Bulked Continuous Carpet Filament From Recycled PET With Vacuum Debulking
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Solution Overview
Problem
The high cost of virgin polyethylene terephthalate (PET) polymer and the environmental benefits of using recycled PET polymer necessitate the development of methods and systems to produce bulked continuous carpet filament entirely from recycled PET polymer, while overcoming challenges associated with contaminants and quality issues in recycled materials.
Innovation Solution
A melt processing unit is used to melt and separate polymer flakes into multiple streams, exposing them to a controlled low-pressure environment before recombining them into a single stream for spinning into bulked continuous carpet filament, utilizing a pressure regulation system to maintain pressures between 0 and 5 millibars, and optionally including a crystallization step to enhance quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If recycled PET polymer is used instead of virgin PET polymer, then cost is reduced and environmental benefits are improved, but quality issues and contaminants worsen
Solution Approach 1:
The polymer melt is divided into multiple streams (at least 8 streams) through a separation element, allowing each stream to be independently exposed to reduced pressure for debulking. This segmentation enables thorough removal of contaminants and air bubbles from recycled PET while maintaining production efficiency
Solution Approach 2:
The process changes the pressure parameter by exposing multiple polymer melt streams to reduced pressure (0.5-12 millibars) in a vacuum chamber. This parameter change enables effective removal of volatiles and contaminants from recycled PET, improving the quality and reliability of the final filament product
2Reliability
If multiple melting and cooling cycles are used to process recycled PET, then quality is improved, but productivity is reduced and time is increased
Solution Approach 1:
The process maintains continuous operation by melting polymer flakes once and immediately processing the resulting melt through the multi-stream separation and debulking system. This continuous action eliminates the need for repeated melting and cooling cycles, maintaining high productivity while ensuring quality through effective contaminant removal
Solution Approach 2:
The polymer flakes are pre-dried in a crystallizer before melting to remove moisture and prepare the material for processing. This preliminary action prevents quality issues during the single melting cycle, eliminating the need for subsequent reprocessing while maintaining high production efficiency
3Manufacturing precision
If polymer melt is exposed to high pressure, then manufacturing precision is maintained, but the need for debulking and quality improvement is reduced
Solution Approach 1:
Instead of using high pressure to maintain manufacturing precision, the process inverts the approach by using reduced pressure (vacuum) to achieve the desired outcome. The vacuum environment removes air bubbles and volatiles from the polymer melt, improving intrinsic viscosity and product quality while maintaining precise control over the processing parameters
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 produces high-quality recycled PET polymer with an intrinsic viscosity of at least 0.79 dL/g, enabling the production of bulked continuous carpet filament with 100% recycled content, improving efficiency and reducing the need for multiple melting and cooling cycles.
Implementation Method 1
exposing them to a controlled low-pressure environment before recombining them into a single stream for spinning into bulked continuous carpet filament, utilizing a pressure regulation system to maintain pressures between 0 and 5 millibars
Data Source
AI summary
Systems for manufacturing bulked continuous carpet filament from polymer, where the systems are configured for: (1) passing polymer flakes through a crystalliers; (2) melting the polymer to create a first single stream of polymer melt; (3) separating the first single stream of polymer melt into multiple streams of polymer melt; (4) exposing the multiple streams of polymer melt to a pressure of between about 0 millibars and about 25 millibars in a chamber; (5) recombining the multiple streams of polymer melt into a second single stream of polymer melt; and (6) providing the second single stream of polymer melt to one or more spinning machines that are configured to form the second single stream of polymer melt into bulked continuous carpet filament.