Bilayer Tire Tread Composition for Snow Grip and Low Rolling Resistance
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Solution Overview
Problem
All-season tires face challenges in achieving a balance between dry performance, wet performance, and snow performance while reducing rolling resistance, as these characteristics often conflict with each other due to the properties of tread rubber.
Innovation Solution
A pneumatic tire with a bilayer tread structure, comprising an undertread layer and a cap tread layer, where the cap tread layer contains a specific rubber composition with a high silica content, a blend of natural rubber, styrene-butadiene rubber, and modified butadiene rubber, and a hardness relationship between the undertread and cap tread rubbers is optimized to enhance dry, wet, and snow performance while reducing rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blended amount of butadiene rubber is increased to improve snow performance, then the dispersibility of silica deteriorates, but rolling resistance reduction becomes difficult
Solution Approach 1:
The tire is segmented into cap tread layer and undertread layer with different rubber compositions. The cap tread layer contains optimized butadiene rubber content for snow performance while maintaining good silica dispersibility, whereas the undertread layer has different composition priorities, allowing each layer to optimize for its specific performance requirements without compromising the other
Solution Approach 2:
The patent uses composite rubber materials combining different types of rubber (natural rubber, styrene-butadiene rubber, butadiene rubber) with silica in specific proportions. This composite approach allows optimization of multiple properties simultaneously - snow performance through butadiene rubber content, silica dispersibility through surface treatment, and rolling resistance through overall composition design
2Device complexity
If a single-layer tread structure is used, then the structure is simple, but it is difficult to provide dry performance, wet performance, and snow performance in a well-balanced manner
Solution Approach 1:
The single-layer tread is segmented into two functional layers: cap tread layer and undertread layer. Each layer has optimized rubber composition for its specific function, allowing the tire to achieve well-balanced performance across dry, wet, and snowy conditions while maintaining relatively simple manufacturing processes
Solution Approach 2:
The bilayer tread structure provides multi-functionality within a unified tire design. The cap tread layer optimizes for snow performance and surface contact, while the undertread layer optimizes for structural support and durability. Together, they create a universal tread design that performs well across all seasonal conditions
Data Source
AI summary
For a cap tread layer of a pneumatic tire, a rubber composition is used, which contains from 60 to 90 parts by mass of silica per 100 parts by mass of a diene rubber containing from 15 to 30 mass % of a natural rubber, from 40 to 70 mass % of a terminal-modified styrene-butadiene rubber having a vinyl content of from 35 to 45 mass %, and from 15 to 30 mass % of a modified butadiene rubber obtained by modifying an active terminal of a conjugated diene polymer with at least a hydrocarbyloxysilane compound, the total of these being 100 mass %. A hardness Hu of the undertread Layer and a hardness Hc of the cap tread layer satisfy the relationship of Hu>Hc. The hardness Hc is 63 or greater and 67 or less. A difference ΔH between the hardness Hu and the hardness Hc is 10 or more.