GOLF BALL
An object of the present invention is to provide a golf ball excellent in resilience performance. The present invention provides a golf ball comprising a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) a compound represented by a formula (1) as a co-crosslinking agent and (c) a crosslinking initiator. (R 1 OCO)M(COOR 2 ) m (1) [In the formula (1), M represents a metal atom, R 1 and R 2 represent an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 30 carbon atoms, and m represents 1 or 2.]
1 . A golf ball comprising a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, and (b) the co-crosslinking agent contains a compound represented by a formula (1):
(R 1 OCO)M(COOR 2 ) m (1)
in the formula (1), M represents a metal atom, and m represents 1 or 2; when m is 1, R 1 and R 2 are different from each other and represent an alkenyl group having 2 to 30 carbon atoms or an alkynyl group having 2 to 30 carbon atoms; when m is 2, R 1 represents an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 30 carbon atoms, and two of R 2 are identical to or different from each other and represent an alkenyl group having 2 to 30 carbon atoms or an alkynyl group having 2 to 30 carbon atoms; and when m is 2, a compound in which R 1 and two of R 2 are all identical to each other is excluded.
2 . The golf ball according to claim 1 , wherein in the compound represented by the formula (1), the metal atom (M) is at least one metal atom selected from the group consisting of zinc, calcium, magnesium and aluminum.
3 . The golf ball according to claim 1 , wherein in the compound represented by the formula (1), R 2 is an alkenyl group having 2 to 30 carbon atoms and a carbon-carbon double bond at a carbon atom bonding to the carbonyl group of the compound represented by the formula (1).
4 . The golf ball according to claim 1 , wherein in the compound represented by the formula (1), R 1 is an alkenyl group having 2 to 30 carbon atoms and no carbon-carbon double bond at a carbon atom bonding to the carbonyl group of the compound represented by the formula (1).
5 . The golf ball according to claim 1 , wherein in the compound represented by the formula (1), R 1 has more carbon atoms than R 2 .
6 . The golf ball according to claim 1 , wherein the compound represented by the formula (1) is a compound represented by a formula (2):
in the formula (2), M 1 represents a metal atom, R 11 , R 12 and R 13 are identical to or different from each other and represent a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, R 14 represents an alkylene group having 1 to 28 carbon atoms, and R 15 represents a hydrogen atom or an alkyl group having 1 to 27 carbon atoms.
7 . The golf ball according to claim 6 , wherein M 1 is at least one member selected from the group consisting of beryllium, magnesium, calcium, zinc, barium, cadmium, lead and aluminum.
8 . The golf ball according to claim 6 , wherein R 11 to R 13 are a hydrogen atom; or R 11 and R 12 are a hydrogen atom and R 13 is a methyl group.
9 . The golf ball according to claim 1 , wherein the compound represented by the formula (1) is a compound represented by a formula (3):
in the formula (3), M 2 represents a metal atom, R 21 , R 22 and R 23 are identical to or different from each other and represent a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, R 24 represents an alkylene group having 1 to 28 carbon atoms, R 25 represents a hydrogen atom or an alkyl group having 1 to 27 carbon atoms, R 26 represents an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, an alkyl group having 1 to 30 carbon atoms, or an aryl group having 6 to 30 carbon atoms.
10 . The golf ball according to claim 9 , wherein M 2 is at least one member selected from the group consisting of beryllium, magnesium, calcium, zinc, barium, cadmium, lead and aluminum.
11 . The golf ball according to claim 9 , wherein R 21 to R 23 are a hydrogen atom; or R 21 and R 22 are a hydrogen atom and R 23 is a methyl group.
12 . The golf ball according to claim 1 , wherein (b) the co-crosslinking agent further contains another co-crosslinking agent than the compound represented by the formula (1).
13 . The golf ball according to claim 12 , wherein the other co-crosslinking agent is an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof.
14 . The golf ball according to claim 12 , wherein (b) the co-crosslinking agent contains the compound represented by the formula (1) in an amount of ranging from 3 mass % to 40 mass %.
15 . The golf ball according to claim 1 , wherein the rubber composition contains (b) the co-crosslinking agent in an amount of ranging from 10 parts by mass to 50 parts by mass with respect to 100 parts by mass of (a) the base rubber.
16 . The golf ball according to claim 1 , wherein the rubber composition further contains (d) a metal compound, (e) an organic sulfur compound, and/or (f) a carboxylic acid and/or a salt thereof.