RETARDATION FILM, AND CIRCULARLY POLARIZING PLATE AND IMAGE DISPLAY DEVICE EACH USING THE SAME

• US 20140268333A1
• Filed: 03/14/2014
• Published: 09/18/2014
• Est. Priority Date: 09/14/2011
• Status: Abandoned Application

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.), Nitto Denko Corporation
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.), Nitto Denko Corporation
• Inventors: TANAKA, Tomohiko, Yokogi, Masashi, Murakami, Nao, IIDA, Toshiyuki
• Application Number:
  US14/211,897
• Publication Number:
  US 20140268333A1
• Time in Patent Office: Days
• US Class Current: 359/489.07
• CPC Class Codes: B29B 11/10 Extrusion moulding
• CPC Class Codes: B29C 35/02 Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mouldcold vulcanisation B29C35/18 ; vulcanising tyres, presses therefor B29D30/0601
• CPC Class Codes: B29C 55/005 characterised by the choice of materials
• CPC Class Codes: B29D 11/00644 polarizing
• CPC Class Codes: B29K 2069/00 Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: C08G 64/1608 saturated
• CPC Class Codes: C08G 64/183 containing polyether sequences
• CPC Class Codes: C08G 64/305 and alcohols
• 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: G02B 1/04 made of organic materials, e.g. plastics G02B1/08 takes precedence
• CPC Class Codes: G02B 1/08 made of polarising materials
• 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: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
• 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

An object of the present invention is to provide a retardation film succeeded in solving those conventional problems, that is, a retardation film insusceptible to color dropout or color shift even under environment of severe temperature or humidity conditions and capable of being produced by a melt film-forming method. The retardation film of the present invention satisfies the relationships of the following formulae (A) and (B):

0.7<R₁(450)/R₁(550)<1  Formula (A):

|R₂(450)/R₂(550)−R₁(450)/R₁(550)|<0.020  Formula (B):

Claims

1. A retardation film, satisfying formulae (A) and (B):

0.7<

R₁(450)/R₁(550)<

1; and

 

 

Formula (A);

|R₂(450)/R₂(550)−

R₁(450)/R₁(550)|<

0.020, 

 

Formula (B);

wherein R₁(450) and R₁(550) represent the retardation value in film plane at respective wavelengths of 450 nm and 550 nm, and R₂(450) and R₂(550) represent a retardation value in film plane at respective wavelengths of 450 nm and 550 nm after leaving the retardation film to stand at a temperature of 90°

C. for 48 hours.

2. The retardation film according to claim 1, satisfying formulae (C) and (D):

1<

R₁(650)/R₁(550)<

1.2; and

 

 

Formula (C);

|R₂(650)/R₂(550)−

R₁(650)/R₁(550)|<

0.010, 

 

Formula (D);

wherein R₁(650) represents a retardation value in film plane at a wavelength of 650 nm, and R₂(650) represents a retardation value in film plane at a wavelength of 650 nm after leaving the retardation film to stand at a temperature of 90°

C. for 48 hours.

3. The retardation film according to claim 1, wherein the retardation film is obtained by a process comprising forming a polymer comprising a structural unit (a) having a positive refractive index anisotropy with an absorption end being less than 260 nm and a structural unit (b) having a negative refractive index anisotropy with an absorption end being from 260 to 380 nm.

4. The retardation film according to claim 3, wherein the polymer is a polycarbonate resin, a polyester carbonate resin or both.

5. The retardation film according to claim 4, wherein:

the structural unit (b) is a structural unit derived from a dihydroxy compound represented by formula (1), and the structural unit (a) is a structural unit derived from a dihydroxy compound represented by the formula (2) and one or more dihydroxy compounds selected from the group consisting of a dihydroxy compound represented by formula (3), a dihydroxy compound represented by formula (4), a dihydroxy compound represented by formula (5) and a dihydroxy compound represented by the formula (6);

6. The retardation film according to claim 5, wherein in the polymer, a content of the structural unit derived from a dihydroxy compound having an acetal structure is 10 mol % or less based on all dihydroxy compound-derived structural units.

7. The retardation film according to claim 5, wherein:

the structural unit (b) is derived from the dihydroxy compound represented by formula (1), and

the structural unit (a) is derived from the dihydroxy compound represented by formula (2) and the dihydroxy compound represented by formula (5).

8. The retardation film according to claim 1, wherein the retardation film is a single-layer film.

9. The retardation film according to claim 3, wherein a photoelastic coefficient of the polymer is 45×

10<sup>−

12</sup> Pa<sup>−

1</sup> or less.

10. The retardation film according to claim 1, wherein a glass transition temperature of the polymer is from 110 to 150°

C.

11. A circularly polarizing plate comprising the retardation film according to claim 1 and a polarizing plate.

12. An image display device, comprising the circularly polarizing plate according to claim 11.

13. The image display device according to claim 12, wherein the image display device uses an organic EL.