Two-Layer Tread Composition for Wet Grip After Rubber Hardening
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Solution Overview
Problem
Tires with multiple rubber layers face a challenge in maintaining wet grip performance over time due to hardening of the cap rubber layer, which is influenced by the thickness and surface roughness of the rubber, leading to a need for predicting and controlling the change in rubber hardness.
Innovation Solution
A tire design with a first layer forming the tread surface and a second layer adjacent to it in the radial direction, where the difference in acetone extraction amounts between the two layers is set within a specific range, and subjected to a dynamic stimulus, controls the diffusion of plasticizers to maintain optimal rubber hardness and grip performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cap rubber layer is used to touch the road surface, then wet grip performance is improved, but the rubber hardens over time due to running, deteriorating wet grip performance
Solution Approach 1:
The patent applies parameter changes by controlling the plasticizer content in the cap rubber layer within a specific range (5-20 parts by mass per 100 parts of rubber component) and adjusting the acetone extraction amount to maintain optimal rubber hardness. This prevents excessive hardening while preserving wet grip performance over time.
Solution Approach 2:
The patent uses composite materials by formulating the cap rubber layer with a specific combination of rubber components and plasticizers, creating a multi-component material system that balances initial wet grip performance with long-term hardness stability. The controlled plasticizer diffusion between layers creates a composite structure that maintains performance consistency.
2Reliability
If plasticizer diffusion is controlled to maintain rubber hardness, then wet grip performance is maintained, but the complexity of controlling acetone extraction amounts increases
Solution Approach 1:
The patent applies preliminary action by pre-controlling the plasticizer content and acetone extraction amount during the rubber composition formulation stage. This preliminary setup ensures that plasticizer diffusion occurs at a controlled rate during tire operation, maintaining rubber hardness without requiring complex real-time control mechanisms.
Solution Approach 2:
The patent implements self-service by designing the rubber composition system to automatically regulate plasticizer diffusion through the inherent properties of the materials. The controlled acetone extraction amount creates a self-regulating mechanism where the plasticizer naturally diffuses at an optimal rate, eliminating the need for external control systems.
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 effectively maintains wet grip performance even after abrasion by controlling the change in rubber hardness through controlled plasticizer diffusion, ensuring consistent traction and safety.
Implementation Method 1
a change in rubber hardness over time occurs due to diffusion of a plasticizer from the first layer to the second layer
Implementation Method 2
a degree of diffusion of the plasticizer can be judged by a change in acetone extraction amount of the second layer over time
Data Source
AI summary
Provided is a tire comprising a tread at least having two layers each comprising a rubber component and a plasticizer, wherein a difference (AE1−AE2) between an acetone extraction amount AE1 of the rubber composition of the first layer and an acetone extraction amount AE2 of the rubber composition of the second layer is greater than 6.0% by mass, and wherein, with the first layer and the second layer being attached together, when they are applied with a dynamic stimulus under a condition of a dynamic stress of 0.45 MPa, a frequency of 50 Hz, and a temperature at 80° C. for 120 hours, a rate of change in acetone extraction amount of the rubber composition of the first layer before and after being applied with the predetermined dynamic stimulus is −10% or more and 10% or less.