molecules to be dissolved in liquid, so lower crystallinity results in higher solubility of the anthraquinone derivative in both liquid crystals and monomers. Therefore, in a structure where X and Y are different from each other, the solubility in both liquid crystals and monomers is higher compared to a structure where X and Y are the same. In addition, lower crystallinity suppresses the precipitation of the anthraquinone derivative even when liquid crystal elements using the anthraquinone derivative are stored for a long period of time, thus improving the reliability of the liquid crystal elements.

[0041] The anthraquinone derivatives of this embodiment can be produced, for example, by introducing each substituent to the anthraquinone skeleton using 1,5-diaminoanthraquinone as a starting material. Known methods can be used for the introduction of substituents. For example, the desired substituent can be introduced by substituent exchange to an intermediate in which the 2,6 positions of 1,5-diaminoanthraquinone are iodized.

[0042] [Pigment composition] The dye composition of this embodiment is a composition containing a dichroic dye which is an anthraquinone derivative as described above. Specific examples of the dye composition are a liquid crystal composition or a monomer composition.

[0043] The liquid crystal composition comprises a dichroic dye, which is an anthraquinone derivative as described above, and a liquid crystal compound. The liquid crystal composition is used in the liquid crystal layer of liquid crystal elements such as liquid crystal display devices and dimming sheets. The monomer composition comprises a dichroic dye, which is an anthraquinone derivative as described above, a liquid crystal compound, and a polymerizable compound. That is, the monomer composition may be a mixture of the liquid crystal composition and the polymerizable compound. The monomer composition is used to manufacture a liquid crystal layer having a structure in which liquid crystals are dispersed within a polymer layer. An example of a liquid crystal element having such a liquid crystal layer is a light-adjustable sheet.

[0044] The liquid crystal compounds included in the liquid crystal composition preferably have a cyclic structure and side chains such as alkyl chains in their molecular structure. Furthermore, it is preferable that the liquid crystal composition contains multiple types of liquid crystal compounds. In order to achieve rapid switching of liquid crystal orientation in a liquid crystal element under typical operating conditions, it is preferable that the liquid crystal components included in the liquid crystal composition exhibit a nematic phase in a temperature range of -30°C to 130°C.

[0045] In order to exhibit the nematic phase within the above temperature range, the number of cyclic structures in the liquid crystal compound is preferably 2 to 4, and the number of carbon atoms in the alkyl side chains of the liquid crystal compound is preferably 1 to 7. The anthraquinone derivative of this embodiment has high solubility in liquid crystals composed of liquid crystal compounds with such structures.

[0046] Examples of liquid crystal compounds included in liquid crystal compositions include 4'-ethoxybenzylidene-4-butylaniline, 4-cyano-4'-pentylbiphenyl, 4-cyano-4''-pentyl-p-terphenyl, 4-aminophenyl aminobenzoate, 1,2-diphenylacetylene, 4-[trans-4-[(E)-1-propenyl]cyclohexyl]benzonitrile, 4-cyano-4'-pentylbiphenylcyclohexane, 4-fluoro-4'-(trans-4-propylcyclohexyl)biphenyl, and 1-fluoro-4-[4-(4-pentylcyclohexyl)phenyl]benzene.

[0047] The liquid crystal composition may contain liquid crystal compounds that include a structure in which two or more benzene rings are bonded. For example, the liquid crystal composition may contain a biphenyl-based liquid crystal compound. Furthermore, among the multiple types of liquid crystal compounds contained in the liquid crystal composition, the liquid crystal compound containing a structure in which two or more benzene rings are bonded may have the largest mass proportion. For example, the liquid crystal composition may contain a biphenyl-based liquid crystal as its main component. The main component is the liquid crystal compound that has the largest mass proportion among the liquid crystal compounds contained in the liquid crystal composition. Because liquid crystal compounds containing a structure in which two or more benzene rings are bonded have a high structural affinity with the anthraquinone derivative of this embodiment, the anthraquinone derivative of this embodiment has high solubility in liquid crystal compositions containing liquid crystal compounds of such a structure.

[0048] The liquid crystal composition may contain at least one of a liquid crystal compound having one benzene ring and a liquid crystal compound not having a benzene ring. For example, the liquid crystal composition may contain at least one of a monophenyl liquid crystal compound and a bicyclohexane-based liquid crystal compound. Furthermore, the largest mass proportion of the liquid crystal compounds in the liquid crystal composition may be the liquid crystal compound having one benzene ring and the liquid crystal compound not having a benzene ring. The anthraquinone derivative of this embodiment has good solubility even in liquid crystal compositions containing liquid crystal compounds of this structure.

[0049] The polymerizable compound contained in the monomer composition is preferably an ultraviolet-curable compound having a polymerizable functional group in its molecular structure. The polymerizable compound is preferably at least one selected from the group consisting of (meth)acrylates, thiols, and oligomers of each of these compounds. The (meth)acrylate is preferably at least one selected from the group consisting of monofunctional, difunctional, trifunctional, and tetrafunctional (meth)acrylates. The anthraquinone derivative of this embodiment has high solubility in liquids consisting of polymerizable compounds of such structures. Note that "(meth)acrylate" is a general term for acrylates and methacrylates.

[0050] Examples of (meth)acrylates contained in monomer compositions include methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, isobolonyl acrylate, methoxypolyethylene glycol acrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, neopentyl glycol hydroxypivalate diacrylate, 3-[2,2-dimethyl-3-[[1-oxo-6-(propenoyloxy)hexyl]oxy]propoxy]-2,2-dimethyl-3-oxopropyl 6-(propenoyloxy)hexanoate, trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, and the like. Examples of thiols contained in monomer compositions include 1,3-propanedithiol and 1,6-hexanedithiol.

[0051] The monomer composition may contain a (meth)acrylate having a first structure in which a saturated hydrocarbon group with 6 or fewer carbon atoms is bonded to a (meth)acryloyloxy group, and the mass proportion of the (meth)acrylate having the first structure may be the largest among the polymerizable compounds contained in the monomer composition. Because the molecular size of the (meth)acrylate having the first structure is not too large, it easily fits between the molecules of the anthraquinone derivative. Therefore, the anthraquinone derivative of this embodiment has good solubility in the monomer composition containing the (meth)acrylate having the first structure. Examples of (meth)acrylate having the first structure are ethyl acrylate and cyclohexyl acrylate.

[0052] Furthermore, the monomer composition may contain a (meth)acrylate having a second structure in which a chain-like saturated hydrocarbon group with 5 or fewer carbon atoms is bonded to a (meth)acryloyloxy group, and the mass proportion of the (meth)acrylate having the second structure may be the largest among the polymerizable compounds contained in the monomer composition. The molecular size of the (meth)acrylate having the second structure is smaller than that of the (meth)acrylate containing a cyclic saturated hydrocarbon group. Therefore, the anthraquinone derivative of this embodiment has high solubility in monomer compositions containing the (meth)acrylate having the second structure. An example of a (meth)acrylate having the second structure is ethyl acrylate.

[0053] The monomer composition may further contain one or more polymerization initiators. Examples of polymerization initiators include diketone compounds, acetophenone compounds, benzoin compounds, benzophenone compounds, thioxanthone compounds, and the like.

[0054] The dye composition may contain other dichroic dyes in addition to the anthraquinone derivative of this embodiment. Preferably, the content of dichroic dyes, including the anthraquinone derivative of this embodiment, in the dye composition is 0.5% by mass or more and 10% by mass or less. Within this range, good solubility of the anthraquinone derivative is possible. The dye composition may also contain various additives.

[0055] [Dimmable sheet] Referring to Figure 1, the configuration of the dimming sheet of this embodiment will be described. As shown in Figure 1, the dimming sheet 10 comprises a dimming layer 20, which is an example of a liquid crystal layer, 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. The second transparent support layer 42 supports the second transparent electrode layer 32 on the side opposite to the dimming layer 20.

[0056] The light-adjusting layer 20 comprises a transparent polymer layer and the liquid crystal composition described above, and is formed from the monomer composition described above. That is, the transparent polymer layer is a polymer of the polymerizable compound contained in the monomer composition. The transparent polymer layer has a plurality of voids, and the liquid crystal composition fills these voids. The shape of the voids is spherical, ellipsoidal, or irregular.

[0057] The structure for holding the liquid crystal composition in the dimming layer 20 is either a polymer network type or a polymer dispersion type. The polymer network type dimming layer 20 comprises a polymer network having a three-dimensional mesh structure. The polymer network is an example of a transparent polymer layer, and the liquid crystal composition is held in the interconnected voids of the polymer network. The polymer dispersion type dimming layer 20 comprises a transparent polymer layer that partitions a number of isolated voids, and the liquid crystal composition is held in the voids dispersed in the transparent polymer layer.

[0058] The dielectric anisotropy of the liquid crystal compound contained in the liquid crystal composition is, for example, positive. The dichroic dye is oriented using a guest-host method with the liquid crystal compound as the host, and exhibits a predetermined color when its long axis is substantially perpendicular to the direction of incident light. In addition to the liquid crystal compound and dichroic dye, the liquid crystal composition may also contain viscosity reducers, defoamers, antioxidants, weather stabilizers, etc. Examples of weather stabilizers include ultraviolet absorbers and light stabilizers.

[0059] Furthermore, the light-adjusting layer 20 may include spacers dispersed throughout the transparent polymer layer. The spacers uniformize the thickness of the light-adjusting layer 20 by defining its thickness around the spacers. The spacers may be bead spacers or photospacers formed by exposure and development of the photoresist, as long as they are light-transmitting.

[0060] The spacer may be colorless and transparent, or colored and transparent. Preferably, the spacer is colored and transparent, and the color exhibited by the spacer is the same as the color exhibited by the dichroic dye of the light-adjusting layer 20, that is, the color of the opaque light-adjusting sheet 10. For example, the liquid crystal composition contains multiple types of dichroic dyes, thereby the opaque light-adjusting sheet 10 may exhibit a color that is black or close to black.

[0061] Each of the first transparent electrode layer 31 and the second transparent electrode layer 32 is conductive and transparent to visible light. The materials for the transparent electrode layers 31 and 32 include, for example, indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, poly(3,4-ethylenedioxythiophene), silver, and silver alloys.

[0062] Each of the first transparent support layer 41 and the second transparent support layer 42 is a substrate that is 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 include, for example, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyacrylates such as polymethyl methacrylate, polycarbonates, and polyolefins. Inorganic compounds include, for example, silicon dioxide, silicon oxynitride, and silicon nitride.

[0063] The transparent electrode layers 31 and 32 are electrically connected to the control unit 50 via wiring. The control unit 50 applies a drive voltage, which is an AC voltage for changing the orientation state of the liquid crystal compound, to the transparent electrode layers 31 and 32 via the wiring. The control unit 50 controls the potential difference between the transparent electrode layers 31 and 32 by controlling whether or not the voltage is applied and by controlling the magnitude of the applied voltage. The dimming device is composed of the dimming sheet 10 and the control unit 50.

[0064] The dimming sheet 10 switches between a transparent state and an opaque state based on a change in the orientation state of the liquid crystal compound. The transparent state is a state with relatively high light transmittance, and the opaque state is a state with relatively low light transmittance.

[0065] When no driving voltage is applied, the orientation of the liquid crystal compound along its long axis is irregular. As a result, due to the birefringence of the liquid crystal compound and the refractive index difference between the liquid crystal compound and the transparent polymer layer, light incident on the dimming sheet 10 is scattered in various directions by the dimming layer 20. At this time, since the orientation of the dichroic dye along its long axis is also disordered, at least a portion of the dichroic dye exhibits color. Therefore, the dimming sheet 10 becomes opaque when no driving voltage is applied. In the opaque state, the dimming sheet 10 appears in a color corresponding to the color exhibited by the dichroic dye.

[0066] When a driving voltage is applied, the liquid crystal compound, which has positive dielectric anisotropy, is oriented so that its long axis aligns with the direction of the electric field. In other words, the orientation of the liquid crystal compound changes so that its long axis aligns with the thickness direction of the dichroic layer 20. Consequently, the dichroic dye is also oriented so that its long axis aligns with the direction of the electric field. As a result, light scattering and absorption in the dichroic layer 20 are suppressed, and light is more easily transmitted through the dichroic sheet 10. Therefore, the dichroic sheet 10 becomes transparent when a driving voltage is applied.

[0067] The dimming sheet 10 may also include layers different from those described above. For example, the dimming sheet 10 may include a pair of alignment layers sandwiching the dimming layer 20 between the dimming layer 20 and the transparent electrode layers 31 and 32. The alignment layers are layers that control the orientation of the liquid crystal compound, and when no driving voltage is applied, they orient the liquid crystal compound in a predetermined direction. The material of the alignment layer may be, for example, an organic compound such as polyimide, polyamide, polyvinyl alcohol, or a cyanide compound, an inorganic compound such as silicon oxide or zirconium oxide, or silicone.

[0068] The alignment layer is, for example, a vertical alignment film, in which the liquid crystal compound is aligned perpendicular to the alignment layer. In this case, by using a compound having negative dielectric anisotropy as the liquid crystal compound, when a driving voltage is applied to the transparent electrode layers 31 and 32, the liquid crystal compound and dichroic dye are aligned parallel to the transparent electrode layers 31 and 32. As a result, when no driving voltage is applied to the transparent electrode layers 31 and 32, the dimming sheet 10 is transparent, and when a driving voltage is applied to the transparent electrode layers 31 and 32, the dimming sheet 10 is opaque.

[0069] The dielectric anisotropy of the liquid crystal compound can be appropriately selected according to the direction in which the orientation-regulating force of the orientation layer acts. Furthermore, whether the dimming sheet 10 becomes transparent or opaque when a driving voltage is applied can be changed by the presence or absence of an orientation layer, the direction in which the orientation-regulating force of the orientation layer acts, the sign of dielectric anisotropy in the liquid crystal compound, etc.

[0070] At least one of the front and back surfaces of the dimming sheet 10 is attached to a transparent plate made of glass, resin, or the like. The transparent plate is, for example, a windowpane in various buildings, a partition installed indoors, or a windowpane or windshield in a moving object such as a vehicle or aircraft. The surface of the transparent plate may be flat or curved.

[0071] [Manufacturing method for dimmable sheets] A method for manufacturing the dimming sheet 10 will now be described. First, a first transparent support layer 41 on which a first transparent electrode layer 31 is laminated, and a second transparent support layer 42 on which a second transparent electrode layer 32 is laminated are prepared. The transparent electrode layers 31 and 32 are formed by known film deposition methods such as sputtering.

[0072] Then, a coating film for forming a light-adjusting layer 20 is formed between the first transparent electrode layer 31 and the second transparent electrode layer 32. The coating film is formed by applying a coating liquid which is the monomer composition described above. The monomer composition includes a liquid crystal composition containing the anthraquinone derivative and liquid crystal compound of this embodiment, a polymerizable compound, and a polymerization initiator. The spacer may be dispersed in the coating film after its formation, or it may be dispersed in the coating film by being mixed with the coating liquid.

[0073] When light such as ultraviolet light is irradiated onto the laminate in which the coating film is sandwiched between transparent electrode layers 31 and 32, the polymerizable compound is polymerized, causing phase separation of the liquid crystal composition and forming the light-adjusting layer 20. This forms the light-adjusting sheet 10.

[0074] The applications of the anthraquinone derivative and dye composition of this embodiment are not limited to the light-adjusting sheet 10 described above. For example, the anthraquinone derivative of this embodiment may be used in a light-adjusting sheet having a light-adjusting layer that does not include a transparent polymer layer, or it may be used in the liquid crystal layer of a liquid crystal display device.

[0075] [Examples] The anthraquinone derivatives and dye compositions described above will be explained using specific examples.

[0076] (Example 1) <Synthesis of precursor P1> As shown in the reaction scheme below, precursor P1 was obtained by introducing an iodine atom to the starting material, 1,5-diaminoanthraquinone. A known method was used for introducing the iodine atom.

[0077] [ka]

[0078] <Synthesis of anthraquinone derivatives> The dichroic dye D1, an anthraquinone derivative of Example 1, was obtained according to the reaction scheme described below.

[0079] [ka]

[0080] The detailed procedure is described below. In a two-necked flask, precursor P1, boronic acid A1 (1.4 equivalents), boronic acid A2 (1.4 equivalents), Pd(PPh3)4 (0.01 equivalents), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. After that, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, the resulting residue was purified twice by silica gel chromatography (developing solvent: hexane / ethyl acetate = 10 / 1) to obtain the dichroic dye D1. The yield of dichroic dye D1 was 21%.

[0081] (Example 2) <Synthesis of anthraquinone derivatives> Precursor P1 was synthesized in the same manner as in Example 1, and dichroic dye D2, an anthraquinone derivative of Example 2, was obtained according to the reaction scheme below.

[0082] [ka]

[0083] The detailed procedure is described below. In a two-necked flask, precursor P1, boronic acid A1 (1.4 equivalents), boronic acid A3 (1.4 equivalents), Pd(PPh3)4 (0.01 equivalents), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. After that, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, the resulting residue was purified twice by silica gel chromatography (developing solvent: hexane / ethyl acetate = 10 / 1) to obtain the dichroic dye D2. The yield of dichroic dye D2 was 25%.

[0084] (Example 3) <Synthesis of anthraquinone derivatives> Precursor P1 was synthesized in the same manner as in Example 1, and dichroic dye D3, an anthraquinone derivative of Example 3, was obtained according to the reaction scheme below.

[0085] [ka]

[0086] The detailed procedure is described below. In a two-necked flask, precursor P1, boronic acid A4 (1.4 equivalents), boronic acid A3 (1.4 equivalents), Pd(PPh3)4 (0.01 equivalent), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. After that, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, the resulting residue was purified twice by silica gel chromatography (developing solvent: hexane / ethyl acetate = 10 / 1) to obtain the dichroic dye D3. The yield of dichroic dye D3 was 26%.

[0087] (Example 4) <Synthesis of anthraquinone derivatives> Precursor P1 was synthesized in the same manner as in Example 1, and dichroic dye D4, an anthraquinone derivative of Example 4, was obtained according to the reaction scheme below.

[0088] [ka]

[0089] The detailed procedure is described below. In a two-necked flask, precursor P1, boronic acid A2 (2.8 equivalents), Pd(PPh3)4 (0.01 equivalent), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. After that, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, the resulting residue was purified by silica gel chromatography (developing solvent: hexane / ethyl acetate = 10 / 1) to obtain the dichroic dye D4. The yield of dichroic dye D4 was 52%.

[0090] (Example 5) <Synthesis of anthraquinone derivatives> Precursor P1 was synthesized in the same manner as in Example 1, and dichroic dye D5, an anthraquinone derivative of Example 5, was obtained according to the reaction scheme below.

[0091] [ka]

[0092] The detailed procedure is described below. In a two-necked flask, precursor P1, boronic acid A3 (2.8 equivalents), Pd(PPh3)4 (0.01 equivalent), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. After that, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, the resulting residue was purified by silica gel chromatography (developing solvent: hexane / ethyl acetate = 10 / 1) to obtain the dichroic dye D5. The yield of dichroic dye D5 was 57%.

[0093] (Example 6) <Synthesis of anthraquinone derivatives> Precursor P1 was synthesized in the same manner as in Example 1, and dichroic dye D6, an anthraquinone derivative of Example 6, was obtained according to the reaction scheme below.

[0094] [ka]

[0095] The detailed procedure is described below. In a two-necked flask, precursor P1, boronic acid A5 (2.8 equivalents), Pd(PPh3)4 (0.01 equivalent), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. After that, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, the resulting residue was purified by silica gel chromatography (developing solvent: hexane / ethyl acetate = 10 / 1) to obtain the dichroic dye D6. The yield of dichroic dye D6 was 56%.

[0096] (Example 7) <Synthesis of anthraquinone derivatives> Precursor P1 was synthesized in the same manner as in Example 1, and dichroic dye D7, an anthraquinone derivative of Example 7, was obtained according to the reaction scheme below.

[0097] [ka]

[0098] The detailed procedure is described below. In a two-necked flask, precursor P1, boronic acid A4 (2.8 equivalents), Pd(PPh3)4 (0.01 equivalent), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. After that, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, the resulting residue was purified by silica gel chromatography (developing solvent: hexane / ethyl acetate = 10 / 1) to obtain the dichroic dye D7. The yield of dichroic dye D7 was 60%.

[0099] (Example 8) <Synthesis of anthraquinone derivatives> Precursor P1 was synthesized in the same manner as in Example 1, and dichroic dye D8, an anthraquinone derivative of Example 8, was obtained according to the reaction scheme below.

[0100] [ka]

[0101] The detailed procedure is described below. In a two-necked flask, precursor P1, boronic acid A6 (2.8 equivalents), Pd(PPh3)4 (0.01 equivalent), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. After that, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, the resulting residue was purified by silica gel chromatography (developing solvent: hexane / ethyl acetate = 10 / 1) to obtain the dichroic dye D8. The yield of dichroic dye D8 was 58%.

[0102] (Comparative Example 1) <Synthesis of anthraquinone derivatives> Precursor P1 was synthesized in the same manner as in Example 1, and dichroic dye D9, an anthraquinone derivative of Comparative Example 1, was obtained according to the reaction scheme below.

[0103] [ka]

[0104] The detailed procedure is described below. In a two-necked flask, precursor P1, boronic acid A1 (2.8 equivalents), Pd(PPh3)4 (0.01 equivalent), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. After that, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, the resulting residue was purified by silica gel chromatography (developing solvent: hexane / ethyl acetate = 10 / 1) to obtain the dichroic dye D9. The yield of dichroic dye D9 was 55%.

[0105] (Comparative Example 2) <Synthesis of precursor P2> As shown in the reaction scheme below, precursor P2 was obtained by introducing an iodine atom into the starting material, antralphine. A known method was used for introducing the iodine atom.

[0106] [ka]

[0107] <Synthesis of anthraquinone derivatives> According to the reaction scheme below, the dichroic dye D10, an anthraquinone derivative of Comparative Example 2, was obtained.

[0108] [ka]

[0109] The detailed procedure is described below. In a two-necked flask, precursor P2, boronic acid A1 (2.8 equivalents), Pd(PPh3)4 (0.01 equivalent), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. After that, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, it was purified by silica gel chromatography (developing solvent: chloroform / hexane = 2 / 1) to obtain the dichroic dye D10. The yield of dichroic dye D10 was 80%.

[0110] (Comparative Example 3) <Synthesis of anthraquinone derivatives> Precursor P2 was synthesized in the same manner as in Comparative Example 2, and dichroic dye D11, an anthraquinone derivative of Comparative Example 3, was obtained according to the reaction scheme described below.

[0111] [ka]

[0112] The detailed procedure is described below. In a two-necked flask, precursor P2, boronic acid A2 (2.8 equivalents), Pd(PPh3)4 (0.01 equivalent), and sodium carbonate (3.5 equivalents) were added, and a Liebig tube was attached to purge the flask with nitrogen. To this, toluene / ethanol / water (volume ratio: toluene / ethanol / water = 5 / 1.3 / 1) was added to achieve a molar concentration of precursor P1 of 0.05 mol / L, and the mixture was bubbling with nitrogen for 20 minutes. Then, the mixture was heated and stirred at 90°C for 9 hours. After cooling to room temperature, liquid-liquid separation was performed using ethyl acetate and water, and the organic phase was dried with sodium sulfate. After filtering off the sodium sulfate and concentrating the solution, it was purified by silica gel chromatography (developing solvent: chloroform / hexane = 2 / 1) to obtain the dichroic dye D11. The yield of dichroic dye D11 was 28%.

[0113] (Comparative Example 4) The dichroic dye D12 (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the anthraquinone derivative in Comparative Example 3.

[0114] [ka]

[0115] (Evaluation method) <Solubility: Liquid crystal> The dichroic dyes of each example and comparative example were mixed with each of the following liquid crystal mixtures L1 to L4, and their solubility was evaluated. Each of the following liquid crystal mixtures L1 to L4 is a mixture of multiple liquid crystal compounds. In the liquid crystal mixtures L1 and L3, the largest mass proportion is that of a liquid crystal compound containing a structure with two or more benzene rings bonded together. In the liquid crystal mixtures L2 and L4, the largest mass proportion is that of a liquid crystal compound having one benzene ring and a liquid crystal compound not having a benzene ring combined. L1: JC-5259XX (manufactured by JNC) L2: JC-7156XX (manufactured by JNC) L3: JC-5261XX (manufactured by JNC) L4:JC-7157XX (manufactured by JNC)

[0116] In the solubility evaluation test, the dichroic dye and liquid crystal mixture were mixed to a mass percentage concentration of 15%, and the mixture was heated and stirred at 150°C for 10 minutes. After that, it was allowed to cool at room temperature for 5 minutes, and the presence or absence of dichroic dye precipitation was visually determined. If dichroic dye precipitation was observed, the liquid crystal mixture was added to a mass percentage concentration of 12% of the dichroic dye, and the mixture was heated, stirred, and cooled in the same manner as above, after which the presence or absence of dichroic dye precipitation was visually determined. The same procedure was repeated to decrease the mass percentage concentration of the dichroic dye in the order of 9%, 6%, 3%, and 1.5% until it was determined that no dichroic dye precipitation occurred, thereby determining the upper limit of the mass percentage concentration at which the dichroic dye could dissolve.

[0117] <Solubility: Monomer> The dichroic dyes from each example and comparative example were mixed with the polymerizable compounds M1 and M2 described below, and their solubility was evaluated. M1: Cyclohexyl acrylate M2: Ethyl acrylate

[0118] In the solubility evaluation test, the dichroic dye and polymerizable compound were mixed to a mass percentage concentration of 0.5% and stirred at room temperature for 10 minutes. After that, the presence or absence of precipitation of the dichroic dye was visually determined. If precipitation of the dichroic dye was observed, the polymerizable compound was added to a mass percentage concentration of 0.4% of the dichroic dye, and after stirring in the same manner as above, the presence or absence of precipitation of the dichroic dye was visually determined. The same procedure was repeated to lower the mass percentage concentration of the dichroic dye in the order of 0.3%, 0.2%, 0.1%, and 0.05% until it was determined that no precipitation of the dichroic dye occurred, thereby determining the upper limit of the mass percentage concentration at which the dichroic dye could be dissolved.

[0119] <Liquid crystal cell> For the examples and comparative examples in which the mass percentage concentration of the L3 liquid crystal mixture was 3% or higher and soluble, the dichroic dye was mixed with the L3 liquid crystal mixture so that the mass percentage concentration of the dichroic dye was 1.5%, heated and stirred at 120°C for 10 minutes, and then allowed to cool to room temperature to prepare a liquid crystal composition. The L3 liquid crystal mixture contains a biphenyl-based liquid crystal compound and a cyanophenyl-based liquid crystal compound.

[0120] A liquid crystal cell was fabricated by injecting the prepared liquid crystal composition into an evaluation cell (manufactured by EHC). The evaluation cell has a structure in which two glass plates (0.7 mm thick) are placed facing each other and sealed with epoxy resin. Each glass plate has a transparent electrode layer made of indium tin oxide and an alignment layer made of polyimide laminated on it, and the glass plates are arranged so that the alignment layers face each other. The alignment layers are parallel aligned by a rubbing process. The cell gap is 10 μm.

[0121] The transmission spectra were measured for liquid crystal cells when linearly polarized light parallel to the orientation direction and linearly polarized light perpendicular to the orientation direction were incident on them. A spectrophotometer (U-4100, Hitachi High-Technologies) was used for the measurements. Linearly polarized light parallel to the orientation direction is extraordinary light, and linearly polarized light perpendicular to the orientation direction is ordinary light.

[0122] The transmission spectrum was converted to an absorption spectrum to obtain the absorption maximum wavelength λmax in the absorption spectrum of the anomalous light, as well as the anomalous light absorbance and ordinary light absorbance at the absorption maximum wavelength λmax. The dichromatic ratio was then calculated by determining the ratio of the anomalous light absorbance to the ordinary light absorbance.

[0123] <Dimming Sheet> A monomer mixture was prepared by mixing the following materials. The mixing ratios of each material listed below represent the mass ratio of each material to the total monomer mixture. • Ethyl acrylate (manufactured by Fujifilm Wako Pure Chemical Industries) 48% • Isobolonyl acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) 22% • Methoxytriethylene glycol acrylate (Light Acrylate MTG-A, manufactured by Kyoeisha Chemical Co., Ltd.) 10% • Dipropylene glycol diacrylate (NK ester APG-100, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) 5% • Trimethylolpropane triacrylate (NK ester A-TMPT, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) 9% • Trifunctional secondary thiol (Callenz MT NR1, manufactured by Resonaq) 6%

[0124] For each example and comparative example, the dichroic dye was mixed with the liquid crystal mixture, the dichroic dye, the monomer mixture, and the polymerization initiator in the following proportions. Specifically, the liquid crystal mixture and the dichroic dye were mixed and heated and stirred at 120°C for 10 minutes. After returning to room temperature, the monomer mixture in which the polymerization initiator was dissolved was added and stirred at room temperature for 10 minutes. This yielded a monomer composition containing the liquid crystal compound, the dichroic dye, the polymerizable compound, and the polymerization initiator. The mixing ratios of each material listed below represent the mass ratio of each material to the total monomer composition. ·Liquid crystal mixture (JC-5261XX, manufactured by JNC) 54% • Dichroic pigment 2% • Monomer mixture 43% • Polymerization initiator (Omnirad 819, IGM Resins) 1%

[0125] When the monomer compositions were visually inspected for the presence or absence of dichroic pigment precipitation, no dichroic pigment precipitation was observed in Examples 1 to 8. For Examples 1 to 8, 1% by mass of spacer particles (particle size 20 μm) made of polymethyl methacrylate was added to the monomer composition, and the mixture was stirred at room temperature for 10 minutes to prepare a coating solution for forming a light-adjusting layer.

[0126] A laminate was fabricated in which a coating film made of the above-mentioned coating was sandwiched between the transparent electrode layers of two electrode sheets by applying the above-mentioned coating solution to an electrode sheet in which a transparent electrode layer made of indium tin oxide was laminated to a transparent support layer made of polyethylene terephthalate and the above-mentioned coating solution was laminated. Subsequently, ultraviolet light with a wavelength of 365 nm was applied to the laminate at a rate of 12 mW / cm². 2 By irradiating with this intensity for 120 seconds, a photochromic layer was formed, and a photochromic sheet was obtained.

[0127] Voltage-applying electrodes were placed on the dimming sheet so that a voltage could be applied between the two transparent electrode layers. The total light transmittance was measured both when no voltage was applied and when a 100V sinusoidal AC voltage was applied, and the transmittance ratio was calculated. The transmittance ratio is the ratio of the total light transmittance in the transparent state to the total light transmittance in the opaque state. When no voltage is applied, the dimming sheet is in the opaque state, and when voltage is applied, the dimming sheet is in the transparent state.

[0128] Furthermore, an optically transparent adhesive film that cuts light with wavelengths below 395 nm was laminated to one side of the dimming sheet, and then a blue glass plate was laminated onto the optically transparent adhesive film. Then, using a lightfastness tester (iSuper UV Tester SUV-W161, manufactured by Iwasaki Electric), light was irradiated onto the dimming sheet from the side where the blue glass plate was located, and a lightfastness test was performed. The test conditions are as follows. ·Illuminance: 65mW / cm 2 ·Temperature: 63℃ Humidity: 60Rh% • Exam duration: 300 hours

[0129] For both the opaque and transparent states of the light-adjusting sheet, the transmission spectra before and after the lightfastness test were measured using a spectrophotometer (U-4100, Hitachi High-Technologies Corporation), and L * ,a * ,b * We calculated the following. Then, we calculated the color difference ΔEab of the light-adjusting sheet before and after the light-fastness test.

[0130] Furthermore, the storage performance of the light-adjusting sheets was evaluated by visually checking for the presence or absence of dichroic pigment precipitation after storing them at room temperature for 100 days from the time of fabrication. In the evaluation, a score of "G (Good)" was given if no dichroic pigment precipitation was observed, and a score of "B (Bad)" was given if dichroic pigment precipitation was observed.

[0131] (Evaluation results) Figures 2 and 3 show the structures of the anthraquinone derivatives for each example and comparative example, as well as the results of each evaluation. In Figures 2 and 3, α, X, and Y correspond to α, X, and Y in the following formula (I). In addition, Figures 2 and 3 show the upper limit of the mass percentage concentration at which the dichroic dye can be dissolved, as an evaluation of the solubility for the liquid crystal and monomer, respectively. Regarding solubility for monomer, "<0.05%" indicates that precipitation of the dichroic dye was confirmed even at a concentration of 0.05%.

[0132] [ka]

[0133] As shown in Figures 2 and 3, in Examples 1 to 8, where the anthraquinone derivative structure has a substituent at the α position of -NH2 and at least one of X and Y is a branched alkyl group, the upper limit of the soluble concentration was 3% or more for all of the liquid crystal mixtures L1 to L4.

[0134] On the other hand, in Comparative Examples 1 and 2, where both X and Y are linear alkyl groups, in Comparative Example 2, where the substituent at the α position is -OH, the upper limit of the soluble concentration for all L1 to L4 liquid crystal mixtures was 1.5%, and the solubility in monomers was extremely low. Furthermore, in Comparative Example 1, where the substituent at the α position is -NH2, solubility in liquid crystals was obtained compared to Comparative Example 2, but the solubility in monomers was similarly low. Also, even though both X and Y are branched alkyl groups, in Comparative Example 3, where the substituent at the α position is -OH, solubility in liquid crystals was obtained compared to Comparative Example 2, but the solubility in monomers was similarly low.

[0135] In contrast, in Examples 1 to 8, the solubility in liquid crystals was generally improved, and higher solubility in monomers was also obtained compared to Comparative Examples 1 to 4. In Examples 1-8, compared to the L2 and L4 liquid crystal mixtures, which had the highest mass proportion of liquid crystal compounds containing two or more benzene rings, a tendency was observed for higher solubility in the L1 and L3 liquid crystal mixtures, which had the highest mass proportion of liquid crystal compounds containing one benzene ring and liquid crystal compounds without a benzene ring. Furthermore, a tendency was observed for higher solubility in ethyl acrylate than in cyclohexyl acrylate.

[0136] In Examples 1-8, it was confirmed that the absorption maximum wavelength λmax in a usable wavelength range for magenta-based dyes could be obtained, along with a good dichroism ratio. Specifically, the absorption maximum wavelength λmax was between 470 nm and 560 nm, and the dichroism ratio was 7 or higher. In Comparative Example 4, an existing magenta-based dichroic dye, even though the upper limit of the soluble concentration in each liquid crystal mixture was 3%, the solubility in the monomer was insufficient, and the dichroism ratio was low.

[0137] Therefore, it was confirmed that when the substituent at the α position is -NH2 and at least one of X and Y is a branched alkyl group, both a high dichroism ratio and high solubility in liquid crystals can be obtained in magenta-based dichroic dyes, and furthermore, good solubility in monomers can also be obtained.

[0138] Furthermore, in Examples 1-3, where X and Y were different from each other, good storage properties were confirmed. In addition, a comparison between Examples 2 and 3 and Example 5 suggests that structures in which X and Y are different from each other yield higher solubility for both the liquid crystal and the monomer than structures in which X and Y are identical.

[0139] As described above using the examples, the anthraquinone derivative, dye composition, and light-adjusting sheet of the above embodiment provide the following effects. [1] In formula (1) described above, at least one of X and Y is a branched alkyl group. With the above configuration, both a high dichroic ratio and high solubility in liquid crystals can be obtained in a magenta-based dichroic dye. Furthermore, high solubility in monomers can also be obtained.

[0140] [2] In formula (1) above, if both X and Y are branched alkyl groups, the branching in the molecular structure increases, making it easier to suppress the aggregation of anthraquinone derivatives. [3] In formula (1) above, at least one of X and Y is a branched alkyl group represented by formula (2) above, and each of m and l in formula (2) above is an integer between 1 and 6. With the above configuration, high solubility in liquid crystals and monomers can be obtained, and excessive bulkiness of the molecule can be suppressed.

[0141] [4] In formula (1) above, if X and Y are different from each other, the precipitation of the anthraquinone derivative can be suppressed even when the device using the anthraquinone derivative is stored for a long period of time. In addition, the solubility of the liquid crystal and monomer can be improved.

[0142] [5] The dye composition containing the anthraquinone derivative and the liquid crystal compound of the above embodiment is suitable for use in liquid crystal elements because it uses an anthraquinone derivative that has a high dichromatic ratio and high solubility in liquid crystals.

[0143] [6] The dye composition comprising the anthraquinone derivative, liquid crystal compound, and polymerizable compound of the above embodiment is suitable for use in the manufacture of liquid crystal elements having a liquid crystal layer including a transparent polymer layer, since it uses an anthraquinone derivative having a high dichromatic ratio and high solubility in liquid crystals and monomers.

[0144] [7] In the case of a light-adjusting sheet equipped with a light-adjusting layer containing an anthraquinone derivative according to the above embodiment, since an anthraquinone derivative having a high dichromatic ratio and high solubility in liquid crystal and monomer is used, suitable manufacturing of the light-adjusting sheet is possible, and properties such as contrast can also be enhanced. [Explanation of Symbols]

[0145] 10… Dimming sheet 20…Dimming layer 31,32...Transparent electrode layer 41,42...Transparent support layer 50…Control Unit

Claims

1. An anthraquinone derivative represented by the following formula (1). 【Chemistry 1】 In formula (1), X and Y are each independently alkyl groups, and at least one of X and Y is a branched alkyl group having 3 to 15 carbon atoms.

2. In formula (1), the branched alkyl group is represented by the following formula (2), where in formula (2), n, m, and l are each independently integers of 1 or more, and satisfying 3 ≤ n + m + l ≤ 15. -C n H 2n-1 (C m H 2m+1 ) C l H 2l+1 ... (2) The anthraquinone derivative according to claim 1.

3. In formula (2), n is an integer between 1 and 5, m is an integer between 1 and 6, and l is an integer between 1 and 6. The anthraquinone derivative according to claim 2.

4. In formula (1) above, X and Y are each independently branched alkyl groups having 3 to 15 carbon atoms. The anthraquinone derivative according to claim 1.

5. In formula (1) above, X and Y are different alkyl groups, and at least one of X and Y is a branched alkyl group having 3 to 15 carbon atoms. The anthraquinone derivative according to claim 1.

6. An anthraquinone derivative according to any one of claims 1 to 5, A liquid crystal compound, including A pigment composition.

7. An anthraquinone derivative according to any one of claims 1 to 5, Liquid crystal compounds and polymerizable compounds, A pigment composition.

8. A light-adjusting layer comprising an anthraquinone derivative and a liquid crystal compound according to any one of claims 1 to 5, The light-adjusting layer is sandwiched between a pair of transparent electrode layers. Dimming sheet.

9. The aforementioned dimming layer is A transparent polymer layer containing multiple voids, A liquid crystal composition held in the void, comprising the anthraquinone derivative and the liquid crystal compound. The dimming sheet according to claim 8.

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