Tire Tread Composition Using Unsaturated Styrenic Elastomer
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Solution Overview
Problem
Tire treads experience mechanical stresses that lead to incipient cracks, which propagate and reduce tread life, and existing solutions do not adequately address the need for improved crack resistance without compromising other performance metrics like wear and rolling resistance.
Innovation Solution
A tire tread composition incorporating a polyisoprene-based elastomeric matrix with an unsaturated styrenic thermoplastic elastomer, a reinforcing filler, and a crosslinking system, where the unsaturated styrenic thermoplastic elastomer constitutes 5-50% of the matrix, enhancing crack resistance without deteriorating other performance aspects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If natural rubber is used in treads to improve crack propagation resistance, then crack propagation resistance is improved, but other tread performance aspects such as wear and rolling resistance may deteriorate
Solution Approach 1:
The patent applies composite materials by combining natural rubber with unsaturated styrenic thermoplastic elastomer (specifically SIS triblock copolymer) in a defined ratio (60-90 parts natural rubber to 10-40 parts thermoplastic elastomer). This composite composition achieves superior crack propagation resistance while maintaining acceptable wear and rolling resistance properties, resolving the contradiction between reliability and performance by creating a synergistic material system where each component contributes its strengths.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the composition ratios of the elastomeric matrix components, the glass transition temperature of the flexible segment (-50°C to -20°C), and the content of unsaturated styrenic thermoplastic elastomer (5-50% by mass). These parameter optimizations enable the tread to achieve enhanced crack propagation resistance while maintaining balanced wear and rolling resistance performance.
2Reliability
If the content of unsaturated styrenic thermoplastic elastomer is increased to improve crack propagation resistance, then crack propagation resistance is improved, but the structural integrity and other performance aspects may worsen
Solution Approach 1:
The patent applies parameter changes by establishing precise compositional boundaries (60-90 parts natural rubber to 10-40 parts thermoplastic elastomer) and controlling the glass transition temperature of the flexible segment within -50°C to -20°C. These parameter optimizations ensure that the unsaturated styrenic thermoplastic elastomer content is sufficient to improve crack propagation resistance while maintaining the structural integrity and overall strength of the tread.
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 significantly improves crack propagation resistance, as demonstrated by reduced crack propagation rates, thereby extending tire service life and maintaining performance across various temperatures.
Implementation Method 1
which the at least one flexible isoprene segment has a glass transition temperature below -20°C
Data Source
AI summary
A tire tread comprises a composition based on at least an elastomer matrix comprising a polyisoprene and an unsaturated thermoplastic styrene elastomer which represents at most 50% by weight of the elastomer matrix, a reinforcing filler and a crosslinking system. The unsaturated thermoplastic styrene elastomer comprises at least one rigid styrene segment and at least one flexible isoprene segment, which at least one flexible isoprene segment has a glass transition temperature of less than −20° C. Such a tread exhibits an improved resistance to crack propagation.