Anthraquinone compound, liquid crystal composition containing said compound, and light control element

Abstract

The present invention relates to an anthraquinone compound represented by formula (1) (in the formula, R1 represents a hydrogen atom, a C1-14 linear or branched alkyl group, or a C1-14 linear or branched alkoxy group. R2 represents a hydrogen atom, a C1-16 linear or branched alkyl group, or a C1-16 linear or branched alkoxy group. n represents 1-3 carbon atoms.). R1 may be a C1-8 linear or branched alkyl group or a C1-8 linear or branched alkoxy group. R2 may be a C1-10 linear or branched alkyl group or a C1-10 linear or branched alkoxy group.

Description

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

[0001] The present invention relates to a novel anthraquinone compound, a liquid crystal composition containing the compound, and a light-adjusting element.

[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 used in automobile windowpanes, such light-controlling panels are required to provide clear visibility without fogging when transparent, high contrast, and light resistance that prevents a decrease in transmittance even when exposed to light at high temperatures for long periods of time due to long-term exposure to light during outdoor use. Furthermore, there is a growing 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 devices called GH (guest-host) type devices using liquid crystal compositions containing dyes have been proposed. These liquid crystal display devices, which are characterized by their viewing angle, brightness, etc., have also been put to practical use in automotive applications and as light control devices.

[0004] Dichroic dyes commonly used in liquid crystal compositions for light-control devices are required to not only provide high contrast when used in a device, but also to have 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, a dichroic dye that can block more visible light and has a lower transmittance when blocking light is required. Generally, increasing the amount of dye added reduces transmittance when blocking light, but increasing the amount of dye reduces solubility and reduces contrast when used in a device. To improve light-blocking performance with a smaller amount of dye, the color-developing power of the dye itself is important. For example, Patent Documents 4 and 5 disclose dichroic dyes with a maximum absorption wavelength in the range of 500 to 550 nm. However, the dyes in these documents either have high color development but insufficient contrast, or sufficient contrast but insufficient color development. No dichroic dyes have been found that have a maximum absorption wavelength in the above range, have high color development per se, and provide excellent contrast in a device.

[0005] JP 63-501512, JP 03-47392, JP 2018-205746, JP 2011-190314, JP 04-264193

[0006] One object of the present invention is to provide an anthraquinone compound which is a dichroic dye having a novel structure. Another object of the present invention is to provide an anthraquinone compound which is a dichroic dye having a novel structure, which has an absorption maximum in a specific wavelength region and excellent color-developing properties. Yet another object of the present invention is to provide a liquid crystal composition containing an anthraquinone compound which is a dichroic dye having a novel structure, which has an absorption maximum in a specific wavelength region and excellent color-developing properties, and a light-controlling device which contains the composition and has excellent contrast.

[0007] As a result of extensive research, the present inventors have succeeded in developing a novel anthraquinone compound having a specific structure. Furthermore, the present inventors have discovered that the above-mentioned problems can be solved by using this anthraquinone compound, and have thus completed the present invention. Specifically, various aspects or embodiments of the present invention are as follows: [1]. A compound represented by the following formula (1): (In the formula, R １ represents a hydrogen atom, a linear or branched alkyl group having 1 to 14 carbon atoms, or a linear or branched alkoxy group having 1 to 14 carbon atoms. ２ represents a hydrogen atom, a linear or branched alkyl group having 1 to 16 carbon atoms, or a linear or branched alkoxy group having 1 to 16 carbon atoms; and n represents a carbon number of 1 to 3. [2]. R １ [3]. The anthraquinone compound according to the above item [1], wherein R is a linear or branched alkyl group having 1 to 8 carbon atoms. １ [4]. The anthraquinone compound according to the above item [2], wherein R is a linear or branched alkyl group having 2 to 6 carbon atoms. １ [5]. The anthraquinone compound according to the above item [1], wherein R is a linear or branched alkoxy group having 1 to 8 carbon atoms. ２ [6]. The anthraquinone compound according to the above item [1], wherein R is a linear or branched alkyl group having 1 to 10 carbon atoms. ２ is a straight-chain or branched-chain alkoxy group having 1 to 10 carbon atoms. [7]. The anthraquinone compound according to any one of the preceding items [1] to [6], having a maximum absorption wavelength in the range of 500 to 550 nm. [8]. A light-controlling liquid crystal composition containing the anthraquinone compound according to any one of the preceding items [1] to [7] and a liquid crystal material. [9]. The light-controlling liquid crystal composition according to the preceding item [8], further containing a dye compound other than the anthraquinone compound represented by formula (1).

[10] . A light-controlling element comprising a pair of opposing substrates, at least one of which is a transparent substrate having a transparent electrode, and the light-controlling liquid crystal composition according to the preceding item [8] or [9] sandwiched between them.

[0008] The anthraquinone compound of the present invention, which has a maximum absorption wavelength in a specific wavelength region, has high color-developing properties, and by using a light-modulating liquid crystal composition containing the anthraquinone compound, a light-modulating element having excellent contrast can be obtained.

[0009] The present invention will be described in detail below. The anthraquinone compound of the present invention is represented by the following formula (1).

[0010]

[0011] In formula (1), R １ represents a hydrogen atom, a linear or branched alkyl group having 1 to 14 carbon atoms, or a linear or branched alkoxy group having 1 to 14 carbon atoms. １ The alkyl group having 1 to 14 carbon atoms represented by may be either linear or branched. Specific examples thereof 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, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a 2-ethylhexyl group, a 2-propylhexyl group, a 2-butylhexyl group, a 2-pentylhexyl group, a 2-pentylheptyl group, and a 2-pentylnonyl group. The linear alkyl group preferably has 1 to 8 carbon atoms, more preferably 2 to 7, still more preferably 2 to 6, and still more preferably 2 to 4. The branched alkyl group preferably has 3 to 6 carbon atoms, and more preferably 3 or 4 carbon atoms.

[0012] R in formula (1) １The alkoxy group having 1 to 14 carbon atoms represented by may be either a straight chain or a branched chain. Specific examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, an n-butoxy group, an iso-butoxy group, a sec-butoxy group, a t-butoxy group, an n-pentyloxy group, an iso-pentyloxy group, a neo-pentyloxy group, a t-pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, an undecyloxy group, a dodecyloxy group, a tridecyloxy group, a tetradecyloxy group, a 2-ethylhexyloxy group, a 2-propylhexyloxy group, a 2-butylhexyloxy group, a 2-pentylhexyloxy group, a 2-pentylheptyloxy group, and a 2-pentylnonyloxy group. Among these, a linear or branched alkoxy group having 1 to 8 carbon atoms is preferred, a linear or branched alkoxy group having 3 to 8 carbon atoms is more preferred, a linear or branched alkoxy group having 3 to 6 carbon atoms is even more preferred, a linear alkoxy group having 3 to 6 carbon atoms is even more preferred, and a linear alkoxy group having 3 to 5 carbon atoms is even more preferred.

[0013] R in formula (1) １ As the alkyl group, a linear alkyl group having 1 to 8 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, or a linear or branched alkoxy group having 1 to 8 carbon atoms is preferred, a branched alkyl group having 3 or 4 carbon atoms, or a linear or branched alkoxy group having 3 to 6 carbon atoms is more preferred, a linear alkyl group having 2 to 6 carbon atoms, or a linear alkoxy group having 3 to 6 carbon atoms is even more preferred, and a linear alkyl group having 2 to 4 carbon atoms, or a linear alkoxy group having 3 to 5 carbon atoms is even more preferred.

[0014] In formula (1), R ２ represents a hydrogen atom, a linear or branched alkyl group having 1 to 16 carbon atoms, or a linear or branched alkoxy group having 1 to 16 carbon atoms.

[0015] R in formula (1) ２The alkyl group having 1 to 16 carbon atoms represented by may be either a straight chain or a branched chain, and specific examples thereof 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, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a 2-ethylhexyl group, a 2-propylhexyl group, a 2-butylhexyl group, a 2-pentylhexyl group, a 2-pentylheptyl group, and a 2-heptylnonyl group. A linear or branched alkyl group having 1 to 10 carbon atoms is preferred, a linear alkyl group having 2 to 8 carbon atoms is more preferred, and a linear alkyl group having 4 to 7 carbon atoms is even more preferred.

[0016] R in formula (1) ２ The alkoxy group having 1 to 16 carbon atoms represented by may be either a straight chain or a branched chain. Specific examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, an iso-butoxy group, a sec-butoxy group, a t-butoxy group, an n-pentyloxy group, an iso-pentyloxy group, a neo-pentyloxy group, a t-pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, an undecyloxy group, a dodecyloxy group, a tridecyloxy group, a tetradecyloxy group, a pentadecyloxy group, a hexadecyloxy group, a 2-ethylhexyloxy group, a 2-propylhexyloxy group, a 2-butylhexyloxy group, a 2-pentylhexyloxy group, a 2-pentylheptyloxy group, and a 2-heptylnonyloxy group. A straight-chain alkoxy group having 2 to 8 carbon atoms is more preferred.

[0017] R in formula (1) ２ As the alkyl group, a linear or branched alkyl group having 1 to 10 carbon atoms is preferable, a linear alkyl group or alkoxy group having 2 to 8 carbon atoms is more preferable, and a linear alkyl group having 4 to 7 carbon atoms is even more preferable.

[0018] In formula (1), n ​​represents 1 to 3 carbon atoms, and more preferably 1 carbon atom.

[0019] Specific preferred examples of the compound represented by formula (1) include the following, but the present invention is not limited to these.

[0020]

[0021]

[0022]

[0023]

[0024]

[0025] The compound represented by formula (1) can be synthesized by a conventionally known method described in, for example, WO2023 / 100848A1 and WO2023 / 096111A1. Specifically, for example, an anthraquinone compound represented by formula (A) below and an aniline derivative represented by formula (B) below are reacted in the presence of a catalyst such as palladium or copper powder under basic conditions such as tripotassium phosphate in a solvent such as xylene at 110 to 120°C to obtain a compound represented by formula (C) below. ２ is R in formula (1) ２ It has the same meaning as:

[0026]

[0027] The compound represented by formula (C) obtained above can be brominated to obtain a compound represented by formula (D) below. Thereafter, the compound represented by formula (D) below and the compound represented by formula (E) below are reacted in the presence of a palladium catalyst such as palladium acetate under basic conditions such as potassium carbonate in a solvent such as 1,4-dioxane at 80 to 90°C to obtain an anthraquinone compound represented by formula (1). １ and R ２ and n is R in formula (1). １ and R ２ and n have the same meaning as in the following formula (E): ｐｉｎrepresents a pinacolboryl group.

[0028]

[0029] 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 formula (1) and a liquid crystal material.

[0030] The content ratio of the anthraquinone compound represented by formula (1) in the liquid crystal composition is not particularly limited, but is preferably 0.5 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the liquid crystal material. When a dichroic dye (described later) other than the compound represented by formula (1) is used in combination, the total content of the anthraquinone compound represented by formula (1) and the dichroic dye other than the compound represented by formula (1) is preferably within the above-mentioned range (0.5 to 10 parts by mass relative to 100 parts by mass of the liquid crystal material).

[0031] The liquid crystal material 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 the compound having liquid crystallinity include the liquid crystal compounds described on 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, Ltd., 1989).

[0032] The liquid crystal composition of the present invention may contain an optically active substance that exhibits or does not exhibit a liquid crystal phase, such as a dichroic dye other than the anthraquinone compound represented by formula (1) or cholesteryl nonanoate, various additives such as an ultraviolet absorber and an antioxidant, a photocurable compound, a photopolymerization initiator, and the like.

[0033] The composition of the present invention can use an anthraquinone compound represented by formula (1) in combination with a dichroic dye other than the anthraquinone compound represented by formula (1). The dichroic dye that can be used in combination with the anthraquinone compound represented by formula (1) 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" (A.V. Ivashchenko, CRC, 1994). Among these, it is preferable to use an azo dye, an anthraquinone dye, a perylene dye, or a quinophthalone dye in combination with the anthraquinone compound represented by formula (1), and it is more preferable to use an azo dye or an anthraquinone dye in combination.

[0034] When the anthraquinone compound represented by formula (1) is used in combination with a dichroic dye other than the anthraquinone compound represented by formula (1), the content of the anthraquinone compound represented by formula (1) in the total dichroic dye 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 1 to 90 mass %, more preferably 5 to 70 mass %, and even more preferably 10 to 50 mass %.

[0035] The composition of the present invention may further contain other additives as needed, such as light stabilizers such as benzotriazoles, benzophenones, and hindered amines, antioxidants such as phosphites and hindered phenols, thermal polymerization inhibitors, thiol compounds, photosensitizers, photosensitizers, chain transfer inhibitors, polymerization inhibitors, adhesion promoters, antifoaming agents, crosslinking agents, surfactants, thermosetting accelerators, thermoplastic resins, thermosetting resins, and thickeners such as urethane diacrylate. Furthermore, spherical or cylindrical spacers such as silica, glass, plastic, and ceramic may be added to control the cell gap of the photochromic element. The cell gap of the photochromic element can usually be set in the range of 2 to 100 μm.

[0036] 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 substrate by known coating methods, printing methods, or vapor deposition methods such as sputtering, over the entire surface or in part of the substrate, forming thin films of metal oxides, metals, semiconductors, organic conductive materials, etc., using known coating methods, printing methods, 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 by vapor deposition methods such as sputtering or printing methods, from the standpoints of productivity and processability. Wiring may be provided on the substrate to connect the electrodes or the electrodes to the outside. For example, a segment-drive electrode substrate, a matrix-drive electrode substrate, or an active-matrix drive electrode substrate may be used. Furthermore, the surface of the electrode provided on the substrate is covered with an organic compound such as polyimide, polyamide, silicone, or cyanide, or SiO ２ , TiO ２ , ZrO ２ The entire surface or a part of the surface may be covered with a protective film or an alignment film formed from an inorganic compound such as those mentioned above, or a mixture thereof.

[0037] The use of a plastic film as a substrate allows for the production of a flexible and lightweight light-controlling element. Therefore, the light-controlling 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 light-controlling 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 light-controlling 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 can be provided on the substrate surface opposite the electrode surface of the light-controlling element. A color filter or a polarizer filter can be laminated on the light-controlling element. An electroluminescent display element, a light-emitting diode display element, an electrochromic display element, or another liquid crystal display element can also be laminated on the light-controlling element.

[0038] The driving device for applying a voltage to the light-adjusting element of the present invention may be a device capable of applying a DC voltage of 2 to 100 V or an AC voltage of 10 to 1000 Hz, and which opens or shorts the electrodes when no voltage is applied. The 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.

[0039] The anthraquinone compound of the present invention represented by formula (1) has high color development properties, and a light-controlling element using this compound can realize a high-contrast display. Therefore, this light-controlling element is suitable for use as a construction material such as a window, a partition, or a door, an in-vehicle material such as a window or a sunroof, a display that displays letters and numbers, or a material for exhibits such as a show window.

[0040] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the text, "parts" and "%" are based on mass 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 Anthraquinone Compound of the Present Invention Represented by Specific Example No. 12) (Step 1-1) Synthesis of Intermediate Compound Represented by the Following Formula (3) 0.6 parts of 2,2-bis(diphenylphosphino)-1,1-binaphthyl and 0.22 parts of palladium acetate were added to 80 parts of xylene, and the mixture was stirred at 80°C for 10 minutes under a nitrogen atmosphere. Thereafter, 8.0 parts of a compound represented by the following formula (2), 8.2 parts of tripotassium phosphate, 5.8 parts of 4-n-butylaniline, and 32 parts of N-methyl-2-pyrrolidone were added, and the mixture was stirred at 120°C for 2 hours. The reaction solution was cooled to 45°C, and then 160 parts of methanol was added, followed by stirring for 30 minutes. The reaction product was collected by filtration, washed with methanol, and then dried in a hot air dryer at 80°C for 24 hours, yielding 9.1 parts of an intermediate compound represented by the following formula (3).

[0042]

[0043] (Step 1-2) Synthesis of intermediate compound represented by the following formula (4) 6.51 parts of the compound represented by the above formula (3) was added to 65.1 parts of methanol and stirred for 10 minutes, and then 2.9 parts of 49% hydrobromic acid and 1.71 parts of 35% hydrogen peroxide were added and stirred for 3 hours at 25° C. The reaction product was collected by filtration, washed with methanol, and then dried in a hot air dryer at 80° C. for 24 hours to obtain 5.55 parts of the intermediate compound represented by the following formula (4).

[0044]

[0045] (Step 1-3) Synthesis of Compound Represented by Specific Example No. 12 To 80 parts of 1,4-dioxane and 17 parts of water, 1.9 parts of the compound represented by the above formula (4), 0.7 parts of potassium carbonate, 1.9 parts of the compound represented by the following formula (5), and 0.49 parts of tetrakistriphenylphosphine palladium were added, and the mixture was stirred at 80°C for 3 hours. After the reaction solution was cooled to 30°C, 80 parts of methanol was added, and the mixture was stirred for 30 minutes. The reaction product was collected by filtration, washed with methanol, and then dried in a hot air dryer at 80°C for 24 hours, thereby obtaining 0.7 parts of Compound Represented by Specific Example No. 12. The maximum absorption wavelength of this compound in toluene was 519.5 nm.

[0046]

[0047] Example 2 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 11) 0.7 parts of the compound represented by the above specific example No. 11 was obtained in the same manner as in Example 1, except that the following formula (6) was used instead of the above formula (5). The maximum absorption wavelength of this compound in toluene was 515.8 nm.

[0048]

[0049] Example 3 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 30) 0.7 parts of the compound represented by the above specific example No. 30 was obtained in the same manner as in Example 1, except that 2.1 parts of the following formula (7) was used instead of the above formula (5). The maximum absorption wavelength of this compound in toluene was 514.3 nm.

[0050]

[0051] Example 4 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 17) 0.7 parts of the compound represented by the above specific example No. 17 was obtained in the same manner as in Example 1, except that 5.3 parts of 4-n-heptylaniline were used instead of 4-n-butylaniline and 2.1 parts of the following formula (8) were used instead of the above formula (5) in step 1-1. The maximum absorption wavelength of this compound in toluene was 516.0 nm.

[0052]

[0053] Example 5 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 26) 0.7 parts of the compound represented by the above specific example No. 26 was obtained in the same manner as in Example 1, except that 2.0 parts of the following formula (9) was used instead of the above formula (5). The maximum absorption wavelength of this compound in toluene was 515.0 nm.

[0054]

[0055] Example 6 (Synthesis of an anthraquinone compound of the present invention represented by specific example No. 19) 0.5 parts of the compound represented by the above specific example No. 19 were obtained in the same manner as in Example 1, except that 9.1 parts of 4-n-decylaniline were used instead of 4-n-butylaniline in step 1-1. The maximum absorption wavelength of this compound in toluene was 516.0 nm.

[0056] Example 7 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 38) 0.6 parts of the compound represented by specific example No. 38 was obtained in the same manner as in Example 1, except that 2.3 parts of the following formula (10) was used instead of the above formula (5). The maximum absorption wavelength of this compound in toluene was 515.5 nm.

[0057]

[0058] Example 8 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 39) 0.4 parts of the compound represented by the above specific example No. 39 was obtained in the same manner as in Example 1, except that 1.8 parts of the following formula (11) was used instead of the above formula (5). The maximum absorption wavelength of this compound in toluene was 515.0 nm.

[0059]

[0060] Example 9 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 40) 0.6 parts of the compound represented by the above specific example No. 40 was obtained in the same manner as in Example 1, except that 3.6 parts of aniline were used instead of 4-n-butylaniline and 1.8 parts of the following formula (12) were used instead of the above formula (5) in step 1-1. The maximum absorption wavelength of this compound in toluene was 516.0 nm.

[0061]

[0062] Example 10 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 41) 0.5 parts of the compound represented by the above specific example No. 41 was obtained in the same manner as in Example 1, except that 1.8 parts of the following formula (13) was used instead of the above formula (5). The maximum absorption wavelength of this compound in toluene was 515.5 nm.

[0063]

[0064] Example 11 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 42) 0.7 parts of the compound represented by specific example No. 42 was obtained in the same manner as in Example 1, except that 7.4 parts of 4-n-heptylaniline were used instead of 4-n-butylaniline and 1.9 parts of formula (6) were used instead of formula (5) in step 1-1. The maximum absorption wavelength of this compound in toluene was 516.0 nm.

[0065] Example 12 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 43) 0.6 parts of the compound represented by specific example No. 43 was obtained in the same manner as in Example 1, except that 2.1 parts of the following formula (14) was used instead of the above formula (5). The maximum absorption wavelength of this compound in toluene was 515.0 nm.

[0066]

[0067] Example 13 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 44) 0.4 parts of the compound represented by the above specific example No. 44 was obtained in the same manner as in Example 1, except that 9.1 parts of 4-n-decylaniline were used instead of 4-n-butylaniline and 2.3 parts of the following formula (15) were used instead of the above formula (5) in step 1-1. The maximum absorption wavelength of this compound in toluene was 515.5 nm.

[0068]

[0069] Example 14 (Synthesis of anthraquinone compound of the present invention represented by specific example No. 45) 0.5 parts of the compound represented by specific example No. 45 was obtained in the same manner as in Example 1, except that 3.6 parts of aniline were used instead of 4-n-butylaniline and 1.9 parts of formula (6) were used instead of formula (5) in step 1-1. The maximum absorption wavelength of this compound in toluene was 515.5 nm.

[0070] Synthesis Example 1 (Synthesis of Comparative Example Compound) The compound represented by the following formula (X), which corresponds to No. 37 shown in Table 1 of JP-A-04-264193, was synthesized according to the description in paragraph

[0031] of the document.

[0071]

[0072] Synthesis Example 2 (Synthesis of Comparative Example Compound) A compound represented by the following formula (Y), which corresponds to general formula (II) described in paragraphs

[0045] to

[0046] of JP-A No. 2011-190314, was synthesized in accordance with the description in paragraph

[0054] of the same document.

[0073]

[0074] Example 15 (Preparation of Liquid Crystal Composition of the Present Invention) 0.012 parts of the compound represented by Specific Example No. 12 obtained in Example 1, 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 obtain a liquid crystal composition of the present invention.

[0075] Examples 16 to 28 and Comparative Examples 1 and 2 (Preparation of Liquid Crystal Compositions of the Present Invention and Comparative Liquid Crystal Compositions) Liquid crystal compositions of the present invention and comparative liquid crystal compositions were obtained in the same manner as in Example 15, except that the compound represented by No. 12 obtained in Example 1 was changed to the compounds obtained in Examples 2 to 14, the compound represented by Formula (X) obtained in Synthesis Example 1, and the compound represented by Formula (Y) obtained in Synthesis Example 2, respectively.

[0076] The liquid crystal composition obtained in Example 15 was sealed in a device having a transparent electrode and two glass substrates, one above the other, which had been subjected to a homogeneous alignment treatment by rubbing a polyamide resin on the surface in contact with the liquid crystal, with a gap of 15 μm between the substrates. In the device thus obtained, the liquid crystal was in a homogeneous alignment state when no voltage was applied, and the dye molecules (the anthraquinone compound obtained in Example 1) also took the same alignment according to the liquid crystal.

[0077] Examples 30 to 42 and Comparative Examples 3 and 4 (Preparation of the light-controlling element of the present invention and the comparative light-controlling element) The light-controlling element of the present invention and the comparative light-controlling element were prepared in accordance with Example 15, except that the liquid crystal composition obtained in Example 15 was replaced with the liquid crystal compositions obtained in Examples 16 to 28 and Comparative Examples 1 and 2, respectively. The transmittance (Kz) for linearly polarized light parallel to the alignment direction, the transmittance (Ky) for polarized light perpendicular to the alignment direction, and the dichroic ratio (Rd) were measured for the obtained light-controlling elements. At the same dye concentration, a smaller value of transmittance (Kz) indicates higher color development, and a larger value of dichroic ratio (Rd) indicates better contrast.

[0078] As shown in Table 1 below, the photochromic elements of Examples 29 to 42 had similar transmittance (Kz) but showed higher dichroic ratios (Rd) than the photochromic element of Comparative Example 3. Furthermore, the photochromic elements of Examples 29 to 42 had similar dichroic ratios (Rd) to the photochromic element of Comparative Example 4, but had smaller transmittance (Kz) values, indicating high color development. These results demonstrate that the photochromic elements of Examples 29 to 42 achieved both high color development and high contrast.

[0079]

[0080] The light-controlling liquid crystal composition of the present invention, which contains the anthraquinone compound having a maximum absorption wavelength in a specific wavelength region, high color development property, and a high dichroic ratio, can be used to obtain a light-controlling element having excellent contrast. The light-controlling element of the present invention can be suitably used for building materials such as windows, partitions, and doors, in-vehicle materials such as windows and sunroofs, displays showing letters and numbers, and materials for exhibits such as show windows.

Claims

1. An anthraquinone compound represented by the following formula (1). (In the formula, R １ represents a hydrogen atom, a linear or branched alkyl group having 1 to 14 carbon atoms, or a linear or branched alkoxy group having 1 to 14 carbon atoms. R ２ represents a hydrogen atom, a linear or branched alkyl group having 1 to 16 carbon atoms, or a linear or branched alkoxy group having 1 to 16 carbon atoms. n represents 1 to 3 carbon atoms.) 2. R １ The anthraquinone compound according to claim 1, wherein R is a linear or branched alkyl group having 1 to 8 carbon atoms.

3. R １ The anthraquinone compound according to claim 2, wherein R is a linear or branched alkyl group having 2 to 6 carbon atoms.

4. R １ The anthraquinone compound according to claim 1, wherein R is a linear or branched alkoxy group having 1 to 8 carbon atoms.

5. R ２ The anthraquinone compound according to claim 1, wherein R is a linear or branched alkyl group having 1 to 10 carbon atoms.

6. R ２ The anthraquinone compound according to claim 1, wherein R is a linear or branched alkoxy group having 1 to 10 carbon atoms.

7. The anthraquinone compound according to any one of claims 1 to 6, having a maximum absorption wavelength at 500 to 550 nm.

8. A dimming liquid crystal composition containing the anthraquinone compound according to any one of claims 1 to 6 and a liquid crystal material.

9. A dimming liquid crystal composition containing the anthraquinone compound according to claim 7 and a liquid crystal material.

10. The dimming liquid crystal composition according to claim 8, further containing a dye compound other than the anthraquinone compound represented by formula (1).

11. The dimming liquid crystal composition according to claim 9, further containing a dye compound other than the anthraquinone compound represented by formula (1).

12. A dimming element formed by sandwiching the dimming liquid crystal composition according to claim 8 between a pair of substrates arranged opposite to each other, at least one of which is a transparent substrate having a transparent electrode.

13. A dimming element formed by sandwiching the dimming liquid crystal composition according to claim 9 between a pair of substrates arranged opposite to each other, at least one of which is a transparent substrate having a transparent electrode.

14. A dimming element formed by sandwiching the dimming liquid crystal composition according to claim 10 between a pair of substrates arranged opposite to each other, at least one of which is a transparent substrate having a transparent electrode.

15. A dimming element formed by sandwiching the dimming liquid crystal composition according to claim 11 between a pair of substrates arranged opposite to each other, at least one of which is a transparent substrate having a transparent electrode.

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