The present invention provides a golf ball having a center and at least one intermediate layer covering the center and a cover, wherein at least one of the intermediate layer is formed from a composition comprising, as a resin component, (A) a polyamide copolymer containing (a-1) a polymerized fatty acid, (a-2) sebacic acid and/or azelaic acid, (a-3) a polyamine component as an essential component, and (B) at least one member selected from (b-1) a binary copolymer composed of an olefin and an α,β-unsaturated carboxylic acid, (b-2) a metal ion-neutralized product of a binary copolymer composed of an olefin and an α,β-unsaturated carboxylic acid, (b-3) a ternary copolymer composed of an olefin, an α,β-unsaturated carboxylic acid and an α,β-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralized product of a ternary copolymer composed of an olefin, an α,β-unsaturated carboxylic acid and an α,β-unsaturated carboxylic acid ester.
1. A golf ball comprising a core consisting of a center and at least one intermediate layer covering the center and a cover covering the core, wherein at least one intermediate layer is formed from an intermediate layer composition comprising, as a resin component,
(A) a polyamide copolymer containing (a-1) a polymerized fatty acid, (a-2) sebacic acid and/or azelaic acid, and (a-3) a polyamine component, and
(B) (b-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, and (b-4) 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 (b-2) the metal ion-neutralized product of the binary copolymer composed of the olefin and the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms is a mixture of a binary ionomer resin neutralized with a sodium ion and a binary ionomer resin neutralized with a zinc ion, and the intermediate layer composition has a melt flow rate (240° C., 2.16 kg) of 35 g/10 min or more.
2. The golf ball according to claim 1 , wherein the intermediate layer composition comprises, as a resin component, (A) component in a content ranging from 10 mass % to 80 mass %, and (B) component in a content ranging from 20 mass % to 90 mass % so that a total content of (A) component and (B) component becomes 100 mass %.
3. The golf ball according to claim 1 , wherein the intermediate layer composition has a flexural modulus ranging from 350 MPa to 1,000 MPa.
4. The golf ball according to claim 1 , wherein the intermediate layer composition has a slab hardness ranging from 66 to 75 in Shore D hardness.
5. The golf ball according to claim 1 , wherein the intermediate layer has a thickness ranging from 0.5 mm to 1.5 mm.
6. The golf ball according to claim 1 , wherein a mass ratio (a-1)/(a-2) of (a-1) component to (a-2) component ranges from 0.25 to 5.2.
7. The golf ball according to claim 1 , wherein (A) the polyamide copolymer has a melt viscosity ranging from 5 Pa·s to 500 Pa·s.
8. The golf ball according to claim 1 , wherein (A) the polyamide copolymer has a melt flow rate (230° C., 2.16 kg) ranging from 10 g/10 min. to 2,000 g/10 min.
9. The golf ball according to claim 1 , wherein (A) the polyamide copolymer has a flexural modulus ranging from 400 MPa to 1,000 MPa.
10. A golf ball comprising a core consisting of a center and at least one intermediate layer covering the center and a cover covering the core, wherein at least one intermediate layer is formed from an intermediate layer composition comprising, as a resin component,
(A) a polyamide copolymer containing (a-1) a polymerized fatty acid, (a-2) sebacic acid and/or azelaic acid, and (a-3) a polyamine component,
(B) (b-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, and (b-4) 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, and
(C) a polyamide resin composition comprising (c-1) a polyamide resin not containing (a-1) the polymerized fatty acid and (c-2) a resin having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an anhydride group, a sulfonic acid group, and an epoxy group,
wherein the intermediate layer composition comprises component (A) in a content ranging from 1 mass % to 70 mass %, component (B) in a content ranging from 15 mass % to 65 mass %, and component (C) in a content ranging from 15 mass % to 60 mass %, with the total content of components (A), (B), and (C) being 100 mass %, and
wherein the intermediate composition has a melt flow rate (240° C., 2.16 kg) of 35 g/10 min or more.
11. The golf ball according to claim 10 , wherein the intermediate layer composition comprises, as (b-2) the metal ion-neutralized product of the binary copolymer composed of the olefin and the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, a mixture of a binary ionomer resin neutralized with a sodium ion and a binary ionomer resin neutralized with a zinc ion.
12. The golf ball according to claim 10 , wherein the intermediate layer composition has a flexural modulus ranging from 350 MPa to 1,000 MPa.
13. The golf ball according to claim 10 , wherein the intermediate layer composition has a slab hardness ranging from 66 to 75 in Shore D hardness.
14. The golf ball according to claim 10 , wherein the intermediate layer has a thickness ranging from 0.5 mm to 1.5 mm.
15. The golf ball according to claim 10 , wherein a mass ratio (a-1)/(a-2) of (a-1) component to (a-2) component ranges from 0.25 to 5.2.
16. The golf ball according to claim 10 , wherein (A) the polyamide copolymer has a melt viscosity ranging from 5 Pa·s to 500 Pa·s.
17. The golf ball according to claim 10 , wherein (A) the polyamide copolymer has a melt flow rate (230° C., 2.16 kg) ranging from 10 g/10 min. to 2,000 g/10 min.
18. The golf ball according to claim 10 , wherein (A) the polyamide copolymer has a flexural modulus ranging from 400 MPa to 1,000 MPa.