Drawn PET Fiber Modulus and Dimensional Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current cap ply cords, such as those made of nylon 66 and high modulus low shrinkage PET fibers, face challenges with low modulus and dimensional stability, leading to tire deformation and instability during high-speed driving due to insufficient shrinkage force and heat resistance.
Innovation Solution
A drawn PET fiber with 90 mol% or more PET, high crystallinity (53% or more), low amorphous orientation factor (0.15 or less), and specific birefringence index (0.14 to 0.16) is developed, providing improved modulus and dimensional stability through a heat-treatment process, which is then used to create a PET tire cord suitable for cap ply applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nylon 66 or high modulus low shrinkage PET fibers are used for cap ply cords, then the cord can provide shrinkage force, but the modulus and dimensional stability are insufficient, leading to tire deformation during high-speed driving
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallinity (50-60%) and amorphous orientation factor (0.10-0.20) of PET fibers through specific heat treatment conditions (temperature, time, and initial load). This resolves the contradiction by achieving both high modulus (through optimized crystallinity) and dimensional stability (through controlled amorphous orientation), preventing tire deformation while maintaining structural integrity.
2Strength
If the crystallinity of PET fiber is increased to improve modulus, then the shrinkage force may be reduced, affecting the cord's ability to restrain steel belt movement
Solution Approach 1:
The patent simultaneously optimizes two parameters: crystallinity (50-60%) for modulus and amorphous orientation factor (0.10-0.20) for shrinkage force. This dual-parameter control resolves the contradiction by ensuring that increased crystallinity for higher modulus does not compromise shrinkage force, as the amorphous phase maintains sufficient orientational order to provide thermal shrinkage capability.
3Stability of the object's composition
If the amorphous orientation factor is decreased to improve dimensional stability, then the shrinkage force is improved, but the modulus may be affected
Solution Approach 1:
The patent achieves the optimal balance by controlling the amorphous orientation factor within 0.10-0.20 while maintaining crystallinity at 50-60%. This resolves the contradiction by ensuring that the amorphous phase has sufficient orientation to provide shrinkage force and dimensional stability, while the crystalline phase maintains the necessary modulus for structural support.
4Stability of the object's composition
If heat treatment is applied to improve crystallinity and dimensional stability, then the processing complexity increases, but the fiber properties are significantly improved
Solution Approach 1:
The patent simplifies heat treatment by specifying precise parameter ranges: temperature (200-250°C), time (0.5-2 hours), and initial load (10-30 g/d). These well-defined parameters resolve the contradiction by making the complex heat treatment process controllable and repeatable, achieving high dimensional stability without excessive processing complexity.
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 drawn PET fiber and resulting tire cord exhibit superior shrinkage force, modulus, and dimensional stability, effectively preventing tire deformation and enhancing high-speed driving performance and stability by restraining the movement of steel belts and maintaining tire shape under varying loads and temperatures.
Implementation Method 1
the drawn PET fiber... after heat-treating the same at 230° C. for 1 minute
Implementation Method 2
the crystallinity is 53% or more... after heat-treating the same
Implementation Method 3
the birefringence index is 0.14 to 0.16
Data Source
AI summary
The present invention relates to a drawn PET fiber that can provide a cap ply cord and the like showing more improved modulus and good dimensional stability, a PET tire cord, and a tire including the same. The drawn PET fiber may be a fiber including 90 mol % or more of PET, of which the crystallinity is 53% or more, the amorphous orientation factor (AOF) is 0.15 or less, and the birefringence index is 0.14 to 0.16, after heat-treating the same at 230° C. for 1 minute under the initial load of 20 g/1000 d.