Iodine-type polarizer, polarizing plate and method for producing thereof

Abstract

There is provided a method for producing a polarizer having improved cross transmittance. The method for producing a polarizer includes: dyeing a polyvinyl alcohol (PVA)-based film with molecular iodine by immersing the PVA- based film in an aqueous iodine solution (a dyeing step); absorbing the molecular iodine into the PVA- based film using an aqueous boric acid solution (a cross-linking step); arranging the molecular iodine in the certain direction by stretching the PVA-based film in a certain direction (an stretching step); and drying, in an oven, the PVA-based film in which the molecular iodine is oriented; wherein a phosphate compound is added to the iodine aqueous solution(the dyeing step) or the aqueous boric acid solution(the stretching step) so that a weight ratio of the boric acid: the phosphate compound is in a range of 1:0.1 to 1:10.

Description

technical field [0001] The present invention relates to a method for preparing an iodine-type polarizer and a polarizing plate, more particularly, to a polarizer and a polarizing plate with improved crosstransmittance capable of achieving high brightness and high contrast and its Preparation. Background technique [0002] A polarizer is a device that generates polarized light from natural light, where polarized light has a vibration plane in a specific direction and natural light has a vibration plane in all directions. Polarizers can be classified into iodine-type polarizers, dye-type polarizers, metal-type polarizers, polyvinylidene-type polarizers, infrared polarizers, and the like. Among them, the metal-type polarizer is still to be studied, while the iodine-type polarizer film and the dye-type polarizer film are practically used and commercially available. [0003] The iodine type is produced by dyeing a polyvinyl alcohol (PVA)-based film with dichroic iodine or a dic...

AI Technical Summary

Problems solved by technology

In this case, the contrast, represented by the ratio of white to black luminance, is reduced because black luminance values ​​increase over a higher range than white luminance values

[0006] Therefore, when the brightness of the white point increases, it is difficult to achieve a clear color image due to the decrease in the contrast ratio of the screen due to the increase in brightness

[0007] Meanwhile, a method of increasing the amount of dye used to dye PVA film is used in the art to improve the contrast, but there is a problem in this method that the brightness of the white field decreases due to the increase of the amount of the dye, so that the entire screen becomes dark.

[0008] As described above, the conventional method has a disadvantage in that it is difficult to display a high-quality image with high luminance and high contrast because the luminance and contrast cannot be simultaneously improved.

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