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Polyvinyl alcohol-based film, polarizing film, polarizer, and method for producing polyvinyl alcohol-based film

A polyvinyl alcohol-based, manufacturing method technology, applied in polarizing elements, optical elements, flat products, etc., can solve problems such as breakage, and achieve excellent swelling and stretchability, improved performance, and improved swelling and stretchability. Effect

Active Publication Date: 2021-10-26
MITSUBISHI CHEM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this thin polyvinyl alcohol-based film has problems in productivity such as breakage due to stretching during the production of polarizing films.

Method used

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  • Polyvinyl alcohol-based film, polarizing film, polarizer, and method for producing polyvinyl alcohol-based film

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0195] (Production of polyvinyl alcohol-based film)

[0196] Add 1000kg of polyvinyl alcohol-based resin with a weight average molecular weight of 142000 and a degree of saponification of 99.8 mol%, 2500kg of water, 105kg of glycerin as a plasticizer, and 0.25kg of polyoxyethylene laurylamine as a surfactant in a 5000L dissolution tank , the temperature was raised to 150° C. while stirring to dissolve under pressure, and the aqueous solution of polyvinyl alcohol-based resin having a resin concentration of 25% by weight was obtained by adjusting the concentration. Then, after supplying the polyvinyl alcohol-based resin aqueous solution to a twin-screw extruder for defoaming, the temperature of the aqueous solution was set at 95° C., and it was discharged from the discharge port of a T-shaped slot die (discharge speed 1.3 m / min) in parallel. Film formation was carried out by extending to a casting drum having a surface temperature of 80°C. The formed film was peeled from the ca...

Embodiment 2

[0201] In Example 1, after stretching 1.4 times in the width direction (TD) using a stretching machine at 80°C, it was shrunk to a fixed width of 2.4m (equivalent to stretching 1.2 times) at 130°C by relaxing stress, and transported. A polyvinyl alcohol-based film (2.4 m in width, 25 μm in thickness, and 2 km in length) was obtained in the same manner as in Example 1 except for this. The properties of the obtained polyvinyl alcohol-based film are shown in Table 1 below.

[0202] In addition, a polarizing film and a polarizing plate were obtained in the same manner as in Example 1 using the above-mentioned polyvinyl alcohol-based film. In the swelling step during the production of the polarizing film, no creases or wrinkles occurred in the above-mentioned polyvinyl alcohol-based film, and no breakage occurred either. The properties of the obtained polarizing film and polarizing plate are shown in Table 1 below.

Embodiment 3

[0204] In Example 1, the discharge speed during film formation was set to 0.8 m / min, and a film (width 2 m, thickness 20 μm) with a water content of 5% by weight was formed and stretched in the width direction (TD) at 80° C. After being stretched 1.4 times, it was shrunk to a fixed width of 2.4 m (equivalent to stretching 1.2 times) at 130° C. for stress relaxation, except that a polyvinyl alcohol-based film was obtained in the same manner as in Example 1 (width 2.4m, thickness 17μm, length 2km). Table 1 shows the properties of the obtained polyvinyl alcohol-based film.

[0205] In addition, a polarizing film and a polarizing plate were obtained in the same manner as in Example 1 using the above-mentioned polyvinyl alcohol-based film. In the swelling step during the production of the polarizing film, no creases or wrinkles occurred in the above-mentioned polyvinyl alcohol-based film, and no breakage occurred either. The properties of the obtained polarizing film and polarizi...

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Abstract

The present invention provides a polyvinyl alcohol-based film that is excellent in balance between swelling and stretchability during production of a polarizing film, does not break when producing a thin polarizing film, exhibits high polarization performance, and has little color unevenness The invention provides a polarizing film and a polarizer using the polyvinyl alcohol-based film, and a method for producing the polyvinyl alcohol-based film. The polyvinyl alcohol-based film of the present invention is characterized in that it is an elongated polyvinyl alcohol-based film with a thickness of 5 to 60 μm, and the birefringence in the longitudinal direction (MD) of the first surface is Δn MDA , The birefringence index Δn in the longitudinal direction (MD) of the second surface MDB , the birefringence of the central part in the thickness direction Δn MDC , all of the following formulas (A) to (C) are met: 1.0≤Δn MDA / Δn MDB ≤1.5...(A)Δn MDB -Δn MDC ≥0.2×10 ‑3 ...(B)Δn MDA ≥3.0×10 ‑3 ...(C).

Description

technical field [0001] The present invention relates to a polyvinyl alcohol-based film which can be used as a material for forming a polarizing film having excellent dyeability, a high degree of polarization, and less color unevenness, and to a polarizing film and a polarizing film using the polyvinyl alcohol-based film. sheet, and a method for producing the polyvinyl alcohol-based film. Background technique [0002] Conventionally, polyvinyl alcohol-based films have been used in many applications as films excellent in transparency, and one of such useful applications includes polarizing films. The polarizing film is used as a basic structural element of a liquid crystal display, and in recent years, its use has expanded to devices requiring high quality and high reliability. [0003] Under such circumstances, along with the increase in luminance, high definition, large area, and thinning of screens such as liquid crystal televisions and multifunctional mobile terminals, po...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G02B5/30B29C55/08C08J5/18B29K29/00B29L7/00B29L11/00
CPCB29C55/08C08J5/18G02B5/30C08J2329/04
Inventor 清水俊宏北村秀一寺本裕一
Owner MITSUBISHI CHEM CORP
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