US 5,772,531 · Granted 1998-06-30
The Three-Layer Golf Ball That Changed Ball Construction
A golf ball isn't just a rubber sphere—it's engineered like a jawbreaker candy with three distinct layers inside. This patent locks down the recipe for a solid core where each layer has a different hardness, making the ball fly farther and perform better on the course.
The plain-English version
What it protects
The claim covers a solid golf ball with a three-layer core design: an inner layer, a middle layer tuned to a specific hardness range (50-80 on the JIS-C scale), and an outer layer that's deliberately harder than the middle. What's protected here is the combination of these three layers working together with that precise hardness relationship—anyone manufacturing a solid golf ball with this exact layering and hardness profile would be infringing.
Why it matters
In the 1990s, golf ball technology was a major competitive battleground. Manufacturers realized that by controlling how soft or hard each internal layer was, they could engineer spin rates, compression, and distance in ways a uniform solid ball never could. This patent represents Kasco Corporation's approach to that problem: a carefully tuned multi-layer architecture that became part of the standard playbook for modern golf ball design.
Real-world use
Every time a golfer hits a premium solid ball off the tee, the three-layer core inside is absorbing and transferring energy according to this patented design, influencing how far it flies and how it behaves around the green.
Original USPTO abstract
Disclosed is a solid golf ball comprising a solid core having a three-layered structure composed of an inner layer, an intermediate layer, and an outer layer, and a cover for coating the solid core. The intermediate layer is designed to have a JIS-C hardness of 50 to 80, and the outer layer is designed to have a hardness which is higher than the hardness of the intermediate layer.
Patent details
- Publication number
- US 5,772,531
- Filing date
- 1997-03-07
- Grant date
- 1998-06-30
- Assignee
- Kasco Corporation
- Inventor(s)
- OHSUMI; SHUNJI, KAWABATA; HIROSHI, BABA; KENJI, FUKUI; YASUHIRO, NAITO; HIROYUKI, IZAWA; TARO
- CPC class
- A63B37/0003
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