Patent ID: 12207494

Hereinafter, the present application will be described in detail through examples complying with the present application and comparative examples not complying with the present application, but the scope of the present application is not limited to the following examples.

Circularly Polarizing Plate

A circularly polarizing plate comprising an antireflection film, a polarizer, a retardation film and an adhesive layer sequentially was prepared.

The antireflection film was produced by coating a hard coating layer having a thickness of about 5 μm on a triacetyl cellulose (TAC) base film and then coating a low refractive layer including hollow silica nanoparticles on the hard coating layer. The low refractive layer has a refractive index of about 1.32 for light having a wavelength of 550 nm. The thickness of the low refractive layer is controlled in a range of about 80 nm to 200 nm, and the lowest reflection wavelength of the antireflection film can be adjusted by controlling the thickness of the low refractive layer. Specifically, the lowest reflection wavelength of the antireflection film shifts to longer wavelengths as the thickness of the low refractive layer becomes thicker, and shifts to short wavelengths as the thickness of the low refractive layer becomes thinner. As the lowest reflection wavelength of the antireflection film increases, the b* of the reflection colors of the antireflection film tends to decrease. By adjusting the thickness within the thickness range, six types of antireflection films were prepared as shown in Table 1 below.

The retardation film was a product produced by obliquely stretching a COP film from Zeon, where products that the R(450)/R(550) value was 1 and the in-plane retardation values for light having a wavelength of 550 nm were 130 nm, 135 nm, and 137.5 nm, 140 nm, 142 nm and 144 nm, respectively, were prepared. In addition, the angle formed by the slow axis of the retardation film and the light absorption axis of the polarizer was adjusted to be 45 degrees or 40 degrees. The retardation value and optical axis of the retardation film are determined using Axometrics' Axoscan equipment.

As the polarizer, a PVA-based polarizer having transmittance of 44% was used. The transmittance and absorption axis of the polarizer are determined using Jasco's V-7100 Spectrophotometer equipment.

The pressure-sensitive adhesive layer is laminated on the retardation film surface by using a product coated between release films. As the pressure-sensitive adhesive layer, a commercially available acrylic pressure-sensitive adhesive for polarizing plates is used. As the pressure-sensitive adhesive, a pressure-sensitive adhesive comprising no blue cut dye and a pressure-sensitive adhesive comprising a blue cut dye (Eutec Chemical Co., Ltd.'s Eusorb UV-1990) were prepared. The thickness of the adhesive is 20 μm. The blue cut dye in the pressure-sensitive adhesive was mixed to have concentrations of about 0.3%, 0.6% and 0.9% to prepare the pressure-sensitive adhesive comprising the blue cut dye. The transmittance spectrum of the pressure-sensitive adhesive layer comprising the blue cut dye was specifically described in Evaluation Example 2 below.

EVALUATION EXAMPLE 1

Evaluation of Surface Reflection Characteristics in Antireflection Films

For antireflection films, reflection colors and reflectance were measured to evaluate surface reflection characteristics. Table 1 shows results of measuring lowest reflection wavelengths, reflection colors (L*a*b* color coordinates) and reflectance in the antireflection films.

The reflectance of the antireflection film was measured by attaching a black tape absorbing light to the backside of the antireflective coating layer of the base material and then using Minolta's CM-2600d equipment to measure mirror reflectance of the surface layer of the antireflective coating layer. Specifically, the reflectance is a result value of subtracting the SCE (Specular component excluded) value from the SCI (Specular component included) value among the measured values of the equipment. Simultaneously with the above measurements, CIE 1976 L*a*b* under a D65 light source condition can be obtained from the measurement equipment. Since most of the SCE values were values reflected from the black tape attached to the backside instead of the antireflection film, the SCE values were subtracted to accurately determine the reflection characteristics of the antireflection film.

FIG.4shows reflectance spectra of the antireflection films AR1 to AR6, and Table 1 shows the L*a*b* color coordinates of reflection colors of the antireflection film, luminous reflectance (Y) and reflectance for light having a wavelength of 550 nm.

LowReflection colorAnti-refractiveLowest(D65, CIE 1976ReflectancereflectionlayerreflectionL*a*b*)550filmthicknesswavelengthL*a*b*YnmAR173 nm380 nm11.532.227.801.3%1.3%AR284 nm440 nm8.273.395.040.9%0.9%AR390 nm470 nm7.663.943.250.8%0.8%AR4105 nm550 nm5.723.57−5.460.6%0.6%AR5113 nm590 nm7.802.50−10.480.9%0.8%AR6120 nm630 nm8.611.84−11.231.0%0.9%

EVALUATION EXAMPLE 2

Evaluation of Transmittance of Pressure-Sensitive Adhesive and Polarizing Plate

The transmittance of the pressure-sensitive adhesive comprising the blue cut dye and the transmittance of the polarizer before and after the attachment of the pressure-sensitive adhesive were measured, and the results are shown inFIGS.5and6, respectively. The pressure-sensitive adhesive with a blue cut dye concentration of 0.3% has transmittance of 90% for a wavelength of 430 nm, the pressure-sensitive adhesive with a blue cut dye concentration of 0.6% has transmittance of 80% for a wavelength of 430 nm, and the pressure-sensitive adhesive with a blue cut dye concentration of 0.9% has transmittance of 70% for a wavelength of 430 nm.

The transmittance of the pressure-sensitive adhesive comprising the blue cut dye was measured using Shimadzu UV-3600. Specifically, it was measured using a sample that the pressure-sensitive adhesive comprising the blue cut dye was attached to a glass substrate, and then a transparent PET film was attached to the exposed pressure-sensitive adhesive surface again. Upon setting the baseline of the equipment before the measurement of the sample, it was performed in a state of loading a sample having the same structure as the measurement sample and introducing a transparent pressure-sensitive adhesive instead of the pressure-sensitive adhesive comprising the blue cut dye. As a result, the measured transmittance of the sample was measured under the condition that the reflectance was not included, whereby the transmittance of the wavelength band without absorption of the dye is 100%. The transmission colors of the pressure-sensitive adhesive were calculated using the transmission data for each wavelength obtained using the Shimadzu UV-3600 equipment.

The transmittance of the polarizer was measured using Jasco's V-7100 Spectrophotometer. The transmittance and transmission color measurement results were described in Table 2 below.

TABLE 2Transmission color(D65, CIE 1976TransmittanceL*a*b*)Y430 nmL*a*b*PSA1Pressure-sensitive99.9%90%99.97−1.622.88adhesive 1 (0.3%)PSA2Pressure-sensitive99.8%80%99.93−3.005.41adhesive 2 (0.6%)PSA3Pressure-sensitive99.7%70%99.90−4.147.57adhesive 3 (0.9%)POL1Polarizer44.1%40.6%72.28−0.872.53POL2Polarizer +44.0%36.5%72.26−1.964.54Pressure-sensitiveadhesive 1POL3Polarizer +44.0%32.3%72.24−2.926.34Pressure-sensitiveadhesive 2POL4Polarizer +44.0%28.4%72.21−3.717.89Pressure-sensitiveadhesive 3

EVALUATION EXAMPLE 3

Evaluation of Reflection Characteristics of Circularly Polarizing Plate

A reflective ND (neutral density) filter with an OD (optical density) of 0.5 coated with Inconel (metal) on one side of a glass substrate purchased from Edmund Optics was used as a reflective plate to measure the reflective characteristics of the circularly polarizing plate.FIG.7shows the reflectance spectrum of the reflective plate. The reflectance was measured using Minolta's CM-2600d, and the reflectance was measured on the glass surface with the deposition surface of the reflective plate facing the light trap. The reflectance was obtained from the SCI (specular component included) mode value. The circularly polarizing plate was attached to the glass surface of the reflective plate, and then the reflectance and the reflection colors were measured in the same method as above. The reflectance and reflection colors are measured in the CIE 1964/10° standard under the D65 light source condition. When the reflection colors based on the L*a*b* color coordinates satisfy Δa*b*<8 or 0<a*<8 and −8<b*<0, it can be evaluated as having excellent reflective visual appreciation.

While the constitutions of the circularly polarizing plate were changed, the reflectance and reflection colors were measured, and the measurement results were described in Tables 3 to 6.

Table 3 shows the measurement results of the circularly polarizing plate in which the b* value of the antireflection film and the Rin value of the retardation film for light having a wavelength of 550 nm have been changed with regard to the circularly polarizing plate that the angle formed by the slow axis of the retardation film and the light absorption axis of the polarizer is 45 degrees and the pressure-sensitive adhesive layer comprises no dye, whereby the transmittance of the circularly polarizing plate for light having a wavelength of 430 nm is 40.6%.

Table 4 shows the measurement results of the circularly polarizing plate in which the b* value of the antireflection film and the Rin value of the retardation film for light having a wavelength of 550 nm have been changed with regard to the circularly polarizing plate that the angle formed by the slow axis of the retardation film and the light absorption axis of the polarizer is 40 degrees and the pressure-sensitive adhesive layer comprises no dye, whereby the transmittance of the circularly polarizing plate for light having a wavelength of 430 nm is 40.6%.

Table 5 shows the measurement results of the circularly polarizing plate in which the b* value of the antireflection film and the Rin value of the retardation film for light having a wavelength of 550 nm have been changed with regard to the circularly polarizing plate that the angle formed by the slow axis of the retardation film and the light absorption axis of the polarizer is 45 degrees and the pressure-sensitive adhesive layer comprises the dye in an amount of 0.3 wt %, whereby the transmittance of the circularly polarizing plate for light having a wavelength of 430 nm is 36.5%.

Table 6 shows the measurement results of the circularly polarizing plate in which the b* value of the antireflection film and the Rin value of the retardation film for light having a wavelength of 550 nm have been changed with regard to the circularly polarizing plate that the angle formed by the slow axis of the retardation film and the light absorption axis of the polarizer is 45 degrees and the pressure-sensitive adhesive layer comprises the dye in an amount of 0.6 wt %, whereby the transmittance of the circularly polarizing plate for light having a wavelength of 430 nm is 32.4%.

In Tables 3 to 6, Y(%) means luminous reflectance, R@550 nm means reflectance for light having a wavelength of 550 nm, and Δa*b* means a value calculated as √{square root over (a*2+b*2)}. As a result of the evaluation, it can be seen that Examples exhibit excellent reflection colors, as the reflection characteristics satisfy Δa*b*<8 or 0<a*<8 and −8<b*<0.

TABLE 3Structure of circularlypolarizing plateReflection characteristicsAntireflectionRetardationYR @film b*film Rin (nm)(%)550 nma*b*Δa*b*Example17.801301.481.245.354.587.025.041301.060.847.052.037.333.251300.990.777.680.357.7Comparative1−5.461300.770.558.30−7.5411.2Example2−10.481301.010.736.42−11.4413.13−11.231301.100.815.65−12.0913.3Example47.801351.451.205.122.075.557.801351.030.816.80−0.826.965.041350.960.737.44−2.447.8Comparative43.251350.750.527.94−9.9312.7Example5−5.461350.960.706.15−13.3214.76−10.481351.070.785.38−13.8614.9Example77.80137.51.451.194.930.875.085.04137.51.030.806.58−2.146.993.25137.50.960.737.21−3.728.1Comparative7−5.46137.50.750.517.68−11.0113.4Example8−10.48137.50.980.705.92−14.1615.39−11.23137.51.070.785.15−14.6415.5Example107.801401.461.204.71−0.274.7115.041401.040.816.29−3.387.1123.251400.970.736.91−4.918.5Comparative10−5.461400.760.527.36−12.0014.1Example11−10.481400.990.705.63−14.9215.912−11.231401.080.784.88−15.3516.1Example137.801421.471.204.50−1.134.6145.041421.060.826.02−4.297.4153.251420.990.746.62−5.798.8Comparative13−5.461420.770.527.08−12.7214.6Example14−10.481421.000.715.35−15.4616.415−11.231421.090.794.62−15.8716.5Example167.801441.491.224.26−1.944.7175.041441.070.835.72−5.137.7183.251441.010.766.30−6.609.1Comparative16−5.461440.790.546.75−13.3715.0Example17−10.481441.020.725.04−15.9416.718−11.231441.110.804.33−16.3216.9

TABLE 4Structure of circularlypolarizing plateReflection characteristicsAntireflectionRetardationYR @film b*film Rin (nm)(%)550 nma*b*Δa*b*Example197.801301.631.364.904.556.7205.041301.210.976.342.186.7213.251301.140.906.890.646.9Comparative19−5.461300.920.687.46−6.6810.0Example20−10.481301.150.875.73−10.5112.021−11.231301.240.955.05−11.2012.3Example227.801351.601.334.682.265.2237.801351.180.946.11−0.396.1245.041351.110.876.65−1.886.9Comparative223.251350.900.657.21−8.9011.5Example23−5.461351.130.835.47−12.2613.424−10.481351.220.914.80−12.8413.7Example257.80137.51.601.334.511.164.7265.04137.51.180.945.90−1.596.1273.25137.51.110.866.45−3.057.1Comparative25−5.46137.50.900.656.98−9.9112.1Example26−10.48137.51.130.835.26−13.0514.127−11.23137.51.220.914.60−13.5814.3Example287.801401.611.334.300.114.3295.041401.190.945.65−2.736.3303.251401.120.876.18−4.157.4Comparative28−5.461400.910.656.67−10.8212.7Example29−10.481401.140.835.00−13.7714.630−11.231401.230.914.35−14.2614.9Example317.801421.621.344.11−0.694.2325.041421.200.955.41−3.586.5333.251421.130.885.93−4.977.7Comparative31−5.461420.920.666.38−11.4913.1Example32−10.481421.150.844.76−14.2915.133−11.231421.240.924.12−14.7615.3Example347.801441.641.353.90−1.454.2355.041441.220.965.14−4.376.7363.251441.150.895.65−5.738.1Comparative34−5.461440.940.676.05−12.0913.5Example35−10.481441.170.864.49−14.7615.436−11.231441.260.943.86−15.2115.7

TABLE 5Structure of circularlypolarizing plateReflection characteristicsAntireflectionRetardationYR @film b*film Rin (nm)(%)550 nma*b*Δa*b*Example377.801301.481.234.915.727.5385.041301.060.846.523.307.3393.251300.990.777.141.607.3Comparative37−5.461300.770.557.66−6.5410.1Example38−10.481301.000.735.87−10.7112.239−11.231301.090.815.11−11.4112.5Example407.801351.451.204.493.525.7417.801351.030.816.050.806.1425.041350.960.736.66−0.876.7Comparative403.251350.750.527.03−8.6411.1Example41−5.461350.980.705.36−12.3513.542−10.481351.070.784.62−12.9513.7Example437.80137.51.451.194.212.474.9445.04137.51.030.805.70−0.385.7453.25137.50.960.736.31−2.016.6Comparative43−5.46137.50.750.516.62−9.5911.7Example44−10.48137.50.980.705.00−13.0714.045−11.23137.51.070.784.27−13.6214.3Example467.801401.461.203.881.484.1475.041401.040.815.30−1.475.5483.251400.970.735.88−3.066.6Comparative46−5.461400.750.526.16−10.4412.1Example47−10.481400.980.704.58−13.7014.448−11.231401.080.783.87−14.2114.7Example497.801421.471.203.580.723.7505.041421.050.824.92−2.285.4513.251420.980.745.49−3.836.7Comparative49−5.461420.770.525.75−11.0512.5Example50−10.481421.000.714.19−14.1514.851−11.231421.090.793.51−14.6315.0Example527.801441.491.223.260.013.3535.041441.070.834.52−3.025.4543.251441.000.765.06−4.546.8Comparative52−5.461440.780.545.31−11.6012.8Example53−10.481441.020.723.78−14.5415.054−11.231441.110.803.12−15.0015.3

TABLE 6Structure of circularlypolarizing plateReflection characteristicsAntireflectionRetardationYR @film b*film Rin (nm)(%)550 nma*b*Δa*b*Example557.801301.481.234.915.727.5565.041301.060.846.523.307.3573.251300.990.777.141.607.3Comparative55−5.461300.770.557.66−6.5410.1Example56−10.481301.000.735.87−10.7112.257−11.231301.090.815.11−11.4112.5Example587.801351.451.204.493.525.7597.801351.030.816.050.806.1605.041350.960.736.66−0.876.7Comparative583.251350.750.527.03−8.6411.1Example59−5.461350.980.705.36−12.3513.560−10.481351.070.784.62−12.9513.7Example617.80137.51.451.194.212.474.9625.04137.51.030.805.70−0.385.7633.25137.50.960.736.31−2.016.6Comparative61−5.46137.50.750.516.62−9.5911.7Example62−10.48137.50.980.705.00−13.0714.063−11.23137.51.070.784.27−13.6214.3Example647.801401.461.203.881.484.1655.041401.040.815.30−1.475.5663.251400.970.735.88−3.066.6Comparative64−5.461400.750.526.16−10.4412.1Example65−10.481400.980.704.58−13.7014.466−11.231401.080.783.87−14.2114.7Example677.801421.471.203.580.723.7685.041421.050.824.92−2.285.4693.251420.980.745.49−3.836.7Comparative67−5.461420.770.525.75−11.0512.5Example68−10.481421.000.714.19−14.1514.869−11.231421.090.793.51−14.6315.0Example707.801441.491.223.260.013.3715.041441.070.834.52−3.025.4723.251441.000.765.06−4.546.8Comparative70−5.461440.780.545.31−11.6012.8Example71−10.481441.020.723.78−14.5415.072−11.231441.110.803.12−15.0015.3

EXPLANATION OF REFERENCE NUMERALS

100: circularly polarizing plate,10: antireflection film,20: polarizer,30: retardation film40: pressure-sensitive adhesive layer,200: OLED panel