| US 7,501,165 B2 | ||
| Retardation film, novel polymer, optical film, and image display device | ||
| Yutaka Ohmori, Ibaraki (Japan); Michie Sakamoto, Ibaraki (Japan); Shuusaku Nakano, Ibaraki (Japan); Takahisa Konishi, Ibaraki (Japan); and Seiji Umemoto, Ibaraki (Japan) | ||
| Assigned to Nitto Denko Corporation, Osaka (Japan) | ||
| Appl. No. 10/592,729 PCT Filed Jun. 03, 2005, PCT No. PCT/JP2005/010260 § 371(c)(1), (2), (4) Date Sep. 14, 2006, PCT Pub. No. WO2006/011298, PCT Pub. Date Feb. 02, 2006. |
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| Claims priority of application No. 2004-221204 (JP), filed on Jul. 29, 2004; and application No. 2004-266757 (JP), filed on Sep. 14, 2004. | ||
| Prior Publication US 2008/0200621 A1, Aug. 21, 2008 | ||
| Int. Cl. G02F 1/13363 (2006.01); C08G 10/06 (2006.01) | ||
| U.S. Cl. 428—1.3 [525/330.3] | 17 Claims |
1. A retardation film consisting of a single-layer film in which a birefringent chain polymer is oriented, the polymer having
as a side chain (a), a group represented by the following general formula (I), the retardation film having a smaller in-plane
retardation at a shorter wavelength lying within a range of at least 450 to 650 nm, and having a larger in-plane retardation
at a longer wavelength relative to the shorter wavelength lying within a range of at least 450 to 650 nm:
 wherein two oxygen atoms are bonded to atoms constituting a main chain, respectively;
and R1 and R2 each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aromatic group, and
wherein at least either R1 or R2 is an aromatic group, and the aromatic group(s) represented by R1 or/and R2 is (are) arranged in a direction such that the planar structure thereof is substantially orthogonal to a virtual line obtained
by connecting the two oxygen atoms.
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