Golf Ball Core Composition for Hardness Gradient Without Cracking
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Solution Overview
Problem
Conventional golf ball cores with thermoset rubber formulations exhibit a hardness gradient that weakens impact durability due to high amounts of free radical initiators and cross-linking co-agents, leading to cracks upon impact.
Innovation Solution
Incorporating a terpene-based resin, ethylene-propylene-diene (EPDM) rubber, and a water releasing agent into the core formulation during curing, creating a positive hardness gradient with the outer surface harder than the center, enhancing durability and resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high amounts of free radical initiators and cross-linking co-agents are used to create a hardness gradient in the core, then the spin rate is reduced, but the impact durability deteriorates due to cracks forming in the core
Solution Approach 1:
The patent changes the chemical composition parameters of the core formulation by incorporating terpene-based resin (5-20 phr), EPDM rubber (5-30 phr), and water releasing agent (1-5 phr) into the traditional polybutadiene base. These parameter changes modify the curing behavior and cross-linking density distribution, enabling a hardness gradient that reduces spin rate while preventing core cracks through improved material toughness and controlled cross-linking.
Solution Approach 2:
The patent creates a composite rubber formulation combining polybutadiene rubber with terpene-based resin, EPDM rubber, and water releasing agent. This composite material system leverages the complementary properties of each component: polybutadiene provides elasticity, terpene resin enhances durability and controls curing, EPDM improves crack resistance, and water releasing agent modulates the curing profile. The composite achieves both spin rate reduction and impact durability enhancement simultaneously.
2Ease of operation
If a hardness gradient is created in the core to reduce spin rate, then ball control is improved, but the core becomes more susceptible to cracking upon impact
Solution Approach 1:
The patent modifies the physical and chemical parameters of the rubber composition by adding specific quantities of terpene-based resin (5-20 phr), EPDM rubber (5-30 phr), and water releasing agent (1-5 phr). These parameter changes result in a controlled hardness gradient that maintains core strength while achieving the desired spin rate reduction, thereby preserving both ball control and core integrity during impact.
Solution Approach 2:
The patent employs a composite material system where EPDM rubber provides crack resistance and toughness, terpene-based resin enhances overall durability, and water releasing agent controls the curing profile. This composite approach allows the core to maintain sufficient strength and elasticity to withstand impact forces while still creating the hardness gradient necessary for spin rate control and player accuracy.
3Ease of operation
If the core is cured with high cross-linking density to increase hardness, then the feel and spin control are improved, but the impact durability decreases due to increased brittleness
Solution Approach 1:
The patent adjusts the cross-linking parameters by incorporating water releasing agent (1-5 phr) that controls the rate and distribution of cross-linking during curing, and terpene-based resin (5-20 phr) that modifies the cross-linking density. These parameter changes create a more uniform and controlled cross-linking process that achieves the desired hardness and feel while preventing excessive brittleness, thereby maintaining impact durability.
Solution Approach 2:
The patent uses a composite formulation where EPDM rubber (5-30 phr) provides flexible cross-linking and crack resistance, terpene-based resin (5-20 phr) enhances durability while controlling cross-linking density, and water releasing agent (1-5 phr) modulates the curing profile. This composite system achieves optimal balance between cross-linking density for feel and spin control, and material toughness for impact durability.
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 combination of these additives improves the durability and reduces spin rate of golf balls by maintaining structural integrity and reducing spin, while maintaining desired hardness characteristics.
Implementation Method 1
a water releasing agent
Implementation Method 2
crosslinked in a variety of processing steps
Implementation Method 3
free radical initiators
Implementation Method 4
cured under heat
Data Source
AI summary
Golf balls having cores with increased hardness gradients and improved impact durability 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 cores are formed from rubber formulations including combinations of a terpene-based resin, ethylene-propylene-diene (EPDM) rubber, and/or a water releasing agent. The resulting golf balls have increased impact durability and resilience.