Abstract: A mold for forming a golf ball makes it possible to form minute dimples, and to improve mold release properties of the mold and wettability of the mold by a material when a urethane material is used for a cover layer. A mold according to the present invention is a mold for forming a urethane cover as an outermost layer of a golf ball, and includes: at least two split molds that are separably joined with each other, and that includes a cavity formed therein by the joining, the cavity being for forming the urethane cover; protrusions that are formed on a cavity surface of the split molds to form dimples of the golf ball; and a composite plating film that covers the cavity surface of the split molds, that comes into contact with a material of the urethane cover, and that contains a nickel-based matrix and fluororesin particles dispersed in the nickel-based matrix.

Abstract: A mold for forming a golf ball makes it possible to form minute dimples, and to improve mold release properties of the mold and wettability of the mold by a material when a urethane material is used for a cover layer. A mold according to the present invention is a mold for forming a urethane cover as an outermost layer of a golf ball, and includes: at least two split molds that are separably joined with each other, and that includes a cavity formed therein by the joining, the cavity being for forming the urethane cover; protrusions that are formed on a cavity surface of the split molds to form dimples of the golf ball; and a composite plating film that covers the cavity surface of the split molds, that comes into contact with a material of the urethane cover, and that contains a nickel-based matrix and fluororesin particles dispersed in the nickel-based matrix.

Abstract: The invention provides a multi-piece solid golf ball having a core, an outermost layer cover with a surface on which are formed a plurality of dimples, and one or more intermediate layer between the core and the cover. At least one intermediate layer and the outermost layer cover are each formed primarily of an ionomer-containing thermoplastic resin. The resin of which the outermost layer cover is formed contains up to 20 wt % of a ternary copolymer ionomer and has formulated therein from 0.1 to 5.0 parts by weight of short organic fibers per 100 parts by weight of the resin. The golf ball of the invention has a fully satisfactory flight performance and a good feel on impact. Moreover, it has an excellent durability to cracking on repeated impact and also an excellent scuff resistance.

Abstract: The invention provides a multi-piece solid golf ball having a core, an outermost layer cover with a surface on which are formed a plurality of dimples, and one or more intermediate layer between the core and the cover. At least one intermediate layer and the outermost layer cover are each formed primarily of an ionomer-containing thermoplastic resin. The resin of which the outermost layer cover is formed contains up to 20 wt % of a ternary copolymer ionomer and has formulated therein from 0.1 to 5.0 parts by weight of short organic fibers per 100 parts by weight of the resin. The golf ball of the invention has a fully satisfactory flight performance and a good feel on impact. Moreover, it has an excellent durability to cracking on repeated impact and also an excellent scuff resistance.

Abstract: The invention provides a multi-piece solid golf ball having a core, an outermost layer cover with a surface on which are formed a plurality of dimples, and one or more intermediate layer between the core and the cover. At least one intermediate layer and the outermost layer cover are each formed primarily of an ionomer-containing thermoplastic resin. The resin of which the outermost layer cover is formed contains up to 20 wt % of a ternary copolymer ionomer and has formulated therein from 0.1 to 5.0 parts by weight of short organic fibers per 100 parts by weight of the resin. The golf ball of the invention has a fully satisfactory flight performance and a good feel on impact. Moreover, it has an excellent durability to cracking on repeated impact and also an excellent scuff resistance.

Abstract: A solid golf ball includes a core formed from a rubber composition and a cover directly covering the core. The cover is formed from a cover material mainly containing a thermoplastic urethane resin by injection molding using a mold composed of upper and lower mold halves. The core has a hardness, expressed by a deflection measured under an applied load of 5 kg to 130 kg, in a range of 2.0 mm or more. The cover has a thickness in a range of 0.9 mm to 1.7 mm. Assuming that a parting plane of the upper and lower mold halves is taken as an equator, each of the upper and lower mold halves has air vent portions in a region within a radius of 10 mm, measured as that projected on the equator plane, from a pole of the mold half. The total length of gaps of the air vent portions formed in the upper and lower mold halves is in a range of 90 mm or more. The width of each of the gaps of the air vent portions is in a range of 0.01 to 0.08 mm.

Abstract: In a solid golf ball comprising an elastic solid core and a resin cover, the cover has a JIS-C hardness of 50-85, and provided that the ball receives a spin rate S1 (rpm) in the dry state and a spin rate S2 (rpm) in the wet state when hit with a short iron having a loft of an 8-iron or greater, the percent spin retention: (S2/S1)×100 is at least 47%. The ball's spin susceptibility when hit with the short iron is not reduced in the dry state or fine weather, nor is noticeably reduced even in the wet state or rain weather. The ball has so high performance that the ball travels a distance as intended, immediately stops on the green, is easy to control and thus, suited for professional and amateur low-handicap golfers.

Abstract: In a solid golf ball comprising an elastic solid core and a resin cover, the cover has a JIS-C hardness of 50-85, and provided that the ball receives a spin rate S1 (rpm) in the dry state and a spin rate S2 (rpm) in the wet state when hit with a short iron having a loft of an 8-iron or greater, the percent spin retention: (S2/S1)×100 is at least 47%. The ball's spin susceptibility when hit with the short iron is not reduced in the dry state or fine weather, nor is noticeably reduced even in the wet state or rain weather. The ball has so high performance that the ball travels a distance as intended, immediately stops on the green, is easy to control and thus, suited for professional and amateur low-handicap golfers.

Abstract: In a solid golf ball comprising an elastic solid core and a resin cover, the cover has a JIS-C hardness of 50-85, and provided that the ball receives a spin rate S1 (rpm) in the dry state and a spin rate S2 (rpm) in the wet state when hit with a short iron having a loft of an 8-iron or greater, the percent spin retention: (S2/S1)×100 is at least 47%. The ball's spin susceptibility when hit with the short iron is not reduced in the dry state or fine weather, nor is noticeably reduced even in the wet state or rain weather. The ball has so high performance that the ball travels a distance as intended, immediately stops on the green, is easy to control and thus, suited for professional and amateur low-handicap golfers.

Abstract: In a multi-piece solid golf ball comprising a solid core and a cover of two inner and outer layers enclosing the solid core, the solid core has a deflection of at least 1.

Abstract: In a multi-piece solid golf ball comprising a solid core and a cover of two inner and outer layers enclosing the solid core and formed on the surface with a plurality of dimples, the solid core in its entirety has a hardness distribution falling within the range of JIS-C hardness 50-85, the difference between maximum and minimum JIS-C hardnesses in the solid core falls within 5%, the cover inner layer has a JIS-C hardness of 70-90, the cover outer layer has a JIS-C hardness of 60-80, the sum of high-speed region dimple operative volumes HDOV of respective dimples is 170-310, the sum of low-speed region dimple operative volumes of respective dimples LDOV is 200-310, and the overall dimple volume is 260-360 mm3.

Abstract: In a multi-piece solid golf ball comprising a rubbery elastic solid core and a resin cover including at least an inner layer, an intermediate layer and an outer layer, the solid core undergoes a deflection of 1.6-6.0 mm under an applied load of 294 N (30 kgf), the cover inner layer has a Shore D hardness of 55-70, the cover intermediate layer has a Shore D hardness of 8-50 and a gage of 0.1-1.2 mm, and the cover outer layer has a Shore D hardness of 40-55. The ball prevents any undesired increase of spin upon driver shots without detracting from rebound, has good flight performance, and receives enough spin to facilitate control on short iron shots.

Abstract: A method of manufacturing a golf ball is disclosed. A cover is molded through use of either a thermoplastic resin having a group capable of reacting with an isocyanate group or a thermoplastic resin containing a compound having two or more groups capable of reacting with an isocyanate group. Subsequently, a polyisocyanate compound is caused to permeate into the surface layer of the cover to thereby cause the reaction between the polyisocyanate compound and the group(s) capable of reacting with the isocyanate group. As a result, a modified layer having excellent properties is formed at the surface of the cover formed from thermoplastic resin. In this case, a non-yellowing polyurethane resin is preferably used as the thermoplastic resin having a group capable of reacting with an isocyanate group, and 4,4-diphenylmethane diisocyanate (MDI) is preferably used as the polyisocyanate compound.

Abstract: In a multi-piece solid golf ball comprising a solid core and a cover of two inner and outer layers enclosing the solid core, the solid core has a deflection of at least 1.

Abstract: A multi-piece solid golf ball comprising a solid core and an enclosing cover of inner and outer layers is characterized in that the solid core has a deflection of at least 1.1 mm under an applied load of 30 kg, the cover inner layer has a Shore D hardness of 45-61, the cover outer layer has a Shore D hardness of 35-55, and the sum of dimple trajectory volumes each obtained by multiplying a dimple volume by the square root of a dimple diameter is 530-750.

Abstract: A golf ball comprising an elastic solid core, an intermediate layer and a resin cover of urethane elastomer having a plurality of dimples on its surface, wherein the dimples include 330-400 circular dimples having a diameter of 3.7-5.0 mm, have a total volume of 330-380 mm3, and are substantially uniformly distributed such that there is no or only one great circle which does not intersect with the dimples exhibit uniform flight performance.

Abstract: In a multi-piece solid golf ball comprising an elastic solid core and a resin cover, the cover includes at least an inner layer and an outer layer, the solid core undergoes a deflection of 1.1-4.0 mm under a load of 294 N, the cover inner and outer layers have a Shore D hardness of 45-70 and 35-55, respectively. The ball is provided with a multiplicity of dimples which are substantially uniformly arranged such that a great circle which does not intersect with the dimples is absent. The ball exhibits consistent flight performance when hit with a driver, suppresses reduction of spin when hit in the wet state with a short iron, and offers stable ready-to-strike conditions, flight performance and spin performance under any conditions covering from the fairway to the putting green.

Abstract: A solid golf ball includes a core formed from a rubber composition and a cover directly covering the core. The cover is formed from a cover material mainly containing a thermoplastic urethane resin by injection molding using a mold composed of upper and lower mold halves. The core has a hardness, expressed by a deflection measured under an applied load of 5 kg to 130 kg, in a range of 2.0 mm or more. The cover has a thickness in a range of 0.9 mm to 1.7 mm. Assuming that a parting plane of the upper and lower mold halves is taken as an equator, each of the upper and lower mold halves has air vent portions in a region within a radius of 10 mm, measured as that projected on the equator plane, from a pole of the mold half. The total length of gaps of the air vent portions formed in the upper and lower mold halves is in a range of 90 mm or more. The width of each of the gaps of the air vent portions is in a range of 0.01 to 0.08 mm.

Abstract: A solid multi-piece golf ball includes a solid elastic core, an intermediate layer of a thermoplastic material and a cover. The core undergoes a deformation of 3.2-6.5 mm when subjected to a load of 1274 N from an initial load of 98 N. The cover has a Shore D hardness of 45-55 and the intermediate layer has a Shore D hardness of 54-65 and higher than that of the cover. The cover and the intermediate layer have a combined thickness of 2.3-3.5 mm and a ratio of cover thickness to intermediate layer thickness between 0.48 and 0.84. This combination of features provides the ball with qualities desired by professional golfers and skilled amateurs, including carry, spin performance, cracking resistance, topping durability, scuffing resistance, and feel.

Abstract: A solid golf ball having a plurality of dimples formed in its surface is characterized in that at least 70% of the entire dimples have a point of inflection at a position of 75 to 90% of their depth, and the overall dimple volume proportion is 0.7 to 0.9%.