Golf Ball Dual Core Hardness Gradient Design

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Solution Overview

Problem

Conventional golf ball cores, particularly those with thermoset materials, have limitations in achieving varied properties across the core due to their inherent characteristics, such as thermoset polymers' inability to be reprocessed and the difficulty in creating gradients like 'soft-to-hard' or 'hard-to-soft' hardness, which restricts customization of compression, feel, and spin.

Innovation Solution

A golf ball design featuring a thermoplastic inner core layer with a negative hardness gradient and a thermoset outer core layer with a positive hardness gradient, utilizing materials like ionomers, diene rubber, and gradient-promoting additives to achieve specific hardness values and gradients, allowing for customizable properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermoset materials are used for golf ball cores, then the core achieves structural stability and durability, but the ability to create varied hardness gradients and reprocess the material is lost

Engineering Contradiction:

Improvecore structural stabilityVSAvoidhardness gradient customization

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The core is divided into multiple layers with different material compositions and hardness characteristics. The inner core layer uses thermoplastic material while the outer core layer uses thermoset material, allowing each layer to contribute different properties to the overall core performance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the core are assigned different material properties to achieve specific performance characteristics. The inner core has a negative hardness gradient while the outer core has a positive hardness gradient, creating localized property variations that address different functional requirements

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If a single-material core is used, then manufacturing is simpler, but the ability to achieve varied compression and spin characteristics is limited

Engineering Contradiction:

Improvecore manufacturing simplicityVSAvoidcompression and spin customization

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The core is constructed as a composite structure combining thermoplastic and thermoset materials in distinct layers. This composite approach enables tailored compression and spin characteristics while maintaining manufacturing feasibility through established multi-layer molding techniques

Inventive Principle:

Principle #40Composite materials

3Productivity

If thermoset materials are cured with standard cycles, then production efficiency is maintained, but precise control over hardness distribution is difficult

Engineering Contradiction:

Improveproduction efficiencyVSAvoidhardness distribution control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The curing process parameters are specifically optimized to achieve the desired hardness gradients in each layer. By controlling temperature, time, and pressure parameters during curing, the patent achieves precise hardness distribution while maintaining efficient production cycles

Inventive Principle:

Principle #35Parameter changes

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 design enables the creation of golf balls with tailored compression, feel, and spin characteristics by manipulating the hardness gradients, enhancing performance and user experience.

Implementation Method 1

dual cores having a surface hardness greater than the center hardness to define a 'positive' hardness gradient

Methodology Applied

Scientific EffectHardness gradient:

Implementation Method 2

inner core layer consisting essentially of a thermoplastic material and having a geometric center hardness greater than a surface hardness to define a negative hardness gradient

Methodology Applied

Scientific EffectThermoplastic material properties:

Implementation Method 3

outer core layer... formed from a substantially homogenous thermoset composition and having an inner surface hardness substantially less than an outer surface hardness to define a positive hardness gradient

Methodology Applied

Scientific EffectThermoset material properties:

Data Source

PatentUS9999809B2Dual core having thermoplastic inner core, thermoset outer core layer, and positive hardness gradient

Publication Date: 2018.06.19 ACUSHNET CO

AI summary

A golf ball includes a thermoplastic HNP inner core layer having a center hardness less than the surface hardness to define a positive hardness gradient. An outer core layer is formed from a thermoset rubber composition. The core layer has an inner surface hardness less than the outer surface hardness to define a positive hardness gradient of 3 to 30 Shore D. Inner and outer cover layers are disposed about the outer core layer. The HNP composition includes an acid copolymer of ethylene and an α,β-unsaturated carboxylic acid; a non-acid polymer comprising polyolefins, polyamides, polyesters, polyethers, polyurethanes, metallocene-catalyzed polymers, single-site catalyst polymerized polymers, ethylene propylene rubber, ethylene propylene diene rubber, styrenic block copolymer rubbers, alkyl acrylate rubbers, or functionalized derivatives thereof; an organic acid or salt thereof; and a cation source in an amount sufficient to neutralize at least about 80% of the acid groups.