# US 11,298,592 B2 · Multi-piece solid golf ball

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- Number: US 11,298,592 B2
- Document ID: US11298592B2
- Status: Granted
- Kind: B2
- Application number: 17/174,410
- Filed: 2021-02-12
- Published: 2021-06-03
- Granted: 2022-04-12
- Earliest claimed: 2019-05-09
- Assignees: Bridgestone Sports Co., Ltd.
- Applicants: Bridgestone Sports Co., Ltd.
- Inventors: Hideo Watanabe
- Web page: https://patentgrep.com/patent/US11298592B2

## CPC

- A63B 37/0076: {Multi-piece balls, i.e. having two or more intermediate layers}
- A63B 37/0007: {Non-circular dimples}
- A63B 37/0018: {Specified number of dimples}
- A63B 37/0021: {Occupation ratio, i.e. percentage surface occupied by dimples}
- A63B 37/0022: {Coatings, e.g. paint films; Markings}
- A63B 37/00222: {Physical properties, e.g. hardness}
- A63B 37/0031: {Hardness}
- A63B 37/0039: {characterised by the material}
- A63B 37/0044: {Hardness gradient}
- A63B 37/0063: {Hardness gradient}
- A63B 37/009: {Coefficient of lift}
- A63B 37/0092: {Hardness distribution amongst different ball layers}
- A63B 37/00921: {whereby hardness of the cover is higher than hardness of the intermediate layers}
- A63B 37/0096: {Spin rate}
- A63B 37/00621: {Centre hardness}
- A63B 37/00622: {Surface hardness}
- A63B 37/0065: {Deflection or compression}
- A63B 37/0087: {Deflection or compression}
- A63B: APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT (apparatus for passive exercising, massage A61H)

## Abstract

In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, the envelope layer is formed into two layers—an inner envelope layer and an outer envelope layer. The inner envelope layer-encased sphere, outer envelope layer-encased sphere, intermediate layer-encased sphere and ball have respective surface hardness that satisfy a specific relationship. The inner envelope layer or outer envelope layer is formed primarily of one or more elastomer, and further the core has a particular hardness profile. This ball has an excellent flight when struck by golfers whose head speeds are not that fast and has a good, soft feel at impact, thus making it highly suitable for amateur golfers.

## Claims

### Claim 1

A multi-piece solid golf ball comprising a core, an envelope layer, an intermediate layer and a cover, wherein the envelope layer is formed into two layers—an inner envelope layer and an outer envelope layer; the sphere obtained by encasing the core with the inner envelope layer (inner envelope layer-encased sphere), the sphere obtained by encasing the inner envelope layer-encased sphere with the outer envelope layer (outer envelope layer-encased sphere), the sphere obtained by encasing the outer envelope layer-encased sphere with the intermediate layer (intermediate layer-encased sphere) and the ball have respective surface hardnesses which together satisfy the following relationship:
surface hardness of inner envelope layer-encased sphere<surface hardness of outer envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere<surface hardness of ball;
and the inner envelope layer or outer envelope layer is formed primarily of an elastomer; and
wherein the core has a hardness profile in which, letting Cc be the Shore C hardness at a center of the core, Cs be the Shore C hardness at a surface of the core, CM be the Shore C hardness at a midpoint M between the center and surface of the core, CM+2.5, CM+5.0 and CM+7.5 be the respective Shore C hardnesses at positions 2.5 mm, 5.0 mm and 7.5 mm from the midpoint M toward the core surface and CM−2.5, CM−5.0 and CM−7.5 be the respective Shore C hardnesses at positions 2.5 mm, 5.0 mm and 7.5 mm from the midpoint M toward the core center, the following surface areas A to F:
surface area A: ½×2.5×(CM−5.0−CM−7.5)
surface area B: ½×2.5×(CM−2.5−CM−5.0)
surface area C: ½×2.5×(CM−CM−2.5)
surface area D: ½×2.5×(CM+2.5−CM)
surface area E: ½×2.5×(CM+5−CM+2.5)
surface area F: ½×2.5×(CM+7.5−CM+5)
satisfy the two conditions
(surface area D+surface area E+surface area F)−(surface area A+surface area B+surface area C)>0, and
(surface area D+surface area E)−(surface area A+surface area B+surface area C)≥0.

### Claim 2 (depends on 1)

The golf ball of claim 1, wherein the inner envelope layer or outer envelope layer is formed primarily of one or more elastomer selected from the group consisting of polyester elastomers, polyamide elastomers, polyurethane elastomers, olefin elastomers and styrene elastomers.

### Claim 3 (depends on 2)

The golf ball of claim 2, wherein the elastomer is a thermoplastic elastomer.

### Claim 4 (depends on 1)

The golf ball of claim 1, wherein both the inner envelope layer and the outer envelope layer are formed primarily of one or more elastomer selected from the group consisting of polyester elastomers, polyamide elastomers, polyurethane elastomers, olefin elastomers and styrene elastomers.

### Claim 5 (depends on 4)

The golf ball of claim 4, wherein the elastomer is a thermoplastic elastomer.

### Claim 6 (depends on 1)

The golf ball of claim 1, wherein surface areas A to F in the core hardness profile satisfy the condition
0.15≤[(surface area D+surface area E+surface area F)−(surface area A+surface area B+surface area C)]/(Cs−Cc)≤0.60.

### Claim 7 (depends on 1)

The golf ball of claim 1, wherein a coating layer is formed on a surface of the cover and, letting the Shore C hardness of the coating layer be Hc, the difference Hc−Cc between Hc and the Shore C hardness Cc at a center of the core is at least −5 and not more than 20.

### Claim 8 (depends on 1)

The golf ball of claim 1, wherein the ball has from 250 to 370 dimples on the surface thereof, the dimples are of three or more dimple shapes, dimple diameter and dimple depth, the dimple coverage SR, defined as the proportion of the spherical surface of the golf ball accounted for by the dimples, is at least 75%, and the ball when struck has a coefficient of lift CL at a Reynolds number of 70,000 and a spin rate of 2,000 rpm which is at least 70% of the coefficient of lift CL at a Reynolds number of 80,000 and a spin rate of 2,000 rpm.

### Claim 9 (depends on 1)

The golf ball of claim 1, wherein the ball has dimples on the surface thereof, the dimples are of non-spherical shape and the ball surface has a land thereon that is surrounded by a plurality of the non-spherical dimples, which land has a shape that includes at least one vertex, is contiguous at substantially a point with each of at least two neighboring lands and has a surface area in the range of 0.05 to 16.0 mm2.