Bridgestone Sports Co., Ltd.

Fujifilm Corporation

Nippon Shokubai Co., Ltd.

Nihon Joryu Kogyo Co., Ltd.

Nobuyuki Kataoka

Hiroshi Higuchi

Atsushi Nanba

Hiroto Sasaki

Hiroyuki Nagasawa

Kazuhiko Nakamura

Shojiro Kaita

Manabu Hasegawa

Yasuo Wakatsuki

Yoshinori Saito

Keiji Kobayashi

Masataka Imoto

Yoshihiko Fujii

A golf ball which is formed from a vulcanized rubber compound composed of 100 parts by weight of a rubber base material, 10 to 60 parts by weight of an unsaturated carboxylic acid and/or a metal salt thereof, 0.1 to 5 parts by weight of an organosulfur compound, 5 to 80 parts by weight of an inorganic filler, and 0.1 to 3 parts by weight of an organic peroxide, the rubber base material being composed of a first polybutadiene accounting for 50 to 95 wt % and a second polybutadiene accounting for 5 to 50 wt %, both polybutadiene being synthesized by using a rare earth element-based catalyst, the first polybutadiene containing no less than 60 wt % of cis-1,4 bonds and having a Mooney viscosity (ML1+4 (100&#xb0; C.)) no lower than 50 and the second polybutadiene containing no less than 60 wt % of cis-1,4 bonds and having a Mooney viscosity (ML1+, (100&#xb0; C.)) no higher than 45. The golf ball is characterized by good rebound resilience and good workability with which it is produced.

Golf ball

A golf ball which is formed from a vulcanized rubber compound composed of 100 parts by weight of a rubber base material, 10 to 60 parts by weight of an unsaturated carboxylic acid and/or a metal salt thereof, 0.1 to 5 parts by weight of an organosulfur compound, 5 to 80 parts by weight of an inorganic filler, and 0.1 to 3 parts by weight of an organic peroxide, the rubber base material being composed of a first polybutadiene accounting for 50 to 95 wt % and a second polybutadiene accounting for 5 to 50 wt %, both polybutadiene being synthesized by using a rare earth element-based catalyst, the first polybutadiene containing no less than 60 wt % of cis-1,4 bonds and having a Mooney viscosity (ML(100&#xb0; C.)) no lower than 50 and the second polybutadiene containing no less than 60 wt % of cis-1,4 bonds and having a Mooney viscosity (ML(100&#xb0; C.)) no higher than 45. The golf ball is characterized by good rebound resilience and good workability with which it is produced.

A rubber composition for a one-piece golf ball or the solid core of a multilayer structure solid golf ball having a solid core enclosed with a cover directly or via an intermediate layer is provided comprising a base rubber, a dry preblend of an unsaturated carboxylic acid metal salt with a solid rubber having a Mooney viscosity (ML, 100&#xb0; C.) of 5&#x2013;150, and an organic peroxide.

Rubber composition for golf ball and golf ball

A golf ball, typically its core, is manufactured by hot molding a rubber composition comprising a base rubber, an unsaturated carboxylic acid or a metal salt thereof, and an organic peroxide, the base rubber comprising a methacryloxy or acryloxy-modified silicone polymer and optionally, a peroxide-crosslinkable rubber. The golf ball exhibits high rebound and prevents the rebound property from declining at low temperatures.

A rubber compound for solid golf balls which includes (A) a base rubber, (B) a filler, (C) an organic peroxide, and (D) a co-crosslinking agent coated with a coating rubber in which the ratio of the co-crosslinking agent to the coating rubber is from 100/1 to 100/20 by weight. A solid golf ball with good flight performance and uniform quality which is formed from the rubber compound. The rubber compound contains a co-crosslinking agent (a metal salt of unsaturated carboxylic acid) finely dispersed therein and also permits processing with good workability.

Rubber compound for solid golf balls and solid golf ball

A golf ball, typically its core, is manufactured by molding and vulcanizing a rubber composition comprising a base rubber, an unsaturated carboxylic acid or a metal salt thereof, an inorganic filler, an organic peroxide, and an organosulfur compound. The base rubber contains a polybutadiene having a Mw of 60&#x2013;150&#xd7;10and a Mw/Mn of up to 2.0 and containing at least 98% of cis-1,4 bonds and up to 1.5% of trans-1,4 bonds. The composition is easy to mold and work, and the golf ball has good rebound and improved flight performance.

A golf ball comprises a solid core consisting of a center core and an outer core, wherein at least one of cores is made of a rubber composition comprising 100 parts by weight of a base rubber including. 60 to 100% by weight of a polybutadiene containing at least 60% by weight of cis-1,4-bond, having a Mooney viscosity (ML(100&#xb0; C.)) of at least 52, and synthesized using a rare-earth catalyst, 10 to 60 parts by weight of an unsaturated carboxylic acid and/or a metal salt thereof, 5 to 80 parts by weight of an-inorganic filler, and an organic peroxide, and wherein the center core has a JIS-C hardness of 40 to 60 on its center and a JIS-C hardness of 55 to 75 on its surface and the difference therebetween is at least 10, the outer core is harder than the surface hardness of the center core, the cross-sectional hardness of 1 mm outside from the border between the center core and the outer core is from 65 to 85 on a JIS-C hardness, the surface of the outer core has a JIS-C hardness of 75 to 95.

A golf ball-which is formed from a crosslinked rubber compound composed of, as essential components, (A) a rubber base material composed of (a) a polybutadiene containing no less than 60 wt % of cis-1,4 bonds and having a Mooney viscosity (ML(100&#xb0; C.)) of 50 to 120, which is synthesized by using a group VIII element catalyst and/or a rare earth element-based catalyst, and (b) a solid isoprene rubber containing no less than 60 wt % of cis-1,4 bonds and having a Mooney viscosity (ML(100&#xb0; C.)) of 70 to 90, with the ratio of (a) to (b) being from 70/30 to 98/2 by weight; (B) an unsaturated carboxylic acid and/or a metal salt thereof; and (C) an organic peroxide. The golf ball is characterized by good rebound resilience and good workability with which it is produced.

A golf ball which is formed from a crosslinked rubber compound composed of, as essential components, (A) a rubber base material composed of (a) a polybutadiene containing no less than 60 wt % of cis-1,4 bonds and having a Mooney viscosity (ML(100&#xb0; C.)) of 50 to 120, which is synthesized by using a group VIII catalyst element and/or a rare earth element-based catalyst, and (b) a solid isoprene rubber containing no less than 60 wt % of cis-1,4 bonds and having a Mooney viscosity (ML(100&#xb0; C.)) of 70 to 90, with the ratio of (a) to (b) being from 96/4 to 99/1 by weight; (B) an unsaturated carboxylic acid and/or a metal salt thereof; and (C) an organic peroxide. The golf ball is characterized by good rebound resilience and good workability with which it is produced.

A golf ball has a core obtained by molding and vulcanizing a rubber composition comprising (A) a base rubber which includes a polybutadiene having a cis-1,4 content of at least 60 wt %, (B) an unsaturated carboxylic acid and/or metal salt thereof, (C) an inorganic filler and (D) at least one organic peroxide selected from among 1,1-bis(t-hexylperoxy)cyclohexane, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, and 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane. The golf ball has excellent rebound characteristics and flight performance as well as a high productivity due to a reduced vulcanization time.

A golf ball is characterized by comprising a molded and vulcanized product of a rubber composition as a constituent component, the rubber composition comprising 100 pbw of a base rubber including 60&#x2013;100 wt % of a polybutadiene containing at least 60 wt % of cis-1,4-bond, having a Mooney viscosity (ML(100&#xb0; C.)) of at least 40, and synthesized using a rare-earth catalyst, 10&#x2013;60 pbw of an unsaturated carboxylic acid and/or a metal salt thereof, 0.1&#x2013;5 pbw of an organosulfur compound, 5&#x2013;80 pbw of an inorganic filler, and at least two organic peroxides including an organic peroxide having the shortest half-life at 155&#xb0; C. designated (a) and another organic peroxide having the longest half-life at 155&#xb0; C. designated (b), a ratio of half-lives (b/a) being from 7 to 20 wherein ais the half-life of (a) and bis the half-life of (b), a total content of the organic peroxides being 0.1&#x2013;0.8 pbw per 100 pbw of the base rubber.

A golf ball is manufactured by molding and vulcanizing a rubber composition comprising 100 pbw of a base rubber composed primarily of a polybutadiene having a cis-1,4 content of at least 60 wt % and a Mooney viscosity of at least 30 and synthesized using a rare-earth catalyst, 15&#x2013;50 pbw of an unsaturated carboxylic acid and/or a metal salt thereof, at least 2 pbw of a processing aid having a highest melting point of up to 115&#xb0; C., and 1&#x2013;5 pbw of an organic peroxide. The golf ball can be efficiently manufactured and has excellent rebound characteristics.

A zinc acrylate particle composition which is substantially fine and, even when kneaded with a rubber composition, is capable of being uniformly dispersed and kneaded in a state very rarely inducing fast adhesion or agglomeration, a method for the production thereof, and a golf ball using the composition are provided. The zinc acrylate particle composition contemplated by this invention comprises zinc acrylate satisfying the conditions that the proportion accounted for by the zinc acrylate particles measuring not less than 300 &#x3bc;m in particle size as determined by the dry type method be not more than 20% by mass of all the particles, that the median of particle sizes as determined by the dry type method be in the range of 10-300 &#x3bc;m, and that the ratio of the median (A) of particle sizes as determined by the dry type method to the median (B) of particle sizes as determined by the wet type method exceed 2, and an anionic surfactant.

Zinc acrylate particle composition, method for production thereof, and golf ball using the composition

A golf ball is characterized by comprising a molded and vulcanized product of a rubber composition as a constituent component, the rubber composition comprising 100 pbw of a base rubber composed primarily of a polybutadiene containing at least 60 wt % of cis-1,4-bond, having a Mooney viscosity (ML, 100&#xb0; C.) of at least 30, and synthesized using a rare-earth catalyst, 15-50 pbw of an unsaturated carboxylic acid and/or a metal salt thereof, at least 2 pbw of a processing aid having a highest melting point of up to 115&#xb0; C., and at least two organic peroxides including an organic peroxide having the shortest half-life at 155&#xb0; C. designated (a) and another organic peroxide having the longest half-life at 155&#xb0; C. designated (b), a ratio of half-lives (b/a) being at least 7 wherein ais the half-life of (a) and bis the half-life of (b), a total content of the organic peroxides being 0.1-0.9 pbw per 100 pbw of the base rubber.

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Chichibu, Japan

Nobuyuki Kataoka