Polyvinyl alcohol-based resin, method for producing polyvinyl alcohol-based resin, dispersant and dispersant for suspension polymerization

A polyvinyl alcohol-based resin, wherein

• an average degree of saponification is 68 mol % to 85 mol %, and
• a ¼ value width of a degree of saponification distribution obtained by high performance liquid chromatogram measured under the following conditions is 7.0 minutes or less,
• (Conditions):
• apparatus:
• liquid chromatography (LC-10AD, manufactured by Shimadzu Corporation), detector:
• corona charged aerosol detector (Corona plus, manufactured by ESA), column:
• particle diameter:
• 5 μm, 4.6 mm (inner diameter)×250 mm (length) (Nucleosil 100-5C18 B column, manufactured by GL Sciences Inc.), mobile phase flow rate:
• 0.5 mL/min, injection amount:
• 50 μL, eluent:
• (solvent A) ultrapure water, (solvent B) tetrahydrofuran, high-pressure gradient:
• solvent A/solvent B (volume ratio)=90/10 (0 minutes), 90/10 (5 minutes), 14/86 (43 minutes), and 14/86 (58 minutes) by a gradient elution method, measurement temperature:
• 50° C., sample:
• 10 vol % tetrahydrofuran aqueous solution (concentration:
• 2 mg/mL), and data acquisition interval:
• every second.