Cation exchange membrane, electrolysis vessel using the same and method for producing cation exchange membrane

1. A cation exchange membrane at least comprising:

a membrane body containing a fluorine-based polymer having an ion-exchange group; and

two or more reinforcing core materials arranged approximately in parallel within the membrane body,

wherein the membrane body is provided with two or more elution holes formed between the reinforcing core materials adjacent to each other, and

assuming that a distance between the reinforcing core materials adjacent to each other is represented by a, a distance between the reinforcing core materials and the elution holes adjacent to each other is represented by b, a distance between the elution holes adjacent to each other is represented by c, and the number of the elution holes formed between the reinforcing core materials adjacent to each other is represented by n, then a, b, c, and n satisfying the relationship represented by the following expression (1) or expression (2) are at least present

b>a /( n+ 1), and n= 2  (1)

c>a /( n+ 1), and n= 2  (2);

in the case where a, b, and n satisfy the relationship represented by expression (1), a, c and n further satisfy the relationship represented by the following expression (3)

0.2 a /( n+ 1)≦ c≦ 0.9 a /( n+ 1)  (3); or

in the case where a, c, and n satisfy the relationship represented by expression (2), a, c, and n further satisfy the relationship represented by the following expression (5)

1.1 a /( n+ 1)≦ c≦ 0.8 a   (5).

2. The cation exchange membrane according to claim 1 , wherein a, b, and n further satisfy the relationship represented by the following expression (4)

a/ ( n+ 1)< b≦ 1.8 a/ ( n+ 1)  (4).

3. The cation exchange membrane according to claim 1 , wherein

a first interval between the reinforcing core materials in which a, b, c, and n satisfy the relationship represented by the expression (1), and

a second interval between the reinforcing core materials in which a, b, c, and n satisfy the relationship represented by the expression (2) are alternately present.

4. The cation exchange membrane according to claim 3 , wherein

in the first interval between the reinforcing core materials, a, b, c, and n further satisfy the relationships represented by the following expression (3) and the following expression (4), and

in the second interval between the reinforcing core materials, a, b, c, and n further satisfy the relationship represented by the following expression (5)

0.2 a/ ( n+ 1)≦ c≦ 0.9 a/ ( n+ 1)  (3)

a/ ( n+ 1)< b≦ 1.8 a/ ( n+ 1)  (4)

1.1 a/ ( n+ 1)≦ c≦ 0.8 a   (5).

5. The cation exchange membrane according to claim 3 , wherein the first interval between the reinforcing core materials satisfying the relationship represented by the following expression (6) and the second interval between the reinforcing core materials satisfying the relationship represented by the following expression (7) are alternately present

n= 2 , b>a/ 3  (6)

n= 2 , c>a/ 3  (7).

6. The cation exchange membrane according to claim 3 , wherein the first interval between the reinforcing core materials satisfying the relationship represented by the following expression (8) and the second interval between the reinforcing core materials satisfying the relationship represented by the following expression (9) are alternately present

n= 2, 0.2 a/ 3 ≦c≦ 0.9 a/ 3, a/ 3 <b≦ 1.8 a/ 3  (8)

n= 2, 1.1 a/ 3 ≦c≦ 0.8 a   (9).

7. The cation exchange membrane according to claim 1 , wherein a, b, c, and n satisfying the relationship represented by the above expression (1) or the above expression (2) are at least present in a MD direction and in a TD direction of the cation exchange membrane.

8. The cation exchange membrane according to claim 4 , wherein the first interval between the reinforcing core materials satisfying the relationships represented by the expression (3) and the expression (4) or the second interval between the reinforcing core materials satisfying the relationship represented by the expression (5) is present in the MD direction and in the TD direction of the cation exchange membrane.

9. An electrolysis vessel at least comprising: an anode; a cathode; and the cation exchange membrane according to claim 1 arranged between the anode and the cathode.

10. The cation exchange membrane according to claim 1 , wherein a, b, and n further satisfy the relationship represented by the following expression (4)

a/ ( n+ 1)< b≦ 1.8 a/ ( n+ 1)  (4).

11. The cation exchange membrane according to claim 1 , wherein

a first interval between the reinforcing core materials in which a, b, c, and n satisfy the relationship represented by the expression (1), and

a second interval between the reinforcing core materials in which a, b, c, and n satisfy the relationship represented by the expression (2) are alternately present.

12. The cation exchange membrane according to claim 11 , wherein

in the first interval between the reinforcing core materials, a, b, c, and n further satisfy the relationships represented by the following expression (3) and the following expression (4), and

in the second interval between the reinforcing core materials, a, b, c, and n further satisfy the relationship represented by the following expression (5)

0.2 a/ ( n+ 1)≦ c≦ 0.9 a/ ( n+ 1)  (3)

a/ ( n+ 1)< b≦ 1.8 a/ ( n+ 1)  (4)

1.1 a/ ( n+ 1)≦ c≦ 0.8 a   (5).

13. The cation exchange membrane according to claim 11 , wherein the first interval between the reinforcing core materials satisfying the relationship represented by the following expression (6) and the second interval between the reinforcing core materials satisfying the relationship represented by the following expression (7) are alternately present

n= 2 , b>a/ 3  (6)

n= 2 , c>a/ 3  (7).

14. The cation exchange membrane according to claim 11 , wherein the first interval between the reinforcing core materials satisfying the relationship represented by the following expression (8) and the second interval between the reinforcing core materials satisfying the relationship represented by the following expression (9) are alternately present

n= 2, 0.2 a/ 3 ≦c≦ 0.9 a/ 3 , a/ 3 <b≦ 1.8 a/ 3  (8)

n= 2, 1.1 a/ 3 ≦c≦ 0.8 a   (9).

15. The cation exchange membrane according to claim 12 , wherein the first interval between the reinforcing core materials satisfying the relationships represented by the expression (3) and the expression (4) or the second interval between the reinforcing core materials satisfying the relationship represented by the expression (5) is present in the MD direction and in the TD direction of the cation exchange membrane.