LIQUID CRYSTAL COMPOSITION CONTAINING POLYMERIZABLE COMPOUND AND DISPLAY DEVICE THEREOF

Abstract

A liquid crystal composition includes at least one compound of general Formula I, at least one compound of general Formula II and at least one compound of general Formula M. The polymerizable liquid crystal composition provides a higher VHR (especially an excellent VHR after UV irradiation), a lower surface roughness of the polymer layer, a faster polymerization rate, a lower residual amount of the polymerizable compound and a better pretilt angle stability, which enables the production of a liquid crystal display device with a better voltage stability and a faster response speed, and can effectively reduce or prevent the occurrences of problems such as “burn-in”, “image sticking”, “Zara Particle” and “uneven display” in the liquid crystal display device. A liquid crystal display includes the liquid crystal composition.

##STR00001##

Claims

1. A liquid crystal composition containing polymerizable compounds, comprising: at least one compound of general Formula I ##STR00071## at least one compound of general Formula II ##STR00072## and at least one compound of general Formula M ##STR00073## in which, R and X.sub.1-X.sub.12 each independently represents —H, halogen, —CN, -Sp.sub.2-P.sub.2 or C.sub.1-12 linear, branched or cyclic alkyl, wherein one or more nonadjacent —CH.sub.2— in the C.sub.1-12 linear, branched or cyclic alkyl can each be independently replaced by —CH═CH—, —C≡C—, —O—, —CO—, —CO—O— or —O—CO—, and one or more —H in the C.sub.1-12 linear, branched or cyclic alkyl can each be independently substituted by —F or —Cl, wherein at least one of X.sub.1-X.sub.12 represents —Cl; P.sub.1 and P.sub.2 each independently represents a polymerizable group; Sp.sub.1 and Sp.sub.2 each independently represents spacer group or single bond; R.sub.1, R.sub.2, R.sub.M1 and R.sub.M2 each independently represents C.sub.1-12 linear or branched alkyl, ##STR00074## wherein one or more nonadjacent —CH.sub.2— in the C.sub.1-12 linear or branched alkyl can each be independently replaced by —CH═CH—, —C≡C—, —O—, —CO—, —CO—O— or —O—CO—; ring ##STR00075## represents ##STR00076## wherein one or more —CH.sub.2-in ##STR00077## can be replaced by —O—, and one or more single bonds in the ring can be replaced by double bond: ring ##STR00078## ring ##STR00079## and ring ##STR00080## each independently represents ##STR00081## wherein one or more —CH.sub.2— in ##STR00082## can be replaced by —O—, and one or more single bonds in the ring can be replaced by double bond; at most one —H on ##STR00083## can be substituted by halogen; Z.sub.1 and Z.sub.2 each independently represents —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CH.sub.2O—, —OCH.sub.2—, —CH.sub.2S—, —SCH.sub.2—, —CF.sub.2O—, —OCF.sub.2—, —CF.sub.2S—, —SCF.sub.2—, —(CH.sub.2).sub.n—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —(CF.sub.2).sub.n—, —CH═CH—, —CF═CF—, —CH═CF—, —CF═CH—, —C≡C—, —CH═CH—CO—O—, —O—CO—CH═CH—, —CH.sub.2CH.sub.2—CO—O—, —O—CO—CH.sub.2CH.sub.2—, —CR.sup.1R.sup.2— or single bond, wherein R.sup.1 and R.sup.2 each independently represents —H or C.sub.1-12 linear or branched alkyl, and n represents a integer from 1 to 4; Z.sub.M1 and Z.sub.M2 each independently represents single bond, —CO—O—, —O—CO—, —CH.sub.2O—, —OCH.sub.2—, —C≡C—, —CH═CH— —CH.sub.2CH.sub.2— or —(CH.sub.2).sub.4—; L.sub.N1 and L.sub.N2 each independently represents —F or —Cl; L.sub.N3 and L.sub.N4 each independently represents —H, C.sub.1-3 alkyl or halogen; a represents 0, 1 or 2, and when a=2, ring ##STR00084## can be same or different, Z.sub.2 can be same or different; b represents 0, 1 or 2, when b=2, ring ##STR00085## can be same or different; and n.sub.M represents 0, 1, 2 or 3, when n.sub.M=2, ring ##STR00086## can be same or different, Z.sub.M2 can be same or different.

2. The liquid crystal composition according to claim 1, wherein R represents -Sp.sub.2-P.sub.2.

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

4. The liquid crystal composition according to claim 1, wherein the compound of general Formula I is selected from a group consisting of the following compounds: ##STR00087## ##STR00088## ##STR00089## ##STR00090## in which, X.sub.1-X.sub.12 each independently represents —F, —Cl, —Sp.sub.2-P.sub.2, or C.sub.1-5 linear, branched or cyclic alkyl or alkoxy.

5. The liquid crystal composition according to claim 1, wherein the compound of general Formula II is selected from a group consisting of the following compounds: ##STR00091##

6. The liquid crystal composition according to claim 1, wherein the compound of general Formula I provides 0.001%-5% by weight of the total weight of the liquid crystal composition, the compound of general Formula II provides 1%-45% by weight of the total weight of the liquid crystal composition, and the compound of general Formula M provides 1%-80% by weight of the total weight of the liquid crystal composition.

7. The liquid crystal composition according to claim 1, further comprising at least one compound of general Formula III and at least one compound of general Formula IV: ##STR00092## in which, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 each independently represents C.sub.1-12 linear or branched alkyl, ##STR00093## wherein one or more nonadjacent —CH.sub.2— in the C.sub.1-12 linear or branched alkyl can each be independently replaced by —CH═CH—, —C≡C—, —O—, —CO—, —CO—O— or —O—CO—; ring ##STR00094## and ring ##STR00095## each independently represents ##STR00096## wherein one or more —CH.sub.2— in ##STR00097## can be replaced by —O—, and one or more single bonds in the ring can be replaced by double bond; one or more —H on ##STR00098## can be substituted by —F, —Cl or —CN, and one or more —CH═ in the ring can be replaced by —N═; ring ##STR00099## represents, ##STR00100## wherein one or more —H on ##STR00101## can be substituted by —F, —Cl or —CN, and one or more —CH═ in the ring can be replaced by —N═; L.sub.1 and L.sub.2 each independently represents —F or —Cl; L.sub.3 and L.sub.4 each independently represents —H, C.sub.1-3 alkyl or halogen; L.sub.5, L.sub.6, L.sub.7 and L.sub.8 each independently represents —H, —F or —Cl, wherein at least two of L.sub.5, L.sub.6, L.sub.7 and L.sub.8 represents —F or —Cl, and when only two of L.sub.5, L.sub.6, L.sub.7 and L.sub.8 represents —F or —Cl, —F and —Cl are on the same benzene ring; Z.sub.3 and Z.sub.4 each independently represents single bond, —CO—O—, —O—CO—, —CH.sub.2O—, —OCH.sub.2—, —CH═CH—, —C≡C—, —CH.sub.2CH.sub.2—, —CF.sub.2CF.sub.2—, —(CH.sub.2).sub.4—, —CF.sub.2O— or —OCF.sub.2—, wherein ring ##STR00102## is non-aromatic ring when Z.sub.3 represents single bond; n.sub.1 represents 1 or 2, and when n.sub.1=2, ring ##STR00103## can be same or different; and n.sub.2 represents 0 or 1.

8. The liquid crystal composition according to claim 7, wherein the compound of general Formula III is selected from the following compounds: ##STR00104## ##STR00105## ##STR00106##

9. The liquid crystal composition according to claim 7, wherein the compound of general Formula III provides 1%-50% by weight of the total weight of the liquid crystal composition, and the compound of general Formula IV provides 1%-20% by weight of the total weight of the liquid crystal composition.

10. A liquid crystal display device comprising the liquid crystal composition according to claim 1.

Description

DETAILED EMBODIMENTS

[0101] The present invention will be illustrated by combining the detailed embodiments below. It should be noted that, the following examples are exemplary embodiments of the present invention, which are only used to illustrate the present invention, not to limit it. Other combinations and various modifications within the conception of the present invention are possible without departing from the subject matter and scope of the present invention.

[0102] For the convenience of the expression, the group structures of the liquid crystal compounds in the following Examples are represented by the codes listed in Table 1:

TABLE-US-00001 TABLE 1 Codes of the group structures of the liquid crystal compounds Unit structure of group Code Name of the group [00054] C 1,4-cyclohexylidene [00055] P 1,4-phenylene [00056] G 2-fluoro-1,4-phenylene [00057] U 2,6-difluoro-1,4-phenylene [00058] W 2,3-difluoro-1,4-phenylene —F F fluorine substituent —O— O oxygen substituent —CH═CH— or V ethenyl —CH═CH.sub.2 —CH.sub.2O— 1O methyleneoxy —OCF.sub.3 OCF3 trifluoromethoxy —CF.sub.3 CF3 trifluoromethyl [00059] Q difluoromethoxy —CH.sub.2CH.sub.2— 2 ethyl bridge bond —C.sub.nH.sub.2n+1 or n (n represents alkyl or alkylene —C.sub.nH.sub.2n— a positive integer of 1-12)

[0103] Take the compound with the following structural formula as an example:

##STR00060##

[0104] Represented by the codes listed in Table 1, this structural formula can be expressed as nCCGF, in which, n in the code represents the number of the carbon atoms of the alkyl group on the left, for example, n is “3”, meaning that the alkyl is —C.sub.3H.sub.7; C in the code represents “cyclohexyl”, G represent 2-fluoro-1,4-phenylene, F represents fluorine substituent.

[0105] The abbreviated codes of the test items in the following Examples are represented as follows: [0106] Cp clearing point (nematic-isotropic phases transition temperature, ° C.) [0107] Δn optical anisotropy (589 nm, 25° C.) [0108] Δε dielectric anisotropy (1 KHz, 25° C.) [0109] γ.sub.1 rotational viscosity (mPa-s, 25° C.) [0110] K.sub.11 splay elastic constant [0111] K.sub.33 bend elastic constant [0112] Tc low temperature phase transition point (minimum temperature of a nematic phase) (° C.) [0113] Ra roughness (nm) [0114] ΔPTA stability of pretilt angle (change in pretilt angle after applying voltage for 120 h) (°) [0115] PTA pretilt angle (°) [0116] VHR (initial) initial voltage holding ratio (%) [0117] VHR (UV) voltage holding ratio after UV-irradiation (%)

[0118] in which,

[0119] Cp is measured with melting point apparatus.

[0120] Δn is measured with an Abbe refractometer under sodium lamp (589 nm) light source at 25° C.

[0121] Δε=ε.sub.//−ε.sub.⊥, in which, ε.sub.// is the dielectric constant parallel to the molecular axis, ε.sub.⊥ is the dielectric constant perpendicular to the molecular axis, with the test conditions: 25° C., 1 KHz, VA type test cell with a cell gap of 6 μm.

[0122] γ1 is measured using a LCM-2 type liquid crystal physical property evaluation system at 25° C. with a test cell having a cell gap of 20 m and a test voltage of 240 V.

[0123] K.sub.11 and K.sub.33 are calculated from the measured C-V curve of the liquid crystal material using LCR meter and an antiparallel rubbed cell, with the following test conditions: a cell gap of 7 μm, V=0.1-20V.

[0124] Tc: samples each having a nematic phase are put in glass vials and kept in freezers at temperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10 days respectively, and then liquid crystal phases are observed. For example, when the sample maintains the nematic phase at −20° C. and changes to crystals or a smectic phase at −30° C., Tc is expressed as Tc<−20° C.

[0125] Ra: after UV photopolymerization of the polymerizable compound contained in the liquid crystal composition, the liquid crystal molecules are rinsed and then the morphological roughness of the polymerized polymer layer is tested with an atomic force microscope (AFM).

[0126] PTA: the pretilt angle is measured by crystal rotation method. Liquid crystals are filled into VA type test cell having a cell gap of 3.5 μm. The test cells are exposed to UV irradiation as described in UV1 step with the application of a voltage (16 V, 60 Hz), causing polymerization of the polymerizable compound and generation of pretilt angle PTA1. The test cells are subsequently exposed to UV irradiation as described in UV2 step to remove residual polymerizable compounds and pretilt angle PTA2 is then generated. In the present invention, the polymerization rate of polymerizable compound are investigated through the comparation of the pretilt angles formed after the same exposure time of UV1 irradiation (the smaller the pretilt angle, the faster the polymerization rate) or the times for generating the same pretilt angle (the shorter the time for generating the same pretilt angle, the fast the polymerization rate). After different exposure times of UV2 irradiation, the liquid crystal is rinsed out of the liquid crystal test cell and the concentration of unreacted polymerizable compound in the liquid crystal is measured by HPLC to evaluate the residual amount of the polymerizable compound.

[0127] ΔPTA: after the test cell used in the measurement of PTA is subjected to UV1 and UV2 steps to form a pretilt angle of 88±0.2°, 60 Hz square wave, AC voltage (20 V) and DC voltage (2 V) are applied to the test cell at 40° C. with the presence of backlight. After a fixed time period, the pretilt angle of the test cell is tested, and ΔPTA (168 h)=PTA (initial)−PTA (168 h), the smaller the ΔPTA (168 h), the better the stability of the pretilt angle.

[0128] VHR (initial) is measured using a TOYO6254 type liquid crystal physical property evaluation system; the test temperature is 60° C., the test voltage is 5 V, and the test frequency is 6 Hz.

[0129] VHR (UV) is measured using a TOYO6254 liquid crystal physical property evaluation system; the test temperature is close to room temperature (i.e., 15-35° C.), the UV-irradiation intensity is 0.1 mW/cm.sup.2-50 mW/cm.sup.2 and the UV-irradiation time is 2 h.

[0130] The components used in the following Examples can either be synthesized by method known in the art or be obtained commercially. The synthetic techniques are conventional, and each of the obtained liquid crystal compounds is tested to meet the standards of electronic compound.

[0131] The liquid crystal compositions are prepared in accordance with the ratios specified in the following Examples through conventional methods in the art, such as heating, ultrasonic wave, or suspension.

TABLE-US-00002 TABLE 2 Structures and codes of polymerizable compounds Code of Formula component Structure of polymerizable compound Code RM-01 [00061] RM-02 [00062] RM-03 [00063] RM-1  [00064] I-12 RM-2  [00065] I-1  RM-3  [00066] I-18 RM-4  [00067] I-1  RM-5  [00068] I-1  RM-6  [00069] I-5  RM-7  [00070] I-18

Comparative Examples 1-4 and Examples 1-8

[0132] The liquid crystal host mixture Host-1 is prepared according to each compound and weight percentage listed in Table 3 as follows.

TABLE-US-00003 TABLE 3 Formulation of the liquid crystal host mixture Host-1 and its test performances Code of Weight Formula Test results for the component percentage Code performance parameters 2CPWO2 8 II-2 Cp 74.2 3CPWO2 9.5 II-2 Δn 0.1095 3PWO2 11 II-1 Δε −3.28 3C1OWO2 11 III-6 γ.sub.1 77 3CC1OWO2 15.5 III-7 Tc −30 3CPO2 4 M-2 3CPP2 10.5 M-13 3CC2 18 M-1 5CC2 4 M-1 4CC3 4 M-1 5PP1 4.5 M-3 Total 100

[0133] Polymerizable compounds RM-01, RM-02 and RM-03 are added into 100 parts by weight of Host-1 to form the compositions of comparative Examples 1-4, and polymerizable compounds RM-1, RM-2, RM-3, RM-4, RM-5, RM-6 and RM-7 are added into 100 parts by weight of Host-1 to form the compositions of Examples 1-8. The specific parts by weight of the polymerizable compounds and the test results of the relevant performance parameters are shown as follows in Table 4.

TABLE-US-00004 TABLE 4 Formulation of the liquid crystal compositions of Comparative Examples 1-4 and Examples 1-8 and the test performances Comparative Example No. Example No. 1 2 3 4 1 2 3 4 5 6 7 8 Polymerizable RM-01 0.28 0.32 compound and its RM-02 0.28 0.28 content RM-03 0.01 RM-1 0.28 0.32 RM-2 0.28 0.28 RM-3 0.01 0.01 RM-4 0.28 RM-5 0.28 0.28 RM-6 0.28 RM-7 0.01 VHR (initial) (%) 93.24 93.94 94.24 93.76 94.42 95.13 95.53 94.42 94.36 95.1 95.53 94.52 VHR (UV) (%) 95.45 95.85 96.15 95.69 96.76 96.83 96.95 96.96 96.66 96.85 96.85 96.96 Ra (nm) 14.8 14.7 14.9 14.5 11.7 11.7 11.5 11.6 11.9 11.8 11.4 11.6 PTA1 (°) formed 100 s 88.88 88.83 88.78 88.72 88.44 88.42 88.35 88.3 88.42 88.41 88.42 88.36 after UV1 step for 120 s 87.85 87.74 87.65 87.56 87.4 87.4 87.37 87.3 87.4 87.5 87.4 87.37 different times 150 s 86.97 86.92 86.78 86.76 86.5 86.6 86.4 86.3 86.5 86.5 86.5 86.4 Residual content of polymerizable 208 210 227 198 148 139 114 148 157 141 147 124 compound after UV2 step for 90 min (ppm) Pretilt angle PTA (initial) 88.06 88.05 88.09 88.03 87.95 88.05 87.98 87.96 88.11 88.06 88.14 87.91 stability test PTA (24 h) 87.91 87.90 87.98 87.91 87.86 87.95 87.90 87.80 88.02 87.94 88.05 87.83 (°) PTA (72 h) 87.81 87.79 87.87 87.80 87.78 87.87 87.82 87.69 87.94 87.87 87.97 87.75 PTA (120 h) 87.67 87.68 87.67 87.69 87.71 87.81 87.75 87.68 87.87 87.82 87.90 87.69 PTA (168 h) 87.60 87.58 87.59 87.61 87.65 87.77 87.68 87.64 87.81 87.77 87.84 87.64 ΔPTA (168 h) 0.46 0.47 0.5 0.42 0.3 0.28 0.3 0.32 0.3 0.29 0.3 0.27

[0134] From Table 4, it can be seen that, when the host liquid crystal Host-1 is the same and only the polymerizable compounds are different, as compared to Comparative Examples 1-4 (liquid crystal compositions in the prior art), the liquid crystal compositions of the present invention have a higher voltage holding ratio (especially an excellent voltage holding ratio after UV irradiation), and a higher reliability; the polymer layer formed by the polymerizable compounds in the liquid crystal composition of the present invention has a lower surface roughness, and a higher uniformity. It can be seen from the data of PTA1 formed after the application of UV1 for different time to the liquid crystal composition that the liquid crystal composition of the present invention has a faster polymerization rate and a faster response speed; according to the test results of polymer residue, the liquid crystal composition of the present invention can achieve a lower residual polymer content and a faster response speed; according to the pretilt angle stability test results, after the generation of pretilt angel, the liquid crystal composition of the present invention shows a smaller change in the pretilt angle under the driving of voltage and thus has a better pretilt angle stability.

Comparative Examples 5-7 and Examples 9-16

[0135] The liquid crystal host mixture Host-2 is prepared according to each compound and weight percentage listed in Table 5 as follows.

TABLE-US-00005 TABLE 5 Formulation of the liquid crystal host mixture Host-2 and its test performances Code of Weight Formula Test results for the component percentage Code performance parameters 3PWO1 5.5 II-1 Cp 76.1 3PWO2 9.5 II-1 Δn 0.094 3CPWO2 6.5 II-2 Δε −3.3 3CWO2 14.5 III-1 K.sub.11 13.2 3CCWO2 9 III-2 K.sub.33 14.8 3CCWO3 7 III-2 γ.sub.1 91 2CCWO2 8 III-2 3CC2 10 M-1 4CC3 6 M-1 5CC3 6 M-1 3CCP1 10 M-12 3CCV1 8 M-1 Total 100

[0136] Polymerizable compounds RM-01, RM-02 and RM-03 are added into 100 parts by weight of Host-2 to form the compositions of Comparative Examples 5-7, and polymerizable compounds RM-1, RM-2, RM-3, RM-4, RM-5, RM-6 and RM-7 are added into 100 parts by weight of Host-2 to form the compositions of Examples 9-16. The specific parts by weight of the polymerizable compounds and the test results of the relevant performance parameters are shown as follows in Table 6.

TABLE-US-00006 TABLE 6 Formulation of the liquid crystal compositions of Comparative Examples 5-7 and Examples 9-16 and the test performances Comparative Example No. Example No. 5 6 7 9 10 11 12 13 14 15 16 Polymerizable RM-01 0.3 compound and its RM-02 0.3 0.28 content RM-03 0.02 RM-1 0.3 RM-2 0.3 0.35 0.28 RM-3 0.02 RM-4 0.3 RM-5 0.3 RM-6 0.3 0.28 RM-7 0.02 VHR (initial) (%) 93.95 93.34 93.76 94.43 95.14 95.53 94.42 94.4 95.15 95.57 94.5 VHR (UV) (%) 95.86 95.48 95.69 96.77 96.85 96.95 96.95 96.78 96.84 96.87 96.89 Ra (nm) 14.1 14.7 14.6 11.9 11.8 11.5 11.6 11.6 11.4 11.5 11.5 PTA1 (°) formed after 100 s 88.7 88.9 88.6 88.3 88.4 88.2 88.0 88.3 88.4 88.3 88.1 UV1 step for different 120 s 88.3 88.4 88.2 87.7 87.8 87.7 87.6 87.8 87.7 87.8 87.8 times 150 s 87.6 87.8 87.5 87.1 87.2 87.2 86.7 87.0 87.1 87.2 86.9 Residual content of polymerizable 185 234 179 137 134 164 111 139 145 136 117 compound after UV2 step for 90 min (ppm) Pretilt angle PTA (initial) 88.02 88.07 88.11 88.03 87.96 88.01 88.04 88.08 88.05 88.03 88.13 stability test (°) PTA (24 h) 87.88 87.96 88.04 87.95 87.88 87.94 87.97 88.03 88.00 87.95 88.09 PTA (72 h) 87.76 87.85 87.96 87.89 87.81 87.86 87.91 87.96 88.94 87.87 88.05 PTA (120 h) 87.66 87.70 87.76 87.83 87.73 87.82 87.84 87.87 87.86 87.82 88.02 PTA (168 h) 87.6 87.63 87.71 87.76 87.71 87.77 87.81 87.82 87.78 87.78 87.9 ΔPTA (168 h) 0.42 0.44 0.40 0.27 0.25 0.24 0.23 0.26 0.27 0.25 0.23

[0137] From Table 6, it can be seen that, when the host liquid crystal Host-2 is the same and only the polymerizable compounds are different, as compared to Comparative Examples 5-7 (liquid crystal compositions in the prior art), the liquid crystal compositions of the present invention have a higher voltage holding ratio (especially an excellent voltage holding ratio after UV irradiation), and a higher reliability; the polymer layer formed by the polymerizable compounds in the liquid crystal composition of the present invention has a lower surface roughness, and a higher uniformity. It can be seen from the data of PTA1 formed after the application of UV1 for different time to the liquid crystal composition that the liquid crystal composition of the present invention has a faster polymerization rate and a faster response speed; according to the test results of polymer residue, the liquid crystal composition of the present invention can achieve a lower residual polymer content and a faster response speed; according to the pretilt angle stability test results, after the generation of pretilt angel, the liquid crystal composition of the present invention shows a smaller change in the pretilt angle under the driving of voltage and thus has a better pretilt angle stability.

Comparative Examples 8-10 and Examples 17-24

[0138] The liquid crystal host mixture Host-3 is prepared according to each compound and weight percentage listed in Table 7 as follows.

TABLE-US-00007 TABLE 7 Formulation of the liquid crystal host mixture Host-3 and its test performances Code of Weight Formula Test results for the component percentage Code performance parameters 3C1OWO2 14 III-6 Cp 77 4C1OWO2 6 III-6 Δn 0.095 2CC1OWO2 4.5 III-7 Δε −3.1 3CC1OWO2 9.5 III-7 K.sub.11 14 3CCWO2 3.5 III-2 K.sub.33 14.4 3CPWO2 7 II-2 γ.sub.1 91 3CPO2 9 M-2 3CPP2 10.5 M-13 3CPPC3 1.5 M-22 3CC2 20 M-1 5CC2 3 M-1 4CC3 5 M-1 5PP1 4.5 M-3 3CGPC2 2 M-23 Total 100

[0139] Polymerizable compounds RM-01, RM-02 and RM-03 are added into 100 parts by weight of Host-3 to form the compositions of Comparative Examples 8-10, and polymerizable compounds RM-1, RM-2, RM-3, RM-4, RM-5, RM-6 and RM-7 are added into 100 parts by weight of Host-3 to form the compositions of Examples 17-24. The specific parts by weight of the polymerizable compounds and the test results of the relevant performance parameters are shown as follows in Table 8.

TABLE-US-00008 TABLE 8 Formulation of the liquid crystal compositions of Comparative Examples 8-10 and Examples 17-24 and the test performances Comparative Example No. Example No. 8 9 10 17 18 19 20 21 22 23 24 Polymerizable RM-01 0.3 compound and its RM-02 0.3 0.28 content RM-03 0.02 RM-1 0.3 RM-2 0.3 0.35 0.28 RM-3 0.02 RM-4 0.3 RM-5 0.3 RM-6 0.3 0.28 RM-7 0.02 VHR (initial) (%) 93.85 93.34 93.65 94.48 95.16 95.54 94.42 94.58 95.26 95.44 94.68 VHR (UV) (%) 95.66 95.48 95.57 96.76 96.83 96.95 96.56 96.76 96.73 96.75 96.96 Ra (nm) 14.7 14.6 14.8 12.5 11.7 11.6 12.4 11.5 11.9 11.8 12.4 PTA1 (°) formed 100 s 88.82 88.86 88.77 88.46 88.45 88.40 88.35 88.4 88.42 88.41 88.36 after UV1 step for 120 s 87.74 87.84 87.68 87.41 87.4 87.36 87.32 87.42 87.4 87.38 87.34 different times 150 s 86.92 86.98 86.86 86.52 86.5 86.47 86.4 86.49 86.5 86.49 86.43 Residual content of polymerizable 218 220 237 158 159 168 126 157 148 152 130 compound after UV2 step for 90 min (ppm) Pretilt angle PTA (initial) 88.05 88.06 88.03 87.98 88.05 87.98 87.96 88.01 88.06 88.04 87.97 stability test (°) PTA (24 h) 87.90 87.91 87.91 87.86 87.95 87.87 87.82 88.90 87.94 88.93 87.87 PTA (72 h) 87.79 87.81 87.80 87.78 87.86 87.80 87.74 87.82 87.87 87.82 87.78 PTA (120 h) 87.68 87.67 87.69 87.71 87.79 87.74 87.70 87.74 87.79 87.76 87.73 PTA (168 h) 87.6 87.59 87.6 87.67 87.73 87.69 87.68 87.69 87.75 87.72 87.7 ΔPTA (168 h) 0.45 0.47 0.43 0.31 0.32 0.29 0.28 0.32 0.31 0.32 0.27

[0140] From Table 8, it can be seen that, when the host liquid crystal Host-3 is the same and only the polymerizable compounds are different, as compared to Comparative Examples 8-10 (liquid crystal compositions in the prior art), the liquid crystal compositions of the present invention have a higher voltage holding ratio (especially an excellent voltage holding ratio after UV irradiation), and a higher reliability; the polymer layer formed by the polymerizable compounds in the liquid crystal composition of the present invention has a lower surface roughness, and a higher uniformity. It can be seen from the data of PTA1 formed after the application of UV1 for different time to the liquid crystal composition that the liquid crystal composition of the present invention has a faster polymerization rate and a faster response speed; according to the test results of polymer residue, the liquid crystal composition of the present invention can achieve a lower residual polymer content and a faster response speed; according to the pretilt angle stability test results, after the generation of pretilt angel, the liquid crystal composition of the present invention shows a smaller change in the pretilt angle under the driving of voltage and thus has a better pretilt angle stability.

[0141] In conclusion, the liquid crystal composition containing polymerizable compound provided herein has a higher VHR (especially an excellent VHR after UV irradiation), a lower surface roughness of the polymer layer, a faster polymerization rate, a lower residual amount of the polymerizable compound and a better pretilt angle stability, enables the production of a liquid crystal display device with a better voltage stability and a faster response speed, and can effectively reduce or prevent the occurrences of problems such as “burn-in”, “image sticking”, “Zara Particle” and “uneven display” in the liquid crystal display device. Therefore, the liquid crystal composition and the liquid crystal display device provided herein have high practical values.

[0142] The above embodiments are merely illustrative of the technical concepts and the features of the present invention, are included merely for purposes of illustration and implement of the present invention, and are not intended to limit the scope of the present invention. Equivalent variations or modifications are intended to be included within the scope of the present invention.