Polymer Dissolution Purification for Recycling
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Solution Overview
Problem
Recycling of high-value polymer materials like aromatic polyesters is economically challenging due to impurities and degradation from mechanical processing at high temperatures, which degrades the quality of the recycled polymer feedstock.
Innovation Solution
The method involves dissolving polymers in recoverable solvents at lower temperatures, purifying the solutions to remove contaminants, and recovering the solvents efficiently, allowing for lower energy processing and maintaining the molecular weight and quality of the polymer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical recycling is performed at high temperature (>250°C), then the polymer can be processed and recycled, but the color degrades and molecular weight decreases, reducing optical and mechanical properties
Solution Approach 1:
The patent changes the fundamental processing parameter from temperature-based melting to solvent-based dissolution. By using selective solvents at lower temperatures (below 250°C), the method maintains molecular weight and optical properties while enabling recycling. The solvent choice (e.g., phenolic compounds, carboxylic acids) is specifically optimized to dissolve target polymers without degrading their molecular structure.
Solution Approach 2:
The patent introduces a solvent as an intermediary substance to facilitate polymer processing. The solvent acts as a medium that dissolves the polymer, allows for purification of contaminants, and then can be recovered and reused. This intermediary approach avoids direct high-temperature thermal processing that causes degradation.
2Productivity
If high temperature processing is used for polymer recycling, then the recycling process can proceed, but energy consumption increases and quality of recycled feedstock decreases
Solution Approach 1:
The patent fundamentally changes the energy parameter by replacing high-temperature thermal processing with low-temperature solvent-based processing. The operating temperature is reduced from >250°C to below 250°C, significantly reducing energy consumption while maintaining recycling effectiveness.
Solution Approach 2:
The patent replaces the thermal-mechanical recycling system with a chemical-solvent system. Instead of using heat and mechanical force to melt and reprocess polymers, the method uses chemical dissolution, filtration, and solvent recovery, which operates at lower energy levels.
3Ease of manufacture
If conventional solvents are used for polymer recovery, then dissolution can occur, but the solvents present challenges including high cost, low recovery, degradation, and safety concerns
Solution Approach 1:
The patent optimizes solvent selection based on specific parameters: selectivity for target polymer, boiling point for easy recovery, low toxicity for safety, and cost-effectiveness. The chosen solvents (phenolic compounds, carboxylic acids, esters) are specifically selected to balance dissolution capability with ease of recovery and safety.
Solution Approach 2:
The patent implements a solvent recovery and reuse system. After the polymer is dissolved, processed, and purified, the solvent is recovered through methods such as distillation, evaporation, or precipitation, and then reused in subsequent processing cycles. This reduces solvent cost and environmental impact while maintaining process effectiveness.
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 reduces temperature requirements, minimizes physical and optical degradation, and enables the recovery of high-quality polymer feedstocks with a high solvent recovery rate, making the recycling process more economical and efficient.
Implementation Method 1
dissolving at least one polymer in a solvent, thereby generating a dissolved polymer solution
Implementation Method 2
purifying the dissolved polymer solution thereby forming a purified dissolved plastic solution
Implementation Method 3
Examples of the step of purifying the dissolved polymer solution include filtration, carbon filtration and/or ion exchange
Implementation Method 4
recovering the solvent by treating the purified dissolved polymer solution thereby generating a recovered solvent and a purified recycled polymer
Implementation Method 5
Examples of the step of recovering the solvent include membrane filtration, evaporation, distillation, spray drying, precipitation and/or devolatilizing extrusion
Data Source
AI summary
Described herein are systems and methods for the recycling of polymer materials that utilize recoverable solvents to efficiently produce high quality valuable polymer while removing contaminants such as metals, dyes or fibers present in the product to be recycled. The described methods may reduce temperature requirements, both reducing the energy requirements as well as providing higher quality recycled feedstocks by, for example, reducing discoloration due to high temperature processing.