Pneumatic Tire Inner Liner Using Grafted EVOH Composite
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Solution Overview
Problem
The air permeability of pneumatic tires incorporating ethylene-vinyl alcohol copolymers increases due to repeated deformation, leading to a change in air permeability over time, which is undesirable for maintaining tire performance.
Innovation Solution
A thermoplastic elastomer composition is developed, comprising a modified ethylene-vinyl alcohol copolymer grafted with aliphatic polyester, a polyamide resin, and a modified rubber containing acid anhydride or epoxy groups, which forms a matrix phase and dispersed phase respectively, enhancing the tire's air permeability and resistance to fatigue-induced changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ethylene-vinyl alcohol copolymer is incorporated to improve air permeability, then air permeability is reduced initially, but air permeability increases due to repeated deformation (fatigue)
Solution Approach 1:
The patent uses a composite material system consisting of ethylene-vinyl alcohol copolymer (EVOH) combined with polypropylene or polystyrene. This composite structure leverages the excellent gas barrier properties of EVOH while the polypropylene or polystyrene component provides structural stability and resistance to deformation-induced permeability changes, thereby resolving the contradiction between achieving low initial air permeability and maintaining stability under repeated deformation
Solution Approach 2:
The patent modifies the physical and chemical parameters of the EVOH by combining it with other polymers in specific ratios and configurations. This parameter change approach transforms the pure EVOH material into a composite system where the overall air permeability and its stability under fatigue are optimized, converting the harmful effect of EVOH's poor fatigue resistance into a beneficial stable performance
2Reliability
If ethylene-vinyl alcohol copolymer is used to reduce air permeability, then gas barrier properties are improved, but heat drawability deteriorates making deep drawing difficult
Solution Approach 1:
The patent creates a composite material combining EVOH with polypropylene or polystyrene, where the polypropylene or polystyrene component compensates for the poor heat drawability of EVOH. This composite approach maintains the excellent gas barrier properties of EVOH while introducing materials with superior processability and heat drawability, enabling both deep drawing and effective air permeability control
Solution Approach 2:
The patent applies different material properties to different functional requirements within the same tire component. The EVOH provides local gas barrier functionality, while the polypropylene or polystyrene provides local structural support and processability. This local quality differentiation allows the inner liner to simultaneously achieve low air permeability and good heat drawability for manufacturing
Data Source
AI summary
Provided is a pneumatic tire which has low air permeability and undergoes a small change in air permeability due to fatigue. A pneumatic tire of the present invention contains a layer which is formed of a thermoplastic elastomer composition that is composed of (A) a modified ethylene-vinyl alcohol copolymer to which an aliphatic polyester is grafted, (B) a polyamide resin and (C) a modified rubber having an acid anhydride group or an epoxy group.