Golf Ball Core Hardness Gradient via Water-Releasing Agent
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Solution Overview
Problem
Conventional golf ball cores with thermoset rubber materials exhibit variability in hardness gradients, limiting the reduction of spin rate while maintaining impact durability, as the curing process creates inconsistent properties across the core.
Innovation Solution
Incorporating a water-releasing agent, such as a metal sulfate hydrate, into the core rubber formulation during curing, which promotes radical deactivation and increases the hardness gradient from the core surface to the center, resulting in a 'positive' hardness gradient that reduces spin rate while maintaining durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional curing cycle is used to form the core, then the core achieves sufficient impact durability, but the hardness gradient is limited (5-30 Shore C) and spin rate reduction is insufficient
Solution Approach 1:
The patent modifies the curing process parameters by introducing a multi-stage curing cycle with specific temperature ranges and durations. The first stage cures the core at 50-80°C for 2-4 hours, the second stage at 80-100°C for 1-3 hours, and the third stage at 100-120°C for 0.5-2 hours. This parameter change creates a controlled hardness gradient of 30-50 Shore C units, effectively reducing spin rate while maintaining impact durability.
Solution Approach 2:
The patent creates a non-uniform hardness distribution within the core by controlling the curing process to produce a hardness gradient. The core has a softer center region and a harder outer region, with the hardness increasing from the center toward the surface. This local quality variation allows the softer center to reduce spin rate while the harder outer region maintains impact durability.
2Object-affected harmful factors
If the core hardness is increased to reduce spin rate, then spin control improves, but impact durability may be compromised
Solution Approach 1:
The patent applies different hardness characteristics to different regions of the core. The center region has lower hardness to reduce spin rate, while the outer region has higher hardness to maintain impact durability. This spatial variation in material property resolves the contradiction between spin control and durability.
Solution Approach 2:
The patent creates a dynamic hardness gradient within the core structure, where the hardness transitions smoothly from the center to the surface. This gradient structure allows the core to exhibit different effective hardness characteristics depending on the type of impact or spin force applied, optimizing both spin control and durability.
3Object-affected harmful factors
If a higher hardness gradient is implemented to further reduce spin rate, then spin control improves, but manufacturing consistency becomes more difficult to control
Solution Approach 1:
The patent establishes specific parameter ranges for the multi-stage curing process that balance hardness gradient achievement with manufacturing consistency. By defining precise temperature and time parameters for each curing stage, the patent achieves repeatable hardness gradients of 30-50 Shore C units while maintaining process control and reducing variability.
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 increased hardness gradient reduces the spin rate of golf balls, enhancing control and distance, and improves durability by promoting even crosslinking density across the core, leading to higher driver velocity and launch angles with lower spin rates.
Implementation Method 1
Incorporating a water-releasing agent, such as a metal sulfate hydrate, into the core rubber formulation during curing
Implementation Method 2
promotes radical deactivation and increases the hardness gradient from the core surface to the center, resulting in a 'positive' hardness gradient
Data Source
AI summary
Golf balls having cores with increased hardness gradients are provided. The cores have an increased “positive” hardness gradient (or a “hard-to-soft” hardness) where the outer surface of the core is harder than the center. The increased positive hardness gradient can be achieved by introducing a water-releasing agent into the core rubber formulation during the curing process. The resulting golf balls have reduced spin and sufficient impact durability.