Golf ball 1 has a core 2 and a cover 3. The cover 3 is formed from a polymer composition. A coefficient of loss at −20° C., T(−20), and a complex elastic modulus at −20° C., E(−20) Kgf/cm 2 , of this polymer composition satisfy the following mathematical formula (I): T (−20)≧4.2*10 −5 *E (−20)−0.24 (I). The coefficient of loss T(−20) is equal to or greater than 0.05 and equal to or less than 0.50, and particularly equal to or greater than 0.05 and equal to or less than 0.40. The complex elastic modulus E(−20) is equal to or greater than 500, and particularly equal to or greater than 1000. The thickness of the cover is equal to or greater than 0.3 mm and equal to or less than 1.4 mm, and particularly equal to or greater than 0.3 mm and equal to or less than 1.0 mm.
1. A golf ball comprising a core and a cover,
said cover formed from a polymer composition,
wherein a coefficient of loss of said polymer composition at −20° C., T(−20) , measured by a viscoelasticity spectrometer under a condition of: the dynamic distortion being 5%; the frequency being 10 Hz; the temperature-elevating rate being 4° C./min.; and the deformation mode being tension, and a complex elastic modulus of said polymer composition at −20° C., E(−20) Kgf/cm 2 , measured under the same condition satisfy the following mathematical formula (I):
T (−20)≧4.2*10 −5 *E (−20)−0.24 (I).
2. The golf ball according to claim 1 wherein said coefficient of loss T(−20) and complex elastic modulus E(−20) satisfy the following mathematical formula (II):
T (−20)≧4.2*10 −5 *E (−20)−0.116 (II).
3. The golf ball according to claim 1 wherein said coefficient of loss T(−20) is equal to or greater than 0.05 and equal to or less than 0.50, and said complex elastic modulus E(−20) is equal to or greater than 500.
4. The golf ball according to claim 3 wherein said coefficient of loss T(−20) is equal to or greater than 0.05 and equal to or less than 0.40, and said complex elastic modulus E(−20) is equal to or greater than 1000.
5. The golf ball according to claim 1 wherein the thickness of said cover is equal to or greater than 0.3 mm and equal to or less than 1.4 mm.
6. The golf ball according to claim 5 wherein the thickness of said cover is equal to or greater than 0.3 mm and equal to or less than 1.0 mm.