An object of the present invention is to provide an environmentally safe golf ball having excellent resilience. The present invention provides a golf ball having constituting members, wherein at least a part of the constituting members is formed from a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent, (c) a crosslinking initiator, and (d) an organic sulfur compound, wherein the organic sulfur compound includes a disubstituted compound of thiophenol, disulfide and/or thiophenol metal salt with Br, F or CF 3 only at ortho positions.
1. A golf ball having constituting members, wherein at least a part of the constituting members is formed from a rubber composition containing:
(a) a base rubber haying a molecular weight distribution Mw/Mn of from 2.0 to 3.4,
(b) a co-crosslinking agent,
(c) a crosslinking initiator, and
(d) at least one organic sulfur compound selected from the group consisting of organic sulfur compounds represented by the following formulae (1) to (4):
wherein R 1 and R 2 each independently represents Br or F,
wherein R 3 to R 6 each independently represents Br or F,
wherein R 7 and R 8 each independently represents Br or F, and M 1 represents a monovalent metal atom,
wherein R 9 to R 12 each independently represents Br or F, and M 2 represents a bivalent metal atom.
2. The golf ball according to claim 1 , wherein the rubber composition contains (d) the organic sulfur compound in an amount from 0.05 part to 3 parts by mass with respect to 100 parts by mass of (a) the base rubber.
3. The golf bail according, to claim 1 , wherein a blending ratio of (d) the organic sulfur compound to (c) the crosslinking initiator ((d)/(c), mass ratio) ranges from 0.01 to 1.0.
4. The golf ball according to claim 1 , wherein the organic sulfur compound represented by the above formulae (1) to (4) has a substituent constant from 0.1 to 1.2 as a sum of substituent constants of the substituents in at least one of the structures represented by the following formula (5):
wherein R 13 and R 14 represent R 1 to R 12 .
5. The golf ball according to claim 1 , wherein (d) the organic sulfur compound contains at least one organic sulfur compound selected from the group consisting of 2,6-dibromothiophenol, 2,6-difluorothiophenol, bis(2,6-dibromophenyl)disulfide, bis(2,6-difluorophenyl)disulfide, 2,6-dibromothiophenol sodium salt, 2,6-difluorothiophenol sodium salt, and 2,6-dibromothiophenol zinc salt, and 2,6-difluorothiophenol zinc salt.
6. A golf ball comprising a core and a cover covering the core, wherein at least a part of the core is formed from a rubber composition containing:
(a) a base rubber having a molecular weight distribution Mw/Mn of from 2.0 to 3.4,
(b) a co-crosslinking agent,
(c) a crosslinking initiator, and
(d) at least one organic sulfur compound selected from the group consisting of organic sulfur compounds represented by the following formulae (1) to (4):
wherein R 1 and R 2 each independently represents Br or F,
wherein R 3 to R 6 each independently represents Br or F,
wherein R 7 and R 8 each independently represents Br or F, and M 1 represents a monovalent metal atom,
wherein R 9 to R 12 each independently represents Br or F, and M 2 represents a bivalent metal atom.
7. The golf ball according to claim 6 , wherein the rubber composition contains (d) the organic sulfur compound in an amount from 0.05 part to 3 parts by mass with respect to 100 parts by mass of (a) the base rubber.
8. The golf ball according to claim 6 , wherein a blending ratio of (d) the organic, sulfur compound to (c) the crosslinking initiator ((d) (c), mass ratio) ranges from 0.01 to 1.0.
9. The golf ball according to claim 6 , wherein the organic sulfur compound represented by the above formulae (1) to (4) has a substituent constant from 0.1 to 1.2 as a sum of substituent constants of the substituents in at least one of the structures represented by the following formula (5):
wherein R 13 and R 14 represent R 1 to R 12 .
10. The golf ball according to claim 6 , wherein (d) the organic sulfur compound contains at least one organic sulfur compound selected from the group consisting of 2,6-dibromothiophenol, 2,6-difluorothiophenol, bis(2,6-dibromophenyl)disulfide, bis(2,6-difluorophenyl)disulfide, 2,6-dibromothiophenol sodium salt, 2,6-difluorothiophenol sodium salt, 2,6-dibromothiophenol zinc salt, and 2,6-difluorothiophenol zinc salt.
11. The golf ball according to claim 6 , wherein the core has a diameter from 32.8 mm to 40.8 mm, and has a compression deformation amount from 2.0 mm to 6.0 mm when applying a load from 98 N as an initial load to 1275 N as a final load to the core.