Polymerizable compound-containing liquid crystal composition and liquid crystal display device using the same

Abstract

A polymerizable compound-containing liquid crystal composition of the present invention relates to a liquid crystal composition containing a polymerizable compound represented by general formula (I) and a compound represented by general formula (II) and can be used for a liquid crystal display device imparted with liquid crystal aligning ability by polymerization. The polymerizable liquid crystal composition is required to cause no precipitation in a wide temperature range and have a low viscosity corresponding to fast switching, and a liquid crystal display device using the composition is required to have more stable alignment after polymerization and to cause no defect in display characteristics. In the present invention, the problems can be solved using a specified compound.

Claims

1. A polymerizable compound-containing liquid crystal composition comprising, as a first component, at least one polymerizable compound represented by general formula (I), ##STR00030## wherein in the formula, R.sup.1 and R.sup.2 each independently represent any of formulae (R-1) to (R-15) below, ##STR00031## ##STR00032## and X.sup.1 to X.sup.8 each independently represent a trifluoromethyl group, a trifluoromethoxy group, a fluorine atom, a chlorine atom, or a hydrogen atom, but at least one of X.sup.1 to X.sup.8 represents a fluorine atom and, at least one compounds represented by general formulae (IV-8) ##STR00033## wherein in the formula, R.sup.3 represents an alkyl group having 1 to 10 carbon atoms, wherein at least one hydrogen atom present in the group may be substituted by a fluorine atom, R.sup.4 represents an alkyl group or alkoxyl group having 1 to 10 carbon atoms, wherein at least one hydrogen atom present in the group may be substituted by a fluorine atom.

2. A polymerizable compound-containing liquid crystal composition, further comprising, as a second component, at least one compound represented by general formula (IV-10), ##STR00034## wherein in the formula, R.sup.3 represents an alkyl group having 1 to 10 carbon atoms, wherein at least one hydrogen atom present in the group may be substituted by a fluorine atom, R.sup.4 represents an alkyl group or alkoxyl group having 1 to 10 carbon atoms, wherein at least one hydrogen atom present in the group may be substituted by a fluorine atom.

3. The polymerizable compound-containing liquid crystal composition according to claim 1, wherein the general formula (I) is any one of general formula (I-1) to general formula (I-4), ##STR00035##

4. The polymerizable compound-containing liquid crystal composition according to claim 1, wherein the general formula (I) is the general formula (I-1).

5. The polymerizable compound-containing liquid crystal composition according to claim 1, wherein in the general formula (I), R.sup.1 and R.sup.2 are each independently formula (R-1) or (R-2).

6. The polymerizable compound-containing liquid crystal composition according to claim 1, further comprising, as a third component, at least one compound represented by general formula (III), ##STR00036## wherein in the formula, R.sup.9 represents the same meaning as R.sup.3 described in claim 1, R.sup.10 represents the same meaning as R.sup.4 described in claim 1.

7. The polymerizable compound-containing liquid crystal composition according to claim 1, wherein the content of the compound represented by the general formula (I) is 0.01% by mass to 2.0% by mass.

8. The polymerizable compound-containing liquid crystal composition according to claim 1, wherein the content of the compound represented by the general formula (III) is 5% by mass to 35% by mass.

9. The polymerizable compound-containing liquid crystal composition according to claim 1, wherein a dielectric constant anisotropy at 25 C. is in a range of 6.0 to 2.0, a refractive index anisotropy n at 25 C. is in a range of 0.08 to 0.13, a viscosity () at 20 C. is in a range of 10 to 30 mPa.Math.s, and a nematic-isotropic liquid phase transition temperature (T.sub.ni) is in a range of 60 C. to 120 C.

10. A liquid crystal display device comprising the polymerizable compound-containing liquid crystal composition according to claim 1.

11. The liquid crystal display device according to claim 10, wherein the liquid crystal display device is an active matrix drive liquid crystal device.

12. The liquid crystal display device according to claim 10, wherein the liquid crystal display device is of a PSA mode, a PSVA mode, a VA mode, an IPS mode, or an ECB mode.

13. The liquid crystal display device according to claim 10, wherein a pretilt angle is 85 to 89.9 degrees.

Description

EXAMPLES

(1) The present invention is described in further detail below with reference to examples, but the present invention is not limited to these examples. In a composition of each of the examples and comparative examples, % represents % by mass.

(2) In the examples, the measured characteristics are as follows.

(3) T.sub.ni: nematic-isotropic liquid phase transition temperature ( C.)

(4) n: refractive index anisotropy at 25 C.

(5) : dielectric constant anisotropy at 25 C.

(6) : viscosity at 20 C. (mPa.Math.s)

EXAMPLE 1

(7) A polymerizable compound-containing liquid crystal composition prepared and physical property values thereof are given below.

(8) ##STR00014## ##STR00015##

(9) The polymerizable compound-containing liquid crystal composition described in Example 1 contained 99.85% of the above-described liquid crystal composition and 0.15% of a polymerizable compound represented by general formula (I-11), and showed T.sub.ni: 75.5 C., n: 0.107, : 3.0, and : 17.5 mPa.Math.s.

(10) The polymerizable compound-containing liquid crystal composition was injected, by a vacuum injection method, into a cell with ITO having a cell gap of 3.5 m and a polyimide alignment film applied thereto for inducing homeotropic alignment. The liquid crystal composition was irradiated with ultraviolet rays for 600 seconds through a filter for cutting off ultraviolet rays of 320 nm or less while a rectangular wave of a frequency of 1 kHz and 1.8 V was applied using a high-pressure mercury vapor lamp adjusted so that the intensity of irradiation of a cell surface was 15 mW/cm.sup.2 to polymerize the polymerizable compound in the polymerizable compound-containing liquid crystal composition, thereby producing a homeotropic liquid crystal display device. The liquid crystal display device (PSVA mode) showed high contrast and was capable of fast switching. Also, the alignment regulating force of the polymerizable compound for the liquid crystal compound was confirmed by measuring a pretilt angle.

EXAMPLE 2

(11) A polymerizable compound-containing liquid crystal composition prepared and physical property values thereof are given below.

(12) ##STR00016## ##STR00017##

(13) The polymerizable compound-containing liquid crystal composition described in Example 2 contained 99.8% of the above-described liquid crystal composition and 0.2% of a polymerizable compound represented by general formula (I-11), and showed T.sub.ni: 75.5 C., n: 0.107, : 3.0, and : 17.5 mPa.Math.s.

(14) A liquid crystal display device (PSVA mode) using the polymerizable compound-containing liquid crystal composition showed high contrast and was capable of fast switching. Also, the alignment regulating force of the polymerizable compound for the liquid crystal compound was confirmed by measuring a pretilt angle.

EXAMPLE 3

(15) A polymerizable compound-containing liquid crystal composition prepared and physical property values thereof are given below.

(16) ##STR00018## ##STR00019##

(17) The polymerizable compound-containing liquid crystal composition described in Example 3 contained 99.65% of the above-described liquid crystal composition and 0.35% of a polymerizable compound represented by general formula (I-11), and showed T.sub.ni: 75.4 C., n: 0.107, : 3.0, and : 17.5 mPa.Math.s.

(18) A liquid crystal display device (PSVA mode) using the polymerizable compound-containing liquid crystal composition showed high contrast and was capable of fast switching. Also, the alignment regulating force of the polymerizable compound for the liquid crystal compound was confirmed by measuring a pretilt angle.

EXAMPLE 4

(19) A polymerizable compound-containing liquid crystal composition prepared and physical property values thereof are given below.

(20) ##STR00020## ##STR00021##

(21) The polymerizable compound-containing liquid crystal composition described in Example 4 contained 99.6% of the above-described liquid crystal composition and 0.4% of a polymerizable compound represented by general formula (I-11), and showed T.sub.ni: 75.4 C., n: 0.107, : 3.0, and : 17.5 mPa.Math.s.

(22) A liquid crystal display device (PSVA mode) using the polymerizable compound-containing liquid crystal composition showed high contrast and was capable of fast switching. Also, the alignment regulating force of the polymerizable compound for the liquid crystal compound was confirmed by measuring a pretilt angle.

COMPARATIVE EXAMPLE 1

(23) The polymerizable compound-containing liquid crystal composition prepared and physical property values thereof are given below.

(24) ##STR00022## ##STR00023##

(25) A polymerizable compound-containing liquid crystal composition described in Comparative Example 1 contained 99.8% of the liquid crystal composition of Example 1 and 0.2% of a polymerizable compound described in Japanese Unexamined Patent Application Publication No. 2003-307720.

(26) Each of the liquid crystal compositions of Examples 1 to 4 and Comparative Example 1 was subjected to a low-temperature storage test. As a result, Examples 1 to 4 maintained a nematic state at a temperature of any one of 40 C. and 25 C. for 2 or 3 weeks, while Comparative Example 1 maintained a nematic state only for 1 week, and precipitation was observed in the second week. This confirmed that Examples 1 to 4 maintain a nematic state within a wide temperature range and maintain stability at a low temperature over a long period of time of 2 or 3 times that of Comparative Example 1 and are very useful polymerizable compound-containing liquid crystal compositions.

(27) TABLE-US-00001 TABLE 1 Low-temperature storage test 40 C. 25 C. Example 1 Nematic state for 3 weeks Nematic state for 3 weeks Example 2 Nematic state for 3 weeks Nematic state for 3 weeks Example 3 Nematic state for 3 weeks Nematic state for 3 weeks Example 4 Nematic state for 2 weeks Nematic state for 3 weeks Comparative Nematic state for 1 week Nematic state for 1 week Example 1

COMPARATIVE EXAMPLE 2

(28) A polymerizable compound-containing liquid crystal composition prepared and physical property values thereof are given below.

(29) ##STR00024## ##STR00025##

(30) The polymerizable compound-containing liquid crystal composition described in Comparative Example 2 contained 99.8% of the liquid crystal composition not containing compounds represented by the general formulae (II-A) and (II-B) of the present invention and 0.2% of a polymerizable compound described in Japanese Unexamined Patent Application Publication No. 2003-307720, and showed T.sub.ni: 76.4 C., n: 0.107, : 2.9, and : 21.2 mPa.Math.s. It is easily supposed that since the viscosity is significantly increased, the switching speed is significantly worsened when a liquid crystal device is manufactured. A liquid crystal display device (PSVA mode) using the polymerizable compound-containing liquid crystal composition showed high contrast but showed a low switching speed and impracticality. Also, the alignment regulating force of the polymerizable compound for the liquid crystal compound was confirmed by measuring a pretilt angle.

EXAMPLE 5

(31) A polymerizable compound-containing liquid crystal composition prepared and physical property values thereof are given below.

(32) ##STR00026## ##STR00027##

(33) The polymerizable compound-containing liquid crystal composition described in Example 5 contained 99.8% of the above-described liquid crystal composition and 0.2% of a polymerizable compound represented by general formula (I-11), and showed T.sub.ni: 76.4 C., n: 0.092, : 2.9, and : 18.6 mPa.Math.s.

(34) A liquid crystal display device (PSVA mode) using the polymerizable compound-containing liquid crystal composition showed high contrast and was capable of fast switching. Also, the alignment regulating force of the polymerizable compound for the liquid crystal compound was confirmed by measuring a pretilt angle.

EXAMPLE 6

(35) A polymerizable compound-containing liquid crystal composition prepared and physical property values thereof are given below.

(36) ##STR00028## ##STR00029##

(37) The polymerizable compound-containing liquid crystal composition described in Example 6 contained 99.8% of the above-described liquid crystal composition and 0.2% of a polymerizable compound represented by general formula (I-11), and showed T.sub.ni: 76.3 C., n: 0.091, : 2.7, and : 18.4 mPa.Math.s.

(38) A liquid crystal display device (PSVA mode) using the polymerizable compound-containing liquid crystal composition showed high contrast and was capable of fast switching. Also, the alignment regulating force of the polymerizable compound for the liquid crystal compound was confirmed by measuring a pretilt angle.

(39) Therefore, it was confirmed that the polymerizable compound-containing liquid crystal composition of the present invention maintains a nematic state over a wide temperature range, and the liquid crystal display device using the liquid crystal composition exhibits fast switching.

INDUSTRIAL APPLICABILITY

(40) The present invention is useful as a liquid crystal composition for a liquid crystal display device.