Tire Tread Rubber Composition for Low Rolling Resistance Grip
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Solution Overview
Problem
Existing tire compositions struggle to simultaneously improve rolling resistance without compromising wet and dry braking performance.
Innovation Solution
A rubber composition comprising specific ratios of high and low glass transition temperature styrene butadiene rubbers, silica, terpene resin, and controlled amounts of silane and oil, along with functionalized rubbers for improved coupling, achieves a balanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If rolling resistance is reduced to improve energy efficiency, then wet grip and braking performance deteriorate
Solution Approach 1:
The patent employs a composite rubber composition combining solution-polymerized styrene butadiene rubber (SSBR) with natural rubber (NR) and synthetic polyisoprene. This multi-component composite system achieves synergistic effects where SSBR provides low rolling resistance through its molecular structure, while NR and polyisoprene contribute to wet grip and braking performance through their natural adhesion properties and glass transition characteristics.
Solution Approach 2:
The patent utilizes silane modification of SSBR to change the chemical and physical parameters of the rubber matrix. The silane treatment alters the surface properties and molecular interactions, enabling the rubber to simultaneously achieve low hysteresis (reducing rolling resistance) and high adhesion (improving wet grip). The specific parameter changes include modified crosslinking density and altered polymer chain flexibility.
2Reliability
If silica content is increased to improve wet performance, then rolling resistance increases
Solution Approach 1:
The patent introduces silane as an intermediary substance that mediates between silica filler and the rubber matrix. The silane acts as a coupling agent, creating strong interfacial bonds between silica particles and polymer chains. This intermediary layer prevents silica aggregation and ensures uniform stress distribution, allowing high silica content to be incorporated without excessive energy loss. The silane treatment transforms silica from a potentially harmful filler into a beneficial reinforcement that improves wet grip while maintaining low rolling resistance.
Data Source
Figure 1
AI summary
In a first aspect, the present invention is directed to a rubber composition comprising 70 phr to 90 phr of styrene butadiene rubber, wherein said styrene butadiene rubber comprises a first styrene butadiene rubber having a glass transition temperature within a range of -49°C to -15°C and a second styrene butadiene rubber having a glass transition temperature within a range of -50°C to -89°C. Furthermore, the rubber composition comprises from 10 phr to 30 phr of one or more of natural rubber and synthetic polyisoprene rubber, 100 phr to 200 phr of silica, and at least 25 phr of at least one terpene resin having a weight average molecular weight (Mw) of at most 1000 g/mol. Moreover, the invention is directed to a tire comprising such a rubber composition, in particular in the tread of the tire.