PROTECTIVE FILM FOR A POLARIZER, A POLARIZING PLATE COMPRISING THE SAME, AND A DISPLAY DEVICE WITH THE POLARIZING PLATE

• US 20170363778A1
• Filed: 06/19/2017
• Published: 12/21/2017
• Est. Priority Date: 06/20/2016
• Status: Active Grant

• Current Assignee: SK Microworks Company Limited
• Original Assignee: SKC Company Limited
• Inventors: LEE, Se Chul, HEO, Young Min, JEONG, Da Woo, KANG, Ho Chun, LEE, Jang Won
• Granted Patent: US 10,088,606 B2
• Time in Patent Office: Days
• CPC Class Codes: C08L 67/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds C08L67/06 takes precedence
• CPC Class Codes: G02B 1/04 made of organic materials, e.g. plastics G02B1/08 takes precedence
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02F 1/133502 Antiglare, refractive index matching layers
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 2201/501 Blocking layers, e.g. against migration of ions
• CPC Class Codes: H10K 50/86 Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: H10K 59/8791 Arrangements for improving contrast, e.g. preventing reflection of ambient light

Abstract

Disclosed are a protective film for a polarizer with superior optical and mechanical properties, a polarizing plate including the same and a display device including the same.

Claims

1. A protective film for a polarizer, which

comprises polyethylene terephthalate (PET),

satisfies the in-plane phase difference and phase difference in the thickness direction conditions of (1) and (2) at a wavelength of 550 nm:

(1) in-plane phase difference (R_o)≦

350 nm

(2) 16,000 nm≧

phase difference in thickness direction (R_th)≧

6,000 nm,

experiences change in the in-plane phase difference with respect to the width change within the effective width (|Δ

R_o|/|Δ

x|) of less than 5 nm/cm, and

experiences variation in the in-plane phase difference within the effective width (R_o,max−

R_o,min) of 250 nm/m or less.

2. The protective film for a polarizer according to claim 1, which has an in-plane phase difference (R_o) at the width center of 200 nm or less.

3. The protective film for a polarizer according to claim 1, which has an in-plane phase difference (R_o) within ±

500 mm from the width center along the width direction of 250 nm or less.

4. The protective film for a polarizer according to claim 1, which has an in-plane phase difference (R_o) within ±

1000 mm from the width center along the width direction of 300 nm or less.

5. The protective film for a polarizer according to claim 1, which has a ratio (R_th/R_o) of the phase difference in the thickness direction (R_th) with respect to the in-plane phase difference (R_o) at the width center of 60 or larger and 1,600 or smaller.

6. The protective film for a polarizer according to claim 1, which has a stretching ratio in the length direction (MD) of 2.8-3.5 times and a stretching ratio in the width direction (TD) of 2.9-3.7 times.

7. The protective film for a polarizer according to claim 1, which has a ratio (MD/TD) of a stretching ratio in the length direction (MD) with respect to a stretching ratio in the width direction (TD) of 0.9-1.1.

8. The protective film for a polarizer according to claim 1, which has a thickness of 20-60 μ

m.

9. The protective film for a polarizer according to claim 1, which is stretched in the length direction and the width direction and then heat-treated at 160-230°

C.

10. A polarizing plate which comprises a polarizer and the protective film for a polarizer according to claim 1, which is adjacent to at least one of the upper side and the lower side of the polarizer.

11. A display device which comprises a display panel and the polarizing plate according to claim 10 which is disposed on at least one of the upper side and the lower side of the display panel.