Stretched laminate, method of manufacturing thin polarizer, thin polarizer manufactured by the method, and polarizing plate including the thin polarizer
There is provided a stretched laminate having superior optical characteristics, easily separable from a base film, and usable for manufacturing a thin polarizer. In addition, there are provided a method of manufacturing a thin polarizer having superior optical characteristics by using the stretched laminate, a thin polarizer manufactured by the method, and a polarizing plate including the thin polarizer.
1. A stretched laminate formed by stretching a laminate comprising: a non-stretched polymer film; and a non-stretched polyvinyl alcohol-based film attached to at least one surface of the polymer film wherein the polymer film is a thermoplastic polyurethane film,
wherein both the polymer film and the polyvinyl alcohol-based film satisfy Formula 1 below in case of
x
=
film
thickness
after
stretching
film
thickness
before
stretching
and
y
=
film
width
after
stretching
film
width
before
stretching
:
y≤− 0.175 x+ 0.675 [Formula 1]
where 0.16≤x<1, and 0<y<1.
2. The stretched laminate of claim 1 , wherein both the polymer film and the polyvinyl alcohol-based film further satisfy Formula 2 below:
−1.350 x+ 0.830≤ y [Formula 2]
where 0.16≤x<1, and 0<y<1.
3. The stretched laminate of claim 1 ,
wherein the laminate further comprises an adhesive layer between the non-stretched polymer film and the non-stretched polyvinyl alcohol-based film,
wherein an adhesive force between the polyvinyl alcohol-based film and the polymer film of the stretched laminate is 0.1 N/2 cm to 2 N/2 cm.
4. A method of manufacturing a thin polarizer, the method comprising:
forming a laminate by attaching a non-stretched polyvinyl alcohol-based film to at least one surface of a non-stretched polymer film, wherein the non-stretched polymer film is a thermoplastic polyurethane film; and
stretching the laminate such that both the polymer film and the polyvinyl alcohol-based film thickness after stretching film satisfy Formula 1 below in case of below in case of
x
=
film
thickness
after
stretching
film
thickness
before
stretching
and
y
=
film
width
after
stretching
film
width
before
stretching
:
y≤− 0.175 x+ 0.675 [Formula 1]
where 0.16≤x<1, and 0<y<1, and
wherein an adhesive force between the polyvinyl alcohol-based film and the polymer film of the stretched laminate is 0.1 N/2 cm to 2 N/2 cm.
5. The method of claim 4 , wherein the stretching of the laminate is performed such that both the polymer film and the polyvinyl alcohol-based film satisfy Formula 2 below:
0.350 x+ 0.830≤ y [Formula 2]
where 0.16≤x<1, and 0<y<1.
6. The method of claim 4 , wherein the forming of the laminate comprises attaching the non-stretched polymer film and the non-stretched polyvinyl alcohol-based film to each other by using an adhesive.
7. The method of claim 4 , wherein the stretching of the laminate is performed such that the polyvinyl alcohol-based film has a thickness of 60 μm or less before the stretching and a thickness of 10 μm or less after the stretching.
8. The method of claim 4 , wherein the stretching of the laminate is performed within a temperature range of 20° C. to 80° C. at a stretching ratio of 5 times to 15 times.
9. The method of claim 4 , wherein the stretching of the laminate is performed in an aqueous boric acid solution having a boric acid content of 1 wt % to 5 wt %.
10. The method of claim 4 , wherein after the stretching of the laminate, an adhesive force between the stretched polyvinyl alcohol-based film and the stretched polymer film is 2 N/2 cm or less.
11. The method of claim 4 , wherein before the stretching of the laminate, the method further comprises dyeing the non-stretched polyvinyl alcohol-based film with one or more of iodine and a dichroic dye.
12. The method of claim 4 , wherein after the stretching of the laminate, the method further comprises separating the stretched polyvinyl alcohol-based film from the stretched polymer film.
13. The method of claim 12 , wherein the separating of the stretched polyvinyl alcohol-based film from the stretched polymer film is performed by applying peel force of 2 N/2 cm or less.