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Double-refraction optical film, elliptic polarizing piece using same and liquid crystal display using said polarizing piece

A liquid crystal display, optical film technology, applied in optics, optical elements, polarizing elements, etc., can solve the problems of small photoelastic coefficient, difficult to provide and so on

Inactive Publication Date: 2009-01-21
NITTO DENKO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] That is, it is difficult for any conventional technology to provide a high degree of orientation (in order to obtain the desired retardation value) and a small photoelastic coefficient (in order to withstand the heat and / or moisture application during the durability test). Irregularities that reduce contrast) birefringent film

Method used

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  • Double-refraction optical film, elliptic polarizing piece using same and liquid crystal display using said polarizing piece
  • Double-refraction optical film, elliptic polarizing piece using same and liquid crystal display using said polarizing piece
  • Double-refraction optical film, elliptic polarizing piece using same and liquid crystal display using said polarizing piece

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preparation example Construction

[0031] There is no particular limitation on the production method of the birefringent optical film of the present invention. For example, it can be produced by coating the polymer material of the present invention on a base film or the like. At this point, the polymer material can be heated to melt. Alternatively, it is possible to dissolve in a solvent to obtain a polymer solution, and then apply the solution. From the viewpoints of production efficiency and control of optical anisotropy, it is preferable to coat a polymer solution. When a polymer solution is used, it is preferable, for example, to contain 5 to 50 parts by weight, more preferably 10 to 40 parts by weight, of the polymer material per 100 parts by weight of the solvent, from the viewpoint of its viscosity and the like.

[0032] In a method of coating a polymer solution on a base film or the like, the base film can be used as the polymer layer of the present invention. For example, a polymer layer is formed b...

Embodiment 1

[0138] Polyimide is dissolved in ethyl acetate to make a 15% by weight solution. The Mw of the polyimide is 133,000, which is composed of 2,2-bis(3,4-dicarboxylic acid phenyl)hexa Synthesized by fluoropropane dianhydride (6FDA) and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (PFMB or TFMB). This solution was coated on a 120 μm thick thermoplastic polymer base film (trade name: Acryplen, manufactured by Mitsubishi Rayon Co. Ltd), followed by drying at 70° C., thereby obtaining a laminated birefringent optical film having nx = ny > nz optical anisotropy. During the test, the photoelastic coefficient of the polymer base film was -3×10 -8 cm 2 / N, and the photoelastic coefficient of the 6FDA-PFMB layer (thickness d=7μm) is 98×10 -8 cm 2 / N. Therefore, the birefringent optical film thus produced has a calculated value of Σ(Cn×Wn) of 2.6×10 -8 cm 2 / N, the measured value of the photoelastic coefficient of the same optical film is 5×10 -8 cm 2 / N. In the 6FDA-PFMB layer,...

Embodiment 2

[0140] The polyimide solution of Example 1 was coated on a 120 μm thick thermoplastic polymer base film (trade name: Acryplen, manufactured by Mitsubishi Rayon Co. Ltd), followed by 6% uniaxial stretching in the longitudinal direction, while at 100 °C, thereby obtaining a laminated birefringent optical film having an optical anisotropy of nx>ny>nz. During the test, the photoelastic coefficient of the polymer base film was -3×10 -8 cm 2 / N, the thickness is 119 μm. The photoelastic coefficient of the 6FDA-PFMB layer is 98×10 -8 cm 2 / N, the thickness is 5.7 μm. Therefore, the birefringent optical film thus produced has a calculated value of Σ(Cn×Wn) of 1.6×10 -8 cm 2 / N, the measured value of the photoelastic coefficient of the same optical film is 3×10 -8 cm 2 / N. In the 6FDA-PFMB layer, Δnd was 53nm, Rth was 245nm, and Δnxz was 0.043.

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Abstract

The present invention provides a birefringent optical film having a high orientation for easily obtaining a desired retardation value and also a small photoelastic coefficient. The birefringent optical film includes at least two kinds of polymer materials. A total of products of Cn and Wn satisfies a numerical formula (1): Sigma(CnxWn)<=20X10<-8 >cm<2> / N (1) where Cn and Wn denote respectively a photoelastic coefficient and a volume fraction of each polymer material, and at least one of the polymer materials of the film has a photoelastic coefficient value of at least 60x10<-8 >cm<2> / N, while at least one of the remaining polymer materials has a negative value of photoelastic coefficient.

Description

technical field [0001] The present invention relates to a birefringent optical film, an elliptically polarizing plate using the optical film, and a liquid crystal display using the elliptically polarizing plate with the birefringent film. Background technique [0002] Generally, birefringent films for optical compensation are prepared by film stretching technology, and such birefringent films are used in various liquid crystal displays. For stretching, for example, JP3(1991)-33719A discloses roll tension stretching, roll pressure stretching, and tenter uniaxial stretching. JP3(1991)-24502A discloses that biaxial stretching is performed under anisotropic producing conditions. Regarding other methods of producing birefringent films, for example, JP8(1996)-511812A discloses a method of processing soluble polyimide into a film to obtain negative uniaxiality. [0003] By adopting the above or other film stretching techniques, the film can be endowed with optical properties such...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G02F1/13363G02F1/1335G02B5/30
CPCG02F1/13363G02B5/3083C09K2323/03C09K2323/00
Inventor 西小路祐一村上奈穗藤田时男吉见裕之
Owner NITTO DENKO CORP
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