Golf ball
AssigneeDunlop Sports Co. Ltd.
InventorsKazuhiko ISOGAWA, Kosuke TACHIBANA
Life of this patent
Estimating the term…
Abstract
A golf ball 2 includes a spherical core 4, an inner mid layer 6, an outer mid layer 8, a reinforcing layer 10, and a cover 12. When distances (%) from a central point of the core 4 to nine points and JIS-C hardnesses at the nine points, which nine points are obtained by dividing a region from the central point of the core 4 to a surface of the core 4 at intervals of 12.5% of a radius of the core 4, are plotted in a graph, R2 of a linear approximation curve obtained by a least-square method is equal to or greater than 0.95. Hm1 is greater than Hm2. Hc is less than Hm1. T2 is equal to or greater than 0.5 mm but equal to or less than 1.6 mm.
Claims18
A golf ball comprising a spherical core, an inner mid layer positioned outside the core, an outer mid layer positioned outside the inner mid layer, and a cover positioned outside the outer mid layer, wherein
- if JIS-C hardness values are measured at nine points in the core obtained by dividing the core radius into intervals of 12.5% and including the core center and core surface, and the hardness values are plotted versus distance in a graph, then R2 of a linear approximation curve obtained by a least-square method is equal to or greater than 0.95,
- a Shore D hardness Hm1 of the inner mid layer is greater than a Shore D hardness Hm2 of the outer mid layer,
- a Shore D hardness Hc of the cover is less than the hardness Hm1, and
- a thickness T2 of the outer mid layer is equal to or greater than 0.5 mm but equal to or less than 1.6 mm;
- the core is formed from a crosslinked rubber composition comprising:
- (a) a base rubber;
- (b) a co-crosslinking agent;
- (c) a crosslinking initiator;
- and
- (d) a carboxylic acid and/or a salt thereof wherein the carboxylic acid component of the carboxylic acid has a carbon number that is equal to or greater than one but equal to or less than 14, and
- wherein the co-crosslinking agent (b) is:
- (b1) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms;
- and/or
- (b2) a metal salt of an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms,
- wherein the carboxylic acid is selected from the group consisting of an aromatic carboxylic acid and a fatty acid, and/or the salt thereof is the salt of an aromatic carboxylic acid and does not include the co-crosslinking agent (b), and
- wherein the rubber composition does not include a salt of a fatty acid.
Dependencies are inferred from the claim text.