Tread Rubber Compound Using Polylactic Acid Filler
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Solution Overview
Problem
Existing tire tread compounds that improve roadholding often compromise rolling resistance and abrasion resistance, and thermoplastic polymers with high molecular weight or crystallinity pose processing issues and short-term advantages.
Innovation Solution
A rubber compound for tire treads comprising styrene-butadiene rubber, carbon black, and a vulcanization system, with a thermoplastic polymer filler having a specific range of molecular weight and crystallinity, specifically 5 to 30 phr of polylactic acid with a Tg of 50 to 70°C, molecular weight not exceeding 200,000 g/mol, and crystallinity not exceeding 10%, ensuring improved roadholding, rolling resistance, and abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the quantity of silica in the tread compound is increased to improve roadholding on wet surfaces, then roadholding performance is improved, but abrasion resistance deteriorates
Solution Approach 1:
The patent changes the physical and chemical parameters of the filler material by using thermoplastic polymers with specific Tg ranges (50-70°C), molecular weights (not exceeding 200,000 g/mol), and crystallinity (not exceeding 10%). This parameter optimization allows achieving improved roadholding without the negative abrasion resistance effects associated with traditional high-silica compounds
Solution Approach 2:
The patent creates a composite tread compound by combining styrene-butadiene rubber with thermoplastic polymer fillers and carbon black. This composite approach allows the thermoplastic filler to provide roadholding enhancement while the rubber matrix maintains abrasion resistance, avoiding the trade-off present in silica-only formulations
2Reliability
If thermoplastic polymers with high molecular weight are used to improve compound properties, then certain performance characteristics are enhanced, but homogeneous dispersion and processability deteriorate
Solution Approach 1:
The patent optimizes the molecular weight parameter of the thermoplastic polymer to not exceed 200,000 g/mol. This parameter change ensures that the polymer chains are short enough to disperse homogeneously in the rubber matrix during mixing, while still providing the desired performance characteristics. The lower molecular weight also improves processability by reducing viscosity and enhancing mixing efficiency
3Reliability
If thermoplastic polymers with high crystallinity are used to provide initial advantages, then short-term performance is improved, but the advantages are lost after brief period of use due to crystallization process
Solution Approach 1:
The patent sets the crystallinity parameter of the thermoplastic polymer to not exceed 10%. This low crystallinity parameter prevents excessive crystallization during tyre use, ensuring that the performance advantages are maintained over the long term. The low crystallinity also prevents the polymer from becoming too rigid and losing its beneficial effects after brief use
Solution Approach 2:
Instead of using high crystallinity thermoplastic polymers that provide initial advantages but lose them quickly, the patent inverts the approach by using low crystallinity polymers that provide sustained performance over time. This inversion of the crystallinity parameter strategy resolves the contradiction between short-term and long-term performance
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 compound achieves enhanced roadholding, rolling resistance, and abrasion resistance while maintaining processability, with polylactic acid providing necessary rigidity and stability over time, outperforming current technology in tire tread performance.
Implementation Method 1
a styrene-butadiene rubber (SBR), carbon black and a vulcanization system; said compound being characterized in that it comprises a filler comprising 5 to 30 phr of a thermoplastic polymer having a Tg ranging from 50 to 70°C
Implementation Method 2
a vulcanization system; said compound being characterized in that it comprises a filler comprising 5 to 30 phr of a thermoplastic polymer
Data Source
AI summary
A rubber compound for treads comprising a styrene-butadiene rubber (SBR), carbon black and a vulcanization system. The filler comprises 5 to 30 phr of a thermoplastic polymer, preferably polylactic acid, having a Tg ranging from 50 to 70°C, a molecular weight (Mw) not exceeding 200,000 g/mol and a crystallinity not exceeding 0%.