Bridgestone Sports Co., Ltd.

Jun Shindo

Atsushi Nanba

Eiji Takehana

Hisashi Yamagishi

Yoshinori Egashira

Takahiro Hayashi

Akira Kimura

Hideo Watanabe

Kae Yamazaki

Hiroyuki Nagasawa

Atsushi Nakamura

Kae Iizuka

Katsunobu Mochizuki

Hiroto Sasaki

Hiroshi Higuchi

Tsuyoshi Nakajima

Toru Ogawana

Yasushi Ichikawa

Rinya Takesue

Shinichi Kakiuchi

Junji Umezawa

Takashi Maruko

Takashi Ohira

Daisuke Arai

Kazuyuki Ichioka

In a golf ball having a core and a cover of one or more layer, the core is formed of a material molded under heat from a rubber composition containing This ball achieves both a lower spin rate and excellent durability while maintaining a high rebound.

Golf ball

In a golf ball having a core composed of one or more layer, the outermost layer of the core is formed of a rubber composition containing an α,β-unsaturated metal carboxylate, and an envelope layer directly encasing the core is formed of a resin composition containing a thermoplastic resin having a structure that includes α,β-ethylenically unsaturated carboxylic acid copolymerization units. The infrared absorption spectra at surface sites on the outermost layer of the core, as measured by ATR FT-IR spectroscopy, satisfy a specific condition. The ball has an enhanced adhesion between the rubber-based core and the adjacent cover layer that is formed of an ionomer resin or other α,β-ethylenically unsaturated carboxylic acid copolymer-containing resin material.

Golf ball and method of manufacture

A rubber composition for a golf ball core includes (a) a conjugated diene polymer, (b) a copolymer of a conjugated diene compound and a non-conjugated olefin, and (c) an organic peroxide. Golf balls having at least one core layer formed of such a rubber composition and a cover of one or more layers encasing the core exhibit improved durability to cracking on repeated impact while maintaining the basic properties required of golf balls, such as flight and spin controllability on approach shots.

Rubber composition for golf ball core, and golf ball

A rubber composition for a golf ball core includes (a) a conjugated diene polymer, (b) a multi-component copolymer having conjugated diene units, non-conjugated olefin units and aromatic vinyl units, and (c) an organic peroxide. The conjugated diene units include butadiene units, the non-conjugated olefin units include ethylene units, and the aromatic vinyl units include styrene units. The content of conjugated diene units with respect to the multi-component copolymer is at least 5 wt %. Golf balls having at least one core layer formed of such a rubber composition and a cover of one or more layers encasing the core exhibit improved durability to cracking on repeated impact while maintaining the basic properties required of golf balls, such as flight and spin controllability on approach shots.

In a golf ball having a core composed of one or more layer, the outermost layer of the core is formed of a rubber composition containing an &#x3b1;,&#x3b2;-unsaturated metal carboxylate, and an envelope layer directly encasing the core is formed of a resin composition containing a thermoplastic resin having a structure that includes &#x3b1;,&#x3b2;-ethylenically unsaturated carboxylic acid copolymerization units. The infrared absorption spectra at surface sites on the outermost layer of the core, as measured by ATR FT-IR spectroscopy, satisfy a specific condition. The ball has an enhanced adhesion between the rubber-based core and the adjacent cover layer that is formed of an ionomer resin or other &#x3b1;,&#x3b2;-ethylenically unsaturated carboxylic acid copolymer-containing resin material.

A rubber composition for golf balls includes (a) a base rubber, (b) a co-crosslinking agent which is an &#x3b1;,&#x3b2;-unsaturated carboxylic acid and/or a metal salt thereof, (c) a crosslinking initiator, and (d) an alcohol having a value obtained by dividing the molecular weight of the alcohol by the number of hydroxyl groups thereon which is 70 or less. When the rubber composition is used in a golf ball having a core and a cover of one or more layers encasing the core, by setting the hardness difference in the core interior hardness profile to a large value while maintaining a desired core hardness, low spin properties can be manifested on golf ball shots, enabling the flight performance of the ball to be improved.

Rubber composition for golf ball, and golf ball

In a golf ball having a core composed of one or more layer, the outermost layer of the core is formed of a rubber composition containing a base rubber and an &#x3b1;,&#x3b2;-unsaturated metal carboxylate, an envelope layer directly encasing the core is formed of a resin composition containing a thermoplastic resin having a structure that includes &#x3b1;,&#x3b2;-ethylenically unsaturated carboxylic acid copolymerization units, and a surface of the core outermost layer and the envelope layer adjoin each other through an intervening oxazoline group-containing substance. The golf ball has improved adhesion between the rubber-based core and the cover layer that directly encases the core and is formed of an ionomer resin or other &#x3b1;,&#x3b2;-ethylenically unsaturated carboxylic acid copolymer-containing resin material.

In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, the core, an intermediate layer-encased sphere and the ball have surface hardnesses which satisfy a specific relationship, and the envelope layer, the intermediate layer and the cover have thicknesses which satisfy a specific relationship. Also, the core has a hardness profile in which the hardnesses at the core surface, core center, a position 5 mm from the core center, and a position midway between the surface and center of the core satisfy specific relationships. This golf ball, when used by mid- and high-level amateurs, enables the golfer to maintain an adequate distance on shots with a driver and achieve a good distance on iron shots, has a good spin performance on approach shots and has a good feel on impact. In addition, the ball has an excellent scuff resistance when struck with a grooved wedge.

Multi-piece solid golf ball

In order to satisfy at a high level the golf ball flight and control performances relied on by professional golfers and skilled amateurs, this invention provides a multi-piece solid golf ball G having a corea coverand an intermediate layertherebetween wherein the core is formed of a rubber composition that includes an alcohol having a value obtained by dividing the molecular weight of the alcohol by the number of hydroxyl groups thereon which is 70 or less. Also, letting Hc be the JIS-C hardness at the center of the core, H12 be the JIS-C hardness at a position 12 mm from the core center and Ho be the JIS-C hardness at the surface of the core, the core has a hardness profile in which these hardnesses satisfy fixed relationships defined by specific formulas.

In a golf ball having a core of one or more layer and a cover of one or more layer encasing the core, the core has a deflection when compressed under a specific load of at least 3.8 mm; at least an innermost portion of the core has a specific difference between maximum and minimum values in cross-sectional hardnesses (JIS-C) from a center to a surface thereof; and the center core is formed of a rubber composition that includes (a) a base rubber, (b) an &#x3b1;,&#x3b2;-unsaturated carboxylic acid and/or metal salt thereof, (c) a diacyl peroxide and/or a peroxyester, and (d) a dialkyl peroxide and/or a peroxyketal. The golf ball has a low spin rate on driver shots by low head speed golfers, and thus achieves an improved distance, while minimizing any decrease in durability.

A rubber composition for golf balls includes (a) a base rubber, (b) a co-crosslinking agent which is an &#x3b1;,&#x3b2;-unsaturated carboxylic acid and/or a metal salt thereof, (c) an organic peroxide, (d) water or an alcohol, and (e) an antioxidant which is a benzoimidazole of the following general formula and/or a metal salt thereof. When the rubber composition is used in constituent members of a golf ball, especially the core, the golf ball exhibits low spin properties on shots, resulting in an improved flight performance and enabling a good durability to be maintained.

A rubber composition for golf balls includes (a) a base rubber, (b) a co-crosslinking agent which is an &#x3b1;,&#x3b2;-unsaturated carboxylic acid and/or a metal salt thereof, (c) a crosslinking initiator, and (d) a lower alcohol having a molecular weight of less than 200. When the rubber composition is used in a golf ball having a core and a cover of one or more layers encasing the core, by setting the hardness difference in the core interior hardness profile to a large value while maintaining a desired core hardness, low spin properties can be manifested on golf ball shots, enabling the flight performance of the ball to be improved.

A golf ball having a center core, one or more envelope layer encasing the center core and one or more cover layer is provided wherein at least one envelope layer is formed of a rubber composition that includes (a) a diene rubber, (b) a tetrazine compound of a specific formula or a metal salt thereof, (c) an &#x3b1;,&#x3b2;-unsaturated carboxylic acid metal salt and (d) an organic peroxide. A method for manufacturing the golf ball is also provided. The golf ball has a high rebound and durability. The manufacturing method, by eliminating the need to furnish equipment for a bonding step, lowers production costs and is industrially advantageous.

In a multi-piece solid golf ball having a core, a cover and an intermediate layer therebetween, the core, an intermediate layer-encased sphere and the ball have surface hardnesses which satisfy a specific relationship, and the intermediate layer and the cover have thicknesses which satisfy a specific relationship. Also, the core has a hardness profile in which the hardnesses at the core surface, core center, a position 5 mm from the core center, and a position midway between the surface and center of the core satisfy specific relationships. This golf ball, when used by mid- and high-level amateurs, enables the golfer to maintain an adequate distance on shots with a driver and achieve a good distance on iron shots, has a good spin performance on approach shots and has a good feel on impact. In addition, the ball has an excellent scuff resistance when struck with a grooved wedge.

Growing community of inventors

Chichibu, Japan

Jun Shindo