A center of a golf ball is formed from a composition having a flexural modulus from 150-450 MPa, a maximum loss factor (tan δ) between −20 and 0° C. of 0.08 or less, a rebound resilience of 55% or more, and a slab hardness ranging from 40-60 in Shore D hardness. The center composition includes, as a resin component, 30 to 70 mass % of (A) a modified polyester elastomer having a Shore A hardness of 95 or less; 70-30 mass % of (B) a binary ionomer resin having a Shore D hardness of 65 or more, a flexural modulus of 300 MPa or more, and a melt flow rate (190° C., 2.16 kg) of 1.0 g/10 min or more; and 0-50 mass % of (C) a thermoplastic resin other than (A) and (B) components (provided that a total content of (A), (B), and (C) components is 100 mass %).
1. A golf ball having a center, a cover, and at least one intermediate layer disposed between the center and the cover, wherein the center is formed from a center composition having a flexural modulus ranging from 150 MPa to 450 MPa, a maximum loss factor (tan δ) between −20° C. and 0° C. of 0.08 or less, a rebound resilience of 55% or more, and a slab hardness ranging from 40 to 60 in Shore D hardness, and the center composition comprises, as a resin component,
30 mass % to 70 mass % of (A) a modified polyester elastomer having a Shore A hardness of 95 or less;
70 mass % to 30 mass % of (B) a binary ionomer resin having a Shore D hardness of 65 or more, a flexural modulus of 300 MPa or more, and a melt flow rate (190° C., 2.16 kg) of 1.0 g/10 min or more; and
0 mass % to 50 mass % of (C) a thermoplastic resin other than said (A) component and (B) component (provided that a total content of the (A) component, (B) component, and (C) component is 100 mass %),
wherein (A) the modified polyester elastomer is obtained by a reaction between 0.01 mass % to 30 mass % of (a-3) an unsaturated carboxylic acid or a derivative thereof and 100 mass % of (a-2) a polyester elastomer containing a polyalkylene glycol component in a content ranging from 5 mass % to 90 mass % in a presence of (a-1) a radical generator.
2. The golf ball according to claim 1 , wherein a blending ratio of (a-1) component ranges from 0.001 mass % to 3 mass % with respect to 100 mass % of (a-2) component.
3. The golf ball according to claim 1 , wherein a content of an acid component in (B) the binary ionomer resin is 15 mass % or more.
4. The golf ball according to claim 1 , wherein the center composition comprises, as the resin component, 0.1 mass % to 50 mass % of (C) the thermoplastic resin, and
wherein (C) component is at least one member selected from the group consisting of polyurethane, polyolefin, polyester, polyamide, polystyrene, polycarbonate, polyacetal, modified poly(phenyleneether), polyimide, polysulfone, polyethersulfone, poly(phenylenesulfide), polyarylate, polyamideimide, polyetherimide, polyetheretherketone, polyetherketone, polytetrafluroroethylene, polyaminobismaleimide, polybisamidetriazole, an acrylonitrile-butadiene-styrene copolymer, an acrylonitrile-styrene copolymer, and an acrylonitrile-EPDM-styrene copolymer.
5. The golf ball according to claim 1 , wherein the center composition contains at least one filler selected from the group consisting of gold, tungsten, lead, copper, iron, cast iron, pig iron, zinc, titanium, aluminum, zirconium, aluminum oxide, bismuth oxide, cerium oxide, copper oxide, tin oxide, titanium oxide, yttrium oxide, zinc oxide, silica, barium sulfate, calcium carbonate, talc, montmorillonite, and mica in an amount ranging from 1 part to 40 parts by mass with respect to 100 parts by mass of the resin component.
6. The golf ball according to claim 1 , wherein the center composition has a melt flow rate (230° C., 2.16 kg) in a range from 3 g/10 min to 30 g/10 min.
7. The golf ball according to claim 1 , wherein the center has a diameter of 5.0 mm or more and 40 mm or less.
8. The golf ball according to claim 1 , wherein the center has a density in a range from 0.80 g/cm 3 to 1.5 g/cm 3 .
9. The golf ball according to claim 1 , wherein the intermediate layer directly covering the center is formed from a rubber composition.
10. The golf ball according to claim 1 , wherein the intermediate layer comprises an envelope layer directly covering the center and having a slab in a range from 40 to 90 in JIS-C hardness and at least one intermediate layer covering the envelope layer.
11. The golf ball according to claim 10 , wherein the envelope layer has a thickness in a range from 2.0 mm to 25 mm.
12. The golf ball according to claim 10 , wherein a spherical core consisting of the center and the envelope layer covering the center has a diameter in a range from 7 mm to 41.0 mm.
13. The golf ball according to claim 12 , wherein the spherical core has a surface hardness in a range from 40 to 95 in JIS-C hardness.
14. The golf ball according to claim 10 , wherein the intermediate layer covering the envelope layer has a slab hardness in a range from 40 to 70 in Shore D hardness.
15. The golf ball according to claim 1 , wherein the cover has a thickness in a range from 0.3 mm to 2.5 mm.
16. The golf ball according to claim 1 , wherein the cover has a slab hardness in a range from 20 to 70 in Shore D hardness.