Liquid crystal composition

Abstract

A liquid crystal composition and a method of manufacturing an optical film. The liquid crystal composition which may form a liquid crystal layer having excellent optical characteristics and a high surface hardness. The liquid crystal layer formed as described above may be used in various applications, and for example, may be disposed on the outermost surface of a display device, such as an LCD or an OLED, or at an outer side of a polarizing layer of the display in which the polarizing layer is disposed at a visible side, thereby serving as a liquid crystal layer which may solve a problem of degrading brightness occurring when an observer watches an image with polarizing sunglasses.

Claims

1. A liquid crystal composition which comprises a polymerizable liquid crystal material comprising a multifunctional polymerizable liquid crystal compound and a monofunctional polymerizable liquid crystal compound and a reactive non-liquid crystal compound comprising at least two functional groups capable of reacting with the polymerizable liquid crystal compound and which is configured to form a layer, of which a surface hardness is 1H or more, by being cured in an aligned state, wherein an amount of the multifunctional polymerizable liquid crystal compound in the polymerizable liquid crystal material is 45 to 90 weight %, wherein the reactive non-liquid crystal compound is comprised in an amount of 5 parts by weight or less relative to 100 parts by weight of the polymerizable liquid crystal material, wherein the multifunctional liquid crystal compound comprises a liquid crystal compound having two polymerizable functional groups and a liquid crystal compound having three or more polymerizable functional groups, and wherein an amount of the liquid crystal compound having three or more polymerizable functional groups in the liquid crystal material is 8 to 20 weight %.

2. The composition according to claim 1, wherein the reactive non-liquid crystal compound comprises at least four functional groups capable of reacting with the polymerizable liquid crystal compound.

3. The composition according to claim 2, wherein the non-liquid crystal compound is a compound comprising at least four functional groups capable of reacting with the polymerizable liquid crystal compound, and having a molecular weight or weight average molecular weight of 200 to 5,000 or 200 to 1,000.

4. The composition according to claim 1, which is configured to form a layer, of which a surface hardness is 2 H or more, by being cured.

5. The composition according to claim 1, which is configured to form a layer, of which a sheet resistance is 10.sup.12 or less.

6. The composition according to claim 5, further comprising an antistatic agent.

7. A method of manufacturing an optical film, comprising: forming a layer of the liquid crystal composition of claim 1 on an alignment layer; and polymerizing the liquid crystal compound under a state where it is aligned.

8. The method according to claim 7, wherein the alignment layer comprises an antistatic agent.

9. The method according to claim 7, wherein the layer of the liquid crystal composition comprises an antistatic agent.

10. The method according to claim 7, wherein the alignment layer is formed on a base layer, and an antistatic layer is between the alignment layer and the base layer.

Description

ILLUSTRATIVE EMBODIMENTS

(1) Hereinafter, an optical film will be described in detail with reference to Examples and Comparative Examples, but the scope of the optical film is not limited to the following Examples.

(2) 1. Measurement of Surface Hardness

(3) A surface hardness of liquid crystal layers formed in Examples and Comparative Examples was measured at a pencil weight of 500 g and a pencil moving rate of 250 mm/min according to ASTM D3363.

(4) 2. Measurement of Retardation

(5) Retardation was measured using light with a wavelength of 550 or 589 nm. Sixteen Muller matrixes of retardation films were subjected to measurement of retardation according to a manufacturer's manual using equipment capable of measuring sixteen Muller matrixes, Axoscan (Axomatrics), and thus the retardation was extracted.

(6) 3. Measurement of Sheet Resistance

(7) Sheet resistance was measured using a sheet resistance measurer, HIRESTA-UP (MCP-HT450; Mitsubishi Chemical), according to a manufacturer's manual.

(8) 4. Evaluation of Alignment Property

(9) Aligning properties of liquid crystals in Examples and Comparative Examples were evaluated by placing a liquid crystal layer between two polarizers whose light absorption axes were perpendicular to each other, and observing retardation expressed by a liquid crystal film and its uniformity while irradiating light to one surface.

(10) Structures of polymerizable liquid crystal compounds and reactive non-liquid crystal compounds used in Examples and Comparative Examples were as follows.

(11) Polymerizable Liquid Crystal Compound

(12) ##STR00005##

(13) Reactive Non-Liquid Crystal Compound

(14) ##STR00006##

Examples 1 to 4 and Comparative Examples 1 to 4

(15) A coating solution for forming an alignment layer was prepared by dissolving 20 g of a photoreactive polymer, 5-norbornene-2-methyl-(4-methoxy cinnamate), 20 g of dipentaerythritol hexaacrylate, and 5 g of a photoinitiator (Irgacure OXE02, Ciba-Geigy (Swiss)) in 980 g of cyclopentanone, the coating solution was coated on a triacetyl cellulose (TAC) film to have a thickness after drying of approximately 1,000 , and dried with hot wind in a dry oven at 70 C. for 2 minutes, thereby forming a layer. Subsequently, the TAC film having the layer was transferred in one direction, and exposed once at a rate of 3 m/min while irradiating linearly-polarized UV rays to the film using a high pressure mercury lamp (80 w/cm) as a light source and a wire grid polarizing plate (Moxtek), thereby providing an alignment property.

(16) Afterward, a coating solution for forming a liquid crystal layer was prepared by dissolving a mixture prepared by blending 5 parts by weight of a photoinitiator (Irgacure 907, Ciba-Geigy (Swiss)) in 95 parts by weight of a mixture prepared by blending a polymerizable liquid crystal compound in a composition ratio shown in Table 1, and in case, further blending a reactive non-liquid crystal compound, in toluene to have a solid content of approximately 25 weight %. Afterward, the coating solution was coated on the alignment layer to have a thickness after drying of approximately 1 m, and dried with hot wind in a dry oven at 60 C. for 2 minutes. Then, UV rays were irradiated using a high pressure mercury lamp (80 w/cm) at 300 mJ/cm.sup.2, and the coating solution was cured, thereby forming a liquid crystal layer.

(17) TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 4 1 2 3 4 RM RM B 50 45 48.5 43.5 100 70 47.5 47.5 material com- D 50 45 48.5 43.5 30 47.5 47.5 pound G 10 10 Reactive J 5 non-liquid crystal K 3 3 5 compound Content Unit: g

(18) Results for evaluating physical properties with respect to Examples and Comparative Examples are summarized in Table 2.

(19) TABLE-US-00002 TABLE 2 Example Comparative Example 1 2 3 4 1 2 3 4 Surface hardness 1H 2H 2H 3H 2B 1B 1H 2H Aligning X X properties In-plane approximately 120 to 130 approximately 120 to 130 retardation (nm) Alignment property: : aligned, X: not aligned

Example 5

(20) A liquid crystal layer was formed through the same process as described in Example 1, except that an antistatic agent (Methacroylcholine Chloride, TCI) was added to a mixture of a polymerizable liquid crystal compound and a reactive non-liquid crystal compound to have a concentration of 3 weight %.

Example 6

(21) A liquid crystal layer was formed through the same process as described in Example 1, except that a cyclo olefin polymer (COP) film on a surface of which a coating layer was formed of a conductive polymer (Aedotron) manufactured by TDA was used instead of the TAC film.

Example 7

(22) A liquid crystal layer was formed through the same process as described in Example 5, except that a COP film on a surface of which a coating layer was formed of a conductive polymer (Aedotron) manufactured by TDA was used instead of the TAC film.

Example 8

(23) A liquid crystal film was manufactured through the same process as described in Example 5, except that a coating solution to which a conductive polymer (Aedotron) manufactured by TDA was added in a ratio of approximately 10 weight % during the preparation of the coating solution for an alignment layer.

(24) Results for measuring sheet resistance with respect to Examples 5 to 8 are summarized in Table 3.

(25) TABLE-US-00003 TABLE 3 Example 5 6 7 8 Surface hardness 1H 1H 1H 1H Alignment property In-plane retardation (nm) approximately 120 to 130 Sheet resistance (10.sup.9 ) 1000 100 1 1

Experimental Example

(26) When optical films manufactured in Examples 1 to 8 and Comparative Examples 1 and 2 were disposed on a visible side polarizing plate of a conventional LCD to have an angle between an absorption axis of the visible side polarizing plate and an optical axis (slow axis) of the liquid crystal layer of approximately 45 degrees, a brightness meter was disposed on a back surface of general polarizing glasses with driving the LCD, and the brightness was measured, when the optical film of Example was present, significant change in the brightness according to change in the polarization axis of the polarizing glasses was not observed. In cases of Comparative Examples 1 and 2, in the beginning, similar results to those of Examples were obtained, but it was confirmed that the films were easily damaged by scratches in use, thereby degrading performance according to time.