Sidewall Insert Composition for Runflat Tire Weight Reduction
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Solution Overview
Problem
Conventional rubber formulations for sidewall inserts in runflat tires lack sufficient hardness and modulus while maintaining or decreasing density, which is essential for weight reduction and endurance.
Innovation Solution
A composition comprising natural rubber, butadiene rubber, and ethylene-based polymers such as ethylene/α-olefin copolymers or multiblock copolymers, which provides increased mechanical properties and maintains density, enabling a slim contour for sidewall inserts with significant weight reduction without compromising tire endurance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rubber formulations use natural rubber and polybutadiene with carbon black filler to increase material stiffness, then the sidewall insert hardness and modulus are improved, but the density increases and weight reduction cannot be achieved
Solution Approach 1:
The patent changes the chemical composition parameters of the rubber formulation by introducing ethylene-based polymers (POE and OBC) with specific density ranges (0.866-0.902 g/cm³) and molecular weight characteristics. This parameter change enables achieving higher hardness and modulus while maintaining lower density compared to conventional formulations, directly resolving the contradiction between strength and weight
Solution Approach 2:
The patent creates a composite rubber formulation combining natural rubber (NR), polybutadiene rubber (BR), and ethylene-based polymers (POE/OBC) in specific ratios. This composite material approach leverages the complementary properties of each component: NR provides toughness, BR provides elasticity, and POE/OBC provide stiffness with lower density, achieving both high strength and weight reduction simultaneously
2Strength
If filler loading is increased to increase material stiffness of the sidewall insert, then the hardness and modulus are improved, but the density increases compromising weight reduction goals
Solution Approach 1:
The patent changes the formulation strategy from relying on high filler loading to using ethylene-based polymers with controlled molecular weight and density parameters. By adjusting the polymer composition parameters rather than filler quantity, the patent achieves material stiffness improvement without increasing density, resolving the contradiction between strength and quantity of substance
3Weight of moving object
If the sidewall insert is made thinner to reduce weight, then the weight reduction is achieved, but the mechanical properties and endurance may be compromised
Solution Approach 1:
The patent uses composite materials with synergistic properties where POE/OBC enhance the mechanical strength and stiffness of the sidewall insert. This allows thinner wall designs to maintain sufficient structural integrity and endurance, resolving the contradiction between weight reduction and reliability
Solution Approach 2:
The patent optimizes the molecular weight and density parameters of the ethylene-based polymers to achieve the right balance between strength and weight. The specific parameter ranges selected ensure that even reduced-thickness sidewalls maintain adequate mechanical properties for tire endurance while achieving weight reduction goals
Data Source
AI summary
This invention provides a composition comprising a natural rubber, a polybutadiene rubber and an ethylene/α-olefin copolymer and/or ethylene/α-olefin multiblock copolymer. The invention also provides for methods of making the composition, and articles prepared from the composition.