Liquid crystal device

Abstract

A liquid crystal device, a precursor composition, a method of manufacturing a liquid crystal device, an apparatus of manufacturing a liquid crystal device, and use of the liquid crystal device are provided. A device capable of being driven at a low driving voltage can be provided. The device can be realized so that the device can be driven in a normally transparent mode or a normally black mode. Also, the device has other excellent characteristics such as a contrast ratio. Such a liquid crystal device can be applied to various light modulation devices such as smart windows, window-protecting films, flexible display devices, active retarders for displaying 3D images, or viewing angle-adjusting films.

Claims

1. A liquid crystal device comprising a liquid crystal layer, wherein the liquid crystal layer comprises: a polymer network of a precursor comprising a silicon compound; and a liquid crystal compound present in a state dispersed in the polymer network, and an alignment film disposed adjacent to the liquid crystal layer, wherein the liquid crystal device further comprises polarizing layers disposed at both sides of the liquid crystal layer, wherein the light absorption axes of the two polarizing layers form an angle ranging from 80 to 100 with respect to each other, and the liquid crystal layer is initially aligned to form an angle ranging from 40 to 50 with respect to the light absorption axes of the two polarizing layers, wherein the liquid crystal device is driven in a normally transparent mode, wherein a haze is 10% or less and a light transmittance is 80% or more in a transparent mode of the liquid crystal device, wherein the silicon compound is represented by the following Formula 1 or 2, and wherein the liquid crystal compound is present in the liquid crystal layer in a state in which the liquid crystal compound is ordered in an initial state in one direction: ##STR00024## where in Formula 1 or Formula 2, n is an integer ranging from 0 to 10, m is an integer ranging from 2 to 8, X is O or NW, and R.sub.1 to R.sub.6 are each independently an alkyl group, an alkoxy group, an aryl group, a polymerizable functional group, -A-R.sub.7 or -L-Si(R.sub.8).sub.p(R.sub.9).sub.(3-p), wherein A and L are each independently an alkylene group, an alkynylene group, an arylene group, an alkenylene group, an alkylidene group, O or NW, R.sub.7 is an alkyl group, an alkoxy group, an aryl group or a polymerizable functional group, R.sub.8 is a polymerizable functional group, R.sub.9 is an alkyl group, an alkoxy group or an aryl group, p is an integer ranging from 0 to 3, and W is hydrogen or an alkyl group.

2. The liquid crystal device of claim 1, wherein the precursor further comprises a compound represented by one of the following Formulas 3 or 5: ##STR00025## where in Formula 3, R each independently represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and X represents an alkylene group or an alkylidene group having 1 to 20 carbon atoms; and in Formula 5, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and X represents an alkyl group having 1 to 20 carbon atoms.

3. The liquid crystal device of claim 1, which satisfies the following Expression A:
(1a){(2n.sub.o.sup.2+n.sub.e.sup.2)/3}.sup.0.5n.sub.p(1+a)n.sub.e[Expression A] where in Expression A, a is a number ranging from 0 to 0.5, n.sub.o represents an ordinary refractive index of the liquid crystal compound, n.sub.e represents an extraordinary refractive index of the liquid crystal compound, and n.sub.p represents a refractive index of the polymer network.

4. The liquid crystal device of claim 1, wherein the liquid crystal compound satisfies the following Expression B:
(n.sub.e+n.sub.o)/2b{(2n.sub.o.sup.2+n.sub.e.sup.2)/3}.sup.0.5(n.sub.e+n.sub.o)/2+b[Expression B] where in Expression B, n.sub.e represents an extraordinary refractive index of the liquid crystal compound, n.sub.o represents an ordinary refractive index of the liquid crystal compound, and b is a number ranging from 0.1 to 1.

5. The liquid crystal device of claim 1, wherein the liquid crystal layer comprises the polymer network at 5 to 70 parts by weight and the liquid crystal compound at 30 to 95 parts by weight.

6. The liquid crystal device of claim 1, which satisfies the following Expression C:
247 nm{d(n.sub.en.sub.o)}A302 nm[Expression C] where in Expression C, d represents a thickness (units: nm) of the liquid crystal layer, n.sub.e represents an extraordinary refractive index of the liquid crystal compound, n.sub.o represents an ordinary refractive index of the liquid crystal compound, and A represents a ratio (L/T) of the weight (L) of the liquid crystal compound with respect to the sum (T) of the weights of the polymer network and the liquid crystal compound, or a ratio (VL/TV) of the volume (VL) of the liquid crystal compound with respect to the total volume (TV) of the liquid crystal layer.

7. The liquid crystal device of claim 1, wherein a voltage required to realize a light transmittance of 10% in the normally transparent mode is less than or equal to 60 V.

8. A light modulation device comprising the liquid crystal device defined in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1 and 2 are diagrams showing exemplary liquid crystal devices; and

(2) FIGS. 3 and 4 are diagrams showing exemplary methods of manufacturing a liquid crystal device.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(3) Hereinafter, the present invention will be described with reference to Examples and Comparative Examples in detail. However, the scope of the present invention is not limited to the following Examples.

Example 1

(4) Formation of Alignment Film

(5) A polynorbornene having a repeating unit represented by the following Formula A (PNBCi; weight average molecular weight: 85,000, and polydispersity index (PDI): approximately 4.75) and a photoinitiator (Igacure 907; polynorbornene:photoinitiator=2:0.25 (based on the weight)) were dissolved in toluene so that a solid content of the polynorbornene solid content amounted to 2% by weight, thereby preparing a precursor for alignment films. An electrode layer of a polycarbonate (PC) film (i.e., an substrate layer) having an ITO transparent electrode layer formed on a surface thereof was coated with the precursor, and the precursor was irradiated with linearly polarized UV rays (1,200 mJ/cm.sup.2) by means of a wire grid polarizer (WGP) to form an alignment film.

(6) ##STR00005##

(7) Preparation of Precursor Composition for Liquid Crystal Layer and Manufacture of Device

(8) 70 parts by weight of a compound (HDDA) represented by the following Formula B and 30 parts by weight of a silicon compound represented by the following Formula C were mixed to prepare a precursor. Thereafter, 10 parts by weight of the precursor and 90 parts by weight of a liquid crystal compound (ZGS-8017, JNC, extraordinary refractive index: approximately 1.597, and ordinary refractive index: approximately 1.487) were mixed, and the resulting mixture was dissolved in a toluene solvent together with a proper amount of an initiator to prepare a precursor composition. Subsequently, a surface of the prepared alignment film was coated with the precursor composition. A surface of an alignment film of a PC film having the alignment film formed on one surface thereof in the same manner as described in the contents for forming an alignment film was deposited on the coated composition so that the surface of the alignment film came in contact with the coating layer, and the coated composition was irradiated with UV rays (300 mW/cm.sup.2) to form a liquid crystal layer. Then, two polarizing plates (PVA-based polarizing plates) were disposed at both external sides of the PC film so that the directions of the light absorption axes were perpendicular to each other. In this procedure, the light absorption axes of the polarizing plates were set to form an angle of 45 with respect to the alignment direction of the alignment film of the PC film.

(9) ##STR00006##

Example 2

(10) A device was manufactured in the same manner as in Example 1, except that 30 parts by weight of a compound represented by the following Formula D was mixed with 70 parts by weight of the compound of Formula B to prepare a precursor.

(11) ##STR00007##

Example 3

(12) A device was manufactured in the same manner as in Example 1, except that 50 parts by weight of a compound represented by the following Formula E was mixed with 50 parts by weight of the compound of Formula B to prepare a precursor.

(13) ##STR00008##

Example 4

(14) A device was manufactured in the same manner as in Example 3, except that 45 parts by weight of the compound of Formula E and 45 parts by weight of the compound of Formula B were mixed with 10 parts by weight of a compound represented by the following Formula F to prepare a precursor.

(15) ##STR00009##

Example 5

(16) A device was manufactured in the same manner as in Example 3, except that 45 parts by weight of the compound of Formula E and 45 parts by weight of the compound of Formula B were mixed with 10 parts by weight of a compound represented by the following Formula G to prepare a precursor.

(17) ##STR00010##

Example 6

(18) A device was manufactured in the same manner as in Example 3, except that 40 parts by weight of the compound of Formula E and 40 parts by weight of the compound of Formula B were mixed with 20 parts by weight of the compound of Formula G to prepare a precursor.

Example 7

(19) A device was manufactured in the same manner as in Example 3, except that 80 parts by weight of the compound of Formula E, 10 parts by weight of the compound of Formula F, and 10 parts by weight of the compound of Formula G were mixed to prepare a precursor.

Example 8

(20) A device was manufactured in the same manner as in Example 3, except that 70 parts by weight of the compound of Formula B and 30 parts by weight of the compound of Formula G were mixed to prepare a precursor.

Example 9

(21) A device was manufactured in the same manner as in Example 1, except that 60 parts by weight of the compound of Formula B, 30 parts by weight of the compound of Formula E and 10 parts by weight of the compound of Formula F were mixed to prepare a precursor.

Example 10

(22) A device was manufactured in the same manner as in Example 1, except that 60 parts by weight of the compound of Formula B, 30 parts by weight of the compound of Formula E and 10 parts by weight of the compound of Formula G were mixed to prepare a precursor.

Example 11

(23) A device was manufactured in the same manner as in Example 1, except that 50 parts by weight of the compound of Formula E and 50 parts by weight of the compound of Formula F were mixed to prepare a precursor.

Example 12

(24) A device was manufactured in the same manner as in Example 1, except that 80 parts by weight of the compound of Formula E and 20 parts by weight of the compound of Formula F were mixed to prepare a precursor.

Example 13

(25) A device was manufactured in the same manner as in Example 1, except that 50 parts by weight of the compound of Formula E was mixed with 50 parts by weight of a compound represented by Formula H to prepare a precursor.

(26) ##STR00011##

Example 14

(27) A device was manufactured in the same manner as in Example 13, except that 80 parts by weight of the compound of Formula E and 20 parts by weight of the compound of Formula H were mixed to prepare a precursor.

Example 15

(28) A device was manufactured in the same manner as in Example 13, except that 20 parts by weight of the compound of Formula E and 80 parts by weight of the compound of Formula H were mixed to prepare a precursor.

Example 16

(29) A device was manufactured in the same manner as in Example 1, except that 50 parts by weight of a compound represented by the following Formula I was mixed with 50 parts by weight of the compound of Formula E to prepare a precursor.

(30) ##STR00012##

Example 17

(31) A device was manufactured in the same manner as in Example 1, except that 50 parts by weight of a compound represented by the following Formula J was mixed with 50 parts by weight of the compound of Formula E to prepare a precursor.

(32) ##STR00013##

Example 18

(33) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B and 10 parts by weight of the compound of Formula C were mixed to prepare a precursor.

Example 19

(34) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B and 10 parts by weight of the compound of Formula D were mixed to prepare a precursor.

Example 20

(35) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B was mixed with 10 parts by weight of a compound represented by the following Formula K to prepare a precursor.

(36) ##STR00014##

Example 21

(37) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B and 10 parts by weight of the compound of Formula I were mixed to prepare a precursor.

Example 22

(38) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B and 10 parts by weight of the compound of Formula E were mixed to prepare a precursor.

Example 23

(39) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B and 10 parts by weight of the compound of Formula H were mixed to prepare a precursor.

Example 24

(40) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B and 10 parts by weight of the compound of Formula L were mixed to prepare a precursor.

(41) ##STR00015##

Example 25

(42) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B and 10 parts by weight of the compound of Formula J were mixed to prepare a precursor.

Example 26

(43) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B was mixed with 10 parts by weight of a compound represented by the following Formula M to prepare a precursor.

(44) ##STR00016##

Example 27

(45) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B was mixed with 10 parts by weight of a compound represented by the following Formula N to prepare a precursor.

(46) ##STR00017##

Example 28

(47) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B was mixed with 10 parts by weight of a compound represented by the following Formula O to prepare a precursor.

(48) ##STR00018##

Example 29

(49) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B was mixed with 10 parts by weight of a compound represented by the following Formula P to prepare a precursor.

(50) ##STR00019##

Example 30

(51) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B was mixed with 10 parts by weight of a compound represented by the following Formula Q to prepare a precursor.

(52) ##STR00020##

Example 31

(53) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B was mixed with 10 parts by weight of a compound represented by the following Formula R to prepare a precursor.

(54) ##STR00021##

Example 32

(55) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B and 10 parts by weight of the compound of Formula F were mixed to prepare a precursor.

Example 33

(56) A device was manufactured in the same manner as in Example 1, except that 90 parts by weight of the compound of Formula B and 10 parts by weight of the compound of Formula G were mixed to prepare a precursor.

Comparative Example 1

(57) A device was manufactured in the same manner as in Example 1, except that only a compound represented by the following Formula S was mixed with the liquid crystal compound and the initiator to prepare a precursor.

(58) ##STR00022##

Comparative Example 2

(59) A device was manufactured in the same manner as in Example 1, except that only a compound represented by the following Formula T was mixed with the liquid crystal compound and the initiator to prepare a precursor.

(60) ##STR00023##

Experiment Example 1: Confirmation of Alignment

(61) Each of the liquid crystal layers prepared in Examples was positioned between two polarizing plates whose light absorption axes were arranged perpendicularly to each other, and the alignability was evaluated by determining whether the device can switch between a transparent (white) mode and a black mode. When the device switched between the transparent mode and the black mode in the process, it could be seen that the liquid crystal compound in the polymer network was aligned in the liquid crystal layer. As a result, it was confirmed that the switching between the transparent mode and the black mode was observed in the case of all Examples, but was not observed in the case of Comparative Examples.

Experiment Example 2: Evaluation of Driving Voltage

(62) An AC power source was connected to ITO transparent electrode layers of upper and lower substrate layers of each of the devices manufactured Examples and Comparative Examples, and the driving voltage required to drive each of the devices was measured whiling driving the devices. The driving voltage was measured at a point of time where the switching was blocked to the maximum when a device formed in a normally transparent mode switched to a black mode by application of voltage.

(63) The measurement results on such driving voltages are listed in the following Table 1.

(64) TABLE-US-00001 TABLE 1 Driving voltage (Unit: Volt) Examples 1 9.1 2 12.0 3 18.2 4 17.0 5 16.1 6 14.5 7 14.0 8 28.0 9 20.0 10 21.0 11 9.5 12 9.1 13 10.0 14 9.5 15 10.5 16 11.0 17 10.9 18 20 19 23 20 23 21 30 22 40 23 32 24 30 25 35 26 40 27 42 28 38 29 40 30 35 31 32 32 32 33 34 Comparative 2 103 Examples 3 105

DESCRIPTION OF THE MARKS IN DRAWINGS

(65) 101: alignment film 102: liquid crystal layer 1021: polymer network 1022: liquid crystal region 201A, 201B: substrate layer