Polyterpene Resin Rubber Composition for Tyre Wet Grip and Rolling Resistance
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Solution Overview
Problem
Current tire tread materials face a trade-off between low rolling resistance and good wet grip properties, with materials optimized for one often compromising the other, and existing solutions either increase rolling resistance or reduce wet traction.
Innovation Solution
A cross-linkable rubber composition comprising styrene-butadiene rubber, polybutadiene rubber, and polyterpene resin, with specific molecular weight and branching indices, that balances wet grip and rolling resistance by incorporating a polyterpene resin with a molecular weight of 900 to 1200 g/mol and a branching index of 0.7 to 0.85, which is more effective with nickel-catalyzed polybutadiene rubber for improved wet grip without significantly increasing rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tread material with high tan δ at 0 °C is used to improve wet grip properties, then wet grip is improved, but rolling resistance increases
Solution Approach 1:
The invention changes the molecular weight parameter of the polyterpene resin to a specific range (900-1200 g/mol) and controls the branching index of polybutadiene rubber (0.7-0.85) to achieve optimal balance between wet grip and rolling resistance. This parameter optimization allows the tread to exhibit high tan δ at 0 °C for wet grip while maintaining low tan δ at 70 °C for low rolling resistance
Solution Approach 2:
The invention uses a composite rubber composition combining styrene-butadiene rubber (30-70 phr), polybutadiene rubber with controlled branching (10-40 phr), and low molecular weight polyterpene resin (5-35 phr). This composite material system achieves synergistic effects where each component contributes to both wet grip and rolling resistance properties simultaneously
2Loss of energy
If BR is used to reduce rolling resistance, then rolling resistance is reduced, but wet grip properties deteriorate
Solution Approach 1:
The invention modifies the polybutadiene rubber by controlling its branching index to a specific range (0.7-0.85) and molecular weight, which changes its viscoelastic properties. This parameter control allows BR to maintain low rolling resistance while improving wet grip through optimized tan δ characteristics at different temperatures
Solution Approach 2:
The invention creates different local properties within the rubber composition by using polybutadiene rubber with specific branching characteristics that provide low rolling resistance, while the addition of low molecular weight polyterpene resin creates local regions that enhance wet grip. The composition achieves 0.35 ≤ tan δ at 0°C ≤ 0.65 and 0.08 ≤ tan δ at 70°C ≤ 0.18 simultaneously
Data Source
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AI summary
The present invention relates to a cross-linkable rubber composition, a cross-linked rubber composition obtained by cross-linking such a rubber composition, a method of preparing a tyre and a tyre. A cross-linkable rubber composition comprises, per hundred parts by weight of rubber (phr): ≥ 1 phr to ≤ 99 phr of a styrene-butadiene rubber (SBR) component; ≥ 1 phr to ≤ 99 phr of a polybutadiene rubber (BR) component; ≥ 5 phr to ≤ 35 phr of a polyterpene resin component; The polybutadiene rubber has a branching index G of ≥ 0.7 to ≤ 0.85 and a polydispersity index Mw/Mn of ≥ 3.5 and ≤ 4.5 and the polyterpene resin has a molecular weight Mw of ≥ 900 to ≤ 1200.