All-Season Tire Tread Compound with Multi-Tg Elastomer Blend

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Solution Overview

Problem

Current all-season tire treads face challenges in achieving balanced performance across various weather conditions and road surfaces, struggling to maintain grip on snow while ensuring high wet grip and reduced wear.

Innovation Solution

The development of an elastomeric composition for tire compounds, comprising a specific blend of isoprene rubber and styrene-butadiene rubbers with tailored glass transition temperatures, along with reinforcing fillers and vulcanizing agents, results in a unique hysteresis pattern with two distinct peaks. This composition enhances snow grip, wet grip, and wear resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the glass transition temperature (Tg) of the tread compound is lowered by adding low Tg elastomeric polymers, then wear resistance and snow grip are improved, but wet grip performance deteriorates

Engineering Contradiction:
Improvewear resistanceVSAvoidwet grip performance
Core Design Contradiction:
ReliabilityVSReliability

Solution Approach 1:

The patent divides the single Tg compound into a blend of multiple elastomeric polymers with distinct Tg values. Specifically, it combines a first elastomeric polymer (Tg: -70°C to -50°C) contributing to wear resistance, a second elastomeric polymer (Tg: -40°C to -20°C) contributing to wet grip, and a third elastomeric polymer (Tg: -65°C to -45°C) contributing to snow grip. This segmentation allows each polymer to independently contribute its strengths without compromising other performance aspects.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the Tg parameter distribution from a single value to a multi-value system. By carefully selecting and combining polymers with specific Tg ranges, the compound achieves a broader effective temperature range for different road conditions. The specific Tg values are optimized to ensure peak performance at different temperatures: lower Tg for wear and snow, higher Tg for wet grip.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If plasticisers are added in high amounts to reduce Tg, then snow grip is improved, but wear resistance deteriorates

Engineering Contradiction:
Improvesnow gripVSAvoidwear resistance
Core Design Contradiction:
ReliabilityVSReliability

Solution Approach 1:

Instead of using high amounts of plasticisers to lower Tg, the patent changes the approach by incorporating a third elastomeric polymer with intermediate Tg (-65°C to -45°C) that naturally provides low-temperature flexibility without the detrimental effects of excessive plasticiser content. This maintains the polymer matrix integrity and wear resistance while achieving the desired low-temperature 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 proposed elastomeric composition achieves improved performance in terms of snow grip, wet grip, and wear resistance, providing a balanced solution for all-season tire treads that outperforms conventional compounds.

Implementation Method 1

the glass transition temperature (Tg) of the tread compound is lowered... elastomeric polymers having low Tg, such as polybutadiene rubber (BR) (Tg around -110 °C), natural rubber (NR) (Tg around -65 °C)... a first elastomeric polymer having a Tg of between -70 °C and -50 °C, a second elastomeric polymer having a Tg of between -40°C and -20°C, and a third elastomeric polymer having a Tg of between -65°C and -45°C

Methodology Applied
Scientific EffectGlass transition: Phase Change

Data Source

PatentEP4263698B1Compounds for treads and tyres comprising them
Publication Date: 2025.02.05 PIRELLI TYRE SPA
  • EP4263698B1 patent drawingFigure 1
  • EP4263698B1 patent drawingFigure 2
  • EP4263698B1 patent drawingFigure 3A~3B

AI summary

The present invention relates to elastomeric compositions and compounds for tyres, in particular for tyre treads, comprising elastomeric polymers in specific ratios and having particular Tg values, tyre components and tyres for vehicle wheels which comprise them. These compounds find particular application in all-season tyres as they give them good manoeuvrability on snow, grip in the wet and advantageously limited wear of the tread.