CN115477951B

CN115477951B - Liquid crystal composition and liquid crystal display device

Info

Publication number: CN115477951B
Application number: CN202110598544.2A
Authority: CN
Inventors: 孙成龙; 杨亚非; 贺笛; 王盼盼; 丁文全; 徐爽
Original assignee: Jiangsu Hecheng Display Technology Co Ltd
Current assignee: Jiangsu Hecheng Display Technology Co Ltd
Priority date: 2021-05-31
Filing date: 2021-05-31
Publication date: 2024-07-02
Anticipated expiration: 2041-05-31
Also published as: CN115477951A

Abstract

The invention provides a liquid crystal composition and a liquid crystal display device, wherein the liquid crystal composition comprises a combination of a first component and a second component; the first component comprises at least one polymerizable compound of the formula I, and the second component comprises 10-50% by mass of a compound of the formula II and 20-50% by mass of a compound of the formula III. The liquid crystal composition has better polymerization speed and faster angulation speed, lower surface roughness after polymerization, better voltage retention rate, less residue, good pretilt angle stability and low-temperature stability, excellent comprehensive performance and improved problems of broken bright spots, image viscosity, uneven display and the like in the conventional PSA type liquid crystal display device. The liquid crystal composition can provide a PSA type liquid crystal display device with more excellent quality, and has very broad application prospect.

Description

Liquid crystal composition and liquid crystal display device

Technical Field

The invention belongs to the technical field of liquid crystal materials, and particularly relates to a liquid crystal composition and a liquid crystal display device.

Background

Liquid crystal displays (Liquid CRYSTAL DISPLAY, LCD) have been rapidly developed due to their small size, light weight, low power consumption and excellent display quality, and have been widely used in particular in portable electronic information products. Depending on the type of display mode, liquid crystal displays can be classified into types of PC (PHASE CHANGE ), TN (TWIST NEMATIC, twisted nematic), STN (super TWISTED NEMATIC ), ECB (ELECTRICALLY CONTROLLED BIREFRINGENCE, electrically controlled birefringence), OCB (optically compensated bend ), IPS (in-PLANE SWITCHING, in-plane switching), FFS (FRINGE FIELD SWITCHING ), VA (VERTICAL ALIGNMENT, homeotropic alignment), and PSA (polymer stable alignment ), etc.

The PSA-type liquid crystal display mode is to add a small amount (more typically < 1wt%, such as 0.3 wt%) of one or more polymerizable compounds to the liquid crystal composition, and can ensure that the liquid crystal molecules are polymerized or crosslinked in situ (typically by UV photopolymerization) in a state having an initial alignment, with or without applying a voltage between electrodes, after the liquid crystal composition is filled into a liquid crystal cell, thereby fixing the alignment of the liquid crystal molecules. With the continuous development of the PSA-type liquid crystal display element, it is applied to various conventional liquid crystal display devices such as known PSA-VA, PSA-OCB, PSA-IPS, PSA-FFS and PSA-TN type liquid crystal displays. In a PSA-type liquid crystal display, a liquid crystal composition containing a polymerizable compound is located between two substrates, each of which is provided with an electrode structure, or two electrode structures are disposed on only one of the substrates. In addition, either or both of the substrates may contain an alignment layer disposed on the substrate or electrode structure (if present) to induce initial alignment of the liquid crystal composition. As with conventional liquid crystal displays, PSA-type liquid crystal displays can operate as either active matrix displays or passive matrix displays. In the case of an active matrix display, the individual pixels are addressed by integrated non-linear active elements (e.g. transistors); whereas in the case of passive matrix displays the individual pixels are usually addressed according to multiplexing methods known in the art.

After filling the liquid crystal composition into the display device, the polymerizable compound contained in the liquid crystal composition is usually polymerized or crosslinked in situ by UV photopolymerization, which is achieved by exposing the liquid crystal composition to UV radiation, and preferably simultaneously applying a voltage to the electrode structure. As a result of UV exposure, the polymerized or crosslinked polymerizable compounds phase separate from other compounds in the liquid crystal composition and form a polymer layer on the substrate surface where they cause a pre-tilt angle of the liquid crystal molecules with respect to the substrate. For liquid crystal displays of the PSA-VA, PSA-OCB, PSA-FFS and PSA-TN types, the polymerization of the polymerizable compound is preferably carried out with the application of a voltage; for the PSA-IPS type liquid crystal display, voltage may be applied or not applied, and it is preferable that voltage is not applied.

In general, in a method for producing a PSA-type liquid crystal display, UV photopolymerization is achieved by the following two steps:

In a first step (hereinafter referred to as "UV1 step"), the liquid crystal composition is exposed to UV radiation emitted by a radiation source (hereinafter referred to as "light source") while a voltage is applied to the electrode structure to create a pretilt angle. The more preferred polymerizable compound should produce a smaller pretilt angle in the same time or the same pretilt angle in a shorter UV1 irradiation time (i.e., faster angulation speed) to improve production efficiency, shorten tact time at mass production, reduce cost; meanwhile, the faster the angulation speed of the polymerizable compound is, the more favorable the polymerizable compound is to realize complete polymerization, thereby reducing polymer residues. To increase the angular velocity, it is preferred to use UV1 radiation of shorter wavelength; whereas in order to increase the voltage holding ratio (Voltage Holding Ratio, VHR) a longer wavelength UV1 radiation is preferably used. Therefore, it is often difficult to combine a faster angulation speed with a higher voltage holding ratio.

In the second step (hereinafter referred to as "UV2 step"), the liquid crystal composition is exposed to UV radiation without applying a voltage to the electrode structure to ensure that any residual polymerizable compound that does not polymerize during the UV1 step is able to polymerize thoroughly. It is desirable that the pre-tilt angle is changed as little as possible after the UV2 step to reduce the possibility of uneven display of the PSA type lcd due to UV process non-uniformity (e.g., uneven external conditions such as light, heat, stress, etc.). At the same time, the UV radiation intensity in the UV2 step should be reduced to avoid or reduce negative effects (such as reduced reliability or image sticking).

In the prior art, it has been gradually discovered that not all liquid crystal compositions can be perfectly matched with polymerizable compounds, and after UV1 and UV2 treatment, there may be problems of incomplete polymerization of residual polymerizable compounds, slow pre-tilt angle angulation speed, etc. Meanwhile, poor intersolubility of the liquid crystal composition and the polymerizable compound can lead to poor rigidity of a polymer network formed after the polymerizable compound is polymerized, so that when the PSA type liquid crystal display element continuously displays the same pattern for a long time, the structure of the polymer network is changed, and then the pretilt angle of liquid crystal molecules is changed, so that poor display occurs.

In addition, with the development of display technology, the requirements on the display quality of the LCD in the industry are more strict, especially in the TV industry, the TV size is generally increased, the LCD generation line is also increased, and the manufacturing process difficulty of the large-size LCD panel is also obviously increased. Therefore, how to secure and improve the display quality is a problem to be solved. In order to solve this problem, besides the continuous optimization of the panel manufacturing process, the continuous development of liquid crystal materials is one of the effective means, and especially for PSA-type liquid crystal displays, the selection of liquid crystal compositions to be used in combination with polymerizable compounds is a research hotspot.

Currently, common problems in the production of PSA-type liquid crystal displays include the residue or removal of polymerizable compounds, the stability of pretilt angles, and the like. In the PSA type liquid crystal display, if the polymer particles are too large and the polymer particles are not uniform in size during the UV1 and UV2 processes, the polymer is unevenly distributed, thereby causing a problem of "broken bright spots" in the PSA type liquid crystal display. In addition, after the polymerizable compound is polymerized by applying UV1 radiation and UV2 radiation to generate a pretilt angle, a small amount of unreacted polymerizable compound may be polymerized in an uncontrollable manner after the display is manufactured, thereby affecting the quality of the display. For example, residual polymerizable compounds polymerize under the influence of UV light or backlighting from the environment, the pretilt angle changes and the transmissivity changes over multiple addressing cycles in the on display area, and the pretilt angle and transmissivity remain unchanged in the off display area, creating an "image sticking" effect. It is therefore desirable that during the production of PSA-type liquid crystal displays, the polymerizable compounds polymerize as completely as possible, and that the residual polymerizable compounds are able to react in a controlled manner, the faster the polymerization speed, the more advantageous it is to achieve this desire. Furthermore, it is desirable that the change in the pre-tilt angle is small after a plurality of address periods.

In addition, the polymerizable compounds of the prior art generally have a high melting point and have limited solubility in many of the commonly used liquid crystal compositions available, and often precipitate from the liquid crystal composition. Meanwhile, the polymerizable compound has a possibility of self-polymerization, further deteriorating its solubility in the liquid crystal composition. Therefore, it is generally necessary to introduce a liquid crystal composition in which a polymerizable compound is dissolved at a low temperature to reduce the risk of self-polymerization of the polymerizable compound, which places higher demands on the solubility of the polymerizable compound in the liquid crystal composition, especially at a low temperature.

Therefore, development of a liquid crystal composition with controllable polymerization process, high angulation speed, good pretilt angle stability and excellent solubility is an important research point in the field.

Disclosure of Invention

In view of the shortcomings of the prior art, the invention aims to provide a liquid crystal composition and a liquid crystal display device, wherein the liquid crystal composition has higher polymerization speed and angularity, better pretilt angle stability and low-temperature stability, lower residual quantity after polymerization and smaller surface roughness of a polymer layer, so that the PSA type liquid crystal display device with more excellent quality can be provided.

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 combination of a first component and a second component;

the first component comprises at least one polymerizable compound of formula I:

The second component comprises 10-50% of a compound of formula II:

And

20-50% By mass of a compound of formula III:

Wherein ,Y₁、Y₂、Y₃、Y₄、Y₅、Y₆、Y₇、Y₈、Y₉、Y₁₀、Y₁₁ and Y ₁₂ each independently represent-H, halogen, -CN, -Sp ₃-P₃, unsubstituted or halogenated linear or branched alkyl groups containing 1 to 5 (e.g., 1,2, 3,4, or 5) carbon atoms, unsubstituted or halogenated linear or branched alkoxy groups containing 1 to 4 (e.g., 1,2, 3, or 4) carbon atoms, and comprise at least two-OCH ₃.

The two-OCH ₃ are connected with adjacent benzene rings, and the difference between m values of the corresponding Y _m is 2, 4 or 6; m represents an integer of 1 to 12, for example m represents 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12.

In the invention, at least two of the Y ₁-Y₁₂'s represent-OCH ₃, namely-OCH ₃'s can be 2,3, 4 or 5, etc.; wherein, the connection position of two-OCH ₃ meets the limitation that the connection position is connected with the adjacent benzene rings and the difference of m values of the corresponding Y _m is 2, 4 or 6.

In the present invention, the "adjacent benzene ring" means two benzene rings connected by a single bond, that is, the benzene ring where Y ₁ is located and the benzene ring where Y ₅ is located are adjacent benzene rings, and the benzene ring where Y ₅ is located and the benzene ring where Y ₉ is located are adjacent benzene rings.

In the present invention, the combination satisfying "the two-OCH ₃ are connected to adjacent benzene rings, and the difference between m values of the corresponding Y _m is 2, 4, or 6" illustratively includes: y ₁ and Y ₅、Y₁ and Y ₇、Y₂ and Y ₆、Y₂ and Y ₈、Y₃ and Y ₇、Y₃ and Y ₅、Y₄ and Y ₈、Y₄ and Y ₆、Y₅ and Y ₉、Y₅ and Y ₁₁、Y₆ and Y ₁₀、Y₆ and Y ₁₂、Y₇ and Y ₁₁、Y₇ and Y ₉、Y₈ and Y ₁₂、Y₈ and Y ₁₀.

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

P ₁、P₂ and P ₃ each independently represent a polymerizable group.

Sp ₁、Sp₂ and Sp ₃ each independently represent a single bond or a spacer group.

R ₁、R₂、R₃ and R ₄ each independently represent 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, 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-, -S-, -CO-O-or-O-CO-.

N represents 0 or 1.

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 exampleA short straight line to the left of the CN,Short straight lines on both sides.

In the liquid crystal composition provided by the invention, the first component containing the polymerizable compound with the structure shown in the formula I and the second component containing the compounds with the structures shown in the formulas II and III are mutually cooperated, so that the liquid crystal composition has better polymerization speed and faster angulation speed, the formed bump (bump) after polymerization is smaller, the surface roughness is lower, the voltage retention rate is better, the residue is less, the pretilt angle stability and the low-temperature intersolubility are good, and the liquid crystal composition has excellent comprehensive performance. The liquid crystal composition can provide a PSA type liquid crystal display device with more excellent quality, and has very broad application prospect.

In a preferred embodiment, the content of the compound of formula II is preferably adjusted so that the liquid-crystalline composition comprising it has a faster angular velocity, better pre-tilt angle stability, lower polymer residues, higher VHR and longer low-temperature storage time.

The mass percentage of the compound of formula II in the second component is 10-50%, for example 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% or 48%, and the specific values between the above values are limited in space and for the sake of brevity, the invention is not intended to be exhaustive of the specific values comprised in the range.

In a preferred embodiment, the content of the compound of formula III is preferably adjusted so that the liquid-crystalline composition comprising it has a faster angular velocity, better pre-tilt angle stability, lower polymer residues, higher VHR and longer low-temperature storage time.

The mass percentage of the compound of formula III in the second component is 20-50%, for example 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% or 48%, and the specific values between the above values, are for brevity and for simplicity, the invention is not intended to be exhaustive of the specific values included in the range.

In a preferred embodiment, Y₁、Y₂、Y₃、Y₄、Y₅、Y₆、Y₇、Y₈、Y₉、Y₁₀、Y₁₁ and Y ₁₂ each independently represent-H, -F, -Cl, -OCH ₃、-CH₃ or-Sp ₃-P₃, and comprises at least two-OCH ₃.

In a preferred technical scheme, Y _m corresponding to the two-OCHs ₃ is selected from any one of the following combinations: y ₁ and Y ₅、Y₂ and Y ₆、Y₃ and Y ₇、Y₄ and Y ₈、Y₅ and Y ₉、Y₆ and Y ₁₀、Y₇ and Y ₁₁、Y₈ and Y ₁₂.

In the present invention, the polymerizable group is a group suitable for polymerization (e.g., radical polymerization, ionic bond polymerization, addition polymerization, or polycondensation), or a group suitable for addition or condensation on a polymer main chain. For chain polymerization, polymerizable groups containing-C=C-or-C≡C-are particularly preferred, and for ring-opening polymerization oxetane or epoxy groups are particularly preferred.

In a preferred embodiment, each of said P ₁、P₂ and P ₃ independently represents Or-SH; further preferred is The short straight lines to the right of the above groups all represent access bonds and do not represent methyl groups.

In the present invention, the term "spacer group" is known to the person skilled in the art and is described in the literature (e.g. "Definitions of basic terms relating to low-molar-mass and polymer liquid crystals(IUPAC Recommendations 2001)",Barón et al, pure appl. Chem.,2001, 73 (5), page 888). As used herein, the term "spacer group" means a flexible group that connects a mesogenic group and a polymerizable group in a polymerizable compound. Typical spacer groups are, for example, -(CH₂)_p-、-(CH₂)_p-O-、-(CH₂)_p-O-CO-、-(CH₂)_p-CO-O-、-(CH₂)_p-O-CO-O-、-(CH₂CH₂O)_q-CH₂CH₂-、-(CH₂CH₂S)_q-CH₂CH₂-、-(CH₂CH₂NH)_q-CH₂CH₂-、-CR⁰R¹-(CH₂)_p- or- (SiR ⁰R¹-O)_p -, where p represents an integer from 1 to 12, q represents an integer from 1 to 3, R ⁰ and R ¹ each independently represent-H, a straight-chain or branched alkyl radical having from 1 to 12 carbon atoms, cycloalkyl radicals having from 3 to 12 carbon atoms, particularly preferred spacer groups are -(CH₂)_p-、-(CH₂)_p-O-、-(CH₂)_p-O-CO-、-(CH₂)_p-CO-O-、-(CH₂)_p-O-CO-O- or-CR ⁰R¹-(CH₂)_p -.

In a preferred embodiment, each of Sp ₁、Sp₂ and Sp ₃ independently represents a single bond 、-(CH₂)_p-、-(CH₂)_p-O-、-(CH₂)_p-O-CO-、-(CH₂)_p-CO-O-、-(CH₂)_p-O-CO-O-、-(CH₂CH₂O)_q-CH₂CH₂-、-(CH₂CH₂S)_q-CH₂CH₂-、-(CH₂CH₂NH)_q-CH₂CH₂-、-CR⁰R¹-(CH₂)_p- or- (SiR ⁰R¹-O)_p -.

Wherein R ⁰ and R ¹ each independently represent-H, a straight 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 cycloalkyl group containing 3 to 12 (e.g., 3,4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms.

P 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.

Q represents an integer of 1 to 3, for example 1, 2 or 3.

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

And

Wherein Y ₁'、Y₂'、Y₃'、Y₄'、Y₇'、Y₈'、Y₁₁ 'and Y ₁₂' each independently represent-F, -Cl, -CH ₃ or-Sp ₃-P₃.

In a preferred embodiment, the mass percentage of the polymerizable compound of formula I in the liquid crystal composition is 0.01-2.0%, for example 0.02%, 0.05%, 0.08%, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1.0%, 1.1%, 1.3%, 1.5%, 1.7% or 1.9%, and the specific values between the above values are limited in length and for the sake of brevity, the invention is not exhaustive of the specific values comprised in the range.

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

And

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 alkenyl group containing 2 to 6 (e.g., 2, 3,4, 5, or 6) carbon atoms, or a linear alkoxy group containing 1 to 6 (e.g., 1, 2, 3,4, 5, or 6) carbon atoms.

The linear alkenyl group in the present invention preferably has a structure represented by any one of the formulae (V1) to (V9), and particularly preferably is formula (V1), formula (V2), formula (V8) or formula (V9).

Wherein represents a carbon atom in the bonded ring structure.

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

In a preferred embodiment, the liquid crystal composition comprises at least one compound of formula II-2 in order to obtain a faster angularity, better pre-tilt angle stability, lower polymer residue, higher VHR and longer low temperature storage time.

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

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

And

Wherein R ₃ 'and R ₄' each independently represent a straight chain alkyl group containing 1to 6 (e.g., 1,2,3,4,5, or 6) carbon atoms.

In a preferred embodiment, the second component 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(s)And ringEach independently represents The saidAt 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 _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.

Wherein, when n _M represents 0, the ringAnd ringNot at the same time be

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:

And

In a 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 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, 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-5, a compound of formula M-6, a compound of formula M-11, a compound of formula M-15, a compound of formula M-18, a compound of formula M-25, a compound of formula M-27, or a compound of formula M-28.

In a preferred embodiment, the content of the compound of formula M is preferably adjusted so that the liquid-crystalline composition comprising it has a faster angular velocity, better pre-tilt angle stability, lower polymer residues, higher VHR and longer low-temperature storage time.

In a preferred embodiment, the mass percentage of the compound of formula M in the second component is 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 the specific values between the above values, are not intended to be exhaustive or for reasons of brevity.

In a preferred embodiment, the second component 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-.

Ring(s)And ringEach independently representsThe 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; the said-Ch=in one or at least two rings may be replaced by-n=in one or more rings; one or at least two of the foregoing groups-H may be substituted with-F, -Cl or-CN.

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.

Wherein when N _N1+n_N2 = 1, the compound of formula N does not contain a duplex structure (i.e., does not contain unsubstituted or substitutedStructure).

When n _N1 represents 2 and n _N2 represents 0, the ringNot be of

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:

And

In a preferred embodiment, each of R _N1 and R _N2 independently 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, or a linear 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-1, formula N-2, formula N-3, formula N-5, formula N-6, formula N-10, formula N-12, formula N-21 or formula N-23.

In a preferred embodiment, the second component comprises at least one compound of formula N-2 and/or a compound of formula N-5 in order to obtain a faster angulation speed, better pre-tilt angle stability, lower polymer residue, higher VHR and longer low temperature storage time.

In a preferred embodiment, the second component comprises at least one compound of formula N-3 and/or a compound of formula N-6 in order to obtain a faster angulation speed, better pre-tilt angle stability, lower polymer residue, higher VHR and longer low temperature storage time.

In a preferred embodiment, the content of the compound of formula N is preferably adjusted so that the liquid-crystalline composition comprising it has a faster angular velocity, better pre-tilt angle stability, lower polymer residues, higher VHR and longer low-temperature storage time.

In a preferred embodiment, the mass percentage of the compound of formula N in the second component is 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 the specific values between the above values, are not intended to be exhaustive or for the sake of brevity.

In a preferred embodiment, the second component further comprises at least one compound of formula B:

Wherein R _B1 and R _B2 each independently represent-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; 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-, -S-, -CO-O-or-O-CO-; one or at least two of the foregoing groups, -H, may each independently be substituted with-F or-Cl; r _B1 and R _B2 are each linked to the ring structure via a C atom.

Ring(s)And ringEach independently represents The saidAt 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 said -Ch=in one or at least two rings may be replaced by-n=in one or more rings; one or at least two of the foregoing groups-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 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, a ringThe 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:

And

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

In a preferred embodiment, the mass percentage of the compound of formula B in the second component 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 second component further comprises at least one compound of formula A-1 and/or formula A-2;

Wherein R _A1 and R _A2 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 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 be independently substituted with-F or-Cl.

Ring(s)Ring(s)Ring(s)And ringEach independently representsThe 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 said-Ch=in one or at least two rings may be replaced by-n=in one or more rings; one or at least two of the foregoing groups-H may be substituted with-F, -Cl or-CN.

Z _A11、Z_A21 and Z _A22 each independently represent a single bond 、-CH₂CH₂-、-CF₂CF₂-、-CO-O-、-O-CO-、-O-CO-O-、-CH＝CH-、-CF＝CF-、-CH₂O- or-OCH ₂ -.

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, haloalkenoxy containing 2 to 5 (e.g., 2, 3, 4, or 5) carbon atoms.

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, the ringThe same or different, Z _A21 is the same or different.

N _A12 represents 1 or2; when n _A12 represents 2, the ringThe same or different.

In a preferred embodiment, the compound of formula A-1 is selected from the group consisting of:

And

Wherein R _A1 represents a linear or branched alkyl group containing 1 to 8 (e.g., 1, 2, 3, 4, 5, 6, 7, or 8) carbon atoms; at least two-CH ₂ -of one or non-adjacent of said linear or branched alkyl groups containing 1 to 8 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 be independently substituted with-F or-Cl.

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

L _A11、L_A12、L_A11'、L_A12'、L_A14、L_A15 and L _A16 each independently represent-H or-F.

L _A13 and L _A13' each independently represent-H or-CH ₃.

X _A1 represents-F, -CF ₃、-OCF₃ or-CH ₂CH₂CH＝CF₂.

V and w each independently represent 0 or 1.

In a preferred embodiment, the mass percentage of the compound of formula a-1 in the second component is 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%, etc.

In a preferred embodiment, the compound of formula A-2 is selected from the group consisting of:

And

Wherein R _A2 represents a linear or branched alkyl group containing 1 to 8 (e.g., 1, 2, 3, 4, 5, 6, 7, or 8) carbon atoms; at least two-CH ₂ -of one or non-adjacent of said linear or branched alkyl groups containing 1 to 8 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 be independently substituted with-F or-Cl.

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 preferred embodiment, the mass percentage of the compound of formula a-2 in the second component is 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%, etc.

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:

And

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% by weight 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.

The liquid crystal composition of the present invention can be polymerized even in the absence of a polymerization initiator, but may further contain a polymerization initiator for the purpose of promoting the polymerization. Examples of the polymerization initiator include benzoin ethers, benzophenones, acetophenones, benzil ketals, and acylphosphine oxides.

The liquid crystal composition of the present invention can be imparted with liquid crystal aligning ability by polymerization of a polymerizable compound in the liquid crystal composition, and the amount of transmitted light in a liquid crystal display device is controlled by utilizing birefringence in the liquid crystal composition.

In order to accelerate the polymerization rate, the polymerizable compound is preferably polymerized by irradiation with an active energy ray such as ultraviolet rays or electron beams. When ultraviolet rays are used, a polarized light source may be used, or an unpolarized light source may be used. In addition, when polymerization is performed in a state in which the liquid crystal composition is sandwiched between two substrates, at least the substrate on the irradiation surface side must have appropriate transparency with respect to the active energy rays. Further, it is also possible to polymerize only a specific portion by using a mask at the time of light irradiation, then change the orientation state of the unpolymerized portion by changing the conditions such as an electric field, a magnetic field, or a temperature, and further irradiate an active energy ray to polymerize. In particular, when ultraviolet exposure is performed, it is preferable to perform ultraviolet exposure while applying a voltage to the liquid crystal composition.

The temperature at the time of irradiation with active energy rays such as ultraviolet rays or electron beams is preferably in a temperature range in which the liquid crystal state of the liquid crystal composition of the present invention is maintained. The polymerization is preferably carried out at a temperature close to room temperature (i.e., 15-35 ℃). As the lamp that generates ultraviolet rays, a metal halide lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, or the like can be used. The wavelength of the irradiated ultraviolet light is preferably ultraviolet light having a wavelength outside the absorption wavelength region of the liquid crystal composition, and is preferably used by blocking ultraviolet light if necessary. The intensity of the irradiated ultraviolet rays is preferably 0.1 to 50mW/cm ². When the ultraviolet rays are irradiated, the intensity thereof may be changed, and the time for irradiating the ultraviolet rays is appropriately selected according to the intensity of the irradiated ultraviolet rays, preferably 10 to 600 seconds.

As used herein, the terms "tilt" and "tilt angle" will be understood as the tilt alignment of liquid crystal molecules with respect to the cell surface in a liquid crystal display device (in the present invention, a PSA-type liquid crystal display device is preferred). The tilt angle represents the average angle (< 90 °) formed between the longitudinal molecular axis of the liquid crystal molecules (liquid crystal director loss) and the surface of the outer plate of the liquid crystal cell. A low value of the tilt angle (i.e., a large angle deviating from 90 deg.) corresponds to a large tilt.

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 has better polymerization speed and faster angulation speed, lower surface roughness after polymerization, better voltage retention rate, less residue, good pretilt angle stability and low-temperature stability, excellent comprehensive performance and improved problems of broken bright spots, image viscosity, uneven display and the like in the existing PSA type liquid crystal display device through the mutual cooperation of the first component containing the compound of the formula I and the second component containing the compound of the formula II and the compound of the formula III. The liquid crystal composition can provide a PSA type liquid crystal display device with more excellent quality, and has very broad 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: nCC1OWO2; wherein C represents a1, 4-cyclohexylene group, 1O represents a methoxylene group, W represents a2, 3-difluoro-1, 4-phenylene group, O2 represents an ethoxy group, 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 an n-propyl group.

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.)

Ra surface roughness (nm)

LTS (-20 ℃ C.) low temperature storage time (-20 ℃ C.)

PTA pretilt angle (°)

Stability of ΔPTA pretilt angle (°)

VHR Voltage holding Rate (%)

RM residual Polymer residue (UV 2, 90 min)

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, and the thickness of the VA type test box is 5.8 mu m;

LTS (-20 ℃): placing the liquid crystal medium in a glass bottle, preserving at a constant temperature of-20 ℃, and recording the time when the precipitation of crystals is observed; 19Day OK means that it can be used after 19 days, and 12Day NG means that crystals are precipitated after 12 days;

Ra: after the liquid crystal composition is polymerized by UV illumination to form an angle of 88 degrees, liquid crystal molecules are washed away, and then an Atomic Force Microscope (AFM) is used for testing the morphology roughness of the polymerized polymer layer;

PTA: filling liquid crystal into a VA type test box (box thickness is 3.5 mu m) by using a crystal rotation method, applying voltage (15V, 60 Hz), simultaneously irradiating by using ultraviolet light UV1 to polymerize the polymerizable compound to form a pretilt angle PTA1, and continuously irradiating ultraviolet light UV2 to the liquid crystal composition with the pretilt angle PTA1 so as to eliminate the residual polymerizable compound in the PTA1 state, wherein the pretilt angle formed by the polymerizable compound is PTA2; the polymerization rate of the polymerizable compound was examined by comparing the magnitude of the pretilt angle formed when UV1 was irradiated for the same time (the smaller the pretilt angle, the faster the polymerization rate) or the time required to form the same pretilt angle (the shorter the time required, the faster the polymerization rate);

Δpta: after a fixed time of voltage application, the pretilt angle changes; after the test cartridge used in the test of the pretilt angle PTA is subjected to the UV1 step and the UV2 step to form a pretilt angle of 88±0.2°, a SW wave of 60Hz, an AC voltage of 20V and a DC voltage of 2V are applied to the test cartridge, and after a fixed period of time in an environment where a backlight exists at 40 ℃, the pretilt angle of the test cartridge, Δpta (168 h) =pta (initial) -PTA (168 h); the smaller Δpta (168 h) indicates the better the stability of the pretilt angle;

Polymer residue: after application of UV2 for 90min, the liquid crystals eluted from the liquid crystal test cell were detected by High Performance Liquid Chromatography (HPLC), wherein the content of polymerizable compounds was polymer residue;

VHR: after UV2 was applied for 30min, 60min, 90min, the test was performed using a TOYO 6254 type liquid crystal physical property evaluation system under the following test conditions: VA type test box with 60 ℃, 1V, 0.6Hz and box thickness of 3.5 μm.

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.

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.

Examples 1-2 and comparative examples 1-3

The components and performance parameters of the liquid crystal composition LC1 (second component) for examples 1-2 and comparative examples 1-2 and the liquid crystal composition LC3 (second component) for comparative example 3 are shown in table 2:

TABLE 2

0.3 Part of the compound of formula I-1Is added to 100 parts of the liquid crystal composition LC1 as example 1; 0.3 part of the compound of formula I-2-1Is added to 100 parts of the liquid crystal composition LC1 as example 2; 0.3 part of RM3To 100 parts of liquid crystal composition LC1 as comparative example 1; 0.3 part of RM4To 100 parts of liquid crystal composition LC1 as comparative example 2; 0.3 part of the compound of formula I-1Is added to 100 parts of the liquid crystal composition LC3 as comparative example 3.

The results of the performance test of the liquid crystal compositions provided in examples 1 to 2 and comparative examples 1 to 3 are shown in Table 3:

TABLE 3 Table 3

From the results of the performance tests of examples 1-2 and comparative examples 1-2, it is understood that the liquid crystal composition of the present invention has smaller PTA1 formed after the application of UV1 for different times, faster angulation speed, smaller change of pretilt angle after the application of voltage for different times, better pretilt angle stability, smaller polymer residue after the application of UV2 for a certain time, higher VHR, lower polymer residue and better stability, lower surface roughness, longer low temperature storage time, and better low temperature stability by optimizing the structure of the polymerizable compound of the first component.

As is clear from the performance test results of example 1 and comparative example 3, the liquid crystal composition of the present invention has smaller PTA1 formed after the application of UV1 for different times, faster angulation speed, smaller change of pretilt angle after the application of voltage for different times, better pretilt angle stability, smaller polymer residue after the application of UV2 for a certain time, higher VHR, lower polymer residue and better stability, lower surface roughness, longer low-temperature storage time, and better low-temperature stability by the preference of the second component compound and the content thereof.

Examples 3 to 4 and comparative examples 4 to 6

The components and performance parameters of the liquid crystal composition LC2 (second component) for examples 3 to 4 and comparative examples 4 to 5 and the liquid crystal composition LC4 (second component) for comparative example 6 are shown in table 4:

TABLE 4 Table 4

0.3 Part of the compound of formula I-1Is added to 100 parts of the liquid crystal composition LC2 as example 3; 0.3 part of the compound of formula I-2-1Is added to 100 parts of the liquid crystal composition LC2 as example 4; 0.3 part of RM3To 100 parts of liquid crystal composition LC2 as comparative example 4; 0.3 part of RM4To 100 parts of liquid crystal composition LC2 as comparative example 5; 0.3 part of the compound of formula I-1Is added to 100 parts of the liquid crystal composition LC4 as comparative example 6.

The results of the performance test of the liquid crystal compositions provided in examples 3 to 4 and comparative examples 4 to 6 are shown in Table 5:

TABLE 5

From the results of the performance tests of examples 3 to 4 and comparative examples 4 to 5, it is understood that the liquid crystal composition of the present invention has smaller PTA1 formed after the application of UV1 for different times, faster angulation speed, smaller change of pretilt angle after the application of voltage for different times, better pretilt angle stability, smaller polymer residue after the application of UV2 for a certain time, higher VHR, lower polymer residue and better stability, lower surface roughness, longer low temperature storage time, and better low temperature stability by optimizing the structure of the polymerizable compound of the first component.

As is apparent from the performance test results of example 3 and comparative example 6, the liquid crystal composition of the present invention has smaller PTA1 formed after UV1 is applied for different times, faster angulation speed, smaller change of pretilt angle after voltage is applied for different times, better pretilt angle stability, smaller polymer residue after UV2 is applied for a certain time, higher VHR, lower polymer residue and better stability, lower surface roughness, longer low temperature storage time, and better low temperature stability by the preference of the second component compound and the content thereof.

Examples 5 to 8

Examples 5-8 the components and performance parameters of the liquid crystal composition LC5 (second component) are shown in table 6:

TABLE 6

0.3 Part of the compound of formula I-1Is added to 100 parts of the liquid crystal composition LC5 as example 5; 0.3 part of the compound of formula I-2-1Is added to 100 parts of the liquid crystal composition LC5 as example 6; 0.3 part of the compound of formula I-10Is added to 100 parts of the liquid crystal composition LC1 as example 7; 0.3 part of the compound of formula I-11-1Is added to 100 parts of the liquid crystal composition LC5 as example 8.

The results of the performance test of the liquid crystal compositions provided in examples 5 to 8 are shown in Table 7:

TABLE 7

In summary, the first component containing the polymerizable compound shown in the formula I and the second component containing the compound shown in the formula II and the formula III with a specific content are mutually cooperated, so that the polymerization speed and the angulation speed of the liquid crystal composition are higher, the pretilt angle stability is better, the residual quantity after polymerization is lower (less than or equal to 71 ppm), the surface roughness of a polymer layer is smaller and can be lower than 12nm, the voltage holding rate is high, the stable storage is realized at the low temperature of minus 20 ℃ for more than 18 days, the low-temperature stability is excellent, and the PSA type liquid crystal display device with more excellent quality can be provided.

The applicant states that the present invention is described by way of the above examples as a liquid crystal composition and a liquid crystal display device of the present invention, but the present invention is not limited to the above examples, i.e., it is not meant that the present invention must be practiced by relying on 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, characterized in that the liquid crystal composition comprises a combination of a first component and a second component;

the first component comprises at least one polymerizable compound of formula I:

The second component comprises 10-50% of a compound of formula II:

And

20-50% By mass of a compound of formula III:

Wherein ,Y₁、Y₂、Y₃、Y₄、Y₅、Y₆、Y₇、Y₈、Y₉、Y₁₀、Y₁₁ and Y ₁₂ each independently represent-H, -F, -Cl, -OCH ₃ or-CH ₃, and comprises at least two-OCH ₃;

The two-OCH ₃ are connected with adjacent benzene rings, and the difference between m values of the corresponding Y _m is 2,4 or 6; m represents an integer of 1 to 12;

P ₁ and P ₂ each independently represent

Sp ₁ and Sp ₂ each independently represent a single bond, - (CH ₂)_p-、-(CH₂)_p-O-、-(CH₂)_p -O-CO-or- (CH ₂)_p -CO-O-, p represents an integer of 1 to 12);

R ₁、R₂、R₃ and R ₄ 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-, -S-, -CO-O-or-O-CO-;

n represents 0 or 1;

The mass percentage of the polymerizable compound of the formula I in the liquid crystal composition is 0.01-2.0%.

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

And

Wherein Y ₁'、Y₂'、Y₃'、Y₄'、Y₇'、Y₈'、Y₁₁ 'and Y ₁₂' each independently represent-F, -Cl or-CH ₃.

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

And

The R ₁ and R ₂ have the same defined ranges as in claim 1.

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

And

Wherein R ₃ 'and R ₄' each independently represent a straight-chain alkyl group having 1 to 6 carbon atoms.

5. The liquid crystal composition of claim 1, wherein the second component 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 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-;

Ring(s) Ring(s)And ringEach independently represents The saidAt 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 _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 0, the ring And ringNot at the same time be

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

And

The R _M1 and R _M2 have the same defined ranges as claim 5.

7. The liquid crystal composition according to claim 5, wherein the mass percentage of the compound of formula M in the second component is 0.1 to 50%.

8. The liquid crystal composition of claim 1, wherein the second component 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 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-;

Ring(s) And ringEach independently representsThe 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; the said-Ch=in one or at least two rings may be replaced by-n=in one or more rings; one or at least two of the foregoing groups-H may be substituted with-F, -Cl or-CN;

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 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+n_N2 = 1, the compound of formula N does not contain a duplex structure;

When n _N1 represents 2 and n _N2 represents 0, the ring Not be of

9. The liquid crystal composition according to claim 8, wherein the compound of formula N is selected from the group consisting of:

And

The R _N1 and R _N22 have the same defined ranges as in claim 8.

10. The liquid crystal composition according to claim 8, wherein the mass percentage of the compound of formula N in the second component is 0.1 to 50%.

11. A liquid crystal display device comprising the liquid crystal composition according to any one of claims 1 to 10.