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

Abstract

The present invention is an anthraquinone compound represented by the following formula (1) (wherein R1 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms, or a straight-chain or branched-chain alkoxy group having 1 to 12 carbon atoms. R2 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms, or a straight-chain or branched-chain alkoxy group having 1 to 8 carbon atoms). R2 may be a straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms. R1 may be a straight-chain or branched-chain alkoxy group having 1 to 8 carbon atoms, or a straight-chain or branched-chain alkyl group having 4 to 10 carbon atoms. The present invention also relates to a liquid crystal composition for dimming light containing this anthraquinone compound and a liquid crystal material. The present invention also relates to a light-diffusing element formed by clamping the light-diffusing liquid crystal composition or its photocurable between a pair of opposing substrates, each of which is a transparent substrate having at least one transparent electrode.

Description

Technology Field

[0001] The present invention relates to a novel anthraquinone compound, a liquid crystal composition containing said compound, and a light-diffusing element. Background Technology

[0002] It is becoming common practice to use dimming panels instead of blinds for the purpose of protecting privacy in vehicles such as subways and automobiles, and in windows, doors, and partitions of buildings such as business buildings and hospitals. These panels include films obtained by dispersing liquid crystals in a polymer, or films that form a dimming layer by utilizing the property of liquid crystal material to undergo phase separation during the photocuring of a composition containing a photocurable compound and liquid crystals. Typically, these dimming panels can block the field of view by controlling light transmission or scattering depending on whether voltage is applied, but they cannot block light, so glare tends to increase due to light scattering. Therefore, attempts are being made to use pigments in the materials of dimming panels for the purpose of reducing glare or improving contrast. For example, when such dimming panels are used in automotive windows, in addition to ensuring good visibility without blurring and achieving high contrast during transmission, light resistance is also required so that transmittance does not decrease even when irradiated with light for extended periods at high temperatures due to long-term exposure from outdoor use. Furthermore, there is a growing demand for black elements capable of blocking visible light for reasons of practicality and design.

[0003] To meet the above market demands, various liquid crystal display devices called GH (guest host) type using liquid crystal compositions containing pigments have been proposed. These liquid crystal display devices, which have characteristics such as viewing angle and brightness, are being commercialized for vehicle mounting and light-dimmer applications.

[0004] Dichromatic dyes generally used in liquid crystal compositions for light-diffusing devices require not only high contrast when used as a device, but also lightfastness, UV resistance, heat resistance, and compatibility (solubility) of the dichromatic dye with the components of the liquid crystal composition. Furthermore, in order to obtain a high-contrast black light-diffusing device, in addition to the above required characteristics, a red dye is required that has maximum absorption in the range of 500 to 550 nm, which is a wavelength region with high visual sensitivity, and has high contrast when used as a light-diffusing device, and measures are being taken to improve these characteristics. For example, Patent Documents 4 to 6 disclose dichromatic dyes having a maximum absorption wavelength in the range of 500 to 550 nm. However, light-diffusing devices using the dyes of said documents have insufficient contrast. A dichroic dye having a maximum absorption wavelength in the above range and excellent contrast and lightfastness of the device has not yet been discovered. Prior art literature

[0005] Japanese Patent Publication No. Sho 63-501512, Japanese Published Patent Publication No. Hei 03-47392, Japanese Published Patent Publication No. 2018-205746, Japanese Published Patent Publication No. 2000-336366, Japanese Published Patent Publication No. 2011-190314, Japanese Published Patent Publication No. 2009-108295 The problem to be solved

[0006] The first objective of the present invention is to provide a novel anthraquinone compound.

[0007] Another objective of the present invention is to provide a dichromatic pigment, which is a novel anthraquinone compound having a maximum absorption wavelength in a specific wavelength range, a liquid crystal composition containing said dichromatic pigment, and a light-diffusing element containing said composition having excellent contrast and light resistance. means of solving the problem

[0008] The inventors succeeded in obtaining a novel anthraquinone compound of a specific structure.

[0009] Furthermore, the inventors have discovered that by using this novel anthraquinone compound having a maximum absorption wavelength in a specific wavelength range, a light-diffusing element with excellent contrast and light resistance can be obtained.

[0010] That is, the various embodiments or embodiments included in the present invention are as follows.

[0011] [1]. Hagi-sik (1)

[0012]

[0013] An anthraquinone compound represented by (wherein R1 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms, or a straight-chain or branched-chain alkoxy group having 1 to 12 carbon atoms. R2 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms, or a straight-chain or branched-chain alkoxy group having 1 to 8 carbon atoms).

[0014] [2]. An anthraquinone compound described in claim [1], wherein R2 is a straight or branched alkyl group having 1 to 8 carbon atoms or a straight or branched alkoxy group having 1 to 4 carbon atoms.

[0015] [3]. An anthraquinone compound described in the preceding claim [2], wherein R2 is a straight or branched alkyl group having 1 to 4 carbon atoms.

[0016] [4]. An anthraquinone compound described in the preceding claim [3], wherein R2 is a branched alkyl group having 3 or 4 carbon atoms.

[0017] [5]. An anthraquinone compound described in any one of claims [1] to [4], wherein R1 is a straight-chain or branched-chain alkoxy group having 1 to 8 carbon atoms.

[0018] [6]. An anthraquinone compound described in the preceding claim [5], wherein R1 is a straight or branched alkoxy group having 5 to 8 carbon atoms.

[0019] [7]. An anthraquinone compound described in any one of claims [1] to [4], wherein R1 is a straight or branched alkyl group having 4 to 10 carbon atoms.

[0020] [8]. An anthraquinone compound described in the preceding claim [7], in which R1 is a straight-chain alkyl group having 5 to 8 carbon atoms.

[0021] [9]. An anthraquinone compound described in any one of claims [1] to [8], having a maximum absorption wavelength of 500 to 550 nm.

[0022]

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

[0023]

[11] . Additionally, a light-diffusing liquid crystal composition described in the preceding claim

[10] containing a pigment compound other than the anthraquinone compound represented by formula (1).

[0024]

[12] . Additionally, a light-diffusing liquid crystal composition containing a photocurable compound and a photopolymerization initiator as described in the preceding claim

[10] or

[11] .

[0025]

[13] . A photocurable product of the light-diffusing liquid crystal composition described in the preceding paragraph

[12] .

[0026]

[14] . A light-diffusing element formed by squeezing a light-diffusing liquid crystal composition or a photocurable material described in claim

[13] between a pair of opposing substrates, at least one of which is a transparent substrate having a transparent electrode.

[0027]

[15] . A light-diffusing element described in the preceding paragraph

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

[0028] The anthraquinone compound of the present invention, having a maximum absorption wavelength in a specific wavelength range, has excellent light resistance, and by using a light-diffusing liquid crystal composition containing said anthraquinone compound, a light-diffusing element with excellent contrast and light resistance is obtained. Specific details for implementing the invention

[0029] (Form for carrying out the invention)

[0030] The present invention will be described in detail below.

[0031] The anthraquinone compound of the present invention is represented by the following formula (1).

[0032]

[0033] In formula (1), R1 represents a hydrogen atom, a straight or branched alkyl group having 1 to 12 carbon atoms, or a straight or branched alkoxy group having 1 to 12 carbon atoms.

[0034] The alkyl group having 1 to 12 carbon atoms represented by R1 in Formula (1) may be either a straight chain or a branched chain. Specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, a t-butyl group, an n-pentyl group, an iso-pentyl group, a neo-pentyl group, a t-pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a 2-ethylhexyl group, a 2-propylhexyl group, a 2-butylhexyl group, a 2-pentylhexyl group, and a 2-pentylheptyl group. The number of carbon atoms in the straight-chain alkyl group is preferably 4 to 10, and more preferably 5 to 8. In addition, the number of carbon atoms in the alkyl group of the branched chain is preferably 3 to 6, and more preferably 3 or 4.

[0035] The alkoxy group having 1 to 12 carbon atoms represented by R1 in formula (1) may be either a straight chain or a branched chain. Specific examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, an iso-butoxy group, a sec-butoxy group, a t-butoxy group, an n-pentyloxy group, an iso-pentyloxy group, a neo-pentyloxy group, a t-pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, an undecyloxyl group, a dodecyloxy group, a 2-ethylhexyloxy group, a 2-propylhexyloxy group, a 2-butylhexyloxy group, a 2-pentylhexyloxy group, and a 2-pentylheptyloxy group. A straight or branched alkoxy group having 1 to 8 carbon atoms is preferred, and a straight or branched alkoxy group having 5 to 8 carbon atoms is more preferred. A straight alkoxy group having 5 to 8 carbon atoms is even more preferred.

[0036] As R1 of Formula (1), a straight-chain alkyl group having 1 to 10 carbon atoms, a branched-chain alkyl group having 3 to 6 carbon atoms, or a straight-chain or branched-chain alkoxy group having 1 to 8 carbon atoms is preferred. A straight-chain alkyl group having 4 to 10 carbon atoms, a branched-chain alkyl group having 3 or 4 carbon atoms, or a straight-chain or branched-chain alkoxy group having 5 to 8 carbon atoms is more preferred. A straight-chain alkyl group having 5 to 8 carbon atoms or a straight-chain alkoxy group having 5 to 8 carbon atoms is even more preferred.

[0037] In formula (1), R2 represents a hydrogen atom, a straight or branched alkyl group having 1 to 8 carbon atoms, or a straight or branched alkoxy group having 1 to 8 carbon atoms.

[0038] The alkyl group having 1 to 8 carbon atoms represented by R2 in Formula (1) may be either a straight chain or a branched chain. Specific examples thereof include methyl groups, ethyl groups, n-propyl groups, iso-propyl groups, n-butyl groups, iso-butyl groups, sec-butyl groups, t-butyl groups, n-pentyl groups, iso-pentyl groups, neo-pentyl groups, t-pentyl groups, hexyl groups, heptyl groups, octyl groups, and 2-ethylhexyl groups. A straight or branched alkyl group having 1 to 4 carbon atoms is preferred, and a branched alkyl group having 3 or 4 carbon atoms is more preferred.

[0039] The alkoxy group having 1 to 8 carbon atoms represented by R2 in Formula (1) may be either a straight chain or a branched chain. Specific examples thereof include methoxy groups, ethoxy groups, n-propoxy groups, iso-propoxy groups, n-butoxy groups, iso-butoxy groups, sec-butoxy groups, t-butoxy groups, n-pentyloxy groups, iso-pentyloxy groups, neo-pentyloxy groups, t-pentyloxy groups, hexyloxy groups, heptyloxy groups, octyloxy groups, and 2-ethylhexyloxy groups. A straight or branched alkoxy group having 1 to 4 carbon atoms is more preferred. A straight alkoxy group having 1 to 4 carbon atoms is even more preferred.

[0040] As R2 of formula (1), a straight or branched alkyl group having 1 to 8 carbon atoms or a straight or branched alkoxy group having 1 to 4 carbon atoms is preferred. A straight or branched alkyl group having 1 to 4 carbon atoms or a straight or branched alkoxy group having 1 to 4 carbon atoms is more preferred, a straight or branched alkyl group having 3 or 4 carbon atoms is even more preferred, and a branched alkyl group having 3 or 4 carbon atoms is even more preferred.

[0041] Suitable specific examples of the compound represented by the above formula (1) include the following, but the present invention is not limited to these.

[0042]

[0043]

[0044]

[0045]

[0046] As a compound represented by Formula (1), it is preferable that it has a maximum absorption wavelength at 500 to 550 nm. In addition, as a compound represented by Formula (1), it is preferable that it has a transmittance difference of 43% or more when used as a device. In addition, as a compound represented by Formula (1), it is preferable that it has a maximum absorption wavelength at 500 to 550 nm and a transmittance difference of 43% or more when used as a device. By using a liquid crystal composition comprising a compound having a maximum absorption wavelength in the above range and / or a high transmittance difference in a light-diffusing device, the contrast of the light-diffusing device is improved.

[0047] The compound represented by formula (1) can be synthesized using a conventional known method described in, for example, Japanese Patent Publication No. 2003-192664.

[0048] Specifically, for example, it is possible to synthesize by reacting a 1,5-dichloroanthraquinone compound and an aniline derivative represented by the following formula (A) at 110 to 120°C in a solvent such as xylene under basic conditions such as tripotassium phosphate and under a catalyst such as palladium or copper powder, then reacting a thiol represented by the following formula (B) at 50 to 60°C under basic conditions, and then reacting a benzyl chloride derivative represented by the following formula (C) at 70 to 80°C under basic conditions. In addition, R1 of the following formula (A) and R2 of the following formula (C) have the same meaning as R1 and R2 in formula (1).

[0049]

[0050] The liquid crystal composition of the present invention (hereinafter simply referred to as "composition of the present invention") contains an anthraquinone compound represented by formula (1) and a liquid crystal material.

[0051] The content ratio of the anthraquinone compound represented by Formula (1) in the liquid crystal composition is not particularly limited, but it is preferably 0.5 to 10 parts by mass per 100 parts by mass of the liquid crystal material, and more preferably 0.5 to 5 parts by mass. When a dichromatic pigment (described later) other than the compound represented by Formula (1) is used in combination, it is preferable that the total content of the anthraquinone compound represented by Formula (1) and the dichromatic pigment other than the compound represented by Formula (1) be within the above range (0.5 to 10 parts by mass) per 100 parts by mass of the liquid crystal material.

[0052] The liquid crystal material contained in the liquid crystal composition of the present invention is not particularly limited as long as it is a material having liquid crystal properties (a compound having liquid crystal properties), such as a nematic liquid crystal, a cholesteric liquid crystal, or a smectic liquid crystal, but among these, a nematic liquid crystal is preferred. Examples of compounds having liquid crystal properties include liquid crystal compounds described in paragraphs 154 to 192 and 715 to 722 of the "Handbook of Liquid Crystal Devices" (compiled by the 142nd Committee of the Society for the Promotion of Science of Japan, Nikkan Kogyo Shimbun, 1989).

[0053] The liquid crystal composition of the present invention may contain a dichromatic pigment other than the anthraquinone compound represented by formula (1), an optically active material that exhibits or does not exhibit a liquid crystal phase such as cholesteryl nonanoate, an ultraviolet absorber and an antioxidant, each additive such as a photocurable compound and a photopolymerization initiator.

[0054] The photocurable compound that may be contained in the liquid crystal composition of the present invention is not particularly limited, provided that it is a compound having a functional group capable of polymerization by the action of a photopolymerization initiator described below when irradiated with light. Examples of photocurable compounds include compounds having (meth)acrylate groups, compounds having vinyl groups, and compounds having allyl groups. Compounds having (meth)acrylate groups are preferred. Furthermore, in this specification, the term "(meth)acrylate" means "methacrylate and / or acrylate."

[0055] The (meth)acrylate compounds contained in the liquid crystal composition of the present invention include, for example, 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, but are not limited thereto.

[0056] As a mono(meth)acrylate compound, a mono(meth)acrylate having a straight-chain, cyclic, or branched alkyl group having 5 to 13 carbon atoms is preferred. Specific examples thereof include straight-chain 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; 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. Examples include branched chain alkyl mono(meth)acrylates.

[0057] Examples of di(meth)acrylate compounds include, for instance, 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, and additionally, trialkylene glycol di(meth)acrylates such as triethylene glycol di(meth)acrylate.

[0058] In the liquid crystal composition of the present invention, a mono(meth)acrylate compound and a di(meth)acrylate compound may be used in combination. 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.

[0059] 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 capable of polymerizing a photocurable compound by irradiation with light. It is desirable that the dichromatic pigment, such as an anthraquinone compound represented by Formula (1), does not remain in the cured product after irradiation with light.

[0060] As a photopolymerization initiator, for example, 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 of the anthraquinone compound and liquid crystal material represented by Formula (1) to the photocurable compound is preferably 90:10 to 50:50 by mass, more preferably 80:20 to 50:50, and even more preferably 65:35 to 50:50. By setting the ratio of the photocurable compound to the above range, it is possible to prevent the liquid crystal material and the photocurable compound from separating before curing by light irradiation and to prevent the light-shielding properties of the cured product from decreasing.

[0062] In addition, when a dichromatic pigment (described later) other than the compound represented by Formula (1) is used in combination, the ratio of the total of all dichromatic pigments and liquid crystal materials including the anthraquinone compound represented by Formula (1) in the composition of the present invention to the photocurable compound is preferably in the above range (90:10 to 50:50 in mass ratio), and more preferably and even more preferably ranges are the same as above.

[0063] In the composition of the present invention containing a photocurable compound and a photopolymerization initiator, the content of the photopolymerization initiator is preferably 0.1 to 5 parts by mass per 100 parts by mass of the photocurable compound.

[0064] In the composition of the present invention, a dichromatic pigment other than the anthraquinone compound represented by Formula (1) may be used in combination.

[0065] The dichromatic dyes that can be used in combination are not particularly limited, but may be selected from, for example, azo dyes, anthraquinone dyes, perylene dyes, quinophthalone dyes, melocyanine 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) can be cited.

[0066] 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.

[0067] When a dichromatic pigment other than the anthraquinone compound represented by Formula (1) is used in combination, the content of the anthraquinone compound represented by Formula (1) in the total dichromatic pigment is not particularly limited as long as it is within a range that does not impair the effects of the present invention. The amount thereof is preferably 1 to 80 mass%, more preferably 5 to 70 mass%, and even more preferably 10 to 50 mass%.

[0068] In addition, the composition of the present invention may also use light stabilizers such as benzotriazole-based, benzophenone-based, and hindered amine-based agents, antioxidants such as phosphite-based and hindered phenol-based agents, thermal polymerization inhibitors, thiol compounds, photosensitive agents, photosensitive agents, chain transfer inhibitors, polymerization inhibitors, adhesion promoters, defoaming agents, crosslinking agents, surfactants, thermal curing accelerators, thermoplastic resins, thermosetting resins, thickeners such as urethane diacrylate, etc.

[0069] In addition, to control the cell gap as a light-diffusing element, a spherical or cylindrical spacer made of silica, glass, plastic, ceramic, etc. may be added. At this time, the cell gap can be set in the range of 2 to 100 μm.

[0070] The composition of the present invention is obtained by mixing and stirring an anthraquinone compound represented by Formula (1) and a liquid crystal material, which are essential components, and other optional components such as a photocurable compound and a photopolymerization initiator, which are added as needed. Mixing and stirring can be performed simply by placing all components into a container and stirring manually, but it is effective to perform stirring using a device such as a magnetic stirrer. Furthermore, in order to efficiently produce a uniform composition, it is preferable to first prepare a uniform 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 performed during stirring and mixing if necessary. It is preferable to perform stirring and mixing under a light source that emits the absorption wavelength of the photopolymerization initiator in the shortest possible time. After mixing each component, filtration may be performed using a mesh, a membrane filter, etc.

[0071] By irradiating light onto the composition of the present invention containing a photocurable compound and a photopolymerization initiator, a photocurable product of a liquid crystal composition in which the photocurable compound is cured (polymerized) is obtained. Furthermore, in the present invention, "photocurable product" refers to a state in which the functional groups of the photocurable compound are polymerized or copolymerized by irradiation with light, and does not necessarily refer to a cured product in which the anthraquinone compound or liquid crystal material represented by Formula (1) contributed to the curing reaction.

[0072] As for the light source when irradiating, it is not particularly limited as long as it is a light source capable of irradiating light of a wavelength absorbed by the photopolymerization initiator. Preferred light sources include high-pressure mercury lamps, metal halide lamps, xenon lamps, and halogen lamps capable of irradiating ultraviolet rays.

[0073] The light-diffusing element of the present invention is formed by a layer of the liquid crystal composition or its photocurable material being clamped between a pair of substrates, wherein at least one of which is a transparent substrate having a transparent electrode. Here, the substrate may be, for example, an inorganic transparent material such as glass or quartz, or a colorless transparent, colored transparent, or opaque material such as a metal, metal oxide, semiconductor, ceramic, plastic plate, or plastic film. The electrode is formed on the substrate by a thin film, for example, a metal oxide, metal, semiconductor, or organic conductive material, on the entire surface or partially of the substrate by a known coating method, printing method, or deposition method such as sputtering. In particular, to obtain a large-area light-diffusing element, it is preferable to use an electrode substrate in which an ITO (indium oxide, tin oxide) electrode is formed on a transparent polymer film such as PET using a deposition method such as sputtering or a printing method, from the perspective of productivity and processability. It is more preferable that both of the pair of substrates are transparent substrates having transparent electrodes. Additionally, an electrode or wiring for connecting the electrode to the outside may be formed on the substrate. For example, a segment driving electrode substrate, a matrix driving electrode substrate, or an active matrix driving electrode substrate may be used. In addition, the entire surface or a part thereof may be covered by a protective film or an alignment film made of an organic compound such as polyimide, polyamide, silicon, or a cyanide compound, an inorganic compound such as SiO2, TiO2, or ZrO2, or a mixture thereof.

[0074] By using a plastic film as a substrate, a flexible and lightweight light-diffusing element is obtained. For this reason, the light-diffusing element can be inserted between a pair of planar or curved glass or hard plastics through an adhesive layer such as polyvinyl butyral, vinyl acetate, double-sided tape, or adhesive. Alternatively, the light-diffusing element can be attached to a single surface of planar or curved glass or hard plastic using double-sided tape or adhesive. Furthermore, the light-diffusing element may be inserted between soft plastics or attached to one or both sides. Additionally, a protective layer such as a hard coating, an ultraviolet cut layer, an infrared cut layer, or a half mirror may be formed on the substrate surface opposite to the electrode surface of the light-diffusing element, or a color filter may be laminated or a polarizer filter may be attached. Furthermore, the light-diffusing element may be laminated with an electroluminescence display element, a light-emitting diode display element, an electrochromic display element, or other liquid crystal display elements.

[0075] As a driving device for applying voltage to the dimming element of the present invention, it is a device capable of applying a DC voltage of 2 to 100 V or an AC voltage of 10 to 1000 Hz, and when not applying voltage, it is preferable to open or short-circuit the electrodes. In addition, the driving 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, etc.

[0076] A light-dimmer element using an anthraquinone compound represented by Formula (1) of the present invention can realize a high-contrast display. In addition, since it has excellent light resistance to long-term outdoor exposure, the light-dimmer element of the present invention is optimal for vehicle mounting or building material applications.

[0077] Examples

[0078] The present invention will be explained in more detail below by way of examples, but the present invention is not limited thereto.

[0079] In addition, "parts" and "%" in the text are based on mass unless otherwise noted. The maximum absorption wavelength in the examples is a value measured using a spectrophotometer "UV-3150" manufactured by Shimadzu Seisakusho Inc.

[0080] Example 1 (Synthesis of the anthraquinone compound of the present invention as shown in No. 16 of the specific example)

[0081] (Process 1-1) Synthesis of an intermediate compound represented by the following formula (2)

[0082] 1.7 parts of 2,2-bis(diphenylphosphino)-1,1-vinafthyl and 1.6 parts of tris(dibenzylideneacetone)dipalladium were added to 170 parts of xylene and stirred at 80°C for 10 minutes under a nitrogen atmosphere. Then, 10.0 parts of 1,5-dichloroanthraquinone, 11.5 parts of tripotassium phosphate, 10.3 parts of 4-heptylaniline and 34 parts of N-methyl-2-pyrrolidone were added and stirred at 120°C for 12 hours. After cooling the reaction mixture to 45°C, 340 parts of methanol were added and stirred for 30 minutes. The reaction product was filtered and taken, and then 142 parts of toluene and 71 parts of methanol were added and stirred for 30 minutes, followed by filtration. The reaction product obtained by concentrating the filtrate under reduced pressure was dried in a hot air dryer at 80°C for 24 hours to obtain 4.7 parts of an intermediate compound represented by the following formula (2).

[0083]

[0084] (Process 1-2) Synthesis of an intermediate compound represented by the following formula (3)

[0085] 60 parts of N,N-dimethylformamide were added to 4.6 parts of the intermediate compound represented by Formula (2) obtained in process (1-1), 5.1 parts of potassium carbonate, and 2.7 parts of 4-hydroxybenzenethiol, and stirred at 50°C for 1 hour. After cooling the reaction mixture to 30°C, 129 parts of methanol and 92 parts of water were added and stirred for 20 minutes. The reaction product was filtered and taken and dried in a hot air dryer at 80°C for 24 hours to obtain 4.4 parts of the intermediate compound represented by Formula (3) below.

[0086]

[0087] Process (1-3) Synthesis of the compound represented by No. 16 of the specific example

[0088] 4.4 parts of the intermediate compound represented by Formula (3) obtained in Process (1-2), 2.3 parts of potassium carbonate, and 2.3 parts of 4-t-butylbenzyl chloride were added to 56 parts of N-methyl-2-pyrrolidone, stirred at 80°C for 1 hour, then cooled the reaction mixture to 40°C, added 112 parts of methanol, and stirred for 20 minutes. The reaction product was filtered and dried in a hot air dryer at 80°C for 24 hours. The obtained crude was dissolved in toluene, and column purification was performed using toluene:hexane = 2:1 as the developing solvent. The solvent was removed from the solution after purification by vacuum distillation, and by drying in a vacuum dryer at 50°C for 24 hours, 2.9 parts of the compound represented as No. 16 of the above example were obtained as a red solid. The maximum absorption wavelength of this compound in methanol was 518 nm.

[0089] Example 2 (Synthesis of the anthraquinone compound of the present invention as shown in Example No. 15)

[0090] Process (2-1)

[0091] Except for changing 10.3 parts of 4-heptylaniline in Process 1-1 to 8.1 parts of 4-butylaniline, the process was carried out in the same manner as Example 1, and 3.0 parts of the compound shown as No. 15 of the above example were obtained as a red solid. The maximum absorption wavelength of this compound in methanol was 513 nm.

[0092] Example 3 (Synthesis of the anthraquinone compound of the present invention as shown in Example No. 17)

[0093] Process (3-1)

[0094] Except for changing 10.3 parts of 4-heptylaniline in Process 1-1 to 12.6 parts of 4-decylaniline, the process was carried out in the same manner as Example 1, and 3.0 parts of the compound shown as No. 17 of the above example were obtained as a red solid. The maximum absorption wavelength of this compound in methanol was 515 nm.

[0095] Example 4 (Synthesis of the anthraquinone compound of the present invention as shown in Example No. 26)

[0096] Process (4-1)

[0097] Except for changing 10.3 parts of 4-heptylaniline in Process 1-1 to 11.2 parts of 4-heptyloxyaniline, the process was carried out in the same manner as Example 1, and 3.0 parts of the compound shown as No. 26 of the above example were obtained as a red solid. The maximum absorption wavelength of this compound in methanol was 515 nm.

[0098] Example 5 (Synthesis of the anthraquinone compound of the present invention as shown in Example No. 32)

[0099] Process (5-1)

[0100] Except for changing 10.3 parts of 4-heptylaniline in Process 1-1 to 8.1 parts of 4-butylaniline and changing 2.3 parts of 4-t-butylbenzyl chloride in Process 1-3 to 2.3 parts of 1-butoxy-4-chloromethylbenzene, the process was carried out in the same manner as in Example 1, and 3.0 parts of the compound represented as No. 32 of the above-mentioned Specific Example were obtained as a red solid. The maximum absorption wavelength of this compound in methanol was 513 nm.

[0101] Example 6 (Synthesis of the anthraquinone compound of the present invention as shown in Example No. 34)

[0102] Process (6-1)

[0103] Except for changing 10.3 parts of 4-heptylaniline in Process 1-1 to 8.1 parts of 4-sec-butylaniline, the process was carried out in the same manner as Example 1, and 3.0 parts of the compound shown as No. 34 of the above example were obtained as a red solid. The maximum absorption wavelength of this compound in methanol was 513 nm.

[0104] Comparative Example 1 (Synthesis of Comparative Example Compound)

[0105] Except for changing 10.3 parts of 4-heptylaniline in Process 1-1 to 4.3 parts of 4-butylaniline and changing 2.7 parts of 4-hydroxybenzenethiol in Process 1-2 to 3.5 parts of 4-t-butylbenzenethiol, and not performing any subsequent processes, the same procedure as in Example 1 was followed to obtain 2.9 parts of a compound represented by the following formula (X) as a red solid. The maximum absorption wavelength of this compound in methanol was 518 nm.

[0106]

[0107] Comparative Example 2 (Synthesis of Comparative Example Compound)

[0108] Except for changing 2.3 parts of 4-t-butylbenzyl chloride in process 1-3 to 1.4 parts of 1-bromobutane, the process was carried out in the same manner as in Example 1, and 2.9 parts of the compound represented by the following formula (Y) were obtained as a red solid. The maximum absorption wavelength of this compound in methanol was 515 nm.

[0109]

[0110] Reference Example (Transmittance ratio at the maximum absorption wavelength of anthraquinone compounds of the Example and Comparative Example)

[0111] A methanol solution of the same concentration was prepared using each of the following compounds: the compound represented by No. 16 of the specific example obtained in Example 1, the compound represented by No. 15 of the specific example obtained in Example 2, the compound represented by No. 17 of the specific example obtained in Example 3, the compound represented by No. 26 of the specific example obtained in Example 4, the compound represented by No. 32 of the specific example obtained in Example 5, the compound represented by No. 34 of the specific example obtained in Example 6, the compound represented by Formula (X) obtained in Comparative Example 1, the compound represented by Formula (Y) obtained in Comparative Example 2, and the compound represented by Formula (Z) below (comparative compound, maximum absorption wavelength in methanol is 520 nm). Then, the transmittance (%) at the maximum absorption wavelength of the methanol solution of each compound was measured. The transmittance ratios of each compound, with the transmittance at the maximum absorption wavelength of the compound represented by No. 16 as the denominator, were 0.75 for the compound represented by No. 15, 1.05 for the compound represented by No. 17, 0.75 for the compound represented by No. 26, 0.75 for the compound represented by No. 32, 0.75 for the compound represented by No. 34, 0.95 for the compound represented by Equation (X), 0.85 for the compound represented by Equation (Y), and 0.45 for the compound represented by Equation (Z).

[0112]

[0113] Example 7 (Preparation of the light-diffusing liquid crystal composition of the present invention)

[0114] 0.02 parts of the compound represented as No. 16 of the specific example obtained in Example 1, 0.380 parts of isobornyl acrylate (manufactured by Osaka Yuki Kagaku Kogyo, monoacrylate), 0.020 parts of triethylene glycol dimethacrylate (manufactured by Shinnakamura Kagaku Co., Ltd.), 0.306 parts of 1-cyano-4'-n-pentyl biphenyl, 0.15 parts of 1-cyano-4'-n-heptyl biphenyl, 0.096 parts of 1-cyano-4'-n-octyloxybiphenyl, 0.048 parts of 1-cyano-4'-n-pentylterphenyl, 0.004 parts of Yirgacure TPO (manufactured by BASF), 0.004 parts of Yirgacure 184 (manufactured by BASF), and a spacer agent with a diameter of 20 μm (manufactured by Sekisui Kagaku Co., Ltd. The liquid crystal composition of the present invention was prepared by mixing 0.010 parts of micropearl (registered trademark) SP220 at room temperature, stirring at 50°C for 2 hours, cooling to room temperature, and passing through a 1 μm membrane filter.

[0115] Example 8 (Preparation of the light-diffusing liquid crystal composition of the present invention)

[0116] A liquid crystal composition of the present invention was prepared in the same manner as in Example 7, except that 0.02 parts of the compound represented as No. 16 of the specific example obtained in Example 1 were changed to 0.015 parts of the compound represented as No. 15 of the specific example obtained in Example 2 (the amount of compound represented as No. 16 in Example 7 (0.02 parts) × the transmittance ratio of the compound represented as No. 15 in the reference example above (0.75)).

[0117] Example 9 (Preparation of the light-diffusing liquid crystal composition of the present invention)

[0118] A liquid crystal composition of the present invention was prepared in the same manner as in Example 7, except that 0.02 parts of the compound represented as No. 16 of the specific example obtained in Example 1 were changed to 0.021 parts of the compound represented as No. 17 of the specific example obtained in Example 3 (the amount of compound represented as No. 16 in Example 7 (0.02 parts) × the transmittance ratio of the compound represented as No. 17 in the above reference example (1.05)).

[0119] Example 10 (Preparation of the light-diffusing liquid crystal composition of the present invention)

[0120] The liquid crystal composition of the present invention was prepared in the same manner as in Example 7, except that 0.02 parts of the compound represented as No. 16 of the specific example obtained in Example 1 were changed to 0.015 parts of the compound represented as No. 26 of the specific example obtained in Example 4 (the amount of compound represented as No. 16 in Example 7 (0.02 parts) × the transmittance ratio of the compound represented as No. 26 in the reference example above (0.75)).

[0121] Example 11 (Preparation of the light-diffusing liquid crystal composition of the present invention)

[0122] A liquid crystal composition of the present invention was prepared in the same manner as in Example 7, except that 0.02 parts of the compound represented as No. 16 of the specific example obtained in Example 1 were changed to 0.015 parts of the compound represented as No. 32 of the specific example obtained in Example 5 (the amount of compound represented as No. 16 in Example 7 (0.02 parts) × the transmittance ratio of the compound represented as No. 32 in the above reference example (0.75)).

[0123] Example 12 (Preparation of the light-diffusing liquid crystal composition of the present invention)

[0124] A liquid crystal composition of the present invention was prepared in the same manner as in Example 7, except that 0.02 parts of the compound represented as No. 16 of the specific example obtained in Example 1 were changed to 0.015 parts of the compound represented as No. 34 of the specific example obtained in Example 6 (the amount of compound represented as No. 16 in Example 7 (0.02 parts) × the transmittance ratio of the compound represented as No. 34 in the above reference example (0.75)).

[0125] Comparative Example 3 (Preparation of a light-diffusing liquid crystal composition for comparison)

[0126] A comparative liquid crystal composition was prepared in the same manner as in Example 7, except that 0.02 parts of the compound represented by No. 16 of the specific example obtained in Example 1 were changed to 0.019 parts of the compound represented by formula (X) obtained in Comparative Example 1 (the amount of compound represented by No. 16 in Example 7 (0.02 parts) × the transmittance ratio of the compound represented by formula (X) in the above reference example (0.95)).

[0127] Comparative Example 4 (Preparation of a light-diffusing liquid crystal composition for comparison)

[0128] A comparative liquid crystal composition was prepared in the same manner as in Example 7, except that 0.02 parts of the compound represented by No. 16 of the specific example obtained in Example 1 were changed to 0.017 parts of the compound represented by formula (Y) obtained in Comparative Example 2 (the amount of compound represented by No. 16 in Example 7 (0.02 parts) × the transmittance ratio of the compound represented by formula (Y) in the above reference example (0.85)).

[0129] Comparative Example 5 (Preparation of a light-diffusing liquid crystal composition for comparison)

[0130] A comparative liquid crystal composition was prepared in the same manner as in Example 7, except that 0.02 parts of the compound represented by No. 16 of the specific example obtained in Example 1 were changed to 0.009 parts of the compound represented by the formula (Z) above (the amount of compound represented by No. 16 in Example 7 (0.02 parts) × the transmittance ratio of the compound represented by the formula (Z) in the reference example above (0.45)).

[0131] Examples 13 to 18 and Comparative Examples 6 to 8 (Fabrication of the light-diffusing element for the present invention and comparison)

[0132] A liquid crystal composition obtained in Examples 7 to 12 and Comparative Examples 3 to 5 was applied, respectively, onto the ITO film of a 5 cm square PET film having an ITO film formed thereon using an applicator to form a liquid crystal composition layer. Subsequently, this film and a 5 cm square PET film having the same ITO film formed thereon were overlapped such that the liquid crystal composition layer on the ITO film and the ITO film faced each other. After that, while maintaining the sample of the laminate of the two films and the liquid crystal composition layer obtained in this manner at 23°C using a thermoplate, the sample was set at a position where the light intensity of a 365 nm LED lamp was 9 mW / cm², and light irradiation was performed for 1 minute to photo-cur the photocurable compound, thereby obtaining the light-diffusing element of the present invention and a light-diffusing element for comparison, respectively.

[0133] (Calculation of transmittance difference of light-diffusing elements)

[0134] For the light-diffusing elements obtained in Examples 13 to 18 and Comparative Examples 6 to 8, the difference in transmittance (change in transmittance) between the application of the voltage and the non-application of the voltage was calculated from the measurement results of the transmittance (%) at the maximum absorption wavelength when a 100V AC voltage (50Hz sinusoidal wave) is applied and when it is not applied (when light is blocked). The results are shown in Table 1.

[0135] As shown in Table 1, it is evident that the dimming elements of Examples 13 to 18 have a larger difference in transmittance between when voltage is applied and when it is not applied compared to the dimming elements of Comparative Examples 6 to 8, and thus have superior contrast.

[0136]

[0137] (Lightfastness test of light-diffusing elements)

[0138] Each light-diffusing element obtained in Examples 13 to 18 was subjected to light irradiation for 500 hours using a xenon lamp. Afterward, the transmittance (%) at the maximum absorption wavelength was measured in the same manner as described in "Calculation of Transmittance Difference of Light-Diffusing Elements" above.

[0139] The dimming elements obtained in Examples 13 to 18 showed no change in transmittance even after 500 hours in a xenon lamp light resistance test, and also exhibited excellent light resistance when exposed to light for a long time. From these results, it was shown that the dimming elements of Examples 13 to 18 have excellent light resistance.

[0140] Example 19 (Preparation of the light-diffusing liquid crystal composition of the present invention)

[0141] A liquid crystal composition of the present invention was prepared by mixing 0.012 parts of the compound represented as No. 16 of the specific example 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 at room temperature.

[0142] Examples 20 to 24 and Comparative Examples 9 and 10 (Preparation of dimming liquid crystal compositions for the present invention and comparison)

[0143] A liquid crystal composition of the present invention and a liquid crystal composition for comparison were prepared in accordance with Example 19, except that the compound represented by No. 16 of the specific example obtained in Example 1 was changed to the compound represented by No. 15 of the specific example obtained in Example 2, the compound represented by No. 17 of the specific example obtained in Example 3, the compound represented by No. 26 of the specific example obtained in Example 4, the compound represented by No. 32 of the specific example obtained in Example 5, the compound represented by No. 34 of the specific example obtained in Example 6, the compound represented by Formula (X) obtained in Comparative Example 1, and the compound represented by Formula (Y) obtained in Comparative Example 2.

[0144] Examples 25 to 30 and Comparative Examples 11 and 12 (Preparation of the light-diffusing element for the present invention and comparison)

[0145] Each of the liquid crystal compositions obtained in Examples 19 to 24 and Comparative Examples 9 and 10 was encapsulated in a device with a gap of 15 μm between substrates, comprising two upper and lower glass substrates having a transparent electrode and undergoing homogeneous orientation treatment by rubbing a polyamide resin on the surface in contact with the liquid crystal. In the above device, when no voltage is applied, the liquid crystal is in a homogeneous orientation state, and the pigment molecules are also in the same orientation state according to the liquid crystal.

[0146] (Calculation of the order parameter (S value) of the light-diffusing element)

[0147] Linear polarization parallel to the orientation direction and linear polarization perpendicular to the orientation direction were incident on each of the light-diffusing elements obtained in Examples 25 to 30 and Comparative Examples 11 and 12. From each spectrum therefrom, the absorbance (A) for linear polarization parallel to the orientation direction of the colored cell / / Absorbance for linear polarization perpendicular to ) and orientation direction (A ⊥ ) was measured, and the order parameter (S value) at the maximum absorption wavelength (λmax) was calculated from the following equation. The results are shown in Table 2.

[0148] S=(A / / -A ⊥ ) / (2A ⊥ +A / / )

[0149]

[0150] As shown in the table, it is evident that the dimming elements of Examples 25 to 30 have higher order parameters than the dimming elements of Comparative Examples 11 and 12, and are superior as dimming elements.

[0151] (Lightfastness test of light-diffusing elements)

[0152] After irradiating each light-diffusing element obtained in Examples 25 to 30 with light for 500 hours using a xenon lamp, the transmittance (%) at the maximum absorption wavelength was measured in the same way as in the “calculation of the order parameter (S value) of the light-diffusing element” above.

[0153] The dimming elements obtained in Examples 25 to 30 showed no change in transmittance even after 500 hours in a xenon light resistance test, and also exhibited excellent light resistance when exposed to light for a long time. From these results, it was shown that the dimming elements of Examples 25 to 30 have excellent light resistance.

[0154] Industrial applicability

[0155] The anthraquinone compound of the present invention, having a maximum absorption wavelength in a specific wavelength range and a high transmittance difference, has excellent light resistance, and by using a light-diffusing liquid crystal composition containing said anthraquinone compound, a light-diffusing element with excellent contrast is obtained. The light-diffusing element of the present invention can be suitably used for outdoor building materials requiring high durability and for vehicle mounting applications.

Claims

Claim 1 Hagi-sik (1) An anthraquinone compound represented by (wherein R1 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms, or a straight-chain or branched-chain alkoxy group having 1 to 12 carbon atoms; and R2 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms, or a straight-chain or branched-chain alkoxy group having 1 to 8 carbon atoms). Claim 2 An anthraquinone compound according to claim 1, wherein R2 is a straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms or a straight-chain or branched-chain alkoxy group having 1 to 4 carbon atoms. Claim 3 An anthraquinone compound according to paragraph 2, wherein R2 is a straight-chain or branched-chain alkyl group having 1 to 4 carbon atoms. Claim 4 An anthraquinone compound in which R2 is a branched alkyl group having 3 or 4 carbon atoms, as described in paragraph 3. Claim 5 An anthraquinone compound according to paragraph 2, wherein R1 is a straight-chain or branched-chain alkoxy group having 1 to 8 carbon atoms. Claim 6 An anthraquinone compound according to claim 5, wherein R1 is a straight or branched alkoxy group having 5 to 8 carbon atoms. Claim 7 An anthraquinone compound according to paragraph 2, wherein R1 is a straight-chain or branched-chain alkyl group having 4 to 10 carbon atoms. Claim 8 An anthraquinone compound according to claim 7, wherein R1 is a straight-chain alkyl group having 5 to 8 carbon atoms. Claim 9 An anthraquinone compound according to claim 1, wherein R2 is a straight-chain or branched-chain alkyl group having 1 to 4 carbon atoms, and R1 is a straight-chain or branched-chain alkoxy group having 5 to 8 carbon atoms. Claim 10 An anthraquinone compound according to claim 1, wherein R2 is a straight-chain or branched-chain alkyl group having 1 to 4 carbon atoms, and R1 is a straight-chain or branched-chain alkyl group having 4 to 10 carbon atoms. Claim 11 An anthraquinone compound according to any one of claims 1 to 10, having a maximum absorption wavelength of 500 to 550 nm. Claim 12 A liquid crystal composition for dimming light containing an anthraquinone compound and a liquid crystal material as described in any one of claims 1 to 10. Claim 13 In claim 12, additionally, a light-diffusing liquid crystal composition containing a pigment compound other than the anthraquinone compound represented by formula (1). Claim 14 In claim 12, additionally, a light-diffusing liquid crystal composition containing a photocurable compound and a photopolymerization initiator. Claim 15 A photocurable product of the light-diffusing liquid crystal composition described in Paragraph 14. Claim 16 A light-diffusing element formed by clamping a light-diffusing liquid crystal composition described in claim 12 between a pair of opposing substrates, each of which is a transparent substrate having at least one transparent electrode. Claim 17 A light-curing element formed by clamping the photocurable material described in claim 15 between a pair of opposing substrates, each of which is a transparent substrate having at least one transparent electrode. Claim 18 In claim 16, a light-diffusing element in which both sides of a pair of substrates are transparent substrates having transparent electrodes. Claim 19 In claim 17, a light-diffusing element in which both sides of a pair of substrates are transparent substrates having transparent electrodes.

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