Tire Inner Liner Laminate for Splice Crack Resistance
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Solution Overview
Problem
Pneumatic tires with inner liners formed from laminated sheets of thermoplastic resin and rubber compositions experience cracks at the overlapped-splice portion due to stress concentration during use.
Innovation Solution
A laminate is developed comprising a layer of rubber composition with a high storage elastic modulus and a film of thermoplastic resin or elastomer, with specific elastic modulus and thickness ranges, and a peel strength greater than 30 N/inch, to mitigate stress concentration at the splice.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laminated sheet of thermoplastic resin and rubber composition is used for the inner liner, then the tire can be manufactured with improved production efficiency, but cracks occur at the overlapped-splice portion due to stress concentration during use
Solution Approach 1:
The patent applies local quality by creating a rubber composition layer with specific elastic modulus characteristics (storage elastic modulus of 30 MPa or more at 70°C when dynamic distortion is 0.1%) specifically at the splice portion. This localized modification of mechanical properties allows the splice area to better withstand stress concentration without affecting the overall tire performance, thereby preventing cracks while maintaining production efficiency.
Solution Approach 2:
The patent utilizes parameter changes by controlling the storage elastic modulus of the rubber composition within a specific range (30-500 MPa at 70°C) and specifying thickness parameters (0.5-5.0 mm). By optimizing these physical parameters, the rubber layer can effectively distribute and reduce stress concentration at the splice portion, preventing crack formation while maintaining the benefits of laminated sheet production.
2Reliability
If the storage elastic modulus of the rubber composition is increased to suppress crack formation, then crack resistance improves, but the rubber composition becomes too rigid and may cause other performance issues
Solution Approach 1:
The patent applies parameter changes by precisely controlling the storage elastic modulus within the range of 30-500 MPa at 70°C. This optimized parameter range ensures the rubber composition has sufficient rigidity to suppress crack formation at the splice portion while maintaining adequate flexibility for normal tire operation, thus balancing crack resistance with overall rubber performance.
Solution Approach 2:
The patent employs composite materials by combining thermoplastic resin or thermoplastic elastomer with rubber composition in a laminated structure. This composite approach allows the rubber layer to provide the necessary elastic modulus for crack suppression while the thermoplastic component maintains flexibility and processability, achieving a balance between rigidity and flexibility.
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 laminate effectively suppresses crack formation in the overlapped-splice portion of the tire inner liner, enhancing durability and reducing peeling failures.
Implementation Method 1
it is possible to suppress the cracks by mitigating the concentration of stress at the overlapped-splice portion by compounding a rubber composition having a high storage elastic modulus
Implementation Method 2
a storage elastic modulus at 70° C. being 30 MPa or greater
Implementation Method 3
a peel strength between the film and the rubber composition determined by 180° peel test being 30 N/inch or greater
Data Source
AI summary
A laminate for tires is a laminate of a layer of a rubber composition and a film comprising a thermoplastic resin or a thermoplastic elastomer composition; upon dynamic distortion of the film being 0.1%, a storage elastic modulus at 70° C. being 30 MPa or greater, and a thickness of the film being 60 μm or greater; upon dynamic distortion of the rubber composition being 0.1%, a storage elastic modulus at −20° C. being less than 400 MPa and a storage elastic modulus at 70° C. being 8.5 MPa or greater, and a thickness of the rubber composition being 150 μm or greater; and a peel strength between the film and the rubber composition determined by 180° peel test being 30 N/inch or greater.