Golf Ball Core Hardness Gradient for Low Spin Driver Shots
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Solution Overview
Problem
Current golf ball designs fail to achieve a balance between high flight distance and low spin rate on driver shots, as they either prioritize initial speed or launch angle over spin rate, leading to suboptimal performance.
Innovation Solution
A golf ball with a spherical core formed from a rubber composition containing a base rubber, α,β-unsaturated carboxylic acid, a crosslinking initiator, and thiobenzoic acids or their salts, which creates a hardness gradient that increases from the center to the surface, reducing spin rate and enhancing flight distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a core with high resilience is used to enhance initial speed, then the initial speed is improved, but the spin rate increases and flight distance is reduced
Solution Approach 1:
The core is designed with non-uniform hardness distribution where the surface hardness is higher than the center hardness. This local quality variation allows the surface to provide higher friction for spin control while the softer center maintains resilience for initial speed, resolving the contradiction between initial speed and spin rate
Solution Approach 2:
The hardness parameter of the core is varied spatially, with the surface hardness set to 70-85 and center hardness to 40-60 (JIS-C scale). This parameter change creates an outer-hard inner-soft structure that simultaneously achieves low spin rate and high initial speed, resolving the technical contradiction
2Object-generated harmful factors
If a core with hardness increasing toward the surface is used to reduce spin rate, then the spin rate is reduced and flight distance is improved, but the initial speed may be compromised
Solution Approach 1:
The core employs local quality differentiation with the surface region having higher hardness (70-85) for spin reduction and the center region having lower hardness (40-60) for maintaining resilience and initial speed. This resolves the contradiction between spin rate reduction and initial speed preservation
Solution Approach 2:
The core is formed as a composite structure with varying material properties - an outer hard layer and an inner soft core. This composite approach allows different regions to fulfill different functions: the hard outer layer reduces spin while the soft inner core maintains resilience for initial speed
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 a great flight distance on driver shots with a low spin rate, attributed to the specific hardness distribution and chemical composition of the core, resulting in improved shot performance.
Implementation Method 1
a 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, (c) a crosslinking initiator
Implementation Method 2
at least one compound of thiobenzoic acids and/or salts thereof
Data Source
AI summary
An object of the present invention is to provide a golf ball showing a great flight distance on driver shots. The present invention provides a golf ball comprising a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (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 at least one compound of (d) thiobenzoic acids and/or salts thereof, provided that the rubber composition further contains (e) a metal compound in case of containing only (b) the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent, and the spherical core has a hardness difference (Hs−Ho) between a surface hardness (Hs) and a center hardness (Ho) thereof of 25 or more in JIS-C hardness.