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 thiourea of the general formula wherein R is independently at each occurrence a hydrogen atom or a hydrocarbon group of 1 to 20 carbons. 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 golf ball having a core and a cover of at least one layer. The core is formed of a rubber composition which includes a polybutadiene-containing base rubber, an unsaturated carboxylic acid and/or a metal salt thereof, an organic peroxide and sulfur, and for which the value of [sulfur (mol)÷available active oxygen content in organic peroxide] is at least 0.01 and not more than 0.019.

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 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. The paint layer may have a thickness of at most approximately 100 ?m. The paint layer may have a hardness of at most approximately 70 in terms of JIS-C hardness. The cover may contain ionomer resin. The cover may have a hardness of at least 40 in terms of Shore D hardness.

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: 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 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 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 contains a diene polymer having an aluminum catalyst residue content of not more than 650 ppm.

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 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) below wherein R1 and R2 are each independently a hydrogen atom or a hydrocarbon group of 1 to 20 carbons, and m and n are each 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, and (C) a thiourea of the general formula wherein R is independently at each occurrence a hydrogen atom or a hydrocarbon group of 1 to 20 carbons, with the proviso that at least one occurrence of R is a hydrocarbon group of 1 to 20 carbons. 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, and (C) a thiourea of the general formula wherein R is independently at each occurrence a hydrogen atom or a hydrocarbon group of 1 to 20 carbons. 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, 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 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, and (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. 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: A practice golf ball has a core and a cover. The core is made of a rubber composition which includes a base rubber, a co-crosslinking agent, a crosslinking initiator and a metal oxide. The base rubber is a mixture of polybutadiene with styrene-butadiene rubber and/or isoprene rubber, and the co-crosslinking agent is methacrylic acid. The core has a specific deflection under a specific load, and the ball has a specific initial velocity. The dimples on the surface of the ball have a volume ratio VR of from 0.95 to 1.7.

Abstract: In a practice golf ball having a core and a cover encasing the core, the cover has a material hardness, expressed as the Shore D hardness, of from 30 to 57. The core has an initial velocity CV (m/s) and the ball has an initial velocity BV1 (m/s) such that the value CV?BV1 satisfies the condition (CV?BV1)=0.7×(cover thickness)?b, where 0.1?b?1.0. The ball has a soft feel on impact like that of a one-piece golf ball and thus is able to reduce strain on the player's body, in addition to which it has much better durability to cracking than commonly used game balls, good retention of appearance even with long-term use, and a distance that is controlled so as to be appropriate for a driving range.

Abstract: A practice golf ball with a core and a cover has, upon initial measurement, a deflection BH1 (mm) when compressed under a final load of 1,275 N from an initial load of 98 N and an initial velocity BV1 (m/s), and also has, when measured again after being left to stand for 350 days following initial measurement, a deflection BH2 (mm) when compressed under a final load of 1,275 N from an initial load of 98 N and an initial velocity BV2 (m/s), such that the difference BH2?BH1 is not more than 0.2 mm and the difference BV2?BV1 is not more than 0.3 m/s. The ball has excellent durability to cracking and durability of appearance, and also maintains a stable feel and flight performance over a long period of time.