Drive Wheel TBR Tyre Tread Compound for Low Rolling Resistance

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Solution Overview

Problem

TBR pneumatic tyres for driving wheels face a challenge in improving rolling resistance without compromising wear resistance and service life, as increasing silica in the rubber compound to reduce rolling resistance leads to decreased wear resistance and crack propagation resistance.

Innovation Solution

A tread design with specific slip requirements combined with a compound comprising a cross-linkable unsaturated chain polymer base, styrene-butadiene rubber, silica, and a vulcanization system, optimized to achieve improved rolling resistance without deteriorating wear resistance and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the amount of silica is increased to improve rolling resistance, then rolling resistance is reduced, but wear resistance and crack propagation resistance deteriorate

Engineering Contradiction:
Improverolling resistanceVSAvoidwear resistance
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the rubber compound by introducing specific unsaturated chain polymers (nitrile rubber with 18-35% acrylonitrile, halogenated butadiene rubber with 50-80% 1,4-cis structure) and controlling their molecular weights and unsaturation levels. This allows optimization of both rolling resistance and wear resistance through precise parameter control rather than simply increasing silica content.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite rubber compound system combining multiple polymer types (styrene-butadiene rubber, nitrile rubber, halogenated butadiene rubber) with silica filler and specific vulcanization systems. This composite approach allows the different materials to complement each other's properties, achieving both low rolling resistance and high wear resistance that cannot be obtained with single materials.

Inventive Principle:
Principle #40Composite materials

2Loss of energy

If the amount of silica is increased to improve rolling resistance, then rolling resistance is reduced, but the service life of the pneumatic tyre deteriorates

Engineering Contradiction:
Improverolling resistanceVSAvoidservice life
Core Design Contradiction:
Loss of energyVSDuration of action of moving object

Solution Approach 1:

The patent controls the unsaturation content and molecular weight of the polymer base, and the quantity and type of silica filler, to optimize the balance between rolling resistance and service life. By precise parameter control of the compound composition, the tyre achieves low rolling resistance while maintaining durability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies different compound formulations to different regions of the tread (cap portion and base portion with different thicknesses and compositions), allowing each region to be optimized for its specific functional requirements while contributing to overall tyre performance and service life.

Inventive Principle:
Principle #3Local quality

3Loss of energy

If the amount of silica is increased to improve rolling resistance, then rolling resistance is reduced, but crack propagation resistance deteriorates

Engineering Contradiction:
Improverolling resistanceVSAvoidcrack propagation resistance
Core Design Contradiction:
Loss of energyVSStrength

Solution Approach 1:

The patent introduces halogenated butadiene rubber with high 1,4-cis structure content (50-80%) which provides excellent crack resistance, and controls the unsaturation content of the polymer base (0.5-3.0 mmol/g). These parameter changes enable the compound to resist crack propagation while maintaining low rolling resistance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses specific vulcanization systems including sulfur, metal oxides (zinc oxide, magnesium oxide), and organic peroxides as intermediaries to create strong cross-linking networks between polymer chains and silica particles, enhancing crack propagation resistance without compromising rolling resistance.

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 solution effectively enhances rolling resistance and wet grip while maintaining wear resistance and durability, as demonstrated by comparative testing showing improved performance in rolling resistance and wet grip without adverse effects on wear resistance and durability.

Implementation Method 1

a cross-linkable unsaturated chain polymer base comprising from 40 to 80% by weight of a styrene-butadiene rubber (SBR)... and a vulcanization system

Methodology Applied
Scientific EffectVulcanization: Chemical Bonding

Implementation Method 2

cross-linkable unsaturated chain polymer base

Methodology Applied
Scientific EffectCross-linking: Chemical Bonding

Implementation Method 3

a filler comprising from 40 to 80% by weight of silica

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 4

a tread having a design such as to give an average tread slip of less than 0.5 mm and a slip range for the tread points of between 0.07 mm and 1.17 mm

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3820937B1Truck and bus radial pneumatic tyre of a driving wheel
Publication Date: 2024.08.28 BRIDGESTONE EURO NV SA
  • EP3820937B1 patent drawingFigure 1

AI summary

A TBR pneumatic tyre of a driving wheel comprising a tread having a design such as to confer an average tread slip of less than 0.5 mm and a tread points slip range of between 0.07 mm and 1.17 mm. The tread is manufactured with a compound comprising a cross-linking unsaturated chain polymer base comprising from 40 to 80% by weight of a styrene-butadiene rubber (SBR), a filler comprising from 40 to 80% by weight of silica and a vulcanization system.