Melt-Spun PET/PET Elastic Fiber With Six-Reactor Polymerization
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Solution Overview
Problem
Existing methods for producing PET/PET two-component elastic fibers face challenges such as high production costs, low production capacity, and poor product quality stability due to the complexity and inefficiencies in the chip spinning process, particularly in achieving high-viscosity PET/low-viscosity PET composite spinning.
Innovation Solution
A six-reactor polymerization system is used to separately polymerize high-viscosity and low-viscosity PET melts, followed by direct composite spinning, employing a unique reactor design with unequal-length agitating shafts and combined scrapers to control viscosity and reduce residence time, thereby improving production efficiency and reducing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If chip spinning technology is used to produce PET/PET two-component elastic fibers, then composite spinning can be achieved, but the process becomes long and costly with low production capacity and poor product quality stability
Solution Approach 1:
The patent applies preliminary action by pre-processing the PET chips into melts with different viscosities before spinning. The high-viscosity PET chips and low-viscosity PET chips are separately prepared and then fed into the spinning system, eliminating the need for complex on-site chip spinning and preprocessing during production, thereby simplifying the overall process and increasing productivity
Solution Approach 2:
The patent extracts the preprocessing step from the spinning process by preparing the high-viscosity and low-viscosity PET melts separately before spinning. This separates the complex chip spinning operation into simpler melt spinning operations, reducing process complexity and improving production efficiency
2Ease of manufacture
If chip spinning technology is used to produce PET/PET two-component elastic fibers, then composite spinning can be achieved, but production costs increase and product quality stability deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-processing the PET chips into melts with different viscosities before spinning. The high-viscosity PET chips and low-viscosity PET chips are separately prepared and then fed into the spinning system, eliminating the need for complex on-site chip spinning and preprocessing during production, thereby simplifying the overall process and increasing productivity
Solution Approach 2:
The patent changes the viscosity parameter of the PET material by controlling the molecular weight and processing conditions to create distinct high-viscosity and low-viscosity melts. This parameter differentiation allows the two components to exhibit different flow behaviors during spinning, enabling stable composite fiber formation with consistent quality
3Stability of the object's composition
If the viscosity of high-viscosity PET melt is increased to maintain viscosity during transfer, then elastic crimp performance improves, but melt transfer difficulty increases
Solution Approach 1:
The patent uses an intermediary substance (low-viscosity PET melt) to facilitate the transfer of high-viscosity PET melt. The low-viscosity component acts as a carrier that helps transport the high-viscosity material through the spinning system, reducing transfer difficulty while maintaining the high-viscosity component's elastic crimp performance
Solution Approach 2:
The patent creates a composite melt system combining high-viscosity PET and low-viscosity PET. The composite material leverages the flowability of the low-viscosity component to enable easy transfer while the high-viscosity component maintains its elastic properties, achieving both ease of operation and performance
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 method enables the production of high-viscosity PET/low-viscosity PET two-component elastic fibers with enhanced elastic crimp and crimp shrinkage rates, achieving production capacities of up to 160,000 tons/year while significantly reducing production costs.
Implementation Method 1
spinning the high-viscosity PET melt and the low-viscosity PET melt through a same parallel composite spinning assembly to obtain the PET two-component elastic fiber
Implementation Method 2
During the spinning process, due to the different speeds and percents of transition from an orientation state to a crystallization state, the high-viscosity component and the low-viscosity component produce elastic crimp
Data Source
AI summary
The present disclosure relates to a melt-spun high-viscosity PET/low-viscosity PET two-component elastic fiber and a preparation method therefor. The preparation method adopts a six-reactor process. Terephthalic acid and ethylene glycol undergo first and second esterification reactions and first and second prepolymerization reactions, and an obtained ethylene terephthalate prepolymer is respectively introduced into a high-viscosity final polymerization reactor and a low-viscosity final polymerization reactor for polymerization reaction to obtain a high-viscosity melt and a low-viscosity melt, respectively, and then the two melts are spun together. The viscosity of the high-viscosity component can be significantly improved, and a wider range of viscosity difference between the high-viscosity and low-viscosity polyester melts can be obtained. A difference between the intrinsic viscosity of the high-viscosity melt and the intrinsic viscosity of the low-viscosity melt is 0.100-0.550; the prepared PET/PET two-component elastic fiber has high quality and high crimp shrinkage rate.