Polycarbonate-based oriented film and retardation film

• US 7,223,451 B2
• Filed: 03/28/2003
• Issued: 05/29/2007
• Est. Priority Date: 06/27/2002
• Status: Expired due to Fees

• Current Assignee: Teijin Limited
• Original Assignee: Teijin Limited
• Inventors: Ikeda, Yoshinori, Uchiyama, Akihiko, Ono, Yuhei
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US10/487,765
• Publication Number:
  US 20050163943A1
• Time in Patent Office: 1,523 Days
• Field of Search: 428/1.1, 428/1.2, 428/1.31, 428/412, 349/117, 349/118, 349/123, 528/196, 528/198
• US Class Current: 428/1.1
• CPC Class Codes: B32B 2307/42 Polarizing, birefringent, filtering
• CPC Class Codes: B32B 2307/516 mono-axially
• CPC Class Codes: B32B 2307/518 bi-axially
• CPC Class Codes: B32B 2369/00 Polycarbonates
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/365 comprising polycarbonates
• CPC Class Codes: C08G 64/06 not containing aliphatic unsaturation
• CPC Class Codes: C08J 2369/00 Characterised by the use of polycarbonates; Derivatives of polycarbonates
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: C09K 2323/031 Polarizer or dye
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: Y10T 428/31507 Of polycarbonate

Abstract

A uniaxially or biaxially oriented film which is made from a specific polycarbonate having a fluorene ring and a glass transition temperature of 165° C. or higher and which has a heat shrinkage factor when it is heated at 90° C. for 500 hours of 0.1% or less, and a ratio of retardation R(450) within the film plane at a wavelength of 450 nm to retardation R(550) within the film plane at a wavelength of 550 nm of 1 to 1.06. This film can be used in a high-quality liquid crystal display device such as a vertical alignment liquid crystal display device and is useful as a retardation film which almost solves a frame problem.

Claims

1. A uni- or bi-axially oriented film

(A) which comprises a polymer or polymer mixture containing a recurring unit represented by the following formula (I):

2. The film of claim 1 which is a uniaxially oriented film further satisfying the following expressions (2) and (3) at the same time:

R(550)>

K(550) 

 

(2)

R(550)>

20 nm 

 

(3)

wherein R(550) is as defined in the above expression (1) and K(550) is a value (rim) defined by the following expression (4) at a wavelength of 550 nm;

K=[(n_x+n_y)/2−

n_z]×

d 

 

(4)

wherein n_x, n_y and n_z are refractive indices in x axis, y axis and z axis directions of the film, respectively, and d is the thickness (nm) of the film.

3. The film of claim 1 which is a biaxially oriented film further satisfying the following expression (2′

) and expression (3) at the same time;

R(550)≦

K(550) 

 

(2′

)

R(550)>

20 nm 

 

(3)

wherein R(550) is as defined in the above expression (1) and K(550) is a value (nm) defined by the following expression (4) at a wavelength of 550 nm;

K=[(n_x+n_y)/2−

n_z]×

d 

 

(4)

wherein n_x, n_y and n_z are refractive indices in x axis, y axis and z axis directions of the film, respectively, and d is the thickness (nm) of the film.

4. The film of claim 3 which satisfies the following expression (1′

);

1≦

R(450)/R(550)≦

1.05 

 

(1′

)

wherein R(450) and R(550) are as defined in the above expressions.

5. The film of claim 1 which is a biaxially oriented film further satisfying the following expression (2′

), the following expression (3′

) and the following expression (5) at the same time;

R(550)≦

K(550) 

 

(2′

)

R(550)≦

20 nm 

 

(3′

)

K(550)≧

50 nm 

 

(5)

wherein R(550) is as defined in the above expression (1) and K(550) is a value (nm) defined by the following expression (4) at a wavelength of 550 nm;

K=[(n_x+n_y)/2−

n_z]×

d 

 

(4)

wherein n_x, n_y and n_z are refractive indices in x axis, y axis and z axis directions of the film, respectively, and d is the thickness (nm) of the film.

6. The film of claim 1, wherein the polymer or polymer mixture has a glass transition temperature of 200°

C. or higher.

7. The film of claim 1 which is a retardation film.

8. A laminated polarizer film which comprises the film of any one of claims 1 and 2 to 5 and a polarizer film in a laminated form.

9. The laminated polarizer film of claim 8 which is laminated in such a manner that the transmission axis of the polarizer film becomes parallel to the slow axis within the plane of the film.

10. A liquid crystal display device comprising the laminated polarizer film of claim 8.

11. The liquid crystal display device of claim 10 which is in a vertical alignment mode.