Liquid crystal dielectric applicable to high-frequency electromagnetic wave modulation, and component thereof

Abstract

A liquid crystal dielectric applicable to high-frequency electromagnetic wave modulation has a clearing point of the liquid crystal dielectric higher than 110° C., a low-temperature storage temperature lower than −20° C., and an optical anisotropy greater than 0.35. The liquid crystal dielectric includes: one or more compounds selected by general formula I, which occupy 30-80% of the total weight of the liquid crystal dielectric, and one or more compounds selected by general formula II and/or general formula III, which occupy 20-70% of the total weight of the liquid crystal dielectric. The liquid crystal dielectric has good low-temperature stability, high dielectric anisotropy, a high phase width, appropriate rotary viscosity, appropriate optical anisotropy, low dielectric loss, and a low loss tangent, exhibits strong high-frequency electromagnetic wave tuning capability, is specifically suitable for electromagnetic wave modulation in microwave or millimeter wave areas, and has a good application prospect in liquid crystal phase shifters. ##STR00001##

Claims

1. A liquid-crystalline medium applicable to high-frequency electromagnetic wave modulation, wherein the liquid-crystalline medium having a clearing point of more than 110° C., a low-temperature storage temperature of below −20° C., and an optical anisotropy of more than 0.35, the liquid-crystalline medium comprising: one or more compounds selected from the compounds of general Formula I in an amount of 30-80% of the total weight of the liquid-crystalline medium: ##STR00037## one or more compounds selected from the compounds of general Formula II and/or general Formula III in an amount of 20-70% of the total weight of the liquid-crystalline medium: ##STR00038## in which, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 each independently represents C.sub.1-12 alkane group, ##STR00039## one or more than two nonadjacent —CH.sub.2— in the alkane group can each be independently replaced by —CH═CH—, —C≡C—, —O—, —CO—, —CO—O— or —O—CO—, and one or more —H present in these groups can each be independently substituted by —F or —Cl; and X.sub.1, X.sub.2, X.sub.3, X.sub.4 and X.sub.5 each independently represents —H, —F or —OCF.sub.3, and at least two of X.sub.1, X.sub.2 and X.sub.3 represents —F; and one or more compounds selected from a group consisting of the following compounds: ##STR00040## in which, R.sub.81 represents C.sub.4-10 alkane group or alkoxyl group; and L.sub.1 and L.sub.2 each independently represents —H or —F.

2. A liquid-crystalline medium according to claim 1, wherein R.sub.1 and R.sub.2 each independently selected from a group consisting of —C.sub.2H.sub.5, —C.sub.3H.sub.7, —C.sub.4H.sub.9 and —C.sub.5H.sub.11.

3. A liquid-crystalline medium according to claim 1, wherein the compound of general Formula II is selected from a group consisting of the following compounds: ##STR00041## in which, R.sub.31 and R.sub.41 each independently represents C.sub.2-6 alkane group, ##STR00042##

4. A liquid-crystalline medium according to claim 1, wherein the compound of general Formula III is selected from a group consisting of the following compounds: ##STR00043## in which, R.sub.51 and R.sub.61 each independently represents C.sub.2-6 alkane group, ##STR00044## and R.sub.71 represents C.sub.1-5 alkane group, ##STR00045##

5. A liquid-crystalline medium according to claim 1, wherein the liquid-crystalline medium can further comprise one or more compounds selected from the compounds of general Formula V: ##STR00046## in which, R.sub.10 and R.sub.11 each independently represents C.sub.1-12 alkane group, alkoxyl group, alkenyl group or alkenyloxy group; Z.sub.2 represents single bond, —CF.sub.2O—, —OCF.sub.2—, —CO—O—, —O—CO— or —CH.sub.2CH.sub.2—; and n represents 0 or 1.

6. A liquid-crystalline medium according to claim 5, wherein the compound of general Formula V is selected from a group consisting of the following compounds: ##STR00047## wherein R.sub.10 and R.sub.11 each independently represents C1-12 alkane group, alkoxyl group, alkenyl group or alkenyloxy group.

7. A liquid-crystalline medium according to claim 1, wherein the liquid-crystalline medium further comprises one or more additives.

8. A component for high-frequency technology, comprising the liquid-crystalline medium of claim 1.

Description

DETAILED EMBODIMENTS

(1) The present invention will be illustrated by combining the detailed embodiments below. It should be noted that, the following examples are exemplary embodiments of the present invention, which are only used to illustrate the present invention, and not to limit it. Other combinations and various modifications within the conception of the present invention are possible without departing from the subject matter or scope of the present invention.

(2) For the convenience of the expression, the group structures of the liquid-crystalline medium in each of the following Examples are represented by the codes listed in Table 1:

(3) TABLE-US-00001 TABLE 1 Codes of the group structures of liquid crystal compounds Unit structure of group Code Name of group C 1,4-cyclohexylidene P 1,4-phenylene G 2-fluoro-1,4- phenylene U 2,6-difluoro-1,4- phenylene W 2,3-difluoro-1,4- phenylene M 2,5-pyrimidinyl 0 P(n) 2-alkyl-1,4-phenylene —CH.sub.2CH.sub.2— 2 ethyl bridge bond —OCF.sub.3 OCF3 trifluoromethoxy —F F fluorine substituent —Cl Cl chlorine substituent —CN N cyano —SCN NCS thiocyanato —O— O oxygen substituent —CF.sub.2O— 1(2F)O or Q difluoro ether group —CH.sub.2O— 1O methyleneoxy —COO— E ester bridge bond —C.sub.nH.sub.2n+1 or n or m (n or m each alkyl —C.sub.mH.sub.2m+1 represents a positive integer of 1-12) —CH═CH— or V alkenyl —CH═CH.sub.2 —C≡C— T acetenyl

(4) Take a compound with the following structural formula as an example:

(5) ##STR00031##

(6) Represented by the codes listed in Table 1, this structural formula can be expressed as: nPTPm, n in the code represents the number of the carbon atoms of the alkyl on the left end, for example, n is “3”, meaning that the alkyl is —C.sub.3H.sub.7; Pin the code represents 1,4-phenylene, T in the code represents acetonyl, m represents the number of the carbon atoms of the alkyl on the right end, for example, m is “4”, meaning that the alkyl is —C.sub.4H.sub.9.

(7) The abbreviated codes of the test items in the following Comparative Example 2 and Examples 1-2 are as follows (the testing conditions of Comparative Example 1 can refer to the Reference Document in which it is contained): Cp clearing point (nematic-isotropic phases transition temperature, ° C.) LTS low-temperature storage temperature (° C.) Δn optical anisotropy (589 nm, 25° C.) ne extraordinary refraction index no ordinary refraction index Δε dielectric anisotropy (1 KHz, 25° C.) ε.sub.// parallel dielectric anisotropy (1 KHz, 25° C.) ε.sub.⊥ perpendicular dielectric anisotropy (1 KHz, 25° C.) γ1 rotational viscosity (mPa.Math.s, 25° C.)

(8) in which,

(9) optical anisotropy is tested and obtained using Abbe refractometer under sodium lamp (589 nm) light source at 25° C.; and

(10) Δε=ε.sub.//−ε.sub.⊥, in which, ε.sub.// is a dielectric constant parallel to the molecular axis, ε.sub.⊥ is a dielectric constant perpendicular to the molecular axis, with the test conditions: 25° C., 1 KHz, VA type test cell with a cell gap of 6 μm.

(11) Testing Method of High-Frequency Performances:

(12) The liquid crystal is introduced into a polytetrafluoroethylene (PTFE) or fused silica capillary. The capillary has an internal radius of 180 μm and an external radius of 350 μm. The effective length is 2.0 cm. The filled capillary is introduced into the center of the cylindrical cavity with a resonance frequency of 19 GHz. This cavity has a length of 11.5 mm and a radius of 6 mm. The input signal (source) is then applied, and the result of the output signal is recorded using a commercial vector network analyzer. For other frequencies, the dimensions of the cavity can be adjusted accordingly.

(13) The change in the resonance frequency and the Q factor between the measurement with the capillary filled with the liquid crystal and the measurement without the capillary filled with the liquid crystal is used to determine the dielectric constant as well as the dielectric loss and dielectric dissipation factor at the corresponding target frequency by means of equations 10 and 11 A. Penirschke, S. Müller, P. Scheele, C. Weil, M. Wittek, C. Hock and R. Jakoby: “Cavity Perturbation Method for Characterization of Liquid Crystals up to 35 GHz”, 34.sup.th European Microwave Conference-Amsterdam, pp. 545-548, as described therein.

Comparative Example 1 (Example 1 of CN103842474B)

(14) The liquid-crystalline medium with the formulation and properties as shown below in Table 2 is prepared.

(15) TABLE-US-00002 TABLE 2 Formulation of the liquid-crystalline medium and its physical performances Code of Weight component percentage Physical performances 4UTPP3 25.1 Phase range LTS >0° C. 4UTPP4 48.5 (° C.) Cp 163.5 2UTPP3 26.4 optical anisotropy Δn 0.4 Total 100 (20° C., 589.3 nm) ne / no / Low-frequency Δε 1 dielectric anisotropy ε.sub.// 3.8 (1 KHz, 20° C.) ε.sub.⊥ 2.8 rotational viscosity γ1 310 (mPa .Math. s, 20° C.)

Comparative Example 2

(16) The liquid-crystalline medium with the formulation and properties as shown below in Table 3 is prepared.

(17) TABLE-US-00003 TABLE 3 Formulation of the liquid-crystalline medium and its physical performance Code of Weight component percentage Physical performances 2PTP6 2.5 Phase range LTS −30 5PTPO1 2 (° C.) Cp 103 4PTPO2 1 optical anisotropy Δn 0.305 5PTPO2 1 (25° C., 589 nm) ne 1.82 2UTPP3 4 no 1.515 2UTPP4 17 Low-frequency Δε 7.9 3UTPP2 4 dielectric ε.sub.// 11.7 3UTPP4 12 anisotropy ε.sub.⊥ 3.8 (1 KHz, 25° C.) 4UTPP3 20 rotational viscosity γ1 246 3CEPTP5 3.5 (mPa .Math. s, 25° C.) 3CPO1 6 V2PEUN 4 V2PTP2V 15 3MUN 8 Total 100

(18) The above liquid-crystalline medium is further incorporated with

(19) ##STR00032##
in an amount of 0.7% of the total weight of the liquid-crystalline medium.

Example 1

(20) The liquid-crystalline medium with the formulation and properties as shown below in Table 4 is prepared.

(21) TABLE-US-00004 TABLE 4 Formulation of the liquid-crystalline medium and its physical performance Code of Weight component percentage Physical performances 3UTGTP2 8 Phase range LTS −20 2UTPP3 5 (° C.) Cp 160 2UTPP4 12 Δn 0.3942 3UTPP2 10 optical anisotropy ne 1.9076 3UTPP4 9 (25° C., 589 nm) no 1.5134 4UTPP3 16 Low-frequency Δε 2 3CEPTP5 3 dielectric anisotropy ε.sub.// 4.9 4UTGTP5 8 (1 KHz, 25° C.) ε.sub.⊥ 2.9 3UTGTP5 8 rotational viscosity γ1 280 3UTP(1)TP2 8 (mPa .Math. s, 25° C.) 4UTP(1)TP3 8 7PGNCS 5 Total 100

(22) The above liquid-crystalline medium is further incorporated with

(23) ##STR00033##
in an amount of 0.5% of the total weight of the liquid-crystalline medium, and

(24) ##STR00034##
in an amount of 0.4% of the total weight of the liquid-crystalline medium.

Example 2

(25) The liquid-crystalline medium with the formulation and properties as shown below in Table 5 is prepared.

(26) TABLE-US-00005 TABLE 5 Formulation of the liquid-crystalline medium and its physical performance Code of Weight component percentage Physical performances 3UTGTP2 4 Phase range LTS −30 5PTPO1 6 (° C.) Cp 131 4PTPO2 6 optical anisotropy Δn 0.3672 2UTPP3 5 (25° C., 589 nm) ne 1.8816 2UTPP4 5 no 1.5144 3UTPP2 9 Low-frequency Δε 3.2 3UTPP4 9 dielectric anisotropy ε.sub.// 6.2 4UTPP3 15 (1 KHz, 25° C.) ε.sub.⊥ 3 4UTGTP5 4 rotational viscosity γ1 242 3UTGTP5 5 (mPa .Math. s, 25° C.) 5PPN 5 NPGP3 4 3UTP(1)TP2 5 4UTP(1)TP2 5 4UTP(1)TP3 5 V2PTP2V 8 Total 100

(27) The above liquid-crystalline medium is further incorporated with

(28) ##STR00035##
in an amount of 1% of the total weight of the liquid-crystalline medium, and

(29) ##STR00036##
in an amount of 0.8% of the total weight of the liquid-crystalline medium.

(30) The high-frequency performance test results of comparative Example 2 and Examples 1-2 are shown in Table 6 below.

(31) (note: the liquid-crystalline medium of Comparative Example 1 crystallizes at room temperature, and therefore can not be tested for the following high-frequency performance)

(32) TABLE-US-00006 TABLE 7 High-frequency performance test results High-frequency Comparative performances Frequency Example 2 Example 1 Example 2 High-frequency 10 GHz 3.434 3.1 3.341 dielectric 15 GHz 3.506 3.241 3.396 constant 25 GHz 3.577 3.307 3.454 Dielectric loss 10 GHz 0.0816 0.0416 0.0554 15 GHz 0.0796 0.0399 0.0532 25 GHz 0.0999 0.0452 0.0603 Dielectric 10 GHz 0.0238 0.0125 0.0166 dissipation factor 15 GHz 0.0227 0.0118 0.0157 25 GHz 0.0279 0.0131 0.0175

(33) Based on the above test data, the following conclusions can be drawn:

(34) From the comparison between Comparative Example 1 and Examples 1-2, it can be seen that the liquid-crystalline medium of the present invention has significantly better low-temperature stability, which can meet the outdoor use requirements of the phase shifter; and

(35) From the comparison between Comparative Example 2 and Examples 1-2, it can be seen that the liquid-crystalline medium of the present invention maintains substantially equivalent low-temperature stability and high-frequency dielectric constant, while having a lower dielectric loss and lower dielectric dissipation factor, as well as a larger optical anisotropy a better high-frequency electromagnetic wave tunability.

(36) In conclusion, the liquid-crystalline medium of the present invention has a good low-temperature stability, a higher dielectric anisotropy, a wider phase range, an appropriate rotational viscosity, an appropriate optical anisotropy, an appropriate high-frequency dielectric constant, a lower dielectric loss and a smaller dielectric dissipation factor, and exhibits a stronger tunability for high-frequency electromagnetic wave.

(37) The present invention can also be implemented by other various embodiments. Without departing from the spirit and essence of the present invention, the skilled person in the art can make various equivalent changes and modifications according to the present invention. However, these equivalent changes and modifications should fall within the protection scope of the appended claims of the present invention.

INDUSTRIAL APPLICABILITY

(38) The liquid-crystalline medium involved with the present invention can be applied to the field of liquid crystal.