Reclaimed Polymer Purification via Leaching and Dissolution
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Solution Overview
Problem
Current methods for purifying contaminated reclaimed polymers, such as those from recycled plastics, are inadequate in removing both surface and bulk contaminants efficiently, particularly in high molecular weight plastics like films, and often result in polymeric cross-contamination, failing to produce 'virgin-like' polymers that are colorless and odorless.
Innovation Solution
A method involving flooded leaching and purification steps using a leaching solvent and pressurized solvent to remove contaminants like alkyl phenols, bisphenols, dioxins, and phthalates from reclaimed polymers, followed by dissolution, settling, filtration, and adsorptive filtration to produce a purer polymer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional purification methods are used on reclaimed polymers, then the process is simple and cost-effective, but the polymer remains highly contaminated with impurities and cannot achieve virgin-like quality
Solution Approach 1:
The purification process is divided into multiple sequential stages: initial washing to remove surface contaminants, followed by dissolution in a selective solvent to separate the polymer from bulk contaminants, then filtration to remove insoluble impurities, and finally precipitation to recover the purified polymer. This segmentation allows each stage to target specific types of contaminants, achieving high purity while keeping individual steps relatively simple.
Solution Approach 2:
A selective solvent acts as an intermediary medium that dissolves the reclaimed polymer while leaving most contaminants undissolved. This intermediary enables the separation of the polymer from contaminants based on solubility differences, achieving high purification efficiency without requiring complex equipment or multiple chemical treatment steps.
2Manufacturing precision
If multiple purification stages are implemented to remove both surface and bulk contaminants, then contaminant removal efficiency increases, but processing time and operational complexity increase
Solution Approach 1:
The dissolution step continuously extracts the polymer from the contaminant matrix, and the filtration step continuously removes insoluble impurities from the solution. These continuous operations eliminate the need for repeated batch processing, reducing total processing time while maintaining high contaminant removal efficiency across multiple contaminant types.
Solution Approach 2:
The process exploits changes in temperature and solvent composition parameters to control polymer solubility. By adjusting these parameters, the polymer can be selectively dissolved and then precipitated in a controlled manner, enabling efficient separation from contaminants in a single pass through the dissolution-filtration-precipitation sequence rather than requiring multiple sequential treatments.
3Manufacturing precision
If aggressive cleaning methods are used to remove all contaminants, then purity increases, but polymeric cross-contamination occurs and the polymer structure is compromised
Solution Approach 1:
The selective solvent serves as a gentle intermediary that dissolves the polymer without degrading its molecular structure. Unlike aggressive chemical treatments that may break polymer chains or cause cross-contamination, the solvent selectively interacts with the polymer based on solubility parameters, preserving the polymer's structural integrity while achieving high purity separation from contaminants.
Solution Approach 2:
The process replaces mechanical or chemical force-based purification methods with a thermodynamic approach based on solubility differences. Instead of using harsh chemicals or high-energy treatments that could damage the polymer, the method uses controlled dissolution and precipitation, which are gentler processes that maintain polymer stability while achieving effective contaminant removal.
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 method achieves a significant reduction in contaminant levels, producing a polymer that is essentially contaminant-free, colorless, and odorless, suitable for demanding applications, with an average removal efficiency greater than 55% in multiple stages, and efficiently handles high molecular weight plastics.
Implementation Method 1
decontaminating and dissolving plastics, including high molecular weight plastics, at temperatures below the plastics melting points
Implementation Method 2
The decontaminated and dissolved plastic is then settled and filtered to remove insoluble contaminants
Implementation Method 3
The dissolved plastic is then separated from soluble contaminants through a combination of phase separation, filtration, and precipitation
Implementation Method 4
separated from soluble contaminants through a combination of phase separation, filtration, and precipitation
Implementation Method 5
The decontaminated and dissolved plastic is then settled and filtered to remove insoluble contaminants
Implementation Method 6
separated from soluble contaminants through a combination of phase separation, filtration, and precipitation
Data Source
AI summary
A method for purifying a reclaimed polymer to a purer polymer is disclosed. In embodiments of the present invention, the method involves obtaining a reclaimed polymer, leaching various contaminants with a leaching solvent producing a leached polymer, and then dissolving the leached polymer in a solvent to produce a first solution comprising the dissolved polymer. The first solution is settled, filtered, and extracted. A purer polymer is separated from the resulting solution.