Self-Sealing Elastomer Composition for Tire Puncture Resistance
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Solution Overview
Problem
Existing self-sealing compositions for inflatable tires face challenges in maintaining effectiveness over a wide range of temperatures and stability, particularly when exposed to extreme conditions, and are insufficiently effective after the removal of a perforating object, leading to increased rolling resistance and manufacturing costs.
Innovation Solution
A self-sealing composition comprising at least 30 phr of saturated thermoplastic styrene elastomer, up to 70 phr of unsaturated thermoplastic styrene elastomer, and more than 200 phr of oil extender, which does not require butyl rubber or tackifying resins, enhancing puncture resistance and sealing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If butyl rubber is used in self-sealing composition, then puncture resistance is improved, but rolling resistance increases due to large hysteresis losses
Solution Approach 1:
The patent changes the chemical composition parameters by replacing butyl rubber with thermoplastic styrene elastomers (specifically SBS and SIBS copolymers) in the self-sealing composition. This parameter change maintains the sealing function while reducing hysteresis losses, as thermoplastic elastomers exhibit lower energy dissipation compared to butyl rubber, thereby reducing rolling resistance.
Solution Approach 2:
The patent uses a composite material system consisting of thermoplastic styrene elastomers (SBS and SIBS) combined with specific additives (zinc oxide, stearic acid, and processing oil) to create a self-sealing composition that achieves both puncture resistance and low rolling resistance. The composite formulation leverages the unique properties of each component to resolve the contradiction between sealing effectiveness and energy efficiency.
2Reliability
If high molecular weight crosslinked butyl rubber is used, then self-sealing effectiveness is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent extracts and eliminates the complex crosslinking process and high molecular weight butyl rubber from the self-sealing composition. Instead, it uses thermoplastic styrene elastomers that provide self-sealing functionality through their inherent viscoelastic properties and phase separation structure, without requiring crosslinking chemistry or specialized high molecular weight materials, thereby simplifying manufacturing.
Solution Approach 2:
The patent employs conventional, readily available thermoplastic styrene elastomers (SBS and SIBS) that can be processed using standard extrusion and molding techniques. These materials are commercially available, cost-effective, and do not require specialized handling or processing equipment, making the manufacturing process more accessible and less complex compared to handling high molecular weight crosslinked butyl rubber.
3Reliability
If conventional self-sealing composition is used, then initial sealing is achieved, but effectiveness decreases after removal of perforating object
Solution Approach 1:
The patent utilizes the dynamic viscoelastic properties of thermoplastic styrene elastomers, which can reversibly change their mechanical properties in response to applied stress and temperature. The phase-separated structure of SBS and SIBS allows the material to dynamically adapt: remaining relatively rigid at service temperatures for structural integrity, but becoming more compliant under the heat and pressure of a puncture event to enable effective sealing, and then recovering its original state after the event.
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 provides improved puncture resistance and faster sealing of holes, with reduced rolling resistance and manufacturing costs, maintaining effectiveness across a wide temperature range and after the removal of a perforating object.
Implementation Method 1
more than 200 phr of an oil extender for said elastomers
Implementation Method 2
at least 30 phr of a saturated thermoplastic styrene ("TPS") elastomer; at most 70 phr of an unsaturated TPS elastomer
Data Source
AI summary
Self-sealing elastomer composition that can in particular be used as puncture-resistant layer in an inflatable article, comprising at least 30 phr of a saturated thermoplastic styrene elastomer, at most 70 phr of an unsaturated thermoplastic styrene elastomer and more than 200 phr of an oil extender. Inflatable article, such as a tire, provided with a puncture-resistant layer comprising, as self-sealing composition, an elastomer composition according to the invention. Advantageously, the puncture-resistant layer is combined with an airtight layer, for example based on butyl rubber, so as to constitute, in the inflatable article, a puncture-resistant airtight laminate.