Low Melt Flow Thermoplastic Golf Ball Core
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Solution Overview
Problem
Conventional golf ball manufacturing faces challenges in molding high-temperature thermoset materials over soft layers due to the flow-out or 'leakage' of ionomeric materials, which is exacerbated by their low heat resistance and high melt flow properties, leading to inconsistencies and durability issues in multi-layer core constructions.
Innovation Solution
The use of a thermoplastic ionomeric composition with high neutralization levels (70 wt % or greater) that has a low melt flow index and improved heat resistance, reducing the likelihood of flow-out during the molding process by modifying the ionomeric resin or applying post-mold treatments to enhance its heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional ionomeric materials are used in multi-layer core construction, then the materials are easily moldable due to low melting temperatures, but the ionomers flow out or leak through the thermosetting layer during overmolding due to low heat resistance
Solution Approach 1:
The patent applies parameter changes by modifying the ionomeric resin through high levels of neutralization (70 wt% or greater) to fundamentally alter its thermal properties. This chemical modification increases the melting temperature and heat resistance of the ionomer, allowing it to withstand the elevated temperatures required for overmolding thermoset layers without flowing out or leaking, thus resolving the contradiction between ease of manufacture and heat resistance
Solution Approach 2:
The patent creates a composite material system by combining the modified high-neutralization ionomeric resin with thermosetting rubber layers. The ionomeric layer serves as an intermediate core layer that maintains structural integrity when overmolded with thermoset materials, creating a multi-layer composite golf ball core that achieves both moldability and heat resistance through the synergistic combination of materials
2Reliability
If highly-neutralized ionomers (>70 wt% neutralization) are used, then heat resistance is improved, but molding becomes difficult without addition of high levels of metal cation-fatty acid flow modifiers
Solution Approach 1:
The patent applies parameter changes by optimizing the neutralization level to 70 wt% or greater, which fundamentally changes the thermal and rheological properties of the ionomer. This parameter modification allows the material to achieve sufficient heat resistance while maintaining adequate moldability through controlled flow characteristics, eliminating the need for high levels of flow modifiers
3Ease of manufacture
If conventional low-neutralization ionomers (19-69 wt%) are used, then molding is easy at lower temperatures, but flow-out or leakage occurs during overmolding due to low melt flow control at elevated temperatures
Solution Approach 1:
The patent applies parameter changes by increasing the neutralization level from conventional ranges (19-69 wt%) to 70 wt% or greater, which fundamentally alters the melt flow characteristics and heat resistance of the ionomer. This parameter modification enables the material to maintain controlled flow at elevated temperatures during overmolding, preventing flow-out or leakage while preserving ease of manufacture through adequate moldability
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
This approach significantly reduces 'leakage' and enhances the consistency and durability of golf balls by maintaining the structural integrity of the multi-layer core, improving the aerodynamic properties and resistance to breakage upon impact.
Implementation Method 1
The thermoplastic intermediate core layers attempt to make use of materials having very low flow at elevated temperatures and/or high resistance to heat
Implementation Method 2
Methods have been developed to compression or injection mold ionomers into golf ball layers—such methods involve heating the materials to soften and melt them thereby promoting flow to form the desired layers
Implementation Method 3
heating the materials to soften and melt them thereby promoting flow to form the desired layers
Data Source
AI summary
A golf ball including an inner core layer formed from a first thermoset rubber composition and having a diameter of about 1.25 to 1.58 inches; an outer core layer formed from a second thermoset rubber composition; and an intermediate core layer disposed between the inner core layer and outer core layer. The intermediate core layer is formed from a thermoplastic composition having a first melt flow index at 280° C. under a 10-kg load of less than about 35 g/10 min and has a thickness of about 0.005 inches to 0.10 inches and a surface hardness of greater than about 60 Shore D. A cover layer having a thickness of about 0.01 to 0.05 inches and a surface hardness of about 60 Shore D or less is formed around the core.