CN115247072B

CN115247072B - Liquid crystal composition containing dibenzo derivative and application thereof

Info

Publication number: CN115247072B
Application number: CN202110460075.8A
Authority: CN
Inventors: 赵飞; 姚利芳; 贺笛; 徐爽; 丁文全; 潘帝可; 吴婷
Original assignee: Jiangsu Hecheng Display Technology Co Ltd
Current assignee: Jiangsu Hecheng Display Technology Co Ltd
Priority date: 2021-04-27
Filing date: 2021-04-27
Publication date: 2024-06-25
Anticipated expiration: 2041-04-27
Also published as: CN115247072A

Abstract

The invention provides a liquid crystal composition containing dibenzo derivatives and application thereof, wherein the liquid crystal composition contains at least one compound of a formula I and at least one compound of a formula II and/or a formula III. The liquid crystal composition has higher average elastic constant, higher transmittance, better ratio of vertical dielectric to dielectric and longer low-temperature storage time under the condition of maintaining proper optical anisotropy, proper clearing point and proper dielectric anisotropy, so that a liquid crystal display device comprising the liquid crystal composition has better contrast, better transmittance and better low-temperature storage stability under the condition of maintaining proper threshold voltage, the overall performance of the liquid crystal device is obviously improved, and the liquid crystal composition has wide application prospect.

Description

Liquid crystal composition containing dibenzo derivative and application thereof

Technical Field

The invention belongs to the technical field of liquid crystal materials, and particularly relates to a liquid crystal composition containing dibenzo derivatives and application thereof.

Background

In recent years, with the widespread use of TFT-type LCDs (thin film transistor-type liquid crystal display technology), the performance requirements thereof have been increasing, and high display image quality has been demanded to have a faster response speed, lower power consumption, and higher low-temperature reliability, and in addition, higher contrast and transmittance have been demanded. The contrast of the display is very critical to the visual effect, and in general, the larger the contrast is, the clearer and more striking the image and the more vivid and gorgeous the color is; the smaller the contrast, the more gray the whole picture will be. The high contrast is helpful for the definition, detail representation and gray level representation of the image.

Research shows that the contrast improvement method mainly comprises the following steps: (1) improving the brightness of a white picture; (2) making the black darker, reducing the minimum brightness. I.e. the liquid crystal needs to have a high light transmittance. As is clear from the transmittance formula T +|Δε|/ε _⊥ (T represents transmittance, "++" represents an "inverse ratio" relationship, ∈ _⊥ represents a dielectric constant perpendicular to the molecular axis) of the IPS (In-PLANE SWITCHING ) mode, it is possible to try to reduce Δε of the liquid crystal medium In order to increase the transmittance of the liquid crystal, but the adjustment range of the driving voltage of the same product is generally limited. In addition, the liquid crystal molecules are inclined to the Z-axis direction under the action of the vertical component of the fringe electric field, so that the optical anisotropy of the liquid crystal molecules is changed, and the formula is adopted(Wherein χ is the angle between the optical axis of the liquid crystal layer and the optical axis of the polarizer, Δn is the optical anisotropy, d is the cell pitch, λ is the wavelength), it is known that effective Δn×d affects T, and increasing Δn×d is also considered to increase the transmittance of positive liquid crystals, but the retardation design of each product is fixed.

On the other hand, those skilled in the art find, based on the conventional IPS-LCD light leakage performance test, that the main causes of the light leakage problem of the liquid crystal display device include: light scattering (LC SCATTERING), rubbing uniformity (rubbing uniformity), color filter light leakage (CF/TFT SCATTERING) and polarization capability (polarize ability), wherein the light scattering accounts for 63% of the influencing factors of the light leakage performance.

According to the following relation:

where d represents the pitch of the liquid crystal cell, n _e represents the extraordinary refractive index, and n _o represents the ordinary refractive index.

To improve the light scattering of the liquid crystal material, it is necessary to improve the light scattering by increasing the average elastic constant K _ave (K _ave＝(K₁₁+K₂₂+K₃₃)/(3), and when K _ave is increased, the light leakage of the liquid crystal material can be reduced.

Further, the relation between Contrast (CR) and brightness (L) is as follows:

CR＝L₂₅₅/L₀×100％；

Wherein L ₂₅₅ is on-state luminance and L ₀ is off-state luminance. It can be seen that what significantly affects CR should be a change in L ₀. In the off state, L ₀ is independent of the dielectric properties of the liquid crystal molecules and is related to LC SCATTERING of the liquid crystal material itself; the smaller LC SCATTERING is, the smaller L ₀ is, and the CR is significantly improved.

In view of the above, a common way to improve contrast and transmittance may be considered as follows: (1) The dielectric anisotropy delta epsilon of the liquid crystal composition is kept unchanged, and the transmittance can be effectively improved by improving epsilon _⊥; (2) The value of the elastic constant K of the liquid crystal composition is improved, so that the liquid crystal order is better, the light leakage is less, and the transmittance is improved. The prior art is mainly improved by adding a negative monomer into a positive liquid crystal component; however, the addition of the negative monomer slows down the response and deteriorates the low-temperature storage property. In the known prior art, epsilon _⊥ is not large enough; when epsilon _⊥ is large, the response is slow, and the K value is not large enough; i.e. the properties of the liquid crystal material are not balanced.

Patent application CN110499162a discloses dibenzo-based compounds of the formula:

The dibenzo compound has the advantages of large elastic constant, large dielectric coefficient, very stable structure and the like due to the characteristic benzofuran or benzothiophene structure, and can provide very excellent performance in TFT liquid crystals with fast response, high transmittance and the like. However, dibenzo compounds have the disadvantage of limited amounts, and excessive use can lead to reduced miscibility and reduced low temperature storage properties.

Therefore, development of a compound which can take advantages of dibenzo compounds into consideration, and make up for defects in low-temperature performance and the like, so that the liquid crystal composition has more excellent transmittance and contrast, better low-temperature storage performance and higher K value, and is a problem to be solved in the field.

Disclosure of Invention

In view of the shortcomings of the prior art, the present invention aims to provide a liquid crystal composition containing dibenzo derivatives and application thereof, wherein the liquid crystal composition has high average elastic constant, high transmittance, high ratio of vertical dielectric to dielectric and long low-temperature storage time under the condition of maintaining proper optical anisotropy, proper clearing point and proper dielectric anisotropy.

To achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a liquid crystal composition comprising a dibenzo derivative, the liquid crystal composition comprising:

At least one compound of formula I:

At least one compound of formula II and/or formula III:

Wherein R ₁ represents a linear or branched alkyl group having 1 to 12 carbon atoms, X _R represents a single bond, -O-or-S-; at least two-CH ₂ -of one or non-adjacent of the linear or branched alkyl groups containing 1 to 12 carbon atoms may each independently be replaced by-ch=ch-, -O-, or-S-; said/>At least two rings of which one or not adjacent-CH ₂ -may be independently replaced by-ch=ch-, -O-, or-S-, respectively; one or at least two-H of the foregoing groups may each be independently substituted with halogen.

Wherein, when X _R represents a single bond,Respectively represent/>

R ₂ represents a linear or branched alkyl group having 1 to 12 carbon atoms, At least two-CH ₂ -of one or non-adjacent of the foregoing groups may each independently be replaced by-ch=ch-, -O-, or-S-, and one or at least two-H may each independently be replaced by halogen; r ₂ is linked to the right-hand O of formula I via a C atom.

M ₁ and m ₂ each independently represent an integer from 0 to 6, and may be, for example, 0, 1,2, 3,4, 5 or 6.

Wherein m ₁ =0 represents that X _R is directly connected with the ring structure through a single bond.

R _A1 and R _A2 each independently represent a linear or branched alkyl group having 1 to 12 carbon atoms, At least two-CH ₂ -of one or non-adjacent of said linear or branched alkyl groups containing 1 to 12 carbon atoms may each independently be replaced by-ch=ch-, -c≡c-, -O-, -CO-O-or-O-CO-; one or at least two of the foregoing groups, -H, may each independently be substituted with-F or-Cl;

Ring(s) And Ring/>Each independently represents/> Said/>At least two-CH ₂ -that are not adjacent to one another or one or at least two of the rings may be replaced by-O-, and a single bond may be replaced by a double bond; said/>In which-ch=may be replaced by-n=and one or at least two-H may be substituted by halogen or methyl.

Ring(s)Ring/>Ring/>And Ring/>Each independently representsSaid/> The single bond in one or not adjacent at least two rings may be replaced by a double bond; said/> In which-ch=may be replaced by-n=and one or at least two-H may be replaced by-F, -Cl or-CN.

Z ₁ and Z ₂ each independently represent a single bond 、-CO-O-、-O-CO-、-CH₂O-、-OCH₂-、-CH＝CH-、-CF＝CF-、-CH₂CH₂-、-CF₂CF₂-、-CF₂O- or-OCF ₂ -.

Z _A11、Z_A21 and Z _A22 each independently represent a single bond, -CO-O-, -O-CO-, -CH ₂O-、-OCH₂-、-CH＝CH-、-CF＝CF-、-CH₂CH₂ -or-CF ₂CF₂ -.

Y ₁ and Y ₂ each independently represent-H, -F or-Cl.

X represents-O- -S-or-CO-.

L _A11、L_A12、L_A13、L_A21 and L _A22 each independently represent-H, unsubstituted or halogenated linear alkyl having 1 to 3 (e.g. 1,2 or 3) carbon atoms, halogen.

X _A1 and X _A2 each independently represent halogen, haloalkyl containing 1 to 5 (e.g., 1,2, 3, 4, or 5) carbon atoms, haloalkoxy containing 1 to 5 (e.g., 1,2, 3, 4, or 5) carbon atoms, haloalkenyl containing 2 to 5 (e.g., 2,3, 4, or 5) carbon atoms, or haloalkenoxy containing 2 to 5 (e.g., 2,3, 4, or 5) carbon atoms.

N represents an integer of 1 to 12 and may be, for example, 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12.

N ₁、n₂ each independently represents 0, 1 or 2; when n ₁ represents 2, the ringIdentical or different, Z ₁ identical or different; when n ₂ represents 2, ring/>The same or different, Z ₂ is the same or different.

N _A11 and n _A2 each independently represent 0,1,2 or 3; when n _A11 represents 2 or 3, the ringIdentical or different, Z _A11 identical or different; when n _A2 represents 2 or 3, ring/>The same or different, Z _A21 is the same or different.

N _A12 represents 1 or 2; when n _A12 represents 2, the ringThe same or different.

In the present invention, "can be replaced by … …" independently means that the material can be replaced or not replaced, that is, replaced or not replaced, and all the materials are within the protection scope of the present invention; "can be independently replaced by … …" in the same manner; also, the positions of "substitution" and "substitution" are arbitrary.

In the invention, short straight lines at one side or two sides of the group represent access bonds and do not represent methyl; for example Short straight line on left,/>-Short straight lines on both sides of O-.

In the present invention, the halogen includes fluorine, chlorine, bromine, iodine, or the like; the following description is referred to in the same sense.

In the present invention, the 1 to 12 carbon atoms may each be 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 carbon atoms.

The liquid crystal composition provided by the invention comprises at least one dibenzo derivative (a compound in a formula I) which is matched with at least one compound in a formula II and/or a formula III, so that the epsilon _⊥/[ delta ] epsilon value and K value of the positive liquid crystal composition are obviously improved on the premise of maintaining proper optical anisotropy, proper clearing point and higher dielectric anisotropy, and meanwhile, the liquid crystal composition has better transmittance, contrast and low-temperature storage performance, is favorable for improving the overall performance of liquid crystal materials, and is suitable for display modes such as IPS, NFFS and the like.

In a preferred embodiment, R ₁ represents a linear alkyl group containing 1 to 6 (e.g., 1, 2, 3,4, 5, or 6) carbon atoms, a linear alkoxy group containing 1 to 6 (e.g., 1, 2, 3,4, 5, or 6) carbon atoms, a linear alkylthio group containing 1 to 6 (e.g., 1, 2, 3,4, 5, or 6) atoms, Wherein m ₁ represents an integer of 0 to 4, and may be, for example, 0, 1, 2, 3 or 4.

In a further preferred embodiment, R ₁ represents a linear alkyl group containing 1 to 6 (e.g., 1, 2, 3, 4, 5, or 6) carbon atoms, a linear alkoxy group containing 1 to 6 (e.g., 1, 2, 3, 4, 5, or 6) carbon atoms, a linear alkylthio group containing 1 to 6 (e.g., 1, 2, 3, 4, 5, or 6) carbon atoms,

In a preferred embodiment, R ₂ represents a straight or branched alkyl group containing 1 to 6 (e.g., 1,2,3, 4,5, or 6) carbon atoms; one or at least two-H of the straight-chain or branched alkyl groups having 1 to 6 carbon atoms may each be independently substituted with halogen.

In a further preferred embodiment, said R ₂ represents an unsubstituted or halogenated (preferably fluorinated) linear alkyl group containing 1 to 6 (e.g. 1, 2, 3, 4, 5 or 6) carbon atoms; exemplary include, but are not limited to: methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, perfluoromethyl, perfluoroethyl, or-CH ₂-CF₃, and the like.

In a preferred embodiment, n represents an integer from 1 to 6, and may be, for example, 1, 2, 3, 4, 5 or 6.

In a preferred embodiment, both Y ₁ and Y ₂ represent-F.

In a preferred embodiment, X represents-O-or-S-.

In a preferred embodiment, n ₁ and n ₂ each represent 0.

In a preferred embodiment, the compound of formula I is selected from the group consisting of:

Wherein X represents-O-or-S-.

In a preferred embodiment, the mass percentage of the compound of formula I is adjusted so that the liquid crystal composition comprising it has a higher average elastic constant, higher transmittance, better ratio of vertical dielectric to dielectric and longer low temperature storage time.

In a preferred embodiment, the liquid crystal composition has a mass percentage of the compound of formula I of 0.1-30%, for example, 0.3%, 0.5%, 0.8%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25% or 28%, and the specific values between the above values, are limited in space and for brevity, the invention is not intended to be exhaustive list of the specific values included in the range.

In a preferred embodiment, the compound of formula II is selected from the group consisting of:

Wherein L _A11、L_A12、L_A14、L_A15 and L _A16 each independently represent-H or-F.

L _A13 represents-H or-CH ₃.

X _A1 represents-F, -CF ₃ or-OCF ₃.

In a further preferred embodiment, R _A1 represents a straight-chain alkyl group containing 1 to 8 (e.g. 1, 2, 3, 4, 5, 6, 7 or 8) carbon atoms.

In a further preferred embodiment, the compound of formula II is selected from any one or a combination of at least two of the compounds of formula II-2, formula II-4, formula II-5, formula II-6, formula II-9 or formula II-10.

In a preferred embodiment, the liquid crystal composition comprises at least one compound of formula II-6 in order to obtain a higher average elastic constant, higher transmittance, better vertical dielectric to dielectric ratio and longer low temperature storage time.

In a preferred embodiment, the liquid crystal composition comprises at least one compound of formula II-2 in order to obtain a higher average elastic constant, higher transmittance, better vertical dielectric to dielectric ratio and longer low temperature storage time.

In a preferred embodiment, the compound of formula III is selected from the group consisting of:

/>

Wherein L _A21、L_A22、L_A23、L_A24 and L _A25 each independently represent-H or-F.

X _A2 represents-F, -CF ₃、-OCF₃ or-CH ₂CH₂CH＝CF₂.

In a further preferred embodiment, R _A2 represents a straight-chain alkyl group containing 1 to 6 (e.g. 1, 2, 3, 4, 5 or 6) carbon atoms.

In a further preferred embodiment, the compound of formula III is selected from any one or a combination of at least two of a compound of formula III-1, a compound of formula III-3, a compound of formula III-5, a compound of formula III-9, a compound of formula III-10, a compound of formula III-12, a compound of formula III-13, or a compound of formula III-15.

In a preferred embodiment, the liquid crystal composition comprises at least one compound of formula III-1 and/or a compound of formula III-5 in order to obtain a higher average elastic constant, higher transmittance, better vertical dielectric to dielectric ratio and longer low temperature storage time.

In a preferred embodiment, the liquid crystal composition comprises at least one compound of formula III-12 in order to obtain a higher average elastic constant, higher transmittance, better vertical dielectric to dielectric ratio and longer low temperature storage time.

In a preferred embodiment, the liquid crystal composition comprises at least one compound of formula III-9 and/or III-13 in order to obtain a higher average elastic constant, higher transmittance, better vertical dielectric to dielectric ratio and longer low temperature storage time.

In a preferred embodiment, the mass percentage of the compounds of formula II and/or III in the liquid crystal composition is between 0.1 and 60%, for example 0.3％、0.5％、0.8％、1％、3％、5％、8％、10％、12％、15％、18％、20％、22％、25％、28％、30％、32％、35％、38％、40％、42％、45％、48％、52％、55％、58％, and the specific values between the above values, which are limited in space and for reasons of simplicity, the invention does not exclude an exhaustive list of the specific values comprised in the said range.

In a preferred embodiment, the liquid crystal composition comprises at least one compound of formula II and at least one compound of formula III in order to obtain a higher average elastic constant, higher transmittance, better vertical dielectric to dielectric ratio and longer low temperature storage time.

In a preferred embodiment, the mass percentage of the compound of formula II is adjusted so that the liquid crystal composition comprising it has a higher average elastic constant, higher transmittance, better ratio of vertical dielectric to dielectric and longer low temperature storage time.

In a preferred embodiment, the liquid crystal composition has a mass percentage of the compound of formula II of 0.1-50%, for example, 0.3%, 0.5%, 0.8%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% or 48%, and specific point values between the above point values, and the present invention is not intended to be exhaustive for the sake of brevity and conciseness.

In a preferred embodiment, the mass percentage of the compound of formula III is adjusted so that the liquid crystal composition comprising it has a higher average elastic constant, higher transmittance, better ratio of vertical dielectric to dielectric and longer low temperature storage time.

In a preferred embodiment, the liquid crystal composition has a mass percentage of the compound of formula III of 0.1-50%, for example, 0.3%, 0.5%, 0.8%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% or 48%, and specific point values between the above point values, and the present invention is not intended to be exhaustive for the sake of brevity and conciseness.

In a preferred embodiment, the liquid crystal composition further comprises at least one compound of formula M:

Wherein R _M1 and R _M2 each independently represent a linear or branched alkyl group having 1 to 12 (e.g., 1,2, 3,4,5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms, At least two-CH ₂ -of one or non-adjacent of the straight-chain or branched alkyl groups containing 1 to 12 carbon atoms may each be independently replaced by-ch=ch-, -c≡c-, -O-, -CO-O-or-O-CO-.

Ring(s)Ring/>And Ring/>Each independently represents/> Said/>At least two-CH ₂ -that are not adjacent to one another or one or at least two of the rings may be replaced by-O-, and a single bond may be replaced by a double bond; said/> In which-ch=can be replaced by-n=and at most one-H can be substituted by halogen.

Z _M1 and Z _M2 each independently represent a single bond, -CO-O-, -O-CO-, -CH ₂O-、-OCH₂-、-C≡C-、-CH＝CH-、-CH₂CH₂ -, or- (CH ₂)₄ -.

N _M represents 0, 1 or 2; when n _M represents 2, the ringThe same or different, Z _M2 is the same or different.

In a preferred embodiment, the compound of formula M is selected from the group consisting of:

/>

In a further preferred embodiment, each of R _M1 and R _M2 independently represents a linear alkyl group containing 1 to 8 (e.g., 1,2, 3, 4, 5, 6, 7, or 8) carbon atoms, a linear alkenyl group containing 2 to 8 (e.g., 2, 3, 4, 5, 6, 7, or 8) carbon atoms, or a linear alkoxy group containing 1 to 8 (e.g., 1,2, 3, 4, 5, 6, 7, or 8) carbon atoms.

In a further preferred embodiment, the compound of formula M is selected from any one or a combination of at least two of a compound of formula M-1, a compound of formula M-2, a compound of formula M-6, a compound of formula M-12, a compound of formula M-13, a compound of formula M-15, a compound of formula M-16, a compound of formula M-19, a compound of formula M-21, a compound of formula M-24, a compound of formula M-26, a compound of formula M-28, a compound of formula M-29, a compound of formula M-30, a compound of formula M-31, or a compound of formula M-32. Still more preferred is any one or a combination of at least two of a compound of formula M-1, a compound of formula M-12, a compound of formula M-15, a compound of formula M-19, a compound of formula M-21, a compound of formula M-26, a compound of formula M-28, or a compound of formula M-30.

In a preferred embodiment, the liquid crystal composition comprises at least one compound of formula M-1 and/or a compound of formula M-12 in order to obtain a higher average elastic constant, higher transmittance, better vertical dielectric to dielectric ratio and longer low temperature storage time; further preferably, the liquid crystal composition comprises at least one compound of formula M-1 and/or a compound of formula M-12 having an alkenyl group as a terminal group.

In a preferred embodiment, the liquid crystal composition comprises any one or a combination of at least two of the compounds of formula M-26, formula M-28 or formula M-30 in order to obtain a higher average elastic constant, higher transmittance, better vertical dielectric to dielectric ratio and longer low temperature storage time.

In a preferred embodiment, the mass percentage of the compound of formula M is adjusted so that the liquid crystal composition comprising it has a higher average elastic constant, higher transmittance, better ratio of vertical dielectric to dielectric and longer low temperature storage time.

In a preferred embodiment, the mass percentage of the compound of formula M in the liquid crystal composition is between 0.1 and 75%, for example 0.3％、0.5％、0.8％、1％、3％、5％、8％、10％、12％、15％、18％、20％、22％、25％、28％、30％、32％、35％、38％、40％、42％、45％、48％、50％、52％、55％、58％、60％、62％、65％、68％、70％、72％ or 74%, and the specific values between the above values, are not exhaustive, for reasons of space and for reasons of simplicity, the invention further preferably between 5 and 75%.

In a preferred embodiment, the liquid crystal composition further comprises at least one compound of formula D:

Wherein, R _D1 represents-H, halogen, a linear or branched alkyl group containing 1 to 12 (e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12) carbon atoms, a halogen atom, The straight or branched alkyl group having 1 to 12 carbon atoms,/>At least two-CH ₂ -of which one or not adjacent may be independently replaced by-ch=ch-, -c≡c-, -O-, -S-, -CO-O-or-O-CO-, respectively; one or at least two of the foregoing groups-H may each be independently substituted with-F or-Cl.

R _D2 represents halogen, haloalkyl containing 1 to 5 (e.g., 1,2,3,4, or 5) carbon atoms, haloalkoxy containing 1 to 5 (e.g., 1,2,3,4, or 5) carbon atoms, haloalkenyl containing 2 to 5 (e.g., 2,3,4, or 5) carbon atoms, haloalkenoxy containing 2 to 5 (e.g., 2,3,4, or 5) carbon atoms.

Ring(s)And Ring/>Each independently represents/> Said/>At least two-CH ₂ -that are not adjacent to one another or one or at least two of the rings may be replaced by-O-, and a single bond may be replaced by a double bond; said/>In which-ch=may be replaced by-n=and one or at least two-H may be replaced by-F, -Cl, -CN or-CH ₃.

Ring(s)Representation/>

Z _D1 and Z _D2 each independently represent a single bond 、-CH₂CH₂-、-CF₂CF₂-、-CO-O-、-O-CO-、-CH＝CH-、-CF＝CF-、-CH₂O-、-OCH₂-、-CF₂O- or-OCF ₂ -.

N _D1 represents 0, 1 or 2; when n _D1 represents 2, the ringThe same or different, Z _D1 is the same or different.

N _D2 represents 0,1,2 or 3; when n _D2 represents 2 or 3, the ringThe same or different, Z _D2 is the same or different.

In a preferred embodiment, the compound of formula D is selected from the group consisting of:

/>

Wherein R _v and R _w each independently represent-CH ₂ -or-O-.

L_D11、L_D12、L_D13、L_D14、L_D21、L_D22、L_D21'、L_D22'、L_D24、L_D25 And L _D26 each independently represents-H or-F.

L _D23 and L _D23' each independently represent-H or-CH ₃.

V and w each independently represent 0 or 1.

In a preferred embodiment, R _D1 represents a linear alkyl group containing 1 to 8 (e.g., 1,2, 3, 4,5, 6,7, or 8) carbon atoms, a linear alkoxy group containing 1 to 8 (e.g., 1,2, 3, 4,5, 6,7, or 8) carbon atoms, or a linear alkenyl group containing 2 to 8 (e.g., 2,3, 4,5, 6,7, or 8) carbon atoms.

In a preferred embodiment, R _D2 represents-F, -CF ₃ or-OCF ₃.

In a preferred embodiment, the liquid crystal composition comprises at least one compound of formula D-1 in order to obtain a higher average elastic constant, higher transmittance, better vertical dielectric to dielectric ratio and longer low temperature storage time.

In a preferred embodiment, the mass percentage of the compound of formula D in the liquid crystal composition is 0.1-30%, for example, 0.3%, 0.5%, 0.8%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25% or 28%, etc.

In a preferred embodiment, the liquid crystal composition further comprises at least one compound of formula N:

Wherein R _N1 and R _N2 each independently represent a linear or branched alkyl group having 1 to 12 (e.g., 1,2, 3,4,5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms, At least two-CH ₂ -of one or non-adjacent of the straight-chain or branched alkyl groups containing 1 to 12 carbon atoms may each be independently replaced by-ch=ch-, -c≡c-, -O-, -CO-O-or-O-CO-. /(I)

Ring(s)And Ring/>Each independently represents/>The saidOne or at least two of the-CH ₂ -groups may be replaced by-O-groups and one or at least two of the single bonds in the ring may be replaced by double bonds; said/>In which one or at least two-H may be substituted by-F, -Cl or-CN and one or at least two-ch=may be substituted by-n=in the ring.

Z _N1 and Z _N2 each independently represent a single bond 、-CO-O-、-O-CO-、-CH₂O-、-OCH₂-、-CH＝CH-、-C≡C-、-CH₂CH₂-、-CF₂CF₂-、-(CH₂)₄-、-CF₂O- or-OCF ₂ -.

L _N1 and L _N2 each independently represent-H, halogen, unsubstituted or halogenated linear alkyl groups containing 1 to 3 (e.g. 1,2 or 3) carbon atoms.

N _N1 represents 0, 1,2 or 3, n _N2 represents 0 or 1, and 0.ltoreq.n _N1+n_N2.ltoreq.3; when n _N1 represents 2 or 3, the ringThe same or different, Z _N1 is the same or different.

In a preferred embodiment, the compound of formula N is selected from the group consisting of:

/>

In a preferred embodiment, each of R _N1 and R _N2 independently represents a straight-chain alkyl group containing 1 to 8 (e.g., 1, 2, 3, 4, 5, or 6) carbon atoms, an alkoxy group containing 1 to 6 (e.g., 1, 2, 3, 4, 5, or 6) carbon atoms, or an alkenyl group containing 2 to 6 (e.g., 2, 3, 4, 5, or 6) carbon atoms.

In a preferred embodiment, the compound of formula N is selected from any one or a combination of at least two of the compounds of formula N-2, formula N-3, formula N-5, formula N-6, formula N-10, formula N-12, formula N-13, formula N-14 or formula N-26.

In a preferred embodiment, the liquid crystal composition further comprises at least one compound of formula B:

wherein R _B1 and R _B2 each independently represent a linear or branched alkyl group having 1 to 12 (e.g., 1,2,3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms, M _B represents an integer from 0 to 6, which may be, for example, 0, 1,2, 3, 4, 5 or 6; at least two-CH ₂ -of one or non-adjacent of the foregoing groups may each be independently replaced by-ch=ch-, -c≡c-, -S-, -CO-O-or-O-CO-, and one or at least two-H may each be independently replaced by-F or-Cl; r _B1 and R _B2 are each linked to O in formula B via a C atom.

Ring(s)And Ring/>Each independently represents/> Said/>At least two-CH ₂ -that are not adjacent to one another or one or at least two of the rings may be replaced by-O-, and a single bond may be replaced by a double bond; said/>In which-ch=may be replaced by-n=and one or at least two-hs may be replaced by-F, -Cl, -CN, -CH ₃ or-OCH ₃.

Z _B1 and Z _B2 each independently represent a single bond 、-O-、-S-、-CO-O-、-O-CO-、-CH₂O-、-OCH₂-、-CH＝CH-、-C≡C-、-CH₂CH₂-、-CF₂CF₂-、-(CH₂)₄-、-CF₂O- or-OCF ₂ -.

Y _B1 and Y _B2 each independently represent-H, halogen, unsubstituted or halogenated linear alkyl groups containing 1 to 3 (e.g. 1,2 or 3) carbon atoms, unsubstituted or halogenated linear alkoxy groups containing 1 to 3 (e.g. 1,2 or 3) carbon atoms.

X _B represents-O-; -S-, -CO-, -CF ₂ -, -NH-or-NF-.

N _B1 and n _B2 each independently represent 0,1 or 2; when n _B1 represents 2, the ringIdentical or different, Z _B1 identical or different, when n _B2 denotes 2, ring/>The same or different, Z _B2 is the same or different.

In a preferred embodiment, the compound of formula B is selected from the group consisting of:

Wherein, Y _B3 and Y _B4 each independently represent-H, -F-Cl, -CN, -CH ₃ or-OCH ₃.

In a preferred embodiment, R _B1 and R _B2 each independently represent a linear alkyl group containing 1 to 6 (e.g., 1,2,3,4,5, or 6) carbon atoms,M _B represents an integer from 0 to 4, which may be, for example, 0,1, 2,3 or 4; preferably, m _B represents 0.

In a preferred embodiment, X _B represents-O-or-S-.

In a preferred embodiment, the liquid crystal composition comprises at least one compound of formula B-1 in order to obtain a higher average elastic constant, higher transmittance, better vertical dielectric to dielectric ratio and longer low temperature storage time.

In a preferred embodiment, the mass percentage of the compound of formula B is preferably adjusted so that the liquid crystal composition comprising it has a higher average elastic constant, higher transmittance, better ratio of vertical dielectric to dielectric and longer low temperature storage time.

In a preferred embodiment, the mass percentage of the compound of formula B in the liquid crystal composition is 0.1-30%, for example 0.3%, 0.5%, 0.8%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25% or 28%, and the specific point values between the above-mentioned point values, are limited in space and for the sake of brevity, the invention is not exhaustive of the specific point values comprised in the range.

In addition to the above-mentioned compounds, the liquid crystal composition of the present invention may contain a usual nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, dopant, antioxidant, ultraviolet absorber, infrared absorber, polymerizable monomer, light stabilizer, or the like.

Possible dopants preferably added to the liquid crystal composition of the present invention are shown below:

/>

in some embodiments of the invention, the dopant comprises 0% to 5% by weight of the liquid crystal composition; preferably, the dopant comprises 0.01% to 1% by weight of the liquid crystal composition.

The additives such as antioxidants and light stabilizers used in the liquid crystal composition of the present invention are preferably the following:

/>

Wherein n represents a positive integer of 1 to 12.

Preferably, the light stabilizer is selected from the group consisting of the light stabilizers shown below:

In some embodiments of the invention, the light stabilizer comprises 0% to 5% by weight of the total weight of the liquid crystal composition; preferably, the light stabilizer comprises 0.01% -1% of the total weight of the liquid crystal composition; more preferably, the light stabilizer comprises 0.01% to 0.1% by weight of the total weight of the liquid crystal composition.

In a second aspect, the present invention provides a liquid crystal display device comprising a liquid crystal composition according to the first aspect.

Compared with the prior art, the invention has the following beneficial effects:

The liquid crystal composition provided by the invention comprises at least one dibenzo derivative of the formula I, and by combining and cooperating with a positive compound, the liquid crystal composition has a larger K _ave value, a higher penetration rate, a better ratio of vertical dielectric to dielectric and a longer low-temperature storage time under the condition of maintaining proper optical anisotropy, proper clearing point and proper dielectric anisotropy, is a liquid crystal material with better overall performance, is suitable for various display modes of high-performance liquid crystal display devices such as IPS, NFFS and the like, and has wide application prospect.

Detailed Description

The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

For convenience of expression, in the following examples and comparative examples, the group structures of the respective components in the liquid crystal composition are represented by codes listed in table 1:

TABLE 1

/>

Take as an example a compound of the formula:

The structural formula is represented by the codes listed in table 1, and can be expressed as follows: nCGPUF; wherein C represents a1, 4-cyclohexylene group, G represents a 2-fluoro-1, 4-phenylene group, P represents a1, 4-phenylene group, U represents a 2, 6-difluoro-1, 4-phenylene group, F represents a fluoro substituent, n represents the number of carbon atoms of the left-end alkyl group, for example, n is "3", that is, it means that the alkyl group is n-propyl.

The shorthand numbers of test items in the following examples and comparative examples are as follows:

Cp clearing point (nematic phase-isotropic phase transition temperature, DEG C)

Delta n optical anisotropy (589 nm,25 ℃ C.)

Dielectric anisotropy of delta epsilon (1 kHz,25 ℃ C.)

Dielectric constant of ε _⊥ perpendicular to the molecular axis (1 kHz,25 ℃ C.)

Dielectric constant of ε _∥ parallel to molecular axis (1 kHz,25 ℃ C.)

K ₁₁ spring constant of splay (25 ℃ C.)

K ₂₂ torsion spring constant (25 ℃ C.)

K ₃₃ bending spring constant (25 ℃ C.)

K _ave average spring constant (25 ℃ C.)

Tr (%) penetration (%)

LTS (-30 ℃) low temperature storage time (-30 ℃, h)

Wherein,

Cp: measured by an MP70 melting point instrument;

An: using Abbe refractometer under sodium light (589 nm) source, and testing at 25deg.C;

Δε: Δ∈=ε _∥-ε_⊥, where ε _∥ is the dielectric constant parallel to the molecular axis, ε _⊥ is the dielectric constant perpendicular to the molecular axis, test conditions: 25 ℃ and 1kHz, the test box is TN type, and the thickness of the box is 7 mu m;

K ₁₁、K₂₂ and K ₃₃: testing the C-V curve of the liquid crystal by using an LCR instrument and an antiparallel friction box and calculating; test conditions: 7 μm antiparallel friction cassette, v=0.1 to 20V;

tr: using a DMS 505 photoelectric comprehensive tester to test a V-T curve of the dimming device, taking the maximum value of transmittance on the V-T curve as the transmittance of liquid crystal, wherein a test box is of a positive IPS type, and the thickness of the box is 3.5 mu m;

LTS (-30 ℃): liquid crystal was poured into glass bottles and stored in an incubator at-30℃for a period of time recorded when crystal precipitation was observed.

The compounds used in the examples below may be synthesized by known methods or obtained commercially. These synthetic techniques are conventional and the resulting liquid crystal compositions are tested to meet electronic standards.

Illustratively, the compounds of formula I are prepared by the following synthetic route:

Wherein R ₁、R₂ is a ring Ring/>Z ₁、Z₂、Y₁、Y₂、n₁、n₂ and n have the same defined ranges as in formula I;

x represents-O-or-S-;

U ₁ and U ₂ each independently represent halogen, more preferably chlorine, bromine or iodine.

Taking the following compound of formula I as an example, the specific synthetic method is as follows:

Synthesis example 1

2OB (S) O3O1 (formula I-3) having the following molecular structure:

The preparation method comprises the following steps:

(1)

50g of compound A1-1 (4 '-ethoxy-2', 3 '-trifluoro- [1,1' -biphenyl ] -2-ol), 50.7g of dimethylaminothiocarboxychloride and 37.6g of triethylamine are fully dissolved by 200mL of isododecane, and are subjected to reflux reaction for 18h under the protection of nitrogen at the temperature of 165 ℃, cooled to 25 ℃, filtered, recrystallized by ethanol, filtered by suction, and a filter cake is dried to obtain 35g of compound B1-1 (3-ethoxy-4, 6-difluoro dibenzo [ B, d ] thiophene) as a brown solid with the yield of 71 percent.

(2)

Under the protection of nitrogen, 600mL of tetrahydrofuran is added into a 2L three-necked flask, and 200g of the compound B1-1 obtained in the step (1) is added under stirring. Cooling to-80 ℃, controlling Wen Dijia n-butyllithium 454mL under stirring, and carrying out heat preservation reaction for 2h after the dripping is finished. 214g of triisopropyl borate is added dropwise at the temperature of-80 to-70 ℃, and the temperature is controlled for reaction for 2h after the addition is completed. Adding 10% dilute hydrochloric acid to quench the reaction, distilling, pulping at room temperature by using petroleum ether to obtain an off-white solid C1-1 ((7-ethoxy-4, 6-difluoro dibenzo [ b, d ] thiophene-3-yl) boric acid) accounting for 186.5g, and the yield is 80%.

(3)

600ML of tetrahydrofuran is added into a 2L three-necked flask, 150g of the compound C1-1 obtained in the step (2) is added, 170g of hydrogen peroxide is dropwise added under stirring at a temperature of below 50 ℃, and the reaction is carried out for 4h at room temperature. Sodium bisulphite is added for quenching until no oxidizing property exists, distillation and petroleum ether is pulped at room temperature to obtain brown solid D1-1 (7-ethoxy-4, 6-difluoro dibenzo [ b, D ] thiophene-3-alcohol), which is 102g in total, and the yield is 74.7%.

(4)

200ML of N, N-Dimethylformamide (DMF) is added into a 250mL three-necked flask, 15g of 1-1, 1-chloro-4-methoxypropane, 29.8g of potassium carbonate and 1.8g of potassium iodide obtained in the step (3) are added under stirring, the temperature is raised to 70 ℃, after 5h of reaction, 500mL of water is added into the reaction system for pulping, 300mL of ethanol is added for pulping at room temperature, the mixture is dried at 50 ℃, and after passing through a silica gel column, the mixture is concentrated, petroleum ether is recrystallized, and 33g of white solid of the target product is obtained, and the yield is 89%.

Structural characterization of the target product by Mass Spectrometry (MS): 41 (11%), 45 (55%), 73 (100%), 223 (10%), 252 (21%), 280 (4%), 352 (6%).

Synthesis example 2

C (5) OB (O) O3O1 (formula I-3) has the following molecular structure:

the preparation process differs from synthesis example 1 only in that step (1):

DMF was added to a 500mL three-necked flask under nitrogen protection, 240g K ₂CO₃ and 275g of Compound A1-2 (4 '-cyclopentyloxy-2', 3 '-trifluoro- [1,1' -biphenyl ] -2-ol) were added with stirring, and the temperature was raised to 130℃for reflux reaction for 6h. 400mL of water and 400mL of Ethyl Acetate (EA) were added to the reaction solution, and the aqueous layer was extracted twice with 800mL of EA; the organic layers were combined, dried over anhydrous sodium sulfate with stirring for 30min, and then concentrated to constant weight under reduced pressure at 30℃to give 211g of B1-2 (3-cyclopentyloxy-4, 6-difluorodibenzo [ B, d ] furan) as a white solid in 82% yield.

Compound B1-2 was reacted according to the steps (2) to (4) in Synthesis example 1, whereby the aimed product was obtained as a white solid in 40g, with a yield of 81%.

Structural characterization of the target product by Mass Spectrometry (MS): 41 (11%), 45 (55%), 69 (61%), 73 (100%), 207 (10%), 236 (20%), 304 (3%), 376 (6%).

Liquid crystal compositions were prepared in accordance with the proportions of the respective liquid crystal compositions in the following examples. The liquid crystal composition is prepared by mixing the components according to a prescribed proportion by a conventional method in the art, such as heating, ultrasonic wave, suspension and the like.

Example 1

The components and performance parameters of the liquid crystal composition are shown in Table 2:

TABLE 2

Comparative example 1

The components and performance parameters of the liquid crystal composition are shown in Table 3:

TABLE 3 Table 3

From a comparison of comparative example 1 and example 1, it is understood that the liquid crystal composition of the present invention also has a larger K _ave value, a higher transmittance, a larger ratio of vertical dielectric to dielectric, and a longer low-temperature storage time while maintaining an appropriate optical anisotropy, an appropriate clearing point, and an appropriate dielectric anisotropy.

Example 2

The components and performance parameters of the liquid crystal composition are shown in Table 4:

TABLE 4 Table 4

Example 3

The components and performance parameters of the liquid crystal composition are shown in Table 5:

TABLE 5

Example 4

The components and performance parameters of the liquid crystal composition are shown in Table 6:

TABLE 6

Example 5

The components and performance parameters of the liquid crystal composition are shown in Table 7:

TABLE 7

Example 6

The components and performance parameters of the liquid crystal composition are shown in Table 8:

TABLE 8

Example 7

The components and performance parameters of the liquid crystal composition are shown in Table 9:

TABLE 9

According to the embodiment, through the mutual cooperation of the dibenzo derivative of the formula I and the compound of the formula II and/or the compound of the formula III, the positive liquid crystal composition has higher average elastic constant (K _ave is more than 12.1), higher transmittance, tr is more than or equal to 15.8 percent, better ratio of vertical dielectric to dielectric (epsilon _⊥/delta epsilon is more than 1.4) and longer low-temperature storage time under the condition of maintaining proper optical anisotropy, proper clearing point and proper dielectric anisotropy, and can be stably stored for more than 10 days at-30 ℃, so that the liquid crystal display device containing the liquid crystal composition has better contrast, better transmittance and better low-temperature storage stability under the condition of maintaining proper threshold voltage, and the overall performance of the liquid crystal device is remarkably improved.

The applicant states that the present invention is illustrated by the above examples as a liquid crystal composition comprising a dibenzo derivative of the present invention and its use, but the present invention is not limited to the above examples, i.e. it is not meant that the present invention must be practiced in dependence upon the above examples. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.

Claims

1. A liquid crystal composition comprising a dibenzo derivative, said liquid crystal composition comprising:

At least one compound of formula I:

At least one compound of formula II and at least one compound of formula III:

And at least one compound of formula M:

Wherein R ₁ represents a linear alkyl group having 1 to 6 carbon atoms, a linear alkoxy group having 1 to 6 carbon atoms, a linear alkylthio group having 1 to 6 carbon atoms,

R ₂ represents a linear or branched alkyl group having 1 to 6 carbon atoms, one or at least two-H of which may each independently be substituted by halogen;

r _A1 and R _A2 each independently represent a linear or branched alkyl group having 1 to 12 carbon atoms, At least two-CH ₂ -of one or non-adjacent of the linear or branched alkyl groups containing 1 to 12 carbon atoms may each independently be replaced by-ch=ch-or-O-; one or at least two of the foregoing groups, -H, may each independently be substituted with-F or-Cl;

R _M1 and R _M2 each independently represent a linear or branched alkyl group having 1 to 12 carbon atoms, At least two-CH ₂ -of one or non-adjacent of the linear or branched alkyl groups containing 1 to 12 carbon atoms may each independently be replaced by-ch=ch-or-O-;

Ring(s) And Ring/>Each independently represents/> Said/>At least two-CH ₂ -that are not adjacent to one another or one or at least two of the rings may be replaced by-O-, and a single bond may be replaced by a double bond; said/> At least two-H of (c) may be substituted by halogen or methyl;

Ring(s) Ring/>Ring/>And Ring/>Each independently representsSaid/> The single bond in one or not adjacent at least two rings may be replaced by a double bond; the saidWherein one or at least two of-H may be substituted with-F, -Cl or-CN;

Ring(s) Ring/>And Ring/>Each independently represents/> Said/>At least two-CH ₂ -that are not adjacent to one another or one or at least two of the rings may be replaced by-O-, and a single bond may be replaced by a double bond; the saidAt most one-H of (c) may be substituted by halogen;

Z ₁ and Z ₂ each independently represent a single bond 、-CO-O-、-O-CO-、-CH₂O-、-OCH₂-、-CH＝CH-、-CF＝CF-、-CH₂CH₂-、-CF₂CF₂-、-CF₂O- or-OCF ₂ -;

Z _A11、Z_A21 and Z _A22 each independently represent a single bond, -CO-O-, -O-CO-, -CH ₂O-、-OCH₂-、-CH₂CH₂ -, or-CF ₂CF₂ -;

Z _M1 and Z _M2 each independently represent a single bond, -CO-O-, -O-CO-, -CH ₂O-、-OCH₂-、-C≡C-、-CH＝CH-、-CH₂CH₂ -, or- (CH ₂)₄ -;

Y ₁ and Y ₂ represent-F;

X represents-O-or-S;

l _A11、L_A12、L_A21 and L _A22 each independently represent-H or halogen;

l _A13 represents-H or a linear alkyl group having 1 to 3 carbon atoms;

X _A1 and X _A2 each independently represent halogen, haloalkyl having 1 to 5 carbon atoms, haloalkoxy having 1 to 5 carbon atoms or haloalkenyl having 2 to 5 carbon atoms;

n represents an integer of 1 to 6;

n ₁ and n ₂ each represent 0;

n _A11 and n _A2 each independently represent 0,1,2 or 3; when n _A11 represents 2 or 3, the ring Identical or different, Z _A11 identical or different; when n _A2 represents 2 or 3, ring/>Identical or different, Z _A21 identical or different;

n _A12 represents 1 or 2; when n _A12 represents 2, the ring The same or different;

n _M represents 0, 1 or 2; when n _M represents 2, the ring Identical or different, Z _M2 identical or different;

The liquid crystal composition comprises, by mass, 0.1-20% of a compound of formula I, 0.1-20% of a compound of formula II, 1-30% of a compound of formula III and 50-70% of a compound of formula M.

2. The liquid crystal composition according to claim 1, wherein the compound of formula I is selected from the group consisting of:

Wherein X represents-O-or-S-.

3. The liquid crystal composition according to claim 1, wherein the compound of formula II is selected from the group consisting of:

And

Wherein L _A11、L_A12、L_A14、L_A15 and L _A16 each independently represent-H or-F;

l _A13 represents-H or-CH ₃;

X _A1 represents-F, -CF ₃ or-OCF ₃.

4. A liquid crystal composition according to claim 3, characterized in that it comprises at least one compound of formula II-6.

5. The liquid crystal composition according to claim 1, wherein the compound of formula III is selected from the group consisting of:

And

Wherein L _A21、L_A22、L_A23、L_A24 and L _A25 each independently represent-H or-F;

X _A2 represents-F, -CF ₃、-OCF₃ or-CH ₂CH₂CH＝CF₂.

6. The liquid crystal composition according to claim 1, wherein the compound of formula M is selected from the group consisting of:

7. The liquid crystal composition of claim 1, further comprising at least one compound of formula B:

Wherein R _B1 and R _B2 each independently represent a linear or branched alkyl group having 1 to 12 carbon atoms, M _B represents an integer of 0 to 6; at least two-CH ₂ -of one or non-adjacent of the foregoing groups may each be independently replaced by-ch=ch-, -c≡c-, -S-, -CO-O-or-O-CO-, and one or at least two-H may each be independently replaced by-F or-Cl;

Ring(s) And Ring/>Each independently represents/> Said/>At least two-CH ₂ -that are not adjacent to one another or one or at least two of the rings may be replaced by-O-, and a single bond may be replaced by a double bond; said/> In which-ch=may be replaced by-n=and one or at least two-H may be replaced by-F, -Cl, -CN, -CH ₃ or-OCH ₃;

Z _B1 and Z _B2 each independently represent a single bond 、-O-、-S-、-CO-O-、-O-CO-、-CH₂O-、-OCH₂-、-CH＝CH-、-C≡C-、-CH₂CH₂-、-CF₂CF₂-、-(CH₂)₄-、-CF₂O- or-OCF ₂ -;

Y _B1 and Y _B2 each independently represent-H, halogen, unsubstituted or halogenated linear alkyl groups having 1 to 3 carbon atoms, unsubstituted or halogenated linear alkoxy groups having 1 to 3 carbon atoms;

X _B represents-O-; -S-, -CO-, -CF ₂ -, -NH-, or-NF-;

n _B1 and n _B2 each independently represent 0,1 or 2; when n _B1 represents 2, the ring Identical or different, Z _B1 identical or different, when n _B2 denotes 2, ring/>The same or different, Z _B2 is the same or different. /(I)

8. The liquid crystal composition according to claim 7, wherein the mass percentage of the compound of formula B in the liquid crystal composition is 0.1 to 30%.

9. A liquid crystal display device comprising the liquid crystal composition according to any one of claims 1 to 8.