Patent ID: 6632148
Filing Date: 2003-10-14
Classification: A63B

Abstract:
A golf ball comprising a solid core, an intermediate layer, and a cover in a surface of which a plurality of dimples are formed,wherein said solid core has a center JIS-C hardness in a range of 50 to 70 and a surface JIS-C hardness in a range of 60 to 80, and has a diameter in a range of 35 to 40 mm, said intermediate layer is made from a material containing an ionomer resin as a main component, and has a JIS-C hardness in a range of 70 to 85 and a thickness in a range of 0.5 to 2 mm, said cover is made from a material containing an ionomer resin as a main component, and has a JIS-C hardness in a range of 85 or more and a thickness in a range of 0.5 to 2 mm, a difference in JIS-C hardness between said intermediate layer and the surface of said solid core (|intermediate layer hardnessâˆ’solid core surface hardness|) is in a range of 15 or less, a difference in JIS-C hardness between said cover and said intermediate layer (|cover hardnessâˆ’intermediate layer hardness|) is in a range of 10 or more, the hardnesses of said solid core, said intermediate layer, and said cover satisfy a relationship of (hardness gradient from intermediate layer to cover)/(hardness gradient from core center to intermediate layer)&gE;6, said dimples are arranged in such a manner that there is no great circle line not crossing any one of said dimples; wherein a dimple volume occupying ratio VR (%) is in a range of 0.60 to 1.00%, said dimple volume occupying ratio being defined as a ratio of a total of dimple space volumes under plane surfaces surrounded by edge portions of said dimples to a volume of a virtual ball being the same as said golf ball except that said virtual ball has no dimples, and a dimple surface occupying ratio SR (%) is in a range of 70 to 85%, said dimple surface occupying ratio being defined as a ratio of a total of areas occupied by dimple forming portions to a surface area of said virtual ball.