Liquid crystal composition and use thereof

Abstract

Provided is a liquid crystal composition and a use thereof. The liquid crystal composition has a reverse-wavelength dispersion property and excellent high-temperature durability, and the liquid crystal composition can be applied to a retardation layer, a circularly polarizing plate, or a display device, for example, an organic light emitting display device.

Claims

1. A liquid crystal composition, comprising: a polymerizable liquid crystal compound having a reverse wavelength dispersion property; and a non-liquid crystalline epoxy compound having two or more epoxy groups, wherein the non-liquid crystalline epoxy compound has no radical-curable functional group, wherein the non-liquid crystalline epoxy compound is one of the following Formula 7 or 8 and wherein after the liquid crystal composition is irradiated with ultraviolet rays of UVB region wavelengths at a light quantity of 100 mJ/cm.sup.2 to 250 mJ/cm.sup.2 in the total irradiance level and cured, and it has an in-plane retardation change rate represented by the following Equation 6 of 8% or less: ##STR00009## wherein in Formula 7: X is an m-valent non-mesogenic saturated hydrocarbon group; n is an integer of 1 to 20; and m is an integer of 2 or more; and wherein in Formula 8: Y is an m-valent non-mesogenic hydrocarbon group; L.sub.9 is a single bond, —OCO—, —COO— or —O—; and m is an integer of 2 or more, wherein the non-mesogenic hydrocarbon group means a hydrocarbon group having no mesogen skeleton which means a structure containing at least two aromatic groups;
ΔRin=(1−Rin.sub.2/Rin.sub.1)×100  [Equation 6] wherein ΔRin is an in-plane retardation change rate after high temperature storage, Rin1 is an initial in-plane retardation value, and Rin2 is an in-plane retardation value after high temperature storage at 80° C. for 96 hours.

2. The liquid crystal composition according to claim 1, wherein the polymerizable liquid crystal compound satisfies the following equation 1:
R(450)/R(550)<R(650)/R(550)  [Equation1] wherein R (λ) means an in-plane retardation for light having a wavelength of λ nm.

3. The liquid crystal composition according to claim 1, wherein the polymerizable liquid crystal compound has an R (450)/R (550) value of 0.99 or less and an R (650)/R (550) value of 1.01 or more, where R (λ) means an in-plane retardation for light having a wavelength of λ nm.

4. The liquid crystal composition according to claim 1, wherein the polymerizable liquid crystal compound has a refractive index anisotropy Δn represented by the following formula of 0.03 to 0.13 for light having a wavelength of 550 nm: Δn=ne−no wherein Δn represents a refractive index anisotropy of the polymerizable liquid crystal compound, ne represents an extraordinary refractive index of the polymerizable liquid crystal compound, no represents an ordinary refractive index of the polymerizable liquid crystal compound.

5. The liquid crystal composition according to claim 1, wherein the non-liquid crystalline epoxy compound is included in an amount of 1 to 20 parts by weight relative to 100 parts by weight of the polymerizable liquid crystal compound.

6. The liquid crystal composition according to claim 1, wherein the non-liquid crystalline epoxy compound has 2 to 8 epoxy groups.

7. The liquid crystal composition according to claim 1, wherein X and Y are each a linear, branched or cyclic m-valent non-mesogenic saturated hydrocarbon group having 1 to 20 carbon atoms.

8. The liquid crystal composition according to claim 1, wherein in Formulas 7 and 8, each m is an integer of 2 to 3.

9. The liquid crystal composition according to claim 1, wherein the non-liquid crystalline epoxy compound is one of the following Formulae 9 to 14: ##STR00010##

10. The liquid crystal composition according to claim 1, wherein the liquid crystal composition further comprises a cationic initiator.

11. A circularly polarizing plate comprising a linear polarizer, and a retardation layer containing a cured layer of the liquid crystal composition of claim 1.

12. The circularly polarizing plate according to claim 11, wherein the retardation layer has a quarter-wave phase delay characteristic.

13. The circularly polarizing plate according to claim 11, wherein the light absorption axis of the linear polarizer and the slow axis of the retardation layer form an angle of 40 degrees to 50 degrees.

14. An organic light emitting display device, comprising: a reflective electrode; a transparent electrode; an organic layer interposed between the reflective electrode and the transparent electrode and having a light emitting layer; and the circularly polarizing plate of claim 11, wherein the circularly polarizing plate is present outside the reflective or transparent electrode and the retardation layer is disposed closer to the reflective or transparent electrode than the linear polarizer.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 exemplarily shows the circularly polarizing plate of the present application.

(2) FIG. 2 exemplarily shows the x-axis, the y-axis and the z-axis.

(3) FIG. 3 exemplarily shows the circularly polarizing plate of the present application.

(4) FIG. 4 exemplarily shows the circularly polarizing plate of the present application.

(5) FIG. 5 exemplarily shows the circularly polarizing plate of the present application.

EXAMPLES

(6) Hereinafter, the present application will be specifically described by way of examples, but the scope of the present application is not limited by the following examples.

Measurement Example 1 Measurement of Retardation Value

(7) An in-plane or thickness-direction retardation was measured for light having a wavelength of 550 nm using an Axoscan instrument (Axomatrics) capable of measuring 16 Muller matrices. Using the Axoscan instrument, 16 Muller matrices were obtained according to the manufacturer's manual, through which retardation was extracted.

Example 1

(8) Preparation of Liquid Crystal Composition

(9) 1.75 g of a polymerizable liquid crystal compound (UCL-R17, DIC) having a reverse wavelength dispersion property, 0.175 g of a non-liquid crystalline epoxy compound (neopentyl glycol diglycidyl ether) and 0.0175 g of a cationic initiator (CPI-100P, Sanapro) were mixed with 3.25 g of a toluene solvent to prepare a liquid crystal composition. The polymerizable liquid crystal compound has an R (450)/R (550) value of 0.86 and an R (650)/R (550) value of 1.01.

(10) Production of Retardation Layer

(11) The liquid crystal composition was applied on a triacetyl cellulose (TAC) base material to have a thickness of about 2 μm after drying, irradiated with ultraviolet rays of a UVB region wavelength (about 300 nm) at a light quantity of 200 mJ/cm.sup.2 in the total irradiance level in a state of being oriented on the xy plane and cured to produce a retardation layer. The light quantity was measured using a UV power puck II.

Example 2

(12) A retardation layer was produced in the same manner as in Example 1, except that in Example 1, the non-liquid crystalline epoxy compound was changed to 1,4-cyclohexane dimethanol diglycidyl ether.

Example 3

(13) A retardation layer was produced in the same manner as in Example 1, except that in Example 1, the non-liquid crystalline epoxy compound was changed to 1,4-butanediol diglycidyl ether.

Example 4

(14) A retardation layer was produced in the same manner as in Example 1, except that in Example 1, the non-liquid crystalline epoxy compound was changed to trimethylolpropane triglycidyl ether.

Example 5

(15) A retardation layer was produced in the same manner as in Example 1, except that in Example 1, the non-liquid crystalline epoxy compound was changed to 3′,4′-epoxycyclohexanemethyl-3,4-epoxycyclohexylcarboxylate (Celloxide 2021p, Daicel).

Comparative Example 1

(16) A retardation layer was produced in the same manner as in Example 1, except that in Example 1, the non-liquid crystalline epoxy compound and the cationic initiator were not used in the liquid crystal composition.

Comparative Example 2

(17) A retardation layer was produced in the same manner as in Example 1, except that in Example 1, the non-liquid crystalline epoxy compound was changed to 2-ethylhexyl monoglycidyl ether.

Comparative Example 3

(18) A retardation layer was produced in the same manner as in Example 1, except that in Example 1, the non-liquid crystalline epoxy compound was changed to GMA (glycidyl methacrylate) having an acryl group.

Reference Example 1

(19) 1.75 g of a polymerizable liquid crystal compound (RM257, BASF) having a normal wavelength dispersion property was mixed with 3.25 g of a toluene solvent to prepare a liquid crystal composition. The polymerizable liquid crystal compound has an R (450)/R (550) value of 1.09, and an R (650)/R (550) value of 0.95. The liquid crystal composition was cured in the same manner as in Example 1 to produce a retardation layer.

Reference Example 2

(20) 1.75 g of a polymerizable liquid crystal compound (RM257, BASF) having a normal wavelength dispersion property, 0.175 g of a non-liquid crystal epoxy compound (neopentyl glycol diglycidyl ether) and 0.0175 g of a cationic initiator (CPI-100P, Sanapro) were mixed with 3.25 g of a toluene solvent to prepare a liquid crystal composition. The liquid crystal composition was cured in the same manner as in Example 1 to produce a retardation layer.

Evaluation Example 1 Evaluation of High Temperature Durability

(21) For the Examples, Comparative Examples and Reference Examples, initial retardation values and change rates of the retardation values after high temperature storage were measured according to the following Equation 6, and the results were described in Tables 1 and 2 below.
ΔRin=(1−Rin.sub.2/Rin.sub.1)×100  [Equation 6]

(22) ΔRin is an in-plane retardation change rate after high temperature storage, Rim is an initial in-plane retardation value at 25° C., and Rina is an in-plane retardation value after high temperature storage at 80° C. for 24 hours or 96 hours.

(23) As described in Table 1, Comparative Example 1, which is a retardation layer comprising a polymerizable liquid crystal compound having a reverse wavelength dispersion property, exhibits a retardation change rate of 7.8% after high temperature storage for 24 hours and a retardation change rate of 8.5% after high temperature storage for 96 hours, whereby it can be confirmed that the retardation change rate after high temperature storage is large. In Examples 1 to 5 in which the multifunctional non-liquid crystalline epoxy compound was added, the retardation change amount after high temperature storage was reduced to 3% or less. On the other hand, in Comparative Example 2 in which the monofunctional non-liquid crystalline epoxy compound was added, and Comparative Example 3 in which the non-liquid crystalline epoxy compound having an acryl group was added, the retardation change amount after high temperature storage was instead increased.

(24) As described in Table 2, it can be confirmed that Reference Example 1, which is a retardation layer comprising a polymerizable liquid crystal compound having a normal wavelength dispersion property, has a relatively smaller retardation change amount even after high temperature storage as compared with Comparative Example 1. Also, in Reference Example 2 in which the multifunctional non-liquid crystalline epoxy compound was added, the retardation change amount did not significantly decrease even after high temperature storage.

(25) TABLE-US-00001 TABLE 1 24 hr 96 hr Initial Change Amount Change Amount Rin (nm) Rin (%) Rin (%) Comparative 1 144.5 7.8 8.5 Example 2 138.7 7.5 8.1 3 141.1 7.3 8.2 Example 1 137.5 1.8 2.0 2 136.6 2.2 2.5 3 132.1 2.0 2.7 4 133.3 2.4 2.6 5 135 2.6 3.0

(26) TABLE-US-00002 TABLE 2 Initial 24 hr Change Amount 96 hr Change Amount Rin (nm) Rin (%) Rin (%) Reference 1 136.3 1.5 2.0 Example 2 135.5 2.1 2.3

EXPLANATION OF REFERENCE NUMERALS

(27) 101: polarizer, 102: retardation layer, 100: retardation layer, 301: outer layer, 401: lower layer, 501: middle layer