Light-modulating liquid crystal composition containing anthraquinone compound, photocured product thereof, and light-modulating element

Abstract

The present invention pertains to: a liquid crystal composition for controlling light that contains, as a dichroic dye, an anthraquinone compound having a specific structure; and a light-controlling element that contains a cured product of said liquid crystal composition for controlling light and exhibits excellent contrast, light-blocking performance, lightfastness, and heat tolerance during current supply. More specifically, the present invention pertains to: a liquid crystal composition for controlling light that contains a compound represented by formula (A) (in the formula, R1 represents a C4-12 alkyl group or a C4-12 alkoxy group, and each R2 independently represents a C6-12 alkyl group), a liquid crystal material, a photocurable compound, and a photoinitiator; and a light-controlling element that is formed by sandwiching a photocured product of said composition between a pair of substrates.

Description

[Technical Field]

[0001] The present invention relates to a light-modulating liquid crystal composition containing an anthraquinone compound, a photocured product of the light-modulating liquid crystal composition, and a light-modulating device using the same. [Background technology]

[0002] In a light-modulating material containing liquid crystal and a polymer that holds it, when no electric field is applied, the difference between the refractive index of the polymer and that of the liquid crystal is large, causing incident light to be scattered and the liquid crystal layer to become cloudy.When an electric field is applied, the liquid crystal aligns in the direction of the electric field, reducing the difference between the refractive index of the polymer and that of the liquid crystal, resulting in a transparent state (Patent Document 1).

[0003] Light-controlling films that take advantage of these properties have become commonplace in place of blinds for the purpose of privacy protection and other purposes in windows, doors, and partitions in vehicles such as trains and automobiles, and in buildings such as business buildings and hospitals. While such light-controlling films typically block the view by controlling the transmission and scattering of light depending on whether or not a voltage is applied, they cannot block light itself, and therefore tend to increase glare due to light scattering. Therefore, attempts have been made to use dyes as materials for light-controlling panels to reduce glare and improve contrast. For example, when used in automobile windows, these panels are highly required to have light-blocking performance that provides clear visibility without fogging when transparent, while also achieving a low transmittance of around 10% when blocked. They are also highly required to have light resistance and heat resistance under electrical current, so that transmittance does not decrease even when exposed to light at high temperatures for long periods of time or when a voltage is applied for long periods of time, due to the effects of long-term outdoor use.

[0004] Dichroic dyes are commonly used as dyes in light-control films. GH (guest-host) type light-control elements that do not contain polymers are known as light-control elements that use liquid crystal compositions containing dichroic dyes, and various dichroic dyes have been proposed (Patent Documents 2 and 3).

[0005] Such dichroic dyes are required to have not only contrast when used in display devices but also light resistance and heat resistance, and efforts have been made to improve these properties. However, in light-control applications containing a polymer and a liquid crystal, no dye has been found that is satisfactory in terms of light-blocking performance, contrast, light resistance, and heat resistance when electricity is applied. For example, Patent Document 4 discloses a dichroic dye suitable for light-control applications containing a polymer and a liquid crystal, but the dye in this document is insufficient in terms of contrast, light resistance, and heat resistance when electricity is applied. Furthermore, the light-control material in Patent Document 5 has a high transmittance of about 25% when light is blocked, and its light-blocking performance is insufficient. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 63-501512 [Patent Document 2] Japanese Patent Application Publication No. 62-5941 [Patent Document 3] Japanese Patent Application Laid-Open No. 63-90568 [Patent Document 4] Japanese Patent Application Publication No. 05-224191 [Patent Document 5] Japanese Patent Application Publication No. 04-264193 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to provide a light-controlling liquid crystal composition containing an anthraquinone compound having a specific structure as a dichroic dye, and a light-controlling device containing a cured product of the light-controlling liquid crystal composition, which has excellent contrast, light-blocking performance, light resistance, and heat resistance when electricity is applied. [Means for solving the problem]

[0008] As a result of extensive investigations, the present inventors have found that the above problems can be solved by using an anthraquinone compound having a specific structure, and have thus completed the present invention. That is, the various aspects of the present invention are as follows. (1) The following formula (A) [ka] (In the formula, R1 represents an alkyl group having 4 to 12 carbon atoms or an alkoxy group having 4 to 12 carbon atoms, and R2 each independently represents an alkyl group having 6 to 12 carbon atoms.) A compound represented by Liquid crystal materials, a photocurable compound, and Photopolymerization initiator A light-modulating liquid crystal composition comprising: (2) The light-modulating liquid crystal composition according to the preceding paragraph (1), wherein R1 in formula (A) is an alkyl group having 4 to 7 carbon atoms or an alkoxy group having 4 to 7 carbon atoms, and R2 is each independently an alkyl group having 7 to 10 carbon atoms. (3) The light-modulating liquid crystal composition according to the above item (1), wherein R1 in formula (A) is an alkyl group having 4 or 5 carbon atoms, and R2 are each independently an alkyl group having 8 to 10 carbon atoms. (4) The light-modulating liquid crystal composition according to the above item (1), wherein R1 in formula (A) is an alkyl group having 6 or 7 carbon atoms, and R2 are each independently an alkyl group having 7 to 9 carbon atoms. (5) The light-modulating liquid crystal composition according to any one of the above items (1) to (4), which contains one or more dichroic dyes other than the compound represented by formula (A). (6) A photocured product of the light-modulating liquid crystal composition according to any one of the above items (1) to (5). (7) A light-adjusting element comprising a pair of opposing substrates, at least one of which is a transparent substrate having a transparent electrode, and a photocured product of the liquid crystal composition according to the above item (6) sandwiched between the pair of substrates. (8) The light-adjusting element according to the above (7), wherein both of the pair of substrates are transparent substrates having transparent electrodes. [Effects of the Invention]

[0009] By using the light-modulating liquid crystal composition of the present invention, a light-modulating element having excellent light resistance, heat resistance upon application of current, contrast, and light-shielding performance can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below. The light-modulating liquid crystal composition of the present invention (hereinafter also simply referred to as "the composition of the present invention") contains a compound represented by the following formula (A), a liquid crystal material, a photocurable compound, and a photopolymerization initiator. The compound having a specific structure and an anthraquinone skeleton represented by formula (A) contained in the composition of the present invention functions as a dichroic dye in the composition of the present invention.

[0011] [ka]

[0012] In formula (A), R1 represents an alkyl group having 4 to 12 carbon atoms or an alkoxy group having 4 to 12 carbon atoms, and R2 each independently represents an alkyl group having 6 to 12 carbon atoms.

[0013] The alkyl group having 4 to 12 carbon atoms represented by R1 in formula (A) may be linear, branched, or cyclic. Specific examples thereof include n-butyl, iso-butyl, sec-butyl, t-butyl, n-pentyl, iso-pentyl, neo-pentyl, t-pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, cyclopentyl, cyclohexyl, 2-ethylhexyl, 2-propylhexyl, 2-butylhexyl, 2-pentylhexyl, and 2-pentylheptyl. A linear or branched alkyl group having 4 to 10 carbon atoms is preferred, and a linear or branched alkyl group having 4 to 7 carbon atoms is more preferred.

[0014] The alkoxy group having 4 to 12 carbon atoms represented by R1 in formula (A) may be either linear or branched. Specific examples thereof include methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, iso-butoxy, sec-butoxy, t-butoxy, n-pentyloxy, iso-pentyloxy, neo-pentyloxy, t-pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, and dodecyloxy. A linear or branched alkoxy group having 4 to 10 carbon atoms is preferred, and a linear or branched alkoxy group having 4 to 7 carbon atoms is more preferred.

[0015] The alkyl group having 6 to 12 carbon atoms represented by R2 in formula (A) may be either linear or branched. Specific examples thereof include the same linear or branched alkyl groups having 6 to 12 carbon atoms as described in the section on the alkyl group having 4 to 12 carbon atoms represented by R1 in formula (A). A linear or branched alkyl group having 6 to 10 carbon atoms is preferred, and a linear or branched alkyl group having 7 to 10 carbon atoms is more preferred.

[0016] As for the combination of R1 and R2 in formula (A), when R1 is an alkyl group having 4 or 5 carbon atoms, each R2 is preferably an alkyl group having 8 to 12 carbon atoms, more preferably an alkyl group having 8 to 10 carbon atoms. When R1 is an alkyl group having 6 or 7 carbon atoms, each R2 is preferably an alkyl group having 6 to 10 carbon atoms, more preferably an alkyl group having 7 to 9 carbon atoms.

[0017] Specific preferred examples of the compound represented by formula (A) include the following.

[0018] [ka]

[0019] [ka]

[0020] [ka]

[0021] [ka]

[0022] [ka]

[0023] [ka]

[0024] The compound represented by the above formula (A) can be synthesized by a conventionally known method, for example, as described in JP-A-63-90568.

[0025] When the solubility of the compound represented by formula (A) in the composition of the present invention is defined as the concentration of the compound represented by formula (A) relative to the components excluding the compound represented by formula (A) in a composition obtained by stirring all of the components of the composition of the present invention at 40 to 50°C for 1 hour and then filtering, the concentration is preferably 0.5 to 10 mass%, more preferably 1.0 to 6.0 mass%. When the solubility of the compound represented by formula (A) in the composition of the present invention is in the above range, a sufficient dye addition effect can be obtained and polymerization inhibition of the photocurable compound can be prevented when the composition of the present invention is irradiated with light to form a cured product.

[0026] The liquid crystal material contained in the composition of the present invention is not particularly limited as long as it is a material (compound having liquid crystal properties) having liquid crystal properties such as nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, etc., but among these, nematic liquid crystal is preferred. Examples of compounds having liquid crystal properties include the liquid crystal compounds described in pages 154 to 192 and 715 to 722 of "Liquid Crystal Device Handbook" (edited by the 142nd Committee of the Japan Society for the Promotion of Science, Nikkan Kogyo Shimbun, Ltd., 1989).

[0027] The photocurable compound contained in the 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 below when irradiated with light. As the photocurable compound, it is preferable to use both a monofunctional monomer having one polymerizable functional group and a bifunctional monomer having two polymerizable functional groups in combination.

[0028] The monofunctional monomer used as the photocurable compound in the composition of the present invention is compatible with the liquid crystal in the composition before light irradiation, and when polymerized by light irradiation, it phase-separates from the liquid crystal to form a cured phase, thereby playing a role in mitigating the interfacial interaction with the liquid crystal phase. Therefore, if the polarity of the monofunctional monomer is excessively high, the interfacial interaction with the liquid crystal phase becomes too strong, inhibiting the movement of the liquid crystal and requiring a high driving voltage. Therefore, it is preferable that the polarity of the monofunctional monomer is low.

[0029] The bifunctional monomer used as the photocurable compound in the composition of the present invention phase-separates from the liquid crystal to form a cured phase when polymerized by light irradiation, and serves to stabilize the separation state with the liquid crystal phase. Therefore, if the polarity of the bifunctional monomer is excessively high, the interfacial interaction with the liquid crystal phase becomes too strong, inhibiting the movement of the liquid crystal and requiring a high driving voltage. Therefore, it is preferable that the polarity of the bifunctional monomer is also low.

[0030] 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. That is, it is more preferable to use a mono(meth)acrylate compound having one (meth)acrylate group in one molecule and a di(meth)acrylate compound having two (meth)acrylate groups in one molecule in combination. In this specification, the term "(meth)acrylate" means "methacrylate and / or acrylate".

[0031] The mono(meth)acrylate compound is preferably a mono(meth)acrylate having a linear, cyclic or branched alkyl group having 5 to 13 carbon atoms. Specific examples thereof include linear alkyl mono(meth)acrylates such as pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, and tridecyl (meth)acrylate; cyclic alkyl mono(meth)acrylates such as isobornyl (meth)acrylate; and branched alkyl mono(meth)acrylates such as 2-methylhexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-propylhexyl (meth)acrylate, 2-methylheptyl (meth)acrylate, 2-ethylheptyl (meth)acrylate, and 2-propylheptyl (meth)acrylate.

[0032] Suitable di(meth)acrylate compounds include, for example, 1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,11-undecanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, and 1,13-tridecanediol di(meth)acrylate, as well as trialkylene glycol di(meth)acrylates such as triethylene glycol di(meth)acrylate.

[0033] When a monofunctional monomer and a bifunctional monomer are used in combination, the mass ratio of monofunctional monomer to bifunctional monomer is preferably 1:9 to 9:1, and more preferably 5:5 to 9:1. By using the monofunctional monomer in an amount within the above ratio range, the compatibility with the liquid crystal does not become too high, and therefore separation between the polymer (polymer phase) formed by light irradiation and the liquid crystal phase occurs appropriately, preventing gelation of the monomer alone, and facilitating the formation of a separated phase between the polymer phase and the liquid crystal phase.

[0034] The compatibility of the photocurable compound contained in the composition of the present invention with the liquid crystal material can be evaluated by visually observing the phase separation that occurs as the temperature drops after the photocurable compound and the liquid crystal material are dissolved in each other using a polarizing microscope, or by measuring the phase separation temperature obtained by DSC or other measurements. The phase separation temperature between the photocurable compound and the liquid crystal material is preferably in the range of 0 to 50°C, more preferably in the range of 10 to 40°C. By setting the phase separation temperature within this range, the compatibility between the photocurable compound and the liquid crystal material in the composition is good, and phase separation does not occur after polymerization of the photocurable compound progresses due to light irradiation. This prevents the resulting liquid crystal phase from becoming too small, allowing for a lower driving voltage and making it easier to maintain the compatibility of the above components until light irradiation.

[0035] The photopolymerization initiator 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 by irradiation with light. It is preferable that the photopolymerization initiator does not remain in the cured product after irradiation with light and cause deterioration of the dichroic dye, etc. As the photopolymerization initiator, for example, alkylphenone-based photopolymerization initiators such as Darocur 1173, Irgacure 651, and Irgacure 184, and phosphine oxide-based photopolymerization initiators such as Irgacure TPO are preferably used.

[0036] The content of the compound represented by formula (A) (dichroic dye) in the composition of the present invention is preferably 0.5 to 5 parts by mass relative to 100 parts by mass of the liquid crystal material. When a dichroic dye (described later) other than the compound represented by formula (A) is used in combination with the composition of the present invention, the total content of all dichroic dyes is preferably within the above range (0.5 to 5% by mass).

[0037] The blending ratio of the total of the compound represented by Formula (A) and the liquid crystal material to the photocurable compound in the composition of the present invention is preferably 90:10 to 50:50 by mass, more preferably 80:20 to 50:50, and even more preferably 65:35 to 50:50. By setting the blending ratio of the photocurable compound within this range, it is possible to prevent separation of the liquid crystal material and the photocurable compound before curing by light irradiation and to prevent a decrease in the light-blocking properties of the cured product. When a dichroic dye (described later) other than the compound represented by Formula (A) is used in combination with the composition of the present invention, the blending ratio of the total of all dichroic dyes and liquid crystal materials to the photocurable compound is preferably within the above-mentioned range (90:10 to 50:50 in mass ratio), and the more preferred and even more preferred ranges are also the same as those described above.

[0038] The content of the photopolymerization initiator in the composition of the present invention is preferably 0.1 to 5 parts by mass relative to 100 parts by mass of the photocurable compound.

[0039] By using a dichroic dye other than the compound represented by the above formula (A) in the composition of the present invention in combination, the contrast of the light-controlling element when light is blocked can be improved. The dichroic dye that can be used in combination is not particularly limited, and may be selected from, for example, azo dyes, anthraquinone dyes, perylene dyes, quinophthalone dyes, merocyanine dyes, azomethine dyes, phthaloperylene dyes, indigo dyes, azulene dyes, dioxazine dyes, polythiophene dyes, etc. Specific examples include those described in "Dichroic dyes for Liquid Crystal Display" (AVI Vashchenko, CRC, 1994). Among these, it is preferable to use an azo dye, an anthraquinone dye, a perylene dye or a quinophthalone dye in combination, and it is more preferable to use an azo dye or an anthraquinone dye in combination.

[0040] When a dichroic dye other than the compound represented by formula (A) is used in combination, the content of the compound represented by formula (A) in the total dichroic dyes is not particularly limited as long as it does not impair the effects of the present invention, and the content is preferably 1 to 80% by mass, more preferably 10 to 70% by mass, and even more preferably 30 to 60% by mass.

[0041] In addition to the compound represented by Formula (A) (dichroic dye), liquid crystal material, photocurable compound, and photopolymerization initiator, the composition of the present invention may contain, in combination, for example, benzotriazole-based, benzophenone-based, and hindered amine-based light stabilizers, phosphite-based, and hindered phenol-based antioxidants, thermal polymerization inhibitors, thiol compounds, photosensitizers, photosensitizers, chain transfer inhibitors, polymerization inhibitors, adhesion promoters, antifoaming agents, crosslinking agents, surfactants, heat curing accelerators, thermoplastic resins, thermosetting resins, thickeners such as urethane diacrylate, and the like. In order to control the cell gap of the light-adjusting element, spherical or cylindrical spacers made of silica, glass, plastic, ceramic, etc. may be added. In this case, the cell gap can be set in the range of 2 to 100 μm.

[0042] The composition of the present invention can be obtained by mixing and stirring the essential components, namely, the compound represented by formula (A), a liquid crystal material, a photocurable compound, and a photopolymerization initiator, as well as optional components added as needed. While mixing and stirring can be performed simply by placing all components in a container and stirring manually, it is more effective to use a device such as a magnetic stirrer. To efficiently prepare a homogeneous composition, it is preferable to first prepare a homogeneous mixture of the photocurable compound, photopolymerization initiator, and liquid crystal material, and then add the compound represented by formula (1) and optional components and stir and mix. Heating may be applied as necessary during stirring and mixing. Stirring and mixing under a light source emitting the absorption wavelength of the photopolymerization initiator is preferably performed for as short a time as possible. After mixing the components, the mixture may be further filtered using a mesh, membrane filter, or the like.

[0043] By irradiating the composition of the present invention with light, a cured product of the light-modulating liquid crystal composition in which the photocurable compound component is cured (polymerized) can be obtained. Note that the "cured product" in the present invention means a state in which the functional group of the photocurable compound is polymerized or copolymerized by light irradiation, and does not necessarily mean a cured product in which the compound represented by formula (A), the liquid crystal material, etc., have contributed to the curing reaction. The light source for irradiating light is not particularly limited as long as it is capable of irradiating light 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 light. The temperature during light irradiation is preferably a temperature at which the composition can maintain a uniformly dissolved state, i.e., a temperature higher than the phase separation temperature, and more preferably a temperature in the range of 1 to 5°C higher than the phase separation temperature. When the temperature during light irradiation is higher than the phase separation temperature, separation of the photocurable compound and the liquid crystal material before light irradiation is prevented, and a more uniform cured product can be obtained. On the other hand, when the temperature during light irradiation is not significantly higher than the phase separation temperature, the domain size formed by the liquid crystal material can be prevented from becoming excessively small when the polymer of the photocurable compound obtained by photocuring separates from the liquid crystal material.

[0044] The light-adjusting element of the present invention comprises a pair of substrates, at least one of which is a transparent substrate having a transparent electrode, sandwiched between them and a photocured layer of the light-adjusting liquid crystal composition. Examples of the substrate include inorganic transparent materials such as glass and quartz, and colorless, transparent, or opaque materials such as metals, metal oxides, semiconductors, ceramics, and plastic plates and films. The electrodes are formed on the substrate by known coating methods, printing methods, or vapor deposition methods such as sputtering, forming thin films of metal oxides, metals, semiconductors, or organic conductive materials over the entire surface or in part of the substrate. From the standpoints of productivity and processability, it is particularly desirable to use an electrode substrate in which ITO (indium oxide, tin oxide) electrodes are formed on a transparent polymer film such as PET by vapor deposition methods such as sputtering or printing methods. Wiring may be provided on the substrate to connect the electrodes or the electrodes to the outside. For example, the substrate may be a segment-drive electrode substrate, a matrix-drive electrode substrate, or an active-matrix drive electrode substrate. Furthermore, the surface of the electrode provided on the substrate may be covered entirely or partially with a protective film or alignment film made of organic compounds such as polyimide, polyamide, silicon, and cyanide compounds, inorganic compounds such as SiO2, TiO2, and ZrO2, or mixtures thereof.

[0045] The use of a plastic film as a substrate allows for the production of a flexible and lightweight light-adjusting element. Therefore, the light-adjusting element can be sandwiched between a pair of flat or curved glass or hard plastic substrates via an adhesive layer such as polyvinyl butyral, vinyl acetate, double-sided tape, or adhesive. Alternatively, the light-adjusting element can be attached to the surface of a single flat or curved glass or hard plastic substrate using double-sided tape or adhesive. Alternatively, the light-adjusting element can be sandwiched between soft plastic substrates or attached to one or both sides. A protective layer such as a hard coat, an ultraviolet-blocking layer, an infrared-blocking layer, or a half mirror may be provided on the substrate surface opposite the electrode surface of the light-adjusting element. Furthermore, a color filter or a polarizer filter may be laminated on the light-adjusting element. The light-adjusting element may also be laminated as a component of an electroluminescent display element, a light-emitting diode display element, an electrochromic display element, or another liquid crystal display element.

[0046] The driving device for applying a voltage to the dimming element of the present invention is a device that can apply a DC voltage of 2 to 100 V or an AC voltage of 10 to 1000 Hz, and that leaves the electrodes open or short-circuited when no voltage is applied. This driving device may also be equipped with a voltage application circuit for segment driving, a voltage application circuit for matrix driving, a voltage application circuit for active matrix driving, etc.

[0047] The photochromic element of the present invention may be either a black photochromic element or a color photochromic element depending on the application. The average transmittance of the photochromic element of the present invention when transmitting light in a specific wavelength range is preferably 35% or more, more preferably 40% or more. The average transmittance when shielded from light is preferably 25% or less, more preferably 15% or less, and even more preferably 10% or less.

[0048] The black photochromic element has a neutral color, exhibits little color leakage in the visible light region when no voltage is applied, has excellent contrast, and is also excellent in light resistance and heat resistance under long-term outdoor exposure. Therefore, such a black photochromic element is ideal for use in automobiles or building materials. [Example]

[0049] The present invention will be described in more detail below with reference to examples. In the text, "parts" and "%" are by mass unless otherwise specified. The maximum absorption wavelength in the examples is a value measured using a spectrophotometer "UV-3150 manufactured by Shimadzu Corporation."

[0050] Synthesis Example 1 (Synthesis of a specific example of a compound represented by formula (3)) 2.8 parts of 1-(4-butylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were dissolved in 35 parts of sulfolane, and 0.90 parts of potassium carbonate and 4.4 parts of 4-octyloxyphenol were added and reacted at 130-140°C for 5 hours. After the reaction, the mixture was cooled, methanol was added, and the precipitated crystals were filtered, washed with methanol and water, and then dried. The resulting crude product was purified by column chromatography to yield 1.4 parts of the compound represented by formula (3). The maximum absorption wavelength of this compound in toluene was 627 nm.

[0051] Synthesis Example 2 (Synthesis of a specific example of a compound represented by formula (6)) 2.8 parts of 1-(4-t-butylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were dissolved in 35 parts of sulfolane, and 0.90 parts of potassium carbonate and 4.2 parts of 4-heptyloxyphenol were added and reacted at 130-140°C for 5 hours. After the reaction, the mixture was cooled, methanol was added, and the precipitated crystals were filtered, washed with methanol and water, and then dried. The resulting crude product was purified by column chromatography to yield 1.3 parts of the compound represented by formula (6). The maximum absorption wavelength of this compound in toluene was 627 nm.

[0052] Synthesis Example 3 (Synthesis of a specific example of a compound represented by formula (13)) 3.0 parts of 1-(4-heptylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were dissolved in 35 parts of sulfolane, and 0.90 parts of potassium carbonate and 4.2 parts of 4-heptyloxyphenol were added and reacted at 130-140°C for 5 hours. After the reaction, the mixture was cooled, methanol was added, and the precipitated crystals were filtered, washed with methanol and water, and then dried. The resulting crude product was purified by column chromatography to yield 1.1 parts of the compound represented by formula (13). The maximum absorption wavelength of this compound in toluene was 627 nm.

[0053] Synthesis Example 4 (Synthesis of a specific example of a compound represented by formula (14)) 3.0 parts of 1-(4-heptylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were dissolved in 35 parts of sulfolane, and 0.90 parts of potassium carbonate and 4.4 parts of 4-octyloxyphenol were added and reacted at 130-140°C for 5 hours. After the reaction, the mixture was cooled, methanol was added, and the precipitated crystals were filtered, washed with methanol and water, and then dried. The resulting crude product was purified by column chromatography to yield 0.9 parts of the compound represented by formula (14). The maximum absorption wavelength of this compound in toluene was 627 nm.

[0054] Synthesis Example 5 (Synthesis of a specific example of a compound represented by formula (26)) 2.7 parts of 1-(4-hexylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were dissolved in 35 parts of sulfolane, and 0.90 parts of potassium carbonate and 4.6 parts of 4-nonyloxyphenol were added and reacted at 130-140°C for 5 hours. After the reaction, the mixture was cooled, methanol was added, and the precipitated crystals were filtered, washed with methanol and water, and then dried. The resulting crude product was purified by column chromatography to yield 1.3 parts of the compound represented by formula (26). The maximum absorption wavelength of this compound in toluene was 627 nm.

[0055] Synthesis Example 6 (Synthesis of a specific example of a compound represented by formula (27)) 2.7 parts of 1-(4-pentylanilino)-5-amino-4,8-dihydroxy-3,7-dibromoanthraquinone were dissolved in 40 parts of sulfolane, and 0.90 parts of potassium carbonate and 5.0 parts of 4-decyloxyphenol were added and reacted at 130-140°C for 5 hours. After the reaction, the mixture was cooled, methanol was added, and the precipitated crystals were filtered, washed with methanol and water, and then dried. The resulting crude product was purified by column chromatography to yield 1.2 parts of the compound represented by formula (27). The maximum absorption wavelength of this compound in toluene was 627 nm.

[0056] Comparative Synthesis Example 1 (Synthesis of Comparative Compound) The compound shown in Example 6 of JP-A-62-5941 (compound shown by the following formula (X)) was obtained by a known synthesis method.

[0057] [ka]

[0058] Example 1 (Preparation of a light-modulating liquid crystal composition of the present invention) A light-modulating liquid crystal composition of the present invention was prepared by mixing 0.015 parts of the compound represented by the above formula (3) obtained in Synthesis Example 1, 0.380 parts of isobornyl acrylate (manufactured by Osaka Organic Chemical Industry, monoacrylate), 0.020 parts of triethylene glycol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), 0.283 parts of 1-cyano-4'-n-pentylbiphenyl, 0.139 parts of 1-cyano-4'-n-heptylbiphenyl, 0.089 parts of 1-cyano-4'-n-octyloxybiphenyl, 0.089 parts of 1-cyano-4"-n-pentylterphenyl, 0.004 parts of Irgacure TPO (manufactured by BASF), 0.004 parts of Irgacure 184 (manufactured by BASF), and 0.010 parts of a spacer agent having a diameter of 20 μm (Micropearl (registered trademark) SP220, manufactured by Sekisui Chemical Co., Ltd.) at room temperature.

[0059] Examples 2 to 6 and Comparative Example 1 (Preparation of light-modulating liquid crystal compositions of the present invention and comparative examples) The light-controlling liquid crystal composition of the present invention and the comparative light-controlling liquid crystal composition were obtained in the same manner as in Example 1, except that the compound represented by formula (3) obtained in Synthesis Example 1 was changed to the compound represented by formula (6) obtained in Synthesis Example 2, the compound represented by formula (13) obtained in Synthesis Example 3, the compound represented by formula (14) obtained in Synthesis Example 4, the compound represented by formula (26) obtained in Synthesis Example 5, the compound represented by formula (27) obtained in Synthesis Example 6, and the compound represented by formula (X) obtained in Comparative Synthesis Example 1, respectively.

[0060] Examples 7 to 12 and Comparative Example 2 (Preparation of light-controlling elements of the present invention and comparative examples) The light-control liquid crystal compositions obtained in Examples 1 to 6 and Comparative Example 1 were applied to the ITO film of a 5 cm square PET film using an applicator, and another 5 cm square PET film having the same ITO film as above was placed on top of the ITO film so that the composition layer on the ITO film faced the ITO film. Thereafter, the sample, which had been kept at 23°C on a thermoplate, was heated under a light intensity of 9 mW / cm 365 nm from an LED lamp. 2 The photo-curable compound component was photo-cured by irradiating it with light for 1 minute, thereby obtaining the light control element of the present invention and the light control element for comparison.

[0061] (Calculation of transmittance difference of dimming element) The maximum absorption wavelengths of the photochromic elements obtained in Examples 7 to 12 and Comparative Example 2 were measured, and the transmittance difference (change in transmittance) was calculated from the transmittance (%) measured at the maximum absorption wavelength with and without a 100 V AC voltage (50 Hz sine wave). The transmittance difference was calculated from the difference between the transmittance at the maximum absorption wavelength with and without a voltage applied, using photochromic elements fabricated so that the transmittance at the maximum absorption wavelength with and without a voltage applied (shielded). As shown in Table 1, the photochromic elements of Examples 7 to 12 clearly had a larger difference in transmittance with and without a voltage applied than the photochromic element of Comparative Example 2. Furthermore, the photochromic elements of Examples 7 and 9 to 12 had an even larger difference in transmittance with and without a voltage applied than the photochromic element of Example 8 (which used the compound represented by formula (6) obtained in Synthesis Example 2).

[0062] [Table 1]

[0063] (Light resistance test of dimming element) A UV cut filter of 400 nm or less was attached to the light control elements obtained in Examples 7 to 12 and Comparative Example 2, and the light control elements were then subjected to irradiation at an illuminance of 600 W / m under a condition of 63°C. 2 The absorbance at the maximum absorption wavelength was measured after 24 hours of irradiation with a metal halide lamp, and the absorbance retention rate ((δA)%) was calculated. The absorbance retention rate ((δA)%) is calculated as follows, where the absorbance value at time 0 is A(0) and the absorbance value after 24 hours is A(24). (δA)% = (A(24) / A(0)) × 100 The larger the value of ΔA, the better the light resistance. As shown in Table 2, it was confirmed that the photochromic elements of Examples 7 to 12 had a higher absorbance retention rate and superior light resistance than the photochromic element of Comparative Example 2. Furthermore, the photochromic elements of Examples 7 and 9 to 12 had an even higher absorbance retention rate and superior light resistance than the photochromic element of Example 8 (using the compound represented by formula (6) obtained in Synthesis Example 2). Among these, the photochromic elements of Examples 9 to 12 had particularly excellent light resistance, and the light resistance of Examples 11 and 12 was particularly excellent.

[0064] [Table 2]

[0065] Example 13 (Preparation of black photochromic element) A black dimming element was produced in the same manner as in Examples 7 to 12 using a dimming liquid crystal composition of the present invention prepared in the same manner as in Example 2, except that 0.015 parts of LCD212 (anthraquinone compound, manufactured by Nippon Kayaku Co., Ltd.) and 0.008 parts of LCD307 (azo compound, manufactured by Nippon Kayaku Co., Ltd.) were added. The average transmittance of the obtained black dimming element in the range of 400 to 700 nm with applied voltage was 38%, and the average transmittance with no applied voltage was 9%, showing a large difference in transmittance.

[0066] The black dimming element obtained in Example 13 showed no change in transmittance even after 500 hours in a xenon light resistance test, and also had excellent light resistance when exposed to light for long periods of time. Furthermore, even when a 100 V AC voltage (50 Hz sine wave) was applied at 110°C, there was no change in transmittance, and the element also had excellent heat resistance when energized. These results demonstrate that the black dimming element of Example 13 is a black liquid crystal dimming element that has high contrast and high light-shielding performance, as well as light resistance and heat resistance when energized.

[0067] By using the liquid crystal composition of the present invention, a light-control liquid crystal element having high contrast, high light-shielding performance, high light resistance, and high heat resistance under electrical current can be obtained, and the element can be suitably used for outdoor building materials and automotive applications that require high durability.

Claims

1. The following formula (A) 【Chemistry 1】 (wherein (i) R 1 represents an alkyl group having 4 or 5 carbon atoms, and R 2 each independently represents an alkyl group having 8 to 12 carbon atoms, or (ii) R 1 represents an alkyl group having 6 or 7 carbon atoms, and R 2 each independently represents an alkyl group having 6 to 10 carbon atoms, or (iii) R １ represents an alkyl group having 8 to 12 carbon atoms or an alkoxy group having 4 to 12 carbon atoms; R ２ each independently represents an alkyl group having 6 to 12 carbon atoms. A compound represented by Liquid crystal materials, a photocurable compound, and Photopolymerization initiator A light-modulating liquid crystal composition comprising:

2. R in formula (A) １ is an alkyl group having 4 or 5 carbon atoms, and R ２ 2. The light-modulating liquid crystal composition according to claim 1, wherein each of the groups independently represents an alkyl group having 8 to 10 carbon atoms.

3. R in formula (A) １ is an alkyl group having 6 or 7 carbon atoms, and R ２ 2. The light-modulating liquid crystal composition according to claim 1, wherein each of the groups independently represents an alkyl group having 7 to 9 carbon atoms.

4. 4. The light-modulating liquid crystal composition according to claim 1, further comprising one or more dichroic dyes other than the compound represented by formula (A).

5. A photocured product of the dimming liquid crystal composition described in any one of claims 1 to 4.

6. A light-modulating element comprising a pair of opposing substrates, at least one of which is a transparent substrate having a transparent electrode, and a photocured product of the light-modulating liquid crystal composition according to claim 5 sandwiched between the pair of substrates.

7. The light-adjusting element according to claim 6 , wherein both of the pair of substrates are transparent substrates having transparent electrodes.

Images