Abstract: A wound golf ball comprising a liquid center, thread rubber wound thereon, and a cover enclosing the wound center, whereinsaid cover has a multi-layer structure having a total thickness of 1.0 to 4.0 mm and including an outer layer having a first hardness and a thickness of 0.4 to 3.0 mm and an inner layer having a second hardness higher than the first hardness, the outer layer of said cover being formed of a first resin having a Shore D hardness of 40 to 55, and the inner layer is formed of a second resin having a Shore D hardness of 55 to 68, the difference in hardness between the first and second resins being at least 5 in Shore D hardness.

Abstract: A wound golf ball including a liquid center (4) in the form of a rubber bag (2) filled with a liquid (3), a thread rubber layer (5), and a cover (6). The filling liquid of the liquid center is a liquid having water-insoluble powder dispersed therein so as to have a specific gravity in the range of 1.08-1.70 and a viscosity in the range 1-6,000 centipoise at 23.degree. C. The water-insoluble fine particles are present in the range of 4-60% by weight of the liquid dispersion. By improving the filling liquid, the wound golf ball is increased in flying distance while maintaining its own controllability.

Abstract: In a wound golf ball comprising a solid center (1), thread rubber (2), and a cover (3), the cover has a multi-layer structure including an outer layer (4) and an inner layer (5) having a higher hardness than the outer layer. The outer layer (4) is 0.4-3.0 mm thick, and it is formed of a first ionomer resin having a Shore D hardness of 40 to 55. The inner layer is formed of a second ionomer resin having a Shore D hardness of 55 to 68. The difference in hardness between the first and second ionomer resins is at least 5 in Shore D hardness. The ball affords improved spin and durability.

Abstract: A thread-wound golf ball having a liquid center wound by rubber thread and further having a cover placed thereon, characterized by using as the major component of the cover an ionomer whose JIS-C hardness is 70-85, making the thickness of the cover 1.0-1.8 mm, making the outside diameter of the liquid center 27-30 mm, making the center bag hardness of the liquid center 44-62 (in terms of JIS-A hardness), and making the thickness of the center bag 1.8-2.3 mm.

Abstract: In a thread-wound golf ball comprising a solid center, a thread rubber layer and a cover, the solid center has a single structure and is continuously increased in hardness from its center to its outer surface such that the difference in hardness between the center and 2 mm inside the outer surface is at least about 4 in JIS C scale hardness. The ball is improved in hitting feel.