Liquid crystal composition containing anthraquinone compound, and dimming element

Abstract

To provide a liquid crystal composition excellent in light shielding properties, and a dimming element containing the composition.SOLUTION: The liquid crystal composition contains (A) a dye compound and (B) a liquid crystal material. The dye compound (A) contains a plurality of kinds of anthraquinone compounds of specific structures.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal composition and a light-adjusting element containing an anthraquinone compound. [Background technology]

[0002] For purposes such as privacy protection, light-controlling panels have become commonplace in windows, doors, and partitions in vehicles such as trains and automobiles, and buildings such as business buildings and hospitals. These panels include films obtained by dispersing liquid crystals in polymers and films with a light-controlling layer formed by utilizing the phase separation of a liquid crystal material upon photocuring of a composition containing a photocurable compound and a liquid crystal. While such light-controlling panels typically block the view by controlling the transmission and scattering of light depending on whether or not a voltage is applied, they do not block light and tend to increase glare due to light scattering. Therefore, attempts have been made to use dyes as materials for light-controlling panels to reduce glare and improve contrast. For example, when using such light-controlling panels in automobile windows, they are required to provide clear visibility without fogging when transparent, high contrast, and light resistance that does not decrease transmittance even when exposed to light at high temperatures for long periods of time due to long-term exposure to light during outdoor use. This has led to an increasing demand for black elements that can block visible light from the perspectives of practicality and design.

[0003] In order to satisfy the above market demands, various liquid crystal display elements called GH (guest-host) type, which use liquid crystal compositions containing dyes, have been proposed. These liquid crystal display elements, which are characterized by their viewing angle, brightness, etc., have also been put to practical use in automotive applications and as light control elements.

[0004] Dichroic dyes commonly used in liquid crystal compositions for dimming devices are required to have a dichroic ratio sufficient to enhance contrast when used in a device, as well as light resistance, UV resistance, heat resistance, and compatibility (solubility) of the dichroic dye with the components of the liquid crystal composition. Furthermore, from the perspectives of practicality and design, there is a demand for dyes that can block more visible light. Patent Document 5 discloses a dichroic dye with low transmittance at the maximum absorption wavelength as a material with excellent light-blocking properties, but it is difficult to say that its transmittance at other wavelengths is sufficiently low. Increasing the amount of dye used to reduce transmittance over a wide wavelength range can result in precipitation of the dye or a decrease in contrast when used in a device. Therefore, there is a demand for liquid crystal compositions that can reduce transmittance over a wide wavelength range with a smaller amount of dye. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 63-501512 [Patent Document 2] Japanese Patent Application Publication No. 03-47392 [Patent Document 3] Japanese Patent Application Publication No. 2018-205746 [Patent Document 4] Japanese Patent Application Laid-Open No. 2011-190314 [Patent Document 5] WO2022 / 138440 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a liquid crystal composition containing a dye compound having a specific structure, and a light-controlling element having excellent light-shielding properties. [Means for solving the problem]

[0007] As a result of extensive research, the inventors have discovered that the above problems can be solved by using a liquid crystal composition containing multiple anthraquinone compounds (dichroic dyes) with specific structures, and have thus completed the present invention. That is, the present invention provides: (1) A liquid crystal composition containing (A) a dye compound and (B) a liquid crystal material, wherein the dye compound (A) contains at least one compound selected from the group consisting of an anthraquinone compound represented by the following general formula (1) and an anthraquinone compound represented by the following general formulas (2) to (4): [ka] (In the formula, R1 and R2 each independently represent an alkyl group having 1 to 10 carbon atoms.) [ka] (In the formula, R3 and R4 each independently represent an alkyl group having 1 to 10 carbon atoms.) [ka] (wherein R5 represents an alkyl group having 1 to 10 carbon atoms). [ka] (In the formula, R6 and R7 each independently represent an alkyl group having 1 to 10 carbon atoms.) (2) The liquid crystal composition according to (1), wherein the concentration of the dye compound (A) contained in the liquid crystal composition relative to the liquid crystal material (B) is 0.5 to 10% by mass. (3) A light-adjusting element comprising a pair of opposing substrates, at least one of which is a transparent substrate having a transparent electrode, and a liquid crystal composition according to (1) or (2) sandwiched between the pair of substrates. [Effects of the Invention]

[0008] By using the liquid crystal composition of the present invention, a light-controlling element having excellent light-shielding properties can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below. The liquid crystal composition of the present invention (hereinafter also simply referred to as "the composition of the present invention") contains an anthraquinone compound represented by the following formula (1). The anthraquinone compounds represented by formulas (1) to (4) contained in the composition of the present invention function as dichroic dyes in the composition of the present invention.

[0010] [ka]

[0011] [ka]

[0012] [ka]

[0013] [ka]

[0014] (In the formula, R1, R2, R3, R4, R5, R6, and R7 each independently represent an alkyl group having 1 to 10 carbon atoms.)

[0015] Examples of the alkyl group having 1 to 10 carbon atoms represented by R1, R2, R3, R4, R5, R6, and R7 in formulas (1) to (4) include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, an n-pentyl group, an isopentyl group, a neo-pentyl group, a t-pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, a 2-ethylhexyl group, a 2-propylhexyl group, and a 2-butylhexyl group. An alkyl group having 4 to 8 carbon atoms is preferred, and a linear alkyl group having 4 to 8 carbon atoms is more preferred.

[0016] As for the combinations of R1, R2, R3, R4, R5, R6, and R7 in formulas (1) to (4), combinations in which R2, R4, R5, and R7 are the same substituent and R1, R3, and R6 are the same substituent are preferred, combinations in which R1, R2, R3, R4, R5, R6, and R7 are alkyl groups having 4 to 8 carbon atoms are more preferred, and combinations in which R1, R2, R3, R4, R5, R6, and R7 are linear alkyl groups having 4 to 8 carbon atoms are even more preferred.

[0017] The compound represented by formula (1) can be synthesized by a conventionally known method, for example, as described in JP-A-62-5941. Specifically, an anthraquinone compound represented by the following formula (5) and a phenol derivative represented by the following formula (6) are reacted under basic conditions such as potassium carbonate in a solvent such as NMP at 160 to 165° C. to obtain a compound represented by formula (1). Note that R1 in the following formula (5) and R2 in the following formula (6) have the same meanings as R1 and R2 in formula (1).

[0018] [ka]

[0019] The compound represented by formula (2) can be synthesized by the method described in WO2023 / 063408. Specifically, it can be synthesized by reacting an anthraquinone compound represented by formula (7) below with a bromobenzene derivative represented by formula (8) below in a solvent such as N-methylpyrrolidone under basic conditions such as potassium carbonate in the presence of a copper catalyst such as copper powder at 140 to 160°C. Note that R3 in formulas (7) and (8) below and R4 in formula (7) below have the same meaning as R4 in formula (2).

[0020] [ka]

[0021] The compound represented by formula (3) can be synthesized under the same conditions as the compound represented by formula (1), except that an anthraquinone compound represented by formula (9) below is used instead of formula (5), and a phenol derivative represented by formula (10) below is used instead of formula (6). Note that R5 in formula (10) below has the same meaning as R5 in formula (3).

[0022] [ka]

[0023] The compound represented by formula (4) can be synthesized by the method described in JP-A-62-5941. Specifically, an anthraquinone compound represented by the following formula (11) and a phenol derivative represented by the following formula (12) are reacted under basic conditions such as potassium carbonate in a solvent such as NMP at 140 to 145° C. to obtain a compound represented by formula (4). Note that R6 in the following formula (11) and R7 in the following formula (12) have the same meanings as R6 and R7 in formula (4).

[0024] [ka]

[0025] In the composition of the present invention, the dye compound (A) contains at least one compound represented by formulas (2) to (4), and may contain a plurality of compounds.

[0026] In the composition of the present invention, dichroic dyes other than the anthraquinone compounds represented by formulas (1) to (4) can be used in combination as the dye compound (A). The dichroic dye that can be used in combination is not particularly limited, and may be selected from, for example, azo dyes, anthraquinone dyes, perylene dyes, quinophthalone dyes, merocyanine dyes, azomethine dyes, phthaloperylene dyes, indigo dyes, azulene dyes, dioxazine dyes, polythiophene dyes, and the like. Specific examples include those described in "Dichroic dyes for Liquid Crystal Display" (AVI Vashchenko, CRC, 1994). Among these, it is preferable to use an azo dye, an anthraquinone dye, a perylene dye or a quinophthalone dye in combination, and it is more preferable to use an azo dye or an anthraquinone dye in combination.

[0027] The content of the anthraquinone compound represented by formula (1) in the total dichroic dyes is not particularly limited as long as it is within a range that does not impair the effects of the present invention, but is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. By setting the content of formula (1) within this range, it is possible to reduce the average transmittance in visible light, and a liquid crystal composition with high light-blocking properties can be obtained.

[0028] The liquid crystal material (B) contained in the liquid crystal composition of the present invention is not particularly limited as long as it is a material (compound having liquid crystal properties) having liquid crystallinity such as nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, etc. Examples of such liquid crystal compounds include those described in paragraphs 154 to 192 and 715 to 722 of "Liquid Crystal Device Handbook" (edited by the 142nd Committee of the Japan Society for the Promotion of Science, Nikkan Kogyo Shimbun, Ltd., 1989), and in Japanese Patent Nos. 4,169,692 and 5,659,512.

[0029] The total concentration of the (A) dye compound contained in the liquid crystal composition is preferably 0.5 to 10% by mass, more preferably 0.5 to 5% by mass, relative to the (B) liquid crystal material. By setting the concentration of the (A) dye compound within this range, a sufficient dye addition effect can be obtained, and a liquid crystal composition with high light-blocking properties can be obtained.

[0030] In order to achieve the above-mentioned preferred dye concentration, the solubility of the dye compound (A) in the liquid crystal material (B) is preferably 0.5% by mass or more, and more preferably 1% by mass or more.

[0031] The liquid crystal composition of the present invention may contain various additives such as an optically active substance that exhibits or does not exhibit a liquid crystal phase, such as cholesteryl noenoate, an ultraviolet absorber, and an antioxidant.

[0032] The liquid crystal composition of the present invention may further contain in combination a light stabilizer such as a benzotriazole-based, benzophenone-based or hindered amine-based, an antioxidant such as a phosphite-based or hindered phenol-based, a thermal polymerization inhibitor, a thiol compound, a photosensitizer, a photosensitizer, a chain transfer inhibitor, a polymerization inhibitor, an adhesion promoter, an antifoaming agent, a crosslinking agent, a surfactant, a heat curing accelerator, a thermoplastic resin, a thermosetting resin, a thickener such as urethane diacrylate, and the like. In order to control the cell gap of the light-adjusting element, spherical or cylindrical spacers made of silica, glass, plastic, ceramic, etc. may be added. In this case, the cell gap can be set in the range of 2 to 100 μm.

[0033] As an example of the additives that may be contained, a photocurable compound and a photopolymerization initiator may be contained, as described in Patent Document 4. By photocuring these, the polymer and the liquid crystal substance undergo phase separation, and a film having a light control layer or the like can be obtained.

[0034] In this case, examples of compounds having a functional group polymerizable by the action of a photopolymerization initiator include compounds having a (meth)acrylate group, compounds having a vinyl group, and compounds having an allyl group, but compounds having a (meth)acrylate group are preferred. That is, it is more preferable to use in combination both a mono(meth)acrylate compound having one (meth)acrylate group in one molecule and a di(meth)acrylate compound having two (meth)acrylate groups in one molecule. In this specification, the term "(meth)acrylate" means "methacrylate and / or acrylate".

[0035] The mono(meth)acrylate compound is preferably a mono(meth)acrylate having a linear or branched alkyl group having 5 to 13 carbon atoms, and specific examples thereof include linear alkyl mono(meth)acrylates such as pentyl(meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, octyl(meth)acrylate, nonyl(meth)acrylate, decyl(meth)acrylate, undecyl(meth)acrylate, dodecyl(meth)acrylate, and tridecyl(meth)acrylate, and branched alkyl mono(meth)acrylates such as 2-methylhexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, 2-propylhexyl(meth)acrylate, 2-methylheptyl(meth)acrylate, 2-ethylheptyl(meth)acrylate, and 2-propylheptyl(meth)acrylate.

[0036] Suitable examples of the di(meth)acrylate compound include 1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,11-undecanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, and 1,13-tridecanediol di(meth)acrylate.

[0037] The photopolymerization initiator is not particularly limited as long as it is a compound that can polymerize a photocurable compound by irradiation with light, but it is preferable that it does not remain in the cured liquid crystal composition after irradiation with light and cause deterioration of the dichroic dye, etc. As the photopolymerization initiator, for example, alkylphenone-based photopolymerization initiators such as Darocur 1173, Irgacure 651, Irgacure 184, etc., and phosphine oxide-based photopolymerization initiators such as Irgacure TPO, etc. are preferably used.

[0038] The liquid crystal composition of the present invention can be obtained by mixing and stirring (A) the dye compound, (B) the liquid crystal material, and any optional components added as needed. While the simplest method for mixing and stirring is to simply place all of the components in a container and stir manually, it is more effective to use an electric stirrer such as a magnetic stirrer. Mixing and stirring while heating can also effectively dissolve (A) the dye compound.

[0039] The light-adjusting element of the present invention comprises a pair of substrates, at least one of which is a transparent substrate having a transparent electrode, sandwiched between the liquid crystal composition or a photocured product thereof. Examples of the substrate include inorganic transparent materials such as glass and quartz, and colorless, transparent, or opaque materials such as metals, metal oxides, semiconductors, ceramics, and plastic plates and films. The electrodes are formed on the substrates by coating, printing, or vapor deposition methods such as sputtering with a thin film of a metal oxide, metal, semiconductor, or organic conductive material over the entire surface or in part of the substrate using known coating methods, printing, or vapor deposition methods such as sputtering. In particular, to obtain a large-area light-adjusting element, it is desirable to use an electrode substrate in which an ITO (indium oxide, tin oxide) electrode is formed on a transparent polymer film such as PET using vapor deposition methods such as sputtering or printing, from the standpoints of productivity and processability. The substrate may also have electrodes or wiring for connecting the electrodes to the outside. For example, the substrate may be a segment-drive electrode substrate, a matrix-drive electrode substrate, or an active-matrix drive electrode substrate. Furthermore, the electrode surface provided on the substrate may be covered entirely or partially with a protective film or alignment film made of organic compounds such as polyimide, polyamide, silicon, and cyanide compounds, inorganic compounds such as SiO2, TiO2, and ZrO2, or mixtures thereof.

[0040] The use of a plastic film as a substrate allows for a flexible and lightweight photochromic element. Therefore, the photochromic element can be sandwiched between a pair of flat or curved glass or hard plastic substrates via an adhesive layer such as polyvinyl butyral, vinyl acetate ester, double-sided tape, or adhesive. Alternatively, the photochromic element can be attached to the surface of a single flat or curved glass or hard plastic substrate using double-sided tape or adhesive. The photochromic element can also be sandwiched between soft plastic substrates or attached to one or both sides. A protective layer such as a hard coat, an ultraviolet-blocking layer, an infrared-blocking layer, or a half mirror may be provided on the substrate surface opposite the electrode surface of the photochromic element. A color filter or a polarizer filter may also be laminated. The photochromic element may also be laminated as an electroluminescent display element, a light-emitting diode display element, an electrochromic display element, or another liquid crystal display element.

[0041] The driving device for applying a voltage to the dimming element of the present invention is a device that can apply a DC voltage or an AC voltage and that opens or shorts the electrodes when no voltage is applied. This driving device may also be equipped with a voltage application circuit for segment driving, a voltage application circuit for matrix driving, a voltage application circuit for active matrix driving, etc.

[0042] The dye compounds (A) of the present invention represented by formula (1) and formulas (2) to (4) have high light-shielding properties, and light-control devices using these compounds are suitable for use in building materials such as windows, partitions, and doors, and in-vehicle materials such as windows and sunroofs. [Example]

[0043] The present invention will be described in more detail below with reference to examples. In the text, "parts" and "%" are by mass unless otherwise specified.

[0044] Example 1 21.9 parts of 4-heptyloxyphenol and 3.0 parts of potassium carbonate were added to 30 parts of N-methylpyrrolidone, and the mixture was heated to 150°C under a nitrogen flow for dehydration. After cooling to 100°C, 12.0 parts of 1-(4-heptylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone was added, and the mixture was heated to 160-165°C and stirred for 3 hours. After cooling to 70°C, 35.0 parts of methanol was added, and the precipitated crystals were filtered and washed with water and methanol. After drying, the crystals were purified by silica gel column chromatography to obtain 4.0 parts of the compound represented by the following formula (1-1).

[0045] [ka]

[0046] Example 2 0.9 parts of the compound represented by formula (1-1) was dissolved in 20 parts of N-methylpyrrolidone, and 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.5 parts of 1-bromo-4-n-heptylbenzene, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate were added and reacted at 140 to 150°C for 12 hours. After the reaction, the mixture was cooled, methanol was added, and the precipitated crystals were filtered, washed with methanol and water, and then dried. The resulting crude product was purified by column chromatography to obtain 0.2 parts of the compound represented by formula (2-1) below.

[0047] [ka]

[0048] Example 3 21.9 parts of 4-heptyloxyphenol and 3.0 parts of potassium carbonate were added to 30 parts of N-methylpyrrolidone, and the mixture was heated to 150°C under a nitrogen flow for dehydration. After cooling to 100°C, 8.6 parts of 1,5-diamino-4,8-dihydroxy-3,7-dibromoanthraquinone was added, and the mixture was heated to 160-165°C and stirred for 3 hours. After cooling to 70°C, 35.0 parts of methanol was added, and the precipitated crystals were filtered and washed with water and methanol. After drying, the crystals were purified by silica gel column chromatography to obtain 3.5 parts of a compound represented by the following formula (3-1).

[0049] [ka]

[0050] Example 4 8.3 parts of 4-heptyloxyphenol and 3.0 parts of potassium carbonate were added to 30 parts of N-methylpyrrolidone, and the mixture was heated to 150°C under a nitrogen flow for dehydration. After cooling to 100°C, 12.0 parts of 1-(4-heptylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone was added, and the mixture was heated to 140-145°C and stirred for 3 hours. After cooling to 70°C, 35.0 parts of methanol was added, and the precipitated crystals were filtered and washed with water and methanol. After drying, the crystals were purified by silica gel column chromatography to obtain 3.2 parts of the compound represented by the following formula (4-1).

[0051] [ka]

[0052] Example 5 4.2 parts of a compound represented by the following formula (1-2) were obtained in the same manner as in Example 1, except that 11.2 parts of 1-(4-butylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone was used instead of 12.0 parts of 1-(4-heptylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone.

[0053] [ka]

[0054] Example 6 0.2 parts of a compound represented by the following formula (2-2) was obtained in the same manner as in Example 2, except that 0.9 parts of a compound represented by formula (1-2) was used instead of 0.9 parts of a compound represented by formula (1-1) and 2.2 parts of 1-bromo-4-n-butylbenzene was used instead of 2.5 parts of 1-bromo-4-n-heptylbenzene.

[0055] [ka]

[0056] Example 7 3.1 parts of a compound represented by the following formula (4-2) were obtained in the same manner as in Example 4, except that 11.2 parts of 1-(4-butylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were used instead of 12.0 parts of 1-(4-heptylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone.

[0057] [ka]

[0058] Example 8 (Preparation of Liquid Crystal Composition of the Present Invention) A liquid crystal composition of the present invention was obtained by mixing 0.012 parts of the compound represented by formula (1-1) obtained in Example 1, 0.003 parts of the compound represented by formula (2-1) obtained in Example 2, 0.5024 parts of 1-cyano-4'-n-pentylbiphenyl, 0.2462 parts of 1-cyano-4'-n-heptylbiphenyl, 0.1576 parts of 1-cyano-4'-n-octyloxybiphenyl, and 0.0788 parts of 1-cyano-4''-n-pentylterphenyl at room temperature.

[0059] Example 9 (Preparation of Liquid Crystal Composition of the Present Invention) A liquid crystal composition of the present invention was obtained in accordance with Example 8, except that 0.0123 parts of the compound represented by formula (1-1) and 0.0027 parts of the compound represented by formula (3-1) obtained in Example 3 were used instead of the combination of the compound represented by formula (1-1) and the compound represented by formula (2-1).

[0060] Example 10 (Preparation of Liquid Crystal Composition of the Present Invention) A liquid crystal composition of the present invention was obtained in accordance with Example 8, except that 0.0135 parts of the compound represented by formula (1-1) and 0.0015 parts of the compound represented by formula (4-1) obtained in Example 4 were used instead of the combination of the compound represented by formula (1-1) and the compound represented by formula (2-1).

[0061] Example 11 A liquid crystal composition of the present invention was obtained in accordance with Example 8, except that 0.0126 parts of the compound represented by formula (1-2) obtained in Example 5 and 0.0024 parts of the compound represented by formula (2-2) obtained in Example 6 were used instead of the combination of the compound represented by formula (1-1) and the compound represented by formula (2-1).

[0062] Example 12 (Preparation of Liquid Crystal Composition of the Present Invention) A liquid crystal composition of the present invention was obtained in accordance with Example 8, except that 0.0130 parts of the compound represented by formula (1-2) obtained in Example 5 and 0.0020 parts of the compound represented by formula (4-2) obtained in Example 7 were used instead of the combination of the compound represented by formula (1-1) and the compound represented by formula (2-1).

[0063] Comparative Example 1 (Preparation of Comparative Liquid Crystal Composition) A comparative liquid crystal composition was obtained in accordance with Example 8, except that 0.015 parts of the compound represented by formula (1-1) was used instead of the combination of the compound represented by formula (1-1) and the compound represented by formula (2-1).

[0064] Comparative Example 2 (Preparation of Comparative Liquid Crystal Composition) A comparative liquid crystal composition was obtained in accordance with Example 8, except that 0.015 parts of the compound represented by formula (1-2) was used instead of the combination of the compound represented by formula (1-1) and the compound represented by formula (2-1).

[0065] Example 13 (Fabrication of the light-adjusting element of the present invention) The liquid crystal composition obtained in Example 8 was sealed in a device with a gap of 15 μm between two glass substrates, each having a transparent electrode and having a surface in contact with the liquid crystal that had been subjected to a homogeneous alignment treatment by rubbing a polyamide resin on the surface. In the device obtained above, the liquid crystal was in a homogeneous alignment state when no voltage was applied.

[0066] Examples 14 to 17 and Comparative Examples 3 and 4 (Preparation of light-controlling elements of the present invention and comparative examples) The present invention and comparative light control devices were prepared in accordance with Example 13, except that the liquid crystal composition obtained in Example 8 was replaced with the liquid crystal compositions obtained in Examples 9 to 12 and Comparative Examples 1 and 2. The transmittance (Kz) of the obtained light control devices for linearly polarized light parallel to the alignment direction was measured in the visible range of 380 nm to 780 nm. A smaller transmittance (Kz) value indicates a higher light blocking ability at that wavelength.

[0067] As shown in Table 5, the photochromic elements of Examples 13 to 15 have smaller average transmittance (Kz) in the visible light range than the photochromic element of Comparative Example 3, and are therefore found to have high light-blocking properties against visible light. Furthermore, as shown in Table 6, the photochromic elements of Examples 16 and 17 have smaller average transmittance (Kz) in the visible light range than the photochromic element of Comparative Example 4, indicating that they have high light-blocking properties against visible light.

[0068] [Table 5]

[0069] [Table 6] [Industrial Applicability]

[0070] By using the liquid crystal composition of the present invention, a light-control liquid crystal element having high light-shielding properties can be obtained, and the element can be suitably used for outdoor building materials and vehicle applications where design is required.

Claims

1. A liquid crystal composition containing (A) a dye compound and (B) a liquid crystal material, The liquid crystal composition wherein the dye compound (A) contains at least one compound selected from the group consisting of an anthraquinone compound represented by the following general formula (1) and anthraquinone compounds represented by the following general formulas (2) to (4): 【Chemical 1】 (In the formula, R １ , R ２ each independently represents an alkyl group having 1 to 10 carbon atoms. 【Chemistry 2】 (In the formula, R ３ , R ４ each independently represents an alkyl group having 1 to 10 carbon atoms. 【Chemistry 3】 (In the formula, R ５ represents an alkyl group having 1 to 10 carbon atoms. 【Chemistry 4】 (In the formula, R ６ , R ７ each independently represents an alkyl group having 1 to 10 carbon atoms.

2. 2. The liquid crystal composition according to claim 1, wherein the concentration of the dye compound (A) contained in the liquid crystal composition relative to the liquid crystal material (B) is 0.5 to 10% by mass.

3. A light-adjusting element comprising a pair of opposing substrates, at least one of which is a transparent substrate having a transparent electrode, and the liquid crystal composition according to claim 1 sandwiched between the pair of substrates.

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