Binder

A binder comprising a polyvinyl alcohol-based polymer, wherein the polyvinyl alcohol-based polymer has an average saponification value of 85.0 mol % to 89.0 mol % as measured according to JIS K6726,

• wherein the polyvinyl alcohol-based polymer is a saponified product of a polymer composed of a vinyl acetate as a polymerization component, and
• wherein the polyvinyl alcohol-based polymer meets the following requirement (A):
• based on data obtained by measurement of the polyvinyl alcohol-based polymer by liquid chromatography, a value represented by Formula (3) shown below is 22 or more,
• wherein the measurement is performed with a liquid chromatography system equipped with a charged aerosol detector and a column comprising the following:
• carbon load:
• 8%, maximum pressure:
• 4500 psi, particle size:
• 3 μm, pore size:
• 300 Å, stationary phase:
• C18, surface area:
• 100 m2/g, length:
• 150 mm, diameter:
• 4.6 mm, pH:
• 2.5 to 7.5, material:
• glass lined tubing, and under the measurement conditions described below,
• wherein the data represent a baseline-normalized intensity over a retention time of 5.0 to 12.0 minutes at a sampling interval of 500 ms, and
• wherein the value represented by Formula (3) is calculated from Formulae (1) and (2) shown below, wherein the intensity at a retention time Ti [min] is represented by Pi [pA];
• Measurement Conditions:
• Concentration of an aqueous polyvinyl alcohol-based polymer solution:
• 0.1% by mass
• Injection volume of the aqueous polyvinyl alcohol-based polymer solution:
• 2 μL
• Column temperature:
• 50° C.
• Flow rate:
• 1.0 mL/min
• Eluent:
• a mixed solvent of water and methanol
• Eluent gradient conditions:
• the ratio of water and methanol in the eluent changes from 95:5 to 15:85 at a constant rate over a run time from minutes 0 to 10;
• and the ratio of water and methanol in the eluent is constant at 15:85 over a run time from minutes 10 to 15;
• Formulae:
• Tn=Σ(Ti×Pi)/Σ(Pi) Formula (1)
• Tw=>(Ti2×Pi)/Σ(Ti×Pi) Formula (2)
• {(Tw/Tn)−1}×1000 Formula (3).