Golf Ball Core Hardness Gradient via Para-Monophenol Control
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Solution Overview
Problem
Golf balls with high resilience cores result in poor shot feeling on driver shots due to their hardness, which compromises the overall performance.
Innovation Solution
A golf ball core composition incorporating a base rubber, an α,β-unsaturated carboxylic acid or its metal salt as a co-crosslinking agent, a crosslinking initiator, and a monophenol compound with a substituent group only at the p-position, which stabilizes radicals and controls hardness distribution, creating an outer-hard and inner-soft structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the core resilience is increased to improve flight distance, then the core hardness increases, but the shot feeling on driver shots deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform hardness distribution within the core. The core has higher hardness at the outer region (near the cover) and lower hardness at the inner region (center), achieved through controlled crosslinking density. This gradient structure allows the outer hard region to provide resilience for flight distance while the inner soft region provides comfort for shot feeling, thus resolving the contradiction between these two requirements.
2Strength
If the core hardness is increased to improve resilience, then the flight distance improves, but the shot feeling on driver shots becomes poor
Solution Approach 1:
The patent implements local quality by establishing a spatial gradient in core hardness. The outer region near the cover has higher crosslinking density and hardness, providing the resilience needed for flight distance. The inner center region has lower crosslinking density and hardness, providing the comfort needed for shot feeling. This localized differentiation of material properties resolves the contradiction between strength and ease of operation.
3Strength
If a monophenol compound with substituent groups at o-position and/or m-position is used, then the core hardness decreases, but the hardness distribution becomes non-constant near the core surface
Solution Approach 1:
The patent applies parameter changes by carefully selecting the chemical structure of the monophenol compound used as a polymerization inhibitor. Specifically, it uses monophenol compounds that have substituent groups ONLY at the p-position (para-position) of the phenolic hydroxyl group, and have NO substituent groups at the o-position (ortho-position) and m-position (meta-position). This specific structural parameter control ensures that the radical scavenging effect is optimized to maintain constant hardness near the core surface while achieving the desired overall hardness reduction.
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 solution enables a golf ball that achieves a great flight distance while maintaining excellent shot feeling on driver shots by ensuring constant hardness near the core surface and a balanced hardness distribution.
Implementation Method 1
the monophenol compound having a substituent group only at p-position used in the present invention expresses an effect of functioning as a polymerization inhibitor or radical scavenger
Implementation Method 2
the radical generated by the cleavage of (c) the crosslinking initiator extracts hydrogen from (a) the base rubber to generate the graft starting point for (b) the co-crosslinking agent, and polymerizing and crosslinking start from the graft starting point
Data Source
AI summary
An object of the present invention is to provide a golf ball having excellent shot feeling while maintaining the resilience performance on driver shots. The present invention provides a golf ball comprising a core and at least one cover covering the core, wherein the core is formed from a core rubber composition containing (a) a base rubber, (b) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, and (d) a monophenol compound having a substituent group only at p-position.