JP2023154634A - Liquid crystal composition and light control element - Google Patents

Abstract

To provide a liquid crystal composition that achieves protection from sunlight and shielding against blue light, and has a moderate color and excellent design.SOLUTION: A liquid crystal composition contains (A) a liquid crystal component and (B) a dye. Chromaticities (x, y) under the standard light source D65 are in the ranges of 0.3000≤x≤0.3300 and 0.3 200≤y≤0.3500. The maximum optical density in the wavelength range of 380-420 nm is at least 1.5 times higher than the optical density at the wavelength of 550 nm.SELECTED DRAWING: None

Description

The present invention relates to a guest-host liquid crystal composition for dimming and a dimming element having a dimming function.

Guest-host liquid crystal compositions, in which dichroic dyes are dissolved in liquid crystals, can control light transmittance through the absorption anisotropy of the dichroic dyes, so they have recently been used for window glass and room partitions. Applications to light control elements for building materials, automotive parts, eye-wear, etc. are being considered. Since such a light control element is expected to be used outdoors, the guest-host liquid crystal composition used for the above purpose contains an anthraquinone dichroic dye described in Patent Document 1 and Patent Document 2. It is considered preferable in terms of stability against heat and heat.
On the other hand, in recent years, it has been shown that in addition to the ultraviolet rays contained in sunlight causing skin disorders, blue light contained in sunlight also causes oxidative stress and cell damage, such as Non-Patent Document 1. Based on these findings, blue light absorbing compounds and filters have been proposed as blue light protection measures, such as in Patent Document 3.

Japanese Patent Application Publication No. 2010-144041 Japanese Patent Application Publication No. 11-5980 Japanese Patent Application Publication No. 2018-168140

Free Radical Biology and Medicine 108 (2017) 300-310

Conventionally, although the liquid crystal compositions described in Patent Document 1 and Patent Document 2 have very good stability against light, they have had a problem in that they do not have sufficient light-shielding properties against blue light. In order to improve the light shielding property against blue light, it is possible to use the liquid crystal composition described in Patent Document 1 and Patent Document 2 together with the blue light absorption filter described in Patent Document 3, but this method However, there was another problem in that the coloring of the blue light absorption filter impairs the design and functionality of the liquid crystal light control element. That is, a liquid crystal light control element is an element that can be switched between a state of high transmittance and a state of low transmittance by applying a voltage, etc., and it is generally said that a colorless and transparent state is preferable in a state of high transmittance. However, if a blue light absorption filter is used in conjunction with the LCD dimmer, it will always absorb light in the blue light wavelength band, so it will appear yellow even when the transmittance is high. be.
The present invention provides a liquid crystal composition that has both stability against sunlight and blue light blocking properties, has a moderate color tone and has an excellent design, and also provides a light control element using the liquid crystal composition. Furthermore, it is an object of the present invention to provide a light control window and a smart window equipped with the light control element.

As a result of intensive studies in view of the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by the following liquid crystal composition, and have completed the present invention.
That is, the gist of the present invention is as follows.

[1] A liquid crystal composition containing (A) a liquid crystal component and (B) a dye,
Chromaticity (x, y) in standard light source D65 is 0.3000≦x≦0.3300 and 0.3
is within the range of 200≦y≦0.3500,
A liquid crystal composition characterized in that the maximum value of optical density in the wavelength range of 380 to 420 nm is 1.5 times or more the optical density in the wavelength range of 550 nm.
[2] The liquid crystal composition according to [1], which contains at least four or more anthraquinone dyes represented by the following general formula (I) and having four or less aromatic rings as the dye (B).

[In formula (I), R ¹ represents -NHR ⁸ or -SR ⁹ , and R ² , R ³ , and R ⁴ are each independently a hydrogen atom, -NHR ⁸ , -SR ⁹ , or - Shows OR ¹⁰ . R ⁸ to R ¹⁰ are each independently a hydrogen atom, a linear or branched alkyl group, a cycloalkyl group that may have a substituent, an aryl group that may have a substituent, or Indicates a heterocyclic residue that may have a substituent.
However, if one of R ¹ to R ⁴ is -NH ₂ , the other three are not -NH ₂ .
Furthermore, the substituents of the cycloalkyl group, aryl group, and heterocyclic residue of R ⁸ to R ¹⁰ do not include a connected ring structure.
R ⁵ , R ⁶ , and R ⁷ each independently have a hydrogen atom, a halogen atom, a linear or branched alkyl group, an aryl group that may have a substituent, and a substituent. An optional aryloxy group, -SR ⁹ (R ⁹ is the same as above), or -COYR ¹¹ (Y is an oxygen atom, a sulfur atom, or -NHR ⁸ (R ⁸ is the same as above). ^R11 represents a linear or branched alkyl group, a cycloalkyl group that may have a substituent, an aralkyl group that may have a substituent, or a linear or branched alkyl group that may have a substituent. Indicates a good aryl group or a heterocyclic residue which may have a substituent.
However, when one of R ¹ to R ⁴ is -NH ₂ , at least one of R ⁵ to R ⁷ is not a hydrogen atom. Furthermore, R ⁵ to R ⁷ do not have a linked ring structure of three or more rings. ]

[3] A light control element comprising a layer made of the liquid crystal composition according to [1] or [2].
[4] A layer made of a liquid crystal composition is sandwiched between a pair of transparent electrode-attached substrates in which transparent electrodes are arranged to face each other, and a layer made of a liquid crystal composition is sandwiched between the pair of transparent electrode-attached substrates. dimmer element.
[5] The light control element according to [3], which is for use in automobiles.
[6] The light control element according to [3], which is used for building materials.
[7] A light control window comprising the light control element according to [3].
[8] A smart window comprising the light control element according to [3].

According to the present invention, it is possible to provide a liquid crystal composition that has both stability against sunlight and blue light blocking properties, has a moderate color tone, and is excellent in design. Furthermore, it is possible to provide a liquid crystal element using the liquid crystal composition of the present invention, a light control window, and a smart window equipped with the liquid crystal element of the present invention.

FIG. 1 is a spectral diagram of Example 1. FIG. 2 is a spectral diagram of Comparative Example 1. FIG. 3 is a spectral diagram of Comparative Example 2.

The present invention will be described in detail below, but the following description is an example of an embodiment of the present invention, and the present invention is not limited to the following description unless it exceeds the gist of the invention. Any modifications may be made without departing from the spirit of the invention.

[1] Liquid Crystal Composition The liquid crystal composition of the present invention contains (A) a liquid crystal component and (B) a dye, and has a chromaticity (x, y) of 0.3000≦x≦0.3300 under standard light source D65 and 0.3200≦y≦0.35
00, and the maximum value of optical density in the wavelength range of 380 to 420 nm is within the wavelength range of 5.
It is 1.5 times or more the optical density at 50 nm.
Each component of the liquid crystal composition will be described in detail below.

[1-1] (A) Liquid Crystal Component In the present invention, when a known liquid crystal substance is used as the (A) liquid crystal component, for example, see "Liquid Crystal Device Handbook" edited by the 142nd Committee of the Japan Society for the Promotion of Science, Nippon Kogyo. Newspaper company (1989
2010) pp. 152 to 192 and edited by the Liquid Crystal Handbook Editorial Committee; “Liquid Crystal Handbook” Maruzen Co., Ltd.
Use of various low-molecular compounds or mixtures such as biphenyl, phenylcyclohexane, cyclohexylcyclohexane, alkyl halide, and tolan as described on pages 260 to 330 (2000). I can do it.

In the present invention, (A) the nematic isotropic phase transition temperature (Tni) of the liquid crystal component;
is preferably 80°C or higher. If the phase transition temperature is too low, the usable temperature range will be narrowed and the dimming function will not be achieved in high temperature ranges, and if it is too high, the viscosity near room temperature will increase, making it difficult to drive at room temperature. Note that the phase transition temperature can be evaluated by, for example, measuring the change in transmitted light intensity accompanying the phase transition using a phase transition temperature measuring device.

In the present invention, (A) the dielectric anisotropy value (Δε) of the liquid crystal component may be either positive or negative, but from the viewpoint of reducing the driving voltage of the light control element, the absolute value is preferably 3 or more. It is preferably 5 or more, and more preferably 5 or more.

In the present invention, when the liquid crystal component (A) contains a chiral agent, the twist pitch length (p) of the liquid crystal component after the dye is blended is preferably 1 to 5 μm. Specifically, the torsional pitch length (
It is preferable that the d/p value, which is the relationship between p) and the cell thickness (d) of the light control element, satisfies 1 to 5.

As a chiral agent that may be included in the liquid crystal component, the product name CB-15 (CAS RN: 63
799-11-1), S-1011 (CAS RN: 165660-09-3), R-1
011 (CAS RN: 154102-21-3), S-2011 (CAS RN: 18
5207-90-3), R-2011 (CAS RN: 159077-75-5), S-
5011 (CAS RN: 693227-30-4), R-5011 (CAS RN: 9
44537-61-5). Especially S-1 with large torsional induced force (HTP)
011, R-1011, S-5011, and R-5011 are preferable because a large amount of twist can be obtained with a small amount.

From these viewpoints, as the liquid crystal component, for example, liquid crystal materials for light control elements described in JP 2018-28655A and WO 2020/158038 are particularly preferable.

[1-2] (B) Dye In the present invention, the (B) dye is not particularly limited, but preferably contains a dye (B-1) used for blocking blue light. The dye (B-1) is an anthraquinone dye represented by the following general formula (Ia), edited by the 142nd Committee of the Japan Society for the Promotion of Science; "Liquid Crystal Device Handbook" Nippon Kogyo Shimbun (1989), p. 728; Azo dyes such as those described in JP-A-61-98768 and JP-A-61-145285; JP-A-61-53;
Quinophthalone dyes as described in JP-A No. 361, perylene dye compounds as described in JP-A-57-63377, or mixtures thereof can be used.
Among these, azo dyes and quinophthalone dyes having a large molecular extinction coefficient are preferred.

In formula (Ia), R ¹² represents a linear or branched alkyl group having 1 to 5 carbon atoms, or a cycloalkyl group having a linear alkyl group having 1 to 6 carbon atoms as a substituent. .
R ² _a , R ³ _a , R ⁴ _a , R ⁵ _a , R ⁶ _a , and R ⁷ _a each independently represent a hydrogen atom, a linear alkyl group having 1 to 5 carbon atoms, or a straight chain alkyl group having 1 carbon number. A phenylthio group, a pyridylthio group, which may have ~6 linear or branched alkyl groups as a substituent, or a carbon number of 1 to 6
represents a cyclohexylcarboxy group having a linear alkyl group as a substituent.

In the above formula (Ia), R ¹² is an ethyl group, a propyl group, an n-butyl group, a t-butyl group, a 4-methylcyclohexyl group, or a 4-n -butylcyclohexyl group is preferable, R ³ _a is preferably a hydrogen atom, phenylthio group, 4-methylphenylthio group, or pyridylthio group, R ² _a , R ⁴ _a
, R ⁵ _a , R ⁶ _a and R ⁷ _a are preferably hydrogen atoms.

Preferred examples of the anthraquinone yellow dye represented by the general formula (Ia) include the following.

In the present invention, it is also preferable that the dye (B) contains a dye (B-2) other than the dye (B-1).
Examples of the dye (B-2) include anthraquinone dyes represented by the following general formula (I) and having four or less aromatic rings.

In formula (I), R ¹ represents -NHR ⁸ or -SR ⁹ , and R ² , R ³ and R ⁴ each independently represent a hydrogen atom, -NHR ⁸ , -SR ⁹ or -OR ¹⁰ shows. R ⁸ to R ¹⁰ are each independently a hydrogen atom, a linear or branched alkyl group, a cycloalkyl group that may have a substituent, an aryl group that may have a substituent, or Indicates a heterocyclic residue that may have a substituent.
However, if one of R ¹ to R ⁴ is -NH ₂ , the other three are not -NH ₂ .
Furthermore, the substituents of the cycloalkyl group, aryl group, and heterocyclic residue of R ⁸ to R ¹⁰ do not include a connected ring structure.
R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom, a halogen atom, a linear or branched alkyl group, an aryl group that may have a substituent, or a substituent that may have a substituent. A good aryloxy group, -SR ⁹ (R ⁹ is the same as above), or -COYR ¹¹ (Y is an oxygen atom, a sulfur atom, or -NHR ⁸ (R ⁸ is the same as above)) ^R11 is a hydrogen atom, a linear or branched alkyl group, a cycloalkyl group that may have a substituent, an aralkyl group that may have a substituent, or a substituent. represents an aryl group which may be substituted or a heterocyclic residue which may have a substituent.
However, when one of R ¹ to R ⁴ is -NH ₂ , at least one of R ⁵ to R ⁷ is not a hydrogen atom. Furthermore, R ⁵ to R ⁷ do not have a linked ring structure of three or more rings.

In the above formula (I), from the viewpoint of moderate color tone and dissolution in the host liquid crystal, R ¹ is
An amino group that may have a substituent or a phenylthio group that may have a substituent is preferable, and R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a hydroxy group, or a substituent. An amino group which may have one or a phenylthio group which may have a substituent is preferred. ^R5 ,
R ⁶ and R ⁷ are each independently preferably a hydrogen atom, a carbonyl group which may have a substituent, or a carboxy group which may have a substituent.

In the anthraquinone dye represented by the general formula (I) and having four or less aromatic rings,
More preferable red dyes include those represented by the following general formulas (Ib), (Ic), and (Id).

In formula (Ib), R ² _b is a hydrogen atom, a hydroxy group, a phenylthio group having a linear or branched alkyl group having 1 to 8 carbon atoms as a substituent, or a straight chain having 1 to 8 carbon atoms. A phenylthio group having a cyclohexyl group having a chain alkyl group as a substituent.
R ⁵ _b is a carboxy group having a linear or branched alkyl group having 1 to 8 carbon atoms as a substituent, a cyclohexylcarboxy group having a linear alkyl group having 1 to 8 carbon atoms as a substituent, It represents a phenylcarboxy group having a linear alkyl group having 1 to 8 carbon atoms as a substituent, or a phenoxy group having a linear alkyl group having 1 to 8 carbon atoms as a substituent.
R ⁷ _b is a hydrogen atom, a carboxy group having a linear or branched alkyl group having 1 to 8 carbon atoms as a substituent, or cyclohexyl having a linear alkyl group having 1 to 8 carbon atoms as a substituent; Carboxy group, phenylcarboxy group having a linear alkyl group having 1 to 8 carbon atoms as a substituent, or phenyl having a cyclohexyl group having a linear alkyl group having 1 to 8 carbon atoms as a substituent. Indicates a carboxy group.

In the above formula (Ib), from the viewpoint of moderate color tone and dissolution in the host liquid crystal, R ² _b
is preferably a phenylthio group having a hydroxy group or a methyl group as a substituent, and R ⁵ _b
is preferably a phenylcarboxy group having a linear alkyl group having 1 to 8 carbon atoms as a substituent. R ⁷ _b is preferably a hydrogen atom or a cyclohexylcarboxy group having a linear alkyl group having 1 to 8 carbon atoms as a substituent.

In formula (Ic), R ¹³ is a methyl group, a linear or branched alkyl group having 1 to 8 carbon atoms, or a cyclohexyl group having a linear alkyl group having 1 to 8 carbon atoms as a substituent. , R ¹⁴ is a phenyl group having a linear alkyl group having 1 to 8 carbon atoms as a substituent,
Alternatively, it represents a cyclohexylphenyl group having a linear alkyl group having 1 to 8 carbon atoms as a substituent.

In the above formula (Ic), from the viewpoint of moderate color tone and dissolution in the host liquid crystal, R ¹³
is preferably a cyclohexyl group having a linear alkyl group having 1 to 8 carbon atoms, and R ¹⁴ is preferably a phenyl group having a linear alkyl group having 1 to 8 carbon atoms as a substituent.

In formula (Id), R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, or a C 1 to 8 straight-chain or branched alkyl group. Indicates a cyclohexyl group having a linear alkyl group as a substituent.

In the above formula (Id), from the viewpoint of moderate color tone and solubility in the host liquid crystal, R ¹⁵ ,
R ¹⁶ , R ¹⁷ and R ¹⁸ are each independently preferably a hydrogen atom, a methyl group, a propyl group, a pentyl group, or a t-butyl group.

Preferred examples of the anthraquinone red dyes represented by the general formulas (Ib), (Ic), and (Id) include the following.

In the anthraquinone dye represented by the general formula (I) and having four or less aromatic rings,
More preferred dyes include those represented by the following general formula (Ie).

In formula (Ie), R ² _e is an amino group, a linear alkylthio group having 1 to 8 carbon atoms, a linear alkyl group having 1 to 8 carbon atoms, or a phenylamino group having a fluorine atom as a substituent. ,
or a phenylthio group having a linear alkyl group having 1 to 8 carbon atoms as a substituent, and R
³ _e , R ⁴ _e , and R ⁷ _e are each independently a hydrogen atom, a hydroxy group, a linear alkylthio group having 1 to 8 carbon atoms, or a linear or branched chain having 1 to 13 carbon atoms. R ⁵ _e represents a phenylthio group having a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms as a substituent, or a carboxyl group having 1 to 8 carbon atoms as a substituent; Indicates a cyclohexylcarboxy group having 8 linear alkyl groups as a substituent, or a phenylcarboxy group having a linear alkyl group having 1 to 8 carbon atoms or a fluorine atom as a substituent,
R ¹⁹ represents a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, or a phenyl group having a fluorine atom or a chlorine atom as a substituent.

In the above formula (Ie), from the viewpoint of moderate color tone and dissolution in the host liquid crystal, R ² _e
is an amino group, a linear alkylthio group having 1 to 8 carbon atoms, a phenylamino group having a fluorine atom as a substituent, a linear alkyl group having 1 to 8 carbon atoms, or a phenylamino group having 1 to 8 carbon atoms. A phenylthio group having a linear alkyl group as a substituent is preferable, and R ³ _e is preferably a hydrogen atom or a linear alkylthio group having 1 to 8 carbon atoms. R ⁴ _e , R ⁷ _e and R ¹⁹ are preferably hydrogen atoms, and R ⁵ _e is a linear alkyl group having 1 to 8 carbon atoms or a phenylcarboxy group having a fluorine atom as a substituent, or a phenylcarboxy group having 1 to 8 carbon atoms. A cyclohexylcarboxy group having 8 linear alkyl groups as a substituent is preferred.

Preferred examples of the anthraquinone blue dye represented by the general formula (Ie) include the following.

In the present invention, from the viewpoint of moderate color tone and dimming dynamic range, the wavelength is 500 nm.
Since it is preferable that the light absorption characteristic is flat from 800 nm to It is more preferable to contain at least four or more types of anthraquinone dyes.

The anthraquinone dye represented by the general formula (I) is disclosed in, for example, JP-A-56-5547.
It can be synthesized by combining conventionally known methods described in JP-A No. 9, JP-A-58-53954, and the like.

In the present invention, the dye (B) may optionally include a dye (B-1) such as an ultraviolet absorbing dye or a near-infrared absorbing dye, an anthraquinone dye represented by the above formula (I) and having 4 or less aromatic rings. It may contain other pigments.

The liquid crystal composition of the present invention has a chromaticity (x, y) of 0.3000≦x≦ under standard light source D65.
Within the range of 0.3300 and 0.3200≦y≦0.3500, and the wavelength is 380 to 420
The maximum value of optical density in the nm range is 1.5 times or more the optical density at a wavelength of 550 nm.

The chromaticity (x, y) in the standard light source D65 is 0.3000≦x≦0.3400 and 0.3000≦x≦0.3400.
3200≦y≦0.3600, 0.3000≦x≦0.3400 and 0.3000≦x≦0.3400.
3200≦y≦0.3500 is preferable, 0.3200≦x≦0.3400 and 0.33
More preferably, 00≦y≦0.3500.
Within the above range, a moderate color tone can be achieved.

The maximum value of optical density in the wavelength range of 380 to 420 nm is 1.5 times or more, preferably 1.6 times or more, the optical density at wavelength 550 nm. Further, the upper limit is not particularly limited, but is preferably 1.8 times or less.
If it is above the above lower limit value, it is excellent in blocking blue light, and if it is below the above upper limit value, a moderate color tone can be achieved.

In order to satisfy the range of chromaticity and the ratio of optical density, for example, dye (B-1),
It can be adjusted by appropriately combining dyes (B-2).

The content of the (B) dye in the liquid crystal composition of the present invention is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, based on 100 parts by mass of the (A) liquid crystal component. Moreover, 20 parts by mass or less is preferable, and 15 parts by weight or less is more preferable. The above upper limit and lower limit can be arbitrarily combined, for example, the content of (B) dye is 3 to 20 parts by mass with respect to 100 parts by mass of (A) liquid crystal component.
Parts by weight are preferred, and 5 to 15 parts by weight are particularly preferred. (B) When the content of the pigment is equal to or higher than the lower limit value, a sufficient blue light blocking effect tends to be obtained. Moreover, if it is below the said upper limit, there exists a tendency for precipitation of a dye in a liquid crystal composition to be suppressed.

The liquid crystal composition of the present invention may contain other additives in addition to (A) the liquid crystal component and (B) the dye, if necessary.

The liquid crystal composition of the present invention can be prepared by mixing (A) the liquid crystal component and (B) the dye using a known method. Specifically, for example, (A) liquid crystal component and (
B) It can be prepared by shaking and mixing a container containing the dye.

[2] Light control element The light control element of the present invention is provided with a layer made of the liquid crystal composition of the present invention, and includes a pair of substrates with transparent electrodes arranged so that the transparent electrodes face each other, and the above-mentioned 1. It is preferable to have a structure in which a layer made of the liquid crystal composition of the present invention is sandwiched between a pair of substrates with transparent electrodes.

The operating temperature range of the light control element of the present invention is preferably 0°C to 60°C, more preferably -10°C to 80°C. It is preferable that the visible light transmittance (wavelength 380 to 780 nm) of the light control element can be arbitrarily adjusted by the driving voltage, and the visible light transmittance range is preferably 1% to 40%.
More preferably 1% to 70%. The haze is preferably 10% or less, more preferably 5% or less. These device characteristics can be appropriately selected depending on the physical properties of the liquid crystal component used in the liquid crystal composition, the cell thickness of the light control element, the number of layers of the light control element, and the like.

The substrate for the transparent electrode of the light control element of the present invention is not particularly limited, but various synthetic resin plates such as glass plates, acrylic resins, polycarbonate resins, and polyethylene terephthalate resins are suitably used. The transparent electrode layer formed on the substrate is not particularly limited, but may be made of metal oxides such as indium oxide, indium tin oxide (ITO, IZO), or PE.
Conductive polymers such as DOT/PSS are preferably used. The surface of the transparent electrode layer that comes into contact with the liquid crystal can be subjected to alignment treatment, if necessary. Examples of the alignment treatment include a method of applying octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride for vertical alignment, a method of applying polyimide for parallel alignment, and a method of known methods such as a photo-alignment film. Any method can be used as appropriate.
The two electrode-attached substrates are arranged so that their orientation treated surfaces face each other, and are integrated via a spacer etc., so that the distance between the two electrode-attached substrates is, for example, 1 to 30 μm, preferably 3 to 30 μm. An element (cell) with a space of 10 μm is formed, and liquid crystal is sealed in this space.

[3] Light control window, smart window The use of the light control element of the present invention is not particularly limited, but since visible light can be efficiently controlled, examples include light control windows for automobiles and building materials, smart windows, etc. Suitably used as a window. The light control element of the present invention can be manufactured by using the known method described in JP-A-6-18856, JP-A-2007-102210, JP-A-2020-126240, etc. to create a light control window such as laminated glass or curved glass. Can be processed into windows.

EXAMPLES The present invention will be specifically explained below using examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

[Example 1]
As a host liquid crystal component, a nematic liquid crystal (Shan) with a twist pitch length adjusted to 4 μm was used.
Manufactured by BEN, Sb-412010 Nematic isotropic phase transition temperature: 96°C, dielectric anisotropy Δε: +10.77) 1g, dichroic dye (manufactured by Mitsui Chemicals Fine, S-428) 20.5mg, further as pigment component-2,
The following general formula (Id
38.5 mg of a mixture of red anthraquinone dyes represented by

In formula (Id'), n of R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are hydrogen atoms,
(4-n) represent a tert-butyl group. n represents an integer from 0 to 4.

6.0 mg of red anthraquinone dye represented by the following general formula (III),

18.6 mg of red anthraquinone dye represented by the following general formula (IV),

48.4 mg of blue anthraquinone dye represented by the following general formula (V),

A total of four types of anthraquinone dyes were mixed and dissolved to prepare liquid crystal composition-I.
This liquid crystal composition-I was sealed in a cell with a gap of 12 μm, which was made of a glass plate with transparent electrodes that had been homogeneously aligned by applying and curing a polyimide resin and then rubbing it. A light control element-I was manufactured. The transmission absorption spectrum of the produced cell was measured with a spectrophotometer (U-4100, manufactured by Hitachi High-Technologies), and the chromaticity x and y under standard light source D65 were calculated. Figure 1 shows the spectroscopic spectrum, and Table 1 shows the chromaticity measurement results.
Furthermore, a sharp-cut filter made of triacetylcellulose with a transmission limit wavelength of 380 nm was arranged on the surface of the fabricated cell, and a xenon weathering tester (manufactured by Atlas Corporation, Ci400) was placed.
0) light irradiation test (xenon exposure test) (irradiation intensity 0.55W/m ² wavelengths 340n
After performing m) for 240 hours, the transmission absorption spectrum was measured again. The measurement results are shown in Table 2.

As shown in FIG. 1, the composition described in Example 1 has a maximum optical density in the blue light wavelength range of 380 nm to 420 nm that is 1.71 times the optical density at a wavelength of 550 nm, and has a high blue light blocking effect. and the chromaticity x, y is 0.300 as shown in Table 1.
The color tone was moderate as 0≦x≦0.3300 and 0.3200≦y≦0.3500.
Furthermore, the chromaticity after the xenon exposure test also showed high fastness as shown in Table 2, and the color difference (ΔE ^* ) before and after the exposure test was 0.265, which was very good.
The color difference (ΔE ^* ) before and after the exposure test can be calculated from the following formula, and the smaller the color difference, the higher the fastness and the better the light resistance.

Here, L ^* ₂₄₀ , a ^* ₂₄₀ , b ^* ₂₄₀ is the CI after 240 hours of the xenon exposure test.
E (1976) chromaticity, L ^* _0, a ^* ₀ , b ^* ₀ are CIE (1976) before xenon exposure test.
976) indicates chromaticity.

[Comparative example 1]
A liquid crystal composition-II was prepared with the same composition ratio as the host liquid crystal component and the pigment component-2 of Example 1, except that the blue light shielding component, the pigment component-1, was not included. This liquid crystal composition
II was encapsulated in a cell in the same manner as in Example 1 to produce a light control element-II. FIG. 2 shows the spectroscopic spectrum, and Table 1 shows the chromaticity measurement results. Further, the characteristics of the light control element-II after the light irradiation test were measured by the same method as in Example 1, and the results are shown in Table 2.

As shown in FIG. 2, the composition described in Comparative Example 1 has a maximum optical density in the blue light wavelength range of 380 nm to 420 nm, which is 0.43 higher than the optical density at a wavelength of 550 nm.
Since it is as low as 1.0 times, that is, less than 1.0 times, the blue light shielding property is low, and as shown in Table 1, the chromaticities x and y also have a bluish tone. Furthermore, as shown in Table 2, the color difference (ΔE ^* ) after the xenon exposure test was 0.635, which was inferior to Example 1.

[Comparative example 2]
As a host liquid crystal component, 1 g of nematic liquid crystal (Sb-412010, manufactured by Shanben Co., Ltd.) with a twist pitch length of 4 μm and the following six types of dyes described in JP-A No. 11-5980 were mixed and dissolved to form a liquid crystal composition-III. was prepared. This liquid crystal composition-III was sealed in a cell in the same manner as in Example 1 to produce a light control element-III. FIG. 3 shows the spectroscopic spectrum, and Table 1 shows the chromaticity measurement results. Further, the characteristics of the light control element-III after the light irradiation test were measured by the same method as in Example 1, and the results are shown in Table 2.
In the following formulas (VI) and (VII), C ₈ H ₁₇ represents an octyl group, C ₇ H ₁₅ represents a heptyl group, and C ₅ H ₁₁ represents a pentyl group.

Yellow azo dye represented by the following general formula (VI) 10.0mg

Yellow azo dye represented by the following general formula (VII) 10.0mg

Red anthraquinone dye represented by the following general formula (VIII) 15.0mg

Mixture of red anthraquinone dyes represented by general formula (Id') used in Example 1 20
．． 0mg
Red anthraquinone dye represented by the general formula (IV) 18.0mg
Blue anthraquinone dye represented by the general formula (V) 40.0mg

As shown in FIG. 3, the composition described in Comparative Example 2 has a maximum optical density in the blue light wavelength range of 380 nm to 420 nm that is 0.81 lower than the optical density at a wavelength of 550 nm.
Since it is as low as 1.0 times, that is, about 1.0 times, the blue light shielding property was insufficient. In addition, as shown in Tables 1 and 2, the chromaticity after the xenon exposure test was moderate initially, but the color difference (ΔE ^* ) before and after the xenon exposure test was 0.711, compared to Example 1. The results were inferior.

As described above, the present invention enables a light control element using a guest-host liquid crystal composition that has excellent blue light blocking properties, and has the effect of improving light resistance.

Claims (8)

A liquid crystal composition containing (A) a liquid crystal component and (B) a dye,
Chromaticity (x, y) in standard light source D65 is 0.3000≦x≦0.3300 and 0.3
is within the range of 200≦y≦0.3500,
A liquid crystal composition characterized in that the maximum value of optical density in the wavelength range of 380 to 420 nm is 1.5 times or more the optical density in the wavelength range of 550 nm. 2. The liquid crystal composition according to claim 1, wherein the (B) dye contains at least four or more anthraquinone dyes represented by the following general formula (I) and having four or less aromatic rings.

[In formula (I), R ¹ represents -NHR ⁸ or -SR ⁹ , and R ² , R ³ , and R ⁴ are each independently a hydrogen atom, -NHR ⁸ , -SR ⁹ , or - Shows OR ¹⁰ . R ⁸ to R ¹⁰ are each independently a hydrogen atom, a linear or branched alkyl group, a cycloalkyl group that may have a substituent, an aryl group that may have a substituent, or Indicates a heterocyclic residue that may have a substituent.
However, if one of R ¹ to R ⁴ is -NH ₂ , the other three are not -NH ₂ .
Furthermore, the substituents of the cycloalkyl group, aryl group, and heterocyclic residue of R ⁸ to R ¹⁰ do not include a connected ring structure.
R ⁵ , R ⁶ , and R ⁷ each independently have a hydrogen atom, a halogen atom, a linear or branched alkyl group, an aryl group that may have a substituent, and a substituent. An optional aryloxy group, -SR ⁹ (R ⁹ is the same as above), or -COYR ¹¹ (Y is an oxygen atom, a sulfur atom, or -NHR ⁸ (R ⁸ is the same as above). ^R11 represents a linear or branched alkyl group, a cycloalkyl group that may have a substituent, an aralkyl group that may have a substituent, or a linear or branched alkyl group that may have a substituent. Indicates a good aryl group or a heterocyclic residue which may have a substituent.
However, when one of R ¹ to R ⁴ is -NH ₂ , at least one of R ⁵ to R ⁷ is not a hydrogen atom. Furthermore, R ⁵ to R ⁷ do not have a linked ring structure of three or more rings. ] A light control element comprising a layer made of the liquid crystal composition according to claim 1 or 2. 4. The light control device according to claim 3, further comprising: a pair of substrates with transparent electrodes arranged so that the transparent electrodes face each other; and a layer made of a liquid crystal composition sandwiched between the pair of substrates with transparent electrodes. element. The light control element according to claim 3, which is used for automobiles. The light control element according to claim 3, which is used for building materials. A light control window comprising the light control element according to claim 3. A smart window comprising the light control element according to claim 3.

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