Abstract: The invention provides a golf ball having a core and a cover of at least one layer. The core has a cross-sectional hardness which, letting (H?14) be a JIS-C hardness at a position 14 mm in from a surface toward a center of the core, (H?8) be a JIS-C hardness at a position 8 mm in from the surface toward the center of the core, (H?6) be a JIS-C hardness at a position 6 mm in from the surface toward the center of the core, and (H?4) be a JIS-C hardness at a position 4 mm in from the surface toward the center of the core, satisfies the formulas (1) H?14<70, (2) H?8<72, (3) H?6<75, and (3) H?4?H?8>8.

Abstract: A golf ball having a good rebound and excellent flight performance can be obtained using a golf ball composition which contains a diene polymer having an aluminum catalyst residue content of not more than 650 ppm.

Abstract: The invention provides a golf ball having a core and a cover of one layer or a plurality of layers, the core being formed of a material molded under heat from a rubber composition which includes (A) a base rubber, (B) an organic peroxide, and (C) water and/or a metal monocarboxylate. The product P×E of the difference P (mol/m3) in crosslink density between the core surface and the core center, as measured based on a toluene swelling test, multiplied by the deflection E (mm) of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf) is at least 28×102 mol/m3·mm.

Abstract: A golf ball having a good rebound and excellent flight performance can be obtained using a golf ball composition which includes a diene polymer containing not more than 1.5% of components having a molecular weight of 30,000 or less.

Abstract: A golf ball having a good rebound and excellent flight performance can be obtained using a golf ball composition which includes a diene polymer having a molecular weight distribution (Mw/Mn) of less than 1.9.

Abstract: A golf ball having a good rebound and excellent flight performance can be obtained using a golf ball composition which contains a diene polymer having a smallest molecular weight value of at least 3,000.

Abstract: A golf ball endowed with a good rebound and an excellent flight performance can be obtained using a golf ball composition of good workability which contains a diene polymer having a peak top molecular weight (Mp) on a molecular weight distribution curve measured using gel permeation chromatography (GPC) of at least 40×104 and not more than 100×104.

Abstract: The invention provides a golf ball having a core and a cover of one layer or a plurality of layers, the core being formed of a material molded under heat from a rubber composition which includes (A) a base rubber, (B) an organic peroxide, and (C) water and/or a metal monocarboxylate. The product P×E of the difference P (mol/m3) in crosslink density between the core surface and the core center, as measured based on a toluene swelling test, multiplied by the deflection E (mm) of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf) is at least 28×102 mol/m3·mm.

Abstract: A golf ball of the present invention includes: a core located in the center of the golf ball; a cover surrounding the outside of the core and having plural dimples on the surface thereof; a paint layer surrounding the outside of the cover; and a top coat further surrounding the outside of the paint layer. The paint layer is formed of a material having rubber elasticity. The top coat may have a thickness of at most approximately 60 ?m. A material for forming the paint layer has a first loss tangent, a material for forming the cover has a second loss tangent, and a difference Td between the first loss tangent and the second loss tangent may be at least approximately 0.05.

Abstract: A golf ball of the present invention includes: a core located in the center of the golf ball; a cover surrounding the outside of the core and having plural dimples on the surface thereof; and a paint layer surrounding the outside of the cover. The paint layer is formed of a material having rubber elasticity. When the golf ball has a ? hardness and the paint layer has a JIS-C hardness, a ratio Sp of the JIS-C hardness of the paint layer with respect to the ? hardness of the golf ball is at most approximately 15. When the cover has a Shore D hardness, a ratio Sc of the Shore D hardness of the cover with respect to the ? hardness of the golf ball may be at most approximately 25.

Abstract: The invention provides a golf ball having a core and a cover of one layer or a plurality of layers, the core being formed of a material molded under heat from a rubber composition which includes (A) a base rubber, (B) an organic peroxide, and (C) water and/or a metal monocarboxylate. The product P×E of the difference P (mol/m3) in crosslink density between the core surface and the core center, as measured based on a toluene swelling test, multiplied by the deflection E (mm) of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf) is at least 28×102 mol/m3·mm.

Abstract: The invention provides a rubber composition for golf balls which includes (A) a base rubber containing a polybutadiene having a cis-1,4 bond content of at least 60 wt %, (B) an unsaturated carboxylic acid and/or a metal salt thereof, and (C) a benzimidazole of general formula (1) or (2) below wherein R is a hydrogen atom or a hydrocarbon group of 1 to 20 carbons, and m is an integer from 1 to 4, with the proviso that if m is 2 or more, each occurrence of R may be the same or different. The golf ball rubber composition of the invention enables a high-quality molded and crosslinked product having a suitable hardness and a high resilience to be obtained.

Abstract: The invention provides a solid golf ball having a core and a cover. The core is formed of a rubber composition containing a base rubber, a co-crosslinking agent, a crosslinking initiator and a metal oxide. The base rubber contains polybutadiene, a styrene-butadiene rubber and, optionally, an isoprene rubber. The co-crosslinking agent is methacrylic acid, and the rubber composition includes a specific waste material in the form of a powder. The core deflection and the cover material are optimized. Utilizing a waste material in a solid golf ball conserves resources and thus is beneficial to the global environment. Even during prolonged use, the golf ball maintains its basic performance attributes (feel, flight, durability) at a high level.

Abstract: The invention provides a solid golf ball having a core and a cover. The core is formed of a rubber composition containing a base rubber, a co-crosslinking agent, a crosslinking initiator and a metal oxide. The co-crosslinking agent is methacrylic acid, and the rubber composition includes a specific waste material in the form of a powder. The core deflection and the cover material are optimized. Utilizing a waste material in a solid golf ball conserves resources and thus is beneficial to the global environment. Even during prolonged use, the golf ball maintains its basic performance attributes (feel, flight, durability) at a high level.

Abstract: The invention provides a rubber composition for golf balls which includes (A) a base rubber containing a polybutadiene having a cis-1,4 bond content of at least 60 wt %, (B) an unsaturated carboxylic acid and/or a metal salt thereof, and (C) a diphenylamine of the general formula wherein R1 and R2 are each independently a hydrogen atom or a hydrocarbon group of 1 to 20 carbons, m is an integer from 1 to 5, and n is an integer from 1 to 4, with the proviso that if m and/or n is 2 or more, each occurrence of R1 and R2 may be the same or different. The golf ball rubber composition of the invention enables a high-quality molded and crosslinked product having a suitable hardness and a high resilience to be obtained.

Abstract: The invention provides a rubber composition for golf balls which includes: (A) a base rubber containing a polybutadiene having a cis-1,4 bond content of at least 60 wt %; (B) an unsaturated carboxylic acid and/or a metal salt thereof; (C) an anthranilic acid derivative of the general formula wherein R1 and R2 are each independently a hydrogen atom or a hydrocarbon group of 1 to 20 carbons, m is an integer from 1 to 4, and n is an integer from 1 to 3, with the proviso that if m and/or n is 2 or more, each occurrence of R1 and R2 may be the same or different; and (D) sulfur. The rubber composition for golf balls of the invention enables a high-quality molded and crosslinked product having a suitable hardness and a high resilience to be obtained.

Abstract: Rubber composition for golf balls which includes: (A) a base rubber containing a polybutadiene having a cis-1,4 bond content of at least 60 wt %; (B) an unsaturated carboxylic acid and/or a metal salt thereof; (C) an anthranilic acid derivative of the general formula wherein R1 and R2 are each independently a hydrogen atom or a hydrocarbon group of 1 to 20 carbons, m is an integer from 1 to 4, and n is an integer from 1 to 3, with the proviso that if m and/or n is 2 or more, each occurrence of R1 and R2 may be the same or different; and (D) an organic peroxide having a one-minute half-life temperature which is at least 158° C. and less than 175° C. The rubber composition for golf balls of the invention enables a high-quality molded and crosslinked product having a suitable hardness and a high resilience to be obtained.

Abstract: The invention provides a golf ball endowed with an improved distance and durability. The ball has a core and a cover, the core being formed of a rubber composition containing a base rubber, a co-crosslinking agent, a crosslinking initiator, a metal oxide and an organosulfur compound. The co-crosslinking agent is methacrylic acid, the metal oxide is zinc oxide, and the rubber composition contains the crosslinking initiator in an amount of from 1.2 to 5 parts by weight per 100 parts by weight of the base rubber. The finished ball has an initial velocity of at least 74.3 m/s.

Abstract: The invention provides a golf ball endowed with an improved distance and durability. The ball has a core and a cover, the core being formed of a rubber composition containing a base rubber, a co-crosslinking agent, a crosslinking initiator and a metal oxide. The co-crosslinking agent is methacrylic acid. The core has a hardness profile in which, letting (A) be the JIS-C hardness at the core surface, (B) be the JIS-C hardness at a position 2 mm in from the surface toward the center of the core, (C) be the JIS-C hardness at a position 5 mm in from the surface toward the center of the core, (D) be the JIS-C hardness at a position 10 mm in from the surface toward the center of the core, (E) be the JIS-C hardness at a position 15 mm in from the surface toward the center of the core, and (F) be the JIS-C hardness at the center of the core, (A) to (F) have specific hardnesses.

Abstract: The invention provides a golf ball endowed with an improved distance and durability. The ball has a core and a cover, the core being formed of a rubber composition containing a base rubber, a co-crosslinking agent, a crosslinking initiator and a metal oxide. The base rubber is a mixture of (A) polybutadiene with (B) styrene-butadiene rubber and/or isoprene rubber, the co-crosslinking agent is methacrylic acid, and the metal oxide is zinc oxide. The rubber composition contains the crosslinking initiator in an amount of from 1.2 to 5 parts by weight per 100 parts by weight of the base rubber.