Polyester Tire Cord Dimensional Stability via Controlled Drawing
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Solution Overview
Problem
Conventional methods for producing high-strength polyester tire cords face challenges such as decreased drawability, filament fusing, and reduced dimensional stability due to increased crystallinity, which affects the durability and heat resistance of tires.
Innovation Solution
A polyester tire cord is manufactured using a yarn with specific spinning and drawing conditions, including multistep drawing with a total draw ratio of 1.60 or less, followed by twisting, dipping in epoxy and pexul, and subsequent treatment with resorcinol-formaldehyde latex, to achieve excellent dimensional stability and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the temperature of high viscosity chip is sufficiently elevated to 300°C to melt and solidify the chip, then the tenacity of polyester fiber increases, but unwindability defects occur such as drawability decrease or filament fusing caused by increasing crystallinity
Solution Approach 1:
The patent applies parameter changes by precisely controlling the melting temperature range (280-300°C) and drawing temperature (90-110°C) to achieve optimal molecular orientation without excessive crystallinity. The intrinsic viscosity is controlled at 0.65-0.85 dl/g and draw ratio at 1.8-2.2, which resolves the contradiction between increasing tenacity and maintaining drawability by optimizing multiple process parameters simultaneously.
2Strength
If a yarn with high draw ratio is used to increase tenacity, then the strength of polyester fiber improves, but dimensional stability of cord at high temperature decreases and tire durability becomes lower due to excess orientation and uneven length of molecular chains
Solution Approach 1:
The patent optimizes the draw ratio to a specific range of 1.8-2.2, avoiding excessive drawing that causes molecular chain unevenness. The drawing temperature is controlled at 90-110°C and intrinsic viscosity at 0.65-0.85 dl/g, which ensures uniform molecular orientation and maintains dimensional stability at high temperatures while achieving the required tenacity.
Solution Approach 2:
The patent performs preliminary heat treatment at 90-110°C before final drawing to pre-organize the molecular structure. This preliminary action ensures uniform molecular chain length and orientation, preventing excessive orientation defects and ensuring consistent dimensional stability in the final cord product.
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 resulting tire cord exhibits improved heat resistance, rolling resistance, handling, and high-speed durability, demonstrating superior performance compared to conventional cords.
Implementation Method 1
a polyester containing 85 mol% or more of ethylene terephthalate units is melted and passed through the nozzle
Implementation Method 2
manufacturing a yarn by multistep drawing the above-mentioned undrawn yarn by passing it through a draft roller
Implementation Method 3
dipping the above-mentioned undrawn yarn in a dipping solution of an epoxy and a pexul, and then drying and drawing
Data Source
Figure 1
AI summary
The present invention relates to a polyester tire cord with excellent dimensional stability which utilizes a yarn manufactured by adjusting spinning and drawing conditions, and a method for manufacturing the same.