US-12616878-B2 - Golf ball

US12616878B2US 12616878 B2US12616878 B2US 12616878B2US-12616878-B2

Abstract

An object of the present disclosure is to provide a golf ball having lowered resilience while maintaining the hardness of the golf ball. The present disclosure provides a golf ball comprising a constituent member, wherein at least a part of the constituent member is formed from a cured product of a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, (a) the base rubber contains (a1) a natural rubber and a grafting ratio of (b) the co-crosslinking agent in the cured product of the rubber composition ranges from 40 mass % to 80 mass %.

Inventors

Takumi Kaneko
Hikaru NAGAKURA
Takehiko HYODO
Kazuyoshi Shiga
Yuko KUJIRAI
Hiroaki Tanaka

Assignees

SUMITOMO RUBBER INDUSTRIES, LTD.

Dates

Publication Date: 20260505
Application Date: 20240215
Priority Date: 20230216

Claims (15)

1 . A one-piece golf ball comprising a golf ball body, wherein the golf ball body is formed of a cured product of a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, wherein (a) the base rubber contains (a1) a natural rubber, a grafting ratio of (b) the co-crosslinking agent in the cured product of the rubber composition ranges from 40 mass % to 80 mass %, and the one-piece golf ball has a diameter ranging from 40 mm to 45 mm, a compression deformation amount (shrinking amount along the compression direction) ranging from 2.0 mm to 6.0 mm when applying a load from an initial load of 98 N to a final load of 1275 N to the one-piece golf ball, and a coefficient of restitution (e40) ranging from 0.500 to 0.700.
2 . The golf ball according to claim 1 , wherein an amount of (a1) the natural rubber is 10 mass % or more in 100 mass % of (a) the base rubber.
3 . The golf ball according to claim 1 , wherein an amount of (a1) the natural rubber ranges from 20 mass % to 80 mass % in 100 mass % of (a) the base rubber.
4 . A one-piece golf ball comprising a golf ball body, wherein the golf ball body is formed of a cured product of a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, wherein (a) the base rubber contains (a1) a natural rubber, an amount of a graft polymer of (b) the co-crosslinking agent in the cured product of the rubber composition ranges from 10.0 parts by mass to 18.0 parts by mass, an amount of a non-graft polymer of (b) the co-crosslinking agent in the cured product of the rubber composition ranges from 3.0 parts by mass to 15.0 parts by mass with respect to 100 parts by mass of the (a) base rubber, and the one-piece golf ball has a diameter ranging from 40 mm to 45 mm, a compression deformation amount (shrinking amount along the compression direction) ranging from 2.0 mm to 6.0 mm when applying a load from an initial load of 98 N to a final load of 1275 N to the one-piece golf ball, and a coefficient of restitution (e40) ranging from 0.500 to 0.700.
5 . The golf ball according to claim 4 , wherein an amount of (a1) the natural rubber is 10 mass % or more in 100 mass % of (a) the base rubber.
6 . The golf ball according to claim 4 , wherein an amount of (a1) the natural rubber ranges from 20 mass % to 80 mass % in 100 mass % of (a) the base rubber.
7 . A golf ball comprising a constituent member, wherein at least a part of the constituent member is formed of a cured product of a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, (a) the base rubber contains (a1) a natural rubber and (a2) a synthetic rubber, and the cured product of the rubber composition satisfies the following formulae (3) and (4) 3.5 ≤ ( 100 - A ) / Y ≤ 5 . 0 ( 3 ) 3. ≤ A / Z ≤ 7 . 0 ( 4 ) wherein in the formulae (3) and (4), A represents the amount of (a1) the natural rubber in the base rubber component (mass %), Y represents an amount (parts by mass) of a graft polymer of (b) the co-crosslinking agent in the cured product of the rubber composition and Z represents an amount (parts by mass) of a non-graft polymer of (b) the co-crosslinking agent in the cured product of the rubber composition with respect to 100 parts by mass of the (a) base rubber.
8 . The golf ball according to claim 7 , wherein the amount of (a1) the natural rubber is 10 mass % or more in 100 mass % of (a) the base rubber.
9 . The golf ball according to claim 7 , wherein the golf ball is a one-piece golf ball, and a golf ball body thereof is formed from the cured product of the rubber composition.
10 . The golf ball according to claim 7 , wherein the golf ball has a diameter ranging from 40 mm to 45 mm, a compression deformation amount (shrinking amount along the compression direction) ranging from 2.5 mm to 6.0 mm when applying a load from an initial load of 98 N to a final load of 1275 N to the golf ball, and a coefficient of restitution (e40) ranging from 0.500 to 0.700.
11 . The golf ball according to claim 10 , wherein the compression deformation amount ranges from 3.0 mm to 6.0 mm.
12 . A golf ball comprising a constituent member, wherein at least a part of the constituent member is formed of a cured product of a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, (a) the base rubber contains (a1) a natural rubber and (a2) a synthetic rubber, a grafting ratio of (b) the co-crosslinking agent in the cured product of the rubber composition ranges from 40 mass % to 80 mass %, the cured product of the rubber composition satisfies the following formula (1) when an amount of (a1) the natural rubber is 40 mass % or less in 100 mass % of (a) the base rubber, and the cured product of the rubber composition satisfies the following formula (2) when an amount of (a1) the natural rubber is more than 40 mass % in 100 mass % of (a) the base rubber: 0.7 ≤ ( 100 - A ) / X ≤ 1.25 ( 1 ) 0.7 ≤ A / ( 100 - X ) ≤ 1.25 ( 2 ) wherein in the formulae (1) and (2), A represents the amount of (a1) the natural rubber in the base rubber component (mass %), and X represents the grafting ratio of the co-crosslinking agent (mass %), and the golf ball has a diameter ranging from 40 mm to 45 mm, a compression deformation amount (shrinking amount along the compression direction) ranging from 2.5 mm to 6.0 mm when applying a load from an initial load of 98 N to a final load of 1275 N to the golf ball, and a coefficient of restitution (e40) ranging from 0.500 to 0.700.
13 . The golf ball according to claim 12 , wherein the amount of (a1) the natural rubber is 10 mass % or more in 100 mass % of (a) the base rubber.
14 . The golf ball according to claim 12 , wherein the golf ball is a one-piece golf ball, and a golf ball body thereof is formed from the cured product of the rubber composition.
15 . The golf ball according to claim 12 , wherein the compression deformation amount ranges from 3.0 mm to 6.0 mm.

Description

FIELD OF THE DISCLOSURE The present disclosure relates to a golf ball. DESCRIPTION OF THE RELATED ART Conventionally, as a golf ball used in a driving range, a golf ball travelling a restricted flight distance has been developed. For example, JP S60-92780 A discloses a practice court golf ball obtained by vulcanizing a composition containing 3 to 35 parts by weight of a rubber with low resilience, 20 to 30 parts by weight of methacrylic acid, and 20 to 50 parts by weight of a metal compound which can form a metal salt with methacrylic acid, with respect to 100 parts by weight of a base rubber. In addition, JP S61-71069 A discloses a range golf ball obtained from a composition containing 3 to 35 parts by weight of an epoxidized natural rubber with an epoxidation degree of 10 to 60 mole %, 20 to 35 parts by weight of methacrylic acid, and 20 to 50 parts by weight of zinc oxide, with respect to 100 parts by weight of a base rubber. SUMMARY OF THE DISCLOSURE Recently, a space-limited driving range such as an indoor practice driving range is increasing, and a golf ball travelling a restricted flight distance is desired. However, when the resilience of a golf ball is lowered such that the golf ball can be suitably used even in a narrow driving range, the golf ball tends to become excessively soft. The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a golf ball having lowered resilience while maintaining the hardness of the golf ball. The present disclosure that has solved the above problem provides a golf ball comprising a constituent member, wherein at least a part of the constituent member is formed of a cured product of a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, (a) the base rubber contains (a1) a natural rubber, a grafting ratio of (b) the co-crosslinking agent in the cured product of the rubber composition ranges from 40 mass % to 80 mass %. In the present disclosure, since the rubber composition contains a natural rubber as the base rubber, the cured product of the rubber composition has a lowered coefficient of restitution. Further, if the grafting ratio of (b) the co-crosslinking agent in the cured product of the rubber composition falls in a range from 40 mass % to 80 mass %, the hardness of the cured product is controlled for a golf ball to have a compression deformation amount adjusted in an appropriate range. Thus, if at least a part of the constituent member of the golf ball is formed of the inventive cured product of the rubber composition, the golf ball has lowered resilience while maintaining a hardness of the golf ball. In a preferable embodiment of the present disclosure, the golf ball comprises a constituent member, wherein at least a part of the constituent member is formed of a cured product of a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, (a) the base rubber contains (a1) a natural rubber and (a2) a synthetic rubber, a grafting ratio of (b) the co-crosslinking agent in the cured product of the rubber composition ranges from 40 mass % to 80 mass %, the cured product of the rubber composition satisfies the following formula (1) when an amount of (a1) the natural rubber is 40 mass % or less in 100 mass % of (a) the base rubber, and the cured product of the rubber composition satisfies the following formula (2) when an amount of (a1) the natural rubber is more than 40 mass % in 100 mass % of (a) the base rubber. 0.7≤(100-A)/X≤1.25(1)0.7≤A/(100-X)≤1.25(2) [In the formulae (1) and (2), A represents the amount of the natural rubber in the base rubber component (mass %), and X represents the grafting ratio of the co-crosslinking agent (mass %).] The cured product of the rubber composition used in the present disclosure has a lowered coefficient of restitution by containing (a1) the natural rubber as (a) the base rubber. In addition, if the formula (1) or the formula (2) is satisfied depending on the amount of (a1) the natural rubber, the hardness of the cured product is controlled for a golf ball to have a compression deformation amount adjusted in an appropriate range. Thus, if at least a part of the constituent member of the golf ball is formed of the inventive cured product of the rubber composition, the golf ball has a lowered resilience while maintaining a hardness of the golf ball. In another preferable embodiment of the present disclosure, the golf ball comprises a constituent member, wherein at least a part of the constituent member is formed of a cured product of a rubber composition containing (a) a base rubber, (b) a co-crosslinking agent and (c) a crosslinking initiator, (a) the base rubber contains (a1) a natural rubber, andan amount of a graft polymer of (b) the co-crosslinking agent in the cured product of the rubber composition ranges from 10.0 parts by mass to 18.0 pats by m