Polyether Ester Polyols from Recycled Polyester for Dyeable Spandex
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Solution Overview
Problem
Current methods for recycling polyester plastics are inefficient due to high quality requirements and complex chemical decomposition processes, and spandex production faces challenges with poor dye uptake and high costs, especially when using recycled materials.
Innovation Solution
A method for preparing polyether ester polyols using recycled polyesters as raw materials through a transesterification reaction, which can be used to produce spandex with improved dyeability and mechanical properties, and polyurethane products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional polyester recycling methods (melt pelletizing or chemical decomposition) are used, then recycled plastic can be obtained, but the process is complex and requires high quality standards for the recycled material
Solution Approach 1:
The invention changes the chemical parameters of the recycling process by using transesterification reaction conditions (specific temperature range, catalyst selection, molar ratios) to convert recycled polyester directly into polyether ester polyol with desired molecular weight and structure, eliminating the need for multiple purification and reprocessing steps
Solution Approach 2:
The invention introduces a chemical intermediary approach where recycled polyester is converted through transesterification into polyether ester polyol, which then serves as the soft segment for spandex synthesis. This intermediary transformation allows direct utilization of recycled material without stringent quality requirements
2Reliability
If polytetrahydrofuran ether diol is used as the soft segment for spandex production, then spandex with balanced performance can be obtained, but the cost is high and recycled materials cannot be utilized
Solution Approach 1:
The invention changes the chemical structure parameters of the soft segment from polytetrahydrofuran ether diol to polyether ester polyol with specific molecular weight distribution and end-group composition, achieving comparable elastic performance while enabling the use of lower-cost recycled polyester feedstock
Solution Approach 2:
The invention enables the recycling system to serve itself by converting waste polyester into a functional raw material (polyether ester polyol) that can be directly used in spandex production, creating a closed-loop system where the end product of recycling becomes the input for high-value application
3Ease of manufacture
If conventional spandex is dyed with disperse dyes or acid dyes, then coloring can be achieved, but the dye uptake rate and fixation rate are poor
Solution Approach 1:
The invention modifies the local chemical quality of the spandex molecule by incorporating carboxyl-containing chain extenders that introduce polar carboxyl groups into the hard segment structure. These localized polar regions enhance dye affinity and binding strength without altering the overall spandex architecture or elastic 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 simplifies the production process, utilizes recycled resources, and enhances spandex's dye uptake and mechanical properties, making it suitable for large-scale industrial application.
Implementation Method 1
the main method for recycling polyester plastics is to melt down and pelletize plastic bottle flakes providing a recycled material which is then reprocessed into plastic products
Data Source
AI summary
The present invention provides a method for preparing polyether ester polyols and products thereof. The method involves adding polyether diols and polyesters as raw materials into a reaction kettle, heating the reaction kettle to the reaction temperature to carry out a transesterification reaction, and distilling off the small-molecule polyols produced in the transesterification reaction by means of vacuum distillation, thereby preparing the polyether ester polyols. Wherein, the polyester contains an aromatic dibasic acid polyol ester structure; the polyether diols have a degree of polymerization of 2-20 and a molecular weight of 100-1000; the molar ratio of the aromatic group structure in the polyether diol to those in the polyester is greater than 1.05:1; and the reaction temperature is above the boiling point of the small-molecule polyols and below the boiling point of the polyether diols. The method provided by the present invention can directly process recycled polyesters into polyether ester polyols suitable for the production of polyurethane elastic fibers, which simplifies the polyether ester polyols production process for spandex production. While utilizing recycled resources, it also expands the source of raw materials for polyurethane elastic fibers. Additionally, the present invention provides an easily dyeable spandex prepared using polyether ester polyol and a preparation method thereof. In the process of preparing spandex, the polyether ester polyol provided by the present invention is added to the diol raw materials, causing the molecular soft segment of the prepared spandex fiber to contain a specific aromatic group-polyether block structure. Compared with conventional spandex, the easily dyeable spandex of the present invention can increase the dye uptake rate and fixation capacity of spandex for disperse dyes and acid dyes without sacrificing the mechanical properties of the spandex. By adjusting the mass ratio of the above-mentioned aromatic group-polyether block structures in the molecular soft segment of spandex, the spandex has excellent alkali resistance while ensuring an acceptable dye uptake rate and fixation rate.