Industrial Polyester Catalyst Mixture and Washing Process
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Solution Overview
Problem
Existing methods for producing industrial polyester fibers face challenges in reducing terminal carboxyl end groups, oligomers, and diethylene glycol content, which affect the thermal stability, crystallization, and quality of the final product, leading to issues with high thermal shrinkage and dimensional instability.
Innovation Solution
The use of a polycondensation catalyst mixture of magnesium ethylene glycol and antimony ethylene glycol, followed by boiling and washing the polyester sections with water and a rinsing agent at 120-130°C and 0.2-0.3MPa, to minimize thermal degradation and reduce the content of carboxyl end groups, oligomers, and diethylene glycol, thereby improving the fiber's thermal stability and crystallization integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polycondensation catalysts are used, then the polycondensation reaction proceeds efficiently, but the thermal degradation coefficient increases leading to higher carboxyl end groups and oligomers content
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst system by replacing conventional single-metal catalysts with a dual-metal catalyst system comprising magnesium and antimony compounds. This parameter change optimizes the catalytic activity while reducing thermal degradation, achieving both high productivity and low carboxyl end groups content (≤15 mol/t) and oligomers content (≤0.5%).
2Temperature
If high temperature processing is applied to improve crystallization, then crystallization speed increases, but thermal shrinkage and dimensional instability worsen
Solution Approach 1:
The patent applies local quality by creating a heterogeneous nucleation system where specific nucleating agents are introduced to create localized crystallization centers. This allows crystallization to proceed at lower temperatures with high speed, achieving excellent dimensional stability and low thermal shrinkage without requiring high temperature processing that would cause degradation.
Solution Approach 2:
The patent implements preliminary action by conducting thorough washing of polyester sections at 120-130°C and 0.2-0.3MPa before final processing. This preliminary washing removes residual catalysts, unreacted monomers, and oligomers that could interfere with subsequent crystallization, ensuring optimal crystallization behavior and dimensional stability at lower temperatures.
3Loss of time
If polyester sections are not washed thoroughly, then processing time is reduced, but carboxyl end groups, oligomers, and diethylene glycol content remain high affecting fiber quality
Solution Approach 1:
The patent optimizes washing parameters by using a dual-parameter approach: temperature (120-130°C) and pressure (0.2-0.3MPa). This parameter optimization enables effective removal of carboxyl end groups, oligomers, and diethylene glycol within a reasonable time frame, achieving both efficiency and high manufacturing precision with carboxyl end groups ≤15 mol/t, oligomers ≤0.5%, and diethylene glycol ≤0.5%.
4Manufacturing precision
If oligomers and diethylene glycol content is reduced to improve fiber quality, then crystallization integrity improves, but the complexity of the production process increases
Solution Approach 1:
The patent employs composite materials by creating a dual-functional catalyst system where magnesium and antimony compounds work synergistically. This composite catalyst system achieves superior performance in reducing oligomers and diethylene glycol while maintaining simple production process operations, avoiding the need for complex multi-step purification processes.
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
This approach results in high-strength, low-shrinkage industrial polyester fibers with enhanced dimensional stability and improved crystallization, reducing impurities and heterogeneous nucleation, leading to better fiber quality and reduced thermal shrinkage.
Implementation Method 1
the polycondensation catalysed by a mixture of magnesium ethylene glycol and antimony ethylene glycol
Implementation Method 2
the polyester sections are boiled and washed with water and a rinsing agent at 120-130°C and 0.2-0.3MPa
Data Source
AI summary
A polyester obtained by the esterification of terephthalic acid and ethylene glycol and the polycondensation catalysed by a mixture of magnesium ethylene glycol and antimony ethylene glycol followed by granulation. In the polyester sections, the carboxyl end group is less than 15 mol/t, the mass percentage of oligomer is lower than 0.5%, and weight percentage of diethylene glycol is lower than 0.5%.