Base Tread Rubber Composition Using Modulus Ratio Control

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Solution Overview

Problem

Existing rubber compositions for tire base tread struggle to balance steering stability, rolling resistance, and pass-by noise properties, where improving one aspect often deteriorates another.

Innovation Solution

A rubber composition for tire base tread with a storage modulus ratio of 0 °C to 30 °C in the range of 1.3 to 2.0, incorporating natural rubber, fillers, and specific resins, which enhances tanδ at high frequencies to improve pass-by noise while maintaining tire rigidity and steering stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the tanδ of rubber composition is kept low to improve rolling resistance and fuel efficiency, then rolling resistance is reduced, but pass-by noise is increased and steering stability is deteriorated

Engineering Contradiction:
Improverolling resistanceVSAvoidpass-by noise
Core Design Contradiction:
Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by controlling the ratio of storage modulus at 0°C to storage modulus at 30°C within a specific range of 1.05 to 1.30. This parameter control enables the rubber composition to achieve an optimal balance where tanδ at high frequencies is sufficiently high to reduce pass-by noise, while tanδ at low frequencies remains low to maintain rolling resistance performance. The specific parameter range resolves the contradiction by defining precise boundaries that simultaneously satisfy both requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by formulating a rubber composition containing multiple rubber components (natural rubber, styrene-butadiene rubber, butadiene rubber) combined with specific fillers (carbon black, silica) and resins. This composite approach allows the material to exhibit dual characteristics: the natural rubber provides high elasticity and low heat generation for reduced rolling resistance, while the combination with other rubbers and additives increases tanδ at high frequencies to suppress pass-by noise, thus resolving the contradiction through material composition design.

Inventive Principle:
Principle #40Composite materials

2Use of energy by moving object

If the tanδ of rubber composition is kept low to improve fuel efficiency, then fuel efficiency is improved, but steering stability is deteriorated due to lowered rubber rigidity

Engineering Contradiction:
Improvefuel efficiencyVSAvoidsteering stability
Core Design Contradiction:
Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent resolves this contradiction through parameter changes by establishing a specific ratio range (1.05 to 1.30) for storage modulus at different temperatures. This parameter control ensures that the rubber maintains appropriate rigidity characteristics across temperature conditions, providing sufficient steering stability while keeping energy loss low for improved fuel efficiency.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The composite rubber formulation combines natural rubber (providing low hysteresis and good fuel efficiency) with styrene-butadiene rubber and butadiene rubber (providing appropriate rigidity and steering stability). The synergistic effect of this composite material system allows both fuel efficiency and steering stability to be improved simultaneously, overcoming the trade-off between these properties.

Inventive Principle:
Principle #40Composite materials

3Object-generated harmful factors

If the ratio of 0°C E' to 30°C E' is increased to improve pass-by noise properties, then pass-by noise is reduced, but tire rigidity may be affected

Engineering Contradiction:
Improvepass-by noiseVSAvoidtire rigidity
Core Design Contradiction:
Object-generated harmful factorsVSStrength

Solution Approach 1:

The patent applies parameter changes by defining a specific upper bound (1.30) for the storage modulus ratio. This parameter constraint ensures that while tanδ at high frequencies is increased to reduce pass-by noise, the tire rigidity is maintained within acceptable limits. The bounded parameter approach resolves the contradiction by preventing excessive rigidity changes while achieving noise reduction.

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 solution effectively improves steering stability, rolling resistance, and pass-by noise properties when applied to a tire, achieving a well-balanced performance.

Implementation Method 1

a ratio of storage modulus at 0 °C (0 °C E') to storage modulus at 30 °C (30 °C E') (0 °C E'/30 °C E') is in a range of 1.3 to 2.0

Methodology Applied
Scientific EffectViscoelasticity: Viscoelasticity

Data Source

PatentEP4074519B1Base tread rubber composition and tyre
Publication Date: 2023.12.13 BRIDGESTONE CORP

AI summary

Provided is a rubber composition for base tread which can provide excellent steering stability and rolling resistance and improve pass-by noise properties when applied to a tire. The present disclosure discloses a rubber composition for base tread to be used for base tread of a tread portion of a tire, where a ratio of storage modulus at 0 °C (0 °C E') to storage modulus at 30 °C (30 °C E') (0 °C E'/30 °C E') is in a range of 1.3 to 2.0.