Golf club grip and golf club

1. A golf club grip comprising a polar rubber layer and a nonpolar rubber layer,

wherein the polar rubber layer is formed from a rubber composition containing a base rubber including a polar rubber in an amount of 50 mass % or more,

the nonpolar rubber layer is formed from a rubber composition containing a base rubber including a nonpolar rubber in an amount of 50 mass % or more,

the polar rubber layer and the nonpolar rubber layer are laminated via an interlayer formed from an interlayer composition containing an olefin rubber,

wherein the polar rubber has a solubility parameter value (SP value) (Pa 1/2 (25° C.)) of 8.7 or more and 10.5 or less, and wherein the solubility parameter value is calculated according to a following mathematical formula (1):

SP value=(Δ E/V ) 1/2 =(ΣΔ ei/ΣΔvi ) 1/2   (1)

in the formula (1), ΔE represents vaporization energy, V represents mole volume, Δei represents vaporization energy of an atom or an atomic group, and Δvi represents mole volume of an atom or an atomic group.

2. The golf club grip according to claim 1 , wherein the olefin rubber is a modified olefin rubber including a modified polyethylene in an amount ranging from 5 mass % to 15 mass %.

3. The golf club grip according to claim 1 , wherein the interlayer composition contains 4,4′-diphenylmethane diisocyanate.

4. The golf club grip according to claim 1 , wherein the polar rubber includes at least one diene rubber selected from the group consisting of an acrylonitrile-butadiene rubber (NBR), a carboxyl-modified acrylonitrile-butadiene rubber (XNBR), a hydrogenated acrylonitrile-butadiene rubber (HNBR), and a hydrogenated carboxyl-modified acrylonitrile-butadiene rubber (HXNBR).

5. The golf club grip according to claim 1 , wherein the nonpolar rubber has a solubility parameter value (SP value) (Pa 1/2 (25° C.)) of 7.7 or more and less than 8.7, and wherein the solubility parameter value is calculated according to a following mathematical formula (1):

SP value=(Δ E/V ) 1/2 =(ΣΔ ei/ΣΔvi ) 1/2   (1)

in the formula (1), ΔE represents vaporization energy, V represents mole volume, Δei represents vaporization energy of an atom or an atomic group, and Δvi represents mole volume of an atom or an atomic group.

6. The golf club grip according to claim 1 , wherein the rubber component of the interlayer composition contains the olefin rubber in an amount of 50 mass % or more.

7. The golf club grip according to claim 2 , wherein the modified polyethylene is at least one selected from the group consisting of a chlorosulfonated polyethylene (CSM), a maleic acid modified ethylene-propylene rubber (M-EPM), and a chlorinated polyethylene rubber (CM).

8. The golf club grip according to claim 3 , wherein the interlayer composition contains 4,4′-diphenylmethane diisocyanate in an amount of more than 0 mass % and 6 mass % or less.

9. The golf club grip according to claim 1 , wherein the polar rubber layer is disposed as an outer layer, and the nonpolar rubber layer is disposed as an inner layer, and the interlayer is interposed between the outer layer and the inner layer.

10. A golf club comprising a shaft, a head provided on one end of the shaft, and a grip provided on another end of the shaft,

wherein the grip is a golf club grip comprising a polar rubber layer and a nonpolar rubber layer, and

wherein the polar rubber layer is formed from a rubber composition containing a base rubber including a polar rubber in an amount of 50 mass % or more,

the nonpolar rubber layer is formed from a rubber composition containing a base rubber including a nonpolar rubber in an amount of 50 mass % or more,

the polar rubber layer and the nonpolar rubber layer are laminated via an interlayer formed from an interlayer composition containing an olefin rubber,

wherein the polar rubber has a solubility parameter value (SP value) (Pa 1/2 (25° C.)) of 8.7 or more and 10.5 or less, and wherein the solubility parameter value is calculated according to a following mathematical formula (1):

SP value=(Δ E/V ) 1/2 =(ΣΔ ei/ΣΔvi ) 1/2   (1)

in the formula (1), ΔE represents vaporization energy, V represents mole volume, Δei represents vaporization energy of an atom or an atomic group, and Δvi represents mole volume of an atom or an atomic group.

11. The golf club according to claim 10 , wherein the olefin rubber is a modified olefin rubber including a modified polyethylene in an amount ranging from 5 mass % to 15 mass %.

12. The golf club according to claim 10 , wherein the interlayer composition contains 4,4′-diphenylmethane diisocyanate.

13. The golf club according to claim 10 , wherein the polar rubber includes at least one diene rubber selected from the group consisting of an acrylonitrile-butadiene rubber (NBR), a carboxyl-modified acrylonitrile-butadiene rubber (XNBR), a hydrogenated acrylonitrile-butadiene rubber (HNBR), and a hydrogenated carboxyl-modified acrylonitrile-butadiene rubber (HXNBR).

14. The golf club according to claim 10 , wherein the nonpolar rubber has a solubility parameter value (SP value) (Pa 1/2 (25° C.)) of 7.7 or more and less than 8.7, and wherein the solubility parameter value is calculated according to a following mathematical formula (1):

SP value=(Δ E/V ) 1/2 =(ΣΔ ei/ΣΔvi ) 1/2   (1)

in the formula (1), ΔE represents vaporization energy, V represents mole volume, Δei represents vaporization energy of an atom or an atomic group, and Δvi represents mole volume of an atom or an atomic group.

15. The golf club according to claim 10 , wherein the rubber component of the interlayer composition contains the olefin rubber in an amount of 50 mass % or more.

16. The golf club according to claim 11 , wherein the modified polyethylene is at least one selected from the group consisting of a chlorosulfonated polyethylene (CSM), a maleic acid modified ethylene-propylene rubber (M-EPM), and a chlorinated polyethylene rubber (CM).

17. The golf club according to claim 12 , wherein the interlayer composition contains 4,4′-diphenylmethane diisocyanate in an amount of more than 0 mass % and 6 mass % or less.

18. The golf club according to claim 10 , wherein the polar rubber layer is disposed as an outer layer, and the nonpolar rubber layer is disposed as an inner layer, and the interlayer is interposed between the inner layer and the outer layer.

19. A golf club grip comprising a polar rubber layer and a nonpolar rubber layer,

wherein the polar rubber layer is formed from a rubber composition containing a base rubber including a polar rubber in an amount of 50 mass % or more,

the nonpolar rubber layer is formed from a rubber composition containing a base rubber including a nonpolar rubber in an amount of 50 mass % or more,

the polar rubber layer and the nonpolar rubber layer are laminated via an interlayer formed from an interlayer composition containing an olefin rubber,

wherein the nonpolar rubber has a solubility parameter value (SP value) (Pa 1/2 (25° C.)) of 7.7 or more and less than 8.7, and wherein the solubility parameter value is calculated according to a following mathematical formula (1):

SP value=(Δ E/V ) 1/2 =(ΣΔ ei/ΣΔvi ) 1/2   (1)

in the formula (1), ΔE represents vaporization energy, V represents mole volume, Δei represents vaporization energy of an atom or an atomic group, and Δvi represents mole volume of an atom or an atomic group.

20. The golf club grip according to claim 19 , wherein the olefin rubber is a modified olefin rubber including a modified polyethylene in an amount ranging from 5 mass % to 15 mass %, and

wherein the modified polyethylene is at least one selected from the group consisting of a chlorosulfonated polyethylene (CSM), a maleic acid modified ethylene-propylene rubber (M-EPM), and a chlorinated polyethylene rubber (CM).

21. The golf club grip according to claim 19 , wherein the interlayer composition contains 4,4′-diphenylmethane diisocyanate in an amount of more than 0 mass % and 6 mass % or less.

22. A golf club comprising a shaft, a head provided on one end of the shaft, and a grip provided on another end of the shaft,

wherein the grip is a golf club grip comprising a polar rubber layer and a nonpolar rubber layer, and

wherein the polar rubber layer is formed from a rubber composition containing a base rubber including a polar rubber in an amount of 50 mass % or more,

the nonpolar rubber layer is formed from a rubber composition containing a base rubber including a nonpolar rubber in an amount of 50 mass % or more,

the polar rubber layer and the nonpolar rubber layer are laminated via an interlayer formed from an interlayer composition containing an olefin rubber, and

wherein the nonpolar rubber has a solubility parameter value (SP value) (Pa 1/2 (25° C.)) of 7.7 or more and less than 8.7, and wherein the solubility parameter value is calculated according to a following mathematical formula (1):

SP value=(Δ E/V ) 1/2 =(ΣΔ ei/ΣΔvi ) 1/2   (1)

in the formula (1), ΔE represents vaporization energy, V represents mole volume, Δei represents vaporization energy of an atom or an atomic group, and Δvi represents mole volume of an atom or an atomic group.

23. The golf club according to claim 22 , wherein the olefin rubber is a modified olefin rubber including a modified polyethylene in an amount ranging from 5 mass % to 15 mass %, and

wherein the modified polyethylene is at least one selected from the group consisting of a chlorosulfonated polyethylene (CSM), a maleic acid modified ethylene-propylene rubber (M-EPM), and a chlorinated polyethylene rubber (CM).

24. The golf club according to claim 22 , wherein the interlayer composition contains 4,4′-diphenylmethane diisocyanate in an amount of more than 0 mass % and 6 mass or less.