Golf ball resin composition and golf ball

1. A golf ball resin composition containing as a resin component:

(A1) a metal ion-neutralized product of a binary copolymer composed of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and/or (A2) a metal ion-neutralized product of a ternary copolymer composed of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester,

wherein the golf ball resin composition is obtained by blending a copolymer composition with (c) a metal compound;

wherein the copolymer composition contains

at least one selected from the group consisting of (a1-1) a binary copolymer composed of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (a1-2) a metal ion-neutralized product of a binary copolymer composed of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (a2-1) a ternary copolymer composed of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester, and (a2-2) a metal ion-neutralized product of a ternary copolymer composed of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester as a resin component,

(b1) a betaine type amphoteric surfactant, and

at least one selected from the group consisting of (b2) a saturated fatty acid and (b3) an unsaturated fatty acid, and

wherein in a DSC measurement (a measuring atmosphere: a nitrogen atmosphere, a measuring temperature range: from −50° C. to 150° C., and a temperature rising rate: 10° C./min) of the golf ball resin composition, a first endothermic peak and a second endothermic peak appear, and a peak top temperature (Ti) of the first endothermic peak is equal to or lower than a peak top temperature (Tm) of the second endothermic peak and the peak top temperature (Ti) ranges from 60° C. to 70° C.

2. The golf ball resin composition according to claim 1 , wherein a hyperfine coupling constant (A zz ) of the golf ball resin composition ranges from 31.6 G to 35.0 G, measured by a spin probe-electron spin resonance method (spin probe: 5-doxylstearic acid).

3. The golf ball resin composition according to claim 2 , wherein the resin component contains a divalent metal ion as a metal ion, and the hyperfine coupling constant (A zz ) ranges from 31.6 G to 33.5 G.

4. The golf ball resin composition according to claim 2 , wherein the resin component contains a monovalent metal ion as a metal ion, and the hyperfine coupling constant (A zz ) ranges from 32.5 G to 35.0 G.

5. The golf ball resin composition according to claim 1 , wherein a constrained layer of an ion association of the golf ball resin composition has an average thickness ranging from 3.0 Å to 9.0 Å, measured by a temperature variable spin probe-electron spin resonance method.

6. The golf ball resin composition according to claim 1 , wherein a constrained layer of an ion association of the golf ball resin composition has an average thickness ranging from 0.04 nm to 0.50 nm, measured by an X-ray small angle scattering method.

7. The golf ball resin composition according to claim 1 , wherein the golf ball resin composition has a total neutralization degree ranging from 50 mole % to 200 mole %.

8. The golf ball resin composition according to claim 1 , wherein the peak top temperature (Tm) of the second endothermic peak ranges from 60° C. to 85° C.

9. The golf ball resin composition according to claim 1 , wherein the golf ball resin composition has a melt flow rate (190° C., 2.16 kgf) of 1.5 g/10 min or more, and 200 g/10 min or less.

10. A golf ball having a constituent member formed from a golf ball resin composition, wherein the golf ball resin composition contains as a resin component:

(A1) a metal ion-neutralized product of a binary copolymer composed of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and/or (A2) a metal ion-neutralized product of a ternary copolymer composed of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester as a resin component;

wherein the golf ball resin composition is obtained by blending a copolymer composition with (c) a metal compound;

wherein the copolymer composition contains

at least one selected from the group consisting of (a1-1) a binary copolymer composed of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (a1-2) a metal ion-neutralized product of a binary copolymer composed of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (a2-1) a ternary copolymer composed of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester, and (a2-2) a metal ion-neutralized product of a ternary copolymer composed of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester as a resin component,

(b1) a betaine type amphoteric surfactant, and

at least one selected from the group consisting of (b2) a saturated fatty acid and (b3) an unsaturated fatty acid, and

wherein in a DSC measurement (a measuring atmosphere: a nitrogen atmosphere, a measuring temperature range: from −50° C. to 150° C., and a temperature rising rate: 10° C./min) of the golf ball resin composition, a first endothermic peak and a second endothermic peak appear, and a peak top temperature (Ti) of the first endothermic peak is equal to or lower than a peak top temperature (Tm) of the second endothermic peak and the peak top temperature (Ti) ranges from 60° C. to 70° C.

11. The golf ball according to claim 10 , wherein a hyperfine coupling constant (A zz ) of the golf ball resin composition ranges from 31.6 G to 35.0 G, measured by a spin probe-electron spin resonance method (spin probe: 5-doxylstearic acid).

12. The golf ball according to claim 11 , wherein the resin component contains a divalent metal ion as a metal ion, and the hyperfine coupling constant (A zz ) ranges from 31.6 G to 33.5 G.

13. The golf ball according to claim 11 , wherein the resin component contains a monovalent metal ion as a metal ion, and the hyperfine coupling constant (A zz ) ranges from 32.5 G to 35.0 G.

14. The golf ball according to claim 10 , wherein a constrained layer of an ion association of the golf ball resin composition has an average thickness ranging from 3.0 Å to 9.0 Å, measured by a temperature variable spin probe-electron spin resonance method.

15. The golf ball according to claim 10 , wherein a constrained layer of an ion association of the golf ball resin composition has an average thickness ranging from 0.04 nm to 0.50 nm, measured by an X-ray small angle scattering method.

16. The golf ball according to claim 10 , wherein the golf ball resin composition has a total neutralization degree ranging from 50 mole % to 200 mole %.

17. The golf ball according to claim 10 , wherein the golf ball comprises a core, at least one intermediate layer covering the core, and a cover covering the intermediate layer; and wherein at least one layer of the intermediate layer is formed from the golf ball resin composition.

18. The golf ball according to claim 17 , wherein the intermediate layer has a total thickness of 2.5 mm or less.

19. The golf ball according to claim 10 , wherein the peak top temperature (Tm) of the second endothermic peak ranges from 60° C. to 85° C.

20. The golf ball according to claim 10 , wherein the golf ball resin composition has a melt flow rate (190° C., 2.16 kgf) of 1.5 g/10 min or more, and 200 g/10 min or less.