Polyester Tire Cord Spinning for High Toughness at Lower Weight
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Solution Overview
Problem
Existing tire cords fail to simultaneously achieve high strength, high modulus, low shrinkage, and high elongation, which are necessary for weight reduction and improved durability in tires.
Innovation Solution
A tire cord made from a polyester yarn with specific mechanical properties, including 90 mol% polyethylene terephthalate, tenacity of 8.0 g/d or more, LASE@2% of 1.1 g/d or more, LASE@5% of 2.5 g/d or less, and toughness of 183 g/d.mm or more, is produced using a high multifilament spinning method with controlled spinning conditions to maintain these properties during post-processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the fineness of polyester tire cords is lowered to reduce tire weight, then tire weight is reduced, but the pressure in the spinning pack and spinneret is reduced, causing the toughness of the tire cord to be reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling spinning conditions including spinning pack pressure (1800-2500 psi), polymer discharge rate (2.0 m/min or less), and shear rate (220-260 1/sec) to produce fine-denier yarns (2.5-3.5 denier) with high toughness. This resolves the contradiction by optimizing process parameters to maintain strength while reducing fineness.
Solution Approach 2:
The patent uses composite materials by combining polyester multifilaments (200-2000 filaments) with specific adhesive layers through impregnation and heat treatment. This composite structure maintains high toughness and mechanical properties even when individual filament fineness is reduced, enabling weight reduction without sacrificing strength.
2Weight of moving object
If the fineness of polyester tire cords is lowered, then tire weight is reduced, but it becomes difficult to satisfy all required physical properties (modulus, toughness, shrinkage) simultaneously
Solution Approach 1:
The patent implements comprehensive parameter control across multiple stages: spinning parameters (pressure, discharge rate, shear rate), drawing parameters (temperature, speed ratio), and heat treatment parameters (temperature, time). This multi-stage parameter optimization enables simultaneous achievement of high modulus, toughness, and controlled shrinkage in fine-denier tire cords.
Solution Approach 2:
The patent applies preliminary action by pre-orienting polymer chains during spinning and drawing processes before final tire cord formation. The spinning pack and spinneret design pre-condition the molten polyester to achieve high molecular orientation, which is then locked in during drawing and heat treatment, ensuring all physical properties are satisfied before the cord is fully formed.
3Strength
If high tenacity and high modulus are achieved in polyester yarn, then strength properties are improved, but shrinkage control becomes more difficult
Solution Approach 1:
The patent controls shrinkage through parameter changes in the heat treatment process (temperature and time) and drawing process (temperature and speed ratio). By optimizing these parameters, the patent achieves high tenacity and modulus through molecular orientation while simultaneously controlling shrinkage to meet specifications, resolving the contradiction between strength and dimensional stability.
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 tire cord achieves high tenacity, modulus, and low shrinkage, enabling weight reduction and improved rolling resistance while maintaining excellent mechanical properties.
Implementation Method 1
discharging the molten polyester using a spinneret to form a filament
Implementation Method 2
a nozzle unit having a shear rate of 220 to 260 1/sec
Implementation Method 3
cooling the semi-solidified filament discharged from the spinneret
Implementation Method 4
cooling the semi-solidified filament discharged from the spinneret
Implementation Method 5
bundling, stretching and winding the cooled filaments
Data Source
Figure 1
AI summary
Provided herein is a high tenacity tire cord having a tenacity of 8.0 g/d or more, a LASE@2% of 1.1 g/d or more, and a LASE@5% of 2.5 g/d or less, and a toughness of 183 g/d.mm or more according to the ASTM D 885 standard test method, and satisfying a side wall indentation (SWI) value of 3.6% or less, and a manufacturing method thereof.