JP2023028799A - Liquid crystal composition used for element for controlling electromagnetic wave, and element - Google Patents

Abstract

To provide a liquid crystal composition as a material used for an element for phase control of an electromagnetic wave with a frequency of 1GHz to 10THz, which has: a wide temperature range of nematic phase; large refractive index anisotropy and small tanδ in a frequency region used for phase control; and further large specific resistance in a drive frequency region, and which exhibits an excellent balance in characteristics.SOLUTION: A liquid crystal composition containing at least one compound selected from a group of compounds represented by formula (1) is disclosed. For example: R1 is a C1 to C12 alkyl; a ring A1 is a 1,4 phenylene; Z11 and Z13 are single bonds; Z12 is -C≡C- or -C≡C-C≡C-; L13 to L16 are a hydrogen or a fluorine; Y11 and Y12 are a hydrogen or a fluorine; X1 is -CF3; and n1 is 0.SELECTED DRAWING: None

Description

The present invention relates to an element used for electromagnetic wave control with a frequency of 1 GHz to 10 THz and a liquid crystal composition used in this element. This liquid crystal composition has a nematic phase and positive dielectric anisotropy.

As a new use of liquid crystal compositions, which are often used for displays, attention has been paid to the application of liquid crystal compositions to high-frequency technology such as antennas for transmitting and receiving electromagnetic waves.

Specific examples of elements used for controlling electromagnetic waves with frequencies of 1 GHz to 10 THz include millimeter wave band or microwave band antennas, infrared laser elements, and the like. Various systems have been studied for these elements, but a system using a liquid crystal composition, which is considered to be less likely to fail because it has no mechanically movable parts, is attracting attention.

A liquid crystal composition having dielectric anisotropy has a frequency (relaxation frequency) lower than the frequency at which alignment polarization is relaxed (relaxation frequency) (from several 100 kHz to several 100 MHz). Dielectric constants in different directions.
At frequencies higher than the relaxation frequency, that is, in the range from microwaves to terahertz waves (up to 10 THz), there is a difference in the dielectric constant between the vertical direction and the horizontal direction with respect to the alignment direction of the liquid crystal composition, although the value is small. There is index anisotropy (Non-Patent Document 1). Therefore, the liquid crystal composition can change the dielectric constant in one direction by changing the alignment direction of the molecules according to the external field (electric field).

By utilizing this property, the liquid crystal composition can change the orientation of the molecules in response to an external electric field and change the dielectric constant. For example, it is possible to realize a microwave device that can electrically control the transmission characteristics of a high-frequency transmission line from the outside. Such devices include a voltage-controlled millimeter wave band variable phase shifter in which a nematic liquid crystal composition is filled in a waveguide, and a microwave/millimeter wave band in which a nematic liquid crystal composition is used as a dielectric substrate for a microstrip line. Wideband variable phase shifters and the like have been reported (Patent Documents 1 and 2).

Moreover, in recent years, research has progressed on metamaterial technology that exhibits behavior that is not found in natural substances in response to electromagnetic waves, including light. Due to its characteristics, it is applied to technical fields such as high-frequency devices, microwave devices, and antennas, and various electromagnetic wave control elements have been devised. As a capacitance control material for a transmission line using a metamaterial, the use of a liquid crystal composition that can change the orientation of molecules in response to an external electric field and change the dielectric constant is also considered.

Elements used for such electromagnetic wave control desirably have characteristics such as high gain and low insertion loss. Considering the phase control of high-frequency signals, the properties required of the liquid crystal composition are a large dielectric anisotropy that enables a large phase control in the frequency region used for phase control, and the electromagnetic wave of the liquid crystal composition. A dielectric loss tangent (tan δ) proportional to the absorbed energy of a signal is required to be small (Non-Patent Document 1).

Since the liquid crystal composition is a dielectric, it generates polarization (dielectric polarization) with respect to an external field (electric field). Permittivity is a physical quantity that indicates the response of a dielectric to an electric field, and the magnitude of the permittivity is related to dielectric polarization. The mechanism by which dielectric polarization occurs can be roughly divided into three. They are electronic polarization, ionic polarization, and orientational polarization. The orientation polarization is polarization accompanying the orientation of the dipole moment, and as shown above, it relaxes at frequencies from several hundred kHz to several hundred MHz, and the orientation polarization becomes small. As a result, at high frequencies (range of microwaves to terahertz waves (~10 THz)), dielectric polarization involves only electronic polarization and ionic polarization. In dielectrics with no insertion loss, there is a relationship of ε= ⁿ² between the dielectric constant and the refractive index. It is considered that the greater the property (Δn), the greater the dielectric anisotropy (Δε) in the high frequency region (Non-Patent Document 2). Therefore, it is preferable that the liquid crystal composition has a large refractive index anisotropy.

Also, a low drive voltage is desirable to achieve switching characteristics and high energy efficiency of the device. Therefore, the liquid crystal composition preferably has a large dielectric anisotropy even at low frequencies (frequencies lower than the relaxation frequency).

In addition, elements used for electromagnetic wave control are required to have a wide operating temperature range and a short response time. Low minimum temperature, stability against heat, low viscosity, etc. are also required.

Liquid crystal compositions used in conventional devices are disclosed in Patent Documents 3 to 4 below.

WO2017/201515 WO2017/208996 JP 2004-285085 A JP 2011-74074 A

EKISHO, Vol. 23 (No. 1), (2019), pp. 51-55 Dielectric Phenomenon Theory The Institute of Electrical Engineers of Japan Ohmsha Co., Ltd. July 25, 1973 pp.92-95

As a material for devices used for electromagnetic wave control, liquid crystal compositions have a high upper limit temperature of the nematic phase and a low lower limit temperature of the nematic phase, while exhibiting a large dielectric anisotropy (large refractive index anisotropy), small tan δ, and large dielectric anisotropy at low frequencies for driving voltage reduction, and more preferably small viscosity, large resistivity in the driving frequency range and thermal stability It is required to have sex.

However, as a liquid crystal composition for use in elements used for such electromagnetic wave control, liquid crystal compositions used for conventional display applications and the like are insufficient in terms of characteristics. This is because they have poor properties for use in high frequency control, such as high insertion loss and/or poor phase shift.

The development of liquid crystal materials for devices used for electromagnetic wave control is still in its infancy, and attempts are being made to develop novel compounds that enable the optimization of such devices in order to improve the characteristics of high frequency control. is always done. A unique liquid crystal medium is required for use as a material for devices used in electromagnetic wave control.

An object of the present invention is to provide a liquid crystal composition which satisfies the above-mentioned required characteristics and has an excellent balance of characteristics as a material for use in an element for controlling electromagnetic waves with a frequency of 1 GHz to 10 THz.

As a result of intensive studies, the inventors have found that a liquid crystal composition containing a liquid crystal compound having a specific structure can solve the above problems, and completed the present invention.

The present invention has the following configurations.

式（１）において、
Ｒ^１は、炭素数１から１２のアルキルまたは炭素数２から１２のアルケニルであり、該アルキルまたは該アルケニル中の少なくとも１つの－ＣＨ_２－は、－Ｏ－で置き換えられていてもよく；
環Ａ^１は、

または

であり；
Ｚ^１１は、単結合、－ＣＨ＝ＣＨ－、または－Ｃ≡Ｃ－であり；Ｚ^１２およびＺ^１３は、単結合、－Ｃ≡Ｃ－、または－Ｃ≡Ｃ－Ｃ≡Ｃ－であるが、Ｚ^１２およびＺ^１３のうちの少なくとも１つは単結合ではなく；
Ｌ^１１、Ｌ^１２、Ｌ^１３、Ｌ^１４、Ｌ^１５、およびＬ^１６は、水素、フッ素、塩素、メチル、エチルまたはシクロプロピルであり；
Ｙ^１１およびＹ^１２は、水素、フッ素、メチルまたは塩素であり；
Ｘ^１は、フッ素、－ＣＦ_３、または－ＯＣＦ_３であり；
ｎ１は、０、１、または２である。 Item 1: A liquid crystal composition containing at least one compound selected from the group of compounds represented by formula (1) and used for electromagnetic wave control at a frequency of any one of 1 GHz to 10 THz.

In formula (1),
R ¹ is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O—;
Ring A ¹ is

or

is;
Z ¹¹ is a single bond, —CH═CH—, or —C≡C—; Z ¹² and Z ¹³ are a single bond, —C≡C—, or —C≡CC≡C— but at least one of Z ¹² and Z ¹³ is not a single bond;
L ¹¹ , L ¹² , L ¹³ , L ¹⁴ , L ¹⁵ and L ¹⁶ are hydrogen, fluorine, chlorine, methyl, ethyl or cyclopropyl;
Y ¹¹ and Y ¹² are hydrogen, fluorine, methyl or chlorine;
X ¹ is fluorine, —CF ₃ , or —OCF ₃ ;
n1 is 0, 1, or 2;

式(１－１）から式（１－８）において、
Ｒ^１は、炭素数１から１２のアルキルまたは炭素数２から１２のアルケニルであり、該アルキルまたは該アルケニル中の少なくとも１つの－ＣＨ_２－は、－Ｏ－で置き換えられていてもよく；
Ｌ^１１、Ｌ^１４、Ｌ^１５、およびＬ^１６は、水素、フッ素、塩素、メチル、エチル、またはシクロプロピルであり；
Ｙ^１１およびＹ^１２は、水素、フッ素、または塩素である。 Item 2. The liquid crystal composition according to Item 1, containing at least one compound selected from the group of compounds represented by formulas (1-1) to (1-8).

In formulas (1-1) to (1-8),
R ¹ is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O—;
L ¹¹ , L ¹⁴ , L ¹⁵ , and L ¹⁶ are hydrogen, fluorine, chlorine, methyl, ethyl, or cyclopropyl;
Y ¹¹ and Y ¹² are hydrogen, fluorine, or chlorine.

Item 3. The liquid crystal composition according to item 1, wherein the proportion of the compound represented by formula (1) is in the range of 10% by weight to 100% by weight based on the weight of the liquid crystal composition.

式（２）～（３）において、
Ｒ^２１、Ｒ^２２、Ｒ^３１およびＲ^３２は、炭素数１から１２のアルキルまたは炭素数２から１２のアルケニルであり、該アルキルまたは該アルケニル中の少なくとも１つの－ＣＨ_２－は、－Ｏ－で置き換えられていてもよく；
Ｚ^２１、Ｚ^２３、およびＺ^３１は、単結合、－ＣＨ＝ＣＨ－、または－Ｃ≡Ｃ－であり；Ｚ^３２およびＺ^３３は、単結合、－Ｃ≡Ｃ－、または－Ｃ≡Ｃ－Ｃ≡Ｃ－であり、Ｚ^２２は－Ｃ≡Ｃ－または-Ｃ≡Ｃ－Ｃ≡Ｃ－であり；
Ｌ^２１、Ｌ^２２、Ｌ^２３、Ｌ^３１、Ｌ^３２、Ｌ^３３、Ｌ^３４、Ｌ^３５、およびＬ^３６は、水素、フッ素、塩素、メチル、またはエチルである。 Item 4. The liquid crystal composition according to any one of items 1 to 3, containing at least one compound selected from the group of compounds represented by formula (2) and the group of compounds represented by formula (3).

In formulas (2) to (3),
R ²¹ , R ²² , R ³¹ and R ³² are alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl is —O— may be replaced with;
Z ²¹ , Z ²³ , and Z ³¹ are a single bond, —CH═CH—, or —C≡C—; Z ³² and Z ³³ are a single bond, —C≡C—, or —C≡C -C≡C- and Z ²² is -C≡C- or -C≡CC≡C-;
^L21 , ^{L22 , L23} , ^L31 , L32, ^L33 , ^L34 , ^L35 , and ^L36 are hydrogen, fluorine, chlorine, methyl, or ethyl.

式（２－１）から式（２－５）において、
Ｒ^２１およびＲ^２２は、炭素数１から１２のアルキルまたは炭素数２から１２のアルケニルであり、該アルキルまたは該アルケニル中の少なくとも１つの－ＣＨ_２－は、－Ｏ－で置き換えられていてもよく；
Ｌ^２１、Ｌ^２２、およびＬ^２３は、水素、フッ素、塩素、メチル、またはエチルである。 Item 5. The liquid crystal composition according to Item 4, containing at least one compound selected from the group of compounds represented by formulas (2-1) to (2-5).

In formulas (2-1) to (2-5),
R ²¹ and R ²² are alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O— often;
L ²¹ , L ²² and L ²³ are hydrogen, fluorine, chlorine, methyl or ethyl.

Item 6. The liquid crystal composition according to Item 4, wherein the proportion of the compound represented by formula (2) is in the range of 20% by weight to 50% by weight based on the weight of the liquid crystal composition.

式（３－１）から式(３－４）において、
Ｒ^３１およびＲ^３２は、炭素数１から１２のアルキルまたは炭素数２から１２のアルケニルであり、該アルキルまたは該アルケニル中の少なくとも１つの－ＣＨ_２－は、－Ｏ－で置き換えられていてもよく；
Ｌ^３１、Ｌ^３２、Ｌ^３３、Ｌ^３４、Ｌ^３５、およびＬ^３６は、水素、フッ素、塩素、メチル、またはエチルである。 Item 7. The liquid crystal composition according to any one of Items 4 to 6, containing at least one compound selected from the group of compounds represented by formulas (3-1) to (3-4).

In formulas (3-1) to (3-4),
R ³¹ and R ³² are alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O— often;
L ³¹ , L ³² , L ³³ , L ³⁴ , L ³⁵ and L ³⁶ are hydrogen, fluorine, chlorine, methyl or ethyl.

Item 8. The liquid crystal composition according to Item 4, wherein the proportion of the compound represented by formula (3) is in the range of 10% by weight to 40% by weight based on the weight of the liquid crystal composition.

式（４）において、
Ｒ^４は、炭素数１から１２のアルキルまたは炭素数２から１２のアルケニルであり、該アルキルまたは該アルケニル中の少なくとも１つの－ＣＨ_２－は、－Ｏ－で置き換えられていてもよく；
Ｚ^４１は、単結合、－ＣＨ＝ＣＨ－、または－Ｃ≡Ｃ－であり；Ｚ^４２およびＺ^４３は、単結合、－Ｃ≡Ｃ－、または－Ｃ≡Ｃ－Ｃ≡Ｃ－であり；
Ｌ^４１、Ｌ^4２、Ｌ^４３、Ｌ^４４、およびＬ^４５は、水素、フッ素、塩素、メチル、エチルまたはシクロプロピルであり；
Ｙ^４１およびＹ^４２は、水素、フッ素、または塩素であり；
Ｘ^４は、－Ｃ≡Ｎ、－Ｃ≡Ｃ－Ｃ≡Ｎ、または－Ｎ＝Ｃ＝Ｓであり；
ｎ４は、０、１、または２である。 Item 9. The liquid crystal composition according to any one of Items 1 to 8, containing at least one compound selected from the group of compounds represented by formula (4).

In formula (4),
R ⁴ is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O—;
Z ⁴¹ is a single bond, —CH═CH—, or —C≡C—; Z ⁴² and Z ⁴³ are a single bond, —C≡C—, or —C≡CC≡C— ;
L ⁴¹ , L ⁴² , L ⁴³ , L ⁴⁴ and L ⁴⁵ are hydrogen, fluorine, chlorine, methyl, ethyl or cyclopropyl;
Y ⁴¹ and Y ⁴² are hydrogen, fluorine, or chlorine;
X ⁴ is -C≡N, -C≡C-C≡N, or -N=C=S;
n4 is 0, 1, or 2;

式（４－１）から式(４－１２）において、
Ｒ^４は、炭素数１から１２のアルキルまたは炭素数２から１２のアルケニルであり、該アルキルまたは該アルケニル中の少なくとも１つの－ＣＨ_２－は、－Ｏ－で置き換えられていてもよく；
Ｌ^４１、Ｌ^４３、Ｌ^４４、およびＬ^４６は、水素、フッ素、塩素、メチル、エチル、またはシクロプロピルであり；
Ｙ^４１およびＹ^４２は、水素、フッ素、または塩素である。 Item 10. The liquid crystal composition according to Item 9, containing at least one compound selected from the group of compounds represented by formulas (4-1) to (4-12).

In formulas (4-1) to (4-12),
R ⁴ is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O—;
L ⁴¹ , L ⁴³ , L ⁴⁴ , and L ⁴⁶ are hydrogen, fluorine, chlorine, methyl, ethyl, or cyclopropyl;
Y ⁴¹ and Y ⁴² are hydrogen, fluorine, or chlorine.

Item 11. The liquid crystal composition according to Item 9, wherein the proportion of the compound represented by formula (4) is in the range of 5% by weight to 40% by weight based on the weight of the liquid crystal composition.

Item 12. The liquid crystal composition according to any one of Items 1 to 11, wherein the refractive index anisotropy at 25° C. at a wavelength of 589 nm is in the range of 0.20 to 0.80.

Item 13. The liquid crystal composition according to any one of Items 1 to 12, wherein dielectric anisotropy at 25° C. at any frequency from 1 GHz to 10 THz is in the range of 0.4 to 3.0.

Item 14. The liquid crystal composition according to any one of Items 1 to 13, comprising an optically active compound.

Item 15. The liquid crystal composition according to any one of Items 1 to 14, comprising a polymerizable compound.

Item 16. A device used for electromagnetic wave control at a frequency of 1 GHz to 10 THz, containing the liquid crystal composition according to any one of Items 1 to 15.

According to the present invention, while having a high upper limit temperature of the nematic phase and a low lower limit temperature of the nematic phase, a large dielectric anisotropy in the frequency range for electromagnetic wave control, a small tan δ, and a reduction in the driving voltage It is possible to provide a liquid crystal composition that has a large dielectric anisotropy at low frequencies, a small viscosity, a large specific resistance in the drive frequency range, and stability against heat, and the liquid crystal composition of the present invention is used. The device can exhibit excellent characteristics of electromagnetic wave control over a wide temperature range.

Terms used in this specification are as follows. The terms "liquid crystal composition" and "electromagnetic wave control element" may be abbreviated as "composition" and "element", respectively. "Electromagnetic wave control element" is a general term for an electromagnetic wave control panel and an electromagnetic wave control module. "Liquid crystal compound" means a compound having a liquid crystal phase such as a nematic phase or a smectic phase, or a compound having no liquid crystal phase, but for the purpose of adjusting the properties of the nematic phase such as temperature range, viscosity, dielectric It is a general term for compounds mixed in the composition. This compound has a six-membered ring such as 1,4-cyclohexylene or 1,4-phenylene, and its molecules (liquid crystal molecules) are rod-like. A "polymerizable compound" is a compound added for the purpose of forming a polymer in the composition. A liquid crystalline compound having alkenyl is not classified as a polymerizable compound in that sense.

A liquid crystal composition is prepared by mixing a plurality of liquid crystalline compounds. The ratio (content) of the liquid crystalline compound is represented by weight percentage (% by weight) based on the weight of the liquid crystal composition. This liquid crystal composition contains an optically active compound, an antioxidant, an ultraviolet absorber, a stabilizer against ultraviolet rays and heat, a quenching agent, a dye, an antifoaming agent, a polymerizable compound, a polymerization initiator, a polymerization inhibitor, a magnetic compound, and the like. Additives are added as needed. The proportion (addition amount) of the additive is represented by weight percentage (% by weight) based on the weight of the liquid crystal composition, like the proportion of the liquid crystalline compound. Parts per million (ppm) by weight are sometimes used. Proportions of polymerization initiators and polymerization inhibitors are exceptionally expressed based on the weight of the polymerizable compound.

"The upper limit temperature of the nematic phase" may be abbreviated as "the upper limit temperature". "Lower limit temperature of nematic phase" may be abbreviated as "lower limit temperature". The expression "increase the dielectric anisotropy" means that the value increases positively in the case of a composition with a positive dielectric anisotropy, and in a composition with a negative dielectric anisotropy. When it is a thing, it means that its value increases negatively.

At least one compound selected from the group of compounds represented by formula (1) may be abbreviated as "compound (1)". "Compound (1)" means one compound or two or more compounds represented by Formula (1). The same applies to compounds represented by other formulas. "At least one" with respect to "may be replaced" means that not only the position but also the number thereof may be selected without limitation.

上記の化合物（１ｚ）を例にして説明する。式（１ｚ）において、六角形で囲んだαおよびβの記号はそれぞれ環αおよび環βに対応し、六員環、縮合環のような環を表す。添え字‘ｘ’が２のとき、２つの環αが存在する。２つの環αが表す２つの基は、同一であってもよく、または異なってもよい。このルールは、添え字‘ｘ’が２より大きいとき、任意の２つの環αに適用される。このルールは、結合基Ｚのような、他の記号にも適用される。環βの一辺を横切る斜線は、環β上の任意の水素が置換基（－Ｓｐ－Ｐ）で置き換えられてもよいことを表す。添え字‘ｙ’は置き換えられた置換基の数を示す。添え字‘ｙ’が０のとき、そのような置き換えはない。添え字‘ｙ’が２以上のとき、環β上には複数の置換基（－Ｓｐ－Ｐ）が存在する。この場合にも、「同一であってもよく、または異なってもよい」のルールが適用される。なお、このルールは、Ｒａの記号を複数の化合物に用いた場合にも適用される。

The above compound (1z) will be described as an example. In formula (1z), the symbols α and β surrounded by hexagons correspond to ring α and ring β, respectively, and represent rings such as six-membered rings and condensed rings. When the index 'x' is 2, there are two rings α. Two groups represented by two rings α may be the same or different. This rule applies to any two rings α when the index 'x' is greater than two. This rule also applies to other symbols, such as the bonding group Z. A slash across one side of ring β indicates that any hydrogen on ring β may be replaced with a substituent (-Sp-P). The subscript 'y' indicates the number of substituents replaced. When the index 'y' is 0, there is no such replacement. When the subscript 'y' is 2 or more, there are multiple substituents (-Sp-P) on the ring β. In this case as well, the "can be the same or can be different" rule applies. This rule also applies when the symbol Ra is used for a plurality of compounds.

In formula (1z), for example, expressions such as "Ra and Rb are alkyl, alkoxy, or alkenyl" mean that Ra and Rb are independently selected from the group of alkyl, alkoxy, and alkenyl. means Here, the group represented by Ra and the group represented by Rb may be the same or different. This rule also applies when the Ra symbol is used for multiple compounds. This rule also applies when multiple Ra's are used in one compound.

At least one compound selected from compounds represented by formula (1z) may be abbreviated as "compound (1z)". "Compound (1z)" means one compound, a mixture of two compounds, or a mixture of three or more compounds represented by formula (1z). The same applies to compounds represented by other formulas. The expression "at least one compound selected from compounds represented by formula (1z) and formula (2z)" means at least one compound selected from the group of compound (1z) and compound (2z) .

The expression "at least one 'A'" means that the number of 'A' is arbitrary. The expression "at least one 'A' may be replaced with 'B'" means that when the number of 'A' is 1, the position of 'A' is arbitrary, and the number of 'A' is 2 When there are more than one, their positions can be chosen without restriction. The expression "at least one -CH ₂ - may be replaced with -O-" is sometimes used. In this case, -CH ₂ -CH ₂ -CH ₂ - may be converted to -O-CH ₂ -O- by replacing non-adjacent -CH ₂ - with -O-. However, adjacent -CH ₂ - is not replaced by -O-. This is because —O—O—CH ₂ — (peroxide) is produced by this replacement.

カルボニルオキシのような結合基も同様に、－ＣＯＯ－であってもよいし、－ＯＣＯ－であってもよい。 Alkyl in the liquid crystalline compound is straight-chain alkyl or branched-chain alkyl, and does not include cyclic alkyl unless otherwise specified. Straight-chain alkyl is preferable to branched-chain alkyl from the viewpoint of the stability of the liquid crystal phase (the fact that the liquid crystal phase is exhibited over a wide temperature range). The same applies to terminal groups such as alkoxy and alkenyl. The configuration of 1,4-cyclohexylene is preferably trans rather than cis in order to increase the maximum temperature. 2-Fluoro-1,4-phenylene means the following two divalent radicals. In the chemical formula, fluorine may be directed leftward (L) or rightward (R). This rule includes 2,5-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl, 1,3-dioxane- It also applies to asymmetric ring divalent radicals such as 2,5-diyl, tetrahydropyran-2,5-diyl. A preferred tetrahydropyran-2,5-diyl is rightward (R) in order to increase the maximum temperature.

A linking group such as carbonyloxy may similarly be -COO- or -OCO-.

In the chemical formulas of component compounds, the symbol for the terminal group ^R1 is used for multiple compounds. In these compounds, any two groups represented by R ¹ may be the same or different. For example, there is a case where R ¹ of compound (1-1) is methyl and R ¹ of compound (1-2) is ethyl. In some cases, R ¹ of compound (1-1) is ethyl and R ¹ of compound (1-2) is propyl. This rule also applies to symbols such as R ²¹ , R ²² , R ³¹ , R ³² , R ⁴ .

The present invention also includes the following items (a) to (f). (a) additives such as optically active compounds, antioxidants, UV absorbers, UV and heat stabilizers, quenchers, dyes, antifoaming agents, polymerizable compounds, polymerization initiators, polymerization inhibitors, polar compounds; The above composition further comprising at least one selected from (b) a device containing the above composition; (c) A device containing the above composition and used for phase control of an electromagnetic wave signal of any frequency from 1 GHz to 10 THz. (d) the above composition further containing a polymerizable compound, and a device containing this composition; (e) Use of the above composition as a composition having a nematic phase. (f) Use as an optically active composition by adding an optically active compound to the above composition.

The liquid crystal composition of the present invention has a large dielectric anisotropy and a small tan δ in the frequency range of electromagnetic wave signals from 1 GHz to 10 THz. Therefore, it is preferable to use it for elements related to electromagnetic waves of 1 GHz to 10 THz, more preferably 1 GHz to 50 GHz.

The composition of the present invention will be described in the following order. First, the composition of the component compounds in the composition will be described. Second, the main properties of the component compound and the main effect of this compound on the composition are described. Third, the combination of ingredients in the composition, the preferred proportions of the ingredients and the rationale for them are described. Fourth, preferred forms of component compounds are described. Fifth, preferred component compounds are shown. Sixth, additives that may be added to the composition are described. Seventh, the method for synthesizing the component compounds will be explained. Finally, the use of the composition will be explained.

First, the composition of the component compounds in the composition will be described. The compositions of the present invention are classified into composition A and composition B. Composition A may further contain other liquid crystalline compounds, additives, etc., in addition to the liquid crystalline compound selected from compound (1). "Another liquid crystalline compound" is a liquid crystalline compound different from compound (1). Such compounds are incorporated into the composition for the purpose of further adjusting its properties. Additives include optically active compounds, antioxidants, ultraviolet absorbers, stabilizers against ultraviolet rays and heat, quenchers, dyes, antifoaming agents, polymerizable compounds, polymerization initiators, polymerization inhibitors, polar compounds, and the like.

Composition B consists essentially of a liquid crystalline compound selected from compound (1). "Substantially" means that the composition may contain additives, but does not contain other liquid crystalline compounds. Composition B has fewer components than Composition A. Composition B is preferable to composition A from the viewpoint of cost reduction. The composition A is preferable to the composition B from the viewpoint that the properties can be further adjusted by mixing other liquid crystalline compounds.

Second, the main properties of the component compound and the main effect of this compound on the properties of the composition are described. The main properties of the component compounds are summarized in Table 1 based on the effects of the present invention. In the symbols in Table 1, L means large or high, M medium, and S small or low. The symbols L, M, S are classifications based on qualitative comparisons between component compounds, with 0 (zero) meaning the value is approximately zero or close to zero.

Table 1 Properties of compounds

When the component compounds are mixed into the composition, the main effects of the component compounds on the properties of the composition are as follows.
Compound (1) mainly has the effect of increasing the refractive index anisotropy and increasing the dielectric anisotropy of the liquid crystal composition. The upper limit temperature and viscosity can be adjusted by the number of rings contained in compound (1) and the number of n1 in formula (1). That is, when n1 is 0, the maximum temperature decreases but the viscosity decreases, and when n1 is 2, the viscosity increases but the maximum temperature increases.
The compound (2) mainly increases the refractive index anisotropy of the liquid crystal composition and has the effect of widening the temperature range of the nematic phase. Compound (2) has a high ability to lower the minimum temperature and viscosity of the liquid crystal composition.
Compound (3) has the effect of mainly increasing the refractive index anisotropy of the liquid crystal composition and widening the temperature range of the nematic phase. Compound (3) has a high ability to raise the maximum temperature of the liquid crystal composition.
The compound (4) mainly has the effect of increasing the refractive index anisotropy and increasing the dielectric anisotropy of the liquid crystal composition. The upper limit temperature and viscosity can be adjusted by the number of rings contained in compound (4) and the number of n4 in formula (4). That is, when n4 is 0, the maximum temperature decreases but the viscosity decreases, and when n4 is 2, the viscosity increases but the maximum temperature increases.

Thirdly, the combination of ingredients in the composition, the preferred proportions of the ingredient compounds and the rationale thereof will be explained. The combination of components in the composition is compound (1) + compound (2), compound (1) + compound (3), compound (1) + compound (2) + compound (3) or compound (1) + compound ( 2) + compound (3) + compound (4).

Based on the weight of the liquid crystal composition, a preferable proportion of compound (1) is about 10% by weight or more for increasing dielectric anisotropy and refractive index anisotropy, and the temperature range of the nematic phase is and to reduce the viscosity, it is about 100% by weight or less. A more preferred proportion ranges from about 20% to about 100% by weight. A particularly preferred proportion ranges from about 30% to about 100% by weight.

Based on the weight of the liquid crystal composition, a preferable proportion of compound (2) is about 20% by weight or more in order to widen the temperature range of the nematic phase while increasing the refractive index anisotropy. up to about 50% by weight. A more preferred proportion ranges from about 20% to about 45% by weight. A particularly preferred proportion ranges from about 20% to about 40% by weight.

Based on the weight of the liquid crystal composition, a preferable proportion of compound (3) is about 10% by weight or more in order to increase the temperature range of the nematic phase while increasing the refractive index anisotropy. up to about 40% by weight. A more preferred proportion ranges from about 10% to about 35% by weight. A particularly preferred proportion ranges from about 10% to about 30% by weight.

Based on the weight of the liquid crystal composition, a preferable proportion of compound (4) is about 5% by weight or more for increasing dielectric anisotropy and refractive index anisotropy, and the temperature range of the nematic phase is is about 40% by weight or less in order to spread the viscosity and to lower the viscosity. A more preferred proportion ranges from about 5% to about 35% by weight. A particularly preferred proportion ranges from about 10% to about 35% by weight.

Fourth, preferred forms of component compounds are described. R ¹ , R ²¹ , R ²² , R ³¹ , R ³² and R ⁴ are alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ in said alkyl or said alkenyl — may be replaced with —O—, and preferred R ¹ , R ²¹ , R ²² , R ³¹ , R ³² or R ⁴ has 1 to 6 carbon atoms in order to increase stability against ultraviolet light or heat. is an alkyl of

Preferred alkyls are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl or octyl. More preferred alkyls are ethyl, propyl, butyl, pentyl, or heptyl to reduce viscosity.

Preferred alkoxy are methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy. More preferred alkoxy is methoxy or ethoxy for reducing viscosity.

Preferred alkenyls are vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, or 5-hexenyl. More preferred alkenyls are vinyl, 1-propenyl, 3-butenyl, or 3-pentenyl to reduce viscosity. The preferred configuration of -CH=CH- in these alkenyls depends on the position of the double bond. Trans is preferred in alkenyls such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl, and 3-hexenyl in order to lower the viscosity. Cis is preferred in alkenyls such as 2-butenyl, 2-pentenyl, 2-hexenyl. Among these alkenyls, straight-chain alkenyls are preferred to branched alkenyls.

_Preferred alkoxyalkyls are _-CH2OCH3 , _{-CH2OC2H5 , -CH2OC3H7} , _{-(CH2)2-OCH3 , - ( CH2 ) 2 - OC2H5 ,} - (CH ₂ ) ₂ -OC ₃ H ₇ , -(CH ₂ ) ₃ -OCH ₃ , -(CH ₂ ) ₄ -OCH ₃ , or -(CH ₂ ) ₅ -OCH ₃ .

n1 is 0, 1, or 2; Preferred n1 is 0 for lowering the viscosity, and 1 or 2 for raising the maximum temperature, dielectric anisotropy, and refractive index anisotropy.
n4 is 0, 1, or 2; Preferred n4 is 0 for lowering the viscosity, and 1 or 2 for raising the maximum temperature, dielectric anisotropy, and refractive index anisotropy.

Z ¹¹ , Z ²¹ , Z ²³ , Z ³¹ and Z ⁴¹ are a single bond, -CH=CH- or -C≡C-. Preferred Z ¹¹ , Z ²¹ , Z ²³ , Z ³¹ and Z ⁴¹ are single bonds to reduce viscosity and -C≡C- to increase refractive index anisotropy. Z ¹² , Z ¹³ , Z ³² , Z ³³ , Z ⁴² and Z ⁴³ are single bonds, -C≡C- or -C≡CC≡C-, but in order to increase the refractive index anisotropy, At least one of ^Z12 and ^Z13 is not a single bond. Preferred Z ¹² , Z ¹³ , Z ³² , Z ³³ , Z ⁴² and Z ⁴³ are single bonds to reduce viscosity, and -C≡C- or -C≡C- to increase refractive index anisotropy. C≡C-. Z ²² is -C≡C- or -C≡CC≡C-. Preferred Z ²² is -C≡CC≡C- for increasing refractive index anisotropy.

または

である。好ましい環Ａ^１は、屈折率異方性を上げるために、

である。 Ring A ¹ is

or

is. A preferable ring ^A1 is, in order to increase the refractive index anisotropy,

is.

L ¹¹ , L ¹² , L ¹³ , L ¹⁴ , L ¹⁵ , L ¹⁶ , L ⁴¹ , L ⁴² , L ⁴³ , L ⁴⁴ or L ⁴⁵ is hydrogen, fluorine, chlorine, methyl, ethyl or cyclopropyl. Preferred L ¹¹ , L ¹² , L ¹³ , L ¹⁴ , L ¹⁵ , L ¹⁶ , L ⁴¹ , L ⁴² , L ⁴³ , L ⁴⁴ or L ⁴⁵ are fluorine, ethyl or cyclopropyl to improve compatibility. be. ^L21 , ^L22 , ^L23 , ^L31 , ^L32 , ^L33 , ^L34 , ^L35 and ^L36 are hydrogen, fluorine, chlorine, methyl or ethyl. Preferred L ²¹ , L ²² , L ²³ , L ³¹ , L ³² , L ³³ , L ³⁴ , L ³⁵ or L ³⁶ are fluorine or ethyl to improve compatibility. L ¹³ and L ¹⁴ , L ²¹ and L ²² , L ³² and L ³⁴ , or L ⁴² and L ⁴³ have a negative dielectric anisotropy, which reduces the dielectric anisotropy of the liquid crystal composition as a whole. Therefore, it is preferable that it is not fluorine or the like at the same time.

Y ¹¹ , Y ¹² , Y ⁴¹ and Y ⁴² are hydrogen, fluorine or chlorine. Preferred Y ¹¹ , Y ¹² , Y ⁴¹ and Y ⁴² are fluorine in order to increase dielectric anisotropy. L ¹⁴ and Y ¹¹ , or L ⁴⁵ and Y ⁴¹ have a negative dielectric anisotropy and reduce the dielectric anisotropy of the liquid crystal composition as a whole.

Fifth, preferred component compounds are shown. Preferred compounds (1) are compounds (1-1) to (1-8).

In these formulas, R ¹ is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl is replaced with —O—. L ¹¹ , L ¹⁴ , L ¹⁵ and L ¹⁶ are hydrogen, fluorine, chlorine, methyl, ethyl or cyclopropyl; Y ¹¹ and Y ¹² are hydrogen, fluorine or chlorine. At least one compound (1) is preferably compound (1-1), compound (1-2), compound (1-5) or compound (1-6).

Preferred compounds (2) are compounds (2-1) to (2-5).

In these formulas, R ²¹ and R ²² are alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl is —O— optionally substituted; L ²¹ , L ²² and L ²³ are hydrogen, fluorine, chlorine, methyl or ethyl. At least one compound (2) is preferably compound (2-1) or compound (2-4). At least two compounds (2) are preferably a combination of one of compound (2-1) or compound (2-2) and compound (2-4).

Preferred compounds (3) are compounds (3-1) to (3-4).

In these formulas, R ³¹ and R ³² are alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl is —O— optionally substituted; L ³¹ , L ³² , L ³³ , L ³⁴ , L ³⁵ and L ³⁶ are hydrogen, fluorine, chlorine, methyl or ethyl. At least one compound (3) is preferably compound (3-1), compound (3-2), or compound (3-3).

Preferred compounds (4) are compounds (4-1) to (4-12).

In these formulas, R ⁴ is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl is replaced with —O—. L ⁴¹ , L ⁴³ , L ⁴⁴ and L ⁴⁵ are hydrogen, fluorine, chlorine, methyl or ethyl; Y ⁴¹ and Y ⁴² are hydrogen, fluorine or chlorine. at least one compound (4) is compound (4-3), compound (4-4), compound (4-9), compound (4-10), compound (4-11), or compound (4-12) ) is preferred.

Sixth, additives that may be added to the composition are described. Such additives include optically active compounds, antioxidants, ultraviolet absorbers, stabilizers against ultraviolet rays and heat, quenchers, dyes, antifoaming agents, polymerizable compounds, polymerization initiators, polymerization inhibitors, polar compounds, and the like. is. Hereinafter, the mixing ratio of these additives is the ratio (weight) based on the weight of the liquid crystal composition unless otherwise specified.

An optically active compound is added to the composition for the purpose of inducing a helical structure of liquid crystals to give a twist angle. Examples of such compounds are compounds (5-1) to (5-6). A preferred proportion of the optically active compound is about 5% by weight or less. A more preferred proportion ranges from about 0.01% to about 2% by weight.

In order to prevent a decrease in resistivity due to heating in the atmosphere, or to maintain a large voltage holding ratio not only at room temperature but also at temperatures close to the upper limit after long-term use of the device, an antioxidant is added. added to things. Preferred examples of antioxidants include compounds (6) where t is an integer from 1 to 9.

In compound (6), preferred t is 1, 3, 5, 7, or 9. More preferable t is 7. The compound (6) in which t is 7 has low volatility and is effective in maintaining a large voltage holding ratio not only at room temperature but also at temperatures close to the upper limit temperature after long-term use of the device. A preferable proportion of the antioxidant is about 50 ppm or more to obtain its effect, and about 600 ppm or less so as not to lower the upper limit temperature or raise the lower limit temperature. A more preferred percentage is in the range of about 100 ppm to about 300 ppm.

Preferred examples of UV absorbers are benzophenone derivatives, benzoate derivatives, triazole derivatives and the like. Light stabilizers such as sterically hindered amines are also preferred. A preferable ratio of these absorbents and stabilizers is about 50 ppm or more to obtain the effect, and about 10000 ppm or less so as not to lower the upper limit temperature or raise the lower limit temperature. More preferred proportions range from about 100 ppm to about 10,000 ppm.

式（７）において、Ｒ^ｍおよびＲ^ｎは、炭素数１から１２のアルキル、炭素数１から１２のアルコキシ、炭素数２から１２のアルケニルまたは炭素数２から１２のアルケニルオキシであり；Ｘ^ａは、－ＮＯ_２、－Ｃ≡Ｎ、－Ｎ＝Ｃ＝Ｓ、フッ素、または－ＯＣＦ_３であり；Ｙ^ａおよびＹ^ｂは、水素またはフッ素である。これらの安定剤における好ましい割合は、その効果を得るために１～２０重量％の範囲であり、好ましくは５～１０重量％の範囲である。 A preferred example of a stabilizer against ultraviolet light and heat is an amino-tolane compound represented by compound (7) (US Pat. No. 6,495,066).

In formula (7), R ^m and R ⁿ are alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms or alkenyloxy having 2 to 12 carbon atoms ^; is —NO ₂ , —C≡N, —N═C═S, fluorine, or —OCF ₃ ; Y ^a and Y ^b are hydrogen or fluorine. Preferred proportions of these stabilizers are in the range of 1-20% by weight, preferably in the range of 5-10% by weight, in order to obtain their effect.

A quenching agent is a compound that receives light energy absorbed by a liquid crystalline compound and converts it into heat energy, thereby preventing decomposition of the liquid crystalline compound. A preferable proportion of these quenchers is about 50 ppm or more to obtain the effect, and about 20000 ppm or less to lower the minimum temperature. More preferred proportions range from about 100 ppm to about 10,000 ppm.

Dichroic dyes such as azo dyes, anthraquinone dyes, etc. are added to the composition in order to match the GH (guest host) mode device. Preferred proportions of pigment range from about 0.01% to about 10% by weight. Antifoaming agents such as dimethylsilicone oil, methylphenylsilicone oil, etc. are added to the composition to prevent foaming. A preferable proportion of the antifoaming agent is about 1 ppm or more to obtain its effect, and about 1000 ppm or less to prevent display defects. More preferred percentages range from about 1 ppm to about 500 ppm.

A polymerizable compound is added to the composition to make it compatible with the polymer-stabilized device. Preferred examples of polymerizable compounds are compounds having polymerizable groups such as acrylates, methacrylates, vinyl compounds, vinyloxy compounds, propenyl ethers, epoxy compounds (oxiranes, oxetanes), vinyl ketones. Further preferred examples are derivatives of acrylates or methacrylates. A preferable proportion of the polymerizable compound is about 0.05% by weight or more to obtain its effect, and about 20% by weight or less to prevent an increase in driving temperature. A more preferred percentage ranges from about 0.1% to about 10% by weight. The polymerizable compound is polymerized by UV irradiation. Polymerization may be carried out in the presence of an initiator such as a photoinitiator. Suitable conditions for polymerization, suitable types of initiators, and suitable amounts are known to those skilled in the art and described in the literature. For example, the photoinitiators Irgacure 651 (registered trademark; BASF), Irgacure 184 (registered trademark; BASF) or Darocure 1173 (registered trademark; BASF) are suitable for radical polymerization. A preferred proportion of photoinitiator ranges from about 0.1 parts by weight to about 5 parts by weight based on 100 parts by weight of the polymerizable compound. A more preferred proportion is in the range of about 1 part to about 3 parts by weight.

A polymerization inhibitor may be added to prevent polymerization during storage of the polymerizable compound. The polymerizable compound is usually added to the composition without removing the polymerization inhibitor. Examples of polymerization inhibitors are hydroquinone, hydroquinone derivatives such as methylhydroquinone, 4-tert-butylcatechol, 4-methoxyphenol, phenothiazine and the like.

In this specification, a polar compound is an organic compound with polarity and does not include compounds with ionic bonds. Atoms such as oxygen, sulfur, and nitrogen are more electronegative and tend to have a partial negative charge. Carbon and hydrogen tend to be neutral or have a partial positive charge. Polarity results from the uneven distribution of partial charges between different atoms in a compound. For example, a polar compound has at least one substructure such as —OH, —COOH, —SH, —NH ₂ , >NH, >N—.

Seventh, the method for synthesizing the component compounds will be described. These compounds are available from Organic Syntheses, John Wiley & Sons, Inc., Organic Reactions, John Wiley & Sons, Inc., Comprehensive Organic Synthesis, Perga. It can be synthesized by the method described in books such as Shin Jikken Kagaku Koza (Maruzen). Compositions are prepared by known methods from the compounds thus obtained. For example, the component compounds are mixed and dissolved together by heating.

Finally, the use of the composition will be explained. The compositions of the present invention primarily have a lower temperature limit of about −10° C. or lower, an upper temperature limit of about 70° C. or higher, and a refractive index anisotropy of 25° C. at a wavelength of 589 nm in the range of about 0.20 to about 0.80. have.
Compositions having refractive index anisotropy in the range of about 0.30 to about 0.60, or even about 0.40, by controlling the proportions of component compounds or by mixing other liquid crystalline compounds Compositions having refractive index anisotropy ranging from to about 0.55 may be prepared. This composition can be used as a composition having a nematic phase, and can be used as an optically active composition by adding an optically active compound.

This composition can be used for elements used for controlling electromagnetic waves with frequencies of 1 GHz to 10 THz. Applications include, for example, a millimeter wave band variable phase shifter, a LiDAR (Light Detection and Ranging) element, an antenna to which metamaterial technology is applied, and the like.

For use in driving devices at frequencies up to about 100 kHz, the dielectric anisotropy (Δε) of the composition should be large in order to reduce the driving voltage of the device. The dielectric anisotropy is preferably in the range of 1-50, more preferably in the range of 1-30. From the viewpoint of use in elements used for electromagnetic wave control with a frequency of 1 GHz to 10 THz, the dielectric anisotropy at 25 ° C. (for example, Δε@28 GHz) at any frequency from 1 GHz to 10 THz is preferably 0.8 It is in the range of 3.0, more preferably in the range of 1.0 to 3.0.

The present invention will be described in more detail by way of examples. The invention is not limited by these examples. The invention also includes mixtures of at least two of the compositions of the Examples. The properties of the compositions were measured by the methods described below.

Measurement method: Properties were measured by the following methods. Many of these are methods described in the JEITA standard (JEITA ED-2521B) deliberated and established by the Japan Electronics and Information Technology Industries Association (hereinafter referred to as JEITA), or modified methods thereof was the method. A thin film transistor (TFT) was not attached to the TN device used for the measurement.

Upper limit temperature of nematic phase (NI; °C):
The sample was placed on a hot plate of a melting point apparatus equipped with a polarizing microscope and heated at a rate of 1°C/min. The temperature was measured when part of the sample changed from the nematic phase to the isotropic liquid.

Lower limit temperature of nematic phase ( _TC ; °C):
A sample having a nematic phase was placed in a glass bottle and stored in a freezer at 0°C, -10°C, -20°C, -30°C and -40°C for 10 days, and then the liquid crystal phase was observed. For example, when a sample remained in a nematic phase at -20°C and changed to a crystalline or smectic phase at -30°C, the T _C was described as < -20°C.

Viscosity (bulk viscosity; η; measured at 20°C; mPa s):
An E-type rotational viscometer manufactured by Tokyo Keiki Co., Ltd. was used for the measurement.

Viscosity (rotational viscosity; γ1; measured at 25°C; mPa s):
The measurement followed the method described in M. Imai et al., Molecular Crystals and Liquid Crystals, Vol. 259, 37 (1995). A sample was placed in a TN device with a twist angle of 0° and a gap (cell gap) between two glass substrates of 5 μm. A voltage of 16 V to 19.5 V was applied to the device in steps of 0.5 V. After 0.2 seconds of no application, application was repeated under the conditions of only one rectangular wave (rectangular pulse; 0.2 seconds) and no application (2 seconds). The peak current and peak time of the transient current generated by this application were measured. Rotational viscosity values were obtained from these measurements and equation (8) on page 40 of M. Imai et al. The value of the dielectric anisotropy required for this calculation was obtained by the method described below using the device for which the rotational viscosity was measured.

Refractive index anisotropy (for Δn<0.30; measured at 25° C.):
The measurement was performed with an Abbe refractometer having a polarizing plate attached to an eyepiece using light with a wavelength of 589 nm. After rubbing the surface of the main prism in one direction, the sample was dropped onto the main prism. The refractive index _n∥ was measured when the direction of polarization was parallel to the rubbing direction. The refractive index _n⊥ was measured when the polarization direction was perpendicular to the rubbing direction. The value of refractive index anisotropy was calculated from the formula Δn= _n∥ − _n⊥ .

Refractive index anisotropy (for Δn≧0.30; measured at 25° C.):
A sample was placed in a device composed of two glass substrates and oriented antiparallel. The thickness direction retardation (Rth) of this element was measured using a retardation film/optical material inspection device (manufactured by Otsuka Electronics Co., Ltd., trade name: RETS-100), and the retardation value (Rth) and the distance between the glass substrates were measured. The refractive index anisotropy (Δn) was calculated from (d: cell gap) by the following formula. The wavelength of light used is 589 nm.
Rth=Δn·d

Dielectric anisotropy (Δε; measured at 25°C):
A sample was placed in a TN device in which the distance (cell gap) between the two glass substrates was 9 μm and the twist angle was 80 degrees. A sine wave (10 V, 1 kHz) was applied to this device, and after 2 seconds the permittivity ( _ε∥ ) in the longitudinal direction of the liquid crystal molecules was measured. A sine wave (0.5 V, 1 kHz) was applied to this device, and after 2 seconds the permittivity (ε _⊥ ) in the minor axis direction of the liquid crystal molecules was measured. The value of the dielectric anisotropy was calculated from the formula Δε= _ε∥ − _ε⊥ .

Threshold voltage (Vth; measured at 25°C; V):
A luminance meter LCD5100 manufactured by Otsuka Electronics Co., Ltd. was used for the measurement. The light source was a halogen lamp. A sample was placed in a normally white mode TN device in which the distance (cell gap) between the two glass substrates was 0.45/Δn (μm) and the twist angle was 80 degrees. The voltage (32 Hz, square wave) applied to this device was increased stepwise from 0 V to 10 V by 0.02 V. At this time, the device was irradiated with light from a vertical direction, and the amount of light transmitted through the device was measured. A voltage-transmittance curve was prepared in which the transmittance was 100% when the amount of light was maximum and the transmittance was 0% when the amount of light was minimum. The threshold voltage was expressed as the voltage when the transmittance reached 90%.

Specific resistance (ρ; measured at 25°C; Ωcm):
A 1.0 mL sample was injected into the container with the electrodes. A DC voltage (10 V) was applied to this container, and the DC current was measured after 10 seconds. The specific resistance was calculated from the following formula. (Specific resistance)={(Voltage)×(Electric capacity of container)}/{(DC current)×(Vacuum permittivity)}.

Dielectric anisotropy at 28 GHz (measured at room temperature):
Dielectric anisotropy at 28 GHz (Δε@28 GHz) is reported in Applied Optics, Vol. 44, No. 7, p. 1150 (2005), a V-band variable short-circuit waveguide fitted with a window material was filled with liquid crystal and held in a static magnetic field of 0.3 T for 3 minutes. A microwave of 28 GHz was input to the waveguide, and the amplitude ratio of the reflected wave to the incident wave was measured. Refractive indices (n: ne, no) and loss parameters (α: αe, αo) were determined by changing the direction of the static magnetic field and the tube length of the shunt.
For the calculation of the complex permittivity, the refractive index and the loss parameter calculated in the previous section and the following relational expression were used.
ε′=n ² −κ ²
ε″=2nκ
α=2ωκ/c
where c is the speed of light in a vacuum. _ε'∥ was calculated from _ne and _ε'⊥ from _no , and the dielectric anisotropy (Δε@28 GHz) was calculated from _ε'∥ - _ε'⊥ .

Tan δ at 28 GHz (measured at room temperature):
Tan δ at 28 GHz was calculated as tan δ=ε″/ε′ using complex dielectric constants (ε′, ε″). Since anisotropy also appears in tan δ, the larger value is indicated.

Compounds in Examples are represented by symbols based on the definitions in Table 2. The numbers in parentheses after the symbols correspond to the compound numbers. The symbol (-) means other liquid crystalline compounds. The ratio (percentage) of the liquid crystal compound is the weight percentage (% by weight) based on the weight of the liquid crystal composition. Finally, the characteristic values of the composition are summarized.

[Comparative Example 1] Liquid crystal composition C1
3-BTTB-O1 (2-4) 15%
5-BTTB-O1 (2-4) 15%
5-BTB (F) TB-2 (3-3) 10%
5-BTB (F) TB-3 (3-3) 10%
5-B(F) TB(F)-TC (4-3) 15%
5-B(Me)TB(F)-TC (4-3) 15%
2O-btTB-3 (-) 20%
NI=128.3° C.; Tc<−10° C.; Δn=0.440; Δε=12.3;
The dielectric anisotropy and tan δ of the liquid crystal composition C1 at 28 GHz were as follows.
Δε @ 28 GHz = 1.05
tan δ @ 28 GHz = 0.014

[Example 1] Liquid crystal composition 1
5-BTB(F,F)-TCF3 (1-1) 15%
3-BTTB-O1 (2-4) 15%
5-BTTB-O1 (2-4) 15%
5-BTB (F) TB-2 (3-3) 10%
5-BTB (F) TB-3 (3-3) 10%
5-B(F) TB(F)-TC (4-3) 15%
2O-btTB-3 (-) 20%
NI=117.3° C.; Tc<−10° C.; Δn=0.420; Δε=11.0;
The dielectric anisotropy and tan δ of liquid crystal composition 1 at 28 GHz were as follows.
Δε @ 28 GHz = 1.02
tan δ @ 28 GHz = 0.014

[Example 2] Liquid crystal composition 2
5-BTB(F,F)-TCF3 (1-1) 15%
4-BBTB(F,F)-TCF3 (1-5) 5%
5-BBTB(F,F)-TCF3 (1-5) 5%
5-BB(F)TB-TCF3 (1-5) 5%
3-BTTB-O1 (2-4) 15%
5-BTTB-O1 (2-4) 15%
5-BTB (F) TB-2 (3-3) 10%
5-BTB (F) TB-3 (3-3) 10%
2O-btTB-3 (-) 20%
NI=130.4° C.; Tc<−10° C.; Δn=0.411; Δε=8.4;
The dielectric anisotropy and tan δ of liquid crystal composition 2 at 28 GHz were as follows.
Δε @ 28 GHz = 1.01
tan δ @ 28 GHz = 0.013

[Example 3] Liquid crystal composition 3
5-BTB(F,F)-TCF3 (1-1) 15%
4-BBTB(F,F)-TCF3 (1-5) 5%
5-BBTB(F,F)-TCF3 (1-5) 5%
3-BB(F)TB-TCF3 (1-5) 5%
4-BB(F)TB-TCF3 (1-5) 5%
5-BB(F)TB-TCF3 (1-5) 5%
3-BTTB-O1 (2-4) 15%
5-BTTB-O1 (2-4) 15%
5-BTB (F) TB-2 (3-3) 10%
5-BTB (F) TB-3 (3-3) 10%
2O-btTB-3 (-) 10%
NI=133.8° C.; Tc<−10° C.; Δn=0.413; Δε=10.1;
The dielectric anisotropy and tan δ of liquid crystal composition 3 at 28 GHz were as follows.
Δε @ 28 GHz = 1.03
tan δ @ 28 GHz = 0.013

[Example 4] Liquid crystal composition 4
5-BTB(F,F)-TCF3 (1-1) 20%
5-B(F)TB(F)-TCF3 (1-1) 20%
3-BBTB(F,F)-TCF3 (1-5) 10%
4-BBTB(F,F)-TCF3 (1-5) 10%
5-BBTB(F,F)-TCF3 (1-5) 10%
3-BB(F)TB-TCF3 (1-5) 10%
4-BB(F)TB-TCF3 (1-5) 10%
5-BB(F)TB-TCF3 (1-5) 10%
NI=98.3° C.; Δn=0.383; Δε=22.7; ρ=9.7E12 Ωcm.
The dielectric anisotropy and tan δ of liquid crystal composition 4 at 28 GHz were as follows.
Δε @ 28 GHz = 1.00
tan δ @ 28 GHz = 0.012

Compared with the comparative example, in the example, Δε at 28 GHz was similarly large, and tan δ at 28 GHz was maintained similarly small, while a liquid crystal composition having a large specific resistance (ρ) could be prepared.

The liquid crystal composition of the present invention has a high upper limit temperature of the nematic phase, a low lower limit temperature of the nematic phase, a low viscosity, a large dielectric anisotropy in the frequency range used for phase control, and a frequency range used for phase control. and a large resistivity in the driving frequency range. Devices containing this composition can be used for phase control of electromagnetic wave signals with frequencies of 1 GHz to 10 THz over a wide temperature range.

Claims (16)

A liquid crystal composition containing at least one compound selected from the group of compounds represented by formula (1) and used for electromagnetic wave control at a frequency of any one of 1 GHz to 10 THz.

In formula (1),
R ¹ is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O—;
Ring A ¹ is

or

is;
Z ¹¹ is a single bond, —CH═CH—, or —C≡C—; Z ¹² and Z ¹³ are a single bond, —C≡C—, or —C≡CC≡C— but at least one of Z ¹² and Z ¹³ is not a single bond;
L ¹¹ , L ¹² , L ¹³ , L ¹⁴ , L ¹⁵ and L ¹⁶ are hydrogen, fluorine, chlorine, methyl, ethyl or cyclopropyl;
Y ¹¹ and Y ¹² are hydrogen, fluorine, methyl or chlorine;
X ¹ is fluorine, —CF ₃ , or —OCF ₃ ;
n1 is 0, 1, or 2; 2. The liquid crystal composition according to claim 1, containing at least one compound selected from the group of compounds represented by formulas (1-1) to (1-8).

In formulas (1-1) to (1-8),
R ¹ is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O—;
L ¹¹ , L ¹⁴ , L ¹⁵ , and L ¹⁶ are hydrogen, fluorine, chlorine, methyl, ethyl, or cyclopropyl;
Y ¹¹ and Y ¹² are hydrogen, fluorine, or chlorine. 2. The liquid crystal composition according to claim 1, wherein the proportion of the compound represented by formula (1) is in the range of 10% by weight to 100% by weight based on the weight of the liquid crystal composition. 4. The liquid crystal composition according to any one of claims 1 to 3, containing at least one compound selected from the group of compounds represented by formula (2) and the group of compounds represented by formula (3). thing.

In formulas (2) to (3),
R ²¹ , R ²² , R ³¹ and R ³² are alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl is —O— may be replaced with;
Z ²¹ , Z ²³ , and Z ³¹ are a single bond, —CH═CH—, or —C≡C—; Z ³² and Z ³³ are a single bond, —C≡C—, or —C≡C -C≡C- and Z ²² is -C≡C- or -C≡CC≡C-;
^L21 , ^{L22 , L23} , ^L31 , L32, ^L33 , ^L34 , ^L35 , and ^L36 are hydrogen, fluorine, chlorine, methyl, or ethyl. 5. The liquid crystal composition according to claim 4, containing at least one compound selected from the group of compounds represented by formulas (2-1) to (2-5).

In formulas (2-1) to (2-5),
R ²¹ and R ²² are alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O— often;
L ²¹ , L ²² and L ²³ are hydrogen, fluorine, chlorine, methyl or ethyl. 5. The liquid crystal composition according to claim 4, wherein the proportion of the compound represented by formula (2) is in the range of 20% by weight to 50% by weight based on the weight of the liquid crystal composition. 7. The liquid crystal composition according to any one of claims 4 to 6, comprising at least one compound selected from the group of compounds represented by formulas (3-1) to (3-4).

In formulas (3-1) to (3-4),
R ³¹ and R ³² are alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O— often;
L ³¹ , L ³² , L ³³ , L ³⁴ , L ³⁵ and L ³⁶ are hydrogen, fluorine, chlorine, methyl or ethyl. 5. The liquid crystal composition according to claim 4, wherein the proportion of the compound represented by formula (3) is in the range of 10% by weight to 40% by weight based on the weight of the liquid crystal composition. 9. The liquid crystal composition according to any one of claims 1 to 8, containing at least one compound selected from the group of compounds represented by formula (4).

In formula (4),
R ⁴ is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O—;
Z ⁴¹ is a single bond, —CH═CH—, or —C≡C—; Z ⁴² and Z ⁴³ are a single bond, —C≡C—, or —C≡CC≡C— ;
L ⁴¹ , L ⁴² , L ⁴³ , L ⁴⁴ and L ⁴⁵ are hydrogen, fluorine, chlorine, methyl, ethyl or cyclopropyl;
Y ⁴¹ and Y ⁴² are hydrogen, fluorine, or chlorine;
X ⁴ is -C≡N, -C≡C-C≡N, or -N=C=S;
n4 is 0, 1, or 2; 10. The liquid crystal composition according to claim 9, containing at least one compound selected from the group of compounds represented by formulas (4-1) to (4-12).

In formulas (4-1) to (4-12),
R ⁴ is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms, and at least one —CH ₂ — in said alkyl or said alkenyl may be replaced with —O—;
L ⁴¹ , L ⁴³ , L ⁴⁴ , and L ⁴⁶ are hydrogen, fluorine, chlorine, methyl, ethyl, or cyclopropyl;
Y ⁴¹ and Y ⁴² are hydrogen, fluorine, or chlorine. 10. The liquid crystal composition according to claim 9, wherein the proportion of the compound represented by formula (4) is in the range of 5% by weight to 40% by weight based on the weight of the liquid crystal composition. 12. The liquid crystal composition according to claim 1, wherein the refractive index anisotropy at 25° C. at a wavelength of 589 nm is in the range of 0.20 to 0.80. 13. The liquid crystal composition according to any one of claims 1 to 12, wherein the dielectric anisotropy at 25°C at any frequency from 1 GHz to 10 THz is in the range of 0.4 to 3.0. 14. The liquid crystal composition according to any one of claims 1 to 13, comprising an optically active compound. 15. The liquid crystal composition according to any one of claims 1 to 14, comprising a polymerizable compound. 16. A device used for electromagnetic wave control of any frequency from 1 GHz to 10 THz, containing the liquid crystal composition according to any one of claims 1 to 15.