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Polarizing disc

A polarizer and fiber technology, applied in polarizing components, optics, instruments, etc., can solve the problems of TAC film self-corrosion, difficult processing technology, and inability to obtain polarizing properties, etc.

Inactive Publication Date: 2010-02-10
TEIJIN LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In addition, the durability characteristics required for the polarizing plate have also become very high. In the absorption type polarizing plate using iodine, the durability, especially the heat and humidity resistance, is not sufficient, and the life of the liquid crystal display device using it is limited by the polarizing plate. Feature Restrictions
[0006] With regard to improving durability, on page 13 of the April 2005 issue of Display Monthly, a dye-based polarizing plate that uses a dichroic dye as a polarizing element instead of iodine is disclosed. Compared with the polarizer, the polarizer has been improved, but the following problems remain: the protective film of the polarizer, that is, the TAC film shrinks and gives the liquid crystal panel shrinkage stress, which reduces the image quality, and the TAC film itself corrodes, etc.
However, in order to stretch a polarizer made of a PVA film, a stretching process with a stretching ratio of 4 to 8 times is required, and a large-scale device is required as a facility
And in the oblique stretching of the film, since the stretched film has biaxial orientation, the degree of orientation becomes low anyway, so it is not possible to obtain the same polarizing film as that of a polarizing film composed of a longitudinally uniaxially stretched polyvinyl alcohol film. polarizing performance
In addition, the following problems remain: since the TAC film is used as the protective film of the polarizer as the polarizing film, the image quality is reduced due to the shrinkage of the TAC film, and the TAC film itself is corroded.
However, the biaxial retardation film used to realize this characteristic needs to control the birefringence characteristic, that is, Nz. Therefore, there is a problem that the number of materials and the processing process increase as follows: Both sides of the retardation film processed by uniaxial stretching need to be The special and difficult processing technology of adhering a heat-shrinkable film, shrinking the heat-shrinkable film, and stretching the uniaxially stretched film in the thickness direction of the film has a low yield rate, so the productivity is poor, and it is costly. high material, moreover, must be used with polarizer glued
[0013] As mentioned above, in order to improve the viewing angle characteristics of the polarizing plate, the technology of inserting a biaxial retardation film is used, but the difficulty of the process, the number of components, and the increase in the process will lead to the problem of increasing the cost of the components and cannot be realized. Method of Improving Viewing Angle Characteristics Using Polarizer Monomer

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0149] PVA (manufactured by Kuraray Co., Ltd., degree of polymerization: 4,000, degree of saponification: 99.9%) was dissolved in dimethyl sulfoxide (hereinafter, abbreviated as DMSO) as a solvent to prepare a spinning dope with a PVA concentration of 16% by weight. The spinning stock solution was sprayed from a spinneret with a hole diameter of 100 μm and a hole number of 300 at 100° C. into a coagulation bath composed of methanol, and dry-wet spinning was performed with a spinning draw ratio of 2.0 and an air gap of 30 mm, and then , while extracting DMSO with methanol, it was spun and stretched in a methanol bath, and then dried to obtain unstretched PVA filaments (10 μm in diameter). This undrawn yarn was drawn 6.5 times using a heating roll at 110° C. to obtain a PVA fiber (diameter: 2 μm). The PVA fiber was fixed in the longitudinal direction, and immersed for 60 seconds in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.075 / 5 / 100. Then, ...

reference example 1

[0162] A PVA film (Kuraray Co., Ltd., degree of polymerization 2,400, degree of saponification 99.9%, thickness 75 μm) was uniaxially stretched to 5.0 times at a stretching temperature of 110° C. to make a polarizing substrate. This polarizing substrate was kept under tension during stretching, and immersed for 60 seconds in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.075 / 5 / 100. Next, it was immersed for 300 seconds in the 65 degreeC boric-acid-containing aqueous solution whose weight ratio of potassium iodide / boric acid / water was 6 / 7.5 / 100. This was washed with pure water and dried. The film thickness of the thus obtained iodine-impregnated PVA thin film was 20 μm. A TAC film (manufactured by Fujifilm Co., Ltd., Fuji TAC-UV80) was bonded to both surfaces of the dried film using a PVA-based adhesive. The transmittance of the polarizing plate thus obtained was 44.1%, and the degree of polarization was 99.9%. The optical characteristics of ...

Embodiment 2

[0166] PVA (manufactured by Kuraray Co., Ltd., degree of polymerization: 4,000, degree of saponification: 99.9%) was dissolved in dimethyl sulfoxide (hereinafter, abbreviated as DMSO) as a solvent to prepare a spinning dope with a PVA concentration of 16% by weight. The spinning stock solution was sprayed from a spinneret with a hole diameter of 100 μm and a number of holes of 50 at 100°C into a coagulation bath composed of methanol, and dry-wet spinning was performed at a spinning draw ratio of 2.0 and an air gap of 30 mm. , and then, while extracting DMSO with methanol, it was spun and drawn in a methanol bath, and then dried to obtain undrawn PVA filaments (6 μm in diameter). This undrawn yarn was drawn 6.5 times using a heating roll at 110° C. to obtain a PVA fiber (diameter: 2 μm). This PVA fiber was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.075 / 5 / 100 for 60 seconds while maintaining its length so as not to cause shrinkage...

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Abstract

A polarizing plate which comprises: (a) a layer comprising polyvinyl alcohol fibers which have a dichroic dye adsorbed thereon and an aspect ratio of 10 or higher and which are disposed in a planar arrangement so as to be oriented in one direction or a combination of the layer (a) and (b) a layer comprising fibers which have an aspect ratio of 10 or higher and a difference in refractive index between the major-axis direction and the minor-axis direction of 0.05 or larger and have no dichoric dye adsorbed thereon and which are disposed in a planar arrangement so as to be oriented in one direction and / or (b') fibers which have an aspect ratio of 10 or higher and a difference in refractive index between the major-axis direction and the minor-axis direction less than 0.05 and have no dichoricdye adsorbed thereon, these fibers being disposed in a planar arrangement so as to be oriented in one direction; and (c) an optically transparent resin.

Description

technical field [0001] The present invention relates to a polarizing plate (polarizing plate) having a brightness enhancement function, an optical member formed using the polarizing plate, a liquid crystal display device, and the like. Background technique [0002] As a polarizer for liquid crystal display devices, it is usually colored with iodine, and a uniaxially stretched polyvinyl alcohol (hereinafter referred to as PVA) film is used as a polarizer. A cellulose (hereinafter, abbreviated as TAC) film is used as a polarizing plate for the protective film of the polarizing plate, or a polarizing plate is coated with acrylic resin or the like on one side of the polarizer, or is glued on one side of the polarizer instead of TAC. Polarizers of retardation films such as norbornene and polycarbonate, etc. However, the polarizer is classified as an absorbing polarizer, and only the light in the transmission axis direction of the polarizer is transmitted, and the light of the re...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G02B5/30G02F1/1335
Inventor 池田吉纪城尚志
Owner TEIJIN LTD
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