METHOD FOR MANUFACTURING THIN POLARIZER, AND THIN POLARIZER MANUFACTURED USING SAME

Abstract

The present invention relates to a method for manufacturing a thin polarizer, the method including: a step of preparing an unstretched polyvinyl alcohol-based film having a thickness of 20 m or less, in which a strength applied to stretch the film by 6 times is 4 N or more; and a single stretching step of forming a stretched polyvinyl alcohol-based film having a thickness of 10 m or less by stretching the unstretched polyvinyl alcohol-based film solely, and a thin polarizer manufactured by using the same.

Claims

1. A method for manufacturing a thin polarizer, the method comprising: a step of preparing an unstretched polyvinyl alcohol-based film having a thickness of 20 m or less, in which a strength applied to stretch the film by 6 times is 4 N or more; and a single stretching step of forming a stretched polyvinyl alcohol-based film having a thickness of 10 m or less by stretching the unstretched polyvinyl alcohol-based film solely.

2. The method of claim 1, wherein the unstretched polyvinyl alcohol-based film has an elastic modulus of less than 2 MPa.

3. The method of claim 1, wherein a strength applied to stretch the unstretched polyvinyl alcohol-based film by 6 times is a value measured by a method of stretching the film in an aqueous boric acid solution in a range of 1% to 5% in a temperature range of 50 C. to 60 C.

4. The method of claim 1, wherein the single stretching step is performed by a wet stretching method or a dry stretching method.

5. The method of claim 1, wherein the single stretching step is performed at a stretching magnification of 3 times to 15 times at a temperature of 20 C. to 85 C.

6. The method of claim 1, wherein the single stretching step is performed in an aqueous boric acid solution having a boric acid concentration of 1 wt % to 5 wt %.

7. The method of claim 1, wherein the unstretched polyvinyl alcohol-based film has a polymerization degree of 2,500 to 3,500.

8. The method of claim 1, further comprising: a step of dyeing the unstretched polyvinyl alcohol-based film with at least one of iodine and a dichroic dye before the single stretching step.

9. A thin polarizer manufactured by the method of claim 1, wherein a thickness is 10 m or less, a single transmittance is 40% to 45%, and a polarization degree is 99% or more.

10. A thin polarizer manufactured by the method of claim 2, wherein a thickness is 10 m or less, a single transmittance is 40% to 45%, and a polarization degree is 99% or more.

11. A thin polarizer manufactured by the method of claim 3, wherein a thickness is 10 m or less, a single transmittance is 40% to 45%, and a polarization degree is 99% or more.

12. A thin polarizer manufactured by the method of claim 4, wherein a thickness is 10 m or less, a single transmittance is 40% to 45%, and a polarization degree is 99% or more.

13. A thin polarizer manufactured by the method of claim 5, wherein a thickness is 10 m or less, a single transmittance is 40% to 45%, and a polarization degree is 99% or more.

14. A thin polarizer manufactured by the method of claim 6, wherein a thickness is 10 m or less, a single transmittance is 40% to 45%, and a polarization degree is 99% or more.

15. A thin polarizer manufactured by the method of claim 7, wherein a thickness is 10 m or less, a single transmittance is 40% to 45%, and a polarization degree is 99% or more.

16. A thin polarizer manufactured by the method of claim 8, wherein a thickness is 10 m or less, a single transmittance is 40% to 45%, and a polarization degree is 99% or more.

Description

EXAMPLE 1

[0048] An unstretched polyvinyl alcohol-based film (manufactured by Nippon Synthesis Co., Ltd., M-series), in which the strength applied to the film was 4.8 N, the elastic modulus was 1.5 MPa, and the thickness was 20 m when the film was stretched by 6 times, was prepared.

[0049] Next, the unstretched polyvinyl alcohol-based film was subjected to cleaning process in a 1.0 wt % boric acid solution for 15 seconds, and then stretched solely in a 2.0 wt % boric acid solution at a stretching magnification of 6 times. And then, the polyvinyl alcohol-based film was subjected to complementary color process in a 5.0 wt % potassium iodide (KI) solution, and then dried in an oven at 80 C., thereby obtaining a thin polarizer having a thickness of 8 m.

COMPARATIVE EXAMPLE 1

[0050] A thin polarizer was intended to be manufactured in the same manner as in Example 1 by using an unstretched polyvinyl alcohol-based film, in which the strength applied to the film was 3.3 N and the elastic modulus was 2.8 MPa when the film was stretched by 6 times, but it was difficult to manufacture a thin polarizer because break was caused when the film was stretched.

COMPARATIVE EXAMPLE 2

[0051] A thin polarizer having a thickness of 8.3 m was manufactured in the same manner as in Example 1, except that an unstretched polyvinyl alcohol-based film, in which the strength applied to the film was 4.8 N and the elastic modulus was 2.8 MPa when the film was stretched by 6 times, was used.

EXPERIMENTAL EXAMPLE 1

Measurement of Optical Characteristics

[0052] The optical characteristics of the thin polarizers manufactured in Example 1 and Comparative Example 2 were measured by JASCO V-7100 spectrophotometer, and are shown in the following [Table 1].

TABLE-US-00001 TABLE 1 Single Polarization Single Orthogonal transmittance degree color color Classification (%) (%) a b a b Example 1 41.88 99.9827 0.40 2.01 1.11 1.79 Comparative 41.62 99.9642 0.03 1.56 1.98 2.61 Example 2

[0053] Through the [Table 1], it can be seen that the thin polarizer of Example 1, which is manufactured according to the method of the present invention, was excellent in all the optical properties such as single transmittance, a polarization degree, and a color. In contrast, it can be seen that in the case of Comparative Example 1, it was difficult to manufacture a thin polarizer itself, and all the optical properties such as single transmittance, a polarization degree, and a color sense significantly deteriorate in the polarizer manufactured in Comparative Example 2.

[0054] Even though the exemplary embodiments of the present invention have been described in detail, the right scope of the present invention is not limited thereto, and it will be obvious to a person with ordinary skill in the art that various modifications and alterations are possible without departing from the technical spirit of the present invention described in the claims.