Polyisoprene Tire Rubber Composition for Reversion Resistance

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Solution Overview

Problem

Natural rubber used in pneumatic tire components undergoes strain-induced crystallization, but it is prone to rubber reversion, leading to a loss of mechanical strength and dynamic modulus.

Innovation Solution

A vulcanizable rubber composition is developed, comprising a polyisoprene elastomer, a sulfur-based curative, zinc oxide, and a eutectic composition, which improves resistance to reversion and increases toughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If natural rubber is used in significant levels in tire components, then strain-induced crystallization improves mechanical strength, but rubber reversion causes loss of mechanical strength and dynamic modulus

Engineering Contradiction:

Improvemechanical strengthVSAvoidresistance to reversion

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the rubber composition by incorporating specific additives (polyethylene glycol, zinc oxide, stearic acid, sulfur) in controlled amounts to modify the vulcanization process and reduce reversion while maintaining strength

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite rubber composition by combining natural rubber with specific chemical additives and vulcanizing agents, forming a multi-component system that achieves both strength and reversion resistance

Inventive Principle:

Principle #40Composite materials

2Strength

If sulfur crosslinks are formed in vulcanized rubber, then mechanical strength is improved, but sulfur crosslink fracturing causes reversion

Engineering Contradiction:

Improvemechanical strengthVSAvoidcrosslink stability

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent modifies the vulcanization parameters by using controlled amounts of sulfur (0.5-3.0 phr) combined with zinc oxide and stearic acid to create more stable crosslinks that resist fracturing

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces zinc oxide and stearic acid as intermediary substances that facilitate the formation of more stable crosslink structures, acting as mediators between the sulfur and rubber polymer chains

Inventive Principle:

Principle #24Intermediary (Mediator)

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 inclusion of a eutectic composition in the polyisoprene-based vulcanizable composition significantly enhances the resistance to reversion and increases the toughness of the rubber, maintaining desirable mechanical properties.

Implementation Method 1

a eutectic composition

Methodology Applied

Scientific EffectEutectic composition:

Implementation Method 2

a sulfur-based curative

Methodology Applied

Scientific EffectSulfur crosslinking: Chemical Bonding

Implementation Method 3

Because natural rubber undergoes strain-induced crystallization

Methodology Applied

Scientific EffectStrain-induced crystallization: Crystallisation

Data Source

PatentUS12264245B2Rubber compositions for pneumatic tires

Publication Date: 2025.04.01 BRIDGESTONE CORP

AI summary

A vulcanizable rubber composition comprising (i) a rubber component including a polyisoprene elastomer, (ii) a sulfur-based curative, (iii) zinc oxide, and (iv) a eutectic composition.