OPTICAL LAMINATE, POLARIZING PLATE, AND DISPLAY DEVICE

Abstract

The present disclosure provides an optical laminate including a polymer substrate and an antiglare layer, wherein rubber particles having a cross-sectional diameter of 10 to 500 nm exist within 50% of the thickness of the antiglare layer from the interface between the polymer substrate and the antiglare layer, a polarizing plate including the optical laminate, and a liquid crystal display and a display device including the polarizing plate.

Claims

1. An optical laminate comprising: a polymer substrate containing a polymer resin and rubber particles having a cross-sectional diameter of 10 to 500 nm dispersed in the polymer resin; and an antiglare layer containing a binder resin and organic fine particles or inorganic fine particles dispersed in the binder resin, wherein rubber particles having a cross-sectional diameter of 10 to 500 nm exist within 50% of the thickness of the antiglare layer from an interface between the polymer substrate and the antiglare layer.

2. The optical laminate of claim 1, wherein the rubber particles having a cross-sectional diameter of 10 to 500 nm exist within 30% of the thickness of the antiglare layer from the interface between the polymer substrate and the antiglare layer.

3. The optical laminate of claim 1, wherein the polymer resin includes at least one resin selected from a (meth)acrylate resin, a cellulose resin, a polyolefin resin, and a polyester resin.

4. The optical laminate of claim 1, wherein the rubber particles having a cross-sectional diameter of 10 to 500 nm existing within 50% of the thickness of the antiglare layer from the interface between the polymer substrate and the antiglare layer and the rubber particles having a cross-sectional diameter of 10 to 500 nm contained in the polymer substrate are rubber particles of the same components.

5. The optical laminate of claim 1, wherein the rubber particles include at least one rubber selected from styrene-butadiene-based rubber and acrylic-based rubber.

6. The optical laminate of claim 1, wherein the polymer substrate has a thickness of 10 to 150 μm, and the antiglare layer has a thickness of 1 to 10 μm.

7. The optical laminate of claim 1, wherein a ratio of the thickness of the antiglare layer to a thickness of the polymer substrate is 0.008 to 0.8.

8. The optical laminate of claim 1, wherein The polymer substrate includes 5 to 50 parts by weight of the rubber particles relative to 100 parts by weight of the binder resin.

9. The optical laminate of claim 1, wherein the organic fine particles contained in the antiglare layer have a cross-sectional diameter of 1 to 50 μm, and the inorganic fine particles contained in the antiglare layer have a cross-sectional diameter of 1 nm to 500 nm.

10. The optical laminate of claim 1, wherein a moisture permeation amount of the polymer substrate measured for 24 hours at 40° C. and 100% humidity is 150 g/m.sup.2 or less.

11. The optical laminate of claim 1, wherein the organic fine particles or the inorganic fine particles in the antiglare layer aggregate to form protrusions having a diameter of at least 100 μm and a ratio of the number of the protrusions formed on an outer surface of the antiglare layer is 50/m.sup.2 or less.

12. The optical laminate of claim 11, wherein the diameter of the protrusions is 100 μm to 300 μm.

13. The optical laminate of claim 11, wherein a ratio of the area of a region where the protrusions are located on the surface of the antiglare layer as defined by general formula 1 is 0.5 area % or less:
Ratio of the area of a region where the protrusions are located on a surface of the antiglare layer=(the number of protrusions*the area of a circle having a diameter of 5 mm)/the area of the surface of the antiglare layer (mm.sup.2)  [General Formula 1] wherein the “circle having a diameter of 5 mm” in the general formula 1 is defined as the region where the fine protrusions are located.

14. A polarizing plate comprising the optical laminate of claim 1.

15. A display device comprising the polarizing plate of claim 14.

16. The optical laminate of claim 4, wherein the rubber particles include at least one rubber selected from styrene-butadiene-based rubber and acrylic-based rubber.

17. The optical laminate of claim 6, wherein a ratio of the thickness of the antiglare layer to a thickness of the polymer substrate is 0.008 to 0.8.

18. The optical laminate of claim 12, wherein a ratio of the area of a region where the protrusions are located on the surface of the antiglare layer as defined by general formula 1 is 0.5 area % or less.
Ratio of the area of a region where the protrusions are located on a surface of the antiglare layer=(the number of protrusions*the area of a circle having a diameter of 5 mm)/the area of the surface of the antiglare layer (mm.sup.2)  [General Formula 1] wherein the “circle having a diameter of 5 mm” in the general formula 1 is defined as the region where the fine protrusions are located.

19. The optical laminate of claim 1, wherein the rubber particles in the polymer substrate are capable of migrating into the antiglare layer, and the migrated rubber particles exist within 50% of the thickness of the antiglare layer from the interface between the polymer substrate and the antiglare layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0144] FIG. 1 shows a cross-sectional TEM photograph of the optical laminate of Example 1.

[0145] FIG. 2 shows a cross-sectional TEM photograph of the optical laminate of Example 2.

[0146] FIG. 3 shows a cross-sectional TEM photograph of the optical laminate of Comparative Example 1.

[0147] FIG. 4 shows a cross-sectional TEM photograph of the optical laminate of Comparative Example 2.

[0148] FIG. 5 is a photograph of fine protrusions of 100 μm or more, which was confirmed in the optical laminate of Example 3, taken with a laser microscope (Optical Profiler).

[0149] FIG. 6 shows a cross-sectional TEM photograph of the optical laminate of Example 3.

[0150] FIG. 7 shows a cross-sectional TEM photograph of the optical laminate of Comparative Example 4.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0151] Hereinafter, embodiments of the present disclosure will be described in more detail by way of examples. However, these examples are provided for illustrative purposes only and are not intended to limit the scope of the present disclosure.

Preparation Example 1 and 2: Preparation of Coating Composition for Forming Antiglare Layer

Preparation Example 1

[0152] 25 wt % of pentaerythritol tri(tetra)acrylate, 22.4 wt % of UA-306T (reaction product of toluene diisocyanate and pentaerythritol triacrylate as urethane acrylate, manufactured by Kyoeisha Chemical), 2.5 wt % of Irgacure 184 as a photopolymerization initiator, 24.5 wt % of ethanol, 24.5 wt % of 2-butanol, 1 wt % of XX-113BQ (average diameter: 2.0 μm, refractive index: 1.555, copolymerized particles of polystyrene and polymethyl methacrylate, manufactured by Sekisui Plastic), 0.1 wt % of MA-ST (silica particles having a diameter of 15 nm, manufactured by Nissan Chemical) were mixed to prepare a coating composition for forming an antiglare layer.

Preparation Example 2

[0153] 25 wt % of pentaerythritol tri(tetra)acrylate, 22.4 wt % of 2-hydroxy ethyl acrylate, 2.5 wt % of Irgacure 184 as a photopolymerization initiator, 24.5 wt % of methyl ethyl ketone, 24.5 wt % of 2-butanol, 1 wt % of XX-113BQ (average diameter: 2.0 μm, refractive index: 1.555, copolymerized particles of polystyrene and polymethyl methacrylate, manufactured by Sekisui Plastic), and 0.1 wt % of MA-ST (silica particles having a diameter of 15 nm, manufactured by Nissan Chemical) were mixed to prepare a coating composition for forming an antiglare layer.

Examples 1 and 2 and Comparative Examples 1 and 2: Preparation of Optical Laminate

Example 1

[0154] The coating composition for forming an antiglare layer of Preparation Example 1 was coated onto an acrylic film (WOLF, provided by Sumitomo, thickness: 60 μm) containing rubber particles having an average diameter of 300 nm a bar coating method so that the thickness after drying was about 5 μm.

[0155] Then, the film coated with the composition was dried at 40° C. for 2 minutes, and cured under a condition of 50 mJ/cm.sup.2 with a mercury lamp.

Example 2

[0156] The coating composition for forming an antiglare layer of Preparation Example 1 was coated onto an acrylic film (WOLF, provided by Sumitomo, thickness: 60 μm) containing rubber particles having an average diameter of 300 nm by a bar coating method so that the thickness after drying was about 5 μm.

[0157] Then, the film coated with the composition was dried at 70° C. for 2 minutes, and cured under a condition of 50 mJ/cm.sup.2 with a mercury lamp.

Comparative Example 1

[0158] The coating composition for forming an antiglare layer of Preparation Example 1 was coated onto an acrylic film (WOLF, provided by Sumitomo, thickness: 60 μm) containing rubber particles having an average diameter of 300 nm by a bar-coating method so that the thickness after drying was about 5 μm.

[0159] Then, the film coated with the composition was dried at 90° C. for 2 minutes, and cured under a condition of 50 mJ/cm.sup.2 with a mercury lamp.

Comparative Example 2

[0160] The coating composition for forming an antiglare layer of Preparation Example 2 was coated onto an acrylic film (WOLF, provided by Sumitomo, thickness: 60 μm) containing rubber particles having an average diameter of 300 nm by a bar-coating method so that the thickness after drying was about 5 μm.

[0161] Then, the film coated with the composition was dried at 40° C. for 2 minutes, and cured under a condition of 50 mJ/cm.sup.2 with a mercury lamp.

Experimental Example: Measurement of Physical Properties of Optical Laminate

Experimental Example 1: Evaluation of Haze of Optical Laminate

[0162] The internal haze and the external haze of the optical laminates prepared in Examples and Comparative Examples were determined, and the total haze value was determined.

[0163] Specifically, using a haze meter (HM-150, A light source, manufactured by Murakami Color Research Laboratory), the transmittance was measured three times according to JIS K 7361 standard, and the haze was measured three times according to JIS K 7105 standard, and then then the average value of each measurement was calculated to obtain the total haze.

[0164] Further, in order to make the surface of the manufactured coating layer flat, an adhesive having a haze of 0 was attached to the surface so that external irregularities were embedded in the adhesive, and then, the haze was measured three times with a haze meter, and the average value was calculated to obtain the internal haze.

[0165] Thereafter, the external haze value was obtained by subtracting the internal haze value from the total haze value.

Experimental Example 2: Measurement of Image Sharpness (%)

[0166] The image sharpness of the optical laminates obtained in each of Examples and Comparative Examples was measured using ICM-1T manufactured by Suga Test Instrument Co., Ltd.

[0167] The image sharpness was measured with slit widths of 0.125 mm, 0.5 mm, 1 mm and 2 mm and displayed as a total.

Experimental Example 3. Measurement of Cross-Section

[0168] Using an electron transmission microscope (TEM), the area where the rubber particles are present inside the antiglare layer in each of the optical laminates of Examples and Comparative Examples was specifically confirmed, and the results are shown in FIGS. 1 to 4.

Experimental Example 4. Measurement of Scratch Resistance

[0169] The surface of the optical Laminates obtained in Examples and Comparative Examples were rubbed back and forth 10 times with a steel wool (#0000) under a load at a speed of 27 rpm.

[0170] The scratch resistance was evaluated by confirming the maximum load at which the number of scratches of 1 mm or more was 1 or less by observing with the naked eye.

TABLE-US-00001 TABLE 1 Comparative Comparative Example 1 Example 2 Example 1 Example 2 Haze(%) 3.0 2.7 1.8 1.9 External haze (%) 0.5 0.4 0.0 0.1 Internal haze (%) 2.5 2.3 1.8 1.8 Image sharpness 305 310 340 335 Maximum thickness 0% 29% 100% 62% at which rubber particles were observed Scratch resistance 500 gf 500 gf Less than Less than 100 gf 100 gf

[0171] Further, as shown in FIG. 1, it was confirmed that in the optical laminate of Example 1, the rubber particles do not exist in the antiglare layer beyond the interface between the polymer substrate and the antiglare layer, and that in the optical laminate of Example 2, the rubber particles having a cross-sectional diameter of 10 to 500 nm exist within 29% of the thickness of the antiglare layer from the interface between the polymer substrate and the antiglare layer.

[0172] In contrast, it was confirmed that in the optical laminate of Comparative Example 1, the rubber particles existing in a polymer substrate exists even in the entire area of the antiglare layer, and it was confirmed that in the optical laminate of Comparative Example 2, the rubber particle having a cross-sectional diameter of 10 to 500 nm exists up to a range of 62% of the thickness of the antiglare layer from the interface between the polymer substrate and the antiglare layer.

[0173] On the other hand, as shown in Table 1, it was confirmed that the optical laminates of Examples 1 and 2 have a haze and high image sharpness at the level that antiglare property can be realized while having a high scratch resistance, whereas the optical laminates of Comparative Examples 1 and 2 have a low level of scratch resistance, and they had an external haze value that was difficult to have anti-glare property.

Examples 3 to 5 and Comparative Examples 3 to 4: Preparation of Optical Laminate

[0174] (1) Preparation of Coating Composition for Forming Antiglare Layer

[0175] The components shown in Table 2 below were mixed to prepare a coating composition for forming an antiglare layer.

[0176] (2) Preparation of Optical Laminate

[0177] Each of the above-prepared coating solutions for forming the antiglare layer was coated onto the polymer substrate described in Table 2 below by #12 mayer bar, and then dried at a temperature of 40° C. for 2 minutes, followed by UV curing to form an antiglare layer (coating thickness of 4 μm).

[0178] When UV curing, the UV lamp used a H bulb, the curing reaction was carried out under a nitrogen atmosphere, and the amount of UV light irradiated during curing is 150 mJ/cm.sup.2.

TABLE-US-00002 TABLE 2 Comparative Comparative Example 3 Example 4 Example 5 Example 3 Example 4 Acryl film(WOLF, provided by Sumitomo, thickness: 60 μm, containing Polymer substrate acrylic rubber particles having an average diameter of 300 nm) Antiglare layer TMPTA 9.85 7.88 8.77 10.7 8.76 coating PETA 6.11 7.88 7.18 4.67 6.81 composition UA-306T 6.11 5.32 6.98 4.67 5.26 G8161 6.9 7.88 5.98 8.76 7.79 D1173 0.89 0.83 0.83 0.83 0.83 I184 0.89 0.83 0.83 0.83 0.83 Tego270 0.04 0.04 0.06 0.04 0.05 BYK350 0.07 0.07 0.07 0.07 0.07 Organic fine 0.97 1.16 1.32 1.15 1.31 particle XX-103BQ Inorganic fine 0.18 0.18 0.18 0.2 0.16 particle MA-ST EtOH 41.84 9.73 n-BA 12.81 12.8 13.12 29.2 2-BuOH 55.18 55.13 54.68 26.24 29.2 Coating 4 4 4 4 4 thickness (μm) TMPTA: trimethyloylpropyltriacrylate PETA: pentaerythritol triacrylate UA-306T: reaction product of toluene diisocyanate and pentaerythritol triacrylate as urethane acrylate (manufactured by Kyoeisha Chemical) G8161: photocurable acrylate polymer (Mw~200,000, manufactured by San Nopco) IRG-184: initiator (Irgacure 184, Ciba) Tego-270: leveling agent (Tego) BYK350: leveling agent (BYK Chemie) IPA: Isopropyl Alcohol XX-103BQ (2.0 μm 1.515): Copolymerized particles of polystyrene and polymethyl methacrylate (manufactured by Sekisui Plastic) XX-113BQ (2.0 μm 1.555): Copolymerized particles of polystyrene and polymethyl methacrylate (manufactured by Sekisui Plastic) MA-ST (30% in MeOH): a dispersion in which nanosilica particles with a size of 10 to 15 nm are dispersed in methyl alcohol (product of Nissan Chemical) EtOH: ethanol n-BA: n-butyl acetate 2-BuOH: 2-butanol

Experimental Example: Measurement of Physical Properties of Optical Laminate

Experimental Example 5. Confirmation of the Ratio of Fine Particles that Aggregate on the Surface of the Antiglare Layer

[0179] Samples cut into 50 cm*50 cm (width*length) from the optical laminates obtained in each of Examples and Comparative Examples were placed on black matt paper under LED illumination with a illuminance of 700 lux.

[0180] Then, the film was arranged so that light was made incident at 70 degrees based on the surface of the sample film, and then observed from the side where the light was reflected to find fine protrusions having stronger sparkling than the peripheral part.

[0181] The parts confirmed by the fine protrusions were represented by circles of 5 mm in diameter, and the number of protrusions and the protrusion area ratios were calculated according to the following general formula.

[0182] At this time, the number of protrusions was calculated by the following general formula 2, the ratio of the area where fine protrusions having a diameter of 100 μm or more were formed on the outer surface of the antiglare layer of the aggregate of the organic fine particles or inorganic fine particles was defined by the following general formula 1.

The ratio of the area where the fine protrusions are located on one surface of the antiglare layer=(the number of fine protrusions*the area of a circle having a diameter of 5 mm)/the area of one side of the antiglare layer (mm.sup.2)  [General Formula 1]

[0183] The “circle having a diameter of 5 mm” in the general formula 1 is defined as an area where the fine protrusions are located.

Number of protrusions (number/m.sup.2): Number measured at 50 cm*50 cm*4  [General Formula 2]

TABLE-US-00003 TABLE 3 Result of Experimental Example Comparative Comparative Example 3 Example 4 Example 5 Example 3 Example 4 Haze(%) 2.1 2.1 2 2.0 2.1 Image sharpness 368 360 343 300 or less 300 or less Number of 3 16 38 about 1000 about 300 protrusions (number(s)/m2) Area ratio of <0.1 <0.1 <0.1  ~2%  0.5% protrusion (%) Maximum thickness <25% <25% <50% <25% <90% at which rubber particles were observed Scratch resistance 700 gf 700 gf 500 gf 500 gf 500 gf NG *Haze evaluation, image sharpness(%) measurement, cross-section measurement of the optical laminates were performed by the methods of Experimental Examples 1 to 4.

[0184] As shown in Table 3, it was confirmed that the optical laminates of Examples have fine protrusions existing on the outer surface of the antiglare layer of 50/m.sup.2 or less, and realize a haze and high image sharpness at the level that antiglare property can be realized while having a high scratch resistance.

[0185] On the contrary, it was confirmed that the optical laminates of Comparative Examples have the ratio of the fine protrusions existing on the outer surface of the antiglare layer of 100/m.sup.2 or more, and realize a low level of scratch resistance or a relatively low image sharpness.

[0186] Further, as shown in FIG. 6, it was confirmed that in the optical laminate of Example 3, the rubber particles having a cross-sectional diameter of 10 to 500 nm exist within 25% of the thickness of the antiglare layer from the interface between the polymer substrate and the antiglare layer.

[0187] On the contrary, as shown in FIG. 7, it was confirmed that in the optical laminate of Comparative Example 4, the rubber particle having a cross-sectional diameter of 10 to 500 nm exists from the interface between the polymer substrate and the antiglare layer to a range of 90% of the thickness of the antiglare layer.

EXPLANATION OF SYMBOLS

[0188] 1 polymer substrate [0189] 2 antiglare layer [0190] 3 rubber particles [0191] 4 interface between polymer substrate and antiglare layer [0192] 5 surface of antiglare layer [0193] 6 Maximum range where rubber particles exist from the interface between the polymer substrate and the antiglare layer