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Optical element and method for manufacturing the same

a technology of optical elements and manufacturing methods, applied in the field of optical elements, can solve the problems of inability to utilize coating solutions including such solvents, the refractive index anisotropic layer can be easily peeled off from the alignment film, and the mesh-like wrinkles in the refractive index anisotropic layer are generated, so as to achieve excellent adhesion between the alignment property providing layer and the refractive index anisotropic layer, and the adhesion with respect to the alignmen

Inactive Publication Date: 2008-08-21
TAZAKI KEIKO +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an optical element using a liquid crystal layer made from a liquid crystalline composition including a polymerizable liquid crystal material, and a refractive index anisotropic layer with excellent adhesion and durability. The refractive index anisotropic layer has a curing degree that changes monotonously with a predetermined gradient in its thickness direction. The invention also provides a method for manufacturing the optical element by coating a liquid crystalline composition onto an alignment property providing layer and curing it. The technical effects of the invention include improved adhesion between the alignment property providing layer and the refractive index anisotropic layer, and improved durability of each layer.

Problems solved by technology

As to the latter problem, for example, if the adhesion between the alignment film and the refractive index anisotropic layer constituting the optical element is poor, there is a problem that the refractive index anisotropic layer can be easily peeled off from the alignment film.
Moreover, if the optical element is used or stored in a high temperature and high humidity environment, there is a problem that mesh like wrinkles are generated in the refractive index anisotropic layer.
However, among the conventional methods mentioned above, in the method mentioned in JP-A No. 9-152509, since the boiling point of the solvent, used for the modification reaction of the polyvinyl alcohol, is high, the coating solution including such solvent cannot be utilized.
Therefore, a refining process of reprecipitation of the polyvinyl alcohol is indispensable, and thus, there is a problem that the manufacturing cost is increased.
Moreover, in the method disclosed in JP-A No. 10-10320, when the liquid crystal compound is used as the material for the refractive index anisotropic layer, there is a problem that the liquid crystal molecules are not aligned preferably on the anchor coating layer.
Thus, there is a problem that the optical characteristics are deteriorated (for example, the display unevenness generation).

Method used

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  • Optical element and method for manufacturing the same
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  • Optical element and method for manufacturing the same

Examples

Experimental program
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Effect test

example 1

[0070]First, by adding a cyclohexanone (98 parts by weight) to an alignment film composition, including a polymer having a cinnamoyl group (2.0 parts by weight), and dissolving, a solution of an alignment film composition was obtained. Then, after coating this solution onto a triacetyl cellulose (TAC) film (thickness 80 μm), as the transparent base material, by a wire bar coater, it was dried for 2 minutes with hot air of 80° C. Thus, a 0.1 μm thickness coated film was obtained. By irradiating a polarized ultraviolet ray to the coated film by 10 mJ / cm2, an alignment film with the alignment limiting force exhibited on the surface was formed.

[0071]Next, a solution of a liquid crystalline composition was obtained by: dissolving a liquid crystalline composition, including a polymerizable nematic liquid crystal compound represented by the above-mentioned chemical formula (I), into a toluene solution by a 20% by mass ratio; and furthermore, adding a polymerization initiator (IRGACURE 907 ...

example 2

[0072]First, according to the same method as in the above-mentioned example 1, an alignment film was formed on a triacetyl cellulose (TAC) film as the transparent base material.

[0073]Next, a solution of a liquid crystalline composition was obtained by: dissolving a liquid crystalline composition, including a polymerizable nematic liquid crystal compound represented by the above-mentioned chemical formula (I), into a toluene solution by a 20% by mass ratio; and furthermore, adding a polymerization initiator (IRGACURE 907 (product name), manufactured by Chiba Speciality Chemicals). Then, by coating this solution onto the alignment film, produced in the above-mentioned process, by a wire bar coater and drying, a 1 μm thickness coated film was obtained. Next, by heating the coated film at 85° C. for 2 minutes, the liquid crystal molecules in the coated film were aligned by the alignment limiting force exhibited on the surface of the alignment film. Thereafter, a 100 mJ ultraviolet ray w...

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Abstract

The present invention provides an optical element capable of improving the adhesion between the alignment property providing layer, for providing the alignment property to the refractive index anisotropic layer, and the refractive index anisotropic layer, as well as improving durability of each layer.An optical element 10 comprises an alignment property providing layer 12 laminated on the transparent base material 11, and a refractive index anisotropic layer 13 laminated on the alignment property providing layer 12. The alignment property providing layer 12 is an alignment film which provides the alignment property to the refractive index anisotropic layer 13. And the alignment property providing layer 12 is made from an alignment film composition capable of exhibiting the alignment limiting force by the photo-alignment method. The refractive index anisotropic layer 13 comprises a liquid crystal layer formed by curing (polymerizing) a liquid crystalline composition including a polymerizable liquid crystal material. In the refractive index anisotropic layer 13, the curing degree of the refractive index anisotropic layer 13 changes monotonously with a predetermined gradient in its thickness direction such that, within the refractive index anisotropic layer 13, the curing degree of the portion closer to the alignment property providing layer 12 is larger, compared with the curing degree of the portion farther from the alignment property providing layer 12. It is preferable that the average curing degree of the refractive index anisotropic layer 13 is 90% or more.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an optical element such as a retardation plate, a polarizing plate, and a color filter for a display. In particular, the invention relates to an optical element comprising a liquid crystal layer, made from a liquid crystalline composition including a polymerizable liquid crystal material, as a refractive index anisotropic layer, and a method for manufacturing the same. In this specification, the term “liquid crystal layer” is used for the meaning of a layer optically having the property of a liquid crystal, and those having a solid phase state solidified while maintaining the molecular arrangement of the liquid crystal phase are also included as the layer state.[0003]2. Description of the Related Art[0004]In general, the liquid crystal is used as a display medium such as a display element, represented by the TN (twisted nematic) type and the STN (super twisted nematic) type, utilizing th...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B32B37/14
CPCC09K19/2007C09K19/322C09K2019/0448Y10T428/1005G02B5/3016Y10T428/10Y10T428/1009C09K2219/03C09K2323/00C09K2323/02C09K2323/021G02B5/30
Inventor TAZAKI, KEIKONAKAMURA, RUNA
Owner TAZAKI KEIKO