Colored Recycled PET Extrusion With Vacuum Filtration for Carpet Filament
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Solution Overview
Problem
The high cost of virgin PET polymer and the desire for environmental benefits necessitate the development of a process to produce bulked continuous carpet filament from 100% recycled PET polymer, while effectively removing contaminants and water to achieve polymer quality comparable to virgin PET.
Innovation Solution
A system comprising a grinding unit, washing unit, and extruder is used to process recycled PET bottles into bulked continuous carpet filament, utilizing a multi-screw extruder with pressure regulation to maintain low pressures, adding color concentrate, and employing vacuum and filtration to purify the polymer melt, resulting in a recycled PET polymer with intrinsic viscosity similar to virgin PET.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple melting and cooling cycles are used to process recycled PET, then contaminants and water can be removed, but energy consumption increases and polymer integrity deteriorates
Solution Approach 1:
The patent applies preliminary action by performing vacuum drying and filtration on the recycled PET flakes before extrusion. The flakes are dried under vacuum to remove moisture and then filtered to remove contaminants prior to the melting process, eliminating the need for multiple subsequent melting and cooling cycles while achieving high polymer quality with minimal energy input
2Reliability
If multiple melting and cooling cycles are used to process recycled PET, then contaminants and water can be removed, but the number of processing steps increases
Solution Approach 1:
The patent performs necessary purification actions before extrusion by drying flakes under vacuum and filtering them to remove contaminants and moisture. This preliminary treatment consolidates multiple purification steps into a single pre-processing stage, eliminating the need for repeated melting and cooling cycles and simplifying the overall process flow
Solution Approach 2:
The patent extracts and removes contaminants and moisture from the recycled PET flakes through vacuum drying and filtration before extrusion. By separating these purification steps from the main extrusion process and performing them beforehand, the system achieves high polymer quality without requiring multiple complex processing cycles
3Reliability
If conventional extrusion is used without pressure regulation, then the process is simpler, but volatile contaminants are not effectively removed
Solution Approach 1:
The patent applies parameter changes by implementing pressure regulation within the extruder to maintain optimal conditions for removing volatile contaminants. By controlling and adjusting the pressure parameter during extrusion, the system effectively eliminates volatile impurities while maintaining a relatively simple process configuration
Solution Approach 2:
The patent employs feedback through a pressure regulation system that monitors and adjusts pressure conditions during extrusion to optimize contaminant removal. This closed-loop control ensures volatile contaminants are effectively removed while maintaining process simplicity through automated pressure management
4Adaptability or versatility
If colored recycled PET flakes are used, then the variety of recyclable materials increases, but additional color concentration is required
Solution Approach 1:
The patent applies local quality by selectively adding color concentrate only to the colored flakes portion of the mixture. Since the input contains up to 10% colored flakes and 90% clear flakes, the color concentrate is locally applied only where needed to recolor the colored portion, significantly reducing the total amount of color concentrate required compared to recoloring the entire batch
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 achieves high-quality recycled PET polymer suitable for producing bulked continuous carpet filament, reducing energy consumption and maintaining polymer integrity by minimizing melting and cooling cycles, while achieving comparable quality to virgin PET.
Implementation Method 1
reducing a pressure within the extruder to between about 0 millibars and about 12 millibars
Implementation Method 2
filtering the polymer melt through at least one filter
Implementation Method 3
melt the concentrate-polymer mixture to produce a polymer melt
Data Source
AI summary
A system comprising: (1) a grinding unit configured to receive and grind recycled PET bottles into a group of polymer flakes comprising up to about ten percent colored polymer flakes and balance substantially clear polymer flakes; (2) a washing unit configured to wash the group of polymer flakes; and (3) an extruder configured to extrude material in a plurality of different extrusion streams. The extruder may be further configured to: (1) receive a concentrate-polymer mixture comprising a mixture of the polymer flakes and a color concentrate; (2) melt the concentrate-polymer mixture to produce a polymer melt; (3) reduce a pressure within the extruder; and (4) pass the polymer melt through the extruder so that the polymer melt is divided into the plurality of extrusion streams. The system may then filter the polymer melt through at least one filter and form the polymer melt into bulked continuous carpet filament.