Plastic Recycling Filter Element Vacuum Degassing
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Solution Overview
Problem
Existing plastic recycling methods require lengthy degassing processes, leading to potential decomposition and limited degassing capacity, which complicates the production of high-purity plastic melts due to the need for multiple degassing stages and long dwell times.
Innovation Solution
A method and device that integrate filtration and degassing into a single process step, utilizing a vacuum atmosphere to achieve large-area contact zones for efficient volatile constituent removal, allowing for reduced dwell times and high-purity plastic production through multi-stage filtration and degassing, with optional additional homogenization in a dwell reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If long dwell sections are used in the screw extruder to increase contact time between plastic melt and vacuum atmosphere, then degassing capacity is improved, but dwell time increases leading to decomposition risk
Solution Approach 1:
The patent combines filtration and degassing into a single integrated process step by positioning filter elements directly in the vacuum atmosphere zone. The filter elements serve dual functions: filtering solid particles from the plastic melt while simultaneously enabling volatile constituent removal through the vacuum atmosphere contact at their surfaces. This merging eliminates the need for separate long dwell sections while maintaining effective degassing capacity.
Solution Approach 2:
The patent transitions from linear degassing along the screw extruder length to a radial/dimensional approach by creating large-area contact zones around the filter elements in the vacuum atmosphere. The filter elements act as centralized degassing points with surface areas that radiate vacuum contact to the plastic melt, effectively increasing degassing capacity without extending the linear dwell time through the extruder.
2Reliability
If multiple degassing stages are used to increase degassing capacity, then volatile constituent removal is improved, but device complexity and process steps increase
Solution Approach 1:
The patent merges multiple degassing functions into a single integrated zone by positioning multiple filter elements within one vacuum atmosphere section. Each filter element provides both filtration and degassing functions, and their combined surfaces create large-area vacuum contact zones that achieve high degassing capacity without requiring multiple separate degassing stages or sections in the extruder.
Solution Approach 2:
The filter elements serve universal dual functions: they simultaneously act as filtration media for solid particle removal and as degassing surfaces for volatile constituent removal through vacuum contact. This multi-functionality eliminates the need for separate filtration and degassing stages, reducing device complexity while maintaining effective degassing capacity.
3Productivity
If large-area contact zones between plastic melt and vacuum atmosphere are created, then volatile constituent removal efficiency is improved, but apparatus requirements increase
Solution Approach 1:
The patent utilizes the porous structure of the filter elements to create large-area contact zones. The porous material provides extensive surface area within a compact form factor, allowing the plastic melt to contact the vacuum atmosphere through the filter surfaces. This achieves high volatile constituent removal efficiency without requiring large-volume apparatus or complex vacuum chamber configurations.
Solution Approach 2:
The patent creates large-area contact zones by utilizing the radial surface area of filter elements positioned in the vacuum atmosphere, rather than requiring long linear sections. The filter element surfaces provide two-dimensional contact areas that efficiently transfer volatile constituents from the plastic melt to the vacuum atmosphere without extending the extruder length or requiring additional degassing apparatus.
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 enables the production of high-purity plastic melts with reduced process steps and dwell times, achieving intrinsic viscosity values greater than 0.6 and 0.8, while minimizing apparatus requirements and allowing for continuous melt flow to final processing.
Implementation Method 1
the filtered plastic melt can be degassed directly by filtration in a vacuum atmosphere. Large-area contact zones between the plastic melt and the vacuum atmosphere can thus be achieved so that the volatile constituents can be released from the plastic melt
Implementation Method 2
The vacuum atmosphere is set to a vacuum in the range of from 0.5 mbar to 50 mbar
Implementation Method 3
so that the volatile constituents can be released from the plastic melt
Implementation Method 4
By a first filtration of the plastic melt under an excess pressure atmosphere, it is possible in this way first of all to remove coarse solid particles and impurities from the melted recyclable material. The subsequent second filtration with integrated degassing can be carried out correspondingly finely in order to remove the solids first before the actual degassing
Implementation Method 5
the plastic melt is additionally homogenized to a high degree, enabling it subsequently to be discharged directly for final processing. In particular, in addition to filtration and degassing, the viscosity of the melt can also be built up again
Data Source
AI summary
Techniques recycle plastics in multiple successive process steps. A polymer, preferably a recyclable material, is melted using a discharge extruder, filtered using a first filter device under a positive pressure atmosphere, filtered and degassed using a degassing device, and discharged using a discharge extruder. The degassing device has at least one filter element and a vacuum chamber with a negative pressure atmosphere for filtering and degassing purposes, wherein the plastic melt can be conducted into the negative pressure atmosphere of the vacuum chamber through the filter element.