Bead Apex Rubber Composition for Heavy-Duty Tire Interface Durability
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Solution Overview
Problem
Heavy duty tires face durability issues due to poor adhesion at the interface of the bead apex rubber, leading to potential damage under high loads, especially when using recycled rubber materials.
Innovation Solution
A bead apex rubber formulation with an inner and outer apex portion containing isoprene-based rubber, carbon black, and a modified rubber material functionalized with a thiuram sulfide compound, where the complex moduli of the inner and outer apex portions are controlled to satisfy specific relationships, ensuring improved adhesion and reduced strain at the interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If recycled rubber materials are used in the bead apex rubber, then cost is reduced and sustainability is improved, but adhesion at the interface deteriorates and durability decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the complex modulus values of the inner and outer apex portions through specific rubber compound formulations. By adjusting the modulus parameters (Ei* and Eo*) to satisfy specific relationships, the patent achieves optimal adhesion between recycled rubber materials and the bead core, resolving the contradiction between using cost-effective recycled materials and maintaining high adhesion quality.
Solution Approach 2:
The patent uses composite materials by combining recycled rubber materials with specific polymer compounds and additives in the bead apex rubber formulation. This composite approach allows the utilization of recycled materials while maintaining or improving adhesion properties through the synergistic effects of different material components, thereby achieving both sustainability and durability.
2Strength
If the complex modulus of the bead apex rubber is increased to improve strength, then resistance to deformation improves, but adhesion at the interface deteriorates due to strain concentration
Solution Approach 1:
The patent resolves this contradiction through parameter changes by establishing specific relationships between the complex modulus of the inner apex portion (Ei*) and the outer apex portion (Eo*). By controlling these modulus parameters to satisfy defined relationships, the patent achieves both high resistance to deformation and optimal interface adhesion, preventing strain concentration at the interface.
3Reliability
If a single-layer bead apex rubber structure is used, then manufacturing complexity is reduced, but adhesion and durability under high loads are insufficient
Solution Approach 1:
The patent applies segmentation by dividing the bead apex rubber into distinct inner and outer apex portions, each with different rubber compound formulations and complex modulus characteristics. This segmentation allows each layer to perform its specific function optimally, with the inner layer providing adhesion to the bead core and the outer layer providing resistance to deformation, thereby achieving high durability while maintaining reasonable manufacturing complexity.
Solution Approach 2:
The patent implements local quality by赋予ing different properties to different regions of the bead apex rubber. The inner apex portion has specific modulus characteristics optimized for adhesion to the bead core, while the outer apex portion has different modulus characteristics optimized for resistance to deformation. This localized property differentiation resolves the contradiction between structural simplicity and performance requirements.
Data Source
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AI summary
Provided is a highly durable heavy duty tire. Included is a heavy duty tire (1) which includes a bead apex rubber including an inner apex portion (8A) and an outer apex portion (8B), and in which at least one selected from the group consisting of the inner apex portion and the outer apex portion contains an isoprene-based rubber, carbon black, and a modified rubber material functionalized with a thiuram sulfide compound, and the heavy duty tire satisfies the following relationships (1) and (2) : (1) Ei* > Eo* and (2) Ei*/Eo* ≤ 7.0, wherein Ei* and Eo* represent the complex moduli of the inner apex portion and the outer apex portion, respectively, measured under conditions including a temperature of 70°C, an initial strain of 5%, a dynamic strain of 1%, a frequency of 10 Hz, and an extension mode.