Multilayer reflective polarizer
Multilayer reflective polarizers are described. More particularly, multilayer reflective polarizers having a higher block light transmission at longer wavelengths than shorter wavelengths while having a high pass light transmission are described. The described multilayer reflective polarizers may be combined with absorbing polarizers or used in display devices.
1. A reflective polarizer, comprising:
a plurality of alternating high and low index layers, the high index layers being birefringent and including polyethylene terephthalate and polyethylene naphthalate and the low index layers being substantially isotropic and including polycarbonate and polyethylene terephthalate,
wherein a layer profile of the high and low index layers has a slope of about 0.3 nanometers/layer, and
wherein a pass transmission percentage for light having a wavelength between 400 nanometers and 800 nanometers at normal incidence and at 60° is greater than 80%.
2. The reflective polarizer of claim 1 , wherein a block transmission percentage for light having a wavelength between 900 nanometers and 1200 nanometers is greater than 20%.
3. The reflective polarizer of claim 1 , wherein the high index layers include 90% polyethylene naphthalate and 10% polyethylene terephthalate.
4. The reflective polarizer of claim 1 , wherein a glass transition temperature of the low index layers is 105° C.
5. The reflective polarizer of claim 1 , wherein a refractive index of the low index layers is about 1.57.
6. The reflective polarizer of claim 1 , wherein a thickness of the reflective polarizer is about 16.3 micrometers.
7. The reflective polarizer of claim 1 , wherein the low index layers include polycarbonate and copolyester.
8. The reflective polarizer of claim 7 , wherein the low index layers include a molar ratio of about 42.5 mol % polycarbonate and 57.5 mol % copolyester.
9. The reflective polarizer of claim 1 , further including an additional plurality of alternating high and low index layers,
wherein a layer profile of the additional plurality of alternating high and low index layers has a slope of about 0.9 nanometers/layer.
10. The reflective polarizer of claim 9 , wherein the plurality of alternating high and low index layers corresponds to layers 1 through 150 and the additional plurality of alternating high and low index layers corresponds to layers 151-183.