Bridgestone Sports Co., Ltd.

Kae Iizuka

Hiroshi Higuchi

Junji Umezawa

Daisuke Arai

Eiji Takehana

Atsushi Komatsu

Katsunori Sato

Jun Shindo

Atsuki Kasashima

Hiroyuki Nagasawa

Takashi Ohira

Masataka Kai

Hirotaka Shinohara

Toru Ogawana

Atsushi Namba

A golf ball for amateur golfers exhibits excellent flight characteristics when hit by the average golfer and also has a good feel at impact that is both soft and solid. The golf ball includes a core, an intermediate layer and a cover, and has coefficient of restitution and compressive deformation relationships that satisfy specific conditions.

Golf ball

A matte golf ball which is free of luster and gloss has such a good ball appearance that the injection marks which form during injection molding of the cover are not visible. The golf ball includes a core of at least one layer, a cover of at least one layer, and a paint film. The outermost layer of the cover is formed of a resin composition which includes a thermoplastic resin and a colorant comprising a fluorescent dye or a fluorescent pigment, and has a visible light transmittance with an average value at wavelengths in the 380 to 780 nm spectrum of from 2.0 to 50.0%. The paint film is formed of a urethane-based paint composition containing delustering particles.

A method for forming a golf ball provides a core member comprising a core of a golf ball into a cavity of a mold so that the core member is supported by a movable holding pin disposed in the mold; forming a layer outside the core member by injecting a material of the layer into the cavity; and retracting the pin from the cavity into the mold during the material injection so that a portion projecting from a surface of the layer is formed by a tip of the pin, the projecting portion having a site area of at least 0.2% in relation to an entire area of the tip of the pin and having a height of at least 0.2 mm. This method can be implemented by controlling the retraction of the pin, or alternatively by using the pin having a predetermined indentation portion on the tip.

Method for forming golf ball and mold therefor

In a colored golf ball having a core, a cover of two or more layers encasing the core, and a coat of paint applied to a surface of an outermost layer of the cover, the outermost cover layer is formed of a resin composition which includes (a) a thermoplastic resin, (b) a fluorescent color-containing color pigment and/or dye, and (c) titanium oxide. A layer adjoining an inner side of the outermost layer is formed of a resin composition containing a resin. The colored golf ball has an excellent rebound and weatherability, and also is endowed with a high brightness and a sense of quality and elegance.

Colored golf ball

The present invention provides a golf ball which includes (I) a first member composed of a material molded under heat from a rubber composition of (a) a base rubber composed primarily of a mixture of at least 60 wt % of a polybutadiene having a stress relaxation time (T), as defined below, of less than 4 seconds and up to 40 wt % of a polybutadiene having a stress relaxation time (T) of at least 4 seconds, (b) an unsaturated carboxylic acid and/or a metal salt thereof, and (c) an organic peroxide; and (II) a second member composed of a specific, highly-neutralized, resin composition. The golf ball of the invention, by being thus constituted, has an excellent resilience for the ball as a whole, a good, soft, feel on impact, and imparts an excellent spin performance, thereby enabling an increased distance to be achieved. In addition, it has a high manufacturability.

A multi-piece solid golf ball composed of a solid core having an inner core layer and an outer core layer encased by a cover including at least an inner cover layer and an outer cover layer. The inner core layer has a JIS-C cross-sectional hardness of from 60 to 83 at any single point on a cross-section, and has a cross-sectional hardness difference between any two points on the cross-section of within &#xb1;5. The ball has specific relationships between the hardness of the inner core layer 1 mm inside a boundary between the inner core layer and the outer core layer, the hardness of the outer core layer 1 mm outside the boundary, and the surface hardness of the outer core layer. And, the outer cover layer has the specific thickness and Shore D hardness, which is higher than that of the inner cover layer.

Multi-piece solid golf ball

A multi-piece solid golf ball composed of a solid core having an inner core layer and an outer core layer encased by a cover including at least an inner cover layer and an outer cover layer. The inner core layer has a JIS-C cross-sectional hardness of from 60 to 83 at any single point on a cross-section, and has a cross-sectional hardness difference between any two points on the cross-section of within &#xb1;5. The ball has specific relationships between the hardness of the inner core layer 1 mm inside a boundary between the inner core layer and the outer core layer, the hardness of the outer core layer 1 mm outside the boundary, and the surface hardness of the outer core layer. And, the outer cover layer has the specific Shore D hardness, which is lower than that of the inner cover layer.

A multi-piece solid golf ball composed of a solid core having an inner core layer and an outer core layer encased by a cover including at least an inner cover layer and an outer cover layer. The inner core layer has a JIS-C cross-sectional hardness of from 60 to 83 at any single point on a cross-section, and has a cross-sectional hardness difference between any two points on the cross-section of within &#xb1;5. The ball has specific relationships between the hardness of the inner core layer 1 mm inside a boundary between the inner core layer and the outer core layer, the hardness of the outer core layer 1 mm outside the boundary, and the surface hardness of the outer core layer. And, the difference in Shore D hardness between the inner cover layer and the outer cover layer is within &#xb1;5.

A multi-piece solid golf ball composed of a solid core having an inner core layer and an outer core layer encased by a cover of one or more layer. The inner core layer 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 &#xb1;5. The ball has specific relationships between the hardness of the inner core layer 1 mm inside a boundary between the inner core layer and the outer core layer, the hardness of the outer core layer 1 mm outside the boundary, and the surface hardness of the outer core layer.

A multi-piece solid golf ball composed of a solid core having an inner core layer and an outer core layer encased by a cover of one or more layer. The inner core layer has a JIS-C cross-sectional hardness of from 60 to 83 at any single point on a cross-section, and has a cross-sectional hardness difference between any two points on the cross-section of within &#xb1;5. The ball has specific relationships between the hardness of the inner core layer 1 mm inside a boundary between the inner core layer and the outer core layer, the hardness of the outer core layer 1 mm outside the boundary, and the surface hardness of the outer core layer.

The invention provides a multi-piece solid golf ball composed of a solid core, a cover, at least one intermediate layer situated therebetween, and a plurality of dimples on a surface of the ball. The diameter of the solid core, the deflection of the core when compressed under a final load of 130 kgf from an initial load of 10 kgf, the hardness at the center of the core, the hardness in a region 5 mm to 10 mm from the center of the core, the hardness 15 mm from the center of the core, and the surface hardness are set within specific ranges. The intermediate layer is composed primarily of a material obtained by mixing under applied heat a specific resin composition. The golf ball of the invention has an excellent flight performance, feel, controllability and scuff resistance.

The invention provides a golf ball material which is a resin mixture composed of (a) an olefin-methacrylic acid copolymer and/or an olefin-methacrylic acid-unsaturated carboxylic acid ester copolymer having a weight-average molecular weight (Mw) of from 120,000 to 200,000 and a weight-average molecular weight (Mw) to number-average molecular weight (Mn) ratio of from 4.0 to 7.0, or a metal neutralization product thereof, (b) an olefin-acrylic acid copolymer and/or an olefin-acrylic acid-unsaturated carboxylic acid ester copolymer having a weight-average molecular weight (Mw) of from 150,000 to 220,000 and a weight-average molecular weight (Mw) to number-average molecular weight (Mn) ratio of from 5.5 to 8.5, or a metal neutralization product thereof, (c) an organic acid or a metal salt thereof, and (d) a basic inorganic metal compound for neutralizing at least 70 mol % of acid groups in components (a) to (c), which resin mixture has a Shore D hardness of from 30 to 60. The golf ball material of the invention is a low-hardness material. Golf balls in which an injection molding of the golf ball material is used as a cover material have an excellent rebound and durability.

Golf ball material and method of preparing the same

The invention provides a golf ball material which is a resin mixture composed of (a) an olefin-unsaturated carboxylic acid copolymer and/or an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer having a weight-average molecular weight (Mw) of from 120,000 to 200,000 and a weight-average molecular weight (Mw) to number-average molecular weight (Mn) ratio of from 4.3 to 6.6, or a metal neutralization product thereof, (b) an olefin-unsaturated carboxylic acid copolymer and/or an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer having a weight-average molecular weight (Mw) of from 120,000 to 200,000 and a weight-average molecular weight (Mw) to number-average molecular weight (Mn) ratio of from 6.8 to 9.5, or a metal neutralization product thereof, (c) an organic acid or a metal salt thereof and (d) a basic inorganic metal compound for neutralizing at least 70 mol % of acid groups in components (a) to (c), which resin mixture has a Shore D hardness of from 30 to 55. The golf ball material of the invention is a low-hardness material. Golf balls in which an injection molding of the golf ball material is used as a cover material have an excellent rebound and durability.

The invention provides a multi-piece solid golf ball having a core, a cover of at least one layer encasing the core, and a layer of paint applied to a surface of an outermost layer of the cover, wherein the outermost cover layer or an inner cover layer adjacent to the outermost layer is formed of a resin composition which includes:

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Saitama-ken, Japan

Kae Iizuka