Water-Responsive Tire Tread Rubber for Wet Grip and Dry Efficiency
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Solution Overview
Problem
Conventional rubber compositions for tire treads face challenges in maintaining consistent grip performance across varying road conditions, with reduced wet grip and increased rolling resistance on dry roads due to changes in hardness and volume upon water absorption.
Innovation Solution
A rubber composition containing polybutadiene or styrene-butadiene rubbers with a complex modulus that reversibly changes with water, satisfying specific relationships to maintain optimal grip and rolling resistance across dry and wet conditions, achieved through ionic bonding and controlled filler and softener content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a softener is incorporated to soften the rubber to improve wet performance, then wet grip performance is improved, but rolling resistance on dry road deteriorates
Solution Approach 1:
The patent applies dynamics by making the rubber composition's hardness dynamic rather than static. The composition becomes softer when wet (improving wet grip) and maintains higher hardness when dry (reducing rolling resistance). This is achieved through the reversible interaction between water and the rubber polymer chains, which allows the material to adapt its mechanical properties based on environmental conditions.
Solution Approach 2:
The patent changes the physical parameter of hardness by controlling the rubber composition's interaction with water. By selecting specific rubber polymers and controlling their molecular structure, the composition exhibits variable hardness that decreases upon water absorption (improving wet grip) while maintaining acceptable dry-state properties (limiting rolling resistance increase).
2Strength
If the rubber composition becomes harder due to cooling with water when changing from dry state to wet state, then structural integrity is maintained, but road contact area is reduced and wet grip performance is reduced
Solution Approach 1:
The patent changes the thermal parameter by allowing the rubber composition to warm up upon water contact rather than cooling down. This is achieved through the selection of rubber polymers with specific thermal properties and molecular structures that facilitate heat generation or retention during water interaction, thereby preventing excessive hardening and maintaining road contact area.
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 composition improves wet grip performance by reducing complex modulus upon water absorption and maintaining rolling resistance on dry roads, minimizing volume changes for enhanced overall tire performance.
Implementation Method 1
when conventional rubber compounds change from a dry state where they are not wet with water to a so-called wet state where they are wet with water
Implementation Method 2
rubber molecules of at least one rubber component are partially or fully cross-linked by ionic bonding
Data Source
AI summary
The present disclosure provides a rubber composition and a tire which provide improved overall performance in terms of wet performance and dry performance. The present disclosure relates to a rubber composition, containing at least one polybutadiene rubber and/or at least one styrene-butadiene rubber, having a complex modulus E* that reversibly changes with water, and satisfying the following relationships 1) to 3): 1) Complex modulus E* when water-wet/Complex modulus E* before water-wet×100≤98 wherein E* represents the E* at 23° C. of the rubber composition; 2) 99≤Complex modulus E* after water-wet and dehydrated/Complex modulus E* before water-wet×100≤100 wherein E* represents the E* at 23° C. of the rubber composition; 3) 99≤Volume when water-wet/Volume before water-wet×100≤100 wherein Volume represents the volume at 23° C. of the rubber composition.