Golf ball

Patent metadata

Field	Value
Publication number	US-10065079-B2
Application number	US-201715495264-A
Country	US
Kind code	B2
Filing date	Apr 24, 2017
Priority date	Dec 15, 2014
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

Golf ball having a core and a cover of one or more layers, the core being formed of a material molded under heat from a rubber composition including a base rubber, an organic peroxide, and water and/or a metal monocarboxylate. Defining the tan δ slope as (tan δ 10 −tan δ 1 )/(10%−1%), where tan δ 1 and tan δ 10 are the loss tangents at dynamic strains of, respectively, 1% and 10% when the loss tangents of the core center and the core surface are measured at −12° C. and 15 Hz, the difference between the tan δ slopes at the core surface and the core center is larger than 0.002. Because a core material which undergoes little decrease in resilience over time and experiences little energy loss can be obtained, the golf ball maintains a good rebound, has a reduced spin rate and thus is able to achieve an increased distance.

First claim

The invention claimed is:

1. A golf ball comprising a core and a cover of one layer or a plurality of layers, wherein the core is formed of a material molded under heat from a rubber composition comprising:
(A) a base rubber,
(B) an organic peroxide, and
(C) a metal monocarboxylate; and
letting tan δ 1 be the loss tangent at a dynamic strain of 1% and tan δ 10 be the loss tangent at a dynamic strain of 10% when the loss tangents of the core center and the core surface are measured at a temperature of −12° C. and a frequency of 15 Hz, and defining the tan δ slope as (tan δ 10 −tan δ 1 )/(10%−1%), the difference between the tan δ slope at the core surface and the tan δ slope at the core center is larger than 0.002, and the tan δ slope at the core surface is larger than the tan δ slope at the core center.

2. The golf ball of claim 1 , wherein the difference (B)−(A) within the core between the JIS-C cross-sectional hardness (A) at a position 6 mm from the core center and the JIS-C cross-sectional hardness (B) at a position 16 mm from the core center is larger than 13.

3. The golf ball of claim 1 which satisfies the condition V 0 −V 60 <0.7, wherein V 0 is the initial velocity of the core in the golf ball after the cover has been molded, as measured after peeling away the cover, and V 60 is the core initial velocity measured 60 days after measuring V 0 .

4. The golf ball of claim 1 , wherein the moisture content in the rubber composition prior to vulcanization is at least 1,000 ppm.

5. The golf ball of claim 1 wherein, in the vulcanized core, the core center has a higher moisture content than the core surface.

6. The golf ball of claim 1 , wherein the rubber composition contains from 0.1 to 5 parts by weight of an organosulfur compound per 100 parts by weight of the base rubber.

7. The golf ball of claim 1 , wherein the core of the golf ball after the cover has been molded has an initial velocity V 0 , as measured after peeling away the cover, which is at least 77.0 m/s and not more than 78.5 m/s.

8. The golf ball of claim 1 , wherein the JIS-C hardness difference obtained by subtracting the core center hardness from the core surface hardness is at least 20 and not more than 40.

9. The golf ball of claim 1 , wherein the base rubber serving as component (A) is a polybutadiene synthesized using a rare-earth catalyst or a group VIII metal compound catalyst.

10. The golf ball of claim 1 , wherein the tan δ 1 at the core surface is larger than the tan δ 1 at the core center.

11. The golf ball of claim 1 , wherein the tan δ 10 at the core surface is larger than the tan δ 10 at the core center.

12. The golf ball of claim 1 , wherein the core is a single layer and the diameter of the core is at least 32 mm.

Assignees

• Bridgestone Sports Co Ltd

Inventors

• Nakajima Tsuyoshi
• Ozawa Yuichiro

Classifications

• A63B37/0063

  Hardness gradient · CPC title

• A63B37/0094

  Rebound resilience · CPC title

• A63B37/0096

  Spin rate · CPC title

• C08K5/14

  Peroxides · CPC title

• C08K5/00

  Use of organic ingredients · CPC title