Polyester Tire Cord Microstructure for High-Temperature Dimensional Stability
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Solution Overview
Problem
Polyester tire cords face challenges with poor dimensional stability and heat resistance, especially at high temperatures, which limits their application in ultra-high-performance tires.
Innovation Solution
A polyester tire cord with a 5% LASE of 1.2 g/d or more at 80° C. and 1.0 g/d or more at 120° C., along with a toughness retention rate of 65% or more at these temperatures, is developed. This is achieved through specific spinning and drawing processes that enhance the cord's microstructure and properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high-speed spinning and spin-draft increasing technologies are applied to improve dimensional stability of polyester fiber cord, then dimensional stability is improved, but the strengths of yarns and dipped cords are lowered due to excessive increase in crystallinity
Solution Approach 1:
The patent applies parameter changes by precisely controlling spinning speed (2,500-4,000 m/min) and spin-draft (1,200-2,000) to achieve optimal crystallinity levels. This resolves the contradiction by finding the optimal parameter range that provides sufficient dimensional stability without excessive crystallinity that would reduce strength
Solution Approach 2:
The patent introduces dynamic control of spinning parameters, adjusting spinning speed and spin-draft within specific ranges rather than using fixed values. This allows optimization of both dimensional stability and strength by dynamically balancing crystallinity development
2Strength
If drawing property is increased to improve the strength of the tire cord, then strength is improved, but the processability becomes poor so that the appearance of the yarn becomes poor and the strength utilization rate is reduced
Solution Approach 1:
The patent controls the draw ratio within a specific range (1.3-2.0) to balance strength improvement with processability. By optimizing this parameter, the patent achieves adequate tire cord strength while maintaining good yarn appearance and processing characteristics
3Temperature
If polyester fiber cord is used for tire cords, then higher modulus and lower heat shrinkage rate are achieved compared to nylon, but poor dimensional stability occurs due to reduced elastic modulus and increased shrinkage rate during tire molding at high temperatures
Solution Approach 1:
The patent optimizes spinning parameters (spinning speed, spin-draft) to control the crystallinity and molecular orientation of the polyester fiber. This parameter optimization maintains dimensional stability at high temperatures by preventing excessive shrinkage while preserving the inherent heat resistance of polyester
Solution Approach 2:
The patent applies preliminary high-speed spinning and drawing treatments to establish optimal molecular structure and crystallinity before the tire molding process. This preliminary structuring ensures dimensional stability is maintained during subsequent high-temperature vulcanization
4Stability of the object's composition
If rayon fiber cords are used for high-performance tires, then excellent thermal stability and little deterioration in mechanical properties at high temperatures are achieved, but low strength and high manufacturing costs occur along with environmental pollution problems
Solution Approach 1:
The patent uses polyester fiber, which is cheaper and environmentally friendlier than rayon, by optimizing its processing parameters to achieve rayon-comparable thermal stability. This replaces expensive rayon with cost-effective polyester without sacrificing performance
Solution Approach 2:
The patent modifies spinning parameters to enhance the thermal stability of polyester fiber, making it comparable to rayon. This parameter optimization allows polyester to substitute for rayon in high-performance tires, reducing both cost and environmental impact
Data Source
AI summary
The present invention relates to a polyester tire cord made of polyester yarn and having a 5% LASE of 1.2 g/d or more as measured according to ASTM D885 at 80° C., a 5% LASE of 1.0 g/d or more as measured according to ASTM D885 at 120° C., and a toughness retention rate of 65% or more at 80° C. and 120° C. The tire cord of the present invention has a modulus comparable to that of rayon even in a high-temperature environment at 120° C. or higher, and has excellent dimensional stability and heat resistance, and thus it can be advantageously applied to a high-performance tire.