Sumitomo Rubber Industries Limited

Toshiyuki Takubo

Takahiro Sajima

Hironori Takihara

A golf ball includes a core and a cover positioned outside the core. An n-layer (n is a natural number) partial mid layer is provided between the core and the cover. An area of the core in a region where the cover is laminated thereon is not less than 5.0% and not greater than 95.0% of a surface area of a phantom sphere having a radius equal to an average value of a distance from a central point of the core to a surface of the core. In an outer surface of the golf ball, a color difference &#x394;E1 based on a CIELAB color system between a region C where the cover is directly laminated on the core and a region M where the cover is laminated on the partial mid layer is not less than 20.0.

Golf ball

A golf ball includes a core, a mid layer, and a cover. An amount of compressive deformation Cof the golf ball can be not less than 2.80 mm. The golf ball can satisfy the following mathematical formulas (1) and (2):1&#x3e;(124.8&#x2212;)/11.5&#x2003;&#x2003;(1)2&#x2212;1&#x2265;(&#x2212;1/6*1+(68&#x2212;2)/20+(5&#x2212;)/100)*2&#x2003;&#x2003;(2), where Cis an amount of compressive deformation (mm) of the core, Cis an amount of compressive deformation (mm) of a sphere including the core and the mid layer, Hd is Hs&#x2212;Ho, Ho is a hardness (Shore C) of a center the core, Hs is a hardness (Shore C) of a surface of the core, His a hardness (Shore D) of the mid layer, and Tis a thickness (mm) of the mid layer.

A golf ball can include a core, a mid layer, and a cover. The golf ball can satisfy the following mathematical formulas (1), (2), and (3):1&#x2264;(124.8&#x2212;)/11.5&#x2003;&#x2003;(1)2&#x2212;1&#x2265;(&#x2212;1/6*1+(68&#x2212;2)/20+(5&#x2212;)/100)*2&#x2003;&#x2003; (2)10&#x2264;2*2&#x2212;3*3&#x2003;&#x2003;(3), where

A golf ball according to an aspect of the present invention is a golf ball having a large number of dimples, a surface of the golf ball is covered with a plurality of virtual flat surfaces each having a triangular shape, one or more dimples are arranged so as to correspond to each of the virtual flat surfaces, and an edge of each dimple is formed in a linear shape. Each dimple may have a triangular pyramid shape or a triangular frustum shape.

A golf ball includes a core and a cover. An n-layer (n is a natural number) partial mid layer is provided between the core and the cover. An area of the core in a region where the cover is laminated thereon is not less than 5.0% and not greater than 95.0% of a surface area of a phantom sphere. A hitting feel index Cx calculated using a thickness T(mm) of the cover laminated on the partial mid layer, a Shore D hardness Cof a kth layer (k is an integer from 1 to n) from the core side, a thickness T(mm) of the kth layer, a Shore D hardness C of the cover, and an average thickness T (mm) of the cover, is less than 66.0. An absolute value |Cx&#x2212;C| is not less than 1.0 and not greater than 5.0.

A golf ball has a plurality of dimplesand a landon a surface thereof. The golf ball further has a large number of minute projectionsformed on surfaces of the dimplesand the land. The surface of the golf ball has an arithmetic average height Sa of not less than 0.5 &#x3bc;m and not greater than 30 &#x3bc;m. An average value Hav of heights H of the minute projectionsis not less than 0.5 &#x3bc;m and not greater than 50 &#x3bc;m. A ratio Pp of a sum of areas of all the minute projectionsto a surface area of a phantom sphere of the golf ball is not less than 7%. An average value Dav of diameters D of the minute projectionsis not less than 5 &#x3bc;m and not greater than 50 &#x3bc;m.

A golf ball has a plurality of minute projectionson a surface thereof. An average value Hav of heights H of these minute projectionsis not less than 0.5 &#x3bc;m and not greater than 50 &#x3bc;m. The surface of the golf ball has one or more first zones and one or more second zones. An average value Hav1 of the heights H of the minute projectionson these first zones is higher than an average value Hav2 of the heights H of the minute projectionson these second zones. Preferably, the average value Hav1 and the average value Hav2 satisfy the following mathematical formula.3&#x2264;(1&#x2212;2)&#x2264;50

A golf ball has a large number of exposed portionson a surface thereof. An average value Hav of heights H of these exposed portionsis not less than 0.5 &#x3bc;m and not greater than 50 &#x3bc;m. The surface of the golf ball has one or more first zones and one or more second zones. An average value Havof the heights H of the exposed portionson these first zones is higher than an average value Havof the heights H of the exposed portionson these second zones. Preferably, the average value Havand the average value Havsatisfy the following mathematical formula.3&#x2264;(Hav&#x2212;Hav)&#x2264;50

A golf ball has a plurality of dimplesand a landon a surface thereof. The golf ball further has a large number of minute projectionsformed on surfaces of the dimplesand the land. The minute projectionsare exposed on the surface of the golf ball. The surface of the golf ball has an arithmetic average height Sa of not less than 0.5 &#x3bc;m and not greater than 30 &#x3bc;m. The surface of the golf ball has a maximum height Sz of not less than 5 &#x3bc;m and not greater than 200 &#x3bc;m.

A golf ballincludes a coreand a coverpositioned outside the core. The coveris molded in a mold having support pins by injection molding. A ratio (K/S) of a surface hardness K of the coreto an amount of compressive deformation S of the coresatisfies the following mathematical formula.13.0&#x2264;&#x2264;24.0The coverhas a hardness H of not greater than 62. A product (&#x3b1;*V) of a latitude &#x3b1; of each support pin and a volume V of the coveris not less than 300.

A golf ball has a main bodyand a paint layerpositioned outside the main body. The main bodyhas a plurality of minute projectionson a surface thereof. The paint layerhas a thickness Tp of not less than 5 &#x3bc;m and not greater than 30 &#x3bc;m. Each minute projectionis embedded in the paint layer. An average value Hav of heights H of the minute projectionsis not less than 0.5 &#x3bc;m and not greater than 80% of the thickness Tp. A ratio Pp of a sum of areas of all the minute projectionsto a surface area of a phantom sphere of the golf ball is not less than 7%. An average value Dav of diameters D of the minute projectionsis not less than 5 &#x3bc;m and not greater than 50 &#x3bc;m.

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Kobe, Japan

Toshiyuki Takubo