Processing method of base material sheet, manufacturing method of modified base material sheet, base material with grafted polymer chain, and ion exchange membrane

1. A base material with grafted polymer chain,

wherein a width is 0.8 m or more, a length is 1 m or more, and a thickness falls within a range from 30 μm to 200 μm,

wherein a maximum value of a graft polymerization rate is 115% of an average value of the graft polymerization rate or less, and

wherein a minimum value of the graft polymerization rate is 85% of the average value of the graft polymerization rate or more,

wherein the graft polymerization rate is calculated by the following formula:

Graft polymerization rate (%)=(W2-W1)/W1× 100

where W1 is a weight of the base material sheet before the graft polymerization within a square area having a size of 100 mm (vertical)×100 mm (horizontal), viewed in a direction orthogonal to a main surface of the base material sheet, and W2 is a weight of the base material sheet after the graft polymerization within the square area having the size of 100 mm (vertical)×100 mm (horizontal), viewed in a direction orthogonal to the main surface of the base material sheet,

and wherein the maximum value, minimum value, and average value of the graft polymerization rate are calculated by the following process:

the graft polymerization rate is measured at five points that are arranged at an equal interval in a width direction of the base material sheet

one point of the five points is arranged at a position separated from one end in the width direction of the base material sheet by 0.05 m, and the other point is arranged at a position separated from the other end in the width direction of the base material sheet by 0.05 m;

the three remaining points are arranged between the two end points, wherein the five points are arranged at an equal interval in the width direction of the base material sheet;

measurement points of the five points are arranged, in the case where the length of the base material sheet is 10 m or more, at an interval of 10 m in the longitudinal direction of the base material sheet; and

from the measured value obtained at the arranged measurement points, the average value, the maximum value and the minimum value are calculated.

2. An ion exchange membrane including a base material with grafted polymer chain,

wherein a width is 0.8 m or more, a length is 1 m or more, and a thickness falls within a range from 30 μm to 200 μm,

wherein a maximum value of an ion exchange capacity is 115% of an average value of the ion exchange capacity or less, and

wherein a minimum value of the ion exchange capacity is 85% of the average value of the ion exchange capacity or more,

wherein the ion exchange capacity is obtained by the following process (i) or (ii):

(i) in a case of a cationic exchange membrane:

an operation of immersing an obtained square-shaped sample of 50 mm sides approximately 200 mL of 2 normal aqueous solution of hydrochloric acid is repeated a few times, to replace an ion exchange group of the sample by a strongly acidic H + type;

an operation of immersing the sample into 500 mL of pure water is repeated to remove excessive hydrochloric acid inside the sample;

the sample is placed into a beaker, and approximately 100 mL of 5% aqueous solution of sodium chloride is placed into the beaker;

after an immersion for one hour, the ion exchange group of the sample is returned to a neutral Na + type;

the operation is repeated until the aqueous solution of sodium chloride becomes neutral, and the aqueous solution of sodium chloride used in the operation is collected;

for the collected liquid, a neutralization titration is performed with aqueous solution of sodium hydroxide of known concentration,

an obtained titration amount is denoted as V mL;

the immersed sample is extracted, repeatedly washed with pure water to remove sodium chloride in the sample, and dried at 80° C. for two hours;

a dry weight is measured and denoted as W (g);

and the ion exchange capacity (mmol/dry weight g) is obtained by the following formula:

Ion exchange capacity (dry weight g)=V×C/W,

wherein

V is an obtained titration amount (mL),

C is a concentration of the aqueous solution of sodium hydroxide (mol/L), and

W is a weight that is measured (dry weight g),

and wherein the maximum value, minimum value, and average value of the ion exchange capacity are calculated by the following process:

the ion exchange capacity is measured at five points that are arranged at an equal interval in a width direction of the base material sheet

one point of the five points is arranged at one end portion in the width direction of the base material sheet, and the other point is arranged at the other end portion in the width direction of the base material sheet

measurement points of the five points are arranged, in the case where the length of the base material sheet is 1 m or more, at an interval of 0.5 m in the longitudinal direction of the base material sheet and

from the measured value obtained at the arranged measurement points, the average value, the maximum value and the minimum value are calculated, wherein a measurement area at each measurement point is a square area having the size of 50 mm (vertical)×50 mm (horizontal), viewed in a direction orthogonal to a main surface of the base material sheet or

(ii) in a case of an anionic exchange membrane:

an operation of immersing an obtained square-shaped sample of 50 mm sides into approximately 200 mL of 1 normal aqueous solution of sodium hydroxide is repeated a few times, to replace an ion exchange group of the sample by a strongly basic OH − type;

an operation of immersing the sample into 500 mL of pure water is repeated, to remove excessive sodium hydroxide inside the sample;

the sample is placed into a, and approximately 100 mL of 5% aqueous solution of sodium chloride is placed into the beaker;

after an immersion for one hour, the ion exchange group of the sample is returned to a neutral Cl − type;

the operation is repeated until the aqueous solution of sodium chloride becomes neutral, and the aqueous solution of sodium chloride used in the operation is collected;

for the collected liquid, a neutralization titration is performed with aqueous solution of hydrochloric acid of known concentration;

an obtained titration amount is denoted as V mL;

the immersed sample is extracted, repeatedly washed with pure water to remove sodium chloride in the sample, and dried at 80° C. for two hours;

a dry weight is measured and denoted as W (g); and

the ion exchange capacity (mmol/dry weight g) is obtained by the following formula:

Ion exchange capacity (dry weight g)=V×C/W,

wherein

V is an obtained titration amount (mL),

C is a concentration of the aqueous solution of hydrochloric acid (mol/L), and

W is a weight that is measured (dry weight g),

and wherein the maximum value, minimum value, and average value of the ion exchange capacity are calculated by the following process:

the ion exchange capacity is measured at five points that are arranged at an equal interval in a width direction of the base material sheet;

one point of the five points is arranged at one end portion in the width direction of the base material sheet, and the other point is arranged at the other end portion in the width direction of the base material sheet;

measurement points of the five points are arranged, in the case where the length of the base material sheet is 1 m or more, at an interval of 0.5 m in the longitudinal direction of the base material sheet and

from the measured value obtained at the arranged measurement points, the average value, the maximum value and the minimum value are calculated, wherein a measurement area at each measurement point is a square area having the size of 50 mm (vertical)×50 mm (horizontal), viewed in a direction orthogonal to a main surface of the base material sheet.