Anthraquinone compounds, liquid crystal compositions containing such compounds, and dimming elements

Abstract

This invention relates to anthraquinone compounds represented by the following formula (1) (where R1 represents a hydrogen atom, a straight-chain or branched alkyl group having 1 to 14 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 14 carbon atoms. R2 represents a hydrogen atom, a straight-chain or branched alkyl group having 1 to 16 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 16 carbon atoms. n represents 1 to 3 carbon atoms.). R1 ​​can be a straight-chain or branched alkyl group having 1 to 8 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 8 carbon atoms. R2 can be a straight-chain or branched alkyl group having 1 to 10 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 10 carbon atoms.

Description

Technical Field

[0001] This invention relates to novel anthraquinone compounds, liquid crystal compositions containing such compounds, and dimming elements. Background Technology

[0002] In windows, doors, and partitions of vehicles such as trams and automobiles, as well as buildings such as commercial buildings and hospitals, for the purpose of protecting privacy, thin films obtained by dispersing liquid crystals in polymers, and thin films that form a dimming layer by utilizing the property of phase separation of liquid crystal substances during photocuring of a composition containing photocurable compounds and liquid crystals, are often used as dimming panels to replace blinds. While such dimming panels can control light transmission and scattering by applying voltage to block the view, there is a tendency for glare to increase due to light scattering, as they may not completely block light. Therefore, to reduce glare and improve contrast, pigments have been used in the materials of dimming panels. For example, when using such dimming panels in automobile windows, in addition to requiring no blurring when transparent, good visibility, and high contrast, the following light resistance is also required: even under long-term exposure to outdoor use and prolonged exposure to light at high temperatures, the transmittance should not decrease. Furthermore, from practical and design perspectives, the demand for black elements that can block visible light is also increasing.

[0003] To meet the aforementioned market demands, various liquid crystal display elements, known as GH (guest-host) type, using liquid crystal compositions containing pigments, have been proposed. These liquid crystal display elements, characterized by their viewing angle and brightness, have also been put into practical use in automotive applications and as dimming components.

[0004] For dichroic pigments commonly used in liquid crystal compositions for dimming elements, not only is high contrast required when the element is manufactured, but also lightfastness, UV resistance, heat resistance, and compatibility (solubility) of the dichroic pigment with the constituent components of the liquid crystal composition are also required. Furthermore, from a practical and design perspective, it is necessary to further reduce transmittance during light blocking and further block visible light. Generally, to reduce transmittance during light blocking, the amount of pigment added needs to be increased; however, if the amount of pigment increases, solubility decreases, making it difficult to achieve contrast when the element is manufactured. To improve light blocking with less pigment, the color rendering ability of the pigment itself is important. For example, Patent Documents 4 and 5 disclose dichroic pigments with extremely high absorption wavelengths in the 500 to 550 nm range. However, the pigments in these documents have high color rendering but insufficient contrast, or sufficient contrast but insufficient color rendering. A dichroic pigment with extremely high absorption wavelengths in the aforementioned range, high color rendering of the pigment itself, and excellent contrast of the element has not yet been discovered.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 63-501512

[0008] Patent Document 2: Japanese Patent Application Publication No. 03-47392

[0009] Patent Document 3: Japanese Patent Application Publication No. 2018-205746

[0010] Patent Document 4: Japanese Patent Application Publication No. 2011-190314

[0011] Patent Document 5: Japanese Patent Application Publication No. 04-264193 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] One object of the present invention is to provide anthraquinone compounds as novel structures for dichroic pigments.

[0014] Another object of the present invention is to provide an anthraquinone compound, which is a novel dichroic pigment with a large absorption wavelength in a specific wavelength region and excellent color rendering properties.

[0015] Another object of the present invention is to provide a liquid crystal composition containing anthraquinone compounds and a dimming element with excellent contrast containing the composition, wherein the anthraquinone compounds are novel dichroic pigments with a structure that has a large absorption wavelength in a specific wavelength region and excellent color rendering.

[0016] Solution for solving the problem

[0017] The inventors conducted in-depth research and successfully developed a novel anthraquinone compound with a specific structure. Furthermore, the inventors discovered that by using this anthraquinone compound, the aforementioned problems could be solved, thus completing this invention.

[0018] That is, the various methods or embodiments of the present invention are described below.

[0019] [1]. An anthraquinone compound represented by the following formula (1).

[0020]

[0021] (In the formula, R1 represents a hydrogen atom, a straight-chain or branched alkyl group having 1 to 14 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 14 carbon atoms. R2 represents a hydrogen atom, a straight-chain or branched alkyl group having 1 to 16 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 16 carbon atoms. n represents 1 to 3 carbon atoms.)

[0022] [2]. The anthraquinone compound according to [1] above, wherein R1 is a straight-chain or branched alkyl group having 1 to 8 carbon atoms.

[0023] [3]. The anthraquinone compound according to [2] above, wherein R1 is a straight-chain or branched alkyl group having 2 to 6 carbon atoms.

[0024] [4]. The anthraquinone compound according to [1] above, wherein R1 is a straight-chain or branched alkoxy group having 1 to 8 carbon atoms.

[0025] [5]. The anthraquinone compound according to [1] above, wherein R2 is a straight-chain or branched alkyl group having 1 to 10 carbon atoms.

[0026] [6]. The anthraquinone compound according to [1] above, wherein R2 is a straight-chain or branched alkoxy group having 1 to 10 carbon atoms.

[0027] [7]. The anthraquinone compound according to any one of [1] to [6] above has a maximum absorption wavelength at 500 to 550 nm.

[0028] [8]. A dimming liquid crystal composition comprising an anthraquinone compound and a liquid crystal material as described in any one of [1] to [7].

[0029] [9]. The dimming liquid crystal composition according to [8] above also contains pigment compounds other than the anthraquinone compound shown in formula (1).

[0030]

[10] . A dimming element is formed by sandwiching the dimming liquid crystal composition described above [8] or [9] between a pair of substrates arranged opposite to each other, at least one of the pair of substrates being a transparent substrate having a transparent electrode.

[0031] The effects of the invention

[0032] The anthraquinone compounds of the present invention, which have a large absorption wavelength in a specific wavelength region, have high color rendering properties. By using a dimming liquid crystal composition containing the anthraquinone compounds, a dimming element with excellent contrast can be obtained. Detailed Implementation

[0033] The present invention will now be described in detail.

[0034] The anthraquinone compounds of the present invention are represented by the following formula (1).

[0035]

[0036] In formula (1), R1 represents a hydrogen atom, a straight-chain or branched alkyl group having 1 to 14 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 14 carbon atoms.

[0037] The alkyl group represented by R1 in formula (1) having 1 to 14 carbon atoms can be either straight-chain or branched. Specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, 2-ethylhexyl, 2-propylhexyl, 2-butylhexyl, 2-pentylhexyl, 2-pentylheptyl, and 2-pentylnonyl. The straight-chain alkyl group preferably has 1 to 8 carbon atoms, more preferably 2 to 7, further preferably 2 to 6, and even more preferably 2 to 4. In addition, the branched alkyl group preferably has 3 to 6 carbon atoms, more preferably 3 or 4.

[0038] The alkoxy group represented by R1 in formula (1) having 1 to 14 carbon atoms can be either straight-chain or branched. Specific examples include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, neopentoxy, tert-pentoxy, hexoxy, heptoxy, octoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy, tetradecoxy, 2-ethylhexoxy, 2-propylhexoxy, 2-butylhexoxy, 2-pentylhexoxy, 2-pentylheptoxy, and 2-pentylnonoxy. Preferably, it is a straight-chain or branched alkoxy group having 1 to 8 carbon atoms, more preferably a straight-chain or branched alkoxy group having 3 to 8 carbon atoms, even more preferably a straight-chain or branched alkoxy group having 3 to 6 carbon atoms, even more preferably a straight-chain alkoxy group having 3 to 6 carbon atoms, and even more preferably a straight-chain alkoxy group having 3 to 5 carbon atoms.

[0039] As R1 in formula (1), it is preferably a straight-chain alkyl group having 1 to 8 carbons, a branched alkyl group having 3 to 6 carbons, or a straight-chain or branched alkoxy group having 1 to 8 carbons, more preferably a branched alkyl group having 3 or 4 carbons, or a straight-chain or branched alkoxy group having 3 to 6 carbons, even more preferably a straight-chain alkyl group having 2 to 6 carbons, or a straight-chain alkoxy group having 3 to 6 carbons, and even more preferably a straight-chain alkyl group having 2 to 4 carbons, or a straight-chain alkoxy group having 3 to 5 carbons.

[0040] In formula (1), R2 represents a hydrogen atom, a straight-chain or branched alkyl group having 1 to 16 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 16 carbon atoms.

[0041] The alkyl group represented by R2 in formula (1) having 1 to 16 carbon atoms can be either straight-chain or branched. Specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, 2-ethylhexyl, 2-propylhexyl, 2-butylhexyl, 2-pentylhexyl, 2-pentylheptyl, and 2-heptylnonyl. Preferably, it is a straight-chain or branched alkyl group having 1 to 10 carbon atoms, more preferably a straight-chain alkyl group having 2 to 8 carbon atoms, and even more preferably a straight-chain alkyl group having 4 to 7 carbon atoms.

[0042] The alkoxy group represented by R2 in formula (1) having 1 to 16 carbon atoms can be either straight-chain or branched. Specific examples include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, neopentoxy, tert-pentoxy, hexoxy, heptoxy, octoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy, tetradecoxy, pentadecoxy, hexadecoxy, 2-ethylhexoxy, 2-propylhexoxy, 2-butylhexoxy, 2-pentylhexoxy, 2-pentylheptoxy, and 2-heptylnonoxy. More preferably, it is a straight-chain alkoxy group having 2 to 8 carbon atoms.

[0043] As R2 in formula (1), it is preferably a straight-chain or branched alkyl group having 1 to 10 carbon atoms, more preferably a straight-chain alkyl or alkoxy group having 2 to 8 carbon atoms, and even more preferably a straight-chain alkyl group having 4 to 7 carbon atoms.

[0044] In equation (1), n ​​represents the number of carbons from 1 to 3, more preferably the number of carbons is 1.

[0045] As preferred examples of the compounds represented by the aforementioned formula (1), the following compounds can be listed, but the present invention is not limited to these.

[0046]

[0047]

[0048]

[0049]

[0050]

[0051] The compound shown in formula (1) can be synthesized, for example, by conventionally known methods as described in WO2023 / 100848A1 and WO2023 / 096111A1.

[0052] Specifically, for example, in the presence of a catalyst such as palladium or copper powder, under alkaline conditions such as tripotassium phosphate, the anthraquinone compound shown in formula (A) and the aniline derivative shown in formula (B) are reacted in a solvent such as xylene at 110 to 120 °C, thereby yielding the compound shown in formula (C). It should be noted that R2 in formulas (B) and (C) has the same meaning as R2 in formula (1).

[0053]

[0054] By brominating the compound shown in formula (C) above, the compound shown in formula (D) below can be obtained. Then, in the presence of a palladium catalyst such as palladium acetate, under alkaline conditions such as potassium carbonate, the compound shown in formula (D) below and the compound shown in formula (E) below are reacted in a solvent such as 1,4-dioxane at 80 to 90 °C, thereby obtaining the anthraquinone compound shown in formula (1). It should be noted that R1, R2, and n in formulas (D) and (E) below have the same meaning as R1, R2, and n in formula (1). In addition, B in formula (E) below... pin It indicates pinacol boron group.

[0055]

[0056] The liquid crystal composition of the present invention (hereinafter also referred to as "the composition of the present invention") contains an anthraquinone compound of formula (1) and a liquid crystal material.

[0057] The proportion 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, more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the liquid crystal material. When using dichroic pigments other than the compound represented by formula (1) (described later), the total content of the anthraquinone compound represented by formula (1) and the dichroic pigments other than the compound represented by formula (1) is preferably within the aforementioned range (0.5 to 10 parts by mass relative to 100 parts by mass of the liquid crystal material).

[0058] The liquid crystal material contained in the liquid crystal composition of the present invention is not particularly limited as long as it is a liquid crystal material (a liquid crystal compound) such as a nematic liquid crystal, cholesteric liquid crystal, or smectic liquid crystal. Examples of liquid crystal compounds include those described on pages 154 to 192 and 715 to 722 of the "Handbook of Liquid Crystal Devices" (edited by the 142nd Committee of the Japanese Society for the Promotion of Science, Nikkan Kogyo Shimbun, 1989).

[0059] The liquid crystal composition of the present invention may contain various additives such as dichroic pigments or cholesterol nonanoate other than the anthraquinone compound shown in formula (1) that display or do not display a liquid crystal phase, ultraviolet absorbers and antioxidants, photocurable compounds, and photopolymerization initiators.

[0060] In the compositions of the present invention, anthraquinone compounds of formula (1) and dichroic pigments other than anthraquinone compounds of formula (1) may be used in combination.

[0061] There are no particular limitations on the dichroic dyes that can be used in combination with the anthraquinone compounds shown in formula (1). For example, they can be selected from azo dyes, anthraquinone dyes, perylene dyes, quinoline dyes, anthocyanin dyes, methylimine dyes, phthaloperylene dyes, indigo dyes, azurite dyes, dioxazine dyes, polythiophene dyes, etc. Specifically, the contents described in "Dichroic dyes for Liquid Crystal Display" (Avivashchenko, CRC Corporation, 1994) can be cited.

[0062] Preferably, azo dyes, anthraquinone dyes, perylene dyes or quinoline dyes are used in combination with anthraquinone compounds shown in formula (1), and more preferably, azo dyes and anthraquinone dyes are used in combination.

[0063] When using anthraquinone compounds of formula (1) in combination with dichroic pigments other than those of formula (1), the amount of anthraquinone compounds of formula (1) in all dichroic pigments is not particularly limited as long as it does not impair the effects of the present invention, preferably 1 to 90% by mass, more preferably 5 to 70% by mass, and even more preferably 10 to 50% by mass.

[0064] The compositions of the present invention may also contain other additives as needed, such as light stabilizers such as benzotriazole, benzophenone and hindered amine, antioxidants such as phosphite and hindered phenol, heat-inhibiting agents, thiols, photosensitizers, photosensitizers, chain transfer inhibitors, polymerization inhibitors, adhesiveness enhancers, defoamers, crosslinking agents, surfactants, thermosetting accelerators, thermoplastic resins, thermosetting resins, thickeners such as urethane diacrylates, etc.

[0065] In addition, spherical or cylindrical spacers made of materials such as silica, glass, plastic, or ceramic can be added to control the unit gap of the dimming element. The unit gap of the dimming element can typically be set in the range of 2 to 100 μm.

[0066] The dimming element of the present invention is formed by sandwiching a layer of the aforementioned liquid crystal composition or its photocurable form between a pair of substrates arranged opposite each other, wherein at least one of the substrates is a transparent substrate having a transparent electrode. Examples of substrates include inorganic transparent materials such as glass and quartz, metals, metal oxides, semiconductors, ceramics, plastic sheets, and plastic films, which are colorless and transparent, colored and transparent, or opaque. The electrode is formed on the substrate by forming a thin film of, for example, metal oxide, metal, semiconductor, or organic conductive material on the entire surface or part of the substrate using known coating, printing, sputtering, or other vapor deposition methods. Particularly for obtaining a large-area dimming element, from the perspective of productivity and processability, an electrode substrate having ITO (indium tin oxide) electrodes formed on a transparent polymer film such as PET using sputtering, vapor deposition, or printing methods is preferred. It should be noted that wiring for connecting electrodes or connecting electrodes to the outside can also be provided on the substrate. For example, segmented driving electrode substrates, matrix driving electrode substrates, and active matrix driving electrode substrates can be used. Furthermore, the surface of the electrode disposed on the substrate can be covered entirely or partially by a protective film or alignment film formed of organic compounds such as polyimide, polyamide, organosilicon, and cyanide compounds, inorganic compounds such as SiO2, TiO2, and ZrO2, or mixtures thereof.

[0067] By using a plastic film as a substrate, flexible and lightweight dimming elements can be obtained. Therefore, dimming elements can be sandwiched between a pair of planar or curved glass or rigid plastic materials using adhesive layers such as polyvinyl butyral, vinyl acetate, double-sided tape, or adhesives. Alternatively, dimming elements can be attached to the surface of a single planar or curved glass or rigid plastic material using double-sided tape or adhesives. Furthermore, dimming elements can be sandwiched between flexible plastic materials or attached to one or both sides. Additionally, protective layers such as hard coatings, ultraviolet blocking layers, infrared blocking layers, or semi-transparent mirrors can be provided on the substrate surface opposite the electrode surface of the dimming element. Color filters or additional polarizing filters can also be stacked on the dimming element. Furthermore, electroluminescent display elements, light-emitting diode display elements, electrochromic display elements, and other liquid crystal display elements can be stacked on the dimming element.

[0068] As a driving device for applying voltage to the dimming element of the present invention, any device capable of applying a DC voltage of 2 to 100V or an AC voltage of 10 to 1000Hz is acceptable, and the electrodes can be open-circuited or short-circuited when no voltage is applied. Furthermore, the driving device may also include a voltage application circuit for segmented driving, a voltage application circuit for matrix driving, a voltage application circuit for active matrix, etc.

[0069] The anthraquinone compound represented by formula (1) of this invention has high color rendering properties, and dimming elements using this compound can achieve high-contrast displays. Therefore, this dimming element is suitable for building materials such as windows, partitions, and doors; vehicle-mounted materials such as windows and skylights; displays for text, numbers, etc.; and materials for display items such as shop windows.

[0070] Example

[0071] The present invention will now be described in more detail through examples, but the invention is not limited to these examples. It should be noted that, unless otherwise specified, "parts" and "%" refer to mass. The maximum absorption wavelengths in the examples were measured using a Shimadzu UV-3150 spectrophotometer manufactured by Shimadzu Corporation.

[0072] Example 1 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 12)

[0073] (Step 1-1) Synthesis of the intermediate compound shown in the following formula (3)

[0074] 0.6 parts of 2,2-bis(diphenylphosphino)-1,1-binaphthylene 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. Then, 8.0 parts of the compound shown in 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. After cooling the reaction solution to 45°C, 160 parts of methanol were added, and the mixture was stirred for 30 minutes. The reaction product was filtered, washed with methanol, and dried in a hot air dryer at 80°C for 24 hours to obtain 9.1 parts of the intermediate compound shown in formula (3).

[0075]

[0076] (Step 1-2) Synthesis of the intermediate compound shown in the following formula (4)

[0077] Add 6.51 parts of the compound shown in formula (3) above to 65.1 parts of methanol, stir for 10 minutes, then add 2.9 parts of 49% hydrobromic acid and 1.71 parts of 35% hydrogen peroxide, and stir at 25°C for 3 hours. Filter the reaction product, wash with methanol, and dry in a hot air dryer at 80°C for 24 hours to obtain 5.55 parts of the intermediate compound shown in formula (4) below.

[0078]

[0079] (Steps 1-3) Synthesis of the compound shown in Example No. 12

[0080] 1.9 parts of the compound shown in formula (4), 0.7 parts of potassium carbonate, 1.9 parts of the compound shown in formula (5), and 0.49 parts of tetrakis(triphenylphosphine)palladium were added to 80 parts of 1,4-dioxane and 17 parts of water, and the mixture was stirred at 80°C for 3 hours. After cooling the reaction solution to 30°C, 80 parts of methanol were added, and the mixture was stirred for 30 minutes. The reaction product was filtered, washed with methanol, and dried in a hot air dryer at 80°C for 24 hours to obtain 0.7 parts of the compound shown in Specific Example No. 12. The maximum absorption wavelength of this compound in toluene is 519.5 nm.

[0081]

[0082] Example 2 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 11)

[0083] Using formula (6) instead of formula (5) above, and otherwise operating in the same manner as in Example 1, 0.7 parts of the compound shown in Specific Example No. 11 above were obtained. The compound has a maximum absorption wavelength of 515.8 nm in toluene.

[0084]

[0085] Example 3 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 30)

[0086] Using 2.1 parts of formula (7) below instead of formula (5) above, and otherwise operating in the same manner as in Example 1, 0.7 parts of the compound shown in Specific Example No. 30 above were obtained. The compound has a maximum absorption wavelength of 514.3 nm in toluene.

[0087]

[0088] Example 4 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 17)

[0089] In step 1-1, 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). Otherwise, the procedure was the same as in Example 1, and 0.7 parts of the compound shown in Specific Example No. 17 were obtained. The maximum absorption wavelength of this compound in toluene is 516.0 nm.

[0090]

[0091] Example 5 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 26)

[0092] By substituting 2.0 parts of the following formula (9) for the above formula (5), and otherwise operating in the same manner as in Example 1, 0.7 parts of the compound shown in Specific Example No. 26 were obtained. The compound has a maximum absorption wavelength of 515.0 nm in toluene.

[0093]

[0094] Example 6 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 19)

[0095] In step 1-1, 9.1 parts of 4-n-decylaniline were used instead of 4-n-butylaniline, and the procedure was otherwise the same as in Example 1, yielding 0.5 parts of the compound shown in Specific Example No. 19 above. The compound exhibits a maximum absorption wavelength of 516.0 nm in toluene.

[0096] Example 7 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 38)

[0097] By substituting 2.3 parts of the following formula (10) for the above formula (5), and otherwise operating in the same manner as in Example 1, 0.6 parts of the compound shown in Specific Example No. 38 were obtained. The compound has a maximum absorption wavelength of 515.5 nm in toluene.

[0098]

[0099] Example 8 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 39)

[0100] Using 1.8 parts of the following formula (11) instead of the above formula (5), and otherwise operating in the same manner as in Example 1, 0.4 parts of the compound shown in Specific Example No. 39 were obtained. The compound has a maximum absorption wavelength of 515.0 nm in toluene.

[0101]

[0102] Example 9 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 40)

[0103] In step 1-1, 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). Otherwise, the procedure was the same as in Example 1, and 0.6 parts of the compound shown in Specific Example No. 40 were obtained. The maximum absorption wavelength of this compound in toluene is 516.0 nm.

[0104]

[0105] Example 10 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 41)

[0106] By substituting 1.8 parts of the following formula (13) for the above formula (5), and otherwise operating in the same manner as in Example 1, 0.5 parts of the compound shown in Specific Example No. 41 were obtained. The compound has a maximum absorption wavelength of 515.5 nm in toluene.

[0107]

[0108] Example 11 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 42)

[0109] In step 1-1, 7.4 parts of 4-n-heptylaniline were used instead of 4-n-butylaniline, and 1.9 parts of the above formula (6) were used instead of the above formula (5). Otherwise, the operation was the same as in Example 1, and 0.7 parts of the compound shown in Specific Example No. 42 were obtained. The maximum absorption wavelength of this compound in toluene is 516.0 nm.

[0110] Example 12 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 43)

[0111] Using 2.1 parts of the following formula (14) instead of the above formula (5), and otherwise operating in the same manner as in Example 1, 0.6 parts of the compound shown in Specific Example No. 43 were obtained. The compound has a maximum absorption wavelength of 515.0 nm in toluene.

[0112]

[0113] Example 13 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 44)

[0114] In step 1-1, 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). Otherwise, the operation was the same as in Example 1, and 0.4 parts of the compound shown in Specific Example No. 44 were obtained. The maximum absorption wavelength of this compound in toluene is 515.5 nm.

[0115]

[0116] Example 14 (Synthesis of the anthraquinone compound of the present invention as shown in Specific Example No. 45)

[0117] In step 1-1, 3.6 parts of aniline were used instead of 4-n-butylaniline, and 1.9 parts of the above formula (6) were used instead of the above formula (5). Otherwise, the operation was the same as in Example 1, and 0.5 parts of the compound shown in Specific Example No. 45 were obtained. The maximum absorption wavelength of this compound in toluene is 515.5 nm.

[0118] Synthesis Example 1 (Synthesis of the Comparative Compound)

[0119] The compound represented by the following formula (X) of Table 1, which corresponds to No. 37 of Japanese Patent Application Publication No. 04-264193, was synthesized according to the description in paragraph

[0031] of that document.

[0120]

[0121] Synthesis Example 2 (Synthesis of the Comparative Compound)

[0122] The compound represented by formula (Y) of general formula (II) as described in paragraphs

[0045] to

[0046] of Japanese Patent Application Publication No. 2011-190314 was synthesized according to paragraph

[0054] of that publication.

[0123]

[0124] Example 15 (Preparation of the liquid crystal composition of the present invention)

[0125] The liquid crystal composition of the present invention was obtained by mixing 0.012 parts of the compound shown in Specific Example No. 12 of 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 at room temperature.

[0126] Examples 16 to 28 and Comparative Examples 1 to 2 (liquid crystal compositions of the present invention and comparative liquid crystal compositions) preparation)

[0127] The compound shown in No. 12 obtained in Example 1 was replaced with the compounds obtained in Examples 2 to 14, the compound shown in formula (X) obtained in Synthesis Example 1, and the compound shown in formula (Y) obtained in Synthesis Example 2. Otherwise, the liquid crystal composition of the present invention and the liquid crystal composition for comparison were obtained according to Example 15.

[0128] Example 29 (Fabrication of the dimming element of the present invention)

[0129] The liquid crystal composition obtained in Example 15 was encapsulated in an element with a substrate gap of 15 μm. This element was formed from two glass substrates having transparent electrodes and having undergone parallel alignment treatment by rubbing polyamide resin on the surfaces in contact with the liquid crystal. In the element thus obtained, the liquid crystal is in a parallel alignment state when no voltage is applied, and the pigment molecules (anthraquinone compounds obtained in Example 1) also take the same orientation as the liquid crystal.

[0130] Examples 30 to 42 and Comparative Examples 3 to 4 (manufacturing of the dimming element of the present invention and the dimming element for comparison) do)

[0131] 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 to 2, respectively. Otherwise, the dimming element of the present invention and a comparative dimming element were fabricated according to Example 15. For the obtained dimming elements, the transmittance (Kz) for linearly polarized light parallel to the orientation direction, the transmittance (Ky) for polarized light perpendicular to the orientation direction, and the dichroism ratio (Rd) were measured. At the same pigment concentration, a smaller transmittance (Kz) value indicates higher color rendering, and a larger dichroism ratio (Rd) value indicates better contrast.

[0132] As shown in Table 1 below, the dimming elements of Examples 29 to 42 have the same transmittance (Kz) as the dimming element of Comparative Example 3, but exhibit a higher dichroic ratio (Rd). Furthermore, the dimming elements of Examples 29 to 42 have the same dichroic ratio (Rd) as the dimming element of Comparative Example 4, but have a lower transmittance (Kz) value, indicating higher color rendering. These results show that the dimming elements of Examples 29 to 42 can achieve a balance between high color rendering and high contrast.

[0133] [Table 1]

[0134]

[0135] Industrial availability

[0136] By using a dimming liquid crystal composition comprising the anthraquinone compound of the present invention, wherein the anthraquinone compound of the present invention has a maximum absorption wavelength in a specific wavelength region, high color rendering, and high dichroism ratio, a dimming element with excellent contrast can be obtained. The dimming element of the present invention is suitable for use in building materials such as windows, partitions, and doors; automotive materials such as windows and skylights; displays for displaying text, numbers, etc.; and materials for display items such as shop windows.

Claims

1. An anthraquinone compound represented by formula (1) below, In the formula, R1 represents a hydrogen atom, a straight-chain or branched alkyl group having 1 to 14 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 14 carbon atoms, R2 represents a hydrogen atom, a straight-chain or branched alkyl group having 1 to 16 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 16 carbon atoms, and n represents 1 to 3 carbon atoms.

2. The anthraquinone compound according to claim 1, wherein, R1 is a straight-chain or branched alkyl group having 1 to 8 carbon atoms.

3. The anthraquinone compound according to claim 2, wherein, R1 is a straight-chain or branched alkyl group having 2 to 6 carbon atoms.

4. The anthraquinone compound according to claim 1, wherein, R1 is a straight-chain or branched alkoxy group with 1 to 8 carbon atoms.

5. The anthraquinone compound according to claim 1, wherein, R2 is a straight-chain or branched alkyl group having 1 to 10 carbon atoms.

6. The anthraquinone compound according to claim 1, wherein, R2 is a straight-chain or branched alkoxy group with 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 comprising an anthraquinone compound as described in any one of claims 1 to 6 and a liquid crystal material.

9. A liquid crystal composition for dimming, comprising the anthraquinone compound of claim 7 and a liquid crystal material.

10. The liquid crystal composition for dimming according to claim 8, further comprising a pigment compound other than the anthraquinone compound shown in formula (1).

11. The liquid crystal composition for dimming according to claim 9, further comprising a pigment compound other than the anthraquinone compound shown in formula (1).

12. A dimming element comprising a dimming liquid crystal composition of claim 8 sandwiched between a pair of oppositely arranged substrates, at least one of the pair of substrates being a transparent substrate having a transparent electrode.

13. A dimming element comprising a dimming liquid crystal composition of claim 9 sandwiched between a pair of oppositely arranged substrates, at least one of the pair of substrates being a transparent substrate having a transparent electrode.

14. A dimming element comprising a dimming liquid crystal composition of claim 10 sandwiched between a pair of oppositely arranged substrates, at least one of the pair of substrates being a transparent substrate having a transparent electrode.

15. A dimming element comprising a dimming liquid crystal composition of claim 11 sandwiched between a pair of oppositely arranged substrates, at least one of the pair of substrates being a transparent substrate having a transparent electrode.

Images