EVOH Laminate for Tire Gas Barrier and Fatigue Durability
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Solution Overview
Problem
Existing gas permeation preventing structures in pneumatic tires, such as those using EVOH-containing layers, face challenges in achieving a balance between gas permeation prevention and fatigue durability due to cracking issues under mechanical stress, which compromises air pressure retention.
Innovation Solution
A laminate comprising alternately stacked EVOH layers and layers of a thermoplastic resin composition with a different composition, specifically a halogenated isoolefin-paraalkylstyrene copolymer rubber, where the tensile modulus ratio and thickness ratio between the two layers are optimized to reduce stress on the EVOH layers, preventing cracking and enhancing fatigue durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an EVOH-containing layer is applied to the inner surface of a tire as a laminate with another layer having a low elastic modulus, such as a rubber layer, then gas permeation preventing properties are improved, but excessive stresses due to repeated flex and tensile deformations cause cracks in the EVOH-containing layer, reducing fatigue durability
Solution Approach 1:
The patent applies composite materials by creating a laminate structure that combines an EVOH-containing layer (providing gas barrier properties) with a thermoplastic elastomer layer (providing flexibility and stress absorption). This composite structure allows the EVOH layer to maintain gas permeation prevention while the elastomer layer absorbs excessive stresses from flex and tensile deformations, preventing crack formation and improving fatigue durability.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the elastic modulus and thickness of each layer in the laminate. The thermoplastic elastomer layer is designed with specific elastic modulus parameters that allow it to absorb stresses while the EVOH layer maintains its gas barrier function. By optimizing these parameters, the patent resolves the contradiction between gas permeation prevention and fatigue durability.
2Reliability
If the thickness of the EVOH-containing layer is increased to improve gas barrier properties, then gas permeation prevention is enhanced, but the weight of the layer increases, reducing fuel efficiency
Solution Approach 1:
The patent uses composite materials to achieve high gas barrier properties with reduced weight. The laminate structure combines a thin EVOH-containing layer (providing gas barrier function) with a thermoplastic elastomer layer (providing mechanical flexibility). This composite approach allows the EVOH layer to be thinner than it would need to be if used alone, thereby reducing overall weight while maintaining gas permeation prevention performance.
3Reliability
If an EVOH-containing layer is directly applied to the inner surface of a tire, then gas permeation preventing properties are achieved, but excessive stresses from repeated flex and tensile deformations cause cracking, reducing air pressure retaining properties
Solution Approach 1:
The patent applies the intermediary principle by introducing a thermoplastic elastomer layer as a mediator between the EVOH-containing layer and the tire structure. This elastomer layer acts as a stress-absorbing intermediary that protects the EVOH layer from excessive stresses during flex and tensile deformations, preventing crack formation and maintaining air pressure retaining properties while preserving gas permeation prevention.
Data Source
AI summary
A laminate comprising at least one layer of a first thermoplastic resin composition alternately stacked with at least two layers of a second thermoplastic resin composition so that the outermost layers are the layers of the second thermoplastic resin composition, wherein the first thermoplastic resin composition comprises at least one selected from the group consisting of ethylene-vinyl alcohol copolymer and modified ethylene-vinyl alcohol copolymers, and the second thermoplastic resin composition has a different composition from the first thermoplastic resin composition, and wherein, in any adjacent pair of the layer of the first thermoplastic resin composition and the layer of the second thermoplastic resin composition, the layer of the first thermoplastic resin composition and the layer of the second thermoplastic resin composition have a specific tensile modulus ratio and a specific thickness ratio.