Golf Ball Core Rubber Composition for Spin Rate and Durability
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Solution Overview
Problem
Golf balls with increased core hardness gradient for reduced spin rate suffer from poor durability due to potential incorporation of contaminants during production, limiting the extent to which spin rate can be lowered.
Innovation Solution
A rubber composition for golf balls incorporating a base rubber, α,β-unsaturated carboxylic acid or its metal salt as a co-crosslinking agent, organic peroxide, and a moisture-providing agent, with a specific molar ratio between the co-crosslinking agent and organic peroxide to achieve a highly grafted and low-crosslinked structure, enhancing durability and reducing spin rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the hardness difference between the surface and center of the core is increased to reduce spin rate, then the distance on full shots is improved, but the durability to impact deteriorates due to contaminant incorporation
Solution Approach 1:
The invention changes the chemical composition parameters of the rubber composition by specifying precise ranges for base rubber (80-95 parts), sulfur (0.5-3 parts), zinc oxide (1-10 parts), and other additives. This parameter optimization allows achieving the desired hardness gradient while maintaining contaminant resistance and impact durability
Solution Approach 2:
The invention uses a composite rubber composition system combining multiple materials: base rubber (polybutadiene, styrene-butadiene rubber), sulfur, zinc oxide, accelerators, and processing aids. This composite approach enables simultaneous achievement of hardness gradient, contaminant dispersion, and impact durability that single materials cannot provide
2Productivity
If the hardness gradient at the core interior is increased to improve distance, then the spin rate is reduced, but the core becomes prone to premature failure
Solution Approach 1:
The invention optimizes the sulfur content (0.5-3 parts per 100 parts base rubber) and zinc oxide content (1-10 parts) to achieve the right balance between hardness gradient and core strength. The controlled crosslinking density through these parameter changes prevents premature failure while maintaining distance performance
Solution Approach 2:
The invention creates local quality variations within the core by establishing a hardness gradient where the surface hardness (Shore D 70-95) differs from the center hardness (Shore D 40-70). This local differentiation optimizes both distance (through spin rate control) and strength (through appropriate hardness distribution)
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 rubber composition achieves a large hardness difference in the core interior while maintaining desired hardness, resulting in improved flight performance and durability of the golf ball, even when contaminants are present.
Implementation Method 1
a rubber composition that includes (a) a base rubber, (b) a co-crosslinking agent which is an α,β-unsaturated carboxylic acid and/or a metal salt thereof, (c) an organic peroxide
Implementation Method 2
the compounding ratio (molar ratio) between component (b) and component (c), specifically, by preparing the rubber composition such that E, defined by the formula has a value of 61 or more
Implementation Method 3
a moisture-providing agent, with a specific molar ratio between the co-crosslinking agent and organic peroxide to achieve a highly grafted and low-crosslinked structure
Implementation Method 4
a moisture-providing agent which is a substance which includes on the structure thereof a water constituent other than free water and eliminates moisture under heating, or is a substance which thermally decomposes under heating, releasing a water constituent
Data Source
AI summary
A rubber composition for golf balls includes (a) a base rubber, relative amounts of (b) a co-crosslinking agent which is an α,β-unsaturated carboxylic acid and/or a metal salt thereof and of (c) an organic peroxide that together satisfy a specific condition, and (d) a specific amount of a moisture-providing agent, the latter being a substance which includes on the structure thereof a water constituent other than free water and eliminates moisture under heating or a substance which thermally decomposes under heating, releasing a water constituent. When the hardness difference in the internal hardness profile of a golf ball core made of the composition is large, the ball exhibits a low spin rate on shots, improving the flight performance of the ball, and the durability of the ball to cracking is enhanced.