Methods for manufacturing bulked continuous filament from recycled PET
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Solution Overview
Problem
Current methods for manufacturing bulked continuous carpet filament from recycled PET are inefficient in removing contaminants and water, and often require multiple melting and cooling cycles, limiting the use of 100% recycled PET due to quality issues.
Innovation Solution
A process involving the preparation of PET flakes from post-consumer bottles, followed by extrusion into multiple streams within a chamber to increase surface area and reduce pressure, allowing for effective removal of contaminants and water, resulting in a high-quality polymer melt suitable for 100% recycled PET content.
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 manufacturing precision and polymer quality deteriorate due to contaminants and lower intrinsic viscosity
Solution Approach 1:
The polymer melt is divided into multiple streams (at least eight streams) within the chamber, with each stream being separately exposed to the reduced pressure environment. This segmentation increases the surface area to volume ratio for each stream, enhancing the efficiency of contaminant and moisture removal while maintaining polymer quality.
Solution Approach 2:
The pressure within the chamber is reduced to below about 5 millibars, creating a vacuum environment that facilitates the removal of contaminants and water from the polymer melt. This parameter change (pressure reduction) directly improves polymer quality by removing harmful substances that would otherwise degrade the intrinsic viscosity and overall quality of the recycled PET.
2Ease of manufacture
If multiple melting and cooling cycles are used in existing processes, then polymer processing is achieved, but energy consumption increases and intrinsic viscosity decreases
Solution Approach 1:
The process maintains the polymer in a melted state continuously through the extrusion and chamber processing steps, avoiding repeated melting and cooling cycles. The polymer melt is extruded, processed in the chamber with reduced pressure, and formed into bulked continuous filament all in one continuous operation, thereby conserving energy and preserving intrinsic viscosity.
3Ease of manufacture
If existing processes are used to process recycled PET, then manufacturing is achieved, but productivity is reduced due to inefficient contaminant removal and multiple processing cycles
Solution Approach 1:
The polymer melt is separated into multiple parallel streams within the chamber, effectively adding a dimensional aspect to the processing. This multi-stream approach increases the total surface area exposed to the reduced pressure environment, accelerating contaminant and moisture removal rates, and thereby improving productivity without compromising polymer quality.
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 enhances the intrinsic viscosity of recycled PET polymer, making it structurally similar to virgin PET, enabling the production of high-quality bulked continuous carpet filament from 100% recycled PET without the need for multiple melting and cooling cycles.
Implementation Method 1
The pressure within the chamber is reduced to reach the chamber pressure below about 5 millibars corresponding to a desired moisture level or intrinsic viscosity associated with a single polymer stream that includes the at least eight streams of the polymer melt
Data Source
AI summary
A method of manufacturing bulked continuous carpet filament that includes providing a polymer melt and separating the polymer melt from the extruder into at least eight streams. The multiple streams are exposed to a chamber pressure within a chamber that is below approximately 25 millibars, or another predetermined pressure. The streams are recombined into a single polymer stream. Polymer from the polymer stream is then formed into bulked continuous carpet filament.