Optical film

• US 6,881,453 B2
• Filed: 04/23/2001
• Issued: 04/19/2005
• Est. Priority Date: 04/25/2000
• Status: Expired due to Fees

• Current Assignee: Teijin Limited
• Original Assignee: Bayer AG, Teijin Limited
• Inventors: Sasaki, Takeshi, Hashidzume, Kiyonari, Iwata, Kaoru, Yamaura, Michio, Kido, Nobuaki, Uchiyama, Akihiko, Kushida, Takashi, Matsumura, Shunichi
• Primary Examiner(s): Pyon, Harold
• Assistant Examiner(s): HON, SOW FUN
• Application Number:
  US10/257,758
• Publication Number:
  US 20030138654A1
• Time in Patent Office: 1,457 Days
• Field of Search: 428/1.1, 428/1.3, 428/1.31, 428/64.2, 428/64.3, 428/65.3, 428/65.5, 349/117, 525/332.8, 525/332.9, 525/333.3
• US Class Current: 428/1.1
• CPC Class Codes: C08J 2325/02 Homopolymers or copolymers of hydrocarbons
• 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 2323/03 Viewing 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 428/31504 Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31931 Polyene monomer-containing
• CPC Class Codes: Y10T 428/31938 Polymer of monoethylenically unsaturated hydrocarbon

Abstract

A film which is a single polymer film and has a smaller phase difference as the wavelength becomes shorter. This film is made from an olefin-based polymer which has an alicyclic group in the side chain, such as hydrogenated polystyrene, the amount of the alicyclic group in the side chain being 60 to 90 wt % based on the whole polymer, and satisfies the following expression:
R(450)/R(550)<1
wherein R(450) and R(550) are phase differences on the film plane at a wavelength of 450 nm and a wavelength of 550 nm, respectively.

Claims

1. A film which comprises a polymer having such a structure that the main chain thereof consists of a hydrocarbon skeleton and some of the hydrogen atoms of the hydrocarbon skeleton are substituted by at least one alicyclic group selected from the group consisting of an alicyclic hydrocarbon group having a 4 or more membered ring and an alicyclic heterocyclic group, the amount of the alicyclic group being 60 to 90 wt %, and which satisfies the following formula (A):

R(450)/R(550)<

1 

 

(A)

wherein R(450) and R(5

     50) are phase differences on the film plane at a wavelength of 450 nm and a wavelength of 550 nm, respectively;

wherein the polymer consists of a recurring unit represented by the following formula (1);

wherein R¹, R², R³ and R⁴ are the same or different and each being a hydrogen atom, aliphatic group having 1 to 10 carbon atoms or alicyclic group having a 4 or more membered ring, with the proviso that at least one of R¹, R², R³ and R⁴ is an alicyclic group having a 4 or more membered ring; and

optionally a recurring unit represented by the following formula (2);

wherein R⁵, R⁶, R⁷ and R⁸ are the same or different and each a hydrogen atom, aliphatic group having 1 to 10 carbon atoms or aromatic group having 6 to 12 carbon atoms.

2. The film of claim 1, wherein 8 to 50 mol % of all the hydrogen atoms of the hydrocarbon skeleton of the main chain of the polymer are substituted by an alicyclic group.

3. The film of claim 1, wherein the alicyclic group has a 4- to 7-membered ring.

4. The film of claim 1, wherein the polymer is a copolymer consisting of a recurring unit represented by the following formula (1):

wherein R¹, R², R³ and R⁴ are the same or different and each a hydrogen atom, aliphatic group having 1 to 10 carbon atoms or alicyclic group having a 4 or more membered ring, with the proviso that at least one of R¹, R², R³ and R⁴ is an alicyclic group having a 4 or more membered ring,

and a recurring unit represented by the following formula (2);

wherein R⁵, R⁶, R⁷ and R⁸ are the same or different and each a hydrogen atom, aliphatic group having 1 to 10 carbon atoms or aromatic group having 6 to 12 carbon atoms.

5. The film of claim 1, wherein the polymer is a polymer consisting of a recurring unit represented by formula (1):

wherein R¹, R², R³ and R⁴ are the same or different and each a hydrogen atom, aliphatic group having 1 to 10 carbon atoms or alicyclic group having a 4 or more membered ring, with the proviso that at least one of R¹, R², R³ and R⁴ is an alicyclic group having a 4 or more membered ring.

6. The film of claim 1 or 4, wherein the polymer is a hydrogenated product of a block copolymer consisting of a (styrene polymer) block and a (polyconjugated diene) block.

7. The film of claim 1 or 5, wherein the polymer is a hydrogenated product of a styrene polymer.

8. The film of claim 1 which has a light transmission of 85% or more.

9. The film of claim 1 which has an elongation at 25°

C. of 1 to 50%.

10. The film of claim 1 which has a thickness of 3 to 300 μ

m.

11. The film of claim 1 which is a phase difference film.

12. The film of claim 11 which is a λ

/4 film.

13. The film of claim 11 which is a λ

/2 film.

14. The film of claim 1 which is a phase difference film for liquid crystal display devices.

15. The film of claim 1 which is a cover layer for information recording media.

16. The film of claim 11 which has a phase difference of 50 nm or more.

17. The film of claim 15 which has a phase difference of 30 nm or less.

18. The film of claim 15 which satisfies the following expression (B):

K(450)/K(550)<

1 

 

(B)

wherein K(450) and K(550) are K values at a wavelength of 450 nm and a wavelength of 550 nm, respectively, the K values being represented by the following expression;

K=(nz−

(nx+ny)/2)×

d

wherein nx is a refractive index in a mechanical axis direction on the film plane, ny is a refractive index in a direction perpendicular to the mechanical axis direction on the film plane and nz is a refractive index in a direction normal to the film plane, and d is a film thickness (nm).

19. The film of claim 15 which has an elongation of 1% or more and a shrinkage factor of more than 1% in at least one direction.