Golf Ball Core Crosslinking Gradient for Slow Swing Speed
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Solution Overview
Problem
Golf balls with slow head speed golfer's struggle with poor shot feeling and limited flight distance due to the inability to compress hard balls effectively, leading to increased spin rates and reduced distance.
Innovation Solution
A golf ball design featuring a spherical core with a core rubber composition containing high-cis polybutadiene, α,β-unsaturated carboxylic acid, and a crosslinking initiator, along with a crosslinking density difference and hardness gradient, paired with multiple cover layers to enhance durability and shot feeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a hard golf ball is used, then flight distance increases for fast head speed golfers, but shot feeling deteriorates and compression becomes insufficient for slow head speed golfers
Solution Approach 1:
The core is designed with non-uniform crosslinking density, where the center region has lower crosslinking density (softer) and the outer region has higher crosslinking density (harder). This local differentiation allows the core to provide both compression for distance and support for shot feeling simultaneously.
Solution Approach 2:
The patent controls the crosslinking density parameter through specific formulation (base rubber, unsaturated carboxylic acid, metal salt, peroxide) and processing conditions to achieve a hardness difference of 10-30 JIS-C between center and outer regions, optimizing both compression characteristics and structural integrity.
2Strength
If the core hardness is increased to improve durability, then structural strength improves, but compression deformation capability decreases for slow head speed golfers
Solution Approach 1:
The core structure features a soft center region (lower crosslinking density) that enables compression deformation for energy storage, surrounded by a harder outer region (higher crosslinking density) that provides structural strength and durability.
Solution Approach 2:
The core uses a composite rubber composition combining base rubber with unsaturated carboxylic acid and metal salt crosslinking agents, creating a material with spatially varying properties that balances softness for compression and hardness for durability.
3Ease of manufacture
If uniform crosslinking density is used throughout the core, then manufacturing simplicity is maintained, but shot feeling and spin control become insufficient
Solution Approach 1:
The patent achieves controlled crosslinking density gradient through formulation parameters (unsaturated carboxylic acid content: 5-50 parts, metal salt: 1-20 parts, peroxide: 0.1-5 parts per 100 parts base rubber) and curing conditions, balancing manufacturing feasibility with performance requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The golf ball achieves excellent durability and increased flight distance while providing a good shot feeling for golfers with slow head speeds by optimizing core and cover layer composition.
Implementation Method 1
a core rubber composition containing (a) a base rubber, (b) an α,β-unsaturated carboxylic acid and/or a metal salt thereof as a co-crosslinking agent, and (c) a crosslinking initiator
Implementation Method 2
an elastic portion formed from a rubber composition containing a base rubber
Data Source
AI summary
An object of the present disclosure is to provide a golf ball having excellent durability and flight distance and good shot feeling for an average golfer who hits a golf ball at a slow head speed. The present disclosure provides a golf ball comprising a spherical core and at least two cover layers covering the spherical core, wherein a difference between a core surface crosslinking density and a core center crosslinking density is more than 1.0×102 mol/m3 and less than 9.0×102 mol/m3, a hardness difference between a core surface hardness Cs (Shore C hardness) and a core center hardness Co (Shore C hardness) is 13.0 or more and 30.0 or less, a compression deformation amount of the core when applying a load from an initial load of 98 N to a final load of 1275 N to the core is 3.8 mm or more, and the at least two cover layers include a first cover layer and a second cover layer positioned closer to the spherical core than the first cover layer, an average hardness Dave=(Ti×Hi+To×Ho)/(Ti+To) of the first cover layer and the second cover layer is 55 or more, where To (mm) is a thickness of the first cover layer, Ho (Shore D) is a slab hardness of the first cover layer, Ti (mm) is a thickness of the second cover layer, and Hi (Shore D) is a slab hardness of the second cover layer.