Gradient SBR Rubber Mixture for Tire Tread Performance
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Solution Overview
Problem
Existing tire rubber compounds for vehicle treads often face a trade-off where optimizing one desired property, such as ice braking or wet grip, worsens another property like rolling resistance, making it difficult to simultaneously improve multiple performance characteristics.
Innovation Solution
A vulcanizable rubber mixture with a conjugated diolefin-styrene copolymer (SBR) containing 10 to 60 mol% styrene, where the distribution of styrene units along the chain is uneven, allowing for fine-tuning of performance properties by varying monomer concentrations during copolymerization, thereby optimizing opposing pairs of properties like ice braking and wet grip without deteriorating rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If styrene content and vinyl content of SBR are increased to improve ice braking and wet grip, then rolling resistance increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the temperature difference between the maximum value of tan δ and the first maximum of the loss modulus to be at least 30°C. This specific parameter control allows optimization of wet grip and ice braking while maintaining acceptable rolling resistance characteristics.
Solution Approach 2:
The patent uses a composite approach by combining SBR rubber with specific polybutadiene content (20-70 phr) and silica filler (30-80 phr), creating a multi-component system where each component contributes different properties. The composite structure allows balancing wet grip, ice braking, and rolling resistance through synergistic interactions between components.
2Duration of action of stationary object
If SBR content is increased to improve tread durability and abrasion resistance, then cold flexibility deteriorates
Solution Approach 1:
The patent controls the temperature difference parameter (≥30°C between tan δ maximum and loss modulus maximum) to simultaneously achieve both tread durability and cold flexibility. This parameter control enables the rubber compound to maintain appropriate hardness and elasticity across a wide temperature range.
Solution Approach 2:
The patent creates a composite system combining SBR (providing durability) with polybutadiene (providing cold flexibility) in specific ratios. This composite approach allows the tread to exhibit both long-term durability and good performance at low temperatures.
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 enables the simultaneous optimization of different tire properties, improving wet grip and ice braking while maintaining low rolling resistance and unchanged abrasion, as demonstrated by the shifted tangent delta value and improved cold flexibility.
Implementation Method 1
the maximum value for tan δ determined from the data of the dynamic mechanical analysis (DMA) of the SBR pure polymer exceeds the first maximum of the loss modulus by at least 30 °C
Data Source
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AI summary
To improve the performance characteristics, particularly the dynamic mechanical properties, of rubber compounds for vehicle tire treads, a vulcanizable rubber compound is proposed, comprising a rubber component, one or more fillers, and optionally additives, and containing a special SBR rubber. For this purpose, the rubber component of the compound comprises 1 to 100 wt.% of an SBR rubber with a styrene content of 10 to 60 mol%, distributed gradient-wise across the rubber chains. The styrene units can be organized in microblocks of 2 to 10 interconnected units. The SBR rubber is formulated such that the maximum tan δ exceeds the first maximum of the loss factor by at least 30 °C.