Stacked transparent film and window for display device and display device
A stacked transparent film includes a polymer film including at least one of an amide structural unit and an imide structural unit, wherein the polymer film has a refractive index of about 1.65 to about 1.75 at a 550 nanometer wavelength and an elastic modulus of greater than or equal to about 5.5 gigapascals; and at least one of a first coating layer on a first side of the polymer film and a second coating layer on a side opposite the first side of the polymer film.
1. A stacked transparent film comprising
a polyamide-polyimide polymer film comprising an amide structural unit and an imide structural unit, wherein the polymer film has a refractive index of about 1.65 to about 1.75 at a 550 nanometer wavelength and an elastic modulus of greater than or equal to about 5.5 gigapascals; and
at least one of a first coating layer on a first side of the polymer film and a second coating layer on a side opposite the first side of the polymer film,
wherein the polyamide-imide polymer film is obtained by
preparing an amide group-containing oligomer by reacting a dicarboxylic acid compound and a diamine compound; and
reacting an anhydride and the amide group-containing oligomer.
2. The stacked transparent film of claim 1 , wherein a light transmittance of the stacked transparent film in a visible ray region is greater than a light transmittance of the polymer film in a visible ray region.
3. The stacked transparent film of claim 1 , wherein a pencil hardness of the stacked transparent film is greater than a pencil hardness of the polymer film, each as measured according to ASTM D3363.
4. The stacked transparent film of claim 3 , wherein the pencil hardness of the polymer film is greater than or equal to 2H and the pencil hardness of the stacked transparent film is greater than or equal to 4H, each as measured according to ASTM D3363.
5. The stacked transparent film of claim 1 , wherein an absolute value of a yellow index of the stacked transparent film is less than an absolute value of a yellow index of the polymer film, each as measured according to ASTM D1925.
6. The stacked transparent film of claim 5 , wherein the absolute value of the yellow index of the polymer film is about 2.2 to about 3.6 at a thickness of 50 micrometers, as measured according to ASTM D19251, and the absolute value of the yellow index of the stacked transparent film is less than or equal to about 2.0, as measured according to ASTM D1925.
7. The stacked transparent film of claim 1 , wherein the first coating layer has a refractive index of about 1.45 to about 1.55 at a 550 nanometer wavelength.
8. The stacked transparent film of claim 1 , wherein the first coating layer comprises a polysiloxane copolymer having a cross-linked structure.
9. The stacked transparent film of claim 8 , wherein the first coating layer further comprises inorganic particles dispersed in the polysiloxane copolymer or chemically bound to the polysiloxane copolymer.
10. The stacked transparent film of claim 8 , wherein the first coating layer further comprises a light absorbing material that absorbs light in at least a portion of an about 570 nanometer to about 780 nanometer wavelength region.
11. The stacked transparent film of claim 1 , wherein the second coating layer comprises a light absorbing material that absorbs light in at least a portion of an about 570 nanometer to about 780 nanometer wavelength region.
12. The stacked transparent film of claim 1 , wherein the second coating layer has a refractive index of about 1.50 to about 1.65.
13. The stacked transparent film of claim 1 , wherein the stacked transparent film comprises the second coating layer, and further comprises a transparent adhesive layer on a side of the second coating layer opposite the polymer film.
14. The stacked transparent film of claim 13 , wherein the transparent adhesive layer has a refractive index of about 1.45 to about 1.55.
15. The stacked transparent film of claim 1 , wherein the stacked transparent film has a light transmittance of greater than or equal to about 85%, a pencil hardness of greater than or equal to 4H, as measured according to ASTM D3363, and an absolute value of a yellow index of less than or equal to about 2.0, as measured according to ASTM D1925, simultaneously.
16. The stacked transparent film of claim 1 , wherein the polymer film has a thickness of about 20 micrometers to about 100 micrometers.
17. A window for a display device, the window comprising the stacked transparent film of claim 1 .
18. A display device comprising the stacked transparent film of claim 1 .
19. An amide-imide copolymer film having a thickness of about 20 micrometers to about 100 micrometers, a refractive index of about 1.65 to about 1.75 at a 550 nanometer wavelength, and an elastic modulus of greater than or equal to about 5.5 gigapascals,
wherein the amide-imide copolymer film is obtained by
preparing an amide group-containing oligomer by reacting a dicarboxylic acid compound and a diamine compound; and
reacting an anhydride and the amide group-containing oligomer.
20. The amide-imide copolymer film of claim 19 , wherein a pencil hardness of the amide-imide copolymer film is greater than or equal to 2H, as measured according to ASTM D3363.
21. The amide-imide copolymer film of claim 19 , wherein an absolute value of a yellow index of the amide-imide copolymer film is about 2.2 to about 3.6 at the thickness of 50 micrometers, as measured according to ASTM D1925.
22. A window for a display device, the window comprising the amide-imide copolymer film of claim 19 .
23. A display device comprising the amide-imide copolymer film of claim 19 .