Alkaline Delamination of Multilayer Films for Polyolefin Recycling
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Solution Overview
Problem
Current recycling processes for polyolefin mixed streams face challenges in efficiently separating and purifying desired polyolefins due to contamination from non-polyolefin materials and poor mechanical properties of cross-linked polyolefins, leading to low recycling rates and high waste generation.
Innovation Solution
A combined washing/delamination process using an alkaline aqueous solution is employed to treat polyolefin mixed recycling streams. This process involves selecting and enriching the desired polyolefin, milling into flakes, treating with an alkaline solution for delamination, rinsing to remove residues, and sorting to isolate the desired polyolefin, thereby improving the yield and purity of recycled polyolefins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multilayer films are removed from polyolefin mixed recycling streams, then contamination is reduced, but polyolefin recovery is lost
Solution Approach 1:
The multilayer film is segmented into separate layers through delamination, allowing the polyolefin layer to be separated from contaminating layers. This enables recovery of the polyolefin while removing contamination sources.
Solution Approach 2:
An alkaline aqueous solution acts as an intermediary medium to facilitate delamination of the multilayer films. The solution enables separation of layers without requiring removal of the entire multilayer structure, thus preserving polyolefin recovery while reducing contamination.
2Loss of substance
If delamination procedures are added to the recycling process, then polyolefin recovery is improved, but process complexity increases
Solution Approach 1:
The delamination step is merged with the existing washing step in the recycling process. By combining these two functions into a single integrated step using an alkaline aqueous solution, the process achieves improved polyolefin recovery without proportionally increasing process complexity.
Solution Approach 2:
The alkaline aqueous solution serves multiple functions simultaneously: it acts as both a washing medium and a delamination agent. This multi-functionality reduces the need for separate dedicated delamination equipment and procedures, thereby limiting the increase in process complexity.
3Ease of manufacture
If simple washing is used, then process economy is maintained, but delamination efficiency is insufficient
Solution Approach 1:
The washing solution parameters are changed from neutral to alkaline, which fundamentally alters its interaction with multilayer films. This parameter change enables the solution to perform both washing and delamination functions effectively, maintaining process economy while significantly improving delamination efficiency.
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 process effectively delaminates multilayer films, removes contaminants, and enhances the yield of desired polyolefins, thereby improving the efficiency and economy of polyolefin recycling while minimizing waste.
Implementation Method 1
treating the recycling stream (B) enriched in the desired polyolefin (PO) in flaked form with an alkaline aqueous solution
Data Source
AI summary
A method for achieving the simultaneous washing/delamination of multilayer films via treatment with an alkaline aqueous solution during a mechanical recycling process, thereby improving the yield and/or purity of a desired polyolefin.