Separating Polymer Layers from Aluminum Foil Using Swelling Fluids
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for recycling laminates in food packaging, such as those used in Tetra Pak cartons, face challenges in separating polyethylene from aluminum foil due to high energy requirements and safety risks associated with using aggressive acid mixtures, which also lead to aluminum loss during the recycling process.
Innovation Solution
A method involving a separation fluid comprising a carboxylic acid and a hydrocarbon solvent, potentially with water and surfactants, is used to separate metal layers from polymer layers in multiple layer materials, allowing for efficient recycling by creating a microemulsion that selectively swells polymer layers without attacking aluminum, thereby enabling the separation of metal and plastic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aggressive acid mixtures (high concentration acetic acid) are used to separate metal and plastic layers, then separation effectiveness is improved, but aluminum loss increases and safety risks increase
Solution Approach 1:
The patent changes the chemical parameters of the separation medium by using diluted acid mixtures (lower concentration) combined with specific surfactants and swelling agents. This parameter change allows effective separation while reducing the aggressive nature of the solution, thereby minimizing aluminum loss and improving safety without sacrificing separation effectiveness.
Solution Approach 2:
The patent introduces surfactants and swelling agents as intermediary substances that facilitate the separation process. These intermediaries enable effective layer separation by modifying the interface properties between metal and plastic layers, allowing separation to occur with less aggressive acid concentrations, thus reducing aluminum attack while maintaining separation effectiveness.
2Productivity
If high temperature (80°C) is used for separation process, then separation effectiveness is improved, but energy consumption increases
Solution Approach 1:
The patent modifies the temperature parameter of the separation process by conducting it at lower temperatures (below 80°C, potentially at ambient or mildly elevated temperatures). This parameter change is compensated by optimizing the chemical composition of the separation medium (using surfactants and swelling agents), which maintains separation effectiveness while significantly reducing energy consumption for heating.
3Productivity
If high concentration (80%) acetic acid is used for separation, then separation effectiveness is improved, but safety risks increase due to proximity to flash point
Solution Approach 1:
The patent changes the concentration parameter of the acid solution from high (80%) to lower concentrations. This parameter change reduces the solution's aggressiveness and moves it further from the flash point, thereby reducing safety risks related to flammability and corrosion, while maintaining separation effectiveness through the addition of surfactants and swelling agents.
Solution Approach 2:
The patent converts the potential harm of aggressive acid solutions into benefit by using diluted acid combinations with surfactants. The reduced acidity lowers safety risks and aluminum loss, while the surfactants compensate for the reduced aggressive power, actually improving overall process safety and sustainability while maintaining separation 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 energy consumption, minimizes aluminum loss, and effectively recovers metal and plastic components, facilitating their reuse in new products while maintaining the integrity of the aluminum layer.
Implementation Method 1
The separation fluid comprises a mixture comprising a carboxylic acid and a swelling agent for the polymer. The swelling agent used is a hydrocarbon solvent in some embodiments of the invention.
Implementation Method 2
the separation fluid further comprises water and at least one surfactant and is a microemulsion
Implementation Method 3
separating the layers in a multiple layer material from each other
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for recycling of packaging material (300) is disclosed. The packaging material (300) comprises a multiple layer material (10) comprising a metal layer (50), at least one polymer layer (20, 40, 60) and, optionally, a paperboard layer (30). The method comprises placing the residual waste in a vat (360) comprising a separation fluid (375) to produce a mixture of metal shreds from the metal layer (50), plastic shreds from the polymer layer (20, 40, 60) and residual components. The separation fluid comprises a mixture comprising at least one swelling agent and at least one carboxylic acid.