Method for preparing polarizing plate locally having depolarization region, and polarizing plate prepared by using same

Patent metadata

Field	Value
Publication number	US-10215903-B2
Application number	US-201515105938-A
Country	US
Kind code	B2
Filing date	Jun 24, 2015
Priority date	Jun 30, 2014
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

The present invention relates to a method for manufacturing a polarizing plate, the method including: preparing a polarizing plate where a protection film is laminated on one surface of a polyvinyl alcohol-based polarizer dyed with at least one or more of iodine and dichromatic dyes; and forming a depolarization region having single transmittance of 80% or more at a wavelength band in a range of 400 nm to 800 nm by bringing a decoloring solution including 1 to 30 wt % of a decolorant into local contact with the other surface of the polarizer, and a polarizing plate manufactured by using the same.

First claim

The invention claimed is:

1. A method for manufacturing a polarizing plate, the method comprising:
preparing a polarizing plate where a protection film is laminated on one surface of a polyvinyl alcohol-based polarizer dyed with at least one or more of iodine and dichromatic dyes;
forming at least one depolarization region having single transmittance of 80% or more at a wavelength band in a range of 400 nm to 800 nm and arithmetic mean roughness (Ra) of 100 nm or less, by bringing a decoloring solution including 1 to 30 wt % of a decolorant into local contact with the other surface of the polarizer; and
performing washing by using an acid solution,
wherein the forming of the depolarization region is performed by a dispenser, inkjet, or gravure printing method.

2. The method of claim 1 , wherein the decolorant includes one kind or more selected from the group consisting of sodium hydroxide (NaOH), sodium hydrosulfide (NaSH), sodium azide (NaN 3 ), potassium hydroxide (KOH), potassium hydrosulfide (KSH), and potassium thiosulfate (KS 2 O 3 ).

3. The method of claim 1 , wherein a pH of the decoloring solution is 11 to 14.

4. The method of claim 1 , wherein a viscosity of the decoloring solution is 1 cP to 2000 cP.

5. The method of claim 1 , wherein the decoloring solution further includes a viscosity agent.

6. The method of claim 5 , wherein the viscosity agent includes one kind or more selected from the group consisting of a polyvinyl alcohol-based resin, a polyvinyl acetoacetate-based resin, an acetoacetyl group-denatured polyvinyl alcohol-based resin, butenediolvinyl alcohols, a polyethylene glycol-based resin, and a polyacrylamide-based resin.

7. The method of claim 1 , wherein the decoloring solution includes: 1 wt % to 30 wt % of a decolorant; 0.5 wt % to 30 wt % of the viscosity agent; and water as a balance, based on a total weight.

8. The method of claim 1 , wherein an area of at least one depolarization region is 0.5 mm 2 or more and 500 mm 2 or less.

9. The method of claim 1 , further comprising:
after the forming of the depolarization region, forming an optical layer on at least one surface of the polarizing plate.

10. The method of claim 9 , wherein the optical layer includes a protection film, a retardation film, a luminance improvement film, a hard coating layer, an antireflection layer, a cohesive layer, an adhesion layer, or a local decoloring region which is a combination thereof.

11. A polarizing plate comprising:
a polyvinyl alcohol-based polarizer dyed with at least one or more of iodine and dichromatic dyes, and
an acryl-based protection film laminated on at least one surface of the polyvinyl alcohol-based polarizer by using a cation-based UV adhesive,
wherein the polarizing plate locally has at least one depolarization region having single transmittance of 80% or more at a wavelength band in a range of 400 nm to 800 nm, and arithmetic mean roughness (Ra) of the depolarization region is 100 nm or less.

12. The polarizing plate of claim 11 , wherein root mean square roughness (Rq) of the depolarization region is 100 nm or less.

13. The polarizing plate of claim 11 , wherein an area of at least one depolarization region is 0.5 mm2 or more and 500 mm2 or less.

14. The polarizing plate of claim 11 , wherein in the depolarization region of the polarizing plate, a polarization degree is 20% or less.

15. The polarizing plate of claim 11 , wherein in a region of the polarizing plate other than the depolarization region, the single transmittance is 40% to 45% and a polarization degree is 99% or more.

16. The polarizing plate of claim 11 , wherein in the depolarization region of the polarizing plate, a haze is 3% or less.

17. The polarizing plate of claim 11 , wherein in the depolarization region, a content of at least one or more of the iodine and dichromatic dyes is 0.1 wt % to 0.5 wt %, and in a region other than the depolarization region, the content of at least one or more of the iodine and dichromatic dyes is 1 wt % to 4 wt %.

Assignees

• Lg Chemical Ltd

Inventors

• Lee Byung Sun
• Kim Ji Young
• Nam Sung Hyun
• Rah Kyun Il

Classifications

• B32B2260/02

  Composition of the impregnated, bonded or embedded layer · CPC title

• B32B7/06

  permitting easy separation · CPC title

• B32B27/32

  comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)} · CPC title

• G02F1/13362

  providing polarized light, e.g. by converting a polarisation component into another one · CPC title

• B32B27/40

  comprising polyurethanes · CPC title