Liquid crystal composition

Abstract

A liquid crystal composition, a liquid crystal film and a display device are provided. The liquid crystal composition can be uniformly aligned with no problems such as dewetting in an operation of aligning horizontally alignable liquid crystals. Also, a state of the aligned liquid crystal compound can be stably maintained.

Claims

1. A liquid crystal film comprising a liquid crystal layer including a liquid crystal composition, the liquid crystal composition comprising: a horizontally alignable liquid crystal compound; and an amine compound represented by Formula 3: ##STR00009## wherein the amine compound is a compound in which, in Formula 3, each of L1 and L2 is a single bond, R16 and R17 are each independently an alkyl group having 1 to 12 carbon atoms, or the amine compound is a compound in which, in Formula 3, each of R16 and R17 is -L3-Si(R18).sub.n(OR19).sub.3-n, and L1 and L2 are each independently a single bond or an alkylene group having 1 to 12 carbon atoms, with the proviso that L3 is an alkylene group having 1 to 12 carbon atoms, and R18 and R19 are each independently an alkyl group having 1 to 12 carbon atoms and n is an integer ranging from 0 to 2, or the amine compound is a compound in which, in Formula 3, R16 is an alkyl group having 1 to 12 carbon atoms, each of L1 and L2 is a single bond, and R17 is -L3-Si(R18).sub.n(OR19).sub.3-n, wherein L3 is an alkylene group having 1 to 12 carbon atoms, and R18 and R19 are each independently an alkyl group having 1 to 12 carbon atoms and n is an integer ranging from 0 to 2, wherein an optical axis of the liquid crystal layer comprising the liquid crystal compound has an inclination angle of 0 to 25 with respect to a plane of the liquid crystal layer, wherein the liquid crystal film satisfies the requirements of General Formula 1:
X<8%[General Formula 1] wherein X represents a percentage (%) of the absolute value of a variation in phase difference value of the liquid crystal layer formed of the liquid crystal composition after the liquid crystal layer is kept at 80 C. for 100 hours, based on an initial phase difference value of the liquid crystal layer, and wherein X is calculated by the formula, 100(|R.sub.oR.sub.1|)/R.sub.o, wherein R.sub.o is the initial phase difference value of the liquid crystal layer, and R.sub.1 represents a phase difference value of the liquid crystal layer after the liquid crystal layer is kept at 80 C. for 100 hours.

2. The liquid crystal film of claim 1, wherein the horizontally alignable liquid crystal compound comprises a multifunctional polymerizable liquid crystal compound and a monofunctional polymerizable liquid crystal compound.

3. The liquid crystal film of claim 2, wherein the monofunctional polymerizable liquid crystal compound is comprised at a content of greater than 0 parts by weight and not more than 100 parts by weight, based on 100 parts by weight of the multifunctional polymerizable liquid crystal compound.

4. The liquid crystal film of claim 1, wherein the horizontally alignable liquid crystal compound is represented by Formula 1: ##STR00010## wherein A is a single bond, COO or OCO, and R.sub.1 to R.sub.10 are each independently hydrogen, a halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group, O-Q-P or a substituent of Formula 2, or a pair of two adjacent substituents of R.sub.1 to R.sub.5 or a pair of two adjacent substituents of R.sub.6 to R.sub.10 are joined together to form a benzene ring substituted with O-Q-P, with the proviso that at least one of the substituents R.sub.1 to R.sub.10 is O-Q-P or the substituent of Formula 2, or at least one of the pair of two adjacent substituents of R.sub.1 to R.sub.5 and the pair of two adjacent substituents of R.sub.6 to R.sub.10 are joined together to form a benzene ring substituted with O-Q-P, wherein Q is an alkylene group or an alkylidene group, and P is an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group: ##STR00011## wherein B is a single bond, COO or OCO, and R.sub.11 to R.sub.15 are each independently hydrogen, a halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group or O-Q-P, or a pair of two substituents of R.sub.11 to R.sub.15 are joined together to form a benzene ring substituted with O-Q-P, with the proviso that at least one of the substituents R.sub.11 to R.sub.15 is O-Q-P, or two adjacent substituents of R.sub.11 to R.sub.15 are joined together to form a benzene ring substituted with O-Q-P, wherein Q is an alkylene group or an alkylidene group, and P is an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group, and wherein the symbol ##STR00012## means that a portion of the symbol is connected to a mother compound.

5. The liquid crystal film of claim 1, wherein the liquid crystal composition further comprises a photopolymerization initiator.

6. The liquid crystal film of claim 1, which further comprises a substrate layer and wherein the liquid crystal layer is formed on one surface of the substrate layer.

7. The liquid crystal film of claim 6, wherein the substrate layer is an optically isotropic substrate layer, an optically anisotropic substrate layer or a polarizing element.

8. A display device comprising the liquid crystal film according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram showing a liquid crystal film according to one exemplary embodiment;

(2) FIG. 2 is a photograph showing a liquid crystal layer prepared in Example 1; and

(3) FIG. 3 is a photograph showing a liquid crystal layer prepared in Comparative Example 1.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(4) Hereinafter, exemplary embodiments of the liquid crystal composition will be described in detail. However, the liquid crystal composition is not limited to the embodiments disclosed below.

Example 1

(5) A surface of a TAC substrate layer (refractive index: 1.49, thickness: 80,000 nm) was coated with a composition for forming a photoalignment layer so that a thickness of a coating layer after drying could amount to approximately 1,000 , and dried at 80 C. for 2 minutes in an oven. A composition (polynorbornene:acrylic monomer:photoinitiator=2:1:0.25 (based on the weight ratio)), which was prepared by mixing a photoinitiator (Irgacure 907) with a mixture of an acrylic monomer and polynorbornene (molecular weight (M.sub.w)=150,000) having a cinnamate group of the following Formula A and dissolving the resulting mixture in a toluene solvent so that a solid concentration of the polynorbornene could amount to 2% by weight, was used as the composition for forming a photoalignment layer.

(6) ##STR00007##

(7) The dried composition for forming a photoalignment layer was subjected to alignment treatment to form a photoalignment layer. A wire grid polarizing plate that can generate linearly polarized light in a predetermined direction was disposed on the dried composition. Thereafter, the dried composition was aligned by irradiating the composition with UV rays (300 mW/cm.sup.2) for approximately 30 seconds while transferring the TAC substrate layer at a rate of approximately 3 m/min. Then, a liquid crystal layer was formed on the alignment layer undergoing the alignment treatment. As the liquid crystal composition, a liquid crystal composition including 70 parts by weight of a multifunctional polymerizable liquid crystal compound represented by the following Formula B, 30 parts by weight of a monofunctional polymerizable liquid crystal compound represented by the following Formula C, 3-propyl amine as an amine compound, which was present at a content of 0.5 parts by weight based on 100 parts by weight of the multifunctional and monofunctional polymerizable liquid crystal compounds, and a suitable amount of a photoinitiator was coated to a drying thickness of approximately 1 m, and the liquid crystal composition was aligned according to alignment of the alignment layer disposed under the liquid crystal layer. Then, a liquid crystal layer, which included a horizontally aligned liquid crystal compound aligned according to the alignment of the photoalignment film disposed under the liquid crystal layer, was formed by irradiating the liquid crystals with UV rays (300 mW/cm.sup.2) for approximately 10 seconds. A photograph taken of the liquid crystal layer formed as described above is shown in FIG. 2.

(8) ##STR00008##

Example 2

(9) A liquid crystal film was manufactured in the same manner as in Example 1, except that 55 parts by weight of the multifunctional polymerizable liquid crystal compound represented by Formula B and 45 parts by weight of the monofunctional polymerizable liquid crystal compound represented by Formula C were mixed during preparation of the liquid crystal composition.

Example 3

(10) A liquid crystal film was manufactured in the same manner as in Example 1, except that 3-dimethylaminopropyl amine was used as the amine compound at a content of 0.7 parts by weight, based on 100 parts by weight of the multifunctional and monofunctional polymerizable liquid crystal compounds.

Example 4

(11) A liquid crystal film was manufactured in the same manner as in Example 1, except that diethyl amine was used as the amine compound at a content of 1 part by weight, based on 100 parts by weight of the multifunctional and monofunctional polymerizable liquid crystal compounds.

Example 5

(12) A liquid crystal film was manufactured in the same manner as in Example 1, except that 3-(N-propylamino)propyl trimethoxy silane was used as the amine compound at a content of 0.5 parts by weight, based on 100 parts by weight of the multifunctional and monofunctional polymerizable liquid crystal compounds.

Comparative Example 1

(13) A liquid crystal film was manufactured in the same manner as in Example 1, except that the amine compound was not used during preparation of the liquid crystal composition. A photograph taken of the prepared liquid crystal layer is shown in FIG. 3.

Experimental Example 1: Evaluation of Durability of Liquid Crystal Layer

(14) The durability of a liquid crystal layer was evaluated by measuring a variation of a phase difference value caused after a durability test of the liquid crystal layers prepared in Examples and Comparative Examples. More particularly, a liquid crystal film was cut into pieces having a size of 10 cm10 cm (widthlength), thereby preparing a test sample. The test sample was then kept under a heat-resistant condition of 80 C. for 100 hours or 250 hours. Then, a decrease in phase difference values of the liquid crystal layer before and after being kept under the heat-resistant condition was calculated as the percentage (%), and evaluated according to the following evaluation criteria. As such, the phase difference value was measured at a wavelength of 550 nm according to the manufacturer's manual using Axoscan (commercially available from Axomatrix). The durability evaluation results are as follows: it is marked by O when variations in phase difference values of the liquid crystal layers after being kept under a heat-resistant condition for 100 hours and 250 hours were less than 8%, and X when a variation in phase difference value of any one of the liquid crystal layers after being kept under a heat-resistant condition for 100 hours and 250 hours was 8% or more. The evaluation results are summarized in the following Table 1.

(15) TABLE-US-00001 TABLE 1 Durability of liquid crystal layer Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 X