Patent ID: 8834296
Filing Date: 2014-09-16
Classification: A63B

Abstract:
1. A multi-piece solid golf ball comprising a solid core encased by a cover of two or more layers, which solid core has an inner core layer and an outer core layer, and cover has an inner cover layer and an outer cover layer, wherein the inner core layer is formed primarily of a thermoplastic resin, has a diameter of from 21 to 38 mm, has a JIS-C cross-sectional hardness of from 60 to 83 at any single point on a cross-section obtained by cutting the inner core layer in half, and has a cross-sectional hardness difference between any two points on the cross-section of within ±5; the outer core layer is formed of a rubber composition made primarily of polybutadiene rubber; the core of the inner core layer and the outer core layer combined has a diameter of from 35 to 42 mm; and, letting (b) represent the JIS-C cross-sectional hardness of the inner core layer 1 mm inside a boundary between the inner core layer and the outer core layer, (c) represent the JIS-C cross-sectional hardness of the outer core layer 1 mm outside the boundary, and (d) represent the JIS-C surface hardness of the outer core layer, the value (c)−(b) is in a range of from −15 to 10 and the value (d)−(b) is in a range of from −10 to 20, and the inner cover layer has a thickness of from 0.8 mm to 3.0 mm and a Shore D hardness of from 10 to 60, and the outer cover layer has a thickness of from 0.7 mm to 3.0 mm and a Shore D hardness of from 45 to 70, which is harder than the Shore D hardness of the inner cover layer.