Recycled PET Yarn for Tire Cords With Multi-Stage Drawing
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Solution Overview
Problem
Tire cords produced using recycled polyethylene terephthalate exhibit poor molding processability, impact resistance, heat resistance, and marketability due to property degradation, necessitating a technology that minimizes property deterioration while being environmentally friendly.
Innovation Solution
A method involving the production of recycled polyethylene terephthalate yarn through melting, spinning, and multi-stage drawing using specific godet rolls with controlled draw ratios and speeds, followed by winding, to achieve properties comparable to virgin polyethylene terephthalate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If recycled polyethylene terephthalate is used to produce tire cords, then environmental friendliness is improved, but physical properties such as impact resistance and heat resistance deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the isophthalic acid content (1.0 mol% or less) in the recycled PET chips and optimizing the multi-stage drawing parameters (draw ratios of 1.5-2.45, specific godet roll speeds including 5,500-7,000 m/min for the fourth set). These parameter optimizations resolve the contradiction by maintaining physical properties comparable to virgin PET while using recycled material, thereby achieving both environmental friendliness and mechanical strength.
2Reliability
If recycled polyethylene terephthalate is used to produce tire cords, then environmental friendliness is improved, but molding processability deteriorates
Solution Approach 1:
The patent resolves the contradiction between environmental friendliness and molding processability through parameter changes in the drawing process. By controlling the draw ratio within 1.5-2.45 and optimizing the multi-stage drawing conditions (including specific godet roll speeds), the yarn achieves good processability despite using recycled PET with isophthalic acid content of 1.0 mol% or less, thus maintaining both environmental benefits and manufacturing ease.
3Reliability
If recycled polyethylene terephthalate is used to produce tire cords, then environmental friendliness is improved, but appearance deteriorates
Solution Approach 1:
The patent addresses the contradiction between environmental friendliness and appearance by optimizing the multi-stage drawing parameters. By controlling the draw ratio (1.5-2.45) and implementing specific drawing speeds (5,500-7,000 m/min for the fourth godet roll set), the yarn achieves smooth surface and uniform structure, resolving the appearance issues associated with recycled PET while maintaining environmental benefits.
4Strength
If multi-stage drawing with five or more sets of godet rolls is used, then physical properties such as tenacity and dimensional stability are improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the drawing process into five or more distinct stages, each with specific godet roll speed ratios. This segmentation allows progressive orientation and crystallization of the yarn, achieving high tenacity (8.5 g/d or more) and dimensional stability (E-S of 11.0% or less) through controlled multi-stage deformation rather than a single complex operation.
Solution Approach 2:
The patent implements dynamics by varying the speeds of different godet roll sets in the multi-stage drawing process. The fourth set of godet rolls operates at 5,500-7,000 m/min, creating dynamic speed differences that control the drawing ratio (1.5-2.45) and enable progressive yarn orientation. This dynamic control achieves superior physical properties while managing device complexity through systematic speed variation.
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 recycled polyethylene terephthalate yarn and tire cord exhibit enhanced tenacity, dimensional stability, and fatigue resistance, making them environmentally friendly with properties similar to virgin polyethylene terephthalate.
Implementation Method 1
melting recycled polyethylene terephthalate chips and spinning the melt through a spinning nozzle
Implementation Method 2
drawing the spun yarn in multiple stages using an apparatus including five or more sets of drawing godet rolls
Implementation Method 3
drawing the spun yarn in multiple stages using an apparatus including five or more sets of drawing godet rolls
Data Source
Figure 1
AI summary
A method for producing a recycled polyethylene terephthalate yarn according to the present invention includes: melting recycled polyethylene terephthalate chips and spinning the melt through a spinning nozzle, thereby producing a spun yarn; and drawing the spun yarn in multiple stages using an apparatus including five or more sets of drawing godet rolls, followed by winding; wherein the recycled polyethylene terephthalate chips contain isophthalic acid in an amount of 1.0 mol% or less; wherein the drawing is performed at a draw ratio of 1.5 to 2.45; and wherein a fourth set of godet rolls among the five or more sets of drawing godet rolls has a speed of 5,500 m/min to 7,000 m/min. The recycled polyethylene terephthalate yarn produced by the production method has a tenacity of 8.5 g/d or more and a dimensional stability (E-S) of 11.0% or less.