Patent ID: 8672776
Filing Date: 2014-03-18
Classification: A63B

Abstract:
1. A multi-piece solid golf ball comprising a solid core, a cover, at least one intermediate layer situated therebetween, and a plurality of dimples on a surface of the ball, wherein the solid core has a diameter of from 34 to 38.7 mm, a deflection when compressed under a final load of 130 kgf from an initial load of 10 kgf of from 3.5 to 6.0 mm, a Shore D hardness at a center of the core of from 20 to 38, a Shore D hardness in a region 5 mm to 10 mm from the core center of from 23 to 41, a Shore D hardness 15 mm from the core center of from 28 to 46, and a Shore D hardness at a surface of the core of from 37 to 62; the intermediate layer is composed primarily of a material obtained by mixing under applied heat: 100 parts by weight of a resin component of (a) an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random copolymer having a weight-average molecular weight (Mw) of from about 100,000 to about 200,000 and a weight-average molecular weight (Mw) to number-average molecular weight (Mn) ratio of from about 3.0 to about 10, and/or a metal salt thereof, and/or (b) an olefin-unsaturated carboxylic acid random copolymer having a weight-average molecular weight (Mw) of from about 100,000 to about 200,000 and a weight-average molecular weight (Mw) to number-average molecular weight (Mn) ratio in a range of from about 3.0 to about 10, and/or a metal salt thereof, (d) about 55 to about 200 parts by weight of a fatty acid or fatty acid derivative having a molecular weight of from 280 to 1500, and (e) a basic inorganic metal compound; wherein component (e) is a component for neutralizing acid groups in components (a), (b) and (d), and is included in an amount corresponding to from 30 to 130 mol % of the acid groups in components (a), (b) and (d); the intermediate layer material has a Shore D hardness of from 35 to 60 and has a Shore D hardness difference with the surface of the solid core of within ±10; the cover is formed primarily of polyurethane, has a thickness of from 0.5 to 1.5 mm, and has a Shore D hardness of from 53 to 65 which is higher than the intermediate layer hardness, the Shore D hardness difference therebetween being from 6 to 15; the overall ball has a deflection, when compressed under a final load of 130 kgf from an initial load of 10 kgf, of from 2.9 to 5.0 mm.