Rim Cushion Rubber Composition for Low Heat Build-Up and Wear Resistance
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Solution Overview
Problem
Existing rubber compositions for rim cushions in tires face challenges in balancing low heat build-up, elongation at break, and wear resistance, with previous methods failing to adequately address these requirements.
Innovation Solution
A rubber composition comprising diene rubber with specific blends of isoprene and butadiene rubber, silica with a CTAB adsorption specific surface area of 60-100 m2/g, carbon black with a CTAB adsorption specific surface area of 60-160 m2/g, and a sulfur-containing silane coupling agent, along with a product of stress M100 at 100% elongation and hardness of 150 or more, to achieve a well-balanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the blended amount of filler such as carbon black is reduced or particle size of carbon black is increased, then heat build-up is reduced, but rubber hardness and wear resistance deteriorate
Solution Approach 1:
The patent uses a composite filler system combining silica and carbon black in specific ratios (silica: 20-40 parts, carbon black: 10-30 parts per 100 parts rubber). This composite approach allows the silica to provide reinforcement for wear resistance while the carbon black contributes to heat build-up reduction, achieving both goals simultaneously through material composition rather than relying on a single filler type.
Solution Approach 2:
The patent specifies precise particle size ranges for both silica (0.5-2.0 μm) and carbon black (surface area 80-150 m²/g). By controlling these physical parameters within optimal ranges, the composition achieves balanced performance: the fine silica particles provide reinforcement without excessive heat generation, while the controlled carbon black particle size maintains wear resistance while limiting heat build-up.
2Loss of energy
If silica having a large particle size is blended to reduce heat build-up, then tan δ (60° C.) is reduced, but rubber hardness and elongation at break are insufficient
Solution Approach 1:
The patent specifies silica particle size of 0.5-2.0 μm (measured by laser diffraction method, D50 value). This controlled particle size range is optimal: large enough to reduce heat build-up compared to fine particles, but small enough to maintain good elongation at break and hardness. The surface area is controlled at 150-300 m²/g to ensure proper reinforcement.
Solution Approach 2:
The patent uses surface-modified silica with specific surface treatment (silane coupling agents) to enhance the interface between silica particles and rubber matrix. This local modification at the particle surface improves adhesion and stress transfer, maintaining elongation at break and hardness even when using larger particle sizes that reduce heat build-up.
3Strength
If the blended amount of silica and carbon black is increased to improve wear resistance, then wear resistance is enhanced, but heat build-up increases
Solution Approach 1:
The patent employs a synergistic composite filler system where silica (20-40 parts) provides the primary reinforcement for wear resistance, while carbon black (10-30 parts) contributes to both wear resistance and heat build-up management. The specific ratio and combination allow the silica-carrying the main mechanical load- to protect against wear, while the carbon black network helps dissipate heat, achieving both wear resistance and low heat build-up.
Solution Approach 2:
The patent applies surface modification to silica particles using silane coupling agents, creating a localized improved interface region. This surface treatment enhances the silica-rubber bonding, allowing effective stress transfer and wear resistance at lower overall filler loadings, thereby reducing the total filler amount needed and consequently reducing heat build-up from excessive filler content.
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 effectively improves low heat build-up, maintains elongation at break, and enhances wear resistance, providing a balanced and compatible performance for rim cushion rubber layers.
Implementation Method 1
a sulfur-containing silane coupling agent
Implementation Method 2
tan δ at 60° C. (hereinafter, referred to as 'tan δ (60° C.)') from dynamic visco-elasticity measurement is typically used, and smaller tan δ (60° C.) of the rubber composition indicates less heat build-up
Data Source
AI summary
Provided is a rubber composition for a rim cushion that can provide satisfactorily maintained hardness, elongation at break, and wear resistance and improved low heat build-up and can provide these performances in a well-balanced and highly compatible manner. Silica having a CTAB adsorption specific surface area of 60 m2/g to 100 m2/g, carbon black having a CTAB adsorption specific surface area of 60 m2/g to 160 m2/g, and a sulfur-containing silane coupling agent are blended in diene rubber containing 35 mass % to 65 mass % of isoprene rubber and 35 mass % to 65 mass % of butadiene rubber. At least one type of terminal-modified butadiene rubber for silica is used as the butadiene rubber. A blended amount of the silica per 100 parts by mass of the diene rubber is 10 parts by mass or more and a total of the blended amount of the silica. A blended amount of the carbon black per 100 parts by mass of the diene rubber is more than 50 parts by mass. A product of a stress M100 at 100% elongation and hardness is set to 150 or more.