阅读说明：本技术 含有可聚合化合物的液晶组合物及其液晶显示器件 (Liquid crystal composition containing polymerizable compound and liquid crystal display device thereof ) 是由 丁文全 王盼盼 杨亚非 徐海彬 陈昭远 于 2020-05-15 设计创作，主要内容包括：本发明公开了一种液晶组合物,所述液晶组合物包含一种或更多种通式I的可聚合化合物以及一种或更多种通式II的化合物。与现有技术相比,本发明的液晶组合物的聚合速度可以维持在较高水平,同时聚合后的聚合物残留量低且无碎亮点产生,在应用于PSA型液晶显示器件中时,可以有效改善现有PSA型液晶显示器件中存在的“图像粘滞”和“碎亮点”等问题,从而满足液晶面板对信赖性高、残影低风险的要求,在PSA型液晶显示器中具有较高的应用价值。(The invention discloses a liquid crystal composition comprising one or more polymerizable compounds of formula I and one or more compounds of formula II. Compared with the prior art, the polymerization speed of the liquid crystal composition can be maintained at a higher level, the residual amount of the polymerized polymer is low, and no broken bright spots are generated, so that when the liquid crystal composition is applied to a PSA type liquid crystal display device, the problems of image sticking, broken bright spots and the like in the conventional PSA type liquid crystal display device can be effectively improved, the requirements of a liquid crystal panel on high reliability and low risk of residual shadow are met, and the liquid crystal composition has higher application value in the PSA type liquid crystal display device.)

1. A liquid crystal composition comprising one or more polymerizable compounds of formula I:

and

one or more compounds of formula II:

wherein the content of the first and second substances,

R、X₁-X₁₂each independently represents-H, halogen, -CN, -Sp₂-P₂Or a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, wherein one or two or more-CH groups which are not adjacent to each other are contained in the linear, branched or cyclic alkyl group having 1 to 12 carbon atoms₂-may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-or-O-CO-One or more-H may each be independently substituted with-F or-Cl; wherein X₁-X₁₂At least one of them represents-Cl;

P₁and P₂Each independently represents a polymerizable group;

Sp₁and Sp₂Each independently represents a spacer group or a single bond;

Z₁and Z₂Each independently represents-O-, -S-, -CO-O-, -O-CO-O-, -CH₂O-、-OCH₂-、-CH₂S-、-SCH₂-、-CF₂O-、-OCF₂-、-CF₂S-、-SCF₂-、-(CH₂)_n-、-CF₂CH₂-、-CH₂CF₂-、-(CF₂)_n-、-CH＝CH-、-CF＝CF-、-CH＝CF-、-CF＝CH-、-C≡C-、-CH＝CH-CO-O-、-O-CO-CH＝CH-、-CH₂CH₂-CO-O-、-O-CO-CH₂CH₂-、-CR¹R²-or a single bond, wherein R¹And R²Each independently represents-H or a linear or branched alkyl group containing 1 to 12 carbon atoms, and n represents an integer of 1 to 4; (ii) a

a represents an integer of 0 to 2;

R_b1and R_b2Each independently represents-H, a linear, linear or cyclic alkyl group having 1 to 12 carbon atoms, wherein one or two or more-CH groups which are not adjacent to each other in the linear, branched or cyclic alkyl group having 1 to 12 carbon atoms₂-may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-, respectively, and one or more-H may be independently substituted by-F or-Cl, respectively;

ring (C)And ringEach independently representWhereinOne or more-CH of₂-may be replaced by-O-, one or at most two of the ring single bonds may be replaced by double bonds, whereinMay be substituted by-F or-Cl, and one or more rings may be substituted by-CH-may be substituted by-N;

Z_b1and Z_b2Each independently represents-CO-O-, -O-CO-, -CF₂O-、-OCF₂-、-CH₂O-、-OCH₂-、-CH₂-、-CH₂CH₂-、-(CH₂)₄-、-CH＝CH-CH₂O-、-C₂F₄-、-CH₂CF₂-、-CF₂CH₂-, -CF ═ CF-, -CH ═ CF-, -CF ═ CH-, -CH ═ CH-, -C ≡ C-, or a single bond;

L₁and L₂Each independently represents-F, -Cl, -CF₃or-CHF₂；

X represents-CO-, -S-or-O-; and is

b1 and b2 each independently represent 0, 1 or 2.

2. The liquid crystal composition of claim 1, wherein R represents-Sp₂-P₂。

3. The liquid crystal composition according to claim 2, wherein a represents 0 or 1.

4. The liquid crystal composition of claim 3, wherein the polymerizable compound of formula I is selected from the group consisting of:

and

wherein the content of the first and second substances,

X₁-X₁₂each independently represents-F, -Cl, -Sp₂-P₂Or a linear, branched or cyclic alkyl or alkoxy group containing 1 to 5 carbon atoms.

5. The liquid crystal composition of claim 4, wherein Z is₁And Z₂At least one of them represents a single bond.

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

and

wherein the content of the first and second substances,

ring (C)Having a ringThe same definition;

Z_b1' having and Z_b1The same definition; and is

X represents-S-or-O-.

7. The liquid crystal composition of claim 6, wherein the compound of formula II is present in an amount of 1-20% by weight based on the total weight of the liquid crystal composition.

8. The liquid crystal composition of claim 1, further comprising one or more compounds of formula M

Wherein the content of the first and second substances,

R_M1and R_M2Each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms, Wherein one of the linear or branched alkyl groups having 1 to 12 carbon atomsOr more than two non-adjacent-CH₂-may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-;

ring (C)Ring (C)And ringEach independently represent WhereinOne or more-CH of₂-may be replaced by-O-, whereinAt most one-H in (a) may be substituted by halogen;

Z_M1and Z_M2Each independently represents a single bond, -CO-O-, -O-CO-, -CH₂O-、-OCH₂-、-CH＝CH-、-C≡C-、-CH₂CH₂-、-(CH₂)₄-、-CF₂O-、-OCF₂-or-CF₂CF₂-; and is

n_M1Represents 0, 1, 2 or 3, wherein when n is_M1When 2 or 3, ringMay be the same or different, Z_M2May be the same or different.

9. The liquid crystal composition of claim 1, further comprising one or more compounds of formula N

Wherein the content of the first and second substances,

R_N1and R_N2Each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms, Wherein one or two or more non-adjacent-CH groups in the linear or branched alkyl group having 1 to 12 carbon atoms₂-said linear or branched alkyl radical containing from 1 to 12 carbon atoms which may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-or-O-CO-, respectively,Each of one or more-H may be independently substituted with-F or-Cl;

ring (C)And ringEach independently representWhereinOne or more-CH of₂-may be replaced by-O-, one or at most two rings of single bondsIs replaced by a double bond, whereinMay be substituted by-F or-Cl, and one or more rings may be substituted by-CH-may be substituted by-N;

Z_N1and Z_N2Each independently represents a single bond, -CO-O-, -O-CO-, -CH₂O-、-OCH₂-、-CH＝CH-、-C≡C-、-CH₂CH₂-、-(CH₂)₄-、-CF₂O-、-OCF₂-or-CF₂CF₂-；

L_N1And L_N2Each independently represents-H or methyl; and is

n_N1Represents 0, 1, 2 or 3, n_N2Represents 0 or 1, and 0. ltoreq. n_N1+n_N2Is less than or equal to 3, wherein when n is_N1When 2 or 3, ringMay be the same or different, Z_N1May be the same or different.

10. The liquid crystal composition of claim 1, further comprising one or more additives.

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

12. The liquid crystal display device according to claim 11, wherein the liquid crystal display device is a PSA type liquid crystal display device.

Technical Field

The invention relates to the field of liquid crystal display, in particular to a liquid crystal composition containing a polymerizable compound and a liquid crystal display device thereof.

Background

Liquid Crystal Displays (LCDs) have been rapidly developed due to their small size, light weight, low power consumption and excellent Display quality, and are widely used particularly in portable electronic information products. Liquid crystal displays are classified into types of PC (phase change), TN (twisted nematic), STN (super twisted nematic), ECB (electrically controlled birefringence), OCB (optically compensated bend), IPS (in-plane switching), FFS (fringe field switching), VA (vertical alignment), and PSA (polymer stable alignment), etc., according to the type of display mode.

The PSA mode is to fix the orientation of liquid crystal molecules by adding a small amount (e.g., 0.3 wt%, more typically < 1 wt%) of one or more polymerizable compounds to a liquid crystal composition and polymerizing or crosslinking it in situ (typically by UV photopolymerization) in a state where the liquid crystal molecules have an initial orientation with or without applying a voltage between electrodes after filling the liquid crystal composition into a liquid crystal cell. The polymerization is carried out at a temperature at which the liquid-crystalline composition exhibits a liquid-crystalline phase (generally at room temperature). It has been confirmed that the addition of a polymerizable liquid crystal compound to a liquid crystal composition is particularly suitable because the tilt angle of liquid crystal molecules can be well controlled by the polymer structure formed in the cell, and the PSA type liquid crystal display element also has the effects of high-speed response and high contrast.

Accordingly, a PSA type liquid crystal display element is continuously developed, and the PSA principle is also used in various conventional liquid crystal displays such as known PSA-VA, PSA-OCB, PSA-IPS, PSA-FFS and PSA-TN type liquid crystal displays. PSA type displays can operate as either active matrix or passive matrix displays, as conventional liquid crystal displays. In the case of active matrix displays the individual pixels are typically addressed by integrated non-linear active elements, such as transistors, whereas in the case of passive matrix displays the individual pixels are typically addressed according to multiplexing methods known in the art.

However, the PSA type liquid crystal display element also has some cases of display defects (such as image retention). Studies have shown that such problems are mostly caused by the presence of impurities and by the variation of the orientation of the liquid crystal molecules (variation of the pretilt angle) which is controlled by the polymer network formed after polymerization of the polymerizable compound. If the structural rigidity of the polymerizable compound constituting the polymer network is insufficient, there is a possibility that the structure of the polymer network changes when the PSA type liquid crystal display element continuously displays the same pattern for a long time, which in turn causes a change in the pretilt angle of the liquid crystal molecules. Therefore, it is generally necessary to select a polymerizable compound having a rigid structure.

The prior art widely uses polymerizable compounds of the following formulae (a) and (b):

wherein, P₁And P₂Both represent polymerizable groups, which are typically acrylate or methacrylate groups.

However, with the development of technology, the LCD display quality requirement in the LCD display industry is more strict, especially in the TV industry, the TV size is generally increased, the LCD generation line is also increased, and the difficulty of the manufacturing process of the large-size LCD panel is also obviously increased. Therefore, how to ensure the display quality is an urgent problem to be solved. In addition to the continuous optimization of panel manufacturing processes, the continuous development of liquid crystal materials is one of the solutions, and especially for PSA type liquid crystal displays, the improvement of the performance of various aspects of polymerizable compounds is a hot spot of research.

At present, one of the common problems in the production of PSA type liquid crystal displays is the residue or removal of polymerizable compounds. In PSA type liquid crystal displays, after the polymerizable compound is polymerized by applying UV light to produce the pretilt angle, a small amount of unreacted polymerizable compound may polymerize in an uncontrolled manner after the display is fabricated, affecting the quality of the display, e.g., the residual polymerizable compound may be polymerized by UV light from the environment or by backlighting, the pretilt angle may change and the transmittance may change over multiple addressing periods in the on display area, while the pretilt angle and transmittance may remain unchanged in the off area, producing an "image sticking" effect. Therefore, it is desirable that the polymerizable compound be able to polymerize as completely as possible during the production of the PSA-type liquid crystal display, and that the residual polymerizable compound react in a controlled manner. The faster the polymerization rate, the more advantageous it is to achieve this desire.

Another common problem of the PSA type liquid crystal display is the tendency to "shatter bright spots" due to the excessive size of the polymer particles formed by the polymerizable compound during the polymerization process. In addition, the polymer particles are not uniform in size, which causes uneven distribution of the polymer, and thus causes a problem of uneven display. Therefore, it is desired to obtain a polymerizable compound capable of forming polymer particles having a small particle size and a uniform distribution, thereby improving the problems of "broken bright spots" and display unevenness.

In addition, the prior art polymerizable compounds generally have high melting points and show only limited solubility in many of the existing commonly used liquid crystal compositions, often precipitating out of the liquid crystal composition. In addition, the polymerizable compound has a possibility of self-polymerization, which further deteriorates its solubility in the liquid crystal composition. Therefore, it is generally necessary to introduce a liquid crystal composition having a polymerizable compound dissolved therein at a low temperature in order to reduce the risk of self-polymerization of the polymerizable compound, which puts higher demands on the solubility of the polymerizable compound in the liquid crystal composition, especially its solubility at a low temperature.

Therefore, it is desirable to develop a liquid crystal composition that can simultaneously or satisfy the above requirements or at least satisfy one of the above requirements.

Disclosure of Invention

The purpose of the invention is as follows: in view of the drawbacks of the prior art, the present invention aims to provide a polymerizable compound-containing liquid crystal composition having a faster polymerization rate and a lower residual amount of polymer after polymerization, and which does not cause display defects such as "image sticking" and "broken bright spots" when applied to a liquid crystal display device (particularly, a PSA type liquid crystal display device).

Another object of the present invention is to provide a liquid crystal display device comprising the above liquid crystal composition.

The technical scheme is as follows: in order to achieve the above object, the present invention provides a liquid crystal composition comprising one or more polymerizable compounds of the general formula I:

one or more compounds of formula II:

wherein the content of the first and second substances,

R、X₁-X₁₂each independently represents-H, halogen, -CN, -Sp₂-P₂Or a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, wherein one or two or more-CH groups which are not adjacent to each other are contained in the linear, branched or cyclic alkyl group having 1 to 12 carbon atoms₂-may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-, respectively, and one or more-H may be independently substituted by-F or-Cl, respectively; wherein X₁-X₁₂At least one of them represents-Cl;

P₁and P₂Each independently represents a polymerizable group;

Sp₁and Sp₂Each independently represents a spacer group or a single bond;

Z₁and Z₂Each independently represents-O-, -S-, -CO-O-, -O-CO-O-, -CH₂O-、-OCH₂-、-CH₂S-、-SCH₂-、-CF₂O-、-OCF₂-、-CF₂S-、-SCF₂-、-(CH₂)_n-、-CF₂CH₂-、-CH₂CF₂-、-(CF₂)_n-、-CH＝CH-、-CF＝CF-、-CH＝CF-、-CF＝CH-、-C≡C-、-CH＝CH-CO-O-、-O-CO-CH＝CH-、-CH₂CH₂-CO-O-、-O-CO-CH₂CH₂-、-CR¹R²-or a single bond, wherein R¹And R²Each independently represents-H or a linear or branched alkyl group containing 1 to 12 carbon atoms, and n represents an integer of 1 to 4;

a represents an integer of 0 to 2;

R_b1and R_b2Each independently represents-H, a linear, linear or cyclic alkyl group having 1 to 12 carbon atoms, wherein one or two or more-CH groups which are not adjacent to each other in the linear, branched or cyclic alkyl group having 1 to 12 carbon atoms₂-may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-, respectively, and one or more-H may be independently substituted by-F or-Cl, respectively;

ring (C)And ringEach independently representWhereinOne or more-CH of₂-may be replaced by-O-, one or at most two of the ring single bonds may be replaced by double bonds, whereinMay be substituted by-F or-Cl, and one or more rings may be substituted by-CH-may be substituted by-N;

Z_b1and Z_b2Each independently represents-CO-O-, -O-CO-, -CF₂O-、-OCF₂-、-CH₂O-、-OCH₂-、-CH₂-、-CH₂CH₂-、-(CH₂)₄-、-CH＝CH-CH₂O-、-C₂F₄-、-CH₂CF₂-、-CF₂CH₂-, -CF ═ CF-, -CH ═ CF-, -CF ═ CH-, -CH ═ CH-, -C ≡ C-, or a single bond;

L₁and L₂Each independently represents-F, -Cl, -CF₃or-CHF₂；

X represents-CO-, -S-or-O-; and is

b1 and b2 each independently represent 0, 1 or 2.

In some embodiments of the invention, preferably, R represents-Sp₂-P₂。

In some embodiments of the invention, preferably, a represents 0 or 1.

In some embodiments of the present invention, the liquid crystal composition comprises a polymerizable compound of formula I.

In some embodiments of the present invention, the liquid crystal composition comprises one polymerizable compound of formula I wherein a ═ 0 and one polymerizable compound of formula I wherein a ═ 1.

In some embodiments of the present invention, the polymerizable compound of formula I is selected from the group consisting of:

wherein the content of the first and second substances,

X₁-X₁₂each independently represents-F, -Cl, -Sp₂-P₂Or a linear, branched or cyclic alkyl or alkoxy group containing 1 to 5 carbon atoms.

In some embodiments of the invention, preferably, Z is₁And Z₂At least one of them represents a single bond; further preferably, Z₁And Z₂All represent single bonds.

The polymerizable groups referred to in the present invention are groups suitable for polymerization reactions (e.g., radical or ionic bond polymerization, polyaddition or polycondensation), or groups suitable for addition or condensation on the polymer backbone. For chain polymerization, particular preference is given to groups comprising-C ═ C-or-C ≡ C-; for the ring-opening polymerization, oxetane or epoxy, for example, is particularly preferable.

In some embodiments of the invention, it is preferred that the polymerizable group P is a polymerizable group₁And P₂Each independently represent or-SH; preferably, the polymerizable group P₁And P₂Each independently represent

As used herein, the term "spacer group" is known to those skilled in the art and is described in the literature (e.g., Pure appl. chem.2001,73(5),888 and c.tscherske, g.pelzl, s.diele, angelw.chem.2004, 116, 6340-6368). The term "spacer group" as used herein meansA flexible group linking the mesogenic group and the polymerizable group in the polymerizable compound. A typical spacer group may be, for example, - (CH)₂)_p1-、-(CH₂CH₂O)_q1-CH₂CH₂-、-(CH₂CH₂S)_q1-CH₂CH₂-、-(CH₂CH₂NH)_q1-CH₂CH₂-、-CR⁰R⁰⁰-(CH₂)_p1-or- (SiR)⁰R⁰⁰-O)_p1-, wherein p1 represents an integer of 1 to 12, q1 represents an integer of 1 to 3, and R⁰And R⁰⁰Each independently represents-H or a linear, linear or cyclic alkyl group containing 1 to 12 carbon atoms. A particularly preferred spacer group is- (CH)₂)_p1-、-(CH₂)_p1-O-、-(CH₂)_p1-O-CO-、-(CH₂)_p1-CO-O-、-(CH₂)_p1-O-CO-O-or-CR⁰R⁰⁰-(CH₂)_p1-。

In some embodiments of the invention, the polymerizable compound of formula I comprises 0.001 to 5% by weight of the total liquid crystal composition; preferably, the polymerizable compound of formula I is present in an amount of 0.01 to 2% by weight of the total liquid crystal composition; further preferably, the polymerizable compound of formula I accounts for 0.25-0.4% of the total weight of the liquid crystal composition.

In some embodiments of the invention, the compound of formula II is selected from the group consisting of:

and

wherein the content of the first and second substances,

ring (C)Having a ringThe same definition;

Z_b1' having and Z_b1The same definition; and is

X represents-S-or-O-.

In some embodiments of the invention, preferably, R_b1And R_b2Each independently represents a straight chain alkyl or alkoxy group having 1 to 12 carbon atoms.

In some embodiments of the invention, preferably, Z is_b1、Z_b1' and Z_b2Each independently represents-CO-O-, -O-CO-, -CH₂O-、-OCH₂-or a single bond.

In some embodiments of the present invention, preferably, the compound of formula II is selected from the group consisting of compounds of formula II-1 and formula II-2.

In some embodiments of the present invention, preferably, the compound of formula II comprises 1-20% of the total weight of the liquid crystal composition; further preferably, the compound of formula II accounts for 1-15% of the total weight of the liquid crystal composition; still more preferably, the compound of formula II is present in an amount of 2 to 15% by weight of the total liquid crystal composition.

The alkenyl group in the present invention is preferably a group represented by any one of the formulae (V1) to (V9), and particularly preferably formula (V1), formula (V2), formula (V8), or formula (V9). The groups represented by formulae (V1) to (V9) are shown below:

wherein denotes the carbon atom in the ring structure to which it is bonded.

The alkenyloxy group in the present invention is preferably a group represented by any one of formulae (OV1) to (OV9), and particularly preferably formula (OV1), formula (OV2), formula (OV8) or (OV 9). The groups represented by formulae (OV1) to (OV9) are shown below:

wherein denotes the carbon atom in the ring structure to which it is bonded.

In some embodiments of the invention, the liquid crystal composition further comprises one or more compounds of formula M

Wherein the content of the first and second substances,

R_M1and R_M2Each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms, In which one or more than two non-adjacent-CH groups in the linear or branched alkyl group containing 1-12 carbon atoms₂-may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-;

ring (C)Ring (C)And ringEach independently representOrWhereinOne or more-CH of₂-may be replaced by-O-, whereinAt most one-H in (a) may be substituted by halogen;

Z_M1and Z_M2Each independently represents a single bond, -CO-O-, -O-CO-, -CH₂O-、-OCH₂-、-CH＝CH-、-C≡C-、-CH₂CH₂-、-(CH₂)₄-、-CF₂O-、-OCF₂-or-CF₂CF₂-; and is

n_M1Represents 0, 1, 2 or 3, wherein when n is_M1When 2 or 3, ringMay be the same or different, Z_M2May be the same or different.

In some embodiments of the invention, preferably, R_M1And R_M2Each independently represents a linear alkyl group having 1 to 10 carbon atoms, a linear alkoxy group having 1 to 9 carbon atoms, or a linear alkenyl group having 2 to 10 carbon atoms; further preferably, R_M1And R_M2Each independently represents a linear alkyl group having 1 to 8 carbon atoms, a linear alkoxy group having 1 to 7 carbon atoms, or a linear alkenyl group having 2 to 8 carbon atoms; even further preferably, R_M1And R_M2Each independently represents a linear alkyl group having 1 to 5 carbon atoms, a linear alkoxy group having 1 to 4 carbon atoms, or a linear alkenyl group having 2 to 5 carbon atoms.

In some embodiments of the invention, preferably, R_M1And R_M2Each independently represents a straight-chain alkenyl group having 2 to 8 carbon atoms; further preferably, R_M1And R_M2Each independently represents a straight-chain alkenyl group having 2 to 5 carbon atoms.

In some embodiments of the invention, preferably, R_M1And R_M2One of them is a linear alkenyl group having 2 to 5 carbon atoms, and the other is a linear alkyl group having 1 to 5 carbon atoms.

In some embodiments of the invention, preferably, R_M1And R_M2Each independently represents a linear alkyl group having 1 to 8 carbon atoms, or a linear alkoxy group having 1 to 7 carbon atoms; further preferably, R_M1And R_M2Each independently represents a linear alkyl group having 1 to 5 carbon atoms or a linear alkoxy group having 1 to 4 carbon atoms.

In some embodiments of the invention, preferably, R_M1And R_M2Either one of which is a linear alkyl group having 1 to 5 carbon atoms and the other is a linear alkyl group having 1 to 5 carbon atoms or a linear alkoxy group having 1 to 4 carbon atoms; further preferably, R_M1And R_M2Both of which are each independently a linear alkyl group having 1 to 5 carbon atoms.

In some embodiments of the invention, the compound of formula M is selected from the group consisting of:

the lower limit of the content of the compound of formula M is 10%, 20%, 25%, 30%, 40% or 50% relative to the total weight of the liquid crystal composition of the present invention; the upper limit of the content of the compound of formula M is 70%, 65%, 60%, 55%, 45%, 35% or 25% with respect to the total weight of the liquid crystal composition of the present invention.

For conditioning liquid crystal compositionsClearing points, viscosity, low-temperature storage stability and the like, so that the obtained liquid crystal display device has excellent transmittance and color expression and better application value, and the component composition of the liquid crystal composition needs to be adjusted; in particular, relative to the total weight of the liquid crystal composition of the present invention, wherein the ringTo representThe content of the compound of the general formula M is 10-50%; preferably, wherein the ringTo representThe content of the compound of the general formula M is 20 to 45%.

The content of the compound of formula M is preferably higher in the lower limit and higher in the upper limit when the viscosity of the liquid crystal composition of the present invention needs to be kept low and the response time is short; further, when it is necessary to keep the clearing point of the liquid crystal composition of the present invention high and the temperature stability good, it is preferable that the lower limit value is high and the upper limit value is high; when the absolute value of the dielectric anisotropy is increased in order to keep the driving voltage low, it is preferable that the lower limit value is lowered and the upper limit value is lowered.

In the case where reliability is important, R is preferable_M1And R_M2Each independently is alkyl; in the case where importance is attached to reduction in volatility of the compound, R is preferably_M1And R_M2Each independently is an alkoxy group; when importance is attached to the reduction in viscosity, R is preferably used_M1And R_M2At least one of which is alkenyl.

In some embodiments of the present invention, the liquid crystal composition preferably comprises one or more compounds wherein R_M1And/or R_M2Compounds of the formula M1 being n-propyl

In some embodiments of the invention, the liquid crystal composition further comprises one or more compounds of formula N

Wherein the content of the first and second substances,

R_N1and R_N2Each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms, In which one or more than two non-adjacent-CH groups in the linear or branched alkyl group containing 1-12 carbon atoms₂-may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-, respectively, and one or more-H present in these groups may be independently substituted by-F or-Cl, respectively;

ring (C)And ringEach independently representWhereinOne or more-CH of₂-may be replaced by-O-, one or at most two of the ring single bonds may be replaced by double bonds, whereinMay be substituted by-F or-Cl, and one or more rings may be substituted by-CH-may be substituted by-N;

Z_N1and Z_N2Each independently represents a single bond, -CO-O-, -O-CO-, -CH₂O-、-OCH₂-、-CH＝CH-、-C≡C-、-CH₂CH₂-、-(CH₂)₄-、-CF₂O-、-OCF₂-or-CF₂CF₂-；

L_N1And L_N2Each independently represents-H or methyl; and is

n_N1Represents 0, 1, 2 or 3, n_N2Represents 0 or 1, and 0. ltoreq. n_N1+n_N2Is less than or equal to 3, wherein when n is_N1When 2 or 3, ringMay be the same or different, Z_N1May be the same or different.

In some embodiments of the invention, preferably, R_N1And R_N2Each independently represents a linear or branched alkyl or alkoxy group having 1 to 8 carbon atoms, or a linear or branched alkenyl or alkenyloxy group having 2 to 8 carbon atoms, and further preferably R_N1And R_N2Each independently a linear or branched alkyl or alkoxy group containing 1 to 5 carbon atoms, or a linear or branched alkenyl or alkenyloxy group containing 2 to 5 carbon atoms.

In some embodiments of the invention, R_N1Further preferred is a linear or branched alkyl group having 1 to 5 carbon atoms or a linear or branched alkenyl group having 2 to 5 carbon atoms, R_N1Still more preferably a linear or branched alkyl group having 2 to 5 carbon atoms or an alkenyl group having 2 to 3 carbon atoms; r_N2Further preferred is a straight-chain or branched alkoxy group having 1 to 4 carbon atoms.

In some embodiments of the invention, preferably, the ringAnd ringEach independently represent

In some embodiments of the invention, the compound of formula N is selected from the group consisting of:

in some embodiments of the invention, the compound of formula N is preferably selected from the group consisting of compounds of formula N12, formula N14, formula N16-N20.

The lower limit of the content of the compound of formula N is 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 33%, 35%, 38%, or 40% with respect to the total weight of the liquid crystal composition of the present invention; the upper limit of the content of the compound of formula N is 75%, 72%, 70%, 68%, 65%, 63%, 60%, 55%, 50%, 40%, 38%, 35%, 33%, 30%, 28%, 25%, 23%, 20%, 18%, 15%, or 10% with respect to the total weight of the liquid crystal composition of the present invention.

With respect to the content of the compound of the general formula N, when it is necessary to keep the response time of the liquid crystal display device of the present invention short, the lower limit value and the upper limit value thereof are preferably low; further, when the liquid crystal display device of the present invention needs to maintain a wider operating temperature range, it is preferable that the lower limit value and the upper limit value are lower; when the absolute value of the dielectric anisotropy is increased in order to keep the driving voltage of the liquid crystal composition low, it is preferable that the lower limit value is increased and the upper limit value is increased.

In some embodiments of the present invention, one or more other additives known to those skilled in the art and described in the literature may be added to the liquid crystal composition.

Further, additives such as an antioxidant and a light stabilizer used in the liquid crystal composition of the present invention are preferably as follows:

wherein n represents a positive integer of 1 to 12.

Preferably, the stabilizer is selected from the stabilizers shown below.

In some embodiments of the invention, the stabilizer comprises 0-5% by weight of the total liquid crystal composition; preferably, the stabilizer is 0-1% of the total weight of the liquid crystal composition; more preferably, the stabilizer is present in an amount of 0.01 to 0.1% by weight based on the total weight of the liquid crystal composition.

The liquid crystal composition of the present invention has a dielectric anisotropy Delta epsilon at 25 ℃ in the range of-6 to-2, an optical anisotropy Delta n at 25 ℃ in the range of 0.08 to 0.13, a rotational viscosity Gamma 1 at 25 ℃ in the range of 40 mPas to 100 mPas, and a nematic phase-isotropic phase transition temperature Cp in the range of 60 ℃ to 120 ℃.

The invention also provides a liquid crystal display device, preferably a PSA type liquid crystal display device, more preferably a PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, PS-positive-VA or PS-TN type liquid crystal display device, comprising the compound of formula I of the invention.

The pre-tilt angle PTA of the liquid crystal display device of the present invention is in the range of 85 ° to 89.9 °.

As used herein, the terms "tilt" and "tilt angle" will be understood as the tilt alignment of liquid crystal molecules with respect to the surface of a liquid crystal cell in a liquid crystal display device (in the present invention, preferably a PSA type liquid crystal display device). The tilt angle means an average angle (< 90 °) formed between the longitudinal molecular axis of the liquid crystal molecules (liquid crystal director) 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 °) corresponds to a large tilt.

Has the advantages that:

compared with the prior art, the polymerization speed of the liquid crystal composition can be maintained at a higher level, the residual amount of the polymerized polymer is low, and no broken bright spots are generated, so that when the liquid crystal composition is applied to a PSA type liquid crystal display device, the problems of image sticking, broken bright spots and the like in the conventional PSA type liquid crystal display device can be effectively improved, the requirements of a liquid crystal panel on high reliability and low risk of residual shadow are met, and the liquid crystal composition has higher application value in the PSA type liquid crystal display device.

Detailed Description

The invention will be illustrated below with reference to specific embodiments. It should be noted that the following examples are illustrative of the present invention, and are not intended to limit the present invention. Other combinations and various modifications within the spirit or scope of the present invention may be made without departing from the spirit or scope of the present invention.

In the present invention, unless otherwise specified, all the ratios mentioned in the present invention are weight ratios and all the temperatures are given in degrees Celsius.

For convenience of expression, in the following examples, the group structures of the liquid crystal compounds are represented by the codes listed in Table 1:

TABLE 1 radical structural code of liquid crystal compounds

Compounds of the following formula are exemplified:

the structural formula is represented by the code listed in Table 1, and can be expressed as: nCCGF, wherein n in the code represents the number of C atoms of the left alkyl group, for example, n is 3, namely, the alkyl group is-C₃H₇(ii) a C in the code represents 1, 4-cyclohexylene, G represents 2-fluoro-1, 4-phenylene and F represents a fluoro substituent.

The abbreviated codes of the test items in the following examples are as follows:

cp clearing Point (nematic phase-isotropic phase transition temperature, ° C)

Delta epsilon dielectric anisotropy (1KHz, 25 ℃ C.)

Δ n optical anisotropy (illumination wavelength 589nm, 25 ℃ C.)

Gamma.1 rotational viscosity (mPa. multidot.s, 25 ℃ C.)

PTA Pre-tilt Angle (°)

Wherein the content of the first and second substances,

cp: obtained by testing by a melting point measuring method;

Δε：Δε＝ε_‖-ε_⊥wherein, epsilon_‖Is a dielectric constant parallel to the molecular axis,. epsilon_⊥For the dielectric constant perpendicular to the molecular axis, test conditions: a TN90 type test box with the box thickness of 7 μm and the temperature of 25 ℃; Δ n: testing with Abbe refractometer under sodium lamp (589nm) at 25 deg.C;

γ 1: testing by using a TOYO6254 type liquid crystal physical property evaluation system; and (3) testing conditions are as follows: the temperature is 25 ℃, the voltage is 90V, and the thickness of the test box is 20 μm;

PTA: using a crystal rotation method, a liquid crystal was poured into a VA type test cell (cell thickness 3.5 μm), a voltage (16V, 60Hz) was applied while irradiation with ultraviolet light UV1 was performed to polymerize the polymerizable compound to form a pre-tilt angle PTA1, and then irradiation of ultraviolet light UV2 was continued to the liquid crystal composition having formed the pre-tilt angle PTA1 to eliminate the residual polymerizable compound in the state of PTA1, at which time the polymerizable compound formed a pre-tilt angle PTA 2. The present inventors examined the polymerization speed of the polymerizable compound 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 speed) or the time required to form the same pretilt angle (the shorter the time required, the faster the polymerization speed). The invention inspects the residual amount of the polymerizable compound by eluting the liquid crystal in the liquid crystal test box after applying UV2 with fixed irradiation time length and testing the concentration of the polymerizable compound by High Performance Liquid Chromatography (HPLC).

Broken bright point test method: after completely dissolving the liquid crystal composition containing the polymerizable compound, the solution was poured into a VA type test cell (cell thickness: 4 μm), voltage (16V, 60Hz) was applied thereto and irradiated with UV for 180 seconds, and the state of the polymerized bright spots in the cells was observed using an optical microscope.

The components used in the following examples can be synthesized by a known method or obtained commercially. These synthesis techniques are conventional and the resulting liquid crystal compositions are tested for compliance with electronic compound standards.

Liquid crystal compositions were prepared according to the formulation of each liquid crystal composition specified in the following examples. The liquid crystal composition is prepared by a conventional method in the art, such as mixing in a prescribed ratio by heating, ultrasonic wave, suspension, etc.

The following is a further description of the various precursor liquid crystal compositions by mixing them with the exemplary representatives of the polymerizable compounds of the general formula I according to the invention (I-1-a and I-18-b) and the polymerizable compounds widely used in the prior art (DB-1 and DB-2), respectively, and testing the properties under different conditions.

Comparative example 1

TABLE 2 composition and Performance parameters of the mother liquid Crystal composition Host 1

To 100 parts by weight of the above-described mother liquid crystal composition Host 1, 0.3 parts by weight of the following polymerizable compound DB-1 was added:

comparative example 2

TABLE 3 composition and Performance parameters of the mother liquid Crystal composition Host 2

To 100 parts by weight of the above-described mother liquid crystal composition Host 2, 0.3 parts by weight of the following polymerizable compound DB-1 was added:

comparative example 3

TABLE 4 composition and Performance parameters of the mother liquid Crystal composition Host 3

To 100 parts by weight of the above mother liquid crystal composition Host 3, 0.3 parts by weight of the following polymerizable compound DB-2 was added:

example 1

TABLE 5 composition and Performance parameters of the precursor liquid Crystal composition Host4

To 100 parts by weight of the above-described mother liquid crystal composition Host4 were added 0.3 parts by weight of the following polymerizable compound I-1-a:

example 2

TABLE 6 composition and Performance parameters of the precursor liquid Crystal composition Host5

To 100 parts by weight of the above-described mother liquid crystal composition Host5 were added 0.28 parts by weight of the following polymerizable compound I-1-a and 0.015 parts by weight of the following polymerizable compound I-18-b:

example 3

TABLE 7 composition and Performance parameters of the precursor liquid Crystal composition Host6

To 100 parts by weight of the above-described mother liquid crystal composition Host6, 0.32 parts by weight of the following polymerizable compound I-1-a was added:

example 4

TABLE 8 composition and Performance parameters of the precursor liquid Crystal composition Host6

To 100 parts by weight of the above-described mother liquid crystal composition Host6, 0.32 parts by weight of the following polymerizable compound I-1-a was added:

the liquid crystal compositions prepared in the above comparative examples 1 to 3 and examples 1 to 4 were subjected to pre-tilt angle and polymer residue tests, and the instances of broken bright spots were observed, with the results shown in the following table 9:

table 9 results of performance testing

As can be seen from comparative example 1 and example 1 in the above table, the liquid crystal composition containing formula I and formula II of the present invention has significantly lower polymer residue when the polymerization rate is comparable, on the premise of having substantially equivalent clearing point, dielectric anisotropy, optical anisotropy and rotational viscosity; as can be seen from comparison of comparative examples 2-3 with example 1, in example 1, the polymerizable compounds DB-1 and DB-2 commonly used in the art are replaced by the compounds of the general formula I, the liquid crystal composition of the invention has lower polymer residue while maintaining the polymerization speed at a higher level, and can effectively avoid the generation of broken bright spots, thereby remarkably reducing the reliability of the liquid crystal panel and the risk of afterimage; as can be seen from examples 1-4, the polymerization rate of the liquid crystal composition of the present invention is maintained at a high level, and the polymer residue after polymerization is low and no broken bright spots are generated, so that the requirements of liquid crystal panels on high reliability and low risk of residual image can be satisfied. Therefore, the liquid crystal composition can effectively solve the problems of image sticking, broken bright spots and the like in the conventional PSA type liquid crystal display device, and has higher practical application value.

The above embodiments are merely illustrative of the technical concept and features of the present invention, and the present invention is not limited thereto, and equivalent changes and modifications made according to the spirit of the present invention should be covered thereby.