Decontamination bath and method for decontaminating a plastic article
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Solution Overview
Problem
The challenge in recycling plastic articles lies in the contamination of recycled plastics, which can contain substances like mineral oil hydrocarbons, bisphenols, and flavor compounds, leading to health and safety risks, as well as issues with colored plastics that result in low-quality recyclates due to undesirable color tones and the inefficiency of current decontamination methods.
Innovation Solution
A decontamination bath comprising water, a non-polar organic solvent, an anionic and/or non-ionic surfactant, a resoiling inhibitor, and an alkaline or acidic agent, with a pH adjusted to ≥8 or ≤6, is used to expose plastic articles to temperatures above the glass transition temperature but below the melting temperature, enhancing the affinity of contaminants for the bath and preventing re-attachment during drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional decontamination methods are used, then contaminants can be removed from plastic articles, but the process is inefficient and results in low-quality recyclates with undesirable color tones
Solution Approach 1:
The patent applies parameter changes by adjusting the pH of the decontamination bath to specific ranges (pH ≥ 8 or pH ≤ 6) and controlling the exposure temperature within a specific range (above glass transition temperature but below melting temperature). These parameter optimizations enable efficient contaminant removal while maintaining high recyclate quality without undesirable color tones
Solution Approach 2:
The decontamination bath uses a composite formulation combining water, non-polar organic solvent component (0.1-25 wt%), anionic and/or non-ionic surfactant, resoiling inhibitor, and alkaline or acidic agent. This composite composition synergistically enhances decontamination efficiency while preserving recyclate quality
2Manufacturing precision
If strong oxidation or reduction processes are used to chemically modify coloring agents, then the coloring agent loses its chromophoric property, but the destroyed coloring agent remains in the plastic and limits the use of recyclate
Solution Approach 1:
The patent extracts coloring agents and other contaminants from the plastic matrix through the optimized decontamination bath. By using the composite formulation with surfactants and resoiling inhibitors, the coloring agents are removed from the plastic and transferred to the bath, preventing them from remaining in the recyclate and limiting its usability
3Manufacturing precision
If plastic articles are sorted according to color to achieve high quality colored recycled material, then the sorting process becomes complex and expensive, but mixing colorful plastics during regranulation results in recyclates with undesirable color tones
Solution Approach 1:
The patent removes coloring agents from plastic articles through the decontamination bath, enabling mixed-color plastics to be recycled together without producing undesirable color tones. This extraction approach eliminates the need for complex color-based sorting processes while maintaining recyclate quality
4Adaptability or versatility
If dissolving plastics in chemical recycling is used to handle colored plastics, then the recycling process can handle mixed colors, but the effort involved is considerable and dissolving the plastic contradicts the idea of sustainability
Solution Approach 1:
The patent extracts contaminants and coloring agents from the plastic surface and matrix without dissolving the plastic polymer itself. This selective extraction approach enables processing of mixed-colored plastics while preserving the plastic material for reuse, aligning with sustainability goals by avoiding complete dissolution and reformation
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 improves the quality of recycled plastics by preventing color changes and unpleasant odors, increasing the efficiency of contaminant removal and maintaining the recyclate's quality, while being more sustainable than traditional solvent-based recycling methods.
Implementation Method 1
a non-polar organic solvent component, wherein the amount of the non-polar organic solvent component in the decontamination bath is 0.1 wt % to 25 wt % based on the total weight of the decontamination bath
Implementation Method 2
the decontamination bath comprise the alkaline agent and the pH of the decontamination bath is ≥8, or wherein the decontamination bath comprise the acidic agent and the pH of the decontamination bath is ≤6
Implementation Method 3
optionally an anionic and/or non-ionic surfactant
Implementation Method 4
an alkaline agent or an acidic agent for adjusting the pH of the decontamination bath
Data Source
AI summary
A decontamination bath for decontaminating plastic articles including a contaminant is provided, wherein the decontamination bath includes water, a non-polar organic solvent component, optionally an anionic and/or non-ionic surfactant, a resoiling inhibitor, and an alkaline agent or an acidic agent for adjusting the pH of the decontamination bath, wherein the amount of the non-polar organic solvent component in the decontamination bath is 0.1 wt % to 25 wt % based on the total weight of the decontamination bath, and wherein the decontamination bath comprise the alkaline agent and the pH of the decontamination bath is ≥8, or wherein the decontamination bath comprise the acidic agent and the pH of the decontamination bath is ≤6. A method for decontaminating a plastic article using the above decontamination bath is also provided.