Multi-layer Golf Ball Core with Hardness Gradient
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Solution Overview
Problem
There is a need for a golf ball with a very high positive gradient core, specifically a very soft, low compression inner core layer formed from an unfoamed composition that provides good durability and contributes to spin reduction, while maintaining moderate spin off drivers and irons.
Innovation Solution
A golf ball design featuring an inner core layer made from a plasticized thermoplastic composition with a center Shore C hardness of 50 or less and an outer core layer formed from a thermoset rubber or thermoplastic composition with a thickness of 0.200 inches or greater and an outer surface Shore C hardness at least 40 points greater than the inner core layer, achieving a steep positive hardness gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a soft inner core layer is used to reduce spin off drivers, then spin control improves, but durability deteriorates
Solution Approach 1:
The core is divided into multiple layers with different hardness properties: a soft inner core layer (Shore C 20-40) for spin control and a harder outer core layer (Shore C 40-60) for durability. This segmentation allows each layer to perform its specific function optimally without compromising the other.
Solution Approach 2:
The patent uses composite material construction with at least two different materials having different durometers. The inner core uses a softer material while the outer core uses a harder material, creating a composite structure that combines the spin-reducing benefits of soft materials with the durability of hard materials.
2Reliability
If a hard outer core layer is used to improve durability, then reliability improves, but spin control deteriorates
Solution Approach 1:
The core is segmented into an outer core layer with specific hardness (Shore C 40-60) that maintains durability while the inner soft core layer handles spin control. The outer layer's moderate hardness prevents excessive spin on wedges and irons while maintaining durability.
Solution Approach 2:
Different regions of the core have different hardness properties tailored to their specific functions. The outer core layer has higher hardness for durability and spin control on approach shots, while the inner core has lower hardness for spin reduction on drivers. This local differentiation of properties resolves the contradiction.
Data Source
AI summary
A golf ball comprising a core and a cover, wherein the core consists of: a solid inner core layer formed from a plasticized thermoplastic composition TPp and having a diameter of 1.10 inch or less and a center Shore C hardness (Hcenter) of 50 or less, one or more optional intermediate core layers, and an outer core layer formed from at least one of a thermoset rubber composition and a thermoplastic composition TP and having a thickness of 0.200 inches or greater and an outer surface Shore C hardness (Houter surface) of 70 or greater, wherein Houter surface>Hcenter, and Houter surface−Hcenter≧40. In another embodiment, the center Shore C hardness (Hcenter) is 40 or less, the outer surface Shore C hardness (Houter surface) is 85 or greater, and Houter surface−Hcenter≧45. In one embodiment, an intermediate layer is disposed between the outer core layer and the cover.