Pneumatic Tire Tread Composition for Winter Traction and Rolling Resistance
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Solution Overview
Problem
Tires face challenges in balancing wet skid resistance, low rolling resistance, and wear characteristics, particularly in low-temperature winter conditions, due to the viscoelastic inconsistencies of rubber compositions used in tire treads.
Innovation Solution
A pneumatic tire tread composition comprising solution polymerized styrene-butadiene rubber, natural rubber, process oil, and silica, with a specific ratio of silica to oil and traction resin, and optionally a hydrocarbon traction resin, to achieve improved traction and reduced rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rubbers with high energy loss are used to increase wet skid resistance, then wet traction is improved, but rolling resistance increases
Solution Approach 1:
The patent utilizes rubbers with different glass transition temperatures (Tg) to achieve parameter changes in viscoelastic properties. Specifically, it combines rubbers with low Tg (e.g., polybutadiene with Tg = -100°C to -90°C) for low-temperature flexibility and wet traction, with rubbers with higher Tg for reduced rolling resistance. The composition ratios and curing systems are optimized to balance energy loss characteristics across different temperature ranges, resolving the contradiction between wet skid resistance and rolling resistance.
Solution Approach 2:
The patent employs composite rubber formulations combining multiple elastomer types (polybutadiene, styrene-butadiene rubber, natural rubber) with distinct viscoelastic properties. This composite approach allows the tread to exhibit optimized performance characteristics: the low-Tg polybutadiene provides wet grip and low-temperature flexibility, while the higher-Tg components contribute to reduced hysteresis loss and rolling resistance. The composite material strategy enables simultaneous achievement of contradictory performance goals.
2Reliability
If rubber compositions are optimized for wet traction, then wet skid resistance is improved, but wear characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by selecting rubbers with specific glass transition temperatures and optimizing their proportions in the compound. The low-Tg rubbers (polybutadiene, cis-1,4-polyisoprene) enhance wet adhesion through increased molecular mobility and hysteresis loss, while the inclusion of higher-Tg rubbers (styrene-butadiene rubber, natural rubber) and optimization of curing systems maintain tensile strength and abrasion resistance. This parameter optimization allows the tread to achieve both wet skid resistance and acceptable wear characteristics.
Solution Approach 2:
The patent utilizes composite rubber materials combining elastomers with different Tg values and mechanical properties. The composite formulation balances the soft, high-hysteresis low-Tg rubbers (for wet grip) with tougher, lower-hysteresis higher-Tg rubbers (for wear resistance). This composite material approach enables the tread compound to simultaneously achieve wet traction performance and durability, resolving the contradiction between wet skid resistance and wear characteristics.
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 tire tread composition enhances wet traction, reduces rolling resistance, and maintains low temperature performance by optimizing the viscoelastic properties of the rubber, thereby balancing the conflicting demands of wear and traction characteristics.
Implementation Method 1
These properties depend, to a great extent, on the dynamic viscoelastic properties of the rubbers utilized in making the tire
Implementation Method 2
a solution polymerized styrene-butadiene rubber having a glass transition temperature (Tg) ranging from −85° C. to −50° C.
Data Source
AI summary
The present invention is directed to a pneumatic tire having a tread comprising a vulcanizable rubber composition comprising, based on 100 parts by weight of elastomer (phr),(A) from about 60 to about 40 phr of a solution polymerized styrene-butadiene rubber having a glass transition temperature (Tg) ranging from −85° C. to −50° C.;(B) from about 40 to about 60 phr of natural rubber; and(C) from about 5 to 40 phr of a process oil;(D) optionally, from about 5 to 15 phr of a hydrocarbon traction resin(E) from 60 to 90 phr of silica;wherein the weight ratio of silica to the sum of the amounts of oil and traction resin is greater than 2.2.