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JP-7855902-B2 - Multi-piece solid golf ball

JP7855902B2JP 7855902 B2JP7855902 B2JP 7855902B2JP-7855902-B2

Inventors

  • 渡邊 英郎

Assignees

  • ブリヂストンスポーツ株式会社

Dates

Publication Date
20260511
Application Date
20220404

Claims (8)

  1. A multi-piece solid golf ball comprising a core, a surrounding layer, an intermediate layer, and a cover, wherein the core is formed from a single or multiple layers of rubber composition, and the surrounding layer, intermediate layer, and cover are each formed from a single layer of resin material, and the hardness relationship of each layer is given by the following two formulas: hardness of the cover material > hardness of the intermediate layer, and The material hardness of the surrounding layer ≥ the surface hardness of the core (wherein hardness in the above formula refers to Shore C hardness). In addition to satisfying the following condition, the following formula is also true: thickness of the surrounding layer (mm) × material hardness of the surrounding layer (Shore D hardness) ≥ thickness of the cover (mm) × material hardness of the cover (Shore D hardness) If the following conditions are met, and the deflection amount when the core is subjected to an initial load of 98 N (10 kgf) and a final load of 1,275 N (130 kgf) is C (mm), and the deflection amount when the ball is subjected to an initial load of 98 N (10 kgf) and a final load of 1,275 N (130 kgf) is B (mm), then the value of C - B is 1.00 mm or more, and furthermore, if the value of [Core volume (mm³ ) × (Shore C hardness of core surface + Shore C hardness of core center) / 2] is Core・vh, the value of [Volume of surrounding layer material (mm³ ) × Shore C hardness of surrounding layer material] is E・vh, and the value of [Volume of intermediate layer material (mm³ ) × Shore C hardness of intermediate layer material] is I・vh, then the following formula 1.10≦(E・vh + I・vh)/Core・vh ≦1.46 A multi-piece solid golf ball characterized by satisfying the following conditions.
  2. Furthermore, the following formula holds true: Thickness of the surrounding layer (mm) × Material hardness of the surrounding layer (Shore D hardness) ≥ Thickness of the intermediate layer (mm) × Material hardness of the intermediate layer (Shore D hardness) A multi-piece solid golf ball according to claim 1 that satisfies the requirements.
  3. A multi-piece solid golf ball according to claim 1 or 2, wherein the thickness relationship of each layer satisfies the following formula: (cover thickness + intermediate layer thickness) < surrounding layer thickness.
  4. The hardness relationship between each layer is given by the following formula: Cover material hardness > Intermediate layer material hardness > Enveloping layer material hardness ≥ Core surface hardness (wherein hardness in the above formula refers to Shore C hardness). A multi-piece solid golf ball according to claim 1 or 2 that satisfies the requirements.
  5. The surrounding layer and/or the resin material of the intermediate layer consist of the following components (A) to (D): (a-1) A binary random copolymer of olefin-unsaturated carboxylic acid and/or a metal ion neutralized product of a binary random copolymer of olefin-unsaturated carboxylic acid, (a-2) A ternary random copolymer of olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester and/or a metal ion neutralized product of the ternary random copolymer of olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester, (A) base resin formulated in a mass ratio of 100:0 to 0:100, (B) A resin component blended with a non-ionomer thermoplastic elastomer in a mass ratio of 100:0 to 50:50 for 100 parts by mass, (C) 5 to 120 parts by mass of fatty acids and/or derivatives thereof having a molecular weight of 228 to 1500, The multi-piece solid golf ball according to claim 1 or 2, comprising (D) 0.1 to 17 parts by mass of a basic inorganic metal compound capable of neutralizing unneutralized acid groups in the above-mentioned components (A) and (C) as an essential component, wherein the resin material is highly neutralizing.
  6. The multi-piece solid golf ball according to claim 5, wherein both the surrounding layer and the intermediate layer are made of different types of highly neutralizing resin materials, each containing components (A) to (D) as essential components.
  7. The thickness relationship of each layer is given by the following formula: Encircling layer thickness / (Cover thickness + Intermediate layer thickness) ≥ 1.2 A multi-piece solid golf ball according to claim 1 or 2 that satisfies the requirements.
  8. The relationship between the core diameter and the ball diameter is given by the following formula: 0.65 ≤ (core diameter) / (ball diameter) ≤ 0.78 A multi-piece solid golf ball according to claim 1 or 2 that satisfies the requirements.

Description

This invention relates to a multi-piece solid golf ball comprising four or more layers, including a core, a surrounding layer, an intermediate layer, and a cover. Many innovations have been made in designing golf balls with a multi-layered structure, resulting in the development of numerous balls that satisfy not only professional golfers but also amateur golfers ranging from beginners to advanced players. For example, functional multi-piece solid golf balls with optimized material and surface hardness for each layer—the core, surrounding layer, intermediate layer, and cover (outermost layer)—have become widespread. Furthermore, several technologies have been proposed that focus on the core hardness distribution, which occupies the majority of the ball's volume, and design various configurations of internal core hardness to provide high-performance golf balls. Examples of such technical documents include the following Patent Documents 1 to 13. These golf balls are multi-layered golf balls with four or more layers, and are designed with a focus on distance, where the cover (outermost layer) is harder than the intermediate layers. However, the proposed golf ball still has room for improvement in optimizing the core hardness distribution and the thickness relationship between each layer. Specifically, the proposed golf ball made it difficult for amateur users, especially those with lower swing speeds, to achieve a sufficiently satisfying distance. While the proposed golf ball achieved satisfactory distance with a driver, it did not provide superior distance performance with full iron shots. Therefore, there was still room for improvement in the proposed distance-focused golf ball in terms of pursuing maximum distance with both a driver (W#1) and full iron shots. Japanese Patent Publication No. 2000-061002Japanese Patent Publication No. 2000-061000Japanese Patent Publication No. 2001-218872Japanese Patent Publication No. 2005-218859Japanese Patent Publication No. 2010-253268Japanese Patent Publication No. 2014-132955Japanese Patent Publication No. 2016-016117Japanese Patent Publication No. 2016-179052Japanese Patent Publication No. 2019-198467Japanese Patent Publication No. 2021-087743Japanese Patent Application Publication No. 10-295852Japanese Patent Publication No. 2000-140160Japanese Patent Publication No. 2013-244129 This is a schematic cross-sectional view of the multi-piece solid golf ball (four-layer structure) of the present invention.These are plan views showing the dimple patterns common to each embodiment and comparative example. Figure 2(A) shows a plan view of the dimples as seen from directly above, centered on the pole of the ball, while Figure 2(B) shows a plan view of the dimples as seen from diagonally above, shifted upwards from Figure 2(A). The present invention will be described in more detail below. The multi-piece solid golf ball of the present invention, as shown in Figure 1, is a golf ball G having four or more layers, comprising a core 1, a surrounding layer 2 covering the core, an intermediate layer 3 covering the surrounding layer, and a cover 4 covering the intermediate layer. The surface of the cover 4 typically has numerous dimples D formed thereon. Although not specifically shown, the surface of the cover 4 typically has a coating layer formed by paint. Excluding the coating layer, the cover 4 is the outermost layer in the layer structure of the golf ball. The core 1 is not limited to a single layer but can be formed from two or more layers, while the surrounding layer 2, intermediate layer 3, or cover 4 are formed as single layers. The above core is obtained by vulcanizing a rubber composition primarily composed of rubber material. This rubber composition typically consists mainly of a base rubber, to which co-crosslinking agents, crosslinking initiators, inert fillers, organic sulfur compounds, etc., are blended to obtain the rubber composition. It is preferable to use polybutadiene as the base rubber. Commercially available polybutadienes can be used, such as BR01, BR51, and BR730 (manufactured by JSR Corporation). The proportion of polybutadiene in the base rubber is preferably 60% by mass or more, and more preferably 80% by mass or more. In addition to polybutadiene, other rubber components may be blended into the base rubber within a range that does not impair the effects of the present invention. Examples of rubber components other than polybutadiene include other polybutadienes, other diene rubbers, such as styrene-butadiene rubber, natural rubber, isoprene rubber, and ethylene-propylene-diene rubber. The cocrosslinking agent is an α,β-unsaturated carboxylic acid and/or its metal salt. Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, and fumaric acid, with acrylic acid and methacrylic acid being particularly preferred. The metal salt of the unsaturated carboxylic acid is not particularly limited, but examples include