Anthraquinone compounds, liquid crystal compositions containing the compound, and dimming elements

Abstract

An anthraquinone compound represented by formula (1): (where R1 and R4 represent -H, a C1-C12 alkyl group, a C1-C12 alkoxy group, a halogen atom, -CO2R9, -OCOR9, -COR9, a cyano group, or -CF3, R2, R3, R5 and R6 represent -H, a C1-C4 alkyl group, a C1-C4 alkoxy group, a halogen atom, -CO2R9, -OCOR9, -COR9, a cyano group, or -CF3. R7 and R8 represent -H, a C1-C12 alkyl group, or a C1-C12 alkoxy group. R9 represents a C1-C12 alkyl group, or a substituent represented by formula (a) (where R10 represents -H, a C1-C8 alkyl group, or a C1-C8 alkoxy group) or formula (b) (where R11 represents -H or a C1-C8 alkyl group); however, at least one of R1 through R6 represents a halogen atom, -CO2R9, -COR9, a cyano group, or -CF3).

Description

[Technical Field]

[0001] The present invention relates to a novel anthraquinone compound, a liquid crystal composition containing the compound, and a dimming element. [Background technology]

[0002] Various innovations have been proposed for dimmable films that control the transmission of external light for purposes such as protecting privacy in windows, doors, and partitions of vehicles such as trains and automobiles, and buildings such as business buildings and hospitals (see Patent Documents 1 and 2). One such dimmable film utilizes liquid crystal. Normally, liquid crystal dimmable films can block visibility by controlling the transmission and scattering of light depending on whether or not voltage is applied, but they cannot block light itself, so glare tends to increase due to light scattering. Therefore, attempts have been made to use dyes as materials for dimmable panels with the aim of reducing glare and improving contrast (see Patent Documents 3 and 4). For example, when such a dimmable panel is used in the windows of an automobile, there is a strong demand for a dimmable element that, in addition to being clear and providing good visibility when transparent, does not change color much when exposed to light for long periods of time outdoors, i.e., when exposed to light at high temperatures for extended periods, not only when blocking light but also when transparent, from the standpoint of practicality and design.

[0003] Dichroic dyes are commonly used as dyes in liquid crystal dimming films. GH (guest-host) type dimming elements using liquid crystal compositions containing dichroic dyes are known, and various dichroic dyes have been proposed (see Patent Document 5).

[0004] Such dichroic dyes require not only contrast when used as display elements, but also lightfastness, UV resistance, and heat resistance. Efforts have been made to improve these properties, but none have yet been found that satisfy all of them. For example, Patent Document 5 discloses a dichroic dye suitable for dimming applications, but the dye in that document has insufficient lightfastness. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Special Publication No. 63-501512 [Patent Document 2] Japanese Patent Application Publication No. 03-47392 [Patent Document 3] Japanese Patent Publication No. 2018-205746 [Patent Document 4] Japanese Patent Publication No. 2011-190314 [Patent Document 5] Japanese Patent Application Publication No. 62-5941 [Overview of the project] [Problems that the invention aims to solve]

[0006] The first objective of the present invention is to provide novel anthraquinone compounds. Another object of the present invention is to provide a novel anthraquinone compound, a dichroic dye with excellent lightfastness, a liquid crystal composition containing the dichroic dye, and a light-adjusting element containing the composition. [Means for solving the problem]

[0007] The inventors have succeeded in obtaining a novel anthraquinone compound with a specific structure. Furthermore, the present inventors have found that a light-resistant dichromatic element can be obtained by using a liquid crystal composition containing a dichroic dye, which is a novel anthraquinone compound with such a specific structure. In other words, the various aspects or embodiments encompassed by the present invention are as follows: [1] The following formula (1) [ka] (In the formula, R1 and R4 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, a halogen atom, -CO2R9, -OCOR9, -COR9, a cyano group, or a trifluoromethyl group. R2, R3, R5, and R6 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a halogen atom, -CO2R9, -OCOR9, -COR9, a cyano group, or a trifluoromethyl group. R7 and R8 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, or a linear or branched alkoxy group having 1 to 12 carbon atoms. R9 each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms or the following formula (a) [ka] (In the formula, R 10 ) or the following formula (b) [ka] (In the formula, R 11 ) represents a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms. ) represents a substituent, where at least one of R1 to R6 represents a halogen atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group. ) represents an anthraquinone compound. [2]. The anthraquinone compound according to item [1] above, wherein R9 is independently a linear or branched alkyl group having 1 to 8 carbon atoms. [3]. The anthraquinone compound according to the above [1] or [2], wherein in Formula (1), R1 and R4 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, a fluorine atom, a chlorine atom, -CO2R9, -COR9, a cyano group or a trifluoromethyl group; and R2, R3, R5 and R6 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a fluorine atom, a chlorine atom, -CO2R9, -COR9, a cyano group or a trifluoromethyl group. [4]. The anthraquinone compound according to the above [3], wherein in Formula (1), R1 and R4 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a fluorine atom, -CO2R9, -COR9, a cyano group or a trifluoromethyl group; and R2, R3, R5 and R6 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a fluorine atom, -CO2R9, -COR9, a cyano group or a trifluoromethyl group. [5]. The anthraquinone compound according to any one of the above [1] to [4], wherein in Formula (1), R2 and R5 are hydrogen atoms. [6]. The anthraquinone compound according to any one of the above [1] to [5], wherein in Formula (1), only one of R1 and R3 is a hydrogen atom, and only one of R4 and R6 is a hydrogen atom. [7]. The anthraquinone compound according to any one of the above [1] to [6], wherein in Formula (1), R3 and R6 are hydrogen atoms. [8]. The anthraquinone compound according to any one of the above [1] to [7], wherein in Formula (1), R4 is a linear or branched alkyl group having 4 to 12 carbon atoms. [9]. The anthraquinone compound according to any one of the above [1] to [8], wherein in Formula (1), R7 and R8 are each independently a linear or branched alkyl group having 4 to 12 carbon atoms or a linear or branched alkoxy group having 4 to 12 carbon atoms.

[10] A liquid crystal composition containing an anthraquinone compound and a liquid crystal material as described in any one of the preceding paragraphs [1] to [9].

[11] The liquid crystal composition according to the preceding paragraph

[10] , further comprising at least one dye compound other than the anthraquinone compound represented by formula (1).

[12] The liquid crystal composition according to paragraph

[10] or

[11] , further comprising a photocurable compound and a photopolymerization initiator.

[13] . A photocured product of the liquid crystal composition described in the preceding paragraph

[12] .

[14] A dimming element comprising a pair of opposing substrates, at least one of which is a transparent substrate having a transparent electrode, with the liquid crystal composition described in any one of the preceding paragraphs

[10] to

[12] or the photocured product described in the preceding paragraph

[13] sandwiched between them.

[15] The dimming element according to the preceding paragraph

[14] , wherein both of the pair of substrates are transparent substrates having transparent electrodes. [Effects of the Invention]

[0008] The anthraquinone compound of the present invention has dichroism and excellent light resistance. Therefore, by using a liquid crystal composition containing this compound, a light-adjusting element can be obtained that exhibits minimal color change even when exposed to light for long periods at high temperatures, not only when shielded from light but also when transparent. [Modes for carrying out the invention]

[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] [ka]

[0011] In formula (1), R1 and R4 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, a halogen atom, -CO2R9, -OCOR9, -COR9, a cyano group, or a trifluoromethyl group. R2, R3, R5, and R6 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a halogen atom, -CO2R9, -OCOR9, -COR9, a cyano group, or a trifluoromethyl group. R7 and R8 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, or a linear or branched alkoxy group having 1 to 12 carbon atoms. Each R9 independently represents a linear or branched alkyl group having 1 to 12 carbon atoms, or a substituent represented by the following formula (a) or (b). However, at least one of R1 to R6 represents a halogen atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group.

[0012] [ka]

[0013] In formula (a), R 10 R represents a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, or a linear or branched alkoxy group having 1 to 8 carbon atoms, in formula (b), 11 represents a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms.

[0014] The C1 to C12 alkyl groups represented by R1 and R4 in formula (1) may be linear or branched. Specific examples include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, sec-butyl group, t-butyl group, n-pentyl group, iso-pentyl group, neo-pentyl group, t-pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, 2-ethylhexyl group, 2-propylhexyl group, 2-butylhexyl group, 2-pentylhexyl group, and 2-pentylheptyl group. Among these, linear or branched alkyl groups having C4 to C12 are preferred, linear alkyl groups having C4 to C12 are more preferred, and linear alkyl groups having C4 to C8 are even more preferred.

[0015] The alkoxy groups having 1 to 12 carbon atoms represented by R1 and R4 in formula (1) may be linear or branched. Specific examples include methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, iso-butoxy group, sec-butoxy group, t-butoxy group, n-pentyloxy group, iso-pentyloxy group, neo-pentyloxy group, t-pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, decyloxy group, undecyloxyl group, dodecyloxy group, 2-ethylhexyloxy group, 2-propylhexyloxy group, 2-butylhexyloxy group, 2-pentylhexyloxy group, and 2-pentylheptyloxy group. Linear or branched alkoxy groups having 1 to 8 carbon atoms are preferred, linear or branched alkoxy groups having 4 to 8 carbon atoms are more preferred, and linear alkoxy groups having 4 to 8 carbon atoms are even more preferred.

[0016] Specific examples of halogen atoms represented by R1 and R4 in formula (1) include fluorine, chlorine, bromine, and iodine atoms, with fluorine or chlorine atoms being preferred, and fluorine atoms being more preferred.

[0017] Specific examples of the linear or branched alkyl group having 1 to 12 carbon atoms represented by R9 are the same as the specific examples of the linear or branched alkyl group having 1 to 12 carbon atoms represented by R1 and R4 in formula (1). Each is independently preferably a linear or branched alkyl group having 1 to 8 carbon atoms, each is independently more preferably a linear or branched alkyl group having 1 to 4 carbon atoms, and each is independently still more preferably a linear alkyl group having 1 to 4 carbon atoms.

[0018] R in equation (a) 10 Specific examples of linear or branched alkyl groups having 1 to 8 carbon atoms represented by R1 and R4 of formula (1) include the same linear or branched alkyl groups having 1 to 8 carbon atoms as described in the section on specific examples of linear or branched alkyl groups having 1 to 12 carbon atoms represented by R1 and R4 of formula (1). Linear or branched alkyl groups having 1 to 7 carbon atoms are preferred, and linear alkyl groups having 1 to 7 carbon atoms are more preferred.

[0019] R in equation (a) 10 Specific examples of the linear or branched alkoxy group having 1 to 8 carbon atoms represented by R1 and R4 of formula (1) are the same as those described in the section on specific examples of linear or branched alkoxy groups having 1 to 12 carbon atoms represented by R1 and R4 of formula (1). Linear or branched alkoxy groups having 1 to 7 carbon atoms are preferred, and linear alkoxy groups having 1 to 7 carbon atoms are more preferred.

[0020] R in equation (b) 11 Specific examples of linear or branched alkyl groups having 1 to 8 carbon atoms represented by R1 and R4 of formula (1) include the same linear or branched alkyl groups having 1 to 8 carbon atoms as described in the section on specific examples of linear or branched alkyl groups having 1 to 12 carbon atoms represented by R1 and R4 of formula (1). Linear or branched alkyl groups having 1 to 5 carbon atoms are preferred, and linear alkyl groups having 1 to 5 carbon atoms are more preferred.

[0021] In formula (1), R9 is preferably a linear or branched alkyl group having 1 to 12 carbon atoms.

[0022] As R1 in formula (1), a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, a fluorine atom, a chlorine atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group are preferred. More preferably, as R1, a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a fluorine atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group are preferred, and even more preferably, a hydrogen atom, a fluorine atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group are preferred, and particularly preferably, a hydrogen atom, a fluorine atom, -CO2R9, -COR9, or a cyano group are preferred.

[0023] As R4 in formula (1), a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, a fluorine atom, a chlorine atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group are preferred. More preferably, as R4, a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a fluorine atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group are preferred, a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a fluorine atom, -CO2R9, -COR9, or a cyano group are even more preferred, a linear or branched alkyl group having 1 to 12 carbon atoms is particularly preferred, and a linear or branched alkyl group having 4 to 8 carbon atoms is most preferred.

[0024] Specific examples of linear or branched alkyl groups having 1 to 4 carbon atoms represented by R2, R3, R5, and R6 in formula (1) include the same linear or branched alkyl groups having 1 to 4 carbon atoms as described in the section on specific examples of linear or branched alkyl groups having 1 to 12 carbon atoms represented by R1 and R4 in formula (1). Methyl or ethyl groups are preferred.

[0025] Specific examples of the linear or branched alkoxy groups having 1 to 4 carbon atoms represented by R2, R3, R5, and R6 in formula (1) include the same linear or branched alkoxy groups having 1 to 4 carbon atoms as described in the section on specific examples of linear or branched alkoxy groups having 1 to 12 carbon atoms represented by R1 and R4 in formula (1). Methoxy or ethoxy groups are preferred.

[0026] Specific examples of halogen atoms represented by R2, R3, R5, and R6 in formula (1) are the same as the specific examples of halogen atoms represented by R1 and R4 in formula (1). Fluorine atoms or chlorine atoms are preferred, and fluorine atoms are more preferred.

[0027] For R2 and R5 of formula (1), independently, a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a fluorine atom, a chlorine atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group are preferred. For R2 and R5, independently, a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a fluorine atom, a chlorine atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group are more preferred, independently, a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a fluorine atom, -CO2R9, -COR9, or a cyano group are even more preferred, independently, a hydrogen atom, a fluorine atom, -CO2R9, -COR9, or a cyano group are particularly preferred, and a hydrogen atom is most preferred.

[0028] For R3 and R6 in formula (1), independently, a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a fluorine atom, a chlorine atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group are preferred. For R3 and R6, independently, a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a fluorine atom, a chlorine atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group are more preferred, independently, a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a fluorine atom, -CO2R9, -COR9, or a cyano group is even more preferred, and independently, a hydrogen atom, a fluorine atom, -CO2R9, -COR9, or a cyano group is particularly preferred.

[0029] Specific examples of linear or branched alkyl groups having 1 to 12 carbon atoms represented by R7 and R8 in formula (1) are the same as the specific examples of linear or branched alkyl groups having 1 to 12 carbon atoms represented by R1 and R4 in formula (1), with linear or branched alkyl groups having 4 to 12 carbon atoms being preferred, and linear alkyl groups having 4 to 12 carbon atoms being more preferred.

[0030] Specific examples of the linear or branched alkoxy groups having 1 to 12 carbon atoms represented by R7 and R8 in formula (1) are the same as the specific examples of the linear or branched alkoxy groups having 1 to 12 carbon atoms represented by R1 and R4 in formula (1), with linear or branched alkoxy groups having 4 to 12 carbon atoms being preferred, and linear alkoxy groups having 4 to 12 carbon atoms being more preferred.

[0031] For R7 and R8 in formula (1), each is independently preferably a linear or branched alkyl group having 4 to 10 carbon atoms or a linear or branched alkoxy group having 4 to 10 carbon atoms. For R7 and R8, each is independently preferably a linear alkyl group having 4 to 10 carbon atoms or a linear alkoxy group having 4 to 10 carbon atoms, and each is independently even more preferably a linear alkoxy group having 4 to 10 carbon atoms.

[0032] In formula (1), it is preferable that the number of substituents on the phenyl group having R1 to R3 and the number of substituents on the phenyl group having R4 to R6 are each independently 0 to 2 (that is, at least one of R1 to R3 is a hydrogen atom, and at least one of R4 to R6 is a hydrogen atom), and it is more preferable that the number is 0 to 1 (that is, at least two of R1 to R3 are hydrogen atoms, and at least two of R4 to R6 are hydrogen atoms). Note that the substituent herein means a group other than a hydrogen atom.

[0033] In addition, in formula (1), when the positions of substituents on the phenyl group having R1 to R3 and the positions of substituents on the phenyl group having R4 to R6 are each independently described by the numbers shown in the following formula (3), preferred are only the 2-position, only the 3-position, only the 4-position, two positions of the 2-position and 4-position, or two positions of the 3-position and 4-position; more preferred are only the 2-position, only the 3-position, and only the 4-position; and even more preferred is only the 4-position. Note that, for example, "only the 4-position" means having a substituent other than a hydrogen atom only at the 4-position.

[0034] [Chemical Formula]

[0035] At least one of R1 to R6 in formula (1) is preferably a halogen atom, -CO2R9, -COR9, a cyano group, or a trifluoromethyl group. In addition, as for R1 and R3 in formula (1), it is preferable that only one of them is a hydrogen atom, and it is more preferable that only R3 is a hydrogen atom; and / or, as for R4 and R6 in formula (1), it is preferable that only one of them is a hydrogen atom, and it is more preferable that only R6 is a hydrogen atom.

[0036] As the anthraquinone compound represented by formula (1), R in the above R1 to R9 and formula (a) 10 and R in formula (b) 11 a combination of the respective preferred to most preferred embodiments of is more preferable.

[0037] The following are some preferred specific examples of the compound represented by formula (1), but the present invention is not limited to these. Note that the alkyl groups, the alkyl portion of alkoxy groups, and the alkyl portion of ester groups in the structures of the specific examples below all represent straight carbon chains.

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] The anthraquinone compound represented by formula (1) of the present invention can be synthesized, for example, by referring to the method described in US2004 / 0087692A1 specification. Specifically, for example, an anthraquinone compound represented by the following formula (A), synthesized by a conventionally known method described in Japanese Patent Publication No. 63-72760, can be synthesized by reacting it with an iodobenzene derivative (or alternatively, a bromobenzene derivative) represented by the following formula (B) at 140 to 160°C in a solvent such as N-methyl-2-pyrrolidone, under basic conditions such as potassium carbonate, in the presence of a copper catalyst such as copper powder. In addition, R1 to R8 in formulas (A) and (B) below represent the same meaning as in formula (1). As an alternative to this synthesis method, instead of introducing a benzene ring having R1 to R3 as substituents as an iodobenzene derivative (for example, the reaction exemplified in Examples 1 to 3 described below), a reaction in which a benzene ring having R4 to R6 as substituents is introduced as an iodobenzene derivative (for example, the reaction exemplified in Example 4 described below) may be carried out.

[0050] [ka]

[0051] The liquid crystal composition of the present invention (hereinafter sometimes simply referred to as "the composition of the present invention") contains an anthraquinone compound represented by formula (1) and a liquid crystal material.

[0052] The content of the anthraquinone compound represented by formula (1) in the liquid crystal composition is not particularly limited, but is preferably 0.5 to 15 parts by mass, and more preferably 0.5 to 5 parts by mass, per 100 parts by mass of liquid crystal material. When a dichroic dye other than the compound represented by formula (1) (described later) is used in combination, it is preferable that the total content of the anthraquinone compound represented by formula (1) and the dichroic dye other than the compound represented by formula (1) is within the above range (0.5 to 15 parts by mass) per 100 parts by mass of liquid crystal material.

[0053] 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, but among these, a nematic liquid crystal is preferred. Examples of liquid crystal compounds include the liquid crystal compounds described in paragraphs 154 to 192 and 715 to 722 of the "Liquid Crystal Device Handbook" (edited by the 142nd Committee of the Japan Society for the Promotion of Science, Nikkan Kogyo Shimbun, 1989).

[0054] The liquid crystal composition of the present invention may contain optically active substances that exhibit or do not exhibit a liquid crystal phase, such as dichroic dyes or cholesteryl noenanoate other than the anthraquinone compound represented by formula (1), various additives such as ultraviolet absorbers and antioxidants, photocurable compounds and photopolymerization initiators.

[0055] The photocurable compound that may be contained in the liquid crystal composition of the present invention is not particularly limited as long as it is a compound having a functional group that can be polymerized by the action of a photopolymerization initiator described later when irradiated with light. Examples of photocurable compounds include compounds having a (meth)acrylate group, compounds having a vinyl group, and compounds having an allyl group. Compounds having a (meth)acrylate group are preferred. In this specification, "(meth)acrylate" means "methacrylate and / or acrylate".

[0056] The (meth)acrylate compounds contained in the liquid crystal composition of the present invention include, but are not limited to, mono(meth)acrylate compounds having one (meth)acrylate group in one molecule and di(meth)acrylate compounds having two (meth)acrylate groups in one molecule.

[0057] As the mono(meth)acrylate compound, mono(meth)acrylates having linear, cyclic, or branched alkyl groups with 5 to 13 carbon atoms are preferred. Specific examples 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; cyclic alkyl mono(meth)acrylates such as isobornyl(meth)acrylate; branched alkyl mono(meth)acrylates such as 2-methylhexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, 2-propylhexyl(meth)acrylate, 2-methylheptyl(meth)acrylate, 2-ethylheptyl(meth)acrylate, and 2-propylheptyl(meth)acrylate.

[0058] Examples of di(meth)acrylate compounds include 1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,11-undecanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, and 1,13-tridecanediol di(meth)acrylate, as well as trichloroethylene glycol di(meth)acrylates such as triethylene glycol di(meth)acrylate.

[0059] The liquid crystal composition of the present invention may contain both a mono(meth)acrylate compound and a di(meth)acrylate compound. When a mono(meth)acrylate compound and a di(meth)acrylate compound are used in combination, the mass ratio of the mono(meth)acrylate compound to the di(meth)acrylate compound is preferably 10:90 to 96:4, and more preferably 50:50 to 95:5.

[0060] The photopolymerization initiator that may be contained in the composition of the present invention is not particularly limited as long as it is a compound that can polymerize a photocurable compound upon irradiation with light. Preferably, it is a compound that remains in the cured product after light irradiation and does not cause alteration of dichroic dyes such as anthraquinone compounds represented by formula (1). As photopolymerization initiators, alkylphenone-based photopolymerization initiators such as Darocure 1173, Irgacure 651, and Irgacure 184, or phosphine oxide-based photopolymerization initiators such as Irgacure TPO are preferably used.

[0061] In the composition of the present invention containing a photocurable compound and a photopolymerization initiator, the ratio of the total anthraquinone compound represented by formula (1) and liquid crystal material to the photocurable compound is preferably 90:10 to 50:50 by mass ratio, more preferably 80:20 to 50:50, and even more preferably 60:40 to 50:50. By setting the ratio of the photocurable compound within the above range, it is possible to prevent the separation of the liquid crystal material and the photocurable compound before curing by light irradiation, and to prevent a decrease in the light-shielding properties of the cured product. Furthermore, when using dichroic dyes other than the compound represented by formula (1) (described later), the blending ratio of all dichroic dyes, including 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 within the above range (mass ratio of 90:10 to 50:50), and the more preferred range and even more preferred range are the same as above.

[0062] When the composition of the present invention contains a photocurable compound and a photopolymerization initiator, the amount of the photopolymerization initiator is preferably 0.1 to 5 parts by mass per 100 parts by mass of the photocurable compound.

[0063] The compositions of the present invention may also contain dichroic dyes other than the anthraquinone compound represented by formula (1). The dichroic dyes that can be used in combination are not particularly limited, but can 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. Specifically, those described in "Dichroic dyes for Liquid Crystal Display" (by AVIvashchenko, CRC, 1994) are examples. Among these, it is preferable to use azo dyes, anthraquinone dyes, perylene dyes, or quinophthalone dyes in combination, and it is more preferable to use azo dyes and anthraquinone dyes in combination.

[0064] When using dichroic dyes other than the anthraquinone compound represented by formula (1) in combination, the content of the anthraquinone compound represented by formula (1) in the total dichroic dyes is not particularly limited as long as it does not impair the effects of the present invention. The amount is preferably 1 to 80% by mass, more preferably 5 to 70% by mass, and even more preferably 10 to 50% by mass.

[0065] The composition of the present invention may further contain light stabilizers such as benzotriazole, benzophenone, and hindered amine types, antioxidants such as phosphite and hindered phenol types, thermal polymerization inhibitors, thiol compounds, photosensitizers, photosensitizers, chain transfer inhibitors, polymerization inhibitors, adhesion promoters, defoamers, crosslinking agents, surfactants, thermosetting accelerators, thermoplastic resins, thermosetting resins, thickeners such as urethane diacrylate, and the like. Furthermore, spherical or cylindrical spacers made of silica, glass, plastic, ceramic, or other materials may be added to control the cell gap as a dimming element. In this case, the cell gap can be set in the range of 2 to 100 μm.

[0066] The composition of the present invention is obtained by mixing and stirring the essential components, an anthraquinone compound represented by formula (1) and a liquid crystal material, and optionally other optional components such as a photocurable compound and a photopolymerization initiator. Mixing and stirring can be done simply by manually stirring all the components in a container, but it is more effective to stir using equipment such as a magnetic stirrer. Furthermore, in order to efficiently prepare a homogeneous composition, it is preferable to first prepare a homogeneous mixture of the photocurable compound, the photopolymerization initiator and the liquid crystal material, and then add the anthraquinone compound represented by formula (1) and other optional components and stir and mix. Heating may be applied during stirring and mixing if necessary. It is preferable to stir and mix under a light source emitting the absorption wavelength of the photopolymerization initiator for as short a time as possible. After mixing each component, filtration may be further performed using a mesh, membrane filter, etc.

[0067] By irradiating the composition of the present invention, which contains a photocurable compound and a photopolymerization initiator, with light, a cured liquid crystal composition is obtained in which the photocurable compound component has been cured (polymerized). In this invention, "cured product" refers to a state in which the functional groups of the photocurable compound have been polymerized or copolymerized by irradiation with light, and does not necessarily mean a cured product in which the anthraquinone compound represented by formula (1) or liquid crystal material has contributed to the curing reaction. The light source used for irradiation is not particularly limited, as long as it is capable of irradiating light at wavelengths absorbed by the photopolymerization initiator. Preferred light sources include high-pressure mercury lamps, metal halide lamps, xenon lamps, and halogen lamps, which are capable of irradiating ultraviolet light.

[0068] The dimming element of the present invention comprises a layer of the liquid crystal composition or its photocured product sandwiched between a pair of substrates, each having a transparent substrate with at least one transparent electrode, arranged opposite each other. Examples of substrates include colorless, colored, or opaque inorganic transparent materials such as glass or quartz, metals, metal oxides, semiconductors, ceramics, plastic plates, and plastic films. The electrodes are formed on the substrate by known coating methods, printing methods, or vapor deposition methods such as sputtering, using thin films of metal oxides, metals, semiconductors, or organic conductive materials on the entire or partial surface of the substrate. In particular, to obtain large-area dimming elements, it is desirable to use electrode substrates in which ITO (indium oxide, tin oxide) electrodes are formed on a transparent polymer film such as PET using vapor deposition methods such as sputtering or printing, from the viewpoint of productivity and processability. It is more preferable that both substrates in the pair are transparent substrates having transparent electrodes. Electrodes or wiring connecting electrodes to the outside may be provided on the substrate. For example, segment driving electrode substrates, matrix driving electrode substrates, active matrix driving electrode substrates, etc., may be used. Furthermore, the electrode surface provided on the substrate may be entirely or partially covered with a protective or aligning film made of an organic compound such as polyimide, polyamide, silicone, or cyanide compound, an inorganic compound such as SiO2, TiO2, or ZrO2, or a mixture thereof.

[0069] By using a plastic film as a substrate, a flexible and lightweight dimming element can be obtained. For this reason, the dimming element can be used by sandwiching it between a pair of flat or curved glass or hard plastic surfaces with an adhesive layer such as polyvinyl butyral, vinyl acetate, double-sided tape, or adhesive in between. Alternatively, the dimming element can be attached to the surface of a single flat or curved glass or hard plastic surface with double-sided tape or adhesive. It can also be sandwiched between soft plastics, or attached to one or both sides. Furthermore, a protective layer such as a hard coat, an ultraviolet cut layer, an infrared cut layer, or a half mirror may be provided on the substrate surface opposite the electrode surface of the dimming element, or a color filter may be laminated or a polarizer filter may be attached. It can also be laminated as an electroluminescent display element, a light-emitting diode display element, an electrochromic display element, or other liquid crystal display element.

[0070] The drive device for applying voltage to the dimming element of the present invention is a device capable of applying a DC voltage of 2 to 100V or an AC voltage of 10 to 1000Hz, and when no voltage is applied, it is sufficient to open or short-circuit the electrodes. Furthermore, this drive device may be equipped with a voltage application circuit for segment driving, a voltage application circuit for matrix driving, a voltage application circuit for active matrix, and so on.

[0071] The anthraquinone compound represented by formula (1) of the present invention has high light resistance, and a dimming element using it can achieve high-quality display with minimal color change over long periods of time. Furthermore, because it has excellent light resistance to long-term outdoor exposure to light at high temperatures, the dimming element of the present invention is ideal for automotive or building material applications. [Examples]

[0072] 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 this text, "parts" and "%" refer to mass unless otherwise specified. The maximum absorption wavelengths in the examples were measured using a spectrophotometer "UV-3150" manufactured by Shimadzu Corporation.

[0073] Example 1 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 8) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (11), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of 1-fluoro-4-iodobenzene, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.2 parts of the compound represented by Specific Example No. 8 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 651 nm.

[0074] [ka]

[0075] Example 2 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 9) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (12), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of 4-iodobenzonitrile, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.15 parts of the compound represented by Specific Example No. 9 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 650 nm.

[0076] [ka]

[0077] Example 3 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 10) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (13), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of ethyl 4-iodobenzoate, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.18 parts of the compound represented by Specific Example No. 10 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 655 nm.

[0078] [ka]

[0079] Example 4 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 19) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (14), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of 4-iodobenzonitrile, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.1 parts of the compound represented by Specific Example No. 19 as a brown solid. The maximum absorption wavelength of this compound in toluene was 651 nm.

[0080] [ka]

[0081] Example 5 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 5) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (15), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of 4-iodobenzonitrile, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.15 parts of the compound represented by Specific Example No. 5 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 651 nm.

[0082] [ka]

[0083] Example 6 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 7) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (16), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.5 parts of 1-chloro-4-iodobenzene, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.05 parts of the compound represented by Specific Example No. 7 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 652 nm.

[0084] [ka]

[0085] Example 7 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 11) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (17), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of 4-iodoacetophenone, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.15 parts of the compound represented by Specific Example No. 11 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 654 nm.

[0086] [ka]

[0087] Example 8 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 12) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (18), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of 4-iodobenzotrifluoride, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.11 parts of the compound represented by Specific Example No. 12 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 651 nm.

[0088] [ka]

[0089] Example 9 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 15) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (19), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of 4-iodobenzonitrile, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.1 parts of the compound represented by Specific Example No. 15 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 651 nm.

[0090] [ka]

[0091] Example 10 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 18) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (20) below, 0.02 parts of copper powder, 0.02 parts of copper iodide, 4.0 parts of 2-ethylhexyl 4-iodobenzoate, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.1 parts of the compound represented by Specific Example No. 18 above as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 651 nm.

[0092] [ka]

[0093] Example 11 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 24) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (21), 0.025 parts of copper powder, 0.025 parts of copper iodide, 2.0 parts of 2-iodobenzotrifluoride, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 150 to 160°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.07 parts of the compound represented by Specific Example No. 24 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 649 nm.

[0094] [ka]

[0095] Example 12 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 28) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (22), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of 3-iodobenzonitrile, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.13 parts of the compound represented by Specific Example No. 28 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 650 nm.

[0096] [ka]

[0097] Example 13 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 33) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (23), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of 1-fluoro-4-iodobenzene, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.1 parts of the compound represented by Specific Example No. 33 as a brown solid. The maximum absorption wavelength of this compound in toluene was 652 nm.

[0098] [ka]

[0099] Example 14 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 35) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (24), 0.025 parts of copper powder, 0.025 parts of copper iodide, 2.5 parts of 3-fluoro-4-iodobenzonitrile, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 150 to 160°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.04 parts of the compound represented by Specific Example No. 35 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 648 nm.

[0100] [ka]

[0101] Example 15 (Synthesis of the anthraquinone compound of the present invention represented in specific example No. 37) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (25), 0.02 parts of copper powder, 0.02 parts of copper iodide, 2.0 parts of 1,2-difluoro-4-iodobenzene, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 140 to 150°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.07 parts of the compound represented by Specific Example No. 37 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 650 nm.

[0102] [ka]

[0103] Example 16 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 46) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (26), 0.03 parts of copper powder, 0.03 parts of copper iodide, 2.0 parts of 4-bromo-2-fluoroanisole, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 150 to 160°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered and washed with methanol, and then dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.03 parts of the compound represented by Specific Example No. 46 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 654 nm.

[0104] [ka]

[0105] Example 17 (Synthesis of the anthraquinone compound of the present invention represented by specific example No. 51) 20 parts of NMP were mixed with 0.9 parts of the compound represented by formula (27), 0.03 parts of copper powder, 0.03 parts of copper iodide, 2.5 parts of 1-bromo-3,4,5-trifluorobenzene, 0.02 parts of potassium carbonate, and 0.15 parts of sodium acetate. The mixture was stirred at 150 to 160°C for 12 hours, then the reaction mixture was cooled to 25°C, 200 parts of methanol were added, and the mixture was stirred for a further 1 hour. The reaction product was filtered, washed with methanol, and dried in a hot air dryer at 50°C for 24 hours. The resulting crude product was dissolved in toluene and purified by column chromatography using toluene as the developing solvent. The solvent was removed from the purified solution under reduced pressure, and the mixture was dried in a hot air dryer at 50°C for 24 hours to obtain 0.06 parts of the compound represented by Specific Example No. 51 as a dark brown solid. The maximum absorption wavelength of this compound in toluene was 649 nm.

[0106] [ka]

[0107] Synthesis Example 1 (Synthesis of a comparative compound) A compound represented by the following formula (X) was obtained in accordance with the description of Example 6 in Japanese Patent Publication No. 62-5941.

[0108] [ka]

[0109] Example 18 (Preparation of the liquid crystal composition of the present invention) 0.006 parts of the compound represented by Specific Example No. 8 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 the liquid crystal composition of the present invention.

[0110] Examples 19 to 34 and Comparative Example 1 (Preparation of the present invention and comparative liquid crystal compositions) The compound represented by No. 8 obtained in Example 1, the compound represented by specific example No. 9 obtained in Example 2, the compound represented by specific example No. 10 obtained in Example 3, the compound represented by specific example No. 19 obtained in Example 4, the compound represented by specific example No. 5 obtained in Example 5, the compound represented by specific example No. 7 obtained in Example 6, the compound represented by specific example No. 11 obtained in Example 7, the compound represented by specific example No. 12 obtained in Example 8, the compound represented by specific example No. 15 obtained in Example 9, the compound represented by specific example No. 18 obtained in Example 10, implementation The liquid crystal composition of the present invention and a comparative liquid crystal composition were obtained in accordance with Example 1, except that the compounds were changed to the compound represented by Specific Example No. 24 obtained in Example 11, the compound represented by Specific Example No. 28 obtained in Example 12, the compound represented by Specific Example No. 33 obtained in Example 13, the compound represented by Specific Example No. 35 obtained in Example 14, the compound represented by Specific Example No. 37 obtained in Example 15, the compound represented by Specific Example No. 46 obtained in Example 16, the compound represented by Specific Example No. 51 obtained in Example 17, and the comparative compound represented by formula (X) obtained in Synthesis Example 1.

[0111] Example 35 (Fabrication of the dimming element of the present invention) The liquid crystal composition obtained in Example 18 was sealed in an element with a substrate gap of 15 μm, consisting of two glass substrates, one above the other, each having a transparent electrode and a polyamide resin rubbing on the surface in contact with the liquid crystal to perform homogeneous orientation treatment. In the resulting element, the liquid crystal was in a homogeneous orientation state when no voltage was applied, and the dye molecules (anthraquinone compound obtained in Example 1) were also in a similar orientation state according to the liquid crystal.

[0112] Examples 36 to 51 and Comparative Example 2 (Fabrication of dimming elements for the present invention and comparison) The present invention and a comparative dimming element were fabricated in accordance with Example 35, except that the liquid crystal composition obtained in Example 18 was replaced with the liquid crystal compositions obtained in Examples 19 to 34 and Comparative Example 1, respectively.

[0113] (Lightfastness test of dimming element) A UV-cut filter with a wavelength of 380 nm or less was attached to the dimming elements obtained in Examples 35 to 51 and Comparative Example 2, and an illuminance of 650 W / m² was measured at 63°C. 2 The dimmers were subjected to a lightfastness test by irradiating them with a metal halide lamp for 100 hours. The transmittance of the dimmers before and after the lightfastness test was measured using a spectrophotometer in the range of 380 to 780 nm, both with no voltage applied and with a voltage (100V) applied. From the obtained transmission spectra, the chromaticity (L*, a*, b*) was calculated according to JIS Z 8781-4:2013, and the color difference (ΔEab) before and after the lightfastness test, both with no voltage applied and with a voltage (100V) applied, was calculated using the following formula. A smaller value of ΔEab indicates less color change before and after the lightfastness test, and thus better lightfastness. The results are shown in Table 1. ΔEab(L*, a*, b*)={(ΔL*) 2 +(Δa*) 2 +(Δb*) 2} 1 / 2

[0114] [Table 1]

[0115] As shown in Table 1, the dimming elements of Examples 35 to 51 showed smaller color differences before and after the lightfastness test than the dimming element of Comparative Example 2, both when no voltage was applied and when a voltage (100V) was applied, confirming that they had superior lightfastness.

[0116] Example 52 (Preparation of the liquid crystal composition of the present invention and fabrication of a black dimming element) To the liquid crystal composition obtained in Example 19, 0.005 parts of a compound represented by the following formula (30) and 0.006 parts of a compound represented by the following formula (31) were added and mixed at room temperature to obtain the black liquid crystal composition of the present invention. A black dimming element was fabricated in accordance with Example 35, except that the liquid crystal composition obtained in Example 18 was replaced with the black liquid crystal composition obtained above. The average transmittance difference of the obtained black dimming element at 400 to 700 nm was 31%, showing high contrast.

[0117] [ka]

[0118] [ka]

[0119] Example 53 (Preparation of the liquid crystal composition of the present invention and fabrication of a black dimming element) As a monofunctional monomer of the photocurable compound, 0.467 parts of isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.); as a difunctional monomer of the photocurable compound, 0.024 parts of triethylene glycol dimethacrylate (manufactured by Shin Nakamura Chemical Co., Ltd.); as liquid crystal materials, 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 0.040 parts of 1-cyano-4''-n-pentylterphenyl; as a photopolymerization initiator 0.005 parts of Irgacure TPO (manufactured by BASF) and 0.005 parts of Irgacure 184 (manufactured by BASF), along with 0.01 parts of the compound represented by Specific Example No. 9 obtained in Example 2, plus 0.009 parts of the compound represented by formula (30) and 0.007 parts of the compound represented by formula (31), were stirred at room temperature for 2 hours. Then, 0.010 parts of a 20 μm diameter spacer ("Micropearl (registered trademark) SP220" manufactured by Sekisui Chemical Co., Ltd.) were added and the mixture was further mixed at room temperature to obtain the liquid crystal composition of the present invention. Using an applicator, the liquid crystal composition containing the spacer agent was applied onto the ITO film of a 5cm square PET film, which had an ITO film on it, to form a liquid crystal composition layer. Next, this film and another 5cm square PET film, which also had an ITO film, were stacked so that the liquid crystal composition layer on the ITO film faced the other ITO film. After that, the resulting laminate of the two films and the liquid crystal composition layer was maintained at 23°C on a thermoplate, and the light intensity of the LED lamp at 365nm was 9mW / cm². 2A black dimming element was fabricated by setting it in a position where it would be visible and irradiating it with light for 1 minute to photocur the photocurable compound. The average transmittance difference of the obtained black dimming element at 400 to 700 nm was 29%, showing high contrast.

[0120] (Lightfastness test of black dimming element) The black dimming elements obtained in Examples 52 and 53 were subjected to an illuminance of 60 W / m² at 63°C. 2 The dimmers were subjected to a lightfastness test by irradiating them with a xenon lamp for 500 hours. The transmittance of the dimmers before and after the lightfastness test was measured using a spectrophotometer in the range of 380 to 780 nm, both with no voltage applied and with a voltage (100V) applied. From the obtained transmission spectra, the chromaticity (L*, a*, b*) was calculated according to JIS Z 8781-4:2013, and the color difference (ΔEab) before and after the lightfastness test, both with no voltage applied and with a voltage (100V) applied, was calculated using the following formula. A smaller value of ΔEab indicates less color change before and after the lightfastness test, and thus better lightfastness. ΔEab(L*, a*, b*)={(ΔL*) 2 +(Δa*) 2 +(Δb*) 2} 1 / 2 The black dimmable elements obtained in Examples 52 and 53 showed a color difference (ΔEab) of 3 or less in both the unapplied and applied voltage states even after 500 hours in a xenon lightfastness test, demonstrating excellent lightfastness during prolonged exposure to light. These results indicate that the black dimmable elements of Examples 52 and 53 are black liquid crystal dimmable elements with high lightfastness.

[0121] By using the liquid crystal composition of the present invention, a dimmable liquid crystal element with high light resistance can be obtained. Such a dimmable element can be suitably used in outdoor building materials and automotive applications where high durability is required. [Industrial applicability]

[0122] The anthraquinone compound of the present invention has dichroism and excellent lightfastness; therefore, by using a liquid crystal composition containing this compound, a dimmable liquid crystal element with high contrast and high lightfastness can be obtained. Such a dimmable element can be suitably used in outdoor building materials and automotive applications where high durability is required.

Claims

1. The following formula (1) 【Chemistry 1】 (wherein R １ and R ４ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, a halogen atom, -CO ２ R ９ , -OCOR ９ , -COR ９ , a cyano group or a trifluoromethyl group. R ２ , R ３ , R ５ and R ６ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a halogen atom, -CO ２ R ９ , -OCOR ９ , -COR ９ , a cyano group or a trifluoromethyl group. R ７ and R ８ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, or a linear or branched alkoxy group having 1 to 12 carbon atoms. R ９ each independently represent a linear or branched alkyl group having 1 to 12 carbon atoms, or the following formula (a) 【Chemistry 2】 (In the formula, R １０ ) or the following formula (b) 【Transformation 3】 (In the formula, R １１ R represents a substituent represented by ), where R represents a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms. １ ~R ６ At least one of them is a halogen atom, -CO ２ R ９ , -COR ９ (This represents a cyano group or a trifluoromethyl group.) An anthraquinone compound represented by the term.

2. R ９ The anthraquinone compound according to claim 1, wherein each is independently a linear or branched alkyl group having 1 to 8 carbon atoms.

3. R in equation (1) １ and R ４ However, each is independently a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, a fluorine atom, a chlorine atom, -CO ２ R ９ , -COR ９ , a cyano group or a trifluoromethyl group, R ２ , R ３ , R ５ and R ６ However, each is independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a fluorine atom, a chlorine atom, -CO ２ R ９ , -COR ９ The anthraquinone compound according to claim 2, wherein the group is a cyano group or a trifluoromethyl group.

4. R in equation (1) １ and R ４ However, each is independently a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a fluorine atom, and -CO ２ R ９ , -COR ９ , a cyano group or a trifluoromethyl group, R ２ , R ３ , R ５ and R ６ However, each is independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a fluorine atom, and -CO ２ R ９ , -COR ９ The anthraquinone compound according to claim 3, wherein the group is a cyano group or a trifluoromethyl group.

5. R in equation (1) ２ and R ５ The anthraquinone compound according to claim 3, wherein is a hydrogen atom.

6. R in equation (1) １ and R ３ Only one of them is a hydrogen atom, and R ４ and R ６ The anthraquinone compound according to claim 5, wherein only one of the two atoms is a hydrogen atom.

7. R in equation (1) ３ and R ６ The anthraquinone compound according to claim 5, wherein is a hydrogen atom.

8. R in equation (1) 4 The anthraquinone compound according to claim 7, wherein is a linear or branched alkyl group having 4 to 12 carbon atoms.

9. R in equation (1) ７ , R ８ The anthraquinone compound according to claim 1, wherein each is independently a linear or branched alkyl group having 4 to 12 carbon atoms or a linear or branched alkoxy group having 4 to 12 carbon atoms.

10. A liquid crystal composition containing an anthraquinone compound and a liquid crystal material according to any one of claims 1 to 9.

11. Furthermore, the liquid crystal composition according to claim 10, further comprising at least one dye compound other than the anthraquinone compound represented by formula (1).

12. The liquid crystal composition according to claim 10, further comprising a photocurable compound and a photopolymerization initiator.

13. A photocured product of the liquid crystal composition according to claim 12.

14. A dimming element comprising a pair of opposing substrates, at least one of which is a transparent substrate having a transparent electrode, with the liquid crystal composition according to claim 10 sandwiched between them.

15. A dimming element comprising a pair of opposing substrates, at least one of which is a transparent substrate having a transparent electrode, with the photocured material described in Claim 13 sandwiched between them.

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