Reflective polarizer having a dispersed polymer
A reflective polarizer of the invention has excellent optical properties even though a very small number of polymer components per unit area is disposed inside a matrix thereof compared to reflective polarizers of the related art, which include birefringent polymer, since the polymer inside the matrix has a plate-like shape. This is advantageous for covering the entire range of visible light, since a plate-like polymer having a variety of optical thicknesses can be used. The additional processing of bonding the skin layer is not performed, since the skin layer is formed on at least one surface of the core layer in the state in which it is molten. This can greatly reduce manufacturing costs, and is advantageous in that it maximizes optical properties in a limited thickness.
1. A reflective polarizer comprising; a plurality of disperse phases being dispersed in a matrix in order to allow a first polarization, which is emitted from outside, to pass through while reflecting a second polarization, wherein a refractive index of the plurality of disperse phases is different in at least one axial direction from that of the matrix, a light modulation interface is formed between the plurality of disperse phases and the matrix, an aspect ratio, which is a ratio of a length of a long axis to a length of a short axis with respect to a vertical cross-section of a polarizer, does not exceed 1/1000 .
2. The reflective polarizer of claim 1 , wherein the matrix is stretched in at least one axial direction.
3. The reflective polarizer of claim 1 , wherein a difference in refractive indexes between the matrix and the plurality of disperse phases is 0.05 or less in two axial directions and 0.1 or more in a third axial direction.
4. The reflective polarizer of claim 1 , wherein a skin layer is integrally formed on at least one surface of the matrix.
5. The reflective polarizer of claim 4 , wherein a bonding layer is not formed between the matrix and the skin layer.
6. The reflective polarizer of claim 1 , wherein the plurality of disperse phases has 100 layers or more with respect to a vertical cross-section in a lengthwise direction of the plurality of disperse phases, the layers being separated from each other.
7. The reflective polarizer of claim 1 , wherein the plurality of disperse phases has 400 layers or more with respect to a vertical cross-section in a lengthwise direction of the plurality of disperse phases, the layers being separated from each other.
8. The reflective polarizer of claim 1 , wherein the aspect ratio is 1/5000 or less.
9. The reflective polarizer of claim 1 , wherein the aspect ratio is 1/10000 or less.
10. The reflective polarizer of claim 1 , wherein the aspect ratio is 1/30000 or less.
11. The reflective polarizer of claim 1 , wherein the length of the short axis of the vertical cross-section of the plurality of disperse phases ranges from 0.01 μm to 1.0 μm.
12. The reflective polarizer of claim 1 , wherein 50% or more of the plurality of disperse phases satisfies the aspect ratio.
13. The reflective polarizer of claim 1 , wherein the plurality of disperse phases in the matrix has a width of 1580 mm and a height of 400 μm with respect to the vertical cross-section of the reflective polarizer is one million or less.
14. The reflective polarizer of claim 13 , wherein the plurality of disperse phases is 500 thousand or less.
15. The reflective polarizer of claim 13 , wherein the plurality of disperse phases is 300 thousand or less.
16. The reflective polarizer of claim 13 , wherein a transmittance of a reflective polarizer in a direction of a transmission axis is 87% or more, and a transmittance of a reflective polarizer in a direction of a reflection axis is 10% or less.
17. The reflective polarizer of claim 6 , wherein an average distance d 1 between adjacent disperse phases that form a same layer is smaller than an average distance d 2 between adjacent disperse phases that form different layers.
18. A backlight unit comprising the reflective polarizer as set forth in claim 1 .