A golf ball 2 has a core 4 , a cover 6 , and numerous dimples 8 . This cover 6 is composed of a resin composition which includes a thermoplastic styrene elastomer and an ionomer resin as principle components. A melt index of this resin composition at 190° C. is equal to or greater than 4.0 g/10 min. Ratio R1 of the diameter d max of the maximum dimple to the diameter D of the golf ball 2 is 10.5% or greater and 17.0% or less. A ratio R2 of the number of dimples 8 having a diameter d accounting for 10.5% or greater and 17.0% or less of the diameter D of the golf ball 2 , occupied in total number N of the dimples is equal to or greater than 20%. Shore D hardness of the cover 6 is 50 or greater and 63 or less.
1. A golf ball having a core, a cover, and numerous dimples formed on the surface of said cover,
wherein said cover comprises a resin composition which includes a thermoplastic styrene elastomer,
a melt index of said resin composition at 190° C. is equal to or greater than 4.0 g/10min., and
a ratio R 1 of the diameter d max of the maximum dimple to the diameter D of the golf ball is 10.5% or greater and 17.0% or less.
2. The golf ball according to claim 1 wherein a ratio R 2 of the number of dimples having a diameter d accounting for 10.5% or greater and 17.0% or less of said diameter D, with respect to the total number N of the dimples is equal to or greater than 20%.
3. The golf ball according to claim 1 wherein a base polymer of said resin composition comprises a thermoplastic styrene elastomer and an ionomer resin as principle components, and the Shore D hardness of said cover is 50 or greater and 63 or less.
4. The golf ball according to claim 1 wherein the thickness of said cover is 1.0 mm or greater and 1.8 mm or less.
5. The golf ball according to claim 1 wherein a total number N of the dimples is 150 or greater and 360 or less.
6. The golf ball according to claim 2 wherein a total number N of the dimples is 150 or greater and 360 or less.
7. The golf ball according to claim 1 wherein said resin composition of said cover comprises an ionomer resin and a thermoplastic styrene elastomer within a weight ratio range of 60/40 to 95/5.
8. The golf ball according to claim 1 wherein said resin composition of said cover comprises an ionomer resin and a thermoplastic styrene elastomer within a weight ratio range of 80/20 to 90/10.
9. The golf ball according to claim 1 wherein the melt index of said resin composition at 190° C. is equal to or greater than 5.0 g/10 mm. and equal to or less than 20.0 g/10 min.
10. The golf ball according to claim 1 wherein the ratio R 1 is equal to or greater than 12.0% and equal to or less than 16.0%.
11. The golf ball according to claim 1 wherein the ratio R 1 is equal to or greater than 13.0% and equal to or less than 15.0%.
12. The golf ball according to claim 1 wherein a ratio R 2 of the number of dimples having a diameter d accounting for 10.5% or greater and 17.0% or less of said diameter D, with respect to the total number N of the dimples is equal to or greater than 22%.
13. The golf ball according to claim 1 wherein a ratio R 2 of the number of dimples having a diameter d accounting for 10.5% or greater and 17.0% or less of said diameter D, with respect to the total number N of the dimples is equal to or greater than 30%.
14. The golf ball according to claim 1 wherein all of the dimples have a diameter d accounting for equal to or greater than 5.0% of the diameter D of the golf ball.
15. The golf ball according to claim 1 wherein all of the dimples have a diameter d accounting for equal to or greater than 5.8% of the diameter D of the golf ball.