Bridgestone Sports Co., Ltd.

Yutaka Masutani

Hisashi Yamagishi

Takashi Maruko

Keisuke Ihara

Hirotaka Shimosaka

Michio Inoue

Atsushi Nakamura

Atuki Kasasima

Atsuki Kasashima

Junji Hayashi

Yasushi Ichikawa

Junji Umezawa

Shinichi Kakiuchi

Seisuke Tomita

Kunitoshi Ishihara

Nobuhiko Matsumura

Shinich Kakiuchi

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.

Golf ball

A golf ball includes a core, and a cover made from a cover material containing an ionomer resin and also barium sulfate and titanium dioxide added in a total amount ranging from 10 to 25 parts by mass on the basis of 100 parts by mass of the ionomer resin. A flexural amount of the core, measured by applying a load of 980 N thereto, is in a range of 4.0 to 5.5 mm. A ratio of a melt-flow rate to a specific gravity (melt-flow rate/specific gravity) of the cover material is in a range of 1.6 or more. A Shore D hardness of the cover is in a range of 55 to 65.

In connection with a golf ball comprising a core, an intermediate resin layer, and a cover, the invention provides a mold defining therein a spherical cavity for molding the resin layer. The mold is divided into a pair of mold halves each of which has at least three segments which are removably assembled to define the spherical cavity, each of the segments being provided on its cavity-defining surface with at least one projection. When the core is placed in the mold cavity, the projections support the core in place. The resin layer having perforations can be effectively molded and readily removed from the mold.

Golf ball mold and golf ball

In connection with a golf ball comprising a core, an intermediate resin layer, and a cover, the invention provides a mold having a cavity wall defining a spherical cavity, wherein the core is placed in the cavity to define a space for molding the resin layer. The cavity wall is provided with a plurality of radially extending projections, the total cross-sectional area of the projections relative to the cavity wall and the total volume of the projections relative to the space volume are properly controlled.

A golf ball includes a solid core and a cover of at least one layer; wherein each of a specific gravity of the solid core and a specific gravity of the cover is nearly equal to a value (S) of a relation expression given by S&equals;W/&lsqb;(&pgr;/6)&times;D &rsqb;, where W is a weight of the golf ball and D is a diameter of the golf ball. The golf ball can enhance the durability to increase the carry of the ball with less variations in carry of the ball.

A method for producing a golf ball including a spherical elastic inner layer having a large number of projections with a round shape or a polygonal shape when viewed two-dimensionally on the outer surface with a predetermined space, and a thermoplastic resin outer layer covering the inner layer. The method employs a mold including an upper mold and a lower mold with a spherical cavity formed in the inside and a parting surface provided at a position corresponding to an equator of the spherical cavity, with pole sections of the upper mold and the lower mold each provided with a plurality of columnar support pins elongating into the cavity reciprocally movably. In the method, the inner layer is supported at the cavity center portion of the mold by the support pins from above and below at the outer surface space position, and an external layer resin is injected into the space between the inner layer and the cavity wall surface so as to integrally form the inner and outer layers.

Production method of golf ball

In a solid golf ball comprising a solid core and a cover, the solid core has a multilayer construction which includes a center core and an outer core of at least one layer that encloses the center core. The center core is formed primarily of a resin and has a diameter from 3 mm to less than 15 mm. The outer core is formed of a rubber composition based on polybutadiene. The center core has a surface hardness which is higher than the hardness of an innermost layer of the outer core. The ball has a high-pitched click and a soft feel.

Solid golf ball

A golf ball includes a core and a cover made from a cover material mainly containing an ionomer resin and also an inorganic filler having a specific gravity of 3.50 or more in an amount of 10 to 25 parts by mass on the basis of 100 parts by mass of the ionomer resin. A flexural amount of the core, measured by applying a load of 980 N thereto, is in a range of 4.7 to 5.3 mm. A specific gravity of the cover material is in a range of 1.050 to 1.100, a thickness of the cover is in a range of 1.5 to 2.0 mm, and a Shore D hardness of the cover is in a range of 57 to 63. A weight of the golf ball is in a range of 45.0 to 46.0 g, and a flexural amount of the golf ball, measured by applying a load of 980 N thereto, is in a range of 3.7 to 4.3 mm. A weight (W) of the golf ball and an inertia moment (MI) thereof satisfy a relationship of 1.53&times;W&plus;13.32&lE;MI&lE;1.61&times;W&plus;11.02. Such a golf ball can enhance the resilience to increase the carry of the ball, realize player's feeling of hitting the ball, and improve the durability against cracking.

A golf ball includes at least a core, an inner cover, and an outer cover. The inner and outer covers are of different colors. A portion of the inner cover penetrates the outer cover and is exposed to the outside on the surface of the golf ball. The exposed portion constitutes a mark portion on the surface of the golf ball. Further, an auxiliary layer is provided in contact with the inner cover. The auxiliary layer has a color different from those of the inner and outer covers and has an end surface which is exposed to the outside on the surface of the golf ball within the mark portion. Either the inner cover or the auxiliary layer completely covers the core.

Golf ball and method of manufacturing the same

A golf ball includes a core made from a rubber composition containing polybutadiene as a main rubber component and also an organic sulfur compound; and a cover made from a cover material mainly containing an ionomer resin composed of an Li ion neutralized type ionomer resin and a Mg ion neutralized ionomer resin, and also an inorganic filler having a specific gravity of 3.50 or more. A flexural amount of the core, measured by applying a load of 980 N thereto, is in a range of 4.0 to 5.5 mm. A specific gravity of the cover material is in a range of 1.020 to 1.110, and a Shore D hardness of the cover is in a range of 55 to 65. Such golf ball exhibits high durability and very high resilience.

A multilayer solid golf ball comprising a core and a cover of four layers is characterized in that the core undergoes a deflection of 2.5-5.5 mm under an applied load of 100 kg, the difference in hardness between a first layer of the cover enclosing the core and a second layer of the cover enclosing the first layer is at least 5 Shore D hardness units, the second layer has a Shore D hardness of up to 52, a third layer of the cover enclosing the second layer is harder than the second layer and a fourth layer of the cover enclosing the third layer.

A golf ball includes at least a core, an inner cover, and an outer cover. The inner cover completely encloses the core, and the inner and outer covers are of different colors. A portion of the inner cover penetrates the outer cover and is exposed to the outside on the surface of the golf ball. The exposed portion serves as a mark portion on the surface of the golf ball.

A golf ball includes a core, an intermediate layer, and a cover. At a boundary between the core and the intermediate layer or at a boundary between the intermediate layer and the cover, convex ribs are formed in a network pattern on a first layer such that the convex ribs intrude into a second layer. In addition, columnar projections are formed on the first layer at positions corresponding to the nodes of the network pattern such that the columnar projections intrude into the second layer deeper than the convex ribs.

In a solid golf ball of multilayer structure comprising a core, an enclosing layer, and a cover, the core and the enclosing layer have volumes V and V which satisfy 0.05%&lE;V /V &times;100%&lE;60%, and the core has a rebound of A (cm) and the core enclosed with the enclosing layer has a rebound of B (cm) both when dropped from a height of 120 cm, which satisfy A<B. The ball travels an increased carry at both high and low club-head speeds and ensures greater carry for low head speed players.

A solid golf ball comprising a core, an intermediate layer, and a cover is improved in rebound, distance and feel when the intermediate layer is comprised of a thermoplastic resin in admixture with rubber powder.

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Chichibu, Japan

Yutaka Masutani