Polyvinyl alcohol film, polarizing film and polarizing plate using the same

Abstract

Provided are: a PVA film in which breakage during uniaxial stretching is suppressed even when the maximum stretching speed is high in uniaxial stretching performed in manufacturing of an optical film such as a polarizing film; a polarizing film in which such a PVA film is used; and a polarizing plate.　A polyvinyl alcohol film in which the ratio ((A2)50°C / (A2)30°C) of (A2)50°C to (A2)30°C is 0.20-0.65, where (A2)50°C is the bound amorphous content calculated based on a transition curve obtained in pulse NMR measurement in a 3 mass% boric acid heavy water solution at 50°C, and (A2)30°C is the bound amorphous content calculated based on a transition curve obtained in pulse NMR measurement in a 3 mass% boric acid heavy water solution at 30°C.

Claims

[Claim 1] (A2) The amount of constrained amorphous component is calculated from the relaxation curve obtained by pulsed NMR measurement in a 3% by mass boric acid aqueous solution at 50°C. ５０℃ year, (A2) The amount of constrained amorphous component is calculated from the relaxation curve obtained by pulsed NMR measurement in a 3 mass% boric acid heavy aqueous solution at 30°C. ３０℃ In that case, (A2) ５０℃ (A2) ３０℃ Ratio to ((A2)) ５０℃ / (A2) ３０℃ ) is between 0.20 and 0.65, The above (A2) 50°C is 15 or less, When the amount of crystalline component calculated from the relaxation curve obtained in pulsed NMR measurement in a 3% by mass boric acid aqueous solution at 50°C is defined as (A1) 50°C, The ratio of (A2) 50°C to (A1) 50°C ((A2) 50°C / (A1) 50°C) is between 0.60 and 1.

6. The polyvinyl alcohol contained in the polyvinyl alcohol film has a degree of polymerization of 2,000 or more. It contains a plasticizer, and the plasticizer content is 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of polyvinyl alcohol. The amount of constrained amorphous component and the amount of crystalline component affect the relaxation curve. Formula: y=y0+a1×exp(-0.5×(t / tau1) 2 )+a2×exp(-0.5×(t / tau2) 2 )+a3×exp(-t / tau3) [In the formula, "y" represents the magnetization intensity at time "t", y0 is a constant, a1 is the intensity in the excited state of the crystalline component, a2 is the intensity in the excited state of the constrained amorphous component, a3 is the intensity in the excited state of the amorphous component, tau1 is the relaxation time of the crystalline component, tau2 is the relaxation time of the constrained amorphous component, and tau3 is the relaxation time of the amorphous component.] This is a polyvinyl alcohol film, calculated by fitting it to the specified dimensions. [Claim 2] The polyvinyl alcohol film according to claim 1, wherein the degree of swelling is 170 to 220%. [Claim 3] The polyvinyl alcohol film according to claim 1 or 2, wherein the degree of polymerization of the polyvinyl alcohol contained in the polyvinyl alcohol film is 2,700 or less. [Claim 4] A polyvinyl alcohol film according to any one of claims 1 to 3, which is a raw film roll for manufacturing optical films. [Claim 5] The polyvinyl alcohol film according to claim 4, wherein the optical film is a polarizing film. [Claim 6] A polarizing film manufactured using the polyvinyl alcohol film described in claim 5. [Claim 7] A polarizing plate having a protective film attached to at least one side of the polarizing film according to claim 6.

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