Studless Winter Tire Two-Layer Tread Softener Optimization
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Solution Overview
Problem
Studless winter tires face challenges in maintaining performance on ice and snow both initially and after degradation, with high softener content leading to hardness changes that reduce traction and abrasion resistance.
Innovation Solution
A studless winter tire design featuring a cap tread and base tread with specific softener content ratios, where the softener content in the cap tread is less than in the base tread, suppressing softener migration and maintaining performance through a two-layered tread structure with natural rubber and polybutadiene rubber compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the softener content in the rubber composition is increased to enhance initial performance on ice and snow, then the initial performance on ice and snow is improved, but the resistance to change in hardness with age deteriorates
Solution Approach 1:
The tread is divided into two layers with different softener contents: the cap tread contains 5-25 parts by mass of softener per 100 parts by mass of rubber component, while the base tread contains 15-35 parts by mass of softener per 100 parts by mass of rubber component. This segmentation allows the cap tread to provide good initial performance on ice and snow while the base tread maintains stability and resists hardening degradation.
Solution Approach 2:
Different regions of the tread are given different softener contents to perform different functions. The cap tread (outer layer) has lower softener content for stability, while the base tread (inner layer) has higher softener content for initial performance. This local differentiation resolves the contradiction between initial performance and long-term stability.
2Reliability
If the softener content is increased unlimitedly to improve performance on ice and snow, then the performance on ice and snow is enhanced, but the tread rubber undergoes greater change in hardness with age
Solution Approach 1:
The tread is segmented into cap and base layers with differentiated softener contents. The cap tread contains 5-25 parts by mass of softener per 100 parts by mass of rubber component, while the base tread contains 15-35 parts by mass of softener per 100 parts by mass of rubber component. This segmentation prevents unlimited softener content while maintaining performance.
3Device complexity
If a single-layer tread structure is used, then the structure is simple, but it is hard to simultaneously enhance performance on ice and snow after degradation and initial performance on ice and snow
Solution Approach 1:
The tread is divided into two layers: cap tread with 5-25 parts by mass of softener per 100 parts by mass of rubber component, and base tread with 15-35 parts by mass of softener per 100 parts by mass of rubber component. This segmentation enables simultaneous enhancement of initial performance and performance after degradation.
Solution Approach 2:
The tread uses a composite structure combining two rubber compositions with different softener contents. The cap tread rubber composition and base tread rubber component work together to provide both initial performance and durability, resolving the contradiction between complexity and performance.
Data Source
AI summary
A studless winter tire that has enhanced performance on ice and snow both initially and after degradation while maintaining good abrasion resistance is provided. The studless winter tire includes: a cap tread formed from a rubber composition A; and a base tread formed from a rubber composition B. The studless winter tire satisfies the following formulas (1) and (2): (1) a×c/100<b×d/100; and (2) a≥8, where a represents the softener content (% by mass) based on 100% by mass of the rubber composition A; b represents the softener content (% by mass) based on 100% by mass of the rubber composition B; c represents the percentage by mass (% by mass) of the cap tread based on the entire tread; and d represents the percentage by mass (% by mass) of the base tread based on the entire tread.