Liquid Rubber Tennis Ball Adhesive for Durable Core Bonding

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Solution Overview

Problem

Existing solvent-based adhesives for tennis balls have stability issues due to high volatility, environmental concerns, and reduced adhesive strength, leading to durability problems when the ball is repeatedly hit during play.

Innovation Solution

A liquid rubber-based adhesive with a number average molecular weight of not less than 10,000 and shear viscosity of not greater than 2,000 Pa·s is used, eliminating volatile organic solvents and ensuring high adhesive strength and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If solvent-based adhesive is used for adhering half cores, then adhesive strength is improved, but viscosity stability deteriorates due to solvent volatilization

Engineering Contradiction:
Improveadhesive strengthVSAvoidviscosity stability
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent changes the fundamental parameter of the adhesive composition by replacing solvent-based formulations with water-based adhesive comprising rubber latex and filler. This substitution eliminates the volatility issue while maintaining adhesive strength, as the water-based system does not suffer from rapid solvent evaporation that causes viscosity instability in conventional solvent-based adhesives.

Inventive Principle:
Principle #35Parameter changes

2Strength

If solvent-based adhesive is used, then adhesive strength is improved, but environmental harm increases due to volatile organic compounds

Engineering Contradiction:
Improveadhesive strengthVSAvoidenvironmental harm
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent fundamentally changes the chemical composition parameter by adopting water-based adhesive instead of solvent-based adhesive. This eliminates volatile organic compounds from the formulation, thereby removing the environmental harm and health hazards associated with solvent evaporation while preserving the necessary adhesive strength through the rubber latex base.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If rubber latex adhesive is used to reduce organic solvent, then environmental load is reduced, but residual moisture affects adhesive strength

Engineering Contradiction:
Improveenvironmental loadVSAvoidadhesive strength
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent optimizes the water content parameter in the rubber latex adhesive formulation. By controlling the amount and type of water-based components, the patent eliminates excessive residual moisture that would compromise adhesive strength, while maintaining the environmental benefits of using water instead of organic solvents. The specific formulation parameters are adjusted to achieve the right balance between moisture content and adhesive performance.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If liquid rubber with low molecular weight is used, then viscosity for application is improved, but adhesive strength deteriorates

Engineering Contradiction:
Improveviscosity for applicationVSAvoidadhesive strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent identifies and optimizes the molecular weight parameter of the liquid rubber component. By selecting liquid rubber with an appropriate molecular weight range, the patent achieves a balance where the adhesive has sufficiently low viscosity for easy application while maintaining high adhesive strength. The molecular weight is controlled to ensure proper flow characteristics during application without compromising the bonding performance.

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

The adhesive maintains suitable viscosity for application, reduces environmental and worker exposure, and enhances the durability of the tennis ball by providing excellent adhesive strength.

Implementation Method 1

an adhesive whose main component is liquid rubber... by using an adhesive having excellent adhesive strength

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

the adhesive is used for adhering the half cores to each other by vulcanization adhesion

Methodology Applied
Scientific EffectVulcanization: Chemical Bonding

Data Source

PatentEP4119203B1Adhesive for tennis ball
Publication Date: 2025.09.17 SUMITOMO RUBBER INDUSTRIES LTD
  • EP4119203B1 patent drawingFigure 1
  • EP4119203B1 patent drawingFigure 2A~2B

AI summary

An adhesive for a tennis ball includes base rubber. The base rubber contains, as a main component thereof, liquid rubber having a number average molecular weight of not less than 10,000. The adhesive has a shear viscosity of not greater than 2,000 Pa·s. A tennis ball includes a hollow core made of a rubber material. The core includes two hemispherical half cores. The two half cores are adhered to each other by using the adhesive for a tennis ball.