Anthraquinone compound, light-adjusting liquid crystal composition containing said compound and light-adjusting element

Abstract

The present invention relates to an anthraquinone compound represented by formula (1) (in formula (1), R1 represents a C1-9 alkyl group and R2 represents a C1-8 alkyl group.); a yellow dichroic pigment that includes this compound; a liquid crystal composition for dimming that contains this yellow dichroic pigment and a liquid crystal material; and a dimming element that uses this composition.

Description

[Technical field]

[0001] The present invention relates to a novel anthraquinone compound, a yellow dichroic dye containing the compound, and a light-controlling liquid crystal composition and a light-controlling element each containing the dichroic dye. [Background technology]

[0002] Various ideas have been proposed for light control films that control the transmission of external light for the purpose of protecting privacy, etc., in vehicles such as trains and automobiles, and windows, doors, and partitions in buildings such as business buildings and hospitals (Patent Documents 1 and 2). One such light control film uses liquid crystal. Normally, liquid crystal light control films can block the view by controlling the transmission and scattering of light depending on whether or not a voltage is applied, but they cannot block the light itself, so there is a tendency for glare to increase due to light scattering. Therefore, attempts have been made to use dyes as materials for light control panels for the purpose of reducing glare and improving contrast, etc. (Patent Documents 3 and 4). For example, when such light control panels are used in automobile windows, they are required to have good visibility without fogging when transparent, as well as to obtain deep coloring when blocking light.

[0003] Dichroic dyes are generally used as dyes in liquid crystal light control films. GH (guest-host) type light control elements using liquid crystal compositions containing dichroic dyes are known, and various dichroic dyes have been proposed.

[0004] Such dichroic dyes are required to have light resistance, UV resistance, and heat resistance as well as contrast when used as an element, and efforts are being made to improve these properties. On the other hand, in a liquid crystal composition containing a dichroic dye, it is necessary to include a large amount of the dichroic dye in the liquid crystal composition in order to obtain a large dichroic ratio. However, if the compatibility (solubility) of the dichroic dye with the components of the liquid crystal composition is low, the dichroic dye will precipitate at room temperature or low temperature, resulting in a decrease in contrast and inability to exhibit sufficient performance as a light-adjusting element. For example, Patent Documents 5 and 6 disclose dyes that are excellent in light resistance, heat resistance, order parameters, etc., but the dyes in these documents have insufficient compatibility with the components of the liquid crystal composition.

[0005] As one method for improving the compatibility of a dichroic dye with a liquid crystal composition, it is generally known to make the molecular structure asymmetric, as disclosed in Patent Document 7. However, such a method has disadvantages such as an increase in the number of steps, a tendency for mixtures to be generated in the synthesis process, and the necessity of column chromatography purification using silica gel to increase the purity. As a result, this method is undesirable for industrially producing a liquid crystal composition containing a dichroic dye, as it may result in a decrease in yield and a complicated work process. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 63-501512 [Patent Document 2] Japanese Patent Application Publication No. 03-47392 [Patent Document 3] JP 2018-205746 A [Patent Document 4] JP 2011-190314 A [Patent Document 5] Japanese Patent Application Publication No. 04-264193 [Patent Document 6] Japanese Patent Application Publication No. 57-73067 [Patent Document 7] Japanese Patent Publication No. 61-87756 Summary of the Invention [Problem to be solved by the invention]

[0007] A first object of the present invention is to provide a novel anthraquinone compound. A second object of the present invention is to provide a dichroic dye which can be produced by a simple process, has sufficient solubility and coloring power in a liquid crystal composition, and exhibits excellent contrast; a light-controlling liquid crystal composition containing the dichroic dye and exhibiting excellent light-blocking performance; and a light-controlling element containing a cured product of the composition. [Means for solving the problem]

[0008] As a result of intensive research into achieving the first object, the present inventors have succeeded in obtaining a novel anthraquinone compound. Furthermore, the present inventors have found that the second object can be achieved by using this novel compound.

[0009] That is, the various aspects of the present invention are as follows. [1].The following formula (1) [ka] (In formula (1), R1 represents an alkyl group having 1 to 9 carbon atoms, and R2 represents an alkyl group having 1 to 8 carbon atoms.) A compound represented by the formula: [2] The compound according to the above item [1], wherein the total number of carbon atoms in the alkyl group represented by R1 and the total number of carbon atoms in the alkyl group represented by R2 is 6 to 14. [3] The compound according to the above item [2], wherein R1 is an alkyl group having 4 to 8 carbon atoms and R2 is an alkyl group having 2 to 6 carbon atoms. [4]. A yellow dichroic dye comprising the compound represented by formula (1) described in the preceding paragraph [1]. [5] A light-adjusting liquid crystal composition comprising the yellow dichroic dye according to the above item [4] and a liquid crystal material. [6] The light-adjusting liquid crystal composition according to the above item [5], further comprising a photocurable compound and a photopolymerization initiator. [7] The light-adjusting liquid crystal composition according to the above item [5] or [6], further comprising a red dichroic dye and a blue dichroic dye. [8] A cured product of the light-adjusting liquid crystal composition according to the preceding item [6] or [7]. [9] A light control element comprising a pair of substrates, at least one of which is a transparent substrate having a transparent electrode, and a light control liquid crystal composition according to the above item [5] or a cured product according to the above item [8] sandwiched between the pair of substrates.

[10] The light control element according to the preceding paragraph [9], wherein both of the pair of substrates are transparent substrates having transparent electrodes.

[11] . A light control element according to the preceding paragraph [9] or

[10] , for use in a vehicle.

[12] The light control element according to the preceding paragraph [9] or

[10] , which is used as a building material. Effect of the Invention

[0010] The light-adjusting liquid crystal composition of the present invention is capable of stably maintaining a high dye concentration at room temperature and at low temperatures, and a light-adjusting element having excellent solubility and contrast can be obtained by using the composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below. The compound of the present invention (anthraquinone compound) is represented by the following formula (1).

[0012] [ka]

[0013] In formula (1), R1 represents an alkyl group having 1 to 9 carbon atoms, and R2 represents an alkyl group having 1 to 8 carbon atoms.

[0014] The alkyl group having 1 to 9 carbon atoms represented by R1 in formula (1) may be either linear or branched. Specific examples of R1 include a methyl group, an ethyl group, an n-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, and a nonyl group.

[0015] The alkyl group having 1 to 9 carbon atoms represented by R1 in formula (1) is preferably an alkyl group having 2 to 9 carbon atoms, more preferably an ethyl group, n-propyl group, n-butyl group, n-pentyl group, hexyl group, heptyl group, octyl group, or nonyl group. The alkyl group having 1 to 9 carbon atoms represented by R1 in formula (1) is more preferably an alkyl group having 4 to 8 carbon atoms, further preferably an n-butyl group or octyl group.

[0016] The alkyl group having 1 to 8 carbon atoms represented by R2 in formula (1) may be either linear or branched. Specific examples of R2 include a methyl group, an ethyl group, an n-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, and an octyl group.

[0017] The alkyl group having 1 to 8 carbon atoms represented by R2 in formula (1) is preferably an alkyl group having 1 to 7 carbon atoms, more preferably a methyl group, an ethyl group, an n-butyl group, an n-pentyl group, a hexyl group, or a heptyl group. The alkyl group having 1 to 8 carbon atoms represented by R2 in formula (1) is more preferably an alkyl group having 2 to 6 carbon atoms, still more preferably an ethyl group, an n-butyl group, or a hexyl group. In formula (1), the total number of carbon atoms in the alkyl group represented by R1 and the alkyl group represented by R2 is preferably 3 to 16, and more preferably 6 to 14.

[0018] Preferable specific examples of the compound represented by the formula (1) include the following.

[0019] [ka]

[0020] [ka]

[0021] The compound represented by the above formula (1) can be produced, for example, as follows. 1,5-Dichloroanthraquinone and 4-hydroxybenzenethiol are stirred in an organic solvent, a base such as potassium carbonate is added, and the mixture is heated to 60 to 100°C. The resulting compound, the corresponding carboxylic acid, and dicyclohexylcarbodiimide are dissolved in dichloromethane, 4-dimethylaminopyridine is added, and the mixture is stirred at room temperature. Then, purification is performed by silica gel column chromatography.

[0022] The yellow dichroic dye of the present invention containing the compound represented by the above formula (1) may or may not contain a yellow dichroic dye other than the compound represented by formula (1). The yellow dichroic dye that can be used in combination with the compound represented by formula (1) is not particularly limited as long as it is a yellow dichroic dye. The content of the compound represented by formula (1) in the yellow dichroic dye of the present invention 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 from 50 mass % to 100 mass % (or less), more preferably from 70 mass % to 100 mass % (or less), and even more preferably from 80 mass % to 100 mass % (or less).

[0023] The light-modulating liquid crystal composition of the present invention (hereinafter also simply referred to as "the composition of the present invention") contains a yellow dichroic dye containing an anthraquinone compound represented by formula (1) and a liquid crystal material.

[0024] The content ratio of the yellow dichroic dye (containing the anthraquinone compound represented by formula (1) and optionally other yellow dichroic dyes) in the composition of the present invention is not particularly limited, but is preferably 0.5 to 10 parts by mass, and more preferably 2 to 7 parts by mass, relative to 100 parts by mass of the liquid crystal material. In some cases, this content ratio is even more preferably 2 to 5 parts by mass, or 2 to 4 parts by mass. When a dichroic dye other than yellow (described later) is used in combination, it is preferable that the total content of the yellow dichroic dye and the dichroic dye other than yellow is in the above-mentioned range (e.g., 0.5 to 10 parts by mass).

[0025] The liquid crystal material contained in the composition of the present invention is not particularly limited as long as it is a material (a compound having liquid crystal properties) having liquid crystal properties such as nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, etc. Examples of the compound having liquid crystal properties include the liquid crystal compounds described in pages 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, 1989).

[0026] The photocurable compound that can be used in combination with the composition of the present invention is not particularly limited as long as it is a compound having a functional group (single or multiple in one molecule) that can be polymerized by the action of a photopolymerization initiator described below when irradiated with light. As the photocurable compound, it is preferable to use in combination both a monofunctional monomer having one polymerizable functional group in one molecule and a bifunctional monomer having two polymerizable functional groups. Examples of compounds having a functional group that can be polymerized 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 preferred 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".

[0027] The mono(meth)acrylate compound is preferably a mono(meth)acrylate having a linear or branched alkyl group having 5 to 13 carbon atoms. 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, 2-propylheptyl(meth)acrylate, and isobornyl(meth)acrylate.

[0028] As the di(meth)acrylate compound, for example, 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, 1,13-tridecanediol di(meth)acrylate, and triethylene glycol di(meth)acrylate are suitably used.

[0029] When a mono(meth)acrylate compound and a di(meth)acrylate compound are used in combination in the composition of the present invention, the mass ratio of the mono(meth)acrylate compound:di(meth)acrylate compound is preferably 0.5:9.5 to 9.5:0.5, and more preferably 5:5 to 9:1.

[0030] The photopolymerization initiator that can be used in combination with the composition of the present invention is not particularly limited as long as it is a compound that can polymerize a photocurable compound by irradiation with light. As the photopolymerization initiator, one that does not remain in the cured liquid crystal composition after irradiation with light and does not cause deterioration of the dichroic dye, etc. is preferable. 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 (all of the examples are manufactured by BASF).

[0031] The mixing ratio of the total of the yellow dichroic dye containing the anthraquinone compound represented by formula (1) and the liquid crystal material to the photocurable compound in the composition of the present invention is preferably 90:10 to 50:50 by mass, more preferably 80:20 to 50:50, and even more preferably 60:40 to 50:50. By setting the mixing ratio of the photocurable compound within the above range, it is possible to prevent separation of the liquid crystal material and the photocurable compound before curing by light irradiation and a decrease in the light-shielding property of the cured product. Incidentally, even when a dichroic dye other than yellow is used in combination, the blending ratio of the total of all dichroic dyes and liquid crystal material contained in the composition of the present invention to the photocurable compound is preferably within the above-mentioned range (mass ratio of 90:10 to 50:50), and the more preferable and even more preferable ranges are the same as those described above.

[0032] The content of the photopolymerization initiator in the liquid crystal composition of the present invention is preferably about 0.1 to 5 parts by mass based on 100 parts by mass of the photocurable compound.

[0033] In addition to the yellow dichroic dye, liquid crystal material, photocurable compound and photopolymerization initiator of the present invention, the liquid crystal composition of the present invention may contain (or may not contain) dichroic dyes other than yellow, such as red dichroic dyes and blue dichroic dyes, or optically active substances that exhibit or do not exhibit a liquid crystal phase, such as cholesteryl nonanoate, light stabilizers such as benzotriazoles, benzophenones and hindered amines, antioxidants such as phosphites and hindered phenols, thermal polymerization inhibitors, thiol compounds, photosensitizers, photosensitizers, ultraviolet absorbers, chain transfer inhibitors, polymerization inhibitors, antioxidants, adhesion promoters, defoamers, crosslinking agents, surfactants, heat curing accelerators, thermoplastic resins, thermosetting resins, thickeners such as urethane diacrylate, etc. The use of a red dichroic dye and a blue dichroic dye in combination to form a black light-adjusting liquid crystal composition is a preferred embodiment from the viewpoint of improving the contrast of the light-adjusting element when light is blocked. In order to control the cell gap as a light control element, a spherical or cylindrical spacer 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.

[0034] The dichroic dyes other than yellow, such as red dichroic dyes and blue dichroic dyes, that can be used in combination with the liquid crystal composition of the present invention 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, etc. Specific examples include those described in "Dichroic dyes for Liquid Crystal Display" (AVIvashchenko, 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 anthraquinone dye in combination.

[0035] When a dichroic dye other than yellow is used in combination, the content of the yellow dichroic dye in the total dichroic dyes is not particularly limited as long as the effects of the present invention are not impaired. The content of the yellow dichroic dye in the combined use is preferably 1 to 80% by mass, more preferably 5 to 70% by mass, and even more preferably 10 to 50% by mass.

[0036] The light-modulating liquid crystal composition of the present invention can be obtained by mixing and stirring the essential components of the yellow dichroic dye and liquid crystal material, and optional components such as a photocurable compound and a photopolymerization initiator, which are added as necessary. The mixing and stirring can be carried out most simply by putting all the components in a container and stirring manually, but it is more effective to use a device such as a magnetic stirrer for stirring.

[0037] By irradiating the liquid crystal composition of the present invention containing a photocurable compound and a photopolymerization initiator with light, a cured product of the light-controlling liquid crystal composition in which the photocurable compound component is cured (polymerized) is obtained. Note that the "cured product" in the present invention means a state in which the functional group of the photocurable compound is polymerized or copolymerized by irradiation with light, and does not necessarily mean a cured product in which the anthraquinone dye, liquid crystal material, etc. have contributed to the curing reaction. The light source for irradiating light is not particularly limited as long as it is capable of irradiating light with a wavelength that is absorbed by the photopolymerization initiator. Preferred examples of the light source include a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, and a halogen lamp capable of irradiating ultraviolet light.

[0038] The light-adjusting element of the present invention is formed by sandwiching a thin film layer formed from a cured product of the light-adjusting liquid crystal composition of the present invention between a pair of substrates arranged facing each other, at least one of which is a transparent substrate having a transparent electrode. Examples of the material of the substrate include glass, quartz, metal, metal oxide, semiconductor, ceramic, and organic polymer materials. The material of the substrate may be a composite material obtained by combining the materials listed here with a filler, reinforcing fiber, or the like. The shape of the substrate may be a plate or a film.

[0039] The electrode is a conductive thin film formed on the entire surface or part of the substrate by, for example, a coating method, a printing method, or deposition such as sputtering using a metal oxide, a metal, a semiconductor, or an organic conductive substance. The electrode formed on the substrate can also be partially etched. In terms of efficiently producing a large-area light control element, it is preferable to use an electrode substrate in which an ITO (indium oxide, tin oxide) electrode is formed on a transparent polymer film such as PET by deposition such as sputtering or a printing method. The substrate may be provided with wiring for connecting the electrodes or for connecting the electrodes to an external device. The substrate may be, for example, a segment driving electrode substrate, a matrix driving electrode substrate, or an active matrix driving electrode substrate. Furthermore, a protective film or an alignment film made of an organic compound such as polyimide, polyamide, silicon, or a cyanide compound, an inorganic compound such as SiO2, TiO2, or ZrO2, or a mixture thereof, may be provided on the electrode surface provided on the substrate. EXAMPLES

[0040] The present invention will be described in detail below with reference to examples. In the text, "parts" and "%" are by weight unless otherwise specified. The maximum absorption wavelength in the examples is a value measured using a spectrophotometer "UV-3150 manufactured by Shimadzu Corporation."

[0041] Example 1 (Synthesis of the compound represented by formula (1) of the present invention) (Step 1) Synthesis of an intermediate compound represented by the following formula (2) 5.5 parts of 1,5-dichloroanthraquinone and 8.2 parts of potassium carbonate were added to 20 parts of DMF, and a DMF solution of 7.5 parts of 4-hydroxybenzenethiol was added dropwise at 25°C, followed by stirring at the same temperature for 4 hours. The resulting reaction solution was added to an aqueous hydrochloric acid solution, filtered, washed with water, and dried in a hot air dryer at 80°C for 24 hours to obtain 5.7 parts of an intermediate compound represented by the following formula (2) as an orange solid. The yield was 98%.

[0042] [ka]

[0043] (Step 2) Synthesis of the compound of the present invention represented by the above specific example No. 2 After mixing 2.3 parts of the intermediate compound represented by formula (2) obtained in step 1, 40 parts of dichloromethane, 0.3 parts of 4-dimethylaminopyridine, and 4.2 parts of 2-hexyldecanoic acid, a dichloromethane solution of 3.4 parts of N,N'-dicyclohexylcarbodiimide was added dropwise at 25°C, and the mixture was stirred at the same temperature for 3 hours. After the reaction was completed, the solvent was distilled off under reduced pressure, methanol was added to the resulting residue, and the mixture was filtered and then dried in a hot air dryer at 80°C for 24 hours. The obtained crude product was dissolved in toluene, passed through a short column, the solvent was distilled off under reduced pressure, and dried in a hot air dryer at 80°C for 24 hours to obtain 3.5 parts of the compound represented by No. 2 of the above specific example as an orange solid. The yield was 82%. The overall yield of steps 1 and 2 was 80%.

[0044] Example 2 (Synthesis of the compound represented by formula (1) of the present invention) (Step 3) Synthesis of the compound of the present invention represented by the above specific example No. 3 After mixing 2.3 parts of the intermediate compound represented by formula (2) obtained in step 1 of Example 1, 40 parts of dichloromethane, 0.3 parts of 4-dimethylaminopyridine, and 3.2 parts of 2-ethylhexanoic acid, a dichloromethane solution of 3.4 parts of N,N'-dicyclohexylcarbodiimide was added dropwise at 25°C, and the mixture was stirred at the same temperature for 3 hours. After the reaction was completed, the solvent was distilled off under reduced pressure, methanol was added to the resulting residue, and the mixture was filtered and then dried in a hot air dryer at 80°C for 24 hours. The obtained crude product was dissolved in toluene, passed through a short column, the solvent was distilled off under reduced pressure, and dried in a hot air dryer at 80°C for 24 hours to obtain 2.5 parts of the compound represented by No. 3 of the above specific example as an orange solid. The yield was 84%. The overall yield of steps 1 and 3 was 82%.

[0045] Comparative Example 1 (Synthesis of Comparative Example Compound) The compound represented by No. 4 in Table 1 of Patent Document 5 (compound represented by the following formula (A)) was obtained by the synthesis method described in H. Iwanaga et al. / Journal of Molecular Structure 975 (2010) 110-114. The yield was 30%. It is clear that symmetric compounds such as those of the present invention can be produced easily and with a good yield.

[0046] [ka]

[0047] Comparative Example 2 (Synthesis of Comparative Example Compound) Except for using 11.8 parts of palmitic acid instead of 2-hexyldecanoic acid, the same procedure as in step 2 of Example 1 was performed to obtain 7.8 parts of a compound represented by the following formula (B) as an orange solid.

[0048] [ka]

[0049] Comparative Example 3 (Synthesis of Comparative Compound) The same procedure as in step 2 of Example 1 was carried out except for using 5.9 parts of n-octanoic acid instead of 2-hexyldecanoic acid, to obtain 3.9 parts of a compound represented by the following formula (C) as an orange solid.

[0050] [ka]

[0051] Comparative Example 4 (Synthesis of Comparative Example Compound) Except for using 6.6 parts of 3,5,5-trimethylhexanoic acid instead of 2-hexyldecanoic acid, the same procedure as in step 2 of Example 1 was performed to obtain 4.4 parts of a compound represented by the following formula (D) as an orange solid.

[0052] [ka]

[0053] Comparative Example 5 (Synthesis of Comparative Compound) Except for using 7.3 parts of 4-methylnonanoic acid instead of 2-hexyldecanoic acid, the procedure was repeated in the same manner as in step 2 of Example 1 to obtain 4.9 parts of a compound represented by the following formula (E) as an orange solid.

[0054] [ka]

[0055] Example 3 (Preparation of the composition of the present invention) 0.003 parts of the compound represented by No. 2 of the specific example obtained in Example 1 and liquid crystal materials (0.306 parts of 1-cyano-4'-n-pentylbiphenyl, 0.15 parts of 1-cyano-4'-n-heptylbiphenyl, 0.096 parts of 1-cyano-4'-n-octyloxybiphenyl, and 0.048 parts of 1-cyano-4''-n-pentylterphenyl) were mixed at room temperature to prepare a liquid crystal composition of the present invention.

[0056] Example 4 and Comparative Examples 6 to 10 (Preparation of compositions of the present invention and for comparison) The compositions of the present invention and the comparative compositions were prepared in accordance with Example 3, except that the compound represented by specific example No. 2 obtained in Example 1 was changed to the compound represented by specific example No. 3 obtained in Example 2, the compound represented by formula (A) obtained in Comparative Example 1, the compound represented by formula (B) obtained in Comparative Example 2, the compound represented by formula (C) obtained in Comparative Example 3, the compound represented by formula (D) obtained in Comparative Example 4, and the compound represented by formula (E) obtained in Comparative Example 5, respectively.

[0057] Examples 5 and 6 and Comparative Examples 11 to 15 (Preparation of light control elements of the present invention and comparative examples) The compositions obtained in Examples 3 and 4 and Comparative Examples 6 to 10 were filled into elements having transparent electrodes, two glass substrates, one above the other, which had been subjected to homogeneous alignment treatment by rubbing a polyamide resin on the surface in contact with the liquid crystal, and a gap between the substrates of 15 μm. In the elements subjected to the above alignment treatment, when no voltage was applied, the liquid crystal was in a homogeneous alignment state, and the dye molecules were also aligned in the same manner according to the host liquid crystal.

[0058] (Evaluation of solubility of the compound of the present invention and the comparative compound in liquid crystal materials) 0.003 parts of the compound represented by No. 2 was added to the composition obtained in Example 3, and the mixture was stirred at room temperature for 1 hour, after which the appearance of the composition was visually confirmed. If a homogeneous composition without insolubles was obtained, 0.003 parts of the compound represented by No. 2 was further added, and the mixture was stirred at room temperature for 1 hour, after which the appearance of the composition was visually confirmed. This procedure was repeated until the dissolved amount (see below) reached about 4.5 mass %, and the solubility of the compound represented by No. 2 in the liquid crystal material was evaluated based on the maximum amount added at which a homogeneous composition without insolubles was obtained. The results are shown in Table 1.

[0059] The mass ratio and dissolution amount of the compound represented by No. 2 relative to the liquid crystal material in the composition of Example 3, and the mass ratio and dissolution amount of the compound represented by No. 2 relative to the liquid crystal material after further adding the compound represented by No. 2, are as follows. Mass ratio and dissolved amount of the compound in Example 3: about 0.5 mass% (0.003 parts) Mass ratio and dissolution amount after adding 0.003 parts in total: Approximately 1.0 mass% (0.006 parts) Mass ratio and dissolution amount after adding 0.006 parts in total: Approximately 1.5% by mass (0.009 parts) Mass ratio and dissolution amount after adding 0.009 parts in total: Approximately 2.0 mass% (0.012 parts) Mass ratio and dissolution amount after adding 0.012 parts in total: Approximately 2.5 mass% (0.015 parts) Mass ratio and dissolution amount after adding 0.015 parts in total: Approximately 3.0 mass% (0.018 parts) Mass ratio and dissolution amount after adding 0.018 parts in total: Approximately 3.5% by mass (0.021 parts) Mass ratio and dissolution amount after adding 0.021 parts in total: Approximately 4.0 mass% (0.024 parts) Mass ratio and dissolution amount after adding 0.024 parts in total: Approximately 4.5 mass% (0.027 parts) (Supplementary Note) For example, if a homogeneous composition without insoluble matter was obtained after adding a total of 0.009 parts of the compound and stirring, and if insoluble matter remained after adding 0.003 parts of the compound and stirring, the maximum dissolution amount was determined to be 2.0% by mass. If a homogeneous composition without insoluble matter was obtained even after adding 0.024 parts of the compound, the maximum dissolution amount was provisionally determined to be "about 4.5% by mass." In addition, instead of using the composition obtained in Example 3 containing the compound represented by No. 2, the compositions obtained in Example 4 and Comparative Examples 6 to 10 containing No. 3 and the compounds represented by formulae (A) to (E), respectively, were used to evaluate the solubility of the compounds in the liquid crystal material in the same manner as above. The results are shown in Table 1.

[0060] (Contrast Evaluation of the Composition of the Present Invention and the Comparative Example Composition) The transmittance (Ky) of the cell filled with the composition obtained in the above "Evaluation of the solubility of the compound of the present invention and the compound of the comparative example in the liquid crystal material" was measured for linearly polarized light parallel to the alignment direction and for linearly polarized light perpendicular to the alignment direction, and the contrast (C) at the absorption peak wavelength (λmax) was calculated from the following formula. The results are shown in Table 1. C=Ky / Kz

[0061] [Table 1]

[0062] As shown in Table 1, the compound of the present invention having a branch at the α-position of the carbonyl group has higher solubility in liquid crystal materials than the compounds of the comparative examples, and the content of the dye compound (dichroic dye) in the light-adjusting liquid crystal composition can be increased. Therefore, it was found that the contrast of the light-adjusting element obtained by using the composition of the present invention can be increased.

[0063] Example 7 (Preparation of a composition of the present invention) 0.467 parts of isobornyl acrylate (Osaka Organic Chemical Industry Co., Ltd.) as a monofunctional monomer of the photocurable compound, 0.024 parts of triethylene glycol dimethacrylate (Shin-Nakamura Chemical Co., Ltd.) as a bifunctional monomer of the photocurable compound, 0.255 parts of 1-cyano-4'-n-pentylbiphenyl, 0.125 parts of 1-cyano-4'-n-heptylbiphenyl, 0.080 parts of 1-cyano-4'-n-octyloxybiphenyl and 1-cyano-4''- 0.040 parts of n-pentyl terphenyl, 0.005 parts of Irgacure TPO (manufactured by BASF) and 0.005 parts of Irgacure 184 (manufactured by BASF) as photopolymerization initiators, and 0.005 parts of the compound represented by No. 2 of the specific example obtained in Example 1 as a yellow dichroic dye were stirred at room temperature for 2 hours to prepare a composition of the present invention (the content of the compound represented by No. 2 (dichroic dye) relative to the liquid crystal material, photocurable compound, and photopolymerization initiator is approximately 0.5% by mass).

[0064] Example 8 and Comparative Examples 16 to 20 (Preparation of Liquid Crystal Compositions of the Present Invention and Comparative Examples) The composition of the present invention and the comparative composition were obtained in the same manner as in Example 7, except that the compound represented by the above specific example No. 2 obtained in Example 1 was changed to the compound represented by the above specific example No. 3 obtained in Example 2, the compound represented by formula (A) obtained in Comparative Example 1, the compound represented by formula (B) obtained in Comparative Example 2, the compound represented by formula (C) obtained in Comparative Example 3, the compound represented by formula (D) obtained in Comparative Example 4, and the compound represented by formula (E) obtained in Comparative Example 5, respectively.

[0065] (Evaluation of solubility of the compound of the present invention and the comparative compound in liquid crystal materials, photocurable compounds, and photopolymerization initiators) 0.005 parts of the compound represented by No. 2 was added to the composition obtained in Example 7, and the composition was stirred at room temperature for 1 hour, and the appearance of the composition was visually confirmed. If a homogeneous composition without insoluble matter was obtained, 0.005 parts of the compound represented by No. 2 was further added, and the composition was stirred at room temperature for 1 hour, and the appearance of the composition was visually confirmed. This procedure was repeated until the dissolved amount (see below) reached about 3.5 mass%, and the solubility of the compound represented by No. 2 in the liquid crystal material, the photocurable compound, and the photopolymerization initiator was evaluated based on the maximum amount added at which a homogeneous composition without insoluble matter was obtained. The results are shown in Table 2.

[0066] The mass ratio and dissolution amount of the compound represented by No. 2 relative to the liquid crystal material, photocurable compound, and photopolymerization initiator in Example 7, as well as the mass ratio and dissolution amount of the compound represented by No. 2 relative to the liquid crystal material, photocurable compound, and photopolymerization initiator after further adding the compound represented by No. 2, are as follows. Mass ratio and dissolved amount of the compound in Example 7: about 0.5% by mass (0.005 parts by mass) Mass ratio and dissolved amount of compound after adding 0.005 parts in total: Approximately 1.0% by mass (0.010 parts by mass) Mass ratio and dissolved amount of compound after adding 0.010 parts in total: Approximately 1.5% by mass (0.015 parts by mass) Mass ratio and dissolved amount of compound after adding 0.015 parts in total: Approximately 2.0% by mass (0.020 parts by mass) Mass ratio and dissolved amount of compound after adding 0.020 parts in total: Approximately 2.5% by mass (0.025 parts by mass) Mass ratio and dissolved amount of compound after adding 0.025 parts in total: Approximately 3.0% by mass (0.030 parts by mass) Mass ratio and dissolved amount of compound after adding 0.030 parts in total: Approximately 3.5% by mass (0.035 parts by mass) (Supplementary Note) For example, if a homogeneous composition without insoluble matter was obtained after adding a total of 0.020 parts of the compound and stirring, and if insoluble matter remained after adding 0.005 parts of the compound and stirring, the maximum dissolution amount was determined to be 2.5% by mass. If a homogeneous composition without insoluble matter was obtained even after adding 0.030 parts of the compound, the maximum dissolution amount was provisionally determined to be "about 3.5% by mass." In addition, instead of using the composition containing the compound represented by No. 2 obtained in Example 7, the compositions containing No. 3 and the compounds represented by formulas (A) to (E) obtained in Example 8 and Comparative Examples 16 to 20 were used to evaluate the solubility of the compounds in the liquid crystal material, the photocurable compound, and the photopolymerization initiator in the same manner as above. The results are shown in Table 2.

[0067] Examples 9 and 10 and Comparative Examples 21 to 25 (Preparation of light control elements of the present invention and comparative examples) A spacer agent having a diameter of 20 μm (Micropearl (registered trademark) SP220 manufactured by Sekisui Chemical Co., Ltd.) of 0.010 parts was mixed at room temperature with the composition having a uniform maximum solubility without insoluble matter obtained in the above "Evaluation of solubility of the compound of the present invention and the compound of the comparative example in liquid crystal material, photocurable compound, and photopolymerization initiator". The composition containing the spacer agent was applied to the ITO film of a 5 cm square PET film having an ITO film using an applicator, and then a 5 cm square PET film having the same ITO film as above was superimposed so that the composition layer provided on the ITO film obtained above faces the ITO film. The laminate of the two films and the composition obtained above was heated to 23° C. on a thermoplate and heated to 9 mW / cm 3 at a light intensity of 365 nm from an LED lamp. 2 The photocurable compound component was photocured by irradiating it with light for 1 minute, thereby obtaining light control elements of the present invention and a comparative example.

[0068] (Spectral characteristics of light control element) For the light control elements obtained in Examples 9 and 10 and Comparative Examples 21 to 25, the transmittance T (0 V) at the absorption peak wavelength (λmax) when no voltage was applied was measured using a spectrophotometer. The results are shown in Table 2.

[0069] [Table 2]

[0070] As shown in Table 2, the compound of the present invention having a branch at the α-position of the carbonyl group has higher solubility in liquid crystal materials, photocurable compounds, and photopolymerization initiators than the compounds of the comparative examples, and the content of the dye compound (dichroic dye) in the light-adjusting liquid crystal composition could be increased. Therefore, it was found that the light-adjusting element obtained using the composition of the present invention has a lower transmittance at the absorption peak wavelength (λmax) when no voltage is applied (when the light-adjusting element is shielded) than the light-adjusting element of the comparative examples, and the contrast can be increased.

[0071] Example 11 (Preparation of black light control element) 0.013 parts of the compound (yellow dichroic dye) represented by No. 2 of the specific example obtained in Example 1, 0.007 parts of a blue dichroic dye represented by the following formula (X), 0.006 parts of a red dichroic dye represented by the following formula (Y), 0.467 parts of isobornyl acrylate (manufactured by Osaka Organic Chemical Industry, monoacrylate), 0.024 parts of triethylene glycol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), 0.255 parts of 1-cyano-4'-n-pentylbiphenyl, 1-cyano-4' 0.125 parts of 1-n-heptylbiphenyl, 0.080 parts of 1-cyano-4'-n-octyloxybiphenyl, 0.040 parts of 1-cyano-4''-n-pentylterphenyl, 0.005 parts of Irgacure TPO (manufactured by BASF), 0.005 parts of Irgacure 184 (manufactured by BASF), and 0.010 parts of a spacer agent having a diameter of 20 μm (Micropearl (registered trademark) SP220 manufactured by Sekisui Chemical Co., Ltd.) were mixed at room temperature to prepare a light control liquid crystal composition of the present invention. The light control liquid crystal composition was applied onto the ITO film of a 5 cm square PET film having an ITO film using an applicator, and a 5 cm square PET film having the same ITO film as above was overlaid so that the composition layer on the ITO film and the ITO film faced each other. Then, using an LED lamp manufactured by ITEC Systems Co., Ltd., a light intensity of 9 mW / cm at 365 nm was measured. 2 The sample was set on a thermoplate so as to keep the sample temperature at 23° C. in a position where the temperature became equal to or higher than 100° C., and the sample was irradiated with light for 1 minute to photocure the photocurable compound component, thereby obtaining a black light-adjusting element.

[0072] [ka]

[0073] Example 12 (Preparation of black light control element) A black photochromic element was obtained in the same manner as in Example 11, except that the compound represented by specific example No. 2 was replaced with the compound represented by specific example No. 3 (yellow dichroic dye) obtained in Example 2. [Industrial Applicability]

[0074] The light-adjusting liquid crystal composition of the present invention can stably maintain a high dye concentration at room temperature and low temperatures, and a light-adjusting element having excellent solubility and contrast can be obtained by using the composition. The light-adjusting element obtained by the present invention can be used for building materials such as windows, partitions, and doors, in-vehicle materials such as windows and sunroofs, displays that show letters and numbers, and materials for exhibits such as show windows.

Claims

1. The following formula (1) 【Chemistry 1】 (In formula (1), R １ represents an alkyl group having 1 to 9 carbon atoms; R ２ Each represents an alkyl group having 1 to 8 carbon atoms. A compound represented by the formula:

2. R １ The number of carbon atoms in the alkyl group represented by R ２ The compound according to claim 1, wherein the total number of carbon atoms in the alkyl group represented by is 6 to 14.

3. R １ is an alkyl group having 4 to 8 carbon atoms; R ２ The compound according to claim 2, wherein is an alkyl group having 2 to 6 carbon atoms.

4. A yellow dichroic dye comprising the compound represented by formula (1) according to claim 1.

5. A light-adjusting liquid crystal composition comprising the yellow dichroic dye according to claim 4 and a liquid crystal material.

6. The light-adjusting liquid crystal composition according to claim 5 , further comprising a photocurable compound and a photopolymerization initiator.

7. The light-adjusting liquid crystal composition according to claim 5 or 6, further comprising a red dichroic dye and a blue dichroic dye.

8. A cured product of the light-modulating liquid crystal composition according to claim 6 or 7.

9. A light-adjusting element comprising a pair of substrates, at least one of which is a transparent substrate having a transparent electrode, and the light-adjusting liquid crystal composition according to claim 5 or the cured product according to claim 8 sandwiched between the pair of substrates.

10. 10. The light control element according to claim 9, wherein both of the pair of substrates are transparent substrates having transparent electrodes.

11. 11. The light control element according to claim 9, wherein the light control element is mounted on a vehicle.

12. The light control element according to claim 9 or 10, which is used for building materials.

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