Airless Tire Reinforcing Layer Sulfur Migration Barrier
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Solution Overview
Problem
Airless tires face challenges in achieving high elasticity and low heat generation in their tread ring components, leading to issues with steering stability and rolling resistance, while conventional sulfur-vulcanized rubber compounds tend to degrade due to sulfur migration and differences in elasticity between rubber layers, causing separation and durability problems.
Innovation Solution
A butadiene-based rubber compound with a metal salt of an alpha beta unsaturated carboxylic acid and peroxide is used as a reinforcing layer, accompanied by a barrier layer formed from a vulcanizing adhesive to prevent sulfur migration and ensure the compound's original properties are maintained, and the reinforcing layer is sandwiched between outer and inner reinforcing cord layers for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a butadiene-based rubber compound with peroxide is used as the reinforcing rubber layer to achieve high elasticity and low heat generation, then steering stability and rolling resistance are improved, but sulfur migration from adjacent rubber compounds deactivates the peroxide and degrades the physical properties
Solution Approach 1:
A barrier layer made from sulfur-free rubber compound is introduced between the reinforcing rubber layer (containing peroxide) and the adjacent rubber compound (containing sulfur). This intermediary layer prevents sulfur migration to the peroxide, avoiding deactivation while maintaining the high elasticity and low heat generation properties of the butadiene-based rubber compound.
2Loss of energy
If the reinforcing rubber layer is made with high elasticity rubber compound to reduce rolling resistance, then energy loss is reduced, but large differences in elasticity and elongation between adjacent rubber layers cause separation and breakage at interfaces
Solution Approach 1:
The barrier layer is specifically positioned at the interface between the reinforcing rubber layer and adjacent rubber compound, providing localized sulfur prevention exactly where needed. This allows the reinforcing layer to maintain its high elasticity for low rolling resistance while the barrier layer locally addresses the interface strength issue by preventing chemical degradation.
3Strength
If sulfur is used as vulcanizing agent in adjacent rubber compound to achieve strong bonding, then strength is improved, but sulfur migration during vulcanization deactivates peroxide in the reinforcing rubber layer
Solution Approach 1:
The barrier layer acts as a mediator that allows the adjacent rubber compound to use sulfur for strong bonding while preventing sulfur migration to the peroxide in the reinforcing layer. This enables both requirements to be met: strong bonding in the adjacent layer and effective vulcanization in the reinforcing layer.
4Reliability
If conventional sulfur-vulcanized rubber compounds are used to ensure durability and strength, then reliability is improved, but heat generation increases and elasticity decreases
Solution Approach 1:
The tread ring is segmented into multiple functional layers: the reinforcing rubber layer uses butadiene-based compound with peroxide for low heat generation and high elasticity, while the adjacent rubber compound uses sulfur-vulcanized formulation for durability and strength. The barrier layer separates these segments, allowing each to optimize its properties without compromising the other.
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 solution achieves excellent steering stability, low rolling resistance, and improved durability by maintaining the high elasticity and low heat generation properties of the butadiene-based rubber compound, while addressing the issues of sulfur migration and layer separation.
Implementation Method 1
a barrier layer, which is formed from a rubber-based adhesive or a resin-based adhesive and restrains a part of the sulfur in the adjacent rubber compound from migrating into the reinforcing rubber layer during vulcanization
Implementation Method 2
a rubber compound [A] comprising: 100 parts by mass of the rubber component containing 10 to 100 % by mass of butadiene rubber; 10 to 80 parts by mass of a metal salt of an alpha beta unsaturated carboxylic acid; and a peroxide
Data Source
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AI summary
An airless tire 1 has a tread ring 2 provided with a reinforcing rubber layer 7 disposed radially inside a tread rubber layer 22 and made of a rubber compound [A] comprising: 100 parts by mass of the rubber component containing 10 to 100 % by mass of butadiene rubber; 10 to 80 parts by mass of an metal salt of an alpha beta unsaturated carboxylic acid; and a peroxide. A barrier layer 11, which restrains sulfur in an adjacent rubber compound 10 from migrating into the reinforcing rubber layer 7, is disposed between the reinforcing rubber layer 7 and the adjacent rubber compound 10.