Circularly polarizing plate

Abstract

Provided is a circularly polarizing plate and a display device that includes the circularly polarizing plate. The circularly polarizing plate can be applied to a display device such as an organic light emitting display device to minimize blocking of light in the visible light region affecting image quality while blocking harmful ultraviolet rays appropriately and also has excellent durability.

Claims

1. A circularly polarizing plate comprising a polarizer; and a phase difference layer formed on one side of the polarizer, wherein the phase difference layer comprises a polymerized unit of a normal dispersion polymerizable liquid crystal compound and a polymerization unit of a reverse dispersion polymerizable liquid crystal compound in a ratio of 5:95 to 10:90 (normal: reverse), the phase difference layer has ultraviolet absorptivity that transmittance for light having a wavelength of 385 nm is 3% or less and transmittance of 2% or more for light having a wavelength of 390 nm, the phase difference layer has an absolute value of a phase difference change ratio according to Equation A below of 17% or less, wherein the normal dispersion polymerizable liquid crystal compound is a compound of Formula 6, and wherein the reverse dispersion polymerizable liquid crystal compound is a compound of Formula 1:
Phase difference change ratio=100×(Ra−Ri)/Ri  [Equation A] wherein, Ri is the initial in-plane phase difference of the phase difference layer for a wavelength of 550 nm, and Ra is the in-plane phase difference of the phase difference layer for a wavelength of 550 nm after an endurance condition, where the endurance condition is a condition that the phase difference layer is allowed to stand at a temperature of 85° C. for 50 hours or more, ##STR00008## wherein: A is a single bond, —C(═O)O— or —OC(═O)—; R.sub.2 and R.sub.3 or R.sub.3 and R.sub.4 are bonded to each other to constitute a benzene ring substituted with -L-A-P, where L is —OC(═O)O—, A is an alkylene group and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group; any one of R.sub.7 to R.sub.9 is Formula 7 below; the remaining substituents are each independently hydrogen, halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group or a nitro group; ##STR00009## wherein: B is a single bond, —C(═O)O— or —OC(═O)—; and two neighboring substituents of R.sub.11 to R.sub.15 are bonded to each other to constitute a benzene ring substituted with -L-A-P, where L is —OC(═O)O—, A is an alkylene group and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group; the remaining substituents are each independently hydrogen, halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group or a nitro group; ##STR00010## wherein: R.sub.1 is a substituent of Formula 2 or 3 below; and R.sub.2 to R.sub.6 are each independently hydrogen, an alkyl group, an alkoxy group, a cyano group, a substituent of Formula 4 below or a substituent of Formula 5 below where at least two or more of R.sub.2 to R.sub.6 are substituents of Formula 4 below or substituents of Formula 5 below:
-A.sub.1-L.sub.1-Cyc-A.sub.2-L.sub.2-P   [Formula 2] wherein: A.sub.1 and A.sub.2are each independently an oxygen atom or a single bond; L.sub.1 and L.sub.2 are each independently —C(═O)—O—, —O—C(═O)— or an alkylene group; Cyc is an arylene group or a cycloalkylene group; and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group; ##STR00011## wherein: L.sub.3 and L.sub.4 are each an alkylene group; n is a number in a range of 1 to 4; and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group or a hydrogen atom;
-A.sub.3-L.sub.5-Cyc-A.sub.4-L.sub.6-P   [Formula 4] wherein: A.sub.3 and A.sub.4 are an oxygen atom, an alkylene group or a single bond; L.sub.5 and L.sub.6 are each independently —C(═O)—O—, —O—C(═O)— or an alkylene group; Cyc is an arylene group; and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group;
-A.sub.5-L.sub.7-Cy.sub.1-A.sub.6-L.sub.8-Cy.sub.2-A.sub.7-L.sub.9-P   [Formula 5] wherein: A.sub.5, A.sub.6 and A.sub.7 are each independently an oxygen atom or a single bond; L.sub.7, L.sub.8 and L.sub.9 are each independently —C(═O)—O—, —O—C(═O) — or an alkylene group; Cy1is a cycloalkylene group; Cy2 is an arylene group; and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group.

2. A circularly polarizing plate comprising a polarizer; and a phase difference layer formed on one side of the polarizer, wherein the phase difference layer comprises a polymerized unit of a normal dispersion polymerizable liquid crystal compound and a polymerization unit of a reverse dispersion polymerizable liquid crystal compound in a ratio of 5:95 to 10:90 (normal: reverse), and the phase difference layer has ultraviolet absorptivity that transmittance for light having a wavelength of 385 nm is 3% or less, and transmittance of 2% or more for light having a wavelength of 390 nm, and does not comprise an ultraviolet absorber having a maximum absorption wavelength in a range of 385 nm to 400 nm, wherein the normal dispersion polymerizable liquid crystal compound is a compound of Formula 6, and wherein the reverse dispersion polymerizable liquid crystal compound is a compound of Formula 1: ##STR00012## wherein: A is a single bond, —C(═O)O— or —OC(═O)—; R.sub.2 and R.sub.3 or R.sub.3 and R.sub.4 are bonded to each other to constitute a benzene ring substituted with -L-A-P, where L is —OC(═O)O—, A is an alkylene group and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group; any one of R.sub.7 to R.sub.9 is Formula 7 below; the remaining substituents are each independently hydrogen, halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group or a nitro group; ##STR00013## wherein: B is a single bond, —C(═O)O— or —OC(═O)—; and two neighboring substituents of R.sub.11 to R.sub.15 are bonded to each other to constitute a benzene ring substituted with -L-A-P, where L is —OC(═O)O—, A is an alkylene group and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group, and the remaining substituents are each independently hydrogen, halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group or a nitro group; ##STR00014## wherein: R.sub.1 is a substituent of Formula 2 or 3 below; and R.sub.2 to R.sub.6 are each independently hydrogen, an alkyl group, an alkoxy group, a cyano group, a substituent of Formula 4 below or a substituent of Formula 5 below where at least two or more of R.sub.2 to R.sub.6 are substituents of Formula 4 below or substituents of Formula 5 below:
-A.sub.1-L.sub.1-Cyc-A.sub.2-L.sub.2-P   [Formula 2] wherein: A.sub.1 and A.sub.2 are each independently an oxygen atom or a single bond; L.sub.1 and L.sub.2 are each independently —C(═O)—O—, —O—C(═O)— or an alkylene group; Cyc is an arylene group or a cycloalkylene group; and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group; ##STR00015## wherein: L.sub.3 and L.sub.4 are each an alkylene group; n is a number in a range of 1 to 4; and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group or a hydrogen atom;
-A.sub.3-L.sub.5-Cyc-A.sub.4-L.sub.6-P   [Formula 4] wherein: A.sub.3 and A.sub.4 are an oxygen atom, an alkylene group or a single bond; L.sub.5 and L.sub.6 are each independently —C(═O)—O—, —O—C(═O)— or an alkylene group; Cyc is an arylene group; and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group;
-A.sub.5-L.sub.7-Cy.sub.1-A.sub.6-L.sub.8-Cy.sub.2-A.sub.7-L.sub.9-P   [Formula 5] wherein: A.sub.5, A.sub.6 and A.sub.7 are each independently an oxygen atom or a single bond; L.sub.7, L.sub.8 and L.sub.9 are each independently —C(═O)—O—, —O—C(═O)— or an alkylene group; Cy1 is a cycloalkylene group; Cy2 is an arylene group; and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group.

3. The circularly polarizing plate according to claim 1, wherein the phase difference layer has a transmittance of 25% or less for light having a wavelength of 395 nm.

4. The circularly polarizing plate according to claim 1, wherein the phase difference layer has a transmittance of 40% or less for light having a wavelength of 400 nm.

5. The circularly polarizing plate according to claim 1, wherein the phase difference layer comprises 40 wt % or more of polymerized units of the reverse wavelength polymerizable liquid crystal compound in polymerized units of the entire polymerizable liquid crystal compound.

6. The circularly polarizing plate according to claim 1, wherein the phase difference layer comprises 30 wt % or more of polymerized units of the polymerizable liquid crystal compound having tri-functionality or more in polymerized units of the entire polymerizable liquid crystal compound.

7. The circularly polarizing plate according to claim 1, further comprising an optical film laminated on an opposite surface of the polarizer facing the phase difference layer and having a planar phase difference for light having a wavelength of 550 nm in a range of 90 nm to 300 nm.

8. The circularly polarizing plate according to claim 1, further comprising an optical film present between the polarizer and the phase difference layer, and having a planar phase difference of 10 nm or less for light having a wavelength of 550 nm and a thickness direction phase difference for light having a wavelength of 550 nm in a range of 40 nm to 400 nm.

9. The circularly polarizing plate according to claim 1, further comprising an optical film present on the lower part of the phase difference layer and having a thickness direction phase difference in a range of 10 to 400 nm.

10. 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 1, wherein: the circularly polarizing plate is present outside the reflective or transparent electrode, and the phase difference layer is disposed closer to the reflective or transparent electrode than the polarizer.

11. 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 2, wherein: the circularly polarizing plate is present outside the reflective or transparent electrode, and the phase difference layer is disposed closer to the reflective or transparent electrode than the polarizer.

12. The circularly polarizing plate according to claim 2, wherein the phase difference layer has a transmittance of 25% or less for light having a wavelength of 395 nm.

13. The circularly polarizing plate according to claim 2, wherein the phase difference layer has a transmittance of 40% or less for light having a wavelength of 400 nm.

14. The circularly polarizing plate according to claim 2, further comprising an optical film laminated on an opposite surface of the polarizer facing the phase difference layer and having a planar phase difference for light having a wavelength of 550 nm in a range of 90 nm to 300 nm.

15. The circularly polarizing plate according to claim 2, further comprising an optical film present between the polarizer and the phase difference layer, and having a planar phase difference of 10 nm or less for light having a wavelength of 550 nm and a thickness direction phase difference for light having a wavelength of 550 nm in a range of 40 nm to 400 nm.

16. The circularly polarizing plate according to claim 2, further comprising an optical film present on the lower part of the phase difference layer and having a thickness direction phase difference in a range of 10 to 400 nm.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1 and 3 to 5 are schematic diagrams of exemplary circularly polarizing plate structures.

(2) FIG. 2 is a diagram for explaining an axial relationship.

(3) FIGS. 6 and 7 are graphs showing transmittance of an example or a comparative example.

(4) FIGS. 8 to 13 are graphs showing changes in phase difference in examples or comparative examples.

EXPLANATION OF REFERENCE NUMERALS

(5) 101: polarizer

(6) 102: phase difference layer

(7) 100: phase difference layer, retardation layer, phase difference film, optical film

(8) 301: outer layer

(9) 401: lower layer

(10) 501: middle layer

EXAMPLES

(11) Hereinafter, the present application will be described in detail by way of examples and comparative examples, but the scope of the present application is not limited by the following transmittance-variable device.

PREPARATION EXAMPLE 1

Preparation of Polymerizable Liquid Crystal Composition A

(12) A polymerizable liquid crystal composition was prepared using LC1057 liquid crystals of BASF Corporation as a normal dispersion polymerizable liquid crystal compound and a liquid crystal compound of Formula A below as a reverse dispersion liquid crystal compound. The normal dispersion polymerizable liquid crystal compound has R (450)/R (550) in a level of about 1.09 to 1.11 or so and R (650)/R (550) in a level of about 0.93 to 0.95 or so, and the liquid crystal compound of Formula A has R (450)/R (550) in a level of about 0.84 to 0.86 or so and R (650)/R (550) in a level of about 1.01 to 1.03 or so. The R (450), R (550) and R (650) are in-plane phase differences for light having wavelengths of 450 nm, 550 nm and 650 nm, respectively, as measured with respect to a phase difference layer formed by using the normal dispersion polymerizable liquid crystal compound or the polymerizable liquid crystal compound of Formula A alone. The in-plane phase difference can be measured by a known method, and for example, it can be measured by a polarization measurement method using Axoscan (Axometrics), which is a birefringence meter. The method of forming the phase difference layer by using the polymerizable liquid crystal compounds alone is the same as that described in the following examples, except that the polymerizable liquid crystal compounds are applied alone. The normal dispersion polymerizable liquid crystal compound and the reverse dispersion polymerizable liquid crystal compound of Formula A were mixed in a weight ratio of approximately 94:6 to 95:5 (reverse dispersion polymerizable liquid crystal: normal dispersion polymerizable liquid crystal) and about 5 parts by weight of a radical photoinitiator (BASF, Irgacure 907) relative to 100 parts by weight of the total of the polymerizable liquid crystal compounds was combined in a solvent (cyclopentanone) to prepare a polymerizable liquid crystal composition A.

(13) ##STR00005##

(14) Here, the compound of Formula A was synthesized in the following manner. Under a nitrogen atmosphere, 17.7 g of a compound of Formula A1 below and 100 ml of tetrahydrofuran were placed in a reaction vessel. 103 ml of a 0.9 mol/L borane-tetrahydrofuran complex was dripped while cooling with ice and the mixture was stirred for 1 hour. After dripping 5% hydrochloric acid, the mixture was extracted with ethyl acetate and washed with a saline solution. The extract was dried over sodium sulfate and the solvent was distilled off to obtain 14.9 g of a compound of Formula A2 below. Under a nitrogen atmosphere, 14.9 g of the compound of Formula A2, 7.2 g of pyridine and 150 ml of dichloromethane were added to the reaction vessel. 8.8 g of methanesulfonyl chloride was dripped while cooling with ice and the mixture was stirred at room temperature for 3 hours. The reactant was poured into water, and washed sequentially with 5% hydrochloric acid and a saline solution. Purification was performed by column chromatography (silica gel, hexane/ethyl acetate) and recrystallization (acetone/hexane) to obtain 16.3 g of a compound of Formula A3 (in Formula A3 below, Ms is a methanesulfonyl group). Under a nitrogen atmosphere, 2.5 g of a compound of Formula A4, 10.6 g of the compound of Formula A3, 7.5 g of potassium carbonate and 70 ml of N,N-dimethylformamide were added to the reaction vessel and the mixture was heated and stirred at 90° C. for 3 days. The reactant was poured into water, extracted with toluene and washed with a saline solution. Purification was performed by column chromatography (silica gel, toluene) and recrystallization (acetone/methanol) to obtain 7.7 g of a compound of Formula A5. 7.7 g of the compound of Formula A5, 150 ml of dichloromethane and 100 ml of trifluoroacetic acid were added to the reaction vessel and stirred. After the solvent was distilled off, the resulting solid was washed with water and dried to obtain 5.5 g of a compound of Formula A6.

(15) Under a nitrogen atmosphere, 5.5 g of the compound of Formula A6, 6.9 g of a compound of Formula A7, 0.8 g of N,N-dimethylaminopyridine and 200 ml of dichloromethane were added to the reaction vessel. 4.1 g of diisopropylcarbodiimide was dripped while cooling with ice and the mixture was stirred at room temperature for 10 hours. After the precipitate was removed by filtration, the filtrate was washed successively with 1% hydrochloric acid, water and a saline solution. After performing recrystallization (dichloromethane/methanol), purification was performed by column chromatography (silica gel, dichloromethane) and recrystallization (dichloromethane/methanol) to obtain 8.4 g of a compound of Formula A8.

(16) 1.4 g of the compound of Formula A8, 0.35 g of 2-hydrazinobenzothiazole and 5 ml of tetrahydrofuran were added to a 30 ml three-necked flask, and the mixture was stirred at 25° C. for 9 hours. Then, 50 ml of water was added, and the mixture was extracted twice with 30 ml of ethyl acetate. The resulting organic phase was dried with sodium sulfate. After sodium sulfate was filtered off, the organic phase was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (hexane/ethyl acetate=2/1). The resulting crude product was subjected to reprecipitation using acetone/methanol. These crystals were filtered and dried to obtain 0.98 g of a compound of Formula A9. Subsequently, the hydrogen atom attached to the nitrogen atom of the compound of Formula A9 was substituted with a 2-[2-(2-acryloyloxyethoxy)ethoxy]ethyl group to obtain the compound of Formula A. NMR confirmatory results of the resulting compound of Formula A were described below.

(17) ##STR00006##

(18) <NMR Results>

(19) .sup.1H NMR (CDCl.sub.3) δ 1.19-1.29 (m, 4H), 1.41-1.82 (m, 22H), 1.91 (m, 2H), 2.08 (m, 4H), 2.24 (m, 4H), 2.53 (m, 2H), 3.62 (m, 3H), 3.67 (m, 2H), 3.84-3.90 (m, 5H), 3.94 (t, 4H), 4.15-4.19 (m, 6H), 4.53 (t, 2H), 5.76 (dd, 1H), 5.82 (dd, 2H), 6.08 (dd, 1H), 6.12 (dd, 2H), 6.37 (dd, 1H), 6.40 (dd, 2H), 6.84-6.90 (m, 6H), 6.95-6.98 (m, 4H), 7.14 (t, 1H), 7.32 (t, 1H), 7.53 (d, 1H), 7.65 (d, 1H), 7.69 (d, 1H), 8.34 (s, 1H) ppm.

PREPARATION EXAMPLE 2

Preparation of Polymerizable Liquid Crystal Composition B

(20) A polymerizable liquid crystal composition B was prepared in the same manner as in Preparation Example 1, except that a liquid crystal compound of Formula B below was applied as the reverse dispersion polymerizable liquid crystal compound. The liquid crystal compound of Formula B has R (450)/R (550) in a level of about 0.81 to 0.83 or so and R (650)/R (550) in a level of about 1.01 to 1.03 or so. The R (450), R (550) and R (650) are in-plane phase differences for light having wavelengths of 450 nm, 550 nm and 650 nm, as measured with respect to a phase difference layer formed by using the polymerizable liquid crystal compound of Formula B alone.

(21) ##STR00007##

(22) Here, the compound of the Formula B was obtained by obtaining a compound of Formula A9 below in the same manner as in Preparation Example 1 and then substituting the hydrogen atom attached to the nitrogen atom of the compound of Formula A9 with a 2-[2-(methoxyethoxy)]ethyl group. NMR confirmatory results of the resulting compound of Formula B were described below.

(23) <NMR Results>

(24) .sup.1H NMR (CDCl.sub.3) δ 1.22-1.28 (m, 4H), 1.44-1.47 (m, 8H), 1.60-1.82 (m, 12H), 1.90 (m, 2H), 2.07 (t, 4H), 2.24 (d, 4H), 2.53 (m, 2H), 3.30 (s, 3H), 3.50 (t, 2H), 3.66 (t, 2H), 3.85-3.89 (m, 6H), 3.93 (t, 4H), 4.17 (t, 4H), 4.53 (t, 2H), 5.82 (d, 2H), 6.13 (q, 2H), 6.40 (d, 2H), 6.83-6.90 (m, 6H), 6.95-6.98 (m, 4H), 7.14 (t, 1H), 7.32 (t, 1H), 7.52 (t, 1H), 7.67 (t, 2H), 8.33 (s, 1H) ppm.

PREPARATION EXAMPLE 3

Preparation of Polymerizable Liquid Crystal Composition C

(25) A polymerizable liquid crystal composition was prepared by applying the reverse dispersion polymerizable liquid crystal compound of Formula A in Preparation Example 1 above, the same photoinitiator as that used in Preparation Example 1 and an ultraviolet absorber (Orient Chemical Industries, BONASORB UA-3912) having a maximum absorption wavelength range of about 380 to 390 nm as an ultraviolet absorber. The reverse dispersion polymerizable liquid crystal compound of Formula A, the photoinitiator and the ultraviolet absorber were combined in a solvent (cyclopentanone) in a weight ratio of 20:1:1 (reverse dispersion polymerizable liquid crystal compound:photoinitiator:ultraviolet absorber) to prepare a polymerizable liquid crystal composition C.

PREPARATION EXAMPLE 4

Preparation of Polymerizable Liquid Crystal Composition D

(26) A polymerizable liquid crystal composition D was prepared in the same manner as in the case of Preparation Example 3, except that the reverse dispersion polymerizable liquid crystal compound of Formula A, the photoinitiator and the ultraviolet absorber were combined in a weight ratio of 20:1:0.6 (reverse dispersion polymerizable liquid crystal compound:photoinitiator:ultraviolet absorber).

EXAMPLE 1

(27) Production of Phase Difference Layer

(28) A photo-alignment film was formed on an NRT base film from FujiFilm. A known cinnamate series composition for forming a photo-alignment film was applied on the NRT base film to a thickness of about 100 nm and irradiated with linearly polarized ultraviolet rays at about 300 mW/cm.sup.2 to form it. Subsequently, the polymerizable liquid crystal composition A was coated on the photo-alignment film to be a dry thickness of about 1 oriented along the lower alignment film, and then irradiated with ultraviolet rays at about 300 mW/cm.sup.2 for about 10 seconds to form a phase difference layer. The in-plane phase difference of the phase difference layer for light having a wavelength of 550 nm was about 146.0 nm. The formed phase difference layer had R (450)/R (550) in a level of about 0.85 to 0.87 or so and R (650)/R (550) in a level of about 1.01 to 1.05 or so.

(29) Production of Circularly Polarizing Plate

(30) The produced phase difference layer was attached to one side of a known iodine PVA (poly(vinyl alcohol)) polarizer (LG Chemical Co., Ltd.) as a polarizer to produce a circularly polarizing plate. For attachment, a general ultraviolet curable adhesive used for lamination of an optical film was applied.

EXAMPLE 2

(31) Production of Phase Difference Layer

(32) A phase difference layer was formed in the same manner as in Example 1, except that the polymerizable liquid crystal composition B was applied instead of the polymerizable liquid crystal composition A. The in-plane phase difference of the phase difference layer for light having a wavelength of 550 nm was about 144.5 nm. The formed phase difference layer had R (450)/R (550) in a level of about 0.82 to 0.85 or so and R (650)/R (550) in a level of about 1.01 to 1.05 or so.

(33) Production of Circularly Polarizing Plate

(34) A circularly polarizing plate was produced in the same manner as in Example 1, using the produced phase difference layer.

COMPARATIVE EXAMPLE 1

(35) Production of Phase Difference Layer

(36) A phase difference layer was formed in the same manner as in Example 1, except that the polymerizable liquid crystal composition C was applied instead of the polymerizable liquid crystal composition A. The in-plane phase difference of the phase difference layer for light having a wavelength of 550 nm was about 131.7 nm. The formed phase difference layer had R (450)/R (550) in a level of about 0.84 to 0.86 or so and R (650)/R (550) in a level of about 1.01 to 1.03 or so.

(37) Production of Circularly Polarizing Plate

(38) A circularly polarizing plate was produced in the same manner as in Example 1, using the produced phase difference layer.

COMPARATIVE EXAMPLE 2

(39) Production of Phase Difference Layer

(40) A phase difference layer was formed in the same manner as in Example 1, except that the polymerizable liquid crystal composition D was applied instead of the polymerizable liquid crystal composition A. The in-plane phase difference of the phase difference layer for light having a wavelength of 550 nm was about 140.7 nm. The formed phase difference layer had R (450)/R (550) in a level of about 0.81 to 0.83 or so and R (650)/R (550) in a level of about 1.01 to 1.03 or so.

(41) Production of Circularly Polarizing Plate

(42) A circularly polarizing plate was produced in the same manner as in Example 1, using the produced phase difference layer.

(43) Evaluation 1. Comparison of Ultraviolet Absorption Characteristics.

(44) The ultraviolet absorption characteristics of each of the phase difference layers produced in Examples and Comparative Examples were compared. The ultraviolet absorption characteristics for each wavelength were evaluated for a specimen that an alignment film and a liquid crystal layer (phase difference layer) were sequentially formed on an NRT base material which does not exhibit any absorption peak in a wavelength region of 300 nm or more by a method shown in each of Examples and Comparative Examples by using N&K UV Spectrometer (HP). FIGS. 6 and 7 are measurement results for Example 1, respectively and FIGS. 8 and 9 are measurement results for Comparative Examples 1 and 2, respectively. The specific transmittance for each wavelength was summarized in Table 1 below.

(45) TABLE-US-00001 TABLE 1 Transmittance (unit: %) 385 nm 390 nm 395 nm 400 nm Example 1 1.7 3.7 10.4 27.0 Example 2 1.7 3.8 10.5 27.2 Comparative 0.5 0.9 2.6 7.0 Example 1 Comparative 0.7 1.6 4.3 11.6 Example 2

(46) From Table 1, it can be confirmed that the present application can secure superior ultraviolet blocking properties without applying an ultraviolet absorber.

(47) Evaluation 2. Durability Evaluation.

(48) Durability was evaluated for each of the phase difference layers produced in Examples and Comparative Examples. The durability was evaluated by maintaining each of the phase difference layers produced in Examples and Comparative Examples at a condition of about 85° C. (endurance condition) for 250 hours, and then comparing the in-plane phase difference (based on a wavelength of 550 nm) before maintaining the condition and the in-plane phase difference (based on a wavelength of 550 nm) after maintaining the condition. FIGS. 10 and 11 are measurement results for Example 1, respectively and FIGS. 12 and 13 are measurement results for Comparative Examples 1 and 2, respectively.

(49) TABLE-US-00002 TABLE 2 In-plane phase difference (based on a wavelength of 550 nm) Before After maintaining maintaining endurance endurance Change condition condition amount Example 1 146.0 nm 123.8 nm −15.2% Example 2 144.5 nm 123.8 nm −14.8% Comparative 131.7 nm 101.7 nm −22.8% Example 1 Comparative 140.7 nm 113.6 nm −19.3% Example 2

(50) From the results of Table 2, in the case of the phase difference layer according to the present application, it can be confirmed that it has excellent ultraviolet absorbing ability without using an ultraviolet absorber or a light stabilizer and also as a result, shows excellent results in terms of durability.